includes/libs/rdbms/database/DatabaseMysqlBase.php

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