Current File : /www/varak.net/wiki.varak.net/includes/libs/rdbms/lbfactory/LBFactoryMulti.php
<?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 ) {
$callback( $lb, ...$params );
}
foreach ( $this->extLBs as $lb ) {
$callback( $lb, ...$params );
}
}
}
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