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 IDatabase;
  27 use InvalidArgumentException;
  28
  29 /**
  30  * A multi-database, multi-master factory for Wikimedia and similar installations.
  31  * Ignores the old configuration globals.
  32  *
  33  * @ingroup Database
  34  */
  35 class LBFactoryMulti extends LBFactory {
  36         /** @var array A map of database names to section names */
  37         private $sectionsByDB;
  38
  39         /**
  40          * @var array A 2-d map. For each section, gives a map of server names to
  41          * load ratios
  42          */
  43         private $sectionLoads;
  44
  45         /**
  46          * @var array[] Server info associative array
  47          * @note The host, hostName and load entries will be overridden
  48          */
  49         private $serverTemplate;
  50
  51         // Optional settings
  52
  53         /** @var array A 3-d map giving server load ratios for each section and group */
  54         private $groupLoadsBySection = [];
  55
  56         /** @var array A 3-d map giving server load ratios by DB name */
  57         private $groupLoadsByDB = [];
  58
  59         /** @var array A map of hostname to IP address */
  60         private $hostsByName = [];
  61
  62         /** @var array A map of external storage cluster name to server load map */
  63         private $externalLoads = [];
  64
  65         /**
  66          * @var array A set of server info keys overriding serverTemplate for
  67          * external storage
  68          */
  69         private $externalTemplateOverrides;
  70
  71         /**
  72          * @var array A 2-d map overriding serverTemplate and
  73          * externalTemplateOverrides on a server-by-server basis. Applies to both
  74          * core and external storage
  75          */
  76         private $templateOverridesByServer;
  77
  78         /** @var array A 2-d map overriding the server info by section */
  79         private $templateOverridesBySection;
  80
  81         /** @var array A 2-d map overriding the server info by external storage cluster */
  82         private $templateOverridesByCluster;
  83
  84         /** @var array An override array for all master servers */
  85         private $masterTemplateOverrides;
  86
  87         /**
  88          * @var array|bool A map of section name to read-only message. Missing or
  89          * false for read/write
  90          */
  91         private $readOnlyBySection = [];
  92
  93         /** @var array Load balancer factory configuration */
  94         private $conf;
  95
  96         /** @var LoadBalancer[] */
  97         private $mainLBs = [];
  98
  99         /** @var LoadBalancer[] */
 100         private $extLBs = [];
 101
 102         /** @var string */
 103         private $loadMonitorClass = 'LoadMonitor';
 104
 105         /** @var string */
 106         private $lastDomain;
 107
 108         /** @var string */
 109         private $lastSection;
 110
 111         /**
 112          * @see LBFactory::__construct()
 113          *
 114          * Template override precedence (highest => lowest):
 115          *   - templateOverridesByServer
 116          *   - masterTemplateOverrides
 117          *   - templateOverridesBySection/templateOverridesByCluster
 118          *   - externalTemplateOverrides
 119          *   - serverTemplate
 120          * Overrides only work on top level keys (so nested values will not be merged).
 121          *
 122          * Server configuration maps should be of the format Database::factory() requires.
 123          * Additionally, a 'max lag' key should also be set on server maps, indicating how stale the
 124          * data can be before the load balancer tries to avoid using it. The map can have 'is static'
 125          * set to disable blocking  replication sync checks (intended for archive servers with
 126          * unchanging data).
 127          *
 128          * @param array $conf Parameters of LBFactory::__construct() as well as:
 129          *   - sectionsByDB                Map of database names to section names.
 130          *   - sectionLoads                2-d map. For each section, gives a map of server names to
 131          *                                 load ratios. For example:
 132          *                                 [
 133          *                                     'section1' => [
 134          *                                         'db1' => 100,
 135          *                                         'db2' => 100
 136          *                                     ]
 137          *                                 ]
 138          *   - serverTemplate              Server configuration map intended for Database::factory().
 139          *                                 Note that "host", "hostName" and "load" entries will be
 140          *                                 overridden by "sectionLoads" and "hostsByName".
 141          *   - groupLoadsBySection         3-d map giving server load ratios for each section/group.
 142          *                                 For example:
 143          *                                 [
 144          *                                     'section1' => [
 145          *                                         'group1' => [
 146          *                                             'db1' => 100,
 147          *                                             'db2' => 100
 148          *                                         ]
 149          *                                     ]
 150          *                                 ]
 151          *   - groupLoadsByDB              3-d map giving server load ratios by DB name.
 152          *   - hostsByName                 Map of hostname to IP address.
 153          *   - externalLoads               Map of external storage cluster name to server load map.
 154          *   - externalTemplateOverrides   Set of server configuration maps overriding
 155          *                                 "serverTemplate" for external storage.
 156          *   - templateOverridesByServer   2-d map overriding "serverTemplate" and
 157          *                                 "externalTemplateOverrides" on a server-by-server basis.
 158          *                                 Applies to both core and external storage.
 159          *   - templateOverridesBySection  2-d map overriding the server configuration maps by section.
 160          *   - templateOverridesByCluster  2-d map overriding the server configuration maps by external
 161          *                                 storage cluster.
 162          *   - masterTemplateOverrides     Server configuration map overrides for all master servers.
 163          *   - loadMonitorClass            Name of the LoadMonitor class to always use.
 164          *   - readOnlyBySection           A map of section name to read-only message.
 165          *                                 Missing or false for read/write.
 166          */
 167         public function __construct( array $conf ) {
 168                 parent::__construct( $conf );
 169
 170                 $this->conf = $conf;
 171                 $required = [ 'sectionsByDB', 'sectionLoads', 'serverTemplate' ];
 172                 $optional = [ 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
 173                         'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
 174                         'templateOverridesByCluster', 'templateOverridesBySection', 'masterTemplateOverrides',
 175                         'readOnlyBySection', 'loadMonitorClass' ];
 176
 177                 foreach ( $required as $key ) {
 178                         if ( !isset( $conf[$key] ) ) {
 179                                 throw new InvalidArgumentException( __CLASS__ . ": $key is required." );
 180                         }
 181                         $this->$key = $conf[$key];
 182                 }
 183
 184                 foreach ( $optional as $key ) {
 185                         if ( isset( $conf[$key] ) ) {
 186                                 $this->$key = $conf[$key];
 187                         }
 188                 }
 189         }
 190
 191         /**
 192          * @param bool|string $domain
 193          * @return string
 194          */
 195         private function getSectionForDomain( $domain = false ) {
 196                 if ( $this->lastDomain === $domain ) {
 197                         return $this->lastSection;
 198                 }
 199                 list( $dbName, ) = $this->getDBNameAndPrefix( $domain );
 200                 if ( isset( $this->sectionsByDB[$dbName] ) ) {
 201                         $section = $this->sectionsByDB[$dbName];
 202                 } else {
 203                         $section = 'DEFAULT';
 204                 }
 205                 $this->lastSection = $section;
 206                 $this->lastDomain = $domain;
 207
 208                 return $section;
 209         }
 210
 211         /**
 212          * @param bool|string $domain
 213          * @return LoadBalancer
 214          */
 215         public function newMainLB( $domain = false ) {
 216                 list( $dbName, ) = $this->getDBNameAndPrefix( $domain );
 217                 $section = $this->getSectionForDomain( $domain );
 218                 if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
 219                         $groupLoads = $this->groupLoadsByDB[$dbName];
 220                 } else {
 221                         $groupLoads = [];
 222                 }
 223
 224                 if ( isset( $this->groupLoadsBySection[$section] ) ) {
 225                         $groupLoads = array_merge_recursive(
 226                                 $groupLoads, $this->groupLoadsBySection[$section] );
 227                 }
 228
 229                 $readOnlyReason = $this->readOnlyReason;
 230                 // Use the LB-specific read-only reason if everything isn't already read-only
 231                 if ( $readOnlyReason === false && isset( $this->readOnlyBySection[$section] ) ) {
 232                         $readOnlyReason = $this->readOnlyBySection[$section];
 233                 }
 234
 235                 $template = $this->serverTemplate;
 236                 if ( isset( $this->templateOverridesBySection[$section] ) ) {
 237                         $template = $this->templateOverridesBySection[$section] + $template;
 238                 }
 239
 240                 return $this->newLoadBalancer(
 241                         $template,
 242                         $this->sectionLoads[$section],
 243                         $groupLoads,
 244                         $readOnlyReason
 245                 );
 246         }
 247
 248         /**
 249          * @param DatabaseDomain|string|bool $domain Domain ID, or false for the current domain
 250          * @return LoadBalancer
 251          */
 252         public function getMainLB( $domain = false ) {
 253                 $section = $this->getSectionForDomain( $domain );
 254                 if ( !isset( $this->mainLBs[$section] ) ) {
 255                         $this->mainLBs[$section] = $this->newMainLB( $domain );
 256                 }
 257
 258                 return $this->mainLBs[$section];
 259         }
 260
 261         public function newExternalLB( $cluster ) {
 262                 if ( !isset( $this->externalLoads[$cluster] ) ) {
 263                         throw new InvalidArgumentException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
 264                 }
 265                 $template = $this->serverTemplate;
 266                 if ( $this->externalTemplateOverrides ) {
 267                         $template = $this->externalTemplateOverrides + $template;
 268                 }
 269                 if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
 270                         $template = $this->templateOverridesByCluster[$cluster] + $template;
 271                 }
 272
 273                 return $this->newLoadBalancer(
 274                         $template,
 275                         $this->externalLoads[$cluster],
 276                         [],
 277                         $this->readOnlyReason
 278                 );
 279         }
 280
 281         public function getExternalLB( $cluster ) {
 282                 if ( !isset( $this->extLBs[$cluster] ) ) {
 283                         $this->extLBs[$cluster] = $this->newExternalLB( $cluster );
 284                 }
 285
 286                 return $this->extLBs[$cluster];
 287         }
 288
 289         public function getAllMainLBs() {
 290                 $lbs = [];
 291                 foreach ( $this->sectionsByDB as $db => $section ) {
 292                         if ( !isset( $lbs[$section] ) ) {
 293                                 $lbs[$section] = $this->getMainLB( $db );
 294                         }
 295                 }
 296
 297                 return $lbs;
 298         }
 299
 300         public function getAllExternalLBs() {
 301                 $lbs = [];
 302                 foreach ( $this->externalLoads as $cluster => $unused ) {
 303                         $lbs[$cluster] = $this->getExternalLB( $cluster );
 304                 }
 305
 306                 return $lbs;
 307         }
 308
 309         /**
 310          * Make a new load balancer object based on template and load array
 311          *
 312          * @param array $template
 313          * @param array $loads
 314          * @param array $groupLoads
 315          * @param string|bool $readOnlyReason
 316          * @return LoadBalancer
 317          */
 318         private function newLoadBalancer( $template, $loads, $groupLoads, $readOnlyReason ) {
 319                 $lb = new LoadBalancer( array_merge(
 320                         $this->baseLoadBalancerParams(),
 321                         [
 322                                 'servers' => $this->makeServerArray( $template, $loads, $groupLoads ),
 323                                 'loadMonitor' => [ 'class' => $this->loadMonitorClass ],
 324                                 'readOnlyReason' => $readOnlyReason
 325                         ]
 326                 ) );
 327                 $this->initLoadBalancer( $lb );
 328
 329                 return $lb;
 330         }
 331
 332         /**
 333          * Make a server array as expected by LoadBalancer::__construct, using a template and load array
 334          *
 335          * @param array $template
 336          * @param array $loads
 337          * @param array $groupLoads
 338          * @return array
 339          */
 340         private function makeServerArray( $template, $loads, $groupLoads ) {
 341                 $servers = [];
 342                 $master = true;
 343                 $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
 344                 foreach ( $groupLoadsByServer as $server => $stuff ) {
 345                         if ( !isset( $loads[$server] ) ) {
 346                                 $loads[$server] = 0;
 347                         }
 348                 }
 349                 foreach ( $loads as $serverName => $load ) {
 350                         $serverInfo = $template;
 351                         if ( $master ) {
 352                                 $serverInfo['master'] = true;
 353                                 if ( $this->masterTemplateOverrides ) {
 354                                         $serverInfo = $this->masterTemplateOverrides + $serverInfo;
 355                                 }
 356                                 $master = false;
 357                         } else {
 358                                 $serverInfo['replica'] = true;
 359                         }
 360                         if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
 361                                 $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
 362                         }
 363                         if ( isset( $groupLoadsByServer[$serverName] ) ) {
 364                                 $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
 365                         }
 366                         if ( isset( $this->hostsByName[$serverName] ) ) {
 367                                 $serverInfo['host'] = $this->hostsByName[$serverName];
 368                         } else {
 369                                 $serverInfo['host'] = $serverName;
 370                         }
 371                         $serverInfo['hostName'] = $serverName;
 372                         $serverInfo['load'] = $load;
 373                         $serverInfo += [ 'flags' => IDatabase::DBO_DEFAULT ];
 374
 375                         $servers[] = $serverInfo;
 376                 }
 377
 378                 return $servers;
 379         }
 380
 381         /**
 382          * Take a group load array indexed by group then server, and reindex it by server then group
 383          * @param array $groupLoads
 384          * @return array
 385          */
 386         private function reindexGroupLoads( $groupLoads ) {
 387                 $reindexed = [];
 388                 foreach ( $groupLoads as $group => $loads ) {
 389                         foreach ( $loads as $server => $load ) {
 390                                 $reindexed[$server][$group] = $load;
 391                         }
 392                 }
 393
 394                 return $reindexed;
 395         }
 396
 397         /**
 398          * @param DatabaseDomain|string|bool $domain Domain ID, or false for the current domain
 399          * @return array [database name, table prefix]
 400          */
 401         private function getDBNameAndPrefix( $domain = false ) {
 402                 $domain = ( $domain === false )
 403                         ? $this->localDomain
 404                         : DatabaseDomain::newFromId( $domain );
 405
 406                 return [ $domain->getDatabase(), $domain->getTablePrefix() ];
 407         }
 408
 409         /**
 410          * Execute a function for each tracked load balancer
 411          * The callback is called with the load balancer as the first parameter,
 412          * and $params passed as the subsequent parameters.
 413          * @param callable $callback
 414          * @param array $params
 415          */
 416         public function forEachLB( $callback, array $params = [] ) {
 417                 foreach ( $this->mainLBs as $lb ) {
 418                         call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
 419                 }
 420                 foreach ( $this->extLBs as $lb ) {
 421                         call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
 422                 }
 423         }
 424 }