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