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