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          * @throws MWException
  74          */
  75         function __construct( $conf ) {
  76                 $this->chronProt = new ChronologyProtector;
  77                 $this->conf = $conf;
  78                 $required = array( 'sectionsByDB', 'sectionLoads', 'serverTemplate' );
  79                 $optional = array( 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
  80                         'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
  81                         'templateOverridesByCluster', 'masterTemplateOverrides',
  82                         'readOnlyBySection' );
  83
  84                 foreach ( $required as $key ) {
  85                         if ( !isset( $conf[$key] ) ) {
  86                                 throw new MWException( __CLASS__.": $key is required in configuration" );
  87                         }
  88                         $this->$key = $conf[$key];
  89                 }
  90
  91                 foreach ( $optional as $key ) {
  92                         if ( isset( $conf[$key] ) ) {
  93                                 $this->$key = $conf[$key];
  94                         }
  95                 }
  96
  97                 // Check for read-only mode
  98                 $section = $this->getSectionForWiki();
  99                 if ( !empty( $this->readOnlyBySection[$section] ) ) {
 100                         global $wgReadOnly;
 101                         $wgReadOnly = $this->readOnlyBySection[$section];
 102                 }
 103         }
 104
 105         /**
 106          * @param $wiki bool|string
 107          * @return string
 108          */
 109         function getSectionForWiki( $wiki = false ) {
 110                 if ( $this->lastWiki === $wiki ) {
 111                         return $this->lastSection;
 112                 }
 113                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
 114                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
 115                         $section = $this->sectionsByDB[$dbName];
 116                 } else {
 117                         $section = 'DEFAULT';
 118                 }
 119                 $this->lastSection = $section;
 120                 $this->lastWiki = $wiki;
 121                 return $section;
 122         }
 123
 124         /**
 125          * @param $wiki bool|string
 126          * @return LoadBalancer
 127          */
 128         function newMainLB( $wiki = false ) {
 129                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
 130                 $section = $this->getSectionForWiki( $wiki );
 131                 $groupLoads = array();
 132                 if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
 133                         $groupLoads = $this->groupLoadsByDB[$dbName];
 134                 }
 135                 if ( isset( $this->groupLoadsBySection[$section] ) ) {
 136                         $groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
 137                 }
 138                 return $this->newLoadBalancer( $this->serverTemplate, $this->sectionLoads[$section], $groupLoads );
 139         }
 140
 141         /**
 142          * @param $wiki bool|string
 143          * @return LoadBalancer
 144          */
 145         function getMainLB( $wiki = false ) {
 146                 $section = $this->getSectionForWiki( $wiki );
 147                 if ( !isset( $this->mainLBs[$section] ) ) {
 148                         $lb = $this->newMainLB( $wiki, $section );
 149                         $this->chronProt->initLB( $lb );
 150                         $lb->parentInfo( array( 'id' => "main-$section" ) );
 151                         $this->mainLBs[$section] = $lb;
 152                 }
 153                 return $this->mainLBs[$section];
 154         }
 155
 156         /**
 157          * @param String $cluster
 158          * @param bool $wiki
 159          * @throws MWException
 160          * @return LoadBalancer
 161          */
 162         function newExternalLB( $cluster, $wiki = false ) {
 163                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 164                         throw new MWException( __METHOD__.": Unknown cluster \"$cluster\"" );
 165                 }
 166                 $template = $this->serverTemplate;
 167                 if ( isset( $this->externalTemplateOverrides ) ) {
 168                         $template = $this->externalTemplateOverrides + $template;
 169                 }
 170                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 171                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 172                 }
 173                 return $this->newLoadBalancer( $template, $this->externalLoads[$cluster], array() );
 174         }
 175
 176         /**
 177          * @param $cluster
 178          * @param $wiki
 179          * @return LoadBalancer
 180          */
 181         function &getExternalLB( $cluster, $wiki = false ) {
 182                 if ( !isset( $this->extLBs[$cluster] ) ) {
 183                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $wiki );
 184                         $this->extLBs[$cluster]->parentInfo( array( 'id' => "ext-$cluster" ) );
 185                 }
 186                 return $this->extLBs[$cluster];
 187         }
 188
 189         /**
 190          * Make a new load balancer object based on template and load array
 191          *
 192          * @param $template
 193          * @param $loads array
 194          * @param $groupLoads
 195          * @return LoadBalancer
 196          */
 197         function newLoadBalancer( $template, $loads, $groupLoads ) {
 198                 global $wgMasterWaitTimeout;
 199                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 200                 $lb = new LoadBalancer( array(
 201                         'servers' => $servers,
 202                         'masterWaitTimeout' => $wgMasterWaitTimeout
 203                 ));
 204                 return $lb;
 205         }
 206
 207         /**
 208          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 209          *
 210          * @param $template
 211          * @param $loads array
 212          * @param $groupLoads
 213          * @return array
 214          */
 215         function makeServerArray( $template, $loads, $groupLoads ) {
 216                 $servers = array();
 217                 $master = true;
 218                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 219                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 220                         if ( !isset( $loads[$server] ) ) {
 221                                 $loads[$server] = 0;
 222                         }
 223                 }
 224                 foreach ( $loads as $serverName => $load ) {
 225                         $serverInfo = $template;
 226                         if ( $master ) {
 227                                 $serverInfo['master'] = true;
 228                                 if ( isset( $this->masterTemplateOverrides ) ) {
 229                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 230                                 }
 231                                 $master = false;
 232                         }
 233                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 234                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 235                         }
 236                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 237                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 238                         }
 239                         if ( isset( $this->hostsByName[$serverName] ) ) {
 240                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 241                         } else {
 242                                 $serverInfo['host'] = $serverName;
 243                         }
 244                         $serverInfo['hostName'] = $serverName;
 245                         $serverInfo['load'] = $load;
 246                         $servers[] = $serverInfo;
 247                 }
 248                 return $servers;
 249         }
 250
 251         /**
 252          * Take a group load array indexed by group then server, and reindex it by server then group
 253          * @param $groupLoads
 254          * @return array
 255          */
 256         function reindexGroupLoads( $groupLoads ) {
 257                 $reindexed = array();
 258                 foreach ( $groupLoads as $group => $loads ) {
 259                         foreach ( $loads as $server => $load ) {
 260                                 $reindexed[$server][$group] = $load;
 261                         }
 262                 }
 263                 return $reindexed;
 264         }
 265
 266         /**
 267          * Get the database name and prefix based on the wiki ID
 268          * @param $wiki bool
 269          * @return array
 270          */
 271         function getDBNameAndPrefix( $wiki = false ) {
 272                 if ( $wiki === false ) {
 273                         global $wgDBname, $wgDBprefix;
 274                         return array( $wgDBname, $wgDBprefix );
 275                 } else {
 276                         return wfSplitWikiID( $wiki );
 277                 }
 278         }
 279
 280         /**
 281          * Execute a function for each tracked load balancer
 282          * The callback is called with the load balancer as the first parameter,
 283          * and $params passed as the subsequent parameters.
 284          * @param $callback
 285          * @param $params array
 286          */
 287         function forEachLB( $callback, $params = array() ) {
 288                 foreach ( $this->mainLBs as $lb ) {
 289                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 290                 }
 291                 foreach ( $this->extLBs as $lb ) {
 292                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 293                 }
 294         }
 295
 296         function shutdown() {
 297                 foreach ( $this->mainLBs as $lb ) {
 298                         $this->chronProt->shutdownLB( $lb );
 299                 }
 300                 $this->chronProt->shutdown();
 301                 $this->commitMasterChanges();
 302         }
 303 }