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<?php
/**
* Advanced generator of database load balancing objects for wiki farms
*
* @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 LBFactory_Multi extends LBFactory {
// Required settings
var $sectionsByDB, $sectionLoads, $serverTemplate;
// Optional settings
var $groupLoadsBySection = array(), $groupLoadsByDB = array(), $hostsByName = array();
var $externalLoads = array(), $externalTemplateOverrides, $templateOverridesByServer;
var $templateOverridesByCluster, $masterTemplateOverrides, $readOnlyBySection = array();
// Other stuff
var $conf, $mainLBs = array(), $extLBs = array();
var $lastWiki, $lastSection;
function __construct( $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];
}
}
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 $wiki string
* @return LoadBalancer
*/
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 $wiki
* @return LoadBalancer
*/
function getMainLB( $wiki = false ) {
$section = $this->getSectionForWiki( $wiki );
if ( !isset( $this->mainLBs[$section] ) ) {
$lb = $this->newMainLB( $wiki, $section );
$this->chronProt->initLB( $lb );
$lb->parentInfo( array( 'id' => "main-$section" ) );
$this->mainLBs[$section] = $lb;
}
return $this->mainLBs[$section];
}
/**
* @param $cluster
* @param $wiki
* @return LoadBalancer
*/
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 $cluster
* @param $wiki
* @return LoadBalancer
*/
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];
}
/**
* Make a new load balancer object based on template and load array
*
* @return LoadBalancer
*/
function newLoadBalancer( $template, $loads, $groupLoads ) {
global $wgMasterWaitTimeout;
$servers = $this->makeServerArray( $template, $loads, $groupLoads );
$lb = new LoadBalancer( array(
'servers' => $servers,
'masterWaitTimeout' => $wgMasterWaitTimeout
));
return $lb;
}
/**
* Make a server array as expected by LoadBalancer::__construct, using a template and load array
*
* @return array
*/
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
*/
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
*/
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.
*/
function forEachLB( $callback, $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 ) );
}
}
function shutdown() {
foreach ( $this->mainLBs as $lb ) {
$this->chronProt->shutdownLB( $lb );
}
$this->chronProt->shutdown();
$this->commitMasterChanges();
}
}
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