<?php
/**
 * Generator and manager of database load balancing objects
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup Database
 */

namespace Wikimedia\Rdbms;

use BagOStuff;
use EmptyBagOStuff;
use Exception;
use LogicException;
use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;
use RuntimeException;
use Throwable;
use WANObjectCache;
use Wikimedia\RequestTimeout\CriticalSectionProvider;
use Wikimedia\ScopedCallback;

/**
 * An interface for generating database load balancers
 * @ingroup Database
 */
abstract class LBFactory implements ILBFactory {
	/** @var ChronologyProtector */
	private $chronProt;
	/** @var CriticalSectionProvider|null */
	private $csProvider;
	/**
	 * @var callable|null An optional callback that returns a ScopedCallback instance,
	 * meant to profile the actual query execution in {@see Database::doQuery}
	 */
	private $profiler;
	/** @var TransactionProfiler */
	private $trxProfiler;
	/** @var LoggerInterface */
	private $replLogger;
	/** @var LoggerInterface */
	private $connLogger;
	/** @var LoggerInterface */
	private $queryLogger;
	/** @var LoggerInterface */
	private $perfLogger;
	/** @var callable Error logger */
	private $errorLogger;
	/** @var callable Deprecation logger */
	private $deprecationLogger;

	/** @var BagOStuff */
	protected $cpStash;
	/** @var BagOStuff */
	protected $srvCache;
	/** @var WANObjectCache */
	protected $wanCache;

	/** @var DatabaseDomain Local domain */
	protected $localDomain;

	/** @var array Web request information about the client */
	private $requestInfo;
	/** @var bool Whether this PHP instance is for a CLI script */
	private $cliMode;
	/** @var string Agent name for query profiling */
	private $agent;
	/** @var string Secret string for HMAC hashing */
	private $secret;

	/** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
	private $tableAliases = [];
	/** @var string[] Map of (index alias => index) */
	private $indexAliases = [];
	/** @var DatabaseDomain[]|string[] Map of (domain alias => DB domain) */
	private $domainAliases = [];
	/** @var callable[] */
	private $replicationWaitCallbacks = [];

	/** var int An identifier for this class instance */
	private $id;
	/** @var int|null Ticket used to delegate transaction ownership */
	private $ticket;
	/** @var string|bool String if a requested DBO_TRX transaction round is active */
	private $trxRoundId = false;
	/** @var string One of the ROUND_* class constants */
	private $trxRoundStage = self::ROUND_CURSORY;
	/** @var int Default replication wait timeout */
	private $replicationWaitTimeout;

	/** @var string|bool Reason all LBs are read-only or false if not */
	protected $readOnlyReason = false;

	/** @var string|null */
	private $defaultGroup = null;

	/** @var int|null */
	protected $maxLag;

	/** @var DatabaseDomain[] Map of (domain ID => domain instance) */
	private $nonLocalDomainCache = [];

	private const ROUND_CURSORY = 'cursory';
	private const ROUND_BEGINNING = 'within-begin';
	private const ROUND_COMMITTING = 'within-commit';
	private const ROUND_ROLLING_BACK = 'within-rollback';
	private const ROUND_COMMIT_CALLBACKS = 'within-commit-callbacks';
	private const ROUND_ROLLBACK_CALLBACKS = 'within-rollback-callbacks';

	private static $loggerFields =
		[ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ];

	public function __construct( array $conf ) {
		$this->localDomain = isset( $conf['localDomain'] )
			? DatabaseDomain::newFromId( $conf['localDomain'] )
			: DatabaseDomain::newUnspecified();

		$this->maxLag = $conf['maxLag'] ?? null;
		if ( isset( $conf['readOnlyReason'] ) && is_string( $conf['readOnlyReason'] ) ) {
			$this->readOnlyReason = $conf['readOnlyReason'];
		}

		$this->cpStash = $conf['cpStash'] ?? new EmptyBagOStuff();
		$this->srvCache = $conf['srvCache'] ?? new EmptyBagOStuff();
		$this->wanCache = $conf['wanCache'] ?? WANObjectCache::newEmpty();

		foreach ( self::$loggerFields as $key ) {
			$this->$key = $conf[$key] ?? new NullLogger();
		}
		$this->errorLogger = $conf['errorLogger'] ?? static function ( Throwable $e ) {
			trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
		};
		$this->deprecationLogger = $conf['deprecationLogger'] ?? static function ( $msg ) {
			trigger_error( $msg, E_USER_DEPRECATED );
		};

		$this->profiler = $conf['profiler'] ?? null;
		$this->trxProfiler = $conf['trxProfiler'] ?? new TransactionProfiler();

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

		$this->requestInfo = [
			'IPAddress' => $_SERVER[ 'REMOTE_ADDR' ] ?? '',
			'UserAgent' => $_SERVER['HTTP_USER_AGENT'] ?? '',
			// Headers application can inject via LBFactory::setRequestInfo()
			'ChronologyProtection' => null,
			'ChronologyClientId' => null, // prior $cpClientId value from LBFactory::shutdown()
			'ChronologyPositionIndex' => null // prior $cpIndex value from LBFactory::shutdown()
		];

		$this->cliMode = $conf['cliMode'] ?? ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
		$this->agent = $conf['agent'] ?? '';
		$this->defaultGroup = $conf['defaultGroup'] ?? null;
		$this->secret = $conf['secret'] ?? '';
		$this->replicationWaitTimeout = $this->cliMode ? 60 : 1;

		static $nextId, $nextTicket;
		$this->id = $nextId = ( is_int( $nextId ) ? $nextId++ : mt_rand() );
		$this->ticket = $nextTicket = ( is_int( $nextTicket ) ? $nextTicket++ : mt_rand() );
	}

	public function destroy() {
		/** @noinspection PhpUnusedLocalVariableInspection */
		$scope = ScopedCallback::newScopedIgnoreUserAbort();

		$this->forEachLBCallMethod( 'disable', [ __METHOD__, $this->id ] );
	}

	public function getLocalDomainID() {
		return $this->localDomain->getId();
	}

	public function resolveDomainID( $domain ) {
		return $this->resolveDomainInstance( $domain )->getId();
	}

	/**
	 * @param DatabaseDomain|string|bool $domain
	 * @return DatabaseDomain
	 */
	final protected function resolveDomainInstance( $domain ) {
		if ( $domain instanceof DatabaseDomain ) {
			return $domain; // already a domain instance
		} elseif ( $domain === false || $domain === $this->localDomain->getId() ) {
			return $this->localDomain;
		} elseif ( isset( $this->domainAliases[$domain] ) ) {
			// This array acts as both the original map and as instance cache.
			// Instances pass-through DatabaseDomain::newFromId as-is.
			$this->domainAliases[$domain] =
				DatabaseDomain::newFromId( $this->domainAliases[$domain] );

			return $this->domainAliases[$domain];
		}

		$cachedDomain = $this->nonLocalDomainCache[$domain] ?? null;
		if ( $cachedDomain === null ) {
			$cachedDomain = DatabaseDomain::newFromId( $domain );
			$this->nonLocalDomainCache = [ $domain => $cachedDomain ];
		}

		return $cachedDomain;
	}

	public function shutdown(
		$flags = self::SHUTDOWN_NORMAL,
		callable $workCallback = null,
		&$cpIndex = null,
		&$cpClientId = null
	) {
		/** @noinspection PhpUnusedLocalVariableInspection */
		$scope = ScopedCallback::newScopedIgnoreUserAbort();

		$chronProt = $this->getChronologyProtector();
		if ( ( $flags & self::SHUTDOWN_NO_CHRONPROT ) != self::SHUTDOWN_NO_CHRONPROT ) {
			$this->shutdownChronologyProtector( $chronProt, $workCallback, $cpIndex );
			$this->replLogger->debug( __METHOD__ . ': finished ChronologyProtector shutdown' );
		}
		$cpClientId = $chronProt->getClientId();

		$this->commitPrimaryChanges( __METHOD__ );

		$this->replLogger->debug( 'LBFactory shutdown completed' );
	}

	/**
	 * Call a method on each tracked (instantiated) load balancer instance
	 *
	 * @param string $methodName
	 * @param array $args
	 */
	protected function forEachLBCallMethod( $methodName, array $args = [] ) {
		$this->forEachLB(
			static function ( ILoadBalancer $loadBalancer, $methodName, array $args ) {
				$loadBalancer->$methodName( ...$args );
			},
			[ $methodName, $args ]
		);
	}

	public function flushReplicaSnapshots( $fname = __METHOD__ ) {
		if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
			$this->queryLogger->warning(
				"$fname: transaction round '{$this->trxRoundId}' still running",
				[ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
			);
		}
		$this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname, $this->id ] );
	}

	final public function commitAll( $fname = __METHOD__, array $options = [] ) {
		$this->commitPrimaryChanges( $fname, $options );
		$this->forEachLBCallMethod( 'flushPrimarySnapshots', [ $fname, $this->id ] );
		$this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname, $this->id ] );
	}

	final public function beginPrimaryChanges( $fname = __METHOD__ ) {
		$this->assertTransactionRoundStage( self::ROUND_CURSORY );
		/** @noinspection PhpUnusedLocalVariableInspection */
		$scope = ScopedCallback::newScopedIgnoreUserAbort();

		$this->trxRoundStage = self::ROUND_BEGINNING;
		if ( $this->trxRoundId !== false ) {
			throw new DBTransactionError(
				null,
				"$fname: transaction round '{$this->trxRoundId}' already started"
			);
		}
		$this->trxRoundId = $fname;
		// Set DBO_TRX flags on all appropriate DBs
		$this->forEachLBCallMethod( 'beginPrimaryChanges', [ $fname, $this->id ] );
		$this->trxRoundStage = self::ROUND_CURSORY;
	}

	final public function commitPrimaryChanges( $fname = __METHOD__, array $options = [] ) {
		$this->assertTransactionRoundStage( self::ROUND_CURSORY );
		/** @noinspection PhpUnusedLocalVariableInspection */
		$scope = ScopedCallback::newScopedIgnoreUserAbort();

		$this->trxRoundStage = self::ROUND_COMMITTING;
		if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) {
			throw new DBTransactionError(
				null,
				"$fname: transaction round '{$this->trxRoundId}' still running"
			);
		}
		// Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure
		do {
			$count = 0; // number of callbacks executed this iteration
			$this->forEachLB( function ( ILoadBalancer $lb ) use ( &$count, $fname ) {
				$count += $lb->finalizePrimaryChanges( $fname, $this->id );
			} );
		} while ( $count > 0 );
		$this->trxRoundId = false;
		// Perform pre-commit checks, aborting on failure
		$this->forEachLBCallMethod( 'approvePrimaryChanges', [ $options, $fname, $this->id ] );
		// Log the DBs and methods involved in multi-DB transactions
		$this->logIfMultiDbTransaction();
		// Actually perform the commit on all primary DB connections and revert DBO_TRX
		$this->forEachLBCallMethod( 'commitPrimaryChanges', [ $fname, $this->id ] );
		// Run all post-commit callbacks in a separate step
		$this->trxRoundStage = self::ROUND_COMMIT_CALLBACKS;
		$e = $this->executePostTransactionCallbacks();
		$this->trxRoundStage = self::ROUND_CURSORY;
		// Throw any last post-commit callback error
		if ( $e instanceof Exception ) {
			throw $e;
		}
	}

	final public function rollbackPrimaryChanges( $fname = __METHOD__ ) {
		/** @noinspection PhpUnusedLocalVariableInspection */
		$scope = ScopedCallback::newScopedIgnoreUserAbort();

		$this->trxRoundStage = self::ROUND_ROLLING_BACK;
		$this->trxRoundId = false;
		// Actually perform the rollback on all primary DB connections and revert DBO_TRX
		$this->forEachLBCallMethod( 'rollbackPrimaryChanges', [ $fname, $this->id ] );
		// Run all post-commit callbacks in a separate step
		$this->trxRoundStage = self::ROUND_ROLLBACK_CALLBACKS;
		$this->executePostTransactionCallbacks();
		$this->trxRoundStage = self::ROUND_CURSORY;
	}

	/**
	 * @return Exception|null
	 */
	private function executePostTransactionCallbacks() {
		$fname = __METHOD__;
		// Run all post-commit callbacks until new ones stop getting added
		$e = null; // first callback exception
		do {
			$this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e, $fname ) {
				$ex = $lb->runPrimaryTransactionIdleCallbacks( $fname, $this->id );
				$e = $e ?: $ex;
			} );
		} while ( $this->hasPrimaryChanges() );
		// Run all listener callbacks once
		$this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e, $fname ) {
			$ex = $lb->runPrimaryTransactionListenerCallbacks( $fname, $this->id );
			$e = $e ?: $ex;
		} );

		return $e;
	}

	public function hasTransactionRound() {
		return ( $this->trxRoundId !== false );
	}

	public function isReadyForRoundOperations() {
		return ( $this->trxRoundStage === self::ROUND_CURSORY );
	}

	/**
	 * Log query info if multi DB transactions are going to be committed now
	 */
	private function logIfMultiDbTransaction() {
		$callersByDB = [];
		$this->forEachLB( static function ( ILoadBalancer $lb ) use ( &$callersByDB ) {
			$primaryName = $lb->getServerName( $lb->getWriterIndex() );
			$callers = $lb->pendingPrimaryChangeCallers();
			if ( $callers ) {
				$callersByDB[$primaryName] = $callers;
			}
		} );

		if ( count( $callersByDB ) >= 2 ) {
			$dbs = implode( ', ', array_keys( $callersByDB ) );
			$msg = "Multi-DB transaction [{$dbs}]:\n";
			foreach ( $callersByDB as $db => $callers ) {
				$msg .= "$db: " . implode( '; ', $callers ) . "\n";
			}
			$this->queryLogger->info( $msg );
		}
	}

	public function hasPrimaryChanges() {
		$ret = false;
		$this->forEachLB( static function ( ILoadBalancer $lb ) use ( &$ret ) {
			$ret = $ret || $lb->hasPrimaryChanges();
		} );

		return $ret;
	}

	public function laggedReplicaUsed() {
		$ret = false;
		$this->forEachLB( static function ( ILoadBalancer $lb ) use ( &$ret ) {
			$ret = $ret || $lb->laggedReplicaUsed();
		} );

		return $ret;
	}

	public function hasOrMadeRecentPrimaryChanges( $age = null ) {
		$ret = false;
		$this->forEachLB( static function ( ILoadBalancer $lb ) use ( $age, &$ret ) {
			$ret = $ret || $lb->hasOrMadeRecentPrimaryChanges( $age );
		} );
		return $ret;
	}

	public function waitForReplication( array $opts = [] ) {
		$opts += [
			'domain' => false,
			'cluster' => false,
			'timeout' => $this->replicationWaitTimeout,
			'ifWritesSince' => null
		];

		if ( $opts['domain'] === false && isset( $opts['wiki'] ) ) {
			$opts['domain'] = $opts['wiki']; // b/c
		}

		// Figure out which clusters need to be checked
		/** @var ILoadBalancer[] $lbs */
		$lbs = [];
		if ( $opts['cluster'] !== false ) {
			$lbs[] = $this->getExternalLB( $opts['cluster'] );
		} elseif ( $opts['domain'] !== false ) {
			$lbs[] = $this->getMainLB( $opts['domain'] );
		} else {
			$this->forEachLB( static function ( ILoadBalancer $lb ) use ( &$lbs ) {
				$lbs[] = $lb;
			} );
			if ( !$lbs ) {
				return true; // nothing actually used
			}
		}

		// Get all the primary DB positions of applicable DBs right now.
		// This can be faster since waiting on one cluster reduces the
		// time needed to wait on the next clusters.
		$primaryPositions = array_fill( 0, count( $lbs ), false );
		foreach ( $lbs as $i => $lb ) {
			if (
				// No writes to wait on getting replicated
				!$lb->hasPrimaryConnection() ||
				// No replication; avoid getPrimaryPos() permissions errors (T29975)
				!$lb->hasStreamingReplicaServers() ||
				// No writes since the last replication wait
				(
					$opts['ifWritesSince'] &&
					$lb->lastPrimaryChangeTimestamp() < $opts['ifWritesSince']
				)
			) {
				continue; // no need to wait
			}

			$primaryPositions[$i] = $lb->getPrimaryPos();
		}

		// Run any listener callbacks *after* getting the DB positions. The more
		// time spent in the callbacks, the less time is spent in waitForAll().
		foreach ( $this->replicationWaitCallbacks as $callback ) {
			$callback();
		}

		$failed = [];
		foreach ( $lbs as $i => $lb ) {
			if ( $primaryPositions[$i] ) {
				// The RDBMS may not support getPrimaryPos()
				if ( !$lb->waitForAll( $primaryPositions[$i], $opts['timeout'] ) ) {
					$failed[] = $lb->getServerName( $lb->getWriterIndex() );
				}
			}
		}

		return !$failed;
	}

	public function setWaitForReplicationListener( $name, callable $callback = null ) {
		if ( $callback ) {
			$this->replicationWaitCallbacks[$name] = $callback;
		} else {
			unset( $this->replicationWaitCallbacks[$name] );
		}
	}

	public function getEmptyTransactionTicket( $fname ) {
		if ( $this->hasPrimaryChanges() ) {
			$this->queryLogger->error(
				__METHOD__ . ": $fname does not have outer scope",
				[ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
			);

			return null;
		}

		return $this->ticket;
	}

	final public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) {
		if ( $ticket !== $this->ticket ) {
			$this->perfLogger->error(
				__METHOD__ . ": $fname does not have outer scope",
				[ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
			);

			return false;
		}

		// The transaction owner and any caller with the empty transaction ticket can commit
		// so that getEmptyTransactionTicket() callers don't risk seeing DBTransactionError.
		if ( $this->trxRoundId !== false && $fname !== $this->trxRoundId ) {
			$this->queryLogger->info( "$fname: committing on behalf of {$this->trxRoundId}" );
			$fnameEffective = $this->trxRoundId;
		} else {
			$fnameEffective = $fname;
		}

		$this->commitPrimaryChanges( $fnameEffective );
		$waitSucceeded = $this->waitForReplication( $opts );
		// If a nested caller committed on behalf of $fname, start another empty $fname
		// transaction, leaving the caller with the same empty transaction state as before.
		if ( $fnameEffective !== $fname ) {
			$this->beginPrimaryChanges( $fnameEffective );
		}

		return $waitSucceeded;
	}

	public function getChronologyProtectorTouched( $domain = false ) {
		return $this->getChronologyProtector()->getTouched( $this->getMainLB( $domain ) );
	}

	public function disableChronologyProtection() {
		$this->getChronologyProtector()->setEnabled( false );
	}

	/**
	 * @return ChronologyProtector
	 */
	protected function getChronologyProtector() {
		if ( $this->chronProt ) {
			return $this->chronProt;
		}

		$this->chronProt = new ChronologyProtector(
			$this->cpStash,
			[
				'ip' => $this->requestInfo['IPAddress'],
				'agent' => $this->requestInfo['UserAgent'],
				'clientId' => $this->requestInfo['ChronologyClientId'] ?: null
			],
			$this->requestInfo['ChronologyPositionIndex'],
			$this->secret
		);
		$this->chronProt->setLogger( $this->replLogger );

		if ( $this->cliMode ) {
			$this->chronProt->setEnabled( false );
		} elseif ( $this->requestInfo['ChronologyProtection'] === 'false' ) {
			// Request opted out of using position wait logic. This is useful for requests
			// done by the job queue or background ETL that do not have a meaningful session.
			$this->chronProt->setWaitEnabled( false );
		} elseif ( $this->cpStash instanceof EmptyBagOStuff ) {
			// No where to store any DB positions and wait for them to appear
			$this->chronProt->setEnabled( false );
			$this->replLogger->debug( 'Cannot use ChronologyProtector with EmptyBagOStuff' );
		}

		$this->replLogger->debug(
			__METHOD__ . ': request info ' .
			json_encode( $this->requestInfo, JSON_PRETTY_PRINT )
		);

		return $this->chronProt;
	}

	/**
	 * Get and record all of the staged DB positions into persistent memory storage
	 *
	 * @param ChronologyProtector $cp
	 * @param callable|null $workCallback Work to do instead of waiting on syncing positions
	 * @param int|null &$cpIndex DB position key write counter; incremented on update [returned]
	 */
	protected function shutdownChronologyProtector(
		ChronologyProtector $cp, $workCallback, &$cpIndex = null
	) {
		// Remark all of the relevant DB primary positions
		$this->forEachLB( static function ( ILoadBalancer $lb ) use ( $cp ) {
			$cp->stageSessionReplicationPosition( $lb );
		} );
		// Write the positions to the persistent stash
		$unsavedPositions = $cp->persistSessionReplicationPositions( $cpIndex );
		if ( $unsavedPositions && $workCallback ) {
			// Invoke callback in case it did not cache the result yet
			$workCallback();
		}
		// If the positions failed to write to the stash, then wait on the local datacenter
		// replica DBs to catch up before sending an HTTP response. As long as the request that
		// caused such DB writes occurred in the primary datacenter, and clients are temporarily
		// pinned to the primary datacenter after causing DB writes, then this should suffice.
		$this->forEachLB( static function ( ILoadBalancer $lb ) use ( $unsavedPositions ) {
			$primaryName = $lb->getServerName( $lb->getWriterIndex() );
			if ( isset( $unsavedPositions[$primaryName] ) ) {
				$lb->waitForAll( $unsavedPositions[$primaryName] );
			}
		} );
	}

	/**
	 * Get parameters to ILoadBalancer::__construct()
	 *
	 * @param int|null $owner Use getOwnershipId() if this is for getMainLB()/getExternalLB()
	 * @return array
	 */
	final protected function baseLoadBalancerParams( $owner ) {
		if ( $this->trxRoundStage === self::ROUND_COMMIT_CALLBACKS ) {
			$initStage = ILoadBalancer::STAGE_POSTCOMMIT_CALLBACKS;
		} elseif ( $this->trxRoundStage === self::ROUND_ROLLBACK_CALLBACKS ) {
			$initStage = ILoadBalancer::STAGE_POSTROLLBACK_CALLBACKS;
		} else {
			$initStage = null;
		}

		return [
			'localDomain' => $this->localDomain,
			'readOnlyReason' => $this->readOnlyReason,
			'srvCache' => $this->srvCache,
			'wanCache' => $this->wanCache,
			'profiler' => $this->profiler,
			'trxProfiler' => $this->trxProfiler,
			'queryLogger' => $this->queryLogger,
			'connLogger' => $this->connLogger,
			'replLogger' => $this->replLogger,
			'perfLogger' => $this->perfLogger,
			'errorLogger' => $this->errorLogger,
			'deprecationLogger' => $this->deprecationLogger,
			'cliMode' => $this->cliMode,
			'agent' => $this->agent,
			'maxLag' => $this->maxLag,
			'defaultGroup' => $this->defaultGroup,
			'chronologyCallback' => function ( ILoadBalancer $lb ) {
				// Defer ChronologyProtector construction in case setRequestInfo() ends up
				// being called later (but before the first connection attempt) (T192611)
				$this->getChronologyProtector()->applySessionReplicationPosition( $lb );
			},
			'roundStage' => $initStage,
			'ownerId' => $owner,
			'criticalSectionProvider' => $this->csProvider
		];
	}

	/**
	 * @param ILoadBalancer $lb
	 */
	protected function initLoadBalancer( ILoadBalancer $lb ) {
		if ( $this->trxRoundId !== false ) {
			$lb->beginPrimaryChanges( $this->trxRoundId, $this->id ); // set DBO_TRX
		}

		$lb->setTableAliases( $this->tableAliases );
		$lb->setIndexAliases( $this->indexAliases );
		$lb->setDomainAliases( $this->domainAliases );
	}

	public function setTableAliases( array $aliases ) {
		$this->tableAliases = $aliases;
	}

	public function setIndexAliases( array $aliases ) {
		$this->indexAliases = $aliases;
	}

	public function setDomainAliases( array $aliases ) {
		$this->domainAliases = $aliases;
	}

	public function getTransactionProfiler(): TransactionProfiler {
		return $this->trxProfiler;
	}

	public function setLocalDomainPrefix( $prefix ) {
		$this->localDomain = new DatabaseDomain(
			$this->localDomain->getDatabase(),
			$this->localDomain->getSchema(),
			$prefix
		);

		$this->forEachLB( static function ( ILoadBalancer $lb ) use ( $prefix ) {
			$lb->setLocalDomainPrefix( $prefix );
		} );
	}

	public function redefineLocalDomain( $domain ) {
		$this->closeAll();

		$this->localDomain = DatabaseDomain::newFromId( $domain );

		$this->forEachLB( function ( ILoadBalancer $lb ) {
			$lb->redefineLocalDomain( $this->localDomain );
		} );
	}

	public function closeAll() {
		/** @noinspection PhpUnusedLocalVariableInspection */
		$scope = ScopedCallback::newScopedIgnoreUserAbort();

		$this->forEachLBCallMethod( 'closeAll', [ __METHOD__, $this->id ] );
	}

	public function setAgentName( $agent ) {
		$this->agent = $agent;
	}

	public function appendShutdownCPIndexAsQuery( $url, $index ) {
		$usedCluster = false;
		$this->forEachLB( static function ( ILoadBalancer $lb ) use ( &$usedCluster ) {
			$usedCluster = $usedCluster || $lb->hasStreamingReplicaServers();
		} );

		if ( !$usedCluster ) {
			return $url; // no primary/replica clusters touched
		}

		return strpos( $url, '?' ) === false ? "$url?cpPosIndex=$index" : "$url&cpPosIndex=$index";
	}

	public function getChronologyProtectorClientId() {
		return $this->getChronologyProtector()->getClientId();
	}

	/**
	 * Build a string conveying the client and write index of the chronology protector data
	 *
	 * @param int $writeIndex
	 * @param int $time UNIX timestamp; can be used to detect stale cookies (T190082)
	 * @param string $clientId Client ID hash from ILBFactory::shutdown()
	 * @return string Value to use for "cpPosIndex" cookie
	 * @since 1.32
	 */
	public static function makeCookieValueFromCPIndex(
		int $writeIndex,
		int $time,
		string $clientId
	) {
		// Format is "<write index>@<write timestamp>#<client ID hash>"
		return "{$writeIndex}@{$time}#{$clientId}";
	}

	/**
	 * Parse a string conveying the client and write index of the chronology protector data
	 *
	 * @param string|null $value Value of "cpPosIndex" cookie
	 * @param int $minTimestamp Lowest UNIX timestamp that a non-expired value can have
	 * @return array (index: int or null, clientId: string or null)
	 * @since 1.32
	 */
	public static function getCPInfoFromCookieValue( ?string $value, int $minTimestamp ) {
		static $placeholder = [ 'index' => null, 'clientId' => null ];

		if ( $value === null ) {
			return $placeholder; // not set
		}

		// Format is "<write index>@<write timestamp>#<client ID hash>"
		if ( !preg_match( '/^(\d+)@(\d+)#([0-9a-f]{32})$/', $value, $m ) ) {
			return $placeholder; // invalid
		}

		$index = (int)$m[1];
		if ( $index <= 0 ) {
			return $placeholder; // invalid
		} elseif ( isset( $m[2] ) && $m[2] !== '' && (int)$m[2] < $minTimestamp ) {
			return $placeholder; // expired
		}

		$clientId = ( isset( $m[3] ) && $m[3] !== '' ) ? $m[3] : null;

		return [ 'index' => $index, 'clientId' => $clientId ];
	}

	public function setRequestInfo( array $info ) {
		if ( $this->chronProt ) {
			throw new LogicException( 'ChronologyProtector already initialized' );
		}

		$this->requestInfo = $info + $this->requestInfo;
	}

	public function setDefaultReplicationWaitTimeout( $seconds ) {
		$old = $this->replicationWaitTimeout;
		$this->replicationWaitTimeout = max( 1, (int)$seconds );

		return $old;
	}

	/**
	 * @return int Internal instance ID used to assert ownership of ILoadBalancer instances
	 * @since 1.34
	 */
	final protected function getOwnershipId() {
		return $this->id;
	}

	/**
	 * @param string $stage
	 */
	private function assertTransactionRoundStage( $stage ) {
		if ( $this->trxRoundStage !== $stage ) {
			throw new DBTransactionError(
				null,
				"Transaction round stage must be '$stage' (not '{$this->trxRoundStage}')"
			);
		}
	}

	public function __destruct() {
		$this->destroy();
	}

	/**
	 * @param float|null &$time Mock UNIX timestamp for testing
	 * @codeCoverageIgnore
	 */
	public function setMockTime( &$time ) {
		$this->getChronologyProtector()->setMockTime( $time );
	}
}