includes/db/LBFactory_Multi.php

   1 <?php
   2 /**
   3  * Advanced generator of database load balancing objects for wiki farms
   4  *
   5  * @file
   6  * @ingroup Database
   7  */
   8
   9
  10 /**
  11  * A multi-wiki, multi-master factory for Wikimedia and similar installations.
  12  * Ignores the old configuration globals
  13  *
  14  * Configuration:
  15  *     sectionsByDB                A map of database names to section names
  16  *
  17  *     sectionLoads                A 2-d map. For each section, gives a map of server names to load ratios.
  18  *                                 For example: array( 'section1' => array( 'db1' => 100, 'db2' => 100 ) )
  19  *
  20  *     serverTemplate              A server info associative array as documented for $wgDBservers. The host,
  21  *                                 hostName and load entries will be overridden.
  22  *
  23  *     groupLoadsBySection         A 3-d map giving server load ratios for each section and group. For example:
  24  *                                 array( 'section1' => array( 'group1' => array( 'db1' => 100, 'db2' => 100 ) ) )
  25  *
  26  *     groupLoadsByDB              A 3-d map giving server load ratios by DB name.
  27  *
  28  *     hostsByName                 A map of hostname to IP address.
  29  *
  30  *     externalLoads               A map of external storage cluster name to server load map
  31  *
  32  *     externalTemplateOverrides   A set of server info keys overriding serverTemplate for external storage
  33  *
  34  *     templateOverridesByServer   A 2-d map overriding serverTemplate and externalTemplateOverrides on a
  35  *                                 server-by-server basis. Applies to both core and external storage.
  36  *
  37  *     templateOverridesByCluster  A 2-d map overriding the server info by external storage cluster
  38  *
  39  *     masterTemplateOverrides     An override array for all master servers.
  40  *
  41  *     readOnlyBySection           A map of section name to read-only message. Missing or false for read/write.
  42  *
  43  * @ingroup Database
  44  */
  45 class LBFactory_Multi extends LBFactory {
  46         // Required settings
  47         var $sectionsByDB, $sectionLoads, $serverTemplate;
  48         // Optional settings
  49         var $groupLoadsBySection = array(), $groupLoadsByDB = array(), $hostsByName = array();
  50         var $externalLoads = array(), $externalTemplateOverrides, $templateOverridesByServer;
  51         var $templateOverridesByCluster, $masterTemplateOverrides, $readOnlyBySection = array();
  52         // Other stuff
  53         var $conf, $mainLBs = array(), $extLBs = array();
  54         var $lastWiki, $lastSection;
  55
  56         /**
  57          * @param $conf array
  58          */
  59         function __construct( $conf ) {
  60                 $this->chronProt = new ChronologyProtector;
  61                 $this->conf = $conf;
  62                 $required = array( 'sectionsByDB', 'sectionLoads', 'serverTemplate' );
  63                 $optional = array( 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
  64                         'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
  65                         'templateOverridesByCluster', 'masterTemplateOverrides',
  66                         'readOnlyBySection' );
  67
  68                 foreach ( $required as $key ) {
  69                         if ( !isset( $conf[$key] ) ) {
  70                                 throw new MWException( __CLASS__.": $key is required in configuration" );
  71                         }
  72                         $this->$key = $conf[$key];
  73                 }
  74
  75                 foreach ( $optional as $key ) {
  76                         if ( isset( $conf[$key] ) ) {
  77                                 $this->$key = $conf[$key];
  78                         }
  79                 }
  80
  81                 // Check for read-only mode
  82                 $section = $this->getSectionForWiki();
  83                 if ( !empty( $this->readOnlyBySection[$section] ) ) {
  84                         global $wgReadOnly;
  85                         $wgReadOnly = $this->readOnlyBySection[$section];
  86                 }
  87         }
  88
  89         /**
  90          * @param $wiki bool|string
  91          * @return string
  92          */
  93         function getSectionForWiki( $wiki = false ) {
  94                 if ( $this->lastWiki === $wiki ) {
  95                         return $this->lastSection;
  96                 }
  97                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
  98                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
  99                         $section = $this->sectionsByDB[$dbName];
 100                 } else {
 101                         $section = 'DEFAULT';
 102                 }
 103                 $this->lastSection = $section;
 104                 $this->lastWiki = $wiki;
 105                 return $section;
 106         }
 107
 108         /**
 109          * @param $wiki bool|string
 110          * @return LoadBalancer
 111          */
 112         function newMainLB( $wiki = false ) {
 113                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
 114                 $section = $this->getSectionForWiki( $wiki );
 115                 $groupLoads = array();
 116                 if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
 117                         $groupLoads = $this->groupLoadsByDB[$dbName];
 118                 }
 119                 if ( isset( $this->groupLoadsBySection[$section] ) ) {
 120                         $groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
 121                 }
 122                 return $this->newLoadBalancer( $this->serverTemplate, $this->sectionLoads[$section], $groupLoads );
 123         }
 124
 125         /**
 126          * @param $wiki bool|string
 127          * @return LoadBalancer
 128          */
 129         function getMainLB( $wiki = false ) {
 130                 $section = $this->getSectionForWiki( $wiki );
 131                 if ( !isset( $this->mainLBs[$section] ) ) {
 132                         $lb = $this->newMainLB( $wiki, $section );
 133                         $this->chronProt->initLB( $lb );
 134                         $lb->parentInfo( array( 'id' => "main-$section" ) );
 135                         $this->mainLBs[$section] = $lb;
 136                 }
 137                 return $this->mainLBs[$section];
 138         }
 139
 140         /**
 141          * @param $cluster
 142          * @param $wiki
 143          * @return LoadBalancer
 144          */
 145         function newExternalLB( $cluster, $wiki = false ) {
 146                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 147                         throw new MWException( __METHOD__.": Unknown cluster \"$cluster\"" );
 148                 }
 149                 $template = $this->serverTemplate;
 150                 if ( isset( $this->externalTemplateOverrides ) ) {
 151                         $template = $this->externalTemplateOverrides + $template;
 152                 }
 153                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 154                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 155                 }
 156                 return $this->newLoadBalancer( $template, $this->externalLoads[$cluster], array() );
 157         }
 158
 159         /**
 160          * @param $cluster
 161          * @param $wiki
 162          * @return LoadBalancer
 163          */
 164         function &getExternalLB( $cluster, $wiki = false ) {
 165                 if ( !isset( $this->extLBs[$cluster] ) ) {
 166                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $wiki );
 167                         $this->extLBs[$cluster]->parentInfo( array( 'id' => "ext-$cluster" ) );
 168                 }
 169                 return $this->extLBs[$cluster];
 170         }
 171
 172         /**
 173          * Make a new load balancer object based on template and load array
 174          *
 175          * @param $template
 176          * @param $loads array
 177          * @param $groupLoads
 178          * @return LoadBalancer
 179          */
 180         function newLoadBalancer( $template, $loads, $groupLoads ) {
 181                 global $wgMasterWaitTimeout;
 182                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 183                 $lb = new LoadBalancer( array(
 184                         'servers' => $servers,
 185                         'masterWaitTimeout' => $wgMasterWaitTimeout
 186                 ));
 187                 return $lb;
 188         }
 189
 190         /**
 191          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 192          *
 193          * @param $template
 194          * @param $loads array
 195          * @param $groupLoads
 196          * @return array
 197          */
 198         function makeServerArray( $template, $loads, $groupLoads ) {
 199                 $servers = array();
 200                 $master = true;
 201                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 202                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 203                         if ( !isset( $loads[$server] ) ) {
 204                                 $loads[$server] = 0;
 205                         }
 206                 }
 207                 foreach ( $loads as $serverName => $load ) {
 208                         $serverInfo = $template;
 209                         if ( $master ) {
 210                                 $serverInfo['master'] = true;
 211                                 if ( isset( $this->masterTemplateOverrides ) ) {
 212                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 213                                 }
 214                                 $master = false;
 215                         }
 216                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 217                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 218                         }
 219                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 220                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 221                         }
 222                         if ( isset( $this->hostsByName[$serverName] ) ) {
 223                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 224                         } else {
 225                                 $serverInfo['host'] = $serverName;
 226                         }
 227                         $serverInfo['hostName'] = $serverName;
 228                         $serverInfo['load'] = $load;
 229                         $servers[] = $serverInfo;
 230                 }
 231                 return $servers;
 232         }
 233
 234         /**
 235          * Take a group load array indexed by group then server, and reindex it by server then group
 236          * @param $groupLoads
 237          * @return array
 238          */
 239         function reindexGroupLoads( $groupLoads ) {
 240                 $reindexed = array();
 241                 foreach ( $groupLoads as $group => $loads ) {
 242                         foreach ( $loads as $server => $load ) {
 243                                 $reindexed[$server][$group] = $load;
 244                         }
 245                 }
 246                 return $reindexed;
 247         }
 248
 249         /**
 250          * Get the database name and prefix based on the wiki ID
 251          * @param $wiki bool
 252          * @return array
 253          */
 254         function getDBNameAndPrefix( $wiki = false ) {
 255                 if ( $wiki === false ) {
 256                         global $wgDBname, $wgDBprefix;
 257                         return array( $wgDBname, $wgDBprefix );
 258                 } else {
 259                         return wfSplitWikiID( $wiki );
 260                 }
 261         }
 262
 263         /**
 264          * Execute a function for each tracked load balancer
 265          * The callback is called with the load balancer as the first parameter,
 266          * and $params passed as the subsequent parameters.
 267          * @param $callback
 268          * @param $params array
 269          */
 270         function forEachLB( $callback, $params = array() ) {
 271                 foreach ( $this->mainLBs as $lb ) {
 272                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 273                 }
 274                 foreach ( $this->extLBs as $lb ) {
 275                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 276                 }
 277         }
 278
 279         function shutdown() {
 280                 foreach ( $this->mainLBs as $lb ) {
 281                         $this->chronProt->shutdownLB( $lb );
 282                 }
 283                 $this->chronProt->shutdown();
 284                 $this->commitMasterChanges();
 285         }
 286 }