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 DatabaseDomain;
  29 use InvalidArgumentException;
  30
  31 /**
  32  * A multi-database, multi-master factory for Wikimedia and similar installations.
  33  * Ignores the old configuration globals.
  34  *
  35  * @ingroup Database
  36  */
  37 class LBFactoryMulti extends LBFactory {
  38         /** @var array A map of database names to section names */
  39         private $sectionsByDB;
  40
  41         /**
  42          * @var array A 2-d map. For each section, gives a map of server names to
  43          * load ratios
  44          */
  45         private $sectionLoads;
  46
  47         /**
  48          * @var array[] Server info associative array
  49          * @note The host, hostName and load entries will be overridden
  50          */
  51         private $serverTemplate;
  52
  53         // Optional settings
  54
  55         /** @var array A 3-d map giving server load ratios for each section and group */
  56         private $groupLoadsBySection = [];
  57
  58         /** @var array A 3-d map giving server load ratios by DB name */
  59         private $groupLoadsByDB = [];
  60
  61         /** @var array A map of hostname to IP address */
  62         private $hostsByName = [];
  63
  64         /** @var array A map of external storage cluster name to server load map */
  65         private $externalLoads = [];
  66
  67         /**
  68          * @var array A set of server info keys overriding serverTemplate for
  69          * external storage
  70          */
  71         private $externalTemplateOverrides;
  72
  73         /**
  74          * @var array A 2-d map overriding serverTemplate and
  75          * externalTemplateOverrides on a server-by-server basis. Applies to both
  76          * core and external storage
  77          */
  78         private $templateOverridesByServer;
  79
  80         /** @var array A 2-d map overriding the server info by section */
  81         private $templateOverridesBySection;
  82
  83         /** @var array A 2-d map overriding the server info by external storage cluster */
  84         private $templateOverridesByCluster;
  85
  86         /** @var array An override array for all master servers */
  87         private $masterTemplateOverrides;
  88
  89         /**
  90          * @var array|bool A map of section name to read-only message. Missing or
  91          * false for read/write
  92          */
  93         private $readOnlyBySection = [];
  94
  95         /** @var array Load balancer factory configuration */
  96         private $conf;
  97
  98         /** @var LoadBalancer[] */
  99         private $mainLBs = [];
 100
 101         /** @var LoadBalancer[] */
 102         private $extLBs = [];
 103
 104         /** @var string */
 105         private $loadMonitorClass = 'LoadMonitor';
 106
 107         /** @var string */
 108         private $lastDomain;
 109
 110         /** @var string */
 111         private $lastSection;
 112
 113         /**
 114          * @see LBFactory::__construct()
 115          *
 116          * Template override precedence (highest => lowest):
 117          *   - templateOverridesByServer
 118          *   - masterTemplateOverrides
 119          *   - templateOverridesBySection/templateOverridesByCluster
 120          *   - externalTemplateOverrides
 121          *   - serverTemplate
 122          * Overrides only work on top level keys (so nested values will not be merged).
 123          *
 124          * Server configuration maps should be of the format Database::factory() requires.
 125          * Additionally, a 'max lag' key should also be set on server maps, indicating how stale the
 126          * data can be before the load balancer tries to avoid using it. The map can have 'is static'
 127          * set to disable blocking  replication sync checks (intended for archive servers with
 128          * unchanging data).
 129          *
 130          * @param array $conf Parameters of LBFactory::__construct() as well as:
 131          *   - sectionsByDB                Map of database names to section names.
 132          *   - sectionLoads                2-d map. For each section, gives a map of server names to
 133          *                                 load ratios. For example:
 134          *                                 [
 135          *                                     'section1' => [
 136          *                                         'db1' => 100,
 137          *                                         'db2' => 100
 138          *                                     ]
 139          *                                 ]
 140          *   - serverTemplate              Server configuration map intended for Database::factory().
 141          *                                 Note that "host", "hostName" and "load" entries will be
 142          *                                 overridden by "sectionLoads" and "hostsByName".
 143          *   - groupLoadsBySection         3-d map giving server load ratios for each section/group.
 144          *                                 For example:
 145          *                                 [
 146          *                                     'section1' => [
 147          *                                         'group1' => [
 148          *                                             'db1' => 100,
 149          *                                             'db2' => 100
 150          *                                         ]
 151          *                                     ]
 152          *                                 ]
 153          *   - groupLoadsByDB              3-d map giving server load ratios by DB name.
 154          *   - hostsByName                 Map of hostname to IP address.
 155          *   - externalLoads               Map of external storage cluster name to server load map.
 156          *   - externalTemplateOverrides   Set of server configuration maps overriding
 157          *                                 "serverTemplate" for external storage.
 158          *   - templateOverridesByServer   2-d map overriding "serverTemplate" and
 159          *                                 "externalTemplateOverrides" on a server-by-server basis.
 160          *                                 Applies to both core and external storage.
 161          *   - templateOverridesBySection  2-d map overriding the server configuration maps by section.
 162          *   - templateOverridesByCluster  2-d map overriding the server configuration maps by external
 163          *                                 storage cluster.
 164          *   - masterTemplateOverrides     Server configuration map overrides for all master servers.
 165          *   - loadMonitorClass            Name of the LoadMonitor class to always use.
 166          *   - readOnlyBySection           A map of section name to read-only message.
 167          *                                 Missing or false for read/write.
 168          */
 169         public function __construct( array $conf ) {
 170                 parent::__construct( $conf );
 171
 172                 $this->conf = $conf;
 173                 $required = [ 'sectionsByDB', 'sectionLoads', 'serverTemplate' ];
 174                 $optional = [ 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
 175                         'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
 176                         'templateOverridesByCluster', 'templateOverridesBySection', 'masterTemplateOverrides',
 177                         'readOnlyBySection', 'loadMonitorClass' ];
 178
 179                 foreach ( $required as $key ) {
 180                         if ( !isset( $conf[$key] ) ) {
 181                                 throw new InvalidArgumentException( __CLASS__ . ": $key is required." );
 182                         }
 183                         $this->$key = $conf[$key];
 184                 }
 185
 186                 foreach ( $optional as $key ) {
 187                         if ( isset( $conf[$key] ) ) {
 188                                 $this->$key = $conf[$key];
 189                         }
 190                 }
 191         }
 192
 193         /**
 194          * @param bool|string $domain
 195          * @return string
 196          */
 197         private function getSectionForDomain( $domain = false ) {
 198                 if ( $this->lastDomain === $domain ) {
 199                         return $this->lastSection;
 200                 }
 201                 list( $dbName, ) = $this->getDBNameAndPrefix( $domain );
 202                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
 203                         $section = $this->sectionsByDB[$dbName];
 204                 } else {
 205                         $section = 'DEFAULT';
 206                 }
 207                 $this->lastSection = $section;
 208                 $this->lastDomain = $domain;
 209
 210                 return $section;
 211         }
 212
 213         /**
 214          * @param bool|string $domain
 215          * @return LoadBalancer
 216          */
 217         public function newMainLB( $domain = false ) {
 218                 list( $dbName, ) = $this->getDBNameAndPrefix( $domain );
 219                 $section = $this->getSectionForDomain( $domain );
 220                 if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
 221                         $groupLoads = $this->groupLoadsByDB[$dbName];
 222                 } else {
 223                         $groupLoads = [];
 224                 }
 225
 226                 if ( isset( $this->groupLoadsBySection[$section] ) ) {
 227                         $groupLoads = array_merge_recursive(
 228                                 $groupLoads, $this->groupLoadsBySection[$section] );
 229                 }
 230
 231                 $readOnlyReason = $this->readOnlyReason;
 232                 // Use the LB-specific read-only reason if everything isn't already read-only
 233                 if ( $readOnlyReason === false && isset( $this->readOnlyBySection[$section] ) ) {
 234                         $readOnlyReason = $this->readOnlyBySection[$section];
 235                 }
 236
 237                 $template = $this->serverTemplate;
 238                 if ( isset( $this->templateOverridesBySection[$section] ) ) {
 239                         $template = $this->templateOverridesBySection[$section] + $template;
 240                 }
 241
 242                 return $this->newLoadBalancer(
 243                         $template,
 244                         $this->sectionLoads[$section],
 245                         $groupLoads,
 246                         $readOnlyReason
 247                 );
 248         }
 249
 250         /**
 251          * @param DatabaseDomain|string|bool $domain Domain ID, or false for the current domain
 252          * @return LoadBalancer
 253          */
 254         public function getMainLB( $domain = false ) {
 255                 $section = $this->getSectionForDomain( $domain );
 256                 if ( !isset( $this->mainLBs[$section] ) ) {
 257                         $lb = $this->newMainLB( $domain );
 258                         $this->getChronologyProtector()->initLB( $lb );
 259                         $this->mainLBs[$section] = $lb;
 260                 }
 261
 262                 return $this->mainLBs[$section];
 263         }
 264
 265         public function newExternalLB( $cluster ) {
 266                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 267                         throw new InvalidArgumentException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
 268                 }
 269                 $template = $this->serverTemplate;
 270                 if ( $this->externalTemplateOverrides ) {
 271                         $template = $this->externalTemplateOverrides + $template;
 272                 }
 273                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 274                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 275                 }
 276
 277                 return $this->newLoadBalancer(
 278                         $template,
 279                         $this->externalLoads[$cluster],
 280                         [],
 281                         $this->readOnlyReason
 282                 );
 283         }
 284
 285         public function getExternalLB( $cluster ) {
 286                 if ( !isset( $this->extLBs[$cluster] ) ) {
 287                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster );
 288                         $this->getChronologyProtector()->initLB( $this->extLBs[$cluster] );
 289                 }
 290
 291                 return $this->extLBs[$cluster];
 292         }
 293
 294         public function getAllMainLBs() {
 295                 $lbs = [];
 296                 foreach ( $this->sectionsByDB as $db => $section ) {
 297                         if ( !isset( $lbs[$section] ) ) {
 298                                 $lbs[$section] = $this->getMainLB( $db );
 299                         }
 300                 }
 301
 302                 return $lbs;
 303         }
 304
 305         public function getAllExternalLBs() {
 306                 $lbs = [];
 307                 foreach ( $this->externalLoads as $cluster => $unused ) {
 308                         $lbs[$cluster] = $this->getExternalLB( $cluster );
 309                 }
 310
 311                 return $lbs;
 312         }
 313
 314         /**
 315          * Make a new load balancer object based on template and load array
 316          *
 317          * @param array $template
 318          * @param array $loads
 319          * @param array $groupLoads
 320          * @param string|bool $readOnlyReason
 321          * @return LoadBalancer
 322          */
 323         private function newLoadBalancer( $template, $loads, $groupLoads, $readOnlyReason ) {
 324                 $lb = new LoadBalancer( array_merge(
 325                         $this->baseLoadBalancerParams(),
 326                         [
 327                                 'servers' => $this->makeServerArray( $template, $loads, $groupLoads ),
 328                                 'loadMonitor' => [ 'class' => $this->loadMonitorClass ],
 329                                 'readOnlyReason' => $readOnlyReason
 330                         ]
 331                 ) );
 332                 $this->initLoadBalancer( $lb );
 333
 334                 return $lb;
 335         }
 336
 337         /**
 338          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 339          *
 340          * @param array $template
 341          * @param array $loads
 342          * @param array $groupLoads
 343          * @return array
 344          */
 345         private function makeServerArray( $template, $loads, $groupLoads ) {
 346                 $servers = [];
 347                 $master = true;
 348                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 349                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 350                         if ( !isset( $loads[$server] ) ) {
 351                                 $loads[$server] = 0;
 352                         }
 353                 }
 354                 foreach ( $loads as $serverName => $load ) {
 355                         $serverInfo = $template;
 356                         if ( $master ) {
 357                                 $serverInfo['master'] = true;
 358                                 if ( $this->masterTemplateOverrides ) {
 359                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 360                                 }
 361                                 $master = false;
 362                         } else {
 363                                 $serverInfo['replica'] = true;
 364                         }
 365                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 366                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 367                         }
 368                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 369                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 370                         }
 371                         if ( isset( $this->hostsByName[$serverName] ) ) {
 372                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 373                         } else {
 374                                 $serverInfo['host'] = $serverName;
 375                         }
 376                         $serverInfo['hostName'] = $serverName;
 377                         $serverInfo['load'] = $load;
 378                         $serverInfo += [ 'flags' => IDatabase::DBO_DEFAULT ];
 379
 380                         $servers[] = $serverInfo;
 381                 }
 382
 383                 return $servers;
 384         }
 385
 386         /**
 387          * Take a group load array indexed by group then server, and reindex it by server then group
 388          * @param array $groupLoads
 389          * @return array
 390          */
 391         private function reindexGroupLoads( $groupLoads ) {
 392                 $reindexed = [];
 393                 foreach ( $groupLoads as $group => $loads ) {
 394                         foreach ( $loads as $server => $load ) {
 395                                 $reindexed[$server][$group] = $load;
 396                         }
 397                 }
 398
 399                 return $reindexed;
 400         }
 401
 402         /**
 403          * @param DatabaseDomain|string|bool $domain Domain ID, or false for the current domain
 404          * @return array [database name, table prefix]
 405          */
 406         private function getDBNameAndPrefix( $domain = false ) {
 407                 $domain = ( $domain === false )
 408                         ? $this->localDomain
 409                         : DatabaseDomain::newFromId( $domain );
 410
 411                 return [ $domain->getDatabase(), $domain->getTablePrefix() ];
 412         }
 413
 414         /**
 415          * Execute a function for each tracked load balancer
 416          * The callback is called with the load balancer as the first parameter,
 417          * and $params passed as the subsequent parameters.
 418          * @param callable $callback
 419          * @param array $params
 420          */
 421         public function forEachLB( $callback, array $params = [] ) {
 422                 foreach ( $this->mainLBs as $lb ) {
 423                         call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
 424                 }
 425                 foreach ( $this->extLBs as $lb ) {
 426                         call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
 427                 }
 428         }
 429 }