853 lines
35 KiB
PHP
853 lines
35 KiB
PHP
<?php
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/**
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* Database load balancing interface
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup Database
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*/
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namespace Wikimedia\Rdbms;
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use Exception;
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use InvalidArgumentException;
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use LogicException;
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/**
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* Database cluster connection, tracking, load balancing, and transaction manager interface
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*
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* A "cluster" is considered to be one primary database and zero or more replica databases.
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* Typically, the replica DBs replicate from the primary asynchronously. The first node in the
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* "servers" configuration array is always considered the "primary". However, this class can still
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* be used when all or some of the "replica" DBs are multi-primary peers of the primary or even
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* when all the DBs are non-replicating clones of each other holding read-only data. Thus, the
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* role of "primary" is in some cases merely nominal.
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*
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* By default, each DB server uses DBO_DEFAULT for its 'flags' setting, unless explicitly set
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* otherwise in configuration. DBO_DEFAULT behavior depends on whether 'cliMode' is set:
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* - In CLI mode, the flag has no effect with regards to LoadBalancer.
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* - In non-CLI mode, the flag causes implicit transactions to be used; the first query on
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* a database starts a transaction on that database. The transactions are meant to remain
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* pending until either commitPrimaryChanges() or rollbackPrimaryChanges() is called. The
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* application must have some point where it calls commitPrimaryChanges() near the end of
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* the PHP request.
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* Every iteration of beginPrimaryChanges()/commitPrimaryChanges() is called a "transaction round".
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* Rounds are useful on the primary DB connections because they make single-DB (and by and large
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* multi-DB) updates in web requests all-or-nothing. Also, transactions on replica DBs are useful
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* when REPEATABLE-READ or SERIALIZABLE isolation is used because all foreign keys and constraints
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* hold across separate queries in the DB transaction since the data appears within a consistent
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* point-in-time snapshot.
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*
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* The typical caller will use LoadBalancer::getConnection( DB_* ) to yield a live database
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* connection handle. The choice of which DB server to use is based on pre-defined loads for
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* weighted random selection, adjustments thereof by LoadMonitor, and the amount of replication
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* lag on each DB server. Lag checks might cause problems in certain setups, so they should be
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* tuned in the server configuration maps as follows:
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* - Primary + N Replica(s): set 'max lag' to an appropriate threshold for avoiding any database
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* lagged by this much or more. If all DBs are this lagged, then the load balancer considers
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* the cluster to be read-only.
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* - Galera Cluster: Seconds_Behind_Master will be 0, so there probably is nothing to tune.
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* Note that lag is still possible depending on how wsrep-sync-wait is set server-side.
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* - Read-only archive clones: set 'is static' in the server configuration maps. This will
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* treat all such DBs as having 0 lag.
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* - Externally updated dataset clones: set 'is static' in the server configuration maps.
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* This will treat all such DBs as having 0 lag.
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* - SQL load balancing proxy: any proxy should handle lag checks on its own, so the 'max lag'
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* parameter should probably be set to INF in the server configuration maps. This will make
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* the load balancer ignore whatever it detects as the lag of the logical replica is (which
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* would probably just randomly bounce around).
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*
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* If using a SQL proxy service, it would probably be best to have two proxy hosts for the
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* load balancer to talk to. One would be the 'host' of the primary server entry and another for
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* the (logical) replica server entry. The proxy could map the load balancer's "replica" DB to
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* any number of physical replica DBs.
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*
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* @since 1.28
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* @ingroup Database
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*/
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interface ILoadBalancer {
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/** Request a replica DB connection */
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public const DB_REPLICA = -1;
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/**
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* Request a primary, write-enabled DB connection
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* @since 1.36
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*/
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public const DB_PRIMARY = -2;
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// phpcs:disable MediaWiki.Usage.DeprecatedConstantUsage.DB_MASTER
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/**
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* Request a primary, write-enabled DB connection
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* @deprecated since 1.36, Use DB_PRIMARY instead
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*/
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public const DB_MASTER = self::DB_PRIMARY;
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// phpcs:enable MediaWiki.Usage.DeprecatedConstantUsage.DB_MASTER
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/** Domain specifier when no specific database needs to be selected */
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public const DOMAIN_ANY = '';
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/** The generic query group */
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public const GROUP_GENERIC = '';
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/** DB handle should have DBO_TRX disabled and the caller will leave it as such */
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public const CONN_TRX_AUTOCOMMIT = 1;
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/** Return null on connection failure instead of throwing an exception */
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public const CONN_SILENCE_ERRORS = 2;
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/** Caller is requesting the primary DB server for possibly writes */
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public const CONN_INTENT_WRITABLE = 4;
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/** Bypass and update any server-side read-only mode state cache */
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public const CONN_REFRESH_READ_ONLY = 8;
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/** Manager of ILoadBalancer instances is running post-commit callbacks */
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public const STAGE_POSTCOMMIT_CALLBACKS = 'stage-postcommit-callbacks';
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/** Manager of ILoadBalancer instances is running post-rollback callbacks */
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public const STAGE_POSTROLLBACK_CALLBACKS = 'stage-postrollback-callbacks';
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/**
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* Construct a manager of IDatabase connection objects
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*
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* @param array $params Parameter map with keys:
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* - servers : List of server info structures
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* - localDomain: A DatabaseDomain or domain ID string
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* - loadMonitor : LoadMonitor::__construct() parameters with "class" field. [optional]
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* - readOnlyReason : Reason the primary DB is read-only if so [optional]
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* - waitTimeout : Maximum time to wait for replicas for consistency [optional]
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* - maxLag: Try to avoid DB replicas with lag above this many seconds [optional]
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* - srvCache : BagOStuff object for server cache [optional]
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* - wanCache : WANObjectCache object [optional]
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* - chronologyCallback: Callback to run before the first connection attempt [optional]
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* - defaultGroup: Default query group; the generic group if not specified [optional]
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* - hostname : The name of the current server [optional]
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* - cliMode: Whether the execution context is a CLI script [optional]
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* - profiler : Callback that takes a section name argument and returns
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* a ScopedCallback instance that ends the profile section in its destructor [optional]
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* - trxProfiler: TransactionProfiler instance [optional]
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* - replLogger: PSR-3 logger instance [optional]
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* - connLogger: PSR-3 logger instance [optional]
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* - queryLogger: PSR-3 logger instance [optional]
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* - perfLogger: PSR-3 logger instance [optional]
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* - errorLogger : Callback that takes an Exception and logs it [optional]
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* - deprecationLogger: Callback to log a deprecation warning [optional]
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* - roundStage: STAGE_POSTCOMMIT_* class constant; for internal use [optional]
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* - ownerId: integer ID of an LBFactory instance that manages this instance [optional]
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* - clusterName: The logical name of the DB cluster [optional]
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* - criticalSectionProvider: CriticalSectionProvider instance [optional]
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* @throws InvalidArgumentException
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*/
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public function __construct( array $params );
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/**
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* Get the logical name of the database cluster
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*
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* This is useful for identifying a cluster or replicated dataset, even when:
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* - The primary server is sometimes swapped with another one
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* - The cluster/dataset is replicated among multiple datacenters, with one "primary"
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* datacenter having the writable primary server and the other datacenters having a
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* read-only replica in the "primary" server slot
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* - The dataset is replicated among multiple datacenters, via circular replication,
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* with each datacenter having its own "primary" server
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*
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* @return string
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* @since 1.36
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*/
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public function getClusterName(): string;
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/**
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* Get the local (and default) database domain ID of connection handles
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*
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* @see DatabaseDomain
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* @return string Database domain ID; this specifies DB name, schema, and table prefix
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* @since 1.31
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*/
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public function getLocalDomainID(): string;
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/**
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* @param DatabaseDomain|string|bool $domain Database domain
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* @return string Value of $domain if it is foreign or the local domain otherwise
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* @since 1.32
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*/
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public function resolveDomainID( $domain ): string;
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/**
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* Close all connection and redefine the local domain for testing or schema creation
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*
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* @param DatabaseDomain|string $domain
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* @since 1.33
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*/
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public function redefineLocalDomain( $domain );
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/**
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* Indicate whether the tables on this domain are only temporary tables for testing
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*
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* In "temporary tables mode", the ILoadBalancer::CONN_TRX_AUTOCOMMIT flag is ignored
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*
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* @param bool $value
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* @param string $domain
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* @return bool Whether "temporary tables mode" was active
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* @since 1.34
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*/
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public function setTempTablesOnlyMode( $value, $domain );
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/**
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* Get the specific server index of the reader connection for a given group
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*
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* This takes into account load ratios and lag times. It should return a consistent
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* index during the life time of the load balancer. This initially checks replica DBs
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* for connectivity to avoid returning an unusable server. This means that connections
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* might be attempted by calling this method (usually one at the most but possibly more).
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* Subsequent calls with the same $group will not need to make new connection attempts
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* since the acquired connection for each group is preserved.
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*
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* @param string|bool $group Query group or false for the generic group
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* @param string|bool $domain DB domain ID or false for the local domain
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* @return int|bool Specific server index, or false if no live handle can be obtained
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*/
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public function getReaderIndex( $group = false, $domain = false );
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/**
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* Set the primary position to reach before the next generic group DB handle query
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*
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* If a generic replica DB connection is already open then this immediately waits
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* for that DB to catch up to the specified replication position. Otherwise, it will
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* do so once such a connection is opened.
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*
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* If a timeout happens when waiting, then getLaggedReplicaMode()/laggedReplicaUsed()
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* will return true. This is useful for discouraging clients from taking further actions
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* if session consistency could not be maintained with respect to their last actions.
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*
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* @param DBPrimaryPos|bool $pos Primary position or false
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*/
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public function waitFor( $pos );
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/**
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* Set the primary wait position and wait for ALL replica DBs to catch up to it
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*
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* This method is only intended for use a throttling mechanism for high-volume updates.
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* Unlike waitFor(), failure does not effect getLaggedReplicaMode()/laggedReplicaUsed().
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*
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* @param DBPrimaryPos|bool $pos Primary position or false
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* @param int|null $timeout Max seconds to wait; default is mWaitTimeout
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* @return bool Success (able to connect and no timeouts reached)
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*/
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public function waitForAll( $pos, $timeout = null );
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/**
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* Get an existing live handle to the given server index (on any domain)
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*
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* Use the CONN_TRX_AUTOCOMMIT flag to only look for connections opened with that flag.
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*
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* Avoid the use of begin()/commit() and startAtomic()/endAtomic() on any handle returned.
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* This method is largely intended for internal by RDBMs callers that issue queries that do
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* not affect any current transaction.
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*
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* @param int $i Specific or virtual (DB_PRIMARY/DB_REPLICA) server index
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* @param int $flags Bitfield of CONN_* class constants
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* @return Database|bool False if no such connection is open
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*/
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public function getAnyOpenConnection( $i, $flags = 0 );
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/**
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* Get a live handle for a specific or virtual (DB_PRIMARY/DB_REPLICA) server index
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*
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* The server index, $i, can be one of the following:
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* - DB_REPLICA: a server index will be selected by the load balancer based on read
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* weight, connectivity, and replication lag. Note that the primary server might be
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* configured with read weight. If $groups is empty then it means "the generic group",
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* in which case all servers defined with read weight will be considered. Additional
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* query groups can be configured, having their own list of server indexes and read
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* weights. If a query group list is provided in $groups, then each recognized group
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* will be tried, left-to-right, until server index selection succeeds or all groups
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* have been tried, in which case the generic group will be tried.
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* - DB_PRIMARY: the primary server index will be used; the same as getWriterIndex().
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* The value of $groups should be [] when using this server index.
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* - Specific server index: a positive integer can be provided to use the server with
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* that index. An error will be thrown in no such server index is recognized. This
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* server selection method is usually only useful for internal load balancing logic.
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* The value of $groups should be [] when using a specific server index.
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*
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* Handles acquired by this method, getConnectionRef(), getLazyConnectionRef(), and
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* getMaintenanceConnectionRef() use the same set of shared connection pools. Callers that
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* get a *local* DB domain handle for the same server will share one handle for all of those
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* callers using CONN_TRX_AUTOCOMMIT (via $flags) and one handle for all of those callers not
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* using CONN_TRX_AUTOCOMMIT. Callers that get a *foreign* DB domain handle (via $domain) will
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* share any handle that has the right CONN_TRX_AUTOCOMMIT mode and is already on the right
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* DB domain. Otherwise, one of the "free for reuse" handles will be claimed or a new handle
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* will be made if there are none.
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*
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* Handle sharing is particularly useful when callers get local DB domain (the default),
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* transaction round aware (the default), DB_PRIMARY handles. All such callers will operate
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* within a single database transaction as a consequence. Handle sharing is also useful when
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* callers get local DB domain (the default), transaction round aware (the default), samely
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* query grouped (the default), DB_REPLICA handles. All such callers will operate within a
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* single database transaction as a consequence.
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*
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* Callers of this function that use a non-local $domain must call reuseConnection() after
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* their last query on this handle executed. This lets the load balancer share the handle with
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* other callers requesting connections on different database domains.
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*
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* Use CONN_TRX_AUTOCOMMIT to use a separate pool of only auto-commit handles. This flag
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* is ignored for databases with ATTR_DB_LEVEL_LOCKING (e.g. sqlite) in order to avoid
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* deadlocks. getServerAttributes() can be used to check such attributes beforehand. Avoid
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* using IDatabase::begin() and IDatabase::commit() on such handles. If it is not possible
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* to avoid using methods like IDatabase::startAtomic() and IDatabase::endAtomic(), callers
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* should at least make sure that the atomic sections are closed on failure via try/catch
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* and IDatabase::cancelAtomic().
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*
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* @see ILoadBalancer::reuseConnection()
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* @see ILoadBalancer::getServerAttributes()
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*
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* @param int $i Specific (overrides $groups) or virtual (DB_PRIMARY/DB_REPLICA) server index
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* @param string[]|string $groups Query group(s) in preference order; [] for the default group
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* @param string|bool $domain DB domain ID or false for the local domain
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* @param int $flags Bitfield of CONN_* class constants
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*
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* @note This method throws DBAccessError if ILoadBalancer::disable() was called
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*
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* @return IDatabase|bool This returns false on failure if CONN_SILENCE_ERRORS is set
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* @throws DBError If no live handle could be obtained and CONN_SILENCE_ERRORS is not set
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* @throws DBAccessError If disable() was previously called
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* @throws InvalidArgumentException
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*/
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public function getConnection( $i, $groups = [], $domain = false, $flags = 0 );
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/**
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* Get a live handle for a specific server index
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*
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* This is a simpler version of getConnection() that does not accept virtual server
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* indexes (e.g. DB_PRIMARY/DB_REPLICA), does not assure that primary DB handles have
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* read-only mode when there is high replication lag, and can only trigger attempts
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* to connect to a single server (the one with the specified server index).
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*
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* @see ILoadBalancer::getConnection()
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*
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* @param int $i Specific server index
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* @param string $domain Resolved DB domain
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* @param int $flags Bitfield of class CONN_* constants
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* @return IDatabase|false This returns false on failure if CONN_SILENCE_ERRORS is set
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* @throws DBError If no live handle could be obtained and CONN_SILENCE_ERRORS is not set
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* @internal Only for use within ILoadBalancer/ILoadMonitor
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*/
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public function getServerConnection( $i, $domain, $flags = 0 );
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/**
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* Mark a live handle as being available for reuse under a different database domain
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*
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* This mechanism is reference-counted, and must be called the same number of times as
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* getConnection() to work. Never call this on handles acquired via getConnectionRef(),
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* getLazyConnectionRef(), and getMaintenanceConnectionRef(), as they already manage
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* the logic of calling this method when they fall out of scope in PHP.
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*
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* @see ILoadBalancer::getConnection()
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*
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* @param IDatabase $conn
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* @throws LogicException
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*/
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public function reuseConnection( IDatabase $conn );
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/**
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* Get a live database handle reference for a server index
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*
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* The CONN_TRX_AUTOCOMMIT flag is ignored for databases with ATTR_DB_LEVEL_LOCKING
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* (e.g. sqlite) in order to avoid deadlocks. The getServerAttributes() method can be used
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* to check such flags beforehand. Avoid the use of begin() or startAtomic()
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* on any CONN_TRX_AUTOCOMMIT connections.
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*
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* @see ILoadBalancer::getConnection() for parameter information
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*
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* @param int $i Specific or virtual (DB_PRIMARY/DB_REPLICA) server index
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* @param string[]|string $groups Query group(s) in preference order; [] for the default group
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* @param string|bool $domain DB domain ID or false for the local domain
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* @param int $flags Bitfield of CONN_* class constants (e.g. CONN_TRX_AUTOCOMMIT)
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* @return DBConnRef
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*/
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public function getConnectionRef( $i, $groups = [], $domain = false, $flags = 0 ): IDatabase;
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/**
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* Get a lazy-connecting database handle reference for a server index
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*
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* The handle's methods simply proxy to those of an underlying IDatabase handle which
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* takes care of the actual connection and query logic.
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*
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* The CONN_TRX_AUTOCOMMIT flag is ignored for databases with ATTR_DB_LEVEL_LOCKING
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* (e.g. sqlite) in order to avoid deadlocks. getServerAttributes()
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* can be used to check such flags beforehand. Avoid the use of begin() or startAtomic()
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* on any CONN_TRX_AUTOCOMMIT connections.
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*
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* @see ILoadBalancer::getConnection() for parameter information
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*
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* @param int $i Specific or virtual (DB_PRIMARY/DB_REPLICA) server index
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* @param string[]|string $groups Query group(s) in preference order; [] for the default group
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* @param string|bool $domain DB domain ID or false for the local domain
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* @param int $flags Bitfield of CONN_* class constants
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* @return IDatabase Live connection handle
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* @throws DBError If no live handle could be obtained
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* @throws DBAccessError If disable() was previously called
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* @deprecated since 1.38 use getConnectionRef instead
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*/
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public function getLazyConnectionRef( $i, $groups = [], $domain = false, $flags = 0 ): IDatabase;
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/**
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* Get a live database handle, suitable for migrations and schema changes, for a server index
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*
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* The handle's methods simply proxy to those of an underlying IDatabase handle which
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* takes care of the actual connection and query logic.
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*
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* The CONN_TRX_AUTOCOMMIT flag is ignored for databases with ATTR_DB_LEVEL_LOCKING
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* (e.g. sqlite) in order to avoid deadlocks. getServerAttributes()
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* can be used to check such flags beforehand. Avoid the use of begin() or startAtomic()
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* on any CONN_TRX_AUTOCOMMIT connections.
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*
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* @see ILoadBalancer::getConnection() for parameter information
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*
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* @param int $i Specific or virtual (DB_PRIMARY/DB_REPLICA) server index
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* @param string[]|string $groups Query group(s) in preference order; [] for the default group
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* @param string|bool $domain DB domain ID or false for the local domain
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* @param int $flags Bitfield of CONN_* class constants (e.g. CONN_TRX_AUTOCOMMIT)
|
|
* @return DBConnRef Live connection handle
|
|
* @throws DBError If no live handle could be obtained
|
|
* @throws DBAccessError If disable() was previously called
|
|
*/
|
|
public function getMaintenanceConnectionRef( $i, $groups = [], $domain = false, $flags = 0 ): DBConnRef;
|
|
|
|
/**
|
|
* Get the specific server index of the primary server
|
|
*
|
|
* @return int
|
|
*/
|
|
public function getWriterIndex();
|
|
|
|
/**
|
|
* Get the number of servers defined in configuration
|
|
*
|
|
* @return int
|
|
*/
|
|
public function getServerCount();
|
|
|
|
/**
|
|
* Whether there are any replica servers configured
|
|
*
|
|
* This counts both servers using streaming replication from the primary server and
|
|
* servers that just have a clone of the static dataset found on the primary server
|
|
*
|
|
* @return bool
|
|
* @since 1.34
|
|
*/
|
|
public function hasReplicaServers();
|
|
|
|
/**
|
|
* Whether any replica servers use streaming replication from the primary server
|
|
*
|
|
* Generally this is one less than getServerCount(), though it might otherwise
|
|
* return a lower number if some of the servers are configured with "is static".
|
|
* That flag is used when both the server has no active replication setup and the
|
|
* dataset is either read-only or occasionally updated out-of-band. For example,
|
|
* a script might import a new geographic information dataset each week by writing
|
|
* it to each server and later directing the application to use the new version.
|
|
*
|
|
* It is possible for some replicas to be configured with "is static" but not
|
|
* others, though it generally should either be set for all or none of the replicas.
|
|
*
|
|
* If this returns false, this means that there is generally no reason to execute
|
|
* replication wait logic for session consistency and lag reduction.
|
|
*
|
|
* @return bool
|
|
* @since 1.34
|
|
*/
|
|
public function hasStreamingReplicaServers();
|
|
|
|
/**
|
|
* Get the readable name of the server with the specified index
|
|
*
|
|
* @param int $i Specific server index
|
|
* @return string Readable server name, falling back to the hostname or IP address
|
|
*/
|
|
public function getServerName( $i ): string;
|
|
|
|
/**
|
|
* Return the server configuration map for the server with the specified index
|
|
*
|
|
* @param int $i Specific server index
|
|
* @return array|false Server configuration map; false if the index is invalid
|
|
* @since 1.31
|
|
*/
|
|
public function getServerInfo( $i );
|
|
|
|
/**
|
|
* Get the RDBMS type of the server with the specified index (e.g. "mysql", "sqlite")
|
|
*
|
|
* @param int $i Specific server index
|
|
* @return string One of (mysql,postgres,sqlite,...) or "unknown" for bad indexes
|
|
* @since 1.30
|
|
*/
|
|
public function getServerType( $i );
|
|
|
|
/**
|
|
* Get basic attributes of the server with the specified index without connecting
|
|
*
|
|
* @param int $i Specific server index
|
|
* @return array (Database::ATTRIBUTE_* constant => value) for all such constants
|
|
* @since 1.31
|
|
*/
|
|
public function getServerAttributes( $i );
|
|
|
|
/**
|
|
* Get the current primary replication position
|
|
*
|
|
* @return DBPrimaryPos|bool Returns false if not applicable
|
|
* @throws DBError
|
|
* @since 1.37
|
|
*/
|
|
public function getPrimaryPos();
|
|
|
|
/**
|
|
* Get the highest DB replication position for chronology control purposes
|
|
*
|
|
* If there is only a primary server then this returns false. If replication is present
|
|
* and correctly configured, then this returns the highest replication position of any
|
|
* server with an open connection. That position can later be passed to waitFor() on a
|
|
* new load balancer instance to make sure that queries on the new connections see data
|
|
* at least as up-to-date as queries (prior to this method call) on the old connections.
|
|
*
|
|
* This can be useful for implementing session consistency, where the session
|
|
* will be resumed across multiple HTTP requests or CLI script instances.
|
|
*
|
|
* @return DBPrimaryPos|bool Replication position or false if not applicable
|
|
* @since 1.34
|
|
*/
|
|
public function getReplicaResumePos();
|
|
|
|
/**
|
|
* Close all connections and disable this load balancer
|
|
*
|
|
* Any attempt to open a new connection will result in a DBAccessError.
|
|
*
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
*/
|
|
public function disable( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Close all open connections
|
|
*
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
*/
|
|
public function closeAll( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Close a connection
|
|
*
|
|
* Using this function makes sure the LoadBalancer knows the connection is closed.
|
|
* If you use $conn->close() directly, the load balancer won't update its state.
|
|
*
|
|
* @param IDatabase $conn
|
|
*/
|
|
public function closeConnection( IDatabase $conn );
|
|
|
|
/**
|
|
* Commit transactions on all open connections
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
* @throws DBExpectedError
|
|
*/
|
|
public function commitAll( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Run pre-commit callbacks and defer execution of post-commit callbacks
|
|
*
|
|
* Use this only for multi-database commits
|
|
*
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
* @return int Number of pre-commit callbacks run (since 1.32)
|
|
* @since 1.37
|
|
*/
|
|
public function finalizePrimaryChanges( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Perform all pre-commit checks for things like replication safety
|
|
*
|
|
* Use this only for multi-database commits
|
|
*
|
|
* @param array $options Includes:
|
|
* - maxWriteDuration : max write query duration time in seconds
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
* @throws DBTransactionError
|
|
* @since 1.37
|
|
*/
|
|
public function approvePrimaryChanges( array $options, $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Flush any primary transaction snapshots and set DBO_TRX (if DBO_DEFAULT is set)
|
|
*
|
|
* The DBO_TRX setting will be reverted to the default in each of these methods:
|
|
* - commitPrimaryChanges()
|
|
* - rollbackPrimaryChanges()
|
|
* - commitAll()
|
|
* This allows for custom transaction rounds from any outer transaction scope.
|
|
*
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
* @throws DBExpectedError
|
|
* @since 1.37
|
|
*/
|
|
public function beginPrimaryChanges( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Issue COMMIT on all open primary connections to flush changes and view snapshots
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
* @throws DBExpectedError
|
|
* @since 1.37
|
|
*/
|
|
public function commitPrimaryChanges( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Consume and run all pending post-COMMIT/ROLLBACK callbacks and commit dangling transactions
|
|
*
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
* @return Exception|null The first exception or null if there were none
|
|
* @since 1.37
|
|
*/
|
|
public function runPrimaryTransactionIdleCallbacks( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Run all recurring post-COMMIT/ROLLBACK listener callbacks
|
|
*
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
* @return Exception|null The first exception or null if there were none
|
|
* @since 1.37
|
|
*/
|
|
public function runPrimaryTransactionListenerCallbacks( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Issue ROLLBACK only on primary, only if queries were done on connection
|
|
*
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
* @throws DBExpectedError
|
|
* @since 1.37
|
|
*/
|
|
public function rollbackPrimaryChanges( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Release/destroy session-level named locks, table locks, and temp tables
|
|
*
|
|
* Only call this function right after calling rollbackPrimaryChanges()
|
|
*
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
* @throws DBExpectedError
|
|
* @since 1.38
|
|
*/
|
|
public function flushPrimarySessions( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshots
|
|
*
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
*/
|
|
public function flushReplicaSnapshots( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* Commit all primary DB transactions so as to flush any REPEATABLE-READ or SSI snapshots
|
|
*
|
|
* An error will be thrown if a connection has pending writes or callbacks
|
|
*
|
|
* @param string $fname Caller name
|
|
* @param int|null $owner ID of the calling instance (e.g. the LBFactory ID)
|
|
* @since 1.37
|
|
*/
|
|
public function flushPrimarySnapshots( $fname = __METHOD__, $owner = null );
|
|
|
|
/**
|
|
* @return bool Whether a primary connection is already open
|
|
* @since 1.37
|
|
*/
|
|
public function hasPrimaryConnection();
|
|
|
|
/**
|
|
* Whether there are pending changes or callbacks in a transaction by this thread
|
|
* @return bool
|
|
* @since 1.37
|
|
*/
|
|
public function hasPrimaryChanges();
|
|
|
|
/**
|
|
* Get the timestamp of the latest write query done by this thread
|
|
* @return float|bool UNIX timestamp or false
|
|
* @since 1.37
|
|
*/
|
|
public function lastPrimaryChangeTimestamp();
|
|
|
|
/**
|
|
* Check if this load balancer object had any recent or still
|
|
* pending writes issued against it by this PHP thread
|
|
*
|
|
* @param float|null $age How many seconds ago is "recent" [defaults to mWaitTimeout]
|
|
* @return bool
|
|
* @since 1.37
|
|
*/
|
|
public function hasOrMadeRecentPrimaryChanges( $age = null );
|
|
|
|
/**
|
|
* Get the list of callers that have pending primary changes
|
|
*
|
|
* @return string[] List of method names
|
|
* @since 1.37
|
|
*/
|
|
public function pendingPrimaryChangeCallers();
|
|
|
|
/**
|
|
* @note This method will trigger a DB connection if not yet done
|
|
* @param string|bool $domain DB domain ID or false for the local domain
|
|
* @return bool Whether the database for generic connections this request is highly "lagged"
|
|
*/
|
|
public function getLaggedReplicaMode( $domain = false );
|
|
|
|
/**
|
|
* Checks whether the database for generic connections this request was both:
|
|
* - a) Already chosen due to a prior connection attempt
|
|
* - b) Considered highly "lagged"
|
|
*
|
|
* @note This method will never cause a new DB connection
|
|
* @return bool
|
|
*/
|
|
public function laggedReplicaUsed();
|
|
|
|
/**
|
|
* @note This method may trigger a DB connection if not yet done
|
|
* @param string|bool $domain DB domain ID or false for the local domain
|
|
* @return string|bool Reason the primary is read-only or false if it is not
|
|
*/
|
|
public function getReadOnlyReason( $domain = false );
|
|
|
|
/**
|
|
* @return bool
|
|
*/
|
|
public function pingAll();
|
|
|
|
/**
|
|
* Call a function with each open connection object
|
|
* @param callable $callback
|
|
* @param array $params
|
|
*/
|
|
public function forEachOpenConnection( $callback, array $params = [] );
|
|
|
|
/**
|
|
* Call a function with each open connection object to a primary
|
|
* @param callable $callback
|
|
* @param array $params
|
|
* @since 1.37
|
|
*/
|
|
public function forEachOpenPrimaryConnection( $callback, array $params = [] );
|
|
|
|
/**
|
|
* Get the name and lag time of the most-lagged replica server
|
|
*
|
|
* This is useful for maintenance scripts that need to throttle their updates.
|
|
* May attempt to open connections to replica DBs on the default DB. If there is
|
|
* no lag, the maximum lag will be reported as -1.
|
|
*
|
|
* @param bool|string $domain Domain ID or false for the default database
|
|
* @return array{0:string,1:float|int|false,2:int} (host, max lag, index of max lagged host)
|
|
*/
|
|
public function getMaxLag( $domain = false );
|
|
|
|
/**
|
|
* Get an estimate of replication lag (in seconds) for each server
|
|
*
|
|
* Results are cached for a short time in memcached/process cache
|
|
*
|
|
* Values may be "false" if replication is too broken to estimate
|
|
*
|
|
* @param string|bool $domain
|
|
* @return float[]|int[]|false[] Map of (server index => lag) in order of server index
|
|
*/
|
|
public function getLagTimes( $domain = false );
|
|
|
|
/**
|
|
* Wait for a replica DB to reach a specified primary position
|
|
*
|
|
* If $conn is not a replica server connection, then this will return true.
|
|
* Otherwise, if $pos is not provided, this will connect to the primary server
|
|
* to get an accurate position.
|
|
*
|
|
* @param IDatabase $conn Replica DB
|
|
* @param DBPrimaryPos|bool $pos Primary position; default: current position
|
|
* @param int $timeout Timeout in seconds [optional]
|
|
* @return bool Success
|
|
* @since 1.37
|
|
*/
|
|
public function waitForPrimaryPos( IDatabase $conn, $pos = false, $timeout = 10 );
|
|
|
|
/**
|
|
* Set a callback via IDatabase::setTransactionListener() on
|
|
* all current and future primary connections of this load balancer
|
|
*
|
|
* @param string $name Callback name
|
|
* @param callable|null $callback
|
|
*/
|
|
public function setTransactionListener( $name, callable $callback = null );
|
|
|
|
/**
|
|
* Set a new table prefix for the existing local domain ID for testing
|
|
*
|
|
* @param string $prefix
|
|
* @since 1.33
|
|
*/
|
|
public function setLocalDomainPrefix( $prefix );
|
|
|
|
/**
|
|
* Make certain table names use their own database, schema, and table prefix
|
|
* when passed into SQL queries pre-escaped and without a qualified database name
|
|
*
|
|
* For example, "user" can be converted to "myschema.mydbname.user" for convenience.
|
|
* Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
|
|
*
|
|
* Calling this twice will completely clear any old table aliases. Also, note that
|
|
* callers are responsible for making sure the schemas and databases actually exist.
|
|
*
|
|
* @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
|
|
*/
|
|
public function setTableAliases( array $aliases );
|
|
|
|
/**
|
|
* Convert certain index names to alternative names before querying the DB
|
|
*
|
|
* Note that this applies to indexes regardless of the table they belong to.
|
|
*
|
|
* This can be employed when an index was renamed X => Y in code, but the new Y-named
|
|
* indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
|
|
* the aliases can be removed, and then the old X-named indexes dropped.
|
|
*
|
|
* @param string[] $aliases
|
|
* @since 1.31
|
|
*/
|
|
public function setIndexAliases( array $aliases );
|
|
|
|
/**
|
|
* Convert certain database domains to alternative ones.
|
|
*
|
|
* This can be used for backwards compatibility logic.
|
|
*
|
|
* @param DatabaseDomain[]|string[] $aliases Map of (domain alias => domain)
|
|
* @since 1.35
|
|
*/
|
|
public function setDomainAliases( array $aliases );
|
|
}
|