An interface for generating database load balancers. More...

Inheritance diagram for ILBFactory:

Public Member Functions
	__construct (array $conf)
	Construct a manager of ILoadBalancer objects. More...

	appendPreShutdownTimeAsQuery ($url, $time)
	Append ?cpPosTime parameter to a URL for ChronologyProtector purposes if needed. More...

	beginMasterChanges ($fname=__METHOD__)
	Flush any master transaction snapshots and set DBO_TRX (if DBO_DEFAULT is set) More...

	closeAll ()
	Close all open database connections on all open load balancers. More...

	commitAll ($fname=__METHOD__, array $options=[])
	Commit open transactions on all connections. More...

	commitAndWaitForReplication ($fname, $ticket, array $opts=[])
	Convenience method for safely running commitMasterChanges()/waitForReplication() More...

	commitMasterChanges ($fname=__METHOD__, array $options=[])
	Commit changes on all master connections. More...

	destroy ()
	Disables all load balancers. More...

	disableChronologyProtection ()
	Disable the ChronologyProtector for all load balancers. More...

	flushReplicaSnapshots ($fname=__METHOD__)
	Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshot. More...

	forEachLB ($callback, array $params=[])
	Execute a function for each tracked load balancer The callback is called with the load balancer as the first parameter, and $params passed as the subsequent parameters. More...

	getChronologyProtectorTouched ($dbName)

	getEmptyTransactionTicket ($fname)
	Get a token asserting that no transaction writes are active. More...

	getExternalLB ($cluster)
	Get a cached (tracked) load balancer for external storage. More...

	getMainLB ($domain=false)
	Get a cached (tracked) load balancer object. More...

	hasMasterChanges ()
	Determine if any master connection has pending changes. More...

	hasOrMadeRecentMasterChanges ($age=null)
	Determine if any master connection has pending/written changes from this request. More...

	laggedReplicaUsed ()
	Detemine if any lagged replica DB connection was used. More...

	newExternalLB ($cluster)
	Create a new load balancer for external storage. More...

	newMainLB ($domain=false)
	Create a new load balancer object. More...

	rollbackMasterChanges ($fname=__METHOD__)
	Rollback changes on all master connections. More...

	setAgentName ($agent)

	setDomainPrefix ($prefix)
	Set a new table prefix for the existing local domain ID for testing. More...

	setRequestInfo (array $info)

	setWaitForReplicationListener ($name, callable $callback=null)
	Add a callback to be run in every call to waitForReplication() before waiting. More...

	shutdown ($mode=self::SHUTDOWN_CHRONPROT_SYNC, callable $workCallback=null)
	Prepare all tracked load balancers for shutdown. More...

	waitForReplication (array $opts=[])
	Waits for the replica DBs to catch up to the current master position. More...

Public Attributes
const	SHUTDOWN_CHRONPROT_ASYNC = 1

const	SHUTDOWN_CHRONPROT_SYNC = 2

const	SHUTDOWN_NO_CHRONPROT = 0

Detailed Description

An interface for generating database load balancers.

Since: 1.28

Definition at line 29 of file ILBFactory.php.

Constructor & Destructor Documentation

ILBFactory::__construct ( array $conf )

Construct a manager of ILoadBalancer objects.

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

Parameters

$conf

$params Array with keys:

localDomain: A DatabaseDomain or domain ID string.
readOnlyReason : Reason the master DB is read-only if so [optional]
srvCache : BagOStuff object for server cache [optional]
memCache : BagOStuff object for cluster memory cache [optional]
wanCache : WANObjectCache object [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]

Exceptions

InvalidArgumentException

Implemented in LBFactoryMulti, LBFactory, LBFactorySimple, and LBFactorySingle.

Member Function Documentation

ILBFactory::appendPreShutdownTimeAsQuery	(	$url,
		$time
	)

Append ?cpPosTime parameter to a URL for ChronologyProtector purposes if needed.

Note that unlike cookies, this works accross domains

Parameters

string	$url
float	$time	UNIX timestamp just before shutdown() was called

Returns: string

Implemented in LBFactory.

ILBFactory::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:

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

Parameters

string $fname

Exceptions

DBTransactionError

Implemented in LBFactory.

ILBFactory::closeAll ( )

Close all open database connections on all open load balancers.

Implemented in LBFactory.

ILBFactory::commitAll	(		$fname = `__METHOD__`,
		array	$options = `[]`
	)

Commit open transactions on all connections.

This is useful for two main cases:

a) To commit changes to the masters.
b) To release the snapshot on all connections, master and replica DBs.
Parameters

string $fname Caller name

array $options Options map:
maxWriteDuration: abort if more than this much time was spent in write queries

Implemented in LBFactory.

ILBFactory::commitAndWaitForReplication	(		$fname,
			$ticket,
		array	$opts = `[]`
	)

Convenience method for safely running commitMasterChanges()/waitForReplication()

This will commit and wait unless $ticket indicates it is unsafe to do so

Parameters

string	$fname	Caller name (e.g. METHOD)
mixed	$ticket	Result of getEmptyTransactionTicket()
array	$opts	Options to waitForReplication()

Exceptions

DBReplicationWaitError

Implemented in LBFactory.

ILBFactory::commitMasterChanges	(		$fname = `__METHOD__`,
		array	$options = `[]`
	)

Commit changes on all master connections.

Parameters

string	$fname	Caller name
array	$options	Options map: maxWriteDuration: abort if more than this much time was spent in write queries

Exceptions

Exception

Implemented in LBFactory.

ILBFactory::destroy ( )

Disables all load balancers.

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

See also: ILoadBalancer::disable()

Implemented in LBFactory.

ILBFactory::disableChronologyProtection ( )

Disable the ChronologyProtector for all load balancers.

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

Implemented in LBFactory.

ILBFactory::flushReplicaSnapshots ( $fname = __METHOD__ )

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

Parameters

string $fname Caller name

Implemented in LBFactory.

ILBFactory::forEachLB	(		$callback,
		array	$params = `[]`
	)

Execute a function for each tracked load balancer The callback is called with the load balancer as the first parameter, and $params passed as the subsequent parameters.

Parameters

callable	$callback
array	$params

Implemented in LBFactoryMulti, LBFactorySimple, and LBFactorySingle.

Referenced by LBFactory\appendPreShutdownTimeAsQuery(), LBFactory\commitMasterChanges(), LBFactory\forEachLBCallMethod(), LBFactory\hasMasterChanges(), LBFactory\hasOrMadeRecentMasterChanges(), LBFactory\laggedReplicaUsed(), LBFactory\logIfMultiDbTransaction(), LBFactory\rollbackMasterChanges(), LBFactory\setDomainPrefix(), LBFactory\shutdownChronologyProtector(), and LBFactory\waitForReplication().

ILBFactory::getChronologyProtectorTouched ( $dbName )

Parameters

string $dbName DB master name (e.g. "db1052")

Returns: float|bool UNIX timestamp when client last touched the DB or false if not recent

Implemented in LBFactory.

ILBFactory::getEmptyTransactionTicket ( $fname )

Get a token asserting that no transaction writes are active.

Parameters

string $fname Caller name (e.g. METHOD)

Returns: mixed A value to pass to commitAndWaitForReplication()

Implemented in LBFactory.

ILBFactory::getExternalLB ( $cluster )

Get a cached (tracked) load balancer for external storage.

Parameters

string $cluster External storage cluster name

Returns: ILoadBalancer

Implemented in LBFactoryMulti, LBFactory, LBFactorySimple, and LBFactorySingle.

ILBFactory::getMainLB ( $domain = false )

Get a cached (tracked) load balancer object.

Parameters

bool | string $domain Domain ID, or false for the current domain

Returns: ILoadBalancer

Implemented in LBFactoryMulti, LBFactory, LBFactorySimple, and LBFactorySingle.

ILBFactory::hasMasterChanges ( )

Determine if any master connection has pending changes.

Returns: bool

Implemented in LBFactory.

ILBFactory::hasOrMadeRecentMasterChanges ( $age = null )

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

Parameters

float $age How many seconds ago is "recent" [defaults to LB lag wait timeout]

Returns: bool

Implemented in LBFactory.

ILBFactory::laggedReplicaUsed ( )

Detemine if any lagged replica DB connection was used.

Returns: bool

Implemented in LBFactory.

ILBFactory::newExternalLB ( $cluster )

Create a new load balancer for external storage.

The resulting object will be untracked, not chronology-protected, and the caller is responsible for cleaning it up.

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

Parameters

string $cluster External storage cluster name

Returns: ILoadBalancer

Implemented in LBFactoryMulti, LBFactory, LBFactorySimple, and LBFactorySingle.

ILBFactory::newMainLB ( $domain = false )

Create a new load balancer object.

The resulting object will be untracked, not chronology-protected, and the caller is responsible for cleaning it up.

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

Parameters

bool | string $domain Domain ID, or false for the current domain

Returns: ILoadBalancer

Implemented in LBFactoryMulti, LBFactory, LBFactorySimple, and LBFactorySingle.

ILBFactory::rollbackMasterChanges ( $fname = __METHOD__ )

Rollback changes on all master connections.

Parameters

string $fname Caller name

Implemented in LBFactory.

ILBFactory::setAgentName ( $agent )

Parameters

string $agent Agent name for query profiling

Implemented in LBFactory.

ILBFactory::setDomainPrefix ( $prefix )

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

Parameters

string $prefix

Implemented in LBFactory.

ILBFactory::setRequestInfo ( array $info )

Parameters

array

$info

Map of fields, including:

IPAddress : IP address
UserAgent : User-Agent HTTP header
ChronologyProtection : cookie/header value specifying ChronologyProtector usage

Implemented in LBFactory.

ILBFactory::setWaitForReplicationListener	(		$name,
		callable	$callback = `null`
	)

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

Callbacks must clear any transactions that they start

Parameters

string	$name	Callback name
callable \| null	$callback	Use null to unset a callback

Implemented in LBFactory.

ILBFactory::shutdown	(		$mode = `self::SHUTDOWN_CHRONPROT_SYNC`,
		callable	$workCallback = `null`
	)

Prepare all tracked load balancers for shutdown.

Parameters

integer	$mode	One of the class SHUTDOWN_* constants
callable \| null	$workCallback	Work to mask ChronologyProtector writes

Implemented in LBFactory.

ILBFactory::waitForReplication ( array $opts = [] )

Waits for the replica DBs to catch up to the current master position.

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

By default this waits on all DB clusters actually used in this request. This makes sense when lag being waiting on is caused by the code that does this check. In that case, setting "ifWritesSince" can avoid the overhead of waiting for clusters that were not changed since the last wait check. To forcefully wait on a specific cluster for a given domain, use the 'domain' parameter. To forcefully wait on an "external" cluster, use the "cluster" parameter.

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

Parameters

array

$opts

Optional fields that include:

domain : wait on the load balancer DBs that handles the given domain ID
cluster : wait on the given external load balancer DBs
timeout : Max wait time. Default: ~60 seconds
ifWritesSince: Only wait if writes were done since this UNIX timestamp

Exceptions

DBReplicationWaitError If a timeout or error occured waiting on a DB cluster

Implemented in LBFactory.

Member Data Documentation

const ILBFactory::SHUTDOWN_CHRONPROT_ASYNC = 1

Definition at line 31 of file ILBFactory.php.

const ILBFactory::SHUTDOWN_CHRONPROT_SYNC = 2

Definition at line 32 of file ILBFactory.php.

const ILBFactory::SHUTDOWN_NO_CHRONPROT = 0

Definition at line 30 of file ILBFactory.php.

Referenced by MediaWiki\restInPeace().

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

includes/libs/rdbms/lbfactory/ILBFactory.php

Public Member Functions

Public Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation