Wikimedia\Rdbms\LoadBalancerSingle Class Reference

Trivial LoadBalancer that always returns an injected connection handle. More...

Inherits Wikimedia\Rdbms\LoadBalancer.

Collaboration diagram for Wikimedia\Rdbms\LoadBalancerSingle:

Public Member Functions
	__construct (array $params)
	You probably want to use newFromConnection instead.
	__destruct ()
Public Member Functions inherited from Wikimedia\Rdbms\LoadBalancer
	approvePrimaryChanges (int $maxWriteDuration, $fname=__METHOD__)
	Perform all pre-commit checks for things like replication safety.Use this only for multi-database commits Parameters int $maxWriteDuration : max write query duration time in seconds string $fname Caller name Exceptions DBTransactionError Since 1.37
	beginPrimaryChanges ( $fname=__METHOD__)
	Flush any primary 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: commitPrimaryChanges() rollbackPrimaryChanges() This allows for custom transaction rounds from any outer transaction scope. Parameters string $fname Caller name Exceptions DBExpectedError Since 1.37
	closeAll ( $fname=__METHOD__)
	Close all open connections. Parameters string $fname Caller name
	commitPrimaryChanges ( $fname=__METHOD__)
	Issue COMMIT on all open primary connections to flush changes and view snapshots. Parameters string $fname Caller name Exceptions DBExpectedError Since 1.37
	disable ( $fname=__METHOD__)
	Close all connections and disable this load balancer.Any attempt to open a new connection will result in a DBAccessError. Parameters string $fname Caller name
	explicitTrxActive ()
	Determine whether an explicit transaction is active on any open primary connection. Returns bool Since 1.39
	finalizePrimaryChanges ( $fname=__METHOD__)
	Run pre-commit callbacks and defer execution of post-commit callbacks.Use this only for multi-database commits Parameters string $fname Caller name Returns int Number of pre-commit callbacks run (since 1.32) Since 1.37
	flushPrimarySessions ( $fname=__METHOD__)
	Release/destroy session-level named locks, table locks, and temp tables.Only call this function right after calling rollbackPrimaryChanges() Parameters string $fname Caller name Exceptions DBExpectedError Since 1.38
	flushPrimarySnapshots ( $fname=__METHOD__)
	Commit all primary 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 $fname Caller name Since 1.37
	flushReplicaSnapshots ( $fname=__METHOD__)
	Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshots. Parameters string $fname Caller name
	getAnyOpenConnection ( $i, $flags=0)
	getClusterName ()
	Get the name of the overall cluster of database servers managing the dataset.
	getConnection ( $i, $groups=[], string|false $domain=false, $flags=0)
	Get a lazy-connecting database handle for a specific or virtual (DB_PRIMARY/DB_REPLICA) server index.The server index, $i, can be one of the following: DB_REPLICA: a server index will be selected by the load balancer based on read weight, connectivity, and replication lag. Note that the primary server might be configured with read weight. If $groups is empty then it means "the generic group", in which case all servers defined with read weight will be considered. Additional query groups can be configured, having their own list of server indexes and read weights. If a query group list is provided in $groups, then each recognized group will be tried, left-to-right, until server index selection succeeds or all groups have been tried, in which case the generic group will be tried. DB_PRIMARY: the primary server index will be used; the same as ServerInfo::WRITER_INDEX. The value of $groups should be [] when using this server index. Specific server index: a positive integer can be provided to use the server with that index. An error will be thrown in no such server index is recognized. This server selection method is usually only useful for internal load balancing logic. The value of $groups should be [] when using a specific server index. Handle sharing is very useful when callers get DB_PRIMARY handles that are transaction round aware (the default). All such callers will operate within a single transaction as a consequence. The same applies to DB_REPLICA that are samely query grouped (the default) and transaction round aware (the default).Use CONN_TRX_AUTOCOMMIT to use a separate pool of only autocommit handles. This flag is ignored for databases with ATTR_DB_LEVEL_LOCKING (e.g. sqlite) in order to avoid deadlocks. getServerAttributes() can be used to check this attribute beforehand. Avoid using begin() and commit() on such handles. If handle methods like startAtomic() and endAtomic() must be used on the handles, callers should at least make sure that the atomic sections are closed on failure via try/catch and cancelAtomic().Use CONN_UNTRACKED_GAUGE to get a new, untracked, handle, that uses a low connection timeout, a low read timeout, and autocommit mode. This flag is intended for use only be internal callers.CONN_UNTRACKED_GAUGE and CONN_TRX_AUTOCOMMIT are incompatible. See also ILoadBalancer::getServerAttributes() Parameters int $i Specific (overrides $groups) or virtual (DB_PRIMARY/DB_REPLICA) server index string[] | string $groups Query group(s) in preference order; [] for the default group string | false $domain DB domain ID or false for the local domain int $flags Bitfield of CONN_* class constants Returns IDatabase|false This returns false on failure if CONN_SILENCE_ERRORS is set
	getConnectionInternal ( $i, $groups=[], $domain=false, $flags=0)
	Access: internal Only to be used by DBConnRef Parameters int $i Specific (overrides $groups) or virtual (DB_PRIMARY/DB_REPLICA) server index string[] | string $groups Query group(s) in preference order; [] for the default group string | false $domain DB domain ID or false for the local domain int $flags Bitfield of CONN_* class constants (e.g. CONN_TRX_AUTOCOMMIT) Returns IDatabase
	getLagTimes ()
	Get an estimate of replication lag (in seconds) for each server.Results are cached for a short time in memcached/process cacheValues may be "false" if replication is too broken to estimate Returns float[]|int[]|false[] Map of (server index => lag) in order of server index
	getLocalDomainID ()
	Get the local (and default) database domain ID of connection handles.
	getMaintenanceConnectionRef ( $i, $groups=[], $domain=false, $flags=0)
	Get a DB handle, suitable for migrations and schema changes, for a server index.The DBConnRef methods simply proxy an underlying IDatabase object which takes care of the actual connection and query logic.The CONN_TRX_AUTOCOMMIT flag is ignored for databases with ATTR_DB_LEVEL_LOCKING (e.g. sqlite) in order to avoid deadlocks. 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 $i Specific or virtual (DB_PRIMARY/DB_REPLICA) server index string[] | string $groups Query group(s) in preference order; [] for the default group string | false $domain DB domain ID or false for the local domain int $flags Bitfield of CONN_* class constants (e.g. CONN_TRX_AUTOCOMMIT) Returns DBConnRef
	getMaxLag ()
	Get the name and lag time of the most-lagged replica server.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. Returns array{0:string,1:float|int|false,2:int} (host, max lag, index of max lagged host)
	getPrimaryPos ()
	Get the current primary replication position. Returns DBPrimaryPos|false Returns false if not applicable Exceptions DBError Since 1.37
	getReaderIndex ( $group=false)
	Get the specific server index of the reader connection for a given group.This takes into account load ratios and lag times. It should return a consistent index during the life time of the load balancer. This initially checks replica DBs for connectivity to avoid returning an unusable server. This means that connections might be attempted by calling this method (usually one at the most but possibly more). Subsequent calls with the same $group will not need to make new connection attempts since the acquired connection for each group is preserved. Parameters string | false | string[] $group Query group or false for the generic group Returns int|false Specific server index, or false if no DB handle can be obtained
	getReadOnlyReason ()
	Note This method may trigger a DB connection if not yet done Returns string|false Reason the primary is read-only or false if it is not
	getServerAttributes ( $i)
	Get basic attributes of the server with the specified index without connecting. Parameters int $i Specific server index Returns array (Database::ATTRIBUTE_* constant => value) for all such constants Since 1.31
	getServerConnection ( $i, $domain, $flags=0)
	Get a DB handle for a specific server index.This is an internal utility method for methods like LoadBalancer::getConnectionInternal() and DBConnRef to create the underlying connection to a concrete server.The following is the responsibility of the caller: translate any virtual server indexes (DB_PRIMARY/DB_REPLICA) to a real server index. enforce read-only mode on primary DB handle if there is high replication lag. See also ILoadBalancer::getConnection() Access: internal Only for use within ILoadBalancer/ILoadMonitor Parameters int $i Specific server index string $domain Resolved DB domain int $flags Bitfield of class CONN_* constants Returns IDatabaseForOwner|false This returns false on failure if CONN_SILENCE_ERRORS is set Exceptions DBError If no DB handle could be obtained and CONN_SILENCE_ERRORS is not set
	getServerCount ()
	Get the number of servers defined in configuration. Returns int
	getServerInfo ( $i)
	Return the server configuration map for the server with the specified index. Parameters int $i Specific server index Returns array|false Server configuration map; false if the index is invalid Since 1.31
	getServerName ( $i)
	Get the readable name of the server with the specified index. Parameters int $i Specific server index Returns string Readable server name, falling back to the hostname or IP address
	getServerType ( $i)
	Get the RDBMS type of the server with the specified index (e.g."mysql", "sqlite") Parameters int $i Specific server index Returns string One of (mysql,postgres,sqlite,...) or "unknown" for bad indexes Since 1.30
	hasOrMadeRecentPrimaryChanges ( $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 $age How many seconds ago is "recent" [defaults to mWaitTimeout] Returns bool Since 1.37
	hasPrimaryChanges ()
	Whether there are pending changes or callbacks in a transaction by this thread. Returns bool Since 1.37
	hasPrimaryConnection ()
	Returns bool Whether a primary connection is already open Since 1.37
	hasReplicaServers ()
	Whether there are any replica servers configured.This scans the list of servers defined in configuration, checking for: Servers that are listed after the primary and not flagged with "is static"; such servers are assumed to be typical streaming replicas Servers that are listed after the primary and flagged with "is static"; such servers are assumed to have a clone of the static dataset (matching the primary) Returns bool Since 1.34
	hasStreamingReplicaServers ()
	Whether any replica servers use streaming replication from the primary server.This scans the list of servers defined in configuration, checking for: Servers that are listed after the primary and not flagged with "is static"; such servers are assumed to be typical streaming replicas It is possible for some replicas to be configured with "is static" but not others, though it generally should either be set for all or none of the replicas.If this returns false, this means that there is generally no reason to execute replication wait logic for session consistency and lag reduction. Returns bool Since 1.34
	laggedReplicaUsed ()
	Whether a highly "lagged" replica database connection was queried. Note This method will never cause a new DB connection Returns bool
	lastPrimaryChangeTimestamp ()
	Get the last time that a tracked connection was used to commit a write. Access: internal Should only be called from the rdbms library. Returns float|null UNIX timestamp, or, false (if no writes were committed) Since 1.37
	pendingPrimaryChangeCallers ()
	Get the list of callers that have pending primary changes. Returns string[] List of method names Since 1.37
	pingAll ()
	Returns bool
	reconfigure (array $params)
	Apply updated configuration.
	redefineLocalDomain ( $domain)
	Close all connection and redefine the local domain for testing or schema creation. Parameters DatabaseDomain | string $domain Since 1.33
	resolveDomainID (DatabaseDomain|string|false $domain)
	Parameters DatabaseDomain | string | false $domain Database domain Returns string Value of $domain if it is foreign or the local domain otherwise Since 1.32
	rollbackPrimaryChanges ( $fname=__METHOD__)
	Issue ROLLBACK only on primary, only if queries were done on connection. Parameters string $fname Caller name Exceptions DBExpectedError Since 1.37
	runPrimaryTransactionIdleCallbacks ( $fname=__METHOD__)
	Consume and run all pending post-COMMIT/ROLLBACK callbacks and commit dangling transactions. Parameters string $fname Caller name Returns Exception|null The first exception or null if there were none Since 1.37
	runPrimaryTransactionListenerCallbacks ( $fname=__METHOD__)
	Run all recurring post-COMMIT/ROLLBACK listener callbacks. Parameters string $fname Caller name Returns Exception|null The first exception or null if there were none Since 1.37
	setDefaultGroupName (string $defaultGroup)
	Set the default group name for all load balancers.
	setDomainAliases (array $aliases)
	Convert certain database domains to alternative ones.
	setLocalDomainPrefix ( $prefix)
	Set a new table prefix for the existing local domain ID for testing. Parameters string $prefix Since 1.33
	setMockTime (&$time)
	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.
	setTempTablesOnlyMode ( $value, $domain)
	Indicate whether the tables on this domain are only temporary tables for testing.In "temporary tables mode", the CONN_TRX_AUTOCOMMIT flag is ignored Parameters bool $value string $domain Returns bool Whether "temporary tables mode" was active Since 1.34
	setTransactionListener ( $name, ?callable $callback=null)
	Set a callback via IDatabase::setTransactionListener() on all current and future primary connections of this load balancer. Parameters string $name Callback name callable | null $callback Deprecated Since 1.44
	waitForAll (DBPrimaryPos $pos, $timeout=null)
	Set the primary wait position and wait for ALL replica DBs to catch up to it.This method is only intended for use a throttling mechanism for high-volume updates. Unlike waitFor(), failure does not effect laggedReplicaUsed(). Parameters DBPrimaryPos $pos Primary position int | null $timeout Max seconds to wait; default is mWaitTimeout Returns bool Success (able to connect and no timeouts reached)
	waitForPrimaryPos (IDatabase $conn)
	Wait for a replica DB to reach a specified primary position.If $conn is not a replica server connection, then this will return true. Otherwise, if $pos is not provided, this will connect to the primary server to get an accurate position. Parameters IDatabase $conn Replica DB Returns bool Success Since 1.37

Static Public Member Functions
static	newFromConnection (IDatabase $db, array $params=[])

Protected Member Functions
	reallyOpenConnection ( $i, DatabaseDomain $domain, array $lbInfo)
	Open a new network connection to a server (uncached)Returns a Database object whether or not the connection was successful. Parameters int $i Specific server index DatabaseDomain $domain Domain the connection is for, possibly unspecified array $lbInfo Additional information for setLBInfo() Returns Database Exceptions DBAccessError InvalidArgumentException
	sanitizeConnectionFlags ( $flags, $domain)
	Sanitize connection flags provided by a call to getConnection() Parameters int $flags Bitfield of class CONN_* constants string $domain Database domain Returns int Sanitized bitfield
Protected Member Functions inherited from Wikimedia\Rdbms\LoadBalancer
	configure (array $params)
	getConnLogContext (IDatabase $conn, array $extras=[])
	Create a log context to pass to PSR-3 logger functions.
	getExistingReaderIndex ( $group)
	Get the server index chosen for DB_REPLICA connections for the given query group.
	resolveDomainInstance (DatabaseDomain|string|false $domain)

Additional Inherited Members
Public Attributes inherited from Wikimedia\Rdbms\ILoadBalancerForOwner
const	STAGE_POSTCOMMIT_CALLBACKS = 'stage-postcommit-callbacks'
	Manager of ILoadBalancer instances is running post-commit callbacks.
const	STAGE_POSTROLLBACK_CALLBACKS = 'stage-postrollback-callbacks'
	Manager of ILoadBalancer instances is running post-rollback callbacks.
Public Attributes inherited from Wikimedia\Rdbms\ILoadBalancer
const	CONN_SILENCE_ERRORS = 4
	Yield null on connection failure instead of throwing an exception.
const	CONN_TRX_AUTOCOMMIT = 1
	Yield a tracked autocommit-mode handle (reuse existing ones)
const	CONN_UNTRACKED_GAUGE = 2
	Yield an untracked, low-timeout, autocommit-mode handle (to gauge server health)
const	DB_PRIMARY = -2
	Request a primary, write-enabled DB connection.
const	DB_REPLICA = -1
	Request a replica DB connection.
const	DOMAIN_ANY = ''
	Domain specifier when no specific database needs to be selected.
const	GROUP_GENERIC = ''
	The generic query group.

Detailed Description

Trivial LoadBalancer that always returns an injected connection handle.

Definition at line 15 of file LoadBalancerSingle.php.

Constructor & Destructor Documentation

__construct()

Wikimedia\Rdbms\LoadBalancerSingle::__construct

(

array

$params

)

You probably want to use newFromConnection instead.

Parameters

array

$params

An associative array with one member: connection: An IDatabase connection object

Reimplemented from Wikimedia\Rdbms\LoadBalancer.

Definition at line 25 of file LoadBalancerSingle.php.

References Wikimedia\Rdbms\Database\getDBname(), Wikimedia\Rdbms\Database\getServer(), Wikimedia\Rdbms\IReadableDatabase\getType(), and Wikimedia\Rdbms\Database\setLBInfo().

__destruct()

Wikimedia\Rdbms\LoadBalancerSingle::__destruct

(

)

Definition at line 86 of file LoadBalancerSingle.php.

Member Function Documentation

newFromConnection()

static Wikimedia\Rdbms\LoadBalancerSingle::newFromConnection ( IDatabase $db, array $params = [] )

static

Parameters

IDatabase	$db	Live connection handle
array	$params	Parameter map to LoadBalancerSingle::__constructs()

Since

1.28

Definition at line 59 of file LoadBalancerSingle.php.

reallyOpenConnection()

Wikimedia\Rdbms\LoadBalancerSingle::reallyOpenConnection ( $i, DatabaseDomain $domain, array $lbInfo )

protected

Open a new network connection to a server (uncached)Returns a Database object whether or not the connection was successful.

Parameters

int	$i	Specific server index
DatabaseDomain	$domain	Domain the connection is for, possibly unspecified
array	$lbInfo	Additional information for setLBInfo()

Returns

Database

Exceptions

DBAccessError
InvalidArgumentException

Reimplemented from Wikimedia\Rdbms\LoadBalancer.

Definition at line 78 of file LoadBalancerSingle.php.

sanitizeConnectionFlags()

Wikimedia\Rdbms\LoadBalancerSingle::sanitizeConnectionFlags ( $flags, $domain )

protected

Sanitize connection flags provided by a call to getConnection()

Parameters

int	$flags	Bitfield of class CONN_* constants
string	$domain	Database domain

Returns

int Sanitized bitfield

Reimplemented from Wikimedia\Rdbms\LoadBalancer.

Definition at line 68 of file LoadBalancerSingle.php.

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

• includes/libs/Rdbms/LoadBalancer/LoadBalancerSingle.php