+++ /dev/null
-<?php
-/**
- * Generator of database load balancing objects
- *
- * @file
- * @ingroup Database
- */
-
-/**
- * An interface for generating database load balancers
- * @ingroup Database
- */
-abstract class LBFactory {
- 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 LBFactory_Fake( $wgLBFactoryConf );
- }
-
- /**
- * Resets the singleton for use if it's been disabled. Does nothing otherwise
- */
- public static function enableBackend() {
- if( self::$instance instanceof LBFactory_Fake )
- self::$instance = null;
- }
-
- /**
- * Get an LBFactory instance
- */
- static function &singleton() {
- if ( is_null( self::$instance ) ) {
- global $wgLBFactoryConf;
- $class = $wgLBFactoryConf['class'];
- self::$instance = new $class( $wgLBFactoryConf );
- }
- return self::$instance;
- }
-
- /**
- * Shut down, close connections and destroy the cached instance.
- *
- */
- static function destroyInstance() {
- if ( self::$instance ) {
- self::$instance->shutdown();
- self::$instance->forEachLBCallMethod( 'closeAll' );
- self::$instance = null;
- }
- }
-
- /**
- * Set the instance to be the given object
- */
- static function setInstance( $instance ) {
- self::destroyInstance();
- self::$instance = $instance;
- }
-
- /**
- * Construct a factory based on a configuration array (typically from $wgLBFactoryConf)
- */
- abstract function __construct( $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 $wiki String: wiki ID, or false for the current wiki
- * @return LoadBalancer
- */
- abstract function newMainLB( $wiki = false );
-
- /**
- * Get a cached (tracked) load balancer object.
- *
- * @param $wiki String: wiki ID, or false for the current wiki
- * @return LoadBalancer
- */
- abstract 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 $cluster String: external storage cluster, or false for core
- * @param $wiki String: wiki ID, or false for the current wiki
- */
- abstract function newExternalLB( $cluster, $wiki = false );
-
- /*
- * Get a cached (tracked) load balancer for external storage
- *
- * @param $cluster String: external storage cluster, or false for core
- * @param $wiki String: wiki ID, or false for the current wiki
- */
- abstract 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.
- */
- abstract function forEachLB( $callback, $params = array() );
-
- /**
- * Prepare all tracked load balancers for shutdown
- * STUB
- */
- function shutdown() {}
-
- /**
- * Call a method of each tracked load balancer
- */
- function forEachLBCallMethod( $methodName, $args = array() ) {
- $this->forEachLB( array( $this, 'callMethod' ), array( $methodName, $args ) );
- }
-
- /**
- * Private helper for forEachLBCallMethod
- */
- function callMethod( $loadBalancer, $methodName, $args ) {
- call_user_func_array( array( $loadBalancer, $methodName ), $args );
- }
-
- /**
- * Commit changes on all master connections
- */
- function commitMasterChanges() {
- $this->forEachLBCallMethod( 'commitMasterChanges' );
- }
-}
-
-/**
- * A simple single-master LBFactory that gets its configuration from the b/c globals
- */
-class LBFactory_Simple extends LBFactory {
- var $mainLB;
- var $extLBs = array();
-
- # Chronology protector
- var $chronProt;
-
- function __construct( $conf ) {
- $this->chronProt = new ChronologyProtector;
- }
-
- function newMainLB( $wiki = false ) {
- global $wgDBservers, $wgMasterWaitTimeout;
- if ( $wgDBservers ) {
- $servers = $wgDBservers;
- } else {
- global $wgDBserver, $wgDBuser, $wgDBpassword, $wgDBname, $wgDBtype, $wgDebugDumpSql;
- $servers = array(array(
- 'host' => $wgDBserver,
- 'user' => $wgDBuser,
- 'password' => $wgDBpassword,
- 'dbname' => $wgDBname,
- 'type' => $wgDBtype,
- 'load' => 1,
- 'flags' => ($wgDebugDumpSql ? DBO_DEBUG : 0) | DBO_DEFAULT
- ));
- }
-
- return new LoadBalancer( array(
- 'servers' => $servers,
- 'masterWaitTimeout' => $wgMasterWaitTimeout
- ));
- }
-
- 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;
- }
-
- 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]
- ));
- }
-
- 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" ) );
- }
- 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.
- */
- function forEachLB( $callback, $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 ) );
- }
- }
-
- function shutdown() {
- if ( $this->mainLB ) {
- $this->chronProt->shutdownLB( $this->mainLB );
- }
- $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 LBFactory_Fake extends LBFactory {
- function __construct( $conf ) {}
-
- function newMainLB( $wiki = false) {
- throw new DBAccessError;
- }
- function getMainLB( $wiki = false ) {
- throw new DBAccessError;
- }
- function newExternalLB( $cluster, $wiki = false ) {
- throw new DBAccessError;
- }
- function &getExternalLB( $cluster, $wiki = false ) {
- throw new DBAccessError;
- }
- function forEachLB( $callback, $params = array() ) {}
-}
-
-/**
- * Exception class for attempted DB access
- */
-class DBAccessError extends MWException {
- function __construct() {
- parent::__construct( "Mediawiki tried to access the database via wfGetDB(). This is not allowed." );
- }
-}
-
-/**
- * Class for ensuring a consistent ordering of events as seen by the user, despite replication.
- * Kind of like Hawking's [[Chronology Protection Agency]].
- */
-class ChronologyProtector {
- var $startupPos;
- var $shutdownPos = array();
-
- /**
- * Initialise a LoadBalancer to give it appropriate chronology protection.
- *
- * @param $lb LoadBalancer
- */
- function initLB( $lb ) {
- if ( $this->startupPos === null ) {
- if ( !empty( $_SESSION[__CLASS__] ) ) {
- $this->startupPos = $_SESSION[__CLASS__];
- }
- }
- if ( !$this->startupPos ) {
- return;
- }
- $masterName = $lb->getServerName( 0 );
-
- if ( $lb->getServerCount() > 1 && !empty( $this->startupPos[$masterName] ) ) {
- $info = $lb->parentInfo();
- $pos = $this->startupPos[$masterName];
- wfDebug( __METHOD__.": LB " . $info['id'] . " waiting for master pos $pos\n" );
- $lb->waitFor( $this->startupPos[$masterName] );
- }
- }
-
- /**
- * Notify the ChronologyProtector that the LoadBalancer is about to shut
- * down. Saves replication positions.
- *
- * @param $lb LoadBalancer
- */
- function shutdownLB( $lb ) {
- // Don't start a session, don't bother with non-replicated setups
- if ( strval( session_id() ) == '' || $lb->getServerCount() <= 1 ) {
- return;
- }
- $masterName = $lb->getServerName( 0 );
- if ( isset( $this->shutdownPos[$masterName] ) ) {
- // Already done
- return;
- }
- // Only save the position if writes have been done on the connection
- $db = $lb->getAnyOpenConnection( 0 );
- $info = $lb->parentInfo();
- if ( !$db || !$db->doneWrites() ) {
- wfDebug( __METHOD__.": LB {$info['id']}, no writes done\n" );
- return;
- }
- $pos = $db->getMasterPos();
- wfDebug( __METHOD__.": LB {$info['id']} has master pos $pos\n" );
- $this->shutdownPos[$masterName] = $pos;
- }
-
- /**
- * Notify the ChronologyProtector that the LBFactory is done calling shutdownLB() for now.
- * May commit chronology data to persistent storage.
- */
- function shutdown() {
- if ( session_id() != '' && count( $this->shutdownPos ) ) {
- wfDebug( __METHOD__.": saving master pos for " .
- count( $this->shutdownPos ) . " master(s)\n" );
- $_SESSION[__CLASS__] = $this->shutdownPos;
- }
- }
-}
scripts.mit.edu / autoinstallsdev / mediawiki.git / blobdiff