includes/libs/rdbms/database/DatabaseMysqlBase.php

   1 <?php
   2 /**
   3  * This is the MySQL database abstraction layer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23 namespace Wikimedia\Rdbms;
  24
  25 use DateTime;
  26 use DateTimeZone;
  27 use Wikimedia;
  28 use InvalidArgumentException;
  29 use Exception;
  30 use stdClass;
  31
  32 /**
  33  * Database abstraction object for MySQL.
  34  * Defines methods independent on used MySQL extension.
  35  *
  36  * @ingroup Database
  37  * @since 1.22
  38  * @see Database
  39  */
  40 abstract class DatabaseMysqlBase extends Database {
  41         /** @var MysqlMasterPos */
  42         protected $lastKnownReplicaPos;
  43         /** @var string Method to detect replica DB lag */
  44         protected $lagDetectionMethod;
  45         /** @var array Method to detect replica DB lag */
  46         protected $lagDetectionOptions = [];
  47         /** @var bool bool Whether to use GTID methods */
  48         protected $useGTIDs = false;
  49         /** @var string|null */
  50         protected $sslKeyPath;
  51         /** @var string|null */
  52         protected $sslCertPath;
  53         /** @var string|null */
  54         protected $sslCAFile;
  55         /** @var string|null */
  56         protected $sslCAPath;
  57         /** @var string[]|null */
  58         protected $sslCiphers;
  59         /** @var string sql_mode value to send on connection */
  60         protected $sqlMode;
  61         /** @var bool Use experimental UTF-8 transmission encoding */
  62         protected $utf8Mode;
  63         /** @var bool|null */
  64         protected $defaultBigSelects = null;
  65
  66         /** @var string|null */
  67         private $serverVersion = null;
  68         /** @var bool|null */
  69         private $insertSelectIsSafe = null;
  70         /** @var stdClass|null */
  71         private $replicationInfoRow = null;
  72
  73         // Cache getServerId() for 24 hours
  74         const SERVER_ID_CACHE_TTL = 86400;
  75
  76         /** @var float Warn if lag estimates are made for transactions older than this many seconds */
  77         const LAG_STALE_WARN_THRESHOLD = 0.100;
  78
  79         /**
  80          * Additional $params include:
  81          *   - lagDetectionMethod : set to one of (Seconds_Behind_Master,pt-heartbeat).
  82          *       pt-heartbeat assumes the table is at heartbeat.heartbeat
  83          *       and uses UTC timestamps in the heartbeat.ts column.
  84          *       (https://www.percona.com/doc/percona-toolkit/2.2/pt-heartbeat.html)
  85          *   - lagDetectionOptions : if using pt-heartbeat, this can be set to an array map to change
  86          *       the default behavior. Normally, the heartbeat row with the server
  87          *       ID of this server's master will be used. Set the "conds" field to
  88          *       override the query conditions, e.g. ['shard' => 's1'].
  89          *   - useGTIDs : use GTID methods like MASTER_GTID_WAIT() when possible.
  90          *   - insertSelectIsSafe : force that native INSERT SELECT is or is not safe [default: null]
  91          *   - sslKeyPath : path to key file [default: null]
  92          *   - sslCertPath : path to certificate file [default: null]
  93          *   - sslCAFile: path to a single certificate authority PEM file [default: null]
  94          *   - sslCAPath : parth to certificate authority PEM directory [default: null]
  95          *   - sslCiphers : array list of allowable ciphers [default: null]
  96          * @param array $params
  97          */
  98         function __construct( array $params ) {
  99                 $this->lagDetectionMethod = $params['lagDetectionMethod'] ?? 'Seconds_Behind_Master';
 100                 $this->lagDetectionOptions = $params['lagDetectionOptions'] ?? [];
 101                 $this->useGTIDs = !empty( $params['useGTIDs' ] );
 102                 foreach ( [ 'KeyPath', 'CertPath', 'CAFile', 'CAPath', 'Ciphers' ] as $name ) {
 103                         $var = "ssl{$name}";
 104                         if ( isset( $params[$var] ) ) {
 105                                 $this->$var = $params[$var];
 106                         }
 107                 }
 108                 $this->sqlMode = $params['sqlMode'] ?? '';
 109                 $this->utf8Mode = !empty( $params['utf8Mode'] );
 110                 $this->insertSelectIsSafe = isset( $params['insertSelectIsSafe'] )
 111                         ? (bool)$params['insertSelectIsSafe'] : null;
 112
 113                 parent::__construct( $params );
 114         }
 115
 116         /**
 117          * @return string
 118          */
 119         public function getType() {
 120                 return 'mysql';
 121         }
 122
 123         protected function open( $server, $user, $password, $dbName ) {
 124                 # Close/unset connection handle
 125                 $this->close();
 126
 127                 $this->server = $server;
 128                 $this->user = $user;
 129                 $this->password = $password;
 130                 $this->dbName = $dbName;
 131
 132                 $this->installErrorHandler();
 133                 try {
 134                         $this->conn = $this->mysqlConnect( $this->server );
 135                 } catch ( Exception $ex ) {
 136                         $this->restoreErrorHandler();
 137                         throw $ex;
 138                 }
 139                 $error = $this->restoreErrorHandler();
 140
 141                 # Always log connection errors
 142                 if ( !$this->conn ) {
 143                         $error = $error ?: $this->lastError();
 144                         $this->connLogger->error(
 145                                 "Error connecting to {db_server}: {error}",
 146                                 $this->getLogContext( [
 147                                         'method' => __METHOD__,
 148                                         'error' => $error,
 149                                 ] )
 150                         );
 151                         $this->connLogger->debug( "DB connection error\n" .
 152                                 "Server: $server, User: $user, Password: " .
 153                                 substr( $password, 0, 3 ) . "..., error: " . $error . "\n" );
 154
 155                         throw new DBConnectionError( $this, $error );
 156                 }
 157
 158                 if ( strlen( $dbName ) ) {
 159                         Wikimedia\suppressWarnings();
 160                         $success = $this->selectDB( $dbName );
 161                         Wikimedia\restoreWarnings();
 162                         if ( !$success ) {
 163                                 $error = $this->lastError();
 164                                 $this->queryLogger->error(
 165                                         "Error selecting database {db_name} on server {db_server}: {error}",
 166                                         $this->getLogContext( [
 167                                                 'method' => __METHOD__,
 168                                                 'error' => $error,
 169                                         ] )
 170                                 );
 171                                 throw new DBConnectionError( $this, "Error selecting database $dbName: $error" );
 172                         }
 173                 }
 174
 175                 // Tell the server what we're communicating with
 176                 if ( !$this->connectInitCharset() ) {
 177                         $error = $this->lastError();
 178                         $this->queryLogger->error(
 179                                 "Error setting character set: {error}",
 180                                 $this->getLogContext( [
 181                                         'method' => __METHOD__,
 182                                         'error' => $this->lastError(),
 183                                 ] )
 184                         );
 185                         throw new DBConnectionError( $this, "Error setting character set: $error" );
 186                 }
 187
 188                 // Abstract over any insane MySQL defaults
 189                 $set = [ 'group_concat_max_len = 262144' ];
 190                 // Set SQL mode, default is turning them all off, can be overridden or skipped with null
 191                 if ( is_string( $this->sqlMode ) ) {
 192                         $set[] = 'sql_mode = ' . $this->addQuotes( $this->sqlMode );
 193                 }
 194                 // Set any custom settings defined by site config
 195                 // (e.g. https://dev.mysql.com/doc/refman/4.1/en/innodb-parameters.html)
 196                 foreach ( $this->sessionVars as $var => $val ) {
 197                         // Escape strings but not numbers to avoid MySQL complaining
 198                         if ( !is_int( $val ) && !is_float( $val ) ) {
 199                                 $val = $this->addQuotes( $val );
 200                         }
 201                         $set[] = $this->addIdentifierQuotes( $var ) . ' = ' . $val;
 202                 }
 203
 204                 if ( $set ) {
 205                         // Use doQuery() to avoid opening implicit transactions (DBO_TRX)
 206                         $success = $this->doQuery( 'SET ' . implode( ', ', $set ) );
 207                         if ( !$success ) {
 208                                 $error = $this->lastError();
 209                                 $this->queryLogger->error(
 210                                         'Error setting MySQL variables on server {db_server}: {error}',
 211                                         $this->getLogContext( [
 212                                                 'method' => __METHOD__,
 213                                                 'error' => $error,
 214                                         ] )
 215                                 );
 216                                 throw new DBConnectionError( $this, "Error setting MySQL variables: $error" );
 217                         }
 218                 }
 219
 220                 $this->opened = true;
 221
 222                 return true;
 223         }
 224
 225         /**
 226          * Set the character set information right after connection
 227          * @return bool
 228          */
 229         protected function connectInitCharset() {
 230                 if ( $this->utf8Mode ) {
 231                         // Tell the server we're communicating with it in UTF-8.
 232                         // This may engage various charset conversions.
 233                         return $this->mysqlSetCharset( 'utf8' );
 234                 } else {
 235                         return $this->mysqlSetCharset( 'binary' );
 236                 }
 237         }
 238
 239         /**
 240          * Open a connection to a MySQL server
 241          *
 242          * @param string $realServer
 243          * @return mixed Raw connection
 244          * @throws DBConnectionError
 245          */
 246         abstract protected function mysqlConnect( $realServer );
 247
 248         /**
 249          * Set the character set of the MySQL link
 250          *
 251          * @param string $charset
 252          * @return bool
 253          */
 254         abstract protected function mysqlSetCharset( $charset );
 255
 256         /**
 257          * @param ResultWrapper|resource $res
 258          * @throws DBUnexpectedError
 259          */
 260         public function freeResult( $res ) {
 261                 if ( $res instanceof ResultWrapper ) {
 262                         $res = $res->result;
 263                 }
 264                 Wikimedia\suppressWarnings();
 265                 $ok = $this->mysqlFreeResult( $res );
 266                 Wikimedia\restoreWarnings();
 267                 if ( !$ok ) {
 268                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 269                 }
 270         }
 271
 272         /**
 273          * Free result memory
 274          *
 275          * @param resource $res Raw result
 276          * @return bool
 277          */
 278         abstract protected function mysqlFreeResult( $res );
 279
 280         /**
 281          * @param ResultWrapper|resource $res
 282          * @return stdClass|bool
 283          * @throws DBUnexpectedError
 284          */
 285         public function fetchObject( $res ) {
 286                 if ( $res instanceof ResultWrapper ) {
 287                         $res = $res->result;
 288                 }
 289                 Wikimedia\suppressWarnings();
 290                 $row = $this->mysqlFetchObject( $res );
 291                 Wikimedia\restoreWarnings();
 292
 293                 $errno = $this->lastErrno();
 294                 // Unfortunately, mysql_fetch_object does not reset the last errno.
 295                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 296                 // these are the only errors mysql_fetch_object can cause.
 297                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 298                 if ( $errno == 2000 || $errno == 2013 ) {
 299                         throw new DBUnexpectedError(
 300                                 $this,
 301                                 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() )
 302                         );
 303                 }
 304
 305                 return $row;
 306         }
 307
 308         /**
 309          * Fetch a result row as an object
 310          *
 311          * @param resource $res Raw result
 312          * @return stdClass
 313          */
 314         abstract protected function mysqlFetchObject( $res );
 315
 316         /**
 317          * @param IResultWrapper|resource $res
 318          * @return array|bool
 319          * @throws DBUnexpectedError
 320          */
 321         public function fetchRow( $res ) {
 322                 if ( $res instanceof ResultWrapper ) {
 323                         $res = $res->result;
 324                 }
 325                 Wikimedia\suppressWarnings();
 326                 $row = $this->mysqlFetchArray( $res );
 327                 Wikimedia\restoreWarnings();
 328
 329                 $errno = $this->lastErrno();
 330                 // Unfortunately, mysql_fetch_array does not reset the last errno.
 331                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 332                 // these are the only errors mysql_fetch_array can cause.
 333                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 334                 if ( $errno == 2000 || $errno == 2013 ) {
 335                         throw new DBUnexpectedError(
 336                                 $this,
 337                                 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() )
 338                         );
 339                 }
 340
 341                 return $row;
 342         }
 343
 344         /**
 345          * Fetch a result row as an associative and numeric array
 346          *
 347          * @param resource $res Raw result
 348          * @return array
 349          */
 350         abstract protected function mysqlFetchArray( $res );
 351
 352         /**
 353          * @throws DBUnexpectedError
 354          * @param ResultWrapper|resource $res
 355          * @return int
 356          */
 357         function numRows( $res ) {
 358                 if ( $res instanceof ResultWrapper ) {
 359                         $res = $res->result;
 360                 }
 361                 Wikimedia\suppressWarnings();
 362                 $n = !is_bool( $res ) ? $this->mysqlNumRows( $res ) : 0;
 363                 Wikimedia\restoreWarnings();
 364
 365                 // Unfortunately, mysql_num_rows does not reset the last errno.
 366                 // We are not checking for any errors here, since
 367                 // there are no errors mysql_num_rows can cause.
 368                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 369                 // See https://phabricator.wikimedia.org/T44430
 370                 return $n;
 371         }
 372
 373         /**
 374          * Get number of rows in result
 375          *
 376          * @param resource $res Raw result
 377          * @return int
 378          */
 379         abstract protected function mysqlNumRows( $res );
 380
 381         /**
 382          * @param ResultWrapper|resource $res
 383          * @return int
 384          */
 385         public function numFields( $res ) {
 386                 if ( $res instanceof ResultWrapper ) {
 387                         $res = $res->result;
 388                 }
 389
 390                 return $this->mysqlNumFields( $res );
 391         }
 392
 393         /**
 394          * Get number of fields in result
 395          *
 396          * @param resource $res Raw result
 397          * @return int
 398          */
 399         abstract protected function mysqlNumFields( $res );
 400
 401         /**
 402          * @param ResultWrapper|resource $res
 403          * @param int $n
 404          * @return string
 405          */
 406         public function fieldName( $res, $n ) {
 407                 if ( $res instanceof ResultWrapper ) {
 408                         $res = $res->result;
 409                 }
 410
 411                 return $this->mysqlFieldName( $res, $n );
 412         }
 413
 414         /**
 415          * Get the name of the specified field in a result
 416          *
 417          * @param ResultWrapper|resource $res
 418          * @param int $n
 419          * @return string
 420          */
 421         abstract protected function mysqlFieldName( $res, $n );
 422
 423         /**
 424          * mysql_field_type() wrapper
 425          * @param ResultWrapper|resource $res
 426          * @param int $n
 427          * @return string
 428          */
 429         public function fieldType( $res, $n ) {
 430                 if ( $res instanceof ResultWrapper ) {
 431                         $res = $res->result;
 432                 }
 433
 434                 return $this->mysqlFieldType( $res, $n );
 435         }
 436
 437         /**
 438          * Get the type of the specified field in a result
 439          *
 440          * @param ResultWrapper|resource $res
 441          * @param int $n
 442          * @return string
 443          */
 444         abstract protected function mysqlFieldType( $res, $n );
 445
 446         /**
 447          * @param ResultWrapper|resource $res
 448          * @param int $row
 449          * @return bool
 450          */
 451         public function dataSeek( $res, $row ) {
 452                 if ( $res instanceof ResultWrapper ) {
 453                         $res = $res->result;
 454                 }
 455
 456                 return $this->mysqlDataSeek( $res, $row );
 457         }
 458
 459         /**
 460          * Move internal result pointer
 461          *
 462          * @param ResultWrapper|resource $res
 463          * @param int $row
 464          * @return bool
 465          */
 466         abstract protected function mysqlDataSeek( $res, $row );
 467
 468         /**
 469          * @return string
 470          */
 471         public function lastError() {
 472                 if ( $this->conn ) {
 473                         # Even if it's non-zero, it can still be invalid
 474                         Wikimedia\suppressWarnings();
 475                         $error = $this->mysqlError( $this->conn );
 476                         if ( !$error ) {
 477                                 $error = $this->mysqlError();
 478                         }
 479                         Wikimedia\restoreWarnings();
 480                 } else {
 481                         $error = $this->mysqlError();
 482                 }
 483                 if ( $error ) {
 484                         $error .= ' (' . $this->server . ')';
 485                 }
 486
 487                 return $error;
 488         }
 489
 490         /**
 491          * Returns the text of the error message from previous MySQL operation
 492          *
 493          * @param resource|null $conn Raw connection
 494          * @return string
 495          */
 496         abstract protected function mysqlError( $conn = null );
 497
 498         protected function wasQueryTimeout( $error, $errno ) {
 499                 return $errno == 2062;
 500         }
 501
 502         /**
 503          * @param string $table
 504          * @param array $uniqueIndexes
 505          * @param array $rows
 506          * @param string $fname
 507          * @return ResultWrapper
 508          */
 509         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
 510                 return $this->nativeReplace( $table, $rows, $fname );
 511         }
 512
 513         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
 514                 $row = $this->getReplicationSafetyInfo();
 515                 // For row-based-replication, the resulting changes will be relayed, not the query
 516                 if ( $row->binlog_format === 'ROW' ) {
 517                         return true;
 518                 }
 519                 // LIMIT requires ORDER BY on a unique key or it is non-deterministic
 520                 if ( isset( $selectOptions['LIMIT'] ) ) {
 521                         return false;
 522                 }
 523                 // In MySQL, an INSERT SELECT is only replication safe with row-based
 524                 // replication or if innodb_autoinc_lock_mode is 0. When those
 525                 // conditions aren't met, use non-native mode.
 526                 // While we could try to determine if the insert is safe anyway by
 527                 // checking if the target table has an auto-increment column that
 528                 // isn't set in $varMap, that seems unlikely to be worth the extra
 529                 // complexity.
 530                 return (
 531                         in_array( 'NO_AUTO_COLUMNS', $insertOptions ) ||
 532                         (int)$row->innodb_autoinc_lock_mode === 0
 533                 );
 534         }
 535
 536         /**
 537          * @return stdClass Process cached row
 538          */
 539         protected function getReplicationSafetyInfo() {
 540                 if ( $this->replicationInfoRow === null ) {
 541                         $this->replicationInfoRow = $this->selectRow(
 542                                 false,
 543                                 [
 544                                         'innodb_autoinc_lock_mode' => '@@innodb_autoinc_lock_mode',
 545                                         'binlog_format' => '@@binlog_format',
 546                                 ],
 547                                 [],
 548                                 __METHOD__
 549                         );
 550                 }
 551
 552                 return $this->replicationInfoRow;
 553         }
 554
 555         /**
 556          * Estimate rows in dataset
 557          * Returns estimated count, based on EXPLAIN output
 558          * Takes same arguments as Database::select()
 559          *
 560          * @param string|array $table
 561          * @param string|array $var
 562          * @param string|array $conds
 563          * @param string $fname
 564          * @param string|array $options
 565          * @param array $join_conds
 566          * @return bool|int
 567          */
 568         public function estimateRowCount( $table, $var = '*', $conds = '',
 569                 $fname = __METHOD__, $options = [], $join_conds = []
 570         ) {
 571                 $conds = $this->normalizeConditions( $conds, $fname );
 572                 $column = $this->extractSingleFieldFromList( $var );
 573                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 574                         $conds[] = "$column IS NOT NULL";
 575                 }
 576
 577                 $options['EXPLAIN'] = true;
 578                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 579                 if ( $res === false ) {
 580                         return false;
 581                 }
 582                 if ( !$this->numRows( $res ) ) {
 583                         return 0;
 584                 }
 585
 586                 $rows = 1;
 587                 foreach ( $res as $plan ) {
 588                         $rows *= $plan->rows > 0 ? $plan->rows : 1; // avoid resetting to zero
 589                 }
 590
 591                 return (int)$rows;
 592         }
 593
 594         public function tableExists( $table, $fname = __METHOD__ ) {
 595                 // Split database and table into proper variables as Database::tableName() returns
 596                 // shared tables prefixed with their database, which do not work in SHOW TABLES statements
 597                 list( $database, , $prefix, $table ) = $this->qualifiedTableComponents( $table );
 598                 $tableName = "{$prefix}{$table}";
 599
 600                 if ( isset( $this->sessionTempTables[$tableName] ) ) {
 601                         return true; // already known to exist and won't show in SHOW TABLES anyway
 602                 }
 603
 604                 // We can't use buildLike() here, because it specifies an escape character
 605                 // other than the backslash, which is the only one supported by SHOW TABLES
 606                 $encLike = $this->escapeLikeInternal( $tableName, '\\' );
 607
 608                 // If the database has been specified (such as for shared tables), use "FROM"
 609                 if ( $database !== '' ) {
 610                         $encDatabase = $this->addIdentifierQuotes( $database );
 611                         $query = "SHOW TABLES FROM $encDatabase LIKE '$encLike'";
 612                 } else {
 613                         $query = "SHOW TABLES LIKE '$encLike'";
 614                 }
 615
 616                 return $this->query( $query, $fname )->numRows() > 0;
 617         }
 618
 619         /**
 620          * @param string $table
 621          * @param string $field
 622          * @return bool|MySQLField
 623          */
 624         public function fieldInfo( $table, $field ) {
 625                 $table = $this->tableName( $table );
 626                 $res = $this->query( "SELECT * FROM $table LIMIT 1", __METHOD__, true );
 627                 if ( !$res ) {
 628                         return false;
 629                 }
 630                 $n = $this->mysqlNumFields( $res->result );
 631                 for ( $i = 0; $i < $n; $i++ ) {
 632                         $meta = $this->mysqlFetchField( $res->result, $i );
 633                         if ( $field == $meta->name ) {
 634                                 return new MySQLField( $meta );
 635                         }
 636                 }
 637
 638                 return false;
 639         }
 640
 641         /**
 642          * Get column information from a result
 643          *
 644          * @param resource $res Raw result
 645          * @param int $n
 646          * @return stdClass
 647          */
 648         abstract protected function mysqlFetchField( $res, $n );
 649
 650         /**
 651          * Get information about an index into an object
 652          * Returns false if the index does not exist
 653          *
 654          * @param string $table
 655          * @param string $index
 656          * @param string $fname
 657          * @return bool|array|null False or null on failure
 658          */
 659         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 660                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 661                 # SHOW INDEX should work for 3.x and up:
 662                 # https://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 663                 $table = $this->tableName( $table );
 664                 $index = $this->indexName( $index );
 665
 666                 $sql = 'SHOW INDEX FROM ' . $table;
 667                 $res = $this->query( $sql, $fname );
 668
 669                 if ( !$res ) {
 670                         return null;
 671                 }
 672
 673                 $result = [];
 674
 675                 foreach ( $res as $row ) {
 676                         if ( $row->Key_name == $index ) {
 677                                 $result[] = $row;
 678                         }
 679                 }
 680
 681                 return $result ?: false;
 682         }
 683
 684         /**
 685          * @param string $s
 686          * @return string
 687          */
 688         public function strencode( $s ) {
 689                 return $this->mysqlRealEscapeString( $s );
 690         }
 691
 692         /**
 693          * @param string $s
 694          * @return mixed
 695          */
 696         abstract protected function mysqlRealEscapeString( $s );
 697
 698         public function addQuotes( $s ) {
 699                 if ( is_bool( $s ) ) {
 700                         // Parent would transform to int, which does not play nice with MySQL type juggling.
 701                         // When searching for an int in a string column, the strings are cast to int, which
 702                         // means false would match any string not starting with a number.
 703                         $s = (string)(int)$s;
 704                 }
 705                 return parent::addQuotes( $s );
 706         }
 707
 708         /**
 709          * MySQL uses `backticks` for identifier quoting instead of the sql standard "double quotes".
 710          *
 711          * @param string $s
 712          * @return string
 713          */
 714         public function addIdentifierQuotes( $s ) {
 715                 // Characters in the range \u0001-\uFFFF are valid in a quoted identifier
 716                 // Remove NUL bytes and escape backticks by doubling
 717                 return '`' . str_replace( [ "\0", '`' ], [ '', '``' ], $s ) . '`';
 718         }
 719
 720         /**
 721          * @param string $name
 722          * @return bool
 723          */
 724         public function isQuotedIdentifier( $name ) {
 725                 return strlen( $name ) && $name[0] == '`' && substr( $name, -1, 1 ) == '`';
 726         }
 727
 728         public function getLag() {
 729                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 730                         return $this->getLagFromPtHeartbeat();
 731                 } else {
 732                         return $this->getLagFromSlaveStatus();
 733                 }
 734         }
 735
 736         /**
 737          * @return string
 738          */
 739         protected function getLagDetectionMethod() {
 740                 return $this->lagDetectionMethod;
 741         }
 742
 743         /**
 744          * @return bool|int
 745          */
 746         protected function getLagFromSlaveStatus() {
 747                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
 748                 $row = $res ? $res->fetchObject() : false;
 749                 // If the server is not replicating, there will be no row
 750                 if ( $row && strval( $row->Seconds_Behind_Master ) !== '' ) {
 751                         return intval( $row->Seconds_Behind_Master );
 752                 }
 753
 754                 return false;
 755         }
 756
 757         /**
 758          * @return bool|float
 759          */
 760         protected function getLagFromPtHeartbeat() {
 761                 $options = $this->lagDetectionOptions;
 762
 763                 $currentTrxInfo = $this->getRecordedTransactionLagStatus();
 764                 if ( $currentTrxInfo ) {
 765                         // There is an active transaction and the initial lag was already queried
 766                         $staleness = microtime( true ) - $currentTrxInfo['since'];
 767                         if ( $staleness > self::LAG_STALE_WARN_THRESHOLD ) {
 768                                 // Avoid returning higher and higher lag value due to snapshot age
 769                                 // given that the isolation level will typically be REPEATABLE-READ
 770                                 $this->queryLogger->warning(
 771                                         "Using cached lag value for {db_server} due to active transaction",
 772                                         $this->getLogContext( [ 'method' => __METHOD__, 'age' => $staleness ] )
 773                                 );
 774                         }
 775
 776                         return $currentTrxInfo['lag'];
 777                 }
 778
 779                 if ( isset( $options['conds'] ) ) {
 780                         // Best method for multi-DC setups: use logical channel names
 781                         $data = $this->getHeartbeatData( $options['conds'] );
 782                 } else {
 783                         // Standard method: use master server ID (works with stock pt-heartbeat)
 784                         $masterInfo = $this->getMasterServerInfo();
 785                         if ( !$masterInfo ) {
 786                                 $this->queryLogger->error(
 787                                         "Unable to query master of {db_server} for server ID",
 788                                         $this->getLogContext( [
 789                                                 'method' => __METHOD__
 790                                         ] )
 791                                 );
 792
 793                                 return false; // could not get master server ID
 794                         }
 795
 796                         $conds = [ 'server_id' => intval( $masterInfo['serverId'] ) ];
 797                         $data = $this->getHeartbeatData( $conds );
 798                 }
 799
 800                 list( $time, $nowUnix ) = $data;
 801                 if ( $time !== null ) {
 802                         // @time is in ISO format like "2015-09-25T16:48:10.000510"
 803                         $dateTime = new DateTime( $time, new DateTimeZone( 'UTC' ) );
 804                         $timeUnix = (int)$dateTime->format( 'U' ) + $dateTime->format( 'u' ) / 1e6;
 805
 806                         return max( $nowUnix - $timeUnix, 0.0 );
 807                 }
 808
 809                 $this->queryLogger->error(
 810                         "Unable to find pt-heartbeat row for {db_server}",
 811                         $this->getLogContext( [
 812                                 'method' => __METHOD__
 813                         ] )
 814                 );
 815
 816                 return false;
 817         }
 818
 819         protected function getMasterServerInfo() {
 820                 $cache = $this->srvCache;
 821                 $key = $cache->makeGlobalKey(
 822                         'mysql',
 823                         'master-info',
 824                         // Using one key for all cluster replica DBs is preferable
 825                         $this->getLBInfo( 'clusterMasterHost' ) ?: $this->getServer()
 826                 );
 827                 $fname = __METHOD__;
 828
 829                 return $cache->getWithSetCallback(
 830                         $key,
 831                         $cache::TTL_INDEFINITE,
 832                         function () use ( $cache, $key, $fname ) {
 833                                 // Get and leave a lock key in place for a short period
 834                                 if ( !$cache->lock( $key, 0, 10 ) ) {
 835                                         return false; // avoid master connection spike slams
 836                                 }
 837
 838                                 $conn = $this->getLazyMasterHandle();
 839                                 if ( !$conn ) {
 840                                         return false; // something is misconfigured
 841                                 }
 842
 843                                 // Connect to and query the master; catch errors to avoid outages
 844                                 try {
 845                                         $res = $conn->query( 'SELECT @@server_id AS id', $fname );
 846                                         $row = $res ? $res->fetchObject() : false;
 847                                         $id = $row ? (int)$row->id : 0;
 848                                 } catch ( DBError $e ) {
 849                                         $id = 0;
 850                                 }
 851
 852                                 // Cache the ID if it was retrieved
 853                                 return $id ? [ 'serverId' => $id, 'asOf' => time() ] : false;
 854                         }
 855                 );
 856         }
 857
 858         /**
 859          * @param array $conds WHERE clause conditions to find a row
 860          * @return array (heartbeat `ts` column value or null, UNIX timestamp) for the newest beat
 861          * @see https://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html
 862          */
 863         protected function getHeartbeatData( array $conds ) {
 864                 // Query time and trip time are not counted
 865                 $nowUnix = microtime( true );
 866                 // Do not bother starting implicit transactions here
 867                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
 868                 try {
 869                         $whereSQL = $this->makeList( $conds, self::LIST_AND );
 870                         // Use ORDER BY for channel based queries since that field might not be UNIQUE.
 871                         // Note: this would use "TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6))" but the
 872                         // percision field is not supported in MySQL <= 5.5.
 873                         $res = $this->query(
 874                                 "SELECT ts FROM heartbeat.heartbeat WHERE $whereSQL ORDER BY ts DESC LIMIT 1",
 875                                 __METHOD__
 876                         );
 877                         $row = $res ? $res->fetchObject() : false;
 878                 } finally {
 879                         $this->restoreFlags();
 880                 }
 881
 882                 return [ $row ? $row->ts : null, $nowUnix ];
 883         }
 884
 885         protected function getApproximateLagStatus() {
 886                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 887                         // Disable caching since this is fast enough and we don't wan't
 888                         // to be *too* pessimistic by having both the cache TTL and the
 889                         // pt-heartbeat interval count as lag in getSessionLagStatus()
 890                         return parent::getApproximateLagStatus();
 891                 }
 892
 893                 $key = $this->srvCache->makeGlobalKey( 'mysql-lag', $this->getServer() );
 894                 $approxLag = $this->srvCache->get( $key );
 895                 if ( !$approxLag ) {
 896                         $approxLag = parent::getApproximateLagStatus();
 897                         $this->srvCache->set( $key, $approxLag, 1 );
 898                 }
 899
 900                 return $approxLag;
 901         }
 902
 903         public function masterPosWait( DBMasterPos $pos, $timeout ) {
 904                 if ( !( $pos instanceof MySQLMasterPos ) ) {
 905                         throw new InvalidArgumentException( "Position not an instance of MySQLMasterPos" );
 906                 }
 907
 908                 if ( $this->getLBInfo( 'is static' ) === true ) {
 909                         return 0; // this is a copy of a read-only dataset with no master DB
 910                 } elseif ( $this->lastKnownReplicaPos && $this->lastKnownReplicaPos->hasReached( $pos ) ) {
 911                         return 0; // already reached this point for sure
 912                 }
 913
 914                 // Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
 915                 if ( $pos->getGTIDs() ) {
 916                         // Ignore GTIDs from domains exclusive to the master DB (presumably inactive)
 917                         $rpos = $this->getReplicaPos();
 918                         $gtidsWait = $rpos ? MySQLMasterPos::getCommonDomainGTIDs( $pos, $rpos ) : [];
 919                         if ( !$gtidsWait ) {
 920                                 $this->queryLogger->error(
 921                                         "No GTIDs with the same domain between master ($pos) and replica ($rpos)",
 922                                         $this->getLogContext( [
 923                                                 'method' => __METHOD__,
 924                                         ] )
 925                                 );
 926
 927                                 return -1; // $pos is from the wrong cluster?
 928                         }
 929                         // Wait on the GTID set (MariaDB only)
 930                         $gtidArg = $this->addQuotes( implode( ',', $gtidsWait ) );
 931                         if ( strpos( $gtidArg, ':' ) !== false ) {
 932                                 // MySQL GTIDs, e.g "source_id:transaction_id"
 933                                 $res = $this->doQuery( "SELECT WAIT_FOR_EXECUTED_GTID_SET($gtidArg, $timeout)" );
 934                         } else {
 935                                 // MariaDB GTIDs, e.g."domain:server:sequence"
 936                                 $res = $this->doQuery( "SELECT MASTER_GTID_WAIT($gtidArg, $timeout)" );
 937                         }
 938                 } else {
 939                         // Wait on the binlog coordinates
 940                         $encFile = $this->addQuotes( $pos->getLogFile() );
 941                         $encPos = intval( $pos->getLogPosition()[$pos::CORD_EVENT] );
 942                         $res = $this->doQuery( "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)" );
 943                 }
 944
 945                 $row = $res ? $this->fetchRow( $res ) : false;
 946                 if ( !$row ) {
 947                         throw new DBExpectedError( $this, "Replication wait failed: {$this->lastError()}" );
 948                 }
 949
 950                 // Result can be NULL (error), -1 (timeout), or 0+ per the MySQL manual
 951                 $status = ( $row[0] !== null ) ? intval( $row[0] ) : null;
 952                 if ( $status === null ) {
 953                         if ( !$pos->getGTIDs() ) {
 954                                 // T126436: jobs programmed to wait on master positions might be referencing
 955                                 // binlogs with an old master hostname; this makes MASTER_POS_WAIT() return null.
 956                                 // Try to detect this case and treat the replica DB as having reached the given
 957                                 // position (any master switchover already requires that the new master be caught
 958                                 // up before the switch).
 959                                 $replicationPos = $this->getReplicaPos();
 960                                 if ( $replicationPos && !$replicationPos->channelsMatch( $pos ) ) {
 961                                         $this->lastKnownReplicaPos = $replicationPos;
 962                                         $status = 0;
 963                                 }
 964                         }
 965                 } elseif ( $status >= 0 ) {
 966                         // Remember that this position was reached to save queries next time
 967                         $this->lastKnownReplicaPos = $pos;
 968                 }
 969
 970                 return $status;
 971         }
 972
 973         /**
 974          * Get the position of the master from SHOW SLAVE STATUS
 975          *
 976          * @return MySQLMasterPos|bool
 977          */
 978         public function getReplicaPos() {
 979                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
 980
 981                 if ( $this->useGTIDs() ) {
 982                         // Try to use GTIDs, fallbacking to binlog positions if not possible
 983                         $data = $this->getServerGTIDs( __METHOD__ );
 984                         // Use gtid_slave_pos for MariaDB and gtid_executed for MySQL
 985                         foreach ( [ 'gtid_slave_pos', 'gtid_executed' ] as $name ) {
 986                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
 987                                         return new MySQLMasterPos( $data[$name], $now );
 988                                 }
 989                         }
 990                 }
 991
 992                 $data = $this->getServerRoleStatus( 'SLAVE', __METHOD__ );
 993                 if ( $data && strlen( $data['Relay_Master_Log_File'] ) ) {
 994                         return new MySQLMasterPos(
 995                                 "{$data['Relay_Master_Log_File']}/{$data['Exec_Master_Log_Pos']}",
 996                                 $now
 997                         );
 998                 }
 999
1000                 return false;
1001         }
1002
1003         /**
1004          * Get the position of the master from SHOW MASTER STATUS
1005          *
1006          * @return MySQLMasterPos|bool
1007          */
1008         public function getMasterPos() {
1009                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
1010
1011                 $pos = false;
1012                 if ( $this->useGTIDs() ) {
1013                         // Try to use GTIDs, fallbacking to binlog positions if not possible
1014                         $data = $this->getServerGTIDs( __METHOD__ );
1015                         // Use gtid_binlog_pos for MariaDB and gtid_executed for MySQL
1016                         foreach ( [ 'gtid_binlog_pos', 'gtid_executed' ] as $name ) {
1017                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
1018                                         $pos = new MySQLMasterPos( $data[$name], $now );
1019                                         break;
1020                                 }
1021                         }
1022                         // Filter domains that are inactive or not relevant to the session
1023                         if ( $pos ) {
1024                                 $pos->setActiveOriginServerId( $this->getServerId() );
1025                                 $pos->setActiveOriginServerUUID( $this->getServerUUID() );
1026                                 if ( isset( $data['gtid_domain_id'] ) ) {
1027                                         $pos->setActiveDomain( $data['gtid_domain_id'] );
1028                                 }
1029                         }
1030                 }
1031
1032                 if ( !$pos ) {
1033                         $data = $this->getServerRoleStatus( 'MASTER', __METHOD__ );
1034                         if ( $data && strlen( $data['File'] ) ) {
1035                                 $pos = new MySQLMasterPos( "{$data['File']}/{$data['Position']}", $now );
1036                         }
1037                 }
1038
1039                 return $pos;
1040         }
1041
1042         /**
1043          * @return int
1044          * @throws DBQueryError If the variable doesn't exist for some reason
1045          */
1046         protected function getServerId() {
1047                 $fname = __METHOD__;
1048                 return $this->srvCache->getWithSetCallback(
1049                         $this->srvCache->makeGlobalKey( 'mysql-server-id', $this->getServer() ),
1050                         self::SERVER_ID_CACHE_TTL,
1051                         function () use ( $fname ) {
1052                                 $res = $this->query( "SELECT @@server_id AS id", $fname );
1053                                 return intval( $this->fetchObject( $res )->id );
1054                         }
1055                 );
1056         }
1057
1058         /**
1059          * @return string|null
1060          */
1061         protected function getServerUUID() {
1062                 return $this->srvCache->getWithSetCallback(
1063                         $this->srvCache->makeGlobalKey( 'mysql-server-uuid', $this->getServer() ),
1064                         self::SERVER_ID_CACHE_TTL,
1065                         function () {
1066                                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'server_uuid'" );
1067                                 $row = $this->fetchObject( $res );
1068
1069                                 return $row ? $row->Value : null;
1070                         }
1071                 );
1072         }
1073
1074         /**
1075          * @param string $fname
1076          * @return string[]
1077          */
1078         protected function getServerGTIDs( $fname = __METHOD__ ) {
1079                 $map = [];
1080                 // Get global-only variables like gtid_executed
1081                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'gtid_%'", $fname );
1082                 foreach ( $res as $row ) {
1083                         $map[$row->Variable_name] = $row->Value;
1084                 }
1085                 // Get session-specific (e.g. gtid_domain_id since that is were writes will log)
1086                 $res = $this->query( "SHOW SESSION VARIABLES LIKE 'gtid_%'", $fname );
1087                 foreach ( $res as $row ) {
1088                         $map[$row->Variable_name] = $row->Value;
1089                 }
1090
1091                 return $map;
1092         }
1093
1094         /**
1095          * @param string $role One of "MASTER"/"SLAVE"
1096          * @param string $fname
1097          * @return string[] Latest available server status row
1098          */
1099         protected function getServerRoleStatus( $role, $fname = __METHOD__ ) {
1100                 return $this->query( "SHOW $role STATUS", $fname )->fetchRow() ?: [];
1101         }
1102
1103         public function serverIsReadOnly() {
1104                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'read_only'", __METHOD__ );
1105                 $row = $this->fetchObject( $res );
1106
1107                 return $row ? ( strtolower( $row->Value ) === 'on' ) : false;
1108         }
1109
1110         /**
1111          * @param string $index
1112          * @return string
1113          */
1114         function useIndexClause( $index ) {
1115                 return "FORCE INDEX (" . $this->indexName( $index ) . ")";
1116         }
1117
1118         /**
1119          * @param string $index
1120          * @return string
1121          */
1122         function ignoreIndexClause( $index ) {
1123                 return "IGNORE INDEX (" . $this->indexName( $index ) . ")";
1124         }
1125
1126         /**
1127          * @return string
1128          */
1129         function lowPriorityOption() {
1130                 return 'LOW_PRIORITY';
1131         }
1132
1133         /**
1134          * @return string
1135          */
1136         public function getSoftwareLink() {
1137                 // MariaDB includes its name in its version string; this is how MariaDB's version of
1138                 // the mysql command-line client identifies MariaDB servers (see mariadb_connection()
1139                 // in libmysql/libmysql.c).
1140                 $version = $this->getServerVersion();
1141                 if ( strpos( $version, 'MariaDB' ) !== false || strpos( $version, '-maria-' ) !== false ) {
1142                         return '[{{int:version-db-mariadb-url}} MariaDB]';
1143                 }
1144
1145                 // Percona Server's version suffix is not very distinctive, and @@version_comment
1146                 // doesn't give the necessary info for source builds, so assume the server is MySQL.
1147                 // (Even Percona's version of mysql doesn't try to make the distinction.)
1148                 return '[{{int:version-db-mysql-url}} MySQL]';
1149         }
1150
1151         /**
1152          * @return string
1153          */
1154         public function getServerVersion() {
1155                 // Not using mysql_get_server_info() or similar for consistency: in the handshake,
1156                 // MariaDB 10 adds the prefix "5.5.5-", and only some newer client libraries strip
1157                 // it off (see RPL_VERSION_HACK in include/mysql_com.h).
1158                 if ( $this->serverVersion === null ) {
1159                         $this->serverVersion = $this->selectField( '', 'VERSION()', '', __METHOD__ );
1160                 }
1161                 return $this->serverVersion;
1162         }
1163
1164         /**
1165          * @param array $options
1166          */
1167         public function setSessionOptions( array $options ) {
1168                 if ( isset( $options['connTimeout'] ) ) {
1169                         $timeout = (int)$options['connTimeout'];
1170                         $this->query( "SET net_read_timeout=$timeout" );
1171                         $this->query( "SET net_write_timeout=$timeout" );
1172                 }
1173         }
1174
1175         /**
1176          * @param string &$sql
1177          * @param string &$newLine
1178          * @return bool
1179          */
1180         public function streamStatementEnd( &$sql, &$newLine ) {
1181                 if ( strtoupper( substr( $newLine, 0, 9 ) ) == 'DELIMITER' ) {
1182                         preg_match( '/^DELIMITER\s+(\S+)/', $newLine, $m );
1183                         $this->delimiter = $m[1];
1184                         $newLine = '';
1185                 }
1186
1187                 return parent::streamStatementEnd( $sql, $newLine );
1188         }
1189
1190         /**
1191          * Check to see if a named lock is available. This is non-blocking.
1192          *
1193          * @param string $lockName Name of lock to poll
1194          * @param string $method Name of method calling us
1195          * @return bool
1196          * @since 1.20
1197          */
1198         public function lockIsFree( $lockName, $method ) {
1199                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1200                         return false; // already held
1201                 }
1202
1203                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1204                 $result = $this->query( "SELECT IS_FREE_LOCK($encName) AS lockstatus", $method );
1205                 $row = $this->fetchObject( $result );
1206
1207                 return ( $row->lockstatus == 1 );
1208         }
1209
1210         /**
1211          * @param string $lockName
1212          * @param string $method
1213          * @param int $timeout
1214          * @return bool
1215          */
1216         public function lock( $lockName, $method, $timeout = 5 ) {
1217                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1218                 $result = $this->query( "SELECT GET_LOCK($encName, $timeout) AS lockstatus", $method );
1219                 $row = $this->fetchObject( $result );
1220
1221                 if ( $row->lockstatus == 1 ) {
1222                         parent::lock( $lockName, $method, $timeout ); // record
1223                         return true;
1224                 }
1225
1226                 $this->queryLogger->info( __METHOD__ . " failed to acquire lock '{lockname}'",
1227                         [ 'lockname' => $lockName ] );
1228
1229                 return false;
1230         }
1231
1232         /**
1233          * FROM MYSQL DOCS:
1234          * https://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock
1235          * @param string $lockName
1236          * @param string $method
1237          * @return bool
1238          */
1239         public function unlock( $lockName, $method ) {
1240                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1241                 $result = $this->query( "SELECT RELEASE_LOCK($encName) as lockstatus", $method );
1242                 $row = $this->fetchObject( $result );
1243
1244                 if ( $row->lockstatus == 1 ) {
1245                         parent::unlock( $lockName, $method ); // record
1246                         return true;
1247                 }
1248
1249                 $this->queryLogger->warning( __METHOD__ . " failed to release lock '$lockName'\n" );
1250
1251                 return false;
1252         }
1253
1254         private function makeLockName( $lockName ) {
1255                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1256                 // Newer version enforce a 64 char length limit.
1257                 return ( strlen( $lockName ) > 64 ) ? sha1( $lockName ) : $lockName;
1258         }
1259
1260         public function namedLocksEnqueue() {
1261                 return true;
1262         }
1263
1264         public function tableLocksHaveTransactionScope() {
1265                 return false; // tied to TCP connection
1266         }
1267
1268         protected function doLockTables( array $read, array $write, $method ) {
1269                 $items = [];
1270                 foreach ( $write as $table ) {
1271                         $items[] = $this->tableName( $table ) . ' WRITE';
1272                 }
1273                 foreach ( $read as $table ) {
1274                         $items[] = $this->tableName( $table ) . ' READ';
1275                 }
1276
1277                 $sql = "LOCK TABLES " . implode( ',', $items );
1278                 $this->query( $sql, $method );
1279
1280                 return true;
1281         }
1282
1283         protected function doUnlockTables( $method ) {
1284                 $this->query( "UNLOCK TABLES", $method );
1285
1286                 return true;
1287         }
1288
1289         /**
1290          * @param bool $value
1291          */
1292         public function setBigSelects( $value = true ) {
1293                 if ( $value === 'default' ) {
1294                         if ( $this->defaultBigSelects === null ) {
1295                                 # Function hasn't been called before so it must already be set to the default
1296                                 return;
1297                         } else {
1298                                 $value = $this->defaultBigSelects;
1299                         }
1300                 } elseif ( $this->defaultBigSelects === null ) {
1301                         $this->defaultBigSelects =
1302                                 (bool)$this->selectField( false, '@@sql_big_selects', '', __METHOD__ );
1303                 }
1304                 $encValue = $value ? '1' : '0';
1305                 $this->query( "SET sql_big_selects=$encValue", __METHOD__ );
1306         }
1307
1308         /**
1309          * DELETE where the condition is a join. MySql uses multi-table deletes.
1310          * @param string $delTable
1311          * @param string $joinTable
1312          * @param string $delVar
1313          * @param string $joinVar
1314          * @param array|string $conds
1315          * @param bool|string $fname
1316          * @throws DBUnexpectedError
1317          * @return bool|ResultWrapper
1318          */
1319         public function deleteJoin(
1320                 $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__
1321         ) {
1322                 if ( !$conds ) {
1323                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
1324                 }
1325
1326                 $delTable = $this->tableName( $delTable );
1327                 $joinTable = $this->tableName( $joinTable );
1328                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1329
1330                 if ( $conds != '*' ) {
1331                         $sql .= ' AND ' . $this->makeList( $conds, self::LIST_AND );
1332                 }
1333
1334                 return $this->query( $sql, $fname );
1335         }
1336
1337         /**
1338          * @param string $table
1339          * @param array $rows
1340          * @param array $uniqueIndexes
1341          * @param array $set
1342          * @param string $fname
1343          * @return bool
1344          */
1345         public function upsert( $table, array $rows, array $uniqueIndexes,
1346                 array $set, $fname = __METHOD__
1347         ) {
1348                 if ( !count( $rows ) ) {
1349                         return true; // nothing to do
1350                 }
1351
1352                 if ( !is_array( reset( $rows ) ) ) {
1353                         $rows = [ $rows ];
1354                 }
1355
1356                 $table = $this->tableName( $table );
1357                 $columns = array_keys( $rows[0] );
1358
1359                 $sql = "INSERT INTO $table (" . implode( ',', $columns ) . ') VALUES ';
1360                 $rowTuples = [];
1361                 foreach ( $rows as $row ) {
1362                         $rowTuples[] = '(' . $this->makeList( $row ) . ')';
1363                 }
1364                 $sql .= implode( ',', $rowTuples );
1365                 $sql .= " ON DUPLICATE KEY UPDATE " . $this->makeList( $set, self::LIST_SET );
1366
1367                 return (bool)$this->query( $sql, $fname );
1368         }
1369
1370         /**
1371          * Determines how long the server has been up
1372          *
1373          * @return int
1374          */
1375         public function getServerUptime() {
1376                 $vars = $this->getMysqlStatus( 'Uptime' );
1377
1378                 return (int)$vars['Uptime'];
1379         }
1380
1381         /**
1382          * Determines if the last failure was due to a deadlock
1383          *
1384          * @return bool
1385          */
1386         public function wasDeadlock() {
1387                 return $this->lastErrno() == 1213;
1388         }
1389
1390         /**
1391          * Determines if the last failure was due to a lock timeout
1392          *
1393          * @return bool
1394          */
1395         public function wasLockTimeout() {
1396                 return $this->lastErrno() == 1205;
1397         }
1398
1399         /**
1400          * Determines if the last failure was due to the database being read-only.
1401          *
1402          * @return bool
1403          */
1404         public function wasReadOnlyError() {
1405                 return $this->lastErrno() == 1223 ||
1406                         ( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
1407         }
1408
1409         public function wasConnectionError( $errno ) {
1410                 return $errno == 2013 || $errno == 2006;
1411         }
1412
1413         protected function wasKnownStatementRollbackError() {
1414                 $errno = $this->lastErrno();
1415
1416                 if ( $errno === 1205 ) { // lock wait timeout
1417                         // Note that this is uncached to avoid stale values of SET is used
1418                         $row = $this->selectRow(
1419                                 false,
1420                                 [ 'innodb_rollback_on_timeout' => '@@innodb_rollback_on_timeout' ],
1421                                 [],
1422                                 __METHOD__
1423                         );
1424                         // https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
1425                         // https://dev.mysql.com/doc/refman/5.5/en/innodb-parameters.html
1426                         return $row->innodb_rollback_on_timeout ? false : true;
1427                 }
1428
1429                 // See https://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html
1430                 return in_array( $errno, [ 1022, 1216, 1217, 1137 ], true );
1431         }
1432
1433         /**
1434          * @param string $oldName
1435          * @param string $newName
1436          * @param bool $temporary
1437          * @param string $fname
1438          * @return bool
1439          */
1440         public function duplicateTableStructure(
1441                 $oldName, $newName, $temporary = false, $fname = __METHOD__
1442         ) {
1443                 $tmp = $temporary ? 'TEMPORARY ' : '';
1444                 $newName = $this->addIdentifierQuotes( $newName );
1445                 $oldName = $this->addIdentifierQuotes( $oldName );
1446                 $query = "CREATE $tmp TABLE $newName (LIKE $oldName)";
1447
1448                 return $this->query( $query, $fname );
1449         }
1450
1451         /**
1452          * List all tables on the database
1453          *
1454          * @param string|null $prefix Only show tables with this prefix, e.g. mw_
1455          * @param string $fname Calling function name
1456          * @return array
1457          */
1458         public function listTables( $prefix = null, $fname = __METHOD__ ) {
1459                 $result = $this->query( "SHOW TABLES", $fname );
1460
1461                 $endArray = [];
1462
1463                 foreach ( $result as $table ) {
1464                         $vars = get_object_vars( $table );
1465                         $table = array_pop( $vars );
1466
1467                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1468                                 $endArray[] = $table;
1469                         }
1470                 }
1471
1472                 return $endArray;
1473         }
1474
1475         /**
1476          * @param string $tableName
1477          * @param string $fName
1478          * @return bool|ResultWrapper
1479          */
1480         public function dropTable( $tableName, $fName = __METHOD__ ) {
1481                 if ( !$this->tableExists( $tableName, $fName ) ) {
1482                         return false;
1483                 }
1484
1485                 return $this->query( "DROP TABLE IF EXISTS " . $this->tableName( $tableName ), $fName );
1486         }
1487
1488         /**
1489          * Get status information from SHOW STATUS in an associative array
1490          *
1491          * @param string $which
1492          * @return array
1493          */
1494         private function getMysqlStatus( $which = "%" ) {
1495                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1496                 $status = [];
1497
1498                 foreach ( $res as $row ) {
1499                         $status[$row->Variable_name] = $row->Value;
1500                 }
1501
1502                 return $status;
1503         }
1504
1505         /**
1506          * Lists VIEWs in the database
1507          *
1508          * @param string|null $prefix Only show VIEWs with this prefix, eg.
1509          * unit_test_, or $wgDBprefix. Default: null, would return all views.
1510          * @param string $fname Name of calling function
1511          * @return array
1512          * @since 1.22
1513          */
1514         public function listViews( $prefix = null, $fname = __METHOD__ ) {
1515                 // The name of the column containing the name of the VIEW
1516                 $propertyName = 'Tables_in_' . $this->dbName;
1517
1518                 // Query for the VIEWS
1519                 $res = $this->query( 'SHOW FULL TABLES WHERE TABLE_TYPE = "VIEW"' );
1520                 $allViews = [];
1521                 foreach ( $res as $row ) {
1522                         array_push( $allViews, $row->$propertyName );
1523                 }
1524
1525                 if ( is_null( $prefix ) || $prefix === '' ) {
1526                         return $allViews;
1527                 }
1528
1529                 $filteredViews = [];
1530                 foreach ( $allViews as $viewName ) {
1531                         // Does the name of this VIEW start with the table-prefix?
1532                         if ( strpos( $viewName, $prefix ) === 0 ) {
1533                                 array_push( $filteredViews, $viewName );
1534                         }
1535                 }
1536
1537                 return $filteredViews;
1538         }
1539
1540         /**
1541          * Differentiates between a TABLE and a VIEW.
1542          *
1543          * @param string $name Name of the TABLE/VIEW to test
1544          * @param string|null $prefix
1545          * @return bool
1546          * @since 1.22
1547          */
1548         public function isView( $name, $prefix = null ) {
1549                 return in_array( $name, $this->listViews( $prefix ) );
1550         }
1551
1552         protected function isTransactableQuery( $sql ) {
1553                 return parent::isTransactableQuery( $sql ) &&
1554                         !preg_match( '/^SELECT\s+(GET|RELEASE|IS_FREE)_LOCK\(/', $sql );
1555         }
1556
1557         /**
1558          * @param string $field Field or column to cast
1559          * @return string
1560          */
1561         public function buildIntegerCast( $field ) {
1562                 return 'CAST( ' . $field . ' AS SIGNED )';
1563         }
1564
1565         /*
1566          * @return bool Whether GTID support is used (mockable for testing)
1567          */
1568         protected function useGTIDs() {
1569                 return $this->useGTIDs;
1570         }
1571 }
1572
1573 /**
1574  * @deprecated since 1.29
1575  */
1576 class_alias( DatabaseMysqlBase::class, 'DatabaseMysqlBase' );