includes/db/LBFactory_Multi.php

   1 <?php
   2 /**
   3  * Advanced generator of database load balancing objects for wiki farms.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23
  24
  25 /**
  26  * A multi-wiki, multi-master factory for Wikimedia and similar installations.
  27  * Ignores the old configuration globals
  28  *
  29  * Configuration:
  30  *     sectionsByDB                A map of database names to section names
  31  *
  32  *     sectionLoads                A 2-d map. For each section, gives a map of server names to load ratios.
  33  *                                 For example: array( 'section1' => array( 'db1' => 100, 'db2' => 100 ) )
  34  *
  35  *     serverTemplate              A server info associative array as documented for $wgDBservers. The host,
  36  *                                 hostName and load entries will be overridden.
  37  *
  38  *     groupLoadsBySection         A 3-d map giving server load ratios for each section and group. For example:
  39  *                                 array( 'section1' => array( 'group1' => array( 'db1' => 100, 'db2' => 100 ) ) )
  40  *
  41  *     groupLoadsByDB              A 3-d map giving server load ratios by DB name.
  42  *
  43  *     hostsByName                 A map of hostname to IP address.
  44  *
  45  *     externalLoads               A map of external storage cluster name to server load map
  46  *
  47  *     externalTemplateOverrides   A set of server info keys overriding serverTemplate for external storage
  48  *
  49  *     templateOverridesByServer   A 2-d map overriding serverTemplate and externalTemplateOverrides on a
  50  *                                 server-by-server basis. Applies to both core and external storage.
  51  *
  52  *     templateOverridesByCluster  A 2-d map overriding the server info by external storage cluster
  53  *
  54  *     masterTemplateOverrides     An override array for all master servers.
  55  *
  56  *     readOnlyBySection           A map of section name to read-only message. Missing or false for read/write.
  57  *
  58  * @ingroup Database
  59  */
  60 class LBFactory_Multi extends LBFactory {
  61         // Required settings
  62         var $sectionsByDB, $sectionLoads, $serverTemplate;
  63         // Optional settings
  64         var $groupLoadsBySection = array(), $groupLoadsByDB = array(), $hostsByName = array();
  65         var $externalLoads = array(), $externalTemplateOverrides, $templateOverridesByServer;
  66         var $templateOverridesByCluster, $masterTemplateOverrides, $readOnlyBySection = array();
  67         // Other stuff
  68         var $conf, $mainLBs = array(), $extLBs = array();
  69         var $lastWiki, $lastSection;
  70
  71         /**
  72          * @param $conf array
  73          */
  74         function __construct( $conf ) {
  75                 $this->chronProt = new ChronologyProtector;
  76                 $this->conf = $conf;
  77                 $required = array( 'sectionsByDB', 'sectionLoads', 'serverTemplate' );
  78                 $optional = array( 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
  79                         'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
  80                         'templateOverridesByCluster', 'masterTemplateOverrides',
  81                         'readOnlyBySection' );
  82
  83                 foreach ( $required as $key ) {
  84                         if ( !isset( $conf[$key] ) ) {
  85                                 throw new MWException( __CLASS__.": $key is required in configuration" );
  86                         }
  87                         $this->$key = $conf[$key];
  88                 }
  89
  90                 foreach ( $optional as $key ) {
  91                         if ( isset( $conf[$key] ) ) {
  92                                 $this->$key = $conf[$key];
  93                         }
  94                 }
  95
  96                 // Check for read-only mode
  97                 $section = $this->getSectionForWiki();
  98                 if ( !empty( $this->readOnlyBySection[$section] ) ) {
  99                         global $wgReadOnly;
 100                         $wgReadOnly = $this->readOnlyBySection[$section];
 101                 }
 102         }
 103
 104         /**
 105          * @param $wiki bool|string
 106          * @return string
 107          */
 108         function getSectionForWiki( $wiki = false ) {
 109                 if ( $this->lastWiki === $wiki ) {
 110                         return $this->lastSection;
 111                 }
 112                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
 113                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
 114                         $section = $this->sectionsByDB[$dbName];
 115                 } else {
 116                         $section = 'DEFAULT';
 117                 }
 118                 $this->lastSection = $section;
 119                 $this->lastWiki = $wiki;
 120                 return $section;
 121         }
 122
 123         /**
 124          * @param $wiki bool|string
 125          * @return LoadBalancer
 126          */
 127         function newMainLB( $wiki = false ) {
 128                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
 129                 $section = $this->getSectionForWiki( $wiki );
 130                 $groupLoads = array();
 131                 if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
 132                         $groupLoads = $this->groupLoadsByDB[$dbName];
 133                 }
 134                 if ( isset( $this->groupLoadsBySection[$section] ) ) {
 135                         $groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
 136                 }
 137                 return $this->newLoadBalancer( $this->serverTemplate, $this->sectionLoads[$section], $groupLoads );
 138         }
 139
 140         /**
 141          * @param $wiki bool|string
 142          * @return LoadBalancer
 143          */
 144         function getMainLB( $wiki = false ) {
 145                 $section = $this->getSectionForWiki( $wiki );
 146                 if ( !isset( $this->mainLBs[$section] ) ) {
 147                         $lb = $this->newMainLB( $wiki, $section );
 148                         $this->chronProt->initLB( $lb );
 149                         $lb->parentInfo( array( 'id' => "main-$section" ) );
 150                         $this->mainLBs[$section] = $lb;
 151                 }
 152                 return $this->mainLBs[$section];
 153         }
 154
 155         /**
 156          * @param $cluster
 157          * @param $wiki
 158          * @return LoadBalancer
 159          */
 160         function newExternalLB( $cluster, $wiki = false ) {
 161                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 162                         throw new MWException( __METHOD__.": Unknown cluster \"$cluster\"" );
 163                 }
 164                 $template = $this->serverTemplate;
 165                 if ( isset( $this->externalTemplateOverrides ) ) {
 166                         $template = $this->externalTemplateOverrides + $template;
 167                 }
 168                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 169                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 170                 }
 171                 return $this->newLoadBalancer( $template, $this->externalLoads[$cluster], array() );
 172         }
 173
 174         /**
 175          * @param $cluster
 176          * @param $wiki
 177          * @return LoadBalancer
 178          */
 179         function &getExternalLB( $cluster, $wiki = false ) {
 180                 if ( !isset( $this->extLBs[$cluster] ) ) {
 181                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $wiki );
 182                         $this->extLBs[$cluster]->parentInfo( array( 'id' => "ext-$cluster" ) );
 183                 }
 184                 return $this->extLBs[$cluster];
 185         }
 186
 187         /**
 188          * Make a new load balancer object based on template and load array
 189          *
 190          * @param $template
 191          * @param $loads array
 192          * @param $groupLoads
 193          * @return LoadBalancer
 194          */
 195         function newLoadBalancer( $template, $loads, $groupLoads ) {
 196                 global $wgMasterWaitTimeout;
 197                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 198                 $lb = new LoadBalancer( array(
 199                         'servers' => $servers,
 200                         'masterWaitTimeout' => $wgMasterWaitTimeout
 201                 ));
 202                 return $lb;
 203         }
 204
 205         /**
 206          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 207          *
 208          * @param $template
 209          * @param $loads array
 210          * @param $groupLoads
 211          * @return array
 212          */
 213         function makeServerArray( $template, $loads, $groupLoads ) {
 214                 $servers = array();
 215                 $master = true;
 216                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 217                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 218                         if ( !isset( $loads[$server] ) ) {
 219                                 $loads[$server] = 0;
 220                         }
 221                 }
 222                 foreach ( $loads as $serverName => $load ) {
 223                         $serverInfo = $template;
 224                         if ( $master ) {
 225                                 $serverInfo['master'] = true;
 226                                 if ( isset( $this->masterTemplateOverrides ) ) {
 227                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 228                                 }
 229                                 $master = false;
 230                         }
 231                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 232                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 233                         }
 234                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 235                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 236                         }
 237                         if ( isset( $this->hostsByName[$serverName] ) ) {
 238                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 239                         } else {
 240                                 $serverInfo['host'] = $serverName;
 241                         }
 242                         $serverInfo['hostName'] = $serverName;
 243                         $serverInfo['load'] = $load;
 244                         $servers[] = $serverInfo;
 245                 }
 246                 return $servers;
 247         }
 248
 249         /**
 250          * Take a group load array indexed by group then server, and reindex it by server then group
 251          * @param $groupLoads
 252          * @return array
 253          */
 254         function reindexGroupLoads( $groupLoads ) {
 255                 $reindexed = array();
 256                 foreach ( $groupLoads as $group => $loads ) {
 257                         foreach ( $loads as $server => $load ) {
 258                                 $reindexed[$server][$group] = $load;
 259                         }
 260                 }
 261                 return $reindexed;
 262         }
 263
 264         /**
 265          * Get the database name and prefix based on the wiki ID
 266          * @param $wiki bool
 267          * @return array
 268          */
 269         function getDBNameAndPrefix( $wiki = false ) {
 270                 if ( $wiki === false ) {
 271                         global $wgDBname, $wgDBprefix;
 272                         return array( $wgDBname, $wgDBprefix );
 273                 } else {
 274                         return wfSplitWikiID( $wiki );
 275                 }
 276         }
 277
 278         /**
 279          * Execute a function for each tracked load balancer
 280          * The callback is called with the load balancer as the first parameter,
 281          * and $params passed as the subsequent parameters.
 282          * @param $callback
 283          * @param $params array
 284          */
 285         function forEachLB( $callback, $params = array() ) {
 286                 foreach ( $this->mainLBs as $lb ) {
 287                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 288                 }
 289                 foreach ( $this->extLBs as $lb ) {
 290                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 291                 }
 292         }
 293
 294         function shutdown() {
 295                 foreach ( $this->mainLBs as $lb ) {
 296                         $this->chronProt->shutdownLB( $lb );
 297                 }
 298                 $this->chronProt->shutdown();
 299                 $this->commitMasterChanges();
 300         }
 301 }