includes/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 $localSection = null;
  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 ) {
  75                 list( $dbName, $prefix ) = $this->getDBNameAndPrefix( $wiki );
  76                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
  77                         return $this->sectionsByDB[$dbName];
  78                 } else {
  79                         return 'DEFAULT';
  80                 }
  81         }
  82
  83         function getMainLB( $wiki = false ) {
  84                 // Determine section
  85                 if ( $wiki === false ) {
  86                         if ( $this->localSection === null ) {
  87                                 $this->localSection = $this->getSectionForWiki( $wiki );
  88                         }
  89                         $section = $this->localSection;
  90                 } else {
  91                         $section = $this->getSectionForWiki( $wiki );
  92                 }
  93
  94                 if ( !isset( $this->mainLBs[$section] ) ) {
  95                         list( $dbName, $prefix ) = $this->getDBNameAndPrefix( $wiki );
  96                         $groupLoads = array();
  97                         if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
  98                                 $groupLoads = $this->groupLoadsByDB[$dbName];
  99                         }
 100                         if ( isset( $this->groupLoadsBySection[$section] ) ) {
 101                                 $groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
 102                         }
 103                         $this->mainLBs[$section] = $this->newLoadBalancer( $this->serverTemplate,
 104                                 $this->sectionLoads[$section], $groupLoads, "main-$section" );
 105                         $this->chronProt->initLB( $this->mainLBs[$section] );
 106                 }
 107                 return $this->mainLBs[$section];
 108         }
 109
 110         function &getExternalLB( $cluster, $wiki = false ) {
 111                 if ( !isset( $this->extLBs[$cluster] ) ) {
 112                         if ( !isset( $this->externalLoads[$cluster] ) ) {
 113                                 throw new MWException( __METHOD__.": Unknown cluster \"$cluster\"" );
 114                         }
 115                         $template = $this->serverTemplate;
 116                         if ( isset( $this->externalTemplateOverrides ) ) {
 117                                 $template = $this->externalTemplateOverrides + $template;
 118                         }
 119                         if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 120                                 $template = $this->templateOverridesByCluster[$cluster] + $template;
 121                         }
 122                         $this->extLBs[$cluster] = $this->newLoadBalancer( $template,
 123                                 $this->externalLoads[$cluster], array(), "ext-$cluster" );
 124                 }
 125                 return $this->extLBs[$cluster];
 126         }
 127
 128         /**
 129          * Make a new load balancer object based on template and load array
 130          */
 131         function newLoadBalancer( $template, $loads, $groupLoads, $id ) {
 132                 global $wgMasterWaitTimeout;
 133                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 134                 $lb = new LoadBalancer( $servers, false, $wgMasterWaitTimeout );
 135                 $lb->parentInfo( array( 'id' => $id ) );
 136                 return $lb;
 137         }
 138
 139         /**
 140          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 141          */
 142         function makeServerArray( $template, $loads, $groupLoads ) {
 143                 $servers = array();
 144                 $master = true;
 145                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 146                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 147                         if ( !isset( $loads[$server] ) ) {
 148                                 $loads[$server] = 0;
 149                         }
 150                 }
 151                 foreach ( $loads as $serverName => $load ) {
 152                         $serverInfo = $template;
 153                         if ( $master ) {
 154                                 $serverInfo['master'] = true;
 155                                 if ( isset( $this->masterTemplateOverrides ) ) {
 156                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 157                                 }
 158                                 $master = false;
 159                         }
 160                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 161                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 162                         }
 163                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 164                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 165                         }
 166                         if ( isset( $this->hostsByName[$serverName] ) ) {
 167                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 168                         } else {
 169                                 $serverInfo['host'] = $serverName;
 170                         }
 171                         $serverInfo['hostName'] = $serverName;
 172                         $serverInfo['load'] = $load;
 173                         $servers[] = $serverInfo;
 174                 }
 175                 return $servers;
 176         }
 177
 178         /**
 179          * Take a group load array indexed by group then server, and reindex it by server then group
 180          */
 181         function reindexGroupLoads( $groupLoads ) {
 182                 $reindexed = array();
 183                 foreach ( $groupLoads as $group => $loads ) {
 184                         foreach ( $loads as $server => $load ) {
 185                                 $reindexed[$server][$group] = $load;
 186                         }
 187                 }
 188                 return $reindexed;
 189         }
 190
 191         /**
 192          * Get the database name and prefix based on the wiki ID
 193          */
 194         function getDBNameAndPrefix( $wiki = false ) {
 195                 if ( $wiki === false ) {
 196                         global $wgDBname, $wgDBprefix;
 197                         return array( $wgDBname, $wgDBprefix );
 198                 } else {
 199                         return wfSplitWikiID( $wiki );
 200                 }
 201         }
 202
 203         /**
 204          * Execute a function for each tracked load balancer
 205          * The callback is called with the load balancer as the first parameter,
 206          * and $params passed as the subsequent parameters.
 207          */
 208         function forEachLB( $callback, $params = array() ) {
 209                 foreach ( $this->mainLBs as $lb ) {
 210                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 211                 }
 212                 foreach ( $this->extLBs as $lb ) {
 213                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 214                 }
 215         }
 216
 217         function shutdown() {
 218                 foreach ( $this->mainLBs as $lb ) {
 219                         $this->chronProt->shutdownLB( $lb );
 220                 }
 221                 $this->chronProt->shutdown();
 222                 $this->commitMasterChanges();
 223         }
 224 }