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