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  *     readOnlyBySection           A map of section name to read-only message. Missing or false for read/write.
  40  *
  41  * @ingroup Database
  42  */
  43 class LBFactory_Multi extends LBFactory {
  44         // Required settings
  45         var $sectionsByDB, $sectionLoads, $serverTemplate;
  46         // Optional settings
  47         var $groupLoadsBySection = array(), $groupLoadsByDB = array(), $hostsByName = array();
  48         var $externalLoads = array(), $externalTemplateOverrides, $templateOverridesByServer;
  49         var $templateOverridesByCluster, $masterTemplateOverrides, $readOnlyBySection = array();
  50         // Other stuff
  51         var $conf, $mainLBs = array(), $extLBs = array();
  52         var $lastWiki, $lastSection;
  53
  54         function __construct( $conf ) {
  55                 $this->chronProt = new ChronologyProtector;
  56                 $this->conf = $conf;
  57                 $required = array( 'sectionsByDB', 'sectionLoads', 'serverTemplate' );
  58                 $optional = array( 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
  59                         'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
  60                         'templateOverridesByCluster', 'masterTemplateOverrides',
  61                         'readOnlyBySection' );
  62
  63                 foreach ( $required as $key ) {
  64                         if ( !isset( $conf[$key] ) ) {
  65                                 throw new MWException( __CLASS__.": $key is required in configuration" );
  66                         }
  67                         $this->$key = $conf[$key];
  68                 }
  69
  70                 foreach ( $optional as $key ) {
  71                         if ( isset( $conf[$key] ) ) {
  72                                 $this->$key = $conf[$key];
  73                         }
  74                 }
  75
  76                 // Check for read-only mode
  77                 $section = $this->getSectionForWiki();
  78                 if ( !empty( $this->readOnlyBySection[$section] ) ) {
  79                         global $wgReadOnly;
  80                         $wgReadOnly = $this->readOnlyBySection[$section];
  81                 }
  82         }
  83
  84         function getSectionForWiki( $wiki = false ) {
  85                 if ( $this->lastWiki === $wiki ) {
  86                         return $this->lastSection;
  87                 }
  88                 list( $dbName, $prefix ) = $this->getDBNameAndPrefix( $wiki );
  89                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
  90                         $section = $this->sectionsByDB[$dbName];
  91                 } else {
  92                         $section = 'DEFAULT';
  93                 }
  94                 $this->lastSection = $section;
  95                 $this->lastWiki = $wiki;
  96                 return $section;
  97         }
  98
  99         function newMainLB( $wiki = false ) {
 100                 list( $dbName, $prefix ) = $this->getDBNameAndPrefix( $wiki );
 101                 $section = $this->getSectionForWiki( $wiki );
 102                 $groupLoads = array();
 103                 if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
 104                         $groupLoads = $this->groupLoadsByDB[$dbName];
 105                 }
 106                 if ( isset( $this->groupLoadsBySection[$section] ) ) {
 107                         $groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
 108                 }
 109                 return $this->newLoadBalancer( $this->serverTemplate, $this->sectionLoads[$section], $groupLoads );
 110         }
 111
 112         function getMainLB( $wiki = false ) {
 113                 $section = $this->getSectionForWiki( $wiki );
 114                 if ( !isset( $this->mainLBs[$section] ) ) {
 115                         $lb = $this->newMainLB( $wiki, $section );
 116                         $this->chronProt->initLB( $lb );
 117                         $lb->parentInfo( array( 'id' => "main-$section" ) );
 118                         $this->mainLBs[$section] = $lb;
 119                 }
 120                 return $this->mainLBs[$section];
 121         }
 122
 123         function newExternalLB( $cluster, $wiki = false ) {
 124                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 125                         throw new MWException( __METHOD__.": Unknown cluster \"$cluster\"" );
 126                 }
 127                 $template = $this->serverTemplate;
 128                 if ( isset( $this->externalTemplateOverrides ) ) {
 129                         $template = $this->externalTemplateOverrides + $template;
 130                 }
 131                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 132                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 133                 }
 134                 return $this->newLoadBalancer( $template, $this->externalLoads[$cluster], array() );
 135         }
 136
 137         function &getExternalLB( $cluster, $wiki = false ) {
 138                 if ( !isset( $this->extLBs[$cluster] ) ) {
 139                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $wiki );
 140                         $this->extLBs[$cluster]->parentInfo( array( 'id' => "ext-$cluster" ) );
 141                 }
 142                 return $this->extLBs[$cluster];
 143         }
 144
 145         /**
 146          * Make a new load balancer object based on template and load array
 147          */
 148         function newLoadBalancer( $template, $loads, $groupLoads ) {
 149                 global $wgMasterWaitTimeout;
 150                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 151                 $lb = new LoadBalancer( array(
 152                         'servers' => $servers,
 153                         'masterWaitTimeout' => $wgMasterWaitTimeout
 154                 ));
 155                 return $lb;
 156         }
 157
 158         /**
 159          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 160          */
 161         function makeServerArray( $template, $loads, $groupLoads ) {
 162                 $servers = array();
 163                 $master = true;
 164                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 165                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 166                         if ( !isset( $loads[$server] ) ) {
 167                                 $loads[$server] = 0;
 168                         }
 169                 }
 170                 foreach ( $loads as $serverName => $load ) {
 171                         $serverInfo = $template;
 172                         if ( $master ) {
 173                                 $serverInfo['master'] = true;
 174                                 if ( isset( $this->masterTemplateOverrides ) ) {
 175                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 176                                 }
 177                                 $master = false;
 178                         }
 179                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 180                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 181                         }
 182                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 183                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 184                         }
 185                         if ( isset( $this->hostsByName[$serverName] ) ) {
 186                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 187                         } else {
 188                                 $serverInfo['host'] = $serverName;
 189                         }
 190                         $serverInfo['hostName'] = $serverName;
 191                         $serverInfo['load'] = $load;
 192                         $servers[] = $serverInfo;
 193                 }
 194                 return $servers;
 195         }
 196
 197         /**
 198          * Take a group load array indexed by group then server, and reindex it by server then group
 199          */
 200         function reindexGroupLoads( $groupLoads ) {
 201                 $reindexed = array();
 202                 foreach ( $groupLoads as $group => $loads ) {
 203                         foreach ( $loads as $server => $load ) {
 204                                 $reindexed[$server][$group] = $load;
 205                         }
 206                 }
 207                 return $reindexed;
 208         }
 209
 210         /**
 211          * Get the database name and prefix based on the wiki ID
 212          */
 213         function getDBNameAndPrefix( $wiki = false ) {
 214                 if ( $wiki === false ) {
 215                         global $wgDBname, $wgDBprefix;
 216                         return array( $wgDBname, $wgDBprefix );
 217                 } else {
 218                         return wfSplitWikiID( $wiki );
 219                 }
 220         }
 221
 222         /**
 223          * Execute a function for each tracked load balancer
 224          * The callback is called with the load balancer as the first parameter,
 225          * and $params passed as the subsequent parameters.
 226          */
 227         function forEachLB( $callback, $params = array() ) {
 228                 foreach ( $this->mainLBs as $lb ) {
 229                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 230                 }
 231                 foreach ( $this->extLBs as $lb ) {
 232                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 233                 }
 234         }
 235
 236         function shutdown() {
 237                 foreach ( $this->mainLBs as $lb ) {
 238                         $this->chronProt->shutdownLB( $lb );
 239                 }
 240                 $this->chronProt->shutdown();
 241                 $this->commitMasterChanges();
 242         }
 243 }