includes/db/LBFactory_Multi.php

   1 <?php
   2 /**
   3  * @file
   4  * @ingroup Database
   5  */
   6
   7
   8 /**
   9  * A multi-wiki, multi-master factory for Wikimedia and similar installations.
  10  * Ignores the old configuration globals
  11  *
  12  * Configuration:
  13  *     sectionsByDB                A map of database names to section names
  14  *
  15  *     sectionLoads                A 2-d map. For each section, gives a map of server names to load ratios.
  16  *                                 For example: array( 'section1' => array( 'db1' => 100, 'db2' => 100 ) )
  17  *
  18  *     serverTemplate              A server info associative array as documented for $wgDBservers. The host,
  19  *                                 hostName and load entries will be overridden.
  20  *
  21  *     groupLoadsBySection         A 3-d map giving server load ratios for each section and group. For example:
  22  *                                 array( 'section1' => array( 'group1' => array( 'db1' => 100, 'db2' => 100 ) ) )
  23  *
  24  *     groupLoadsByDB              A 3-d map giving server load ratios by DB name.
  25  *
  26  *     hostsByName                 A map of hostname to IP address.
  27  *
  28  *     externalLoads               A map of external storage cluster name to server load map
  29  *
  30  *     externalTemplateOverrides   A set of server info keys overriding serverTemplate for external storage
  31  *
  32  *     templateOverridesByServer   A 2-d map overriding serverTemplate and externalTemplateOverrides on a
  33  *                                 server-by-server basis. Applies to both core and external storage.
  34  *
  35  *     templateOverridesByCluster  A 2-d map overriding the server info by external storage cluster
  36  *
  37  *     masterTemplateOverrides     An override array for all master servers.
  38  *
  39  * @ingroup Database
  40  */
  41 class LBFactory_Multi extends LBFactory {
  42         // Required settings
  43         var $sectionsByDB, $sectionLoads, $serverTemplate;
  44         // Optional settings
  45         var $groupLoadsBySection = array(), $groupLoadsByDB = array(), $hostsByName = array();
  46         var $externalLoads = array(), $externalTemplateOverrides, $templateOverridesByServer;
  47         var $templateOverridesByCluster, $masterTemplateOverrides;
  48         // Other stuff
  49         var $conf, $mainLBs = array(), $extLBs = array();
  50         var $lastWiki, $lastSection;
  51
  52         function __construct( $conf ) {
  53                 $this->chronProt = new ChronologyProtector;
  54                 $this->conf = $conf;
  55                 $required = array( 'sectionsByDB', 'sectionLoads', 'serverTemplate' );
  56                 $optional = array( 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
  57                         'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
  58                         'templateOverridesByCluster', 'masterTemplateOverrides' );
  59
  60                 foreach ( $required as $key ) {
  61                         if ( !isset( $conf[$key] ) ) {
  62                                 throw new MWException( __CLASS__.": $key is required in configuration" );
  63                         }
  64                         $this->$key = $conf[$key];
  65                 }
  66
  67                 foreach ( $optional as $key ) {
  68                         if ( isset( $conf[$key] ) ) {
  69                                 $this->$key = $conf[$key];
  70                         }
  71                 }
  72         }
  73
  74         function getSectionForWiki( $wiki = false ) {
  75                 if ( $this->lastWiki === $wiki ) {
  76                         return $this->lastSection;
  77                 }
  78                 list( $dbName, $prefix ) = $this->getDBNameAndPrefix( $wiki );
  79                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
  80                         $section = $this->sectionsByDB[$dbName];
  81                 } else {
  82                         $section = 'DEFAULT';
  83                 }
  84                 $this->lastSection = $section;
  85                 $this->lastWiki = $wiki;
  86                 return $section;
  87         }
  88
  89         function newMainLB( $wiki = false ) {
  90                 list( $dbName, $prefix ) = $this->getDBNameAndPrefix( $wiki );
  91                 $section = $this->getSectionForWiki( $wiki );
  92                 $groupLoads = array();
  93                 if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
  94                         $groupLoads = $this->groupLoadsByDB[$dbName];
  95                 }
  96                 if ( isset( $this->groupLoadsBySection[$section] ) ) {
  97                         $groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
  98                 }
  99                 return $this->newLoadBalancer( $this->serverTemplate, $this->sectionLoads[$section], $groupLoads );
 100         }
 101
 102         function getMainLB( $wiki = false ) {
 103                 $section = $this->getSectionForWiki( $wiki );
 104                 if ( !isset( $this->mainLBs[$section] ) ) {
 105                         $lb = $this->newMainLB( $wiki, $section );
 106                         $this->chronProt->initLB( $lb );
 107                         $lb->parentInfo( array( 'id' => "main-$section" ) );
 108                         $this->mainLBs[$section] = $lb;
 109                 }
 110                 return $this->mainLBs[$section];
 111         }
 112
 113         function newExternalLB( $cluster, $wiki = false ) {
 114                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 115                         throw new MWException( __METHOD__.": Unknown cluster \"$cluster\"" );
 116                 }
 117                 $template = $this->serverTemplate;
 118                 if ( isset( $this->externalTemplateOverrides ) ) {
 119                         $template = $this->externalTemplateOverrides + $template;
 120                 }
 121                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 122                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 123                 }
 124                 return $this->newLoadBalancer( $template, $this->externalLoads[$cluster], array() );
 125         }
 126
 127         function &getExternalLB( $cluster, $wiki = false ) {
 128                 if ( !isset( $this->extLBs[$cluster] ) ) {
 129                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $wiki );
 130                         $this->extLBs[$cluster]->parentInfo( array( 'id' => "ext-$cluster" ) );
 131                 }
 132                 return $this->extLBs[$cluster];
 133         }
 134
 135         /**
 136          * Make a new load balancer object based on template and load array
 137          */
 138         function newLoadBalancer( $template, $loads, $groupLoads ) {
 139                 global $wgMasterWaitTimeout;
 140                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 141                 $lb = new LoadBalancer( array(
 142                         'servers' => $servers,
 143                         'masterWaitTimeout' => $wgMasterWaitTimeout
 144                 ));
 145                 return $lb;
 146         }
 147
 148         /**
 149          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 150          */
 151         function makeServerArray( $template, $loads, $groupLoads ) {
 152                 $servers = array();
 153                 $master = true;
 154                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 155                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 156                         if ( !isset( $loads[$server] ) ) {
 157                                 $loads[$server] = 0;
 158                         }
 159                 }
 160                 foreach ( $loads as $serverName => $load ) {
 161                         $serverInfo = $template;
 162                         if ( $master ) {
 163                                 $serverInfo['master'] = true;
 164                                 if ( isset( $this->masterTemplateOverrides ) ) {
 165                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 166                                 }
 167                                 $master = false;
 168                         }
 169                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 170                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 171                         }
 172                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 173                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 174                         }
 175                         if ( isset( $this->hostsByName[$serverName] ) ) {
 176                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 177                         } else {
 178                                 $serverInfo['host'] = $serverName;
 179                         }
 180                         $serverInfo['hostName'] = $serverName;
 181                         $serverInfo['load'] = $load;
 182                         $servers[] = $serverInfo;
 183                 }
 184                 return $servers;
 185         }
 186
 187         /**
 188          * Take a group load array indexed by group then server, and reindex it by server then group
 189          */
 190         function reindexGroupLoads( $groupLoads ) {
 191                 $reindexed = array();
 192                 foreach ( $groupLoads as $group => $loads ) {
 193                         foreach ( $loads as $server => $load ) {
 194                                 $reindexed[$server][$group] = $load;
 195                         }
 196                 }
 197                 return $reindexed;
 198         }
 199
 200         /**
 201          * Get the database name and prefix based on the wiki ID
 202          */
 203         function getDBNameAndPrefix( $wiki = false ) {
 204                 if ( $wiki === false ) {
 205                         global $wgDBname, $wgDBprefix;
 206                         return array( $wgDBname, $wgDBprefix );
 207                 } else {
 208                         return wfSplitWikiID( $wiki );
 209                 }
 210         }
 211
 212         /**
 213          * Execute a function for each tracked load balancer
 214          * The callback is called with the load balancer as the first parameter,
 215          * and $params passed as the subsequent parameters.
 216          */
 217         function forEachLB( $callback, $params = array() ) {
 218                 foreach ( $this->mainLBs as $lb ) {
 219                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 220                 }
 221                 foreach ( $this->extLBs as $lb ) {
 222                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 223                 }
 224         }
 225
 226         function shutdown() {
 227                 foreach ( $this->mainLBs as $lb ) {
 228                         $this->chronProt->shutdownLB( $lb );
 229                 }
 230                 $this->chronProt->shutdown();
 231                 $this->commitMasterChanges();
 232         }
 233 }