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