includes/libs/rdbms/database/DatabaseMysqlBase.php

   1 <?php
   2 /**
   3  * This is the MySQL database abstraction layer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23 namespace Wikimedia\Rdbms;
  24
  25 use DateTime;
  26 use DateTimeZone;
  27 use Wikimedia;
  28 use InvalidArgumentException;
  29 use Exception;
  30 use stdClass;
  31
  32 /**
  33  * Database abstraction object for MySQL.
  34  * Defines methods independent on used MySQL extension.
  35  *
  36  * @ingroup Database
  37  * @since 1.22
  38  * @see Database
  39  */
  40 abstract class DatabaseMysqlBase extends Database {
  41         /** @var MysqlMasterPos */
  42         protected $lastKnownReplicaPos;
  43         /** @var string Method to detect replica DB lag */
  44         protected $lagDetectionMethod;
  45         /** @var array Method to detect replica DB lag */
  46         protected $lagDetectionOptions = [];
  47         /** @var bool bool Whether to use GTID methods */
  48         protected $useGTIDs = false;
  49         /** @var string|null */
  50         protected $sslKeyPath;
  51         /** @var string|null */
  52         protected $sslCertPath;
  53         /** @var string|null */
  54         protected $sslCAFile;
  55         /** @var string|null */
  56         protected $sslCAPath;
  57         /** @var string[]|null */
  58         protected $sslCiphers;
  59         /** @var string sql_mode value to send on connection */
  60         protected $sqlMode;
  61         /** @var bool Use experimental UTF-8 transmission encoding */
  62         protected $utf8Mode;
  63         /** @var bool|null */
  64         protected $defaultBigSelects = null;
  65
  66         /** @var string|null */
  67         private $serverVersion = null;
  68         /** @var bool|null */
  69         private $insertSelectIsSafe = null;
  70         /** @var stdClass|null */
  71         private $replicationInfoRow = null;
  72
  73         // Cache getServerId() for 24 hours
  74         const SERVER_ID_CACHE_TTL = 86400;
  75
  76         /** @var float Warn if lag estimates are made for transactions older than this many seconds */
  77         const LAG_STALE_WARN_THRESHOLD = 0.100;
  78
  79         /**
  80          * Additional $params include:
  81          *   - lagDetectionMethod : set to one of (Seconds_Behind_Master,pt-heartbeat).
  82          *       pt-heartbeat assumes the table is at heartbeat.heartbeat
  83          *       and uses UTC timestamps in the heartbeat.ts column.
  84          *       (https://www.percona.com/doc/percona-toolkit/2.2/pt-heartbeat.html)
  85          *   - lagDetectionOptions : if using pt-heartbeat, this can be set to an array map to change
  86          *       the default behavior. Normally, the heartbeat row with the server
  87          *       ID of this server's master will be used. Set the "conds" field to
  88          *       override the query conditions, e.g. ['shard' => 's1'].
  89          *   - useGTIDs : use GTID methods like MASTER_GTID_WAIT() when possible.
  90          *   - insertSelectIsSafe : force that native INSERT SELECT is or is not safe [default: null]
  91          *   - sslKeyPath : path to key file [default: null]
  92          *   - sslCertPath : path to certificate file [default: null]
  93          *   - sslCAFile: path to a single certificate authority PEM file [default: null]
  94          *   - sslCAPath : parth to certificate authority PEM directory [default: null]
  95          *   - sslCiphers : array list of allowable ciphers [default: null]
  96          * @param array $params
  97          */
  98         function __construct( array $params ) {
  99                 $this->lagDetectionMethod = $params['lagDetectionMethod'] ?? 'Seconds_Behind_Master';
 100                 $this->lagDetectionOptions = $params['lagDetectionOptions'] ?? [];
 101                 $this->useGTIDs = !empty( $params['useGTIDs' ] );
 102                 foreach ( [ 'KeyPath', 'CertPath', 'CAFile', 'CAPath', 'Ciphers' ] as $name ) {
 103                         $var = "ssl{$name}";
 104                         if ( isset( $params[$var] ) ) {
 105                                 $this->$var = $params[$var];
 106                         }
 107                 }
 108                 $this->sqlMode = $params['sqlMode'] ?? '';
 109                 $this->utf8Mode = !empty( $params['utf8Mode'] );
 110                 $this->insertSelectIsSafe = isset( $params['insertSelectIsSafe'] )
 111                         ? (bool)$params['insertSelectIsSafe'] : null;
 112
 113                 parent::__construct( $params );
 114         }
 115
 116         /**
 117          * @return string
 118          */
 119         public function getType() {
 120                 return 'mysql';
 121         }
 122
 123         /**
 124          * @param string $server
 125          * @param string $user
 126          * @param string $password
 127          * @param string $dbName
 128          * @throws Exception|DBConnectionError
 129          * @return bool
 130          */
 131         public function open( $server, $user, $password, $dbName ) {
 132                 # Close/unset connection handle
 133                 $this->close();
 134
 135                 $this->server = $server;
 136                 $this->user = $user;
 137                 $this->password = $password;
 138                 $this->dbName = $dbName;
 139
 140                 $this->installErrorHandler();
 141                 try {
 142                         $this->conn = $this->mysqlConnect( $this->server );
 143                 } catch ( Exception $ex ) {
 144                         $this->restoreErrorHandler();
 145                         throw $ex;
 146                 }
 147                 $error = $this->restoreErrorHandler();
 148
 149                 # Always log connection errors
 150                 if ( !$this->conn ) {
 151                         $error = $error ?: $this->lastError();
 152                         $this->connLogger->error(
 153                                 "Error connecting to {db_server}: {error}",
 154                                 $this->getLogContext( [
 155                                         'method' => __METHOD__,
 156                                         'error' => $error,
 157                                 ] )
 158                         );
 159                         $this->connLogger->debug( "DB connection error\n" .
 160                                 "Server: $server, User: $user, Password: " .
 161                                 substr( $password, 0, 3 ) . "..., error: " . $error . "\n" );
 162
 163                         throw new DBConnectionError( $this, $error );
 164                 }
 165
 166                 if ( strlen( $dbName ) ) {
 167                         Wikimedia\suppressWarnings();
 168                         $success = $this->selectDB( $dbName );
 169                         Wikimedia\restoreWarnings();
 170                         if ( !$success ) {
 171                                 $error = $this->lastError();
 172                                 $this->queryLogger->error(
 173                                         "Error selecting database {db_name} on server {db_server}: {error}",
 174                                         $this->getLogContext( [
 175                                                 'method' => __METHOD__,
 176                                                 'error' => $error,
 177                                         ] )
 178                                 );
 179                                 throw new DBConnectionError( $this, "Error selecting database $dbName: $error" );
 180                         }
 181                 }
 182
 183                 // Tell the server what we're communicating with
 184                 if ( !$this->connectInitCharset() ) {
 185                         $error = $this->lastError();
 186                         $this->queryLogger->error(
 187                                 "Error setting character set: {error}",
 188                                 $this->getLogContext( [
 189                                         'method' => __METHOD__,
 190                                         'error' => $this->lastError(),
 191                                 ] )
 192                         );
 193                         throw new DBConnectionError( $this, "Error setting character set: $error" );
 194                 }
 195
 196                 // Abstract over any insane MySQL defaults
 197                 $set = [ 'group_concat_max_len = 262144' ];
 198                 // Set SQL mode, default is turning them all off, can be overridden or skipped with null
 199                 if ( is_string( $this->sqlMode ) ) {
 200                         $set[] = 'sql_mode = ' . $this->addQuotes( $this->sqlMode );
 201                 }
 202                 // Set any custom settings defined by site config
 203                 // (e.g. https://dev.mysql.com/doc/refman/4.1/en/innodb-parameters.html)
 204                 foreach ( $this->sessionVars as $var => $val ) {
 205                         // Escape strings but not numbers to avoid MySQL complaining
 206                         if ( !is_int( $val ) && !is_float( $val ) ) {
 207                                 $val = $this->addQuotes( $val );
 208                         }
 209                         $set[] = $this->addIdentifierQuotes( $var ) . ' = ' . $val;
 210                 }
 211
 212                 if ( $set ) {
 213                         // Use doQuery() to avoid opening implicit transactions (DBO_TRX)
 214                         $success = $this->doQuery( 'SET ' . implode( ', ', $set ) );
 215                         if ( !$success ) {
 216                                 $error = $this->lastError();
 217                                 $this->queryLogger->error(
 218                                         'Error setting MySQL variables on server {db_server}: {error}',
 219                                         $this->getLogContext( [
 220                                                 'method' => __METHOD__,
 221                                                 'error' => $error,
 222                                         ] )
 223                                 );
 224                                 throw new DBConnectionError( $this, "Error setting MySQL variables: $error" );
 225                         }
 226                 }
 227
 228                 $this->opened = true;
 229
 230                 return true;
 231         }
 232
 233         /**
 234          * Set the character set information right after connection
 235          * @return bool
 236          */
 237         protected function connectInitCharset() {
 238                 if ( $this->utf8Mode ) {
 239                         // Tell the server we're communicating with it in UTF-8.
 240                         // This may engage various charset conversions.
 241                         return $this->mysqlSetCharset( 'utf8' );
 242                 } else {
 243                         return $this->mysqlSetCharset( 'binary' );
 244                 }
 245         }
 246
 247         /**
 248          * Open a connection to a MySQL server
 249          *
 250          * @param string $realServer
 251          * @return mixed Raw connection
 252          * @throws DBConnectionError
 253          */
 254         abstract protected function mysqlConnect( $realServer );
 255
 256         /**
 257          * Set the character set of the MySQL link
 258          *
 259          * @param string $charset
 260          * @return bool
 261          */
 262         abstract protected function mysqlSetCharset( $charset );
 263
 264         /**
 265          * @param ResultWrapper|resource $res
 266          * @throws DBUnexpectedError
 267          */
 268         public function freeResult( $res ) {
 269                 if ( $res instanceof ResultWrapper ) {
 270                         $res = $res->result;
 271                 }
 272                 Wikimedia\suppressWarnings();
 273                 $ok = $this->mysqlFreeResult( $res );
 274                 Wikimedia\restoreWarnings();
 275                 if ( !$ok ) {
 276                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 277                 }
 278         }
 279
 280         /**
 281          * Free result memory
 282          *
 283          * @param resource $res Raw result
 284          * @return bool
 285          */
 286         abstract protected function mysqlFreeResult( $res );
 287
 288         /**
 289          * @param ResultWrapper|resource $res
 290          * @return stdClass|bool
 291          * @throws DBUnexpectedError
 292          */
 293         public function fetchObject( $res ) {
 294                 if ( $res instanceof ResultWrapper ) {
 295                         $res = $res->result;
 296                 }
 297                 Wikimedia\suppressWarnings();
 298                 $row = $this->mysqlFetchObject( $res );
 299                 Wikimedia\restoreWarnings();
 300
 301                 $errno = $this->lastErrno();
 302                 // Unfortunately, mysql_fetch_object does not reset the last errno.
 303                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 304                 // these are the only errors mysql_fetch_object can cause.
 305                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 306                 if ( $errno == 2000 || $errno == 2013 ) {
 307                         throw new DBUnexpectedError(
 308                                 $this,
 309                                 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() )
 310                         );
 311                 }
 312
 313                 return $row;
 314         }
 315
 316         /**
 317          * Fetch a result row as an object
 318          *
 319          * @param resource $res Raw result
 320          * @return stdClass
 321          */
 322         abstract protected function mysqlFetchObject( $res );
 323
 324         /**
 325          * @param IResultWrapper|resource $res
 326          * @return array|bool
 327          * @throws DBUnexpectedError
 328          */
 329         public function fetchRow( $res ) {
 330                 if ( $res instanceof ResultWrapper ) {
 331                         $res = $res->result;
 332                 }
 333                 Wikimedia\suppressWarnings();
 334                 $row = $this->mysqlFetchArray( $res );
 335                 Wikimedia\restoreWarnings();
 336
 337                 $errno = $this->lastErrno();
 338                 // Unfortunately, mysql_fetch_array does not reset the last errno.
 339                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 340                 // these are the only errors mysql_fetch_array can cause.
 341                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 342                 if ( $errno == 2000 || $errno == 2013 ) {
 343                         throw new DBUnexpectedError(
 344                                 $this,
 345                                 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() )
 346                         );
 347                 }
 348
 349                 return $row;
 350         }
 351
 352         /**
 353          * Fetch a result row as an associative and numeric array
 354          *
 355          * @param resource $res Raw result
 356          * @return array
 357          */
 358         abstract protected function mysqlFetchArray( $res );
 359
 360         /**
 361          * @throws DBUnexpectedError
 362          * @param ResultWrapper|resource $res
 363          * @return int
 364          */
 365         function numRows( $res ) {
 366                 if ( $res instanceof ResultWrapper ) {
 367                         $res = $res->result;
 368                 }
 369                 Wikimedia\suppressWarnings();
 370                 $n = $res ? $this->mysqlNumRows( $res ) : 0;
 371                 Wikimedia\restoreWarnings();
 372
 373                 // Unfortunately, mysql_num_rows does not reset the last errno.
 374                 // We are not checking for any errors here, since
 375                 // there are no errors mysql_num_rows can cause.
 376                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 377                 // See https://phabricator.wikimedia.org/T44430
 378                 return $n;
 379         }
 380
 381         /**
 382          * Get number of rows in result
 383          *
 384          * @param resource $res Raw result
 385          * @return int
 386          */
 387         abstract protected function mysqlNumRows( $res );
 388
 389         /**
 390          * @param ResultWrapper|resource $res
 391          * @return int
 392          */
 393         public function numFields( $res ) {
 394                 if ( $res instanceof ResultWrapper ) {
 395                         $res = $res->result;
 396                 }
 397
 398                 return $this->mysqlNumFields( $res );
 399         }
 400
 401         /**
 402          * Get number of fields in result
 403          *
 404          * @param resource $res Raw result
 405          * @return int
 406          */
 407         abstract protected function mysqlNumFields( $res );
 408
 409         /**
 410          * @param ResultWrapper|resource $res
 411          * @param int $n
 412          * @return string
 413          */
 414         public function fieldName( $res, $n ) {
 415                 if ( $res instanceof ResultWrapper ) {
 416                         $res = $res->result;
 417                 }
 418
 419                 return $this->mysqlFieldName( $res, $n );
 420         }
 421
 422         /**
 423          * Get the name of the specified field in a result
 424          *
 425          * @param ResultWrapper|resource $res
 426          * @param int $n
 427          * @return string
 428          */
 429         abstract protected function mysqlFieldName( $res, $n );
 430
 431         /**
 432          * mysql_field_type() wrapper
 433          * @param ResultWrapper|resource $res
 434          * @param int $n
 435          * @return string
 436          */
 437         public function fieldType( $res, $n ) {
 438                 if ( $res instanceof ResultWrapper ) {
 439                         $res = $res->result;
 440                 }
 441
 442                 return $this->mysqlFieldType( $res, $n );
 443         }
 444
 445         /**
 446          * Get the type of the specified field in a result
 447          *
 448          * @param ResultWrapper|resource $res
 449          * @param int $n
 450          * @return string
 451          */
 452         abstract protected function mysqlFieldType( $res, $n );
 453
 454         /**
 455          * @param ResultWrapper|resource $res
 456          * @param int $row
 457          * @return bool
 458          */
 459         public function dataSeek( $res, $row ) {
 460                 if ( $res instanceof ResultWrapper ) {
 461                         $res = $res->result;
 462                 }
 463
 464                 return $this->mysqlDataSeek( $res, $row );
 465         }
 466
 467         /**
 468          * Move internal result pointer
 469          *
 470          * @param ResultWrapper|resource $res
 471          * @param int $row
 472          * @return bool
 473          */
 474         abstract protected function mysqlDataSeek( $res, $row );
 475
 476         /**
 477          * @return string
 478          */
 479         public function lastError() {
 480                 if ( $this->conn ) {
 481                         # Even if it's non-zero, it can still be invalid
 482                         Wikimedia\suppressWarnings();
 483                         $error = $this->mysqlError( $this->conn );
 484                         if ( !$error ) {
 485                                 $error = $this->mysqlError();
 486                         }
 487                         Wikimedia\restoreWarnings();
 488                 } else {
 489                         $error = $this->mysqlError();
 490                 }
 491                 if ( $error ) {
 492                         $error .= ' (' . $this->server . ')';
 493                 }
 494
 495                 return $error;
 496         }
 497
 498         /**
 499          * Returns the text of the error message from previous MySQL operation
 500          *
 501          * @param resource|null $conn Raw connection
 502          * @return string
 503          */
 504         abstract protected function mysqlError( $conn = null );
 505
 506         protected function wasQueryTimeout( $error, $errno ) {
 507                 return $errno == 2062;
 508         }
 509
 510         /**
 511          * @param string $table
 512          * @param array $uniqueIndexes
 513          * @param array $rows
 514          * @param string $fname
 515          * @return ResultWrapper
 516          */
 517         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
 518                 return $this->nativeReplace( $table, $rows, $fname );
 519         }
 520
 521         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
 522                 $row = $this->getReplicationSafetyInfo();
 523                 // For row-based-replication, the resulting changes will be relayed, not the query
 524                 if ( $row->binlog_format === 'ROW' ) {
 525                         return true;
 526                 }
 527                 // LIMIT requires ORDER BY on a unique key or it is non-deterministic
 528                 if ( isset( $selectOptions['LIMIT'] ) ) {
 529                         return false;
 530                 }
 531                 // In MySQL, an INSERT SELECT is only replication safe with row-based
 532                 // replication or if innodb_autoinc_lock_mode is 0. When those
 533                 // conditions aren't met, use non-native mode.
 534                 // While we could try to determine if the insert is safe anyway by
 535                 // checking if the target table has an auto-increment column that
 536                 // isn't set in $varMap, that seems unlikely to be worth the extra
 537                 // complexity.
 538                 return (
 539                         in_array( 'NO_AUTO_COLUMNS', $insertOptions ) ||
 540                         (int)$row->innodb_autoinc_lock_mode === 0
 541                 );
 542         }
 543
 544         /**
 545          * @return stdClass Process cached row
 546          */
 547         protected function getReplicationSafetyInfo() {
 548                 if ( $this->replicationInfoRow === null ) {
 549                         $this->replicationInfoRow = $this->selectRow(
 550                                 false,
 551                                 [
 552                                         'innodb_autoinc_lock_mode' => '@@innodb_autoinc_lock_mode',
 553                                         'binlog_format' => '@@binlog_format',
 554                                 ],
 555                                 [],
 556                                 __METHOD__
 557                         );
 558                 }
 559
 560                 return $this->replicationInfoRow;
 561         }
 562
 563         /**
 564          * Estimate rows in dataset
 565          * Returns estimated count, based on EXPLAIN output
 566          * Takes same arguments as Database::select()
 567          *
 568          * @param string|array $table
 569          * @param string|array $var
 570          * @param string|array $conds
 571          * @param string $fname
 572          * @param string|array $options
 573          * @param array $join_conds
 574          * @return bool|int
 575          */
 576         public function estimateRowCount( $table, $var = '*', $conds = '',
 577                 $fname = __METHOD__, $options = [], $join_conds = []
 578         ) {
 579                 $conds = $this->normalizeConditions( $conds, $fname );
 580                 $column = $this->extractSingleFieldFromList( $var );
 581                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 582                         $conds[] = "$column IS NOT NULL";
 583                 }
 584
 585                 $options['EXPLAIN'] = true;
 586                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 587                 if ( $res === false ) {
 588                         return false;
 589                 }
 590                 if ( !$this->numRows( $res ) ) {
 591                         return 0;
 592                 }
 593
 594                 $rows = 1;
 595                 foreach ( $res as $plan ) {
 596                         $rows *= $plan->rows > 0 ? $plan->rows : 1; // avoid resetting to zero
 597                 }
 598
 599                 return (int)$rows;
 600         }
 601
 602         public function tableExists( $table, $fname = __METHOD__ ) {
 603                 // Split database and table into proper variables as Database::tableName() returns
 604                 // shared tables prefixed with their database, which do not work in SHOW TABLES statements
 605                 list( $database, , $prefix, $table ) = $this->qualifiedTableComponents( $table );
 606                 $tableName = "{$prefix}{$table}";
 607
 608                 if ( isset( $this->sessionTempTables[$tableName] ) ) {
 609                         return true; // already known to exist and won't show in SHOW TABLES anyway
 610                 }
 611
 612                 // We can't use buildLike() here, because it specifies an escape character
 613                 // other than the backslash, which is the only one supported by SHOW TABLES
 614                 $encLike = $this->escapeLikeInternal( $tableName, '\\' );
 615
 616                 // If the database has been specified (such as for shared tables), use "FROM"
 617                 if ( $database !== '' ) {
 618                         $encDatabase = $this->addIdentifierQuotes( $database );
 619                         $query = "SHOW TABLES FROM $encDatabase LIKE '$encLike'";
 620                 } else {
 621                         $query = "SHOW TABLES LIKE '$encLike'";
 622                 }
 623
 624                 return $this->query( $query, $fname )->numRows() > 0;
 625         }
 626
 627         /**
 628          * @param string $table
 629          * @param string $field
 630          * @return bool|MySQLField
 631          */
 632         public function fieldInfo( $table, $field ) {
 633                 $table = $this->tableName( $table );
 634                 $res = $this->query( "SELECT * FROM $table LIMIT 1", __METHOD__, true );
 635                 if ( !$res ) {
 636                         return false;
 637                 }
 638                 $n = $this->mysqlNumFields( $res->result );
 639                 for ( $i = 0; $i < $n; $i++ ) {
 640                         $meta = $this->mysqlFetchField( $res->result, $i );
 641                         if ( $field == $meta->name ) {
 642                                 return new MySQLField( $meta );
 643                         }
 644                 }
 645
 646                 return false;
 647         }
 648
 649         /**
 650          * Get column information from a result
 651          *
 652          * @param resource $res Raw result
 653          * @param int $n
 654          * @return stdClass
 655          */
 656         abstract protected function mysqlFetchField( $res, $n );
 657
 658         /**
 659          * Get information about an index into an object
 660          * Returns false if the index does not exist
 661          *
 662          * @param string $table
 663          * @param string $index
 664          * @param string $fname
 665          * @return bool|array|null False or null on failure
 666          */
 667         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 668                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 669                 # SHOW INDEX should work for 3.x and up:
 670                 # https://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 671                 $table = $this->tableName( $table );
 672                 $index = $this->indexName( $index );
 673
 674                 $sql = 'SHOW INDEX FROM ' . $table;
 675                 $res = $this->query( $sql, $fname );
 676
 677                 if ( !$res ) {
 678                         return null;
 679                 }
 680
 681                 $result = [];
 682
 683                 foreach ( $res as $row ) {
 684                         if ( $row->Key_name == $index ) {
 685                                 $result[] = $row;
 686                         }
 687                 }
 688
 689                 return $result ?: false;
 690         }
 691
 692         /**
 693          * @param string $s
 694          * @return string
 695          */
 696         public function strencode( $s ) {
 697                 return $this->mysqlRealEscapeString( $s );
 698         }
 699
 700         /**
 701          * @param string $s
 702          * @return mixed
 703          */
 704         abstract protected function mysqlRealEscapeString( $s );
 705
 706         public function addQuotes( $s ) {
 707                 if ( is_bool( $s ) ) {
 708                         // Parent would transform to int, which does not play nice with MySQL type juggling.
 709                         // When searching for an int in a string column, the strings are cast to int, which
 710                         // means false would match any string not starting with a number.
 711                         $s = (string)(int)$s;
 712                 }
 713                 return parent::addQuotes( $s );
 714         }
 715
 716         /**
 717          * MySQL uses `backticks` for identifier quoting instead of the sql standard "double quotes".
 718          *
 719          * @param string $s
 720          * @return string
 721          */
 722         public function addIdentifierQuotes( $s ) {
 723                 // Characters in the range \u0001-\uFFFF are valid in a quoted identifier
 724                 // Remove NUL bytes and escape backticks by doubling
 725                 return '`' . str_replace( [ "\0", '`' ], [ '', '``' ], $s ) . '`';
 726         }
 727
 728         /**
 729          * @param string $name
 730          * @return bool
 731          */
 732         public function isQuotedIdentifier( $name ) {
 733                 return strlen( $name ) && $name[0] == '`' && substr( $name, -1, 1 ) == '`';
 734         }
 735
 736         public function getLag() {
 737                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 738                         return $this->getLagFromPtHeartbeat();
 739                 } else {
 740                         return $this->getLagFromSlaveStatus();
 741                 }
 742         }
 743
 744         /**
 745          * @return string
 746          */
 747         protected function getLagDetectionMethod() {
 748                 return $this->lagDetectionMethod;
 749         }
 750
 751         /**
 752          * @return bool|int
 753          */
 754         protected function getLagFromSlaveStatus() {
 755                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
 756                 $row = $res ? $res->fetchObject() : false;
 757                 // If the server is not replicating, there will be no row
 758                 if ( $row && strval( $row->Seconds_Behind_Master ) !== '' ) {
 759                         return intval( $row->Seconds_Behind_Master );
 760                 }
 761
 762                 return false;
 763         }
 764
 765         /**
 766          * @return bool|float
 767          */
 768         protected function getLagFromPtHeartbeat() {
 769                 $options = $this->lagDetectionOptions;
 770
 771                 $currentTrxInfo = $this->getRecordedTransactionLagStatus();
 772                 if ( $currentTrxInfo ) {
 773                         // There is an active transaction and the initial lag was already queried
 774                         $staleness = microtime( true ) - $currentTrxInfo['since'];
 775                         if ( $staleness > self::LAG_STALE_WARN_THRESHOLD ) {
 776                                 // Avoid returning higher and higher lag value due to snapshot age
 777                                 // given that the isolation level will typically be REPEATABLE-READ
 778                                 $this->queryLogger->warning(
 779                                         "Using cached lag value for {db_server} due to active transaction",
 780                                         $this->getLogContext( [ 'method' => __METHOD__, 'age' => $staleness ] )
 781                                 );
 782                         }
 783
 784                         return $currentTrxInfo['lag'];
 785                 }
 786
 787                 if ( isset( $options['conds'] ) ) {
 788                         // Best method for multi-DC setups: use logical channel names
 789                         $data = $this->getHeartbeatData( $options['conds'] );
 790                 } else {
 791                         // Standard method: use master server ID (works with stock pt-heartbeat)
 792                         $masterInfo = $this->getMasterServerInfo();
 793                         if ( !$masterInfo ) {
 794                                 $this->queryLogger->error(
 795                                         "Unable to query master of {db_server} for server ID",
 796                                         $this->getLogContext( [
 797                                                 'method' => __METHOD__
 798                                         ] )
 799                                 );
 800
 801                                 return false; // could not get master server ID
 802                         }
 803
 804                         $conds = [ 'server_id' => intval( $masterInfo['serverId'] ) ];
 805                         $data = $this->getHeartbeatData( $conds );
 806                 }
 807
 808                 list( $time, $nowUnix ) = $data;
 809                 if ( $time !== null ) {
 810                         // @time is in ISO format like "2015-09-25T16:48:10.000510"
 811                         $dateTime = new DateTime( $time, new DateTimeZone( 'UTC' ) );
 812                         $timeUnix = (int)$dateTime->format( 'U' ) + $dateTime->format( 'u' ) / 1e6;
 813
 814                         return max( $nowUnix - $timeUnix, 0.0 );
 815                 }
 816
 817                 $this->queryLogger->error(
 818                         "Unable to find pt-heartbeat row for {db_server}",
 819                         $this->getLogContext( [
 820                                 'method' => __METHOD__
 821                         ] )
 822                 );
 823
 824                 return false;
 825         }
 826
 827         protected function getMasterServerInfo() {
 828                 $cache = $this->srvCache;
 829                 $key = $cache->makeGlobalKey(
 830                         'mysql',
 831                         'master-info',
 832                         // Using one key for all cluster replica DBs is preferable
 833                         $this->getLBInfo( 'clusterMasterHost' ) ?: $this->getServer()
 834                 );
 835
 836                 return $cache->getWithSetCallback(
 837                         $key,
 838                         $cache::TTL_INDEFINITE,
 839                         function () use ( $cache, $key ) {
 840                                 // Get and leave a lock key in place for a short period
 841                                 if ( !$cache->lock( $key, 0, 10 ) ) {
 842                                         return false; // avoid master connection spike slams
 843                                 }
 844
 845                                 $conn = $this->getLazyMasterHandle();
 846                                 if ( !$conn ) {
 847                                         return false; // something is misconfigured
 848                                 }
 849
 850                                 // Connect to and query the master; catch errors to avoid outages
 851                                 try {
 852                                         $res = $conn->query( 'SELECT @@server_id AS id', __METHOD__ );
 853                                         $row = $res ? $res->fetchObject() : false;
 854                                         $id = $row ? (int)$row->id : 0;
 855                                 } catch ( DBError $e ) {
 856                                         $id = 0;
 857                                 }
 858
 859                                 // Cache the ID if it was retrieved
 860                                 return $id ? [ 'serverId' => $id, 'asOf' => time() ] : false;
 861                         }
 862                 );
 863         }
 864
 865         /**
 866          * @param array $conds WHERE clause conditions to find a row
 867          * @return array (heartbeat `ts` column value or null, UNIX timestamp) for the newest beat
 868          * @see https://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html
 869          */
 870         protected function getHeartbeatData( array $conds ) {
 871                 // Query time and trip time are not counted
 872                 $nowUnix = microtime( true );
 873                 // Do not bother starting implicit transactions here
 874                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
 875                 try {
 876                         $whereSQL = $this->makeList( $conds, self::LIST_AND );
 877                         // Use ORDER BY for channel based queries since that field might not be UNIQUE.
 878                         // Note: this would use "TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6))" but the
 879                         // percision field is not supported in MySQL <= 5.5.
 880                         $res = $this->query(
 881                                 "SELECT ts FROM heartbeat.heartbeat WHERE $whereSQL ORDER BY ts DESC LIMIT 1",
 882                                 __METHOD__
 883                         );
 884                         $row = $res ? $res->fetchObject() : false;
 885                 } finally {
 886                         $this->restoreFlags();
 887                 }
 888
 889                 return [ $row ? $row->ts : null, $nowUnix ];
 890         }
 891
 892         protected function getApproximateLagStatus() {
 893                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 894                         // Disable caching since this is fast enough and we don't wan't
 895                         // to be *too* pessimistic by having both the cache TTL and the
 896                         // pt-heartbeat interval count as lag in getSessionLagStatus()
 897                         return parent::getApproximateLagStatus();
 898                 }
 899
 900                 $key = $this->srvCache->makeGlobalKey( 'mysql-lag', $this->getServer() );
 901                 $approxLag = $this->srvCache->get( $key );
 902                 if ( !$approxLag ) {
 903                         $approxLag = parent::getApproximateLagStatus();
 904                         $this->srvCache->set( $key, $approxLag, 1 );
 905                 }
 906
 907                 return $approxLag;
 908         }
 909
 910         public function masterPosWait( DBMasterPos $pos, $timeout ) {
 911                 if ( !( $pos instanceof MySQLMasterPos ) ) {
 912                         throw new InvalidArgumentException( "Position not an instance of MySQLMasterPos" );
 913                 }
 914
 915                 if ( $this->getLBInfo( 'is static' ) === true ) {
 916                         return 0; // this is a copy of a read-only dataset with no master DB
 917                 } elseif ( $this->lastKnownReplicaPos && $this->lastKnownReplicaPos->hasReached( $pos ) ) {
 918                         return 0; // already reached this point for sure
 919                 }
 920
 921                 // Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
 922                 if ( $pos->getGTIDs() ) {
 923                         // Ignore GTIDs from domains exclusive to the master DB (presumably inactive)
 924                         $rpos = $this->getReplicaPos();
 925                         $gtidsWait = $rpos ? MySQLMasterPos::getCommonDomainGTIDs( $pos, $rpos ) : [];
 926                         if ( !$gtidsWait ) {
 927                                 $this->queryLogger->error(
 928                                         "No GTIDs with the same domain between master ($pos) and replica ($rpos)",
 929                                         $this->getLogContext( [
 930                                                 'method' => __METHOD__,
 931                                         ] )
 932                                 );
 933
 934                                 return -1; // $pos is from the wrong cluster?
 935                         }
 936                         // Wait on the GTID set (MariaDB only)
 937                         $gtidArg = $this->addQuotes( implode( ',', $gtidsWait ) );
 938                         if ( strpos( $gtidArg, ':' ) !== false ) {
 939                                 // MySQL GTIDs, e.g "source_id:transaction_id"
 940                                 $res = $this->doQuery( "SELECT WAIT_FOR_EXECUTED_GTID_SET($gtidArg, $timeout)" );
 941                         } else {
 942                                 // MariaDB GTIDs, e.g."domain:server:sequence"
 943                                 $res = $this->doQuery( "SELECT MASTER_GTID_WAIT($gtidArg, $timeout)" );
 944                         }
 945                 } else {
 946                         // Wait on the binlog coordinates
 947                         $encFile = $this->addQuotes( $pos->getLogFile() );
 948                         $encPos = intval( $pos->getLogPosition()[$pos::CORD_EVENT] );
 949                         $res = $this->doQuery( "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)" );
 950                 }
 951
 952                 $row = $res ? $this->fetchRow( $res ) : false;
 953                 if ( !$row ) {
 954                         throw new DBExpectedError( $this, "Replication wait failed: {$this->lastError()}" );
 955                 }
 956
 957                 // Result can be NULL (error), -1 (timeout), or 0+ per the MySQL manual
 958                 $status = ( $row[0] !== null ) ? intval( $row[0] ) : null;
 959                 if ( $status === null ) {
 960                         if ( !$pos->getGTIDs() ) {
 961                                 // T126436: jobs programmed to wait on master positions might be referencing
 962                                 // binlogs with an old master hostname; this makes MASTER_POS_WAIT() return null.
 963                                 // Try to detect this case and treat the replica DB as having reached the given
 964                                 // position (any master switchover already requires that the new master be caught
 965                                 // up before the switch).
 966                                 $replicationPos = $this->getReplicaPos();
 967                                 if ( $replicationPos && !$replicationPos->channelsMatch( $pos ) ) {
 968                                         $this->lastKnownReplicaPos = $replicationPos;
 969                                         $status = 0;
 970                                 }
 971                         }
 972                 } elseif ( $status >= 0 ) {
 973                         // Remember that this position was reached to save queries next time
 974                         $this->lastKnownReplicaPos = $pos;
 975                 }
 976
 977                 return $status;
 978         }
 979
 980         /**
 981          * Get the position of the master from SHOW SLAVE STATUS
 982          *
 983          * @return MySQLMasterPos|bool
 984          */
 985         public function getReplicaPos() {
 986                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
 987
 988                 if ( $this->useGTIDs() ) {
 989                         // Try to use GTIDs, fallbacking to binlog positions if not possible
 990                         $data = $this->getServerGTIDs( __METHOD__ );
 991                         // Use gtid_slave_pos for MariaDB and gtid_executed for MySQL
 992                         foreach ( [ 'gtid_slave_pos', 'gtid_executed' ] as $name ) {
 993                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
 994                                         return new MySQLMasterPos( $data[$name], $now );
 995                                 }
 996                         }
 997                 }
 998
 999                 $data = $this->getServerRoleStatus( 'SLAVE', __METHOD__ );
1000                 if ( $data && strlen( $data['Relay_Master_Log_File'] ) ) {
1001                         return new MySQLMasterPos(
1002                                 "{$data['Relay_Master_Log_File']}/{$data['Exec_Master_Log_Pos']}",
1003                                 $now
1004                         );
1005                 }
1006
1007                 return false;
1008         }
1009
1010         /**
1011          * Get the position of the master from SHOW MASTER STATUS
1012          *
1013          * @return MySQLMasterPos|bool
1014          */
1015         public function getMasterPos() {
1016                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
1017
1018                 $pos = false;
1019                 if ( $this->useGTIDs() ) {
1020                         // Try to use GTIDs, fallbacking to binlog positions if not possible
1021                         $data = $this->getServerGTIDs( __METHOD__ );
1022                         // Use gtid_binlog_pos for MariaDB and gtid_executed for MySQL
1023                         foreach ( [ 'gtid_binlog_pos', 'gtid_executed' ] as $name ) {
1024                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
1025                                         $pos = new MySQLMasterPos( $data[$name], $now );
1026                                         break;
1027                                 }
1028                         }
1029                         // Filter domains that are inactive or not relevant to the session
1030                         if ( $pos ) {
1031                                 $pos->setActiveOriginServerId( $this->getServerId() );
1032                                 $pos->setActiveOriginServerUUID( $this->getServerUUID() );
1033                                 if ( isset( $data['gtid_domain_id'] ) ) {
1034                                         $pos->setActiveDomain( $data['gtid_domain_id'] );
1035                                 }
1036                         }
1037                 }
1038
1039                 if ( !$pos ) {
1040                         $data = $this->getServerRoleStatus( 'MASTER', __METHOD__ );
1041                         if ( $data && strlen( $data['File'] ) ) {
1042                                 $pos = new MySQLMasterPos( "{$data['File']}/{$data['Position']}", $now );
1043                         }
1044                 }
1045
1046                 return $pos;
1047         }
1048
1049         /**
1050          * @return int
1051          * @throws DBQueryError If the variable doesn't exist for some reason
1052          */
1053         protected function getServerId() {
1054                 return $this->srvCache->getWithSetCallback(
1055                         $this->srvCache->makeGlobalKey( 'mysql-server-id', $this->getServer() ),
1056                         self::SERVER_ID_CACHE_TTL,
1057                         function () {
1058                                 $res = $this->query( "SELECT @@server_id AS id", __METHOD__ );
1059                                 return intval( $this->fetchObject( $res )->id );
1060                         }
1061                 );
1062         }
1063
1064         /**
1065          * @return string|null
1066          */
1067         protected function getServerUUID() {
1068                 return $this->srvCache->getWithSetCallback(
1069                         $this->srvCache->makeGlobalKey( 'mysql-server-uuid', $this->getServer() ),
1070                         self::SERVER_ID_CACHE_TTL,
1071                         function () {
1072                                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'server_uuid'" );
1073                                 $row = $this->fetchObject( $res );
1074
1075                                 return $row ? $row->Value : null;
1076                         }
1077                 );
1078         }
1079
1080         /**
1081          * @param string $fname
1082          * @return string[]
1083          */
1084         protected function getServerGTIDs( $fname = __METHOD__ ) {
1085                 $map = [];
1086                 // Get global-only variables like gtid_executed
1087                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'gtid_%'", $fname );
1088                 foreach ( $res as $row ) {
1089                         $map[$row->Variable_name] = $row->Value;
1090                 }
1091                 // Get session-specific (e.g. gtid_domain_id since that is were writes will log)
1092                 $res = $this->query( "SHOW SESSION VARIABLES LIKE 'gtid_%'", $fname );
1093                 foreach ( $res as $row ) {
1094                         $map[$row->Variable_name] = $row->Value;
1095                 }
1096
1097                 return $map;
1098         }
1099
1100         /**
1101          * @param string $role One of "MASTER"/"SLAVE"
1102          * @param string $fname
1103          * @return string[] Latest available server status row
1104          */
1105         protected function getServerRoleStatus( $role, $fname = __METHOD__ ) {
1106                 return $this->query( "SHOW $role STATUS", $fname )->fetchRow() ?: [];
1107         }
1108
1109         public function serverIsReadOnly() {
1110                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'read_only'", __METHOD__ );
1111                 $row = $this->fetchObject( $res );
1112
1113                 return $row ? ( strtolower( $row->Value ) === 'on' ) : false;
1114         }
1115
1116         /**
1117          * @param string $index
1118          * @return string
1119          */
1120         function useIndexClause( $index ) {
1121                 return "FORCE INDEX (" . $this->indexName( $index ) . ")";
1122         }
1123
1124         /**
1125          * @param string $index
1126          * @return string
1127          */
1128         function ignoreIndexClause( $index ) {
1129                 return "IGNORE INDEX (" . $this->indexName( $index ) . ")";
1130         }
1131
1132         /**
1133          * @return string
1134          */
1135         function lowPriorityOption() {
1136                 return 'LOW_PRIORITY';
1137         }
1138
1139         /**
1140          * @return string
1141          */
1142         public function getSoftwareLink() {
1143                 // MariaDB includes its name in its version string; this is how MariaDB's version of
1144                 // the mysql command-line client identifies MariaDB servers (see mariadb_connection()
1145                 // in libmysql/libmysql.c).
1146                 $version = $this->getServerVersion();
1147                 if ( strpos( $version, 'MariaDB' ) !== false || strpos( $version, '-maria-' ) !== false ) {
1148                         return '[{{int:version-db-mariadb-url}} MariaDB]';
1149                 }
1150
1151                 // Percona Server's version suffix is not very distinctive, and @@version_comment
1152                 // doesn't give the necessary info for source builds, so assume the server is MySQL.
1153                 // (Even Percona's version of mysql doesn't try to make the distinction.)
1154                 return '[{{int:version-db-mysql-url}} MySQL]';
1155         }
1156
1157         /**
1158          * @return string
1159          */
1160         public function getServerVersion() {
1161                 // Not using mysql_get_server_info() or similar for consistency: in the handshake,
1162                 // MariaDB 10 adds the prefix "5.5.5-", and only some newer client libraries strip
1163                 // it off (see RPL_VERSION_HACK in include/mysql_com.h).
1164                 if ( $this->serverVersion === null ) {
1165                         $this->serverVersion = $this->selectField( '', 'VERSION()', '', __METHOD__ );
1166                 }
1167                 return $this->serverVersion;
1168         }
1169
1170         /**
1171          * @param array $options
1172          */
1173         public function setSessionOptions( array $options ) {
1174                 if ( isset( $options['connTimeout'] ) ) {
1175                         $timeout = (int)$options['connTimeout'];
1176                         $this->query( "SET net_read_timeout=$timeout" );
1177                         $this->query( "SET net_write_timeout=$timeout" );
1178                 }
1179         }
1180
1181         /**
1182          * @param string &$sql
1183          * @param string &$newLine
1184          * @return bool
1185          */
1186         public function streamStatementEnd( &$sql, &$newLine ) {
1187                 if ( strtoupper( substr( $newLine, 0, 9 ) ) == 'DELIMITER' ) {
1188                         preg_match( '/^DELIMITER\s+(\S+)/', $newLine, $m );
1189                         $this->delimiter = $m[1];
1190                         $newLine = '';
1191                 }
1192
1193                 return parent::streamStatementEnd( $sql, $newLine );
1194         }
1195
1196         /**
1197          * Check to see if a named lock is available. This is non-blocking.
1198          *
1199          * @param string $lockName Name of lock to poll
1200          * @param string $method Name of method calling us
1201          * @return bool
1202          * @since 1.20
1203          */
1204         public function lockIsFree( $lockName, $method ) {
1205                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1206                         return false; // already held
1207                 }
1208
1209                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1210                 $result = $this->query( "SELECT IS_FREE_LOCK($encName) AS lockstatus", $method );
1211                 $row = $this->fetchObject( $result );
1212
1213                 return ( $row->lockstatus == 1 );
1214         }
1215
1216         /**
1217          * @param string $lockName
1218          * @param string $method
1219          * @param int $timeout
1220          * @return bool
1221          */
1222         public function lock( $lockName, $method, $timeout = 5 ) {
1223                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1224                 $result = $this->query( "SELECT GET_LOCK($encName, $timeout) AS lockstatus", $method );
1225                 $row = $this->fetchObject( $result );
1226
1227                 if ( $row->lockstatus == 1 ) {
1228                         parent::lock( $lockName, $method, $timeout ); // record
1229                         return true;
1230                 }
1231
1232                 $this->queryLogger->info( __METHOD__ . " failed to acquire lock '{lockname}'",
1233                         [ 'lockname' => $lockName ] );
1234
1235                 return false;
1236         }
1237
1238         /**
1239          * FROM MYSQL DOCS:
1240          * https://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock
1241          * @param string $lockName
1242          * @param string $method
1243          * @return bool
1244          */
1245         public function unlock( $lockName, $method ) {
1246                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1247                 $result = $this->query( "SELECT RELEASE_LOCK($encName) as lockstatus", $method );
1248                 $row = $this->fetchObject( $result );
1249
1250                 if ( $row->lockstatus == 1 ) {
1251                         parent::unlock( $lockName, $method ); // record
1252                         return true;
1253                 }
1254
1255                 $this->queryLogger->warning( __METHOD__ . " failed to release lock '$lockName'\n" );
1256
1257                 return false;
1258         }
1259
1260         private function makeLockName( $lockName ) {
1261                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1262                 // Newer version enforce a 64 char length limit.
1263                 return ( strlen( $lockName ) > 64 ) ? sha1( $lockName ) : $lockName;
1264         }
1265
1266         public function namedLocksEnqueue() {
1267                 return true;
1268         }
1269
1270         public function tableLocksHaveTransactionScope() {
1271                 return false; // tied to TCP connection
1272         }
1273
1274         protected function doLockTables( array $read, array $write, $method ) {
1275                 $items = [];
1276                 foreach ( $write as $table ) {
1277                         $items[] = $this->tableName( $table ) . ' WRITE';
1278                 }
1279                 foreach ( $read as $table ) {
1280                         $items[] = $this->tableName( $table ) . ' READ';
1281                 }
1282
1283                 $sql = "LOCK TABLES " . implode( ',', $items );
1284                 $this->query( $sql, $method );
1285
1286                 return true;
1287         }
1288
1289         protected function doUnlockTables( $method ) {
1290                 $this->query( "UNLOCK TABLES", $method );
1291
1292                 return true;
1293         }
1294
1295         /**
1296          * @param bool $value
1297          */
1298         public function setBigSelects( $value = true ) {
1299                 if ( $value === 'default' ) {
1300                         if ( $this->defaultBigSelects === null ) {
1301                                 # Function hasn't been called before so it must already be set to the default
1302                                 return;
1303                         } else {
1304                                 $value = $this->defaultBigSelects;
1305                         }
1306                 } elseif ( $this->defaultBigSelects === null ) {
1307                         $this->defaultBigSelects =
1308                                 (bool)$this->selectField( false, '@@sql_big_selects', '', __METHOD__ );
1309                 }
1310                 $encValue = $value ? '1' : '0';
1311                 $this->query( "SET sql_big_selects=$encValue", __METHOD__ );
1312         }
1313
1314         /**
1315          * DELETE where the condition is a join. MySql uses multi-table deletes.
1316          * @param string $delTable
1317          * @param string $joinTable
1318          * @param string $delVar
1319          * @param string $joinVar
1320          * @param array|string $conds
1321          * @param bool|string $fname
1322          * @throws DBUnexpectedError
1323          * @return bool|ResultWrapper
1324          */
1325         public function deleteJoin(
1326                 $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__
1327         ) {
1328                 if ( !$conds ) {
1329                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
1330                 }
1331
1332                 $delTable = $this->tableName( $delTable );
1333                 $joinTable = $this->tableName( $joinTable );
1334                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1335
1336                 if ( $conds != '*' ) {
1337                         $sql .= ' AND ' . $this->makeList( $conds, self::LIST_AND );
1338                 }
1339
1340                 return $this->query( $sql, $fname );
1341         }
1342
1343         /**
1344          * @param string $table
1345          * @param array $rows
1346          * @param array $uniqueIndexes
1347          * @param array $set
1348          * @param string $fname
1349          * @return bool
1350          */
1351         public function upsert( $table, array $rows, array $uniqueIndexes,
1352                 array $set, $fname = __METHOD__
1353         ) {
1354                 if ( !count( $rows ) ) {
1355                         return true; // nothing to do
1356                 }
1357
1358                 if ( !is_array( reset( $rows ) ) ) {
1359                         $rows = [ $rows ];
1360                 }
1361
1362                 $table = $this->tableName( $table );
1363                 $columns = array_keys( $rows[0] );
1364
1365                 $sql = "INSERT INTO $table (" . implode( ',', $columns ) . ') VALUES ';
1366                 $rowTuples = [];
1367                 foreach ( $rows as $row ) {
1368                         $rowTuples[] = '(' . $this->makeList( $row ) . ')';
1369                 }
1370                 $sql .= implode( ',', $rowTuples );
1371                 $sql .= " ON DUPLICATE KEY UPDATE " . $this->makeList( $set, self::LIST_SET );
1372
1373                 return (bool)$this->query( $sql, $fname );
1374         }
1375
1376         /**
1377          * Determines how long the server has been up
1378          *
1379          * @return int
1380          */
1381         public function getServerUptime() {
1382                 $vars = $this->getMysqlStatus( 'Uptime' );
1383
1384                 return (int)$vars['Uptime'];
1385         }
1386
1387         /**
1388          * Determines if the last failure was due to a deadlock
1389          *
1390          * @return bool
1391          */
1392         public function wasDeadlock() {
1393                 return $this->lastErrno() == 1213;
1394         }
1395
1396         /**
1397          * Determines if the last failure was due to a lock timeout
1398          *
1399          * @return bool
1400          */
1401         public function wasLockTimeout() {
1402                 return $this->lastErrno() == 1205;
1403         }
1404
1405         /**
1406          * Determines if the last failure was due to the database being read-only.
1407          *
1408          * @return bool
1409          */
1410         public function wasReadOnlyError() {
1411                 return $this->lastErrno() == 1223 ||
1412                         ( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
1413         }
1414
1415         public function wasConnectionError( $errno ) {
1416                 return $errno == 2013 || $errno == 2006;
1417         }
1418
1419         protected function wasKnownStatementRollbackError() {
1420                 $errno = $this->lastErrno();
1421
1422                 if ( $errno === 1205 ) { // lock wait timeout
1423                         // Note that this is uncached to avoid stale values of SET is used
1424                         $row = $this->selectRow(
1425                                 false,
1426                                 [ 'innodb_rollback_on_timeout' => '@@innodb_rollback_on_timeout' ],
1427                                 [],
1428                                 __METHOD__
1429                         );
1430                         // https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
1431                         // https://dev.mysql.com/doc/refman/5.5/en/innodb-parameters.html
1432                         return $row->innodb_rollback_on_timeout ? false : true;
1433                 }
1434
1435                 // See https://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html
1436                 return in_array( $errno, [ 1022, 1216, 1217, 1137 ], true );
1437         }
1438
1439         /**
1440          * @param string $oldName
1441          * @param string $newName
1442          * @param bool $temporary
1443          * @param string $fname
1444          * @return bool
1445          */
1446         public function duplicateTableStructure(
1447                 $oldName, $newName, $temporary = false, $fname = __METHOD__
1448         ) {
1449                 $tmp = $temporary ? 'TEMPORARY ' : '';
1450                 $newName = $this->addIdentifierQuotes( $newName );
1451                 $oldName = $this->addIdentifierQuotes( $oldName );
1452                 $query = "CREATE $tmp TABLE $newName (LIKE $oldName)";
1453
1454                 return $this->query( $query, $fname );
1455         }
1456
1457         /**
1458          * List all tables on the database
1459          *
1460          * @param string|null $prefix Only show tables with this prefix, e.g. mw_
1461          * @param string $fname Calling function name
1462          * @return array
1463          */
1464         public function listTables( $prefix = null, $fname = __METHOD__ ) {
1465                 $result = $this->query( "SHOW TABLES", $fname );
1466
1467                 $endArray = [];
1468
1469                 foreach ( $result as $table ) {
1470                         $vars = get_object_vars( $table );
1471                         $table = array_pop( $vars );
1472
1473                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1474                                 $endArray[] = $table;
1475                         }
1476                 }
1477
1478                 return $endArray;
1479         }
1480
1481         /**
1482          * @param string $tableName
1483          * @param string $fName
1484          * @return bool|ResultWrapper
1485          */
1486         public function dropTable( $tableName, $fName = __METHOD__ ) {
1487                 if ( !$this->tableExists( $tableName, $fName ) ) {
1488                         return false;
1489                 }
1490
1491                 return $this->query( "DROP TABLE IF EXISTS " . $this->tableName( $tableName ), $fName );
1492         }
1493
1494         /**
1495          * Get status information from SHOW STATUS in an associative array
1496          *
1497          * @param string $which
1498          * @return array
1499          */
1500         private function getMysqlStatus( $which = "%" ) {
1501                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1502                 $status = [];
1503
1504                 foreach ( $res as $row ) {
1505                         $status[$row->Variable_name] = $row->Value;
1506                 }
1507
1508                 return $status;
1509         }
1510
1511         /**
1512          * Lists VIEWs in the database
1513          *
1514          * @param string|null $prefix Only show VIEWs with this prefix, eg.
1515          * unit_test_, or $wgDBprefix. Default: null, would return all views.
1516          * @param string $fname Name of calling function
1517          * @return array
1518          * @since 1.22
1519          */
1520         public function listViews( $prefix = null, $fname = __METHOD__ ) {
1521                 // The name of the column containing the name of the VIEW
1522                 $propertyName = 'Tables_in_' . $this->dbName;
1523
1524                 // Query for the VIEWS
1525                 $res = $this->query( 'SHOW FULL TABLES WHERE TABLE_TYPE = "VIEW"' );
1526                 $allViews = [];
1527                 foreach ( $res as $row ) {
1528                         array_push( $allViews, $row->$propertyName );
1529                 }
1530
1531                 if ( is_null( $prefix ) || $prefix === '' ) {
1532                         return $allViews;
1533                 }
1534
1535                 $filteredViews = [];
1536                 foreach ( $allViews as $viewName ) {
1537                         // Does the name of this VIEW start with the table-prefix?
1538                         if ( strpos( $viewName, $prefix ) === 0 ) {
1539                                 array_push( $filteredViews, $viewName );
1540                         }
1541                 }
1542
1543                 return $filteredViews;
1544         }
1545
1546         /**
1547          * Differentiates between a TABLE and a VIEW.
1548          *
1549          * @param string $name Name of the TABLE/VIEW to test
1550          * @param string|null $prefix
1551          * @return bool
1552          * @since 1.22
1553          */
1554         public function isView( $name, $prefix = null ) {
1555                 return in_array( $name, $this->listViews( $prefix ) );
1556         }
1557
1558         protected function isTransactableQuery( $sql ) {
1559                 return parent::isTransactableQuery( $sql ) &&
1560                         !preg_match( '/^SELECT\s+(GET|RELEASE|IS_FREE)_LOCK\(/', $sql );
1561         }
1562
1563         /**
1564          * @param string $field Field or column to cast
1565          * @return string
1566          */
1567         public function buildIntegerCast( $field ) {
1568                 return 'CAST( ' . $field . ' AS SIGNED )';
1569         }
1570
1571         /*
1572          * @return bool Whether GTID support is used (mockable for testing)
1573          */
1574         protected function useGTIDs() {
1575                 return $this->useGTIDs;
1576         }
1577 }
1578
1579 /**
1580  * @deprecated since 1.29
1581  */
1582 class_alias( DatabaseMysqlBase::class, 'DatabaseMysqlBase' );