Current File : //www/varak.net/wiki.varak.net/includes/db/LBFactoryMulti.php
<?php
/**
* Advanced generator of database load balancing objects for wiki farms.
*
* 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
*/
/**
* A multi-wiki, multi-master factory for Wikimedia and similar installations.
* Ignores the old configuration globals
*
* Configuration:
* sectionsByDB A map of database names to section names.
*
* sectionLoads A 2-d map. For each section, gives a map of server names to
* load ratios. For example:
* array(
* 'section1' => array(
* 'db1' => 100,
* 'db2' => 100
* )
* )
*
* serverTemplate A server info associative array as documented for $wgDBservers.
* The host, hostName and load entries will be overridden.
*
* groupLoadsBySection A 3-d map giving server load ratios for each section and group.
* For example:
* array(
* 'section1' => array(
* 'group1' => array(
* 'db1' => 100,
* 'db2' => 100
* )
* )
* )
*
* groupLoadsByDB A 3-d map giving server load ratios by DB name.
*
* hostsByName A map of hostname to IP address.
*
* externalLoads A map of external storage cluster name to server load map.
*
* externalTemplateOverrides A set of server info keys overriding serverTemplate for external
* storage.
*
* templateOverridesByServer A 2-d map overriding serverTemplate and
* externalTemplateOverrides on a server-by-server basis. Applies
* to both core and external storage.
*
* templateOverridesByCluster A 2-d map overriding the server info by external storage cluster.
*
* masterTemplateOverrides An override array for all master servers.
*
* readOnlyBySection A map of section name to read-only message.
* Missing or false for read/write.
*
* @ingroup Database
*/
class LBFactoryMulti extends LBFactory {
// Required settings
/** @var array A map of database names to section names */
private $sectionsByDB;
/**
* @var array A 2-d map. For each section, gives a map of server names to
* load ratios
*/
private $sectionLoads;
/**
* @var array A server info associative array as documented for
* $wgDBservers. The host, hostName and load entries will be
* overridden
*/
private $serverTemplate;
// Optional settings
/** @var array A 3-d map giving server load ratios for each section and group */
private $groupLoadsBySection = array();
/** @var array A 3-d map giving server load ratios by DB name */
private $groupLoadsByDB = array();
/** @var array A map of hostname to IP address */
private $hostsByName = array();
/** @var array A map of external storage cluster name to server load map */
private $externalLoads = array();
/**
* @var array A set of server info keys overriding serverTemplate for
* external storage
*/
private $externalTemplateOverrides;
/**
* @var array A 2-d map overriding serverTemplate and
* externalTemplateOverrides on a server-by-server basis. Applies to both
* core and external storage
*/
private $templateOverridesByServer;
/** @var array A 2-d map overriding the server info by external storage cluster */
private $templateOverridesByCluster;
/** @var array An override array for all master servers */
private $masterTemplateOverrides;
/**
* @var array|bool A map of section name to read-only message. Missing or
* false for read/write
*/
private $readOnlyBySection = array();
// Other stuff
/** @var array Load balancer factory configuration */
private $conf;
/** @var LoadBalancer[] */
private $mainLBs = array();
/** @var LoadBalancer[] */
private $extLBs = array();
/** @var string */
private $lastWiki;
/** @var string */
private $lastSection;
/**
* @param array $conf
* @throws MWException
*/
public function __construct( array $conf ) {
$this->chronProt = new ChronologyProtector;
$this->conf = $conf;
$required = array( 'sectionsByDB', 'sectionLoads', 'serverTemplate' );
$optional = array( 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
'templateOverridesByCluster', 'masterTemplateOverrides',
'readOnlyBySection' );
foreach ( $required as $key ) {
if ( !isset( $conf[$key] ) ) {
throw new MWException( __CLASS__ . ": $key is required in configuration" );
}
$this->$key = $conf[$key];
}
foreach ( $optional as $key ) {
if ( isset( $conf[$key] ) ) {
$this->$key = $conf[$key];
}
}
// Check for read-only mode
$section = $this->getSectionForWiki();
if ( !empty( $this->readOnlyBySection[$section] ) ) {
global $wgReadOnly;
$wgReadOnly = $this->readOnlyBySection[$section];
}
}
/**
* @param bool|string $wiki
* @return string
*/
private function getSectionForWiki( $wiki = false ) {
if ( $this->lastWiki === $wiki ) {
return $this->lastSection;
}
list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
if ( isset( $this->sectionsByDB[$dbName] ) ) {
$section = $this->sectionsByDB[$dbName];
} else {
$section = 'DEFAULT';
}
$this->lastSection = $section;
$this->lastWiki = $wiki;
return $section;
}
/**
* @param bool|string $wiki
* @return LoadBalancer
*/
public function newMainLB( $wiki = false ) {
list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
$section = $this->getSectionForWiki( $wiki );
$groupLoads = array();
if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
$groupLoads = $this->groupLoadsByDB[$dbName];
}
if ( isset( $this->groupLoadsBySection[$section] ) ) {
$groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
}
return $this->newLoadBalancer(
$this->serverTemplate,
$this->sectionLoads[$section],
$groupLoads
);
}
/**
* @param bool|string $wiki
* @return LoadBalancer
*/
public function getMainLB( $wiki = false ) {
$section = $this->getSectionForWiki( $wiki );
if ( !isset( $this->mainLBs[$section] ) ) {
$lb = $this->newMainLB( $wiki );
$lb->parentInfo( array( 'id' => "main-$section" ) );
$this->chronProt->initLB( $lb );
$this->mainLBs[$section] = $lb;
}
return $this->mainLBs[$section];
}
/**
* @param string $cluster
* @param bool|string $wiki
* @throws MWException
* @return LoadBalancer
*/
protected function newExternalLB( $cluster, $wiki = false ) {
if ( !isset( $this->externalLoads[$cluster] ) ) {
throw new MWException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
}
$template = $this->serverTemplate;
if ( isset( $this->externalTemplateOverrides ) ) {
$template = $this->externalTemplateOverrides + $template;
}
if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
$template = $this->templateOverridesByCluster[$cluster] + $template;
}
return $this->newLoadBalancer( $template, $this->externalLoads[$cluster], array() );
}
/**
* @param string $cluster External storage cluster, or false for core
* @param bool|string $wiki Wiki ID, or false for the current wiki
* @return LoadBalancer
*/
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];
}
/**
* Make a new load balancer object based on template and load array
*
* @param array $template
* @param array $loads
* @param array $groupLoads
* @return LoadBalancer
*/
private function newLoadBalancer( $template, $loads, $groupLoads ) {
$servers = $this->makeServerArray( $template, $loads, $groupLoads );
$lb = new LoadBalancer( array(
'servers' => $servers,
) );
return $lb;
}
/**
* Make a server array as expected by LoadBalancer::__construct, using a template and load array
*
* @param array $template
* @param array $loads
* @param array $groupLoads
* @return array
*/
private function makeServerArray( $template, $loads, $groupLoads ) {
$servers = array();
$master = true;
$groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
foreach ( $groupLoadsByServer as $server => $stuff ) {
if ( !isset( $loads[$server] ) ) {
$loads[$server] = 0;
}
}
foreach ( $loads as $serverName => $load ) {
$serverInfo = $template;
if ( $master ) {
$serverInfo['master'] = true;
if ( isset( $this->masterTemplateOverrides ) ) {
$serverInfo = $this->masterTemplateOverrides + $serverInfo;
}
$master = false;
}
if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
$serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
}
if ( isset( $groupLoadsByServer[$serverName] ) ) {
$serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
}
if ( isset( $this->hostsByName[$serverName] ) ) {
$serverInfo['host'] = $this->hostsByName[$serverName];
} else {
$serverInfo['host'] = $serverName;
}
$serverInfo['hostName'] = $serverName;
$serverInfo['load'] = $load;
$servers[] = $serverInfo;
}
return $servers;
}
/**
* Take a group load array indexed by group then server, and reindex it by server then group
* @param array $groupLoads
* @return array
*/
private function reindexGroupLoads( $groupLoads ) {
$reindexed = array();
foreach ( $groupLoads as $group => $loads ) {
foreach ( $loads as $server => $load ) {
$reindexed[$server][$group] = $load;
}
}
return $reindexed;
}
/**
* Get the database name and prefix based on the wiki ID
* @param bool|string $wiki
* @return array
*/
private function getDBNameAndPrefix( $wiki = false ) {
if ( $wiki === false ) {
global $wgDBname, $wgDBprefix;
return array( $wgDBname, $wgDBprefix );
} else {
return wfSplitWikiID( $wiki );
}
}
/**
* 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() ) {
foreach ( $this->mainLBs as $lb ) {
call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
}
foreach ( $this->extLBs as $lb ) {
call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
}
}
public function shutdown() {
foreach ( $this->mainLBs as $lb ) {
$this->chronProt->shutdownLB( $lb );
}
foreach ( $this->extLBs as $extLB ) {
$this->chronProt->shutdownLB( $extLB );
}
$this->chronProt->shutdown();
$this->commitMasterChanges();
}
}
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