includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Psr\Log\NullLogger;
  31 use Wikimedia\ScopedCallback;
  32 use Wikimedia\Timestamp\ConvertibleTimestamp;
  33 use Wikimedia;
  34 use BagOStuff;
  35 use HashBagOStuff;
  36 use LogicException;
  37 use InvalidArgumentException;
  38 use UnexpectedValueException;
  39 use Exception;
  40 use RuntimeException;
  41 use Throwable;
  42
  43 /**
  44  * Relational database abstraction object
  45  *
  46  * @ingroup Database
  47  * @since 1.28
  48  */
  49 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  50         /** @var string Server that this instance is currently connected to */
  51         protected $server;
  52         /** @var string User that this instance is currently connected under the name of */
  53         protected $user;
  54         /** @var string Password used to establish the current connection */
  55         protected $password;
  56         /** @var array[] Map of (table => (dbname, schema, prefix) map) */
  57         protected $tableAliases = [];
  58         /** @var string[] Map of (index alias => index) */
  59         protected $indexAliases = [];
  60         /** @var bool Whether this PHP instance is for a CLI script */
  61         protected $cliMode;
  62         /** @var string Agent name for query profiling */
  63         protected $agent;
  64         /** @var int Bitfield of class DBO_* constants */
  65         protected $flags;
  66         /** @var array LoadBalancer tracking information */
  67         protected $lbInfo = [];
  68         /** @var array|bool Variables use for schema element placeholders */
  69         protected $schemaVars = false;
  70         /** @var array Parameters used by initConnection() to establish a connection */
  71         protected $connectionParams = [];
  72         /** @var array SQL variables values to use for all new connections */
  73         protected $connectionVariables = [];
  74         /** @var string Current SQL query delimiter */
  75         protected $delimiter = ';';
  76         /** @var string|bool|null Stashed value of html_errors INI setting */
  77         protected $htmlErrors;
  78         /** @var int Row batch size to use for emulated INSERT SELECT queries */
  79         protected $nonNativeInsertSelectBatchSize = 10000;
  80
  81         /** @var BagOStuff APC cache */
  82         protected $srvCache;
  83         /** @var LoggerInterface */
  84         protected $connLogger;
  85         /** @var LoggerInterface */
  86         protected $queryLogger;
  87         /** @var callable Error logging callback */
  88         protected $errorLogger;
  89         /** @var callable Deprecation logging callback */
  90         protected $deprecationLogger;
  91         /** @var callable|null */
  92         protected $profiler;
  93         /** @var TransactionProfiler */
  94         protected $trxProfiler;
  95         /** @var DatabaseDomain */
  96         protected $currentDomain;
  97         /** @var object|resource|null Database connection */
  98         protected $conn;
  99
 100         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 101         private $lazyMasterHandle;
 102
 103         /** @var array Map of (name => 1) for locks obtained via lock() */
 104         protected $sessionNamedLocks = [];
 105         /** @var array Map of (table name => 1) for TEMPORARY tables */
 106         protected $sessionTempTables = [];
 107
 108         /** @var string ID of the active transaction or the empty string otherwise */
 109         protected $trxShortId = '';
 110         /** @var int Transaction status */
 111         protected $trxStatus = self::STATUS_TRX_NONE;
 112         /** @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR */
 113         protected $trxStatusCause;
 114         /** @var array|null Error details of the last statement-only rollback */
 115         private $trxStatusIgnoredCause;
 116         /** @var float|null UNIX timestamp at the time of BEGIN for the last transaction */
 117         private $trxTimestamp = null;
 118         /** @var float Replication lag estimate at the time of BEGIN for the last transaction */
 119         private $trxReplicaLag = null;
 120         /** @var string Name of the function that start the last transaction */
 121         private $trxFname = null;
 122         /** @var bool Whether possible write queries were done in the last transaction started */
 123         private $trxDoneWrites = false;
 124         /** @var bool Whether the current transaction was started implicitly due to DBO_TRX */
 125         private $trxAutomatic = false;
 126         /** @var int Counter for atomic savepoint identifiers (reset with each transaction) */
 127         private $trxAtomicCounter = 0;
 128         /** @var array List of (name, unique ID, savepoint ID) for each active atomic section level */
 129         private $trxAtomicLevels = [];
 130         /** @var bool Whether the current transaction was started implicitly by startAtomic() */
 131         private $trxAutomaticAtomic = false;
 132         /** @var string[] Write query callers of the current transaction */
 133         private $trxWriteCallers = [];
 134         /** @var float Seconds spent in write queries for the current transaction */
 135         private $trxWriteDuration = 0.0;
 136         /** @var int Number of write queries for the current transaction */
 137         private $trxWriteQueryCount = 0;
 138         /** @var int Number of rows affected by write queries for the current transaction */
 139         private $trxWriteAffectedRows = 0;
 140         /** @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries */
 141         private $trxWriteAdjDuration = 0.0;
 142         /** @var int Number of write queries counted in trxWriteAdjDuration */
 143         private $trxWriteAdjQueryCount = 0;
 144         /** @var array[] List of (callable, method name, atomic section id) */
 145         private $trxIdleCallbacks = [];
 146         /** @var array[] List of (callable, method name, atomic section id) */
 147         private $trxPreCommitCallbacks = [];
 148         /** @var array[] List of (callable, method name, atomic section id) */
 149         private $trxEndCallbacks = [];
 150         /** @var array[] List of (callable, method name, atomic section id) */
 151         private $trxSectionCancelCallbacks = [];
 152         /** @var callable[] Map of (name => callable) */
 153         private $trxRecurringCallbacks = [];
 154         /** @var bool Whether to suppress triggering of transaction end callbacks */
 155         private $trxEndCallbacksSuppressed = false;
 156
 157         /** @var int[] Prior flags member variable values */
 158         private $priorFlags = [];
 159
 160         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 161         protected $affectedRowCount;
 162
 163         /** @var float UNIX timestamp */
 164         private $lastPing = 0.0;
 165         /** @var string The last SQL query attempted */
 166         private $lastQuery = '';
 167         /** @var float|bool UNIX timestamp of last write query */
 168         private $lastWriteTime = false;
 169         /** @var string|bool */
 170         private $lastPhpError = false;
 171         /** @var float Query rount trip time estimate */
 172         private $lastRoundTripEstimate = 0.0;
 173
 174         /** @var string Lock granularity is on the level of the entire database */
 175         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
 176         /** @var string The SCHEMA keyword refers to a grouping of tables in a database */
 177         const ATTR_SCHEMAS_AS_TABLE_GROUPS = 'supports-schemas';
 178
 179         /** @var int New Database instance will not be connected yet when returned */
 180         const NEW_UNCONNECTED = 0;
 181         /** @var int New Database instance will already be connected when returned */
 182         const NEW_CONNECTED = 1;
 183
 184         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 185         const STATUS_TRX_ERROR = 1;
 186         /** @var int Transaction is active and in a normal state */
 187         const STATUS_TRX_OK = 2;
 188         /** @var int No transaction is active */
 189         const STATUS_TRX_NONE = 3;
 190
 191         /** @var string Idiom used when a cancelable atomic section started the transaction */
 192         private static $NOT_APPLICABLE = 'n/a';
 193         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 194         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 195
 196         /** @var int Writes to this temporary table do not affect lastDoneWrites() */
 197         private static $TEMP_NORMAL = 1;
 198         /** @var int Writes to this temporary table effect lastDoneWrites() */
 199         private static $TEMP_PSEUDO_PERMANENT = 2;
 200
 201         /** Number of times to re-try an operation in case of deadlock */
 202         private static $DEADLOCK_TRIES = 4;
 203         /** Minimum time to wait before retry, in microseconds */
 204         private static $DEADLOCK_DELAY_MIN = 500000;
 205         /** Maximum time to wait before retry */
 206         private static $DEADLOCK_DELAY_MAX = 1500000;
 207
 208         /** How long before it is worth doing a dummy query to test the connection */
 209         private static $PING_TTL = 1.0;
 210         private static $PING_QUERY = 'SELECT 1 AS ping';
 211
 212         private static $TINY_WRITE_SEC = 0.010;
 213         private static $SLOW_WRITE_SEC = 0.500;
 214         private static $SMALL_WRITE_ROWS = 100;
 215
 216         /**
 217          * @note exceptions for missing libraries/drivers should be thrown in initConnection()
 218          * @param array $params Parameters passed from Database::factory()
 219          */
 220         protected function __construct( array $params ) {
 221                 foreach ( [ 'host', 'user', 'password', 'dbname', 'schema', 'tablePrefix' ] as $name ) {
 222                         $this->connectionParams[$name] = $params[$name];
 223                 }
 224
 225                 $this->cliMode = $params['cliMode'];
 226                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 227                 $this->agent = str_replace( '/', '-', $params['agent'] );
 228
 229                 $this->flags = $params['flags'];
 230                 if ( $this->flags & self::DBO_DEFAULT ) {
 231                         if ( $this->cliMode ) {
 232                                 $this->flags &= ~self::DBO_TRX;
 233                         } else {
 234                                 $this->flags |= self::DBO_TRX;
 235                         }
 236                 }
 237                 // Disregard deprecated DBO_IGNORE flag (T189999)
 238                 $this->flags &= ~self::DBO_IGNORE;
 239
 240                 $this->connectionVariables = $params['variables'];
 241
 242                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 243
 244                 $this->profiler = is_callable( $params['profiler'] ) ? $params['profiler'] : null;
 245                 $this->trxProfiler = $params['trxProfiler'];
 246                 $this->connLogger = $params['connLogger'];
 247                 $this->queryLogger = $params['queryLogger'];
 248                 $this->errorLogger = $params['errorLogger'];
 249                 $this->deprecationLogger = $params['deprecationLogger'];
 250
 251                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 252                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 253                 }
 254
 255                 // Set initial dummy domain until open() sets the final DB/prefix
 256                 $this->currentDomain = new DatabaseDomain(
 257                         $params['dbname'] != '' ? $params['dbname'] : null,
 258                         $params['schema'] != '' ? $params['schema'] : null,
 259                         $params['tablePrefix']
 260                 );
 261         }
 262
 263         /**
 264          * Initialize the connection to the database over the wire (or to local files)
 265          *
 266          * @throws LogicException
 267          * @throws InvalidArgumentException
 268          * @throws DBConnectionError
 269          * @since 1.31
 270          */
 271         final public function initConnection() {
 272                 if ( $this->isOpen() ) {
 273                         throw new LogicException( __METHOD__ . ': already connected.' );
 274                 }
 275                 // Establish the connection
 276                 $this->doInitConnection();
 277         }
 278
 279         /**
 280          * Actually connect to the database over the wire (or to local files)
 281          *
 282          * @throws InvalidArgumentException
 283          * @throws DBConnectionError
 284          * @since 1.31
 285          */
 286         protected function doInitConnection() {
 287                 if ( strlen( $this->connectionParams['user'] ) ) {
 288                         $this->open(
 289                                 $this->connectionParams['host'],
 290                                 $this->connectionParams['user'],
 291                                 $this->connectionParams['password'],
 292                                 $this->connectionParams['dbname'],
 293                                 $this->connectionParams['schema'],
 294                                 $this->connectionParams['tablePrefix']
 295                         );
 296                 } else {
 297                         throw new InvalidArgumentException( "No database user provided." );
 298                 }
 299         }
 300
 301         /**
 302          * Open a new connection to the database (closing any existing one)
 303          *
 304          * @param string $server Database server host
 305          * @param string $user Database user name
 306          * @param string $password Database user password
 307          * @param string $dbName Database name
 308          * @param string|null $schema Database schema name
 309          * @param string $tablePrefix Table prefix
 310          * @throws DBConnectionError
 311          */
 312         abstract protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix );
 313
 314         /**
 315          * Construct a Database subclass instance given a database type and parameters
 316          *
 317          * This also connects to the database immediately upon object construction
 318          *
 319          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 320          * @param array $p Parameter map with keys:
 321          *   - host : The hostname of the DB server
 322          *   - user : The name of the database user the client operates under
 323          *   - password : The password for the database user
 324          *   - dbname : The name of the database to use where queries do not specify one.
 325          *      The database must exist or an error might be thrown. Setting this to the empty string
 326          *      will avoid any such errors and make the handle have no implicit database scope. This is
 327          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 328          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 329          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 330          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 331          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 332          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 333          *      recognized in queries. This can be used in place of schemas for handle site farms.
 334          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 335          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 336          *      flag in place UNLESS this this database simply acts as a key/value store.
 337          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 338          *      'mysqli' driver; the old one 'mysql' has been removed.
 339          *   - variables: Optional map of session variables to set after connecting. This can be
 340          *      used to adjust lock timeouts or encoding modes and the like.
 341          *   - connLogger: Optional PSR-3 logger interface instance.
 342          *   - queryLogger: Optional PSR-3 logger interface instance.
 343          *   - profiler : Optional callback that takes a section name argument and returns
 344          *      a ScopedCallback instance that ends the profile section in its destructor.
 345          *      These will be called in query(), using a simplified version of the SQL that
 346          *      also includes the agent as a SQL comment.
 347          *   - trxProfiler: Optional TransactionProfiler instance.
 348          *   - errorLogger: Optional callback that takes an Exception and logs it.
 349          *   - deprecationLogger: Optional callback that takes a string and logs it.
 350          *   - cliMode: Whether to consider the execution context that of a CLI script.
 351          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 352          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 353          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 354          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 355          * @return Database|null If the database driver or extension cannot be found
 356          * @throws InvalidArgumentException If the database driver or extension cannot be found
 357          * @since 1.18
 358          */
 359         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 360                 $class = self::getClass( $dbType, $p['driver'] ?? null );
 361
 362                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 363                         // Resolve some defaults for b/c
 364                         $p['host'] = $p['host'] ?? false;
 365                         $p['user'] = $p['user'] ?? false;
 366                         $p['password'] = $p['password'] ?? false;
 367                         $p['dbname'] = $p['dbname'] ?? false;
 368                         $p['flags'] = $p['flags'] ?? 0;
 369                         $p['variables'] = $p['variables'] ?? [];
 370                         $p['tablePrefix'] = $p['tablePrefix'] ?? '';
 371                         $p['schema'] = $p['schema'] ?? null;
 372                         $p['cliMode'] = $p['cliMode'] ?? ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 373                         $p['agent'] = $p['agent'] ?? '';
 374                         if ( !isset( $p['connLogger'] ) ) {
 375                                 $p['connLogger'] = new NullLogger();
 376                         }
 377                         if ( !isset( $p['queryLogger'] ) ) {
 378                                 $p['queryLogger'] = new NullLogger();
 379                         }
 380                         $p['profiler'] = $p['profiler'] ?? null;
 381                         if ( !isset( $p['trxProfiler'] ) ) {
 382                                 $p['trxProfiler'] = new TransactionProfiler();
 383                         }
 384                         if ( !isset( $p['errorLogger'] ) ) {
 385                                 $p['errorLogger'] = function ( Exception $e ) {
 386                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 387                                 };
 388                         }
 389                         if ( !isset( $p['deprecationLogger'] ) ) {
 390                                 $p['deprecationLogger'] = function ( $msg ) {
 391                                         trigger_error( $msg, E_USER_DEPRECATED );
 392                                 };
 393                         }
 394
 395                         /** @var Database $conn */
 396                         $conn = new $class( $p );
 397                         if ( $connect == self::NEW_CONNECTED ) {
 398                                 $conn->initConnection();
 399                         }
 400                 } else {
 401                         $conn = null;
 402                 }
 403
 404                 return $conn;
 405         }
 406
 407         /**
 408          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 409          * @param string|null $driver Optional name of a specific DB client driver
 410          * @return array Map of (Database::ATTR_* constant => value) for all such constants
 411          * @throws InvalidArgumentException
 412          * @since 1.31
 413          */
 414         final public static function attributesFromType( $dbType, $driver = null ) {
 415                 static $defaults = [
 416                         self::ATTR_DB_LEVEL_LOCKING => false,
 417                         self::ATTR_SCHEMAS_AS_TABLE_GROUPS => false
 418                 ];
 419
 420                 $class = self::getClass( $dbType, $driver );
 421
 422                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 423         }
 424
 425         /**
 426          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 427          * @param string|null $driver Optional name of a specific DB client driver
 428          * @return string Database subclass name to use
 429          * @throws InvalidArgumentException
 430          */
 431         private static function getClass( $dbType, $driver = null ) {
 432                 // For database types with built-in support, the below maps type to IDatabase
 433                 // implementations. For types with multipe driver implementations (PHP extensions),
 434                 // an array can be used, keyed by extension name. In case of an array, the
 435                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 436                 // we auto-detect the first available driver. For types without built-in support,
 437                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 438                 static $builtinTypes = [
 439                         'mssql' => DatabaseMssql::class,
 440                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 441                         'sqlite' => DatabaseSqlite::class,
 442                         'postgres' => DatabasePostgres::class,
 443                 ];
 444
 445                 $dbType = strtolower( $dbType );
 446                 $class = false;
 447
 448                 if ( isset( $builtinTypes[$dbType] ) ) {
 449                         $possibleDrivers = $builtinTypes[$dbType];
 450                         if ( is_string( $possibleDrivers ) ) {
 451                                 $class = $possibleDrivers;
 452                         } elseif ( (string)$driver !== '' ) {
 453                                 if ( !isset( $possibleDrivers[$driver] ) ) {
 454                                         throw new InvalidArgumentException( __METHOD__ .
 455                                                 " type '$dbType' does not support driver '{$driver}'" );
 456                                 }
 457
 458                                 $class = $possibleDrivers[$driver];
 459                         } else {
 460                                 foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 461                                         if ( extension_loaded( $posDriver ) ) {
 462                                                 $class = $possibleClass;
 463                                                 break;
 464                                         }
 465                                 }
 466                         }
 467                 } else {
 468                         $class = 'Database' . ucfirst( $dbType );
 469                 }
 470
 471                 if ( $class === false ) {
 472                         throw new InvalidArgumentException( __METHOD__ .
 473                                 " no viable database extension found for type '$dbType'" );
 474                 }
 475
 476                 return $class;
 477         }
 478
 479         /**
 480          * @return array Map of (Database::ATTR_* constant => value
 481          * @since 1.31
 482          */
 483         protected static function getAttributes() {
 484                 return [];
 485         }
 486
 487         /**
 488          * Set the PSR-3 logger interface to use for query logging. (The logger
 489          * interfaces for connection logging and error logging can be set with the
 490          * constructor.)
 491          *
 492          * @param LoggerInterface $logger
 493          */
 494         public function setLogger( LoggerInterface $logger ) {
 495                 $this->queryLogger = $logger;
 496         }
 497
 498         public function getServerInfo() {
 499                 return $this->getServerVersion();
 500         }
 501
 502         public function bufferResults( $buffer = null ) {
 503                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 504                 if ( $buffer !== null ) {
 505                         $buffer
 506                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 507                                 : $this->setFlag( self::DBO_NOBUFFER );
 508                 }
 509
 510                 return $res;
 511         }
 512
 513         final public function trxLevel() {
 514                 return ( $this->trxShortId != '' ) ? 1 : 0;
 515         }
 516
 517         public function trxTimestamp() {
 518                 return $this->trxLevel() ? $this->trxTimestamp : null;
 519         }
 520
 521         /**
 522          * @return int One of the STATUS_TRX_* class constants
 523          * @since 1.31
 524          */
 525         public function trxStatus() {
 526                 return $this->trxStatus;
 527         }
 528
 529         public function tablePrefix( $prefix = null ) {
 530                 $old = $this->currentDomain->getTablePrefix();
 531                 if ( $prefix !== null ) {
 532                         $this->currentDomain = new DatabaseDomain(
 533                                 $this->currentDomain->getDatabase(),
 534                                 $this->currentDomain->getSchema(),
 535                                 $prefix
 536                         );
 537                 }
 538
 539                 return $old;
 540         }
 541
 542         public function dbSchema( $schema = null ) {
 543                 if ( strlen( $schema ) && $this->getDBname() === null ) {
 544                         throw new DBUnexpectedError( $this, "Cannot set schema to '$schema'; no database set." );
 545                 }
 546
 547                 $old = $this->currentDomain->getSchema();
 548                 if ( $schema !== null ) {
 549                         $this->currentDomain = new DatabaseDomain(
 550                                 $this->currentDomain->getDatabase(),
 551                                 // DatabaseDomain uses null for unspecified schemas
 552                                 strlen( $schema ) ? $schema : null,
 553                                 $this->currentDomain->getTablePrefix()
 554                         );
 555                 }
 556
 557                 return (string)$old;
 558         }
 559
 560         /**
 561          * @return string Schema to use to qualify relations in queries
 562          */
 563         protected function relationSchemaQualifier() {
 564                 return $this->dbSchema();
 565         }
 566
 567         public function getLBInfo( $name = null ) {
 568                 if ( is_null( $name ) ) {
 569                         return $this->lbInfo;
 570                 }
 571
 572                 if ( array_key_exists( $name, $this->lbInfo ) ) {
 573                         return $this->lbInfo[$name];
 574                 }
 575
 576                 return null;
 577         }
 578
 579         public function setLBInfo( $name, $value = null ) {
 580                 if ( is_null( $value ) ) {
 581                         $this->lbInfo = $name;
 582                 } else {
 583                         $this->lbInfo[$name] = $value;
 584                 }
 585         }
 586
 587         public function setLazyMasterHandle( IDatabase $conn ) {
 588                 $this->lazyMasterHandle = $conn;
 589         }
 590
 591         /**
 592          * @return IDatabase|null
 593          * @see setLazyMasterHandle()
 594          * @since 1.27
 595          */
 596         protected function getLazyMasterHandle() {
 597                 return $this->lazyMasterHandle;
 598         }
 599
 600         public function implicitGroupby() {
 601                 return true;
 602         }
 603
 604         public function implicitOrderby() {
 605                 return true;
 606         }
 607
 608         public function lastQuery() {
 609                 return $this->lastQuery;
 610         }
 611
 612         public function doneWrites() {
 613                 return (bool)$this->lastWriteTime;
 614         }
 615
 616         public function lastDoneWrites() {
 617                 return $this->lastWriteTime ?: false;
 618         }
 619
 620         public function writesPending() {
 621                 return $this->trxLevel() && $this->trxDoneWrites;
 622         }
 623
 624         public function writesOrCallbacksPending() {
 625                 return $this->trxLevel() && (
 626                         $this->trxDoneWrites ||
 627                         $this->trxIdleCallbacks ||
 628                         $this->trxPreCommitCallbacks ||
 629                         $this->trxEndCallbacks ||
 630                         $this->trxSectionCancelCallbacks
 631                 );
 632         }
 633
 634         public function preCommitCallbacksPending() {
 635                 return $this->trxLevel() && $this->trxPreCommitCallbacks;
 636         }
 637
 638         /**
 639          * @return string|null
 640          */
 641         final protected function getTransactionRoundId() {
 642                 // If transaction round participation is enabled, see if one is active
 643                 if ( $this->getFlag( self::DBO_TRX ) ) {
 644                         $id = $this->getLBInfo( 'trxRoundId' );
 645
 646                         return is_string( $id ) ? $id : null;
 647                 }
 648
 649                 return null;
 650         }
 651
 652         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 653                 if ( !$this->trxLevel() ) {
 654                         return false;
 655                 } elseif ( !$this->trxDoneWrites ) {
 656                         return 0.0;
 657                 }
 658
 659                 switch ( $type ) {
 660                         case self::ESTIMATE_DB_APPLY:
 661                                 return $this->pingAndCalculateLastTrxApplyTime();
 662                         default: // everything
 663                                 return $this->trxWriteDuration;
 664                 }
 665         }
 666
 667         /**
 668          * @return float Time to apply writes to replicas based on trxWrite* fields
 669          */
 670         private function pingAndCalculateLastTrxApplyTime() {
 671                 $this->ping( $rtt );
 672
 673                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 674                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 675                 // For omitted queries, make them count as something at least
 676                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 677                 $applyTime += self::$TINY_WRITE_SEC * $omitted;
 678
 679                 return $applyTime;
 680         }
 681
 682         public function pendingWriteCallers() {
 683                 return $this->trxLevel() ? $this->trxWriteCallers : [];
 684         }
 685
 686         public function pendingWriteRowsAffected() {
 687                 return $this->trxWriteAffectedRows;
 688         }
 689
 690         /**
 691          * List the methods that have write queries or callbacks for the current transaction
 692          *
 693          * This method should not be used outside of Database/LoadBalancer
 694          *
 695          * @return string[]
 696          * @since 1.32
 697          */
 698         public function pendingWriteAndCallbackCallers() {
 699                 $fnames = $this->pendingWriteCallers();
 700                 foreach ( [
 701                         $this->trxIdleCallbacks,
 702                         $this->trxPreCommitCallbacks,
 703                         $this->trxEndCallbacks,
 704                         $this->trxSectionCancelCallbacks
 705                 ] as $callbacks ) {
 706                         foreach ( $callbacks as $callback ) {
 707                                 $fnames[] = $callback[1];
 708                         }
 709                 }
 710
 711                 return $fnames;
 712         }
 713
 714         /**
 715          * @return string
 716          */
 717         private function flatAtomicSectionList() {
 718                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 719                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 720                 } );
 721         }
 722
 723         public function isOpen() {
 724                 return (bool)$this->conn;
 725         }
 726
 727         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 728                 if ( ( $flag & self::DBO_IGNORE ) ) {
 729                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 730                 }
 731
 732                 if ( $remember === self::REMEMBER_PRIOR ) {
 733                         array_push( $this->priorFlags, $this->flags );
 734                 }
 735                 $this->flags |= $flag;
 736         }
 737
 738         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 739                 if ( ( $flag & self::DBO_IGNORE ) ) {
 740                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 741                 }
 742
 743                 if ( $remember === self::REMEMBER_PRIOR ) {
 744                         array_push( $this->priorFlags, $this->flags );
 745                 }
 746                 $this->flags &= ~$flag;
 747         }
 748
 749         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 750                 if ( !$this->priorFlags ) {
 751                         return;
 752                 }
 753
 754                 if ( $state === self::RESTORE_INITIAL ) {
 755                         $this->flags = reset( $this->priorFlags );
 756                         $this->priorFlags = [];
 757                 } else {
 758                         $this->flags = array_pop( $this->priorFlags );
 759                 }
 760         }
 761
 762         public function getFlag( $flag ) {
 763                 return (bool)( $this->flags & $flag );
 764         }
 765
 766         /**
 767          * @param string $name Class field name
 768          * @return mixed
 769          * @deprecated Since 1.28
 770          */
 771         public function getProperty( $name ) {
 772                 return $this->$name;
 773         }
 774
 775         public function getDomainID() {
 776                 return $this->currentDomain->getId();
 777         }
 778
 779         final public function getWikiID() {
 780                 return $this->getDomainID();
 781         }
 782
 783         /**
 784          * Get information about an index into an object
 785          * @param string $table Table name
 786          * @param string $index Index name
 787          * @param string $fname Calling function name
 788          * @return mixed Database-specific index description class or false if the index does not exist
 789          */
 790         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 791
 792         /**
 793          * Wrapper for addslashes()
 794          *
 795          * @param string $s String to be slashed.
 796          * @return string Slashed string.
 797          */
 798         abstract function strencode( $s );
 799
 800         /**
 801          * Set a custom error handler for logging errors during database connection
 802          */
 803         protected function installErrorHandler() {
 804                 $this->lastPhpError = false;
 805                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 806                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 807         }
 808
 809         /**
 810          * Restore the previous error handler and return the last PHP error for this DB
 811          *
 812          * @return bool|string
 813          */
 814         protected function restoreErrorHandler() {
 815                 restore_error_handler();
 816                 if ( $this->htmlErrors !== false ) {
 817                         ini_set( 'html_errors', $this->htmlErrors );
 818                 }
 819
 820                 return $this->getLastPHPError();
 821         }
 822
 823         /**
 824          * @return string|bool Last PHP error for this DB (typically connection errors)
 825          */
 826         protected function getLastPHPError() {
 827                 if ( $this->lastPhpError ) {
 828                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->lastPhpError );
 829                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 830
 831                         return $error;
 832                 }
 833
 834                 return false;
 835         }
 836
 837         /**
 838          * Error handler for logging errors during database connection
 839          * This method should not be used outside of Database classes
 840          *
 841          * @param int $errno
 842          * @param string $errstr
 843          */
 844         public function connectionErrorLogger( $errno, $errstr ) {
 845                 $this->lastPhpError = $errstr;
 846         }
 847
 848         /**
 849          * Create a log context to pass to PSR-3 logger functions.
 850          *
 851          * @param array $extras Additional data to add to context
 852          * @return array
 853          */
 854         protected function getLogContext( array $extras = [] ) {
 855                 return array_merge(
 856                         [
 857                                 'db_server' => $this->server,
 858                                 'db_name' => $this->getDBname(),
 859                                 'db_user' => $this->user,
 860                         ],
 861                         $extras
 862                 );
 863         }
 864
 865         final public function close() {
 866                 $exception = null; // error to throw after disconnecting
 867
 868                 $wasOpen = (bool)$this->conn;
 869                 // This should mostly do nothing if the connection is already closed
 870                 if ( $this->conn ) {
 871                         // Roll back any dangling transaction first
 872                         if ( $this->trxLevel() ) {
 873                                 if ( $this->trxAtomicLevels ) {
 874                                         // Cannot let incomplete atomic sections be committed
 875                                         $levels = $this->flatAtomicSectionList();
 876                                         $exception = new DBUnexpectedError(
 877                                                 $this,
 878                                                 __METHOD__ . ": atomic sections $levels are still open."
 879                                         );
 880                                 } elseif ( $this->trxAutomatic ) {
 881                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 882                                         // (empty ones we can silently roll back)
 883                                         if ( $this->writesOrCallbacksPending() ) {
 884                                                 $exception = new DBUnexpectedError(
 885                                                         $this,
 886                                                         __METHOD__ .
 887                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)."
 888                                                 );
 889                                         }
 890                                 } else {
 891                                         // Manual transactions should have been committed or rolled
 892                                         // back, even if empty.
 893                                         $exception = new DBUnexpectedError(
 894                                                 $this,
 895                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})."
 896                                         );
 897                                 }
 898
 899                                 if ( $this->trxEndCallbacksSuppressed ) {
 900                                         $exception = $exception ?: new DBUnexpectedError(
 901                                                 $this,
 902                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 903                                         );
 904                                 }
 905
 906                                 // Rollback the changes and run any callbacks as needed
 907                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 908                         }
 909
 910                         // Close the actual connection in the binding handle
 911                         $closed = $this->closeConnection();
 912                 } else {
 913                         $closed = true; // already closed; nothing to do
 914                 }
 915
 916                 $this->conn = false;
 917
 918                 // Throw any unexpected errors after having disconnected
 919                 if ( $exception instanceof Exception ) {
 920                         throw $exception;
 921                 }
 922
 923                 // Note that various subclasses call close() at the start of open(), which itself is
 924                 // called by replaceLostConnection(). In that case, just because onTransactionResolution()
 925                 // callbacks are pending does not mean that an exception should be thrown. Rather, they
 926                 // will be executed after the reconnection step.
 927                 if ( $wasOpen ) {
 928                         // Sanity check that no callbacks are dangling
 929                         $fnames = $this->pendingWriteAndCallbackCallers();
 930                         if ( $fnames ) {
 931                                 throw new RuntimeException(
 932                                         "Transaction callbacks are still pending:\n" . implode( ', ', $fnames )
 933                                 );
 934                         }
 935                 }
 936
 937                 return $closed;
 938         }
 939
 940         /**
 941          * Make sure there is an open connection handle (alive or not) as a sanity check
 942          *
 943          * This guards against fatal errors to the binding handle not being defined
 944          * in cases where open() was never called or close() was already called
 945          *
 946          * @throws DBUnexpectedError
 947          */
 948         final protected function assertHasConnectionHandle() {
 949                 if ( !$this->isOpen() ) {
 950                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 951                 }
 952         }
 953
 954         /**
 955          * Make sure that this server is not marked as a replica nor read-only as a sanity check
 956          *
 957          * @throws DBReadOnlyRoleError
 958          * @throws DBReadOnlyError
 959          */
 960         protected function assertIsWritableMaster() {
 961                 if ( $this->getLBInfo( 'replica' ) === true ) {
 962                         throw new DBReadOnlyRoleError(
 963                                 $this,
 964                                 'Write operations are not allowed on replica database connections.'
 965                         );
 966                 }
 967                 $reason = $this->getReadOnlyReason();
 968                 if ( $reason !== false ) {
 969                         throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 970                 }
 971         }
 972
 973         /**
 974          * Closes underlying database connection
 975          * @since 1.20
 976          * @return bool Whether connection was closed successfully
 977          */
 978         abstract protected function closeConnection();
 979
 980         /**
 981          * Run a query and return a DBMS-dependent wrapper or boolean
 982          *
 983          * This is meant to handle the basic command of actually sending a query to the
 984          * server via the driver. No implicit transaction, reconnection, nor retry logic
 985          * should happen here. The higher level query() method is designed to handle those
 986          * sorts of concerns. This method should not trigger such higher level methods.
 987          *
 988          * The lastError() and lastErrno() methods should meaningfully reflect what error,
 989          * if any, occured during the last call to this method. Methods like executeQuery(),
 990          * query(), select(), insert(), update(), delete(), and upsert() implement their calls
 991          * to doQuery() such that an immediately subsequent call to lastError()/lastErrno()
 992          * meaningfully reflects any error that occured during that public query method call.
 993          *
 994          * For SELECT queries, this returns either:
 995          *   - a) A driver-specific value/resource, only on success. This can be iterated
 996          *        over by calling fetchObject()/fetchRow() until there are no more rows.
 997          *        Alternatively, the result can be passed to resultObject() to obtain an
 998          *        IResultWrapper instance which can then be iterated over via "foreach".
 999          *   - b) False, on any query failure
1000          *
1001          * For non-SELECT queries, this returns either:
1002          *   - a) A driver-specific value/resource, only on success
1003          *   - b) True, only on success (e.g. no meaningful result other than "OK")
1004          *   - c) False, on any query failure
1005          *
1006          * @param string $sql SQL query
1007          * @return mixed|bool An object, resource, or true on success; false on failure
1008          */
1009         abstract protected function doQuery( $sql );
1010
1011         /**
1012          * Determine whether a query writes to the DB. When in doubt, this returns true.
1013          *
1014          * Main use cases:
1015          *
1016          * - Subsequent web requests should not need to wait for replication from
1017          *   the master position seen by this web request, unless this request made
1018          *   changes to the master. This is handled by ChronologyProtector by checking
1019          *   doneWrites() at the end of the request. doneWrites() returns true if any
1020          *   query set lastWriteTime; which query() does based on isWriteQuery().
1021          *
1022          * - Reject write queries to replica DBs, in query().
1023          *
1024          * @param string $sql
1025          * @return bool
1026          */
1027         protected function isWriteQuery( $sql ) {
1028                 // BEGIN and COMMIT queries are considered read queries here.
1029                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1030                 // treat these as write queries, in that their results have "affected rows"
1031                 // as meta data as from writes, instead of "num rows" as from reads.
1032                 // But, we treat them as read queries because when reading data (from
1033                 // either replica or master) we use transactions to enable repeatable-read
1034                 // snapshots, which ensures we get consistent results from the same snapshot
1035                 // for all queries within a request. Use cases:
1036                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1037                 // - We use this method to reject writes to replicas, but we need to allow
1038                 //   use of transactions on replicas for read snapshots. This is fine given
1039                 //   that transactions by themselves don't make changes, only actual writes
1040                 //   within the transaction matter, which we still detect.
1041                 return !preg_match(
1042                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SAVEPOINT|RELEASE|SET|SHOW|EXPLAIN|USE|\(SELECT)\b/i',
1043                         $sql
1044                 );
1045         }
1046
1047         /**
1048          * @param string $sql
1049          * @return string|null
1050          */
1051         protected function getQueryVerb( $sql ) {
1052                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1053         }
1054
1055         /**
1056          * Determine whether a SQL statement is sensitive to isolation level.
1057          *
1058          * A SQL statement is considered transactable if its result could vary
1059          * depending on the transaction isolation level. Operational commands
1060          * such as 'SET' and 'SHOW' are not considered to be transactable.
1061          *
1062          * Main purpose: Used by query() to decide whether to begin a transaction
1063          * before the current query (in DBO_TRX mode, on by default).
1064          *
1065          * @param string $sql
1066          * @return bool
1067          */
1068         protected function isTransactableQuery( $sql ) {
1069                 return !in_array(
1070                         $this->getQueryVerb( $sql ),
1071                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER', 'USE', 'SHOW' ],
1072                         true
1073                 );
1074         }
1075
1076         /**
1077          * @param string $sql A SQL query
1078          * @param bool $pseudoPermanent Treat any table from CREATE TEMPORARY as pseudo-permanent
1079          * @return int|null A self::TEMP_* constant for temp table operations or null otherwise
1080          */
1081         protected function registerTempTableWrite( $sql, $pseudoPermanent ) {
1082                 static $qt = '[`"\']?(\w+)[`"\']?'; // quoted table
1083
1084                 if ( preg_match(
1085                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?' . $qt . '/i',
1086                         $sql,
1087                         $matches
1088                 ) ) {
1089                         $type = $pseudoPermanent ? self::$TEMP_PSEUDO_PERMANENT : self::$TEMP_NORMAL;
1090                         $this->sessionTempTables[$matches[1]] = $type;
1091
1092                         return $type;
1093                 } elseif ( preg_match(
1094                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1095                         $sql,
1096                         $matches
1097                 ) ) {
1098                         $type = $this->sessionTempTables[$matches[1]] ?? null;
1099                         unset( $this->sessionTempTables[$matches[1]] );
1100
1101                         return $type;
1102                 } elseif ( preg_match(
1103                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1104                         $sql,
1105                         $matches
1106                 ) ) {
1107                         return $this->sessionTempTables[$matches[1]] ?? null;
1108                 } elseif ( preg_match(
1109                         '/^(?:(?:INSERT|REPLACE)\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+' . $qt . '/i',
1110                         $sql,
1111                         $matches
1112                 ) ) {
1113                         return $this->sessionTempTables[$matches[1]] ?? null;
1114                 }
1115
1116                 return null;
1117         }
1118
1119         public function query( $sql, $fname = __METHOD__, $flags = 0 ) {
1120                 $flags = (int)$flags; // b/c; this field used to be a bool
1121                 // Sanity check that the SQL query is appropriate in the current context and is
1122                 // allowed for an outside caller (e.g. does not break transaction/session tracking).
1123                 $this->assertQueryIsCurrentlyAllowed( $sql, $fname );
1124
1125                 // Send the query to the server and fetch any corresponding errors
1126                 list( $ret, $err, $errno, $unignorable ) = $this->executeQuery( $sql, $fname, $flags );
1127                 if ( $ret === false ) {
1128                         $ignoreErrors = $this->hasFlags( $flags, self::QUERY_SILENCE_ERRORS );
1129                         // Throw an error unless both the ignore flag was set and a rollback is not needed
1130                         $this->reportQueryError( $err, $errno, $sql, $fname, $ignoreErrors && !$unignorable );
1131                 }
1132
1133                 return $this->resultObject( $ret );
1134         }
1135
1136         /**
1137          * Execute a query, retrying it if there is a recoverable connection loss
1138          *
1139          * This is similar to query() except:
1140          *   - It does not prevent all non-ROLLBACK queries if there is a corrupted transaction
1141          *   - It does not disallow raw queries that are supposed to use dedicated IDatabase methods
1142          *   - It does not throw exceptions for common error cases
1143          *
1144          * This is meant for internal use with Database subclasses.
1145          *
1146          * @param string $sql Original SQL query
1147          * @param string $fname Name of the calling function
1148          * @param int $flags Bitfield of class QUERY_* constants
1149          * @return array An n-tuple of:
1150          *   - mixed|bool: An object, resource, or true on success; false on failure
1151          *   - string: The result of calling lastError()
1152          *   - int: The result of calling lastErrno()
1153          *   - bool: Whether a rollback is needed to allow future non-rollback queries
1154          * @throws DBUnexpectedError
1155          */
1156         final protected function executeQuery( $sql, $fname, $flags ) {
1157                 $this->assertHasConnectionHandle();
1158
1159                 $priorTransaction = $this->trxLevel();
1160
1161                 if ( $this->isWriteQuery( $sql ) ) {
1162                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1163                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1164                         $this->assertIsWritableMaster();
1165                         # Do not treat temporary table writes as "meaningful writes" since they are only
1166                         # visible to one session and are not permanent. Profile them as reads. Integration
1167                         # tests can override this behavior via $flags.
1168                         $pseudoPermanent = $this->hasFlags( $flags, self::QUERY_PSEUDO_PERMANENT );
1169                         $tableType = $this->registerTempTableWrite( $sql, $pseudoPermanent );
1170                         $isPermWrite = ( $tableType !== self::$TEMP_NORMAL );
1171                         # DBConnRef uses QUERY_REPLICA_ROLE to enforce the replica role for raw SQL queries
1172                         if ( $isPermWrite && $this->hasFlags( $flags, self::QUERY_REPLICA_ROLE ) ) {
1173                                 throw new DBReadOnlyRoleError( $this, "Cannot write; target role is DB_REPLICA" );
1174                         }
1175                 } else {
1176                         $isPermWrite = false;
1177                 }
1178
1179                 // Add trace comment to the begin of the sql string, right after the operator.
1180                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1181                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1182
1183                 // Send the query to the server and fetch any corresponding errors
1184                 list( $ret, $err, $errno, $recoverableSR, $recoverableCL, $reconnected ) =
1185                         $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1186
1187                 // Check if the query failed due to a recoverable connection loss
1188                 $allowRetry = !$this->hasFlags( $flags, self::QUERY_NO_RETRY );
1189                 if ( $ret === false && $recoverableCL && $reconnected && $allowRetry ) {
1190                         // Silently resend the query to the server since it is safe and possible
1191                         list( $ret, $err, $errno, $recoverableSR, $recoverableCL ) =
1192                                 $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1193                 }
1194
1195                 $corruptedTrx = false;
1196
1197                 if ( $ret === false ) {
1198                         if ( $priorTransaction ) {
1199                                 if ( $recoverableSR ) {
1200                                         # We're ignoring an error that caused just the current query to be aborted.
1201                                         # But log the cause so we can log a deprecation notice if a caller actually
1202                                         # does ignore it.
1203                                         $this->trxStatusIgnoredCause = [ $err, $errno, $fname ];
1204                                 } elseif ( !$recoverableCL ) {
1205                                         # Either the query was aborted or all queries after BEGIN where aborted.
1206                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1207                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1208                                         # option is ROLLBACK, since the snapshots would have been released.
1209                                         $corruptedTrx = true; // cannot recover
1210                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1211                                         $this->trxStatusCause =
1212                                                 $this->getQueryExceptionAndLog( $err, $errno, $sql, $fname );
1213                                         $this->trxStatusIgnoredCause = null;
1214                                 }
1215                         }
1216                 }
1217
1218                 return [ $ret, $err, $errno, $corruptedTrx ];
1219         }
1220
1221         /**
1222          * Wrapper for doQuery() that handles DBO_TRX, profiling, logging, affected row count
1223          * tracking, and reconnects (without retry) on query failure due to connection loss
1224          *
1225          * @param string $sql Original SQL query
1226          * @param string $commentedSql SQL query with debugging/trace comment
1227          * @param bool $isPermWrite Whether the query is a (non-temporary table) write
1228          * @param string $fname Name of the calling function
1229          * @param int $flags Bitfield of class QUERY_* constants
1230          * @return array An n-tuple of:
1231          *   - mixed|bool: An object, resource, or true on success; false on failure
1232          *   - string: The result of calling lastError()
1233          *   - int: The result of calling lastErrno()
1234          *       - bool: Whether a statement rollback error occured
1235          *   - bool: Whether a disconnect *both* happened *and* was recoverable
1236          *   - bool: Whether a reconnection attempt was *both* made *and* succeeded
1237          * @throws DBUnexpectedError
1238          */
1239         private function executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags ) {
1240                 $priorWritesPending = $this->writesOrCallbacksPending();
1241
1242                 if ( ( $flags & self::QUERY_IGNORE_DBO_TRX ) == 0 ) {
1243                         $this->beginIfImplied( $sql, $fname );
1244                 }
1245
1246                 // Keep track of whether the transaction has write queries pending
1247                 if ( $isPermWrite ) {
1248                         $this->lastWriteTime = microtime( true );
1249                         if ( $this->trxLevel() && !$this->trxDoneWrites ) {
1250                                 $this->trxDoneWrites = true;
1251                                 $this->trxProfiler->transactionWritingIn(
1252                                         $this->server, $this->getDomainID(), $this->trxShortId );
1253                         }
1254                 }
1255
1256                 $prefix = !is_null( $this->getLBInfo( 'master' ) ) ? 'query-m: ' : 'query: ';
1257                 $generalizedSql = new GeneralizedSql( $sql, $this->trxShortId, $prefix );
1258
1259                 $startTime = microtime( true );
1260                 $ps = $this->profiler
1261                         ? ( $this->profiler )( $generalizedSql->stringify() )
1262                         : null;
1263                 $this->affectedRowCount = null;
1264                 $this->lastQuery = $sql;
1265                 $ret = $this->doQuery( $commentedSql );
1266                 $lastError = $this->lastError();
1267                 $lastErrno = $this->lastErrno();
1268
1269                 $this->affectedRowCount = $this->affectedRows();
1270                 unset( $ps ); // profile out (if set)
1271                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1272
1273                 $recoverableSR = false; // recoverable statement rollback?
1274                 $recoverableCL = false; // recoverable connection loss?
1275                 $reconnected = false; // reconnection both attempted and succeeded?
1276
1277                 if ( $ret !== false ) {
1278                         $this->lastPing = $startTime;
1279                         if ( $isPermWrite && $this->trxLevel() ) {
1280                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1281                                 $this->trxWriteCallers[] = $fname;
1282                         }
1283                 } elseif ( $this->wasConnectionError( $lastErrno ) ) {
1284                         # Check if no meaningful session state was lost
1285                         $recoverableCL = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1286                         # Update session state tracking and try to restore the connection
1287                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1288                 } else {
1289                         # Check if only the last query was rolled back
1290                         $recoverableSR = $this->wasKnownStatementRollbackError();
1291                 }
1292
1293                 if ( $sql === self::$PING_QUERY ) {
1294                         $this->lastRoundTripEstimate = $queryRuntime;
1295                 }
1296
1297                 $this->trxProfiler->recordQueryCompletion(
1298                         $generalizedSql,
1299                         $startTime,
1300                         $isPermWrite,
1301                         $isPermWrite ? $this->affectedRows() : $this->numRows( $ret )
1302                 );
1303
1304                 // Avoid the overhead of logging calls unless debug mode is enabled
1305                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1306                         $this->queryLogger->debug(
1307                                 "{method} [{runtime}s]: $sql",
1308                                 [
1309                                         'method' => $fname,
1310                                         'db_host' => $this->getServer(),
1311                                         'domain' => $this->getDomainID(),
1312                                         'runtime' => round( $queryRuntime, 3 )
1313                                 ]
1314                         );
1315                 }
1316
1317                 return [ $ret, $lastError, $lastErrno, $recoverableSR, $recoverableCL, $reconnected ];
1318         }
1319
1320         /**
1321          * Start an implicit transaction if DBO_TRX is enabled and no transaction is active
1322          *
1323          * @param string $sql
1324          * @param string $fname
1325          */
1326         private function beginIfImplied( $sql, $fname ) {
1327                 if (
1328                         !$this->trxLevel() &&
1329                         $this->getFlag( self::DBO_TRX ) &&
1330                         $this->isTransactableQuery( $sql )
1331                 ) {
1332                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1333                         $this->trxAutomatic = true;
1334                 }
1335         }
1336
1337         /**
1338          * Update the estimated run-time of a query, not counting large row lock times
1339          *
1340          * LoadBalancer can be set to rollback transactions that will create huge replication
1341          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1342          * queries, like inserting a row can take a long time due to row locking. This method
1343          * uses some simple heuristics to discount those cases.
1344          *
1345          * @param string $sql A SQL write query
1346          * @param float $runtime Total runtime, including RTT
1347          * @param int $affected Affected row count
1348          */
1349         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1350                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1351                 $indicativeOfReplicaRuntime = true;
1352                 if ( $runtime > self::$SLOW_WRITE_SEC ) {
1353                         $verb = $this->getQueryVerb( $sql );
1354                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1355                         if ( $verb === 'INSERT' ) {
1356                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS;
1357                         } elseif ( $verb === 'REPLACE' ) {
1358                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS / 2;
1359                         }
1360                 }
1361
1362                 $this->trxWriteDuration += $runtime;
1363                 $this->trxWriteQueryCount += 1;
1364                 $this->trxWriteAffectedRows += $affected;
1365                 if ( $indicativeOfReplicaRuntime ) {
1366                         $this->trxWriteAdjDuration += $runtime;
1367                         $this->trxWriteAdjQueryCount += 1;
1368                 }
1369         }
1370
1371         /**
1372          * Error out if the DB is not in a valid state for a query via query()
1373          *
1374          * @param string $sql
1375          * @param string $fname
1376          * @throws DBTransactionStateError
1377          */
1378         private function assertQueryIsCurrentlyAllowed( $sql, $fname ) {
1379                 $verb = $this->getQueryVerb( $sql );
1380                 if ( $verb === 'USE' ) {
1381                         throw new DBUnexpectedError( $this, "Got USE query; use selectDomain() instead." );
1382                 }
1383
1384                 if ( $verb === 'ROLLBACK' ) { // transaction/savepoint
1385                         return;
1386                 }
1387
1388                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1389                         throw new DBTransactionStateError(
1390                                 $this,
1391                                 "Cannot execute query from $fname while transaction status is ERROR.",
1392                                 [],
1393                                 $this->trxStatusCause
1394                         );
1395                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1396                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1397                         call_user_func( $this->deprecationLogger,
1398                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1399                                 "[$iLastErrno] $iLastError"
1400                         );
1401                         $this->trxStatusIgnoredCause = null;
1402                 }
1403         }
1404
1405         public function assertNoOpenTransactions() {
1406                 if ( $this->explicitTrxActive() ) {
1407                         throw new DBTransactionError(
1408                                 $this,
1409                                 "Explicit transaction still active. A caller may have caught an error. "
1410                                 . "Open transactions: " . $this->flatAtomicSectionList()
1411                         );
1412                 }
1413         }
1414
1415         /**
1416          * Determine whether it is safe to retry queries after a database connection is lost
1417          *
1418          * @param string $sql SQL query
1419          * @param bool $priorWritesPending Whether there is a transaction open with
1420          *     possible write queries or transaction pre-commit/idle callbacks
1421          *     waiting on it to finish.
1422          * @return bool True if it is safe to retry the query, false otherwise
1423          */
1424         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1425                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1426                 # Dropped connections also mean that named locks are automatically released.
1427                 # Only allow error suppression in autocommit mode or when the lost transaction
1428                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1429                 if ( $this->sessionNamedLocks ) {
1430                         return false; // possible critical section violation
1431                 } elseif ( $this->sessionTempTables ) {
1432                         return false; // tables might be queried latter
1433                 } elseif ( $sql === 'COMMIT' ) {
1434                         return !$priorWritesPending; // nothing written anyway? (T127428)
1435                 } elseif ( $sql === 'ROLLBACK' ) {
1436                         return true; // transaction lost...which is also what was requested :)
1437                 } elseif ( $this->explicitTrxActive() ) {
1438                         return false; // don't drop atomocity and explicit snapshots
1439                 } elseif ( $priorWritesPending ) {
1440                         return false; // prior writes lost from implicit transaction
1441                 }
1442
1443                 return true;
1444         }
1445
1446         /**
1447          * Clean things up after session (and thus transaction) loss before reconnect
1448          */
1449         private function handleSessionLossPreconnect() {
1450                 // Clean up tracking of session-level things...
1451                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1452                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1453                 $this->sessionTempTables = [];
1454                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1455                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1456                 $this->sessionNamedLocks = [];
1457                 // Session loss implies transaction loss
1458                 $oldTrxShortId = $this->consumeTrxShortId();
1459                 $this->trxAtomicCounter = 0;
1460                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1461                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1462                 // @note: leave trxRecurringCallbacks in place
1463                 if ( $this->trxDoneWrites ) {
1464                         $this->trxProfiler->transactionWritingOut(
1465                                 $this->server,
1466                                 $this->getDomainID(),
1467                                 $oldTrxShortId,
1468                                 $this->pendingWriteQueryDuration( self::ESTIMATE_TOTAL ),
1469                                 $this->trxWriteAffectedRows
1470                         );
1471                 }
1472         }
1473
1474         /**
1475          * Clean things up after session (and thus transaction) loss after reconnect
1476          */
1477         private function handleSessionLossPostconnect() {
1478                 try {
1479                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1480                         // If callback suppression is set then the array will remain unhandled.
1481                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1482                 } catch ( Exception $ex ) {
1483                         // Already logged; move on...
1484                 }
1485                 try {
1486                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1487                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1488                 } catch ( Exception $ex ) {
1489                         // Already logged; move on...
1490                 }
1491         }
1492
1493         /**
1494          * Reset the transaction ID and return the old one
1495          *
1496          * @return string The old transaction ID or the empty string if there wasn't one
1497          */
1498         private function consumeTrxShortId() {
1499                 $old = $this->trxShortId;
1500                 $this->trxShortId = '';
1501
1502                 return $old;
1503         }
1504
1505         /**
1506          * Checks whether the cause of the error is detected to be a timeout.
1507          *
1508          * It returns false by default, and not all engines support detecting this yet.
1509          * If this returns false, it will be treated as a generic query error.
1510          *
1511          * @param string $error Error text
1512          * @param int $errno Error number
1513          * @return bool
1514          */
1515         protected function wasQueryTimeout( $error, $errno ) {
1516                 return false;
1517         }
1518
1519         /**
1520          * Report a query error. Log the error, and if neither the object ignore
1521          * flag nor the $ignoreErrors flag is set, throw a DBQueryError.
1522          *
1523          * @param string $error
1524          * @param int $errno
1525          * @param string $sql
1526          * @param string $fname
1527          * @param bool $ignore
1528          * @throws DBQueryError
1529          */
1530         public function reportQueryError( $error, $errno, $sql, $fname, $ignore = false ) {
1531                 if ( $ignore ) {
1532                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1533                 } else {
1534                         $exception = $this->getQueryExceptionAndLog( $error, $errno, $sql, $fname );
1535
1536                         throw $exception;
1537                 }
1538         }
1539
1540         /**
1541          * @param string $error
1542          * @param string|int $errno
1543          * @param string $sql
1544          * @param string $fname
1545          * @return DBError
1546          */
1547         private function getQueryExceptionAndLog( $error, $errno, $sql, $fname ) {
1548                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1549                 $this->queryLogger->error(
1550                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1551                         $this->getLogContext( [
1552                                 'method' => __METHOD__,
1553                                 'errno' => $errno,
1554                                 'error' => $error,
1555                                 'sql1line' => $sql1line,
1556                                 'fname' => $fname,
1557                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1558                         ] )
1559                 );
1560                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1561                 if ( $this->wasQueryTimeout( $error, $errno ) ) {
1562                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1563                 } elseif ( $this->wasConnectionError( $errno ) ) {
1564                         $e = new DBQueryDisconnectedError( $this, $error, $errno, $sql, $fname );
1565                 } else {
1566                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1567                 }
1568
1569                 return $e;
1570         }
1571
1572         public function freeResult( $res ) {
1573         }
1574
1575         public function selectField(
1576                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1577         ) {
1578                 if ( $var === '*' ) { // sanity
1579                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1580                 }
1581
1582                 if ( !is_array( $options ) ) {
1583                         $options = [ $options ];
1584                 }
1585
1586                 $options['LIMIT'] = 1;
1587
1588                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1589                 if ( $res === false ) {
1590                         throw new DBUnexpectedError( $this, "Got false from select()" );
1591                 }
1592
1593                 $row = $this->fetchRow( $res );
1594                 if ( $row === false ) {
1595                         return false;
1596                 }
1597
1598                 return reset( $row );
1599         }
1600
1601         public function selectFieldValues(
1602                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1603         ) {
1604                 if ( $var === '*' ) { // sanity
1605                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1606                 } elseif ( !is_string( $var ) ) { // sanity
1607                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1608                 }
1609
1610                 if ( !is_array( $options ) ) {
1611                         $options = [ $options ];
1612                 }
1613
1614                 $res = $this->select( $table, [ 'value' => $var ], $cond, $fname, $options, $join_conds );
1615                 if ( $res === false ) {
1616                         throw new DBUnexpectedError( $this, "Got false from select()" );
1617                 }
1618
1619                 $values = [];
1620                 foreach ( $res as $row ) {
1621                         $values[] = $row->value;
1622                 }
1623
1624                 return $values;
1625         }
1626
1627         /**
1628          * Returns an optional USE INDEX clause to go after the table, and a
1629          * string to go at the end of the query.
1630          *
1631          * @param array $options Associative array of options to be turned into
1632          *   an SQL query, valid keys are listed in the function.
1633          * @return array
1634          * @see Database::select()
1635          */
1636         protected function makeSelectOptions( $options ) {
1637                 $preLimitTail = $postLimitTail = '';
1638                 $startOpts = '';
1639
1640                 $noKeyOptions = [];
1641
1642                 foreach ( $options as $key => $option ) {
1643                         if ( is_numeric( $key ) ) {
1644                                 $noKeyOptions[$option] = true;
1645                         }
1646                 }
1647
1648                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1649
1650                 $preLimitTail .= $this->makeOrderBy( $options );
1651
1652                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1653                         $postLimitTail .= ' FOR UPDATE';
1654                 }
1655
1656                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1657                         $postLimitTail .= ' LOCK IN SHARE MODE';
1658                 }
1659
1660                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1661                         $startOpts .= 'DISTINCT';
1662                 }
1663
1664                 # Various MySQL extensions
1665                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1666                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1667                 }
1668
1669                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1670                         $startOpts .= ' HIGH_PRIORITY';
1671                 }
1672
1673                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1674                         $startOpts .= ' SQL_BIG_RESULT';
1675                 }
1676
1677                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1678                         $startOpts .= ' SQL_BUFFER_RESULT';
1679                 }
1680
1681                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1682                         $startOpts .= ' SQL_SMALL_RESULT';
1683                 }
1684
1685                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1686                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1687                 }
1688
1689                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1690                         $startOpts .= ' SQL_CACHE';
1691                 }
1692
1693                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1694                         $startOpts .= ' SQL_NO_CACHE';
1695                 }
1696
1697                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1698                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1699                 } else {
1700                         $useIndex = '';
1701                 }
1702                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1703                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1704                 } else {
1705                         $ignoreIndex = '';
1706                 }
1707
1708                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1709         }
1710
1711         /**
1712          * Returns an optional GROUP BY with an optional HAVING
1713          *
1714          * @param array $options Associative array of options
1715          * @return string
1716          * @see Database::select()
1717          * @since 1.21
1718          */
1719         protected function makeGroupByWithHaving( $options ) {
1720                 $sql = '';
1721                 if ( isset( $options['GROUP BY'] ) ) {
1722                         $gb = is_array( $options['GROUP BY'] )
1723                                 ? implode( ',', $options['GROUP BY'] )
1724                                 : $options['GROUP BY'];
1725                         $sql .= ' GROUP BY ' . $gb;
1726                 }
1727                 if ( isset( $options['HAVING'] ) ) {
1728                         $having = is_array( $options['HAVING'] )
1729                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1730                                 : $options['HAVING'];
1731                         $sql .= ' HAVING ' . $having;
1732                 }
1733
1734                 return $sql;
1735         }
1736
1737         /**
1738          * Returns an optional ORDER BY
1739          *
1740          * @param array $options Associative array of options
1741          * @return string
1742          * @see Database::select()
1743          * @since 1.21
1744          */
1745         protected function makeOrderBy( $options ) {
1746                 if ( isset( $options['ORDER BY'] ) ) {
1747                         $ob = is_array( $options['ORDER BY'] )
1748                                 ? implode( ',', $options['ORDER BY'] )
1749                                 : $options['ORDER BY'];
1750
1751                         return ' ORDER BY ' . $ob;
1752                 }
1753
1754                 return '';
1755         }
1756
1757         public function select(
1758                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1759         ) {
1760                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1761
1762                 return $this->query( $sql, $fname );
1763         }
1764
1765         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1766                 $options = [], $join_conds = []
1767         ) {
1768                 if ( is_array( $vars ) ) {
1769                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1770                 } else {
1771                         $fields = $vars;
1772                 }
1773
1774                 $options = (array)$options;
1775                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1776                         ? $options['USE INDEX']
1777                         : [];
1778                 $ignoreIndexes = (
1779                         isset( $options['IGNORE INDEX'] ) &&
1780                         is_array( $options['IGNORE INDEX'] )
1781                 )
1782                         ? $options['IGNORE INDEX']
1783                         : [];
1784
1785                 if (
1786                         $this->selectOptionsIncludeLocking( $options ) &&
1787                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1788                 ) {
1789                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1790                         // functions. Discourage use of such queries to encourage compatibility.
1791                         call_user_func(
1792                                 $this->deprecationLogger,
1793                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)."
1794                         );
1795                 }
1796
1797                 if ( is_array( $table ) ) {
1798                         $from = ' FROM ' .
1799                                 $this->tableNamesWithIndexClauseOrJOIN(
1800                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1801                 } elseif ( $table != '' ) {
1802                         $from = ' FROM ' .
1803                                 $this->tableNamesWithIndexClauseOrJOIN(
1804                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1805                 } else {
1806                         $from = '';
1807                 }
1808
1809                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1810                         $this->makeSelectOptions( $options );
1811
1812                 if ( is_array( $conds ) ) {
1813                         $conds = $this->makeList( $conds, self::LIST_AND );
1814                 }
1815
1816                 if ( $conds === null || $conds === false ) {
1817                         $this->queryLogger->warning(
1818                                 __METHOD__
1819                                 . ' called from '
1820                                 . $fname
1821                                 . ' with incorrect parameters: $conds must be a string or an array'
1822                         );
1823                         $conds = '';
1824                 }
1825
1826                 if ( $conds === '' || $conds === '*' ) {
1827                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1828                 } elseif ( is_string( $conds ) ) {
1829                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1830                                 "WHERE $conds $preLimitTail";
1831                 } else {
1832                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1833                 }
1834
1835                 if ( isset( $options['LIMIT'] ) ) {
1836                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1837                                 $options['OFFSET'] ?? false );
1838                 }
1839                 $sql = "$sql $postLimitTail";
1840
1841                 if ( isset( $options['EXPLAIN'] ) ) {
1842                         $sql = 'EXPLAIN ' . $sql;
1843                 }
1844
1845                 return $sql;
1846         }
1847
1848         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1849                 $options = [], $join_conds = []
1850         ) {
1851                 $options = (array)$options;
1852                 $options['LIMIT'] = 1;
1853
1854                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1855                 if ( $res === false ) {
1856                         throw new DBUnexpectedError( $this, "Got false from select()" );
1857                 }
1858
1859                 if ( !$this->numRows( $res ) ) {
1860                         return false;
1861                 }
1862
1863                 return $this->fetchObject( $res );
1864         }
1865
1866         public function estimateRowCount(
1867                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1868         ) {
1869                 $conds = $this->normalizeConditions( $conds, $fname );
1870                 $column = $this->extractSingleFieldFromList( $var );
1871                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1872                         $conds[] = "$column IS NOT NULL";
1873                 }
1874
1875                 $res = $this->select(
1876                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1877                 );
1878                 $row = $res ? $this->fetchRow( $res ) : [];
1879
1880                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1881         }
1882
1883         public function selectRowCount(
1884                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1885         ) {
1886                 $conds = $this->normalizeConditions( $conds, $fname );
1887                 $column = $this->extractSingleFieldFromList( $var );
1888                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1889                         $conds[] = "$column IS NOT NULL";
1890                 }
1891
1892                 $res = $this->select(
1893                         [
1894                                 'tmp_count' => $this->buildSelectSubquery(
1895                                         $tables,
1896                                         '1',
1897                                         $conds,
1898                                         $fname,
1899                                         $options,
1900                                         $join_conds
1901                                 )
1902                         ],
1903                         [ 'rowcount' => 'COUNT(*)' ],
1904                         [],
1905                         $fname
1906                 );
1907                 $row = $res ? $this->fetchRow( $res ) : [];
1908
1909                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1910         }
1911
1912         /**
1913          * @param string|array $options
1914          * @return bool
1915          */
1916         private function selectOptionsIncludeLocking( $options ) {
1917                 $options = (array)$options;
1918                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1919                         if ( in_array( $lock, $options, true ) ) {
1920                                 return true;
1921                         }
1922                 }
1923
1924                 return false;
1925         }
1926
1927         /**
1928          * @param array|string $fields
1929          * @param array|string $options
1930          * @return bool
1931          */
1932         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1933                 foreach ( (array)$options as $key => $value ) {
1934                         if ( is_string( $key ) ) {
1935                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1936                                         return true;
1937                                 }
1938                         } elseif ( is_string( $value ) ) {
1939                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1940                                         return true;
1941                                 }
1942                         }
1943                 }
1944
1945                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1946                 foreach ( (array)$fields as $field ) {
1947                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1948                                 return true;
1949                         }
1950                 }
1951
1952                 return false;
1953         }
1954
1955         /**
1956          * @param array|string $conds
1957          * @param string $fname
1958          * @return array
1959          */
1960         final protected function normalizeConditions( $conds, $fname ) {
1961                 if ( $conds === null || $conds === false ) {
1962                         $this->queryLogger->warning(
1963                                 __METHOD__
1964                                 . ' called from '
1965                                 . $fname
1966                                 . ' with incorrect parameters: $conds must be a string or an array'
1967                         );
1968                         $conds = '';
1969                 }
1970
1971                 if ( !is_array( $conds ) ) {
1972                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1973                 }
1974
1975                 return $conds;
1976         }
1977
1978         /**
1979          * @param array|string $var Field parameter in the style of select()
1980          * @return string|null Column name or null; ignores aliases
1981          * @throws DBUnexpectedError Errors out if multiple columns are given
1982          */
1983         final protected function extractSingleFieldFromList( $var ) {
1984                 if ( is_array( $var ) ) {
1985                         if ( !$var ) {
1986                                 $column = null;
1987                         } elseif ( count( $var ) == 1 ) {
1988                                 $column = $var[0] ?? reset( $var );
1989                         } else {
1990                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1991                         }
1992                 } else {
1993                         $column = $var;
1994                 }
1995
1996                 return $column;
1997         }
1998
1999         public function lockForUpdate(
2000                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
2001         ) {
2002                 if ( !$this->trxLevel() && !$this->getFlag( self::DBO_TRX ) ) {
2003                         throw new DBUnexpectedError(
2004                                 $this,
2005                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
2006                         );
2007                 }
2008
2009                 $options = (array)$options;
2010                 $options[] = 'FOR UPDATE';
2011
2012                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
2013         }
2014
2015         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
2016                 $info = $this->fieldInfo( $table, $field );
2017
2018                 return (bool)$info;
2019         }
2020
2021         public function indexExists( $table, $index, $fname = __METHOD__ ) {
2022                 if ( !$this->tableExists( $table ) ) {
2023                         return null;
2024                 }
2025
2026                 $info = $this->indexInfo( $table, $index, $fname );
2027                 if ( is_null( $info ) ) {
2028                         return null;
2029                 } else {
2030                         return $info !== false;
2031                 }
2032         }
2033
2034         abstract public function tableExists( $table, $fname = __METHOD__ );
2035
2036         public function indexUnique( $table, $index ) {
2037                 $indexInfo = $this->indexInfo( $table, $index );
2038
2039                 if ( !$indexInfo ) {
2040                         return null;
2041                 }
2042
2043                 return !$indexInfo[0]->Non_unique;
2044         }
2045
2046         /**
2047          * Helper for Database::insert().
2048          *
2049          * @param array $options
2050          * @return string
2051          */
2052         protected function makeInsertOptions( $options ) {
2053                 return implode( ' ', $options );
2054         }
2055
2056         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2057                 # No rows to insert, easy just return now
2058                 if ( !count( $a ) ) {
2059                         return true;
2060                 }
2061
2062                 $table = $this->tableName( $table );
2063
2064                 if ( !is_array( $options ) ) {
2065                         $options = [ $options ];
2066                 }
2067
2068                 $options = $this->makeInsertOptions( $options );
2069
2070                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2071                         $multi = true;
2072                         $keys = array_keys( $a[0] );
2073                 } else {
2074                         $multi = false;
2075                         $keys = array_keys( $a );
2076                 }
2077
2078                 $sql = 'INSERT ' . $options .
2079                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2080
2081                 if ( $multi ) {
2082                         $first = true;
2083                         foreach ( $a as $row ) {
2084                                 if ( $first ) {
2085                                         $first = false;
2086                                 } else {
2087                                         $sql .= ',';
2088                                 }
2089                                 $sql .= '(' . $this->makeList( $row ) . ')';
2090                         }
2091                 } else {
2092                         $sql .= '(' . $this->makeList( $a ) . ')';
2093                 }
2094
2095                 $this->query( $sql, $fname );
2096
2097                 return true;
2098         }
2099
2100         /**
2101          * Make UPDATE options array for Database::makeUpdateOptions
2102          *
2103          * @param array $options
2104          * @return array
2105          */
2106         protected function makeUpdateOptionsArray( $options ) {
2107                 if ( !is_array( $options ) ) {
2108                         $options = [ $options ];
2109                 }
2110
2111                 $opts = [];
2112
2113                 if ( in_array( 'IGNORE', $options ) ) {
2114                         $opts[] = 'IGNORE';
2115                 }
2116
2117                 return $opts;
2118         }
2119
2120         /**
2121          * Make UPDATE options for the Database::update function
2122          *
2123          * @param array $options The options passed to Database::update
2124          * @return string
2125          */
2126         protected function makeUpdateOptions( $options ) {
2127                 $opts = $this->makeUpdateOptionsArray( $options );
2128
2129                 return implode( ' ', $opts );
2130         }
2131
2132         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2133                 $table = $this->tableName( $table );
2134                 $opts = $this->makeUpdateOptions( $options );
2135                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2136
2137                 if ( $conds !== [] && $conds !== '*' ) {
2138                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2139                 }
2140
2141                 $this->query( $sql, $fname );
2142
2143                 return true;
2144         }
2145
2146         public function makeList( $a, $mode = self::LIST_COMMA ) {
2147                 if ( !is_array( $a ) ) {
2148                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2149                 }
2150
2151                 $first = true;
2152                 $list = '';
2153
2154                 foreach ( $a as $field => $value ) {
2155                         if ( !$first ) {
2156                                 if ( $mode == self::LIST_AND ) {
2157                                         $list .= ' AND ';
2158                                 } elseif ( $mode == self::LIST_OR ) {
2159                                         $list .= ' OR ';
2160                                 } else {
2161                                         $list .= ',';
2162                                 }
2163                         } else {
2164                                 $first = false;
2165                         }
2166
2167                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2168                                 $list .= "($value)";
2169                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2170                                 $list .= "$value";
2171                         } elseif (
2172                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2173                         ) {
2174                                 // Remove null from array to be handled separately if found
2175                                 $includeNull = false;
2176                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2177                                         $includeNull = true;
2178                                         unset( $value[$nullKey] );
2179                                 }
2180                                 if ( count( $value ) == 0 && !$includeNull ) {
2181                                         throw new InvalidArgumentException(
2182                                                 __METHOD__ . ": empty input for field $field" );
2183                                 } elseif ( count( $value ) == 0 ) {
2184                                         // only check if $field is null
2185                                         $list .= "$field IS NULL";
2186                                 } else {
2187                                         // IN clause contains at least one valid element
2188                                         if ( $includeNull ) {
2189                                                 // Group subconditions to ensure correct precedence
2190                                                 $list .= '(';
2191                                         }
2192                                         if ( count( $value ) == 1 ) {
2193                                                 // Special-case single values, as IN isn't terribly efficient
2194                                                 // Don't necessarily assume the single key is 0; we don't
2195                                                 // enforce linear numeric ordering on other arrays here.
2196                                                 $value = array_values( $value )[0];
2197                                                 $list .= $field . " = " . $this->addQuotes( $value );
2198                                         } else {
2199                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2200                                         }
2201                                         // if null present in array, append IS NULL
2202                                         if ( $includeNull ) {
2203                                                 $list .= " OR $field IS NULL)";
2204                                         }
2205                                 }
2206                         } elseif ( $value === null ) {
2207                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2208                                         $list .= "$field IS ";
2209                                 } elseif ( $mode == self::LIST_SET ) {
2210                                         $list .= "$field = ";
2211                                 }
2212                                 $list .= 'NULL';
2213                         } else {
2214                                 if (
2215                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2216                                 ) {
2217                                         $list .= "$field = ";
2218                                 }
2219                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2220                         }
2221                 }
2222
2223                 return $list;
2224         }
2225
2226         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2227                 $conds = [];
2228
2229                 foreach ( $data as $base => $sub ) {
2230                         if ( count( $sub ) ) {
2231                                 $conds[] = $this->makeList(
2232                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2233                                         self::LIST_AND );
2234                         }
2235                 }
2236
2237                 if ( $conds ) {
2238                         return $this->makeList( $conds, self::LIST_OR );
2239                 } else {
2240                         // Nothing to search for...
2241                         return false;
2242                 }
2243         }
2244
2245         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2246                 return $valuename;
2247         }
2248
2249         public function bitNot( $field ) {
2250                 return "(~$field)";
2251         }
2252
2253         public function bitAnd( $fieldLeft, $fieldRight ) {
2254                 return "($fieldLeft & $fieldRight)";
2255         }
2256
2257         public function bitOr( $fieldLeft, $fieldRight ) {
2258                 return "($fieldLeft | $fieldRight)";
2259         }
2260
2261         public function buildConcat( $stringList ) {
2262                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2263         }
2264
2265         public function buildGroupConcatField(
2266                 $delim, $table, $field, $conds = '', $join_conds = []
2267         ) {
2268                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2269
2270                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2271         }
2272
2273         public function buildSubstring( $input, $startPosition, $length = null ) {
2274                 $this->assertBuildSubstringParams( $startPosition, $length );
2275                 $functionBody = "$input FROM $startPosition";
2276                 if ( $length !== null ) {
2277                         $functionBody .= " FOR $length";
2278                 }
2279                 return 'SUBSTRING(' . $functionBody . ')';
2280         }
2281
2282         /**
2283          * Check type and bounds for parameters to self::buildSubstring()
2284          *
2285          * All supported databases have substring functions that behave the same for
2286          * positive $startPosition and non-negative $length, but behaviors differ when
2287          * given 0 or negative $startPosition or negative $length. The simplest
2288          * solution to that is to just forbid those values.
2289          *
2290          * @param int $startPosition
2291          * @param int|null $length
2292          * @since 1.31
2293          */
2294         protected function assertBuildSubstringParams( $startPosition, $length ) {
2295                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2296                         throw new InvalidArgumentException(
2297                                 '$startPosition must be a positive integer'
2298                         );
2299                 }
2300                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2301                         throw new InvalidArgumentException(
2302                                 '$length must be null or an integer greater than or equal to 0'
2303                         );
2304                 }
2305         }
2306
2307         public function buildStringCast( $field ) {
2308                 // In theory this should work for any standards-compliant
2309                 // SQL implementation, although it may not be the best way to do it.
2310                 return "CAST( $field AS CHARACTER )";
2311         }
2312
2313         public function buildIntegerCast( $field ) {
2314                 return 'CAST( ' . $field . ' AS INTEGER )';
2315         }
2316
2317         public function buildSelectSubquery(
2318                 $table, $vars, $conds = '', $fname = __METHOD__,
2319                 $options = [], $join_conds = []
2320         ) {
2321                 return new Subquery(
2322                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2323                 );
2324         }
2325
2326         public function databasesAreIndependent() {
2327                 return false;
2328         }
2329
2330         final public function selectDB( $db ) {
2331                 $this->selectDomain( new DatabaseDomain(
2332                         $db,
2333                         $this->currentDomain->getSchema(),
2334                         $this->currentDomain->getTablePrefix()
2335                 ) );
2336
2337                 return true;
2338         }
2339
2340         final public function selectDomain( $domain ) {
2341                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2342         }
2343
2344         protected function doSelectDomain( DatabaseDomain $domain ) {
2345                 $this->currentDomain = $domain;
2346         }
2347
2348         public function getDBname() {
2349                 return $this->currentDomain->getDatabase();
2350         }
2351
2352         public function getServer() {
2353                 return $this->server;
2354         }
2355
2356         public function tableName( $name, $format = 'quoted' ) {
2357                 if ( $name instanceof Subquery ) {
2358                         throw new DBUnexpectedError(
2359                                 $this,
2360                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2361                         );
2362                 }
2363
2364                 # Skip the entire process when we have a string quoted on both ends.
2365                 # Note that we check the end so that we will still quote any use of
2366                 # use of `database`.table. But won't break things if someone wants
2367                 # to query a database table with a dot in the name.
2368                 if ( $this->isQuotedIdentifier( $name ) ) {
2369                         return $name;
2370                 }
2371
2372                 # Lets test for any bits of text that should never show up in a table
2373                 # name. Basically anything like JOIN or ON which are actually part of
2374                 # SQL queries, but may end up inside of the table value to combine
2375                 # sql. Such as how the API is doing.
2376                 # Note that we use a whitespace test rather than a \b test to avoid
2377                 # any remote case where a word like on may be inside of a table name
2378                 # surrounded by symbols which may be considered word breaks.
2379                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2380                         $this->queryLogger->warning(
2381                                 __METHOD__ . ": use of subqueries is not supported this way.",
2382                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2383                         );
2384
2385                         return $name;
2386                 }
2387
2388                 # Split database and table into proper variables.
2389                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2390
2391                 # Quote $table and apply the prefix if not quoted.
2392                 # $tableName might be empty if this is called from Database::replaceVars()
2393                 $tableName = "{$prefix}{$table}";
2394                 if ( $format === 'quoted'
2395                         && !$this->isQuotedIdentifier( $tableName )
2396                         && $tableName !== ''
2397                 ) {
2398                         $tableName = $this->addIdentifierQuotes( $tableName );
2399                 }
2400
2401                 # Quote $schema and $database and merge them with the table name if needed
2402                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2403                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2404
2405                 return $tableName;
2406         }
2407
2408         /**
2409          * Get the table components needed for a query given the currently selected database
2410          *
2411          * @param string $name Table name in the form of db.schema.table, db.table, or table
2412          * @return array (DB name or "" for default, schema name, table prefix, table name)
2413          */
2414         protected function qualifiedTableComponents( $name ) {
2415                 # We reverse the explode so that database.table and table both output the correct table.
2416                 $dbDetails = explode( '.', $name, 3 );
2417                 if ( count( $dbDetails ) == 3 ) {
2418                         list( $database, $schema, $table ) = $dbDetails;
2419                         # We don't want any prefix added in this case
2420                         $prefix = '';
2421                 } elseif ( count( $dbDetails ) == 2 ) {
2422                         list( $database, $table ) = $dbDetails;
2423                         # We don't want any prefix added in this case
2424                         $prefix = '';
2425                         # In dbs that support it, $database may actually be the schema
2426                         # but that doesn't affect any of the functionality here
2427                         $schema = '';
2428                 } else {
2429                         list( $table ) = $dbDetails;
2430                         if ( isset( $this->tableAliases[$table] ) ) {
2431                                 $database = $this->tableAliases[$table]['dbname'];
2432                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2433                                         ? $this->tableAliases[$table]['schema']
2434                                         : $this->relationSchemaQualifier();
2435                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2436                                         ? $this->tableAliases[$table]['prefix']
2437                                         : $this->tablePrefix();
2438                         } else {
2439                                 $database = '';
2440                                 $schema = $this->relationSchemaQualifier(); # Default schema
2441                                 $prefix = $this->tablePrefix(); # Default prefix
2442                         }
2443                 }
2444
2445                 return [ $database, $schema, $prefix, $table ];
2446         }
2447
2448         /**
2449          * @param string|null $namespace Database or schema
2450          * @param string $relation Name of table, view, sequence, etc...
2451          * @param string $format One of (raw, quoted)
2452          * @return string Relation name with quoted and merged $namespace as needed
2453          */
2454         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2455                 if ( strlen( $namespace ) ) {
2456                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2457                                 $namespace = $this->addIdentifierQuotes( $namespace );
2458                         }
2459                         $relation = $namespace . '.' . $relation;
2460                 }
2461
2462                 return $relation;
2463         }
2464
2465         public function tableNames() {
2466                 $inArray = func_get_args();
2467                 $retVal = [];
2468
2469                 foreach ( $inArray as $name ) {
2470                         $retVal[$name] = $this->tableName( $name );
2471                 }
2472
2473                 return $retVal;
2474         }
2475
2476         public function tableNamesN() {
2477                 $inArray = func_get_args();
2478                 $retVal = [];
2479
2480                 foreach ( $inArray as $name ) {
2481                         $retVal[] = $this->tableName( $name );
2482                 }
2483
2484                 return $retVal;
2485         }
2486
2487         /**
2488          * Get an aliased table name
2489          *
2490          * This returns strings like "tableName AS newTableName" for aliased tables
2491          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2492          *
2493          * @see Database::tableName()
2494          * @param string|Subquery $table Table name or object with a 'sql' field
2495          * @param string|bool $alias Table alias (optional)
2496          * @return string SQL name for aliased table. Will not alias a table to its own name
2497          */
2498         protected function tableNameWithAlias( $table, $alias = false ) {
2499                 if ( is_string( $table ) ) {
2500                         $quotedTable = $this->tableName( $table );
2501                 } elseif ( $table instanceof Subquery ) {
2502                         $quotedTable = (string)$table;
2503                 } else {
2504                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2505                 }
2506
2507                 if ( $alias === false || $alias === $table ) {
2508                         if ( $table instanceof Subquery ) {
2509                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2510                         }
2511
2512                         return $quotedTable;
2513                 } else {
2514                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2515                 }
2516         }
2517
2518         /**
2519          * Gets an array of aliased table names
2520          *
2521          * @param array $tables [ [alias] => table ]
2522          * @return string[] See tableNameWithAlias()
2523          */
2524         protected function tableNamesWithAlias( $tables ) {
2525                 $retval = [];
2526                 foreach ( $tables as $alias => $table ) {
2527                         if ( is_numeric( $alias ) ) {
2528                                 $alias = $table;
2529                         }
2530                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2531                 }
2532
2533                 return $retval;
2534         }
2535
2536         /**
2537          * Get an aliased field name
2538          * e.g. fieldName AS newFieldName
2539          *
2540          * @param string $name Field name
2541          * @param string|bool $alias Alias (optional)
2542          * @return string SQL name for aliased field. Will not alias a field to its own name
2543          */
2544         protected function fieldNameWithAlias( $name, $alias = false ) {
2545                 if ( !$alias || (string)$alias === (string)$name ) {
2546                         return $name;
2547                 } else {
2548                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2549                 }
2550         }
2551
2552         /**
2553          * Gets an array of aliased field names
2554          *
2555          * @param array $fields [ [alias] => field ]
2556          * @return string[] See fieldNameWithAlias()
2557          */
2558         protected function fieldNamesWithAlias( $fields ) {
2559                 $retval = [];
2560                 foreach ( $fields as $alias => $field ) {
2561                         if ( is_numeric( $alias ) ) {
2562                                 $alias = $field;
2563                         }
2564                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2565                 }
2566
2567                 return $retval;
2568         }
2569
2570         /**
2571          * Get the aliased table name clause for a FROM clause
2572          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2573          *
2574          * @param array $tables ( [alias] => table )
2575          * @param array $use_index Same as for select()
2576          * @param array $ignore_index Same as for select()
2577          * @param array $join_conds Same as for select()
2578          * @return string
2579          */
2580         protected function tableNamesWithIndexClauseOrJOIN(
2581                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2582         ) {
2583                 $ret = [];
2584                 $retJOIN = [];
2585                 $use_index = (array)$use_index;
2586                 $ignore_index = (array)$ignore_index;
2587                 $join_conds = (array)$join_conds;
2588
2589                 foreach ( $tables as $alias => $table ) {
2590                         if ( !is_string( $alias ) ) {
2591                                 // No alias? Set it equal to the table name
2592                                 $alias = $table;
2593                         }
2594
2595                         if ( is_array( $table ) ) {
2596                                 // A parenthesized group
2597                                 if ( count( $table ) > 1 ) {
2598                                         $joinedTable = '(' .
2599                                                 $this->tableNamesWithIndexClauseOrJOIN(
2600                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2601                                 } else {
2602                                         // Degenerate case
2603                                         $innerTable = reset( $table );
2604                                         $innerAlias = key( $table );
2605                                         $joinedTable = $this->tableNameWithAlias(
2606                                                 $innerTable,
2607                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2608                                         );
2609                                 }
2610                         } else {
2611                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2612                         }
2613
2614                         // Is there a JOIN clause for this table?
2615                         if ( isset( $join_conds[$alias] ) ) {
2616                                 list( $joinType, $conds ) = $join_conds[$alias];
2617                                 $tableClause = $joinType;
2618                                 $tableClause .= ' ' . $joinedTable;
2619                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2620                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2621                                         if ( $use != '' ) {
2622                                                 $tableClause .= ' ' . $use;
2623                                         }
2624                                 }
2625                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2626                                         $ignore = $this->ignoreIndexClause(
2627                                                 implode( ',', (array)$ignore_index[$alias] ) );
2628                                         if ( $ignore != '' ) {
2629                                                 $tableClause .= ' ' . $ignore;
2630                                         }
2631                                 }
2632                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2633                                 if ( $on != '' ) {
2634                                         $tableClause .= ' ON (' . $on . ')';
2635                                 }
2636
2637                                 $retJOIN[] = $tableClause;
2638                         } elseif ( isset( $use_index[$alias] ) ) {
2639                                 // Is there an INDEX clause for this table?
2640                                 $tableClause = $joinedTable;
2641                                 $tableClause .= ' ' . $this->useIndexClause(
2642                                                 implode( ',', (array)$use_index[$alias] )
2643                                         );
2644
2645                                 $ret[] = $tableClause;
2646                         } elseif ( isset( $ignore_index[$alias] ) ) {
2647                                 // Is there an INDEX clause for this table?
2648                                 $tableClause = $joinedTable;
2649                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2650                                                 implode( ',', (array)$ignore_index[$alias] )
2651                                         );
2652
2653                                 $ret[] = $tableClause;
2654                         } else {
2655                                 $tableClause = $joinedTable;
2656
2657                                 $ret[] = $tableClause;
2658                         }
2659                 }
2660
2661                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2662                 $implicitJoins = implode( ',', $ret );
2663                 $explicitJoins = implode( ' ', $retJOIN );
2664
2665                 // Compile our final table clause
2666                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2667         }
2668
2669         /**
2670          * Allows for index remapping in queries where this is not consistent across DBMS
2671          *
2672          * @param string $index
2673          * @return string
2674          */
2675         protected function indexName( $index ) {
2676                 return $this->indexAliases[$index] ?? $index;
2677         }
2678
2679         public function addQuotes( $s ) {
2680                 if ( $s instanceof Blob ) {
2681                         $s = $s->fetch();
2682                 }
2683                 if ( $s === null ) {
2684                         return 'NULL';
2685                 } elseif ( is_bool( $s ) ) {
2686                         return (int)$s;
2687                 } else {
2688                         # This will also quote numeric values. This should be harmless,
2689                         # and protects against weird problems that occur when they really
2690                         # _are_ strings such as article titles and string->number->string
2691                         # conversion is not 1:1.
2692                         return "'" . $this->strencode( $s ) . "'";
2693                 }
2694         }
2695
2696         public function addIdentifierQuotes( $s ) {
2697                 return '"' . str_replace( '"', '""', $s ) . '"';
2698         }
2699
2700         /**
2701          * Returns if the given identifier looks quoted or not according to
2702          * the database convention for quoting identifiers .
2703          *
2704          * @note Do not use this to determine if untrusted input is safe.
2705          *   A malicious user can trick this function.
2706          * @param string $name
2707          * @return bool
2708          */
2709         public function isQuotedIdentifier( $name ) {
2710                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2711         }
2712
2713         /**
2714          * @param string $s
2715          * @param string $escapeChar
2716          * @return string
2717          */
2718         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2719                 return str_replace( [ $escapeChar, '%', '_' ],
2720                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2721                         $s );
2722         }
2723
2724         public function buildLike( $param, ...$params ) {
2725                 if ( is_array( $param ) ) {
2726                         $params = $param;
2727                 } else {
2728                         $params = func_get_args();
2729                 }
2730
2731                 $s = '';
2732
2733                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2734                 // may escape backslashes, creating problems of double escaping. The `
2735                 // character has good cross-DBMS compatibility, avoiding special operators
2736                 // in MS SQL like ^ and %
2737                 $escapeChar = '`';
2738
2739                 foreach ( $params as $value ) {
2740                         if ( $value instanceof LikeMatch ) {
2741                                 $s .= $value->toString();
2742                         } else {
2743                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2744                         }
2745                 }
2746
2747                 return ' LIKE ' .
2748                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2749         }
2750
2751         public function anyChar() {
2752                 return new LikeMatch( '_' );
2753         }
2754
2755         public function anyString() {
2756                 return new LikeMatch( '%' );
2757         }
2758
2759         public function nextSequenceValue( $seqName ) {
2760                 return null;
2761         }
2762
2763         /**
2764          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2765          * is only needed because a) MySQL must be as efficient as possible due to
2766          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2767          * which index to pick. Anyway, other databases might have different
2768          * indexes on a given table. So don't bother overriding this unless you're
2769          * MySQL.
2770          * @param string $index
2771          * @return string
2772          */
2773         public function useIndexClause( $index ) {
2774                 return '';
2775         }
2776
2777         /**
2778          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2779          * is only needed because a) MySQL must be as efficient as possible due to
2780          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2781          * which index to pick. Anyway, other databases might have different
2782          * indexes on a given table. So don't bother overriding this unless you're
2783          * MySQL.
2784          * @param string $index
2785          * @return string
2786          */
2787         public function ignoreIndexClause( $index ) {
2788                 return '';
2789         }
2790
2791         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2792                 if ( count( $rows ) == 0 ) {
2793                         return;
2794                 }
2795
2796                 $uniqueIndexes = (array)$uniqueIndexes;
2797                 // Single row case
2798                 if ( !is_array( reset( $rows ) ) ) {
2799                         $rows = [ $rows ];
2800                 }
2801
2802                 try {
2803                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2804                         $affectedRowCount = 0;
2805                         foreach ( $rows as $row ) {
2806                                 // Delete rows which collide with this one
2807                                 $indexWhereClauses = [];
2808                                 foreach ( $uniqueIndexes as $index ) {
2809                                         $indexColumns = (array)$index;
2810                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2811                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2812                                                 throw new DBUnexpectedError(
2813                                                         $this,
2814                                                         'New record does not provide all values for unique key (' .
2815                                                         implode( ', ', $indexColumns ) . ')'
2816                                                 );
2817                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2818                                                 throw new DBUnexpectedError(
2819                                                         $this,
2820                                                         'New record has a null value for unique key (' .
2821                                                         implode( ', ', $indexColumns ) . ')'
2822                                                 );
2823                                         }
2824                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2825                                 }
2826
2827                                 if ( $indexWhereClauses ) {
2828                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2829                                         $affectedRowCount += $this->affectedRows();
2830                                 }
2831
2832                                 // Now insert the row
2833                                 $this->insert( $table, $row, $fname );
2834                                 $affectedRowCount += $this->affectedRows();
2835                         }
2836                         $this->endAtomic( $fname );
2837                         $this->affectedRowCount = $affectedRowCount;
2838                 } catch ( Exception $e ) {
2839                         $this->cancelAtomic( $fname );
2840                         throw $e;
2841                 }
2842         }
2843
2844         /**
2845          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2846          * statement.
2847          *
2848          * @param string $table Table name
2849          * @param array|string $rows Row(s) to insert
2850          * @param string $fname Caller function name
2851          */
2852         protected function nativeReplace( $table, $rows, $fname ) {
2853                 $table = $this->tableName( $table );
2854
2855                 # Single row case
2856                 if ( !is_array( reset( $rows ) ) ) {
2857                         $rows = [ $rows ];
2858                 }
2859
2860                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2861                 $first = true;
2862
2863                 foreach ( $rows as $row ) {
2864                         if ( $first ) {
2865                                 $first = false;
2866                         } else {
2867                                 $sql .= ',';
2868                         }
2869
2870                         $sql .= '(' . $this->makeList( $row ) . ')';
2871                 }
2872
2873                 $this->query( $sql, $fname );
2874         }
2875
2876         public function upsert( $table, array $rows, $uniqueIndexes, array $set,
2877                 $fname = __METHOD__
2878         ) {
2879                 if ( $rows === [] ) {
2880                         return true; // nothing to do
2881                 }
2882
2883                 $uniqueIndexes = (array)$uniqueIndexes;
2884                 if ( !is_array( reset( $rows ) ) ) {
2885                         $rows = [ $rows ];
2886                 }
2887
2888                 if ( count( $uniqueIndexes ) ) {
2889                         $clauses = []; // list WHERE clauses that each identify a single row
2890                         foreach ( $rows as $row ) {
2891                                 foreach ( $uniqueIndexes as $index ) {
2892                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2893                                         $rowKey = []; // unique key to this row
2894                                         foreach ( $index as $column ) {
2895                                                 $rowKey[$column] = $row[$column];
2896                                         }
2897                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2898                                 }
2899                         }
2900                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2901                 } else {
2902                         $where = false;
2903                 }
2904
2905                 $affectedRowCount = 0;
2906                 try {
2907                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2908                         # Update any existing conflicting row(s)
2909                         if ( $where !== false ) {
2910                                 $this->update( $table, $set, $where, $fname );
2911                                 $affectedRowCount += $this->affectedRows();
2912                         }
2913                         # Now insert any non-conflicting row(s)
2914                         $this->insert( $table, $rows, $fname, [ 'IGNORE' ] );
2915                         $affectedRowCount += $this->affectedRows();
2916                         $this->endAtomic( $fname );
2917                         $this->affectedRowCount = $affectedRowCount;
2918                 } catch ( Exception $e ) {
2919                         $this->cancelAtomic( $fname );
2920                         throw $e;
2921                 }
2922
2923                 return true;
2924         }
2925
2926         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2927                 $fname = __METHOD__
2928         ) {
2929                 if ( !$conds ) {
2930                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2931                 }
2932
2933                 $delTable = $this->tableName( $delTable );
2934                 $joinTable = $this->tableName( $joinTable );
2935                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2936                 if ( $conds != '*' ) {
2937                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2938                 }
2939                 $sql .= ')';
2940
2941                 $this->query( $sql, $fname );
2942         }
2943
2944         public function textFieldSize( $table, $field ) {
2945                 $table = $this->tableName( $table );
2946                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\"";
2947                 $res = $this->query( $sql, __METHOD__ );
2948                 $row = $this->fetchObject( $res );
2949
2950                 $m = [];
2951
2952                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2953                         $size = $m[1];
2954                 } else {
2955                         $size = -1;
2956                 }
2957
2958                 return $size;
2959         }
2960
2961         public function delete( $table, $conds, $fname = __METHOD__ ) {
2962                 if ( !$conds ) {
2963                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2964                 }
2965
2966                 $table = $this->tableName( $table );
2967                 $sql = "DELETE FROM $table";
2968
2969                 if ( $conds != '*' ) {
2970                         if ( is_array( $conds ) ) {
2971                                 $conds = $this->makeList( $conds, self::LIST_AND );
2972                         }
2973                         $sql .= ' WHERE ' . $conds;
2974                 }
2975
2976                 $this->query( $sql, $fname );
2977
2978                 return true;
2979         }
2980
2981         final public function insertSelect(
2982                 $destTable, $srcTable, $varMap, $conds,
2983                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2984         ) {
2985                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2986
2987                 $insertOptions = (array)$insertOptions;
2988                 $selectOptions = (array)$selectOptions;
2989
2990                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2991                         // For massive migrations with downtime, we don't want to select everything
2992                         // into memory and OOM, so do all this native on the server side if possible.
2993                         $this->nativeInsertSelect(
2994                                 $destTable,
2995                                 $srcTable,
2996                                 $varMap,
2997                                 $conds,
2998                                 $fname,
2999                                 array_diff( $insertOptions, $hints ),
3000                                 $selectOptions,
3001                                 $selectJoinConds
3002                         );
3003                 } else {
3004                         $this->nonNativeInsertSelect(
3005                                 $destTable,
3006                                 $srcTable,
3007                                 $varMap,
3008                                 $conds,
3009                                 $fname,
3010                                 array_diff( $insertOptions, $hints ),
3011                                 $selectOptions,
3012                                 $selectJoinConds
3013                         );
3014                 }
3015
3016                 return true;
3017         }
3018
3019         /**
3020          * @param array $insertOptions INSERT options
3021          * @param array $selectOptions SELECT options
3022          * @return bool Whether an INSERT SELECT with these options will be replication safe
3023          * @since 1.31
3024          */
3025         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3026                 return true;
3027         }
3028
3029         /**
3030          * Implementation of insertSelect() based on select() and insert()
3031          *
3032          * @see IDatabase::insertSelect()
3033          * @since 1.30
3034          * @param string $destTable
3035          * @param string|array $srcTable
3036          * @param array $varMap
3037          * @param array $conds
3038          * @param string $fname
3039          * @param array $insertOptions
3040          * @param array $selectOptions
3041          * @param array $selectJoinConds
3042          */
3043         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3044                 $fname = __METHOD__,
3045                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3046         ) {
3047                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3048                 // on only the master (without needing row-based-replication). It also makes it easy to
3049                 // know how big the INSERT is going to be.
3050                 $fields = [];
3051                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3052                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3053                 }
3054                 $selectOptions[] = 'FOR UPDATE';
3055                 $res = $this->select(
3056                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3057                 );
3058                 if ( !$res ) {
3059                         return;
3060                 }
3061
3062                 try {
3063                         $affectedRowCount = 0;
3064                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3065                         $rows = [];
3066                         $ok = true;
3067                         foreach ( $res as $row ) {
3068                                 $rows[] = (array)$row;
3069
3070                                 // Avoid inserts that are too huge
3071                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3072                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3073                                         if ( !$ok ) {
3074                                                 break;
3075                                         }
3076                                         $affectedRowCount += $this->affectedRows();
3077                                         $rows = [];
3078                                 }
3079                         }
3080                         if ( $rows && $ok ) {
3081                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3082                                 if ( $ok ) {
3083                                         $affectedRowCount += $this->affectedRows();
3084                                 }
3085                         }
3086                         if ( $ok ) {
3087                                 $this->endAtomic( $fname );
3088                                 $this->affectedRowCount = $affectedRowCount;
3089                         } else {
3090                                 $this->cancelAtomic( $fname );
3091                         }
3092                 } catch ( Exception $e ) {
3093                         $this->cancelAtomic( $fname );
3094                         throw $e;
3095                 }
3096         }
3097
3098         /**
3099          * Native server-side implementation of insertSelect() for situations where
3100          * we don't want to select everything into memory
3101          *
3102          * @see IDatabase::insertSelect()
3103          * @param string $destTable
3104          * @param string|array $srcTable
3105          * @param array $varMap
3106          * @param array $conds
3107          * @param string $fname
3108          * @param array $insertOptions
3109          * @param array $selectOptions
3110          * @param array $selectJoinConds
3111          */
3112         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3113                 $fname = __METHOD__,
3114                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3115         ) {
3116                 $destTable = $this->tableName( $destTable );
3117
3118                 if ( !is_array( $insertOptions ) ) {
3119                         $insertOptions = [ $insertOptions ];
3120                 }
3121
3122                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3123
3124                 $selectSql = $this->selectSQLText(
3125                         $srcTable,
3126                         array_values( $varMap ),
3127                         $conds,
3128                         $fname,
3129                         $selectOptions,
3130                         $selectJoinConds
3131                 );
3132
3133                 $sql = "INSERT $insertOptions" .
3134                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3135                         $selectSql;
3136
3137                 $this->query( $sql, $fname );
3138         }
3139
3140         public function limitResult( $sql, $limit, $offset = false ) {
3141                 if ( !is_numeric( $limit ) ) {
3142                         throw new DBUnexpectedError( $this,
3143                                 "Invalid non-numeric limit passed to limitResult()\n" );
3144                 }
3145                 // This version works in MySQL and SQLite. It will very likely need to be
3146                 // overridden for most other RDBMS subclasses.
3147                 return "$sql LIMIT "
3148                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3149                         . "{$limit} ";
3150         }
3151
3152         public function unionSupportsOrderAndLimit() {
3153                 return true; // True for almost every DB supported
3154         }
3155
3156         public function unionQueries( $sqls, $all ) {
3157                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3158
3159                 return '(' . implode( $glue, $sqls ) . ')';
3160         }
3161
3162         public function unionConditionPermutations(
3163                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3164                 $options = [], $join_conds = []
3165         ) {
3166                 // First, build the Cartesian product of $permute_conds
3167                 $conds = [ [] ];
3168                 foreach ( $permute_conds as $field => $values ) {
3169                         if ( !$values ) {
3170                                 // Skip empty $values
3171                                 continue;
3172                         }
3173                         $values = array_unique( $values ); // For sanity
3174                         $newConds = [];
3175                         foreach ( $conds as $cond ) {
3176                                 foreach ( $values as $value ) {
3177                                         $cond[$field] = $value;
3178                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3179                                 }
3180                         }
3181                         $conds = $newConds;
3182                 }
3183
3184                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3185
3186                 // If there's just one condition and no subordering, hand off to
3187                 // selectSQLText directly.
3188                 if ( count( $conds ) === 1 &&
3189                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3190                 ) {
3191                         return $this->selectSQLText(
3192                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3193                         );
3194                 }
3195
3196                 // Otherwise, we need to pull out the order and limit to apply after
3197                 // the union. Then build the SQL queries for each set of conditions in
3198                 // $conds. Then union them together (using UNION ALL, because the
3199                 // product *should* already be distinct).
3200                 $orderBy = $this->makeOrderBy( $options );
3201                 $limit = $options['LIMIT'] ?? null;
3202                 $offset = $options['OFFSET'] ?? false;
3203                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3204                 if ( !$this->unionSupportsOrderAndLimit() ) {
3205                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3206                 } else {
3207                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3208                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3209                         }
3210                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3211                                 // We need to increase the limit by the offset rather than
3212                                 // using the offset directly, otherwise it'll skip incorrectly
3213                                 // in the subqueries.
3214                                 $options['LIMIT'] = $limit + $offset;
3215                                 unset( $options['OFFSET'] );
3216                         }
3217                 }
3218
3219                 $sqls = [];
3220                 foreach ( $conds as $cond ) {
3221                         $sqls[] = $this->selectSQLText(
3222                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3223                         );
3224                 }
3225                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3226                 if ( $limit !== null ) {
3227                         $sql = $this->limitResult( $sql, $limit, $offset );
3228                 }
3229
3230                 return $sql;
3231         }
3232
3233         public function conditional( $cond, $trueVal, $falseVal ) {
3234                 if ( is_array( $cond ) ) {
3235                         $cond = $this->makeList( $cond, self::LIST_AND );
3236                 }
3237
3238                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3239         }
3240
3241         public function strreplace( $orig, $old, $new ) {
3242                 return "REPLACE({$orig}, {$old}, {$new})";
3243         }
3244
3245         public function getServerUptime() {
3246                 return 0;
3247         }
3248
3249         public function wasDeadlock() {
3250                 return false;
3251         }
3252
3253         public function wasLockTimeout() {
3254                 return false;
3255         }
3256
3257         public function wasConnectionLoss() {
3258                 return $this->wasConnectionError( $this->lastErrno() );
3259         }
3260
3261         public function wasReadOnlyError() {
3262                 return false;
3263         }
3264
3265         public function wasErrorReissuable() {
3266                 return (
3267                         $this->wasDeadlock() ||
3268                         $this->wasLockTimeout() ||
3269                         $this->wasConnectionLoss()
3270                 );
3271         }
3272
3273         /**
3274          * Do not use this method outside of Database/DBError classes
3275          *
3276          * @param int|string $errno
3277          * @return bool Whether the given query error was a connection drop
3278          */
3279         public function wasConnectionError( $errno ) {
3280                 return false;
3281         }
3282
3283         /**
3284          * @return bool Whether it is known that the last query error only caused statement rollback
3285          * @note This is for backwards compatibility for callers catching DBError exceptions in
3286          *   order to ignore problems like duplicate key errors or foriegn key violations
3287          * @since 1.31
3288          */
3289         protected function wasKnownStatementRollbackError() {
3290                 return false; // don't know; it could have caused a transaction rollback
3291         }
3292
3293         public function deadlockLoop() {
3294                 $args = func_get_args();
3295                 $function = array_shift( $args );
3296                 $tries = self::$DEADLOCK_TRIES;
3297
3298                 $this->begin( __METHOD__ );
3299
3300                 $retVal = null;
3301                 /** @var Exception $e */
3302                 $e = null;
3303                 do {
3304                         try {
3305                                 $retVal = $function( ...$args );
3306                                 break;
3307                         } catch ( DBQueryError $e ) {
3308                                 if ( $this->wasDeadlock() ) {
3309                                         // Retry after a randomized delay
3310                                         usleep( mt_rand( self::$DEADLOCK_DELAY_MIN, self::$DEADLOCK_DELAY_MAX ) );
3311                                 } else {
3312                                         // Throw the error back up
3313                                         throw $e;
3314                                 }
3315                         }
3316                 } while ( --$tries > 0 );
3317
3318                 if ( $tries <= 0 ) {
3319                         // Too many deadlocks; give up
3320                         $this->rollback( __METHOD__ );
3321                         throw $e;
3322                 } else {
3323                         $this->commit( __METHOD__ );
3324
3325                         return $retVal;
3326                 }
3327         }
3328
3329         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3330                 # Real waits are implemented in the subclass.
3331                 return 0;
3332         }
3333
3334         public function getReplicaPos() {
3335                 # Stub
3336                 return false;
3337         }
3338
3339         public function getMasterPos() {
3340                 # Stub
3341                 return false;
3342         }
3343
3344         public function serverIsReadOnly() {
3345                 return false;
3346         }
3347
3348         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3349                 if ( !$this->trxLevel() ) {
3350                         throw new DBUnexpectedError( $this, "No transaction is active." );
3351                 }
3352                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3353         }
3354
3355         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3356                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3357                         // Start an implicit transaction similar to how query() does
3358                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3359                         $this->trxAutomatic = true;
3360                 }
3361
3362                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3363                 if ( !$this->trxLevel() ) {
3364                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3365                 }
3366         }
3367
3368         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3369                 $this->onTransactionCommitOrIdle( $callback, $fname );
3370         }
3371
3372         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3373                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3374                         // Start an implicit transaction similar to how query() does
3375                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3376                         $this->trxAutomatic = true;
3377                 }
3378
3379                 if ( $this->trxLevel() ) {
3380                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3381                 } else {
3382                         // No transaction is active nor will start implicitly, so make one for this callback
3383                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3384                         try {
3385                                 $callback( $this );
3386                                 $this->endAtomic( __METHOD__ );
3387                         } catch ( Exception $e ) {
3388                                 $this->cancelAtomic( __METHOD__ );
3389                                 throw $e;
3390                         }
3391                 }
3392         }
3393
3394         final public function onAtomicSectionCancel( callable $callback, $fname = __METHOD__ ) {
3395                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3396                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3397                 }
3398                 $this->trxSectionCancelCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3399         }
3400
3401         /**
3402          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3403          */
3404         private function currentAtomicSectionId() {
3405                 if ( $this->trxLevel() && $this->trxAtomicLevels ) {
3406                         $levelInfo = end( $this->trxAtomicLevels );
3407
3408                         return $levelInfo[1];
3409                 }
3410
3411                 return null;
3412         }
3413
3414         /**
3415          * Hoist callback ownership for callbacks in a section to a parent section.
3416          * All callbacks should have an owner that is present in trxAtomicLevels.
3417          * @param AtomicSectionIdentifier $old
3418          * @param AtomicSectionIdentifier $new
3419          */
3420         private function reassignCallbacksForSection(
3421                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3422         ) {
3423                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3424                         if ( $info[2] === $old ) {
3425                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3426                         }
3427                 }
3428                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3429                         if ( $info[2] === $old ) {
3430                                 $this->trxIdleCallbacks[$key][2] = $new;
3431                         }
3432                 }
3433                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3434                         if ( $info[2] === $old ) {
3435                                 $this->trxEndCallbacks[$key][2] = $new;
3436                         }
3437                 }
3438                 foreach ( $this->trxSectionCancelCallbacks as $key => $info ) {
3439                         if ( $info[2] === $old ) {
3440                                 $this->trxSectionCancelCallbacks[$key][2] = $new;
3441                         }
3442                 }
3443         }
3444
3445         /**
3446          * Update callbacks that were owned by cancelled atomic sections.
3447          *
3448          * Callbacks for "on commit" should never be run if they're owned by a
3449          * section that won't be committed.
3450          *
3451          * Callbacks for "on resolution" need to reflect that the section was
3452          * rolled back, even if the transaction as a whole commits successfully.
3453          *
3454          * Callbacks for "on section cancel" should already have been consumed,
3455          * but errors during the cancellation itself can prevent that while still
3456          * destroying the section. Hoist any such callbacks to the new top section,
3457          * which we assume will itself have to be cancelled or rolled back to
3458          * resolve the error.
3459          *
3460          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3461          * @param AtomicSectionIdentifier|null $newSectionId New top section ID.
3462          * @throws UnexpectedValueException
3463          */
3464         private function modifyCallbacksForCancel(
3465                 array $sectionIds, AtomicSectionIdentifier $newSectionId = null
3466         ) {
3467                 // Cancel the "on commit" callbacks owned by this savepoint
3468                 $this->trxIdleCallbacks = array_filter(
3469                         $this->trxIdleCallbacks,
3470                         function ( $entry ) use ( $sectionIds ) {
3471                                 return !in_array( $entry[2], $sectionIds, true );
3472                         }
3473                 );
3474                 $this->trxPreCommitCallbacks = array_filter(
3475                         $this->trxPreCommitCallbacks,
3476                         function ( $entry ) use ( $sectionIds ) {
3477                                 return !in_array( $entry[2], $sectionIds, true );
3478                         }
3479                 );
3480                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3481                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3482                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3483                                 $callback = $entry[0];
3484                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3485                                         // @phan-suppress-next-line PhanInfiniteRecursion No recursion at all here, phan is confused
3486                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3487                                 };
3488                                 // This "on resolution" callback no longer belongs to a section.
3489                                 $this->trxEndCallbacks[$key][2] = null;
3490                         }
3491                 }
3492                 // Hoist callback ownership for section cancel callbacks to the new top section
3493                 foreach ( $this->trxSectionCancelCallbacks as $key => $entry ) {
3494                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3495                                 $this->trxSectionCancelCallbacks[$key][2] = $newSectionId;
3496                         }
3497                 }
3498         }
3499
3500         final public function setTransactionListener( $name, callable $callback = null ) {
3501                 if ( $callback ) {
3502                         $this->trxRecurringCallbacks[$name] = $callback;
3503                 } else {
3504                         unset( $this->trxRecurringCallbacks[$name] );
3505                 }
3506         }
3507
3508         /**
3509          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3510          *
3511          * This method should not be used outside of Database/LoadBalancer
3512          *
3513          * @param bool $suppress
3514          * @since 1.28
3515          */
3516         final public function setTrxEndCallbackSuppression( $suppress ) {
3517                 $this->trxEndCallbacksSuppressed = $suppress;
3518         }
3519
3520         /**
3521          * Actually consume and run any "on transaction idle/resolution" callbacks.
3522          *
3523          * This method should not be used outside of Database/LoadBalancer
3524          *
3525          * @param int $trigger IDatabase::TRIGGER_* constant
3526          * @return int Number of callbacks attempted
3527          * @since 1.20
3528          * @throws Exception
3529          */
3530         public function runOnTransactionIdleCallbacks( $trigger ) {
3531                 if ( $this->trxLevel() ) { // sanity
3532                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3533                 }
3534
3535                 if ( $this->trxEndCallbacksSuppressed ) {
3536                         return 0;
3537                 }
3538
3539                 $count = 0;
3540                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3541                 /** @var Exception $e */
3542                 $e = null; // first exception
3543                 do { // callbacks may add callbacks :)
3544                         $callbacks = array_merge(
3545                                 $this->trxIdleCallbacks,
3546                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3547                         );
3548                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3549                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3550
3551                         // Only run trxSectionCancelCallbacks on rollback, not commit.
3552                         // But always consume them.
3553                         if ( $trigger === self::TRIGGER_ROLLBACK ) {
3554                                 $callbacks = array_merge( $callbacks, $this->trxSectionCancelCallbacks );
3555                         }
3556                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3557
3558                         foreach ( $callbacks as $callback ) {
3559                                 ++$count;
3560                                 list( $phpCallback ) = $callback;
3561                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3562                                 try {
3563                                         // @phan-suppress-next-line PhanParamTooManyCallable
3564                                         call_user_func( $phpCallback, $trigger, $this );
3565                                 } catch ( Exception $ex ) {
3566                                         call_user_func( $this->errorLogger, $ex );
3567                                         $e = $e ?: $ex;
3568                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3569                                         // their transactions are ended so other callbacks don't fail
3570                                         if ( $this->trxLevel() ) {
3571                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3572                                         }
3573                                 } finally {
3574                                         if ( $autoTrx ) {
3575                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3576                                         } else {
3577                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3578                                         }
3579                                 }
3580                         }
3581                 } while ( count( $this->trxIdleCallbacks ) );
3582
3583                 if ( $e instanceof Exception ) {
3584                         throw $e; // re-throw any first exception
3585                 }
3586
3587                 return $count;
3588         }
3589
3590         /**
3591          * Actually consume and run any "on transaction pre-commit" callbacks.
3592          *
3593          * This method should not be used outside of Database/LoadBalancer
3594          *
3595          * @since 1.22
3596          * @return int Number of callbacks attempted
3597          * @throws Exception
3598          */
3599         public function runOnTransactionPreCommitCallbacks() {
3600                 $count = 0;
3601
3602                 $e = null; // first exception
3603                 do { // callbacks may add callbacks :)
3604                         $callbacks = $this->trxPreCommitCallbacks;
3605                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3606                         foreach ( $callbacks as $callback ) {
3607                                 try {
3608                                         ++$count;
3609                                         list( $phpCallback ) = $callback;
3610                                         $phpCallback( $this );
3611                                 } catch ( Exception $ex ) {
3612                                         ( $this->errorLogger )( $ex );
3613                                         $e = $e ?: $ex;
3614                                 }
3615                         }
3616                 } while ( count( $this->trxPreCommitCallbacks ) );
3617
3618                 if ( $e instanceof Exception ) {
3619                         throw $e; // re-throw any first exception
3620                 }
3621
3622                 return $count;
3623         }
3624
3625         /**
3626          * Actually run any "atomic section cancel" callbacks.
3627          *
3628          * @param int $trigger IDatabase::TRIGGER_* constant
3629          * @param AtomicSectionIdentifier[]|null $sectionIds Section IDs to cancel,
3630          *  null on transaction rollback
3631          */
3632         private function runOnAtomicSectionCancelCallbacks(
3633                 $trigger, array $sectionIds = null
3634         ) {
3635                 /** @var Exception|Throwable $e */
3636                 $e = null; // first exception
3637
3638                 $notCancelled = [];
3639                 do {
3640                         $callbacks = $this->trxSectionCancelCallbacks;
3641                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3642                         foreach ( $callbacks as $entry ) {
3643                                 if ( $sectionIds === null || in_array( $entry[2], $sectionIds, true ) ) {
3644                                         try {
3645                                                 $entry[0]( $trigger, $this );
3646                                         } catch ( Exception $ex ) {
3647                                                 ( $this->errorLogger )( $ex );
3648                                                 $e = $e ?: $ex;
3649                                         } catch ( Throwable $ex ) {
3650                                                 // @todo: Log?
3651                                                 $e = $e ?: $ex;
3652                                         }
3653                                 } else {
3654                                         $notCancelled[] = $entry;
3655                                 }
3656                         }
3657                 } while ( count( $this->trxSectionCancelCallbacks ) );
3658                 $this->trxSectionCancelCallbacks = $notCancelled;
3659
3660                 if ( $e !== null ) {
3661                         throw $e; // re-throw any first Exception/Throwable
3662                 }
3663         }
3664
3665         /**
3666          * Actually run any "transaction listener" callbacks.
3667          *
3668          * This method should not be used outside of Database/LoadBalancer
3669          *
3670          * @param int $trigger IDatabase::TRIGGER_* constant
3671          * @throws Exception
3672          * @since 1.20
3673          */
3674         public function runTransactionListenerCallbacks( $trigger ) {
3675                 if ( $this->trxEndCallbacksSuppressed ) {
3676                         return;
3677                 }
3678
3679                 /** @var Exception $e */
3680                 $e = null; // first exception
3681
3682                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3683                         try {
3684                                 $phpCallback( $trigger, $this );
3685                         } catch ( Exception $ex ) {
3686                                 ( $this->errorLogger )( $ex );
3687                                 $e = $e ?: $ex;
3688                         }
3689                 }
3690
3691                 if ( $e instanceof Exception ) {
3692                         throw $e; // re-throw any first exception
3693                 }
3694         }
3695
3696         /**
3697          * Create a savepoint
3698          *
3699          * This is used internally to implement atomic sections. It should not be
3700          * used otherwise.
3701          *
3702          * @since 1.31
3703          * @param string $identifier Identifier for the savepoint
3704          * @param string $fname Calling function name
3705          */
3706         protected function doSavepoint( $identifier, $fname ) {
3707                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3708         }
3709
3710         /**
3711          * Release a savepoint
3712          *
3713          * This is used internally to implement atomic sections. It should not be
3714          * used otherwise.
3715          *
3716          * @since 1.31
3717          * @param string $identifier Identifier for the savepoint
3718          * @param string $fname Calling function name
3719          */
3720         protected function doReleaseSavepoint( $identifier, $fname ) {
3721                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3722         }
3723
3724         /**
3725          * Rollback to a savepoint
3726          *
3727          * This is used internally to implement atomic sections. It should not be
3728          * used otherwise.
3729          *
3730          * @since 1.31
3731          * @param string $identifier Identifier for the savepoint
3732          * @param string $fname Calling function name
3733          */
3734         protected function doRollbackToSavepoint( $identifier, $fname ) {
3735                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3736         }
3737
3738         /**
3739          * @param string $fname
3740          * @return string
3741          */
3742         private function nextSavepointId( $fname ) {
3743                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3744                 if ( strlen( $savepointId ) > 30 ) {
3745                         // 30 == Oracle's identifier length limit (pre 12c)
3746                         // With a 22 character prefix, that puts the highest number at 99999999.
3747                         throw new DBUnexpectedError(
3748                                 $this,
3749                                 'There have been an excessively large number of atomic sections in a transaction'
3750                                 . " started by $this->trxFname (at $fname)"
3751                         );
3752                 }
3753
3754                 return $savepointId;
3755         }
3756
3757         final public function startAtomic(
3758                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3759         ) {
3760                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3761
3762                 if ( !$this->trxLevel() ) {
3763                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3764                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3765                         // in all changes being in one transaction to keep requests transactional.
3766                         if ( $this->getFlag( self::DBO_TRX ) ) {
3767                                 // Since writes could happen in between the topmost atomic sections as part
3768                                 // of the transaction, those sections will need savepoints.
3769                                 $savepointId = $this->nextSavepointId( $fname );
3770                                 $this->doSavepoint( $savepointId, $fname );
3771                         } else {
3772                                 $this->trxAutomaticAtomic = true;
3773                         }
3774                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3775                         $savepointId = $this->nextSavepointId( $fname );
3776                         $this->doSavepoint( $savepointId, $fname );
3777                 }
3778
3779                 $sectionId = new AtomicSectionIdentifier;
3780                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3781                 $this->queryLogger->debug( 'startAtomic: entering level ' .
3782                         ( count( $this->trxAtomicLevels ) - 1 ) . " ($fname)" );
3783
3784                 return $sectionId;
3785         }
3786
3787         final public function endAtomic( $fname = __METHOD__ ) {
3788                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3789                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3790                 }
3791
3792                 // Check if the current section matches $fname
3793                 $pos = count( $this->trxAtomicLevels ) - 1;
3794                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3795                 $this->queryLogger->debug( "endAtomic: leaving level $pos ($fname)" );
3796
3797                 if ( $savedFname !== $fname ) {
3798                         throw new DBUnexpectedError(
3799                                 $this,
3800                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3801                         );
3802                 }
3803
3804                 // Remove the last section (no need to re-index the array)
3805                 array_pop( $this->trxAtomicLevels );
3806
3807                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3808                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3809                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3810                         $this->doReleaseSavepoint( $savepointId, $fname );
3811                 }
3812
3813                 // Hoist callback ownership for callbacks in the section that just ended;
3814                 // all callbacks should have an owner that is present in trxAtomicLevels.
3815                 $currentSectionId = $this->currentAtomicSectionId();
3816                 if ( $currentSectionId ) {
3817                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3818                 }
3819         }
3820
3821         final public function cancelAtomic(
3822                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3823         ) {
3824                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3825                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3826                 }
3827
3828                 $excisedIds = [];
3829                 $newTopSection = $this->currentAtomicSectionId();
3830                 try {
3831                         $excisedFnames = [];
3832                         if ( $sectionId !== null ) {
3833                                 // Find the (last) section with the given $sectionId
3834                                 $pos = -1;
3835                                 foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3836                                         if ( $asId === $sectionId ) {
3837                                                 $pos = $i;
3838                                         }
3839                                 }
3840                                 if ( $pos < 0 ) {
3841                                         throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
3842                                 }
3843                                 // Remove all descendant sections and re-index the array
3844                                 $len = count( $this->trxAtomicLevels );
3845                                 for ( $i = $pos + 1; $i < $len; ++$i ) {
3846                                         $excisedFnames[] = $this->trxAtomicLevels[$i][0];
3847                                         $excisedIds[] = $this->trxAtomicLevels[$i][1];
3848                                 }
3849                                 $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3850                                 $newTopSection = $this->currentAtomicSectionId();
3851                         }
3852
3853                         // Check if the current section matches $fname
3854                         $pos = count( $this->trxAtomicLevels ) - 1;
3855                         list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3856
3857                         if ( $excisedFnames ) {
3858                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
3859                                         "and descendants " . implode( ', ', $excisedFnames ) );
3860                         } else {
3861                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
3862                         }
3863
3864                         if ( $savedFname !== $fname ) {
3865                                 throw new DBUnexpectedError(
3866                                         $this,
3867                                         "Invalid atomic section ended (got $fname but expected $savedFname)."
3868                                 );
3869                         }
3870
3871                         // Remove the last section (no need to re-index the array)
3872                         array_pop( $this->trxAtomicLevels );
3873                         $excisedIds[] = $savedSectionId;
3874                         $newTopSection = $this->currentAtomicSectionId();
3875
3876                         if ( $savepointId !== null ) {
3877                                 // Rollback the transaction to the state just before this atomic section
3878                                 if ( $savepointId === self::$NOT_APPLICABLE ) {
3879                                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
3880                                         // Note: rollback() will run trxSectionCancelCallbacks
3881                                 } else {
3882                                         $this->doRollbackToSavepoint( $savepointId, $fname );
3883                                         $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3884                                         $this->trxStatusIgnoredCause = null;
3885
3886                                         // Run trxSectionCancelCallbacks now.
3887                                         $this->runOnAtomicSectionCancelCallbacks( self::TRIGGER_CANCEL, $excisedIds );
3888                                 }
3889                         } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3890                                 // Put the transaction into an error state if it's not already in one
3891                                 $this->trxStatus = self::STATUS_TRX_ERROR;
3892                                 $this->trxStatusCause = new DBUnexpectedError(
3893                                         $this,
3894                                         "Uncancelable atomic section canceled (got $fname)."
3895                                 );
3896                         }
3897                 } finally {
3898                         // Fix up callbacks owned by the sections that were just cancelled.
3899                         // All callbacks should have an owner that is present in trxAtomicLevels.
3900                         $this->modifyCallbacksForCancel( $excisedIds, $newTopSection );
3901                 }
3902
3903                 $this->affectedRowCount = 0; // for the sake of consistency
3904         }
3905
3906         final public function doAtomicSection(
3907                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3908         ) {
3909                 $sectionId = $this->startAtomic( $fname, $cancelable );
3910                 try {
3911                         $res = $callback( $this, $fname );
3912                 } catch ( Exception $e ) {
3913                         $this->cancelAtomic( $fname, $sectionId );
3914
3915                         throw $e;
3916                 }
3917                 $this->endAtomic( $fname );
3918
3919                 return $res;
3920         }
3921
3922         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3923                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3924                 if ( !in_array( $mode, $modes, true ) ) {
3925                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3926                 }
3927
3928                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3929                 if ( $this->trxLevel() ) {
3930                         if ( $this->trxAtomicLevels ) {
3931                                 $levels = $this->flatAtomicSectionList();
3932                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3933                                 throw new DBUnexpectedError( $this, $msg );
3934                         } elseif ( !$this->trxAutomatic ) {
3935                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3936                                 throw new DBUnexpectedError( $this, $msg );
3937                         } else {
3938                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3939                                 throw new DBUnexpectedError( $this, $msg );
3940                         }
3941                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3942                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3943                         throw new DBUnexpectedError( $this, $msg );
3944                 }
3945
3946                 $this->assertHasConnectionHandle();
3947
3948                 $this->doBegin( $fname );
3949                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3950                 $this->trxStatus = self::STATUS_TRX_OK;
3951                 $this->trxStatusIgnoredCause = null;
3952                 $this->trxAtomicCounter = 0;
3953                 $this->trxTimestamp = microtime( true );
3954                 $this->trxFname = $fname;
3955                 $this->trxDoneWrites = false;
3956                 $this->trxAutomaticAtomic = false;
3957                 $this->trxAtomicLevels = [];
3958                 $this->trxWriteDuration = 0.0;
3959                 $this->trxWriteQueryCount = 0;
3960                 $this->trxWriteAffectedRows = 0;
3961                 $this->trxWriteAdjDuration = 0.0;
3962                 $this->trxWriteAdjQueryCount = 0;
3963                 $this->trxWriteCallers = [];
3964                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3965                 // Get an estimate of the replication lag before any such queries.
3966                 $this->trxReplicaLag = null; // clear cached value first
3967                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3968                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3969                 // caller will think its OK to muck around with the transaction just because startAtomic()
3970                 // has not yet completed (e.g. setting trxAtomicLevels).
3971                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3972         }
3973
3974         /**
3975          * Issues the BEGIN command to the database server.
3976          *
3977          * @see Database::begin()
3978          * @param string $fname
3979          * @throws DBError
3980          */
3981         protected function doBegin( $fname ) {
3982                 $this->query( 'BEGIN', $fname );
3983         }
3984
3985         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3986                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3987                 if ( !in_array( $flush, $modes, true ) ) {
3988                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3989                 }
3990
3991                 if ( $this->trxLevel() && $this->trxAtomicLevels ) {
3992                         // There are still atomic sections open; this cannot be ignored
3993                         $levels = $this->flatAtomicSectionList();
3994                         throw new DBUnexpectedError(
3995                                 $this,
3996                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3997                         );
3998                 }
3999
4000                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
4001                         if ( !$this->trxLevel() ) {
4002                                 return; // nothing to do
4003                         } elseif ( !$this->trxAutomatic ) {
4004                                 throw new DBUnexpectedError(
4005                                         $this,
4006                                         "$fname: Flushing an explicit transaction, getting out of sync."
4007                                 );
4008                         }
4009                 } elseif ( !$this->trxLevel() ) {
4010                         $this->queryLogger->error(
4011                                 "$fname: No transaction to commit, something got out of sync." );
4012                         return; // nothing to do
4013                 } elseif ( $this->trxAutomatic ) {
4014                         throw new DBUnexpectedError(
4015                                 $this,
4016                                 "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
4017                         );
4018                 }
4019
4020                 $this->assertHasConnectionHandle();
4021
4022                 $this->runOnTransactionPreCommitCallbacks();
4023
4024                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
4025                 $this->doCommit( $fname );
4026                 $oldTrxShortId = $this->consumeTrxShortId();
4027                 $this->trxStatus = self::STATUS_TRX_NONE;
4028
4029                 if ( $this->trxDoneWrites ) {
4030                         $this->lastWriteTime = microtime( true );
4031                         $this->trxProfiler->transactionWritingOut(
4032                                 $this->server,
4033                                 $this->getDomainID(),
4034                                 $oldTrxShortId,
4035                                 $writeTime,
4036                                 $this->trxWriteAffectedRows
4037                         );
4038                 }
4039
4040                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4041                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
4042                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
4043                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
4044                 }
4045         }
4046
4047         /**
4048          * Issues the COMMIT command to the database server.
4049          *
4050          * @see Database::commit()
4051          * @param string $fname
4052          * @throws DBError
4053          */
4054         protected function doCommit( $fname ) {
4055                 if ( $this->trxLevel() ) {
4056                         $this->query( 'COMMIT', $fname );
4057                 }
4058         }
4059
4060         final public function rollback( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4061                 $trxActive = $this->trxLevel();
4062
4063                 if ( $flush !== self::FLUSHING_INTERNAL
4064                         && $flush !== self::FLUSHING_ALL_PEERS
4065                         && $this->getFlag( self::DBO_TRX )
4066                 ) {
4067                         throw new DBUnexpectedError(
4068                                 $this,
4069                                 "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
4070                         );
4071                 }
4072
4073                 if ( $trxActive ) {
4074                         $this->assertHasConnectionHandle();
4075
4076                         $this->doRollback( $fname );
4077                         $oldTrxShortId = $this->consumeTrxShortId();
4078                         $this->trxStatus = self::STATUS_TRX_NONE;
4079                         $this->trxAtomicLevels = [];
4080                         // Estimate the RTT via a query now that trxStatus is OK
4081                         $writeTime = $this->pingAndCalculateLastTrxApplyTime();
4082
4083                         if ( $this->trxDoneWrites ) {
4084                                 $this->trxProfiler->transactionWritingOut(
4085                                         $this->server,
4086                                         $this->getDomainID(),
4087                                         $oldTrxShortId,
4088                                         $writeTime,
4089                                         $this->trxWriteAffectedRows
4090                                 );
4091                         }
4092                 }
4093
4094                 // Clear any commit-dependant callbacks. They might even be present
4095                 // only due to transaction rounds, with no SQL transaction being active
4096                 $this->trxIdleCallbacks = [];
4097                 $this->trxPreCommitCallbacks = [];
4098
4099                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4100                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
4101                         try {
4102                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
4103                         } catch ( Exception $e ) {
4104                                 // already logged; finish and let LoadBalancer move on during mass-rollback
4105                         }
4106                         try {
4107                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
4108                         } catch ( Exception $e ) {
4109                                 // already logged; let LoadBalancer move on during mass-rollback
4110                         }
4111
4112                         $this->affectedRowCount = 0; // for the sake of consistency
4113                 }
4114         }
4115
4116         /**
4117          * Issues the ROLLBACK command to the database server.
4118          *
4119          * @see Database::rollback()
4120          * @param string $fname
4121          * @throws DBError
4122          */
4123         protected function doRollback( $fname ) {
4124                 if ( $this->trxLevel() ) {
4125                         # Disconnects cause rollback anyway, so ignore those errors
4126                         $ignoreErrors = true;
4127                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
4128                 }
4129         }
4130
4131         public function flushSnapshot( $fname = __METHOD__ ) {
4132                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
4133                         // This only flushes transactions to clear snapshots, not to write data
4134                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4135                         throw new DBUnexpectedError(
4136                                 $this,
4137                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
4138                         );
4139                 }
4140
4141                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4142         }
4143
4144         public function explicitTrxActive() {
4145                 return $this->trxLevel() && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4146         }
4147
4148         public function duplicateTableStructure(
4149                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4150         ) {
4151                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4152         }
4153
4154         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4155                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4156         }
4157
4158         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4159                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4160         }
4161
4162         public function timestamp( $ts = 0 ) {
4163                 $t = new ConvertibleTimestamp( $ts );
4164                 // Let errors bubble up to avoid putting garbage in the DB
4165                 return $t->getTimestamp( TS_MW );
4166         }
4167
4168         public function timestampOrNull( $ts = null ) {
4169                 if ( is_null( $ts ) ) {
4170                         return null;
4171                 } else {
4172                         return $this->timestamp( $ts );
4173                 }
4174         }
4175
4176         public function affectedRows() {
4177                 return ( $this->affectedRowCount === null )
4178                         ? $this->fetchAffectedRowCount() // default to driver value
4179                         : $this->affectedRowCount;
4180         }
4181
4182         /**
4183          * @return int Number of retrieved rows according to the driver
4184          */
4185         abstract protected function fetchAffectedRowCount();
4186
4187         /**
4188          * Take a query result and wrap it in an iterable result wrapper if necessary.
4189          * Booleans are passed through as-is to indicate success/failure of write queries.
4190          *
4191          * Once upon a time, Database::query() returned a bare MySQL result
4192          * resource, and it was necessary to call this function to convert it to
4193          * a wrapper. Nowadays, raw database objects are never exposed to external
4194          * callers, so this is unnecessary in external code.
4195          *
4196          * @param bool|IResultWrapper|resource $result
4197          * @return bool|IResultWrapper
4198          */
4199         protected function resultObject( $result ) {
4200                 if ( !$result ) {
4201                         return false; // failed query
4202                 } elseif ( $result instanceof IResultWrapper ) {
4203                         return $result;
4204                 } elseif ( $result === true ) {
4205                         return $result; // succesful write query
4206                 } else {
4207                         return new ResultWrapper( $this, $result );
4208                 }
4209         }
4210
4211         public function ping( &$rtt = null ) {
4212                 // Avoid hitting the server if it was hit recently
4213                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::$PING_TTL ) {
4214                         if ( !func_num_args() || $this->lastRoundTripEstimate > 0 ) {
4215                                 $rtt = $this->lastRoundTripEstimate;
4216                                 return true; // don't care about $rtt
4217                         }
4218                 }
4219
4220                 // This will reconnect if possible or return false if not
4221                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4222                 $ok = ( $this->query( self::$PING_QUERY, __METHOD__, true ) !== false );
4223                 $this->restoreFlags( self::RESTORE_PRIOR );
4224
4225                 if ( $ok ) {
4226                         $rtt = $this->lastRoundTripEstimate;
4227                 }
4228
4229                 return $ok;
4230         }
4231
4232         /**
4233          * Close any existing (dead) database connection and open a new connection
4234          *
4235          * @param string $fname
4236          * @return bool True if new connection is opened successfully, false if error
4237          */
4238         protected function replaceLostConnection( $fname ) {
4239                 $this->closeConnection();
4240                 $this->conn = false;
4241
4242                 $this->handleSessionLossPreconnect();
4243
4244                 try {
4245                         $this->open(
4246                                 $this->server,
4247                                 $this->user,
4248                                 $this->password,
4249                                 $this->getDBname(),
4250                                 $this->dbSchema(),
4251                                 $this->tablePrefix()
4252                         );
4253                         $this->lastPing = microtime( true );
4254                         $ok = true;
4255
4256                         $this->connLogger->warning(
4257                                 $fname . ': lost connection to {dbserver}; reconnected',
4258                                 [
4259                                         'dbserver' => $this->getServer(),
4260                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4261                                 ]
4262                         );
4263                 } catch ( DBConnectionError $e ) {
4264                         $ok = false;
4265
4266                         $this->connLogger->error(
4267                                 $fname . ': lost connection to {dbserver} permanently',
4268                                 [ 'dbserver' => $this->getServer() ]
4269                         );
4270                 }
4271
4272                 $this->handleSessionLossPostconnect();
4273
4274                 return $ok;
4275         }
4276
4277         public function getSessionLagStatus() {
4278                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4279         }
4280
4281         /**
4282          * Get the replica DB lag when the current transaction started
4283          *
4284          * This is useful when transactions might use snapshot isolation
4285          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4286          * is this lag plus transaction duration. If they don't, it is still
4287          * safe to be pessimistic. This returns null if there is no transaction.
4288          *
4289          * This returns null if the lag status for this transaction was not yet recorded.
4290          *
4291          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4292          * @since 1.27
4293          */
4294         final protected function getRecordedTransactionLagStatus() {
4295                 return ( $this->trxLevel() && $this->trxReplicaLag !== null )
4296                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4297                         : null;
4298         }
4299
4300         /**
4301          * Get a replica DB lag estimate for this server
4302          *
4303          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4304          * @since 1.27
4305          */
4306         protected function getApproximateLagStatus() {
4307                 return [
4308                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4309                         'since' => microtime( true )
4310                 ];
4311         }
4312
4313         /**
4314          * Merge the result of getSessionLagStatus() for several DBs
4315          * using the most pessimistic values to estimate the lag of
4316          * any data derived from them in combination
4317          *
4318          * This is information is useful for caching modules
4319          *
4320          * @see WANObjectCache::set()
4321          * @see WANObjectCache::getWithSetCallback()
4322          *
4323          * @param IDatabase $db1
4324          * @param IDatabase|null $db2 [optional]
4325          * @return array Map of values:
4326          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4327          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4328          *   - pending: whether any of the DBs have uncommitted changes
4329          * @throws DBError
4330          * @since 1.27
4331          */
4332         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4333                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4334                 foreach ( func_get_args() as $db ) {
4335                         /** @var IDatabase $db */
4336                         $status = $db->getSessionLagStatus();
4337                         if ( $status['lag'] === false ) {
4338                                 $res['lag'] = false;
4339                         } elseif ( $res['lag'] !== false ) {
4340                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4341                         }
4342                         $res['since'] = min( $res['since'], $status['since'] );
4343                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4344                 }
4345
4346                 return $res;
4347         }
4348
4349         public function getLag() {
4350                 if ( $this->getLBInfo( 'master' ) ) {
4351                         return 0; // this is the master
4352                 } elseif ( $this->getLBInfo( 'is static' ) ) {
4353                         return 0; // static dataset
4354                 }
4355
4356                 return $this->doGetLag();
4357         }
4358
4359         protected function doGetLag() {
4360                 return 0;
4361         }
4362
4363         public function maxListLen() {
4364                 return 0;
4365         }
4366
4367         public function encodeBlob( $b ) {
4368                 return $b;
4369         }
4370
4371         public function decodeBlob( $b ) {
4372                 if ( $b instanceof Blob ) {
4373                         $b = $b->fetch();
4374                 }
4375                 return $b;
4376         }
4377
4378         public function setSessionOptions( array $options ) {
4379         }
4380
4381         public function sourceFile(
4382                 $filename,
4383                 callable $lineCallback = null,
4384                 callable $resultCallback = null,
4385                 $fname = false,
4386                 callable $inputCallback = null
4387         ) {
4388                 Wikimedia\suppressWarnings();
4389                 $fp = fopen( $filename, 'r' );
4390                 Wikimedia\restoreWarnings();
4391
4392                 if ( $fp === false ) {
4393                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4394                 }
4395
4396                 if ( !$fname ) {
4397                         $fname = __METHOD__ . "( $filename )";
4398                 }
4399
4400                 try {
4401                         $error = $this->sourceStream(
4402                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4403                 } catch ( Exception $e ) {
4404                         fclose( $fp );
4405                         throw $e;
4406                 }
4407
4408                 fclose( $fp );
4409
4410                 return $error;
4411         }
4412
4413         public function setSchemaVars( $vars ) {
4414                 $this->schemaVars = $vars;
4415         }
4416
4417         public function sourceStream(
4418                 $fp,
4419                 callable $lineCallback = null,
4420                 callable $resultCallback = null,
4421                 $fname = __METHOD__,
4422                 callable $inputCallback = null
4423         ) {
4424                 $delimiterReset = new ScopedCallback(
4425                         function ( $delimiter ) {
4426                                 $this->delimiter = $delimiter;
4427                         },
4428                         [ $this->delimiter ]
4429                 );
4430                 $cmd = '';
4431
4432                 while ( !feof( $fp ) ) {
4433                         if ( $lineCallback ) {
4434                                 call_user_func( $lineCallback );
4435                         }
4436
4437                         $line = trim( fgets( $fp ) );
4438
4439                         if ( $line == '' ) {
4440                                 continue;
4441                         }
4442
4443                         if ( $line[0] == '-' && $line[1] == '-' ) {
4444                                 continue;
4445                         }
4446
4447                         if ( $cmd != '' ) {
4448                                 $cmd .= ' ';
4449                         }
4450
4451                         $done = $this->streamStatementEnd( $cmd, $line );
4452
4453                         $cmd .= "$line\n";
4454
4455                         if ( $done || feof( $fp ) ) {
4456                                 $cmd = $this->replaceVars( $cmd );
4457
4458                                 if ( $inputCallback ) {
4459                                         $callbackResult = $inputCallback( $cmd );
4460
4461                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4462                                                 $cmd = $callbackResult;
4463                                         }
4464                                 }
4465
4466                                 if ( $cmd ) {
4467                                         $res = $this->query( $cmd, $fname );
4468
4469                                         if ( $resultCallback ) {
4470                                                 $resultCallback( $res, $this );
4471                                         }
4472
4473                                         if ( $res === false ) {
4474                                                 $err = $this->lastError();
4475
4476                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4477                                         }
4478                                 }
4479                                 $cmd = '';
4480                         }
4481                 }
4482
4483                 ScopedCallback::consume( $delimiterReset );
4484                 return true;
4485         }
4486
4487         /**
4488          * Called by sourceStream() to check if we've reached a statement end
4489          *
4490          * @param string &$sql SQL assembled so far
4491          * @param string &$newLine New line about to be added to $sql
4492          * @return bool Whether $newLine contains end of the statement
4493          */
4494         public function streamStatementEnd( &$sql, &$newLine ) {
4495                 if ( $this->delimiter ) {
4496                         $prev = $newLine;
4497                         $newLine = preg_replace(
4498                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4499                         if ( $newLine != $prev ) {
4500                                 return true;
4501                         }
4502                 }
4503
4504                 return false;
4505         }
4506
4507         /**
4508          * Database independent variable replacement. Replaces a set of variables
4509          * in an SQL statement with their contents as given by $this->getSchemaVars().
4510          *
4511          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4512          *
4513          * - '{$var}' should be used for text and is passed through the database's
4514          *   addQuotes method.
4515          * - `{$var}` should be used for identifiers (e.g. table and database names).
4516          *   It is passed through the database's addIdentifierQuotes method which
4517          *   can be overridden if the database uses something other than backticks.
4518          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4519          *   database's tableName method.
4520          * - / *i* / passes the name that follows through the database's indexName method.
4521          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4522          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4523          *
4524          * @param string $ins SQL statement to replace variables in
4525          * @return string The new SQL statement with variables replaced
4526          */
4527         protected function replaceVars( $ins ) {
4528                 $vars = $this->getSchemaVars();
4529                 return preg_replace_callback(
4530                         '!
4531                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4532                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4533                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4534                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4535                         !x',
4536                         function ( $m ) use ( $vars ) {
4537                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4538                                 // check for both nonexistent keys *and* the empty string.
4539                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4540                                         if ( $m[1] === 'i' ) {
4541                                                 return $this->indexName( $m[2] );
4542                                         } else {
4543                                                 return $this->tableName( $m[2] );
4544                                         }
4545                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4546                                         return $this->addQuotes( $vars[$m[3]] );
4547                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4548                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4549                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4550                                         return $vars[$m[5]];
4551                                 } else {
4552                                         return $m[0];
4553                                 }
4554                         },
4555                         $ins
4556                 );
4557         }
4558
4559         /**
4560          * Get schema variables. If none have been set via setSchemaVars(), then
4561          * use some defaults from the current object.
4562          *
4563          * @return array
4564          */
4565         protected function getSchemaVars() {
4566                 if ( $this->schemaVars ) {
4567                         return $this->schemaVars;
4568                 } else {
4569                         return $this->getDefaultSchemaVars();
4570                 }
4571         }
4572
4573         /**
4574          * Get schema variables to use if none have been set via setSchemaVars().
4575          *
4576          * Override this in derived classes to provide variables for tables.sql
4577          * and SQL patch files.
4578          *
4579          * @return array
4580          */
4581         protected function getDefaultSchemaVars() {
4582                 return [];
4583         }
4584
4585         public function lockIsFree( $lockName, $method ) {
4586                 // RDBMs methods for checking named locks may or may not count this thread itself.
4587                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4588                 // the behavior choosen by the interface for this method.
4589                 return !isset( $this->sessionNamedLocks[$lockName] );
4590         }
4591
4592         public function lock( $lockName, $method, $timeout = 5 ) {
4593                 $this->sessionNamedLocks[$lockName] = 1;
4594
4595                 return true;
4596         }
4597
4598         public function unlock( $lockName, $method ) {
4599                 unset( $this->sessionNamedLocks[$lockName] );
4600
4601                 return true;
4602         }
4603
4604         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4605                 if ( $this->writesOrCallbacksPending() ) {
4606                         // This only flushes transactions to clear snapshots, not to write data
4607                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4608                         throw new DBUnexpectedError(
4609                                 $this,
4610                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4611                         );
4612                 }
4613
4614                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4615                         return null;
4616                 }
4617
4618                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4619                         if ( $this->trxLevel() ) {
4620                                 // There is a good chance an exception was thrown, causing any early return
4621                                 // from the caller. Let any error handler get a chance to issue rollback().
4622                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4623                                 $this->onTransactionResolution(
4624                                         function () use ( $lockKey, $fname ) {
4625                                                 $this->unlock( $lockKey, $fname );
4626                                         },
4627                                         $fname
4628                                 );
4629                         } else {
4630                                 $this->unlock( $lockKey, $fname );
4631                         }
4632                 } );
4633
4634                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4635
4636                 return $unlocker;
4637         }
4638
4639         public function namedLocksEnqueue() {
4640                 return false;
4641         }
4642
4643         public function tableLocksHaveTransactionScope() {
4644                 return true;
4645         }
4646
4647         final public function lockTables( array $read, array $write, $method ) {
4648                 if ( $this->writesOrCallbacksPending() ) {
4649                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4650                 }
4651
4652                 if ( $this->tableLocksHaveTransactionScope() ) {
4653                         $this->startAtomic( $method );
4654                 }
4655
4656                 return $this->doLockTables( $read, $write, $method );
4657         }
4658
4659         /**
4660          * Helper function for lockTables() that handles the actual table locking
4661          *
4662          * @param array $read Array of tables to lock for read access
4663          * @param array $write Array of tables to lock for write access
4664          * @param string $method Name of caller
4665          * @return true
4666          */
4667         protected function doLockTables( array $read, array $write, $method ) {
4668                 return true;
4669         }
4670
4671         final public function unlockTables( $method ) {
4672                 if ( $this->tableLocksHaveTransactionScope() ) {
4673                         $this->endAtomic( $method );
4674
4675                         return true; // locks released on COMMIT/ROLLBACK
4676                 }
4677
4678                 return $this->doUnlockTables( $method );
4679         }
4680
4681         /**
4682          * Helper function for unlockTables() that handles the actual table unlocking
4683          *
4684          * @param string $method Name of caller
4685          * @return true
4686          */
4687         protected function doUnlockTables( $method ) {
4688                 return true;
4689         }
4690
4691         /**
4692          * Delete a table
4693          * @param string $tableName
4694          * @param string $fName
4695          * @return bool|IResultWrapper
4696          * @since 1.18
4697          */
4698         public function dropTable( $tableName, $fName = __METHOD__ ) {
4699                 if ( !$this->tableExists( $tableName, $fName ) ) {
4700                         return false;
4701                 }
4702                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4703
4704                 return $this->query( $sql, $fName );
4705         }
4706
4707         public function getInfinity() {
4708                 return 'infinity';
4709         }
4710
4711         public function encodeExpiry( $expiry ) {
4712                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4713                         ? $this->getInfinity()
4714                         : $this->timestamp( $expiry );
4715         }
4716
4717         public function decodeExpiry( $expiry, $format = TS_MW ) {
4718                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4719                         return 'infinity';
4720                 }
4721
4722                 return ConvertibleTimestamp::convert( $format, $expiry );
4723         }
4724
4725         public function setBigSelects( $value = true ) {
4726                 // no-op
4727         }
4728
4729         public function isReadOnly() {
4730                 return ( $this->getReadOnlyReason() !== false );
4731         }
4732
4733         /**
4734          * @return string|bool Reason this DB is read-only or false if it is not
4735          */
4736         protected function getReadOnlyReason() {
4737                 $reason = $this->getLBInfo( 'readOnlyReason' );
4738
4739                 return is_string( $reason ) ? $reason : false;
4740         }
4741
4742         public function setTableAliases( array $aliases ) {
4743                 $this->tableAliases = $aliases;
4744         }
4745
4746         public function setIndexAliases( array $aliases ) {
4747                 $this->indexAliases = $aliases;
4748         }
4749
4750         /**
4751          * @param int $field
4752          * @param int $flags
4753          * @return bool
4754          */
4755         protected function hasFlags( $field, $flags ) {
4756                 return ( ( $field & $flags ) === $flags );
4757         }
4758
4759         /**
4760          * Get the underlying binding connection handle
4761          *
4762          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4763          * This catches broken callers than catch and ignore disconnection exceptions.
4764          * Unlike checking isOpen(), this is safe to call inside of open().
4765          *
4766          * @return mixed
4767          * @throws DBUnexpectedError
4768          * @since 1.26
4769          */
4770         protected function getBindingHandle() {
4771                 if ( !$this->conn ) {
4772                         throw new DBUnexpectedError(
4773                                 $this,
4774                                 'DB connection was already closed or the connection dropped.'
4775                         );
4776                 }
4777
4778                 return $this->conn;
4779         }
4780
4781         public function __toString() {
4782                 // spl_object_id is PHP >= 7.2
4783                 $id = function_exists( 'spl_object_id' )
4784                         ? spl_object_id( $this )
4785                         : spl_object_hash( $this );
4786
4787                 $description = $this->getType() . ' object #' . $id;
4788                 if ( is_resource( $this->conn ) ) {
4789                         $description .= ' (' . (string)$this->conn . ')'; // "resource id #<ID>"
4790                 } elseif ( is_object( $this->conn ) ) {
4791                         // spl_object_id is PHP >= 7.2
4792                         $handleId = function_exists( 'spl_object_id' )
4793                                 ? spl_object_id( $this->conn )
4794                                 : spl_object_hash( $this->conn );
4795                         $description .= " (handle id #$handleId)";
4796                 }
4797
4798                 return $description;
4799         }
4800
4801         /**
4802          * Make sure that copies do not share the same client binding handle
4803          * @throws DBConnectionError
4804          */
4805         public function __clone() {
4806                 $this->connLogger->warning(
4807                         "Cloning " . static::class . " is not recommended; forking connection:\n" .
4808                         ( new RuntimeException() )->getTraceAsString()
4809                 );
4810
4811                 if ( $this->isOpen() ) {
4812                         // Open a new connection resource without messing with the old one
4813                         $this->conn = false;
4814                         $this->trxEndCallbacks = []; // don't copy
4815                         $this->trxSectionCancelCallbacks = []; // don't copy
4816                         $this->handleSessionLossPreconnect(); // no trx or locks anymore
4817                         $this->open(
4818                                 $this->server,
4819                                 $this->user,
4820                                 $this->password,
4821                                 $this->getDBname(),
4822                                 $this->dbSchema(),
4823                                 $this->tablePrefix()
4824                         );
4825                         $this->lastPing = microtime( true );
4826                 }
4827         }
4828
4829         /**
4830          * Called by serialize. Throw an exception when DB connection is serialized.
4831          * This causes problems on some database engines because the connection is
4832          * not restored on unserialize.
4833          */
4834         public function __sleep() {
4835                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4836                         'the connection is not restored on wakeup.' );
4837         }
4838
4839         /**
4840          * Run a few simple sanity checks and close dangling connections
4841          */
4842         public function __destruct() {
4843                 if ( $this->trxLevel() && $this->trxDoneWrites ) {
4844                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4845                 }
4846
4847                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4848                 if ( $danglingWriters ) {
4849                         $fnames = implode( ', ', $danglingWriters );
4850                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4851                 }
4852
4853                 if ( $this->conn ) {
4854                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4855                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4856                         Wikimedia\suppressWarnings();
4857                         $this->closeConnection();
4858                         Wikimedia\restoreWarnings();
4859                         $this->conn = false;
4860                 }
4861         }
4862 }
4863
4864 /**
4865  * @deprecated since 1.28
4866  */
4867 class_alias( Database::class, 'DatabaseBase' );
4868
4869 /**
4870  * @deprecated since 1.29
4871  */
4872 class_alias( Database::class, 'Database' );