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  *     mainTemplate                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  *     externalTemplate            A server info structure used for external storage servers
  26  *
  27  *     templateOverridesByServer   A 2-d map overriding mainTemplate or externalTemplate on a
  28  *                                 server-by-server basis.
  29  *
  30  *     templateOverridesByCluster  A 2-d map overriding externalTemplate by cluster
  31  *
  32  *     masterTemplateOverrides     An override array for mainTemplate and externalTemplate for all
  33  *                                 master servers.
  34  *
  35  */
  36 class LBFactory_Multi extends LBFactory {
  37         // Required settings
  38         var $sectionsByDB, $sectionLoads, $mainTemplate;
  39         // Optional settings
  40         var $groupLoadsBySection = array(), $groupLoadsByDB = array(), $hostsByName = array();
  41         var $externalLoads = array(), $externalTemplate, $templateOverridesByServer;
  42         var $templateOverridesByCluster, $masterTemplateOverrides;
  43         // Other stuff
  44         var $conf, $mainLBs = array(), $extLBs = array();
  45         var $localSection = null;
  46
  47         function __construct( $conf ) {
  48                 $this->chronProt = new ChronologyProtector;
  49                 $this->conf = $conf;
  50                 $required = array( 'sectionsByDB', 'sectionLoads', 'mainTemplate' );
  51                 $optional = array( 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
  52                         'externalLoads', 'externalTemplate', 'templateOverridesByServer',
  53                         'templateOverridesByCluster', 'masterTemplateOverrides' );
  54
  55                 foreach ( $required as $key ) {
  56                         if ( !isset( $conf[$key] ) ) {
  57                                 throw new MWException( __CLASS__.": $key is required in configuration" );
  58                         }
  59                         $this->$key = $conf[$key];
  60                 }
  61
  62                 foreach ( $optional as $key ) {
  63                         if ( isset( $conf[$key] ) ) {
  64                                 $this->$key = $conf[$key];
  65                         }
  66                 }
  67         }
  68
  69         function getSectionForWiki( $wiki ) {
  70                 list( $dbName, $prefix ) = $this->getDBNameAndPrefix( $wiki );
  71                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
  72                         return $this->sectionsByDB[$dbName];
  73                 } else {
  74                         return 'DEFAULT';
  75                 }
  76         }
  77
  78         function getMainLB( $wiki = false ) {
  79                 // Determine section
  80                 if ( $wiki === false ) {
  81                         if ( $this->localSection === null ) {
  82                                 $this->localSection = $this->getSectionForWiki( $wiki );
  83                         }
  84                         $section = $this->localSection;
  85                 } else {
  86                         $section = $this->getSectionForWiki( $wiki );
  87                 }
  88
  89                 if ( !isset( $this->mainLBs[$section] ) ) {
  90                         list( $dbName, $prefix ) = $this->getDBNameAndPrefix( $wiki );
  91                         $groupLoads = array();
  92                         if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
  93                                 $groupLoads = $this->groupLoadsByDB[$dbName];
  94                         }
  95                         if ( isset( $this->groupLoadsBySection[$section] ) ) {
  96                                 $groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
  97                         }
  98                         $this->mainLBs[$section] = $this->newLoadBalancer( $this->mainTemplate,
  99                                 $this->sectionLoads[$section], $groupLoads, "main-$section" );
 100                         $this->chronProt->initLB( $this->mainLBs[$section] );
 101                 }
 102                 return $this->mainLBs[$section];
 103         }
 104
 105         function &getExternalLB( $cluster, $wiki = false ) {
 106                 if ( !isset( $this->extLBs[$cluster] ) ) {
 107                         if ( !isset( $this->externalLoads[$cluster] ) ) {
 108                                 throw new MWException( __METHOD__.": Unknown cluster \"$cluster\"" );
 109                         }
 110                         if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 111                                 $template = $this->templateOverridesByCluster[$cluster];
 112                         } elseif ( isset( $this->externalTemplate ) ) {
 113                                 $template = $this->externalTemplate;
 114                         } else {
 115                                 $template = $this->mainTemplate;
 116                         }
 117                         $this->extLBs[$cluster] = $this->newLoadBalancer( $template,
 118                                 $this->externalLoads[$cluster], array(), "ext-$cluster" );
 119                 }
 120                 return $this->extLBs[$cluster];
 121         }
 122
 123         /**
 124          * Make a new load balancer object based on template and load array
 125          */
 126         function newLoadBalancer( $template, $loads, $groupLoads, $id ) {
 127                 global $wgMasterWaitTimeout;
 128                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 129                 $lb = new LoadBalancer( $servers, false, $wgMasterWaitTimeout );
 130                 $lb->parentInfo( array( 'id' => $id ) );
 131                 return $lb;
 132         }
 133
 134         /**
 135          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 136          */
 137         function makeServerArray( $template, $loads, $groupLoads ) {
 138                 $servers = array();
 139                 $master = true;
 140                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 141                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 142                         if ( !isset( $loads[$server] ) ) {
 143                                 $loads[$server] = 0;
 144                         }
 145                 }
 146                 foreach ( $loads as $serverName => $load ) {
 147                         $serverInfo = $template;
 148                         if ( $master ) {
 149                                 $serverInfo['master'] = true;
 150                                 if ( isset( $this->masterTemplateOverrides ) ) {
 151                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 152                                 }
 153                                 $master = false;
 154                         }
 155                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 156                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 157                         }
 158                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 159                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 160                         }
 161                         if ( isset( $this->hostsByName[$serverName] ) ) {
 162                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 163                         } else {
 164                                 $serverInfo['host'] = $serverName;
 165                         }
 166                         $serverInfo['hostName'] = $serverName;
 167                         $serverInfo['load'] = $load;
 168                         $servers[] = $serverInfo;
 169                 }
 170                 return $servers;
 171         }
 172
 173         /**
 174          * Take a group load array indexed by group then server, and reindex it by server then group
 175          */
 176         function reindexGroupLoads( $groupLoads ) {
 177                 $reindexed = array();
 178                 foreach ( $groupLoads as $group => $loads ) {
 179                         foreach ( $loads as $server => $load ) {
 180                                 $reindexed[$server][$group] = $load;
 181                         }
 182                 }
 183                 return $reindexed;
 184         }
 185
 186         /**
 187          * Get the database name and prefix based on the wiki ID
 188          */
 189         function getDBNameAndPrefix( $wiki = false ) {
 190                 if ( $wiki === false ) {
 191                         global $wgDBname, $wgDBprefix;
 192                         return array( $wgDBname, $wgDBprefix );
 193                 } else {
 194                         return wfSplitWikiID( $wiki );
 195                 }
 196         }
 197
 198         /**
 199          * Execute a function for each tracked load balancer
 200          * The callback is called with the load balancer as the first parameter,
 201          * and $params passed as the subsequent parameters.
 202          */
 203         function forEachLB( $callback, $params = array() ) {
 204                 foreach ( $this->mainLBs as $lb ) {
 205                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 206                 }
 207                 foreach ( $this->extLBs as $lb ) {
 208                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 209                 }
 210         }
 211
 212         function shutdown() {
 213                 foreach ( $this->mainLBs as $lb ) {
 214                         $this->chronProt->shutdownLB( $lb );
 215                 }
 216                 $this->chronProt->shutdown();
 217                 $this->commitMasterChanges();
 218         }
 219 }
 220