317 lines
11 KiB
PHP
317 lines
11 KiB
PHP
<?php
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/**
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* Generator and manager of database load balancing objects
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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 InvalidArgumentException;
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/**
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* An interface for generating database load balancers
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* @ingroup Database
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* @since 1.28
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*/
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interface ILBFactory {
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const SHUTDOWN_NO_CHRONPROT = 0; // don't save DB positions at all
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const SHUTDOWN_CHRONPROT_ASYNC = 1; // save DB positions, but don't wait on remote DCs
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const SHUTDOWN_CHRONPROT_SYNC = 2; // save DB positions, waiting on all DCs
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/**
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* Construct a manager of ILoadBalancer objects
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*
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* Sub-classes will extend the required keys in $conf with additional parameters
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*
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* @param $conf $params Array with keys:
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* - localDomain: A DatabaseDomain or domain ID string.
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* - readOnlyReason : Reason the master DB is read-only if so [optional]
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* - srvCache : BagOStuff object for server cache [optional]
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* - memCache : BagOStuff object for cluster memory cache [optional]
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* - wanCache : WANObjectCache object [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 : Class name or instance with profileIn()/profileOut() methods. [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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* @throws InvalidArgumentException
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*/
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public function __construct( array $conf );
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/**
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* Disables all load balancers. All connections are closed, and any attempt to
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* open a new connection will result in a DBAccessError.
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* @see ILoadBalancer::disable()
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*/
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public function destroy();
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/**
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* Create a new load balancer object. The resulting object will be untracked,
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* not chronology-protected, and the caller is responsible for cleaning it up.
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*
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* This method is for only advanced usage and callers should almost always use
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* getMainLB() instead. This method can be useful when a table is used as a key/value
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* store. In that cases, one might want to query it in autocommit mode (DBO_TRX off)
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* but still use DBO_TRX transaction rounds on other tables.
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*
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* @param bool|string $domain Domain ID, or false for the current domain
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* @return ILoadBalancer
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*/
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public function newMainLB( $domain = false );
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/**
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* Get a cached (tracked) load balancer object.
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*
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* @param bool|string $domain Domain ID, or false for the current domain
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* @return ILoadBalancer
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*/
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public function getMainLB( $domain = false );
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/**
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* Create a new load balancer for external storage. The resulting object will be
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* untracked, not chronology-protected, and the caller is responsible for cleaning it up.
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*
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* This method is for only advanced usage and callers should almost always use
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* getExternalLB() instead. This method can be useful when a table is used as a
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* key/value store. In that cases, one might want to query it in autocommit mode
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* (DBO_TRX off) but still use DBO_TRX transaction rounds on other tables.
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*
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* @param string $cluster External storage cluster name
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* @return ILoadBalancer
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*/
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public function newExternalLB( $cluster );
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/**
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* Get a cached (tracked) load balancer for external storage
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*
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* @param string $cluster External storage cluster name
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* @return ILoadBalancer
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*/
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public function getExternalLB( $cluster );
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/**
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* Get cached (tracked) load balancers for all main database clusters
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*
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* @return LoadBalancer[] Map of (cluster name => LoadBalancer)
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* @since 1.29
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*/
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public function getAllMainLBs();
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/**
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* Get cached (tracked) load balancers for all external database clusters
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*
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* @return LoadBalancer[] Map of (cluster name => LoadBalancer)
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* @since 1.29
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*/
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public function getAllExternalLBs();
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/**
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* Execute a function for each tracked load balancer
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* The callback is called with the load balancer as the first parameter,
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* and $params passed as the subsequent parameters.
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*
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* @param callable $callback
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* @param array $params
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*/
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public function forEachLB( $callback, array $params = [] );
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/**
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* Prepare all tracked load balancers for shutdown
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* @param integer $mode One of the class SHUTDOWN_* constants
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* @param callable|null $workCallback Work to mask ChronologyProtector writes
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*/
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public function shutdown(
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$mode = self::SHUTDOWN_CHRONPROT_SYNC, callable $workCallback = null
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);
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/**
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* Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshot
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*
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* @param string $fname Caller name
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*/
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public function flushReplicaSnapshots( $fname = __METHOD__ );
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/**
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* Commit open transactions on all connections. This is useful for two main cases:
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* - a) To commit changes to the masters.
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* - b) To release the snapshot on all connections, master and replica DBs.
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* @param string $fname Caller name
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* @param array $options Options map:
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* - maxWriteDuration: abort if more than this much time was spent in write queries
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*/
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public function commitAll( $fname = __METHOD__, array $options = [] );
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/**
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* Flush any master transaction snapshots and set DBO_TRX (if DBO_DEFAULT is set)
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*
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* The DBO_TRX setting will be reverted to the default in each of these methods:
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* - commitMasterChanges()
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* - rollbackMasterChanges()
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* - commitAll()
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*
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* This allows for custom transaction rounds from any outer transaction scope.
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*
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* @param string $fname
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* @throws DBTransactionError
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*/
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public function beginMasterChanges( $fname = __METHOD__ );
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/**
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* Commit changes on all master connections
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* @param string $fname Caller name
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* @param array $options Options map:
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* - maxWriteDuration: abort if more than this much time was spent in write queries
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* @throws DBTransactionError
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*/
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public function commitMasterChanges( $fname = __METHOD__, array $options = [] );
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/**
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* Rollback changes on all master connections
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* @param string $fname Caller name
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*/
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public function rollbackMasterChanges( $fname = __METHOD__ );
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/**
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* Determine if any master connection has pending changes
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* @return bool
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*/
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public function hasMasterChanges();
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/**
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* Detemine if any lagged replica DB connection was used
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* @return bool
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*/
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public function laggedReplicaUsed();
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/**
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* Determine if any master connection has pending/written changes from this request
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* @param float $age How many seconds ago is "recent" [defaults to LB lag wait timeout]
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* @return bool
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*/
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public function hasOrMadeRecentMasterChanges( $age = null );
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/**
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* Waits for the replica DBs to catch up to the current master position
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*
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* Use this when updating very large numbers of rows, as in maintenance scripts,
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* to avoid causing too much lag. Of course, this is a no-op if there are no replica DBs.
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*
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* By default this waits on all DB clusters actually used in this request.
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* This makes sense when lag being waiting on is caused by the code that does this check.
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* In that case, setting "ifWritesSince" can avoid the overhead of waiting for clusters
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* that were not changed since the last wait check. To forcefully wait on a specific cluster
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* for a given domain, use the 'domain' parameter. To forcefully wait on an "external" cluster,
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* use the "cluster" parameter.
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*
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* Never call this function after a large DB write that is *still* in a transaction.
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* It only makes sense to call this after the possible lag inducing changes were committed.
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*
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* @param array $opts Optional fields that include:
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* - domain : wait on the load balancer DBs that handles the given domain ID
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* - cluster : wait on the given external load balancer DBs
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* - timeout : Max wait time. Default: ~60 seconds
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* - ifWritesSince: Only wait if writes were done since this UNIX timestamp
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* @throws DBReplicationWaitError If a timeout or error occured waiting on a DB cluster
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*/
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public function waitForReplication( array $opts = [] );
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/**
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* Add a callback to be run in every call to waitForReplication() before waiting
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*
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* Callbacks must clear any transactions that they start
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*
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* @param string $name Callback name
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* @param callable|null $callback Use null to unset a callback
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*/
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public function setWaitForReplicationListener( $name, callable $callback = null );
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/**
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* Get a token asserting that no transaction writes are active
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*
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* @param string $fname Caller name (e.g. __METHOD__)
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* @return mixed A value to pass to commitAndWaitForReplication()
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*/
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public function getEmptyTransactionTicket( $fname );
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/**
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* Convenience method for safely running commitMasterChanges()/waitForReplication()
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*
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* This will commit and wait unless $ticket indicates it is unsafe to do so
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*
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* @param string $fname Caller name (e.g. __METHOD__)
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* @param mixed $ticket Result of getEmptyTransactionTicket()
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* @param array $opts Options to waitForReplication()
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* @throws DBReplicationWaitError
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*/
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public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] );
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/**
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* @param string $dbName DB master name (e.g. "db1052")
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* @return float|bool UNIX timestamp when client last touched the DB or false if not recent
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*/
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public function getChronologyProtectorTouched( $dbName );
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/**
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* Disable the ChronologyProtector for all load balancers
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*
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* This can be called at the start of special API entry points
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*/
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public function disableChronologyProtection();
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/**
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* Set a new table prefix for the existing local domain ID for testing
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*
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* @param string $prefix
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*/
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public function setDomainPrefix( $prefix );
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/**
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* Close all open database connections on all open load balancers.
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*/
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public function closeAll();
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/**
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* @param string $agent Agent name for query profiling
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*/
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public function setAgentName( $agent );
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/**
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* Append ?cpPosTime parameter to a URL for ChronologyProtector purposes if needed
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*
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* Note that unlike cookies, this works accross domains
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*
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* @param string $url
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* @param float $time UNIX timestamp just before shutdown() was called
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* @return string
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*/
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public function appendPreShutdownTimeAsQuery( $url, $time );
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/**
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* @param array $info Map of fields, including:
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* - IPAddress : IP address
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* - UserAgent : User-Agent HTTP header
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* - ChronologyProtection : cookie/header value specifying ChronologyProtector usage
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*/
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public function setRequestInfo( array $info );
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}
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