includes/db/LBFactoryMulti.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 LBFactoryMulti extends LBFactory {
  77         // Required settings
  78
  79         /** @var array A map of database names to section names */
  80         protected $sectionsByDB;
  81
  82         /**
  83          * @var array A 2-d map. For each section, gives a map of server names to
  84          * load ratios
  85          */
  86         protected $sectionLoads;
  87
  88         /**
  89          * @var array A server info associative array as documented for
  90          * $wgDBservers. The host, hostName and load entries will be
  91          * overridden
  92          */
  93         protected $serverTemplate;
  94
  95         // Optional settings
  96
  97         /** @var array A 3-d map giving server load ratios for each section and group */
  98         protected $groupLoadsBySection = array();
  99
 100         /** @var array A 3-d map giving server load ratios by DB name */
 101         protected $groupLoadsByDB = array();
 102
 103         /** @var array A map of hostname to IP address */
 104         protected $hostsByName = array();
 105
 106         /** @var array A map of external storage cluster name to server load map */
 107         protected $externalLoads = array();
 108
 109         /**
 110          * @var array A set of server info keys overriding serverTemplate for
 111          * external storage
 112          */
 113         protected $externalTemplateOverrides;
 114
 115         /**
 116          * @var array A 2-d map overriding serverTemplate and
 117          * externalTemplateOverrides on a server-by-server basis. Applies to both
 118          * core and external storage
 119          */
 120         protected $templateOverridesByServer;
 121
 122         /** @var array A 2-d map overriding the server info by external storage cluster */
 123         protected $templateOverridesByCluster;
 124
 125         /** @var array An override array for all master servers */
 126         protected $masterTemplateOverrides;
 127
 128         /**
 129          * @var array|bool A map of section name to read-only message. Missing or
 130          * false for read/write
 131          */
 132         protected $readOnlyBySection = array();
 133
 134         // Other stuff
 135
 136         /** @var array Load balancer factory configuration */
 137         protected $conf;
 138
 139         /** @var LoadBalancer[] */
 140         protected $mainLBs = array();
 141
 142         /** @var LoadBalancer[] */
 143         protected $extLBs = array();
 144
 145         /** @var string */
 146         protected $lastWiki;
 147
 148         /** @var string */
 149         protected $lastSection;
 150
 151         /**
 152          * @param array $conf
 153          * @throws MWException
 154          */
 155         function __construct( $conf ) {
 156                 $this->chronProt = new ChronologyProtector;
 157                 $this->conf = $conf;
 158                 $required = array( 'sectionsByDB', 'sectionLoads', 'serverTemplate' );
 159                 $optional = array( 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
 160                         'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
 161                         'templateOverridesByCluster', 'masterTemplateOverrides',
 162                         'readOnlyBySection' );
 163
 164                 foreach ( $required as $key ) {
 165                         if ( !isset( $conf[$key] ) ) {
 166                                 throw new MWException( __CLASS__ . ": $key is required in configuration" );
 167                         }
 168                         $this->$key = $conf[$key];
 169                 }
 170
 171                 foreach ( $optional as $key ) {
 172                         if ( isset( $conf[$key] ) ) {
 173                                 $this->$key = $conf[$key];
 174                         }
 175                 }
 176
 177                 // Check for read-only mode
 178                 $section = $this->getSectionForWiki();
 179                 if ( !empty( $this->readOnlyBySection[$section] ) ) {
 180                         global $wgReadOnly;
 181                         $wgReadOnly = $this->readOnlyBySection[$section];
 182                 }
 183         }
 184
 185         /**
 186          * @param bool|string $wiki
 187          * @return string
 188          */
 189         function getSectionForWiki( $wiki = false ) {
 190                 if ( $this->lastWiki === $wiki ) {
 191                         return $this->lastSection;
 192                 }
 193                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
 194                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
 195                         $section = $this->sectionsByDB[$dbName];
 196                 } else {
 197                         $section = 'DEFAULT';
 198                 }
 199                 $this->lastSection = $section;
 200                 $this->lastWiki = $wiki;
 201
 202                 return $section;
 203         }
 204
 205         /**
 206          * @param bool|string $wiki
 207          * @return LoadBalancer
 208          */
 209         function newMainLB( $wiki = false ) {
 210                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
 211                 $section = $this->getSectionForWiki( $wiki );
 212                 $groupLoads = array();
 213                 if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
 214                         $groupLoads = $this->groupLoadsByDB[$dbName];
 215                 }
 216
 217                 if ( isset( $this->groupLoadsBySection[$section] ) ) {
 218                         $groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
 219                 }
 220
 221                 return $this->newLoadBalancer(
 222                         $this->serverTemplate,
 223                         $this->sectionLoads[$section],
 224                         $groupLoads
 225                 );
 226         }
 227
 228         /**
 229          * @param bool|string $wiki
 230          * @return LoadBalancer
 231          */
 232         function getMainLB( $wiki = false ) {
 233                 $section = $this->getSectionForWiki( $wiki );
 234                 if ( !isset( $this->mainLBs[$section] ) ) {
 235                         $lb = $this->newMainLB( $wiki, $section );
 236                         $lb->parentInfo( array( 'id' => "main-$section" ) );
 237                         $this->chronProt->initLB( $lb );
 238                         $this->mainLBs[$section] = $lb;
 239                 }
 240
 241                 return $this->mainLBs[$section];
 242         }
 243
 244         /**
 245          * @param string $cluster
 246          * @param bool|string $wiki
 247          * @throws MWException
 248          * @return LoadBalancer
 249          */
 250         function newExternalLB( $cluster, $wiki = false ) {
 251                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 252                         throw new MWException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
 253                 }
 254                 $template = $this->serverTemplate;
 255                 if ( isset( $this->externalTemplateOverrides ) ) {
 256                         $template = $this->externalTemplateOverrides + $template;
 257                 }
 258                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 259                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 260                 }
 261
 262                 return $this->newLoadBalancer( $template, $this->externalLoads[$cluster], array() );
 263         }
 264
 265         /**
 266          * @param string $cluster external storage cluster, or false for core
 267          * @param bool|string $wiki Wiki ID, or false for the current wiki
 268          * @return LoadBalancer
 269          */
 270         function &getExternalLB( $cluster, $wiki = false ) {
 271                 if ( !isset( $this->extLBs[$cluster] ) ) {
 272                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $wiki );
 273                         $this->extLBs[$cluster]->parentInfo( array( 'id' => "ext-$cluster" ) );
 274                         $this->chronProt->initLB( $this->extLBs[$cluster] );
 275                 }
 276
 277                 return $this->extLBs[$cluster];
 278         }
 279
 280         /**
 281          * Make a new load balancer object based on template and load array
 282          *
 283          * @param array $template
 284          * @param array $loads
 285          * @param array $groupLoads
 286          * @return LoadBalancer
 287          */
 288         function newLoadBalancer( $template, $loads, $groupLoads ) {
 289                 global $wgMasterWaitTimeout;
 290                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 291                 $lb = new LoadBalancer( array(
 292                         'servers' => $servers,
 293                         'masterWaitTimeout' => $wgMasterWaitTimeout
 294                 ) );
 295
 296                 return $lb;
 297         }
 298
 299         /**
 300          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 301          *
 302          * @param array $template
 303          * @param array $loads
 304          * @param array $groupLoads
 305          * @return array
 306          */
 307         function makeServerArray( $template, $loads, $groupLoads ) {
 308                 $servers = array();
 309                 $master = true;
 310                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 311                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 312                         if ( !isset( $loads[$server] ) ) {
 313                                 $loads[$server] = 0;
 314                         }
 315                 }
 316                 foreach ( $loads as $serverName => $load ) {
 317                         $serverInfo = $template;
 318                         if ( $master ) {
 319                                 $serverInfo['master'] = true;
 320                                 if ( isset( $this->masterTemplateOverrides ) ) {
 321                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 322                                 }
 323                                 $master = false;
 324                         }
 325                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 326                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 327                         }
 328                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 329                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 330                         }
 331                         if ( isset( $this->hostsByName[$serverName] ) ) {
 332                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 333                         } else {
 334                                 $serverInfo['host'] = $serverName;
 335                         }
 336                         $serverInfo['hostName'] = $serverName;
 337                         $serverInfo['load'] = $load;
 338                         $servers[] = $serverInfo;
 339                 }
 340
 341                 return $servers;
 342         }
 343
 344         /**
 345          * Take a group load array indexed by group then server, and reindex it by server then group
 346          * @param array $groupLoads
 347          * @return array
 348          */
 349         function reindexGroupLoads( $groupLoads ) {
 350                 $reindexed = array();
 351                 foreach ( $groupLoads as $group => $loads ) {
 352                         foreach ( $loads as $server => $load ) {
 353                                 $reindexed[$server][$group] = $load;
 354                         }
 355                 }
 356
 357                 return $reindexed;
 358         }
 359
 360         /**
 361          * Get the database name and prefix based on the wiki ID
 362          * @param bool|string $wiki
 363          * @return array
 364          */
 365         function getDBNameAndPrefix( $wiki = false ) {
 366                 if ( $wiki === false ) {
 367                         global $wgDBname, $wgDBprefix;
 368
 369                         return array( $wgDBname, $wgDBprefix );
 370                 } else {
 371                         return wfSplitWikiID( $wiki );
 372                 }
 373         }
 374
 375         /**
 376          * Execute a function for each tracked load balancer
 377          * The callback is called with the load balancer as the first parameter,
 378          * and $params passed as the subsequent parameters.
 379          * @param callable $callback
 380          * @param array $params
 381          */
 382         function forEachLB( $callback, $params = array() ) {
 383                 foreach ( $this->mainLBs as $lb ) {
 384                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 385                 }
 386                 foreach ( $this->extLBs as $lb ) {
 387                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 388                 }
 389         }
 390
 391         function shutdown() {
 392                 foreach ( $this->mainLBs as $lb ) {
 393                         $this->chronProt->shutdownLB( $lb );
 394                 }
 395                 foreach ( $this->extLBs as $extLB ) {
 396                         $this->chronProt->shutdownLB( $extLB );
 397                 }
 398                 $this->chronProt->shutdown();
 399                 $this->commitMasterChanges();
 400         }
 401 }