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  * A multi-wiki, multi-master factory for Wikimedia and similar installations.
  26  * Ignores the old configuration globals
  27  *
  28  * Configuration:
  29  *     sectionsByDB                A map of database names to section names
  30  *
  31  *     sectionLoads                A 2-d map. For each section, gives a map of server names to load ratios.
  32  *                                 For example: array( 'section1' => array( 'db1' => 100, 'db2' => 100 ) )
  33  *
  34  *     serverTemplate              A server info associative array as documented for $wgDBservers. The host,
  35  *                                 hostName and load entries will be overridden.
  36  *
  37  *     groupLoadsBySection         A 3-d map giving server load ratios for each section and group. For example:
  38  *                                 array( 'section1' => array( 'group1' => array( 'db1' => 100, 'db2' => 100 ) ) )
  39  *
  40  *     groupLoadsByDB              A 3-d map giving server load ratios by DB name.
  41  *
  42  *     hostsByName                 A map of hostname to IP address.
  43  *
  44  *     externalLoads               A map of external storage cluster name to server load map
  45  *
  46  *     externalTemplateOverrides   A set of server info keys overriding serverTemplate for external storage
  47  *
  48  *     templateOverridesByServer   A 2-d map overriding serverTemplate and externalTemplateOverrides on a
  49  *                                 server-by-server basis. Applies to both core and external storage.
  50  *
  51  *     templateOverridesByCluster  A 2-d map overriding the server info by external storage cluster
  52  *
  53  *     masterTemplateOverrides     An override array for all master servers.
  54  *
  55  *     readOnlyBySection           A map of section name to read-only message. Missing or false for read/write.
  56  *
  57  * @ingroup Database
  58  */
  59 class LBFactory_Multi extends LBFactory {
  60         // Required settings
  61         var $sectionsByDB, $sectionLoads, $serverTemplate;
  62         // Optional settings
  63         var $groupLoadsBySection = array(), $groupLoadsByDB = array(), $hostsByName = array();
  64         var $externalLoads = array(), $externalTemplateOverrides, $templateOverridesByServer;
  65         var $templateOverridesByCluster, $masterTemplateOverrides, $readOnlyBySection = array();
  66         // Other stuff
  67         var $conf, $mainLBs = array(), $extLBs = array();
  68         var $lastWiki, $lastSection;
  69
  70         /**
  71          * @param $conf array
  72          * @throws MWException
  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
 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
 139                 return $this->newLoadBalancer( $this->serverTemplate, $this->sectionLoads[$section], $groupLoads );
 140         }
 141
 142         /**
 143          * @param $wiki bool|string
 144          * @return LoadBalancer
 145          */
 146         function getMainLB( $wiki = false ) {
 147                 $section = $this->getSectionForWiki( $wiki );
 148                 if ( !isset( $this->mainLBs[$section] ) ) {
 149                         $lb = $this->newMainLB( $wiki, $section );
 150                         $lb->parentInfo( array( 'id' => "main-$section" ) );
 151                         $this->chronProt->initLB( $lb );
 152                         $this->mainLBs[$section] = $lb;
 153                 }
 154
 155                 return $this->mainLBs[$section];
 156         }
 157
 158         /**
 159          * @param string $cluster
 160          * @param bool $wiki
 161          * @throws MWException
 162          * @return LoadBalancer
 163          */
 164         function newExternalLB( $cluster, $wiki = false ) {
 165                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 166                         throw new MWException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
 167                 }
 168                 $template = $this->serverTemplate;
 169                 if ( isset( $this->externalTemplateOverrides ) ) {
 170                         $template = $this->externalTemplateOverrides + $template;
 171                 }
 172                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 173                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 174                 }
 175
 176                 return $this->newLoadBalancer( $template, $this->externalLoads[$cluster], array() );
 177         }
 178
 179         /**
 180          * @param $cluster
 181          * @param $wiki
 182          * @return LoadBalancer
 183          */
 184         function &getExternalLB( $cluster, $wiki = false ) {
 185                 if ( !isset( $this->extLBs[$cluster] ) ) {
 186                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $wiki );
 187                         $this->extLBs[$cluster]->parentInfo( array( 'id' => "ext-$cluster" ) );
 188                         $this->chronProt->initLB( $this->extLBs[$cluster] );
 189                 }
 190
 191                 return $this->extLBs[$cluster];
 192         }
 193
 194         /**
 195          * Make a new load balancer object based on template and load array
 196          *
 197          * @param $template
 198          * @param $loads array
 199          * @param $groupLoads
 200          * @return LoadBalancer
 201          */
 202         function newLoadBalancer( $template, $loads, $groupLoads ) {
 203                 global $wgMasterWaitTimeout;
 204                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 205                 $lb = new LoadBalancer( array(
 206                         'servers' => $servers,
 207                         'masterWaitTimeout' => $wgMasterWaitTimeout
 208                 ) );
 209
 210                 return $lb;
 211         }
 212
 213         /**
 214          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 215          *
 216          * @param $template
 217          * @param $loads array
 218          * @param $groupLoads
 219          * @return array
 220          */
 221         function makeServerArray( $template, $loads, $groupLoads ) {
 222                 $servers = array();
 223                 $master = true;
 224                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 225                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 226                         if ( !isset( $loads[$server] ) ) {
 227                                 $loads[$server] = 0;
 228                         }
 229                 }
 230                 foreach ( $loads as $serverName => $load ) {
 231                         $serverInfo = $template;
 232                         if ( $master ) {
 233                                 $serverInfo['master'] = true;
 234                                 if ( isset( $this->masterTemplateOverrides ) ) {
 235                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 236                                 }
 237                                 $master = false;
 238                         }
 239                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 240                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 241                         }
 242                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 243                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 244                         }
 245                         if ( isset( $this->hostsByName[$serverName] ) ) {
 246                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 247                         } else {
 248                                 $serverInfo['host'] = $serverName;
 249                         }
 250                         $serverInfo['hostName'] = $serverName;
 251                         $serverInfo['load'] = $load;
 252                         $servers[] = $serverInfo;
 253                 }
 254
 255                 return $servers;
 256         }
 257
 258         /**
 259          * Take a group load array indexed by group then server, and reindex it by server then group
 260          * @param $groupLoads
 261          * @return array
 262          */
 263         function reindexGroupLoads( $groupLoads ) {
 264                 $reindexed = array();
 265                 foreach ( $groupLoads as $group => $loads ) {
 266                         foreach ( $loads as $server => $load ) {
 267                                 $reindexed[$server][$group] = $load;
 268                         }
 269                 }
 270
 271                 return $reindexed;
 272         }
 273
 274         /**
 275          * Get the database name and prefix based on the wiki ID
 276          * @param $wiki bool
 277          * @return array
 278          */
 279         function getDBNameAndPrefix( $wiki = false ) {
 280                 if ( $wiki === false ) {
 281                         global $wgDBname, $wgDBprefix;
 282
 283                         return array( $wgDBname, $wgDBprefix );
 284                 } else {
 285                         return wfSplitWikiID( $wiki );
 286                 }
 287         }
 288
 289         /**
 290          * Execute a function for each tracked load balancer
 291          * The callback is called with the load balancer as the first parameter,
 292          * and $params passed as the subsequent parameters.
 293          * @param $callback
 294          * @param $params array
 295          */
 296         function forEachLB( $callback, $params = array() ) {
 297                 foreach ( $this->mainLBs as $lb ) {
 298                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 299                 }
 300                 foreach ( $this->extLBs as $lb ) {
 301                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 302                 }
 303         }
 304
 305         function shutdown() {
 306                 foreach ( $this->mainLBs as $lb ) {
 307                         $this->chronProt->shutdownLB( $lb );
 308                 }
 309                 foreach ( $this->extLBs as $extLB ) {
 310                         $this->chronProt->shutdownLB( $extLB );
 311                 }
 312                 $this->chronProt->shutdown();
 313                 $this->commitMasterChanges();
 314         }
 315 }