Database load balancing object. More...

Inheritance diagram for LoadBalancer:

Collaboration diagram for LoadBalancer:

Public Member Functions
	__construct (array $params)

	allowLagged ($mode=null)
	Disables/enables lag checks. More...

	approveMasterChanges (array $options)
	Perform all pre-commit checks for things like replication safety. More...

	clearLagTimeCache ()
	Clear the cache for slag lag delay times. More...

	closeAll ()
	Close all open connections. More...

	closeConnection ($conn)
	Close a connection Using this function makes sure the LoadBalancer knows the connection is closed. More...

	commitAll ($fname=__METHOD__)
	Commit transactions on all open connections. More...

	commitMasterChanges ($fname=__METHOD__)
	Issue COMMIT on all master connections where writes where done. More...

	disable ()
	Disable this load balancer. 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...

	getAnyOpenConnection ($i)
	Get any open connection to a given server index, local or foreign Returns false if there is no connection open. More...

	getConnection ($i, $groups=[], $wiki=false)
	Get a connection by index This is the main entry point for this class. More...

	getConnectionRef ($db, $groups=[], $wiki=false)
	Get a database connection handle reference. More...

	getLaggedSlaveMode ($wiki=false)

	getLagTimes ($wiki=false)
	Get an estimate of replication lag (in seconds) for each server. More...

	getLazyConnectionRef ($db, $groups=[], $wiki=false)
	Get a database connection handle reference without connecting yet. More...

	getMasterPos ()
	Get the current master position for chronology control purposes. More...

	getMaxLag ($wiki=false)
	Get the hostname and lag time of the most-lagged slave. More...

	getReaderIndex ($group=false, $wiki=false)
	Get the index of the reader connection, which may be a slave This takes into account load ratios and lag times. More...

	getReadOnlyReason ($wiki=false, DatabaseBase $conn=null)

	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 Prefer a readable name if available. More...

	getWriterIndex ()

	hasMasterChanges ()
	Determine if there are pending changes 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...

	laggedSlaveUsed ()

	lastMasterChangeTimestamp ()
	Get the timestamp of the latest write query done by this thread. More...

	openConnection ($i, $wiki=false)
	Open a connection to the server given by the specified index Index must be an actual index into the array. More...

	parentInfo ($x=null)
	Get or set arbitrary data used by the parent object, usually an LBFactory. More...

	pendingMasterChangeCallers ()
	Get the list of callers that have pending master changes. More...

	pingAll ()

	reuseConnection ($conn)
	Mark a foreign connection as being available for reuse under a different DB name or prefix. More...

	rollbackMasterChanges ($fname=__METHOD__)
	Issue ROLLBACK only on master, only if queries were done on connection. More...

	runMasterPostCommitCallbacks ()
	Issue all pending post-commit callbacks. More...

	runMasterPreCommitCallbacks ()
	Perform all pre-commit callbacks that remain part of the atomic transactions and disable any post-commit callbacks until runMasterPostCommitCallbacks() 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=10)
	Wait for a slave DB to reach a specified master position. More...

	setServerInfo ($i, array $serverInfo)
	Sets the server info structure for the given index. More...

	waitFor ($pos)
	Set the master wait position If a DB_SLAVE connection has been opened already, waits Otherwise sets a variable telling it to wait if such a connection is opened. More...

	waitForAll ($pos, $timeout=null)
	Set the master wait position and wait for ALL slaves to catch up to it. More...

	waitForOne ($pos, $timeout=null)
	Set the master wait position and wait for a "generic" slave to catch up to it. More...

	waitTimeout ($value=null)

Protected Member Functions
	doWait ($index, $open=false, $timeout=null)
	Wait for a given slave to catch up to the master pos stored in $this. More...

	reallyOpenConnection ($server, $dbNameOverride=false)
	Really opens a connection. More...

Protected Attributes
TransactionProfiler	$trxProfiler

Private Member Functions
	getLoadMonitor ()
	Get a LoadMonitor instance. More...

	getRandomNonLagged (array $loads, $wiki=false, $maxLag=self::MAX_LAG)

	isOpen ($index)
	Test if the specified index represents an open connection. More...

	masterRunningReadOnly ($wiki, DatabaseBase $conn=null)

	openForeignConnection ($i, $wiki)
	Open a connection to a foreign DB, or return one if it is already open. More...

	reportConnectionError ()

Private Attributes
integer	$connsOpened = 0
	Total connections opened. More...

boolean	$disabled = false

bool	$laggedSlaveMode = false
	Whether the generic reader fell back to a lagged slave. More...

bool	$mAllowLagged
	Whether to disregard slave lag as a factor in slave selection. More...

array[]	$mConns
	Map of (local/foreignUsed/foreignFree => server index => DatabaseBase array) More...

bool DatabaseBase	$mErrorConnection
	Database connection that caused a problem. More...

array[]	$mGroupLoads
	Map of (group => server index => weight) More...

string	$mLastError = 'Unknown error'
	The last DB selection or connection error. More...

LoadMonitor	$mLoadMonitor

string	$mLoadMonitorClass
	The LoadMonitor subclass name. More...

array	$mLoads
	Map of (server index => weight) More...

array	$mParentInfo
	LBFactory information. More...

integer	$mReadIndex
	The generic (not query grouped) slave index (of $mServers) More...

array[]	$mServers
	Map of (server index => server config array) More...

bool DBMasterPos	$mWaitForPos
	False if not set. More...

integer	$mWaitTimeout
	Seconds to spend waiting on slave lag to resolve. More...

string bool	$readOnlyReason = false
	Reason the LB is read-only or false if not. More...

bool	$slavesDownMode = false
	Whether the generic reader fell back to a lagged slave. More...

BagOStuff	$srvCache

WANObjectCache	$wanCache

Detailed Description

Database load balancing object.

Todo:: document

Definition at line 30 of file LoadBalancer.php.

Constructor & Destructor Documentation

LoadBalancer::__construct ( array $params )

Parameters

array

$params

Array with keys:

servers : Required. Array of server info structures.
loadMonitor : Name of a class used to fetch server lag and load.
readOnlyReason : Reason the master DB is read-only if so [optional]

Exceptions

MWException

Definition at line 96 of file LoadBalancer.php.

References as, ObjectCache\getLocalServerInstance(), and ObjectCache\getMainWANInstance().

Member Function Documentation

LoadBalancer::allowLagged ( $mode = null )

Disables/enables lag checks.

Parameters

null | bool $mode

Returns: bool

Definition at line 1333 of file LoadBalancer.php.

References $mAllowLagged.

LoadBalancer::approveMasterChanges ( array $options )

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

Parameters

array

$options

Includes:

maxWriteDuration : max write query duration time in seconds

Exceptions

DBTransactionError

Since: 1.28

Definition at line 1081 of file LoadBalancer.php.

References $limit, $time, forEachOpenMasterConnection(), DatabaseBase\pendingWriteQueryDuration(), text, use, and wfMessage().

LoadBalancer::clearLagTimeCache ( )

Clear the cache for slag lag delay times.

This is only used for testing

Definition at line 1503 of file LoadBalancer.php.

References getLoadMonitor().

LoadBalancer::closeAll ( )

Close all open connections.

Definition at line 1011 of file LoadBalancer.php.

References DatabaseBase\close(), and forEachOpenConnection().

Referenced by disable().

LoadBalancer::closeConnection ( $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

DatabaseBase $conn

Definition at line 1030 of file LoadBalancer.php.

References $connsOpened, and as.

Referenced by doWait().

LoadBalancer::commitAll ( $fname = __METHOD__ )

Commit transactions on all open connections.

Parameters

string $fname Caller name

Definition at line 1054 of file LoadBalancer.php.

References $fname, DatabaseBase\commit(), forEachOpenConnection(), and use.

LoadBalancer::commitMasterChanges ( $fname = __METHOD__ )

Issue COMMIT on all master connections where writes where done.

Parameters

string $fname Caller name

Definition at line 1100 of file LoadBalancer.php.

References $fname, DatabaseBase\commit(), forEachOpenMasterConnection(), use, and DatabaseBase\writesOrCallbacksPending().

LoadBalancer::disable ( )

Disable this load balancer.

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

Since: 1.27

Definition at line 1003 of file LoadBalancer.php.

References closeAll().

LoadBalancer::doWait	(	$index,
		$open = `false`,
		$timeout = `null`
	)

protected

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

Parameters

int	$index	Server index
bool	$open	Check the server even if a new connection has to be made
int	$timeout	Max seconds to wait; default is mWaitTimeout

Returns: bool

Definition at line 456 of file LoadBalancer.php.

References $mWaitTimeout, closeConnection(), getAnyOpenConnection(), getServerName(), openConnection(), IExpiringStore\TTL_DAY, wfBacktrace(), and wfDebugLog().

Referenced by getReaderIndex(), waitFor(), waitForAll(), and waitForOne().

LoadBalancer::forEachOpenConnection	(		$callback,
		array	$params = `[]`
	)

Call a function with each open connection object.

Parameters

callable	$callback
array	$params

Definition at line 1361 of file LoadBalancer.php.

References $params, and as.

Referenced by closeAll(), commitAll(), JobRunner\commitMasterChanges(), and pingAll().

LoadBalancer::forEachOpenMasterConnection	(		$callback,
		array	$params = `[]`
	)

Call a function with each open connection object to a master.

Parameters

callable	$callback
array	$params

Since: 1.28

Definition at line 1378 of file LoadBalancer.php.

References $params, as, and getWriterIndex().

Referenced by approveMasterChanges(), commitMasterChanges(), runMasterPostCommitCallbacks(), and runMasterPreCommitCallbacks().

LoadBalancer::getAnyOpenConnection ( $i )

Get any open connection to a given server index, local or foreign Returns false if there is no connection open.

Parameters

int $i

Returns: DatabaseBase|bool False on failure

Definition at line 439 of file LoadBalancer.php.

References as.

Referenced by doWait(), getMasterPos(), isOpen(), ChronologyProtector\shutdownLB(), and waitFor().

LoadBalancer::getConnection	(	$i,
		$groups = `[]`,
		$wiki = `false`
	)

Get a connection by index This is the main entry point for this class.

Parameters

int	$i	Server index
array \| string \| bool	$groups	Query group(s), or false for the generic reader
string \| bool	$wiki	Wiki ID, or false for the current wiki

Exceptions

MWException

Returns: DatabaseBase

Definition at line 525 of file LoadBalancer.php.

References $connsOpened, $mLastError, array(), as, DB_MASTER, DB_SLAVE, getReaderIndex(), getReadOnlyReason(), getWriterIndex(), Profiler\instance(), openConnection(), reportConnectionError(), and wfWikiID().

Referenced by getConnectionRef(), getLaggedSlaveMode(), masterRunningReadOnly(), and safeWaitForMasterPos().

LoadBalancer::getConnectionRef	(	$db,
		$groups = `[]`,
		$wiki = `false`
	)

Get a database connection handle reference.

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

See Also: LoadBalancer::getConnection() for parameter information

Parameters

int	$db
array \| string \| bool	$groups	Query group(s), or false for the generic reader
string \| bool	$wiki	Wiki ID, or false for the current wiki

Returns: DBConnRef

Definition at line 651 of file LoadBalancer.php.

References getConnection().

LoadBalancer::getLaggedSlaveMode ( $wiki = false )

Note: This method will trigger a DB connection if not yet done

Parameters

string | bool $wiki Wiki ID, or false for the current wiki

Returns: bool Whether the generic connection for reads is highly "lagged"

Definition at line 1253 of file LoadBalancer.php.

References $e, $laggedSlaveMode, DB_SLAVE, getConnection(), getServerCount(), and reuseConnection().

Referenced by getReadOnlyReason().

LoadBalancer::getLagTimes ( $wiki = 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 $wiki

Returns: int[] Map of (server index => float|int|bool)

Definition at line 1432 of file LoadBalancer.php.

References getLoadMonitor(), and getServerCount().

Referenced by getMaxLag(), and getRandomNonLagged().

LoadBalancer::getLazyConnectionRef	(	$db,
		$groups = `[]`,
		$wiki = `false`
	)

Get a database connection handle reference without connecting yet.

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

See Also: LoadBalancer::getConnection() for parameter information

Parameters

int	$db
array \| string \| bool	$groups	Query group(s), or false for the generic reader
string \| bool	$wiki	Wiki ID, or false for the current wiki

Returns: DBConnRef

Definition at line 667 of file LoadBalancer.php.

Referenced by reallyOpenConnection().

LoadBalancer::getLoadMonitor ( )

private

Get a LoadMonitor instance.

Returns: LoadMonitor

Definition at line 156 of file LoadBalancer.php.

References $mLoadMonitor, and $mLoadMonitorClass.

Referenced by clearLagTimeCache(), getLagTimes(), and getReaderIndex().

LoadBalancer::getMasterPos ( )

Get the current master position for chronology control purposes.

Returns: mixed

Definition at line 978 of file LoadBalancer.php.

References getAnyOpenConnection().

LoadBalancer::getMaxLag ( $wiki = false )

Get the hostname and lag time of the most-lagged slave.

This is useful for maintenance scripts that need to throttle their updates. May attempt to open connections to slaves on the default DB. If there is no lag, the maximum lag will be reported as -1.

Parameters

bool | string $wiki Wiki ID, or false for the default database

Returns: array ( host, max lag, index of max lagged host )

Definition at line 1401 of file LoadBalancer.php.

References as, getLagTimes(), and getServerCount().

LoadBalancer::getRandomNonLagged	(	array	$loads,
			$wiki = `false`,
			$maxLag = `self::MAX_LAG`
	)

private

Parameters

array	$loads
bool \| string	$wiki	Wiki to get non-lagged for
int	$maxLag	Restrict the maximum allowed lag to this many seconds

Returns: bool|int|string

Definition at line 180 of file LoadBalancer.php.

References as, getLagTimes(), getServerName(), ArrayUtils\pickRandom(), and wfDebugLog().

Referenced by getReaderIndex().

LoadBalancer::getReaderIndex	(	$group = `false`,
		$wiki = `false`
	)

Get the index of the reader connection, which may be a slave 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	$group	Query group, or false for the generic reader
string \| bool	$wiki	Wiki ID, or false for the current wiki

Exceptions

MWException

Returns: bool|int|string

Definition at line 234 of file LoadBalancer.php.

References $laggedSlaveMode, $mLoads, $mReadIndex, $wgDBtype, doWait(), getLoadMonitor(), getRandomNonLagged(), getServerName(), getWriterIndex(), global, openConnection(), ArrayUtils\pickRandom(), reuseConnection(), and wfDebugLog().

Referenced by getConnection().

LoadBalancer::getReadOnlyReason	(		$wiki = `false`,
		DatabaseBase	$conn = `null`
	)

Note: This method may trigger a DB connection if not yet done

Parameters

string \| bool	$wiki	Wiki ID, or false for the current wiki
	DatabaseBase\|null	DB master connection; used to avoid loops [optional]

Returns: string|bool Reason the master is read-only or false if it is not

Since: 1.27

Definition at line 1286 of file LoadBalancer.php.

References $readOnlyReason, getLaggedSlaveMode(), and masterRunningReadOnly().

Referenced by getConnection().

LoadBalancer::getServerCount ( )

Get the number of defined servers (not the number of open connections)

Returns: int

Definition at line 929 of file LoadBalancer.php.

Referenced by getLaggedSlaveMode(), getLagTimes(), getMaxLag(), ChronologyProtector\initLB(), safeGetLag(), safeWaitForMasterPos(), and ChronologyProtector\shutdownLB().

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

Definition at line 956 of file LoadBalancer.php.

LoadBalancer::getServerName ( $i )

Get the host name or IP address of the server with the specified index Prefer a readable name if available.

Parameters

string $i

Returns: string

Definition at line 939 of file LoadBalancer.php.

References $name.

Referenced by doWait(), getRandomNonLagged(), getReaderIndex(), ChronologyProtector\initLB(), LBFactory\logIfMultiDbTransaction(), masterRunningReadOnly(), openConnection(), reallyOpenConnection(), LBFactory\shutdownChronologyProtector(), and ChronologyProtector\shutdownLB().

LoadBalancer::getWriterIndex ( )

Returns: int

Since: 1.26

Definition at line 900 of file LoadBalancer.php.

Referenced by forEachOpenMasterConnection(), getConnection(), getReaderIndex(), hasMasterChanges(), hasMasterConnection(), ChronologyProtector\initLB(), lastMasterChangeTimestamp(), LBFactory\logIfMultiDbTransaction(), masterRunningReadOnly(), pendingMasterChangeCallers(), rollbackMasterChanges(), LBFactory\shutdownChronologyProtector(), ChronologyProtector\shutdownLB(), and waitForOne().

LoadBalancer::hasMasterChanges ( )

Determine if there are pending changes in a transaction by this thread.

Since: 1.23

Returns: bool

Definition at line 1165 of file LoadBalancer.php.

References as, and getWriterIndex().

Referenced by LBFactory\hasMasterChanges(), and hasOrMadeRecentMasterChanges().

LoadBalancer::hasMasterConnection ( )

Returns: bool Whether a master connection is already open

Since: 1.24

Definition at line 1156 of file LoadBalancer.php.

References getWriterIndex(), and isOpen().

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 $age How many seconds ago is "recent" [defaults to mWaitTimeout]

Returns: bool

Since: 1.25

Definition at line 1209 of file LoadBalancer.php.

References hasMasterChanges(), and lastMasterChangeTimestamp().

Referenced by LBFactory\hasOrMadeRecentMasterChanges().

LoadBalancer::haveIndex ( $i )

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

Parameters

string $i

Returns: bool

Definition at line 910 of file LoadBalancer.php.

LoadBalancer::isNonZeroLoad ( $i )

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

Parameters

string $i

Returns: bool

Definition at line 920 of file LoadBalancer.php.

LoadBalancer::isOpen ( $index )

private

Test if the specified index represents an open connection.

Parameters

int $index Server index

Access:: private

Returns: bool

Definition at line 801 of file LoadBalancer.php.

References getAnyOpenConnection().

Referenced by hasMasterConnection().

LoadBalancer::laggedSlaveUsed ( )

Note: This method will never cause a new DB connection

Returns: bool Whether any generic connection used for reads was highly "lagged"

Since: 1.27

Definition at line 1275 of file LoadBalancer.php.

References $laggedSlaveMode.

Referenced by LBFactory\laggedSlaveUsed().

LoadBalancer::lastMasterChangeTimestamp ( )

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

Since: 1.25

Returns: float|bool UNIX timestamp or false

Definition at line 1186 of file LoadBalancer.php.

References as, and getWriterIndex().

Referenced by hasOrMadeRecentMasterChanges().

LoadBalancer::masterRunningReadOnly	(		$wiki,
		DatabaseBase	$conn = `null`
	)

private

Parameters

string	$wiki	Wiki ID, or false for the current wiki
	DatabaseBase\|null	DB master connectionl used to avoid loops [optional]

Returns: bool

Definition at line 1309 of file LoadBalancer.php.

References $cache, $e, $wanCache, DB_MASTER, getConnection(), getServerName(), getWriterIndex(), and use.

Referenced by getReadOnlyReason().

LoadBalancer::openConnection	(	$i,
		$wiki = `false`
	)

Open a connection to the server given by the specified index Index must be an actual index into the array.

If the server is already open, returns it.

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

Note: If disable() was called on this LoadBalancer, this method will throw a DBAccessError.

Parameters

int	$i	Server index
string \| bool	$wiki	Wiki ID, or false for the current wiki

Returns: DatabaseBase|bool Returns false on errors

Definition at line 685 of file LoadBalancer.php.

References getServerName(), openForeignConnection(), reallyOpenConnection(), and wfDebugLog().

Referenced by doWait(), getConnection(), and getReaderIndex().

LoadBalancer::openForeignConnection	(	$i,
		$wiki
	)

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 wiki. 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->mErrorConnection.

Note: If disable() was called on this LoadBalancer, this method will throw a DBAccessError.

Parameters

int	$i	Server index
string	$wiki	Wiki ID to open

Returns: DatabaseBase

Definition at line 737 of file LoadBalancer.php.

References key, list, reallyOpenConnection(), wfDebug(), wfHostname(), and wfSplitWikiID().

Referenced by openConnection().

LoadBalancer::parentInfo ( $x = null )

Get or set arbitrary data used by the parent object, usually an LBFactory.

Parameters

mixed $x

Returns: mixed

Definition at line 170 of file LoadBalancer.php.

References wfSetVar().

Referenced by ChronologyProtector\initLB(), and ChronologyProtector\shutdownLB().

LoadBalancer::pendingMasterChangeCallers ( )

Get the list of callers that have pending master changes.

Returns: array

Since: 1.27

Definition at line 1222 of file LoadBalancer.php.

References as, and getWriterIndex().

Referenced by LBFactory\logIfMultiDbTransaction().

LoadBalancer::pingAll ( )

Returns: bool

Definition at line 1345 of file LoadBalancer.php.

References $success, forEachOpenConnection(), DatabaseBase\ping(), and use.

LoadBalancer::reallyOpenConnection	(	$server,
		$dbNameOverride = `false`
	)

protected

Really opens a connection.

Uncached. Returns a Database object whether or not the connection was successful.

Access:: private

Parameters

array	$server
bool	$dbNameOverride

Exceptions

MWException

Returns: DatabaseBase

Definition at line 819 of file LoadBalancer.php.

References $e, DB_MASTER, DatabaseBase\factory(), getLazyConnectionRef(), getServerName(), wfBacktrace(), and wfDebugLog().

Referenced by openConnection(), and openForeignConnection().

LoadBalancer::reportConnectionError ( )

private

Exceptions

DBConnectionError

Returns: bool

Definition at line 866 of file LoadBalancer.php.

References $context, $mErrorConnection, $mLastError, and wfLogDBError().

Referenced by getConnection().

LoadBalancer::reuseConnection ( $conn )

Mark a foreign connection as being available for reuse under a different DB name or prefix.

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

Parameters

DatabaseBase $conn

Exceptions

MWException

Definition at line 600 of file LoadBalancer.php.

References wfDebug().

Referenced by getLaggedSlaveMode(), and getReaderIndex().

LoadBalancer::rollbackMasterChanges ( $fname = __METHOD__ )

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

Parameters

string $fname Caller name

Exceptions

DBExpectedError

Since: 1.23

Definition at line 1125 of file LoadBalancer.php.

References $e, $fname, as, getWriterIndex(), and MWExceptionHandler\logException().

LoadBalancer::runMasterPostCommitCallbacks ( )

Issue all pending post-commit callbacks.

Since: 1.28

Definition at line 1112 of file LoadBalancer.php.

References forEachOpenMasterConnection(), DatabaseBase\runOnTransactionIdleCallbacks(), DatabaseBase\setPostCommitCallbackSupression(), and IDatabase\TRIGGER_COMMIT.

LoadBalancer::runMasterPreCommitCallbacks ( )

Perform all pre-commit callbacks that remain part of the atomic transactions and disable any post-commit callbacks until runMasterPostCommitCallbacks()

Since: 1.28

Definition at line 1065 of file LoadBalancer.php.

References forEachOpenMasterConnection(), DatabaseBase\runOnTransactionPreCommitCallbacks(), and DatabaseBase\setPostCommitCallbackSupression().

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

Definition at line 1455 of file LoadBalancer.php.

References IDatabase\getLag(), and getServerCount().

LoadBalancer::safeWaitForMasterPos	(	IDatabase	$conn,
			$pos = `false`,
			$timeout = `10`
	)

Wait for a slave 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	$conn	Slave DB
DBMasterPos \| bool	$pos	Master position; default: current position
integer	$timeout	Timeout in seconds

Returns: bool Success

Since: 1.27

Definition at line 1474 of file LoadBalancer.php.

References DB_MASTER, getConnection(), IDatabase\getLBInfo(), getServerCount(), IDatabase\masterPosWait(), wfBacktrace(), and wfDebugLog().

LoadBalancer::setServerInfo	(		$i,
		array	$serverInfo
	)

Sets the server info structure for the given index.

Entry at index $i is created if it doesn't exist

Parameters

int	$i
array	$serverInfo

Definition at line 970 of file LoadBalancer.php.

LoadBalancer::waitFor ( $pos )

Set the master wait position If a DB_SLAVE connection has been opened already, waits Otherwise sets a variable telling it to wait if such a connection is opened.

Parameters

DBMasterPos $pos

Definition at line 369 of file LoadBalancer.php.

References $mReadIndex, doWait(), and getAnyOpenConnection().

Referenced by ChronologyProtector\initLB().

LoadBalancer::waitForAll	(	$pos,
		$timeout = `null`
	)

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

Parameters

DBMasterPos	$pos
int	$timeout	Max seconds to wait; default is mWaitTimeout

Returns: bool Success (able to connect and no timeouts reached)

Definition at line 418 of file LoadBalancer.php.

References doWait().

Referenced by LBFactory\shutdownChronologyProtector().

LoadBalancer::waitForOne	(	$pos,
		$timeout = `null`
	)

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

This can be used a faster proxy for waitForAll()

Parameters

DBMasterPos	$pos
int	$timeout	Max seconds to wait; default is mWaitTimeout

Returns: bool Success (able to connect and no timeouts reached)

Since: 1.26

Definition at line 391 of file LoadBalancer.php.

References $mLoads, $mReadIndex, doWait(), getWriterIndex(), and ArrayUtils\pickRandom().

LoadBalancer::waitTimeout ( $value = null )

Parameters

mixed $value

Returns: mixed

Definition at line 1243 of file LoadBalancer.php.

References $value, and wfSetVar().

Member Data Documentation

integer LoadBalancer::$connsOpened = 0

private

Total connections opened.

Definition at line 70 of file LoadBalancer.php.

Referenced by closeConnection(), and getConnection().

boolean LoadBalancer::$disabled = false

private

Definition at line 87 of file LoadBalancer.php.

bool LoadBalancer::$laggedSlaveMode = false

private

Whether the generic reader fell back to a lagged slave.

Definition at line 62 of file LoadBalancer.php.

Referenced by getLaggedSlaveMode(), getReaderIndex(), and laggedSlaveUsed().

bool LoadBalancer::$mAllowLagged

private

Whether to disregard slave lag as a factor in slave selection.

Definition at line 40 of file LoadBalancer.php.

Referenced by allowLagged().

array [] LoadBalancer::$mConns

private

Map of (local/foreignUsed/foreignFree => server index => DatabaseBase array)

Definition at line 34 of file LoadBalancer.php.

bool DatabaseBase LoadBalancer::$mErrorConnection

private

Database connection that caused a problem.

Definition at line 56 of file LoadBalancer.php.

Referenced by reportConnectionError().

array [] LoadBalancer::$mGroupLoads

private

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

Definition at line 38 of file LoadBalancer.php.

string LoadBalancer::$mLastError = 'Unknown error'

private

The last DB selection or connection error.

Definition at line 66 of file LoadBalancer.php.

Referenced by getConnection(), and reportConnectionError().

LoadMonitor LoadBalancer::$mLoadMonitor

private

Definition at line 49 of file LoadBalancer.php.

Referenced by getLoadMonitor().

string LoadBalancer::$mLoadMonitorClass

private

The LoadMonitor subclass name.

Definition at line 47 of file LoadBalancer.php.

Referenced by getLoadMonitor().

array LoadBalancer::$mLoads

private

Map of (server index => weight)

Definition at line 36 of file LoadBalancer.php.

Referenced by getReaderIndex(), and waitForOne().

array LoadBalancer::$mParentInfo

private

LBFactory information.

Definition at line 44 of file LoadBalancer.php.

integer LoadBalancer::$mReadIndex

private

The generic (not query grouped) slave index (of $mServers)

Definition at line 58 of file LoadBalancer.php.

Referenced by getReaderIndex(), waitFor(), and waitForOne().

array [] LoadBalancer::$mServers

private

Map of (server index => server config array)

Definition at line 32 of file LoadBalancer.php.

bool DBMasterPos LoadBalancer::$mWaitForPos

private

False if not set.

Definition at line 60 of file LoadBalancer.php.

integer LoadBalancer::$mWaitTimeout

private

Seconds to spend waiting on slave lag to resolve.

Definition at line 42 of file LoadBalancer.php.

Referenced by doWait().

string bool LoadBalancer::$readOnlyReason = false

private

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

Definition at line 68 of file LoadBalancer.php.

Referenced by getReadOnlyReason().

bool LoadBalancer::$slavesDownMode = false

private

Whether the generic reader fell back to a lagged slave.

Definition at line 64 of file LoadBalancer.php.

BagOStuff LoadBalancer::$srvCache

private

Definition at line 51 of file LoadBalancer.php.

TransactionProfiler LoadBalancer::$trxProfiler

protected

Definition at line 73 of file LoadBalancer.php.

Referenced by LoadBalancerSingle\__construct().

WANObjectCache LoadBalancer::$wanCache

private

Definition at line 53 of file LoadBalancer.php.

Referenced by masterRunningReadOnly().

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

includes/db/loadbalancer/LoadBalancer.php

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