Basic DB load monitor with no external dependencies. More...

Inheritance diagram for Wikimedia\Rdbms\LoadMonitor:

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Collaboration diagram for Wikimedia\Rdbms\LoadMonitor:

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Public Member Functions
	__construct (ILoadBalancer $lb, BagOStuff $srvCache, WANObjectCache $wCache, array $options=[])

	getLagTimes (array $serverIndexes)
	Get an estimate of replication lag (in seconds) for each server. More...

	movingAverage ( $priorValue, $gaugeValue, float $delay, float $movAveRatio)
	Update a moving average for a gauge, accounting for the time delay since the last gauge. More...

	scaleLoads (array &$weightByServer)
	Perform load ratio adjustment before deciding which server to use. More...

	setLogger (LoggerInterface $logger)

	setMockTime (&$time)

	setStatsdDataFactory (StatsdDataFactoryInterface $statsFactory)
	Sets a StatsdDataFactory instance on the object. More...

Protected Member Functions
	computeServerStates (array $serverIndexes, $priorStates)

	getCurrentTime ()

	getServerStates (array $serverIndexes)

	getWeightScale ( $index, IDatabase $conn=null)

	isStateRefreshDue ( $priorAsOf, $priorGenDelay, $referenceTTL, $now)

Protected Attributes
ILoadBalancer	$lb

LoggerInterface	$logger

BagOStuff	$srvCache

StatsdDataFactoryInterface	$statsd

WANObjectCache	$wanCache

Detailed Description

Basic DB load monitor with no external dependencies.

Uses both server-local and shared caches for server state information.

The "domain" parameters are unused, though they might be used in the future. Therefore, at present, this assumes one channel of replication per server.

Definition at line 41 of file LoadMonitor.php.

Constructor & Destructor Documentation

◆ __construct()

Wikimedia\Rdbms\LoadMonitor::__construct	(	ILoadBalancer	$lb,
		BagOStuff	$srvCache,
		WANObjectCache	$wCache,
		array	$options = `[]`
	)

Parameters

ILoadBalancer	$lb
BagOStuff	$srvCache
WANObjectCache	$wCache
array	$options	Additional parameters include: movingAveRatio: maximum new gauge coefficient for moving averages when the new gauge is 1 second newer than the prior one [default: .54] lagWarnThreshold: how many seconds of lag trigger warnings [default: 10]

Implements Wikimedia\Rdbms\ILoadMonitor.

Definition at line 83 of file LoadMonitor.php.

References Wikimedia\Rdbms\LoadMonitor\$lb, Wikimedia\Rdbms\LoadMonitor\$srvCache, and Wikimedia\Rdbms\LoadBalancer\MAX_LAG_DEFAULT.

Member Function Documentation

◆ computeServerStates()

Wikimedia\Rdbms\LoadMonitor::computeServerStates	(	array	$serverIndexes,
			$priorStates
	)

protected

Parameters

array	$serverIndexes
array \| false	$priorStates

Returns: array

Exceptions

DBAccessError

Definition at line 232 of file LoadMonitor.php.

References Wikimedia\Rdbms\LoadMonitor\getCurrentTime(), Wikimedia\Rdbms\LoadMonitor\getWeightScale(), and Wikimedia\Rdbms\LoadMonitor\movingAverage().

Referenced by Wikimedia\Rdbms\LoadMonitor\getServerStates().

◆ getCurrentTime()

Wikimedia\Rdbms\LoadMonitor::getCurrentTime ( )

protected

Returns: float UNIX timestamp

Definition at line 420 of file LoadMonitor.php.

Referenced by Wikimedia\Rdbms\LoadMonitor\computeServerStates(), and Wikimedia\Rdbms\LoadMonitor\getServerStates().

◆ getLagTimes()

Wikimedia\Rdbms\LoadMonitor::getLagTimes ( array $serverIndexes )

final

Get an estimate of replication lag (in seconds) for each server.

Values may be "false" if replication is too broken to estimate

Parameters

int[] $serverIndexes

Returns: array Map of (server index => float|int|false)

Implements Wikimedia\Rdbms\ILoadMonitor.

Definition at line 118 of file LoadMonitor.php.

References Wikimedia\Rdbms\LoadMonitor\getServerStates().

◆ getServerStates()

Wikimedia\Rdbms\LoadMonitor::getServerStates ( array $serverIndexes )

protected

Parameters

array $serverIndexes

Returns: array

Exceptions

DBAccessError

Definition at line 127 of file LoadMonitor.php.

References Wikimedia\Rdbms\LoadMonitor\computeServerStates(), Wikimedia\Rdbms\LoadMonitor\getCurrentTime(), and Wikimedia\Rdbms\LoadMonitor\isStateRefreshDue().

Referenced by Wikimedia\Rdbms\LoadMonitor\getLagTimes(), and Wikimedia\Rdbms\LoadMonitor\scaleLoads().

◆ getWeightScale()

Wikimedia\Rdbms\LoadMonitor::getWeightScale	(		$index,
		IDatabase	$conn = `null`
	)

protected

Parameters

int	$index	Server index
IDatabase \| null	$conn	Connection handle or null on connection failure

Returns: float

Since: 1.28

Definition at line 351 of file LoadMonitor.php.

Referenced by Wikimedia\Rdbms\LoadMonitor\computeServerStates().

◆ isStateRefreshDue()

Wikimedia\Rdbms\LoadMonitor::isStateRefreshDue	(	$priorAsOf,
		$priorGenDelay,
		$referenceTTL,
		$now
	)

protected

Parameters

float	$priorAsOf
float	$priorGenDelay
float	$referenceTTL
float	$now

Returns: bool

Definition at line 213 of file LoadMonitor.php.

Referenced by Wikimedia\Rdbms\LoadMonitor\getServerStates().

◆ movingAverage()

Wikimedia\Rdbms\LoadMonitor::movingAverage	(		$priorValue,
			$gaugeValue,
		float	$delay,
		float	$movAveRatio
	)

Update a moving average for a gauge, accounting for the time delay since the last gauge.

Parameters

float \| int \| null	$priorValue	Prior moving average of value or null
float \| int \| null	$gaugeValue	Newly gauged value or null
float	$delay	Seconds between the new gauge and the prior one
float	$movAveRatio	New gauge weight when it is 1 second newer than the prior one

Returns: float|false New moving average of value

Definition at line 364 of file LoadMonitor.php.

Referenced by Wikimedia\Rdbms\LoadMonitor\computeServerStates().

◆ scaleLoads()

Wikimedia\Rdbms\LoadMonitor::scaleLoads ( array & $weightByServer )

final

Perform load ratio adjustment before deciding which server to use.

Parameters

int[] &$weightByServer Map of (server index => float weight)

Implements Wikimedia\Rdbms\ILoadMonitor.

Definition at line 104 of file LoadMonitor.php.

References Wikimedia\Rdbms\LoadMonitor\getServerStates().

◆ setLogger()

Wikimedia\Rdbms\LoadMonitor::setLogger ( LoggerInterface $logger )

Definition at line 96 of file LoadMonitor.php.

References Wikimedia\Rdbms\LoadMonitor\$logger.

◆ setMockTime()

Wikimedia\Rdbms\LoadMonitor::setMockTime ( & $time )

Parameters

float | null &$time Mock UNIX timestamp for testing

Definition at line 428 of file LoadMonitor.php.

◆ setStatsdDataFactory()

Wikimedia\Rdbms\LoadMonitor::setStatsdDataFactory ( StatsdDataFactoryInterface $statsFactory )

Sets a StatsdDataFactory instance on the object.

Parameters

StatsdDataFactoryInterface $statsFactory

Returns: null

Implements StatsdAwareInterface.

Definition at line 100 of file LoadMonitor.php.

Member Data Documentation

◆ $lb

ILoadBalancer Wikimedia\Rdbms\LoadMonitor::$lb

protected

Definition at line 43 of file LoadMonitor.php.

Referenced by Wikimedia\Rdbms\LoadMonitor\__construct().

◆ $logger

LoggerInterface Wikimedia\Rdbms\LoadMonitor::$logger

protected

Definition at line 49 of file LoadMonitor.php.

Referenced by Wikimedia\Rdbms\LoadMonitor\setLogger().

◆ $srvCache

BagOStuff Wikimedia\Rdbms\LoadMonitor::$srvCache

protected

Definition at line 45 of file LoadMonitor.php.

Referenced by Wikimedia\Rdbms\LoadMonitor\__construct().

◆ $statsd

StatsdDataFactoryInterface Wikimedia\Rdbms\LoadMonitor::$statsd

protected

Definition at line 51 of file LoadMonitor.php.

◆ $wanCache

WANObjectCache Wikimedia\Rdbms\LoadMonitor::$wanCache

protected

Definition at line 47 of file LoadMonitor.php.

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

includes/libs/rdbms/loadmonitor/LoadMonitor.php

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ __construct()

Member Function Documentation

◆ computeServerStates()

◆ getCurrentTime()

◆ getLagTimes()

◆ getServerStates()

◆ getWeightScale()

◆ isStateRefreshDue()

◆ movingAverage()

◆ scaleLoads()

◆ setLogger()

◆ setMockTime()

◆ setStatsdDataFactory()

Member Data Documentation

◆ $lb

◆ $logger

◆ $srvCache

◆ $statsd

◆ $wanCache