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Manager of ILoadBalancer objects and, indirectly, IDatabase connections. More...
Inherits Wikimedia\Rdbms\IConnectionProvider.
Inherited by Wikimedia\Rdbms\LBFactory.
Public Member Functions | |
__construct (array $conf) | |
Sub-classes may extend the required keys in $conf with additional parameters. | |
autoReconfigure () | |
Reload the configuration if necessary. | |
beginPrimaryChanges ( $fname=__METHOD__) | |
Wrap subsequent queries for all transaction round aware primary connections in a transaction. | |
closeAll ( $fname=__METHOD__) | |
Close all connections on instantiated tracked load balancer instances. | |
commitPrimaryChanges ( $fname=__METHOD__, int $maxWriteDuration=0) | |
Commit all primary connection transactions and flush all replica connection transactions. | |
destroy () | |
Close all connections and make further attempts to open connections result in DBAccessError. | |
disableChronologyProtection () | |
Disable the ChronologyProtector on all instantiated tracked load balancer instances. | |
flushPrimarySessions ( $fname=__METHOD__) | |
Release important session-level state (named lock, table locks) as post-rollback cleanup. | |
flushReplicaSnapshots ( $fname=__METHOD__) | |
Commit all replica database server transactions, clearing any point-in-time view snapshots. | |
getAllExternalLBs () | |
Get the tracked load balancer instances for all external clusters. | |
getAllLBs () | |
Get all tracked load balancer instances (generator) | |
getAllMainLBs () | |
Get the tracked load balancer instances for all main clusters. | |
getExternalLB ( $cluster) | |
Get the tracked load balancer instance for an external cluster. | |
getLoadBalancer ( $domain=false) | |
Get the tracked load balancer instance for a given domain. | |
getLocalDomainID () | |
Get the local (and default) database domain ID of connection handles. | |
getMainLB ( $domain=false) | |
Get the tracked load balancer instance for the main cluster that handles the given domain. | |
getTransactionProfiler () | |
Get the TransactionProfiler used by this instance. | |
hasOrMadeRecentPrimaryChanges ( $age=null) | |
Determine if any primary connection has pending/written changes from this request. | |
hasPrimaryChanges () | |
Determine if any primary connection has pending changes. | |
hasStreamingReplicaServers () | |
Whether it has streaming replica servers. | |
hasTransactionRound () | |
Check if an explicit transaction round is active. | |
isReadyForRoundOperations () | |
Check if transaction rounds can be started, committed, or rolled back right now. | |
laggedReplicaUsed () | |
Determine if any lagged replica database server connection was used. | |
newExternalLB ( $cluster) | |
Create a new load balancer instance for an external cluster. | |
newMainLB ( $domain=false) | |
Create a new load balancer instance for the main cluster that handles the given domain. | |
redefineLocalDomain ( $domain) | |
Close all connections and redefine the local database domain. | |
rollbackPrimaryChanges ( $fname=__METHOD__) | |
Rollback all primary connection transactions and flush all replica connection transactions. | |
setAgentName ( $agent) | |
setDefaultReplicationWaitTimeout ( $seconds) | |
Set the default timeout for replication wait checks. | |
setDomainAliases (array $aliases) | |
Convert certain database domains to alternative ones. | |
setIndexAliases (array $aliases) | |
Convert certain index names to alternative names before querying the DB. | |
setLocalDomainPrefix ( $prefix) | |
Set a new table prefix for the existing local domain ID for testing. | |
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. | |
setWaitForReplicationListener ( $name, ?callable $callback=null) | |
Add a callback to be run in every call to waitForReplication() prior to any waiting. | |
shutdown ( $flags=self::SHUTDOWN_NORMAL, ?callable $workCallback=null, &$cpIndex=null, &$cpClientId=null) | |
Prepare all instantiated tracked load balancer instances for shutdown. | |
waitForReplication (array $opts=[]) | |
Waits for the replica database server to catch up to the current primary position. | |
Public Member Functions inherited from Wikimedia\Rdbms\IConnectionProvider | |
commitAndWaitForReplication ( $fname, $ticket, array $opts=[]) | |
Commit primary DB transactions and wait for replication (if $ticket indicates it is safe). | |
getEmptyTransactionTicket ( $fname) | |
Get a token asserting that no write transactions are active on tracked connections. | |
getPrimaryDatabase ( $domain=false) | |
Get connection to the primary database. | |
getReplicaDatabase ( $domain=false, $group=null) | |
Get connection to a replica database. | |
Public Attributes | |
const | SHUTDOWN_NO_CHRONPROT = 1 |
Do not save "session consistency" DB replication positions. | |
const | SHUTDOWN_NORMAL = 0 |
Idiom for "no special shutdown flags". | |
Manager of ILoadBalancer objects and, indirectly, IDatabase connections.
Each Load balancer instances corresponds to a specific database cluster. A "cluster" is the set of database servers that manage a given dataset.
The "main" clusters are meant to colocate the most basic and highly relational application data for one or more "sister projects" managed by this site. This allows for highly flexible queries. Each project is identified by a database domain. Note that if there are several projects stored on a cluster, then the cluster dataset is a superset of the dataset for each of those projects.
The "external" clusters are meant to provide places for bulk text storage, to colocate bulky relational data from specific modules, and to colocate data from cross-project modules such as authentication systems. An external cluster can have a database/schema for each project.
Definition at line 46 of file ILBFactory.php.
Wikimedia\Rdbms\ILBFactory::__construct | ( | array | $conf | ) |
Sub-classes may extend the required keys in $conf with additional parameters.
array | $conf | Array with keys:
|
Implemented in Wikimedia\Rdbms\LBFactory, Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.
Wikimedia\Rdbms\ILBFactory::autoReconfigure | ( | ) |
Reload the configuration if necessary.
This may or may not have any effect.
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::beginPrimaryChanges | ( | $fname = __METHOD__ | ) |
Wrap subsequent queries for all transaction round aware primary connections in a transaction.
Each of these transactions will be owned by this ILBFactory instance such that direct calls to IDatabase::commit()
or IDatabase::rollback()
will be disabled. These transactions get resolved by a single call to either commitPrimaryChanges()
or rollbackPrimaryChanges()
, after which, the transaction wrapping and ownership behavior revert back to the default. When there are multiple connections involved, these methods perform best-effort distributed transactions. When using distributed transactions, the RDBMS should be configured to used pessimistic concurrency control such that the commit step of each transaction is unlikely to fail.
Transactions on replication connections are flushed so that future reads will not keep using the same point-in-time view snapshots (e.g. from MySQL REPEATABLE-READ). However, this does not wait for replication to catch up, so subsequent reads from replicas might not reflect recently committed changes.
This only applies to the tracked load balancer instances.
This allows for custom transaction rounds from any outer transaction scope.
string | $fname |
DBTransactionError |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::closeAll | ( | $fname = __METHOD__ | ) |
Close all connections on instantiated tracked load balancer instances.
string | $fname | Caller name (e.g. METHOD) |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::commitPrimaryChanges | ( | $fname = __METHOD__, | |
int | $maxWriteDuration = 0 ) |
Commit all primary connection transactions and flush all replica connection transactions.
Transactions on replication connections are flushed so that future reads will not keep using the same point-in-time view snapshots (e.g. from MySQL REPEATABLE-READ). However, this does not wait for replication to catch up, so subsequent reads from replicas might not reflect the committed changes.
This only applies to the instantiated tracked load balancer instances.
string | $fname | Caller name |
int | $maxWriteDuration | abort if more than this much time was spent in write queries |
DBTransactionError |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::destroy | ( | ) |
Close all connections and make further attempts to open connections result in DBAccessError.
This only applies to the tracked load balancer instances.
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::disableChronologyProtection | ( | ) |
Disable the ChronologyProtector on all instantiated tracked load balancer instances.
This can be called at the start of special API entry points.
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::flushPrimarySessions | ( | $fname = __METHOD__ | ) |
Release important session-level state (named lock, table locks) as post-rollback cleanup.
This only applies to the instantiated tracked load balancer instances.
This should only be called by application entry point functions, since there must be no chance that a future caller will still be expecting some of the lost session state.
string | $fname | Caller name |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::flushReplicaSnapshots | ( | $fname = __METHOD__ | ) |
Commit all replica database server transactions, clearing any point-in-time view snapshots.
This only applies to the instantiated tracked load balancer instances.
This is useful for getting rid of stale data from an implicit transaction round
string | $fname | Caller name |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::getAllExternalLBs | ( | ) |
Get the tracked load balancer instances for all external clusters.
If no tracked instance exists for a cluster, then one will be instantiated
Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.
Wikimedia\Rdbms\ILBFactory::getAllLBs | ( | ) |
Get all tracked load balancer instances (generator)
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::getAllMainLBs | ( | ) |
Get the tracked load balancer instances for all main clusters.
If no tracked instance exists for a cluster, then one will be instantiated
Note that default main cluster name is ILoadBalancer::CLUSTER_MAIN_DEFAULT
Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.
Wikimedia\Rdbms\ILBFactory::getExternalLB | ( | $cluster | ) |
Get the tracked load balancer instance for an external cluster.
If no tracked instances exists, then one will be instantiated
string | $cluster | External cluster name |
InvalidArgumentException | If $cluster is not recognized |
Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.
Wikimedia\Rdbms\ILBFactory::getLoadBalancer | ( | $domain = false | ) |
Get the tracked load balancer instance for a given domain.
If no tracked instances exists, then one will be instantiated.
This method accepts virtual domains ({
string | false | $domain | Domain ID, or false for the current domain |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::getLocalDomainID | ( | ) |
Get the local (and default) database domain ID of connection handles.
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::getMainLB | ( | $domain = false | ) |
Get the tracked load balancer instance for the main cluster that handles the given domain.
If no tracked instances exists, then one will be instantiated
string | false | $domain | Domain ID, or false for the current domain |
Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.
Referenced by MediaWiki\User\UserFactory\__construct(), and MWLBFactory\applyGlobalState().
Wikimedia\Rdbms\ILBFactory::getTransactionProfiler | ( | ) |
Get the TransactionProfiler used by this instance.
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::hasOrMadeRecentPrimaryChanges | ( | $age = null | ) |
Determine if any primary connection has pending/written changes from this request.
This only applies to the instantiated tracked load balancer instances.
float | null | $age | How many seconds ago is "recent" [defaults to LB lag wait timeout] |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::hasPrimaryChanges | ( | ) |
Determine if any primary connection has pending changes.
This only applies to the instantiated tracked load balancer instances.
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::hasStreamingReplicaServers | ( | ) |
Whether it has streaming replica servers.
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::hasTransactionRound | ( | ) |
Check if an explicit transaction round is active.
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::isReadyForRoundOperations | ( | ) |
Check if transaction rounds can be started, committed, or rolled back right now.
This can be used as a recursion guard to avoid exceptions in transaction callbacks.
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::laggedReplicaUsed | ( | ) |
Determine if any lagged replica database server connection was used.
This only applies to the instantiated tracked load balancer instances.
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::newExternalLB | ( | $cluster | ) |
Create a new load balancer instance for an external cluster.
The resulting object will be untracked and the caller is responsible for cleaning it up. Database replication positions will not be saved by ChronologyProtector.
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.
string | $cluster | External cluster name |
InvalidArgumentException | If $cluster is not recognized |
Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.
Wikimedia\Rdbms\ILBFactory::newMainLB | ( | $domain = false | ) |
Create a new load balancer instance for the main cluster that handles the given domain.
The resulting object is considered to be owned by the caller. Namely, it will be untracked, the caller is responsible for cleaning it up, and replication positions from it will not be saved by ChronologyProtector.
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.
string | false | $domain | Domain ID, or false for the current domain |
Implemented in Wikimedia\Rdbms\LBFactoryMulti, Wikimedia\Rdbms\LBFactorySimple, and Wikimedia\Rdbms\LBFactorySingle.
Wikimedia\Rdbms\ILBFactory::redefineLocalDomain | ( | $domain | ) |
Close all connections and redefine the local database domain.
This only applies to the tracked load balancer instances.
This method is only intended for use with schema creation or integration testing
DatabaseDomain | string | $domain |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::rollbackPrimaryChanges | ( | $fname = __METHOD__ | ) |
Rollback all primary connection transactions and flush all replica connection transactions.
This only applies to the instantiated tracked load balancer instances.
string | $fname | Caller name |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::setAgentName | ( | $agent | ) |
string | $agent | Agent name for query profiling |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::setDefaultReplicationWaitTimeout | ( | $seconds | ) |
Set the default timeout for replication wait checks.
int | $seconds | Timeout, in seconds |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::setDomainAliases | ( | array | $aliases | ) |
Convert certain database domains to alternative ones.
This can be used for backwards compatibility logic.
DatabaseDomain[] | string[] | $aliases | Map of (domain alias => domain) |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::setIndexAliases | ( | array | $aliases | ) |
Convert certain index names to alternative names before querying the DB.
Note that this applies to indexes regardless of the table they belong to.
This can be employed when an index was renamed X => Y in code, but the new Y-named indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA, the aliases can be removed, and then the old X-named indexes dropped.
string[] | $aliases | Map of (index alias => index name) |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::setLocalDomainPrefix | ( | $prefix | ) |
Set a new table prefix for the existing local domain ID for testing.
string | $prefix |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::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.
For example, "user" can be converted to "myschema.mydbname.user" for convenience. Appearances like user
, somedb.user, somedb.someschema.user will used literally.
Calling this twice will completely clear any old table aliases. Also, note that callers are responsible for making sure the schemas and databases actually exist.
array[] | $aliases | Map of (table => (dbname, schema, prefix) map) |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::setWaitForReplicationListener | ( | $name, | |
?callable | $callback = null ) |
Add a callback to be run in every call to waitForReplication() prior to any waiting.
Callbacks must clear any transactions that they start.
string | $name | Callback name |
callable | null | $callback | Use null to unset a callback |
Implemented in Wikimedia\Rdbms\LBFactory.
Referenced by MWLBFactory\applyGlobalState().
Wikimedia\Rdbms\ILBFactory::shutdown | ( | $flags = self::SHUTDOWN_NORMAL, | |
?callable | $workCallback = null, | ||
& | $cpIndex = null, | ||
& | $cpClientId = null ) |
Prepare all instantiated tracked load balancer instances for shutdown.
int | $flags | Bit field of ILBFactory::SHUTDOWN_* constants |
callable | null | $workCallback | Work to mask ChronologyProtector writes |
int | null | &$cpIndex | Position key write counter for ChronologyProtector [returned] |
string | null | &$cpClientId | Client ID hash for ChronologyProtector [returned] |
Implemented in Wikimedia\Rdbms\LBFactory.
Wikimedia\Rdbms\ILBFactory::waitForReplication | ( | array | $opts = [] | ) |
Waits for the replica database server to catch up to the current primary position.
Use this when updating very large numbers of rows, as in maintenance scripts, to avoid causing too much lag. This is a no-op if there are no replica database servers.
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.
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.
This only applies to the instantiated tracked load balancer instances.
array | $opts | Optional fields that include:
|
Implemented in Wikimedia\Rdbms\LBFactory.
const Wikimedia\Rdbms\ILBFactory::SHUTDOWN_NO_CHRONPROT = 1 |
Do not save "session consistency" DB replication positions.
Definition at line 50 of file ILBFactory.php.
const Wikimedia\Rdbms\ILBFactory::SHUTDOWN_NORMAL = 0 |
Idiom for "no special shutdown flags".
Definition at line 48 of file ILBFactory.php.