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Wikimedia\Rdbms\LoadBalancer Class Reference

Database connection, tracking, load balancing, and transaction manager for a cluster. More...

Inheritance diagram for Wikimedia\Rdbms\LoadBalancer:
Collaboration diagram for Wikimedia\Rdbms\LoadBalancer:

Public Member Functions

 __construct (array $params)
 Construct a manager of IDatabase connection objects. More...
 
 __destruct ()
 
 allowLagged ( $mode=null)
 Disables/enables lag checks. More...
 
 approveMasterChanges (array $options)
 Perform all pre-commit checks for things like replication safety. More...
 
 beginMasterChanges ( $fname=__METHOD__)
 Flush any master transaction snapshots and set DBO_TRX (if DBO_DEFAULT is set) More...
 
 closeAll ()
 Close all open connections. More...
 
 closeConnection (IDatabase $conn)
 Close a connection. More...
 
 commitAll ( $fname=__METHOD__)
 Commit transactions on all open connections. More...
 
 commitMasterChanges ( $fname=__METHOD__)
 Issue COMMIT on all open master connections to flush changes and view snapshots. More...
 
 disable ()
 Disable this load balancer. More...
 
 finalizeMasterChanges ()
 Run pre-commit callbacks and defer execution of post-commit callbacks. More...
 
 flushMasterSnapshots ( $fname=__METHOD__)
 Commit all master DB transactions so as to flush any REPEATABLE-READ or SSI snapshots. More...
 
 flushReplicaSnapshots ( $fname=__METHOD__)
 Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshots. More...
 
 forEachOpenConnection ( $callback, array $params=[])
 Call a function with each open connection object. More...
 
 forEachOpenMasterConnection ( $callback, array $params=[])
 Call a function with each open connection object to a master. More...
 
 forEachOpenReplicaConnection ( $callback, array $params=[])
 Call a function with each open replica DB connection object. More...
 
 getAnyOpenConnection ( $i, $flags=0)
 Get any open connection to a given server index, local or foreign. More...
 
 getConnection ( $i, $groups=[], $domain=false, $flags=0)
 Get a connection handle by server index. More...
 
 getConnectionRef ( $i, $groups=[], $domain=false, $flags=0)
 Get a database connection handle reference. More...
 
 getLaggedReplicaMode ( $domain=false)
 
 getLagTimes ( $domain=false)
 Get an estimate of replication lag (in seconds) for each server. More...
 
 getLazyConnectionRef ( $i, $groups=[], $domain=false, $flags=0)
 Get a database connection handle reference without connecting yet. More...
 
 getLocalDomainID ()
 Get the local (and default) database domain ID of connection handles. More...
 
 getMaintenanceConnectionRef ( $i, $groups=[], $domain=false, $flags=0)
 Get a maintenance database connection handle reference for migrations and schema changes. More...
 
 getMasterPos ()
 Get the current master position for chronology control purposes. More...
 
 getMaxLag ( $domain=false)
 Get the hostname and lag time of the most-lagged replica DB. More...
 
 getReaderIndex ( $group=false, $domain=false)
 Get the index of the reader connection, which may be a replica DB. More...
 
 getReadOnlyReason ( $domain=false, IDatabase $conn=null)
 
 getServerAttributes ( $i)
 
 getServerCount ()
 Get the number of defined servers (not the number of open connections) More...
 
 getServerInfo ( $i)
 Return the server info structure for a given index, or false if the index is invalid. More...
 
 getServerName ( $i)
 Get the host name or IP address of the server with the specified index. More...
 
 getServerType ( $i)
 Get DB type of the server with the specified index. More...
 
 getTransactionRoundStage ()
 
 getWriterIndex ()
 
 hasMasterChanges ()
 Whether there are pending changes or callbacks in a transaction by this thread. More...
 
 hasMasterConnection ()
 
 hasOrMadeRecentMasterChanges ( $age=null)
 Check if this load balancer object had any recent or still pending writes issued against it by this PHP thread. More...
 
 haveIndex ( $i)
 Returns true if the specified index is a valid server index. More...
 
 isNonZeroLoad ( $i)
 Returns true if the specified index is valid and has non-zero load. More...
 
 laggedReplicaUsed ()
 Checks whether the database for generic connections this request was both: More...
 
 laggedSlaveUsed ()
 
 lastMasterChangeTimestamp ()
 Get the timestamp of the latest write query done by this thread. More...
 
 openConnection ( $i, $domain=false, $flags=0)
 Open a connection to the server given by the specified index. More...
 
 pendingMasterChangeCallers ()
 Get the list of callers that have pending master changes. More...
 
 pingAll ()
 
 redefineLocalDomain ( $domain)
 Close all connection and redefine the local domain for testing or schema creation. More...
 
 resolveDomainID ( $domain)
 
 reuseConnection (IDatabase $conn)
 Mark a foreign connection as being available for reuse under a different DB domain. More...
 
 rollbackMasterChanges ( $fname=__METHOD__)
 Issue ROLLBACK only on master, only if queries were done on connection. More...
 
 runMasterTransactionIdleCallbacks ()
 Consume and run all pending post-COMMIT/ROLLBACK callbacks and commit dangling transactions. More...
 
 runMasterTransactionListenerCallbacks ()
 Run all recurring post-COMMIT/ROLLBACK listener callbacks. More...
 
 safeGetLag (IDatabase $conn)
 Get the lag in seconds for a given connection, or zero if this load balancer does not have replication enabled. More...
 
 safeWaitForMasterPos (IDatabase $conn, $pos=false, $timeout=null)
 Wait for a replica DB to reach a specified master position. More...
 
 setDomainPrefix ( $prefix)
 
 setIndexAliases (array $aliases)
 Convert certain index names to alternative names before querying the DB. More...
 
 setLocalDomainPrefix ( $prefix)
 Set a new table prefix for the existing local domain ID for testing. More...
 
 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. More...
 
 setTransactionListener ( $name, callable $callback=null)
 Set a callback via IDatabase::setTransactionListener() on all current and future master connections of this load balancer. More...
 
 waitFor ( $pos)
 Set the master wait position. More...
 
 waitForAll ( $pos, $timeout=null)
 Set the master wait position and wait for ALL replica DBs to catch up to it. More...
 
 waitForOne ( $pos, $timeout=null)
 Set the master wait position and wait for a "generic" replica DB to catch up to it. More...
 

Public Attributes

const KEY_FOREIGN_FREE = 'foreignFree'
 
const KEY_FOREIGN_FREE_NOROUND = 'foreignFreeAutoCommit'
 
const KEY_FOREIGN_INUSE = 'foreignInUse'
 
const KEY_FOREIGN_INUSE_NOROUND = 'foreignInUseAutoCommit'
 
const KEY_LOCAL = 'local'
 
const KEY_LOCAL_NOROUND = 'localAutoCommit'
 

Protected Member Functions

 doWait ( $index, $open=false, $timeout=null)
 Wait for a given replica DB to catch up to the master pos stored in $this. More...
 
 reallyOpenConnection (array $server, DatabaseDomain $domain)
 Open a new network connection to a server (uncached) More...
 

Private Member Functions

 applyTransactionRoundFlags (Database $conn)
 Make all DB servers with DBO_DEFAULT/DBO_TRX set join the transaction round. More...
 
 assertTransactionRoundStage ( $stage)
 
 getLoadMonitor ()
 Get a LoadMonitor instance. More...
 
 getRandomNonLagged (array $loads, $domain=false, $maxLag=INF)
 
 getRoleFromIndex ( $i)
 
 isOpen ( $index)
 Test if the specified index represents an open connection. More...
 
 masterRunningReadOnly ( $domain, IDatabase $conn=null)
 
 openForeignConnection ( $i, $domain, $flags=0)
 Open a connection to a foreign DB, or return one if it is already open. More...
 
 openLocalConnection ( $i, $flags=0)
 Open a connection to a local DB, or return one if it is already open. More...
 
 pickReaderIndex (array $loads, $domain=false)
 
 reportConnectionError ()
 
 setLocalDomain (DatabaseDomain $domain)
 
 setWaitForPositionIfHigher ( $pos)
 
 undoTransactionRoundFlags (Database $conn)
 

Private Attributes

string $agent
 Agent name for query profiling. More...
 
bool $allowLagged
 Whether to disregard replica DB lag as a factor in replica DB selection. More...
 
bool $allReplicasDownMode = false
 Whether the generic reader fell back to a lagged replica DB. More...
 
callable null $chronologyCallback
 Callback to run before the first connection attempt. More...
 
bool $cliMode
 Whether this PHP instance is for a CLI script. More...
 
bool $connectionAttempted = false
 Whether any connection has been attempted yet. More...
 
LoggerInterface $connLogger
 
Database [][][] $conns
 Map of (connection category => server index => IDatabase[]) More...
 
int $connsOpened = 0
 Total connections opened. More...
 
string null $defaultGroup = null
 
callable $deprecationLogger
 Deprecation logger. More...
 
bool $disabled = false
 
Database $errorConnection
 DB connection object that caused a problem. More...
 
callable $errorLogger
 Exception logger. More...
 
array [] $groupLoads
 Map of (group => server index => weight) More...
 
string $hostname
 Current server name. More...
 
string [] $indexAliases = []
 Map of (index alias => index) More...
 
bool $laggedReplicaMode = false
 Whether the generic reader fell back to a lagged replica DB. More...
 
string $lastError = 'Unknown error'
 The last DB selection or connection error. More...
 
ILoadMonitor $loadMonitor
 
array $loadMonitorConfig
 The LoadMonitor configuration. More...
 
float [] $loads
 Map of (server index => weight) More...
 
DatabaseDomain $localDomain
 Local Domain ID and default for selectDB() calls. More...
 
string $localDomainIdAlias
 Alternate ID string for the domain instead of DatabaseDomain::getId() More...
 
int $maxLag
 
LoggerInterface $perfLogger
 
mixed $profiler
 Class name or object With profileIn/profileOut methods. More...
 
LoggerInterface $queryLogger
 
int $readIndex
 The generic (not query grouped) replica DB index (of $mServers) More...
 
string bool $readOnlyReason = false
 Reason the LB is read-only or false if not. More...
 
LoggerInterface $replLogger
 
array [] $servers
 Map of (server index => server config array) More...
 
BagOStuff $srvCache
 
 $tableAliases = []
 
TransactionProfiler $trxProfiler
 
array [] $trxRecurringCallbacks = []
 Map of (name => callable) More...
 
string bool $trxRoundId = false
 String if a requested DBO_TRX transaction round is active. More...
 
string $trxRoundStage = self::ROUND_CURSORY
 Stage of the current transaction round in the transaction round life-cycle. More...
 
bool DBMasterPos $waitForPos
 False if not set. More...
 
int $waitTimeout
 Seconds to spend waiting on replica DB lag to resolve. More...
 
WANObjectCache $wanCache
 

Detailed Description

Database connection, tracking, load balancing, and transaction manager for a cluster.

Definition at line 41 of file LoadBalancer.php.

Constructor & Destructor Documentation

◆ __construct()

Wikimedia\Rdbms\LoadBalancer::__construct ( array  $params)

Construct a manager of IDatabase connection objects.

Parameters
array$paramsParameter map with keys:
  • servers : Required. Array of server info structures.
  • localDomain: A DatabaseDomain or domain ID string.
  • loadMonitor : Name of a class used to fetch server lag and load.
  • readOnlyReason : Reason the master DB is read-only if so [optional]
  • waitTimeout : Maximum time to wait for replicas for consistency [optional]
  • maxLag: Try to avoid DB replicas with lag above this many seconds [optional]
  • srvCache : BagOStuff object for server cache [optional]
  • wanCache : WANObjectCache object [optional]
  • chronologyCallback: Callback to run before the first connection attempt [optional]
  • hostname : The name of the current server [optional]
  • cliMode: Whether the execution context is a CLI script. [optional]
  • profiler : Class name or instance with profileIn()/profileOut() methods. [optional]
  • trxProfiler: TransactionProfiler instance. [optional]
  • replLogger: PSR-3 logger instance. [optional]
  • connLogger: PSR-3 logger instance. [optional]
  • queryLogger: PSR-3 logger instance. [optional]
  • perfLogger: PSR-3 logger instance. [optional]
  • errorLogger : Callback that takes an Exception and logs it. [optional]
  • deprecationLogger: Callback to log a deprecation warning. [optional]
  • roundStage: STAGE_POSTCOMMIT_* class constant; for internal use [optional]
Exceptions
InvalidArgumentException

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 164 of file LoadBalancer.php.

References $e, Wikimedia\Rdbms\LoadBalancer\$maxLag, Wikimedia\Rdbms\LoadBalancer\allowLagged(), as, WANObjectCache\newEmpty(), Wikimedia\Rdbms\DatabaseDomain\newFromId(), Wikimedia\Rdbms\DatabaseDomain\newUnspecified(), null, servers, and Wikimedia\Rdbms\LoadBalancer\setLocalDomain().

◆ __destruct()

Wikimedia\Rdbms\LoadBalancer::__destruct ( )

Definition at line 2000 of file LoadBalancer.php.

References class, and Wikimedia\Rdbms\LoadBalancer\disable().

Member Function Documentation

◆ allowLagged()

Wikimedia\Rdbms\LoadBalancer::allowLagged (   $mode = null)

Disables/enables lag checks.

Parameters
null | bool$mode
Returns
bool

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1763 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$allowLagged, and null.

Referenced by Wikimedia\Rdbms\LoadBalancer\__construct(), and Wikimedia\Rdbms\LoadBalancer\pickReaderIndex().

◆ applyTransactionRoundFlags()

Wikimedia\Rdbms\LoadBalancer::applyTransactionRoundFlags ( Database  $conn)
private

Make all DB servers with DBO_DEFAULT/DBO_TRX set join the transaction round.

Some servers may have neither flag enabled, meaning that they opt out of such transaction rounds and remain in auto-commit mode. Such behavior might be desired when a DB server is used for something like simple key/value storage.

Parameters
Database$conn

Definition at line 1594 of file LoadBalancer.php.

References DBO_DEFAULT, DBO_TRX, Wikimedia\Rdbms\Database\getFlag(), Wikimedia\Rdbms\Database\getLBInfo(), Wikimedia\Rdbms\Database\setFlag(), and Wikimedia\Rdbms\Database\setLBInfo().

Referenced by Wikimedia\Rdbms\LoadBalancer\beginMasterChanges(), and Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection().

◆ approveMasterChanges()

Wikimedia\Rdbms\LoadBalancer::approveMasterChanges ( array  $options)

Perform all pre-commit checks for things like replication safety.

Use this only for mutli-database commits

Parameters
array$optionsIncludes:
  • maxWriteDuration : max write query duration time in seconds
Exceptions
DBTransactionError

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1358 of file LoadBalancer.php.

References $time, Wikimedia\Rdbms\IDatabase\assertNoOpenTransactions(), Wikimedia\Rdbms\LoadBalancer\assertTransactionRoundStage(), Wikimedia\Rdbms\LoadBalancer\forEachOpenMasterConnection(), Wikimedia\Rdbms\IDatabase\pendingWriteQueryDuration(), Wikimedia\Rdbms\IDatabase\ping(), use, and Wikimedia\Rdbms\IDatabase\writesOrCallbacksPending().

◆ assertTransactionRoundStage()

Wikimedia\Rdbms\LoadBalancer::assertTransactionRoundStage (   $stage)
private

◆ beginMasterChanges()

Wikimedia\Rdbms\LoadBalancer::beginMasterChanges (   $fname = __METHOD__)

Flush any master 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:

Parameters
string$fname
Exceptions
DBExpectedError

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1391 of file LoadBalancer.php.

References $fname, Wikimedia\Rdbms\LoadBalancer\applyTransactionRoundFlags(), Wikimedia\Rdbms\LoadBalancer\assertTransactionRoundStage(), Wikimedia\Rdbms\LoadBalancer\flushMasterSnapshots(), Wikimedia\Rdbms\LoadBalancer\forEachOpenMasterConnection(), and null.

◆ closeAll()

◆ closeConnection()

Wikimedia\Rdbms\LoadBalancer::closeConnection ( IDatabase  $conn)

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.

Parameters
IDatabase$conn

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1301 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$connsOpened, $type, as, Wikimedia\Rdbms\IDatabase\close(), Wikimedia\Rdbms\IDatabase\getLBInfo(), and Wikimedia\Rdbms\LoadBalancer\getServerName().

Referenced by Wikimedia\Rdbms\LoadBalancer\doWait(), and Wikimedia\Rdbms\LoadBalancer\safeWaitForMasterPos().

◆ commitAll()

Wikimedia\Rdbms\LoadBalancer::commitAll (   $fname = __METHOD__)

Commit transactions on all open connections.

Parameters
string$fnameCaller name
Exceptions
DBExpectedError

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1328 of file LoadBalancer.php.

References $fname, Wikimedia\Rdbms\LoadBalancer\commitMasterChanges(), Wikimedia\Rdbms\LoadBalancer\flushMasterSnapshots(), and Wikimedia\Rdbms\LoadBalancer\flushReplicaSnapshots().

◆ commitMasterChanges()

Wikimedia\Rdbms\LoadBalancer::commitMasterChanges (   $fname = __METHOD__)

◆ disable()

Wikimedia\Rdbms\LoadBalancer::disable ( )

Disable this load balancer.

All connections are closed, and any attempt to open a new connection will result in a DBAccessError.

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1276 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\closeAll().

Referenced by Wikimedia\Rdbms\LoadBalancer\__destruct().

◆ doWait()

Wikimedia\Rdbms\LoadBalancer::doWait (   $index,
  $open = false,
  $timeout = null 
)
protected

Wait for a given replica DB to catch up to the master pos stored in $this.

Parameters
int$indexServer index
bool$openCheck the server even if a new connection has to be made
int | null$timeoutMax seconds to wait; default is "waitTimeout" given to __construct()
Returns
bool

Definition at line 599 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\closeConnection(), Wikimedia\Rdbms\LoadBalancer\getAnyOpenConnection(), Wikimedia\Rdbms\LoadBalancer\getServerName(), Wikimedia\Rdbms\DBMasterPos\hasReached(), null, Wikimedia\Rdbms\LoadBalancer\openConnection(), and IExpiringStore\TTL_DAY.

Referenced by Wikimedia\Rdbms\LoadBalancer\getReaderIndex(), Wikimedia\Rdbms\LoadBalancer\waitFor(), Wikimedia\Rdbms\LoadBalancer\waitForAll(), and Wikimedia\Rdbms\LoadBalancer\waitForOne().

◆ finalizeMasterChanges()

Wikimedia\Rdbms\LoadBalancer::finalizeMasterChanges ( )

Run pre-commit callbacks and defer execution of post-commit callbacks.

Use this only for mutli-database commits

Returns
int Number of pre-commit callbacks run (since 1.32)

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1334 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\assertTransactionRoundStage(), Wikimedia\Rdbms\LoadBalancer\forEachOpenMasterConnection(), Wikimedia\Rdbms\Database\runOnTransactionPreCommitCallbacks(), Wikimedia\Rdbms\Database\setTrxEndCallbackSuppression(), and use.

◆ flushMasterSnapshots()

Wikimedia\Rdbms\LoadBalancer::flushMasterSnapshots (   $fname = __METHOD__)

Commit all master 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

Parameters
string$fnameCaller name

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1633 of file LoadBalancer.php.

References $fname, Wikimedia\Rdbms\IDatabase\flushSnapshot(), Wikimedia\Rdbms\LoadBalancer\forEachOpenMasterConnection(), and use.

Referenced by Wikimedia\Rdbms\LoadBalancer\beginMasterChanges(), and Wikimedia\Rdbms\LoadBalancer\commitAll().

◆ flushReplicaSnapshots()

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

Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshots.

Parameters
string$fnameCaller name

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1627 of file LoadBalancer.php.

References $fname, Wikimedia\Rdbms\IDatabase\flushSnapshot(), Wikimedia\Rdbms\LoadBalancer\forEachOpenReplicaConnection(), and use.

Referenced by Wikimedia\Rdbms\LoadBalancer\commitAll().

◆ forEachOpenConnection()

Wikimedia\Rdbms\LoadBalancer::forEachOpenConnection (   $callback,
array  $params = [] 
)

Call a function with each open connection object.

Parameters
callable$callback
array$params

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1783 of file LoadBalancer.php.

References $params, and as.

Referenced by Wikimedia\Rdbms\LoadBalancer\closeAll(), Wikimedia\Rdbms\LoadBalancer\pingAll(), and Wikimedia\Rdbms\LoadBalancer\setLocalDomainPrefix().

◆ forEachOpenMasterConnection()

◆ forEachOpenReplicaConnection()

Wikimedia\Rdbms\LoadBalancer::forEachOpenReplicaConnection (   $callback,
array  $params = [] 
)

Call a function with each open replica DB connection object.

Parameters
callable$callback
array$params

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1805 of file LoadBalancer.php.

References $params, as, and Wikimedia\Rdbms\LoadBalancer\getWriterIndex().

Referenced by Wikimedia\Rdbms\LoadBalancer\flushReplicaSnapshots().

◆ getAnyOpenConnection()

Wikimedia\Rdbms\LoadBalancer::getAnyOpenConnection (   $i,
  $flags = 0 
)

Get any open connection to a given server index, local or foreign.

Use CONN_TRX_AUTOCOMMIT to only look for connections opened with that flag. Avoid the use of begin() or startAtomic() on any such connections.

Parameters
int$iServer index or DB_MASTER/DB_REPLICA
int$flagsBitfield of CONN_* class constants
Returns
Database|bool False if no such connection is open

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 566 of file LoadBalancer.php.

References as, DB_MASTER, DB_REPLICA, and Wikimedia\Rdbms\LoadBalancer\getWriterIndex().

Referenced by Wikimedia\Rdbms\LoadBalancer\doWait(), Wikimedia\Rdbms\LoadBalancer\getMasterPos(), Wikimedia\Rdbms\LoadBalancer\isOpen(), and Wikimedia\Rdbms\LoadBalancer\safeWaitForMasterPos().

◆ getConnection()

Wikimedia\Rdbms\LoadBalancer::getConnection (   $i,
  $groups = [],
  $domain = false,
  $flags = 0 
)

Get a connection handle by server index.

The CONN_TRX_AUTOCOMMIT flag is ignored for databases with ATTR_DB_LEVEL_LOCKING (e.g. sqlite) in order to avoid deadlocks. ILoadBalancer::getServerAttributes() can be used to check such flags beforehand.

If the caller uses $domain or sets CONN_TRX_AUTOCOMMIT in $flags, then it must also call ILoadBalancer::reuseConnection() on the handle when finished using it. In all other cases, this is not necessary, though not harmful either. Avoid the use of begin() or startAtomic() on any such connections.

Parameters
int$iServer index (overrides $groups) or DB_MASTER/DB_REPLICA
array | string | bool$groupsQuery group(s), or false for the generic reader
string | bool$domainDomain ID, or false for the current domain
int$flagsBitfield of CONN_* class constants
Note
This method throws DBAccessError if ILoadBalancer::disable() was called
Exceptions
DBError
Returns
Database

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 688 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$connsOpened, Wikimedia\Rdbms\LoadBalancer\$defaultGroup, Wikimedia\Rdbms\LoadBalancer\$lastError, Wikimedia\Rdbms\LoadBalancer\$localDomainIdAlias, array(), as, DB_MASTER, DB_REPLICA, false, Wikimedia\Rdbms\LoadBalancer\getReaderIndex(), Wikimedia\Rdbms\LoadBalancer\getReadOnlyReason(), Wikimedia\Rdbms\LoadBalancer\getServerAttributes(), Wikimedia\Rdbms\LoadBalancer\getWriterIndex(), null, Wikimedia\Rdbms\LoadBalancer\openConnection(), and Wikimedia\Rdbms\LoadBalancer\reportConnectionError().

Referenced by Wikimedia\Rdbms\LoadBalancer\getConnectionRef(), Wikimedia\Rdbms\LoadBalancer\getLaggedReplicaMode(), Wikimedia\Rdbms\LoadBalancer\getMaintenanceConnectionRef(), and Wikimedia\Rdbms\LoadBalancer\masterRunningReadOnly().

◆ getConnectionRef()

Wikimedia\Rdbms\LoadBalancer::getConnectionRef (   $i,
  $groups = [],
  $domain = false,
  $flags = 0 
)

Get a database connection handle reference.

The handle's methods simply wrap those of a Database handle

The CONN_TRX_AUTOCOMMIT flag is ignored for databases with ATTR_DB_LEVEL_LOCKING (e.g. sqlite) in order to avoid deadlocks. ILoadBalancer::getServerAttributes() can be used to check such flags beforehand. Avoid the use of begin() or startAtomic() on any CONN_TRX_AUTOCOMMIT connections.

See also
ILoadBalancer::getConnection() for parameter information
Parameters
int$iServer index or DB_MASTER/DB_REPLICA
array | string | bool$groupsQuery group(s), or false for the generic reader
string | bool$domainDomain ID, or false for the current domain
int$flagsBitfield of CONN_* class constants (e.g. CONN_TRX_AUTOCOMMIT)
Returns
DBConnRef

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 837 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\getConnection(), Wikimedia\Rdbms\LoadBalancer\getRoleFromIndex(), and Wikimedia\Rdbms\LoadBalancer\resolveDomainID().

Referenced by ImportableOldRevisionImporter\import().

◆ getLaggedReplicaMode()

Wikimedia\Rdbms\LoadBalancer::getLaggedReplicaMode (   $domain = false)
Note
This method will trigger a DB connection if not yet done
Parameters
string | bool$domainDomain ID, or false for the current domain
Returns
bool Whether the database for generic connections this request is highly "lagged"

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1685 of file LoadBalancer.php.

References $e, Wikimedia\Rdbms\LoadBalancer\$laggedReplicaMode, DB_REPLICA, Wikimedia\Rdbms\LoadBalancer\getConnection(), Wikimedia\Rdbms\LoadBalancer\getServerCount(), and Wikimedia\Rdbms\LoadBalancer\reuseConnection().

Referenced by Wikimedia\Rdbms\LoadBalancer\getReadOnlyReason().

◆ getLagTimes()

Wikimedia\Rdbms\LoadBalancer::getLagTimes (   $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

Parameters
string | bool$domain
Returns
int[] Map of (server index => float|int|bool)

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1839 of file LoadBalancer.php.

References as, Wikimedia\Rdbms\LoadBalancer\getLoadMonitor(), Wikimedia\Rdbms\LoadBalancer\getServerCount(), Wikimedia\Rdbms\LoadBalancer\getWriterIndex(), and servers.

Referenced by Wikimedia\Rdbms\LoadBalancer\getMaxLag(), and Wikimedia\Rdbms\LoadBalancer\getRandomNonLagged().

◆ getLazyConnectionRef()

Wikimedia\Rdbms\LoadBalancer::getLazyConnectionRef (   $i,
  $groups = [],
  $domain = false,
  $flags = 0 
)

Get a database connection handle reference without connecting yet.

The handle's methods simply wrap those of a Database handle

The CONN_TRX_AUTOCOMMIT flag is ignored for databases with ATTR_DB_LEVEL_LOCKING (e.g. sqlite) in order to avoid deadlocks. ILoadBalancer::getServerAttributes() can be used to check such flags beforehand. Avoid the use of begin() or startAtomic() on any CONN_TRX_AUTOCOMMIT connections.

See also
ILoadBalancer::getConnection() for parameter information
Parameters
int$iServer index or DB_MASTER/DB_REPLICA
array | string | bool$groupsQuery group(s), or false for the generic reader
string | bool$domainDomain ID, or false for the current domain
int$flagsBitfield of CONN_* class constants (e.g. CONN_TRX_AUTOCOMMIT)
Returns
DBConnRef

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 844 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\getRoleFromIndex(), and Wikimedia\Rdbms\LoadBalancer\resolveDomainID().

Referenced by Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection().

◆ getLoadMonitor()

Wikimedia\Rdbms\LoadBalancer::getLoadMonitor ( )
private

◆ getLocalDomainID()

Wikimedia\Rdbms\LoadBalancer::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
1.31

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 255 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\resolveDomainID().

◆ getMaintenanceConnectionRef()

Wikimedia\Rdbms\LoadBalancer::getMaintenanceConnectionRef (   $i,
  $groups = [],
  $domain = false,
  $flags = 0 
)

Get a maintenance database connection handle reference for migrations and schema changes.

The handle's methods simply wrap those of a Database handle

The CONN_TRX_AUTOCOMMIT flag is ignored for databases with ATTR_DB_LEVEL_LOCKING (e.g. sqlite) in order to avoid deadlocks. ILoadBalancer::getServerAttributes() can be used to check such flags beforehand. Avoid the use of begin() or startAtomic() on any CONN_TRX_AUTOCOMMIT connections.

See also
ILoadBalancer::getConnection() for parameter information
Parameters
int$iServer index or DB_MASTER/DB_REPLICA
array | string | bool$groupsQuery group(s), or false for the generic reader
string | bool$domainDomain ID, or false for the current domain
int$flagsBitfield of CONN_* class constants (e.g. CONN_TRX_AUTOCOMMIT)
Returns
MaintainableDBConnRef

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 851 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\getConnection(), Wikimedia\Rdbms\LoadBalancer\getRoleFromIndex(), and Wikimedia\Rdbms\LoadBalancer\resolveDomainID().

◆ getMasterPos()

Wikimedia\Rdbms\LoadBalancer::getMasterPos ( )

Get the current master position for chronology control purposes.

Returns
DBMasterPos|bool Returns false if not applicable

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1257 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\getAnyOpenConnection(), Wikimedia\Rdbms\LoadBalancer\getWriterIndex(), and servers.

◆ getMaxLag()

Wikimedia\Rdbms\LoadBalancer::getMaxLag (   $domain = false)

Get the hostname and lag time of the most-lagged replica DB.

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.

Parameters
bool | string$domainDomain ID, or false for the default database
Returns
array ( host, max lag, index of max lagged host )

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1818 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$maxLag, as, Wikimedia\Rdbms\LoadBalancer\getLagTimes(), Wikimedia\Rdbms\LoadBalancer\getServerCount(), and servers.

◆ getRandomNonLagged()

Wikimedia\Rdbms\LoadBalancer::getRandomNonLagged ( array  $loads,
  $domain = false,
  $maxLag = INF 
)
private
Parameters
array$loads
bool | string$domainDomain to get non-lagged for
int$maxLagRestrict the maximum allowed lag to this many seconds
Returns
bool|int|string

Definition at line 295 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$maxLag, as, Wikimedia\Rdbms\LoadBalancer\getLagTimes(), Wikimedia\Rdbms\LoadBalancer\getServerName(), ArrayUtils\pickRandom(), and servers.

Referenced by Wikimedia\Rdbms\LoadBalancer\pickReaderIndex().

◆ getReaderIndex()

Wikimedia\Rdbms\LoadBalancer::getReaderIndex (   $group = false,
  $domain = false 
)

Get the index of the reader connection, which may be a replica DB.

This takes into account load ratios and lag times. It should always return a consistent index during a given invocation.

Side effect: opens connections to databases

Parameters
string | bool$groupQuery group, or false for the generic reader
string | bool$domainDomain ID, or false for the current domain
Exceptions
DBError
Returns
bool|int|string

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 344 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$loads, Wikimedia\Rdbms\LoadBalancer\$readIndex, Wikimedia\Rdbms\LoadBalancer\doWait(), Wikimedia\Rdbms\LoadBalancer\getLoadMonitor(), Wikimedia\Rdbms\LoadBalancer\getServerName(), Wikimedia\Rdbms\LoadBalancer\getWriterIndex(), list, Wikimedia\Rdbms\LoadBalancer\pickReaderIndex(), and servers.

Referenced by Wikimedia\Rdbms\LoadBalancer\getConnection().

◆ getReadOnlyReason()

Wikimedia\Rdbms\LoadBalancer::getReadOnlyReason (   $domain = false,
IDatabase  $conn = null 
)
Note
This method may trigger a DB connection if not yet done
Parameters
string | bool$domainDomain ID, or false for the current domain
IDatabase | null$connDB master connection; used to avoid loops [optional]
Returns
string|bool Reason the master is read-only or false if it is not

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1715 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$readOnlyReason, Wikimedia\Rdbms\LoadBalancer\getLaggedReplicaMode(), and Wikimedia\Rdbms\LoadBalancer\masterRunningReadOnly().

Referenced by Wikimedia\Rdbms\LoadBalancer\getConnection().

◆ getRoleFromIndex()

Wikimedia\Rdbms\LoadBalancer::getRoleFromIndex (   $i)
private
Parameters
int$iServer index or DB_MASTER/DB_REPLICA
Returns
int One of DB_MASTER/DB_REPLICA

Definition at line 863 of file LoadBalancer.php.

References DB_MASTER, DB_REPLICA, and Wikimedia\Rdbms\LoadBalancer\getWriterIndex().

Referenced by Wikimedia\Rdbms\LoadBalancer\getConnectionRef(), Wikimedia\Rdbms\LoadBalancer\getLazyConnectionRef(), and Wikimedia\Rdbms\LoadBalancer\getMaintenanceConnectionRef().

◆ getServerAttributes()

Wikimedia\Rdbms\LoadBalancer::getServerAttributes (   $i)
Parameters
int$iServer index
Returns
array (Database::ATTRIBUTE_* constant => value) for all such constants
Since
1.31

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1084 of file LoadBalancer.php.

References Wikimedia\Rdbms\Database\attributesFromType(), Wikimedia\Rdbms\LoadBalancer\getServerType(), null, and servers.

Referenced by Wikimedia\Rdbms\LoadBalancer\getConnection().

◆ getServerCount()

Wikimedia\Rdbms\LoadBalancer::getServerCount ( )

◆ getServerInfo()

Wikimedia\Rdbms\LoadBalancer::getServerInfo (   $i)

Return the server info structure for a given index, or false if the index is invalid.

Parameters
int$i
Returns
array|bool
Since
1.31

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1249 of file LoadBalancer.php.

References servers.

◆ getServerName()

Wikimedia\Rdbms\LoadBalancer::getServerName (   $i)

◆ getServerType()

Wikimedia\Rdbms\LoadBalancer::getServerType (   $i)

Get DB type of the server with the specified index.

Parameters
int$i
Returns
string One of (mysql,postgres,sqlite,...) or "unknown" for bad indexes
Since
1.30

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1253 of file LoadBalancer.php.

References servers.

Referenced by Wikimedia\Rdbms\LoadBalancer\getServerAttributes().

◆ getTransactionRoundStage()

Wikimedia\Rdbms\LoadBalancer::getTransactionRoundStage ( )
Returns
string
Since
1.32

Definition at line 1643 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$trxRoundStage.

◆ getWriterIndex()

◆ hasMasterChanges()

Wikimedia\Rdbms\LoadBalancer::hasMasterChanges ( )

Whether there are pending changes or callbacks in a transaction by this thread.

Returns
bool

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1651 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\forEachOpenMasterConnection(), use, and Wikimedia\Rdbms\IDatabase\writesOrCallbacksPending().

Referenced by Wikimedia\Rdbms\LoadBalancer\hasOrMadeRecentMasterChanges().

◆ hasMasterConnection()

Wikimedia\Rdbms\LoadBalancer::hasMasterConnection ( )
Returns
bool Whether a master connection is already open

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1647 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\getWriterIndex(), and Wikimedia\Rdbms\LoadBalancer\isOpen().

◆ hasOrMadeRecentMasterChanges()

Wikimedia\Rdbms\LoadBalancer::hasOrMadeRecentMasterChanges (   $age = null)

Check if this load balancer object had any recent or still pending writes issued against it by this PHP thread.

Parameters
float | null$ageHow many seconds ago is "recent" [defaults to mWaitTimeout]
Returns
bool

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1669 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\hasMasterChanges(), Wikimedia\Rdbms\LoadBalancer\lastMasterChangeTimestamp(), and null.

◆ haveIndex()

Wikimedia\Rdbms\LoadBalancer::haveIndex (   $i)

Returns true if the specified index is a valid server index.

Parameters
int$i
Returns
bool

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1231 of file LoadBalancer.php.

References servers.

◆ isNonZeroLoad()

Wikimedia\Rdbms\LoadBalancer::isNonZeroLoad (   $i)

Returns true if the specified index is valid and has non-zero load.

Parameters
int$i
Returns
bool

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1235 of file LoadBalancer.php.

References servers.

◆ isOpen()

Wikimedia\Rdbms\LoadBalancer::isOpen (   $index)
private

Test if the specified index represents an open connection.

Parameters
int$indexServer index
Returns
bool

Definition at line 1098 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\getAnyOpenConnection().

Referenced by Wikimedia\Rdbms\LoadBalancer\hasMasterConnection().

◆ laggedReplicaUsed()

Wikimedia\Rdbms\LoadBalancer::laggedReplicaUsed ( )

Checks whether the database for generic connections this request was both:

  • a) Already choosen due to a prior connection attempt
  • b) Considered highly "lagged"
Note
This method will never cause a new DB connection
Returns
bool

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1702 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$laggedReplicaMode.

Referenced by Wikimedia\Rdbms\LoadBalancer\laggedSlaveUsed().

◆ laggedSlaveUsed()

Wikimedia\Rdbms\LoadBalancer::laggedSlaveUsed ( )
Returns
bool
Since
1.27
Deprecated:
Since 1.28; use laggedReplicaUsed()

Definition at line 1711 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\laggedReplicaUsed().

◆ lastMasterChangeTimestamp()

Wikimedia\Rdbms\LoadBalancer::lastMasterChangeTimestamp ( )

Get the timestamp of the latest write query done by this thread.

Returns
float|bool UNIX timestamp or false

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1660 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\forEachOpenMasterConnection(), Wikimedia\Rdbms\IDatabase\lastDoneWrites(), and use.

Referenced by Wikimedia\Rdbms\LoadBalancer\hasOrMadeRecentMasterChanges().

◆ masterRunningReadOnly()

Wikimedia\Rdbms\LoadBalancer::masterRunningReadOnly (   $domain,
IDatabase  $conn = null 
)
private
Parameters
string$domainDomain ID, or false for the current domain
IDatabase | null$connDB master connectionl used to avoid loops [optional]
Returns
bool

Definition at line 1738 of file LoadBalancer.php.

References $cache, $e, Wikimedia\Rdbms\LoadBalancer\$wanCache, DB_MASTER, Wikimedia\Rdbms\LoadBalancer\getConnection(), Wikimedia\Rdbms\LoadBalancer\getServerName(), Wikimedia\Rdbms\LoadBalancer\getWriterIndex(), Wikimedia\Rdbms\LoadBalancer\reuseConnection(), and use.

Referenced by Wikimedia\Rdbms\LoadBalancer\getReadOnlyReason().

◆ openConnection()

Wikimedia\Rdbms\LoadBalancer::openConnection (   $i,
  $domain = false,
  $flags = 0 
)

Open a connection to the server given by the specified index.

The index must be an actual index into the array. If a connection to the server is already open and not considered an "in use" foreign connection, this simply returns it.

Avoid using CONN_TRX_AUTOCOMMIT for databases with ATTR_DB_LEVEL_LOCKING (e.g. sqlite) in order to avoid deadlocks. ILoadBalancer::getServerAttributes() can be used to check such flags beforehand.

If the caller uses $domain or sets CONN_TRX_AUTOCOMMIT in $flags, then it must also call ILoadBalancer::reuseConnection() on the handle when finished using it. In all other cases, this is not necessary, though not harmful either. Avoid the use of begin() or startAtomic() on any such connections.

Note
This method throws DBAccessError if ILoadBalancer::disable() was called
Parameters
int$iServer index (does not support DB_MASTER/DB_REPLICA)
string | bool$domainDomain ID, or false for the current domain
int$flagsBitfield of CONN_* class constants (e.g. CONN_TRX_AUTOCOMMIT)
Returns
Database|bool Returns false on errors
Exceptions
DBAccessError

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 869 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$chronologyCallback, Wikimedia\Rdbms\LoadBalancer\$localDomainIdAlias, DBO_TRX, Wikimedia\Rdbms\IDatabase\isOpen(), Wikimedia\Rdbms\LoadBalancer\openForeignConnection(), and Wikimedia\Rdbms\LoadBalancer\openLocalConnection().

Referenced by Wikimedia\Rdbms\LoadBalancer\doWait(), Wikimedia\Rdbms\LoadBalancer\getConnection(), Wikimedia\Rdbms\LoadBalancer\pickReaderIndex(), and Wikimedia\Rdbms\LoadBalancer\safeWaitForMasterPos().

◆ openForeignConnection()

Wikimedia\Rdbms\LoadBalancer::openForeignConnection (   $i,
  $domain,
  $flags = 0 
)
private

Open a connection to a foreign DB, or return one if it is already open.

Increments a reference count on the returned connection which locks the connection to the requested domain. This reference count can be decremented by calling reuseConnection().

If a connection is open to the appropriate server already, but with the wrong database, it will be switched to the right database and returned, as long as it has been freed first with reuseConnection().

On error, returns false, and the connection which caused the error will be available via $this->errorConnection.

Note
If disable() was called on this LoadBalancer, this method will throw a DBAccessError.
Parameters
int$iServer index
string$domainDomain ID to open
int$flagsClass CONN_* constant bitfield
Returns
Database|bool Returns false on connection error
Exceptions
DBErrorWhen database selection fails

Definition at line 993 of file LoadBalancer.php.

References as, Wikimedia\Rdbms\DatabaseDomain\newFromId(), null, Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection(), and servers.

Referenced by Wikimedia\Rdbms\LoadBalancer\openConnection().

◆ openLocalConnection()

Wikimedia\Rdbms\LoadBalancer::openLocalConnection (   $i,
  $flags = 0 
)
private

Open a connection to a local DB, or return one if it is already open.

On error, returns false, and the connection which caused the error will be available via $this->errorConnection.

Note
If disable() was called on this LoadBalancer, this method will throw a DBAccessError.
Parameters
int$iServer index
int$flagsClass CONN_* constant bitfield
Returns
Database

Definition at line 930 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\getServerName(), Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection(), and servers.

Referenced by Wikimedia\Rdbms\LoadBalancer\openConnection().

◆ pendingMasterChangeCallers()

Wikimedia\Rdbms\LoadBalancer::pendingMasterChangeCallers ( )

Get the list of callers that have pending master changes.

Returns
string[] List of method names

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1676 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\forEachOpenMasterConnection(), Wikimedia\Rdbms\IDatabase\pendingWriteCallers(), and use.

◆ pickReaderIndex()

Wikimedia\Rdbms\LoadBalancer::pickReaderIndex ( array  $loads,
  $domain = false 
)
private

◆ pingAll()

Wikimedia\Rdbms\LoadBalancer::pingAll ( )

◆ reallyOpenConnection()

◆ redefineLocalDomain()

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

Close all connection and redefine the local domain for testing or schema creation.

Parameters
DatabaseDomain | string$domain
Since
1.33

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1979 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\closeAll(), Wikimedia\Rdbms\DatabaseDomain\newFromId(), and Wikimedia\Rdbms\LoadBalancer\setLocalDomain().

◆ reportConnectionError()

Wikimedia\Rdbms\LoadBalancer::reportConnectionError ( )
private

◆ resolveDomainID()

Wikimedia\Rdbms\LoadBalancer::resolveDomainID (   $domain)
Parameters
DatabaseDomain | string | bool$domainDatabase domain
Returns
string Value of $domain if provided or the local domain otherwise
Since
1.32

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 259 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\getLocalDomainID(), and string.

Referenced by Wikimedia\Rdbms\LoadBalancer\getConnectionRef(), Wikimedia\Rdbms\LoadBalancer\getLazyConnectionRef(), Wikimedia\Rdbms\LoadBalancer\getMaintenanceConnectionRef(), and LoadBalancerTest\testWithoutReplica().

◆ reuseConnection()

Wikimedia\Rdbms\LoadBalancer::reuseConnection ( IDatabase  $conn)

Mark a foreign connection as being available for reuse under a different DB domain.

This mechanism is reference-counted, and must be called the same number of times as getConnection() to work.

Parameters
IDatabase$conn
Exceptions
InvalidArgumentException

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 777 of file LoadBalancer.php.

References Wikimedia\Rdbms\IDatabase\getDomainID(), Wikimedia\Rdbms\IDatabase\getLBInfo(), null, and Wikimedia\Rdbms\IDatabase\setLBInfo().

Referenced by Wikimedia\Rdbms\LoadBalancer\getLaggedReplicaMode(), Wikimedia\Rdbms\LoadBalancer\masterRunningReadOnly(), and Wikimedia\Rdbms\LoadBalancer\pickReaderIndex().

◆ rollbackMasterChanges()

Wikimedia\Rdbms\LoadBalancer::rollbackMasterChanges (   $fname = __METHOD__)

Issue ROLLBACK only on master, only if queries were done on connection.

Parameters
string$fnameCaller name
Exceptions
DBExpectedError

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1549 of file LoadBalancer.php.

References $fname, false, Wikimedia\Rdbms\LoadBalancer\forEachOpenMasterConnection(), Wikimedia\Rdbms\IDatabase\rollback(), Wikimedia\Rdbms\LoadBalancer\undoTransactionRoundFlags(), and use.

◆ runMasterTransactionIdleCallbacks()

◆ runMasterTransactionListenerCallbacks()

Wikimedia\Rdbms\LoadBalancer::runMasterTransactionListenerCallbacks ( )

Run all recurring post-COMMIT/ROLLBACK listener callbacks.

Returns
Exception|null The first exception or null if there were none

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1522 of file LoadBalancer.php.

References $e, $type, Wikimedia\Rdbms\LoadBalancer\forEachOpenMasterConnection(), null, Wikimedia\Rdbms\Database\runTransactionListenerCallbacks(), and use.

◆ safeGetLag()

Wikimedia\Rdbms\LoadBalancer::safeGetLag ( IDatabase  $conn)

Get the lag in seconds for a given connection, or zero if this load balancer does not have replication enabled.

This should be used in preference to Database::getLag() in cases where replication may not be in use, since there is no way to determine if replication is in use at the connection level without running potentially restricted queries such as SHOW SLAVE STATUS. Using this function instead of Database::getLag() avoids a fatal error in this case on many installations.

Parameters
IDatabase$conn
Returns
int|bool Returns false on error

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1857 of file LoadBalancer.php.

References Wikimedia\Rdbms\IDatabase\getLag(), and Wikimedia\Rdbms\LoadBalancer\getServerCount().

◆ safeWaitForMasterPos()

Wikimedia\Rdbms\LoadBalancer::safeWaitForMasterPos ( IDatabase  $conn,
  $pos = false,
  $timeout = null 
)

Wait for a replica DB to reach a specified master position.

This will connect to the master to get an accurate position if $pos is not given

Parameters
IDatabase$connReplica DB
DBMasterPos | bool$posMaster position; default: current position
int$timeoutTimeout in seconds [optional]
Returns
bool Success

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1865 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\closeConnection(), Wikimedia\Rdbms\LoadBalancer\getAnyOpenConnection(), Wikimedia\Rdbms\IDatabase\getLBInfo(), Wikimedia\Rdbms\IDatabase\getServer(), Wikimedia\Rdbms\LoadBalancer\getServerCount(), Wikimedia\Rdbms\LoadBalancer\getWriterIndex(), Wikimedia\Rdbms\IDatabase\masterPosWait(), null, and Wikimedia\Rdbms\LoadBalancer\openConnection().

◆ setDomainPrefix()

Wikimedia\Rdbms\LoadBalancer::setDomainPrefix (   $prefix)
Parameters
string$prefix
Deprecated:
Since 1.33

Definition at line 1943 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\setLocalDomainPrefix().

◆ setIndexAliases()

Wikimedia\Rdbms\LoadBalancer::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[]$aliases
Since
1.31

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1935 of file LoadBalancer.php.

◆ setLocalDomain()

◆ setLocalDomainPrefix()

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

◆ setTableAliases()

Wikimedia\Rdbms\LoadBalancer::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[]$aliases Map of (table => (dbname, schema, prefix) map)

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1931 of file LoadBalancer.php.

◆ setTransactionListener()

Wikimedia\Rdbms\LoadBalancer::setTransactionListener (   $name,
callable  $callback = null 
)

Set a callback via IDatabase::setTransactionListener() on all current and future master connections of this load balancer.

Parameters
string$nameCallback name
callable | null$callback

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 1918 of file LoadBalancer.php.

References $name, Wikimedia\Rdbms\LoadBalancer\forEachOpenMasterConnection(), Wikimedia\Rdbms\IDatabase\setTransactionListener(), and use.

◆ setWaitForPositionIfHigher()

Wikimedia\Rdbms\LoadBalancer::setWaitForPositionIfHigher (   $pos)
private
Parameters
DBMasterPos | bool$pos

Definition at line 556 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\waitFor().

◆ undoTransactionRoundFlags()

◆ waitFor()

Wikimedia\Rdbms\LoadBalancer::waitFor (   $pos)

Set the master wait position.

If a DB_REPLICA connection has been opened already, then wait immediately. Otherwise sets a variable telling it to wait if such a connection is opened.

This only applies to connections to the generic replica DB for this request. If a timeout happens when waiting, then getLaggedReplicaMode()/laggedReplicaUsed() will return true.

Parameters
DBMasterPos | bool$posMaster position or false

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 484 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$readIndex, Wikimedia\Rdbms\LoadBalancer\$waitForPos, Wikimedia\Rdbms\LoadBalancer\doWait(), and Wikimedia\Rdbms\LoadBalancer\setWaitForPositionIfHigher().

◆ waitForAll()

Wikimedia\Rdbms\LoadBalancer::waitForAll (   $pos,
  $timeout = null 
)

Set the master wait position and wait for ALL replica DBs to catch up to it.

Parameters
DBMasterPos | bool$posMaster position or false
int | null$timeoutMax seconds to wait; default is mWaitTimeout
Returns
bool Success (able to connect and no timeouts reached)

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 526 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$waitForPos, Wikimedia\Rdbms\LoadBalancer\$waitTimeout, Wikimedia\Rdbms\LoadBalancer\doWait(), and servers.

◆ waitForOne()

Wikimedia\Rdbms\LoadBalancer::waitForOne (   $pos,
  $timeout = null 
)

Set the master wait position and wait for a "generic" replica DB to catch up to it.

This can be used a faster proxy for waitForAll()

Parameters
DBMasterPos | bool$posMaster position or false
int | null$timeoutMax seconds to wait; default is mWaitTimeout
Returns
bool Success (able to connect and no timeouts reached)

Implements Wikimedia\Rdbms\ILoadBalancer.

Definition at line 499 of file LoadBalancer.php.

References Wikimedia\Rdbms\LoadBalancer\$loads, Wikimedia\Rdbms\LoadBalancer\$readIndex, Wikimedia\Rdbms\LoadBalancer\$waitForPos, Wikimedia\Rdbms\LoadBalancer\doWait(), Wikimedia\Rdbms\LoadBalancer\getWriterIndex(), and ArrayUtils\pickRandom().

Member Data Documentation

◆ $agent

string Wikimedia\Rdbms\LoadBalancer::$agent
private

Agent name for query profiling.

Definition at line 95 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection().

◆ $allowLagged

bool Wikimedia\Rdbms\LoadBalancer::$allowLagged
private

Whether to disregard replica DB lag as a factor in replica DB selection.

Definition at line 80 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\allowLagged().

◆ $allReplicasDownMode

bool Wikimedia\Rdbms\LoadBalancer::$allReplicasDownMode = false
private

Whether the generic reader fell back to a lagged replica DB.

Definition at line 113 of file LoadBalancer.php.

◆ $chronologyCallback

callable null Wikimedia\Rdbms\LoadBalancer::$chronologyCallback
private

Callback to run before the first connection attempt.

Definition at line 45 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\openConnection().

◆ $cliMode

bool Wikimedia\Rdbms\LoadBalancer::$cliMode
private

Whether this PHP instance is for a CLI script.

Definition at line 93 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection().

◆ $connectionAttempted

bool Wikimedia\Rdbms\LoadBalancer::$connectionAttempted = false
private

Whether any connection has been attempted yet.

Definition at line 123 of file LoadBalancer.php.

◆ $connLogger

LoggerInterface Wikimedia\Rdbms\LoadBalancer::$connLogger
private

Definition at line 57 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection().

◆ $conns

Database [][][] Wikimedia\Rdbms\LoadBalancer::$conns
private

Map of (connection category => server index => IDatabase[])

Definition at line 71 of file LoadBalancer.php.

◆ $connsOpened

int Wikimedia\Rdbms\LoadBalancer::$connsOpened = 0
private

Total connections opened.

Definition at line 119 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\closeConnection(), and Wikimedia\Rdbms\LoadBalancer\getConnection().

◆ $defaultGroup

string null Wikimedia\Rdbms\LoadBalancer::$defaultGroup = null
private

Definition at line 131 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\getConnection().

◆ $deprecationLogger

callable Wikimedia\Rdbms\LoadBalancer::$deprecationLogger
private

Deprecation logger.

Definition at line 65 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection().

◆ $disabled

bool Wikimedia\Rdbms\LoadBalancer::$disabled = false
private

Definition at line 121 of file LoadBalancer.php.

◆ $errorConnection

Database Wikimedia\Rdbms\LoadBalancer::$errorConnection
private

DB connection object that caused a problem.

Definition at line 105 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\reportConnectionError().

◆ $errorLogger

callable Wikimedia\Rdbms\LoadBalancer::$errorLogger
private

◆ $groupLoads

array [] Wikimedia\Rdbms\LoadBalancer::$groupLoads
private

Map of (group => server index => weight)

Definition at line 78 of file LoadBalancer.php.

◆ $hostname

string Wikimedia\Rdbms\LoadBalancer::$hostname
private

Current server name.

Definition at line 91 of file LoadBalancer.php.

◆ $indexAliases

string [] Wikimedia\Rdbms\LoadBalancer::$indexAliases = []
private

Map of (index alias => index)

Definition at line 100 of file LoadBalancer.php.

◆ $laggedReplicaMode

bool Wikimedia\Rdbms\LoadBalancer::$laggedReplicaMode = false
private

Whether the generic reader fell back to a lagged replica DB.

Definition at line 111 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\getLaggedReplicaMode(), Wikimedia\Rdbms\LoadBalancer\laggedReplicaUsed(), and Wikimedia\Rdbms\LoadBalancer\pickReaderIndex().

◆ $lastError

string Wikimedia\Rdbms\LoadBalancer::$lastError = 'Unknown error'
private

The last DB selection or connection error.

Definition at line 115 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\getConnection(), and Wikimedia\Rdbms\LoadBalancer\reportConnectionError().

◆ $loadMonitor

ILoadMonitor Wikimedia\Rdbms\LoadBalancer::$loadMonitor
private

Definition at line 43 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\getLoadMonitor().

◆ $loadMonitorConfig

array Wikimedia\Rdbms\LoadBalancer::$loadMonitorConfig
private

The LoadMonitor configuration.

Definition at line 84 of file LoadBalancer.php.

◆ $loads

float [] Wikimedia\Rdbms\LoadBalancer::$loads
private

◆ $localDomain

DatabaseDomain Wikimedia\Rdbms\LoadBalancer::$localDomain
private

Local Domain ID and default for selectDB() calls.

Definition at line 68 of file LoadBalancer.php.

◆ $localDomainIdAlias

string Wikimedia\Rdbms\LoadBalancer::$localDomainIdAlias
private

Alternate ID string for the domain instead of DatabaseDomain::getId()

Definition at line 86 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\getConnection(), and Wikimedia\Rdbms\LoadBalancer\openConnection().

◆ $maxLag

int Wikimedia\Rdbms\LoadBalancer::$maxLag
private

◆ $perfLogger

LoggerInterface Wikimedia\Rdbms\LoadBalancer::$perfLogger
private

Definition at line 61 of file LoadBalancer.php.

◆ $profiler

mixed Wikimedia\Rdbms\LoadBalancer::$profiler
private

Class name or object With profileIn/profileOut methods.

Definition at line 51 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection().

◆ $queryLogger

LoggerInterface Wikimedia\Rdbms\LoadBalancer::$queryLogger
private

Definition at line 59 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection().

◆ $readIndex

int Wikimedia\Rdbms\LoadBalancer::$readIndex
private

The generic (not query grouped) replica DB index (of $mServers)

Definition at line 107 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\getReaderIndex(), Wikimedia\Rdbms\LoadBalancer\waitFor(), and Wikimedia\Rdbms\LoadBalancer\waitForOne().

◆ $readOnlyReason

string bool Wikimedia\Rdbms\LoadBalancer::$readOnlyReason = false
private

Reason the LB is read-only or false if not.

Definition at line 117 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\getReadOnlyReason().

◆ $replLogger

LoggerInterface Wikimedia\Rdbms\LoadBalancer::$replLogger
private

Definition at line 55 of file LoadBalancer.php.

◆ $servers

array [] Wikimedia\Rdbms\LoadBalancer::$servers
private

Map of (server index => server config array)

Definition at line 74 of file LoadBalancer.php.

◆ $srvCache

BagOStuff Wikimedia\Rdbms\LoadBalancer::$srvCache
private

Definition at line 47 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection().

◆ $tableAliases

Wikimedia\Rdbms\LoadBalancer::$tableAliases = []
private

Definition at line 98 of file LoadBalancer.php.

◆ $trxProfiler

TransactionProfiler Wikimedia\Rdbms\LoadBalancer::$trxProfiler
private

Definition at line 53 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\reallyOpenConnection().

◆ $trxRecurringCallbacks

array [] Wikimedia\Rdbms\LoadBalancer::$trxRecurringCallbacks = []
private

Map of (name => callable)

Definition at line 102 of file LoadBalancer.php.

◆ $trxRoundId

string bool Wikimedia\Rdbms\LoadBalancer::$trxRoundId = false
private

String if a requested DBO_TRX transaction round is active.

Definition at line 126 of file LoadBalancer.php.

◆ $trxRoundStage

string Wikimedia\Rdbms\LoadBalancer::$trxRoundStage = self::ROUND_CURSORY
private

Stage of the current transaction round in the transaction round life-cycle.

Definition at line 128 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\getTransactionRoundStage(), and Wikimedia\Rdbms\LoadBalancer\runMasterTransactionIdleCallbacks().

◆ $waitForPos

bool DBMasterPos Wikimedia\Rdbms\LoadBalancer::$waitForPos
private

◆ $waitTimeout

int Wikimedia\Rdbms\LoadBalancer::$waitTimeout
private

Seconds to spend waiting on replica DB lag to resolve.

Definition at line 82 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\waitForAll().

◆ $wanCache

WANObjectCache Wikimedia\Rdbms\LoadBalancer::$wanCache
private

Definition at line 49 of file LoadBalancer.php.

Referenced by Wikimedia\Rdbms\LoadBalancer\masterRunningReadOnly().

◆ KEY_FOREIGN_FREE

const Wikimedia\Rdbms\LoadBalancer::KEY_FOREIGN_FREE = 'foreignFree'

Definition at line 144 of file LoadBalancer.php.

◆ KEY_FOREIGN_FREE_NOROUND

const Wikimedia\Rdbms\LoadBalancer::KEY_FOREIGN_FREE_NOROUND = 'foreignFreeAutoCommit'

Definition at line 148 of file LoadBalancer.php.

◆ KEY_FOREIGN_INUSE

const Wikimedia\Rdbms\LoadBalancer::KEY_FOREIGN_INUSE = 'foreignInUse'

Definition at line 145 of file LoadBalancer.php.

◆ KEY_FOREIGN_INUSE_NOROUND

const Wikimedia\Rdbms\LoadBalancer::KEY_FOREIGN_INUSE_NOROUND = 'foreignInUseAutoCommit'

Definition at line 149 of file LoadBalancer.php.

◆ KEY_LOCAL

const Wikimedia\Rdbms\LoadBalancer::KEY_LOCAL = 'local'

Definition at line 143 of file LoadBalancer.php.

◆ KEY_LOCAL_NOROUND

const Wikimedia\Rdbms\LoadBalancer::KEY_LOCAL_NOROUND = 'localAutoCommit'

Definition at line 147 of file LoadBalancer.php.


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