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