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         private $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         private $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         private $serverTemplate;
  94
  95         // Optional settings
  96
  97         /** @var array A 3-d map giving server load ratios for each section and group */
  98         private $groupLoadsBySection = array();
  99
 100         /** @var array A 3-d map giving server load ratios by DB name */
 101         private $groupLoadsByDB = array();
 102
 103         /** @var array A map of hostname to IP address */
 104         private $hostsByName = array();
 105
 106         /** @var array A map of external storage cluster name to server load map */
 107         private $externalLoads = array();
 108
 109         /**
 110          * @var array A set of server info keys overriding serverTemplate for
 111          * external storage
 112          */
 113         private $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         private $templateOverridesByServer;
 121
 122         /** @var array A 2-d map overriding the server info by external storage cluster */
 123         private $templateOverridesByCluster;
 124
 125         /** @var array An override array for all master servers */
 126         private $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         private $readOnlyBySection = array();
 133
 134         // Other stuff
 135
 136         /** @var array Load balancer factory configuration */
 137         private $conf;
 138
 139         /** @var LoadBalancer[] */
 140         private $mainLBs = array();
 141
 142         /** @var LoadBalancer[] */
 143         private $extLBs = array();
 144
 145         /** @var string */
 146         private $lastWiki;
 147
 148         /** @var string */
 149         private $lastSection;
 150
 151         /**
 152          * @param array $conf
 153          * @throws MWException
 154          */
 155         public function __construct( array $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         private 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         public 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         public 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         protected 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         public 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         private function newLoadBalancer( $template, $loads, $groupLoads ) {
 289                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 290                 $lb = new LoadBalancer( array(
 291                         'servers' => $servers,
 292                 ) );
 293
 294                 return $lb;
 295         }
 296
 297         /**
 298          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 299          *
 300          * @param array $template
 301          * @param array $loads
 302          * @param array $groupLoads
 303          * @return array
 304          */
 305         private function makeServerArray( $template, $loads, $groupLoads ) {
 306                 $servers = array();
 307                 $master = true;
 308                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 309                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 310                         if ( !isset( $loads[$server] ) ) {
 311                                 $loads[$server] = 0;
 312                         }
 313                 }
 314                 foreach ( $loads as $serverName => $load ) {
 315                         $serverInfo = $template;
 316                         if ( $master ) {
 317                                 $serverInfo['master'] = true;
 318                                 if ( isset( $this->masterTemplateOverrides ) ) {
 319                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 320                                 }
 321                                 $master = false;
 322                         }
 323                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 324                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 325                         }
 326                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 327                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 328                         }
 329                         if ( isset( $this->hostsByName[$serverName] ) ) {
 330                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 331                         } else {
 332                                 $serverInfo['host'] = $serverName;
 333                         }
 334                         $serverInfo['hostName'] = $serverName;
 335                         $serverInfo['load'] = $load;
 336                         $servers[] = $serverInfo;
 337                 }
 338
 339                 return $servers;
 340         }
 341
 342         /**
 343          * Take a group load array indexed by group then server, and reindex it by server then group
 344          * @param array $groupLoads
 345          * @return array
 346          */
 347         private function reindexGroupLoads( $groupLoads ) {
 348                 $reindexed = array();
 349                 foreach ( $groupLoads as $group => $loads ) {
 350                         foreach ( $loads as $server => $load ) {
 351                                 $reindexed[$server][$group] = $load;
 352                         }
 353                 }
 354
 355                 return $reindexed;
 356         }
 357
 358         /**
 359          * Get the database name and prefix based on the wiki ID
 360          * @param bool|string $wiki
 361          * @return array
 362          */
 363         private function getDBNameAndPrefix( $wiki = false ) {
 364                 if ( $wiki === false ) {
 365                         global $wgDBname, $wgDBprefix;
 366
 367                         return array( $wgDBname, $wgDBprefix );
 368                 } else {
 369                         return wfSplitWikiID( $wiki );
 370                 }
 371         }
 372
 373         /**
 374          * Execute a function for each tracked load balancer
 375          * The callback is called with the load balancer as the first parameter,
 376          * and $params passed as the subsequent parameters.
 377          * @param callable $callback
 378          * @param array $params
 379          */
 380         public function forEachLB( $callback, array $params = array() ) {
 381                 foreach ( $this->mainLBs as $lb ) {
 382                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 383                 }
 384                 foreach ( $this->extLBs as $lb ) {
 385                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 386                 }
 387         }
 388
 389         public function shutdown() {
 390                 foreach ( $this->mainLBs as $lb ) {
 391                         $this->chronProt->shutdownLB( $lb );
 392                 }
 393                 foreach ( $this->extLBs as $extLB ) {
 394                         $this->chronProt->shutdownLB( $extLB );
 395                 }
 396                 $this->chronProt->shutdown();
 397                 $this->commitMasterChanges();
 398         }
 399 }