Current File : //www/varak.net/wiki.varak.net/includes/db/LBFactory.php
<?php
/**
* Generator 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
*/
abstract class LBFactory {
/** @var LBFactory */
private static $instance;
/**
* Disables all access to the load balancer, will cause all database access
* to throw a DBAccessError
*/
public static function disableBackend() {
global $wgLBFactoryConf;
self::$instance = new LBFactoryFake( $wgLBFactoryConf );
}
/**
* Get an LBFactory instance
*
* @return LBFactory
*/
public static function singleton() {
global $wgLBFactoryConf;
if ( is_null( self::$instance ) ) {
$class = self::getLBFactoryClass( $wgLBFactoryConf );
self::$instance = new $class( $wgLBFactoryConf );
}
return self::$instance;
}
/**
* Returns the LBFactory class to use and the load balancer configuration.
*
* @param array $config (e.g. $wgLBFactoryConf)
* @return string Class name
*/
public static function getLBFactoryClass( array $config ) {
// For configuration backward compatibility after removing
// underscores from class names in MediaWiki 1.23.
$bcClasses = array(
'LBFactory_Simple' => 'LBFactorySimple',
'LBFactory_Single' => 'LBFactorySingle',
'LBFactory_Multi' => 'LBFactoryMulti',
'LBFactory_Fake' => 'LBFactoryFake',
);
$class = $config['class'];
if ( isset( $bcClasses[$class] ) ) {
$class = $bcClasses[$class];
wfDeprecated(
'$wgLBFactoryConf must be updated. See RELEASE-NOTES for details',
'1.23'
);
}
return $class;
}
/**
* Shut down, close connections and destroy the cached instance.
*/
public static function destroyInstance() {
if ( self::$instance ) {
self::$instance->shutdown();
self::$instance->forEachLBCallMethod( 'closeAll' );
self::$instance = null;
}
}
/**
* Set the instance to be the given object
*
* @param LBFactory $instance
*/
public static function setInstance( $instance ) {
self::destroyInstance();
self::$instance = $instance;
}
/**
* Construct a factory based on a configuration array (typically from $wgLBFactoryConf)
* @param array $conf
*/
abstract public function __construct( array $conf );
/**
* Create a new load balancer object. The resulting object will be untracked,
* not chronology-protected, and the caller is responsible for cleaning it up.
*
* @param bool|string $wiki Wiki ID, or false for the current wiki
* @return LoadBalancer
*/
abstract public function newMainLB( $wiki = false );
/**
* Get a cached (tracked) load balancer object.
*
* @param bool|string $wiki Wiki ID, or false for the current wiki
* @return LoadBalancer
*/
abstract public function getMainLB( $wiki = 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.
*
* @param string $cluster External storage cluster, or false for core
* @param bool|string $wiki Wiki ID, or false for the current wiki
* @return LoadBalancer
*/
abstract protected function newExternalLB( $cluster, $wiki = false );
/**
* Get a cached (tracked) load balancer for external storage
*
* @param string $cluster External storage cluster, or false for core
* @param bool|string $wiki Wiki ID, or false for the current wiki
* @return LoadBalancer
*/
abstract public function &getExternalLB( $cluster, $wiki = false );
/**
* 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
*/
abstract public function forEachLB( $callback, array $params = array() );
/**
* Prepare all tracked load balancers for shutdown
* STUB
*/
public function shutdown() {
}
/**
* Call a method of each tracked load balancer
*
* @param string $methodName
* @param array $args
*/
private function forEachLBCallMethod( $methodName, array $args = array() ) {
$this->forEachLB( function ( LoadBalancer $loadBalancer, $methodName, array $args ) {
call_user_func_array( array( $loadBalancer, $methodName ), $args );
}, array( $methodName, $args ) );
}
/**
* Commit on all connections. Done for two reasons:
* 1. To commit changes to the masters.
* 2. To release the snapshot on all connections, master and slave.
*/
public function commitAll() {
$this->forEachLBCallMethod( 'commitAll' );
}
/**
* Commit changes on all master connections
*/
public function commitMasterChanges() {
$this->forEachLBCallMethod( 'commitMasterChanges' );
}
/**
* Rollback changes on all master connections
* @since 1.23
*/
public function rollbackMasterChanges() {
$this->forEachLBCallMethod( 'rollbackMasterChanges' );
}
/**
* Detemine if any master connection has pending changes.
* @since 1.23
* @return bool
*/
public function hasMasterChanges() {
$ret = false;
$this->forEachLB( function ( LoadBalancer $lb ) use ( &$ret ) {
$ret = $ret || $lb->hasMasterChanges();
} );
return $ret;
}
}
/**
* A simple single-master LBFactory that gets its configuration from the b/c globals
*/
class LBFactorySimple extends LBFactory {
/** @var LoadBalancer */
private $mainLB;
/** @var LoadBalancer[] */
private $extLBs = array();
/** @var ChronologyProtector */
private $chronProt;
public function __construct( array $conf ) {
$this->chronProt = new ChronologyProtector;
}
/**
* @param bool|string $wiki
* @return LoadBalancer
*/
public function newMainLB( $wiki = false ) {
global $wgDBservers;
if ( $wgDBservers ) {
$servers = $wgDBservers;
} else {
global $wgDBserver, $wgDBuser, $wgDBpassword, $wgDBname, $wgDBtype, $wgDebugDumpSql;
global $wgDBssl, $wgDBcompress;
$flags = DBO_DEFAULT;
if ( $wgDebugDumpSql ) {
$flags |= DBO_DEBUG;
}
if ( $wgDBssl ) {
$flags |= DBO_SSL;
}
if ( $wgDBcompress ) {
$flags |= DBO_COMPRESS;
}
$servers = array( array(
'host' => $wgDBserver,
'user' => $wgDBuser,
'password' => $wgDBpassword,
'dbname' => $wgDBname,
'type' => $wgDBtype,
'load' => 1,
'flags' => $flags
) );
}
return new LoadBalancer( array(
'servers' => $servers,
) );
}
/**
* @param bool|string $wiki
* @return LoadBalancer
*/
public function getMainLB( $wiki = false ) {
if ( !isset( $this->mainLB ) ) {
$this->mainLB = $this->newMainLB( $wiki );
$this->mainLB->parentInfo( array( 'id' => 'main' ) );
$this->chronProt->initLB( $this->mainLB );
}
return $this->mainLB;
}
/**
* @throws MWException
* @param string $cluster
* @param bool|string $wiki
* @return LoadBalancer
*/
protected function newExternalLB( $cluster, $wiki = false ) {
global $wgExternalServers;
if ( !isset( $wgExternalServers[$cluster] ) ) {
throw new MWException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
}
return new LoadBalancer( array(
'servers' => $wgExternalServers[$cluster]
) );
}
/**
* @param string $cluster
* @param bool|string $wiki
* @return array
*/
public function &getExternalLB( $cluster, $wiki = false ) {
if ( !isset( $this->extLBs[$cluster] ) ) {
$this->extLBs[$cluster] = $this->newExternalLB( $cluster, $wiki );
$this->extLBs[$cluster]->parentInfo( array( 'id' => "ext-$cluster" ) );
$this->chronProt->initLB( $this->extLBs[$cluster] );
}
return $this->extLBs[$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 = array() ) {
if ( isset( $this->mainLB ) ) {
call_user_func_array( $callback, array_merge( array( $this->mainLB ), $params ) );
}
foreach ( $this->extLBs as $lb ) {
call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
}
}
public function shutdown() {
if ( $this->mainLB ) {
$this->chronProt->shutdownLB( $this->mainLB );
}
foreach ( $this->extLBs as $extLB ) {
$this->chronProt->shutdownLB( $extLB );
}
$this->chronProt->shutdown();
$this->commitMasterChanges();
}
}
/**
* LBFactory class that throws an error on any attempt to use it.
* This will typically be done via wfGetDB().
* Call LBFactory::disableBackend() to start using this, and
* LBFactory::enableBackend() to return to normal behavior
*/
class LBFactoryFake extends LBFactory {
public function __construct( array $conf ) {
}
public function newMainLB( $wiki = false ) {
throw new DBAccessError;
}
public function getMainLB( $wiki = false ) {
throw new DBAccessError;
}
protected function newExternalLB( $cluster, $wiki = false ) {
throw new DBAccessError;
}
public function &getExternalLB( $cluster, $wiki = false ) {
throw new DBAccessError;
}
public function forEachLB( $callback, array $params = array() ) {
}
}
/**
* Exception class for attempted DB access
*/
class DBAccessError extends MWException {
public function __construct() {
parent::__construct( "Mediawiki tried to access the database via wfGetDB(). " .
"This is not allowed." );
}
}
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