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<?php
/**
* Generator and manager of database load balancing objects
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup Database
*/
/**
* An interface for generating database load balancers
* @ingroup Database
* @since 1.28
*/
interface ILBFactory {
const SHUTDOWN_NO_CHRONPROT = 0; // don't save DB positions at all
const SHUTDOWN_CHRONPROT_ASYNC = 1; // save DB positions, but don't wait on remote DCs
const SHUTDOWN_CHRONPROT_SYNC = 2; // save DB positions, waiting on all DCs
/**
* Construct a manager of ILoadBalancer objects
*
* Sub-classes will extend the required keys in $conf with additional parameters
*
* @param $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]
* @throws InvalidArgumentException
*/
public function __construct( array $conf );
/**
* Disables all load balancers. All connections are closed, and any attempt to
* open a new connection will result in a DBAccessError.
* @see ILoadBalancer::disable()
*/
public function destroy();
/**
* 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.
*
* @param bool|string $domain Domain ID, or false for the current domain
* @return ILoadBalancer
*/
public function newMainLB( $domain = false );
/**
* Get a cached (tracked) load balancer object.
*
* @param bool|string $domain Domain ID, or false for the current domain
* @return ILoadBalancer
*/
public function getMainLB( $domain = false );
/**
* 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.
*
* @param string $cluster External storage cluster name
* @return ILoadBalancer
*/
public function newExternalLB( $cluster );
/**
* Get a cached (tracked) load balancer for external storage
*
* @param string $cluster External storage cluster name
* @return ILoadBalancer
*/
public function getExternalLB( $cluster );
/**
* 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.
*
* @param callable $callback
* @param array $params
*/
public function forEachLB( $callback, array $params = [] );
/**
* Prepare all tracked load balancers for shutdown
* @param integer $mode One of the class SHUTDOWN_* constants
* @param callable|null $workCallback Work to mask ChronologyProtector writes
*/
public function shutdown(
$mode = self::SHUTDOWN_CHRONPROT_SYNC, callable $workCallback = null
);
/**
* Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshot
*
* @param string $fname Caller name
*/
public function flushReplicaSnapshots( $fname = __METHOD__ );
/**
* 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.
* @param string $fname Caller name
* @param array $options Options map:
* - maxWriteDuration: abort if more than this much time was spent in write queries
*/
public function commitAll( $fname = __METHOD__, array $options = [] );
/**
* 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:
* - commitMasterChanges()
* - rollbackMasterChanges()
* - commitAll()
*
* This allows for custom transaction rounds from any outer transaction scope.
*
* @param string $fname
* @throws DBTransactionError
*/
public function beginMasterChanges( $fname = __METHOD__ );
/**
* Commit changes on all master connections
* @param string $fname Caller name
* @param array $options Options map:
* - maxWriteDuration: abort if more than this much time was spent in write queries
* @throws Exception
*/
public function commitMasterChanges( $fname = __METHOD__, array $options = [] );
/**
* Rollback changes on all master connections
* @param string $fname Caller name
*/
public function rollbackMasterChanges( $fname = __METHOD__ );
/**
* Check if a transaction round is active
* @return bool
* @since 1.28.3
*/
public function hasTransactionRound();
/**
* Determine if any master connection has pending changes
* @return bool
*/
public function hasMasterChanges();
/**
* Detemine if any lagged replica DB connection was used
* @return bool
*/
public function laggedReplicaUsed();
/**
* Determine if any master connection has pending/written changes from this request
* @param float $age How many seconds ago is "recent" [defaults to LB lag wait timeout]
* @return bool
*/
public function hasOrMadeRecentMasterChanges( $age = null );
/**
* 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.
*
* @param 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
* @throws DBReplicationWaitError If a timeout or error occured waiting on a DB cluster
*/
public function waitForReplication( array $opts = [] );
/**
* Add a callback to be run in every call to waitForReplication() before waiting
*
* Callbacks must clear any transactions that they start
*
* @param string $name Callback name
* @param callable|null $callback Use null to unset a callback
*/
public function setWaitForReplicationListener( $name, callable $callback = null );
/**
* Get a token asserting that no transaction writes are active
*
* @param string $fname Caller name (e.g. __METHOD__)
* @return mixed A value to pass to commitAndWaitForReplication()
*/
public function getEmptyTransactionTicket( $fname );
/**
* Convenience method for safely running commitMasterChanges()/waitForReplication()
*
* This will commit and wait unless $ticket indicates it is unsafe to do so
*
* @param string $fname Caller name (e.g. __METHOD__)
* @param mixed $ticket Result of getEmptyTransactionTicket()
* @param array $opts Options to waitForReplication()
* @throws DBReplicationWaitError
*/
public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] );
/**
* @param string $dbName DB master name (e.g. "db1052")
* @return float|bool UNIX timestamp when client last touched the DB or false if not recent
*/
public function getChronologyProtectorTouched( $dbName );
/**
* Disable the ChronologyProtector for all load balancers
*
* This can be called at the start of special API entry points
*/
public function disableChronologyProtection();
/**
* Set a new table prefix for the existing local domain ID for testing
*
* @param string $prefix
*/
public function setDomainPrefix( $prefix );
/**
* Close all open database connections on all open load balancers.
*/
public function closeAll();
/**
* @param string $agent Agent name for query profiling
*/
public function setAgentName( $agent );
/**
* Append ?cpPosTime parameter to a URL for ChronologyProtector purposes if needed
*
* Note that unlike cookies, this works accross domains
*
* @param string $url
* @param float $time UNIX timestamp just before shutdown() was called
* @return string
*/
public function appendPreShutdownTimeAsQuery( $url, $time );
/**
* @param array $info Map of fields, including:
* - IPAddress : IP address
* - UserAgent : User-Agent HTTP header
* - ChronologyProtection : cookie/header value specifying ChronologyProtector usage
*/
public function setRequestInfo( array $info );
}