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<?php
/**
* Generator of database load balancing objects.
*
* 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 simple single-master LBFactory that gets its configuration from the b/c globals
*/
class LBFactorySimple extends LBFactory {
/** @var LoadBalancer */
private $mainLB;
/** @var LoadBalancer[] */
private $extLBs = [];
/** @var array[] Map of (server index => server config) */
private $servers = [];
/** @var array[] Map of (cluster => (server index => server config)) */
private $externalClusters = [];
/** @var string */
private $loadMonitorClass;
/** @var int */
private $maxLag;
/** @var int Default 'maxLag' when unspecified */
const MAX_LAG_DEFAULT = 10;
/**
* @see LBFactory::__construct()
* @param array $conf Parameters of LBFactory::__construct() as well as:
* - servers : list of server configuration maps to Database::factory().
* Additionally, the server maps should have a 'load' key, which is used to decide
* how often clients connect to one server verses the others. 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).
* - externalClusters : map of cluster names to server arrays. The servers arrays have the
* same format as "servers" above.
*/
public function __construct( array $conf ) {
parent::__construct( $conf );
$this->servers = isset( $conf['servers'] ) ? $conf['servers'] : [];
foreach ( $this->servers as $i => $server ) {
if ( $i == 0 ) {
$this->servers[$i]['master'] = true;
} else {
$this->servers[$i]['replica'] = true;
}
}
$this->externalClusters = isset( $conf['externalClusters'] )
? $conf['externalClusters']
: [];
$this->loadMonitorClass = isset( $conf['loadMonitorClass'] )
? $conf['loadMonitorClass']
: 'LoadMonitor';
$this->maxLag = isset( $conf['maxLag'] ) ? $conf['maxLag'] : self::MAX_LAG_DEFAULT;
}
/**
* @param bool|string $domain
* @return LoadBalancer
*/
public function newMainLB( $domain = false ) {
return $this->newLoadBalancer( $this->servers );
}
/**
* @param bool|string $domain
* @return LoadBalancer
*/
public function getMainLB( $domain = false ) {
if ( !isset( $this->mainLB ) ) {
$this->mainLB = $this->newMainLB( $domain );
}
return $this->mainLB;
}
public function newExternalLB( $cluster ) {
if ( !isset( $this->externalClusters[$cluster] ) ) {
throw new InvalidArgumentException( __METHOD__ . ": Unknown cluster \"$cluster\"." );
}
return $this->newLoadBalancer( $this->externalClusters[$cluster] );
}
public function getExternalLB( $cluster ) {
if ( !isset( $this->extLBs[$cluster] ) ) {
$this->extLBs[$cluster] = $this->newExternalLB( $cluster );
}
return $this->extLBs[$cluster];
}
public function getAllMainLBs() {
return [ 'DEFAULT' => $this->getMainLB() ];
}
public function getAllExternalLBs() {
$lbs = [];
foreach ( $this->externalClusters as $cluster => $unused ) {
$lbs[$cluster] = $this->getExternalLB( $cluster );
}
return $lbs;
}
private function newLoadBalancer( array $servers ) {
$lb = new LoadBalancer( array_merge(
$this->baseLoadBalancerParams(),
[
'servers' => $servers,
'maxLag' => $this->maxLag,
'loadMonitor' => [ 'class' => $this->loadMonitorClass ],
]
) );
$this->initLoadBalancer( $lb );
return $lb;
}
/**
* 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 = [] ) {
if ( isset( $this->mainLB ) ) {
call_user_func_array( $callback, array_merge( [ $this->mainLB ], $params ) );
}
foreach ( $this->extLBs as $lb ) {
call_user_func_array( $callback, array_merge( [ $lb ], $params ) );
}
}
}
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