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
  32  *                                 load ratios. For example:
  33  *                                 array(
  34  *                                     'section1' => array(
  35  *                                         'db1' => 100,
  36  *                                         'db2' => 100
  37  *                                     )
  38  *                                 )
  39  *
  40  *     serverTemplate              A server info associative array as documented for $wgDBservers.
  41  *                                 The host, hostName and load entries will be overridden.
  42  *
  43  *     groupLoadsBySection         A 3-d map giving server load ratios for each section and group.
  44  *                                 For example:
  45  *                                 array(
  46  *                                     'section1' => array(
  47  *                                         'group1' => array(
  48  *                                             'db1' => 100,
  49  *                                             'db2' => 100
  50  *                                         )
  51  *                                     )
  52  *                                 )
  53  *
  54  *     groupLoadsByDB              A 3-d map giving server load ratios by DB name.
  55  *
  56  *     hostsByName                 A map of hostname to IP address.
  57  *
  58  *     externalLoads               A map of external storage cluster name to server load map
  59  *
  60  *     externalTemplateOverrides   A set of server info keys overriding serverTemplate for external
  61  *                                 storage
  62  *
  63  *     templateOverridesByServer   A 2-d map overriding serverTemplate and
  64  *                                 externalTemplateOverrides on a server-by-server basis. Applies
  65  *                                 to both core and external storage.
  66  *
  67  *     templateOverridesByCluster  A 2-d map overriding the server info by external storage cluster
  68  *
  69  *     masterTemplateOverrides     An override array for all master servers.
  70  *
  71  *     readOnlyBySection           A map of section name to read-only message.
  72  *                                 Missing or false for read/write.
  73  *
  74  * @ingroup Database
  75  */
  76 class LBFactory_Multi extends LBFactory {
  77         // Required settings
  78         var $sectionsByDB, $sectionLoads, $serverTemplate;
  79         // Optional settings
  80         var $groupLoadsBySection = array(), $groupLoadsByDB = array(), $hostsByName = array();
  81         var $externalLoads = array(), $externalTemplateOverrides, $templateOverridesByServer;
  82         var $templateOverridesByCluster, $masterTemplateOverrides, $readOnlyBySection = array();
  83         // Other stuff
  84         var $conf, $mainLBs = array(), $extLBs = array();
  85         var $lastWiki, $lastSection;
  86
  87         /**
  88          * @param $conf array
  89          * @throws MWException
  90          */
  91         function __construct( $conf ) {
  92                 $this->chronProt = new ChronologyProtector;
  93                 $this->conf = $conf;
  94                 $required = array( 'sectionsByDB', 'sectionLoads', 'serverTemplate' );
  95                 $optional = array( 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
  96                         'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
  97                         'templateOverridesByCluster', 'masterTemplateOverrides',
  98                         'readOnlyBySection' );
  99
 100                 foreach ( $required as $key ) {
 101                         if ( !isset( $conf[$key] ) ) {
 102                                 throw new MWException( __CLASS__ . ": $key is required in configuration" );
 103                         }
 104                         $this->$key = $conf[$key];
 105                 }
 106
 107                 foreach ( $optional as $key ) {
 108                         if ( isset( $conf[$key] ) ) {
 109                                 $this->$key = $conf[$key];
 110                         }
 111                 }
 112
 113                 // Check for read-only mode
 114                 $section = $this->getSectionForWiki();
 115                 if ( !empty( $this->readOnlyBySection[$section] ) ) {
 116                         global $wgReadOnly;
 117                         $wgReadOnly = $this->readOnlyBySection[$section];
 118                 }
 119         }
 120
 121         /**
 122          * @param $wiki bool|string
 123          * @return string
 124          */
 125         function getSectionForWiki( $wiki = false ) {
 126                 if ( $this->lastWiki === $wiki ) {
 127                         return $this->lastSection;
 128                 }
 129                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
 130                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
 131                         $section = $this->sectionsByDB[$dbName];
 132                 } else {
 133                         $section = 'DEFAULT';
 134                 }
 135                 $this->lastSection = $section;
 136                 $this->lastWiki = $wiki;
 137
 138                 return $section;
 139         }
 140
 141         /**
 142          * @param $wiki bool|string
 143          * @return LoadBalancer
 144          */
 145         function newMainLB( $wiki = false ) {
 146                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
 147                 $section = $this->getSectionForWiki( $wiki );
 148                 $groupLoads = array();
 149                 if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
 150                         $groupLoads = $this->groupLoadsByDB[$dbName];
 151                 }
 152
 153                 if ( isset( $this->groupLoadsBySection[$section] ) ) {
 154                         $groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
 155                 }
 156
 157                 return $this->newLoadBalancer(
 158                         $this->serverTemplate,
 159                         $this->sectionLoads[$section],
 160                         $groupLoads
 161                 );
 162         }
 163
 164         /**
 165          * @param $wiki bool|string
 166          * @return LoadBalancer
 167          */
 168         function getMainLB( $wiki = false ) {
 169                 $section = $this->getSectionForWiki( $wiki );
 170                 if ( !isset( $this->mainLBs[$section] ) ) {
 171                         $lb = $this->newMainLB( $wiki, $section );
 172                         $lb->parentInfo( array( 'id' => "main-$section" ) );
 173                         $this->chronProt->initLB( $lb );
 174                         $this->mainLBs[$section] = $lb;
 175                 }
 176
 177                 return $this->mainLBs[$section];
 178         }
 179
 180         /**
 181          * @param string $cluster
 182          * @param bool $wiki
 183          * @throws MWException
 184          * @return LoadBalancer
 185          */
 186         function newExternalLB( $cluster, $wiki = false ) {
 187                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 188                         throw new MWException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
 189                 }
 190                 $template = $this->serverTemplate;
 191                 if ( isset( $this->externalTemplateOverrides ) ) {
 192                         $template = $this->externalTemplateOverrides + $template;
 193                 }
 194                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 195                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 196                 }
 197
 198                 return $this->newLoadBalancer( $template, $this->externalLoads[$cluster], array() );
 199         }
 200
 201         /**
 202          * @param $cluster
 203          * @param $wiki
 204          * @return LoadBalancer
 205          */
 206         function &getExternalLB( $cluster, $wiki = false ) {
 207                 if ( !isset( $this->extLBs[$cluster] ) ) {
 208                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $wiki );
 209                         $this->extLBs[$cluster]->parentInfo( array( 'id' => "ext-$cluster" ) );
 210                         $this->chronProt->initLB( $this->extLBs[$cluster] );
 211                 }
 212
 213                 return $this->extLBs[$cluster];
 214         }
 215
 216         /**
 217          * Make a new load balancer object based on template and load array
 218          *
 219          * @param $template
 220          * @param $loads array
 221          * @param $groupLoads
 222          * @return LoadBalancer
 223          */
 224         function newLoadBalancer( $template, $loads, $groupLoads ) {
 225                 global $wgMasterWaitTimeout;
 226                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 227                 $lb = new LoadBalancer( array(
 228                         'servers' => $servers,
 229                         'masterWaitTimeout' => $wgMasterWaitTimeout
 230                 ) );
 231
 232                 return $lb;
 233         }
 234
 235         /**
 236          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 237          *
 238          * @param $template
 239          * @param $loads array
 240          * @param $groupLoads
 241          * @return array
 242          */
 243         function makeServerArray( $template, $loads, $groupLoads ) {
 244                 $servers = array();
 245                 $master = true;
 246                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 247                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 248                         if ( !isset( $loads[$server] ) ) {
 249                                 $loads[$server] = 0;
 250                         }
 251                 }
 252                 foreach ( $loads as $serverName => $load ) {
 253                         $serverInfo = $template;
 254                         if ( $master ) {
 255                                 $serverInfo['master'] = true;
 256                                 if ( isset( $this->masterTemplateOverrides ) ) {
 257                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 258                                 }
 259                                 $master = false;
 260                         }
 261                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 262                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 263                         }
 264                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 265                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 266                         }
 267                         if ( isset( $this->hostsByName[$serverName] ) ) {
 268                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 269                         } else {
 270                                 $serverInfo['host'] = $serverName;
 271                         }
 272                         $serverInfo['hostName'] = $serverName;
 273                         $serverInfo['load'] = $load;
 274                         $servers[] = $serverInfo;
 275                 }
 276
 277                 return $servers;
 278         }
 279
 280         /**
 281          * Take a group load array indexed by group then server, and reindex it by server then group
 282          * @param $groupLoads
 283          * @return array
 284          */
 285         function reindexGroupLoads( $groupLoads ) {
 286                 $reindexed = array();
 287                 foreach ( $groupLoads as $group => $loads ) {
 288                         foreach ( $loads as $server => $load ) {
 289                                 $reindexed[$server][$group] = $load;
 290                         }
 291                 }
 292
 293                 return $reindexed;
 294         }
 295
 296         /**
 297          * Get the database name and prefix based on the wiki ID
 298          * @param $wiki bool
 299          * @return array
 300          */
 301         function getDBNameAndPrefix( $wiki = false ) {
 302                 if ( $wiki === false ) {
 303                         global $wgDBname, $wgDBprefix;
 304
 305                         return array( $wgDBname, $wgDBprefix );
 306                 } else {
 307                         return wfSplitWikiID( $wiki );
 308                 }
 309         }
 310
 311         /**
 312          * Execute a function for each tracked load balancer
 313          * The callback is called with the load balancer as the first parameter,
 314          * and $params passed as the subsequent parameters.
 315          * @param $callback
 316          * @param $params array
 317          */
 318         function forEachLB( $callback, $params = array() ) {
 319                 foreach ( $this->mainLBs as $lb ) {
 320                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 321                 }
 322                 foreach ( $this->extLBs as $lb ) {
 323                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 324                 }
 325         }
 326
 327         function shutdown() {
 328                 foreach ( $this->mainLBs as $lb ) {
 329                         $this->chronProt->shutdownLB( $lb );
 330                 }
 331                 foreach ( $this->extLBs as $extLB ) {
 332                         $this->chronProt->shutdownLB( $extLB );
 333                 }
 334                 $this->chronProt->shutdown();
 335                 $this->commitMasterChanges();
 336         }
 337 }