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+<?php
+/**
+ * Advanced generator of database load balancing objects for database farms.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Database
+ */
+
+namespace Wikimedia\Rdbms;
+
+use InvalidArgumentException;
+
+/**
+ * A multi-database, multi-master factory for Wikimedia and similar installations.
+ * Ignores the old configuration globals.
+ *
+ * @ingroup Database
+ */
+class LBFactoryMulti extends LBFactory {
+ /** @var array A map of database names to section names */
+ private $sectionsByDB;
+
+ /**
+ * @var array A 2-d map. For each section, gives a map of server names to
+ * load ratios
+ */
+ private $sectionLoads;
+
+ /**
+ * @var array[] Server info associative array
+ * @note The host, hostName and load entries will be overridden
+ */
+ private $serverTemplate;
+
+ // Optional settings
+
+ /** @var array A 3-d map giving server load ratios for each section and group */
+ private $groupLoadsBySection = [];
+
+ /** @var array A 3-d map giving server load ratios by DB name */
+ private $groupLoadsByDB = [];
+
+ /** @var array A map of hostname to IP address */
+ private $hostsByName = [];
+
+ /** @var array A map of external storage cluster name to server load map */
+ private $externalLoads = [];
+
+ /**
+ * @var array A set of server info keys overriding serverTemplate for
+ * external storage
+ */
+ private $externalTemplateOverrides;
+
+ /**
+ * @var array A 2-d map overriding serverTemplate and
+ * externalTemplateOverrides on a server-by-server basis. Applies to both
+ * core and external storage
+ */
+ private $templateOverridesByServer;
+
+ /** @var array A 2-d map overriding the server info by section */
+ private $templateOverridesBySection;
+
+ /** @var array A 2-d map overriding the server info by external storage cluster */
+ private $templateOverridesByCluster;
+
+ /** @var array An override array for all master servers */
+ private $masterTemplateOverrides;
+
+ /**
+ * @var array|bool A map of section name to read-only message. Missing or
+ * false for read/write
+ */
+ private $readOnlyBySection = [];
+
+ /** @var array Load balancer factory configuration */
+ private $conf;
+
+ /** @var LoadBalancer[] */
+ private $mainLBs = [];
+
+ /** @var LoadBalancer[] */
+ private $extLBs = [];
+
+ /** @var string */
+ private $loadMonitorClass = 'LoadMonitor';
+
+ /** @var string */
+ private $lastDomain;
+
+ /** @var string */
+ private $lastSection;
+
+ /** @var int */
+ private $maxLag = self::MAX_LAG_DEFAULT;
+
+ /** @var int Default 'maxLag' when unspecified */
+ const MAX_LAG_DEFAULT = 10;
+
+ /**
+ * @see LBFactory::__construct()
+ *
+ * Template override precedence (highest => lowest):
+ * - templateOverridesByServer
+ * - masterTemplateOverrides
+ * - templateOverridesBySection/templateOverridesByCluster
+ * - externalTemplateOverrides
+ * - serverTemplate
+ * Overrides only work on top level keys (so nested values will not be merged).
+ *
+ * Server configuration maps should be of the format Database::factory() requires.
+ * Additionally, a 'max lag' key should also be set on server maps, indicating how stale the
+ * data can be before the load balancer tries to avoid using it. The map can have 'is static'
+ * set to disable blocking replication sync checks (intended for archive servers with
+ * unchanging data).
+ *
+ * @param array $conf Parameters of LBFactory::__construct() as well as:
+ * - sectionsByDB Map of database names to section names.
+ * - sectionLoads 2-d map. For each section, gives a map of server names to
+ * load ratios. For example:
+ * [
+ * 'section1' => [
+ * 'db1' => 100,
+ * 'db2' => 100
+ * ]
+ * ]
+ * - serverTemplate Server configuration map intended for Database::factory().
+ * Note that "host", "hostName" and "load" entries will be
+ * overridden by "sectionLoads" and "hostsByName".
+ * - groupLoadsBySection 3-d map giving server load ratios for each section/group.
+ * For example:
+ * [
+ * 'section1' => [
+ * 'group1' => [
+ * 'db1' => 100,
+ * 'db2' => 100
+ * ]
+ * ]
+ * ]
+ * - groupLoadsByDB 3-d map giving server load ratios by DB name.
+ * - hostsByName Map of hostname to IP address.
+ * - externalLoads Map of external storage cluster name to server load map.
+ * - externalTemplateOverrides Set of server configuration maps overriding
+ * "serverTemplate" for external storage.
+ * - templateOverridesByServer 2-d map overriding "serverTemplate" and
+ * "externalTemplateOverrides" on a server-by-server basis.
+ * Applies to both core and external storage.
+ * - templateOverridesBySection 2-d map overriding the server configuration maps by section.
+ * - templateOverridesByCluster 2-d map overriding the server configuration maps by external
+ * storage cluster.
+ * - masterTemplateOverrides Server configuration map overrides for all master servers.
+ * - loadMonitorClass Name of the LoadMonitor class to always use.
+ * - maxLag Avoid replica DBs with more lag than this many seconds.
+ * - readOnlyBySection A map of section name to read-only message.
+ * Missing or false for read/write.
+ */
+ public function __construct( array $conf ) {
+ parent::__construct( $conf );
+
+ $this->conf = $conf;
+ $required = [ 'sectionsByDB', 'sectionLoads', 'serverTemplate' ];
+ $optional = [ 'groupLoadsBySection', 'groupLoadsByDB', 'hostsByName',
+ 'externalLoads', 'externalTemplateOverrides', 'templateOverridesByServer',
+ 'templateOverridesByCluster', 'templateOverridesBySection', 'masterTemplateOverrides',
+ 'readOnlyBySection', 'maxLag', 'loadMonitorClass' ];
+
+ foreach ( $required as $key ) {
+ if ( !isset( $conf[$key] ) ) {
+ throw new InvalidArgumentException( __CLASS__ . ": $key is required." );
+ }
+ $this->$key = $conf[$key];
+ }
+
+ foreach ( $optional as $key ) {
+ if ( isset( $conf[$key] ) ) {
+ $this->$key = $conf[$key];
+ }
+ }
+ }
+
+ /**
+ * @param bool|string $domain
+ * @return string
+ */
+ private function getSectionForDomain( $domain = false ) {
+ if ( $this->lastDomain === $domain ) {
+ return $this->lastSection;
+ }
+ list( $dbName, ) = $this->getDBNameAndPrefix( $domain );
+ if ( isset( $this->sectionsByDB[$dbName] ) ) {
+ $section = $this->sectionsByDB[$dbName];
+ } else {
+ $section = 'DEFAULT';
+ }
+ $this->lastSection = $section;
+ $this->lastDomain = $domain;
+
+ return $section;
+ }
+
+ /**
+ * @param bool|string $domain
+ * @return LoadBalancer
+ */
+ public function newMainLB( $domain = false ) {
+ list( $dbName, ) = $this->getDBNameAndPrefix( $domain );
+ $section = $this->getSectionForDomain( $domain );
+ if ( isset( $this->groupLoadsByDB[$dbName] ) ) {
+ $groupLoads = $this->groupLoadsByDB[$dbName];
+ } else {
+ $groupLoads = [];
+ }
+
+ if ( isset( $this->groupLoadsBySection[$section] ) ) {
+ $groupLoads = array_merge_recursive(
+ $groupLoads, $this->groupLoadsBySection[$section] );
+ }
+
+ $readOnlyReason = $this->readOnlyReason;
+ // Use the LB-specific read-only reason if everything isn't already read-only
+ if ( $readOnlyReason === false && isset( $this->readOnlyBySection[$section] ) ) {
+ $readOnlyReason = $this->readOnlyBySection[$section];
+ }
+
+ $template = $this->serverTemplate;
+ if ( isset( $this->templateOverridesBySection[$section] ) ) {
+ $template = $this->templateOverridesBySection[$section] + $template;
+ }
+
+ return $this->newLoadBalancer(
+ $template,
+ $this->sectionLoads[$section],
+ $groupLoads,
+ $readOnlyReason
+ );
+ }
+
+ /**
+ * @param DatabaseDomain|string|bool $domain Domain ID, or false for the current domain
+ * @return LoadBalancer
+ */
+ public function getMainLB( $domain = false ) {
+ $section = $this->getSectionForDomain( $domain );
+ if ( !isset( $this->mainLBs[$section] ) ) {
+ $this->mainLBs[$section] = $this->newMainLB( $domain );
+ }
+
+ return $this->mainLBs[$section];
+ }
+
+ public function newExternalLB( $cluster ) {
+ if ( !isset( $this->externalLoads[$cluster] ) ) {
+ throw new InvalidArgumentException( __METHOD__ . ": Unknown cluster \"$cluster\"" );
+ }
+ $template = $this->serverTemplate;
+ if ( $this->externalTemplateOverrides ) {
+ $template = $this->externalTemplateOverrides + $template;
+ }
+ if ( isset( $this->templateOverridesByCluster[$cluster] ) ) {
+ $template = $this->templateOverridesByCluster[$cluster] + $template;
+ }
+
+ return $this->newLoadBalancer(
+ $template,
+ $this->externalLoads[$cluster],
+ [],
+ $this->readOnlyReason
+ );
+ }
+
+ public function getExternalLB( $cluster ) {
+ if ( !isset( $this->extLBs[$cluster] ) ) {
+ $this->extLBs[$cluster] = $this->newExternalLB( $cluster );
+ }
+
+ return $this->extLBs[$cluster];
+ }
+
+ public function getAllMainLBs() {
+ $lbs = [];
+ foreach ( $this->sectionsByDB as $db => $section ) {
+ if ( !isset( $lbs[$section] ) ) {
+ $lbs[$section] = $this->getMainLB( $db );
+ }
+ }
+
+ return $lbs;
+ }
+
+ public function getAllExternalLBs() {
+ $lbs = [];
+ foreach ( $this->externalLoads as $cluster => $unused ) {
+ $lbs[$cluster] = $this->getExternalLB( $cluster );
+ }
+
+ return $lbs;
+ }
+
+ /**
+ * Make a new load balancer object based on template and load array
+ *
+ * @param array $template
+ * @param array $loads
+ * @param array $groupLoads
+ * @param string|bool $readOnlyReason
+ * @return LoadBalancer
+ */
+ private function newLoadBalancer( $template, $loads, $groupLoads, $readOnlyReason ) {
+ $lb = new LoadBalancer( array_merge(
+ $this->baseLoadBalancerParams(),
+ [
+ 'servers' => $this->makeServerArray( $template, $loads, $groupLoads ),
+ 'maxLag' => $this->maxLag,
+ 'loadMonitor' => [ 'class' => $this->loadMonitorClass ],
+ 'readOnlyReason' => $readOnlyReason
+ ]
+ ) );
+ $this->initLoadBalancer( $lb );
+
+ return $lb;
+ }
+
+ /**
+ * Make a server array as expected by LoadBalancer::__construct, using a template and load array
+ *
+ * @param array $template
+ * @param array $loads
+ * @param array $groupLoads
+ * @return array
+ */
+ private function makeServerArray( $template, $loads, $groupLoads ) {
+ $servers = [];
+ $master = true;
+ $groupLoadsByServer = $this->reindexGroupLoads( $groupLoads );
+ foreach ( $groupLoadsByServer as $server => $stuff ) {
+ if ( !isset( $loads[$server] ) ) {
+ $loads[$server] = 0;
+ }
+ }
+ foreach ( $loads as $serverName => $load ) {
+ $serverInfo = $template;
+ if ( $master ) {
+ $serverInfo['master'] = true;
+ if ( $this->masterTemplateOverrides ) {
+ $serverInfo = $this->masterTemplateOverrides + $serverInfo;
+ }
+ $master = false;
+ } else {
+ $serverInfo['replica'] = true;
+ }
+ if ( isset( $this->templateOverridesByServer[$serverName] ) ) {
+ $serverInfo = $this->templateOverridesByServer[$serverName] + $serverInfo;
+ }
+ if ( isset( $groupLoadsByServer[$serverName] ) ) {
+ $serverInfo['groupLoads'] = $groupLoadsByServer[$serverName];
+ }
+ if ( isset( $this->hostsByName[$serverName] ) ) {
+ $serverInfo['host'] = $this->hostsByName[$serverName];
+ } else {
+ $serverInfo['host'] = $serverName;
+ }
+ $serverInfo['hostName'] = $serverName;
+ $serverInfo['load'] = $load;
+ $serverInfo += [ 'flags' => IDatabase::DBO_DEFAULT ];
+
+ $servers[] = $serverInfo;
+ }
+
+ return $servers;
+ }
+
+ /**
+ * Take a group load array indexed by group then server, and reindex it by server then group
+ * @param array $groupLoads
+ * @return array
+ */
+ private function reindexGroupLoads( $groupLoads ) {
+ $reindexed = [];
+ foreach ( $groupLoads as $group => $loads ) {
+ foreach ( $loads as $server => $load ) {
+ $reindexed[$server][$group] = $load;
+ }
+ }
+
+ return $reindexed;
+ }
+
+ /**
+ * @param DatabaseDomain|string|bool $domain Domain ID, or false for the current domain
+ * @return array [database name, table prefix]
+ */
+ private function getDBNameAndPrefix( $domain = false ) {
+ $domain = ( $domain === false )
+ ? $this->localDomain
+ : DatabaseDomain::newFromId( $domain );
+
+ return [ $domain->getDatabase(), $domain->getTablePrefix() ];
+ }
+
+ /**
+ * Execute a function for each tracked load balancer
+ * The callback is called with the load balancer as the first parameter,
+ * and $params passed as the subsequent parameters.
+ * @param callable $callback
+ * @param array $params
+ */
+ public function forEachLB( $callback, array $params = [] ) {
+ foreach ( $this->mainLBs as $lb ) {
+ call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
+ }
+ foreach ( $this->extLBs as $lb ) {
+ call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
+ }
+ }
+}
generated by cgit v1.2.1 (git 2.18.0) at 2024-05-05 02:06:25 +0000