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 RuntimeException;
  31 use stdClass;
  32
  33 /**
  34  * Database abstraction object for MySQL.
  35  * Defines methods independent on used MySQL extension.
  36  *
  37  * @ingroup Database
  38  * @since 1.22
  39  * @see Database
  40  */
  41 abstract class DatabaseMysqlBase extends Database {
  42         /** @var MysqlMasterPos */
  43         protected $lastKnownReplicaPos;
  44         /** @var string Method to detect replica DB lag */
  45         protected $lagDetectionMethod;
  46         /** @var array Method to detect replica DB lag */
  47         protected $lagDetectionOptions = [];
  48         /** @var bool bool Whether to use GTID methods */
  49         protected $useGTIDs = false;
  50         /** @var string|null */
  51         protected $sslKeyPath;
  52         /** @var string|null */
  53         protected $sslCertPath;
  54         /** @var string|null */
  55         protected $sslCAFile;
  56         /** @var string|null */
  57         protected $sslCAPath;
  58         /** @var string[]|null */
  59         protected $sslCiphers;
  60         /** @var string sql_mode value to send on connection */
  61         protected $sqlMode;
  62         /** @var bool Use experimental UTF-8 transmission encoding */
  63         protected $utf8Mode;
  64         /** @var bool|null */
  65         protected $defaultBigSelects = null;
  66
  67         /** @var string|null */
  68         private $serverVersion = null;
  69         /** @var bool|null */
  70         private $insertSelectIsSafe = null;
  71         /** @var stdClass|null */
  72         private $replicationInfoRow = null;
  73
  74         // Cache getServerId() for 24 hours
  75         const SERVER_ID_CACHE_TTL = 86400;
  76
  77         /** @var float Warn if lag estimates are made for transactions older than this many seconds */
  78         const LAG_STALE_WARN_THRESHOLD = 0.100;
  79
  80         /**
  81          * Additional $params include:
  82          *   - lagDetectionMethod : set to one of (Seconds_Behind_Master,pt-heartbeat).
  83          *       pt-heartbeat assumes the table is at heartbeat.heartbeat
  84          *       and uses UTC timestamps in the heartbeat.ts column.
  85          *       (https://www.percona.com/doc/percona-toolkit/2.2/pt-heartbeat.html)
  86          *   - lagDetectionOptions : if using pt-heartbeat, this can be set to an array map to change
  87          *       the default behavior. Normally, the heartbeat row with the server
  88          *       ID of this server's master will be used. Set the "conds" field to
  89          *       override the query conditions, e.g. ['shard' => 's1'].
  90          *   - useGTIDs : use GTID methods like MASTER_GTID_WAIT() when possible.
  91          *   - insertSelectIsSafe : force that native INSERT SELECT is or is not safe [default: null]
  92          *   - sslKeyPath : path to key file [default: null]
  93          *   - sslCertPath : path to certificate file [default: null]
  94          *   - sslCAFile: path to a single certificate authority PEM file [default: null]
  95          *   - sslCAPath : parth to certificate authority PEM directory [default: null]
  96          *   - sslCiphers : array list of allowable ciphers [default: null]
  97          * @param array $params
  98          */
  99         function __construct( array $params ) {
 100                 $this->lagDetectionMethod = $params['lagDetectionMethod'] ?? 'Seconds_Behind_Master';
 101                 $this->lagDetectionOptions = $params['lagDetectionOptions'] ?? [];
 102                 $this->useGTIDs = !empty( $params['useGTIDs' ] );
 103                 foreach ( [ 'KeyPath', 'CertPath', 'CAFile', 'CAPath', 'Ciphers' ] as $name ) {
 104                         $var = "ssl{$name}";
 105                         if ( isset( $params[$var] ) ) {
 106                                 $this->$var = $params[$var];
 107                         }
 108                 }
 109                 $this->sqlMode = $params['sqlMode'] ?? null;
 110                 $this->utf8Mode = !empty( $params['utf8Mode'] );
 111                 $this->insertSelectIsSafe = isset( $params['insertSelectIsSafe'] )
 112                         ? (bool)$params['insertSelectIsSafe'] : null;
 113
 114                 parent::__construct( $params );
 115         }
 116
 117         /**
 118          * @return string
 119          */
 120         public function getType() {
 121                 return 'mysql';
 122         }
 123
 124         protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix ) {
 125                 $this->close();
 126
 127                 if ( $schema !== null ) {
 128                         throw new DBExpectedError( $this, __CLASS__ . ": domain schemas are not supported." );
 129                 }
 130
 131                 $this->server = $server;
 132                 $this->user = $user;
 133                 $this->password = $password;
 134
 135                 $this->installErrorHandler();
 136                 try {
 137                         $this->conn = $this->mysqlConnect( $this->server, $dbName );
 138                 } catch ( Exception $ex ) {
 139                         $this->restoreErrorHandler();
 140                         throw $ex;
 141                 }
 142                 $error = $this->restoreErrorHandler();
 143
 144                 # Always log connection errors
 145                 if ( !$this->conn ) {
 146                         $error = $error ?: $this->lastError();
 147                         $this->connLogger->error(
 148                                 "Error connecting to {db_server}: {error}",
 149                                 $this->getLogContext( [ 'method' => __METHOD__, 'error' => $error ] )
 150                         );
 151                         $this->connLogger->debug( "DB connection error\n" .
 152                                 "Server: $server, User: $user, Password: " .
 153                                 substr( $password, 0, 3 ) . "..., error: " . $error . "\n" );
 154                         throw new DBConnectionError( $this, $error );
 155                 }
 156
 157                 try {
 158                         $this->currentDomain = new DatabaseDomain(
 159                                 strlen( $dbName ) ? $dbName : null,
 160                                 null,
 161                                 $tablePrefix
 162                         );
 163
 164                         // Abstract over any insane MySQL defaults
 165                         $set = [ 'group_concat_max_len = 262144' ];
 166                         // Set SQL mode, default is turning them all off, can be overridden or skipped with null
 167                         if ( is_string( $this->sqlMode ) ) {
 168                                 $set[] = 'sql_mode = ' . $this->addQuotes( $this->sqlMode );
 169                         }
 170                         // Set any custom settings defined by site config
 171                         // (e.g. https://dev.mysql.com/doc/refman/4.1/en/innodb-parameters.html)
 172                         foreach ( $this->connectionVariables as $var => $val ) {
 173                                 // Escape strings but not numbers to avoid MySQL complaining
 174                                 if ( !is_int( $val ) && !is_float( $val ) ) {
 175                                         $val = $this->addQuotes( $val );
 176                                 }
 177                                 $set[] = $this->addIdentifierQuotes( $var ) . ' = ' . $val;
 178                         }
 179
 180                         if ( $set ) {
 181                                 $this->query(
 182                                         'SET ' . implode( ', ', $set ),
 183                                         __METHOD__,
 184                                         self::QUERY_IGNORE_DBO_TRX | self::QUERY_NO_RETRY
 185                                 );
 186                         }
 187                 } catch ( Exception $e ) {
 188                         // Connection was not fully initialized and is not safe for use
 189                         $this->conn = false;
 190                 }
 191
 192                 return true;
 193         }
 194
 195         protected function doSelectDomain( DatabaseDomain $domain ) {
 196                 if ( $domain->getSchema() !== null ) {
 197                         throw new DBExpectedError( $this, __CLASS__ . ": domain schemas are not supported." );
 198                 }
 199
 200                 $database = $domain->getDatabase();
 201                 // A null database means "don't care" so leave it as is and update the table prefix
 202                 if ( $database === null ) {
 203                         $this->currentDomain = new DatabaseDomain(
 204                                 $this->currentDomain->getDatabase(),
 205                                 null,
 206                                 $domain->getTablePrefix()
 207                         );
 208
 209                         return true;
 210                 }
 211
 212                 if ( $database !== $this->getDBname() ) {
 213                         $sql = 'USE ' . $this->addIdentifierQuotes( $database );
 214                         list( $res, $err, $errno ) =
 215                                 $this->executeQuery( $sql, __METHOD__, self::QUERY_IGNORE_DBO_TRX );
 216
 217                         if ( $res === false ) {
 218                                 $this->reportQueryError( $err, $errno, $sql, __METHOD__ );
 219                                 return false; // unreachable
 220                         }
 221                 }
 222
 223                 // Update that domain fields on success (no exception thrown)
 224                 $this->currentDomain = $domain;
 225
 226                 return true;
 227         }
 228
 229         /**
 230          * Open a connection to a MySQL server
 231          *
 232          * @param string $realServer
 233          * @param string|null $dbName
 234          * @return mixed Raw connection
 235          * @throws DBConnectionError
 236          */
 237         abstract protected function mysqlConnect( $realServer, $dbName );
 238
 239         /**
 240          * @param IResultWrapper|resource $res
 241          * @throws DBUnexpectedError
 242          */
 243         public function freeResult( $res ) {
 244                 if ( $res instanceof ResultWrapper ) {
 245                         $res = $res->result;
 246                 }
 247                 Wikimedia\suppressWarnings();
 248                 $ok = $this->mysqlFreeResult( $res );
 249                 Wikimedia\restoreWarnings();
 250                 if ( !$ok ) {
 251                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 252                 }
 253         }
 254
 255         /**
 256          * Free result memory
 257          *
 258          * @param resource $res Raw result
 259          * @return bool
 260          */
 261         abstract protected function mysqlFreeResult( $res );
 262
 263         /**
 264          * @param IResultWrapper|resource $res
 265          * @return stdClass|bool
 266          * @throws DBUnexpectedError
 267          */
 268         public function fetchObject( $res ) {
 269                 if ( $res instanceof ResultWrapper ) {
 270                         $res = $res->result;
 271                 }
 272                 Wikimedia\suppressWarnings();
 273                 $row = $this->mysqlFetchObject( $res );
 274                 Wikimedia\restoreWarnings();
 275
 276                 $errno = $this->lastErrno();
 277                 // Unfortunately, mysql_fetch_object does not reset the last errno.
 278                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 279                 // these are the only errors mysql_fetch_object can cause.
 280                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 281                 if ( $errno == 2000 || $errno == 2013 ) {
 282                         throw new DBUnexpectedError(
 283                                 $this,
 284                                 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() )
 285                         );
 286                 }
 287
 288                 return $row;
 289         }
 290
 291         /**
 292          * Fetch a result row as an object
 293          *
 294          * @param resource $res Raw result
 295          * @return stdClass
 296          */
 297         abstract protected function mysqlFetchObject( $res );
 298
 299         /**
 300          * @param IResultWrapper|resource $res
 301          * @return array|bool
 302          * @throws DBUnexpectedError
 303          */
 304         public function fetchRow( $res ) {
 305                 if ( $res instanceof ResultWrapper ) {
 306                         $res = $res->result;
 307                 }
 308                 Wikimedia\suppressWarnings();
 309                 $row = $this->mysqlFetchArray( $res );
 310                 Wikimedia\restoreWarnings();
 311
 312                 $errno = $this->lastErrno();
 313                 // Unfortunately, mysql_fetch_array does not reset the last errno.
 314                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 315                 // these are the only errors mysql_fetch_array can cause.
 316                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 317                 if ( $errno == 2000 || $errno == 2013 ) {
 318                         throw new DBUnexpectedError(
 319                                 $this,
 320                                 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() )
 321                         );
 322                 }
 323
 324                 return $row;
 325         }
 326
 327         /**
 328          * Fetch a result row as an associative and numeric array
 329          *
 330          * @param resource $res Raw result
 331          * @return array|false
 332          */
 333         abstract protected function mysqlFetchArray( $res );
 334
 335         /**
 336          * @throws DBUnexpectedError
 337          * @param IResultWrapper|resource $res
 338          * @return int
 339          */
 340         function numRows( $res ) {
 341                 if ( $res instanceof ResultWrapper ) {
 342                         $res = $res->result;
 343                 }
 344                 Wikimedia\suppressWarnings();
 345                 $n = !is_bool( $res ) ? $this->mysqlNumRows( $res ) : 0;
 346                 Wikimedia\restoreWarnings();
 347
 348                 // Unfortunately, mysql_num_rows does not reset the last errno.
 349                 // We are not checking for any errors here, since
 350                 // there are no errors mysql_num_rows can cause.
 351                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 352                 // See https://phabricator.wikimedia.org/T44430
 353                 return $n;
 354         }
 355
 356         /**
 357          * Get number of rows in result
 358          *
 359          * @param resource $res Raw result
 360          * @return int
 361          */
 362         abstract protected function mysqlNumRows( $res );
 363
 364         /**
 365          * @param IResultWrapper|resource $res
 366          * @return int
 367          */
 368         public function numFields( $res ) {
 369                 if ( $res instanceof ResultWrapper ) {
 370                         $res = $res->result;
 371                 }
 372
 373                 return $this->mysqlNumFields( $res );
 374         }
 375
 376         /**
 377          * Get number of fields in result
 378          *
 379          * @param resource $res Raw result
 380          * @return int
 381          */
 382         abstract protected function mysqlNumFields( $res );
 383
 384         /**
 385          * @param IResultWrapper|resource $res
 386          * @param int $n
 387          * @return string
 388          */
 389         public function fieldName( $res, $n ) {
 390                 if ( $res instanceof ResultWrapper ) {
 391                         $res = $res->result;
 392                 }
 393
 394                 return $this->mysqlFieldName( $res, $n );
 395         }
 396
 397         /**
 398          * Get the name of the specified field in a result
 399          *
 400          * @param IResultWrapper|resource $res
 401          * @param int $n
 402          * @return string
 403          */
 404         abstract protected function mysqlFieldName( $res, $n );
 405
 406         /**
 407          * mysql_field_type() wrapper
 408          * @param IResultWrapper|resource $res
 409          * @param int $n
 410          * @return string
 411          */
 412         public function fieldType( $res, $n ) {
 413                 if ( $res instanceof ResultWrapper ) {
 414                         $res = $res->result;
 415                 }
 416
 417                 return $this->mysqlFieldType( $res, $n );
 418         }
 419
 420         /**
 421          * Get the type of the specified field in a result
 422          *
 423          * @param IResultWrapper|resource $res
 424          * @param int $n
 425          * @return string
 426          */
 427         abstract protected function mysqlFieldType( $res, $n );
 428
 429         /**
 430          * @param IResultWrapper|resource $res
 431          * @param int $row
 432          * @return bool
 433          */
 434         public function dataSeek( $res, $row ) {
 435                 if ( $res instanceof ResultWrapper ) {
 436                         $res = $res->result;
 437                 }
 438
 439                 return $this->mysqlDataSeek( $res, $row );
 440         }
 441
 442         /**
 443          * Move internal result pointer
 444          *
 445          * @param IResultWrapper|resource $res
 446          * @param int $row
 447          * @return bool
 448          */
 449         abstract protected function mysqlDataSeek( $res, $row );
 450
 451         /**
 452          * @return string
 453          */
 454         public function lastError() {
 455                 if ( $this->conn ) {
 456                         # Even if it's non-zero, it can still be invalid
 457                         Wikimedia\suppressWarnings();
 458                         $error = $this->mysqlError( $this->conn );
 459                         if ( !$error ) {
 460                                 $error = $this->mysqlError();
 461                         }
 462                         Wikimedia\restoreWarnings();
 463                 } else {
 464                         $error = $this->mysqlError();
 465                 }
 466                 if ( $error ) {
 467                         $error .= ' (' . $this->server . ')';
 468                 }
 469
 470                 return $error;
 471         }
 472
 473         /**
 474          * Returns the text of the error message from previous MySQL operation
 475          *
 476          * @param resource|null $conn Raw connection
 477          * @return string
 478          */
 479         abstract protected function mysqlError( $conn = null );
 480
 481         protected function wasQueryTimeout( $error, $errno ) {
 482                 // https://dev.mysql.com/doc/refman/8.0/en/client-error-reference.html
 483                 // https://phabricator.wikimedia.org/T170638
 484                 return in_array( $errno, [ 2062, 3024 ] );
 485         }
 486
 487         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
 488                 $this->nativeReplace( $table, $rows, $fname );
 489         }
 490
 491         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
 492                 $row = $this->getReplicationSafetyInfo();
 493                 // For row-based-replication, the resulting changes will be relayed, not the query
 494                 if ( $row->binlog_format === 'ROW' ) {
 495                         return true;
 496                 }
 497                 // LIMIT requires ORDER BY on a unique key or it is non-deterministic
 498                 if ( isset( $selectOptions['LIMIT'] ) ) {
 499                         return false;
 500                 }
 501                 // In MySQL, an INSERT SELECT is only replication safe with row-based
 502                 // replication or if innodb_autoinc_lock_mode is 0. When those
 503                 // conditions aren't met, use non-native mode.
 504                 // While we could try to determine if the insert is safe anyway by
 505                 // checking if the target table has an auto-increment column that
 506                 // isn't set in $varMap, that seems unlikely to be worth the extra
 507                 // complexity.
 508                 return (
 509                         in_array( 'NO_AUTO_COLUMNS', $insertOptions ) ||
 510                         (int)$row->innodb_autoinc_lock_mode === 0
 511                 );
 512         }
 513
 514         /**
 515          * @return stdClass Process cached row
 516          */
 517         protected function getReplicationSafetyInfo() {
 518                 if ( $this->replicationInfoRow === null ) {
 519                         $this->replicationInfoRow = $this->selectRow(
 520                                 false,
 521                                 [
 522                                         'innodb_autoinc_lock_mode' => '@@innodb_autoinc_lock_mode',
 523                                         'binlog_format' => '@@binlog_format',
 524                                 ],
 525                                 [],
 526                                 __METHOD__
 527                         );
 528                 }
 529
 530                 return $this->replicationInfoRow;
 531         }
 532
 533         /**
 534          * Estimate rows in dataset
 535          * Returns estimated count, based on EXPLAIN output
 536          * Takes same arguments as Database::select()
 537          *
 538          * @param string|array $table
 539          * @param string|array $var
 540          * @param string|array $conds
 541          * @param string $fname
 542          * @param string|array $options
 543          * @param array $join_conds
 544          * @return bool|int
 545          */
 546         public function estimateRowCount( $table, $var = '*', $conds = '',
 547                 $fname = __METHOD__, $options = [], $join_conds = []
 548         ) {
 549                 $conds = $this->normalizeConditions( $conds, $fname );
 550                 $column = $this->extractSingleFieldFromList( $var );
 551                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 552                         $conds[] = "$column IS NOT NULL";
 553                 }
 554
 555                 $options['EXPLAIN'] = true;
 556                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 557                 if ( $res === false ) {
 558                         return false;
 559                 }
 560                 if ( !$this->numRows( $res ) ) {
 561                         return 0;
 562                 }
 563
 564                 $rows = 1;
 565                 foreach ( $res as $plan ) {
 566                         $rows *= $plan->rows > 0 ? $plan->rows : 1; // avoid resetting to zero
 567                 }
 568
 569                 return (int)$rows;
 570         }
 571
 572         public function tableExists( $table, $fname = __METHOD__ ) {
 573                 // Split database and table into proper variables as Database::tableName() returns
 574                 // shared tables prefixed with their database, which do not work in SHOW TABLES statements
 575                 list( $database, , $prefix, $table ) = $this->qualifiedTableComponents( $table );
 576                 $tableName = "{$prefix}{$table}";
 577
 578                 if ( isset( $this->sessionTempTables[$tableName] ) ) {
 579                         return true; // already known to exist and won't show in SHOW TABLES anyway
 580                 }
 581
 582                 // We can't use buildLike() here, because it specifies an escape character
 583                 // other than the backslash, which is the only one supported by SHOW TABLES
 584                 $encLike = $this->escapeLikeInternal( $tableName, '\\' );
 585
 586                 // If the database has been specified (such as for shared tables), use "FROM"
 587                 if ( $database !== '' ) {
 588                         $encDatabase = $this->addIdentifierQuotes( $database );
 589                         $query = "SHOW TABLES FROM $encDatabase LIKE '$encLike'";
 590                 } else {
 591                         $query = "SHOW TABLES LIKE '$encLike'";
 592                 }
 593
 594                 return $this->query( $query, $fname )->numRows() > 0;
 595         }
 596
 597         /**
 598          * @param string $table
 599          * @param string $field
 600          * @return bool|MySQLField
 601          */
 602         public function fieldInfo( $table, $field ) {
 603                 $table = $this->tableName( $table );
 604                 $res = $this->query( "SELECT * FROM $table LIMIT 1", __METHOD__, true );
 605                 if ( !$res ) {
 606                         return false;
 607                 }
 608                 $n = $this->mysqlNumFields( $res->result );
 609                 for ( $i = 0; $i < $n; $i++ ) {
 610                         $meta = $this->mysqlFetchField( $res->result, $i );
 611                         if ( $field == $meta->name ) {
 612                                 return new MySQLField( $meta );
 613                         }
 614                 }
 615
 616                 return false;
 617         }
 618
 619         /**
 620          * Get column information from a result
 621          *
 622          * @param resource $res Raw result
 623          * @param int $n
 624          * @return stdClass
 625          */
 626         abstract protected function mysqlFetchField( $res, $n );
 627
 628         /**
 629          * Get information about an index into an object
 630          * Returns false if the index does not exist
 631          *
 632          * @param string $table
 633          * @param string $index
 634          * @param string $fname
 635          * @return bool|array|null False or null on failure
 636          */
 637         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 638                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 639                 # SHOW INDEX should work for 3.x and up:
 640                 # https://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 641                 $table = $this->tableName( $table );
 642                 $index = $this->indexName( $index );
 643
 644                 $sql = 'SHOW INDEX FROM ' . $table;
 645                 $res = $this->query( $sql, $fname );
 646
 647                 if ( !$res ) {
 648                         return null;
 649                 }
 650
 651                 $result = [];
 652
 653                 foreach ( $res as $row ) {
 654                         if ( $row->Key_name == $index ) {
 655                                 $result[] = $row;
 656                         }
 657                 }
 658
 659                 return $result ?: false;
 660         }
 661
 662         /**
 663          * @param string $s
 664          * @return string
 665          */
 666         public function strencode( $s ) {
 667                 return $this->mysqlRealEscapeString( $s );
 668         }
 669
 670         /**
 671          * @param string $s
 672          * @return mixed
 673          */
 674         abstract protected function mysqlRealEscapeString( $s );
 675
 676         public function addQuotes( $s ) {
 677                 if ( is_bool( $s ) ) {
 678                         // Parent would transform to int, which does not play nice with MySQL type juggling.
 679                         // When searching for an int in a string column, the strings are cast to int, which
 680                         // means false would match any string not starting with a number.
 681                         $s = (string)(int)$s;
 682                 }
 683                 return parent::addQuotes( $s );
 684         }
 685
 686         /**
 687          * MySQL uses `backticks` for identifier quoting instead of the sql standard "double quotes".
 688          *
 689          * @param string $s
 690          * @return string
 691          */
 692         public function addIdentifierQuotes( $s ) {
 693                 // Characters in the range \u0001-\uFFFF are valid in a quoted identifier
 694                 // Remove NUL bytes and escape backticks by doubling
 695                 return '`' . str_replace( [ "\0", '`' ], [ '', '``' ], $s ) . '`';
 696         }
 697
 698         /**
 699          * @param string $name
 700          * @return bool
 701          */
 702         public function isQuotedIdentifier( $name ) {
 703                 return strlen( $name ) && $name[0] == '`' && substr( $name, -1, 1 ) == '`';
 704         }
 705
 706         protected function doGetLag() {
 707                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 708                         return $this->getLagFromPtHeartbeat();
 709                 } else {
 710                         return $this->getLagFromSlaveStatus();
 711                 }
 712         }
 713
 714         /**
 715          * @return string
 716          */
 717         protected function getLagDetectionMethod() {
 718                 return $this->lagDetectionMethod;
 719         }
 720
 721         /**
 722          * @return bool|int
 723          */
 724         protected function getLagFromSlaveStatus() {
 725                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
 726                 $row = $res ? $res->fetchObject() : false;
 727                 // If the server is not replicating, there will be no row
 728                 if ( $row && strval( $row->Seconds_Behind_Master ) !== '' ) {
 729                         return intval( $row->Seconds_Behind_Master );
 730                 }
 731
 732                 return false;
 733         }
 734
 735         /**
 736          * @return bool|float
 737          */
 738         protected function getLagFromPtHeartbeat() {
 739                 $options = $this->lagDetectionOptions;
 740
 741                 $currentTrxInfo = $this->getRecordedTransactionLagStatus();
 742                 if ( $currentTrxInfo ) {
 743                         // There is an active transaction and the initial lag was already queried
 744                         $staleness = microtime( true ) - $currentTrxInfo['since'];
 745                         if ( $staleness > self::LAG_STALE_WARN_THRESHOLD ) {
 746                                 // Avoid returning higher and higher lag value due to snapshot age
 747                                 // given that the isolation level will typically be REPEATABLE-READ
 748                                 $this->queryLogger->warning(
 749                                         "Using cached lag value for {db_server} due to active transaction",
 750                                         $this->getLogContext( [
 751                                                 'method' => __METHOD__,
 752                                                 'age' => $staleness,
 753                                                 'trace' => ( new RuntimeException() )->getTraceAsString()
 754                                         ] )
 755                                 );
 756                         }
 757
 758                         return $currentTrxInfo['lag'];
 759                 }
 760
 761                 if ( isset( $options['conds'] ) ) {
 762                         // Best method for multi-DC setups: use logical channel names
 763                         $data = $this->getHeartbeatData( $options['conds'] );
 764                 } else {
 765                         // Standard method: use master server ID (works with stock pt-heartbeat)
 766                         $masterInfo = $this->getMasterServerInfo();
 767                         if ( !$masterInfo ) {
 768                                 $this->queryLogger->error(
 769                                         "Unable to query master of {db_server} for server ID",
 770                                         $this->getLogContext( [
 771                                                 'method' => __METHOD__
 772                                         ] )
 773                                 );
 774
 775                                 return false; // could not get master server ID
 776                         }
 777
 778                         $conds = [ 'server_id' => intval( $masterInfo['serverId'] ) ];
 779                         $data = $this->getHeartbeatData( $conds );
 780                 }
 781
 782                 list( $time, $nowUnix ) = $data;
 783                 if ( $time !== null ) {
 784                         // @time is in ISO format like "2015-09-25T16:48:10.000510"
 785                         $dateTime = new DateTime( $time, new DateTimeZone( 'UTC' ) );
 786                         $timeUnix = (int)$dateTime->format( 'U' ) + $dateTime->format( 'u' ) / 1e6;
 787
 788                         return max( $nowUnix - $timeUnix, 0.0 );
 789                 }
 790
 791                 $this->queryLogger->error(
 792                         "Unable to find pt-heartbeat row for {db_server}",
 793                         $this->getLogContext( [
 794                                 'method' => __METHOD__
 795                         ] )
 796                 );
 797
 798                 return false;
 799         }
 800
 801         protected function getMasterServerInfo() {
 802                 $cache = $this->srvCache;
 803                 $key = $cache->makeGlobalKey(
 804                         'mysql',
 805                         'master-info',
 806                         // Using one key for all cluster replica DBs is preferable
 807                         $this->getLBInfo( 'clusterMasterHost' ) ?: $this->getServer()
 808                 );
 809                 $fname = __METHOD__;
 810
 811                 return $cache->getWithSetCallback(
 812                         $key,
 813                         $cache::TTL_INDEFINITE,
 814                         function () use ( $cache, $key, $fname ) {
 815                                 // Get and leave a lock key in place for a short period
 816                                 if ( !$cache->lock( $key, 0, 10 ) ) {
 817                                         return false; // avoid master connection spike slams
 818                                 }
 819
 820                                 $conn = $this->getLazyMasterHandle();
 821                                 if ( !$conn ) {
 822                                         return false; // something is misconfigured
 823                                 }
 824
 825                                 // Connect to and query the master; catch errors to avoid outages
 826                                 try {
 827                                         $res = $conn->query( 'SELECT @@server_id AS id', $fname );
 828                                         $row = $res ? $res->fetchObject() : false;
 829                                         $id = $row ? (int)$row->id : 0;
 830                                 } catch ( DBError $e ) {
 831                                         $id = 0;
 832                                 }
 833
 834                                 // Cache the ID if it was retrieved
 835                                 return $id ? [ 'serverId' => $id, 'asOf' => time() ] : false;
 836                         }
 837                 );
 838         }
 839
 840         /**
 841          * @param array $conds WHERE clause conditions to find a row
 842          * @return array (heartbeat `ts` column value or null, UNIX timestamp) for the newest beat
 843          * @see https://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html
 844          */
 845         protected function getHeartbeatData( array $conds ) {
 846                 // Query time and trip time are not counted
 847                 $nowUnix = microtime( true );
 848                 // Do not bother starting implicit transactions here
 849                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
 850                 try {
 851                         $whereSQL = $this->makeList( $conds, self::LIST_AND );
 852                         // Use ORDER BY for channel based queries since that field might not be UNIQUE.
 853                         // Note: this would use "TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6))" but the
 854                         // percision field is not supported in MySQL <= 5.5.
 855                         $res = $this->query(
 856                                 "SELECT ts FROM heartbeat.heartbeat WHERE $whereSQL ORDER BY ts DESC LIMIT 1",
 857                                 __METHOD__
 858                         );
 859                         $row = $res ? $res->fetchObject() : false;
 860                 } finally {
 861                         $this->restoreFlags();
 862                 }
 863
 864                 return [ $row ? $row->ts : null, $nowUnix ];
 865         }
 866
 867         protected function getApproximateLagStatus() {
 868                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 869                         // Disable caching since this is fast enough and we don't wan't
 870                         // to be *too* pessimistic by having both the cache TTL and the
 871                         // pt-heartbeat interval count as lag in getSessionLagStatus()
 872                         return parent::getApproximateLagStatus();
 873                 }
 874
 875                 $key = $this->srvCache->makeGlobalKey( 'mysql-lag', $this->getServer() );
 876                 $approxLag = $this->srvCache->get( $key );
 877                 if ( !$approxLag ) {
 878                         $approxLag = parent::getApproximateLagStatus();
 879                         $this->srvCache->set( $key, $approxLag, 1 );
 880                 }
 881
 882                 return $approxLag;
 883         }
 884
 885         public function masterPosWait( DBMasterPos $pos, $timeout ) {
 886                 if ( !( $pos instanceof MySQLMasterPos ) ) {
 887                         throw new InvalidArgumentException( "Position not an instance of MySQLMasterPos" );
 888                 }
 889
 890                 if ( $this->getLBInfo( 'is static' ) === true ) {
 891                         return 0; // this is a copy of a read-only dataset with no master DB
 892                 } elseif ( $this->lastKnownReplicaPos && $this->lastKnownReplicaPos->hasReached( $pos ) ) {
 893                         return 0; // already reached this point for sure
 894                 }
 895
 896                 // Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
 897                 if ( $pos->getGTIDs() ) {
 898                         // Ignore GTIDs from domains exclusive to the master DB (presumably inactive)
 899                         $rpos = $this->getReplicaPos();
 900                         $gtidsWait = $rpos ? MySQLMasterPos::getCommonDomainGTIDs( $pos, $rpos ) : [];
 901                         if ( !$gtidsWait ) {
 902                                 $this->queryLogger->error(
 903                                         "No GTIDs with the same domain between master ($pos) and replica ($rpos)",
 904                                         $this->getLogContext( [
 905                                                 'method' => __METHOD__,
 906                                         ] )
 907                                 );
 908
 909                                 return -1; // $pos is from the wrong cluster?
 910                         }
 911                         // Wait on the GTID set (MariaDB only)
 912                         $gtidArg = $this->addQuotes( implode( ',', $gtidsWait ) );
 913                         if ( strpos( $gtidArg, ':' ) !== false ) {
 914                                 // MySQL GTIDs, e.g "source_id:transaction_id"
 915                                 $sql = "SELECT WAIT_FOR_EXECUTED_GTID_SET($gtidArg, $timeout)";
 916                         } else {
 917                                 // MariaDB GTIDs, e.g."domain:server:sequence"
 918                                 $sql = "SELECT MASTER_GTID_WAIT($gtidArg, $timeout)";
 919                         }
 920                 } else {
 921                         // Wait on the binlog coordinates
 922                         $encFile = $this->addQuotes( $pos->getLogFile() );
 923                         $encPos = intval( $pos->getLogPosition()[$pos::CORD_EVENT] );
 924                         $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
 925                 }
 926
 927                 list( $res, $err ) = $this->executeQuery( $sql, __METHOD__, self::QUERY_IGNORE_DBO_TRX );
 928                 $row = $res ? $this->fetchRow( $res ) : false;
 929                 if ( !$row ) {
 930                         throw new DBExpectedError( $this, "Replication wait failed: {$err}" );
 931                 }
 932
 933                 // Result can be NULL (error), -1 (timeout), or 0+ per the MySQL manual
 934                 $status = ( $row[0] !== null ) ? intval( $row[0] ) : null;
 935                 if ( $status === null ) {
 936                         if ( !$pos->getGTIDs() ) {
 937                                 // T126436: jobs programmed to wait on master positions might be referencing
 938                                 // binlogs with an old master hostname; this makes MASTER_POS_WAIT() return null.
 939                                 // Try to detect this case and treat the replica DB as having reached the given
 940                                 // position (any master switchover already requires that the new master be caught
 941                                 // up before the switch).
 942                                 $replicationPos = $this->getReplicaPos();
 943                                 if ( $replicationPos && !$replicationPos->channelsMatch( $pos ) ) {
 944                                         $this->lastKnownReplicaPos = $replicationPos;
 945                                         $status = 0;
 946                                 }
 947                         }
 948                 } elseif ( $status >= 0 ) {
 949                         // Remember that this position was reached to save queries next time
 950                         $this->lastKnownReplicaPos = $pos;
 951                 }
 952
 953                 return $status;
 954         }
 955
 956         /**
 957          * Get the position of the master from SHOW SLAVE STATUS
 958          *
 959          * @return MySQLMasterPos|bool
 960          */
 961         public function getReplicaPos() {
 962                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
 963
 964                 if ( $this->useGTIDs() ) {
 965                         // Try to use GTIDs, fallbacking to binlog positions if not possible
 966                         $data = $this->getServerGTIDs( __METHOD__ );
 967                         // Use gtid_slave_pos for MariaDB and gtid_executed for MySQL
 968                         foreach ( [ 'gtid_slave_pos', 'gtid_executed' ] as $name ) {
 969                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
 970                                         return new MySQLMasterPos( $data[$name], $now );
 971                                 }
 972                         }
 973                 }
 974
 975                 $data = $this->getServerRoleStatus( 'SLAVE', __METHOD__ );
 976                 if ( $data && strlen( $data['Relay_Master_Log_File'] ) ) {
 977                         return new MySQLMasterPos(
 978                                 "{$data['Relay_Master_Log_File']}/{$data['Exec_Master_Log_Pos']}",
 979                                 $now
 980                         );
 981                 }
 982
 983                 return false;
 984         }
 985
 986         /**
 987          * Get the position of the master from SHOW MASTER STATUS
 988          *
 989          * @return MySQLMasterPos|bool
 990          */
 991         public function getMasterPos() {
 992                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
 993
 994                 $pos = false;
 995                 if ( $this->useGTIDs() ) {
 996                         // Try to use GTIDs, fallbacking to binlog positions if not possible
 997                         $data = $this->getServerGTIDs( __METHOD__ );
 998                         // Use gtid_binlog_pos for MariaDB and gtid_executed for MySQL
 999                         foreach ( [ 'gtid_binlog_pos', 'gtid_executed' ] as $name ) {
1000                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
1001                                         $pos = new MySQLMasterPos( $data[$name], $now );
1002                                         break;
1003                                 }
1004                         }
1005                         // Filter domains that are inactive or not relevant to the session
1006                         if ( $pos ) {
1007                                 $pos->setActiveOriginServerId( $this->getServerId() );
1008                                 $pos->setActiveOriginServerUUID( $this->getServerUUID() );
1009                                 if ( isset( $data['gtid_domain_id'] ) ) {
1010                                         $pos->setActiveDomain( $data['gtid_domain_id'] );
1011                                 }
1012                         }
1013                 }
1014
1015                 if ( !$pos ) {
1016                         $data = $this->getServerRoleStatus( 'MASTER', __METHOD__ );
1017                         if ( $data && strlen( $data['File'] ) ) {
1018                                 $pos = new MySQLMasterPos( "{$data['File']}/{$data['Position']}", $now );
1019                         }
1020                 }
1021
1022                 return $pos;
1023         }
1024
1025         /**
1026          * @return int
1027          * @throws DBQueryError If the variable doesn't exist for some reason
1028          */
1029         protected function getServerId() {
1030                 $fname = __METHOD__;
1031                 return $this->srvCache->getWithSetCallback(
1032                         $this->srvCache->makeGlobalKey( 'mysql-server-id', $this->getServer() ),
1033                         self::SERVER_ID_CACHE_TTL,
1034                         function () use ( $fname ) {
1035                                 $res = $this->query( "SELECT @@server_id AS id", $fname );
1036                                 return intval( $this->fetchObject( $res )->id );
1037                         }
1038                 );
1039         }
1040
1041         /**
1042          * @return string|null
1043          */
1044         protected function getServerUUID() {
1045                 return $this->srvCache->getWithSetCallback(
1046                         $this->srvCache->makeGlobalKey( 'mysql-server-uuid', $this->getServer() ),
1047                         self::SERVER_ID_CACHE_TTL,
1048                         function () {
1049                                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'server_uuid'" );
1050                                 $row = $this->fetchObject( $res );
1051
1052                                 return $row ? $row->Value : null;
1053                         }
1054                 );
1055         }
1056
1057         /**
1058          * @param string $fname
1059          * @return string[]
1060          */
1061         protected function getServerGTIDs( $fname = __METHOD__ ) {
1062                 $map = [];
1063                 // Get global-only variables like gtid_executed
1064                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'gtid_%'", $fname );
1065                 foreach ( $res as $row ) {
1066                         $map[$row->Variable_name] = $row->Value;
1067                 }
1068                 // Get session-specific (e.g. gtid_domain_id since that is were writes will log)
1069                 $res = $this->query( "SHOW SESSION VARIABLES LIKE 'gtid_%'", $fname );
1070                 foreach ( $res as $row ) {
1071                         $map[$row->Variable_name] = $row->Value;
1072                 }
1073
1074                 return $map;
1075         }
1076
1077         /**
1078          * @param string $role One of "MASTER"/"SLAVE"
1079          * @param string $fname
1080          * @return string[] Latest available server status row
1081          */
1082         protected function getServerRoleStatus( $role, $fname = __METHOD__ ) {
1083                 return $this->query( "SHOW $role STATUS", $fname )->fetchRow() ?: [];
1084         }
1085
1086         public function serverIsReadOnly() {
1087                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'read_only'", __METHOD__ );
1088                 $row = $this->fetchObject( $res );
1089
1090                 return $row ? ( strtolower( $row->Value ) === 'on' ) : false;
1091         }
1092
1093         /**
1094          * @param string $index
1095          * @return string
1096          */
1097         function useIndexClause( $index ) {
1098                 return "FORCE INDEX (" . $this->indexName( $index ) . ")";
1099         }
1100
1101         /**
1102          * @param string $index
1103          * @return string
1104          */
1105         function ignoreIndexClause( $index ) {
1106                 return "IGNORE INDEX (" . $this->indexName( $index ) . ")";
1107         }
1108
1109         /**
1110          * @return string
1111          */
1112         function lowPriorityOption() {
1113                 return 'LOW_PRIORITY';
1114         }
1115
1116         /**
1117          * @return string
1118          */
1119         public function getSoftwareLink() {
1120                 // MariaDB includes its name in its version string; this is how MariaDB's version of
1121                 // the mysql command-line client identifies MariaDB servers (see mariadb_connection()
1122                 // in libmysql/libmysql.c).
1123                 $version = $this->getServerVersion();
1124                 if ( strpos( $version, 'MariaDB' ) !== false || strpos( $version, '-maria-' ) !== false ) {
1125                         return '[{{int:version-db-mariadb-url}} MariaDB]';
1126                 }
1127
1128                 // Percona Server's version suffix is not very distinctive, and @@version_comment
1129                 // doesn't give the necessary info for source builds, so assume the server is MySQL.
1130                 // (Even Percona's version of mysql doesn't try to make the distinction.)
1131                 return '[{{int:version-db-mysql-url}} MySQL]';
1132         }
1133
1134         /**
1135          * @return string
1136          */
1137         public function getServerVersion() {
1138                 // Not using mysql_get_server_info() or similar for consistency: in the handshake,
1139                 // MariaDB 10 adds the prefix "5.5.5-", and only some newer client libraries strip
1140                 // it off (see RPL_VERSION_HACK in include/mysql_com.h).
1141                 if ( $this->serverVersion === null ) {
1142                         $this->serverVersion = $this->selectField( '', 'VERSION()', '', __METHOD__ );
1143                 }
1144                 return $this->serverVersion;
1145         }
1146
1147         /**
1148          * @param array $options
1149          */
1150         public function setSessionOptions( array $options ) {
1151                 if ( isset( $options['connTimeout'] ) ) {
1152                         $timeout = (int)$options['connTimeout'];
1153                         $this->query( "SET net_read_timeout=$timeout" );
1154                         $this->query( "SET net_write_timeout=$timeout" );
1155                 }
1156         }
1157
1158         /**
1159          * @param string &$sql
1160          * @param string &$newLine
1161          * @return bool
1162          */
1163         public function streamStatementEnd( &$sql, &$newLine ) {
1164                 if ( strtoupper( substr( $newLine, 0, 9 ) ) == 'DELIMITER' ) {
1165                         preg_match( '/^DELIMITER\s+(\S+)/', $newLine, $m );
1166                         $this->delimiter = $m[1];
1167                         $newLine = '';
1168                 }
1169
1170                 return parent::streamStatementEnd( $sql, $newLine );
1171         }
1172
1173         /**
1174          * Check to see if a named lock is available. This is non-blocking.
1175          *
1176          * @param string $lockName Name of lock to poll
1177          * @param string $method Name of method calling us
1178          * @return bool
1179          * @since 1.20
1180          */
1181         public function lockIsFree( $lockName, $method ) {
1182                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1183                         return false; // already held
1184                 }
1185
1186                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1187                 $result = $this->query( "SELECT IS_FREE_LOCK($encName) AS lockstatus", $method );
1188                 $row = $this->fetchObject( $result );
1189
1190                 return ( $row->lockstatus == 1 );
1191         }
1192
1193         /**
1194          * @param string $lockName
1195          * @param string $method
1196          * @param int $timeout
1197          * @return bool
1198          */
1199         public function lock( $lockName, $method, $timeout = 5 ) {
1200                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1201                 $result = $this->query( "SELECT GET_LOCK($encName, $timeout) AS lockstatus", $method );
1202                 $row = $this->fetchObject( $result );
1203
1204                 if ( $row->lockstatus == 1 ) {
1205                         parent::lock( $lockName, $method, $timeout ); // record
1206                         return true;
1207                 }
1208
1209                 $this->queryLogger->info( __METHOD__ . " failed to acquire lock '{lockname}'",
1210                         [ 'lockname' => $lockName ] );
1211
1212                 return false;
1213         }
1214
1215         /**
1216          * FROM MYSQL DOCS:
1217          * https://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock
1218          * @param string $lockName
1219          * @param string $method
1220          * @return bool
1221          */
1222         public function unlock( $lockName, $method ) {
1223                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1224                 $result = $this->query( "SELECT RELEASE_LOCK($encName) as lockstatus", $method );
1225                 $row = $this->fetchObject( $result );
1226
1227                 if ( $row->lockstatus == 1 ) {
1228                         parent::unlock( $lockName, $method ); // record
1229                         return true;
1230                 }
1231
1232                 $this->queryLogger->warning( __METHOD__ . " failed to release lock '$lockName'\n" );
1233
1234                 return false;
1235         }
1236
1237         private function makeLockName( $lockName ) {
1238                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1239                 // Newer version enforce a 64 char length limit.
1240                 return ( strlen( $lockName ) > 64 ) ? sha1( $lockName ) : $lockName;
1241         }
1242
1243         public function namedLocksEnqueue() {
1244                 return true;
1245         }
1246
1247         public function tableLocksHaveTransactionScope() {
1248                 return false; // tied to TCP connection
1249         }
1250
1251         protected function doLockTables( array $read, array $write, $method ) {
1252                 $items = [];
1253                 foreach ( $write as $table ) {
1254                         $items[] = $this->tableName( $table ) . ' WRITE';
1255                 }
1256                 foreach ( $read as $table ) {
1257                         $items[] = $this->tableName( $table ) . ' READ';
1258                 }
1259
1260                 $sql = "LOCK TABLES " . implode( ',', $items );
1261                 $this->query( $sql, $method );
1262
1263                 return true;
1264         }
1265
1266         protected function doUnlockTables( $method ) {
1267                 $this->query( "UNLOCK TABLES", $method );
1268
1269                 return true;
1270         }
1271
1272         /**
1273          * @param bool $value
1274          */
1275         public function setBigSelects( $value = true ) {
1276                 if ( $value === 'default' ) {
1277                         if ( $this->defaultBigSelects === null ) {
1278                                 # Function hasn't been called before so it must already be set to the default
1279                                 return;
1280                         } else {
1281                                 $value = $this->defaultBigSelects;
1282                         }
1283                 } elseif ( $this->defaultBigSelects === null ) {
1284                         $this->defaultBigSelects =
1285                                 (bool)$this->selectField( false, '@@sql_big_selects', '', __METHOD__ );
1286                 }
1287                 $encValue = $value ? '1' : '0';
1288                 $this->query( "SET sql_big_selects=$encValue", __METHOD__ );
1289         }
1290
1291         /**
1292          * DELETE where the condition is a join. MySql uses multi-table deletes.
1293          * @param string $delTable
1294          * @param string $joinTable
1295          * @param string $delVar
1296          * @param string $joinVar
1297          * @param array|string $conds
1298          * @param bool|string $fname
1299          * @throws DBUnexpectedError
1300          */
1301         public function deleteJoin(
1302                 $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__
1303         ) {
1304                 if ( !$conds ) {
1305                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
1306                 }
1307
1308                 $delTable = $this->tableName( $delTable );
1309                 $joinTable = $this->tableName( $joinTable );
1310                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1311
1312                 if ( $conds != '*' ) {
1313                         $sql .= ' AND ' . $this->makeList( $conds, self::LIST_AND );
1314                 }
1315
1316                 $this->query( $sql, $fname );
1317         }
1318
1319         public function upsert(
1320                 $table, array $rows, $uniqueIndexes, array $set, $fname = __METHOD__
1321         ) {
1322                 if ( $rows === [] ) {
1323                         return true; // nothing to do
1324                 }
1325
1326                 if ( !is_array( reset( $rows ) ) ) {
1327                         $rows = [ $rows ];
1328                 }
1329
1330                 $table = $this->tableName( $table );
1331                 $columns = array_keys( $rows[0] );
1332
1333                 $sql = "INSERT INTO $table (" . implode( ',', $columns ) . ') VALUES ';
1334                 $rowTuples = [];
1335                 foreach ( $rows as $row ) {
1336                         $rowTuples[] = '(' . $this->makeList( $row ) . ')';
1337                 }
1338                 $sql .= implode( ',', $rowTuples );
1339                 $sql .= " ON DUPLICATE KEY UPDATE " . $this->makeList( $set, self::LIST_SET );
1340
1341                 $this->query( $sql, $fname );
1342
1343                 return true;
1344         }
1345
1346         /**
1347          * Determines how long the server has been up
1348          *
1349          * @return int
1350          */
1351         public function getServerUptime() {
1352                 $vars = $this->getMysqlStatus( 'Uptime' );
1353
1354                 return (int)$vars['Uptime'];
1355         }
1356
1357         /**
1358          * Determines if the last failure was due to a deadlock
1359          *
1360          * @return bool
1361          */
1362         public function wasDeadlock() {
1363                 return $this->lastErrno() == 1213;
1364         }
1365
1366         /**
1367          * Determines if the last failure was due to a lock timeout
1368          *
1369          * @return bool
1370          */
1371         public function wasLockTimeout() {
1372                 return $this->lastErrno() == 1205;
1373         }
1374
1375         /**
1376          * Determines if the last failure was due to the database being read-only.
1377          *
1378          * @return bool
1379          */
1380         public function wasReadOnlyError() {
1381                 return $this->lastErrno() == 1223 ||
1382                         ( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
1383         }
1384
1385         public function wasConnectionError( $errno ) {
1386                 return $errno == 2013 || $errno == 2006;
1387         }
1388
1389         protected function wasKnownStatementRollbackError() {
1390                 $errno = $this->lastErrno();
1391
1392                 if ( $errno === 1205 ) { // lock wait timeout
1393                         // Note that this is uncached to avoid stale values of SET is used
1394                         $row = $this->selectRow(
1395                                 false,
1396                                 [ 'innodb_rollback_on_timeout' => '@@innodb_rollback_on_timeout' ],
1397                                 [],
1398                                 __METHOD__
1399                         );
1400                         // https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
1401                         // https://dev.mysql.com/doc/refman/5.5/en/innodb-parameters.html
1402                         return $row->innodb_rollback_on_timeout ? false : true;
1403                 }
1404
1405                 // See https://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html
1406                 return in_array( $errno, [ 1022, 1062, 1216, 1217, 1137, 1146, 1051, 1054 ], true );
1407         }
1408
1409         /**
1410          * @param string $oldName
1411          * @param string $newName
1412          * @param bool $temporary
1413          * @param string $fname
1414          * @return bool
1415          */
1416         public function duplicateTableStructure(
1417                 $oldName, $newName, $temporary = false, $fname = __METHOD__
1418         ) {
1419                 $tmp = $temporary ? 'TEMPORARY ' : '';
1420                 $newName = $this->addIdentifierQuotes( $newName );
1421                 $oldName = $this->addIdentifierQuotes( $oldName );
1422                 $query = "CREATE $tmp TABLE $newName (LIKE $oldName)";
1423
1424                 return $this->query( $query, $fname, $this::QUERY_PSEUDO_PERMANENT );
1425         }
1426
1427         /**
1428          * List all tables on the database
1429          *
1430          * @param string|null $prefix Only show tables with this prefix, e.g. mw_
1431          * @param string $fname Calling function name
1432          * @return array
1433          */
1434         public function listTables( $prefix = null, $fname = __METHOD__ ) {
1435                 $result = $this->query( "SHOW TABLES", $fname );
1436
1437                 $endArray = [];
1438
1439                 foreach ( $result as $table ) {
1440                         $vars = get_object_vars( $table );
1441                         $table = array_pop( $vars );
1442
1443                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1444                                 $endArray[] = $table;
1445                         }
1446                 }
1447
1448                 return $endArray;
1449         }
1450
1451         /**
1452          * @param string $tableName
1453          * @param string $fName
1454          * @return bool|IResultWrapper
1455          */
1456         public function dropTable( $tableName, $fName = __METHOD__ ) {
1457                 if ( !$this->tableExists( $tableName, $fName ) ) {
1458                         return false;
1459                 }
1460
1461                 return $this->query( "DROP TABLE IF EXISTS " . $this->tableName( $tableName ), $fName );
1462         }
1463
1464         /**
1465          * Get status information from SHOW STATUS in an associative array
1466          *
1467          * @param string $which
1468          * @return array
1469          */
1470         private function getMysqlStatus( $which = "%" ) {
1471                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1472                 $status = [];
1473
1474                 foreach ( $res as $row ) {
1475                         $status[$row->Variable_name] = $row->Value;
1476                 }
1477
1478                 return $status;
1479         }
1480
1481         /**
1482          * Lists VIEWs in the database
1483          *
1484          * @param string|null $prefix Only show VIEWs with this prefix, eg.
1485          * unit_test_, or $wgDBprefix. Default: null, would return all views.
1486          * @param string $fname Name of calling function
1487          * @return array
1488          * @since 1.22
1489          */
1490         public function listViews( $prefix = null, $fname = __METHOD__ ) {
1491                 // The name of the column containing the name of the VIEW
1492                 $propertyName = 'Tables_in_' . $this->getDBname();
1493
1494                 // Query for the VIEWS
1495                 $res = $this->query( 'SHOW FULL TABLES WHERE TABLE_TYPE = "VIEW"' );
1496                 $allViews = [];
1497                 foreach ( $res as $row ) {
1498                         array_push( $allViews, $row->$propertyName );
1499                 }
1500
1501                 if ( is_null( $prefix ) || $prefix === '' ) {
1502                         return $allViews;
1503                 }
1504
1505                 $filteredViews = [];
1506                 foreach ( $allViews as $viewName ) {
1507                         // Does the name of this VIEW start with the table-prefix?
1508                         if ( strpos( $viewName, $prefix ) === 0 ) {
1509                                 array_push( $filteredViews, $viewName );
1510                         }
1511                 }
1512
1513                 return $filteredViews;
1514         }
1515
1516         /**
1517          * Differentiates between a TABLE and a VIEW.
1518          *
1519          * @param string $name Name of the TABLE/VIEW to test
1520          * @param string|null $prefix
1521          * @return bool
1522          * @since 1.22
1523          */
1524         public function isView( $name, $prefix = null ) {
1525                 return in_array( $name, $this->listViews( $prefix ) );
1526         }
1527
1528         protected function isTransactableQuery( $sql ) {
1529                 return parent::isTransactableQuery( $sql ) &&
1530                         !preg_match( '/^SELECT\s+(GET|RELEASE|IS_FREE)_LOCK\(/', $sql );
1531         }
1532
1533         public function buildStringCast( $field ) {
1534                 return "CAST( $field AS BINARY )";
1535         }
1536
1537         /**
1538          * @param string $field Field or column to cast
1539          * @return string
1540          */
1541         public function buildIntegerCast( $field ) {
1542                 return 'CAST( ' . $field . ' AS SIGNED )';
1543         }
1544
1545         /*
1546          * @return bool Whether GTID support is used (mockable for testing)
1547          */
1548         protected function useGTIDs() {
1549                 return $this->useGTIDs;
1550         }
1551 }
1552
1553 /**
1554  * @deprecated since 1.29
1555  */
1556 class_alias( DatabaseMysqlBase::class, 'DatabaseMysqlBase' );