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 namespace Wikimedia\Rdbms;
  25
  26 use LoadBalancer;
  27 use IDatabase;
  28 use InvalidArgumentException;
  29
  30 /**
  31  * A multi-database, multi-master factory for Wikimedia and similar installations.
  32  * Ignores the old configuration globals.
  33  *
  34  * @ingroup Database
  35  */
  36 class LBFactoryMulti extends LBFactory {
  37         /** @var array A map of database names to section names */
  38         private $sectionsByDB;
  39
  40         /**
  41          * @var array A 2-d map. For each section, gives a map of server names to
  42          * load ratios
  43          */
  44         private $sectionLoads;
  45
  46         /**
  47          * @var array[] Server info associative array
  48          * @note The host, hostName and load entries will be overridden
  49          */
  50         private $serverTemplate;
  51
  52         // Optional settings
  53
  54         /** @var array A 3-d map giving server load ratios for each section and group */
  55         private $groupLoadsBySection = [];
  56
  57         /** @var array A 3-d map giving server load ratios by DB name */
  58         private $groupLoadsByDB = [];
  59
  60         /** @var array A map of hostname to IP address */
  61         private $hostsByName = [];
  62
  63         /** @var array A map of external storage cluster name to server load map */
  64         private $externalLoads = [];
  65
  66         /**
  67          * @var array A set of server info keys overriding serverTemplate for
  68          * external storage
  69          */
  70         private $externalTemplateOverrides;
  71
  72         /**
  73          * @var array A 2-d map overriding serverTemplate and
  74          * externalTemplateOverrides on a server-by-server basis. Applies to both
  75          * core and external storage
  76          */
  77         private $templateOverridesByServer;
  78
  79         /** @var array A 2-d map overriding the server info by section */
  80         private $templateOverridesBySection;
  81
  82         /** @var array A 2-d map overriding the server info by external storage cluster */
  83         private $templateOverridesByCluster;
  84
  85         /** @var array An override array for all master servers */
  86         private $masterTemplateOverrides;
  87
  88         /**
  89          * @var array|bool A map of section name to read-only message. Missing or
  90          * false for read/write
  91          */
  92         private $readOnlyBySection = [];
  93
  94         /** @var array Load balancer factory configuration */
  95         private $conf;
  96
  97         /** @var LoadBalancer[] */
  98         private $mainLBs = [];
  99
 100         /** @var LoadBalancer[] */
 101         private $extLBs = [];
 102
 103         /** @var string */
 104         private $loadMonitorClass = 'LoadMonitor';
 105
 106         /** @var string */
 107         private $lastDomain;
 108
 109         /** @var string */
 110         private $lastSection;
 111
 112         /**
 113          * @see LBFactory::__construct()
 114          *
 115          * Template override precedence (highest => lowest):
 116          *   - templateOverridesByServer
 117          *   - masterTemplateOverrides
 118          *   - templateOverridesBySection/templateOverridesByCluster
 119          *   - externalTemplateOverrides
 120          *   - serverTemplate
 121          * Overrides only work on top level keys (so nested values will not be merged).
 122          *
 123          * Server configuration maps should be of the format Database::factory() requires.
 124          * Additionally, a 'max lag' key should also be set on server maps, indicating how stale the
 125          * data can be before the load balancer tries to avoid using it. The map can have 'is static'
 126          * set to disable blocking  replication sync checks (intended for archive servers with
 127          * unchanging data).
 128          *
 129          * @param array $conf Parameters of LBFactory::__construct() as well as:
 130          *   - sectionsByDB                Map of database names to section names.
 131          *   - sectionLoads                2-d map. For each section, gives a map of server names to
 132          *                                 load ratios. For example:
 133          *                                 [
 134          *                                     'section1' => [
 135          *                                         'db1' => 100,
 136          *                                         'db2' => 100
 137          *                                     ]
 138          *                                 ]
 139          *   - serverTemplate              Server configuration map intended for Database::factory().
 140          *                                 Note that "host", "hostName" and "load" entries will be
 141          *                                 overridden by "sectionLoads" and "hostsByName".
 142          *   - groupLoadsBySection         3-d map giving server load ratios for each section/group.
 143          *                                 For example:
 144          *                                 [
 145          *                                     'section1' => [
 146          *                                         'group1' => [
 147          *                                             'db1' => 100,
 148          *                                             'db2' => 100
 149          *                                         ]
 150          *                                     ]
 151          *                                 ]
 152          *   - groupLoadsByDB              3-d map giving server load ratios by DB name.
 153          *   - hostsByName                 Map of hostname to IP address.
 154          *   - externalLoads               Map of external storage cluster name to server load map.
 155          *   - externalTemplateOverrides   Set of server configuration maps overriding
 156          *                                 "serverTemplate" for external storage.
 157          *   - templateOverridesByServer   2-d map overriding "serverTemplate" and
 158          *                                 "externalTemplateOverrides" on a server-by-server basis.
 159          *                                 Applies to both core and external storage.
 160          *   - templateOverridesBySection  2-d map overriding the server configuration maps by section.
 161          *   - templateOverridesByCluster  2-d map overriding the server configuration maps by external
 162          *                                 storage cluster.
 163          *   - masterTemplateOverrides     Server configuration map overrides for all master servers.
 164          *   - loadMonitorClass            Name of the LoadMonitor class to always use.
 165          *   - readOnlyBySection           A map of section name to read-only message.
 166          *                                 Missing or false for read/write.
 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         public function newExternalLB( $cluster ) {
 265                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 266                         throw new InvalidArgumentException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
 267                 }
 268                 $template = $this->serverTemplate;
 269                 if ( $this->externalTemplateOverrides ) {
 270                         $template = $this->externalTemplateOverrides + $template;
 271                 }
 272                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 273                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 274                 }
 275
 276                 return $this->newLoadBalancer(
 277                         $template,
 278                         $this->externalLoads[$cluster],
 279                         [],
 280                         $this->readOnlyReason
 281                 );
 282         }
 283
 284         public function getExternalLB( $cluster ) {
 285                 if ( !isset( $this->extLBs[$cluster] ) ) {
 286                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster );
 287                         $this->getChronologyProtector()->initLB( $this->extLBs[$cluster] );
 288                 }
 289
 290                 return $this->extLBs[$cluster];
 291         }
 292
 293         public function getAllMainLBs() {
 294                 $lbs = [];
 295                 foreach ( $this->sectionsByDB as $db => $section ) {
 296                         if ( !isset( $lbs[$section] ) ) {
 297                                 $lbs[$section] = $this->getMainLB( $db );
 298                         }
 299                 }
 300
 301                 return $lbs;
 302         }
 303
 304         public function getAllExternalLBs() {
 305                 $lbs = [];
 306                 foreach ( $this->externalLoads as $cluster => $unused ) {
 307                         $lbs[$cluster] = $this->getExternalLB( $cluster );
 308                 }
 309
 310                 return $lbs;
 311         }
 312
 313         /**
 314          * Make a new load balancer object based on template and load array
 315          *
 316          * @param array $template
 317          * @param array $loads
 318          * @param array $groupLoads
 319          * @param string|bool $readOnlyReason
 320          * @return LoadBalancer
 321          */
 322         private function newLoadBalancer( $template, $loads, $groupLoads, $readOnlyReason ) {
 323                 $lb = new LoadBalancer( array_merge(
 324                         $this->baseLoadBalancerParams(),
 325                         [
 326                                 'servers' => $this->makeServerArray( $template, $loads, $groupLoads ),
 327                                 'loadMonitor' => [ 'class' => $this->loadMonitorClass ],
 328                                 'readOnlyReason' => $readOnlyReason
 329                         ]
 330                 ) );
 331                 $this->initLoadBalancer( $lb );
 332
 333                 return $lb;
 334         }
 335
 336         /**
 337          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 338          *
 339          * @param array $template
 340          * @param array $loads
 341          * @param array $groupLoads
 342          * @return array
 343          */
 344         private function makeServerArray( $template, $loads, $groupLoads ) {
 345                 $servers = [];
 346                 $master = true;
 347                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 348                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 349                         if ( !isset( $loads[$server] ) ) {
 350                                 $loads[$server] = 0;
 351                         }
 352                 }
 353                 foreach ( $loads as $serverName => $load ) {
 354                         $serverInfo = $template;
 355                         if ( $master ) {
 356                                 $serverInfo['master'] = true;
 357                                 if ( $this->masterTemplateOverrides ) {
 358                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 359                                 }
 360                                 $master = false;
 361                         } else {
 362                                 $serverInfo['replica'] = true;
 363                         }
 364                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 365                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 366                         }
 367                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 368                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 369                         }
 370                         if ( isset( $this->hostsByName[$serverName] ) ) {
 371                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 372                         } else {
 373                                 $serverInfo['host'] = $serverName;
 374                         }
 375                         $serverInfo['hostName'] = $serverName;
 376                         $serverInfo['load'] = $load;
 377                         $serverInfo += [ 'flags' => IDatabase::DBO_DEFAULT ];
 378
 379                         $servers[] = $serverInfo;
 380                 }
 381
 382                 return $servers;
 383         }
 384
 385         /**
 386          * Take a group load array indexed by group then server, and reindex it by server then group
 387          * @param array $groupLoads
 388          * @return array
 389          */
 390         private function reindexGroupLoads( $groupLoads ) {
 391                 $reindexed = [];
 392                 foreach ( $groupLoads as $group => $loads ) {
 393                         foreach ( $loads as $server => $load ) {
 394                                 $reindexed[$server][$group] = $load;
 395                         }
 396                 }
 397
 398                 return $reindexed;
 399         }
 400
 401         /**
 402          * @param DatabaseDomain|string|bool $domain Domain ID, or false for the current domain
 403          * @return array [database name, table prefix]
 404          */
 405         private function getDBNameAndPrefix( $domain = false ) {
 406                 $domain = ( $domain === false )
 407                         ? $this->localDomain
 408                         : DatabaseDomain::newFromId( $domain );
 409
 410                 return [ $domain->getDatabase(), $domain->getTablePrefix() ];
 411         }
 412
 413         /**
 414          * Execute a function for each tracked load balancer
 415          * The callback is called with the load balancer as the first parameter,
 416          * and $params passed as the subsequent parameters.
 417          * @param callable $callback
 418          * @param array $params
 419          */
 420         public function forEachLB( $callback, array $params = [] ) {
 421                 foreach ( $this->mainLBs as $lb ) {
 422                         call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
 423                 }
 424                 foreach ( $this->extLBs as $lb ) {
 425                         call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
 426                 }
 427         }
 428 }