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Wikimedia\Rdbms\ILBFactory Interface Reference

Manager of ILoadBalancer objects and, indirectly, IDatabase connections. More...

Inherits Wikimedia\Rdbms\IConnectionProvider.

Inherited by Wikimedia\Rdbms\LBFactory.

Collaboration diagram for Wikimedia\Rdbms\ILBFactory:

Public Member Functions

 __construct (array $conf)
 Sub-classes may extend the required keys in $conf with additional parameters.
 
 autoReconfigure ()
 Reload the configuration if necessary.
 
 beginPrimaryChanges ( $fname=__METHOD__)
 Flush any primary transaction snapshots and set DBO_TRX (if DBO_DEFAULT is set)
 
 closeAll ( $fname=__METHOD__)
 Close all connections on instantiated tracked load balancer instances.
 
 commitPrimaryChanges ( $fname=__METHOD__, int $maxWriteDuration=0)
 Commit changes and clear view snapshots on all primary connections.
 
 destroy ()
 Close all connections and make further attempts to open connections result in DBAccessError.
 
 disableChronologyProtection ()
 Disable the ChronologyProtector on all instantiated tracked load balancer instances.
 
 flushPrimarySessions ( $fname=__METHOD__)
 Release important session-level state (named lock, table locks) as post-rollback cleanup.
 
 flushReplicaSnapshots ( $fname=__METHOD__)
 Commit all replica database server transactions, clearing any REPEATABLE-READ/SSI snapshots.
 
 getAllExternalLBs ()
 Get the tracked load balancer instances for all external clusters.
 
 getAllLBs ()
 Get all tracked load balancer instances (generator)
 
 getAllMainLBs ()
 Get the tracked load balancer instances for all main clusters.
 
 getExternalLB ( $cluster)
 Get the tracked load balancer instance for an external cluster.
 
 getLocalDomainID ()
 Get the local (and default) database domain ID of connection handles.
 
 getMainLB ( $domain=false)
 Get the tracked load balancer instance for the main cluster that handles the given domain.
 
 getTransactionProfiler ()
 Get the TransactionProfiler used by this instance.
 
 hasOrMadeRecentPrimaryChanges ( $age=null)
 Determine if any primary connection has pending/written changes from this request.
 
 hasPrimaryChanges ()
 Determine if any primary connection has pending changes.
 
 hasStreamingReplicaServers ()
 Whether it has streaming replica servers.
 
 hasTransactionRound ()
 Check if an explicit transaction round is active.
 
 isReadyForRoundOperations ()
 Check if transaction rounds can be started, committed, or rolled back right now.
 
 laggedReplicaUsed ()
 Determine if any lagged replica database server connection was used.
 
 newExternalLB ( $cluster)
 Create a new load balancer instance for an external cluster.
 
 newMainLB ( $domain=false)
 Create a new load balancer instance for the main cluster that handles the given domain.
 
 redefineLocalDomain ( $domain)
 Close all connections and redefine the local database domain.
 
 rollbackPrimaryChanges ( $fname=__METHOD__)
 Rollback changes on all primary connections.
 
 setAgentName ( $agent)
 
 setDefaultReplicationWaitTimeout ( $seconds)
 Set the default timeout for replication wait checks.
 
 setDomainAliases (array $aliases)
 Convert certain database domains to alternative ones.
 
 setIndexAliases (array $aliases)
 Convert certain index names to alternative names before querying the DB.
 
 setLocalDomainPrefix ( $prefix)
 Set a new table prefix for the existing local domain ID for testing.
 
 setTableAliases (array $aliases)
 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.
 
 setWaitForReplicationListener ( $name, callable $callback=null)
 Add a callback to be run in every call to waitForReplication() before waiting.
 
 shutdown ( $flags=self::SHUTDOWN_NORMAL, callable $workCallback=null, &$cpIndex=null, &$cpClientId=null)
 Prepare all instantiated tracked load balancer instances for shutdown.
 
 waitForReplication (array $opts=[])
 Waits for the replica database server to catch up to the current primary position.
 
- Public Member Functions inherited from Wikimedia\Rdbms\IConnectionProvider
 commitAndWaitForReplication ( $fname, $ticket, array $opts=[])
 Commit primary DB transactions and wait for replication (if $ticket indicates it is safe).
 
 getEmptyTransactionTicket ( $fname)
 Get a token asserting that no write transactions are active on tracked connections.
 
 getPrimaryDatabase ( $domain=false)
 Get connection to the primary database.
 
 getReplicaDatabase ( $domain=false, $group=null)
 Get connection to a replica database.
 

Public Attributes

const SHUTDOWN_NO_CHRONPROT = 1
 Do not save "session consistency" DB replication positions.
 
const SHUTDOWN_NORMAL = 0
 Idiom for "no special shutdown flags".
 

Detailed Description

Manager of ILoadBalancer objects and, indirectly, IDatabase connections.

Each Load balancer instances corresponds to a specific database cluster. A "cluster" is the set of database servers that manage a given dataset.

The "core" clusters are meant to colocate the most basic and highly relational application data for one or more "sister projects" managed by this site. This allows for highly flexible queries. Each project is identified by a database domain. Note that if there are several projects stored on a cluster, then the cluster dataset is a superset of the dataset for each of those projects.

The "external" clusters are meant to provide places for bulk text storage, to colocate bulky relational data from specific modules, and to colocate data from cross-project modules such as authentication systems. An external cluster can have a database/schema for each project.

See also
ILoadBalancer
Since
1.28

Definition at line 46 of file ILBFactory.php.

Constructor & Destructor Documentation

◆ __construct()

Wikimedia\Rdbms\ILBFactory::__construct ( array $conf)

Sub-classes may extend the required keys in $conf with additional parameters.

Parameters
array$confArray with keys:
  • localDomain: A DatabaseDomain or database domain ID string
  • virtualDomains: List of virtual database domain ID strings [optional]. These can be passed to {
See also
ILBFactory::getPrimaryDatabase()} and {
ILBFactory::getReplicaDatabase()}, with the actual cluster and database domain being automatically resolved via "virtualDomainsMapping". Virtual database domains not defined there will resolve to the local database domain.
  • virtualDomainsMapping: Map of (virtual database domain ID => config map) [optional]. Each config map has a "db" key and an optional "cluster" key. The "db" key specifies the actual database domain configured for use, with false indicating that the local database domain is configured for use. The "cluster" key, if provided, specifies the name of the external cluster configured for use, otherwise, the main cluster for the actual database domain will be used.
  • chronologyProtector: ChronologyProtector instance [optional]
  • readOnlyReason: Reason the primary server is read-only (false if not)
  • srvCache: BagOStuff instance for server cache [optional]
  • cpStash: BagOStuff instance for ChronologyProtector store [optional]. See ChronologyProtector requirements.
  • wanCache: WANObjectCache instance [optional]
  • cliMode: Whether the execution context is a CLI script [optional]
  • profiler: Callback that takes a profile section name and returns a ScopedCallback that ends the profile section in its destructor [optional]
  • trxProfiler: TransactionProfiler instance [optional]
  • logger: PSR-3 logger instance [optional]
  • errorLogger: Callback that takes an Exception and logs it [optional]
  • deprecationLogger: Callback to log a deprecation warning [optional]
  • secret: Secret string to use for HMAC hashing [optional]
  • criticalSectionProvider: CriticalSectionProvider instance [optional]

Implemented in Wikimedia\Rdbms\LBFactory, Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.

Member Function Documentation

◆ autoReconfigure()

Wikimedia\Rdbms\ILBFactory::autoReconfigure ( )

Reload the configuration if necessary.

This may or may not have any effect.

Implemented in Wikimedia\Rdbms\LBFactory.

◆ beginPrimaryChanges()

Wikimedia\Rdbms\ILBFactory::beginPrimaryChanges ( $fname = __METHOD__)

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()

This only applies to the tracked load balancer instances.

This allows for custom transaction rounds from any outer transaction scope.

Parameters
string$fname
Exceptions
DBTransactionError
Since
1.37

Implemented in Wikimedia\Rdbms\LBFactory.

◆ closeAll()

Wikimedia\Rdbms\ILBFactory::closeAll ( $fname = __METHOD__)

Close all connections on instantiated tracked load balancer instances.

Parameters
string$fnameCaller name (e.g. METHOD)

Implemented in Wikimedia\Rdbms\LBFactory.

◆ commitPrimaryChanges()

Wikimedia\Rdbms\ILBFactory::commitPrimaryChanges ( $fname = __METHOD__,
int $maxWriteDuration = 0 )

Commit changes and clear view snapshots on all primary connections.

This only applies to the instantiated tracked load balancer instances.

Parameters
string$fnameCaller name
int$maxWriteDurationabort if more than this much time was spent in write queries
Exceptions
DBTransactionError
Since
1.37

Implemented in Wikimedia\Rdbms\LBFactory.

◆ destroy()

Wikimedia\Rdbms\ILBFactory::destroy ( )

Close all connections and make further attempts to open connections result in DBAccessError.

This only applies to the tracked load balancer instances.

See also
ILoadBalancer::disable()

Implemented in Wikimedia\Rdbms\LBFactory.

◆ disableChronologyProtection()

Wikimedia\Rdbms\ILBFactory::disableChronologyProtection ( )

Disable the ChronologyProtector on all instantiated tracked load balancer instances.

This can be called at the start of special API entry points.

Implemented in Wikimedia\Rdbms\LBFactory.

◆ flushPrimarySessions()

Wikimedia\Rdbms\ILBFactory::flushPrimarySessions ( $fname = __METHOD__)

Release important session-level state (named lock, table locks) as post-rollback cleanup.

This only applies to the instantiated tracked load balancer instances.

This should only be called by application entry point functions, since there must be no chance that a future caller will still be expecting some of the lost session state.

Parameters
string$fnameCaller name
Since
1.38

Implemented in Wikimedia\Rdbms\LBFactory.

◆ flushReplicaSnapshots()

Wikimedia\Rdbms\ILBFactory::flushReplicaSnapshots ( $fname = __METHOD__)

Commit all replica database server transactions, clearing any REPEATABLE-READ/SSI snapshots.

This only applies to the instantiated tracked load balancer instances.

This is useful for getting rid of stale data from an implicit transaction round

Parameters
string$fnameCaller name

Implemented in Wikimedia\Rdbms\LBFactory.

◆ getAllExternalLBs()

Wikimedia\Rdbms\ILBFactory::getAllExternalLBs ( )

Get the tracked load balancer instances for all external clusters.

If no tracked instance exists for a cluster, then one will be instantiated

Returns
ILoadBalancer[] Map of (cluster name => ILoadBalancer)
Since
1.29

Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.

◆ getAllLBs()

Wikimedia\Rdbms\ILBFactory::getAllLBs ( )

Get all tracked load balancer instances (generator)

Returns
Generator|ILoadBalancer[]
Since
1.39

Implemented in Wikimedia\Rdbms\LBFactory.

◆ getAllMainLBs()

Wikimedia\Rdbms\ILBFactory::getAllMainLBs ( )

Get the tracked load balancer instances for all main clusters.

If no tracked instance exists for a cluster, then one will be instantiated

Note that default main cluster name is ILoadBalancer::CLUSTER_MAIN_DEFAULT

Returns
ILoadBalancer[] Map of (cluster name => ILoadBalancer)
Since
1.29

Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.

◆ getExternalLB()

Wikimedia\Rdbms\ILBFactory::getExternalLB ( $cluster)

Get the tracked load balancer instance for an external cluster.

If no tracked instances exists, then one will be instantiated

Parameters
string$clusterExternal cluster name
Exceptions
InvalidArgumentExceptionIf $cluster is not recognized
Returns
ILoadBalancer

Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.

◆ getLocalDomainID()

Wikimedia\Rdbms\ILBFactory::getLocalDomainID ( )

Get the local (and default) database domain ID of connection handles.

See also
DatabaseDomain
Returns
string Database domain ID; this specifies DB name, schema, and table prefix
Since
1.32

Implemented in Wikimedia\Rdbms\LBFactory.

Referenced by MWLBFactory\setDomainAliases().

◆ getMainLB()

Wikimedia\Rdbms\ILBFactory::getMainLB ( $domain = false)

Get the tracked load balancer instance for the main cluster that handles the given domain.

If no tracked instances exists, then one will be instantiated

Note
The local/default database domain used by the load balancer instance will still inherit from this ILBFactory instance, regardless of the $domain parameter.
Parameters
string | false$domainDomain ID, or false for the current domain
Returns
ILoadBalancer

Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.

Referenced by MediaWiki\User\UserFactory\__construct(), and MWLBFactory\applyGlobalState().

◆ getTransactionProfiler()

Wikimedia\Rdbms\ILBFactory::getTransactionProfiler ( )

Get the TransactionProfiler used by this instance.

Returns
TransactionProfiler
Since
1.35

Implemented in Wikimedia\Rdbms\LBFactory.

◆ hasOrMadeRecentPrimaryChanges()

Wikimedia\Rdbms\ILBFactory::hasOrMadeRecentPrimaryChanges ( $age = null)

Determine if any primary connection has pending/written changes from this request.

This only applies to the instantiated tracked load balancer instances.

Parameters
float | null$ageHow many seconds ago is "recent" [defaults to LB lag wait timeout]
Returns
bool

Implemented in Wikimedia\Rdbms\LBFactory.

◆ hasPrimaryChanges()

Wikimedia\Rdbms\ILBFactory::hasPrimaryChanges ( )

Determine if any primary connection has pending changes.

This only applies to the instantiated tracked load balancer instances.

Returns
bool
Since
1.37

Implemented in Wikimedia\Rdbms\LBFactory.

◆ hasStreamingReplicaServers()

Wikimedia\Rdbms\ILBFactory::hasStreamingReplicaServers ( )

Whether it has streaming replica servers.

Since
1.41
Returns
bool

Implemented in Wikimedia\Rdbms\LBFactory.

◆ hasTransactionRound()

Wikimedia\Rdbms\ILBFactory::hasTransactionRound ( )

Check if an explicit transaction round is active.

Returns
bool
Since
1.29

Implemented in Wikimedia\Rdbms\LBFactory.

◆ isReadyForRoundOperations()

Wikimedia\Rdbms\ILBFactory::isReadyForRoundOperations ( )

Check if transaction rounds can be started, committed, or rolled back right now.

This can be used as a recursion guard to avoid exceptions in transaction callbacks.

Returns
bool
Since
1.32

Implemented in Wikimedia\Rdbms\LBFactory.

◆ laggedReplicaUsed()

Wikimedia\Rdbms\ILBFactory::laggedReplicaUsed ( )

Determine if any lagged replica database server connection was used.

This only applies to the instantiated tracked load balancer instances.

Returns
bool

Implemented in Wikimedia\Rdbms\LBFactory.

◆ newExternalLB()

Wikimedia\Rdbms\ILBFactory::newExternalLB ( $cluster)

Create a new load balancer instance for an external cluster.

The resulting object will be untracked and the caller is responsible for cleaning it up. Database replication positions will not be saved by ChronologyProtector.

This method is for only advanced usage and callers should almost always use getExternalLB() instead. This method can be useful when a table is used as a key/value store. In that cases, one might want to query it in autocommit mode (DBO_TRX off) but still use DBO_TRX transaction rounds on other tables.

Parameters
string$clusterExternal cluster name
Exceptions
InvalidArgumentExceptionIf $cluster is not recognized
Returns
ILoadBalancerForOwner

Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.

◆ newMainLB()

Wikimedia\Rdbms\ILBFactory::newMainLB ( $domain = false)

Create a new load balancer instance for the main cluster that handles the given domain.

The resulting object will be untracked and the caller is responsible for cleaning it up. Database replication positions will not be saved by ChronologyProtector.

This method is for only advanced usage and callers should almost always use getMainLB() instead. This method can be useful when a table is used as a key/value store. In that cases, one might want to query it in autocommit mode (DBO_TRX off) but still use DBO_TRX transaction rounds on other tables.

Note
The local/default database domain used by the load balancer instance will still inherit from this ILBFactory instance, regardless of the $domain parameter.
Parameters
string | false$domainDomain ID, or false for the current domain
Returns
ILoadBalancerForOwner

Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.

◆ redefineLocalDomain()

Wikimedia\Rdbms\ILBFactory::redefineLocalDomain ( $domain)

Close all connections and redefine the local database domain.

This only applies to the tracked load balancer instances.

This method is only intended for use with schema creation or integration testing

Parameters
DatabaseDomain | string$domain
Since
1.33

Implemented in Wikimedia\Rdbms\LBFactory.

◆ rollbackPrimaryChanges()

Wikimedia\Rdbms\ILBFactory::rollbackPrimaryChanges ( $fname = __METHOD__)

Rollback changes on all primary connections.

This only applies to the instantiated tracked load balancer instances.

Parameters
string$fnameCaller name
Since
1.37

Implemented in Wikimedia\Rdbms\LBFactory.

◆ setAgentName()

Wikimedia\Rdbms\ILBFactory::setAgentName ( $agent)
Parameters
string$agentAgent name for query profiling

Implemented in Wikimedia\Rdbms\LBFactory.

◆ setDefaultReplicationWaitTimeout()

Wikimedia\Rdbms\ILBFactory::setDefaultReplicationWaitTimeout ( $seconds)

Set the default timeout for replication wait checks.

Parameters
int$secondsTimeout, in seconds
Returns
int The previous default timeout
Since
1.35

Implemented in Wikimedia\Rdbms\LBFactory.

◆ setDomainAliases()

Wikimedia\Rdbms\ILBFactory::setDomainAliases ( array $aliases)

Convert certain database domains to alternative ones.

This can be used for backwards compatibility logic.

Parameters
DatabaseDomain[] | string[]$aliasesMap of (domain alias => domain)
Since
1.35

Implemented in Wikimedia\Rdbms\LBFactory.

Referenced by MWLBFactory\setDomainAliases().

◆ setIndexAliases()

Wikimedia\Rdbms\ILBFactory::setIndexAliases ( 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.

Parameters
string[]$aliasesMap of (index alias => index name)
Since
1.31

Implemented in Wikimedia\Rdbms\LBFactory.

◆ setLocalDomainPrefix()

Wikimedia\Rdbms\ILBFactory::setLocalDomainPrefix ( $prefix)

Set a new table prefix for the existing local domain ID for testing.

Parameters
string$prefix
Since
1.33

Implemented in Wikimedia\Rdbms\LBFactory.

◆ setTableAliases()

Wikimedia\Rdbms\ILBFactory::setTableAliases ( array $aliases)

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.

Parameters
array[]$aliasesMap of (table => (dbname, schema, prefix) map)
Since
1.31

Implemented in Wikimedia\Rdbms\LBFactory.

◆ setWaitForReplicationListener()

Wikimedia\Rdbms\ILBFactory::setWaitForReplicationListener ( $name,
callable $callback = null )

Add a callback to be run in every call to waitForReplication() before waiting.

Callbacks must clear any transactions that they start.

Parameters
string$nameCallback name
callable | null$callbackUse null to unset a callback

Implemented in Wikimedia\Rdbms\LBFactory.

Referenced by MWLBFactory\applyGlobalState().

◆ shutdown()

Wikimedia\Rdbms\ILBFactory::shutdown ( $flags = self::SHUTDOWN_NORMAL,
callable $workCallback = null,
& $cpIndex = null,
& $cpClientId = null )

Prepare all instantiated tracked load balancer instances for shutdown.

Parameters
int$flagsBit field of ILBFactory::SHUTDOWN_* constants
callable | null$workCallbackWork to mask ChronologyProtector writes
int | null&$cpIndexPosition key write counter for ChronologyProtector [returned]
string | null&$cpClientIdClient ID hash for ChronologyProtector [returned]

Implemented in Wikimedia\Rdbms\LBFactory.

◆ waitForReplication()

Wikimedia\Rdbms\ILBFactory::waitForReplication ( array $opts = [])

Waits for the replica database server to catch up to the current primary position.

Use this when updating very large numbers of rows, as in maintenance scripts, to avoid causing too much lag. This is a no-op if there are no replica database servers.

By default this waits on all DB clusters actually used in this request. This makes sense when lag being waiting on is caused by the code that does this check. In that case, setting "ifWritesSince" can avoid the overhead of waiting for clusters that were not changed since the last wait check.

Never call this function after a large DB write that is still in a transaction. It only makes sense to call this after the possible lag inducing changes were committed.

This only applies to the instantiated tracked load balancer instances.

Parameters
array$optsOptional fields that include:
  • timeout: Max wait time. Default: 60 seconds for CLI, 1 second for web.
  • ifWritesSince: Only wait if writes were done since this UNIX timestamp.
Returns
bool True on success, false if a timeout or error occurred while waiting

Implemented in Wikimedia\Rdbms\LBFactory.

Member Data Documentation

◆ SHUTDOWN_NO_CHRONPROT

const Wikimedia\Rdbms\ILBFactory::SHUTDOWN_NO_CHRONPROT = 1

Do not save "session consistency" DB replication positions.

Definition at line 50 of file ILBFactory.php.

◆ SHUTDOWN_NORMAL

const Wikimedia\Rdbms\ILBFactory::SHUTDOWN_NORMAL = 0

Idiom for "no special shutdown flags".

Definition at line 48 of file ILBFactory.php.


The documentation for this interface was generated from the following file: