Database.php
7042373a0708master

Database.php
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	<?php
	/**
	* @license GPL-2.0-or-later
	* @file
	*/
	namespace Wikimedia\Rdbms;

	use InvalidArgumentException;
	use LogicException;
	use Psr\Log\LoggerAwareInterface;
	use Psr\Log\LoggerInterface;
	use Psr\Log\NullLogger;
	use RuntimeException;
	use Stringable;
	use Throwable;
	use Wikimedia\AtEase\AtEase;
	use Wikimedia\Rdbms\Database\DatabaseFlags;
	use Wikimedia\Rdbms\Platform\SQLPlatform;
	use Wikimedia\Rdbms\Replication\ReplicationReporter;
	use Wikimedia\RequestTimeout\CriticalSectionProvider;
	use Wikimedia\RequestTimeout\CriticalSectionScope;
	use Wikimedia\ScopedCallback;
	use Wikimedia\Telemetry\NoopTracer;
	use Wikimedia\Telemetry\SpanInterface;
	use Wikimedia\Telemetry\TracerInterface;

	/**
	* A single concrete connection to a relational database.
	*
	* This is the base class for all connection-specific relational database handles.
	* No two instances of this class should share the same underlying network connection.
	*
	* @see IDatabase
	* @ingroup Database
	* @since 1.28
	*/
	abstract class Database implements Stringable, IDatabaseForOwner, IMaintainableDatabase, LoggerAwareInterface {
	/** @var CriticalSectionProvider\|null */
	protected $csProvider;
	/** @var LoggerInterface */
	protected $logger;
	/** @var callable Error logging callback */
	protected $errorLogger;
	/** @var callable Deprecation logging callback */
	protected $deprecationLogger;
	/** @var callable\|null */
	protected $profiler;
	/** @var TracerInterface */
	private $tracer;
	/** @var TransactionManager */
	private $transactionManager;

	/** @var DatabaseDomain */
	protected $currentDomain;
	/** @var DatabaseFlags */
	protected $flagsHolder;

	// phpcs:ignore MediaWiki.Commenting.PropertyDocumentation.ObjectTypeHintVar
	/** @var object\|resource\|null Database connection */
	protected $conn;

	/** @var string\|null Readable name or host/IP of the database server */
	protected $serverName;
	/** @var bool Whether this PHP instance is for a CLI script */
	protected $cliMode;
	/** @var int\|null Maximum seconds to wait on connection attempts */
	protected $connectTimeout;
	/** @var int\|null Maximum seconds to wait on receiving query results */
	protected $receiveTimeout;
	/** @var string Agent name for query profiling */
	protected $agent;
	/** @var array<string,mixed> Connection parameters used by initConnection() and open() */
	protected $connectionParams;
	/** @var string[]\|int[]\|float[] SQL variables values to use for all new connections */
	protected $connectionVariables;
	/** @var int Row batch size to use for emulated INSERT SELECT queries */
	protected $nonNativeInsertSelectBatchSize;

	/** @var bool Whether to use SSL connections */
	protected $ssl;
	/** @var bool Whether to check for warnings */
	protected $strictWarnings;
	/** @var array Current LoadBalancer tracking information */
	protected $lbInfo = [];
	/** @var string\|false Current SQL query delimiter */
	protected $delimiter = ';';

	/** @var string\|bool\|null Stashed value of html_errors INI setting */
	private $htmlErrors;

	/** @var array<string,array> Map of (lock name => (UNIX time,trx ID)) */
	protected $sessionNamedLocks = [];
	/** @var array<string,array<string, TempTableInfo>> Map of (DB name => table name => info) */
	protected $sessionTempTables = [];

	/** @var int Affected row count for the last statement to query() */
	protected $lastQueryAffectedRows = 0;
	/** @var int\|null Insert (row) ID for the last statement to query() (null if not supported) */
	protected $lastQueryInsertId;

	/** @var int\|null Affected row count for the last query method call; null if unspecified */
	protected $lastEmulatedAffectedRows;
	/** @var int\|null Insert (row) ID for the last query method call; null if unspecified */
	protected $lastEmulatedInsertId;

	/** @var string Last error during connection; empty string if none */
	protected $lastConnectError = '';

	/** @var float UNIX timestamp of the last server response */
	private $lastPing = 0.0;
	/** @var float\|null UNIX timestamp of the last committed write */
	private $lastWriteTime;
	/** @var string\|false The last PHP error from a query or connection attempt */
	private $lastPhpError = false;

	/** @var int\|null Current critical section numeric ID */
	private $csmId;
	/** @var string\|null Last critical section caller name */
	private $csmFname;
	/** @var DBUnexpectedError\|null Last unresolved critical section error */
	private $csmError;

	/** Whether the database is a file on disk */
	public const ATTR_DB_IS_FILE = 'db-is-file';
	/** Lock granularity is on the level of the entire database */
	public const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
	/** The SCHEMA keyword refers to a grouping of tables in a database */
	public const ATTR_SCHEMAS_AS_TABLE_GROUPS = 'supports-schemas';

	/** New Database instance will not be connected yet when returned */
	public const NEW_UNCONNECTED = 0;
	/** New Database instance will already be connected when returned */
	public const NEW_CONNECTED = 1;

	/** No errors occurred during the query */
	protected const ERR_NONE = 0;
	/** Retry query due to a connection loss detected while sending the query (session intact) */
	protected const ERR_RETRY_QUERY = 1;
	/** Abort query (no retries) due to a statement rollback (session/transaction intact) */
	protected const ERR_ABORT_QUERY = 2;
	/** Abort any current transaction, by rolling it back, due to an error during the query */
	protected const ERR_ABORT_TRX = 4;
	/** Abort and reset session due to server-side session-level state loss (locks, temp tables) */
	protected const ERR_ABORT_SESSION = 8;

	/** Assume that queries taking this long to yield connection loss errors are at fault */
	protected const DROPPED_CONN_BLAME_THRESHOLD_SEC = 3.0;

	/** @var string Idiom used when a cancelable atomic section started the transaction */
	private const NOT_APPLICABLE = 'n/a';

	/** How long before it is worth doing a dummy query to test the connection */
	private const PING_TTL = 1.0;
	/** Dummy SQL query */
	private const PING_QUERY = 'SELECT 1 AS ping';

	/** Hostname or IP address to use on all connections */
	protected const CONN_HOST = 'host';
	/** Database server username to use on all connections */
	protected const CONN_USER = 'user';
	/** Database server password to use on all connections */
	protected const CONN_PASSWORD = 'password';
	/** Database name to use on initial connection */
	protected const CONN_INITIAL_DB = 'dbname';
	/** Schema name to use on initial connection */
	protected const CONN_INITIAL_SCHEMA = 'schema';
	/** Table prefix to use on initial connection */
	protected const CONN_INITIAL_TABLE_PREFIX = 'tablePrefix';

	/** @var SQLPlatform */
	protected $platform;

	/** @var ReplicationReporter */
	protected $replicationReporter;

	/**
	* @note exceptions for missing libraries/drivers should be thrown in initConnection()
	* @param array $params Parameters passed from Database::factory()
	*/
	public function __construct( array $params ) {
	$this->logger = $params['logger'] ?? new NullLogger();
	$this->transactionManager = new TransactionManager(
	$this->logger,
	$params['trxProfiler']
	);
	$this->connectionParams = [
	self::CONN_HOST => ( isset( $params['host'] ) && $params['host'] !== '' )
	? $params['host']
	: null,
	self::CONN_USER => ( isset( $params['user'] ) && $params['user'] !== '' )
	? $params['user']
	: null,
	self::CONN_INITIAL_DB => ( isset( $params['dbname'] ) && $params['dbname'] !== '' )
	? $params['dbname']
	: null,
	self::CONN_INITIAL_SCHEMA => ( isset( $params['schema'] ) && $params['schema'] !== '' )
	? $params['schema']
	: null,
	self::CONN_PASSWORD => is_string( $params['password'] ) ? $params['password'] : null,
	self::CONN_INITIAL_TABLE_PREFIX => (string)$params['tablePrefix']
	];

	$this->lbInfo = $params['lbInfo'] ?? [];
	$this->connectionVariables = $params['variables'] ?? [];
	// Set SQL mode, default is turning them all off, can be overridden or skipped with null
	if ( is_string( $params['sqlMode'] ?? null ) ) {
	$this->connectionVariables['sql_mode'] = $params['sqlMode'];
	}
	$flags = (int)$params['flags'];
	$this->flagsHolder = new DatabaseFlags( $flags );
	$this->ssl = $params['ssl'] ?? (bool)( $flags & self::DBO_SSL );
	$this->connectTimeout = $params['connectTimeout'] ?? null;
	$this->receiveTimeout = $params['receiveTimeout'] ?? null;
	$this->cliMode = (bool)$params['cliMode'];
	$this->agent = (string)$params['agent'];
	$this->serverName = $params['serverName'];
	$this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'] ?? 10000;
	$this->strictWarnings = !empty( $params['strictWarnings'] );

	$this->profiler = is_callable( $params['profiler'] ) ? $params['profiler'] : null;
	$this->errorLogger = $params['errorLogger'];
	$this->deprecationLogger = $params['deprecationLogger'];

	$this->csProvider = $params['criticalSectionProvider'] ?? null;

	// Set initial dummy domain until open() sets the final DB/prefix
	$this->currentDomain = new DatabaseDomain(
	$params['dbname'] != '' ? $params['dbname'] : null,
	$params['schema'] != '' ? $params['schema'] : null,
	$params['tablePrefix']
	);
	$this->platform = new SQLPlatform(
	$this,
	$this->logger,
	$this->currentDomain,
	$this->errorLogger
	);
	$this->tracer = $params['tracer'] ?? new NoopTracer();
	// Children classes must set $this->replicationReporter.
	}

	/**
	* Initialize the connection to the database over the wire (or to local files)
	*
	* @throws LogicException
	* @throws InvalidArgumentException
	* @throws DBConnectionError
	* @since 1.31
	*/
	final public function initConnection() {
	if ( $this->isOpen() ) {
	throw new LogicException( __METHOD__ . ': already connected' );
	}
	// Establish the connection
	$this->open(
	$this->connectionParams[self::CONN_HOST],
	$this->connectionParams[self::CONN_USER],
	$this->connectionParams[self::CONN_PASSWORD],
	$this->connectionParams[self::CONN_INITIAL_DB],
	$this->connectionParams[self::CONN_INITIAL_SCHEMA],
	$this->connectionParams[self::CONN_INITIAL_TABLE_PREFIX]
	);
	$this->lastPing = microtime( true );
	}

	/**
	* Open a new connection to the database (closing any existing one)
	*
	* @param string\|null $server Server host/address and optional port {@see connectionParams}
	* @param string\|null $user User name {@see connectionParams}
	* @param string\|null $password User password {@see connectionParams}
	* @param string\|null $db Database name
	* @param string\|null $schema Database schema name
	* @param string $tablePrefix
	* @throws DBConnectionError
	*/
	abstract protected function open( $server, $user, $password, $db, $schema, $tablePrefix );

	/**
	* @return array Map of (Database::ATTR_* constant => value)
	* @since 1.31
	*/
	public static function getAttributes() {
	return [];
	}

	/**
	* Set the PSR-3 logger interface to use.
	*/
	public function setLogger( LoggerInterface $logger ): void {
	$this->logger = $logger;
	}

	/** @inheritDoc */
	public function getServerInfo() {
	return $this->getServerVersion();
	}

	/** @inheritDoc */
	public function tablePrefix( $prefix = null ) {
	$old = $this->currentDomain->getTablePrefix();

	if ( $prefix !== null ) {
	$this->currentDomain = new DatabaseDomain(
	$this->currentDomain->getDatabase(),
	$this->currentDomain->getSchema(),
	$prefix
	);
	$this->platform->setCurrentDomain( $this->currentDomain );
	}

	return $old;
	}

	/** @inheritDoc */
	public function dbSchema( $schema = null ) {
	$old = $this->currentDomain->getSchema();

	if ( $schema !== null ) {
	if ( $schema !== '' && $this->getDBname() === null ) {
	throw new DBUnexpectedError(
	$this,
	"Cannot set schema to '$schema'; no database set"
	);
	}

	$this->currentDomain = new DatabaseDomain(
	$this->currentDomain->getDatabase(),
	// DatabaseDomain uses null for unspecified schemas
	( $schema !== '' ) ? $schema : null,
	$this->currentDomain->getTablePrefix()
	);
	$this->platform->setCurrentDomain( $this->currentDomain );
	}

	return (string)$old;
	}

	/** @inheritDoc */
	public function getLBInfo( $name = null ) {
	if ( $name === null ) {
	return $this->lbInfo;
	}

	if ( array_key_exists( $name, $this->lbInfo ) ) {
	return $this->lbInfo[$name];
	}

	return null;
	}

	/** @inheritDoc */
	public function setLBInfo( $nameOrArray, $value = null ) {
	if ( is_array( $nameOrArray ) ) {
	$this->lbInfo = $nameOrArray;
	} elseif ( is_string( $nameOrArray ) ) {
	if ( $value !== null ) {
	$this->lbInfo[$nameOrArray] = $value;
	} else {
	unset( $this->lbInfo[$nameOrArray] );
	}
	} else {
	throw new InvalidArgumentException( "Got non-string key" );
	}
	}

	/** @inheritDoc */
	public function lastDoneWrites() {
	return $this->lastWriteTime;
	}

	/**
	* @return bool
	* @since 1.39
	* @internal For use by Database/LoadBalancer only
	*/
	public function sessionLocksPending() {
	return (bool)$this->sessionNamedLocks;
	}

	/**
	* @return ?string Owner name of explicit transaction round being participating in; null if none
	*/
	final protected function getTransactionRoundFname() {
	if ( $this->flagsHolder->hasImplicitTrxFlag() ) {
	// LoadBalancer transaction round participation is enabled for this DB handle;
	// get the owner of the active explicit transaction round (if any)
	return $this->getLBInfo( self::LB_TRX_ROUND_FNAME );
	}

	return null;
	}

	/** @inheritDoc */
	public function isOpen() {
	return (bool)$this->conn;
	}

	/** @inheritDoc */
	public function getDomainID() {
	return $this->currentDomain->getId();
	}

	/**
	* Wrapper for addslashes()
	*
	* @param string $s String to be slashed.
	* @return string Slashed string.
	*/
	abstract public function strencode( $s );

	/**
	* Set a custom error handler for logging errors during database connection
	*/
	protected function installErrorHandler() {
	$this->lastPhpError = false;
	$this->htmlErrors = ini_set( 'html_errors', '0' );
	set_error_handler( $this->connectionErrorLogger( ... ) );
	}

	/**
	* Restore the previous error handler and return the last PHP error for this DB
	*
	* @return string\|false
	*/
	protected function restoreErrorHandler() {
	restore_error_handler();
	if ( $this->htmlErrors !== false ) {
	ini_set( 'html_errors', $this->htmlErrors );
	}

	return $this->getLastPHPError();
	}

	/**
	* @return string\|false Last PHP error for this DB (typically connection errors)
	*/
	protected function getLastPHPError() {
	if ( $this->lastPhpError ) {
	$error = preg_replace( '!\[<a.*</a>\]!', '', $this->lastPhpError );
	$error = preg_replace( '!^.?:\s?(.)$!', '$1', $error );

	return $error;
	}

	return false;
	}

	/**
	* Error handler for logging errors during database connection
	*
	* @internal This method should not be used outside of Database classes
	*
	* @param int\|string $errno
	* @param string $errstr
	*/
	public function connectionErrorLogger( $errno, $errstr ) {
	$this->lastPhpError = $errstr;
	}

	/**
	* Create a log context to pass to PSR-3 logger functions.
	*
	* @param array $extras Additional data to add to context
	* @return array
	*/
	protected function getLogContext( array $extras = [] ) {
	return $extras + [
	'db_server' => $this->getServerName(),
	'db_name' => $this->getDBname(),
	'db_user' => $this->connectionParams[self::CONN_USER] ?? null,
	];
	}

	/** @inheritDoc */
	final public function close( $fname = __METHOD__ ) {
	$error = null; // error to throw after disconnecting

	$wasOpen = (bool)$this->conn;
	// This should mostly do nothing if the connection is already closed
	if ( $this->conn ) {
	// Roll back any dangling transaction first
	if ( $this->trxLevel() ) {
	$error = $this->transactionManager->trxCheckBeforeClose( $this, $fname );
	// Rollback the changes and run any callbacks as needed
	$this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
	$this->runTransactionPostRollbackCallbacks();
	}

	// Close the actual connection in the binding handle
	$closed = $this->closeConnection();
	} else {
	$closed = true; // already closed; nothing to do
	}

	$this->conn = null;

	// Log any unexpected errors after having disconnected
	if ( $error !== null ) {
	// T217819, T231443: this is probably just LoadBalancer trying to recover from
	// errors and shutdown. Log any problems and move on since the request has to
	// end one way or another. Throwing errors is not very useful at some point.
	$this->logger->error( $error, [ 'db_log_category' => 'query' ] );
	}

	// Note that various subclasses call close() at the start of open(), which itself is
	// called by replaceLostConnection(). In that case, just because onTransactionResolution()
	// callbacks are pending does not mean that an exception should be thrown. Rather, they
	// will be executed after the reconnection step.
	if ( $wasOpen ) {
	// Double check that no callbacks are dangling
	$fnames = $this->pendingWriteAndCallbackCallers();
	if ( $fnames ) {
	throw new RuntimeException(
	"Transaction callbacks are still pending: " . implode( ', ', $fnames )
	);
	}
	}

	return $closed;
	}

	/**
	* Make sure there is an open connection handle (alive or not)
	*
	* This guards against fatal errors to the binding handle not being defined in cases
	* where open() was never called or close() was already called.
	*
	* @throws DBUnexpectedError
	*/
	final protected function assertHasConnectionHandle() {
	if ( !$this->isOpen() ) {
	throw new DBUnexpectedError( $this, "DB connection was already closed" );
	}
	}

	/**
	* Closes underlying database connection
	* @return bool Whether connection was closed successfully
	* @since 1.20
	*/
	abstract protected function closeConnection();

	/**
	* Run a query and return a QueryStatus instance with the query result information
	*
	* This is meant to handle the basic command of actually sending a query to the
	* server via the driver. No implicit transaction, reconnection, nor retry logic
	* should happen here. The higher level query() method is designed to handle those
	* sorts of concerns. This method should not trigger such higher level methods.
	*
	* The lastError() and lastErrno() methods should meaningfully reflect what error,
	* if any, occurred during the last call to this method. Methods like executeQuery(),
	* query(), select(), insert(), update(), delete(), and upsert() implement their calls
	* to doQuery() such that an immediately subsequent call to lastError()/lastErrno()
	* meaningfully reflects any error that occurred during that public query method call.
	*
	* For SELECT queries, the result field contains either:
	* - a) A driver-specific IResultWrapper describing the query results
	* - b) False, on any query failure
	*
	* For non-SELECT queries, the result field contains either:
	* - a) A driver-specific IResultWrapper, only on success
	* - b) True, only on success (e.g. no meaningful result other than "OK")
	* - c) False, on any query failure
	*
	* @param string $sql Single-statement SQL query
	* @return QueryStatus
	* @since 1.39
	*/
	abstract protected function doSingleStatementQuery( string $sql ): QueryStatus;

	/**
	* Determine whether a write query affects a permanent table.
	* This includes pseudo-permanent tables.
	*
	* @param Query $query
	* @return bool
	*/
	private function hasPermanentTable( Query $query ) {
	if ( $query->getVerb() === 'CREATE TEMPORARY' ) {
	// Temporary table creation is allowed
	return false;
	}
	$table = $query->getWriteTable();
	if ( $table === null ) {
	// Parse error? Assume permanent.
	return true;
	}
	[ $db, $pt ] = $this->platform->getDatabaseAndTableIdentifier( $table );
	$tempInfo = $this->sessionTempTables[$db][$pt] ?? null;
	return !$tempInfo \|\| $tempInfo->pseudoPermanent;
	}

	/**
	* Register creation and dropping of temporary tables
	*/
	protected function registerTempTables( Query $query ) {
	$table = $query->getWriteTable();
	if ( $table === null ) {
	return;
	}
	switch ( $query->getVerb() ) {
	case 'CREATE TEMPORARY':
	[ $db, $pt ] = $this->platform->getDatabaseAndTableIdentifier( $table );
	$this->sessionTempTables[$db][$pt] = new TempTableInfo(
	$this->transactionManager->getTrxId(),
	(bool)( $query->getFlags() & self::QUERY_PSEUDO_PERMANENT )
	);
	break;

	case 'DROP':
	[ $db, $pt ] = $this->platform->getDatabaseAndTableIdentifier( $table );
	unset( $this->sessionTempTables[$db][$pt] );
	}
	}

	/** @inheritDoc */
	public function query( $sql, $fname = __METHOD__, $flags = 0 ) {
	if ( !( $sql instanceof Query ) ) {
	$flags = (int)$flags; // b/c; this field used to be a bool
	$sql = QueryBuilderFromRawSql::buildQuery( $sql, $flags, $this->currentDomain->getTablePrefix() );
	} else {
	$flags = $sql->getFlags();
	}

	// Make sure that this caller is allowed to issue this query statement
	$this->assertQueryIsCurrentlyAllowed( $sql->getVerb(), $fname );

	// Send the query to the server and fetch any corresponding errors
	$status = $this->executeQuery( $sql, $fname, $flags );
	if ( $status->res === false ) {
	// An error occurred; log, and, if needed, report an exception.
	// Errors that corrupt the transaction/session state cannot be silenced.
	$ignore = (
	$this->flagsHolder::contains( $flags, self::QUERY_SILENCE_ERRORS ) &&
	!$this->flagsHolder::contains( $status->flags, self::ERR_ABORT_SESSION ) &&
	!$this->flagsHolder::contains( $status->flags, self::ERR_ABORT_TRX )
	);
	$this->reportQueryError( $status->message, $status->code, $sql->getSQL(), $fname, $ignore );
	}

	return $status->res;
	}

	/**
	* Execute a query without enforcing public (non-Database) caller restrictions.
	*
	* Retry it if there is a recoverable connection loss (e.g. no important state lost).
	*
	* This does not precheck for transaction/session state errors or critical section errors.
	*
	* @see Database::query()
	*
	* @param Query $sql SQL statement
	* @param string $fname Name of the calling function
	* @param int $flags Bit field of ISQLPlatform::QUERY_* constants
	* @return QueryStatus
	* @throws DBUnexpectedError
	* @since 1.34
	*/
	final protected function executeQuery( $sql, $fname, $flags ) {
	$this->assertHasConnectionHandle();

	$isPermWrite = false;
	$isWrite = $sql->isWriteQuery();
	if ( $isWrite ) {
	ChangedTablesTracker::recordQuery( $this->currentDomain, $sql );
	// Permit temporary table writes on replica connections, but require a writable
	// master connection for writes to persistent tables.
	if ( $this->hasPermanentTable( $sql ) ) {
	$isPermWrite = true;
	$info = $this->getReadOnlyReason();
	if ( $info ) {
	[ $reason, $source ] = $info;
	if ( $source === 'role' ) {
	throw new DBReadOnlyRoleError( $this, "Database is read-only: $reason" );
	} else {
	throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
	}
	}
	// DBConnRef uses QUERY_REPLICA_ROLE to enforce replica roles during query()
	if ( $this->flagsHolder::contains( $sql->getFlags(), self::QUERY_REPLICA_ROLE ) ) {
	throw new DBReadOnlyRoleError(
	$this,
	"Cannot write; target role is DB_REPLICA"
	);
	}
	}
	}

	// Whether a silent retry attempt is left for recoverable connection loss errors
	$retryLeft = !$this->flagsHolder::contains( $flags, self::QUERY_NO_RETRY );

	$cs = $this->commenceCriticalSection( __METHOD__ );

	do {
	// Start a DBO_TRX wrapper transaction as needed (throw an error on failure)
	if ( $this->beginIfImplied( $sql, $fname, $flags ) ) {
	// Since begin() was called, any connection loss was already handled
	$retryLeft = false;
	}
	// Send the query statement to the server and fetch any results.
	$status = $this->attemptQuery( $sql, $fname, $isPermWrite );
	} while (
	// An error occurred that can be recovered from via query retry
	$this->flagsHolder::contains( $status->flags, self::ERR_RETRY_QUERY ) &&
	// The retry has not been exhausted (consume it now)
	// phpcs:ignore Generic.CodeAnalysis.AssignmentInCondition.FoundInWhileCondition
	$retryLeft && !( $retryLeft = false )
	);

	// Register creation and dropping of temporary tables
	if ( $status->res ) {
	$this->registerTempTables( $sql );
	}
	$this->completeCriticalSection( __METHOD__, $cs );

	return $status;
	}

	/**
	* Query method wrapper handling profiling, logging, affected row count tracking, and
	* automatic reconnections (without retry) on query failure due to connection loss
	*
	* Note that this does not handle DBO_TRX logic.
	*
	* This method handles profiling, debug logging, reconnection and the tracking of:
	* - write callers
	* - last write time
	* - affected row count of the last write
	* - whether writes occurred in a transaction
	* - last successful query time (confirming that the connection was not dropped)
	*
	* @see doSingleStatementQuery()
	*
	* @param Query $sql SQL statement
	* @param string $fname Name of the calling function
	* @param bool $isPermWrite Whether it's a query writing to permanent tables
	* @return QueryStatus statement result
	* @throws DBUnexpectedError
	*/
	private function attemptQuery(
	$sql,
	string $fname,
	bool $isPermWrite
	) {
	// Transaction attributes before issuing this query
	$priorSessInfo = new CriticalSessionInfo(
	$this->transactionManager->getTrxId(),
	$this->transactionManager->explicitTrxActive(),
	$this->transactionManager->pendingWriteCallers(),
	$this->transactionManager->pendingPreCommitCallbackCallers(),
	$this->sessionNamedLocks,
	$this->sessionTempTables
	);
	// Get the transaction-aware SQL string used for profiling
	$generalizedSql = GeneralizedSql::newFromQuery(
	$sql,
	( $this->replicationReporter->getTopologyRole() === self::ROLE_STREAMING_MASTER )
	? 'role-primary: '
	: ''
	);
	// Add agent and calling method comments to the SQL
	$cStatement = $this->makeCommentedSql( $sql->getSQL(), $fname );
	// Start profile section
	$ps = $this->profiler ? ( $this->profiler )( $generalizedSql->stringify() ) : null;
	$startTime = microtime( true );

	// Clear any overrides from a prior "query method". Note that this does not affect
	// any such methods that are currently invoking query() itself since those query
	// methods set these fields before returning.
	$this->lastEmulatedAffectedRows = null;
	$this->lastEmulatedInsertId = null;

	// Record an OTEL span for this query.
	$writeTableName = $sql->getWriteTable();
	$spanName = $writeTableName ?
	"Database {$sql->getVerb()} {$this->getDBname()}.{$writeTableName}" :
	"Database {$sql->getVerb()} {$this->getDBname()}";
	$span = $this->tracer->createSpan( $spanName )
	->setSpanKind( SpanInterface::SPAN_KIND_CLIENT )
	->start();
	if ( $span->getContext()->isSampled() ) {
	$span->setAttributes( [
	'code.function' => $fname,
	'db.namespace' => $this->getDBname(),
	'db.operation.name' => $sql->getVerb(),
	'db.query.text' => $generalizedSql->stringify(),
	'db.system' => $this->getType(),
	'server.address' => $this->getServerName(),
	'db.collection.name' => $writeTableName, # nulls filtered out
	] );
	}

	$status = $this->doSingleStatementQuery( $cStatement );

	// End profile section
	$endTime = microtime( true );
	$queryRuntime = max( $endTime - $startTime, 0.0 );
	unset( $ps );
	$span->end();

	if ( $status->res !== false ) {
	$this->lastPing = $endTime;
	$span->setSpanStatus( SpanInterface::SPAN_STATUS_OK );
	} else {
	$span->setSpanStatus( SpanInterface::SPAN_STATUS_ERROR )
	->setAttributes( [
	'db.response.status_code' => $status->code,
	'exception.message' => $status->message,
	] );
	}

	$affectedRowCount = $status->rowsAffected;
	$returnedRowCount = $status->rowsReturned;
	$this->lastQueryAffectedRows = $affectedRowCount;

	if ( $span->getContext()->isSampled() ) {
	$span->setAttributes( [
	'db.response.affected_rows' => $affectedRowCount,
	'db.response.returned_rows' => $returnedRowCount,
	] );
	}

	if ( $status->res !== false ) {
	if ( $isPermWrite ) {
	if ( $this->trxLevel() ) {
	$this->transactionManager->transactionWritingIn(
	$this->getServerName(),
	$this->getDomainID(),
	$startTime
	);
	$this->transactionManager->updateTrxWriteQueryReport(
	$sql->getSQL(),
	$queryRuntime,
	$affectedRowCount,
	$fname
	);
	} else {
	$this->lastWriteTime = $endTime;
	}
	}
	}

	$this->transactionManager->recordQueryCompletion(
	$generalizedSql,
	$startTime,
	$isPermWrite,
	$isPermWrite ? $affectedRowCount : $returnedRowCount,
	$this->getServerName()
	);

	// Check if the query failed...
	$status->flags = $this->handleErroredQuery( $status, $sql, $fname, $queryRuntime, $priorSessInfo );
	// Avoid the overhead of logging calls unless debug mode is enabled
	if ( $this->flagsHolder->getFlag( self::DBO_DEBUG ) ) {
	$this->logger->debug(
	"{method} [{runtime_ms}ms] {db_server}: {sql}",
	$this->getLogContext( [
	'method' => $fname,
	'sql' => $sql->getSQL(),
	'domain' => $this->getDomainID(),
	'runtime_ms' => round( $queryRuntime * 1000, 3 ),
	'db_log_category' => 'query'
	] )
	);
	}

	return $status;
	}

	private function handleErroredQuery(
	QueryStatus $status, Query $sql, string $fname, float $queryRuntime, CriticalSessionInfo $priorSessInfo
	): int {
	$errflags = self::ERR_NONE;
	$error = $status->message;
	$errno = $status->code;
	if ( $status->res !== false ) {
	// Statement succeeded
	return $errflags;
	}
	if ( $this->isConnectionError( $errno ) ) {
	// Connection lost before or during the query...
	// Determine how to proceed given the lost session state
	$connLossFlag = $this->assessConnectionLoss(
	$sql->getVerb(),
	$queryRuntime,
	$priorSessInfo
	);
	// Update session state tracking and try to reestablish a connection
	$reconnected = $this->replaceLostConnection( $errno, __METHOD__ );
	// Check if important server-side session-level state was lost
	if ( $connLossFlag >= self::ERR_ABORT_SESSION ) {
	$ex = $this->getQueryException( $error, $errno, $sql->getSQL(), $fname );
	$this->transactionManager->setSessionError( $ex );
	}
	// Check if important server-side transaction-level state was lost
	if ( $connLossFlag >= self::ERR_ABORT_TRX ) {
	$ex = $this->getQueryException( $error, $errno, $sql->getSQL(), $fname );
	$this->transactionManager->setTransactionError( $ex );
	}
	// Check if the query should be retried (having made the reconnection attempt)
	if ( $connLossFlag === self::ERR_RETRY_QUERY ) {
	$errflags \|= ( $reconnected ? self::ERR_RETRY_QUERY : self::ERR_ABORT_QUERY );
	} else {
	$errflags \|= $connLossFlag;
	}
	} elseif ( $this->isKnownStatementRollbackError( $errno ) ) {
	// Query error triggered a server-side statement-only rollback...
	$errflags \|= self::ERR_ABORT_QUERY;
	if ( $this->trxLevel() ) {
	// Allow legacy callers to ignore such errors via QUERY_IGNORE_DBO_TRX and
	// try/catch. However, a deprecation notice will be logged on the next query.
	$cause = [ $error, $errno, $fname ];
	$this->transactionManager->setTrxStatusIgnoredCause( $cause );
	}
	} elseif ( $this->trxLevel() ) {
	// Some other error occurred during the query, within a transaction...
	// Server-side handling of errors during transactions varies widely depending on
	// the RDBMS type and configuration. There are several possible results: (a) the
	// whole transaction is rolled back, (b) only the queries after BEGIN are rolled
	// back, (c) the transaction is marked as "aborted" and a ROLLBACK is required
	// before other queries are permitted. For compatibility reasons, pessimistically
	// require a ROLLBACK query (not using SAVEPOINT) before allowing other queries.
	$ex = $this->getQueryException( $error, $errno, $sql->getSQL(), $fname );
	$this->transactionManager->setTransactionError( $ex );
	$errflags \|= self::ERR_ABORT_TRX;
	} else {
	// Some other error occurred during the query, without a transaction...
	$errflags \|= self::ERR_ABORT_QUERY;
	}

	return $errflags;
	}

	/**
	* @param string $sql
	* @param string $fname
	* @return string
	*/
	private function makeCommentedSql( $sql, $fname ): string {
	// Add trace comment to the begin of the sql string, right after the operator.
	// Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598).
	// NOTE: Don't add varying ids such as request id or session id to the comment.
	// It would break aggregation of similar queries in analysis tools (see T193050#7512149)
	$encName = preg_replace( '/[\x00-\x1F\/]/', '-', "$fname {$this->agent}" );
	return preg_replace( '/\s\|$/', " /* $encName */ ", $sql, 1 );
	}

	/**
	* Start an implicit transaction if DBO_TRX is enabled and no transaction is active
	*
	* @param Query $sql SQL statement
	* @param string $fname
	* @param int $flags Bit field of ISQLPlatform::QUERY_* constants
	* @return bool Whether an implicit transaction was started
	* @throws DBError
	*/
	private function beginIfImplied( $sql, $fname, $flags ) {
	if ( !$this->trxLevel() && $this->flagsHolder->hasApplicableImplicitTrxFlag( $flags ) ) {
	if ( $this->platform->isTransactableQuery( $sql ) ) {
	$this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
	$this->transactionManager->turnOnAutomatic();

	return true;
	}
	}

	return false;
	}

	/**
	* Check if callers outside of Database can run the given query given the session state
	*
	* In order to keep the DB handle's session state tracking in sync, certain queries
	* like "USE", "BEGIN", "COMMIT", and "ROLLBACK" must not be issued directly from
	* outside callers. Such commands should only be issued through dedicated methods
	* like selectDomain(), begin(), commit(), and rollback(), respectively.
	*
	* This also checks if the session state tracking was corrupted by a prior exception.
	*
	* @param string $verb
	* @param string $fname
	* @throws DBUnexpectedError
	* @throws DBTransactionStateError
	*/
	private function assertQueryIsCurrentlyAllowed( string $verb, string $fname ) {
	if ( $verb === 'USE' ) {
	throw new DBUnexpectedError( $this, "Got USE query; use selectDomain() instead" );
	}

	if ( $verb === 'ROLLBACK' ) {
	// Whole transaction rollback is used for recovery
	// @TODO: T269161; prevent "BEGIN"/"COMMIT"/"ROLLBACK" from outside callers
	return;
	}

	if ( $this->csmError ) {
	throw new DBTransactionStateError(
	$this,
	"Cannot execute query from $fname while session state is out of sync",
	[],
	$this->csmError
	);
	}

	$this->transactionManager->assertSessionStatus( $this, $fname );

	if ( $verb !== 'ROLLBACK TO SAVEPOINT' ) {
	$this->transactionManager->assertTransactionStatus(
	$this,
	$this->deprecationLogger,
	$fname
	);
	}
	}

	/**
	* Determine how to handle a connection lost discovered during a query attempt
	*
	* This checks if explicit transactions, pending transaction writes, and important
	* session-level state (locks, temp tables) was lost. Point-in-time read snapshot loss
	* is considered acceptable for DBO_TRX logic.
	*
	* If state was lost, but that loss was discovered during a ROLLBACK that would have
	* destroyed that state anyway, treat the error as recoverable.
	*
	* @param string $verb SQL query verb
	* @param float $walltime How many seconds passes while attempting the query
	* @param CriticalSessionInfo $priorSessInfo Session state just before the query
	* @return int Recovery approach. One of the following ERR_* class constants:
	* - Database::ERR_RETRY_QUERY: reconnect silently, retry query
	* - Database::ERR_ABORT_QUERY: reconnect silently, do not retry query
	* - Database::ERR_ABORT_TRX: reconnect, throw error, enforce transaction rollback
	* - Database::ERR_ABORT_SESSION: reconnect, throw error, enforce session rollback
	*/
	private function assessConnectionLoss(
	string $verb,
	float $walltime,
	CriticalSessionInfo $priorSessInfo
	) {
	if ( $walltime < self::DROPPED_CONN_BLAME_THRESHOLD_SEC ) {
	// Query failed quickly; the connection was probably lost before the query was sent
	$res = self::ERR_RETRY_QUERY;
	} else {
	// Query took a long time; the connection was probably lost during query execution
	$res = self::ERR_ABORT_QUERY;
	}

	// List of problems causing session/transaction state corruption
	$blockers = [];
	// Loss of named locks breaks future callers relying on those locks for critical sections
	foreach ( $priorSessInfo->namedLocks as $lockName => $lockInfo ) {
	if ( $lockInfo['trxId'] && $lockInfo['trxId'] === $priorSessInfo->trxId ) {
	// Treat lost locks acquired during the lost transaction as a transaction state
	// problem. Connection loss on ROLLBACK (non-SAVEPOINT) is tolerable since
	// rollback automatically triggered server-side.
	if ( $verb !== 'ROLLBACK' ) {
	$res = max( $res, self::ERR_ABORT_TRX );
	$blockers[] = "named lock '$lockName'";
	}
	} else {
	// Treat lost locks acquired either during prior transactions or during no
	// transaction as a session state problem.
	$res = max( $res, self::ERR_ABORT_SESSION );
	$blockers[] = "named lock '$lockName'";
	}
	}
	// Loss of temp tables breaks future callers relying on those tables for queries
	foreach ( $priorSessInfo->tempTables as $domainTempTables ) {
	foreach ( $domainTempTables as $tableName => $tableInfo ) {
	if ( $tableInfo->trxId && $tableInfo->trxId === $priorSessInfo->trxId ) {
	// Treat lost temp tables created during the lost transaction as a
	// transaction state problem. Connection loss on ROLLBACK (non-SAVEPOINT)
	// is tolerable since rollback automatically triggered server-side.
	if ( $verb !== 'ROLLBACK' ) {
	$res = max( $res, self::ERR_ABORT_TRX );
	$blockers[] = "temp table '$tableName'";
	}
	} else {
	// Treat lost temp tables created either during prior transactions or during
	// no transaction as a session state problem.
	$res = max( $res, self::ERR_ABORT_SESSION );
	$blockers[] = "temp table '$tableName'";
	}
	}
	}
	// Loss of transaction writes breaks future callers and DBO_TRX logic relying on those
	// writes to be atomic and still pending. Connection loss on ROLLBACK (non-SAVEPOINT) is
	// tolerable since rollback automatically triggered server-side.
	if ( $priorSessInfo->trxWriteCallers && $verb !== 'ROLLBACK' ) {
	$res = max( $res, self::ERR_ABORT_TRX );
	$blockers[] = 'uncommitted writes';
	}
	if ( $priorSessInfo->trxPreCommitCbCallers && $verb !== 'ROLLBACK' ) {
	$res = max( $res, self::ERR_ABORT_TRX );
	$blockers[] = 'pre-commit callbacks';
	}
	if ( $priorSessInfo->trxExplicit && $verb !== 'ROLLBACK' && $verb !== 'COMMIT' ) {
	// Transaction automatically rolled back, breaking the expectations of callers
	// relying on the continued existence of that transaction for things like atomic
	// writes, serializability, or reads from the same point-in-time snapshot. If the
	// connection loss occured on ROLLBACK (non-SAVEPOINT) or COMMIT, then we do not
	// need to mark the transaction state as corrupt, since no transaction would still
	// be open even if the query did succeed (T127428).
	$res = max( $res, self::ERR_ABORT_TRX );
	$blockers[] = 'explicit transaction';
	}

	if ( $blockers ) {
	$this->logger->warning(
	"cannot reconnect to {db_server} silently: {error}",
	$this->getLogContext( [
	'error' => 'session state loss (' . implode( ', ', $blockers ) . ')',
	'exception' => new RuntimeException(),
	'db_log_category' => 'connection'
	] )
	);
	}

	return $res;
	}

	/**
	* Clean things up after session (and thus transaction) loss before reconnect
	*/
	private function handleSessionLossPreconnect() {
	// Clean up tracking of session-level things...
	// https://mariadb.com/kb/en/create-table/#create-temporary-table
	// https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
	$this->sessionTempTables = [];
	// https://mariadb.com/kb/en/get_lock/
	// https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
	$this->sessionNamedLocks = [];
	// Session loss implies transaction loss (T67263)
	$this->transactionManager->onSessionLoss( $this );
	// Clear additional subclass fields
	$this->doHandleSessionLossPreconnect();
	}

	/**
	* Reset any additional subclass trx* and session* fields
	*/
	protected function doHandleSessionLossPreconnect() {
	// no-op
	}

	/**
	* Checks whether the cause of the error is detected to be a timeout.
	*
	* It returns false by default, and not all engines support detecting this yet.
	* If this returns false, it will be treated as a generic query error.
	*
	* @param int\|string $errno Error number
	* @return bool
	* @since 1.39
	*/
	protected function isQueryTimeoutError( $errno ) {
	return false;
	}

	/**
	* Report a query error
	*
	* If $ignore is set, emit a DEBUG level log entry and continue,
	* otherwise, emit an ERROR level log entry and throw an exception.
	*
	* @param string $error
	* @param int\|string $errno
	* @param string $sql
	* @param string $fname
	* @param bool $ignore Whether to just log an error rather than throw an exception
	* @throws DBQueryError
	*/
	public function reportQueryError( $error, $errno, $sql, $fname, $ignore = false ) {
	if ( $ignore ) {
	$this->logger->debug(
	"SQL ERROR (ignored): $error",
	[ 'db_log_category' => 'query' ]
	);
	} else {
	throw $this->getQueryExceptionAndLog( $error, $errno, $sql, $fname );
	}
	}

	/**
	* @param string $error
	* @param string\|int $errno
	* @param string $sql
	* @param string $fname
	* @return DBError
	*/
	private function getQueryExceptionAndLog( $error, $errno, $sql, $fname ) {
	// Information that instances of the same problem have in common should
	// not be normalized (T255202).
	$this->logger->error(
	"Error $errno from $fname, {error} {sql1line} {db_server}",
	$this->getLogContext( [
	'method' => __METHOD__,
	'errno' => $errno,
	'error' => $error,
	'sql1line' => mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 ),
	'fname' => $fname,
	'db_log_category' => 'query',
	'exception' => new RuntimeException()
	] )
	);
	return $this->getQueryException( $error, $errno, $sql, $fname );
	}

	/**
	* @param string $error
	* @param string\|int $errno
	* @param string $sql
	* @param string $fname
	* @return DBError
	*/
	private function getQueryException( $error, $errno, $sql, $fname ) {
	if ( $this->isQueryTimeoutError( $errno ) ) {
	return new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
	} elseif ( $this->isConnectionError( $errno ) ) {
	return new DBQueryDisconnectedError( $this, $error, $errno, $sql, $fname );
	} else {
	return new DBQueryError( $this, $error, $errno, $sql, $fname );
	}
	}

	/**
	* @param string $error
	* @return DBConnectionError
	*/
	final protected function newExceptionAfterConnectError( $error ) {
	// Connection was not fully initialized and is not safe for use.
	// Stash any error associated with the handle before destroying it.
	$this->lastConnectError = $error;
	$this->conn = null;

	$this->logger->error(
	"Error connecting to {db_server} as user {db_user}: {error}",
	$this->getLogContext( [
	'error' => $error,
	'exception' => new RuntimeException(),
	'db_log_category' => 'connection',
	] )
	);

	return new DBConnectionError( $this, $error );
	}

	/**
	* Get a SelectQueryBuilder bound to this connection. This is overridden by
	* DBConnRef.
	*/
	public function newSelectQueryBuilder(): SelectQueryBuilder {
	return new SelectQueryBuilder( $this );
	}

	/**
	* Get a UnionQueryBuilder bound to this connection. This is overridden by
	* DBConnRef.
	*/
	public function newUnionQueryBuilder(): UnionQueryBuilder {
	return new UnionQueryBuilder( $this );
	}

	/**
	* Get an UpdateQueryBuilder bound to this connection. This is overridden by
	* DBConnRef.
	*/
	public function newUpdateQueryBuilder(): UpdateQueryBuilder {
	return new UpdateQueryBuilder( $this );
	}

	/**
	* Get a DeleteQueryBuilder bound to this connection. This is overridden by
	* DBConnRef.
	*/
	public function newDeleteQueryBuilder(): DeleteQueryBuilder {
	return new DeleteQueryBuilder( $this );
	}

	/**
	* Get a InsertQueryBuilder bound to this connection. This is overridden by
	* DBConnRef.
	*/
	public function newInsertQueryBuilder(): InsertQueryBuilder {
	return new InsertQueryBuilder( $this );
	}

	/**
	* Get a ReplaceQueryBuilder bound to this connection. This is overridden by
	* DBConnRef.
	*/
	public function newReplaceQueryBuilder(): ReplaceQueryBuilder {
	return new ReplaceQueryBuilder( $this );
	}

	/** @inheritDoc */
	public function selectField(
	$tables, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
	) {
	if ( $var === '*' ) {
	throw new DBUnexpectedError( $this, "Cannot use a * field" );
	} elseif ( is_array( $var ) && count( $var ) !== 1 ) {
	throw new DBUnexpectedError( $this, 'Cannot use more than one field' );
	}

	$options = $this->platform->normalizeOptions( $options );
	$options['LIMIT'] = 1;

	$res = $this->select( $tables, $var, $cond, $fname, $options, $join_conds );
	if ( $res === false ) {
	throw new DBUnexpectedError( $this, "Got false from select()" );
	}

	$row = $res->fetchRow();
	if ( $row === false ) {
	return false;
	}

	return reset( $row );
	}

	/** @inheritDoc */
	public function selectFieldValues(
	$tables, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
	): array {
	if ( $var === '*' ) {
	throw new DBUnexpectedError( $this, "Cannot use a * field" );
	} elseif ( !is_string( $var ) ) {
	throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
	}

	$options = $this->platform->normalizeOptions( $options );
	$res = $this->select( $tables, [ 'value' => $var ], $cond, $fname, $options, $join_conds );
	if ( $res === false ) {
	throw new DBUnexpectedError( $this, "Got false from select()" );
	}

	$values = [];
	foreach ( $res as $row ) {
	$values[] = $row->value;
	}

	return $values;
	}

	/** @inheritDoc */
	public function select(
	$tables, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
	) {
	$options = (array)$options;
	// Don't turn this into using platform directly, DatabaseMySQL overrides this.
	$sql = $this->selectSQLText( $tables, $vars, $conds, $fname, $options, $join_conds );
	// Treat SELECT queries with FOR UPDATE as writes. This matches
	// how MySQL enforces read_only (FOR SHARE and LOCK IN SHADE MODE are allowed).
	$flags = in_array( 'FOR UPDATE', $options, true )
	? self::QUERY_CHANGE_ROWS
	: self::QUERY_CHANGE_NONE;

	$query = new Query( $sql, $flags, 'SELECT' );
	return $this->query( $query, $fname );
	}

	/** @inheritDoc */
	public function selectRow( $tables, $vars, $conds, $fname = __METHOD__,
	$options = [], $join_conds = []
	) {
	$options = (array)$options;
	$options['LIMIT'] = 1;

	$res = $this->select( $tables, $vars, $conds, $fname, $options, $join_conds );
	if ( $res === false ) {
	throw new DBUnexpectedError( $this, "Got false from select()" );
	}

	if ( !$res->numRows() ) {
	return false;
	}

	return $res->fetchObject();
	}

	/**
	* @inheritDoc
	*/
	public function estimateRowCount(
	$tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
	): int {
	$conds = $this->platform->normalizeConditions( $conds, $fname );
	$column = $this->platform->extractSingleFieldFromList( $var );
	if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
	$conds[] = "$column IS NOT NULL";
	}

	$res = $this->select(
	$tables, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
	);
	$row = $res ? $res->fetchRow() : [];

	return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
	}

	/** @inheritDoc */
	public function selectRowCount(
	$tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
	): int {
	$conds = $this->platform->normalizeConditions( $conds, $fname );
	$column = $this->platform->extractSingleFieldFromList( $var );
	if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
	$conds[] = "$column IS NOT NULL";
	}
	if ( in_array( 'DISTINCT', (array)$options ) ) {
	if ( $column === null ) {
	throw new DBUnexpectedError( $this,
	'$var cannot be empty when the DISTINCT option is given' );
	}
	$innerVar = $column;
	} else {
	$innerVar = '1';
	}

	$res = $this->select(
	[
	'tmp_count' => $this->platform->buildSelectSubquery(
	$tables,
	$innerVar,
	$conds,
	$fname,
	$options,
	$join_conds
	)
	],
	[ 'rowcount' => 'COUNT(*)' ],
	[],
	$fname
	);
	$row = $res ? $res->fetchRow() : [];

	return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
	}

	/** @inheritDoc */
	public function lockForUpdate(
	$table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
	) {
	if ( !$this->trxLevel() && !$this->flagsHolder->hasImplicitTrxFlag() ) {
	throw new DBUnexpectedError(
	$this,
	__METHOD__ . ': no transaction is active nor is DBO_TRX set'
	);
	}

	$options = (array)$options;
	$options[] = 'FOR UPDATE';

	return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
	}

	/** @inheritDoc */
	public function fieldExists( $table, $field, $fname = __METHOD__ ) {
	$info = $this->fieldInfo( $table, $field );

	return (bool)$info;
	}

	/** @inheritDoc */
	abstract public function tableExists( $table, $fname = __METHOD__ );

	/** @inheritDoc */
	public function indexExists( $table, $index, $fname = __METHOD__ ) {
	$info = $this->indexInfo( $table, $index, $fname );

	return (bool)$info;
	}

	/** @inheritDoc */
	public function indexUnique( $table, $index, $fname = __METHOD__ ) {
	$info = $this->indexInfo( $table, $index, $fname );

	return $info ? $info['unique'] : null;
	}

	/** @inheritDoc */
	abstract public function getPrimaryKeyColumns( $table, $fname = __METHOD__ );

	/**
	* Get information about an index into an object
	*
	* @param string $table The unqualified name of a table
	* @param string $index Index name
	* @param string $fname Calling function name
	* @return array<string,mixed>\|false Index info map; false if it does not exist
	* @phan-return array{unique:bool}\|false
	*/
	abstract public function indexInfo( $table, $index, $fname = __METHOD__ );

	/** @inheritDoc */
	public function insert( $table, $rows, $fname = __METHOD__, $options = [] ) {
	$query = $this->platform->dispatchingInsertSqlText( $table, $rows, $options );
	if ( !$query ) {
	return true;
	}
	$this->query( $query, $fname );
	if ( $this->strictWarnings ) {
	$this->checkInsertWarnings( $query, $fname );
	}
	return true;
	}

	/**
	* Check for warnings after performing an INSERT query, and throw exceptions
	* if necessary.
	*
	* @param Query $query
	* @param string $fname
	* @return void
	*/
	protected function checkInsertWarnings( Query $query, $fname ) {
	}

	/** @inheritDoc */
	public function update( $table, $set, $conds, $fname = __METHOD__, $options = [] ) {
	$query = $this->platform->updateSqlText( $table, $set, $conds, $options );
	$this->query( $query, $fname );

	return true;
	}

	/** @inheritDoc */
	public function databasesAreIndependent() {
	return false;
	}

	/** @inheritDoc */
	final public function selectDomain( $domain ) {
	$cs = $this->commenceCriticalSection( __METHOD__ );

	try {
	$this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
	} catch ( DBError $e ) {
	$this->completeCriticalSection( __METHOD__, $cs );
	throw $e;
	}

	$this->completeCriticalSection( __METHOD__, $cs );
	}

	/**
	* @param DatabaseDomain $domain
	* @throws DBConnectionError
	* @throws DBError
	* @since 1.32
	*/
	protected function doSelectDomain( DatabaseDomain $domain ) {
	$this->currentDomain = $domain;
	$this->platform->setCurrentDomain( $this->currentDomain );
	}

	/** @inheritDoc */
	public function getDBname() {
	return $this->currentDomain->getDatabase();
	}

	/** @inheritDoc */
	public function getServer() {
	return $this->connectionParams[self::CONN_HOST] ?? null;
	}

	/** @inheritDoc */
	public function getServerName() {
	return $this->serverName ?? $this->getServer() ?? 'unknown';
	}

	/** @inheritDoc */
	public function addQuotes( $s ) {
	if ( $s instanceof RawSQLValue ) {
	return $s->toSql();
	}
	if ( $s instanceof Blob ) {
	$s = $s->fetch();
	}
	if ( $s === null ) {
	return 'NULL';
	} elseif ( is_bool( $s ) ) {
	return (string)(int)$s;
	} elseif ( is_int( $s ) ) {
	return (string)$s;
	} else {
	return "'" . $this->strencode( $s ) . "'";
	}
	}

	/** @inheritDoc */
	public function expr( string $field, string $op, $value ): Expression {
	return new Expression( $field, $op, $value );
	}

	/** @inheritDoc */
	public function andExpr( array $conds ): AndExpressionGroup {
	return AndExpressionGroup::newFromArray( $conds );
	}

	/** @inheritDoc */
	public function orExpr( array $conds ): OrExpressionGroup {
	return OrExpressionGroup::newFromArray( $conds );
	}

	/** @inheritDoc */
	public function replace( $table, $uniqueKeys, $rows, $fname = __METHOD__ ) {
	$uniqueKey = $this->platform->normalizeUpsertParams( $uniqueKeys, $rows );
	if ( !$rows ) {
	return;
	}
	$affectedRowCount = 0;
	$insertId = null;
	$this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
	try {
	foreach ( $rows as $row ) {
	// Delete any conflicting rows (including ones inserted from $rows)
	$query = $this->platform->deleteSqlText(
	$table,
	[ $this->platform->makeKeyCollisionCondition( [ $row ], $uniqueKey ) ]
	);
	$this->query( $query, $fname );
	// Insert the new row
	$query = $this->platform->dispatchingInsertSqlText( $table, $row, [] );
	$this->query( $query, $fname );
	$affectedRowCount += $this->lastQueryAffectedRows;
	$insertId = $insertId ?: $this->lastQueryInsertId;
	}
	$this->endAtomic( $fname );
	} catch ( DBError $e ) {
	$this->cancelAtomic( $fname );
	throw $e;
	}
	$this->lastEmulatedAffectedRows = $affectedRowCount;
	$this->lastEmulatedInsertId = $insertId;
	}

	/** @inheritDoc */
	public function upsert( $table, array $rows, $uniqueKeys, array $set, $fname = __METHOD__ ) {
	$uniqueKey = $this->platform->normalizeUpsertParams( $uniqueKeys, $rows );
	if ( !$rows ) {
	return true;
	}
	$this->platform->assertValidUpsertSetArray( $set, $uniqueKey, $rows );

	$encTable = $this->tableName( $table );
	$sqlColumnAssignments = $this->makeList( $set, self::LIST_SET );
	// Get any AUTO_INCREMENT/SERIAL column for this table so we can set insertId()
	$autoIncrementColumn = $this->getInsertIdColumnForUpsert( $table );
	// Check if there is a SQL assignment expression in $set (as generated by SQLPlatform::buildExcludedValue)
	$useWith = (bool)array_filter(
	$set,
	static function ( $v, $k ) {
	return $v instanceof RawSQLValue \|\| is_int( $k );
	},
	ARRAY_FILTER_USE_BOTH
	);
	// Subclasses might need explicit type casting within "WITH...AS (VALUES ...)"
	// so that these CTE rows can be referenced within the SET clause assigments.
	$typeByColumn = $useWith ? $this->getValueTypesForWithClause( $table ) : [];

	$first = true;
	$affectedRowCount = 0;
	$insertId = null;
	$this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
	try {
	foreach ( $rows as $row ) {
	// Update any existing conflicting row (including ones inserted from $rows)
	[ $sqlColumns, $sqlTuples, $sqlVals ] = $this->platform->makeInsertLists(
	[ $row ],
	'__',
	$typeByColumn
	);
	$sqlConditions = $this->platform->makeKeyCollisionCondition(
	[ $row ],
	$uniqueKey
	);
	$query = new Query(
	( $useWith ? "WITH __VALS ($sqlVals) AS (VALUES $sqlTuples) " : "" ) .
	"UPDATE $encTable SET $sqlColumnAssignments " .
	"WHERE ($sqlConditions)",
	self::QUERY_CHANGE_ROWS,
	'UPDATE',
	$table
	);
	$this->query( $query, $fname );
	$rowsUpdated = $this->lastQueryAffectedRows;
	$affectedRowCount += $rowsUpdated;
	if ( $rowsUpdated > 0 ) {
	// Conflicting row found and updated
	if ( $first && $autoIncrementColumn !== null ) {
	// @TODO: use "RETURNING" instead (when supported by SQLite)
	$query = new Query(
	"SELECT $autoIncrementColumn AS id FROM $encTable " .
	"WHERE ($sqlConditions)",
	self::QUERY_CHANGE_NONE,
	'SELECT'
	);
	$sRes = $this->query( $query, $fname, self::QUERY_CHANGE_ROWS );
	$insertId = (int)$sRes->fetchRow()['id'];
	}
	} else {
	// No conflicting row found
	$query = new Query(
	"INSERT INTO $encTable ($sqlColumns) VALUES $sqlTuples",
	self::QUERY_CHANGE_ROWS,
	'INSERT',
	$table
	);
	$this->query( $query, $fname );
	$affectedRowCount += $this->lastQueryAffectedRows;
	}
	$first = false;
	}
	$this->endAtomic( $fname );
	} catch ( DBError $e ) {
	$this->cancelAtomic( $fname );
	throw $e;
	}
	$this->lastEmulatedAffectedRows = $affectedRowCount;
	$this->lastEmulatedInsertId = $insertId;
	return true;
	}

	/**
	* @param string $table The unqualified name of a table
	* @return string\|null The AUTO_INCREMENT/SERIAL column; null if not needed
	*/
	protected function getInsertIdColumnForUpsert( $table ) {
	return null;
	}

	/**
	* @param string $table The unqualified name of a table
	* @return array<string,string> Map of (column => type); [] if not needed
	*/
	protected function getValueTypesForWithClause( $table ) {
	return [];
	}

	/** @inheritDoc */
	public function deleteJoin(
	$delTable,
	$joinTable,
	$delVar,
	$joinVar,
	$conds,
	$fname = __METHOD__
	) {
	$sql = $this->platform->deleteJoinSqlText( $delTable, $joinTable, $delVar, $joinVar, $conds );
	$query = new Query( $sql, self::QUERY_CHANGE_ROWS, 'DELETE', $delTable );
	$this->query( $query, $fname );
	}

	/** @inheritDoc */
	public function delete( $table, $conds, $fname = __METHOD__ ) {
	$this->query( $this->platform->deleteSqlText( $table, $conds ), $fname );

	return true;
	}

	/** @inheritDoc */
	final public function insertSelect(
	$destTable,
	$srcTable,
	$varMap,
	$conds,
	$fname = __METHOD__,
	$insertOptions = [],
	$selectOptions = [],
	$selectJoinConds = []
	) {
	static $hints = [ 'NO_AUTO_COLUMNS' ];

	$insertOptions = $this->platform->normalizeOptions( $insertOptions );
	$selectOptions = $this->platform->normalizeOptions( $selectOptions );

	if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions, $fname ) ) {
	// For massive migrations with downtime, we don't want to select everything
	// into memory and OOM, so do all this native on the server side if possible.
	$this->doInsertSelectNative(
	$destTable,
	$srcTable,
	$varMap,
	$conds,
	$fname,
	array_diff( $insertOptions, $hints ),
	$selectOptions,
	$selectJoinConds
	);
	} else {
	$this->doInsertSelectGeneric(
	$destTable,
	$srcTable,
	$varMap,
	$conds,
	$fname,
	array_diff( $insertOptions, $hints ),
	$selectOptions,
	$selectJoinConds
	);
	}

	return true;
	}

	/**
	* @param array $insertOptions
	* @param array $selectOptions
	* @param string $fname
	* @return bool Whether an INSERT SELECT with these options will be replication safe
	* @since 1.31
	*/
	protected function isInsertSelectSafe( array $insertOptions, array $selectOptions, $fname ) {
	return true;
	}

	/**
	* Implementation of insertSelect() based on select() and insert()
	*
	* @see IDatabase::insertSelect()
	* @param string $destTable Unqualified name of destination table
	* @param string\|array $srcTable Unqualified name of source table
	* @param array $varMap
	* @param array $conds
	* @param string $fname
	* @param array $insertOptions
	* @param array $selectOptions
	* @param array $selectJoinConds
	* @since 1.35
	*/
	private function doInsertSelectGeneric(
	$destTable,
	$srcTable,
	array $varMap,
	$conds,
	$fname,
	array $insertOptions,
	array $selectOptions,
	$selectJoinConds
	) {
	// For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
	// on only the primary DB (without needing row-based-replication). It also makes it easy to
	// know how big the INSERT is going to be.
	$fields = [];
	foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
	$fields[] = $this->platform->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
	}
	$res = $this->select(
	$srcTable,
	implode( ',', $fields ),
	$conds,
	$fname,
	array_merge( $selectOptions, [ 'FOR UPDATE' ] ),
	$selectJoinConds
	);

	$affectedRowCount = 0;
	$insertId = null;
	if ( $res ) {
	$this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
	try {
	$rows = [];
	foreach ( $res as $row ) {
	$rows[] = (array)$row;
	}
	// Avoid inserts that are too huge
	$rowBatches = array_chunk( $rows, $this->nonNativeInsertSelectBatchSize );
	foreach ( $rowBatches as $rows ) {
	$query = $this->platform->dispatchingInsertSqlText( $destTable, $rows, $insertOptions );
	$this->query( $query, $fname );
	$affectedRowCount += $this->lastQueryAffectedRows;
	$insertId = $insertId ?: $this->lastQueryInsertId;
	}
	$this->endAtomic( $fname );
	} catch ( DBError $e ) {
	$this->cancelAtomic( $fname );
	throw $e;
	}
	}
	$this->lastEmulatedAffectedRows = $affectedRowCount;
	$this->lastEmulatedInsertId = $insertId;
	}

	/**
	* Native server-side implementation of insertSelect() for situations where
	* we don't want to select everything into memory
	*
	* @see IDatabase::insertSelect()
	* @param string $destTable The unqualified name of destination table
	* @param string\|array $srcTable The unqualified name of source table
	* @param array $varMap
	* @param array $conds
	* @param string $fname
	* @param array $insertOptions
	* @param array $selectOptions
	* @param array $selectJoinConds
	* @since 1.35
	*/
	protected function doInsertSelectNative(
	$destTable,
	$srcTable,
	array $varMap,
	$conds,
	$fname,
	array $insertOptions,
	array $selectOptions,
	$selectJoinConds
	) {
	$sql = $this->platform->insertSelectNativeSqlText(
	$destTable,
	$srcTable,
	$varMap,
	$conds,
	$fname,
	$insertOptions,
	$selectOptions,
	$selectJoinConds
	);
	$query = new Query(
	$sql,
	self::QUERY_CHANGE_ROWS,
	'INSERT',
	$destTable
	);
	$this->query( $query, $fname );
	}

	/**
	* Do not use this method outside of Database/DBError classes
	*
	* @param int\|string $errno
	* @return bool Whether the given query error was a connection drop
	* @since 1.38
	*/
	protected function isConnectionError( $errno ) {
	return false;
	}

	/**
	* @param int\|string $errno
	* @return bool Whether it is known that the last query error only caused statement rollback
	* @note This is for backwards compatibility for callers catching DBError exceptions in
	* order to ignore problems like duplicate key errors or foreign key violations
	* @since 1.39
	*/
	protected function isKnownStatementRollbackError( $errno ) {
	return false; // don't know; it could have caused a transaction rollback
	}

	/**
	* @inheritDoc
	*/
	public function serverIsReadOnly() {
	return false;
	}

	/** @inheritDoc */
	final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
	$this->transactionManager->onTransactionResolution( $this, $callback, $fname );
	}

	/** @inheritDoc */
	final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
	if ( !$this->trxLevel() && $this->getTransactionRoundFname() !== null ) {
	// This DB handle is set to participate in LoadBalancer transaction rounds and
	// an explicit transaction round is active. Start an implicit transaction on this
	// DB handle (setting trxAutomatic) similar to how query() does in such situations.
	$this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
	}

	$this->transactionManager->addPostCommitOrIdleCallback( $callback, $fname );
	if ( !$this->trxLevel() ) {
	$dbErrors = [];
	$this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE, $dbErrors );
	if ( $dbErrors ) {
	throw $dbErrors[0];
	}
	}
	}

	/** @inheritDoc */
	final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
	if ( !$this->trxLevel() && $this->getTransactionRoundFname() !== null ) {
	// This DB handle is set to participate in LoadBalancer transaction rounds and
	// an explicit transaction round is active. Start an implicit transaction on this
	// DB handle (setting trxAutomatic) similar to how query() does in such situations.
	$this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
	}

	if ( $this->trxLevel() ) {
	$this->transactionManager->addPreCommitOrIdleCallback(
	$callback,
	$fname
	);
	} else {
	// No transaction is active nor will start implicitly, so make one for this callback
	$this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
	try {
	$callback( $this );
	} catch ( Throwable $e ) {
	// Avoid confusing error reporting during critical section errors
	if ( !$this->csmError ) {
	$this->cancelAtomic( __METHOD__ );
	}
	throw $e;
	}
	$this->endAtomic( __METHOD__ );
	}
	}

	/** @inheritDoc */
	final public function setTransactionListener( $name, ?callable $callback = null ) {
	$this->transactionManager->setTransactionListener( $name, $callback );
	}

	/**
	* Whether to disable running of post-COMMIT/ROLLBACK callbacks
	*
	* @internal This method should not be used outside of Database/LoadBalancer
	*
	* @since 1.28
	* @param bool $suppress
	*/
	final public function setTrxEndCallbackSuppression( $suppress ) {
	$this->transactionManager->setTrxEndCallbackSuppression( $suppress );
	}

	/**
	* Consume and run any "on transaction idle/resolution" callbacks
	*
	* @internal This method should not be used outside of Database/LoadBalancer
	*
	* @since 1.20
	* @param int $trigger IDatabase::TRIGGER_* constant
	* @param DBError[] &$errors DB exceptions caught [returned]
	* @return int Number of callbacks attempted
	* @throws DBUnexpectedError
	* @throws Throwable Any non-DBError exception thrown by a callback
	*/
	public function runOnTransactionIdleCallbacks( $trigger, array &$errors = [] ) {
	if ( $this->trxLevel() ) {
	throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open' );
	}

	if ( $this->transactionManager->isEndCallbacksSuppressed() ) {
	// Execution deferred by LoadBalancer for explicit execution later
	return 0;
	}

	$cs = $this->commenceCriticalSection( __METHOD__ );

	$count = 0;
	$autoTrx = $this->flagsHolder->hasImplicitTrxFlag(); // automatic begin() enabled?
	// Drain the queues of transaction "idle" and "end" callbacks until they are empty
	do {
	$callbackEntries = $this->transactionManager->consumeEndCallbacks();
	$count += count( $callbackEntries );
	foreach ( $callbackEntries as $entry ) {
	$this->flagsHolder->clearFlag( self::DBO_TRX ); // make each query its own transaction
	try {
	$entry[0]( $trigger );
	} catch ( DBError $ex ) {
	( $this->errorLogger )( $ex );
	$errors[] = $ex;
	// Some callbacks may use startAtomic/endAtomic, so make sure
	// their transactions are ended so other callbacks don't fail
	if ( $this->trxLevel() ) {
	$this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
	}
	} finally {
	if ( $autoTrx ) {
	$this->flagsHolder->setFlag( self::DBO_TRX ); // restore automatic begin()
	} else {
	$this->flagsHolder->clearFlag( self::DBO_TRX ); // restore auto-commit
	}
	}
	}
	} while ( $this->transactionManager->countPostCommitOrIdleCallbacks() );

	$this->completeCriticalSection( __METHOD__, $cs );

	return $count;
	}

	/**
	* Actually run any "transaction listener" callbacks
	*
	* @internal This method should not be used outside of Database/LoadBalancer
	*
	* @since 1.20
	* @param int $trigger IDatabase::TRIGGER_* constant
	* @param DBError[] &$errors DB exceptions caught [returned]
	* @throws Throwable Any non-DBError exception thrown by a callback
	*/
	public function runTransactionListenerCallbacks( $trigger, array &$errors = [] ) {
	if ( $this->transactionManager->isEndCallbacksSuppressed() ) {
	// Execution deferred by LoadBalancer for explicit execution later
	return;
	}

	// These callbacks should only be registered in setup, thus no iteration is needed
	foreach ( $this->transactionManager->getRecurringCallbacks() as $callback ) {
	try {
	$callback( $trigger, $this );
	} catch ( DBError $ex ) {
	( $this->errorLogger )( $ex );
	$errors[] = $ex;
	}
	}
	}

	/**
	* Handle "on transaction idle/resolution" and "transaction listener" callbacks post-COMMIT
	*
	* @throws DBError The first DBError exception thrown by a callback
	* @throws Throwable Any non-DBError exception thrown by a callback
	*/
	private function runTransactionPostCommitCallbacks() {
	$dbErrors = [];
	$this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT, $dbErrors );
	$this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT, $dbErrors );
	$this->lastEmulatedAffectedRows = 0; // for the sake of consistency
	if ( $dbErrors ) {
	throw $dbErrors[0];
	}
	}

	/**
	* Handle "on transaction idle/resolution" and "transaction listener" callbacks post-ROLLBACK
	*
	* This will suppress and log any DBError exceptions
	*
	* @throws Throwable Any non-DBError exception thrown by a callback
	*/
	private function runTransactionPostRollbackCallbacks() {
	$this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
	$this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
	$this->lastEmulatedAffectedRows = 0; // for the sake of consistency
	}

	/** @inheritDoc */
	final public function startAtomic(
	$fname = __METHOD__,
	$cancelable = self::ATOMIC_NOT_CANCELABLE
	) {
	$cs = $this->commenceCriticalSection( __METHOD__ );

	if ( $this->trxLevel() ) {
	// This atomic section is only one part of a larger transaction
	$sectionOwnsTrx = false;
	} else {
	// Start an implicit transaction (sets trxAutomatic)
	try {
	$this->begin( $fname, self::TRANSACTION_INTERNAL );
	} catch ( DBError $e ) {
	$this->completeCriticalSection( __METHOD__, $cs );
	throw $e;
	}
	if ( $this->flagsHolder->hasImplicitTrxFlag() ) {
	// This DB handle participates in LoadBalancer transaction rounds; all atomic
	// sections should be buffered into one transaction (e.g. to keep web requests
	// transactional). Note that an implicit transaction round is considered to be
	// active when no there is no explicit transaction round.
	$sectionOwnsTrx = false;
	} else {
	// This DB handle does not participate in LoadBalancer transaction rounds;
	// each topmost atomic section will use its own transaction.
	$sectionOwnsTrx = true;
	}
	$this->transactionManager->setAutomaticAtomic( $sectionOwnsTrx );
	}

	if ( $cancelable === self::ATOMIC_CANCELABLE ) {
	if ( $sectionOwnsTrx ) {
	// This atomic section is synonymous with the whole transaction; just
	// use full COMMIT/ROLLBACK in endAtomic()/cancelAtomic(), respectively
	$savepointId = self::NOT_APPLICABLE;
	} else {
	// This atomic section is only part of the whole transaction; use a SAVEPOINT
	// query so that its changes can be cancelled without losing the rest of the
	// transaction (e.g. changes from other sections or from outside of sections)
	try {
	$savepointId = $this->transactionManager->nextSavePointId( $this, $fname );
	$sql = $this->platform->savepointSqlText( $savepointId );
	$query = new Query( $sql, self::QUERY_CHANGE_TRX, 'SAVEPOINT' );
	$this->query( $query, $fname );
	} catch ( DBError $e ) {
	$this->completeCriticalSection( __METHOD__, $cs, $e );
	throw $e;
	}
	}
	} else {
	$savepointId = null;
	}

	$sectionId = new AtomicSectionIdentifier;
	$this->transactionManager->addToAtomicLevels( $fname, $sectionId, $savepointId );

	$this->completeCriticalSection( __METHOD__, $cs );

	return $sectionId;
	}

	/** @inheritDoc */
	final public function endAtomic( $fname = __METHOD__ ) {
	[ $savepointId, $sectionId ] = $this->transactionManager->onEndAtomic( $this, $fname );

	$runPostCommitCallbacks = false;

	$cs = $this->commenceCriticalSection( __METHOD__ );

	// Remove the last section (no need to re-index the array)
	$finalLevelOfImplicitTrxPopped = $this->transactionManager->popAtomicLevel();

	try {
	if ( $finalLevelOfImplicitTrxPopped ) {
	$this->commit( $fname, self::FLUSHING_INTERNAL );
	$runPostCommitCallbacks = true;
	} elseif ( $savepointId !== null && $savepointId !== self::NOT_APPLICABLE ) {
	$sql = $this->platform->releaseSavepointSqlText( $savepointId );
	$query = new Query( $sql, self::QUERY_CHANGE_TRX, 'RELEASE SAVEPOINT' );
	$this->query( $query, $fname );
	}
	} catch ( DBError $e ) {
	$this->completeCriticalSection( __METHOD__, $cs, $e );
	throw $e;
	}

	$this->transactionManager->onEndAtomicInCriticalSection( $sectionId );

	$this->completeCriticalSection( __METHOD__, $cs );

	if ( $runPostCommitCallbacks ) {
	$this->runTransactionPostCommitCallbacks();
	}
	}

	/** @inheritDoc */
	final public function cancelAtomic(
	$fname = __METHOD__,
	?AtomicSectionIdentifier $sectionId = null
	) {
	$this->transactionManager->onCancelAtomicBeforeCriticalSection( $this, $fname );
	$pos = $this->transactionManager->getPositionFromSectionId( $sectionId );
	if ( $pos < 0 ) {
	throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
	}

	$cs = $this->commenceCriticalSection( __METHOD__ );
	$runPostRollbackCallbacks = false;
	[ $savedFname, $excisedSectionIds, $newTopSectionId, $savedSectionId, $savepointId ] =
	$this->transactionManager->cancelAtomic( $pos );

	try {
	if ( $savedFname !== $fname ) {
	$e = new DBUnexpectedError(
	$this,
	"Invalid atomic section ended (got $fname but expected $savedFname)"
	);
	$this->completeCriticalSection( __METHOD__, $cs, $e );
	throw $e;
	}

	// Remove the last section (no need to re-index the array)
	$this->transactionManager->popAtomicLevel();
	$excisedSectionIds[] = $savedSectionId;
	$newTopSectionId = $this->transactionManager->currentAtomicSectionId();

	if ( $savepointId !== null ) {
	// Rollback the transaction changes proposed within this atomic section
	if ( $savepointId === self::NOT_APPLICABLE ) {
	// Atomic section started the transaction; rollback the whole transaction
	// and trigger cancellation callbacks for all active atomic sections
	$this->rollback( $fname, self::FLUSHING_INTERNAL );
	$runPostRollbackCallbacks = true;
	} else {
	// Atomic section nested within the transaction; rollback the transaction
	// to the state prior to this section and trigger its cancellation callbacks
	$sql = $this->platform->rollbackToSavepointSqlText( $savepointId );
	$query = new Query( $sql, self::QUERY_CHANGE_TRX, 'ROLLBACK TO SAVEPOINT' );
	$this->query( $query, $fname );
	$this->transactionManager->setTrxStatusToOk(); // no exception; recovered
	}
	} else {
	// Put the transaction into an error state if it's not already in one
	$trxError = new DBUnexpectedError(
	$this,
	"Uncancelable atomic section canceled (got $fname)"
	);
	$this->transactionManager->setTransactionError( $trxError );
	}
	} finally {
	// Fix up callbacks owned by the sections that were just cancelled.
	// All callbacks should have an owner that is present in trxAtomicLevels.
	$this->transactionManager->modifyCallbacksForCancel(
	$excisedSectionIds,
	$newTopSectionId
	);
	}

	$this->lastEmulatedAffectedRows = 0; // for the sake of consistency

	$this->completeCriticalSection( __METHOD__, $cs );

	if ( $runPostRollbackCallbacks ) {
	$this->runTransactionPostRollbackCallbacks();
	}
	}

	/** @inheritDoc */
	final public function doAtomicSection(
	$fname,
	callable $callback,
	$cancelable = self::ATOMIC_NOT_CANCELABLE
	) {
	$sectionId = $this->startAtomic( $fname, $cancelable );
	try {
	$res = $callback( $this, $fname );
	} catch ( Throwable $e ) {
	// Avoid confusing error reporting during critical section errors
	if ( !$this->csmError ) {
	$this->cancelAtomic( $fname, $sectionId );
	}

	throw $e;
	}
	$this->endAtomic( $fname );

	return $res;
	}

	/** @inheritDoc */
	final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
	static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
	if ( !in_array( $mode, $modes, true ) ) {
	throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'" );
	}

	$this->transactionManager->onBegin( $this, $fname );

	if ( $this->flagsHolder->hasImplicitTrxFlag() && $mode !== self::TRANSACTION_INTERNAL ) {
	$msg = "$fname: implicit transaction expected (DBO_TRX set)";
	throw new DBUnexpectedError( $this, $msg );
	}

	$this->assertHasConnectionHandle();

	$cs = $this->commenceCriticalSection( __METHOD__ );
	$timeStart = microtime( true );
	try {
	$this->doBegin( $fname );
	} catch ( DBError $e ) {
	$this->completeCriticalSection( __METHOD__, $cs );
	throw $e;
	}
	$timeEnd = microtime( true );
	// Treat "BEGIN" as a trivial query to gauge the RTT delay
	$rtt = max( $timeEnd - $timeStart, 0.0 );
	$this->transactionManager->onBeginInCriticalSection( $mode, $fname, $rtt );
	$this->replicationReporter->resetReplicationLagStatus( $this );
	$this->completeCriticalSection( __METHOD__, $cs );
	}

	/**
	* Issues the BEGIN command to the database server.
	*
	* @see Database::begin()
	* @param string $fname
	* @throws DBError
	*/
	protected function doBegin( $fname ) {
	$query = new Query( 'BEGIN', self::QUERY_CHANGE_TRX, 'BEGIN' );
	$this->query( $query, $fname );
	}

	/** @inheritDoc */
	final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
	static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
	if ( !in_array( $flush, $modes, true ) ) {
	throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'" );
	}

	if ( !$this->transactionManager->onCommit( $this, $fname, $flush ) ) {
	return;
	}

	$this->assertHasConnectionHandle();

	$this->runOnTransactionPreCommitCallbacks();

	$cs = $this->commenceCriticalSection( __METHOD__ );
	try {
	if ( $this->trxLevel() ) {
	$query = new Query( 'COMMIT', self::QUERY_CHANGE_TRX, 'COMMIT' );
	$this->query( $query, $fname );
	}
	} catch ( DBError $e ) {
	$this->completeCriticalSection( __METHOD__, $cs );
	throw $e;
	}
	$lastWriteTime = $this->transactionManager->onCommitInCriticalSection( $this );
	if ( $lastWriteTime ) {
	$this->lastWriteTime = $lastWriteTime;
	}
	// With FLUSHING_ALL_PEERS, callbacks will run when requested by a dedicated phase
	// within LoadBalancer. With FLUSHING_INTERNAL, callbacks will run when requested by
	// the Database caller during a safe point. This avoids isolation and recursion issues.
	if ( $flush === self::FLUSHING_ONE ) {
	$this->runTransactionPostCommitCallbacks();
	}
	$this->completeCriticalSection( __METHOD__, $cs );
	}

	/** @inheritDoc */
	final public function rollback( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
	if (
	$flush !== self::FLUSHING_INTERNAL &&
	$flush !== self::FLUSHING_ALL_PEERS &&
	$this->flagsHolder->hasImplicitTrxFlag()
	) {
	throw new DBUnexpectedError(
	$this,
	"$fname: Expected mass rollback of all peer transactions (DBO_TRX set)"
	);
	}

	if ( !$this->trxLevel() ) {
	$this->transactionManager->setTrxStatusToNone();
	$this->transactionManager->clearPreEndCallbacks();
	if ( $this->transactionManager->trxLevel() === TransactionManager::STATUS_TRX_ERROR ) {
	$this->logger->info(
	"$fname: acknowledged server-side transaction loss on {db_server}",
	$this->getLogContext()
	);
	}

	return;
	}

	$this->assertHasConnectionHandle();

	if ( $this->csmError ) {
	// Since the session state is corrupt, we cannot just rollback the transaction
	// while preserving the non-transaction session state. The handle will remain
	// marked as corrupt until flushSession() is called to reset the connection
	// and deal with any remaining callbacks.
	$this->logger->info(
	"$fname: acknowledged client-side transaction loss on {db_server}",
	$this->getLogContext()
	);

	return;
	}

	$cs = $this->commenceCriticalSection( __METHOD__ );
	if ( $this->trxLevel() ) {
	// Disconnects cause rollback anyway, so ignore those errors
	$query = new Query(
	$this->platform->rollbackSqlText(),
	self::QUERY_SILENCE_ERRORS \| self::QUERY_CHANGE_TRX,
	'ROLLBACK'
	);
	$this->query( $query, $fname );
	}
	$this->transactionManager->onRollbackInCriticalSection( $this );
	// With FLUSHING_ALL_PEERS, callbacks will run when requested by a dedicated phase
	// within LoadBalancer. With FLUSHING_INTERNAL, callbacks will run when requested by
	// the Database caller during a safe point. This avoids isolation and recursion issues.
	if ( $flush === self::FLUSHING_ONE ) {
	$this->runTransactionPostRollbackCallbacks();
	}
	$this->completeCriticalSection( __METHOD__, $cs );
	}

	/**
	* @internal Only for tests and highly discouraged
	* @param TransactionManager $transactionManager
	*/
	public function setTransactionManager( TransactionManager $transactionManager ) {
	$this->transactionManager = $transactionManager;
	}

	/** @inheritDoc */
	public function flushSession( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
	if (
	$flush !== self::FLUSHING_INTERNAL &&
	$flush !== self::FLUSHING_ALL_PEERS &&
	$this->flagsHolder->hasImplicitTrxFlag()
	) {
	throw new DBUnexpectedError(
	$this,
	"$fname: Expected mass flush of all peer connections (DBO_TRX set)"
	);
	}

	if ( $this->csmError ) {
	// If a critical section error occurred, such as Excimer timeout exceptions raised
	// before a query response was marshalled, destroy the connection handle and reset
	// the session state tracking variables. The value of trxLevel() is irrelevant here,
	// and, in fact, might be 1 due to rollback() deferring critical section recovery.
	$this->logger->info(
	"$fname: acknowledged client-side session loss on {db_server}",
	$this->getLogContext()
	);
	$this->csmError = null;
	$this->csmFname = null;
	$this->replaceLostConnection( 2048, __METHOD__ );

	return;
	}

	if ( $this->trxLevel() ) {
	// Any existing transaction should have been rolled back already
	throw new DBUnexpectedError(
	$this,
	"$fname: transaction still in progress (not yet rolled back)"
	);
	}

	if ( $this->transactionManager->sessionStatus() === TransactionManager::STATUS_SESS_ERROR ) {
	// If the session state was already lost due to either an unacknowledged session
	// state loss error (e.g. dropped connection) or an explicit connection close call,
	// then there is nothing to do here. Note that in such cases, even temporary tables
	// and server-side config variables are lost (invocation of this method is assumed
	// to imply that such losses are tolerable).
	$this->logger->info(
	"$fname: acknowledged server-side session loss on {db_server}",
	$this->getLogContext()
	);
	} elseif ( $this->isOpen() ) {
	// Connection handle exists; server-side session state must be flushed
	$this->doFlushSession( $fname );
	$this->sessionNamedLocks = [];
	}

	$this->transactionManager->clearSessionError();
	}

	/**
	* Reset the server-side session state for named locks and table locks
	*
	* Connection and query errors will be suppressed and logged
	*
	* @param string $fname
	* @since 1.38
	*/
	protected function doFlushSession( $fname ) {
	// no-op
	}

	/** @inheritDoc */
	public function flushSnapshot( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
	$this->transactionManager->onFlushSnapshot(
	$this,
	$fname,
	$flush,
	$this->getTransactionRoundFname()
	);
	if (
	$this->transactionManager->sessionStatus() === TransactionManager::STATUS_SESS_ERROR \|\|
	$this->transactionManager->trxStatus() === TransactionManager::STATUS_TRX_ERROR
	) {
	$this->rollback( $fname, self::FLUSHING_INTERNAL );
	} else {
	$this->commit( $fname, self::FLUSHING_INTERNAL );
	}
	}

	/** @inheritDoc */
	public function duplicateTableStructure(
	$oldName,
	$newName,
	$temporary = false,
	$fname = __METHOD__
	) {
	throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
	}

	/** @inheritDoc */
	public function listTables( $prefix = null, $fname = __METHOD__ ) {
	throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
	}

	/** @inheritDoc */
	public function affectedRows() {
	$this->lastEmulatedAffectedRows ??= $this->lastQueryAffectedRows;

	return $this->lastEmulatedAffectedRows;
	}

	/** @inheritDoc */
	public function insertId() {
	if ( $this->lastEmulatedInsertId === null ) {
	// Guard against misuse of this method by checking affectedRows(). Note that calls
	// to insert() with "IGNORE" and calls to insertSelect() might not add any rows.
	if ( $this->affectedRows() ) {
	$this->lastEmulatedInsertId = $this->lastInsertId();
	} else {
	$this->lastEmulatedInsertId = 0;
	}
	}

	return $this->lastEmulatedInsertId;
	}

	/**
	* Get a row ID from the last insert statement to implicitly assign one within the session
	*
	* If the statement involved assigning sequence IDs to multiple rows, then the return value
	* will be any one of those values (database-specific). If the statement was an "UPSERT" and
	* some existing rows were updated, then the result will either reflect only IDs of created
	* rows or it will reflect IDs of both created and updated rows (this is database-specific).
	*
	* The result is unspecified if the statement gave an error.
	*
	* @return int Sequence ID, 0 (if none)
	* @throws DBError
	*/
	abstract protected function lastInsertId();

	/** @inheritDoc */
	public function ping() {
	if ( $this->isOpen() ) {
	// If the connection was recently used, assume that it is still good
	if ( ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
	return true;
	}
	// Send a trivial query to test the connection, triggering an automatic
	// reconnection attempt if the connection was lost
	$query = new Query(
	self::PING_QUERY,
	self::QUERY_IGNORE_DBO_TRX \| self::QUERY_SILENCE_ERRORS \| self::QUERY_CHANGE_NONE,
	'SELECT'
	);
	$res = $this->query( $query, __METHOD__ );
	$ok = ( $res !== false );
	} else {
	// Try to re-establish a connection
	$ok = $this->replaceLostConnection( null, __METHOD__ );
	}

	return $ok;
	}

	/**
	* Close any existing (dead) database connection and open a new connection
	*
	* @param int\|null $lastErrno
	* @param string $fname
	* @return bool True if new connection is opened successfully, false if error
	*/
	protected function replaceLostConnection( $lastErrno, $fname ) {
	if ( $this->conn ) {
	$this->closeConnection();
	$this->conn = null;
	$this->handleSessionLossPreconnect();
	}

	try {
	$this->open(
	$this->connectionParams[self::CONN_HOST],
	$this->connectionParams[self::CONN_USER],
	$this->connectionParams[self::CONN_PASSWORD],
	$this->currentDomain->getDatabase(),
	$this->currentDomain->getSchema(),
	$this->tablePrefix()
	);
	$this->lastPing = microtime( true );
	$ok = true;

	$this->logger->warning(
	$fname . ': lost connection to {db_server} with error {errno}; reconnected',
	$this->getLogContext( [
	'exception' => new RuntimeException(),
	'db_log_category' => 'connection',
	'errno' => $lastErrno
	] )
	);
	} catch ( DBConnectionError $e ) {
	$ok = false;

	$this->logger->error(
	$fname . ': lost connection to {db_server} with error {errno}; reconnection failed: {connect_msg}',
	$this->getLogContext( [
	'exception' => new RuntimeException(),
	'db_log_category' => 'connection',
	'errno' => $lastErrno,
	'connect_msg' => $e->getMessage()
	] )
	);
	}

	// Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
	// If callback suppression is set then the array will remain unhandled.
	$this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
	// Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener().
	// If callback suppression is set then the array will remain unhandled.
	$this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );

	return $ok;
	}

	/**
	* Merge the result of getSessionLagStatus() for several DBs
	* using the most pessimistic values to estimate the lag of
	* any data derived from them in combination
	*
	* This is information is useful for caching modules
	*
	* @see WANObjectCache::set()
	* @see WANObjectCache::getWithSetCallback()
	*
	* @param IReadableDatabase\|null ...$dbs
	* Note: For backward compatibility, it is allowed for null values
	* to be passed among the parameters. This is deprecated since 1.36,
	* only IReadableDatabase objects should be passed.
	*
	* @return array Map of values:
	* - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
	* - since: oldest UNIX timestamp of any of the DB lag estimates
	* - pending: whether any of the DBs have uncommitted changes
	* @throws DBError
	* @since 1.27
	*/
	public static function getCacheSetOptions( ?IReadableDatabase ...$dbs ) {
	$res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];

	foreach ( $dbs as $db ) {
	if ( $db instanceof IReadableDatabase ) {
	$status = $db->getSessionLagStatus();

	if ( $status['lag'] === false ) {
	$res['lag'] = false;
	} elseif ( $res['lag'] !== false ) {
	$res['lag'] = max( $res['lag'], $status['lag'] );
	}
	$res['since'] = min( $res['since'], $status['since'] );
	}

	if ( $db instanceof IDatabaseForOwner ) {
	$res['pending'] = $res['pending'] ?: $db->writesPending();
	}
	}

	return $res;
	}

	/** @inheritDoc */
	public function encodeBlob( $b ) {
	return $b;
	}

	/** @inheritDoc */
	public function decodeBlob( $b ) {
	if ( $b instanceof Blob ) {
	$b = $b->fetch();
	}
	return $b;
	}

	public function setSessionOptions( array $options ) {
	}

	/** @inheritDoc */
	public function sourceFile(
	$filename,
	?callable $lineCallback = null,
	?callable $resultCallback = null,
	$fname = false,
	?callable $inputCallback = null
	) {
	AtEase::suppressWarnings();
	$fp = fopen( $filename, 'r' );
	AtEase::restoreWarnings();

	if ( $fp === false ) {
	throw new RuntimeException( "Could not open \"{$filename}\"" );
	}

	if ( !$fname ) {
	$fname = __METHOD__ . "( $filename )";
	}

	try {
	return $this->sourceStream(
	$fp,
	$lineCallback,
	$resultCallback,
	$fname,
	$inputCallback
	);
	} finally {
	fclose( $fp );
	}
	}

	/** @inheritDoc */
	public function sourceStream(
	$fp,
	?callable $lineCallback = null,
	?callable $resultCallback = null,
	$fname = __METHOD__,
	?callable $inputCallback = null
	) {
	$delimiterReset = new ScopedCallback(
	function ( $delimiter ) {
	$this->delimiter = $delimiter;
	},
	[ $this->delimiter ]
	);
	$cmd = '';

	while ( !feof( $fp ) ) {
	if ( $lineCallback ) {
	$lineCallback();
	}

	$line = trim( fgets( $fp ) );

	if ( $line == '' ) {
	continue;
	}

	if ( $line[0] == '-' && $line[1] == '-' ) {
	continue;
	}

	if ( $cmd != '' ) {
	$cmd .= ' ';
	}

	$done = $this->streamStatementEnd( $cmd, $line );

	$cmd .= "$line\n";

	if ( $done \|\| feof( $fp ) ) {
	$cmd = $this->platform->replaceVars( $cmd );

	if ( $inputCallback ) {
	$callbackResult = $inputCallback( $cmd );

	if ( is_string( $callbackResult ) \|\| !$callbackResult ) {
	$cmd = $callbackResult;
	}
	}

	if ( $cmd ) {
	$res = $this->query( $cmd, $fname );

	if ( $resultCallback ) {
	$resultCallback( $res, $this );
	}

	if ( $res === false ) {
	$err = $this->lastError();

	return "Query \"{$cmd}\" failed with error code \"$err\".\n";
	}
	}
	$cmd = '';
	}
	}

	ScopedCallback::consume( $delimiterReset );
	return true;
	}

	/**
	* Called by sourceStream() to check if we've reached a statement end
	*
	* @param string &$sql SQL assembled so far
	* @param string &$newLine New line about to be added to $sql
	* @return bool Whether $newLine contains end of the statement
	*/
	public function streamStatementEnd( &$sql, &$newLine ) {
	if ( $this->delimiter ) {
	$prev = $newLine;
	$newLine = preg_replace(
	'/' . preg_quote( $this->delimiter, '/' ) . '$/',
	'',
	$newLine
	);
	if ( $newLine != $prev ) {
	return true;
	}
	}

	return false;
	}

	/**
	* @inheritDoc
	*/
	public function lockIsFree( $lockName, $method ) {
	// RDBMs methods for checking named locks may or may not count this thread itself.
	// In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
	// the behavior chosen by the interface for this method.
	if ( isset( $this->sessionNamedLocks[$lockName] ) ) {
	$lockIsFree = false;
	} else {
	$lockIsFree = $this->doLockIsFree( $lockName, $method );
	}

	return $lockIsFree;
	}

	/**
	* @see lockIsFree()
	*
	* @param string $lockName
	* @param string $method
	* @return bool Success
	* @throws DBError
	*/
	protected function doLockIsFree( string $lockName, string $method ) {
	return true; // not implemented
	}

	/**
	* @inheritDoc
	*/
	public function lock( $lockName, $method, $timeout = 5, $flags = 0 ) {
	$lockTsUnix = $this->doLock( $lockName, $method, $timeout );
	if ( $lockTsUnix !== null ) {
	$locked = true;
	$this->sessionNamedLocks[$lockName] = [
	'ts' => $lockTsUnix,
	'trxId' => $this->transactionManager->getTrxId()
	];
	} else {
	$locked = false;
	$this->logger->info(
	__METHOD__ . ": failed to acquire lock '{lockname}'",
	[
	'lockname' => $lockName,
	'db_log_category' => 'locking'
	]
	);
	}

	return $this->flagsHolder::contains( $flags, self::LOCK_TIMESTAMP ) ? $lockTsUnix : $locked;
	}

	/**
	* @see lock()
	*
	* @param string $lockName
	* @param string $method
	* @param int $timeout
	* @return float\|null UNIX timestamp of lock acquisition; null on failure
	* @throws DBError
	*/
	protected function doLock( string $lockName, string $method, int $timeout ) {
	return microtime( true ); // not implemented
	}

	/**
	* @inheritDoc
	*/
	public function unlock( $lockName, $method ) {
	if ( !isset( $this->sessionNamedLocks[$lockName] ) ) {
	$released = false;
	$this->logger->warning(
	__METHOD__ . ": trying to release unheld lock '$lockName'\n",
	[ 'db_log_category' => 'locking' ]
	);
	} else {
	$released = $this->doUnlock( $lockName, $method );
	if ( $released ) {
	unset( $this->sessionNamedLocks[$lockName] );
	} else {
	$this->logger->warning(
	__METHOD__ . ": failed to release lock '$lockName'\n",
	[ 'db_log_category' => 'locking' ]
	);
	}
	}

	return $released;
	}

	/**
	* @see unlock()
	*
	* @param string $lockName
	* @param string $method
	* @return bool Success
	* @throws DBError
	*/
	protected function doUnlock( string $lockName, string $method ) {
	return true; // not implemented
	}

	/** @inheritDoc */
	public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
	$this->transactionManager->onGetScopedLockAndFlush( $this, $fname );

	if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
	return null;
	}

	$unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
	// Note that the callback can be reached due to an exception making the calling
	// function end early. If the transaction/session is in an error state, avoid log
	// spam and confusing replacement of an original DBError with one about unlock().
	// Unlock query will fail anyway; avoid possibly triggering errors in rollback()
	if (
	$this->transactionManager->sessionStatus() === TransactionManager::STATUS_SESS_ERROR \|\|
	$this->transactionManager->trxStatus() === TransactionManager::STATUS_TRX_ERROR
	) {
	return;
	}
	if ( $this->trxLevel() ) {
	$this->onTransactionResolution(
	function () use ( $lockKey, $fname ) {
	$this->unlock( $lockKey, $fname );
	},
	$fname
	);
	} else {
	$this->unlock( $lockKey, $fname );
	}
	} );

	$this->commit( $fname, self::FLUSHING_INTERNAL );

	return $unlocker;
	}

	/** @inheritDoc */
	public function dropTable( $table, $fname = __METHOD__ ) {
	if ( !$this->tableExists( $table, $fname ) ) {
	return false;
	}

	$query = new Query(
	$this->platform->dropTableSqlText( $table ),
	self::QUERY_CHANGE_SCHEMA,
	'DROP',
	$table
	);
	$this->query( $query, $fname );

	return true;
	}

	/** @inheritDoc */
	public function truncateTable( $table, $fname = __METHOD__ ) {
	$sql = "TRUNCATE TABLE " . $this->tableName( $table );
	$query = new Query( $sql, self::QUERY_CHANGE_SCHEMA, 'TRUNCATE', $table );
	$this->query( $query, $fname );
	}

	/** @inheritDoc */
	public function isReadOnly() {
	return ( $this->getReadOnlyReason() !== null );
	}

	/**
	* @return array\|null Tuple of (reason string, "role" or "lb") if read-only; null otherwise
	*/
	protected function getReadOnlyReason() {
	$reason = $this->replicationReporter->getTopologyBasedReadOnlyReason();
	if ( $reason ) {
	return $reason;
	}

	$reason = $this->getLBInfo( self::LB_READ_ONLY_REASON );
	if ( is_string( $reason ) ) {
	return [ $reason, 'lb' ];
	}

	return null;
	}

	/**
	* Get the underlying binding connection handle
	*
	* Makes sure the connection resource is set (disconnects and ping() failure can unset it).
	* This catches broken callers than catch and ignore disconnection exceptions.
	* Unlike checking isOpen(), this is safe to call inside of open().
	*
	* @return mixed
	* @throws DBUnexpectedError
	* @since 1.26
	*/
	protected function getBindingHandle() {
	if ( !$this->conn ) {
	throw new DBUnexpectedError(
	$this,
	'DB connection was already closed or the connection dropped'
	);
	}

	return $this->conn;
	}

	/**
	* Demark the start of a critical section of session/transaction state changes
	*
	* Use this to disable potentially DB handles due to corruption from highly unexpected
	* exceptions (e.g. from zend timers or coding errors) preempting execution of methods.
	*
	* Callers must demark completion of the critical section with completeCriticalSection().
	* Callers should handle DBError exceptions that do not cause object state corruption by
	* catching them, calling completeCriticalSection(), and then rethrowing them.
	*
	* @code
	* $cs = $this->commenceCriticalSection( __METHOD__ );
	* try {
	* //...send a query that changes the session/transaction state...
	* } catch ( DBError $e ) {
	* $this->completeCriticalSection( __METHOD__, $cs );
	* throw $expectedException;
	* }
	* try {
	* //...send another query that changes the session/transaction state...
	* } catch ( DBError $trxError ) {
	* // Require ROLLBACK before allowing any other queries from outside callers
	* $this->completeCriticalSection( __METHOD__, $cs, $trxError );
	* throw $expectedException;
	* }
	* // ...update session state fields of $this...
	* $this->completeCriticalSection( __METHOD__, $cs );
	* @endcode
	*
	* @see Database::completeCriticalSection()
	*
	* @since 1.36
	* @param string $fname Caller name
	* @return CriticalSectionScope\|null RAII-style monitor (topmost sections only)
	* @throws DBUnexpectedError If an unresolved critical section error already exists
	*/
	protected function commenceCriticalSection( string $fname ) {
	if ( $this->csmError ) {
	throw new DBUnexpectedError(
	$this,
	"Cannot execute $fname critical section while session state is out of sync.\n\n" .
	$this->csmError->getMessage() . "\n" .
	$this->csmError->getTraceAsString()
	);
	}

	if ( $this->csmId ) {
	$csm = null; // fold into the outer critical section
	} elseif ( $this->csProvider ) {
	$csm = $this->csProvider->scopedEnter(
	$fname,
	null, // emergency limit (default)
	null, // emergency callback (default)
	function () use ( $fname ) {
	// Mark a critical section as having been aborted by an error
	$e = new RuntimeException( "A critical section from {$fname} has failed" );
	$this->csmError = $e;
	$this->csmId = null;
	}
	);
	$this->csmId = $csm->getId();
	$this->csmFname = $fname;
	} else {
	$csm = null; // not supported
	}

	return $csm;
	}

	/**
	* Demark the completion of a critical section of session/transaction state changes
	*
	* @see Database::commenceCriticalSection()
	*
	* @since 1.36
	* @param string $fname Caller name
	* @param CriticalSectionScope\|null $csm RAII-style monitor (topmost sections only)
	* @param Throwable\|null $trxError Error that requires setting STATUS_TRX_ERROR (if any)
	*/
	protected function completeCriticalSection(
	string $fname,
	?CriticalSectionScope $csm,
	?Throwable $trxError = null
	) {
	if ( $csm !== null ) {
	if ( $this->csmId === null ) {
	throw new LogicException( "$fname critical section is not active" );
	} elseif ( $csm->getId() !== $this->csmId ) {
	throw new LogicException(
	"$fname critical section is not the active ({$this->csmFname}) one"
	);
	}

	$csm->exit();
	$this->csmId = null;
	}

	if ( $trxError ) {
	$this->transactionManager->setTransactionError( $trxError );
	}
	}

	public function __toString() {
	$id = spl_object_id( $this );

	$description = $this->getType() . ' object #' . $id;
	// phpcs:ignore MediaWiki.Usage.ForbiddenFunctions.is_resource
	if ( is_resource( $this->conn ) ) {
	$description .= ' (' . (string)$this->conn . ')'; // "resource id #<ID>"
	} elseif ( is_object( $this->conn ) ) {
	$handleId = spl_object_id( $this->conn );
	$description .= " (handle id #$handleId)";
	}

	return $description;
	}

	/**
	* Make sure that copies do not share the same client binding handle
	* @throws DBConnectionError
	*/
	public function __clone() {
	$this->logger->warning(
	"Cloning " . static::class . " is not recommended; forking connection",
	[
	'exception' => new RuntimeException(),
	'db_log_category' => 'connection'
	]
	);

	if ( $this->isOpen() ) {
	// Open a new connection resource without messing with the old one
	$this->conn = null;
	$this->transactionManager->clearEndCallbacks();
	$this->handleSessionLossPreconnect(); // no trx or locks anymore
	$this->open(
	$this->connectionParams[self::CONN_HOST],
	$this->connectionParams[self::CONN_USER],
	$this->connectionParams[self::CONN_PASSWORD],
	$this->currentDomain->getDatabase(),
	$this->currentDomain->getSchema(),
	$this->tablePrefix()
	);
	$this->lastPing = microtime( true );
	}
	}

	/**
	* Called by serialize. Throw an exception when DB connection is serialized.
	* This causes problems on some database engines because the connection is
	* not restored on unserialize.
	* @return never
	*/
	public function __sleep(): never {
	throw new RuntimeException( 'Database serialization may cause problems, since ' .
	'the connection is not restored on wakeup' );
	}

	/**
	* Run a few simple checks and close dangling connections
	*/
	public function __destruct() {
	if ( $this->transactionManager ) {
	// Tests mock this class and disable constructor.
	$this->transactionManager->onDestruct();
	}

	$danglingWriters = $this->pendingWriteAndCallbackCallers();
	if ( $danglingWriters ) {
	$fnames = implode( ', ', $danglingWriters );
	trigger_error( "DB transaction writes or callbacks still pending ($fnames)" );
	}

	if ( $this->conn ) {
	// Avoid connection leaks. Normally, resources close at script completion.
	// The connection might already be closed in PHP by now, so suppress warnings.
	AtEase::suppressWarnings();
	$this->closeConnection();
	AtEase::restoreWarnings();
	$this->conn = null;
	}
	}

	/* Start of methods delegated to DatabaseFlags. Avoid using them outside of rdbms library */

	/** @inheritDoc */
	public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
	$this->flagsHolder->setFlag( $flag, $remember );
	}

	/** @inheritDoc */
	public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
	$this->flagsHolder->clearFlag( $flag, $remember );
	}

	/** @inheritDoc */
	public function restoreFlags( $state = self::RESTORE_PRIOR ) {
	$this->flagsHolder->restoreFlags( $state );
	}

	/** @inheritDoc */
	public function getFlag( $flag ) {
	return $this->flagsHolder->getFlag( $flag );
	}

	/* End of methods delegated to DatabaseFlags. */

	/* Start of methods delegated to TransactionManager. Avoid using them outside of rdbms library */

	/** @inheritDoc */
	final public function trxLevel() {
	// FIXME: A lot of tests disable constructor leading to trx manager being
	// null and breaking, this is unacceptable but hopefully this should
	// happen less by moving these functions to the transaction manager class.
	if ( !$this->transactionManager ) {
	$this->transactionManager = new TransactionManager( new NullLogger() );
	}
	return $this->transactionManager->trxLevel();
	}

	/** @inheritDoc */
	public function trxTimestamp() {
	return $this->transactionManager->trxTimestamp();
	}

	/** @inheritDoc */
	public function trxStatus() {
	return $this->transactionManager->trxStatus();
	}

	/** @inheritDoc */
	public function writesPending() {
	return $this->transactionManager->writesPending();
	}

	/** @inheritDoc */
	public function writesOrCallbacksPending() {
	return $this->transactionManager->writesOrCallbacksPending();
	}

	/** @inheritDoc */
	public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
	return $this->transactionManager->pendingWriteQueryDuration( $type );
	}

	/** @inheritDoc */
	public function pendingWriteCallers() {
	if ( !$this->transactionManager ) {
	return [];
	}
	return $this->transactionManager->pendingWriteCallers();
	}

	/** @inheritDoc */
	public function pendingWriteAndCallbackCallers() {
	if ( !$this->transactionManager ) {
	return [];
	}
	return $this->transactionManager->pendingWriteAndCallbackCallers();
	}

	/** @inheritDoc */
	public function runOnTransactionPreCommitCallbacks() {
	return $this->transactionManager->runOnTransactionPreCommitCallbacks();
	}

	/** @inheritDoc */
	public function explicitTrxActive() {
	return $this->transactionManager->explicitTrxActive();
	}

	/* End of methods delegated to TransactionManager. */

	/* Start of methods delegated to SQLPlatform. Avoid using them outside of rdbms library */

	/** @inheritDoc */
	public function implicitOrderby() {
	return $this->platform->implicitOrderby();
	}

	/** @inheritDoc */
	public function selectSQLText(
	$tables, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
	) {
	return $this->platform->selectSQLText( $tables, $vars, $conds, $fname, $options, $join_conds );
	}

	/** @inheritDoc */
	public function buildComparison( string $op, array $conds ): string {
	return $this->platform->buildComparison( $op, $conds );
	}

	/** @inheritDoc */
	public function makeList( array $a, $mode = self::LIST_COMMA ) {
	return $this->platform->makeList( $a, $mode );
	}

	/** @inheritDoc */
	public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
	return $this->platform->makeWhereFrom2d( $data, $baseKey, $subKey );
	}

	/** @inheritDoc */
	public function factorConds( $condsArray ) {
	return $this->platform->factorConds( $condsArray );
	}

	/** @inheritDoc */
	public function bitNot( $field ) {
	return $this->platform->bitNot( $field );
	}

	/** @inheritDoc */
	public function bitAnd( $fieldLeft, $fieldRight ) {
	return $this->platform->bitAnd( $fieldLeft, $fieldRight );
	}

	/** @inheritDoc */
	public function bitOr( $fieldLeft, $fieldRight ) {
	return $this->platform->bitOr( $fieldLeft, $fieldRight );
	}

	/** @inheritDoc */
	public function buildConcat( $stringList ) {
	return $this->platform->buildConcat( $stringList );
	}

	/** @inheritDoc */
	public function buildGreatest( $fields, $values ) {
	return $this->platform->buildGreatest( $fields, $values );
	}

	/** @inheritDoc */
	public function buildLeast( $fields, $values ) {
	return $this->platform->buildLeast( $fields, $values );
	}

	/** @inheritDoc */
	public function buildSubstring( $input, $startPosition, $length = null ) {
	return $this->platform->buildSubstring( $input, $startPosition, $length );
	}

	/** @inheritDoc */
	public function buildStringCast( $field ) {
	return $this->platform->buildStringCast( $field );
	}

	/** @inheritDoc */
	public function buildIntegerCast( $field ) {
	return $this->platform->buildIntegerCast( $field );
	}

	/** @inheritDoc */
	public function tableName( string $name, $format = 'quoted' ) {
	return $this->platform->tableName( $name, $format );
	}

	/** @inheritDoc */
	public function tableNamesN( ...$tables ) {
	return $this->platform->tableNamesN( ...$tables );
	}

	/** @inheritDoc */
	public function addIdentifierQuotes( $s ) {
	return $this->platform->addIdentifierQuotes( $s );
	}

	/** @inheritDoc */
	public function isQuotedIdentifier( $name ) {
	return $this->platform->isQuotedIdentifier( $name );
	}

	/** @inheritDoc */
	public function buildLike( $param, ...$params ) {
	return $this->platform->buildLike( $param, ...$params );
	}

	/** @inheritDoc */
	public function anyChar() {
	return $this->platform->anyChar();
	}

	/** @inheritDoc */
	public function anyString() {
	return $this->platform->anyString();
	}

	/** @inheritDoc */
	public function limitResult( $sql, $limit, $offset = false ) {
	return $this->platform->limitResult( $sql, $limit, $offset );
	}

	/** @inheritDoc */
	public function unionSupportsOrderAndLimit() {
	return $this->platform->unionSupportsOrderAndLimit();
	}

	/** @inheritDoc */
	public function unionQueries( $sqls, $all, $options = [] ) {
	return $this->platform->unionQueries( $sqls, $all, $options );
	}

	/** @inheritDoc */
	public function conditional( $cond, $caseTrueExpression, $caseFalseExpression ) {
	return $this->platform->conditional( $cond, $caseTrueExpression, $caseFalseExpression );
	}

	/** @inheritDoc */
	public function strreplace( $orig, $old, $new ) {
	return $this->platform->strreplace( $orig, $old, $new );
	}

	/** @inheritDoc */
	public function timestamp( $ts = 0 ) {
	return $this->platform->timestamp( $ts );
	}

	/** @inheritDoc */
	public function timestampOrNull( $ts = null ) {
	return $this->platform->timestampOrNull( $ts );
	}

	/** @inheritDoc */
	public function getInfinity() {
	return $this->platform->getInfinity();
	}

	/** @inheritDoc */
	public function encodeExpiry( $expiry ) {
	return $this->platform->encodeExpiry( $expiry );
	}

	/** @inheritDoc */
	public function decodeExpiry( $expiry, $format = TS_MW ) {
	return $this->platform->decodeExpiry( $expiry, $format );
	}

	/** @inheritDoc */
	public function setTableAliases( array $aliases ) {
	$this->platform->setTableAliases( $aliases );
	}

	/** @inheritDoc */
	public function getTableAliases() {
	return $this->platform->getTableAliases();
	}

	/** @inheritDoc */
	public function buildGroupConcatField(
	$delim, $tables, $field, $conds = '', $join_conds = []
	) {
	return $this->platform->buildGroupConcatField( $delim, $tables, $field, $conds, $join_conds );
	}

	/** @inheritDoc */
	public function buildSelectSubquery(
	$tables, $vars, $conds = '', $fname = __METHOD__,
	$options = [], $join_conds = []
	) {
	return $this->platform->buildSelectSubquery( $tables, $vars, $conds, $fname, $options, $join_conds );
	}

	/** @inheritDoc */
	public function buildExcludedValue( $column ) {
	return $this->platform->buildExcludedValue( $column );
	}

	/** @inheritDoc */
	public function setSchemaVars( $vars ) {
	$this->platform->setSchemaVars( $vars );
	}

	/* End of methods delegated to SQLPlatform. */

	/* Start of methods delegated to ReplicationReporter. */

	/** @inheritDoc */
	public function primaryPosWait( DBPrimaryPos $pos, $timeout ) {
	return $this->replicationReporter->primaryPosWait( $this, $pos, $timeout );
	}

	/** @inheritDoc */
	public function getPrimaryPos() {
	return $this->replicationReporter->getPrimaryPos( $this );
	}

	/** @inheritDoc */
	public function getLag() {
	return $this->replicationReporter->getLag( $this );
	}

	/** @inheritDoc */
	public function getSessionLagStatus() {
	return $this->replicationReporter->getSessionLagStatus( $this );
	}

	/* End of methods delegated to ReplicationReporter. */
	}

mediawiki/includes/libs/rdbms/database/Database.php7042373a0708master

Database.phpView Options

mediawiki/includes/libs/rdbms/database/Database.php
7042373a0708master

Database.php
View Options