includes/db/loadbalancer/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  *     loadMonitorClass            Name of the LoadMonitor class to always use.
  72  *
  73  *     readOnlyBySection           A map of section name to read-only message.
  74  *                                 Missing or false for read/write.
  75  *
  76  * @ingroup Database
  77  */
  78 class LBFactoryMulti extends LBFactory {
  79         // Required settings
  80
  81         /** @var array A map of database names to section names */
  82         private $sectionsByDB;
  83
  84         /**
  85          * @var array A 2-d map. For each section, gives a map of server names to
  86          * load ratios
  87          */
  88         private $sectionLoads;
  89
  90         /**
  91          * @var array A server info associative array as documented for
  92          * $wgDBservers. The host, hostName and load entries will be
  93          * overridden
  94          */
  95         private $serverTemplate;
  96
  97         // Optional settings
  98
  99         /** @var array A 3-d map giving server load ratios for each section and group */
 100         private $groupLoadsBySection = array();
 101
 102         /** @var array A 3-d map giving server load ratios by DB name */
 103         private $groupLoadsByDB = array();
 104
 105         /** @var array A map of hostname to IP address */
 106         private $hostsByName = array();
 107
 108         /** @var array A map of external storage cluster name to server load map */
 109         private $externalLoads = array();
 110
 111         /**
 112          * @var array A set of server info keys overriding serverTemplate for
 113          * external storage
 114          */
 115         private $externalTemplateOverrides;
 116
 117         /**
 118          * @var array A 2-d map overriding serverTemplate and
 119          * externalTemplateOverrides on a server-by-server basis. Applies to both
 120          * core and external storage
 121          */
 122         private $templateOverridesByServer;
 123
 124         /** @var array A 2-d map overriding the server info by external storage cluster */
 125         private $templateOverridesByCluster;
 126
 127         /** @var array An override array for all master servers */
 128         private $masterTemplateOverrides;
 129
 130         /**
 131          * @var array|bool A map of section name to read-only message. Missing or
 132          * false for read/write
 133          */
 134         private $readOnlyBySection = array();
 135
 136         // Other stuff
 137
 138         /** @var array Load balancer factory configuration */
 139         private $conf;
 140
 141         /** @var LoadBalancer[] */
 142         private $mainLBs = array();
 143
 144         /** @var LoadBalancer[] */
 145         private $extLBs = array();
 146
 147         /** @var string */
 148         private $loadMonitorClass;
 149
 150         /** @var string */
 151         private $lastWiki;
 152
 153         /** @var string */
 154         private $lastSection;
 155
 156         /**
 157          * @param array $conf
 158          * @throws MWException
 159          */
 160         public function __construct( array $conf ) {
 161                 $this->chronProt = new ChronologyProtector;
 162                 $this->conf = $conf;
 163                 $required = array( 'sectionsByDB', 'sectionLoads', 'serverTemplate' );
 164                 $optional = array( 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
 165                         'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
 166                         'templateOverridesByCluster', 'masterTemplateOverrides',
 167                         'readOnlyBySection', 'loadMonitorClass' );
 168
 169                 foreach ( $required as $key ) {
 170                         if ( !isset( $conf[$key] ) ) {
 171                                 throw new MWException( __CLASS__ . ": $key is required in configuration" );
 172                         }
 173                         $this->$key = $conf[$key];
 174                 }
 175
 176                 foreach ( $optional as $key ) {
 177                         if ( isset( $conf[$key] ) ) {
 178                                 $this->$key = $conf[$key];
 179                         }
 180                 }
 181
 182                 // Check for read-only mode
 183                 $section = $this->getSectionForWiki();
 184                 if ( !empty( $this->readOnlyBySection[$section] ) ) {
 185                         global $wgReadOnly;
 186                         $wgReadOnly = $this->readOnlyBySection[$section];
 187                 }
 188         }
 189
 190         /**
 191          * @param bool|string $wiki
 192          * @return string
 193          */
 194         private function getSectionForWiki( $wiki = false ) {
 195                 if ( $this->lastWiki === $wiki ) {
 196                         return $this->lastSection;
 197                 }
 198                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
 199                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
 200                         $section = $this->sectionsByDB[$dbName];
 201                 } else {
 202                         $section = 'DEFAULT';
 203                 }
 204                 $this->lastSection = $section;
 205                 $this->lastWiki = $wiki;
 206
 207                 return $section;
 208         }
 209
 210         /**
 211          * @param bool|string $wiki
 212          * @return LoadBalancer
 213          */
 214         public function newMainLB( $wiki = false ) {
 215                 list( $dbName, ) = $this->getDBNameAndPrefix( $wiki );
 216                 $section = $this->getSectionForWiki( $wiki );
 217                 $groupLoads = array();
 218                 if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
 219                         $groupLoads = $this->groupLoadsByDB[$dbName];
 220                 }
 221
 222                 if ( isset( $this->groupLoadsBySection[$section] ) ) {
 223                         $groupLoads = array_merge_recursive( $groupLoads, $this->groupLoadsBySection[$section] );
 224                 }
 225
 226                 return $this->newLoadBalancer(
 227                         $this->serverTemplate,
 228                         $this->sectionLoads[$section],
 229                         $groupLoads
 230                 );
 231         }
 232
 233         /**
 234          * @param bool|string $wiki
 235          * @return LoadBalancer
 236          */
 237         public function getMainLB( $wiki = false ) {
 238                 $section = $this->getSectionForWiki( $wiki );
 239                 if ( !isset( $this->mainLBs[$section] ) ) {
 240                         $lb = $this->newMainLB( $wiki );
 241                         $lb->parentInfo( array( 'id' => "main-$section" ) );
 242                         $this->chronProt->initLB( $lb );
 243                         $this->mainLBs[$section] = $lb;
 244                 }
 245
 246                 return $this->mainLBs[$section];
 247         }
 248
 249         /**
 250          * @param string $cluster
 251          * @param bool|string $wiki
 252          * @throws MWException
 253          * @return LoadBalancer
 254          */
 255         protected function newExternalLB( $cluster, $wiki = false ) {
 256                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 257                         throw new MWException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
 258                 }
 259                 $template = $this->serverTemplate;
 260                 if ( isset( $this->externalTemplateOverrides ) ) {
 261                         $template = $this->externalTemplateOverrides + $template;
 262                 }
 263                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 264                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 265                 }
 266
 267                 return $this->newLoadBalancer( $template, $this->externalLoads[$cluster], array() );
 268         }
 269
 270         /**
 271          * @param string $cluster External storage cluster, or false for core
 272          * @param bool|string $wiki Wiki ID, or false for the current wiki
 273          * @return LoadBalancer
 274          */
 275         public function &getExternalLB( $cluster, $wiki = false ) {
 276                 if ( !isset( $this->extLBs[$cluster] ) ) {
 277                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $wiki );
 278                         $this->extLBs[$cluster]->parentInfo( array( 'id' => "ext-$cluster" ) );
 279                         $this->chronProt->initLB( $this->extLBs[$cluster] );
 280                 }
 281
 282                 return $this->extLBs[$cluster];
 283         }
 284
 285         /**
 286          * Make a new load balancer object based on template and load array
 287          *
 288          * @param array $template
 289          * @param array $loads
 290          * @param array $groupLoads
 291          * @return LoadBalancer
 292          */
 293         private function newLoadBalancer( $template, $loads, $groupLoads ) {
 294                 $servers = $this->makeServerArray( $template, $loads, $groupLoads );
 295                 $lb = new LoadBalancer( array(
 296                         'servers' => $servers,
 297                         'loadMonitor' => $this->loadMonitorClass
 298                 ) );
 299
 300                 return $lb;
 301         }
 302
 303         /**
 304          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 305          *
 306          * @param array $template
 307          * @param array $loads
 308          * @param array $groupLoads
 309          * @return array
 310          */
 311         private function makeServerArray( $template, $loads, $groupLoads ) {
 312                 $servers = array();
 313                 $master = true;
 314                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 315                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 316                         if ( !isset( $loads[$server] ) ) {
 317                                 $loads[$server] = 0;
 318                         }
 319                 }
 320                 foreach ( $loads as $serverName => $load ) {
 321                         $serverInfo = $template;
 322                         if ( $master ) {
 323                                 $serverInfo['master'] = true;
 324                                 if ( isset( $this->masterTemplateOverrides ) ) {
 325                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 326                                 }
 327                                 $master = false;
 328                         } else {
 329                                 $serverInfo['slave'] = true;
 330                         }
 331                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 332                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 333                         }
 334                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 335                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 336                         }
 337                         if ( isset( $this->hostsByName[$serverName] ) ) {
 338                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 339                         } else {
 340                                 $serverInfo['host'] = $serverName;
 341                         }
 342                         $serverInfo['hostName'] = $serverName;
 343                         $serverInfo['load'] = $load;
 344                         $servers[] = $serverInfo;
 345                 }
 346
 347                 return $servers;
 348         }
 349
 350         /**
 351          * Take a group load array indexed by group then server, and reindex it by server then group
 352          * @param array $groupLoads
 353          * @return array
 354          */
 355         private function reindexGroupLoads( $groupLoads ) {
 356                 $reindexed = array();
 357                 foreach ( $groupLoads as $group => $loads ) {
 358                         foreach ( $loads as $server => $load ) {
 359                                 $reindexed[$server][$group] = $load;
 360                         }
 361                 }
 362
 363                 return $reindexed;
 364         }
 365
 366         /**
 367          * Get the database name and prefix based on the wiki ID
 368          * @param bool|string $wiki
 369          * @return array
 370          */
 371         private function getDBNameAndPrefix( $wiki = false ) {
 372                 if ( $wiki === false ) {
 373                         global $wgDBname, $wgDBprefix;
 374
 375                         return array( $wgDBname, $wgDBprefix );
 376                 } else {
 377                         return wfSplitWikiID( $wiki );
 378                 }
 379         }
 380
 381         /**
 382          * Execute a function for each tracked load balancer
 383          * The callback is called with the load balancer as the first parameter,
 384          * and $params passed as the subsequent parameters.
 385          * @param callable $callback
 386          * @param array $params
 387          */
 388         public function forEachLB( $callback, array $params = array() ) {
 389                 foreach ( $this->mainLBs as $lb ) {
 390                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 391                 }
 392                 foreach ( $this->extLBs as $lb ) {
 393                         call_user_func_array( $callback, array_merge( array( $lb ), $params ) );
 394                 }
 395         }
 396
 397         public function shutdown() {
 398                 foreach ( $this->mainLBs as $lb ) {
 399                         $this->chronProt->shutdownLB( $lb );
 400                 }
 401                 foreach ( $this->extLBs as $extLB ) {
 402                         $this->chronProt->shutdownLB( $extLB );
 403                 }
 404                 $this->chronProt->shutdown();
 405                 $this->commitMasterChanges();
 406         }
 407 }