includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Psr\Log\NullLogger;
  31 use Wikimedia\ScopedCallback;
  32 use Wikimedia\Timestamp\ConvertibleTimestamp;
  33 use Wikimedia;
  34 use BagOStuff;
  35 use HashBagOStuff;
  36 use LogicException;
  37 use InvalidArgumentException;
  38 use UnexpectedValueException;
  39 use Exception;
  40 use RuntimeException;
  41
  42 /**
  43  * Relational database abstraction object
  44  *
  45  * @ingroup Database
  46  * @since 1.28
  47  */
  48 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  49         /** Number of times to re-try an operation in case of deadlock */
  50         const DEADLOCK_TRIES = 4;
  51         /** Minimum time to wait before retry, in microseconds */
  52         const DEADLOCK_DELAY_MIN = 500000;
  53         /** Maximum time to wait before retry */
  54         const DEADLOCK_DELAY_MAX = 1500000;
  55
  56         /** How long before it is worth doing a dummy query to test the connection */
  57         const PING_TTL = 1.0;
  58         const PING_QUERY = 'SELECT 1 AS ping';
  59
  60         const TINY_WRITE_SEC = 0.010;
  61         const SLOW_WRITE_SEC = 0.500;
  62         const SMALL_WRITE_ROWS = 100;
  63
  64         /** @var string Whether lock granularity is on the level of the entire database */
  65         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
  66
  67         /** @var int New Database instance will not be connected yet when returned */
  68         const NEW_UNCONNECTED = 0;
  69         /** @var int New Database instance will already be connected when returned */
  70         const NEW_CONNECTED = 1;
  71
  72         /** @var string SQL query */
  73         protected $lastQuery = '';
  74         /** @var float|bool UNIX timestamp of last write query */
  75         protected $lastWriteTime = false;
  76         /** @var string|bool */
  77         protected $phpError = false;
  78         /** @var string Server that this instance is currently connected to */
  79         protected $server;
  80         /** @var string User that this instance is currently connected under the name of */
  81         protected $user;
  82         /** @var string Password used to establish the current connection */
  83         protected $password;
  84         /** @var string Database that this instance is currently connected to */
  85         protected $dbName;
  86         /** @var array[] Map of (table => (dbname, schema, prefix) map) */
  87         protected $tableAliases = [];
  88         /** @var string[] Map of (index alias => index) */
  89         protected $indexAliases = [];
  90         /** @var bool Whether this PHP instance is for a CLI script */
  91         protected $cliMode;
  92         /** @var string Agent name for query profiling */
  93         protected $agent;
  94         /** @var array Parameters used by initConnection() to establish a connection */
  95         protected $connectionParams = [];
  96         /** @var BagOStuff APC cache */
  97         protected $srvCache;
  98         /** @var LoggerInterface */
  99         protected $connLogger;
 100         /** @var LoggerInterface */
 101         protected $queryLogger;
 102         /** @var callback Error logging callback */
 103         protected $errorLogger;
 104         /** @var callback Deprecation logging callback */
 105         protected $deprecationLogger;
 106
 107         /** @var resource|null Database connection */
 108         protected $conn = null;
 109         /** @var bool */
 110         protected $opened = false;
 111
 112         /** @var array[] List of (callable, method name, atomic section id) */
 113         protected $trxIdleCallbacks = [];
 114         /** @var array[] List of (callable, method name, atomic section id) */
 115         protected $trxPreCommitCallbacks = [];
 116         /** @var array[] List of (callable, method name, atomic section id) */
 117         protected $trxEndCallbacks = [];
 118         /** @var callable[] Map of (name => callable) */
 119         protected $trxRecurringCallbacks = [];
 120         /** @var bool Whether to suppress triggering of transaction end callbacks */
 121         protected $trxEndCallbacksSuppressed = false;
 122
 123         /** @var string */
 124         protected $tablePrefix = '';
 125         /** @var string */
 126         protected $schema = '';
 127         /** @var int */
 128         protected $flags;
 129         /** @var array */
 130         protected $lbInfo = [];
 131         /** @var array|bool */
 132         protected $schemaVars = false;
 133         /** @var array */
 134         protected $sessionVars = [];
 135         /** @var array|null */
 136         protected $preparedArgs;
 137         /** @var string|bool|null Stashed value of html_errors INI setting */
 138         protected $htmlErrors;
 139         /** @var string */
 140         protected $delimiter = ';';
 141         /** @var DatabaseDomain */
 142         protected $currentDomain;
 143         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 144         protected $affectedRowCount;
 145
 146         /**
 147          * @var int Transaction status
 148          */
 149         protected $trxStatus = self::STATUS_TRX_NONE;
 150         /**
 151          * @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR
 152          */
 153         protected $trxStatusCause;
 154         /**
 155          * @var array|null If wasKnownStatementRollbackError() prevented trxStatus from being set,
 156          *  the relevant details are stored here.
 157          */
 158         protected $trxStatusIgnoredCause;
 159         /**
 160          * Either 1 if a transaction is active or 0 otherwise.
 161          * The other Trx fields may not be meaningfull if this is 0.
 162          *
 163          * @var int
 164          */
 165         protected $trxLevel = 0;
 166         /**
 167          * Either a short hexidecimal string if a transaction is active or ""
 168          *
 169          * @var string
 170          * @see Database::trxLevel
 171          */
 172         protected $trxShortId = '';
 173         /**
 174          * The UNIX time that the transaction started. Callers can assume that if
 175          * snapshot isolation is used, then the data is *at least* up to date to that
 176          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 177          *
 178          * @var float|null
 179          * @see Database::trxLevel
 180          */
 181         private $trxTimestamp = null;
 182         /** @var float Lag estimate at the time of BEGIN */
 183         private $trxReplicaLag = null;
 184         /**
 185          * Remembers the function name given for starting the most recent transaction via begin().
 186          * Used to provide additional context for error reporting.
 187          *
 188          * @var string
 189          * @see Database::trxLevel
 190          */
 191         private $trxFname = null;
 192         /**
 193          * Record if possible write queries were done in the last transaction started
 194          *
 195          * @var bool
 196          * @see Database::trxLevel
 197          */
 198         private $trxDoneWrites = false;
 199         /**
 200          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 201          *
 202          * @var bool
 203          * @see Database::trxLevel
 204          */
 205         private $trxAutomatic = false;
 206         /**
 207          * Counter for atomic savepoint identifiers. Reset when a new transaction begins.
 208          *
 209          * @var int
 210          */
 211         private $trxAtomicCounter = 0;
 212         /**
 213          * Array of levels of atomicity within transactions
 214          *
 215          * @var array List of (name, unique ID, savepoint ID)
 216          */
 217         private $trxAtomicLevels = [];
 218         /**
 219          * Record if the current transaction was started implicitly by Database::startAtomic
 220          *
 221          * @var bool
 222          */
 223         private $trxAutomaticAtomic = false;
 224         /**
 225          * Track the write query callers of the current transaction
 226          *
 227          * @var string[]
 228          */
 229         private $trxWriteCallers = [];
 230         /**
 231          * @var float Seconds spent in write queries for the current transaction
 232          */
 233         private $trxWriteDuration = 0.0;
 234         /**
 235          * @var int Number of write queries for the current transaction
 236          */
 237         private $trxWriteQueryCount = 0;
 238         /**
 239          * @var int Number of rows affected by write queries for the current transaction
 240          */
 241         private $trxWriteAffectedRows = 0;
 242         /**
 243          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 244          */
 245         private $trxWriteAdjDuration = 0.0;
 246         /**
 247          * @var int Number of write queries counted in trxWriteAdjDuration
 248          */
 249         private $trxWriteAdjQueryCount = 0;
 250         /**
 251          * @var float RTT time estimate
 252          */
 253         private $rttEstimate = 0.0;
 254
 255         /** @var array Map of (name => 1) for locks obtained via lock() */
 256         private $namedLocksHeld = [];
 257         /** @var array Map of (table name => 1) for TEMPORARY tables */
 258         protected $sessionTempTables = [];
 259
 260         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 261         private $lazyMasterHandle;
 262
 263         /** @var float UNIX timestamp */
 264         protected $lastPing = 0.0;
 265
 266         /** @var int[] Prior flags member variable values */
 267         private $priorFlags = [];
 268
 269         /** @var mixed Class name or object With profileIn/profileOut methods */
 270         protected $profiler;
 271         /** @var TransactionProfiler */
 272         protected $trxProfiler;
 273
 274         /** @var int */
 275         protected $nonNativeInsertSelectBatchSize = 10000;
 276
 277         /** @var string Idiom used when a cancelable atomic section started the transaction */
 278         private static $NOT_APPLICABLE = 'n/a';
 279         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 280         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 281
 282         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 283         const STATUS_TRX_ERROR = 1;
 284         /** @var int Transaction is active and in a normal state */
 285         const STATUS_TRX_OK = 2;
 286         /** @var int No transaction is active */
 287         const STATUS_TRX_NONE = 3;
 288
 289         /**
 290          * @note exceptions for missing libraries/drivers should be thrown in initConnection()
 291          * @param array $params Parameters passed from Database::factory()
 292          */
 293         protected function __construct( array $params ) {
 294                 foreach ( [ 'host', 'user', 'password', 'dbname' ] as $name ) {
 295                         $this->connectionParams[$name] = $params[$name];
 296                 }
 297
 298                 $this->schema = $params['schema'];
 299                 $this->tablePrefix = $params['tablePrefix'];
 300
 301                 $this->cliMode = $params['cliMode'];
 302                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 303                 $this->agent = str_replace( '/', '-', $params['agent'] );
 304
 305                 $this->flags = $params['flags'];
 306                 if ( $this->flags & self::DBO_DEFAULT ) {
 307                         if ( $this->cliMode ) {
 308                                 $this->flags &= ~self::DBO_TRX;
 309                         } else {
 310                                 $this->flags |= self::DBO_TRX;
 311                         }
 312                 }
 313                 // Disregard deprecated DBO_IGNORE flag (T189999)
 314                 $this->flags &= ~self::DBO_IGNORE;
 315
 316                 $this->sessionVars = $params['variables'];
 317
 318                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 319
 320                 $this->profiler = $params['profiler'];
 321                 $this->trxProfiler = $params['trxProfiler'];
 322                 $this->connLogger = $params['connLogger'];
 323                 $this->queryLogger = $params['queryLogger'];
 324                 $this->errorLogger = $params['errorLogger'];
 325                 $this->deprecationLogger = $params['deprecationLogger'];
 326
 327                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 328                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 329                 }
 330
 331                 // Set initial dummy domain until open() sets the final DB/prefix
 332                 $this->currentDomain = DatabaseDomain::newUnspecified();
 333         }
 334
 335         /**
 336          * Initialize the connection to the database over the wire (or to local files)
 337          *
 338          * @throws LogicException
 339          * @throws InvalidArgumentException
 340          * @throws DBConnectionError
 341          * @since 1.31
 342          */
 343         final public function initConnection() {
 344                 if ( $this->isOpen() ) {
 345                         throw new LogicException( __METHOD__ . ': already connected.' );
 346                 }
 347                 // Establish the connection
 348                 $this->doInitConnection();
 349                 // Set the domain object after open() sets the relevant fields
 350                 if ( $this->dbName != '' ) {
 351                         // Domains with server scope but a table prefix are not used by IDatabase classes
 352                         $this->currentDomain = new DatabaseDomain( $this->dbName, null, $this->tablePrefix );
 353                 }
 354         }
 355
 356         /**
 357          * Actually connect to the database over the wire (or to local files)
 358          *
 359          * @throws InvalidArgumentException
 360          * @throws DBConnectionError
 361          * @since 1.31
 362          */
 363         protected function doInitConnection() {
 364                 if ( strlen( $this->connectionParams['user'] ) ) {
 365                         $this->open(
 366                                 $this->connectionParams['host'],
 367                                 $this->connectionParams['user'],
 368                                 $this->connectionParams['password'],
 369                                 $this->connectionParams['dbname']
 370                         );
 371                 } else {
 372                         throw new InvalidArgumentException( "No database user provided." );
 373                 }
 374         }
 375
 376         /**
 377          * Open a new connection to the database (closing any existing one)
 378          *
 379          * @param string $server Database server host
 380          * @param string $user Database user name
 381          * @param string $password Database user password
 382          * @param string $dbName Database name
 383          * @return bool
 384          * @throws DBConnectionError
 385          */
 386         abstract protected function open( $server, $user, $password, $dbName );
 387
 388         /**
 389          * Construct a Database subclass instance given a database type and parameters
 390          *
 391          * This also connects to the database immediately upon object construction
 392          *
 393          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 394          * @param array $p Parameter map with keys:
 395          *   - host : The hostname of the DB server
 396          *   - user : The name of the database user the client operates under
 397          *   - password : The password for the database user
 398          *   - dbname : The name of the database to use where queries do not specify one.
 399          *      The database must exist or an error might be thrown. Setting this to the empty string
 400          *      will avoid any such errors and make the handle have no implicit database scope. This is
 401          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 402          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 403          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 404          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 405          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 406          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 407          *      recognized in queries. This can be used in place of schemas for handle site farms.
 408          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 409          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 410          *      flag in place UNLESS this this database simply acts as a key/value store.
 411          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 412          *      'mysqli' driver; the old one 'mysql' has been removed.
 413          *   - variables: Optional map of session variables to set after connecting. This can be
 414          *      used to adjust lock timeouts or encoding modes and the like.
 415          *   - connLogger: Optional PSR-3 logger interface instance.
 416          *   - queryLogger: Optional PSR-3 logger interface instance.
 417          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 418          *      These will be called in query(), using a simplified version of the SQL that also
 419          *      includes the agent as a SQL comment.
 420          *   - trxProfiler: Optional TransactionProfiler instance.
 421          *   - errorLogger: Optional callback that takes an Exception and logs it.
 422          *   - deprecationLogger: Optional callback that takes a string and logs it.
 423          *   - cliMode: Whether to consider the execution context that of a CLI script.
 424          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 425          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 426          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 427          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 428          * @return Database|null If the database driver or extension cannot be found
 429          * @throws InvalidArgumentException If the database driver or extension cannot be found
 430          * @since 1.18
 431          */
 432         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 433                 $class = self::getClass( $dbType, $p['driver'] ?? null );
 434
 435                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 436                         // Resolve some defaults for b/c
 437                         $p['host'] = $p['host'] ?? false;
 438                         $p['user'] = $p['user'] ?? false;
 439                         $p['password'] = $p['password'] ?? false;
 440                         $p['dbname'] = $p['dbname'] ?? false;
 441                         $p['flags'] = $p['flags'] ?? 0;
 442                         $p['variables'] = $p['variables'] ?? [];
 443                         $p['tablePrefix'] = $p['tablePrefix'] ?? '';
 444                         $p['schema'] = $p['schema'] ?? '';
 445                         $p['cliMode'] = $p['cliMode'] ?? ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 446                         $p['agent'] = $p['agent'] ?? '';
 447                         if ( !isset( $p['connLogger'] ) ) {
 448                                 $p['connLogger'] = new NullLogger();
 449                         }
 450                         if ( !isset( $p['queryLogger'] ) ) {
 451                                 $p['queryLogger'] = new NullLogger();
 452                         }
 453                         $p['profiler'] = $p['profiler'] ?? null;
 454                         if ( !isset( $p['trxProfiler'] ) ) {
 455                                 $p['trxProfiler'] = new TransactionProfiler();
 456                         }
 457                         if ( !isset( $p['errorLogger'] ) ) {
 458                                 $p['errorLogger'] = function ( Exception $e ) {
 459                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 460                                 };
 461                         }
 462                         if ( !isset( $p['deprecationLogger'] ) ) {
 463                                 $p['deprecationLogger'] = function ( $msg ) {
 464                                         trigger_error( $msg, E_USER_DEPRECATED );
 465                                 };
 466                         }
 467
 468                         /** @var Database $conn */
 469                         $conn = new $class( $p );
 470                         if ( $connect == self::NEW_CONNECTED ) {
 471                                 $conn->initConnection();
 472                         }
 473                 } else {
 474                         $conn = null;
 475                 }
 476
 477                 return $conn;
 478         }
 479
 480         /**
 481          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 482          * @param string|null $driver Optional name of a specific DB client driver
 483          * @return array Map of (Database::ATTRIBUTE_* constant => value) for all such constants
 484          * @throws InvalidArgumentException
 485          * @since 1.31
 486          */
 487         final public static function attributesFromType( $dbType, $driver = null ) {
 488                 static $defaults = [ self::ATTR_DB_LEVEL_LOCKING => false ];
 489
 490                 $class = self::getClass( $dbType, $driver );
 491
 492                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 493         }
 494
 495         /**
 496          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 497          * @param string|null $driver Optional name of a specific DB client driver
 498          * @return string Database subclass name to use
 499          * @throws InvalidArgumentException
 500          */
 501         private static function getClass( $dbType, $driver = null ) {
 502                 // For database types with built-in support, the below maps type to IDatabase
 503                 // implementations. For types with multipe driver implementations (PHP extensions),
 504                 // an array can be used, keyed by extension name. In case of an array, the
 505                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 506                 // we auto-detect the first available driver. For types without built-in support,
 507                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 508                 static $builtinTypes = [
 509                         'mssql' => DatabaseMssql::class,
 510                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 511                         'sqlite' => DatabaseSqlite::class,
 512                         'postgres' => DatabasePostgres::class,
 513                 ];
 514
 515                 $dbType = strtolower( $dbType );
 516                 $class = false;
 517
 518                 if ( isset( $builtinTypes[$dbType] ) ) {
 519                         $possibleDrivers = $builtinTypes[$dbType];
 520                         if ( is_string( $possibleDrivers ) ) {
 521                                 $class = $possibleDrivers;
 522                         } else {
 523                                 if ( (string)$driver !== '' ) {
 524                                         if ( !isset( $possibleDrivers[$driver] ) ) {
 525                                                 throw new InvalidArgumentException( __METHOD__ .
 526                                                         " type '$dbType' does not support driver '{$driver}'" );
 527                                         } else {
 528                                                 $class = $possibleDrivers[$driver];
 529                                         }
 530                                 } else {
 531                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 532                                                 if ( extension_loaded( $posDriver ) ) {
 533                                                         $class = $possibleClass;
 534                                                         break;
 535                                                 }
 536                                         }
 537                                 }
 538                         }
 539                 } else {
 540                         $class = 'Database' . ucfirst( $dbType );
 541                 }
 542
 543                 if ( $class === false ) {
 544                         throw new InvalidArgumentException( __METHOD__ .
 545                                 " no viable database extension found for type '$dbType'" );
 546                 }
 547
 548                 return $class;
 549         }
 550
 551         /**
 552          * @return array Map of (Database::ATTRIBUTE_* constant => value
 553          * @since 1.31
 554          */
 555         protected static function getAttributes() {
 556                 return [];
 557         }
 558
 559         /**
 560          * Set the PSR-3 logger interface to use for query logging. (The logger
 561          * interfaces for connection logging and error logging can be set with the
 562          * constructor.)
 563          *
 564          * @param LoggerInterface $logger
 565          */
 566         public function setLogger( LoggerInterface $logger ) {
 567                 $this->queryLogger = $logger;
 568         }
 569
 570         public function getServerInfo() {
 571                 return $this->getServerVersion();
 572         }
 573
 574         public function bufferResults( $buffer = null ) {
 575                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 576                 if ( $buffer !== null ) {
 577                         $buffer
 578                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 579                                 : $this->setFlag( self::DBO_NOBUFFER );
 580                 }
 581
 582                 return $res;
 583         }
 584
 585         public function trxLevel() {
 586                 return $this->trxLevel;
 587         }
 588
 589         public function trxTimestamp() {
 590                 return $this->trxLevel ? $this->trxTimestamp : null;
 591         }
 592
 593         /**
 594          * @return int One of the STATUS_TRX_* class constants
 595          * @since 1.31
 596          */
 597         public function trxStatus() {
 598                 return $this->trxStatus;
 599         }
 600
 601         public function tablePrefix( $prefix = null ) {
 602                 $old = $this->tablePrefix;
 603                 if ( $prefix !== null ) {
 604                         $this->tablePrefix = $prefix;
 605                         $this->currentDomain = ( $this->dbName != '' )
 606                                 ? new DatabaseDomain( $this->dbName, null, $this->tablePrefix )
 607                                 : DatabaseDomain::newUnspecified();
 608                 }
 609
 610                 return $old;
 611         }
 612
 613         public function dbSchema( $schema = null ) {
 614                 $old = $this->schema;
 615                 if ( $schema !== null ) {
 616                         $this->schema = $schema;
 617                 }
 618
 619                 return $old;
 620         }
 621
 622         public function getLBInfo( $name = null ) {
 623                 if ( is_null( $name ) ) {
 624                         return $this->lbInfo;
 625                 } else {
 626                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 627                                 return $this->lbInfo[$name];
 628                         } else {
 629                                 return null;
 630                         }
 631                 }
 632         }
 633
 634         public function setLBInfo( $name, $value = null ) {
 635                 if ( is_null( $value ) ) {
 636                         $this->lbInfo = $name;
 637                 } else {
 638                         $this->lbInfo[$name] = $value;
 639                 }
 640         }
 641
 642         public function setLazyMasterHandle( IDatabase $conn ) {
 643                 $this->lazyMasterHandle = $conn;
 644         }
 645
 646         /**
 647          * @return IDatabase|null
 648          * @see setLazyMasterHandle()
 649          * @since 1.27
 650          */
 651         protected function getLazyMasterHandle() {
 652                 return $this->lazyMasterHandle;
 653         }
 654
 655         public function implicitGroupby() {
 656                 return true;
 657         }
 658
 659         public function implicitOrderby() {
 660                 return true;
 661         }
 662
 663         public function lastQuery() {
 664                 return $this->lastQuery;
 665         }
 666
 667         public function doneWrites() {
 668                 return (bool)$this->lastWriteTime;
 669         }
 670
 671         public function lastDoneWrites() {
 672                 return $this->lastWriteTime ?: false;
 673         }
 674
 675         public function writesPending() {
 676                 return $this->trxLevel && $this->trxDoneWrites;
 677         }
 678
 679         public function writesOrCallbacksPending() {
 680                 return $this->trxLevel && (
 681                         $this->trxDoneWrites ||
 682                         $this->trxIdleCallbacks ||
 683                         $this->trxPreCommitCallbacks ||
 684                         $this->trxEndCallbacks
 685                 );
 686         }
 687
 688         public function preCommitCallbacksPending() {
 689                 return $this->trxLevel && $this->trxPreCommitCallbacks;
 690         }
 691
 692         /**
 693          * @return string|null
 694          */
 695         final protected function getTransactionRoundId() {
 696                 // If transaction round participation is enabled, see if one is active
 697                 if ( $this->getFlag( self::DBO_TRX ) ) {
 698                         $id = $this->getLBInfo( 'trxRoundId' );
 699
 700                         return is_string( $id ) ? $id : null;
 701                 }
 702
 703                 return null;
 704         }
 705
 706         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 707                 if ( !$this->trxLevel ) {
 708                         return false;
 709                 } elseif ( !$this->trxDoneWrites ) {
 710                         return 0.0;
 711                 }
 712
 713                 switch ( $type ) {
 714                         case self::ESTIMATE_DB_APPLY:
 715                                 $this->ping( $rtt );
 716                                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 717                                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 718                                 // For omitted queries, make them count as something at least
 719                                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 720                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 721
 722                                 return $applyTime;
 723                         default: // everything
 724                                 return $this->trxWriteDuration;
 725                 }
 726         }
 727
 728         public function pendingWriteCallers() {
 729                 return $this->trxLevel ? $this->trxWriteCallers : [];
 730         }
 731
 732         public function pendingWriteRowsAffected() {
 733                 return $this->trxWriteAffectedRows;
 734         }
 735
 736         /**
 737          * List the methods that have write queries or callbacks for the current transaction
 738          *
 739          * This method should not be used outside of Database/LoadBalancer
 740          *
 741          * @return string[]
 742          * @since 1.32
 743          */
 744         public function pendingWriteAndCallbackCallers() {
 745                 $fnames = $this->pendingWriteCallers();
 746                 foreach ( [
 747                         $this->trxIdleCallbacks,
 748                         $this->trxPreCommitCallbacks,
 749                         $this->trxEndCallbacks
 750                 ] as $callbacks ) {
 751                         foreach ( $callbacks as $callback ) {
 752                                 $fnames[] = $callback[1];
 753                         }
 754                 }
 755
 756                 return $fnames;
 757         }
 758
 759         /**
 760          * @return string
 761          */
 762         private function flatAtomicSectionList() {
 763                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 764                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 765                 } );
 766         }
 767
 768         public function isOpen() {
 769                 return $this->opened;
 770         }
 771
 772         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 773                 if ( ( $flag & self::DBO_IGNORE ) ) {
 774                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 775                 }
 776
 777                 if ( $remember === self::REMEMBER_PRIOR ) {
 778                         array_push( $this->priorFlags, $this->flags );
 779                 }
 780                 $this->flags |= $flag;
 781         }
 782
 783         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 784                 if ( ( $flag & self::DBO_IGNORE ) ) {
 785                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 786                 }
 787
 788                 if ( $remember === self::REMEMBER_PRIOR ) {
 789                         array_push( $this->priorFlags, $this->flags );
 790                 }
 791                 $this->flags &= ~$flag;
 792         }
 793
 794         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 795                 if ( !$this->priorFlags ) {
 796                         return;
 797                 }
 798
 799                 if ( $state === self::RESTORE_INITIAL ) {
 800                         $this->flags = reset( $this->priorFlags );
 801                         $this->priorFlags = [];
 802                 } else {
 803                         $this->flags = array_pop( $this->priorFlags );
 804                 }
 805         }
 806
 807         public function getFlag( $flag ) {
 808                 return !!( $this->flags & $flag );
 809         }
 810
 811         /**
 812          * @param string $name Class field name
 813          * @return mixed
 814          * @deprecated Since 1.28
 815          */
 816         public function getProperty( $name ) {
 817                 return $this->$name;
 818         }
 819
 820         public function getDomainID() {
 821                 return $this->currentDomain->getId();
 822         }
 823
 824         final public function getWikiID() {
 825                 return $this->getDomainID();
 826         }
 827
 828         /**
 829          * Get information about an index into an object
 830          * @param string $table Table name
 831          * @param string $index Index name
 832          * @param string $fname Calling function name
 833          * @return mixed Database-specific index description class or false if the index does not exist
 834          */
 835         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 836
 837         /**
 838          * Wrapper for addslashes()
 839          *
 840          * @param string $s String to be slashed.
 841          * @return string Slashed string.
 842          */
 843         abstract function strencode( $s );
 844
 845         /**
 846          * Set a custom error handler for logging errors during database connection
 847          */
 848         protected function installErrorHandler() {
 849                 $this->phpError = false;
 850                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 851                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 852         }
 853
 854         /**
 855          * Restore the previous error handler and return the last PHP error for this DB
 856          *
 857          * @return bool|string
 858          */
 859         protected function restoreErrorHandler() {
 860                 restore_error_handler();
 861                 if ( $this->htmlErrors !== false ) {
 862                         ini_set( 'html_errors', $this->htmlErrors );
 863                 }
 864
 865                 return $this->getLastPHPError();
 866         }
 867
 868         /**
 869          * @return string|bool Last PHP error for this DB (typically connection errors)
 870          */
 871         protected function getLastPHPError() {
 872                 if ( $this->phpError ) {
 873                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 874                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 875
 876                         return $error;
 877                 }
 878
 879                 return false;
 880         }
 881
 882         /**
 883          * Error handler for logging errors during database connection
 884          * This method should not be used outside of Database classes
 885          *
 886          * @param int $errno
 887          * @param string $errstr
 888          */
 889         public function connectionErrorLogger( $errno, $errstr ) {
 890                 $this->phpError = $errstr;
 891         }
 892
 893         /**
 894          * Create a log context to pass to PSR-3 logger functions.
 895          *
 896          * @param array $extras Additional data to add to context
 897          * @return array
 898          */
 899         protected function getLogContext( array $extras = [] ) {
 900                 return array_merge(
 901                         [
 902                                 'db_server' => $this->server,
 903                                 'db_name' => $this->dbName,
 904                                 'db_user' => $this->user,
 905                         ],
 906                         $extras
 907                 );
 908         }
 909
 910         final public function close() {
 911                 $exception = null; // error to throw after disconnecting
 912
 913                 if ( $this->conn ) {
 914                         // Roll back any dangling transaction first
 915                         if ( $this->trxLevel ) {
 916                                 if ( $this->trxAtomicLevels ) {
 917                                         // Cannot let incomplete atomic sections be committed
 918                                         $levels = $this->flatAtomicSectionList();
 919                                         $exception = new DBUnexpectedError(
 920                                                 $this,
 921                                                 __METHOD__ . ": atomic sections $levels are still open."
 922                                         );
 923                                 } elseif ( $this->trxAutomatic ) {
 924                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 925                                         // (empty ones we can silently roll back)
 926                                         if ( $this->writesOrCallbacksPending() ) {
 927                                                 $exception = new DBUnexpectedError(
 928                                                         $this,
 929                                                         __METHOD__ .
 930                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)."
 931                                                 );
 932                                         }
 933                                 } else {
 934                                         // Manual transactions should have been committed or rolled
 935                                         // back, even if empty.
 936                                         $exception = new DBUnexpectedError(
 937                                                 $this,
 938                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})."
 939                                         );
 940                                 }
 941
 942                                 if ( $this->trxEndCallbacksSuppressed ) {
 943                                         $exception = $exception ?: new DBUnexpectedError(
 944                                                 $this,
 945                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 946                                         );
 947                                 }
 948
 949                                 // Rollback the changes and run any callbacks as needed
 950                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 951                         }
 952
 953                         // Close the actual connection in the binding handle
 954                         $closed = $this->closeConnection();
 955                         $this->conn = false;
 956                 } else {
 957                         $closed = true; // already closed; nothing to do
 958                 }
 959
 960                 $this->opened = false;
 961
 962                 // Throw any unexpected errors after having disconnected
 963                 if ( $exception instanceof Exception ) {
 964                         throw $exception;
 965                 }
 966
 967                 // Sanity check that no callbacks are dangling
 968                 $fnames = $this->pendingWriteAndCallbackCallers();
 969                 if ( $fnames ) {
 970                         throw new RuntimeException(
 971                                 "Transaction callbacks are still pending:\n" . implode( ', ', $fnames )
 972                         );
 973                 }
 974
 975                 return $closed;
 976         }
 977
 978         /**
 979          * Make sure isOpen() returns true as a sanity check
 980          *
 981          * @throws DBUnexpectedError
 982          */
 983         protected function assertOpen() {
 984                 if ( !$this->isOpen() ) {
 985                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 986                 }
 987         }
 988
 989         /**
 990          * Closes underlying database connection
 991          * @since 1.20
 992          * @return bool Whether connection was closed successfully
 993          */
 994         abstract protected function closeConnection();
 995
 996         /**
 997          * @deprecated since 1.32
 998          * @param string $error Fallback message, if none is given by DB
 999          * @throws DBConnectionError
1000          */
1001         public function reportConnectionError( $error = 'Unknown error' ) {
1002                 call_user_func( $this->deprecationLogger, 'Use of ' . __METHOD__ . ' is deprecated.' );
1003                 throw new DBConnectionError( $this, $this->lastError() ?: $error );
1004         }
1005
1006         /**
1007          * Run a query and return a DBMS-dependent wrapper (that has all IResultWrapper methods)
1008          *
1009          * This might return things, such as mysqli_result, that do not formally implement
1010          * IResultWrapper, but nonetheless implement all of its methods correctly
1011          *
1012          * @param string $sql SQL query.
1013          * @return IResultWrapper|bool Iterator to feed to fetchObject/fetchRow; false on failure
1014          */
1015         abstract protected function doQuery( $sql );
1016
1017         /**
1018          * Determine whether a query writes to the DB. When in doubt, this returns true.
1019          *
1020          * Main use cases:
1021          *
1022          * - Subsequent web requests should not need to wait for replication from
1023          *   the master position seen by this web request, unless this request made
1024          *   changes to the master. This is handled by ChronologyProtector by checking
1025          *   doneWrites() at the end of the request. doneWrites() returns true if any
1026          *   query set lastWriteTime; which query() does based on isWriteQuery().
1027          *
1028          * - Reject write queries to replica DBs, in query().
1029          *
1030          * @param string $sql
1031          * @return bool
1032          */
1033         protected function isWriteQuery( $sql ) {
1034                 // BEGIN and COMMIT queries are considered read queries here.
1035                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1036                 // treat these as write queries, in that their results have "affected rows"
1037                 // as meta data as from writes, instead of "num rows" as from reads.
1038                 // But, we treat them as read queries because when reading data (from
1039                 // either replica or master) we use transactions to enable repeatable-read
1040                 // snapshots, which ensures we get consistent results from the same snapshot
1041                 // for all queries within a request. Use cases:
1042                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1043                 // - We use this method to reject writes to replicas, but we need to allow
1044                 //   use of transactions on replicas for read snapshots. This fine given
1045                 //   that transactions by themselves don't make changes, only actual writes
1046                 //   within the transaction matter, which we still detect.
1047                 return !preg_match(
1048                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
1049         }
1050
1051         /**
1052          * @param string $sql
1053          * @return string|null
1054          */
1055         protected function getQueryVerb( $sql ) {
1056                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1057         }
1058
1059         /**
1060          * Determine whether a SQL statement is sensitive to isolation level.
1061          *
1062          * A SQL statement is considered transactable if its result could vary
1063          * depending on the transaction isolation level. Operational commands
1064          * such as 'SET' and 'SHOW' are not considered to be transactable.
1065          *
1066          * Main purpose: Used by query() to decide whether to begin a transaction
1067          * before the current query (in DBO_TRX mode, on by default).
1068          *
1069          * @param string $sql
1070          * @return bool
1071          */
1072         protected function isTransactableQuery( $sql ) {
1073                 return !in_array(
1074                         $this->getQueryVerb( $sql ),
1075                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER' ],
1076                         true
1077                 );
1078         }
1079
1080         /**
1081          * @param string $sql A SQL query
1082          * @return bool Whether $sql is SQL for TEMPORARY table operation
1083          */
1084         protected function registerTempTableOperation( $sql ) {
1085                 if ( preg_match(
1086                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1087                         $sql,
1088                         $matches
1089                 ) ) {
1090                         $this->sessionTempTables[$matches[1]] = 1;
1091
1092                         return true;
1093                 } elseif ( preg_match(
1094                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1095                         $sql,
1096                         $matches
1097                 ) ) {
1098                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
1099                         unset( $this->sessionTempTables[$matches[1]] );
1100
1101                         return $isTemp;
1102                 } elseif ( preg_match(
1103                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1104                         $sql,
1105                         $matches
1106                 ) ) {
1107                         return isset( $this->sessionTempTables[$matches[1]] );
1108                 } elseif ( preg_match(
1109                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
1110                         $sql,
1111                         $matches
1112                 ) ) {
1113                         return isset( $this->sessionTempTables[$matches[1]] );
1114                 }
1115
1116                 return false;
1117         }
1118
1119         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1120                 $this->assertTransactionStatus( $sql, $fname );
1121
1122                 # Avoid fatals if close() was called
1123                 $this->assertOpen();
1124
1125                 $priorWritesPending = $this->writesOrCallbacksPending();
1126                 $this->lastQuery = $sql;
1127
1128                 $isWrite = $this->isWriteQuery( $sql );
1129                 if ( $isWrite ) {
1130                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
1131                 } else {
1132                         $isNonTempWrite = false;
1133                 }
1134
1135                 if ( $isWrite ) {
1136                         if ( $this->getLBInfo( 'replica' ) === true ) {
1137                                 throw new DBError(
1138                                         $this,
1139                                         'Write operations are not allowed on replica database connections.'
1140                                 );
1141                         }
1142                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1143                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1144                         $reason = $this->getReadOnlyReason();
1145                         if ( $reason !== false ) {
1146                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
1147                         }
1148                         # Set a flag indicating that writes have been done
1149                         $this->lastWriteTime = microtime( true );
1150                 }
1151
1152                 # Add trace comment to the begin of the sql string, right after the operator.
1153                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1154                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1155
1156                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
1157                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
1158                         && $this->isTransactableQuery( $sql )
1159                 ) {
1160                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1161                         $this->trxAutomatic = true;
1162                 }
1163
1164                 # Keep track of whether the transaction has write queries pending
1165                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
1166                         $this->trxDoneWrites = true;
1167                         $this->trxProfiler->transactionWritingIn(
1168                                 $this->server, $this->getDomainID(), $this->trxShortId );
1169                 }
1170
1171                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1172                         $this->queryLogger->debug( "{$this->getDomainID()} {$commentedSql}" );
1173                 }
1174
1175                 # Send the query to the server and fetch any corresponding errors
1176                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1177                 $lastError = $this->lastError();
1178                 $lastErrno = $this->lastErrno();
1179
1180                 # Try reconnecting if the connection was lost
1181                 if ( $ret === false && $this->wasConnectionLoss() ) {
1182                         # Check if any meaningful session state was lost
1183                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1184                         # Update session state tracking and try to restore the connection
1185                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1186                         # Silently resend the query to the server if it is safe and possible
1187                         if ( $reconnected && $recoverable ) {
1188                                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1189                                 $lastError = $this->lastError();
1190                                 $lastErrno = $this->lastErrno();
1191
1192                                 if ( $ret === false && $this->wasConnectionLoss() ) {
1193                                         # Query probably causes disconnects; reconnect and do not re-run it
1194                                         $this->replaceLostConnection( __METHOD__ );
1195                                 }
1196                         }
1197                 }
1198
1199                 if ( $ret === false ) {
1200                         if ( $this->trxLevel ) {
1201                                 if ( $this->wasKnownStatementRollbackError() ) {
1202                                         # We're ignoring an error that caused just the current query to be aborted.
1203                                         # But log the cause so we can log a deprecation notice if a caller actually
1204                                         # does ignore it.
1205                                         $this->trxStatusIgnoredCause = [ $lastError, $lastErrno, $fname ];
1206                                 } else {
1207                                         # Either the query was aborted or all queries after BEGIN where aborted.
1208                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1209                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1210                                         # option is ROLLBACK, since the snapshots would have been released.
1211                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1212                                         $this->trxStatusCause =
1213                                                 $this->makeQueryException( $lastError, $lastErrno, $sql, $fname );
1214                                         $tempIgnore = false; // cannot recover
1215                                         $this->trxStatusIgnoredCause = null;
1216                                 }
1217                         }
1218
1219                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1220                 }
1221
1222                 return $this->resultObject( $ret );
1223         }
1224
1225         /**
1226          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1227          *
1228          * @param string $sql Original SQL query
1229          * @param string $commentedSql SQL query with debugging/trace comment
1230          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1231          * @param string $fname Name of the calling function
1232          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1233          *     object for a successful read query, or false on failure
1234          */
1235         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1236                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1237                 # generalizeSQL() will probably cut down the query to reasonable
1238                 # logging size most of the time. The substr is really just a sanity check.
1239                 if ( $isMaster ) {
1240                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1241                 } else {
1242                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1243                 }
1244
1245                 # Include query transaction state
1246                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1247
1248                 $startTime = microtime( true );
1249                 if ( $this->profiler ) {
1250                         $this->profiler->profileIn( $queryProf );
1251                 }
1252                 $this->affectedRowCount = null;
1253                 $ret = $this->doQuery( $commentedSql );
1254                 $this->affectedRowCount = $this->affectedRows();
1255                 if ( $this->profiler ) {
1256                         $this->profiler->profileOut( $queryProf );
1257                 }
1258                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1259
1260                 unset( $queryProfSection ); // profile out (if set)
1261
1262                 if ( $ret !== false ) {
1263                         $this->lastPing = $startTime;
1264                         if ( $isWrite && $this->trxLevel ) {
1265                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1266                                 $this->trxWriteCallers[] = $fname;
1267                         }
1268                 }
1269
1270                 if ( $sql === self::PING_QUERY ) {
1271                         $this->rttEstimate = $queryRuntime;
1272                 }
1273
1274                 $this->trxProfiler->recordQueryCompletion(
1275                         $queryProf,
1276                         $startTime,
1277                         $isWrite,
1278                         $isWrite ? $this->affectedRows() : $this->numRows( $ret )
1279                 );
1280                 $this->queryLogger->debug( $sql, [
1281                         'method' => $fname,
1282                         'master' => $isMaster,
1283                         'runtime' => $queryRuntime,
1284                 ] );
1285
1286                 return $ret;
1287         }
1288
1289         /**
1290          * Update the estimated run-time of a query, not counting large row lock times
1291          *
1292          * LoadBalancer can be set to rollback transactions that will create huge replication
1293          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1294          * queries, like inserting a row can take a long time due to row locking. This method
1295          * uses some simple heuristics to discount those cases.
1296          *
1297          * @param string $sql A SQL write query
1298          * @param float $runtime Total runtime, including RTT
1299          * @param int $affected Affected row count
1300          */
1301         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1302                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1303                 $indicativeOfReplicaRuntime = true;
1304                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1305                         $verb = $this->getQueryVerb( $sql );
1306                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1307                         if ( $verb === 'INSERT' ) {
1308                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1309                         } elseif ( $verb === 'REPLACE' ) {
1310                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1311                         }
1312                 }
1313
1314                 $this->trxWriteDuration += $runtime;
1315                 $this->trxWriteQueryCount += 1;
1316                 $this->trxWriteAffectedRows += $affected;
1317                 if ( $indicativeOfReplicaRuntime ) {
1318                         $this->trxWriteAdjDuration += $runtime;
1319                         $this->trxWriteAdjQueryCount += 1;
1320                 }
1321         }
1322
1323         /**
1324          * @param string $sql
1325          * @param string $fname
1326          * @throws DBTransactionStateError
1327          */
1328         private function assertTransactionStatus( $sql, $fname ) {
1329                 if ( $this->getQueryVerb( $sql ) === 'ROLLBACK' ) { // transaction/savepoint
1330                         return;
1331                 }
1332
1333                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1334                         throw new DBTransactionStateError(
1335                                 $this,
1336                                 "Cannot execute query from $fname while transaction status is ERROR.",
1337                                 [],
1338                                 $this->trxStatusCause
1339                         );
1340                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1341                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1342                         call_user_func( $this->deprecationLogger,
1343                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1344                                 "[$iLastErrno] $iLastError"
1345                         );
1346                         $this->trxStatusIgnoredCause = null;
1347                 }
1348         }
1349
1350         public function assertNoOpenTransactions() {
1351                 if ( $this->explicitTrxActive() ) {
1352                         throw new DBTransactionError(
1353                                 $this,
1354                                 "Explicit transaction still active. A caller may have caught an error. "
1355                                 . "Open transactions: " . $this->flatAtomicSectionList()
1356                         );
1357                 }
1358         }
1359
1360         /**
1361          * Determine whether or not it is safe to retry queries after a database
1362          * connection is lost
1363          *
1364          * @param string $sql SQL query
1365          * @param bool $priorWritesPending Whether there is a transaction open with
1366          *     possible write queries or transaction pre-commit/idle callbacks
1367          *     waiting on it to finish.
1368          * @return bool True if it is safe to retry the query, false otherwise
1369          */
1370         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1371                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1372                 # Dropped connections also mean that named locks are automatically released.
1373                 # Only allow error suppression in autocommit mode or when the lost transaction
1374                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1375                 if ( $this->namedLocksHeld ) {
1376                         return false; // possible critical section violation
1377                 } elseif ( $this->sessionTempTables ) {
1378                         return false; // tables might be queried latter
1379                 } elseif ( $sql === 'COMMIT' ) {
1380                         return !$priorWritesPending; // nothing written anyway? (T127428)
1381                 } elseif ( $sql === 'ROLLBACK' ) {
1382                         return true; // transaction lost...which is also what was requested :)
1383                 } elseif ( $this->explicitTrxActive() ) {
1384                         return false; // don't drop atomocity and explicit snapshots
1385                 } elseif ( $priorWritesPending ) {
1386                         return false; // prior writes lost from implicit transaction
1387                 }
1388
1389                 return true;
1390         }
1391
1392         /**
1393          * Clean things up after session (and thus transaction) loss
1394          */
1395         private function handleSessionLoss() {
1396                 // Clean up tracking of session-level things...
1397                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1398                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1399                 $this->sessionTempTables = [];
1400                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1401                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1402                 $this->namedLocksHeld = [];
1403                 // Session loss implies transaction loss
1404                 $this->handleTransactionLoss();
1405         }
1406
1407         /**
1408          * Clean things up after transaction loss
1409          */
1410         private function handleTransactionLoss() {
1411                 $this->trxLevel = 0;
1412                 $this->trxAtomicCounter = 0;
1413                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1414                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1415                 try {
1416                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1417                         // If callback suppression is set then the array will remain unhandled.
1418                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1419                 } catch ( Exception $ex ) {
1420                         // Already logged; move on...
1421                 }
1422                 try {
1423                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1424                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1425                 } catch ( Exception $ex ) {
1426                         // Already logged; move on...
1427                 }
1428         }
1429
1430         /**
1431          * Checks whether the cause of the error is detected to be a timeout.
1432          *
1433          * It returns false by default, and not all engines support detecting this yet.
1434          * If this returns false, it will be treated as a generic query error.
1435          *
1436          * @param string $error Error text
1437          * @param int $errno Error number
1438          * @return bool
1439          */
1440         protected function wasQueryTimeout( $error, $errno ) {
1441                 return false;
1442         }
1443
1444         /**
1445          * Report a query error. Log the error, and if neither the object ignore
1446          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1447          *
1448          * @param string $error
1449          * @param int $errno
1450          * @param string $sql
1451          * @param string $fname
1452          * @param bool $tempIgnore
1453          * @throws DBQueryError
1454          */
1455         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1456                 if ( $tempIgnore ) {
1457                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1458                 } else {
1459                         $exception = $this->makeQueryException( $error, $errno, $sql, $fname );
1460
1461                         throw $exception;
1462                 }
1463         }
1464
1465         /**
1466          * @param string $error
1467          * @param string|int $errno
1468          * @param string $sql
1469          * @param string $fname
1470          * @return DBError
1471          */
1472         private function makeQueryException( $error, $errno, $sql, $fname ) {
1473                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1474                 $this->queryLogger->error(
1475                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1476                         $this->getLogContext( [
1477                                 'method' => __METHOD__,
1478                                 'errno' => $errno,
1479                                 'error' => $error,
1480                                 'sql1line' => $sql1line,
1481                                 'fname' => $fname,
1482                         ] )
1483                 );
1484                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1485                 $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1486                 if ( $wasQueryTimeout ) {
1487                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1488                 } else {
1489                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1490                 }
1491
1492                 return $e;
1493         }
1494
1495         public function freeResult( $res ) {
1496         }
1497
1498         public function selectField(
1499                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1500         ) {
1501                 if ( $var === '*' ) { // sanity
1502                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1503                 }
1504
1505                 if ( !is_array( $options ) ) {
1506                         $options = [ $options ];
1507                 }
1508
1509                 $options['LIMIT'] = 1;
1510
1511                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1512                 if ( $res === false || !$this->numRows( $res ) ) {
1513                         return false;
1514                 }
1515
1516                 $row = $this->fetchRow( $res );
1517
1518                 if ( $row !== false ) {
1519                         return reset( $row );
1520                 } else {
1521                         return false;
1522                 }
1523         }
1524
1525         public function selectFieldValues(
1526                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1527         ) {
1528                 if ( $var === '*' ) { // sanity
1529                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1530                 } elseif ( !is_string( $var ) ) { // sanity
1531                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1532                 }
1533
1534                 if ( !is_array( $options ) ) {
1535                         $options = [ $options ];
1536                 }
1537
1538                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1539                 if ( $res === false ) {
1540                         return false;
1541                 }
1542
1543                 $values = [];
1544                 foreach ( $res as $row ) {
1545                         $values[] = $row->$var;
1546                 }
1547
1548                 return $values;
1549         }
1550
1551         /**
1552          * Returns an optional USE INDEX clause to go after the table, and a
1553          * string to go at the end of the query.
1554          *
1555          * @param array $options Associative array of options to be turned into
1556          *   an SQL query, valid keys are listed in the function.
1557          * @return array
1558          * @see Database::select()
1559          */
1560         protected function makeSelectOptions( $options ) {
1561                 $preLimitTail = $postLimitTail = '';
1562                 $startOpts = '';
1563
1564                 $noKeyOptions = [];
1565
1566                 foreach ( $options as $key => $option ) {
1567                         if ( is_numeric( $key ) ) {
1568                                 $noKeyOptions[$option] = true;
1569                         }
1570                 }
1571
1572                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1573
1574                 $preLimitTail .= $this->makeOrderBy( $options );
1575
1576                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1577                         $postLimitTail .= ' FOR UPDATE';
1578                 }
1579
1580                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1581                         $postLimitTail .= ' LOCK IN SHARE MODE';
1582                 }
1583
1584                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1585                         $startOpts .= 'DISTINCT';
1586                 }
1587
1588                 # Various MySQL extensions
1589                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1590                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1591                 }
1592
1593                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1594                         $startOpts .= ' HIGH_PRIORITY';
1595                 }
1596
1597                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1598                         $startOpts .= ' SQL_BIG_RESULT';
1599                 }
1600
1601                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1602                         $startOpts .= ' SQL_BUFFER_RESULT';
1603                 }
1604
1605                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1606                         $startOpts .= ' SQL_SMALL_RESULT';
1607                 }
1608
1609                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1610                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1611                 }
1612
1613                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1614                         $startOpts .= ' SQL_CACHE';
1615                 }
1616
1617                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1618                         $startOpts .= ' SQL_NO_CACHE';
1619                 }
1620
1621                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1622                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1623                 } else {
1624                         $useIndex = '';
1625                 }
1626                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1627                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1628                 } else {
1629                         $ignoreIndex = '';
1630                 }
1631
1632                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1633         }
1634
1635         /**
1636          * Returns an optional GROUP BY with an optional HAVING
1637          *
1638          * @param array $options Associative array of options
1639          * @return string
1640          * @see Database::select()
1641          * @since 1.21
1642          */
1643         protected function makeGroupByWithHaving( $options ) {
1644                 $sql = '';
1645                 if ( isset( $options['GROUP BY'] ) ) {
1646                         $gb = is_array( $options['GROUP BY'] )
1647                                 ? implode( ',', $options['GROUP BY'] )
1648                                 : $options['GROUP BY'];
1649                         $sql .= ' GROUP BY ' . $gb;
1650                 }
1651                 if ( isset( $options['HAVING'] ) ) {
1652                         $having = is_array( $options['HAVING'] )
1653                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1654                                 : $options['HAVING'];
1655                         $sql .= ' HAVING ' . $having;
1656                 }
1657
1658                 return $sql;
1659         }
1660
1661         /**
1662          * Returns an optional ORDER BY
1663          *
1664          * @param array $options Associative array of options
1665          * @return string
1666          * @see Database::select()
1667          * @since 1.21
1668          */
1669         protected function makeOrderBy( $options ) {
1670                 if ( isset( $options['ORDER BY'] ) ) {
1671                         $ob = is_array( $options['ORDER BY'] )
1672                                 ? implode( ',', $options['ORDER BY'] )
1673                                 : $options['ORDER BY'];
1674
1675                         return ' ORDER BY ' . $ob;
1676                 }
1677
1678                 return '';
1679         }
1680
1681         public function select(
1682                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1683         ) {
1684                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1685
1686                 return $this->query( $sql, $fname );
1687         }
1688
1689         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1690                 $options = [], $join_conds = []
1691         ) {
1692                 if ( is_array( $vars ) ) {
1693                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1694                 } else {
1695                         $fields = $vars;
1696                 }
1697
1698                 $options = (array)$options;
1699                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1700                         ? $options['USE INDEX']
1701                         : [];
1702                 $ignoreIndexes = (
1703                         isset( $options['IGNORE INDEX'] ) &&
1704                         is_array( $options['IGNORE INDEX'] )
1705                 )
1706                         ? $options['IGNORE INDEX']
1707                         : [];
1708
1709                 if (
1710                         $this->selectOptionsIncludeLocking( $options ) &&
1711                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1712                 ) {
1713                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1714                         // functions. Discourage use of such queries to encourage compatibility.
1715                         call_user_func(
1716                                 $this->deprecationLogger,
1717                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)."
1718                         );
1719                 }
1720
1721                 if ( is_array( $table ) ) {
1722                         $from = ' FROM ' .
1723                                 $this->tableNamesWithIndexClauseOrJOIN(
1724                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1725                 } elseif ( $table != '' ) {
1726                         $from = ' FROM ' .
1727                                 $this->tableNamesWithIndexClauseOrJOIN(
1728                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1729                 } else {
1730                         $from = '';
1731                 }
1732
1733                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1734                         $this->makeSelectOptions( $options );
1735
1736                 if ( is_array( $conds ) ) {
1737                         $conds = $this->makeList( $conds, self::LIST_AND );
1738                 }
1739
1740                 if ( $conds === null || $conds === false ) {
1741                         $this->queryLogger->warning(
1742                                 __METHOD__
1743                                 . ' called from '
1744                                 . $fname
1745                                 . ' with incorrect parameters: $conds must be a string or an array'
1746                         );
1747                         $conds = '';
1748                 }
1749
1750                 if ( $conds === '' || $conds === '*' ) {
1751                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1752                 } elseif ( is_string( $conds ) ) {
1753                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1754                                 "WHERE $conds $preLimitTail";
1755                 } else {
1756                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1757                 }
1758
1759                 if ( isset( $options['LIMIT'] ) ) {
1760                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1761                                 $options['OFFSET'] ?? false );
1762                 }
1763                 $sql = "$sql $postLimitTail";
1764
1765                 if ( isset( $options['EXPLAIN'] ) ) {
1766                         $sql = 'EXPLAIN ' . $sql;
1767                 }
1768
1769                 return $sql;
1770         }
1771
1772         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1773                 $options = [], $join_conds = []
1774         ) {
1775                 $options = (array)$options;
1776                 $options['LIMIT'] = 1;
1777                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1778
1779                 if ( $res === false ) {
1780                         return false;
1781                 }
1782
1783                 if ( !$this->numRows( $res ) ) {
1784                         return false;
1785                 }
1786
1787                 $obj = $this->fetchObject( $res );
1788
1789                 return $obj;
1790         }
1791
1792         public function estimateRowCount(
1793                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1794         ) {
1795                 $conds = $this->normalizeConditions( $conds, $fname );
1796                 $column = $this->extractSingleFieldFromList( $var );
1797                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1798                         $conds[] = "$column IS NOT NULL";
1799                 }
1800
1801                 $res = $this->select(
1802                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1803                 );
1804                 $row = $res ? $this->fetchRow( $res ) : [];
1805
1806                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1807         }
1808
1809         public function selectRowCount(
1810                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1811         ) {
1812                 $conds = $this->normalizeConditions( $conds, $fname );
1813                 $column = $this->extractSingleFieldFromList( $var );
1814                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1815                         $conds[] = "$column IS NOT NULL";
1816                 }
1817
1818                 $res = $this->select(
1819                         [
1820                                 'tmp_count' => $this->buildSelectSubquery(
1821                                         $tables,
1822                                         '1',
1823                                         $conds,
1824                                         $fname,
1825                                         $options,
1826                                         $join_conds
1827                                 )
1828                         ],
1829                         [ 'rowcount' => 'COUNT(*)' ],
1830                         [],
1831                         $fname
1832                 );
1833                 $row = $res ? $this->fetchRow( $res ) : [];
1834
1835                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1836         }
1837
1838         /**
1839          * @param string|array $options
1840          * @return bool
1841          */
1842         private function selectOptionsIncludeLocking( $options ) {
1843                 $options = (array)$options;
1844                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1845                         if ( in_array( $lock, $options, true ) ) {
1846                                 return true;
1847                         }
1848                 }
1849
1850                 return false;
1851         }
1852
1853         /**
1854          * @param array|string $fields
1855          * @param array|string $options
1856          * @return bool
1857          */
1858         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1859                 foreach ( (array)$options as $key => $value ) {
1860                         if ( is_string( $key ) ) {
1861                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1862                                         return true;
1863                                 }
1864                         } elseif ( is_string( $value ) ) {
1865                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1866                                         return true;
1867                                 }
1868                         }
1869                 }
1870
1871                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1872                 foreach ( (array)$fields as $field ) {
1873                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1874                                 return true;
1875                         }
1876                 }
1877
1878                 return false;
1879         }
1880
1881         /**
1882          * @param array|string $conds
1883          * @param string $fname
1884          * @return array
1885          */
1886         final protected function normalizeConditions( $conds, $fname ) {
1887                 if ( $conds === null || $conds === false ) {
1888                         $this->queryLogger->warning(
1889                                 __METHOD__
1890                                 . ' called from '
1891                                 . $fname
1892                                 . ' with incorrect parameters: $conds must be a string or an array'
1893                         );
1894                         $conds = '';
1895                 }
1896
1897                 if ( !is_array( $conds ) ) {
1898                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1899                 }
1900
1901                 return $conds;
1902         }
1903
1904         /**
1905          * @param array|string $var Field parameter in the style of select()
1906          * @return string|null Column name or null; ignores aliases
1907          * @throws DBUnexpectedError Errors out if multiple columns are given
1908          */
1909         final protected function extractSingleFieldFromList( $var ) {
1910                 if ( is_array( $var ) ) {
1911                         if ( !$var ) {
1912                                 $column = null;
1913                         } elseif ( count( $var ) == 1 ) {
1914                                 $column = $var[0] ?? reset( $var );
1915                         } else {
1916                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1917                         }
1918                 } else {
1919                         $column = $var;
1920                 }
1921
1922                 return $column;
1923         }
1924
1925         public function lockForUpdate(
1926                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1927         ) {
1928                 if ( !$this->trxLevel && !$this->getFlag( self::DBO_TRX ) ) {
1929                         throw new DBUnexpectedError(
1930                                 $this,
1931                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
1932                         );
1933                 }
1934
1935                 $options = (array)$options;
1936                 $options[] = 'FOR UPDATE';
1937
1938                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
1939         }
1940
1941         /**
1942          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1943          * It's only slightly flawed. Don't use for anything important.
1944          *
1945          * @param string $sql A SQL Query
1946          *
1947          * @return string
1948          */
1949         protected static function generalizeSQL( $sql ) {
1950                 # This does the same as the regexp below would do, but in such a way
1951                 # as to avoid crashing php on some large strings.
1952                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1953
1954                 $sql = str_replace( "\\\\", '', $sql );
1955                 $sql = str_replace( "\\'", '', $sql );
1956                 $sql = str_replace( "\\\"", '', $sql );
1957                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1958                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1959
1960                 # All newlines, tabs, etc replaced by single space
1961                 $sql = preg_replace( '/\s+/', ' ', $sql );
1962
1963                 # All numbers => N,
1964                 # except the ones surrounded by characters, e.g. l10n
1965                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1966                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1967
1968                 return $sql;
1969         }
1970
1971         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1972                 $info = $this->fieldInfo( $table, $field );
1973
1974                 return (bool)$info;
1975         }
1976
1977         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1978                 if ( !$this->tableExists( $table ) ) {
1979                         return null;
1980                 }
1981
1982                 $info = $this->indexInfo( $table, $index, $fname );
1983                 if ( is_null( $info ) ) {
1984                         return null;
1985                 } else {
1986                         return $info !== false;
1987                 }
1988         }
1989
1990         abstract public function tableExists( $table, $fname = __METHOD__ );
1991
1992         public function indexUnique( $table, $index ) {
1993                 $indexInfo = $this->indexInfo( $table, $index );
1994
1995                 if ( !$indexInfo ) {
1996                         return null;
1997                 }
1998
1999                 return !$indexInfo[0]->Non_unique;
2000         }
2001
2002         /**
2003          * Helper for Database::insert().
2004          *
2005          * @param array $options
2006          * @return string
2007          */
2008         protected function makeInsertOptions( $options ) {
2009                 return implode( ' ', $options );
2010         }
2011
2012         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2013                 # No rows to insert, easy just return now
2014                 if ( !count( $a ) ) {
2015                         return true;
2016                 }
2017
2018                 $table = $this->tableName( $table );
2019
2020                 if ( !is_array( $options ) ) {
2021                         $options = [ $options ];
2022                 }
2023
2024                 $fh = null;
2025                 if ( isset( $options['fileHandle'] ) ) {
2026                         $fh = $options['fileHandle'];
2027                 }
2028                 $options = $this->makeInsertOptions( $options );
2029
2030                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2031                         $multi = true;
2032                         $keys = array_keys( $a[0] );
2033                 } else {
2034                         $multi = false;
2035                         $keys = array_keys( $a );
2036                 }
2037
2038                 $sql = 'INSERT ' . $options .
2039                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2040
2041                 if ( $multi ) {
2042                         $first = true;
2043                         foreach ( $a as $row ) {
2044                                 if ( $first ) {
2045                                         $first = false;
2046                                 } else {
2047                                         $sql .= ',';
2048                                 }
2049                                 $sql .= '(' . $this->makeList( $row ) . ')';
2050                         }
2051                 } else {
2052                         $sql .= '(' . $this->makeList( $a ) . ')';
2053                 }
2054
2055                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
2056                         return false;
2057                 } elseif ( $fh !== null ) {
2058                         return true;
2059                 }
2060
2061                 return (bool)$this->query( $sql, $fname );
2062         }
2063
2064         /**
2065          * Make UPDATE options array for Database::makeUpdateOptions
2066          *
2067          * @param array $options
2068          * @return array
2069          */
2070         protected function makeUpdateOptionsArray( $options ) {
2071                 if ( !is_array( $options ) ) {
2072                         $options = [ $options ];
2073                 }
2074
2075                 $opts = [];
2076
2077                 if ( in_array( 'IGNORE', $options ) ) {
2078                         $opts[] = 'IGNORE';
2079                 }
2080
2081                 return $opts;
2082         }
2083
2084         /**
2085          * Make UPDATE options for the Database::update function
2086          *
2087          * @param array $options The options passed to Database::update
2088          * @return string
2089          */
2090         protected function makeUpdateOptions( $options ) {
2091                 $opts = $this->makeUpdateOptionsArray( $options );
2092
2093                 return implode( ' ', $opts );
2094         }
2095
2096         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2097                 $table = $this->tableName( $table );
2098                 $opts = $this->makeUpdateOptions( $options );
2099                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2100
2101                 if ( $conds !== [] && $conds !== '*' ) {
2102                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2103                 }
2104
2105                 return (bool)$this->query( $sql, $fname );
2106         }
2107
2108         public function makeList( $a, $mode = self::LIST_COMMA ) {
2109                 if ( !is_array( $a ) ) {
2110                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2111                 }
2112
2113                 $first = true;
2114                 $list = '';
2115
2116                 foreach ( $a as $field => $value ) {
2117                         if ( !$first ) {
2118                                 if ( $mode == self::LIST_AND ) {
2119                                         $list .= ' AND ';
2120                                 } elseif ( $mode == self::LIST_OR ) {
2121                                         $list .= ' OR ';
2122                                 } else {
2123                                         $list .= ',';
2124                                 }
2125                         } else {
2126                                 $first = false;
2127                         }
2128
2129                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2130                                 $list .= "($value)";
2131                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2132                                 $list .= "$value";
2133                         } elseif (
2134                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2135                         ) {
2136                                 // Remove null from array to be handled separately if found
2137                                 $includeNull = false;
2138                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2139                                         $includeNull = true;
2140                                         unset( $value[$nullKey] );
2141                                 }
2142                                 if ( count( $value ) == 0 && !$includeNull ) {
2143                                         throw new InvalidArgumentException(
2144                                                 __METHOD__ . ": empty input for field $field" );
2145                                 } elseif ( count( $value ) == 0 ) {
2146                                         // only check if $field is null
2147                                         $list .= "$field IS NULL";
2148                                 } else {
2149                                         // IN clause contains at least one valid element
2150                                         if ( $includeNull ) {
2151                                                 // Group subconditions to ensure correct precedence
2152                                                 $list .= '(';
2153                                         }
2154                                         if ( count( $value ) == 1 ) {
2155                                                 // Special-case single values, as IN isn't terribly efficient
2156                                                 // Don't necessarily assume the single key is 0; we don't
2157                                                 // enforce linear numeric ordering on other arrays here.
2158                                                 $value = array_values( $value )[0];
2159                                                 $list .= $field . " = " . $this->addQuotes( $value );
2160                                         } else {
2161                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2162                                         }
2163                                         // if null present in array, append IS NULL
2164                                         if ( $includeNull ) {
2165                                                 $list .= " OR $field IS NULL)";
2166                                         }
2167                                 }
2168                         } elseif ( $value === null ) {
2169                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2170                                         $list .= "$field IS ";
2171                                 } elseif ( $mode == self::LIST_SET ) {
2172                                         $list .= "$field = ";
2173                                 }
2174                                 $list .= 'NULL';
2175                         } else {
2176                                 if (
2177                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2178                                 ) {
2179                                         $list .= "$field = ";
2180                                 }
2181                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2182                         }
2183                 }
2184
2185                 return $list;
2186         }
2187
2188         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2189                 $conds = [];
2190
2191                 foreach ( $data as $base => $sub ) {
2192                         if ( count( $sub ) ) {
2193                                 $conds[] = $this->makeList(
2194                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2195                                         self::LIST_AND );
2196                         }
2197                 }
2198
2199                 if ( $conds ) {
2200                         return $this->makeList( $conds, self::LIST_OR );
2201                 } else {
2202                         // Nothing to search for...
2203                         return false;
2204                 }
2205         }
2206
2207         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2208                 return $valuename;
2209         }
2210
2211         public function bitNot( $field ) {
2212                 return "(~$field)";
2213         }
2214
2215         public function bitAnd( $fieldLeft, $fieldRight ) {
2216                 return "($fieldLeft & $fieldRight)";
2217         }
2218
2219         public function bitOr( $fieldLeft, $fieldRight ) {
2220                 return "($fieldLeft | $fieldRight)";
2221         }
2222
2223         public function buildConcat( $stringList ) {
2224                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2225         }
2226
2227         public function buildGroupConcatField(
2228                 $delim, $table, $field, $conds = '', $join_conds = []
2229         ) {
2230                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2231
2232                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2233         }
2234
2235         public function buildSubstring( $input, $startPosition, $length = null ) {
2236                 $this->assertBuildSubstringParams( $startPosition, $length );
2237                 $functionBody = "$input FROM $startPosition";
2238                 if ( $length !== null ) {
2239                         $functionBody .= " FOR $length";
2240                 }
2241                 return 'SUBSTRING(' . $functionBody . ')';
2242         }
2243
2244         /**
2245          * Check type and bounds for parameters to self::buildSubstring()
2246          *
2247          * All supported databases have substring functions that behave the same for
2248          * positive $startPosition and non-negative $length, but behaviors differ when
2249          * given 0 or negative $startPosition or negative $length. The simplest
2250          * solution to that is to just forbid those values.
2251          *
2252          * @param int $startPosition
2253          * @param int|null $length
2254          * @since 1.31
2255          */
2256         protected function assertBuildSubstringParams( $startPosition, $length ) {
2257                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2258                         throw new InvalidArgumentException(
2259                                 '$startPosition must be a positive integer'
2260                         );
2261                 }
2262                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2263                         throw new InvalidArgumentException(
2264                                 '$length must be null or an integer greater than or equal to 0'
2265                         );
2266                 }
2267         }
2268
2269         public function buildStringCast( $field ) {
2270                 return $field;
2271         }
2272
2273         public function buildIntegerCast( $field ) {
2274                 return 'CAST( ' . $field . ' AS INTEGER )';
2275         }
2276
2277         public function buildSelectSubquery(
2278                 $table, $vars, $conds = '', $fname = __METHOD__,
2279                 $options = [], $join_conds = []
2280         ) {
2281                 return new Subquery(
2282                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2283                 );
2284         }
2285
2286         public function databasesAreIndependent() {
2287                 return false;
2288         }
2289
2290         public function selectDB( $db ) {
2291                 # Stub. Shouldn't cause serious problems if it's not overridden, but
2292                 # if your database engine supports a concept similar to MySQL's
2293                 # databases you may as well.
2294                 $this->dbName = $db;
2295
2296                 return true;
2297         }
2298
2299         public function getDBname() {
2300                 return $this->dbName;
2301         }
2302
2303         public function getServer() {
2304                 return $this->server;
2305         }
2306
2307         public function tableName( $name, $format = 'quoted' ) {
2308                 if ( $name instanceof Subquery ) {
2309                         throw new DBUnexpectedError(
2310                                 $this,
2311                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2312                         );
2313                 }
2314
2315                 # Skip the entire process when we have a string quoted on both ends.
2316                 # Note that we check the end so that we will still quote any use of
2317                 # use of `database`.table. But won't break things if someone wants
2318                 # to query a database table with a dot in the name.
2319                 if ( $this->isQuotedIdentifier( $name ) ) {
2320                         return $name;
2321                 }
2322
2323                 # Lets test for any bits of text that should never show up in a table
2324                 # name. Basically anything like JOIN or ON which are actually part of
2325                 # SQL queries, but may end up inside of the table value to combine
2326                 # sql. Such as how the API is doing.
2327                 # Note that we use a whitespace test rather than a \b test to avoid
2328                 # any remote case where a word like on may be inside of a table name
2329                 # surrounded by symbols which may be considered word breaks.
2330                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2331                         $this->queryLogger->warning(
2332                                 __METHOD__ . ": use of subqueries is not supported this way.",
2333                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2334                         );
2335
2336                         return $name;
2337                 }
2338
2339                 # Split database and table into proper variables.
2340                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2341
2342                 # Quote $table and apply the prefix if not quoted.
2343                 # $tableName might be empty if this is called from Database::replaceVars()
2344                 $tableName = "{$prefix}{$table}";
2345                 if ( $format === 'quoted'
2346                         && !$this->isQuotedIdentifier( $tableName )
2347                         && $tableName !== ''
2348                 ) {
2349                         $tableName = $this->addIdentifierQuotes( $tableName );
2350                 }
2351
2352                 # Quote $schema and $database and merge them with the table name if needed
2353                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2354                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2355
2356                 return $tableName;
2357         }
2358
2359         /**
2360          * Get the table components needed for a query given the currently selected database
2361          *
2362          * @param string $name Table name in the form of db.schema.table, db.table, or table
2363          * @return array (DB name or "" for default, schema name, table prefix, table name)
2364          */
2365         protected function qualifiedTableComponents( $name ) {
2366                 # We reverse the explode so that database.table and table both output the correct table.
2367                 $dbDetails = explode( '.', $name, 3 );
2368                 if ( count( $dbDetails ) == 3 ) {
2369                         list( $database, $schema, $table ) = $dbDetails;
2370                         # We don't want any prefix added in this case
2371                         $prefix = '';
2372                 } elseif ( count( $dbDetails ) == 2 ) {
2373                         list( $database, $table ) = $dbDetails;
2374                         # We don't want any prefix added in this case
2375                         $prefix = '';
2376                         # In dbs that support it, $database may actually be the schema
2377                         # but that doesn't affect any of the functionality here
2378                         $schema = '';
2379                 } else {
2380                         list( $table ) = $dbDetails;
2381                         if ( isset( $this->tableAliases[$table] ) ) {
2382                                 $database = $this->tableAliases[$table]['dbname'];
2383                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2384                                         ? $this->tableAliases[$table]['schema']
2385                                         : $this->schema;
2386                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2387                                         ? $this->tableAliases[$table]['prefix']
2388                                         : $this->tablePrefix;
2389                         } else {
2390                                 $database = '';
2391                                 $schema = $this->schema; # Default schema
2392                                 $prefix = $this->tablePrefix; # Default prefix
2393                         }
2394                 }
2395
2396                 return [ $database, $schema, $prefix, $table ];
2397         }
2398
2399         /**
2400          * @param string|null $namespace Database or schema
2401          * @param string $relation Name of table, view, sequence, etc...
2402          * @param string $format One of (raw, quoted)
2403          * @return string Relation name with quoted and merged $namespace as needed
2404          */
2405         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2406                 if ( strlen( $namespace ) ) {
2407                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2408                                 $namespace = $this->addIdentifierQuotes( $namespace );
2409                         }
2410                         $relation = $namespace . '.' . $relation;
2411                 }
2412
2413                 return $relation;
2414         }
2415
2416         public function tableNames() {
2417                 $inArray = func_get_args();
2418                 $retVal = [];
2419
2420                 foreach ( $inArray as $name ) {
2421                         $retVal[$name] = $this->tableName( $name );
2422                 }
2423
2424                 return $retVal;
2425         }
2426
2427         public function tableNamesN() {
2428                 $inArray = func_get_args();
2429                 $retVal = [];
2430
2431                 foreach ( $inArray as $name ) {
2432                         $retVal[] = $this->tableName( $name );
2433                 }
2434
2435                 return $retVal;
2436         }
2437
2438         /**
2439          * Get an aliased table name
2440          *
2441          * This returns strings like "tableName AS newTableName" for aliased tables
2442          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2443          *
2444          * @see Database::tableName()
2445          * @param string|Subquery $table Table name or object with a 'sql' field
2446          * @param string|bool $alias Table alias (optional)
2447          * @return string SQL name for aliased table. Will not alias a table to its own name
2448          */
2449         protected function tableNameWithAlias( $table, $alias = false ) {
2450                 if ( is_string( $table ) ) {
2451                         $quotedTable = $this->tableName( $table );
2452                 } elseif ( $table instanceof Subquery ) {
2453                         $quotedTable = (string)$table;
2454                 } else {
2455                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2456                 }
2457
2458                 if ( !strlen( $alias ) || $alias === $table ) {
2459                         if ( $table instanceof Subquery ) {
2460                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2461                         }
2462
2463                         return $quotedTable;
2464                 } else {
2465                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2466                 }
2467         }
2468
2469         /**
2470          * Gets an array of aliased table names
2471          *
2472          * @param array $tables [ [alias] => table ]
2473          * @return string[] See tableNameWithAlias()
2474          */
2475         protected function tableNamesWithAlias( $tables ) {
2476                 $retval = [];
2477                 foreach ( $tables as $alias => $table ) {
2478                         if ( is_numeric( $alias ) ) {
2479                                 $alias = $table;
2480                         }
2481                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2482                 }
2483
2484                 return $retval;
2485         }
2486
2487         /**
2488          * Get an aliased field name
2489          * e.g. fieldName AS newFieldName
2490          *
2491          * @param string $name Field name
2492          * @param string|bool $alias Alias (optional)
2493          * @return string SQL name for aliased field. Will not alias a field to its own name
2494          */
2495         protected function fieldNameWithAlias( $name, $alias = false ) {
2496                 if ( !$alias || (string)$alias === (string)$name ) {
2497                         return $name;
2498                 } else {
2499                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2500                 }
2501         }
2502
2503         /**
2504          * Gets an array of aliased field names
2505          *
2506          * @param array $fields [ [alias] => field ]
2507          * @return string[] See fieldNameWithAlias()
2508          */
2509         protected function fieldNamesWithAlias( $fields ) {
2510                 $retval = [];
2511                 foreach ( $fields as $alias => $field ) {
2512                         if ( is_numeric( $alias ) ) {
2513                                 $alias = $field;
2514                         }
2515                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2516                 }
2517
2518                 return $retval;
2519         }
2520
2521         /**
2522          * Get the aliased table name clause for a FROM clause
2523          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2524          *
2525          * @param array $tables ( [alias] => table )
2526          * @param array $use_index Same as for select()
2527          * @param array $ignore_index Same as for select()
2528          * @param array $join_conds Same as for select()
2529          * @return string
2530          */
2531         protected function tableNamesWithIndexClauseOrJOIN(
2532                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2533         ) {
2534                 $ret = [];
2535                 $retJOIN = [];
2536                 $use_index = (array)$use_index;
2537                 $ignore_index = (array)$ignore_index;
2538                 $join_conds = (array)$join_conds;
2539
2540                 foreach ( $tables as $alias => $table ) {
2541                         if ( !is_string( $alias ) ) {
2542                                 // No alias? Set it equal to the table name
2543                                 $alias = $table;
2544                         }
2545
2546                         if ( is_array( $table ) ) {
2547                                 // A parenthesized group
2548                                 if ( count( $table ) > 1 ) {
2549                                         $joinedTable = '(' .
2550                                                 $this->tableNamesWithIndexClauseOrJOIN(
2551                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2552                                 } else {
2553                                         // Degenerate case
2554                                         $innerTable = reset( $table );
2555                                         $innerAlias = key( $table );
2556                                         $joinedTable = $this->tableNameWithAlias(
2557                                                 $innerTable,
2558                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2559                                         );
2560                                 }
2561                         } else {
2562                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2563                         }
2564
2565                         // Is there a JOIN clause for this table?
2566                         if ( isset( $join_conds[$alias] ) ) {
2567                                 list( $joinType, $conds ) = $join_conds[$alias];
2568                                 $tableClause = $joinType;
2569                                 $tableClause .= ' ' . $joinedTable;
2570                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2571                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2572                                         if ( $use != '' ) {
2573                                                 $tableClause .= ' ' . $use;
2574                                         }
2575                                 }
2576                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2577                                         $ignore = $this->ignoreIndexClause(
2578                                                 implode( ',', (array)$ignore_index[$alias] ) );
2579                                         if ( $ignore != '' ) {
2580                                                 $tableClause .= ' ' . $ignore;
2581                                         }
2582                                 }
2583                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2584                                 if ( $on != '' ) {
2585                                         $tableClause .= ' ON (' . $on . ')';
2586                                 }
2587
2588                                 $retJOIN[] = $tableClause;
2589                         } elseif ( isset( $use_index[$alias] ) ) {
2590                                 // Is there an INDEX clause for this table?
2591                                 $tableClause = $joinedTable;
2592                                 $tableClause .= ' ' . $this->useIndexClause(
2593                                                 implode( ',', (array)$use_index[$alias] )
2594                                         );
2595
2596                                 $ret[] = $tableClause;
2597                         } elseif ( isset( $ignore_index[$alias] ) ) {
2598                                 // Is there an INDEX clause for this table?
2599                                 $tableClause = $joinedTable;
2600                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2601                                                 implode( ',', (array)$ignore_index[$alias] )
2602                                         );
2603
2604                                 $ret[] = $tableClause;
2605                         } else {
2606                                 $tableClause = $joinedTable;
2607
2608                                 $ret[] = $tableClause;
2609                         }
2610                 }
2611
2612                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2613                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2614                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2615
2616                 // Compile our final table clause
2617                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2618         }
2619
2620         /**
2621          * Allows for index remapping in queries where this is not consistent across DBMS
2622          *
2623          * @param string $index
2624          * @return string
2625          */
2626         protected function indexName( $index ) {
2627                 return $this->indexAliases[$index] ?? $index;
2628         }
2629
2630         public function addQuotes( $s ) {
2631                 if ( $s instanceof Blob ) {
2632                         $s = $s->fetch();
2633                 }
2634                 if ( $s === null ) {
2635                         return 'NULL';
2636                 } elseif ( is_bool( $s ) ) {
2637                         return (int)$s;
2638                 } else {
2639                         # This will also quote numeric values. This should be harmless,
2640                         # and protects against weird problems that occur when they really
2641                         # _are_ strings such as article titles and string->number->string
2642                         # conversion is not 1:1.
2643                         return "'" . $this->strencode( $s ) . "'";
2644                 }
2645         }
2646
2647         /**
2648          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2649          * MySQL uses `backticks` while basically everything else uses double quotes.
2650          * Since MySQL is the odd one out here the double quotes are our generic
2651          * and we implement backticks in DatabaseMysqlBase.
2652          *
2653          * @param string $s
2654          * @return string
2655          */
2656         public function addIdentifierQuotes( $s ) {
2657                 return '"' . str_replace( '"', '""', $s ) . '"';
2658         }
2659
2660         /**
2661          * Returns if the given identifier looks quoted or not according to
2662          * the database convention for quoting identifiers .
2663          *
2664          * @note Do not use this to determine if untrusted input is safe.
2665          *   A malicious user can trick this function.
2666          * @param string $name
2667          * @return bool
2668          */
2669         public function isQuotedIdentifier( $name ) {
2670                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2671         }
2672
2673         /**
2674          * @param string $s
2675          * @param string $escapeChar
2676          * @return string
2677          */
2678         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2679                 return str_replace( [ $escapeChar, '%', '_' ],
2680                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2681                         $s );
2682         }
2683
2684         public function buildLike() {
2685                 $params = func_get_args();
2686
2687                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2688                         $params = $params[0];
2689                 }
2690
2691                 $s = '';
2692
2693                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2694                 // may escape backslashes, creating problems of double escaping. The `
2695                 // character has good cross-DBMS compatibility, avoiding special operators
2696                 // in MS SQL like ^ and %
2697                 $escapeChar = '`';
2698
2699                 foreach ( $params as $value ) {
2700                         if ( $value instanceof LikeMatch ) {
2701                                 $s .= $value->toString();
2702                         } else {
2703                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2704                         }
2705                 }
2706
2707                 return ' LIKE ' .
2708                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2709         }
2710
2711         public function anyChar() {
2712                 return new LikeMatch( '_' );
2713         }
2714
2715         public function anyString() {
2716                 return new LikeMatch( '%' );
2717         }
2718
2719         public function nextSequenceValue( $seqName ) {
2720                 return null;
2721         }
2722
2723         /**
2724          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2725          * is only needed because a) MySQL must be as efficient as possible due to
2726          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2727          * which index to pick. Anyway, other databases might have different
2728          * indexes on a given table. So don't bother overriding this unless you're
2729          * MySQL.
2730          * @param string $index
2731          * @return string
2732          */
2733         public function useIndexClause( $index ) {
2734                 return '';
2735         }
2736
2737         /**
2738          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2739          * is only needed because a) MySQL must be as efficient as possible due to
2740          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2741          * which index to pick. Anyway, other databases might have different
2742          * indexes on a given table. So don't bother overriding this unless you're
2743          * MySQL.
2744          * @param string $index
2745          * @return string
2746          */
2747         public function ignoreIndexClause( $index ) {
2748                 return '';
2749         }
2750
2751         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2752                 if ( count( $rows ) == 0 ) {
2753                         return;
2754                 }
2755
2756                 // Single row case
2757                 if ( !is_array( reset( $rows ) ) ) {
2758                         $rows = [ $rows ];
2759                 }
2760
2761                 try {
2762                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2763                         $affectedRowCount = 0;
2764                         foreach ( $rows as $row ) {
2765                                 // Delete rows which collide with this one
2766                                 $indexWhereClauses = [];
2767                                 foreach ( $uniqueIndexes as $index ) {
2768                                         $indexColumns = (array)$index;
2769                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2770                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2771                                                 throw new DBUnexpectedError(
2772                                                         $this,
2773                                                         'New record does not provide all values for unique key (' .
2774                                                         implode( ', ', $indexColumns ) . ')'
2775                                                 );
2776                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2777                                                 throw new DBUnexpectedError(
2778                                                         $this,
2779                                                         'New record has a null value for unique key (' .
2780                                                         implode( ', ', $indexColumns ) . ')'
2781                                                 );
2782                                         }
2783                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2784                                 }
2785
2786                                 if ( $indexWhereClauses ) {
2787                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2788                                         $affectedRowCount += $this->affectedRows();
2789                                 }
2790
2791                                 // Now insert the row
2792                                 $this->insert( $table, $row, $fname );
2793                                 $affectedRowCount += $this->affectedRows();
2794                         }
2795                         $this->endAtomic( $fname );
2796                         $this->affectedRowCount = $affectedRowCount;
2797                 } catch ( Exception $e ) {
2798                         $this->cancelAtomic( $fname );
2799                         throw $e;
2800                 }
2801         }
2802
2803         /**
2804          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2805          * statement.
2806          *
2807          * @param string $table Table name
2808          * @param array|string $rows Row(s) to insert
2809          * @param string $fname Caller function name
2810          *
2811          * @return ResultWrapper
2812          */
2813         protected function nativeReplace( $table, $rows, $fname ) {
2814                 $table = $this->tableName( $table );
2815
2816                 # Single row case
2817                 if ( !is_array( reset( $rows ) ) ) {
2818                         $rows = [ $rows ];
2819                 }
2820
2821                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2822                 $first = true;
2823
2824                 foreach ( $rows as $row ) {
2825                         if ( $first ) {
2826                                 $first = false;
2827                         } else {
2828                                 $sql .= ',';
2829                         }
2830
2831                         $sql .= '(' . $this->makeList( $row ) . ')';
2832                 }
2833
2834                 return $this->query( $sql, $fname );
2835         }
2836
2837         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2838                 $fname = __METHOD__
2839         ) {
2840                 if ( !count( $rows ) ) {
2841                         return true; // nothing to do
2842                 }
2843
2844                 if ( !is_array( reset( $rows ) ) ) {
2845                         $rows = [ $rows ];
2846                 }
2847
2848                 if ( count( $uniqueIndexes ) ) {
2849                         $clauses = []; // list WHERE clauses that each identify a single row
2850                         foreach ( $rows as $row ) {
2851                                 foreach ( $uniqueIndexes as $index ) {
2852                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2853                                         $rowKey = []; // unique key to this row
2854                                         foreach ( $index as $column ) {
2855                                                 $rowKey[$column] = $row[$column];
2856                                         }
2857                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2858                                 }
2859                         }
2860                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2861                 } else {
2862                         $where = false;
2863                 }
2864
2865                 $affectedRowCount = 0;
2866                 try {
2867                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2868                         # Update any existing conflicting row(s)
2869                         if ( $where !== false ) {
2870                                 $ok = $this->update( $table, $set, $where, $fname );
2871                                 $affectedRowCount += $this->affectedRows();
2872                         } else {
2873                                 $ok = true;
2874                         }
2875                         # Now insert any non-conflicting row(s)
2876                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2877                         $affectedRowCount += $this->affectedRows();
2878                         $this->endAtomic( $fname );
2879                         $this->affectedRowCount = $affectedRowCount;
2880                 } catch ( Exception $e ) {
2881                         $this->cancelAtomic( $fname );
2882                         throw $e;
2883                 }
2884
2885                 return $ok;
2886         }
2887
2888         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2889                 $fname = __METHOD__
2890         ) {
2891                 if ( !$conds ) {
2892                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2893                 }
2894
2895                 $delTable = $this->tableName( $delTable );
2896                 $joinTable = $this->tableName( $joinTable );
2897                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2898                 if ( $conds != '*' ) {
2899                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2900                 }
2901                 $sql .= ')';
2902
2903                 $this->query( $sql, $fname );
2904         }
2905
2906         public function textFieldSize( $table, $field ) {
2907                 $table = $this->tableName( $table );
2908                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2909                 $res = $this->query( $sql, __METHOD__ );
2910                 $row = $this->fetchObject( $res );
2911
2912                 $m = [];
2913
2914                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2915                         $size = $m[1];
2916                 } else {
2917                         $size = -1;
2918                 }
2919
2920                 return $size;
2921         }
2922
2923         public function delete( $table, $conds, $fname = __METHOD__ ) {
2924                 if ( !$conds ) {
2925                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2926                 }
2927
2928                 $table = $this->tableName( $table );
2929                 $sql = "DELETE FROM $table";
2930
2931                 if ( $conds != '*' ) {
2932                         if ( is_array( $conds ) ) {
2933                                 $conds = $this->makeList( $conds, self::LIST_AND );
2934                         }
2935                         $sql .= ' WHERE ' . $conds;
2936                 }
2937
2938                 return $this->query( $sql, $fname );
2939         }
2940
2941         final public function insertSelect(
2942                 $destTable, $srcTable, $varMap, $conds,
2943                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2944         ) {
2945                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2946
2947                 $insertOptions = (array)$insertOptions;
2948                 $selectOptions = (array)$selectOptions;
2949
2950                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2951                         // For massive migrations with downtime, we don't want to select everything
2952                         // into memory and OOM, so do all this native on the server side if possible.
2953                         return $this->nativeInsertSelect(
2954                                 $destTable,
2955                                 $srcTable,
2956                                 $varMap,
2957                                 $conds,
2958                                 $fname,
2959                                 array_diff( $insertOptions, $hints ),
2960                                 $selectOptions,
2961                                 $selectJoinConds
2962                         );
2963                 }
2964
2965                 return $this->nonNativeInsertSelect(
2966                         $destTable,
2967                         $srcTable,
2968                         $varMap,
2969                         $conds,
2970                         $fname,
2971                         array_diff( $insertOptions, $hints ),
2972                         $selectOptions,
2973                         $selectJoinConds
2974                 );
2975         }
2976
2977         /**
2978          * @param array $insertOptions INSERT options
2979          * @param array $selectOptions SELECT options
2980          * @return bool Whether an INSERT SELECT with these options will be replication safe
2981          * @since 1.31
2982          */
2983         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
2984                 return true;
2985         }
2986
2987         /**
2988          * Implementation of insertSelect() based on select() and insert()
2989          *
2990          * @see IDatabase::insertSelect()
2991          * @since 1.30
2992          * @param string $destTable
2993          * @param string|array $srcTable
2994          * @param array $varMap
2995          * @param array $conds
2996          * @param string $fname
2997          * @param array $insertOptions
2998          * @param array $selectOptions
2999          * @param array $selectJoinConds
3000          * @return bool
3001          */
3002         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3003                 $fname = __METHOD__,
3004                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3005         ) {
3006                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3007                 // on only the master (without needing row-based-replication). It also makes it easy to
3008                 // know how big the INSERT is going to be.
3009                 $fields = [];
3010                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3011                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3012                 }
3013                 $selectOptions[] = 'FOR UPDATE';
3014                 $res = $this->select(
3015                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3016                 );
3017                 if ( !$res ) {
3018                         return false;
3019                 }
3020
3021                 try {
3022                         $affectedRowCount = 0;
3023                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3024                         $rows = [];
3025                         $ok = true;
3026                         foreach ( $res as $row ) {
3027                                 $rows[] = (array)$row;
3028
3029                                 // Avoid inserts that are too huge
3030                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3031                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3032                                         if ( !$ok ) {
3033                                                 break;
3034                                         }
3035                                         $affectedRowCount += $this->affectedRows();
3036                                         $rows = [];
3037                                 }
3038                         }
3039                         if ( $rows && $ok ) {
3040                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3041                                 if ( $ok ) {
3042                                         $affectedRowCount += $this->affectedRows();
3043                                 }
3044                         }
3045                         if ( $ok ) {
3046                                 $this->endAtomic( $fname );
3047                                 $this->affectedRowCount = $affectedRowCount;
3048                         } else {
3049                                 $this->cancelAtomic( $fname );
3050                         }
3051                         return $ok;
3052                 } catch ( Exception $e ) {
3053                         $this->cancelAtomic( $fname );
3054                         throw $e;
3055                 }
3056         }
3057
3058         /**
3059          * Native server-side implementation of insertSelect() for situations where
3060          * we don't want to select everything into memory
3061          *
3062          * @see IDatabase::insertSelect()
3063          * @param string $destTable
3064          * @param string|array $srcTable
3065          * @param array $varMap
3066          * @param array $conds
3067          * @param string $fname
3068          * @param array $insertOptions
3069          * @param array $selectOptions
3070          * @param array $selectJoinConds
3071          * @return bool
3072          */
3073         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3074                 $fname = __METHOD__,
3075                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3076         ) {
3077                 $destTable = $this->tableName( $destTable );
3078
3079                 if ( !is_array( $insertOptions ) ) {
3080                         $insertOptions = [ $insertOptions ];
3081                 }
3082
3083                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3084
3085                 $selectSql = $this->selectSQLText(
3086                         $srcTable,
3087                         array_values( $varMap ),
3088                         $conds,
3089                         $fname,
3090                         $selectOptions,
3091                         $selectJoinConds
3092                 );
3093
3094                 $sql = "INSERT $insertOptions" .
3095                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3096                         $selectSql;
3097
3098                 return $this->query( $sql, $fname );
3099         }
3100
3101         /**
3102          * Construct a LIMIT query with optional offset. This is used for query
3103          * pages. The SQL should be adjusted so that only the first $limit rows
3104          * are returned. If $offset is provided as well, then the first $offset
3105          * rows should be discarded, and the next $limit rows should be returned.
3106          * If the result of the query is not ordered, then the rows to be returned
3107          * are theoretically arbitrary.
3108          *
3109          * $sql is expected to be a SELECT, if that makes a difference.
3110          *
3111          * The version provided by default works in MySQL and SQLite. It will very
3112          * likely need to be overridden for most other DBMSes.
3113          *
3114          * @param string $sql SQL query we will append the limit too
3115          * @param int $limit The SQL limit
3116          * @param int|bool $offset The SQL offset (default false)
3117          * @throws DBUnexpectedError
3118          * @return string
3119          */
3120         public function limitResult( $sql, $limit, $offset = false ) {
3121                 if ( !is_numeric( $limit ) ) {
3122                         throw new DBUnexpectedError( $this,
3123                                 "Invalid non-numeric limit passed to limitResult()\n" );
3124                 }
3125
3126                 return "$sql LIMIT "
3127                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3128                 . "{$limit} ";
3129         }
3130
3131         public function unionSupportsOrderAndLimit() {
3132                 return true; // True for almost every DB supported
3133         }
3134
3135         public function unionQueries( $sqls, $all ) {
3136                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3137
3138                 return '(' . implode( $glue, $sqls ) . ')';
3139         }
3140
3141         public function unionConditionPermutations(
3142                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3143                 $options = [], $join_conds = []
3144         ) {
3145                 // First, build the Cartesian product of $permute_conds
3146                 $conds = [ [] ];
3147                 foreach ( $permute_conds as $field => $values ) {
3148                         if ( !$values ) {
3149                                 // Skip empty $values
3150                                 continue;
3151                         }
3152                         $values = array_unique( $values ); // For sanity
3153                         $newConds = [];
3154                         foreach ( $conds as $cond ) {
3155                                 foreach ( $values as $value ) {
3156                                         $cond[$field] = $value;
3157                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3158                                 }
3159                         }
3160                         $conds = $newConds;
3161                 }
3162
3163                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3164
3165                 // If there's just one condition and no subordering, hand off to
3166                 // selectSQLText directly.
3167                 if ( count( $conds ) === 1 &&
3168                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3169                 ) {
3170                         return $this->selectSQLText(
3171                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3172                         );
3173                 }
3174
3175                 // Otherwise, we need to pull out the order and limit to apply after
3176                 // the union. Then build the SQL queries for each set of conditions in
3177                 // $conds. Then union them together (using UNION ALL, because the
3178                 // product *should* already be distinct).
3179                 $orderBy = $this->makeOrderBy( $options );
3180                 $limit = $options['LIMIT'] ?? null;
3181                 $offset = $options['OFFSET'] ?? false;
3182                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3183                 if ( !$this->unionSupportsOrderAndLimit() ) {
3184                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3185                 } else {
3186                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3187                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3188                         }
3189                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3190                                 // We need to increase the limit by the offset rather than
3191                                 // using the offset directly, otherwise it'll skip incorrectly
3192                                 // in the subqueries.
3193                                 $options['LIMIT'] = $limit + $offset;
3194                                 unset( $options['OFFSET'] );
3195                         }
3196                 }
3197
3198                 $sqls = [];
3199                 foreach ( $conds as $cond ) {
3200                         $sqls[] = $this->selectSQLText(
3201                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3202                         );
3203                 }
3204                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3205                 if ( $limit !== null ) {
3206                         $sql = $this->limitResult( $sql, $limit, $offset );
3207                 }
3208
3209                 return $sql;
3210         }
3211
3212         public function conditional( $cond, $trueVal, $falseVal ) {
3213                 if ( is_array( $cond ) ) {
3214                         $cond = $this->makeList( $cond, self::LIST_AND );
3215                 }
3216
3217                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3218         }
3219
3220         public function strreplace( $orig, $old, $new ) {
3221                 return "REPLACE({$orig}, {$old}, {$new})";
3222         }
3223
3224         public function getServerUptime() {
3225                 return 0;
3226         }
3227
3228         public function wasDeadlock() {
3229                 return false;
3230         }
3231
3232         public function wasLockTimeout() {
3233                 return false;
3234         }
3235
3236         public function wasConnectionLoss() {
3237                 return $this->wasConnectionError( $this->lastErrno() );
3238         }
3239
3240         public function wasReadOnlyError() {
3241                 return false;
3242         }
3243
3244         public function wasErrorReissuable() {
3245                 return (
3246                         $this->wasDeadlock() ||
3247                         $this->wasLockTimeout() ||
3248                         $this->wasConnectionLoss()
3249                 );
3250         }
3251
3252         /**
3253          * Do not use this method outside of Database/DBError classes
3254          *
3255          * @param int|string $errno
3256          * @return bool Whether the given query error was a connection drop
3257          */
3258         public function wasConnectionError( $errno ) {
3259                 return false;
3260         }
3261
3262         /**
3263          * @return bool Whether it is safe to assume the given error only caused statement rollback
3264          * @note This is for backwards compatibility for callers catching DBError exceptions in
3265          *   order to ignore problems like duplicate key errors or foriegn key violations
3266          * @since 1.31
3267          */
3268         protected function wasKnownStatementRollbackError() {
3269                 return false; // don't know; it could have caused a transaction rollback
3270         }
3271
3272         public function deadlockLoop() {
3273                 $args = func_get_args();
3274                 $function = array_shift( $args );
3275                 $tries = self::DEADLOCK_TRIES;
3276
3277                 $this->begin( __METHOD__ );
3278
3279                 $retVal = null;
3280                 /** @var Exception $e */
3281                 $e = null;
3282                 do {
3283                         try {
3284                                 $retVal = $function( ...$args );
3285                                 break;
3286                         } catch ( DBQueryError $e ) {
3287                                 if ( $this->wasDeadlock() ) {
3288                                         // Retry after a randomized delay
3289                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3290                                 } else {
3291                                         // Throw the error back up
3292                                         throw $e;
3293                                 }
3294                         }
3295                 } while ( --$tries > 0 );
3296
3297                 if ( $tries <= 0 ) {
3298                         // Too many deadlocks; give up
3299                         $this->rollback( __METHOD__ );
3300                         throw $e;
3301                 } else {
3302                         $this->commit( __METHOD__ );
3303
3304                         return $retVal;
3305                 }
3306         }
3307
3308         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3309                 # Real waits are implemented in the subclass.
3310                 return 0;
3311         }
3312
3313         public function getReplicaPos() {
3314                 # Stub
3315                 return false;
3316         }
3317
3318         public function getMasterPos() {
3319                 # Stub
3320                 return false;
3321         }
3322
3323         public function serverIsReadOnly() {
3324                 return false;
3325         }
3326
3327         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3328                 if ( !$this->trxLevel ) {
3329                         throw new DBUnexpectedError( $this, "No transaction is active." );
3330                 }
3331                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3332         }
3333
3334         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3335                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3336                         // Start an implicit transaction similar to how query() does
3337                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3338                         $this->trxAutomatic = true;
3339                 }
3340
3341                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3342                 if ( !$this->trxLevel ) {
3343                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3344                 }
3345         }
3346
3347         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3348                 $this->onTransactionCommitOrIdle( $callback, $fname );
3349         }
3350
3351         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3352                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3353                         // Start an implicit transaction similar to how query() does
3354                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3355                         $this->trxAutomatic = true;
3356                 }
3357
3358                 if ( $this->trxLevel ) {
3359                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3360                 } else {
3361                         // No transaction is active nor will start implicitly, so make one for this callback
3362                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3363                         try {
3364                                 $callback( $this );
3365                                 $this->endAtomic( __METHOD__ );
3366                         } catch ( Exception $e ) {
3367                                 $this->cancelAtomic( __METHOD__ );
3368                                 throw $e;
3369                         }
3370                 }
3371         }
3372
3373         /**
3374          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3375          */
3376         private function currentAtomicSectionId() {
3377                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3378                         $levelInfo = end( $this->trxAtomicLevels );
3379
3380                         return $levelInfo[1];
3381                 }
3382
3383                 return null;
3384         }
3385
3386         /**
3387          * @param AtomicSectionIdentifier $old
3388          * @param AtomicSectionIdentifier $new
3389          */
3390         private function reassignCallbacksForSection(
3391                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3392         ) {
3393                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3394                         if ( $info[2] === $old ) {
3395                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3396                         }
3397                 }
3398                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3399                         if ( $info[2] === $old ) {
3400                                 $this->trxIdleCallbacks[$key][2] = $new;
3401                         }
3402                 }
3403                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3404                         if ( $info[2] === $old ) {
3405                                 $this->trxEndCallbacks[$key][2] = $new;
3406                         }
3407                 }
3408         }
3409
3410         /**
3411          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3412          * @throws UnexpectedValueException
3413          */
3414         private function modifyCallbacksForCancel( array $sectionIds ) {
3415                 // Cancel the "on commit" callbacks owned by this savepoint
3416                 $this->trxIdleCallbacks = array_filter(
3417                         $this->trxIdleCallbacks,
3418                         function ( $entry ) use ( $sectionIds ) {
3419                                 return !in_array( $entry[2], $sectionIds, true );
3420                         }
3421                 );
3422                 $this->trxPreCommitCallbacks = array_filter(
3423                         $this->trxPreCommitCallbacks,
3424                         function ( $entry ) use ( $sectionIds ) {
3425                                 return !in_array( $entry[2], $sectionIds, true );
3426                         }
3427                 );
3428                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3429                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3430                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3431                                 $callback = $entry[0];
3432                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3433                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3434                                 };
3435                         }
3436                 }
3437         }
3438
3439         final public function setTransactionListener( $name, callable $callback = null ) {
3440                 if ( $callback ) {
3441                         $this->trxRecurringCallbacks[$name] = $callback;
3442                 } else {
3443                         unset( $this->trxRecurringCallbacks[$name] );
3444                 }
3445         }
3446
3447         /**
3448          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3449          *
3450          * This method should not be used outside of Database/LoadBalancer
3451          *
3452          * @param bool $suppress
3453          * @since 1.28
3454          */
3455         final public function setTrxEndCallbackSuppression( $suppress ) {
3456                 $this->trxEndCallbacksSuppressed = $suppress;
3457         }
3458
3459         /**
3460          * Actually consume and run any "on transaction idle/resolution" callbacks.
3461          *
3462          * This method should not be used outside of Database/LoadBalancer
3463          *
3464          * @param int $trigger IDatabase::TRIGGER_* constant
3465          * @return int Number of callbacks attempted
3466          * @since 1.20
3467          * @throws Exception
3468          */
3469         public function runOnTransactionIdleCallbacks( $trigger ) {
3470                 if ( $this->trxLevel ) { // sanity
3471                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3472                 }
3473
3474                 if ( $this->trxEndCallbacksSuppressed ) {
3475                         return 0;
3476                 }
3477
3478                 $count = 0;
3479                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3480                 /** @var Exception $e */
3481                 $e = null; // first exception
3482                 do { // callbacks may add callbacks :)
3483                         $callbacks = array_merge(
3484                                 $this->trxIdleCallbacks,
3485                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3486                         );
3487                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3488                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3489                         foreach ( $callbacks as $callback ) {
3490                                 ++$count;
3491                                 list( $phpCallback ) = $callback;
3492                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3493                                 try {
3494                                         call_user_func( $phpCallback, $trigger, $this );
3495                                 } catch ( Exception $ex ) {
3496                                         call_user_func( $this->errorLogger, $ex );
3497                                         $e = $e ?: $ex;
3498                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3499                                         // their transactions are ended so other callbacks don't fail
3500                                         if ( $this->trxLevel() ) {
3501                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3502                                         }
3503                                 } finally {
3504                                         if ( $autoTrx ) {
3505                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3506                                         } else {
3507                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3508                                         }
3509                                 }
3510                         }
3511                 } while ( count( $this->trxIdleCallbacks ) );
3512
3513                 if ( $e instanceof Exception ) {
3514                         throw $e; // re-throw any first exception
3515                 }
3516
3517                 return $count;
3518         }
3519
3520         /**
3521          * Actually consume and run any "on transaction pre-commit" callbacks.
3522          *
3523          * This method should not be used outside of Database/LoadBalancer
3524          *
3525          * @since 1.22
3526          * @return int Number of callbacks attempted
3527          * @throws Exception
3528          */
3529         public function runOnTransactionPreCommitCallbacks() {
3530                 $count = 0;
3531
3532                 $e = null; // first exception
3533                 do { // callbacks may add callbacks :)
3534                         $callbacks = $this->trxPreCommitCallbacks;
3535                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3536                         foreach ( $callbacks as $callback ) {
3537                                 try {
3538                                         ++$count;
3539                                         list( $phpCallback ) = $callback;
3540                                         $phpCallback( $this );
3541                                 } catch ( Exception $ex ) {
3542                                         ( $this->errorLogger )( $ex );
3543                                         $e = $e ?: $ex;
3544                                 }
3545                         }
3546                 } while ( count( $this->trxPreCommitCallbacks ) );
3547
3548                 if ( $e instanceof Exception ) {
3549                         throw $e; // re-throw any first exception
3550                 }
3551
3552                 return $count;
3553         }
3554
3555         /**
3556          * Actually run any "transaction listener" callbacks.
3557          *
3558          * This method should not be used outside of Database/LoadBalancer
3559          *
3560          * @param int $trigger IDatabase::TRIGGER_* constant
3561          * @throws Exception
3562          * @since 1.20
3563          */
3564         public function runTransactionListenerCallbacks( $trigger ) {
3565                 if ( $this->trxEndCallbacksSuppressed ) {
3566                         return;
3567                 }
3568
3569                 /** @var Exception $e */
3570                 $e = null; // first exception
3571
3572                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3573                         try {
3574                                 $phpCallback( $trigger, $this );
3575                         } catch ( Exception $ex ) {
3576                                 ( $this->errorLogger )( $ex );
3577                                 $e = $e ?: $ex;
3578                         }
3579                 }
3580
3581                 if ( $e instanceof Exception ) {
3582                         throw $e; // re-throw any first exception
3583                 }
3584         }
3585
3586         /**
3587          * Create a savepoint
3588          *
3589          * This is used internally to implement atomic sections. It should not be
3590          * used otherwise.
3591          *
3592          * @since 1.31
3593          * @param string $identifier Identifier for the savepoint
3594          * @param string $fname Calling function name
3595          */
3596         protected function doSavepoint( $identifier, $fname ) {
3597                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3598         }
3599
3600         /**
3601          * Release a savepoint
3602          *
3603          * This is used internally to implement atomic sections. It should not be
3604          * used otherwise.
3605          *
3606          * @since 1.31
3607          * @param string $identifier Identifier for the savepoint
3608          * @param string $fname Calling function name
3609          */
3610         protected function doReleaseSavepoint( $identifier, $fname ) {
3611                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3612         }
3613
3614         /**
3615          * Rollback to a savepoint
3616          *
3617          * This is used internally to implement atomic sections. It should not be
3618          * used otherwise.
3619          *
3620          * @since 1.31
3621          * @param string $identifier Identifier for the savepoint
3622          * @param string $fname Calling function name
3623          */
3624         protected function doRollbackToSavepoint( $identifier, $fname ) {
3625                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3626         }
3627
3628         /**
3629          * @param string $fname
3630          * @return string
3631          */
3632         private function nextSavepointId( $fname ) {
3633                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3634                 if ( strlen( $savepointId ) > 30 ) {
3635                         // 30 == Oracle's identifier length limit (pre 12c)
3636                         // With a 22 character prefix, that puts the highest number at 99999999.
3637                         throw new DBUnexpectedError(
3638                                 $this,
3639                                 'There have been an excessively large number of atomic sections in a transaction'
3640                                 . " started by $this->trxFname (at $fname)"
3641                         );
3642                 }
3643
3644                 return $savepointId;
3645         }
3646
3647         final public function startAtomic(
3648                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3649         ) {
3650                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3651
3652                 if ( !$this->trxLevel ) {
3653                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3654                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3655                         // in all changes being in one transaction to keep requests transactional.
3656                         if ( $this->getFlag( self::DBO_TRX ) ) {
3657                                 // Since writes could happen in between the topmost atomic sections as part
3658                                 // of the transaction, those sections will need savepoints.
3659                                 $savepointId = $this->nextSavepointId( $fname );
3660                                 $this->doSavepoint( $savepointId, $fname );
3661                         } else {
3662                                 $this->trxAutomaticAtomic = true;
3663                         }
3664                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3665                         $savepointId = $this->nextSavepointId( $fname );
3666                         $this->doSavepoint( $savepointId, $fname );
3667                 }
3668
3669                 $sectionId = new AtomicSectionIdentifier;
3670                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3671
3672                 return $sectionId;
3673         }
3674
3675         final public function endAtomic( $fname = __METHOD__ ) {
3676                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3677                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3678                 }
3679
3680                 // Check if the current section matches $fname
3681                 $pos = count( $this->trxAtomicLevels ) - 1;
3682                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3683
3684                 if ( $savedFname !== $fname ) {
3685                         throw new DBUnexpectedError(
3686                                 $this,
3687                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3688                         );
3689                 }
3690
3691                 // Remove the last section (no need to re-index the array)
3692                 array_pop( $this->trxAtomicLevels );
3693
3694                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3695                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3696                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3697                         $this->doReleaseSavepoint( $savepointId, $fname );
3698                 }
3699
3700                 // Hoist callback ownership for callbacks in the section that just ended;
3701                 // all callbacks should have an owner that is present in trxAtomicLevels.
3702                 $currentSectionId = $this->currentAtomicSectionId();
3703                 if ( $currentSectionId ) {
3704                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3705                 }
3706         }
3707
3708         final public function cancelAtomic(
3709                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3710         ) {
3711                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3712                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3713                 }
3714
3715                 if ( $sectionId !== null ) {
3716                         // Find the (last) section with the given $sectionId
3717                         $pos = -1;
3718                         foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3719                                 if ( $asId === $sectionId ) {
3720                                         $pos = $i;
3721                                 }
3722                         }
3723                         if ( $pos < 0 ) {
3724                                 throw new DBUnexpectedError( "Atomic section not found (for $fname)" );
3725                         }
3726                         // Remove all descendant sections and re-index the array
3727                         $excisedIds = [];
3728                         $len = count( $this->trxAtomicLevels );
3729                         for ( $i = $pos + 1; $i < $len; ++$i ) {
3730                                 $excisedIds[] = $this->trxAtomicLevels[$i][1];
3731                         }
3732                         $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3733                         $this->modifyCallbacksForCancel( $excisedIds );
3734                 }
3735
3736                 // Check if the current section matches $fname
3737                 $pos = count( $this->trxAtomicLevels ) - 1;
3738                 list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3739
3740                 if ( $savedFname !== $fname ) {
3741                         throw new DBUnexpectedError(
3742                                 $this,
3743                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3744                         );
3745                 }
3746
3747                 // Remove the last section (no need to re-index the array)
3748                 array_pop( $this->trxAtomicLevels );
3749                 $this->modifyCallbacksForCancel( [ $savedSectionId ] );
3750
3751                 if ( $savepointId !== null ) {
3752                         // Rollback the transaction to the state just before this atomic section
3753                         if ( $savepointId === self::$NOT_APPLICABLE ) {
3754                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
3755                         } else {
3756                                 $this->doRollbackToSavepoint( $savepointId, $fname );
3757                                 $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3758                                 $this->trxStatusIgnoredCause = null;
3759                         }
3760                 } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3761                         // Put the transaction into an error state if it's not already in one
3762                         $this->trxStatus = self::STATUS_TRX_ERROR;
3763                         $this->trxStatusCause = new DBUnexpectedError(
3764                                 $this,
3765                                 "Uncancelable atomic section canceled (got $fname)."
3766                         );
3767                 }
3768
3769                 $this->affectedRowCount = 0; // for the sake of consistency
3770         }
3771
3772         final public function doAtomicSection(
3773                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3774         ) {
3775                 $sectionId = $this->startAtomic( $fname, $cancelable );
3776                 try {
3777                         $res = $callback( $this, $fname );
3778                 } catch ( Exception $e ) {
3779                         $this->cancelAtomic( $fname, $sectionId );
3780
3781                         throw $e;
3782                 }
3783                 $this->endAtomic( $fname );
3784
3785                 return $res;
3786         }
3787
3788         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3789                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3790                 if ( !in_array( $mode, $modes, true ) ) {
3791                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3792                 }
3793
3794                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3795                 if ( $this->trxLevel ) {
3796                         if ( $this->trxAtomicLevels ) {
3797                                 $levels = $this->flatAtomicSectionList();
3798                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3799                                 throw new DBUnexpectedError( $this, $msg );
3800                         } elseif ( !$this->trxAutomatic ) {
3801                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3802                                 throw new DBUnexpectedError( $this, $msg );
3803                         } else {
3804                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3805                                 throw new DBUnexpectedError( $this, $msg );
3806                         }
3807                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3808                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3809                         throw new DBUnexpectedError( $this, $msg );
3810                 }
3811
3812                 // Avoid fatals if close() was called
3813                 $this->assertOpen();
3814
3815                 $this->doBegin( $fname );
3816                 $this->trxStatus = self::STATUS_TRX_OK;
3817                 $this->trxStatusIgnoredCause = null;
3818                 $this->trxAtomicCounter = 0;
3819                 $this->trxTimestamp = microtime( true );
3820                 $this->trxFname = $fname;
3821                 $this->trxDoneWrites = false;
3822                 $this->trxAutomaticAtomic = false;
3823                 $this->trxAtomicLevels = [];
3824                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3825                 $this->trxWriteDuration = 0.0;
3826                 $this->trxWriteQueryCount = 0;
3827                 $this->trxWriteAffectedRows = 0;
3828                 $this->trxWriteAdjDuration = 0.0;
3829                 $this->trxWriteAdjQueryCount = 0;
3830                 $this->trxWriteCallers = [];
3831                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3832                 // Get an estimate of the replication lag before any such queries.
3833                 $this->trxReplicaLag = null; // clear cached value first
3834                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3835                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3836                 // caller will think its OK to muck around with the transaction just because startAtomic()
3837                 // has not yet completed (e.g. setting trxAtomicLevels).
3838                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3839         }
3840
3841         /**
3842          * Issues the BEGIN command to the database server.
3843          *
3844          * @see Database::begin()
3845          * @param string $fname
3846          */
3847         protected function doBegin( $fname ) {
3848                 $this->query( 'BEGIN', $fname );
3849                 $this->trxLevel = 1;
3850         }
3851
3852         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3853                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3854                 if ( !in_array( $flush, $modes, true ) ) {
3855                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3856                 }
3857
3858                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3859                         // There are still atomic sections open; this cannot be ignored
3860                         $levels = $this->flatAtomicSectionList();
3861                         throw new DBUnexpectedError(
3862                                 $this,
3863                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3864                         );
3865                 }
3866
3867                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3868                         if ( !$this->trxLevel ) {
3869                                 return; // nothing to do
3870                         } elseif ( !$this->trxAutomatic ) {
3871                                 throw new DBUnexpectedError(
3872                                         $this,
3873                                         "$fname: Flushing an explicit transaction, getting out of sync."
3874                                 );
3875                         }
3876                 } else {
3877                         if ( !$this->trxLevel ) {
3878                                 $this->queryLogger->error(
3879                                         "$fname: No transaction to commit, something got out of sync." );
3880                                 return; // nothing to do
3881                         } elseif ( $this->trxAutomatic ) {
3882                                 throw new DBUnexpectedError(
3883                                         $this,
3884                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3885                                 );
3886                         }
3887                 }
3888
3889                 // Avoid fatals if close() was called
3890                 $this->assertOpen();
3891
3892                 $this->runOnTransactionPreCommitCallbacks();
3893
3894                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3895                 $this->doCommit( $fname );
3896                 $this->trxStatus = self::STATUS_TRX_NONE;
3897
3898                 if ( $this->trxDoneWrites ) {
3899                         $this->lastWriteTime = microtime( true );
3900                         $this->trxProfiler->transactionWritingOut(
3901                                 $this->server,
3902                                 $this->getDomainID(),
3903                                 $this->trxShortId,
3904                                 $writeTime,
3905                                 $this->trxWriteAffectedRows
3906                         );
3907                 }
3908
3909                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3910                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
3911                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3912                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3913                 }
3914         }
3915
3916         /**
3917          * Issues the COMMIT command to the database server.
3918          *
3919          * @see Database::commit()
3920          * @param string $fname
3921          */
3922         protected function doCommit( $fname ) {
3923                 if ( $this->trxLevel ) {
3924                         $this->query( 'COMMIT', $fname );
3925                         $this->trxLevel = 0;
3926                 }
3927         }
3928
3929         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3930                 $trxActive = $this->trxLevel;
3931
3932                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3933                         if ( $this->getFlag( self::DBO_TRX ) ) {
3934                                 throw new DBUnexpectedError(
3935                                         $this,
3936                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3937                                 );
3938                         }
3939                 }
3940
3941                 if ( $trxActive ) {
3942                         // Avoid fatals if close() was called
3943                         $this->assertOpen();
3944
3945                         $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3946                         $this->doRollback( $fname );
3947                         $this->trxStatus = self::STATUS_TRX_NONE;
3948                         $this->trxAtomicLevels = [];
3949
3950                         if ( $this->trxDoneWrites ) {
3951                                 $this->trxProfiler->transactionWritingOut(
3952                                         $this->server,
3953                                         $this->getDomainID(),
3954                                         $this->trxShortId,
3955                                         $writeTime,
3956                                         $this->trxWriteAffectedRows
3957                                 );
3958                         }
3959                 }
3960
3961                 // Clear any commit-dependant callbacks. They might even be present
3962                 // only due to transaction rounds, with no SQL transaction being active
3963                 $this->trxIdleCallbacks = [];
3964                 $this->trxPreCommitCallbacks = [];
3965
3966                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3967                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
3968                         try {
3969                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3970                         } catch ( Exception $e ) {
3971                                 // already logged; finish and let LoadBalancer move on during mass-rollback
3972                         }
3973                         try {
3974                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3975                         } catch ( Exception $e ) {
3976                                 // already logged; let LoadBalancer move on during mass-rollback
3977                         }
3978
3979                         $this->affectedRowCount = 0; // for the sake of consistency
3980                 }
3981         }
3982
3983         /**
3984          * Issues the ROLLBACK command to the database server.
3985          *
3986          * @see Database::rollback()
3987          * @param string $fname
3988          */
3989         protected function doRollback( $fname ) {
3990                 if ( $this->trxLevel ) {
3991                         # Disconnects cause rollback anyway, so ignore those errors
3992                         $ignoreErrors = true;
3993                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3994                         $this->trxLevel = 0;
3995                 }
3996         }
3997
3998         public function flushSnapshot( $fname = __METHOD__ ) {
3999                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
4000                         // This only flushes transactions to clear snapshots, not to write data
4001                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4002                         throw new DBUnexpectedError(
4003                                 $this,
4004                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
4005                         );
4006                 }
4007
4008                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4009         }
4010
4011         public function explicitTrxActive() {
4012                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4013         }
4014
4015         public function duplicateTableStructure(
4016                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4017         ) {
4018                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4019         }
4020
4021         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4022                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4023         }
4024
4025         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4026                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4027         }
4028
4029         public function timestamp( $ts = 0 ) {
4030                 $t = new ConvertibleTimestamp( $ts );
4031                 // Let errors bubble up to avoid putting garbage in the DB
4032                 return $t->getTimestamp( TS_MW );
4033         }
4034
4035         public function timestampOrNull( $ts = null ) {
4036                 if ( is_null( $ts ) ) {
4037                         return null;
4038                 } else {
4039                         return $this->timestamp( $ts );
4040                 }
4041         }
4042
4043         public function affectedRows() {
4044                 return ( $this->affectedRowCount === null )
4045                         ? $this->fetchAffectedRowCount() // default to driver value
4046                         : $this->affectedRowCount;
4047         }
4048
4049         /**
4050          * @return int Number of retrieved rows according to the driver
4051          */
4052         abstract protected function fetchAffectedRowCount();
4053
4054         /**
4055          * Take the result from a query, and wrap it in a ResultWrapper if
4056          * necessary. Boolean values are passed through as is, to indicate success
4057          * of write queries or failure.
4058          *
4059          * Once upon a time, Database::query() returned a bare MySQL result
4060          * resource, and it was necessary to call this function to convert it to
4061          * a wrapper. Nowadays, raw database objects are never exposed to external
4062          * callers, so this is unnecessary in external code.
4063          *
4064          * @param bool|ResultWrapper|resource $result
4065          * @return bool|ResultWrapper
4066          */
4067         protected function resultObject( $result ) {
4068                 if ( !$result ) {
4069                         return false;
4070                 } elseif ( $result instanceof ResultWrapper ) {
4071                         return $result;
4072                 } elseif ( $result === true ) {
4073                         // Successful write query
4074                         return $result;
4075                 } else {
4076                         return new ResultWrapper( $this, $result );
4077                 }
4078         }
4079
4080         public function ping( &$rtt = null ) {
4081                 // Avoid hitting the server if it was hit recently
4082                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
4083                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
4084                                 $rtt = $this->rttEstimate;
4085                                 return true; // don't care about $rtt
4086                         }
4087                 }
4088
4089                 // This will reconnect if possible or return false if not
4090                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4091                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
4092                 $this->restoreFlags( self::RESTORE_PRIOR );
4093
4094                 if ( $ok ) {
4095                         $rtt = $this->rttEstimate;
4096                 }
4097
4098                 return $ok;
4099         }
4100
4101         /**
4102          * Close any existing (dead) database connection and open a new connection
4103          *
4104          * @param string $fname
4105          * @return bool True if new connection is opened successfully, false if error
4106          */
4107         protected function replaceLostConnection( $fname ) {
4108                 $this->closeConnection();
4109                 $this->opened = false;
4110                 $this->conn = false;
4111                 try {
4112                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4113                         $this->lastPing = microtime( true );
4114                         $ok = true;
4115
4116                         $this->connLogger->warning(
4117                                 $fname . ': lost connection to {dbserver}; reconnected',
4118                                 [
4119                                         'dbserver' => $this->getServer(),
4120                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4121                                 ]
4122                         );
4123                 } catch ( DBConnectionError $e ) {
4124                         $ok = false;
4125
4126                         $this->connLogger->error(
4127                                 $fname . ': lost connection to {dbserver} permanently',
4128                                 [ 'dbserver' => $this->getServer() ]
4129                         );
4130                 }
4131
4132                 $this->handleSessionLoss();
4133
4134                 return $ok;
4135         }
4136
4137         public function getSessionLagStatus() {
4138                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4139         }
4140
4141         /**
4142          * Get the replica DB lag when the current transaction started
4143          *
4144          * This is useful when transactions might use snapshot isolation
4145          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4146          * is this lag plus transaction duration. If they don't, it is still
4147          * safe to be pessimistic. This returns null if there is no transaction.
4148          *
4149          * This returns null if the lag status for this transaction was not yet recorded.
4150          *
4151          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4152          * @since 1.27
4153          */
4154         final protected function getRecordedTransactionLagStatus() {
4155                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4156                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4157                         : null;
4158         }
4159
4160         /**
4161          * Get a replica DB lag estimate for this server
4162          *
4163          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4164          * @since 1.27
4165          */
4166         protected function getApproximateLagStatus() {
4167                 return [
4168                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4169                         'since' => microtime( true )
4170                 ];
4171         }
4172
4173         /**
4174          * Merge the result of getSessionLagStatus() for several DBs
4175          * using the most pessimistic values to estimate the lag of
4176          * any data derived from them in combination
4177          *
4178          * This is information is useful for caching modules
4179          *
4180          * @see WANObjectCache::set()
4181          * @see WANObjectCache::getWithSetCallback()
4182          *
4183          * @param IDatabase $db1
4184          * @param IDatabase|null $db2 [optional]
4185          * @return array Map of values:
4186          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4187          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4188          *   - pending: whether any of the DBs have uncommitted changes
4189          * @throws DBError
4190          * @since 1.27
4191          */
4192         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4193                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4194                 foreach ( func_get_args() as $db ) {
4195                         /** @var IDatabase $db */
4196                         $status = $db->getSessionLagStatus();
4197                         if ( $status['lag'] === false ) {
4198                                 $res['lag'] = false;
4199                         } elseif ( $res['lag'] !== false ) {
4200                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4201                         }
4202                         $res['since'] = min( $res['since'], $status['since'] );
4203                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4204                 }
4205
4206                 return $res;
4207         }
4208
4209         public function getLag() {
4210                 return 0;
4211         }
4212
4213         public function maxListLen() {
4214                 return 0;
4215         }
4216
4217         public function encodeBlob( $b ) {
4218                 return $b;
4219         }
4220
4221         public function decodeBlob( $b ) {
4222                 if ( $b instanceof Blob ) {
4223                         $b = $b->fetch();
4224                 }
4225                 return $b;
4226         }
4227
4228         public function setSessionOptions( array $options ) {
4229         }
4230
4231         public function sourceFile(
4232                 $filename,
4233                 callable $lineCallback = null,
4234                 callable $resultCallback = null,
4235                 $fname = false,
4236                 callable $inputCallback = null
4237         ) {
4238                 Wikimedia\suppressWarnings();
4239                 $fp = fopen( $filename, 'r' );
4240                 Wikimedia\restoreWarnings();
4241
4242                 if ( false === $fp ) {
4243                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4244                 }
4245
4246                 if ( !$fname ) {
4247                         $fname = __METHOD__ . "( $filename )";
4248                 }
4249
4250                 try {
4251                         $error = $this->sourceStream(
4252                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4253                 } catch ( Exception $e ) {
4254                         fclose( $fp );
4255                         throw $e;
4256                 }
4257
4258                 fclose( $fp );
4259
4260                 return $error;
4261         }
4262
4263         public function setSchemaVars( $vars ) {
4264                 $this->schemaVars = $vars;
4265         }
4266
4267         public function sourceStream(
4268                 $fp,
4269                 callable $lineCallback = null,
4270                 callable $resultCallback = null,
4271                 $fname = __METHOD__,
4272                 callable $inputCallback = null
4273         ) {
4274                 $delimiterReset = new ScopedCallback(
4275                         function ( $delimiter ) {
4276                                 $this->delimiter = $delimiter;
4277                         },
4278                         [ $this->delimiter ]
4279                 );
4280                 $cmd = '';
4281
4282                 while ( !feof( $fp ) ) {
4283                         if ( $lineCallback ) {
4284                                 call_user_func( $lineCallback );
4285                         }
4286
4287                         $line = trim( fgets( $fp ) );
4288
4289                         if ( $line == '' ) {
4290                                 continue;
4291                         }
4292
4293                         if ( '-' == $line[0] && '-' == $line[1] ) {
4294                                 continue;
4295                         }
4296
4297                         if ( $cmd != '' ) {
4298                                 $cmd .= ' ';
4299                         }
4300
4301                         $done = $this->streamStatementEnd( $cmd, $line );
4302
4303                         $cmd .= "$line\n";
4304
4305                         if ( $done || feof( $fp ) ) {
4306                                 $cmd = $this->replaceVars( $cmd );
4307
4308                                 if ( $inputCallback ) {
4309                                         $callbackResult = $inputCallback( $cmd );
4310
4311                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4312                                                 $cmd = $callbackResult;
4313                                         }
4314                                 }
4315
4316                                 if ( $cmd ) {
4317                                         $res = $this->query( $cmd, $fname );
4318
4319                                         if ( $resultCallback ) {
4320                                                 $resultCallback( $res, $this );
4321                                         }
4322
4323                                         if ( false === $res ) {
4324                                                 $err = $this->lastError();
4325
4326                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4327                                         }
4328                                 }
4329                                 $cmd = '';
4330                         }
4331                 }
4332
4333                 ScopedCallback::consume( $delimiterReset );
4334                 return true;
4335         }
4336
4337         /**
4338          * Called by sourceStream() to check if we've reached a statement end
4339          *
4340          * @param string &$sql SQL assembled so far
4341          * @param string &$newLine New line about to be added to $sql
4342          * @return bool Whether $newLine contains end of the statement
4343          */
4344         public function streamStatementEnd( &$sql, &$newLine ) {
4345                 if ( $this->delimiter ) {
4346                         $prev = $newLine;
4347                         $newLine = preg_replace(
4348                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4349                         if ( $newLine != $prev ) {
4350                                 return true;
4351                         }
4352                 }
4353
4354                 return false;
4355         }
4356
4357         /**
4358          * Database independent variable replacement. Replaces a set of variables
4359          * in an SQL statement with their contents as given by $this->getSchemaVars().
4360          *
4361          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4362          *
4363          * - '{$var}' should be used for text and is passed through the database's
4364          *   addQuotes method.
4365          * - `{$var}` should be used for identifiers (e.g. table and database names).
4366          *   It is passed through the database's addIdentifierQuotes method which
4367          *   can be overridden if the database uses something other than backticks.
4368          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4369          *   database's tableName method.
4370          * - / *i* / passes the name that follows through the database's indexName method.
4371          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4372          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4373          *
4374          * @param string $ins SQL statement to replace variables in
4375          * @return string The new SQL statement with variables replaced
4376          */
4377         protected function replaceVars( $ins ) {
4378                 $vars = $this->getSchemaVars();
4379                 return preg_replace_callback(
4380                         '!
4381                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4382                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4383                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4384                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4385                         !x',
4386                         function ( $m ) use ( $vars ) {
4387                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4388                                 // check for both nonexistent keys *and* the empty string.
4389                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4390                                         if ( $m[1] === 'i' ) {
4391                                                 return $this->indexName( $m[2] );
4392                                         } else {
4393                                                 return $this->tableName( $m[2] );
4394                                         }
4395                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4396                                         return $this->addQuotes( $vars[$m[3]] );
4397                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4398                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4399                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4400                                         return $vars[$m[5]];
4401                                 } else {
4402                                         return $m[0];
4403                                 }
4404                         },
4405                         $ins
4406                 );
4407         }
4408
4409         /**
4410          * Get schema variables. If none have been set via setSchemaVars(), then
4411          * use some defaults from the current object.
4412          *
4413          * @return array
4414          */
4415         protected function getSchemaVars() {
4416                 if ( $this->schemaVars ) {
4417                         return $this->schemaVars;
4418                 } else {
4419                         return $this->getDefaultSchemaVars();
4420                 }
4421         }
4422
4423         /**
4424          * Get schema variables to use if none have been set via setSchemaVars().
4425          *
4426          * Override this in derived classes to provide variables for tables.sql
4427          * and SQL patch files.
4428          *
4429          * @return array
4430          */
4431         protected function getDefaultSchemaVars() {
4432                 return [];
4433         }
4434
4435         public function lockIsFree( $lockName, $method ) {
4436                 // RDBMs methods for checking named locks may or may not count this thread itself.
4437                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4438                 // the behavior choosen by the interface for this method.
4439                 return !isset( $this->namedLocksHeld[$lockName] );
4440         }
4441
4442         public function lock( $lockName, $method, $timeout = 5 ) {
4443                 $this->namedLocksHeld[$lockName] = 1;
4444
4445                 return true;
4446         }
4447
4448         public function unlock( $lockName, $method ) {
4449                 unset( $this->namedLocksHeld[$lockName] );
4450
4451                 return true;
4452         }
4453
4454         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4455                 if ( $this->writesOrCallbacksPending() ) {
4456                         // This only flushes transactions to clear snapshots, not to write data
4457                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4458                         throw new DBUnexpectedError(
4459                                 $this,
4460                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4461                         );
4462                 }
4463
4464                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4465                         return null;
4466                 }
4467
4468                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4469                         if ( $this->trxLevel() ) {
4470                                 // There is a good chance an exception was thrown, causing any early return
4471                                 // from the caller. Let any error handler get a chance to issue rollback().
4472                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4473                                 $this->onTransactionResolution(
4474                                         function () use ( $lockKey, $fname ) {
4475                                                 $this->unlock( $lockKey, $fname );
4476                                         },
4477                                         $fname
4478                                 );
4479                         } else {
4480                                 $this->unlock( $lockKey, $fname );
4481                         }
4482                 } );
4483
4484                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4485
4486                 return $unlocker;
4487         }
4488
4489         public function namedLocksEnqueue() {
4490                 return false;
4491         }
4492
4493         public function tableLocksHaveTransactionScope() {
4494                 return true;
4495         }
4496
4497         final public function lockTables( array $read, array $write, $method ) {
4498                 if ( $this->writesOrCallbacksPending() ) {
4499                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4500                 }
4501
4502                 if ( $this->tableLocksHaveTransactionScope() ) {
4503                         $this->startAtomic( $method );
4504                 }
4505
4506                 return $this->doLockTables( $read, $write, $method );
4507         }
4508
4509         /**
4510          * Helper function for lockTables() that handles the actual table locking
4511          *
4512          * @param array $read Array of tables to lock for read access
4513          * @param array $write Array of tables to lock for write access
4514          * @param string $method Name of caller
4515          * @return true
4516          */
4517         protected function doLockTables( array $read, array $write, $method ) {
4518                 return true;
4519         }
4520
4521         final public function unlockTables( $method ) {
4522                 if ( $this->tableLocksHaveTransactionScope() ) {
4523                         $this->endAtomic( $method );
4524
4525                         return true; // locks released on COMMIT/ROLLBACK
4526                 }
4527
4528                 return $this->doUnlockTables( $method );
4529         }
4530
4531         /**
4532          * Helper function for unlockTables() that handles the actual table unlocking
4533          *
4534          * @param string $method Name of caller
4535          * @return true
4536          */
4537         protected function doUnlockTables( $method ) {
4538                 return true;
4539         }
4540
4541         /**
4542          * Delete a table
4543          * @param string $tableName
4544          * @param string $fName
4545          * @return bool|ResultWrapper
4546          * @since 1.18
4547          */
4548         public function dropTable( $tableName, $fName = __METHOD__ ) {
4549                 if ( !$this->tableExists( $tableName, $fName ) ) {
4550                         return false;
4551                 }
4552                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4553
4554                 return $this->query( $sql, $fName );
4555         }
4556
4557         public function getInfinity() {
4558                 return 'infinity';
4559         }
4560
4561         public function encodeExpiry( $expiry ) {
4562                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4563                         ? $this->getInfinity()
4564                         : $this->timestamp( $expiry );
4565         }
4566
4567         public function decodeExpiry( $expiry, $format = TS_MW ) {
4568                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4569                         return 'infinity';
4570                 }
4571
4572                 return ConvertibleTimestamp::convert( $format, $expiry );
4573         }
4574
4575         public function setBigSelects( $value = true ) {
4576                 // no-op
4577         }
4578
4579         public function isReadOnly() {
4580                 return ( $this->getReadOnlyReason() !== false );
4581         }
4582
4583         /**
4584          * @return string|bool Reason this DB is read-only or false if it is not
4585          */
4586         protected function getReadOnlyReason() {
4587                 $reason = $this->getLBInfo( 'readOnlyReason' );
4588
4589                 return is_string( $reason ) ? $reason : false;
4590         }
4591
4592         public function setTableAliases( array $aliases ) {
4593                 $this->tableAliases = $aliases;
4594         }
4595
4596         public function setIndexAliases( array $aliases ) {
4597                 $this->indexAliases = $aliases;
4598         }
4599
4600         /**
4601          * Get the underlying binding connection handle
4602          *
4603          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4604          * This catches broken callers than catch and ignore disconnection exceptions.
4605          * Unlike checking isOpen(), this is safe to call inside of open().
4606          *
4607          * @return mixed
4608          * @throws DBUnexpectedError
4609          * @since 1.26
4610          */
4611         protected function getBindingHandle() {
4612                 if ( !$this->conn ) {
4613                         throw new DBUnexpectedError(
4614                                 $this,
4615                                 'DB connection was already closed or the connection dropped.'
4616                         );
4617                 }
4618
4619                 return $this->conn;
4620         }
4621
4622         /**
4623          * @since 1.19
4624          * @return string
4625          */
4626         public function __toString() {
4627                 return (string)$this->conn;
4628         }
4629
4630         /**
4631          * Make sure that copies do not share the same client binding handle
4632          * @throws DBConnectionError
4633          */
4634         public function __clone() {
4635                 $this->connLogger->warning(
4636                         "Cloning " . static::class . " is not recommended; forking connection:\n" .
4637                         ( new RuntimeException() )->getTraceAsString()
4638                 );
4639
4640                 if ( $this->isOpen() ) {
4641                         // Open a new connection resource without messing with the old one
4642                         $this->opened = false;
4643                         $this->conn = false;
4644                         $this->trxEndCallbacks = []; // don't copy
4645                         $this->handleSessionLoss(); // no trx or locks anymore
4646                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
4647                         $this->lastPing = microtime( true );
4648                 }
4649         }
4650
4651         /**
4652          * Called by serialize. Throw an exception when DB connection is serialized.
4653          * This causes problems on some database engines because the connection is
4654          * not restored on unserialize.
4655          */
4656         public function __sleep() {
4657                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4658                         'the connection is not restored on wakeup.' );
4659         }
4660
4661         /**
4662          * Run a few simple sanity checks and close dangling connections
4663          */
4664         public function __destruct() {
4665                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4666                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4667                 }
4668
4669                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4670                 if ( $danglingWriters ) {
4671                         $fnames = implode( ', ', $danglingWriters );
4672                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4673                 }
4674
4675                 if ( $this->conn ) {
4676                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4677                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4678                         Wikimedia\suppressWarnings();
4679                         $this->closeConnection();
4680                         Wikimedia\restoreWarnings();
4681                         $this->conn = false;
4682                         $this->opened = false;
4683                 }
4684         }
4685 }
4686
4687 /**
4688  * @deprecated since 1.28
4689  */
4690 class_alias( Database::class, 'DatabaseBase' );
4691
4692 /**
4693  * @deprecated since 1.29
4694  */
4695 class_alias( Database::class, 'Database' );