includes/libs/rdbms/lbfactory/LBFactoryMulti.php

   1 <?php
   2 /**
   3  * Advanced generator of database load balancing objects for database 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-database, multi-master factory for Wikimedia and similar installations.
  26  * Ignores the old configuration globals.
  27  *
  28  * Template override precedence (highest => lowest):
  29  *   - templateOverridesByServer
  30  *   - masterTemplateOverrides
  31  *   - templateOverridesBySection/templateOverridesByCluster
  32  *   - externalTemplateOverrides
  33  *   - serverTemplate
  34  * Overrides only work on top level keys (so nested values will not be merged).
  35  *
  36  * Configuration:
  37  *     sectionsByDB                A map of database names to section names.
  38  *
  39  *     sectionLoads                A 2-d map. For each section, gives a map of server names to
  40  *                                 load ratios. For example:
  41  *                                 [
  42  *                                     'section1' => [
  43  *                                         'db1' => 100,
  44  *                                         'db2' => 100
  45  *                                     ]
  46  *                                 ]
  47  *
  48  *     serverTemplate              A server info associative array as documented for $wgDBservers.
  49  *                                 The host, hostName and load entries will be overridden.
  50  *
  51  *     groupLoadsBySection         A 3-d map giving server load ratios for each section and group.
  52  *                                 For example:
  53  *                                 [
  54  *                                     'section1' => [
  55  *                                         'group1' => [
  56  *                                             'db1' => 100,
  57  *                                             'db2' => 100
  58  *                                         ]
  59  *                                     ]
  60  *                                 ]
  61  *
  62  *     groupLoadsByDB              A 3-d map giving server load ratios by DB name.
  63  *
  64  *     hostsByName                 A map of hostname to IP address.
  65  *
  66  *     externalLoads               A map of external storage cluster name to server load map.
  67  *
  68  *     externalTemplateOverrides   A set of server info keys overriding serverTemplate for external
  69  *                                 storage.
  70  *
  71  *     templateOverridesByServer   A 2-d map overriding serverTemplate and
  72  *                                 externalTemplateOverrides on a server-by-server basis. Applies
  73  *                                 to both core and external storage.
  74  *     templateOverridesBySection  A 2-d map overriding the server info by section.
  75  *     templateOverridesByCluster  A 2-d map overriding the server info by external storage cluster.
  76  *
  77  *     masterTemplateOverrides     An override array for all master servers.
  78  *
  79  *     loadMonitorClass            Name of the LoadMonitor class to always use.
  80  *
  81  *     readOnlyBySection           A map of section name to read-only message.
  82  *                                 Missing or false for read/write.
  83  *
  84  * @ingroup Database
  85  */
  86 class LBFactoryMulti extends LBFactory {
  87         /** @var array A map of database names to section names */
  88         private $sectionsByDB;
  89
  90         /**
  91          * @var array A 2-d map. For each section, gives a map of server names to
  92          * load ratios
  93          */
  94         private $sectionLoads;
  95
  96         /**
  97          * @var array[] Server info associative array
  98          * @note The host, hostName and load entries will be overridden
  99          */
 100         private $serverTemplate;
 101
 102         // Optional settings
 103
 104         /** @var array A 3-d map giving server load ratios for each section and group */
 105         private $groupLoadsBySection = [];
 106
 107         /** @var array A 3-d map giving server load ratios by DB name */
 108         private $groupLoadsByDB = [];
 109
 110         /** @var array A map of hostname to IP address */
 111         private $hostsByName = [];
 112
 113         /** @var array A map of external storage cluster name to server load map */
 114         private $externalLoads = [];
 115
 116         /**
 117          * @var array A set of server info keys overriding serverTemplate for
 118          * external storage
 119          */
 120         private $externalTemplateOverrides;
 121
 122         /**
 123          * @var array A 2-d map overriding serverTemplate and
 124          * externalTemplateOverrides on a server-by-server basis. Applies to both
 125          * core and external storage
 126          */
 127         private $templateOverridesByServer;
 128
 129         /** @var array A 2-d map overriding the server info by section */
 130         private $templateOverridesBySection;
 131
 132         /** @var array A 2-d map overriding the server info by external storage cluster */
 133         private $templateOverridesByCluster;
 134
 135         /** @var array An override array for all master servers */
 136         private $masterTemplateOverrides;
 137
 138         /**
 139          * @var array|bool A map of section name to read-only message. Missing or
 140          * false for read/write
 141          */
 142         private $readOnlyBySection = [];
 143
 144         // Other stuff
 145
 146         /** @var array Load balancer factory configuration */
 147         private $conf;
 148
 149         /** @var LoadBalancer[] */
 150         private $mainLBs = [];
 151
 152         /** @var LoadBalancer[] */
 153         private $extLBs = [];
 154
 155         /** @var string */
 156         private $loadMonitorClass;
 157
 158         /** @var string */
 159         private $lastDomain;
 160
 161         /** @var string */
 162         private $lastSection;
 163
 164         /**
 165          * @param array $conf
 166          * @throws InvalidArgumentException
 167          */
 168         public function __construct( array $conf ) {
 169                 parent::__construct( $conf );
 170
 171                 $this->conf = $conf;
 172                 $required = [ 'sectionsByDB', 'sectionLoads', 'serverTemplate' ];
 173                 $optional = [ 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
 174                         'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
 175                         'templateOverridesByCluster', 'templateOverridesBySection', 'masterTemplateOverrides',
 176                         'readOnlyBySection', 'loadMonitorClass' ];
 177
 178                 foreach ( $required as $key ) {
 179                         if ( !isset( $conf[$key] ) ) {
 180                                 throw new InvalidArgumentException( __CLASS__ . ": $key is required." );
 181                         }
 182                         $this->$key = $conf[$key];
 183                 }
 184
 185                 foreach ( $optional as $key ) {
 186                         if ( isset( $conf[$key] ) ) {
 187                                 $this->$key = $conf[$key];
 188                         }
 189                 }
 190         }
 191
 192         /**
 193          * @param bool|string $domain
 194          * @return string
 195          */
 196         private function getSectionForDomain( $domain = false ) {
 197                 if ( $this->lastDomain === $domain ) {
 198                         return $this->lastSection;
 199                 }
 200                 list( $dbName, ) = $this->getDBNameAndPrefix( $domain );
 201                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
 202                         $section = $this->sectionsByDB[$dbName];
 203                 } else {
 204                         $section = 'DEFAULT';
 205                 }
 206                 $this->lastSection = $section;
 207                 $this->lastDomain = $domain;
 208
 209                 return $section;
 210         }
 211
 212         /**
 213          * @param bool|string $domain
 214          * @return LoadBalancer
 215          */
 216         public function newMainLB( $domain = false ) {
 217                 list( $dbName, ) = $this->getDBNameAndPrefix( $domain );
 218                 $section = $this->getSectionForDomain( $domain );
 219                 if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
 220                         $groupLoads = $this->groupLoadsByDB[$dbName];
 221                 } else {
 222                         $groupLoads = [];
 223                 }
 224
 225                 if ( isset( $this->groupLoadsBySection[$section] ) ) {
 226                         $groupLoads = array_merge_recursive(
 227                                 $groupLoads, $this->groupLoadsBySection[$section] );
 228                 }
 229
 230                 $readOnlyReason = $this->readOnlyReason;
 231                 // Use the LB-specific read-only reason if everything isn't already read-only
 232                 if ( $readOnlyReason === false && isset( $this->readOnlyBySection[$section] ) ) {
 233                         $readOnlyReason = $this->readOnlyBySection[$section];
 234                 }
 235
 236                 $template = $this->serverTemplate;
 237                 if ( isset( $this->templateOverridesBySection[$section] ) ) {
 238                         $template = $this->templateOverridesBySection[$section] + $template;
 239                 }
 240
 241                 return $this->newLoadBalancer(
 242                         $template,
 243                         $this->sectionLoads[$section],
 244                         $groupLoads,
 245                         $readOnlyReason
 246                 );
 247         }
 248
 249         /**
 250          * @param DatabaseDomain|string|bool $domain Domain ID, or false for the current domain
 251          * @return LoadBalancer
 252          */
 253         public function getMainLB( $domain = false ) {
 254                 $section = $this->getSectionForDomain( $domain );
 255                 if ( !isset( $this->mainLBs[$section] ) ) {
 256                         $lb = $this->newMainLB( $domain );
 257                         $this->getChronologyProtector()->initLB( $lb );
 258                         $this->mainLBs[$section] = $lb;
 259                 }
 260
 261                 return $this->mainLBs[$section];
 262         }
 263
 264         /**
 265          * @param string $cluster
 266          * @param DatabaseDomain|string|bool $domain Domain ID, or false for the current domain
 267          * @throws InvalidArgumentException
 268          * @return LoadBalancer
 269          */
 270         protected function newExternalLB( $cluster, $domain = false ) {
 271                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 272                         throw new InvalidArgumentException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
 273                 }
 274                 $template = $this->serverTemplate;
 275                 if ( isset( $this->externalTemplateOverrides ) ) {
 276                         $template = $this->externalTemplateOverrides + $template;
 277                 }
 278                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 279                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 280                 }
 281
 282                 return $this->newLoadBalancer(
 283                         $template,
 284                         $this->externalLoads[$cluster],
 285                         [],
 286                         $this->readOnlyReason
 287                 );
 288         }
 289
 290         /**
 291          * @param string $cluster External storage cluster, or false for core
 292          * @param DatabaseDomain|string|bool $domain Domain ID, or false for the current domain
 293          * @return LoadBalancer
 294          */
 295         public function getExternalLB( $cluster, $domain = false ) {
 296                 if ( !isset( $this->extLBs[$cluster] ) ) {
 297                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster, $domain );
 298                         $this->getChronologyProtector()->initLB( $this->extLBs[$cluster] );
 299                 }
 300
 301                 return $this->extLBs[$cluster];
 302         }
 303
 304         /**
 305          * Make a new load balancer object based on template and load array
 306          *
 307          * @param array $template
 308          * @param array $loads
 309          * @param array $groupLoads
 310          * @param string|bool $readOnlyReason
 311          * @return LoadBalancer
 312          */
 313         private function newLoadBalancer( $template, $loads, $groupLoads, $readOnlyReason ) {
 314                 $lb = new LoadBalancer( array_merge(
 315                         $this->baseLoadBalancerParams(),
 316                         [
 317                                 'servers' => $this->makeServerArray( $template, $loads, $groupLoads ),
 318                                 'loadMonitor' => $this->loadMonitorClass,
 319                                 'readOnlyReason' => $readOnlyReason
 320                         ]
 321                 ) );
 322                 $this->initLoadBalancer( $lb );
 323
 324                 return $lb;
 325         }
 326
 327         /**
 328          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 329          *
 330          * @param array $template
 331          * @param array $loads
 332          * @param array $groupLoads
 333          * @return array
 334          */
 335         private function makeServerArray( $template, $loads, $groupLoads ) {
 336                 $servers = [];
 337                 $master = true;
 338                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 339                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 340                         if ( !isset( $loads[$server] ) ) {
 341                                 $loads[$server] = 0;
 342                         }
 343                 }
 344                 foreach ( $loads as $serverName => $load ) {
 345                         $serverInfo = $template;
 346                         if ( $master ) {
 347                                 $serverInfo['master'] = true;
 348                                 if ( isset( $this->masterTemplateOverrides ) ) {
 349                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 350                                 }
 351                                 $master = false;
 352                         } else {
 353                                 $serverInfo['replica'] = true;
 354                         }
 355                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 356                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 357                         }
 358                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 359                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 360                         }
 361                         if ( isset( $this->hostsByName[$serverName] ) ) {
 362                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 363                         } else {
 364                                 $serverInfo['host'] = $serverName;
 365                         }
 366                         $serverInfo['hostName'] = $serverName;
 367                         $serverInfo['load'] = $load;
 368                         $serverInfo += [ 'flags' => DBO_DEFAULT ];
 369
 370                         $servers[] = $serverInfo;
 371                 }
 372
 373                 return $servers;
 374         }
 375
 376         /**
 377          * Take a group load array indexed by group then server, and reindex it by server then group
 378          * @param array $groupLoads
 379          * @return array
 380          */
 381         private function reindexGroupLoads( $groupLoads ) {
 382                 $reindexed = [];
 383                 foreach ( $groupLoads as $group => $loads ) {
 384                         foreach ( $loads as $server => $load ) {
 385                                 $reindexed[$server][$group] = $load;
 386                         }
 387                 }
 388
 389                 return $reindexed;
 390         }
 391
 392         /**
 393          * @param DatabaseDomain|string|bool $domain Domain ID, or false for the current domain
 394          * @return array [database name, table prefix]
 395          */
 396         private function getDBNameAndPrefix( $domain = false ) {
 397                 $domain = ( $domain === false )
 398                         ? $this->localDomain
 399                         : DatabaseDomain::newFromId( $domain );
 400
 401                 return [ $domain->getDatabase(), $domain->getTablePrefix() ];
 402         }
 403
 404         /**
 405          * Execute a function for each tracked load balancer
 406          * The callback is called with the load balancer as the first parameter,
 407          * and $params passed as the subsequent parameters.
 408          * @param callable $callback
 409          * @param array $params
 410          */
 411         public function forEachLB( $callback, array $params = [] ) {
 412                 foreach ( $this->mainLBs as $lb ) {
 413                         call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
 414                 }
 415                 foreach ( $this->extLBs as $lb ) {
 416                         call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
 417                 }
 418         }
 419 }