includes/libs/rdbms/database/DatabaseMysqlBase.php

   1 <?php
   2 /**
   3  * This is the MySQL database abstraction layer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23 namespace Wikimedia\Rdbms;
  24
  25 use DateTime;
  26 use DateTimeZone;
  27 use Wikimedia;
  28 use InvalidArgumentException;
  29 use Exception;
  30 use RuntimeException;
  31 use stdClass;
  32
  33 /**
  34  * Database abstraction object for MySQL.
  35  * Defines methods independent on used MySQL extension.
  36  *
  37  * @ingroup Database
  38  * @since 1.22
  39  * @see Database
  40  */
  41 abstract class DatabaseMysqlBase extends Database {
  42         /** @var MysqlMasterPos */
  43         protected $lastKnownReplicaPos;
  44         /** @var string Method to detect replica DB lag */
  45         protected $lagDetectionMethod;
  46         /** @var array Method to detect replica DB lag */
  47         protected $lagDetectionOptions = [];
  48         /** @var bool bool Whether to use GTID methods */
  49         protected $useGTIDs = false;
  50         /** @var string|null */
  51         protected $sslKeyPath;
  52         /** @var string|null */
  53         protected $sslCertPath;
  54         /** @var string|null */
  55         protected $sslCAFile;
  56         /** @var string|null */
  57         protected $sslCAPath;
  58         /** @var string[]|null */
  59         protected $sslCiphers;
  60         /** @var string sql_mode value to send on connection */
  61         protected $sqlMode;
  62         /** @var bool Use experimental UTF-8 transmission encoding */
  63         protected $utf8Mode;
  64         /** @var bool|null */
  65         protected $defaultBigSelects = null;
  66
  67         /** @var string|null */
  68         private $serverVersion = null;
  69         /** @var bool|null */
  70         private $insertSelectIsSafe = null;
  71         /** @var stdClass|null */
  72         private $replicationInfoRow = null;
  73
  74         // Cache getServerId() for 24 hours
  75         const SERVER_ID_CACHE_TTL = 86400;
  76
  77         /** @var float Warn if lag estimates are made for transactions older than this many seconds */
  78         const LAG_STALE_WARN_THRESHOLD = 0.100;
  79
  80         /**
  81          * Additional $params include:
  82          *   - lagDetectionMethod : set to one of (Seconds_Behind_Master,pt-heartbeat).
  83          *       pt-heartbeat assumes the table is at heartbeat.heartbeat
  84          *       and uses UTC timestamps in the heartbeat.ts column.
  85          *       (https://www.percona.com/doc/percona-toolkit/2.2/pt-heartbeat.html)
  86          *   - lagDetectionOptions : if using pt-heartbeat, this can be set to an array map to change
  87          *       the default behavior. Normally, the heartbeat row with the server
  88          *       ID of this server's master will be used. Set the "conds" field to
  89          *       override the query conditions, e.g. ['shard' => 's1'].
  90          *   - useGTIDs : use GTID methods like MASTER_GTID_WAIT() when possible.
  91          *   - insertSelectIsSafe : force that native INSERT SELECT is or is not safe [default: null]
  92          *   - sslKeyPath : path to key file [default: null]
  93          *   - sslCertPath : path to certificate file [default: null]
  94          *   - sslCAFile: path to a single certificate authority PEM file [default: null]
  95          *   - sslCAPath : parth to certificate authority PEM directory [default: null]
  96          *   - sslCiphers : array list of allowable ciphers [default: null]
  97          * @param array $params
  98          */
  99         function __construct( array $params ) {
 100                 $this->lagDetectionMethod = $params['lagDetectionMethod'] ?? 'Seconds_Behind_Master';
 101                 $this->lagDetectionOptions = $params['lagDetectionOptions'] ?? [];
 102                 $this->useGTIDs = !empty( $params['useGTIDs' ] );
 103                 foreach ( [ 'KeyPath', 'CertPath', 'CAFile', 'CAPath', 'Ciphers' ] as $name ) {
 104                         $var = "ssl{$name}";
 105                         if ( isset( $params[$var] ) ) {
 106                                 $this->$var = $params[$var];
 107                         }
 108                 }
 109                 $this->sqlMode = $params['sqlMode'] ?? null;
 110                 $this->utf8Mode = !empty( $params['utf8Mode'] );
 111                 $this->insertSelectIsSafe = isset( $params['insertSelectIsSafe'] )
 112                         ? (bool)$params['insertSelectIsSafe'] : null;
 113
 114                 parent::__construct( $params );
 115         }
 116
 117         /**
 118          * @return string
 119          */
 120         public function getType() {
 121                 return 'mysql';
 122         }
 123
 124         protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix ) {
 125                 # Close/unset connection handle
 126                 $this->close();
 127
 128                 $this->server = $server;
 129                 $this->user = $user;
 130                 $this->password = $password;
 131
 132                 $this->installErrorHandler();
 133                 try {
 134                         $this->conn = $this->mysqlConnect( $this->server, $dbName );
 135                 } catch ( Exception $ex ) {
 136                         $this->restoreErrorHandler();
 137                         throw $ex;
 138                 }
 139                 $error = $this->restoreErrorHandler();
 140
 141                 # Always log connection errors
 142                 if ( !$this->conn ) {
 143                         $error = $error ?: $this->lastError();
 144                         $this->connLogger->error(
 145                                 "Error connecting to {db_server}: {error}",
 146                                 $this->getLogContext( [
 147                                         'method' => __METHOD__,
 148                                         'error' => $error,
 149                                 ] )
 150                         );
 151                         $this->connLogger->debug( "DB connection error\n" .
 152                                 "Server: $server, User: $user, Password: " .
 153                                 substr( $password, 0, 3 ) . "..., error: " . $error . "\n" );
 154
 155                         throw new DBConnectionError( $this, $error );
 156                 }
 157
 158                 if ( strlen( $dbName ) ) {
 159                         $this->selectDomain( new DatabaseDomain( $dbName, null, $tablePrefix ) );
 160                 } else {
 161                         $this->currentDomain = new DatabaseDomain( null, null, $tablePrefix );
 162                 }
 163
 164                 // Tell the server what we're communicating with
 165                 if ( !$this->connectInitCharset() ) {
 166                         $error = $this->lastError();
 167                         $this->queryLogger->error(
 168                                 "Error setting character set: {error}",
 169                                 $this->getLogContext( [
 170                                         'method' => __METHOD__,
 171                                         'error' => $this->lastError(),
 172                                 ] )
 173                         );
 174                         throw new DBConnectionError( $this, "Error setting character set: $error" );
 175                 }
 176
 177                 // Abstract over any insane MySQL defaults
 178                 $set = [ 'group_concat_max_len = 262144' ];
 179                 // Set SQL mode, default is turning them all off, can be overridden or skipped with null
 180                 if ( is_string( $this->sqlMode ) ) {
 181                         $set[] = 'sql_mode = ' . $this->addQuotes( $this->sqlMode );
 182                 }
 183                 // Set any custom settings defined by site config
 184                 // (e.g. https://dev.mysql.com/doc/refman/4.1/en/innodb-parameters.html)
 185                 foreach ( $this->sessionVars as $var => $val ) {
 186                         // Escape strings but not numbers to avoid MySQL complaining
 187                         if ( !is_int( $val ) && !is_float( $val ) ) {
 188                                 $val = $this->addQuotes( $val );
 189                         }
 190                         $set[] = $this->addIdentifierQuotes( $var ) . ' = ' . $val;
 191                 }
 192
 193                 if ( $set ) {
 194                         // Use doQuery() to avoid opening implicit transactions (DBO_TRX)
 195                         $success = $this->doQuery( 'SET ' . implode( ', ', $set ) );
 196                         if ( !$success ) {
 197                                 $error = $this->lastError();
 198                                 $this->queryLogger->error(
 199                                         'Error setting MySQL variables on server {db_server}: {error}',
 200                                         $this->getLogContext( [
 201                                                 'method' => __METHOD__,
 202                                                 'error' => $error,
 203                                         ] )
 204                                 );
 205                                 throw new DBConnectionError( $this, "Error setting MySQL variables: $error" );
 206                         }
 207                 }
 208
 209                 $this->opened = true;
 210
 211                 return true;
 212         }
 213
 214         /**
 215          * Set the character set information right after connection
 216          * @return bool
 217          */
 218         protected function connectInitCharset() {
 219                 if ( $this->utf8Mode ) {
 220                         // Tell the server we're communicating with it in UTF-8.
 221                         // This may engage various charset conversions.
 222                         return $this->mysqlSetCharset( 'utf8' );
 223                 } else {
 224                         return $this->mysqlSetCharset( 'binary' );
 225                 }
 226         }
 227
 228         protected function doSelectDomain( DatabaseDomain $domain ) {
 229                 if ( $domain->getSchema() !== null ) {
 230                         throw new DBExpectedError( $this, __CLASS__ . ": domain schemas are not supported." );
 231                 }
 232
 233                 $database = $domain->getDatabase();
 234                 // A null database means "don't care" so leave it as is and update the table prefix
 235                 if ( $database === null ) {
 236                         $this->currentDomain = new DatabaseDomain(
 237                                 $this->currentDomain->getDatabase(),
 238                                 null,
 239                                 $domain->getTablePrefix()
 240                         );
 241
 242                         return true;
 243                 }
 244
 245                 if ( $database !== $this->getDBname() ) {
 246                         $sql = 'USE ' . $this->addIdentifierQuotes( $database );
 247                         $ret = $this->doQuery( $sql );
 248                         if ( $ret === false ) {
 249                                 $error = $this->lastError();
 250                                 $errno = $this->lastErrno();
 251                                 $this->reportQueryError( $error, $errno, $sql, __METHOD__ );
 252                         }
 253                 }
 254
 255                 // Update that domain fields on success (no exception thrown)
 256                 $this->currentDomain = $domain;
 257
 258                 return true;
 259         }
 260
 261         /**
 262          * Open a connection to a MySQL server
 263          *
 264          * @param string $realServer
 265          * @param string|null $dbName
 266          * @return mixed Raw connection
 267          * @throws DBConnectionError
 268          */
 269         abstract protected function mysqlConnect( $realServer, $dbName );
 270
 271         /**
 272          * Set the character set of the MySQL link
 273          *
 274          * @param string $charset
 275          * @return bool
 276          */
 277         abstract protected function mysqlSetCharset( $charset );
 278
 279         /**
 280          * @param ResultWrapper|resource $res
 281          * @throws DBUnexpectedError
 282          */
 283         public function freeResult( $res ) {
 284                 if ( $res instanceof ResultWrapper ) {
 285                         $res = $res->result;
 286                 }
 287                 Wikimedia\suppressWarnings();
 288                 $ok = $this->mysqlFreeResult( $res );
 289                 Wikimedia\restoreWarnings();
 290                 if ( !$ok ) {
 291                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 292                 }
 293         }
 294
 295         /**
 296          * Free result memory
 297          *
 298          * @param resource $res Raw result
 299          * @return bool
 300          */
 301         abstract protected function mysqlFreeResult( $res );
 302
 303         /**
 304          * @param ResultWrapper|resource $res
 305          * @return stdClass|bool
 306          * @throws DBUnexpectedError
 307          */
 308         public function fetchObject( $res ) {
 309                 if ( $res instanceof ResultWrapper ) {
 310                         $res = $res->result;
 311                 }
 312                 Wikimedia\suppressWarnings();
 313                 $row = $this->mysqlFetchObject( $res );
 314                 Wikimedia\restoreWarnings();
 315
 316                 $errno = $this->lastErrno();
 317                 // Unfortunately, mysql_fetch_object does not reset the last errno.
 318                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 319                 // these are the only errors mysql_fetch_object can cause.
 320                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 321                 if ( $errno == 2000 || $errno == 2013 ) {
 322                         throw new DBUnexpectedError(
 323                                 $this,
 324                                 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() )
 325                         );
 326                 }
 327
 328                 return $row;
 329         }
 330
 331         /**
 332          * Fetch a result row as an object
 333          *
 334          * @param resource $res Raw result
 335          * @return stdClass
 336          */
 337         abstract protected function mysqlFetchObject( $res );
 338
 339         /**
 340          * @param IResultWrapper|resource $res
 341          * @return array|bool
 342          * @throws DBUnexpectedError
 343          */
 344         public function fetchRow( $res ) {
 345                 if ( $res instanceof ResultWrapper ) {
 346                         $res = $res->result;
 347                 }
 348                 Wikimedia\suppressWarnings();
 349                 $row = $this->mysqlFetchArray( $res );
 350                 Wikimedia\restoreWarnings();
 351
 352                 $errno = $this->lastErrno();
 353                 // Unfortunately, mysql_fetch_array does not reset the last errno.
 354                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 355                 // these are the only errors mysql_fetch_array can cause.
 356                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 357                 if ( $errno == 2000 || $errno == 2013 ) {
 358                         throw new DBUnexpectedError(
 359                                 $this,
 360                                 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() )
 361                         );
 362                 }
 363
 364                 return $row;
 365         }
 366
 367         /**
 368          * Fetch a result row as an associative and numeric array
 369          *
 370          * @param resource $res Raw result
 371          * @return array
 372          */
 373         abstract protected function mysqlFetchArray( $res );
 374
 375         /**
 376          * @throws DBUnexpectedError
 377          * @param ResultWrapper|resource $res
 378          * @return int
 379          */
 380         function numRows( $res ) {
 381                 if ( $res instanceof ResultWrapper ) {
 382                         $res = $res->result;
 383                 }
 384                 Wikimedia\suppressWarnings();
 385                 $n = !is_bool( $res ) ? $this->mysqlNumRows( $res ) : 0;
 386                 Wikimedia\restoreWarnings();
 387
 388                 // Unfortunately, mysql_num_rows does not reset the last errno.
 389                 // We are not checking for any errors here, since
 390                 // there are no errors mysql_num_rows can cause.
 391                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 392                 // See https://phabricator.wikimedia.org/T44430
 393                 return $n;
 394         }
 395
 396         /**
 397          * Get number of rows in result
 398          *
 399          * @param resource $res Raw result
 400          * @return int
 401          */
 402         abstract protected function mysqlNumRows( $res );
 403
 404         /**
 405          * @param ResultWrapper|resource $res
 406          * @return int
 407          */
 408         public function numFields( $res ) {
 409                 if ( $res instanceof ResultWrapper ) {
 410                         $res = $res->result;
 411                 }
 412
 413                 return $this->mysqlNumFields( $res );
 414         }
 415
 416         /**
 417          * Get number of fields in result
 418          *
 419          * @param resource $res Raw result
 420          * @return int
 421          */
 422         abstract protected function mysqlNumFields( $res );
 423
 424         /**
 425          * @param ResultWrapper|resource $res
 426          * @param int $n
 427          * @return string
 428          */
 429         public function fieldName( $res, $n ) {
 430                 if ( $res instanceof ResultWrapper ) {
 431                         $res = $res->result;
 432                 }
 433
 434                 return $this->mysqlFieldName( $res, $n );
 435         }
 436
 437         /**
 438          * Get the name of the specified field in a result
 439          *
 440          * @param ResultWrapper|resource $res
 441          * @param int $n
 442          * @return string
 443          */
 444         abstract protected function mysqlFieldName( $res, $n );
 445
 446         /**
 447          * mysql_field_type() wrapper
 448          * @param ResultWrapper|resource $res
 449          * @param int $n
 450          * @return string
 451          */
 452         public function fieldType( $res, $n ) {
 453                 if ( $res instanceof ResultWrapper ) {
 454                         $res = $res->result;
 455                 }
 456
 457                 return $this->mysqlFieldType( $res, $n );
 458         }
 459
 460         /**
 461          * Get the type of the specified field in a result
 462          *
 463          * @param ResultWrapper|resource $res
 464          * @param int $n
 465          * @return string
 466          */
 467         abstract protected function mysqlFieldType( $res, $n );
 468
 469         /**
 470          * @param ResultWrapper|resource $res
 471          * @param int $row
 472          * @return bool
 473          */
 474         public function dataSeek( $res, $row ) {
 475                 if ( $res instanceof ResultWrapper ) {
 476                         $res = $res->result;
 477                 }
 478
 479                 return $this->mysqlDataSeek( $res, $row );
 480         }
 481
 482         /**
 483          * Move internal result pointer
 484          *
 485          * @param ResultWrapper|resource $res
 486          * @param int $row
 487          * @return bool
 488          */
 489         abstract protected function mysqlDataSeek( $res, $row );
 490
 491         /**
 492          * @return string
 493          */
 494         public function lastError() {
 495                 if ( $this->conn ) {
 496                         # Even if it's non-zero, it can still be invalid
 497                         Wikimedia\suppressWarnings();
 498                         $error = $this->mysqlError( $this->conn );
 499                         if ( !$error ) {
 500                                 $error = $this->mysqlError();
 501                         }
 502                         Wikimedia\restoreWarnings();
 503                 } else {
 504                         $error = $this->mysqlError();
 505                 }
 506                 if ( $error ) {
 507                         $error .= ' (' . $this->server . ')';
 508                 }
 509
 510                 return $error;
 511         }
 512
 513         /**
 514          * Returns the text of the error message from previous MySQL operation
 515          *
 516          * @param resource|null $conn Raw connection
 517          * @return string
 518          */
 519         abstract protected function mysqlError( $conn = null );
 520
 521         protected function wasQueryTimeout( $error, $errno ) {
 522                 // https://dev.mysql.com/doc/refman/8.0/en/client-error-reference.html
 523                 // https://phabricator.wikimedia.org/T170638
 524                 return in_array( $errno, [ 2062, 3024 ] );
 525         }
 526
 527         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
 528                 $this->nativeReplace( $table, $rows, $fname );
 529         }
 530
 531         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
 532                 $row = $this->getReplicationSafetyInfo();
 533                 // For row-based-replication, the resulting changes will be relayed, not the query
 534                 if ( $row->binlog_format === 'ROW' ) {
 535                         return true;
 536                 }
 537                 // LIMIT requires ORDER BY on a unique key or it is non-deterministic
 538                 if ( isset( $selectOptions['LIMIT'] ) ) {
 539                         return false;
 540                 }
 541                 // In MySQL, an INSERT SELECT is only replication safe with row-based
 542                 // replication or if innodb_autoinc_lock_mode is 0. When those
 543                 // conditions aren't met, use non-native mode.
 544                 // While we could try to determine if the insert is safe anyway by
 545                 // checking if the target table has an auto-increment column that
 546                 // isn't set in $varMap, that seems unlikely to be worth the extra
 547                 // complexity.
 548                 return (
 549                         in_array( 'NO_AUTO_COLUMNS', $insertOptions ) ||
 550                         (int)$row->innodb_autoinc_lock_mode === 0
 551                 );
 552         }
 553
 554         /**
 555          * @return stdClass Process cached row
 556          */
 557         protected function getReplicationSafetyInfo() {
 558                 if ( $this->replicationInfoRow === null ) {
 559                         $this->replicationInfoRow = $this->selectRow(
 560                                 false,
 561                                 [
 562                                         'innodb_autoinc_lock_mode' => '@@innodb_autoinc_lock_mode',
 563                                         'binlog_format' => '@@binlog_format',
 564                                 ],
 565                                 [],
 566                                 __METHOD__
 567                         );
 568                 }
 569
 570                 return $this->replicationInfoRow;
 571         }
 572
 573         /**
 574          * Estimate rows in dataset
 575          * Returns estimated count, based on EXPLAIN output
 576          * Takes same arguments as Database::select()
 577          *
 578          * @param string|array $table
 579          * @param string|array $var
 580          * @param string|array $conds
 581          * @param string $fname
 582          * @param string|array $options
 583          * @param array $join_conds
 584          * @return bool|int
 585          */
 586         public function estimateRowCount( $table, $var = '*', $conds = '',
 587                 $fname = __METHOD__, $options = [], $join_conds = []
 588         ) {
 589                 $conds = $this->normalizeConditions( $conds, $fname );
 590                 $column = $this->extractSingleFieldFromList( $var );
 591                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 592                         $conds[] = "$column IS NOT NULL";
 593                 }
 594
 595                 $options['EXPLAIN'] = true;
 596                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 597                 if ( $res === false ) {
 598                         return false;
 599                 }
 600                 if ( !$this->numRows( $res ) ) {
 601                         return 0;
 602                 }
 603
 604                 $rows = 1;
 605                 foreach ( $res as $plan ) {
 606                         $rows *= $plan->rows > 0 ? $plan->rows : 1; // avoid resetting to zero
 607                 }
 608
 609                 return (int)$rows;
 610         }
 611
 612         public function tableExists( $table, $fname = __METHOD__ ) {
 613                 // Split database and table into proper variables as Database::tableName() returns
 614                 // shared tables prefixed with their database, which do not work in SHOW TABLES statements
 615                 list( $database, , $prefix, $table ) = $this->qualifiedTableComponents( $table );
 616                 $tableName = "{$prefix}{$table}";
 617
 618                 if ( isset( $this->sessionTempTables[$tableName] ) ) {
 619                         return true; // already known to exist and won't show in SHOW TABLES anyway
 620                 }
 621
 622                 // We can't use buildLike() here, because it specifies an escape character
 623                 // other than the backslash, which is the only one supported by SHOW TABLES
 624                 $encLike = $this->escapeLikeInternal( $tableName, '\\' );
 625
 626                 // If the database has been specified (such as for shared tables), use "FROM"
 627                 if ( $database !== '' ) {
 628                         $encDatabase = $this->addIdentifierQuotes( $database );
 629                         $query = "SHOW TABLES FROM $encDatabase LIKE '$encLike'";
 630                 } else {
 631                         $query = "SHOW TABLES LIKE '$encLike'";
 632                 }
 633
 634                 return $this->query( $query, $fname )->numRows() > 0;
 635         }
 636
 637         /**
 638          * @param string $table
 639          * @param string $field
 640          * @return bool|MySQLField
 641          */
 642         public function fieldInfo( $table, $field ) {
 643                 $table = $this->tableName( $table );
 644                 $res = $this->query( "SELECT * FROM $table LIMIT 1", __METHOD__, true );
 645                 if ( !$res ) {
 646                         return false;
 647                 }
 648                 $n = $this->mysqlNumFields( $res->result );
 649                 for ( $i = 0; $i < $n; $i++ ) {
 650                         $meta = $this->mysqlFetchField( $res->result, $i );
 651                         if ( $field == $meta->name ) {
 652                                 return new MySQLField( $meta );
 653                         }
 654                 }
 655
 656                 return false;
 657         }
 658
 659         /**
 660          * Get column information from a result
 661          *
 662          * @param resource $res Raw result
 663          * @param int $n
 664          * @return stdClass
 665          */
 666         abstract protected function mysqlFetchField( $res, $n );
 667
 668         /**
 669          * Get information about an index into an object
 670          * Returns false if the index does not exist
 671          *
 672          * @param string $table
 673          * @param string $index
 674          * @param string $fname
 675          * @return bool|array|null False or null on failure
 676          */
 677         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 678                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 679                 # SHOW INDEX should work for 3.x and up:
 680                 # https://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 681                 $table = $this->tableName( $table );
 682                 $index = $this->indexName( $index );
 683
 684                 $sql = 'SHOW INDEX FROM ' . $table;
 685                 $res = $this->query( $sql, $fname );
 686
 687                 if ( !$res ) {
 688                         return null;
 689                 }
 690
 691                 $result = [];
 692
 693                 foreach ( $res as $row ) {
 694                         if ( $row->Key_name == $index ) {
 695                                 $result[] = $row;
 696                         }
 697                 }
 698
 699                 return $result ?: false;
 700         }
 701
 702         /**
 703          * @param string $s
 704          * @return string
 705          */
 706         public function strencode( $s ) {
 707                 return $this->mysqlRealEscapeString( $s );
 708         }
 709
 710         /**
 711          * @param string $s
 712          * @return mixed
 713          */
 714         abstract protected function mysqlRealEscapeString( $s );
 715
 716         public function addQuotes( $s ) {
 717                 if ( is_bool( $s ) ) {
 718                         // Parent would transform to int, which does not play nice with MySQL type juggling.
 719                         // When searching for an int in a string column, the strings are cast to int, which
 720                         // means false would match any string not starting with a number.
 721                         $s = (string)(int)$s;
 722                 }
 723                 return parent::addQuotes( $s );
 724         }
 725
 726         /**
 727          * MySQL uses `backticks` for identifier quoting instead of the sql standard "double quotes".
 728          *
 729          * @param string $s
 730          * @return string
 731          */
 732         public function addIdentifierQuotes( $s ) {
 733                 // Characters in the range \u0001-\uFFFF are valid in a quoted identifier
 734                 // Remove NUL bytes and escape backticks by doubling
 735                 return '`' . str_replace( [ "\0", '`' ], [ '', '``' ], $s ) . '`';
 736         }
 737
 738         /**
 739          * @param string $name
 740          * @return bool
 741          */
 742         public function isQuotedIdentifier( $name ) {
 743                 return strlen( $name ) && $name[0] == '`' && substr( $name, -1, 1 ) == '`';
 744         }
 745
 746         public function getLag() {
 747                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 748                         return $this->getLagFromPtHeartbeat();
 749                 } else {
 750                         return $this->getLagFromSlaveStatus();
 751                 }
 752         }
 753
 754         /**
 755          * @return string
 756          */
 757         protected function getLagDetectionMethod() {
 758                 return $this->lagDetectionMethod;
 759         }
 760
 761         /**
 762          * @return bool|int
 763          */
 764         protected function getLagFromSlaveStatus() {
 765                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
 766                 $row = $res ? $res->fetchObject() : false;
 767                 // If the server is not replicating, there will be no row
 768                 if ( $row && strval( $row->Seconds_Behind_Master ) !== '' ) {
 769                         return intval( $row->Seconds_Behind_Master );
 770                 }
 771
 772                 return false;
 773         }
 774
 775         /**
 776          * @return bool|float
 777          */
 778         protected function getLagFromPtHeartbeat() {
 779                 $options = $this->lagDetectionOptions;
 780
 781                 $currentTrxInfo = $this->getRecordedTransactionLagStatus();
 782                 if ( $currentTrxInfo ) {
 783                         // There is an active transaction and the initial lag was already queried
 784                         $staleness = microtime( true ) - $currentTrxInfo['since'];
 785                         if ( $staleness > self::LAG_STALE_WARN_THRESHOLD ) {
 786                                 // Avoid returning higher and higher lag value due to snapshot age
 787                                 // given that the isolation level will typically be REPEATABLE-READ
 788                                 $this->queryLogger->warning(
 789                                         "Using cached lag value for {db_server} due to active transaction",
 790                                         $this->getLogContext( [
 791                                                 'method' => __METHOD__,
 792                                                 'age' => $staleness,
 793                                                 'trace' => ( new RuntimeException() )->getTraceAsString()
 794                                         ] )
 795                                 );
 796                         }
 797
 798                         return $currentTrxInfo['lag'];
 799                 }
 800
 801                 if ( isset( $options['conds'] ) ) {
 802                         // Best method for multi-DC setups: use logical channel names
 803                         $data = $this->getHeartbeatData( $options['conds'] );
 804                 } else {
 805                         // Standard method: use master server ID (works with stock pt-heartbeat)
 806                         $masterInfo = $this->getMasterServerInfo();
 807                         if ( !$masterInfo ) {
 808                                 $this->queryLogger->error(
 809                                         "Unable to query master of {db_server} for server ID",
 810                                         $this->getLogContext( [
 811                                                 'method' => __METHOD__
 812                                         ] )
 813                                 );
 814
 815                                 return false; // could not get master server ID
 816                         }
 817
 818                         $conds = [ 'server_id' => intval( $masterInfo['serverId'] ) ];
 819                         $data = $this->getHeartbeatData( $conds );
 820                 }
 821
 822                 list( $time, $nowUnix ) = $data;
 823                 if ( $time !== null ) {
 824                         // @time is in ISO format like "2015-09-25T16:48:10.000510"
 825                         $dateTime = new DateTime( $time, new DateTimeZone( 'UTC' ) );
 826                         $timeUnix = (int)$dateTime->format( 'U' ) + $dateTime->format( 'u' ) / 1e6;
 827
 828                         return max( $nowUnix - $timeUnix, 0.0 );
 829                 }
 830
 831                 $this->queryLogger->error(
 832                         "Unable to find pt-heartbeat row for {db_server}",
 833                         $this->getLogContext( [
 834                                 'method' => __METHOD__
 835                         ] )
 836                 );
 837
 838                 return false;
 839         }
 840
 841         protected function getMasterServerInfo() {
 842                 $cache = $this->srvCache;
 843                 $key = $cache->makeGlobalKey(
 844                         'mysql',
 845                         'master-info',
 846                         // Using one key for all cluster replica DBs is preferable
 847                         $this->getLBInfo( 'clusterMasterHost' ) ?: $this->getServer()
 848                 );
 849                 $fname = __METHOD__;
 850
 851                 return $cache->getWithSetCallback(
 852                         $key,
 853                         $cache::TTL_INDEFINITE,
 854                         function () use ( $cache, $key, $fname ) {
 855                                 // Get and leave a lock key in place for a short period
 856                                 if ( !$cache->lock( $key, 0, 10 ) ) {
 857                                         return false; // avoid master connection spike slams
 858                                 }
 859
 860                                 $conn = $this->getLazyMasterHandle();
 861                                 if ( !$conn ) {
 862                                         return false; // something is misconfigured
 863                                 }
 864
 865                                 // Connect to and query the master; catch errors to avoid outages
 866                                 try {
 867                                         $res = $conn->query( 'SELECT @@server_id AS id', $fname );
 868                                         $row = $res ? $res->fetchObject() : false;
 869                                         $id = $row ? (int)$row->id : 0;
 870                                 } catch ( DBError $e ) {
 871                                         $id = 0;
 872                                 }
 873
 874                                 // Cache the ID if it was retrieved
 875                                 return $id ? [ 'serverId' => $id, 'asOf' => time() ] : false;
 876                         }
 877                 );
 878         }
 879
 880         /**
 881          * @param array $conds WHERE clause conditions to find a row
 882          * @return array (heartbeat `ts` column value or null, UNIX timestamp) for the newest beat
 883          * @see https://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html
 884          */
 885         protected function getHeartbeatData( array $conds ) {
 886                 // Query time and trip time are not counted
 887                 $nowUnix = microtime( true );
 888                 // Do not bother starting implicit transactions here
 889                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
 890                 try {
 891                         $whereSQL = $this->makeList( $conds, self::LIST_AND );
 892                         // Use ORDER BY for channel based queries since that field might not be UNIQUE.
 893                         // Note: this would use "TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6))" but the
 894                         // percision field is not supported in MySQL <= 5.5.
 895                         $res = $this->query(
 896                                 "SELECT ts FROM heartbeat.heartbeat WHERE $whereSQL ORDER BY ts DESC LIMIT 1",
 897                                 __METHOD__
 898                         );
 899                         $row = $res ? $res->fetchObject() : false;
 900                 } finally {
 901                         $this->restoreFlags();
 902                 }
 903
 904                 return [ $row ? $row->ts : null, $nowUnix ];
 905         }
 906
 907         protected function getApproximateLagStatus() {
 908                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 909                         // Disable caching since this is fast enough and we don't wan't
 910                         // to be *too* pessimistic by having both the cache TTL and the
 911                         // pt-heartbeat interval count as lag in getSessionLagStatus()
 912                         return parent::getApproximateLagStatus();
 913                 }
 914
 915                 $key = $this->srvCache->makeGlobalKey( 'mysql-lag', $this->getServer() );
 916                 $approxLag = $this->srvCache->get( $key );
 917                 if ( !$approxLag ) {
 918                         $approxLag = parent::getApproximateLagStatus();
 919                         $this->srvCache->set( $key, $approxLag, 1 );
 920                 }
 921
 922                 return $approxLag;
 923         }
 924
 925         public function masterPosWait( DBMasterPos $pos, $timeout ) {
 926                 if ( !( $pos instanceof MySQLMasterPos ) ) {
 927                         throw new InvalidArgumentException( "Position not an instance of MySQLMasterPos" );
 928                 }
 929
 930                 if ( $this->getLBInfo( 'is static' ) === true ) {
 931                         return 0; // this is a copy of a read-only dataset with no master DB
 932                 } elseif ( $this->lastKnownReplicaPos && $this->lastKnownReplicaPos->hasReached( $pos ) ) {
 933                         return 0; // already reached this point for sure
 934                 }
 935
 936                 // Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
 937                 if ( $pos->getGTIDs() ) {
 938                         // Ignore GTIDs from domains exclusive to the master DB (presumably inactive)
 939                         $rpos = $this->getReplicaPos();
 940                         $gtidsWait = $rpos ? MySQLMasterPos::getCommonDomainGTIDs( $pos, $rpos ) : [];
 941                         if ( !$gtidsWait ) {
 942                                 $this->queryLogger->error(
 943                                         "No GTIDs with the same domain between master ($pos) and replica ($rpos)",
 944                                         $this->getLogContext( [
 945                                                 'method' => __METHOD__,
 946                                         ] )
 947                                 );
 948
 949                                 return -1; // $pos is from the wrong cluster?
 950                         }
 951                         // Wait on the GTID set (MariaDB only)
 952                         $gtidArg = $this->addQuotes( implode( ',', $gtidsWait ) );
 953                         if ( strpos( $gtidArg, ':' ) !== false ) {
 954                                 // MySQL GTIDs, e.g "source_id:transaction_id"
 955                                 $res = $this->doQuery( "SELECT WAIT_FOR_EXECUTED_GTID_SET($gtidArg, $timeout)" );
 956                         } else {
 957                                 // MariaDB GTIDs, e.g."domain:server:sequence"
 958                                 $res = $this->doQuery( "SELECT MASTER_GTID_WAIT($gtidArg, $timeout)" );
 959                         }
 960                 } else {
 961                         // Wait on the binlog coordinates
 962                         $encFile = $this->addQuotes( $pos->getLogFile() );
 963                         $encPos = intval( $pos->getLogPosition()[$pos::CORD_EVENT] );
 964                         $res = $this->doQuery( "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)" );
 965                 }
 966
 967                 $row = $res ? $this->fetchRow( $res ) : false;
 968                 if ( !$row ) {
 969                         throw new DBExpectedError( $this, "Replication wait failed: {$this->lastError()}" );
 970                 }
 971
 972                 // Result can be NULL (error), -1 (timeout), or 0+ per the MySQL manual
 973                 $status = ( $row[0] !== null ) ? intval( $row[0] ) : null;
 974                 if ( $status === null ) {
 975                         if ( !$pos->getGTIDs() ) {
 976                                 // T126436: jobs programmed to wait on master positions might be referencing
 977                                 // binlogs with an old master hostname; this makes MASTER_POS_WAIT() return null.
 978                                 // Try to detect this case and treat the replica DB as having reached the given
 979                                 // position (any master switchover already requires that the new master be caught
 980                                 // up before the switch).
 981                                 $replicationPos = $this->getReplicaPos();
 982                                 if ( $replicationPos && !$replicationPos->channelsMatch( $pos ) ) {
 983                                         $this->lastKnownReplicaPos = $replicationPos;
 984                                         $status = 0;
 985                                 }
 986                         }
 987                 } elseif ( $status >= 0 ) {
 988                         // Remember that this position was reached to save queries next time
 989                         $this->lastKnownReplicaPos = $pos;
 990                 }
 991
 992                 return $status;
 993         }
 994
 995         /**
 996          * Get the position of the master from SHOW SLAVE STATUS
 997          *
 998          * @return MySQLMasterPos|bool
 999          */
1000         public function getReplicaPos() {
1001                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
1002
1003                 if ( $this->useGTIDs() ) {
1004                         // Try to use GTIDs, fallbacking to binlog positions if not possible
1005                         $data = $this->getServerGTIDs( __METHOD__ );
1006                         // Use gtid_slave_pos for MariaDB and gtid_executed for MySQL
1007                         foreach ( [ 'gtid_slave_pos', 'gtid_executed' ] as $name ) {
1008                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
1009                                         return new MySQLMasterPos( $data[$name], $now );
1010                                 }
1011                         }
1012                 }
1013
1014                 $data = $this->getServerRoleStatus( 'SLAVE', __METHOD__ );
1015                 if ( $data && strlen( $data['Relay_Master_Log_File'] ) ) {
1016                         return new MySQLMasterPos(
1017                                 "{$data['Relay_Master_Log_File']}/{$data['Exec_Master_Log_Pos']}",
1018                                 $now
1019                         );
1020                 }
1021
1022                 return false;
1023         }
1024
1025         /**
1026          * Get the position of the master from SHOW MASTER STATUS
1027          *
1028          * @return MySQLMasterPos|bool
1029          */
1030         public function getMasterPos() {
1031                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
1032
1033                 $pos = false;
1034                 if ( $this->useGTIDs() ) {
1035                         // Try to use GTIDs, fallbacking to binlog positions if not possible
1036                         $data = $this->getServerGTIDs( __METHOD__ );
1037                         // Use gtid_binlog_pos for MariaDB and gtid_executed for MySQL
1038                         foreach ( [ 'gtid_binlog_pos', 'gtid_executed' ] as $name ) {
1039                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
1040                                         $pos = new MySQLMasterPos( $data[$name], $now );
1041                                         break;
1042                                 }
1043                         }
1044                         // Filter domains that are inactive or not relevant to the session
1045                         if ( $pos ) {
1046                                 $pos->setActiveOriginServerId( $this->getServerId() );
1047                                 $pos->setActiveOriginServerUUID( $this->getServerUUID() );
1048                                 if ( isset( $data['gtid_domain_id'] ) ) {
1049                                         $pos->setActiveDomain( $data['gtid_domain_id'] );
1050                                 }
1051                         }
1052                 }
1053
1054                 if ( !$pos ) {
1055                         $data = $this->getServerRoleStatus( 'MASTER', __METHOD__ );
1056                         if ( $data && strlen( $data['File'] ) ) {
1057                                 $pos = new MySQLMasterPos( "{$data['File']}/{$data['Position']}", $now );
1058                         }
1059                 }
1060
1061                 return $pos;
1062         }
1063
1064         /**
1065          * @return int
1066          * @throws DBQueryError If the variable doesn't exist for some reason
1067          */
1068         protected function getServerId() {
1069                 $fname = __METHOD__;
1070                 return $this->srvCache->getWithSetCallback(
1071                         $this->srvCache->makeGlobalKey( 'mysql-server-id', $this->getServer() ),
1072                         self::SERVER_ID_CACHE_TTL,
1073                         function () use ( $fname ) {
1074                                 $res = $this->query( "SELECT @@server_id AS id", $fname );
1075                                 return intval( $this->fetchObject( $res )->id );
1076                         }
1077                 );
1078         }
1079
1080         /**
1081          * @return string|null
1082          */
1083         protected function getServerUUID() {
1084                 return $this->srvCache->getWithSetCallback(
1085                         $this->srvCache->makeGlobalKey( 'mysql-server-uuid', $this->getServer() ),
1086                         self::SERVER_ID_CACHE_TTL,
1087                         function () {
1088                                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'server_uuid'" );
1089                                 $row = $this->fetchObject( $res );
1090
1091                                 return $row ? $row->Value : null;
1092                         }
1093                 );
1094         }
1095
1096         /**
1097          * @param string $fname
1098          * @return string[]
1099          */
1100         protected function getServerGTIDs( $fname = __METHOD__ ) {
1101                 $map = [];
1102                 // Get global-only variables like gtid_executed
1103                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'gtid_%'", $fname );
1104                 foreach ( $res as $row ) {
1105                         $map[$row->Variable_name] = $row->Value;
1106                 }
1107                 // Get session-specific (e.g. gtid_domain_id since that is were writes will log)
1108                 $res = $this->query( "SHOW SESSION VARIABLES LIKE 'gtid_%'", $fname );
1109                 foreach ( $res as $row ) {
1110                         $map[$row->Variable_name] = $row->Value;
1111                 }
1112
1113                 return $map;
1114         }
1115
1116         /**
1117          * @param string $role One of "MASTER"/"SLAVE"
1118          * @param string $fname
1119          * @return string[] Latest available server status row
1120          */
1121         protected function getServerRoleStatus( $role, $fname = __METHOD__ ) {
1122                 return $this->query( "SHOW $role STATUS", $fname )->fetchRow() ?: [];
1123         }
1124
1125         public function serverIsReadOnly() {
1126                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'read_only'", __METHOD__ );
1127                 $row = $this->fetchObject( $res );
1128
1129                 return $row ? ( strtolower( $row->Value ) === 'on' ) : false;
1130         }
1131
1132         /**
1133          * @param string $index
1134          * @return string
1135          */
1136         function useIndexClause( $index ) {
1137                 return "FORCE INDEX (" . $this->indexName( $index ) . ")";
1138         }
1139
1140         /**
1141          * @param string $index
1142          * @return string
1143          */
1144         function ignoreIndexClause( $index ) {
1145                 return "IGNORE INDEX (" . $this->indexName( $index ) . ")";
1146         }
1147
1148         /**
1149          * @return string
1150          */
1151         function lowPriorityOption() {
1152                 return 'LOW_PRIORITY';
1153         }
1154
1155         /**
1156          * @return string
1157          */
1158         public function getSoftwareLink() {
1159                 // MariaDB includes its name in its version string; this is how MariaDB's version of
1160                 // the mysql command-line client identifies MariaDB servers (see mariadb_connection()
1161                 // in libmysql/libmysql.c).
1162                 $version = $this->getServerVersion();
1163                 if ( strpos( $version, 'MariaDB' ) !== false || strpos( $version, '-maria-' ) !== false ) {
1164                         return '[{{int:version-db-mariadb-url}} MariaDB]';
1165                 }
1166
1167                 // Percona Server's version suffix is not very distinctive, and @@version_comment
1168                 // doesn't give the necessary info for source builds, so assume the server is MySQL.
1169                 // (Even Percona's version of mysql doesn't try to make the distinction.)
1170                 return '[{{int:version-db-mysql-url}} MySQL]';
1171         }
1172
1173         /**
1174          * @return string
1175          */
1176         public function getServerVersion() {
1177                 // Not using mysql_get_server_info() or similar for consistency: in the handshake,
1178                 // MariaDB 10 adds the prefix "5.5.5-", and only some newer client libraries strip
1179                 // it off (see RPL_VERSION_HACK in include/mysql_com.h).
1180                 if ( $this->serverVersion === null ) {
1181                         $this->serverVersion = $this->selectField( '', 'VERSION()', '', __METHOD__ );
1182                 }
1183                 return $this->serverVersion;
1184         }
1185
1186         /**
1187          * @param array $options
1188          */
1189         public function setSessionOptions( array $options ) {
1190                 if ( isset( $options['connTimeout'] ) ) {
1191                         $timeout = (int)$options['connTimeout'];
1192                         $this->query( "SET net_read_timeout=$timeout" );
1193                         $this->query( "SET net_write_timeout=$timeout" );
1194                 }
1195         }
1196
1197         /**
1198          * @param string &$sql
1199          * @param string &$newLine
1200          * @return bool
1201          */
1202         public function streamStatementEnd( &$sql, &$newLine ) {
1203                 if ( strtoupper( substr( $newLine, 0, 9 ) ) == 'DELIMITER' ) {
1204                         preg_match( '/^DELIMITER\s+(\S+)/', $newLine, $m );
1205                         $this->delimiter = $m[1];
1206                         $newLine = '';
1207                 }
1208
1209                 return parent::streamStatementEnd( $sql, $newLine );
1210         }
1211
1212         /**
1213          * Check to see if a named lock is available. This is non-blocking.
1214          *
1215          * @param string $lockName Name of lock to poll
1216          * @param string $method Name of method calling us
1217          * @return bool
1218          * @since 1.20
1219          */
1220         public function lockIsFree( $lockName, $method ) {
1221                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1222                         return false; // already held
1223                 }
1224
1225                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1226                 $result = $this->query( "SELECT IS_FREE_LOCK($encName) AS lockstatus", $method );
1227                 $row = $this->fetchObject( $result );
1228
1229                 return ( $row->lockstatus == 1 );
1230         }
1231
1232         /**
1233          * @param string $lockName
1234          * @param string $method
1235          * @param int $timeout
1236          * @return bool
1237          */
1238         public function lock( $lockName, $method, $timeout = 5 ) {
1239                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1240                 $result = $this->query( "SELECT GET_LOCK($encName, $timeout) AS lockstatus", $method );
1241                 $row = $this->fetchObject( $result );
1242
1243                 if ( $row->lockstatus == 1 ) {
1244                         parent::lock( $lockName, $method, $timeout ); // record
1245                         return true;
1246                 }
1247
1248                 $this->queryLogger->info( __METHOD__ . " failed to acquire lock '{lockname}'",
1249                         [ 'lockname' => $lockName ] );
1250
1251                 return false;
1252         }
1253
1254         /**
1255          * FROM MYSQL DOCS:
1256          * https://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock
1257          * @param string $lockName
1258          * @param string $method
1259          * @return bool
1260          */
1261         public function unlock( $lockName, $method ) {
1262                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1263                 $result = $this->query( "SELECT RELEASE_LOCK($encName) as lockstatus", $method );
1264                 $row = $this->fetchObject( $result );
1265
1266                 if ( $row->lockstatus == 1 ) {
1267                         parent::unlock( $lockName, $method ); // record
1268                         return true;
1269                 }
1270
1271                 $this->queryLogger->warning( __METHOD__ . " failed to release lock '$lockName'\n" );
1272
1273                 return false;
1274         }
1275
1276         private function makeLockName( $lockName ) {
1277                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1278                 // Newer version enforce a 64 char length limit.
1279                 return ( strlen( $lockName ) > 64 ) ? sha1( $lockName ) : $lockName;
1280         }
1281
1282         public function namedLocksEnqueue() {
1283                 return true;
1284         }
1285
1286         public function tableLocksHaveTransactionScope() {
1287                 return false; // tied to TCP connection
1288         }
1289
1290         protected function doLockTables( array $read, array $write, $method ) {
1291                 $items = [];
1292                 foreach ( $write as $table ) {
1293                         $items[] = $this->tableName( $table ) . ' WRITE';
1294                 }
1295                 foreach ( $read as $table ) {
1296                         $items[] = $this->tableName( $table ) . ' READ';
1297                 }
1298
1299                 $sql = "LOCK TABLES " . implode( ',', $items );
1300                 $this->query( $sql, $method );
1301
1302                 return true;
1303         }
1304
1305         protected function doUnlockTables( $method ) {
1306                 $this->query( "UNLOCK TABLES", $method );
1307
1308                 return true;
1309         }
1310
1311         /**
1312          * @param bool $value
1313          */
1314         public function setBigSelects( $value = true ) {
1315                 if ( $value === 'default' ) {
1316                         if ( $this->defaultBigSelects === null ) {
1317                                 # Function hasn't been called before so it must already be set to the default
1318                                 return;
1319                         } else {
1320                                 $value = $this->defaultBigSelects;
1321                         }
1322                 } elseif ( $this->defaultBigSelects === null ) {
1323                         $this->defaultBigSelects =
1324                                 (bool)$this->selectField( false, '@@sql_big_selects', '', __METHOD__ );
1325                 }
1326                 $encValue = $value ? '1' : '0';
1327                 $this->query( "SET sql_big_selects=$encValue", __METHOD__ );
1328         }
1329
1330         /**
1331          * DELETE where the condition is a join. MySql uses multi-table deletes.
1332          * @param string $delTable
1333          * @param string $joinTable
1334          * @param string $delVar
1335          * @param string $joinVar
1336          * @param array|string $conds
1337          * @param bool|string $fname
1338          * @throws DBUnexpectedError
1339          */
1340         public function deleteJoin(
1341                 $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__
1342         ) {
1343                 if ( !$conds ) {
1344                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
1345                 }
1346
1347                 $delTable = $this->tableName( $delTable );
1348                 $joinTable = $this->tableName( $joinTable );
1349                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1350
1351                 if ( $conds != '*' ) {
1352                         $sql .= ' AND ' . $this->makeList( $conds, self::LIST_AND );
1353                 }
1354
1355                 $this->query( $sql, $fname );
1356         }
1357
1358         public function upsert(
1359                 $table, array $rows, $uniqueIndexes, array $set, $fname = __METHOD__
1360         ) {
1361                 if ( $rows === [] ) {
1362                         return true; // nothing to do
1363                 }
1364
1365                 if ( !is_array( reset( $rows ) ) ) {
1366                         $rows = [ $rows ];
1367                 }
1368
1369                 $table = $this->tableName( $table );
1370                 $columns = array_keys( $rows[0] );
1371
1372                 $sql = "INSERT INTO $table (" . implode( ',', $columns ) . ') VALUES ';
1373                 $rowTuples = [];
1374                 foreach ( $rows as $row ) {
1375                         $rowTuples[] = '(' . $this->makeList( $row ) . ')';
1376                 }
1377                 $sql .= implode( ',', $rowTuples );
1378                 $sql .= " ON DUPLICATE KEY UPDATE " . $this->makeList( $set, self::LIST_SET );
1379
1380                 $this->query( $sql, $fname );
1381
1382                 return true;
1383         }
1384
1385         /**
1386          * Determines how long the server has been up
1387          *
1388          * @return int
1389          */
1390         public function getServerUptime() {
1391                 $vars = $this->getMysqlStatus( 'Uptime' );
1392
1393                 return (int)$vars['Uptime'];
1394         }
1395
1396         /**
1397          * Determines if the last failure was due to a deadlock
1398          *
1399          * @return bool
1400          */
1401         public function wasDeadlock() {
1402                 return $this->lastErrno() == 1213;
1403         }
1404
1405         /**
1406          * Determines if the last failure was due to a lock timeout
1407          *
1408          * @return bool
1409          */
1410         public function wasLockTimeout() {
1411                 return $this->lastErrno() == 1205;
1412         }
1413
1414         /**
1415          * Determines if the last failure was due to the database being read-only.
1416          *
1417          * @return bool
1418          */
1419         public function wasReadOnlyError() {
1420                 return $this->lastErrno() == 1223 ||
1421                         ( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
1422         }
1423
1424         public function wasConnectionError( $errno ) {
1425                 return $errno == 2013 || $errno == 2006;
1426         }
1427
1428         protected function wasKnownStatementRollbackError() {
1429                 $errno = $this->lastErrno();
1430
1431                 if ( $errno === 1205 ) { // lock wait timeout
1432                         // Note that this is uncached to avoid stale values of SET is used
1433                         $row = $this->selectRow(
1434                                 false,
1435                                 [ 'innodb_rollback_on_timeout' => '@@innodb_rollback_on_timeout' ],
1436                                 [],
1437                                 __METHOD__
1438                         );
1439                         // https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
1440                         // https://dev.mysql.com/doc/refman/5.5/en/innodb-parameters.html
1441                         return $row->innodb_rollback_on_timeout ? false : true;
1442                 }
1443
1444                 // See https://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html
1445                 return in_array( $errno, [ 1022, 1062, 1216, 1217, 1137, 1146, 1051, 1054 ], true );
1446         }
1447
1448         /**
1449          * @param string $oldName
1450          * @param string $newName
1451          * @param bool $temporary
1452          * @param string $fname
1453          * @return bool
1454          */
1455         public function duplicateTableStructure(
1456                 $oldName, $newName, $temporary = false, $fname = __METHOD__
1457         ) {
1458                 $tmp = $temporary ? 'TEMPORARY ' : '';
1459                 $newName = $this->addIdentifierQuotes( $newName );
1460                 $oldName = $this->addIdentifierQuotes( $oldName );
1461                 $query = "CREATE $tmp TABLE $newName (LIKE $oldName)";
1462
1463                 return $this->query( $query, $fname, $this::QUERY_PSEUDO_PERMANENT );
1464         }
1465
1466         /**
1467          * List all tables on the database
1468          *
1469          * @param string|null $prefix Only show tables with this prefix, e.g. mw_
1470          * @param string $fname Calling function name
1471          * @return array
1472          */
1473         public function listTables( $prefix = null, $fname = __METHOD__ ) {
1474                 $result = $this->query( "SHOW TABLES", $fname );
1475
1476                 $endArray = [];
1477
1478                 foreach ( $result as $table ) {
1479                         $vars = get_object_vars( $table );
1480                         $table = array_pop( $vars );
1481
1482                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1483                                 $endArray[] = $table;
1484                         }
1485                 }
1486
1487                 return $endArray;
1488         }
1489
1490         /**
1491          * @param string $tableName
1492          * @param string $fName
1493          * @return bool|ResultWrapper
1494          */
1495         public function dropTable( $tableName, $fName = __METHOD__ ) {
1496                 if ( !$this->tableExists( $tableName, $fName ) ) {
1497                         return false;
1498                 }
1499
1500                 return $this->query( "DROP TABLE IF EXISTS " . $this->tableName( $tableName ), $fName );
1501         }
1502
1503         /**
1504          * Get status information from SHOW STATUS in an associative array
1505          *
1506          * @param string $which
1507          * @return array
1508          */
1509         private function getMysqlStatus( $which = "%" ) {
1510                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1511                 $status = [];
1512
1513                 foreach ( $res as $row ) {
1514                         $status[$row->Variable_name] = $row->Value;
1515                 }
1516
1517                 return $status;
1518         }
1519
1520         /**
1521          * Lists VIEWs in the database
1522          *
1523          * @param string|null $prefix Only show VIEWs with this prefix, eg.
1524          * unit_test_, or $wgDBprefix. Default: null, would return all views.
1525          * @param string $fname Name of calling function
1526          * @return array
1527          * @since 1.22
1528          */
1529         public function listViews( $prefix = null, $fname = __METHOD__ ) {
1530                 // The name of the column containing the name of the VIEW
1531                 $propertyName = 'Tables_in_' . $this->getDBname();
1532
1533                 // Query for the VIEWS
1534                 $res = $this->query( 'SHOW FULL TABLES WHERE TABLE_TYPE = "VIEW"' );
1535                 $allViews = [];
1536                 foreach ( $res as $row ) {
1537                         array_push( $allViews, $row->$propertyName );
1538                 }
1539
1540                 if ( is_null( $prefix ) || $prefix === '' ) {
1541                         return $allViews;
1542                 }
1543
1544                 $filteredViews = [];
1545                 foreach ( $allViews as $viewName ) {
1546                         // Does the name of this VIEW start with the table-prefix?
1547                         if ( strpos( $viewName, $prefix ) === 0 ) {
1548                                 array_push( $filteredViews, $viewName );
1549                         }
1550                 }
1551
1552                 return $filteredViews;
1553         }
1554
1555         /**
1556          * Differentiates between a TABLE and a VIEW.
1557          *
1558          * @param string $name Name of the TABLE/VIEW to test
1559          * @param string|null $prefix
1560          * @return bool
1561          * @since 1.22
1562          */
1563         public function isView( $name, $prefix = null ) {
1564                 return in_array( $name, $this->listViews( $prefix ) );
1565         }
1566
1567         protected function isTransactableQuery( $sql ) {
1568                 return parent::isTransactableQuery( $sql ) &&
1569                         !preg_match( '/^SELECT\s+(GET|RELEASE|IS_FREE)_LOCK\(/', $sql );
1570         }
1571
1572         public function buildStringCast( $field ) {
1573                 return "CAST( $field AS BINARY )";
1574         }
1575
1576         /**
1577          * @param string $field Field or column to cast
1578          * @return string
1579          */
1580         public function buildIntegerCast( $field ) {
1581                 return 'CAST( ' . $field . ' AS SIGNED )';
1582         }
1583
1584         /*
1585          * @return bool Whether GTID support is used (mockable for testing)
1586          */
1587         protected function useGTIDs() {
1588                 return $this->useGTIDs;
1589         }
1590 }
1591
1592 /**
1593  * @deprecated since 1.29
1594  */
1595 class_alias( DatabaseMysqlBase::class, 'DatabaseMysqlBase' );