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

Inherited by Wikimedia\Rdbms\LoadMonitorNull.

Collaboration diagram for Wikimedia\Rdbms\LoadMonitor:

[legend]

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

	getLagTimes (array $serverIndexes)
	Get an estimate of replication lag (in seconds) for the specified servers.

	getServerStates (array $serverIndexes)
	Get a server gauge map for the specified servers.

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

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

	setLogger (LoggerInterface $logger)

	setMockTime (&$time)

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

Protected Member Functions
	computeServerState (int $i, ?array $priorState)

	getCurrentTime ()

	getWeightScale (array $state)

	isStateFresh ( $state, $now)

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

	makeStateKey (IStoreKeyEncoder $cache, int $i)

	newInitialServerState ()

Protected Attributes
ILoadBalancer	$lb

LoggerInterface	$logger

BagOStuff	$srvCache

StatsdDataFactoryInterface	$statsd

WANObjectCache	$wanCache

Additional Inherited Members
Public Attributes inherited from Wikimedia\Rdbms\ILoadMonitor
const	STATE_AS_OF = 'time'

const	STATE_GEN_DELAY = 'delay'

const	STATE_LAG = 'lag'

const	STATE_UP = 'up'

Detailed Description

Basic DB load monitor with no external dependencies.

This uses both local server and local datacenter caches for DB 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 42 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: .8] lagWarnThreshold: how many seconds of lag trigger warnings [default: 10]

Implements Wikimedia\Rdbms\ILoadMonitor.

Definition at line 82 of file LoadMonitor.php.

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

Member Function Documentation

◆ computeServerState()

Wikimedia\Rdbms\LoadMonitor::computeServerState	(	int	$i,
		?array	$priorState
	)

protected

Parameters

int	$i
array \| null	$priorState

Returns: array<string,mixed>

Exceptions

DBAccessError

Definition at line 219 of file LoadMonitor.php.

◆ getCurrentTime()

Wikimedia\Rdbms\LoadMonitor::getCurrentTime ( )

protected

Returns: float UNIX timestamp

Definition at line 420 of file LoadMonitor.php.

◆ getLagTimes()

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

final

Get an estimate of replication lag (in seconds) for the specified servers.

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 116 of file LoadMonitor.php.

◆ getServerStates()

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

Get a server gauge map for the specified servers.

Parameters

int[] $serverIndexes

Returns: array<int,array>

Implements Wikimedia\Rdbms\ILoadMonitor.

Reimplemented in Wikimedia\Rdbms\LoadMonitorNull.

Definition at line 127 of file LoadMonitor.php.

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

◆ getWeightScale()

Wikimedia\Rdbms\LoadMonitor::getWeightScale ( array $state )

protected

Parameters

array $state

Returns: float

Definition at line 308 of file LoadMonitor.php.

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

◆ isStateFresh()

Wikimedia\Rdbms\LoadMonitor::isStateFresh	(	$state,
		$now
	)

protected

Parameters

array \| null	$state
float	$now

Returns: bool

Definition at line 335 of file LoadMonitor.php.

◆ isStateRefreshDue()

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

protected

Parameters

float	$priorAsOf
float	$priorGenDelay
float \| int	$referenceTTL
float	$now

Returns: bool

Definition at line 354 of file LoadMonitor.php.

◆ makeStateKey()

Wikimedia\Rdbms\LoadMonitor::makeStateKey	(	IStoreKeyEncoder	$cache,
		int	$i
	)

protected

Definition at line 202 of file LoadMonitor.php.

References IStoreKeyEncoder\makeGlobalKey().

◆ 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 377 of file LoadMonitor.php.

◆ newInitialServerState()

Wikimedia\Rdbms\LoadMonitor::newInitialServerState ( )

protected

Returns: array<string,mixed>

Definition at line 317 of file LoadMonitor.php.

◆ 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 102 of file LoadMonitor.php.

References Wikimedia\Rdbms\LoadMonitor\getServerStates(), and Wikimedia\Rdbms\LoadMonitor\getWeightScale().

◆ setLogger()

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

Definition at line 94 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 98 of file LoadMonitor.php.

Member Data Documentation

◆ $lb

ILoadBalancer Wikimedia\Rdbms\LoadMonitor::$lb

protected

Definition at line 44 of file LoadMonitor.php.

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

◆ $logger

LoggerInterface Wikimedia\Rdbms\LoadMonitor::$logger

protected

Definition at line 50 of file LoadMonitor.php.

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

◆ $srvCache

BagOStuff Wikimedia\Rdbms\LoadMonitor::$srvCache

protected

Definition at line 46 of file LoadMonitor.php.

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

◆ $statsd

StatsdDataFactoryInterface Wikimedia\Rdbms\LoadMonitor::$statsd

protected

Definition at line 52 of file LoadMonitor.php.

◆ $wanCache

WANObjectCache Wikimedia\Rdbms\LoadMonitor::$wanCache

protected

Definition at line 48 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

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ __construct()

Member Function Documentation

◆ computeServerState()

◆ getCurrentTime()

◆ getLagTimes()

◆ getServerStates()

◆ getWeightScale()

◆ isStateFresh()

◆ isStateRefreshDue()

◆ makeStateKey()

◆ movingAverage()

◆ newInitialServerState()

◆ scaleLoads()

◆ setLogger()

◆ setMockTime()

◆ setStatsdDataFactory()

Member Data Documentation

◆ $lb

◆ $logger

◆ $srvCache

◆ $statsd

◆ $wanCache