includes/LBFactory_Multi.php

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