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<?php
/**
* PhpRedis client connection pooling manager.
*
* 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
* @defgroup Redis Redis
* @author Aaron Schulz
*/
/**
* Helper class to manage redis connections using PhpRedis.
*
* This can be used to get handle wrappers that free the handle when the wrapper
* leaves scope. The maximum number of free handles (connections) is configurable.
* This provides an easy way to cache connection handles that may also have state,
* such as a handle does between multi() and exec(), and without hoarding connections.
* The wrappers use PHP magic methods so that calling functions on them calls the
* function of the actual Redis object handle.
*
* @ingroup Redis
* @since 1.21
*/
class RedisConnectionPool {
// Settings for all connections in this pool
protected $connectTimeout; // string; connection timeout
protected $persistent; // bool; whether connections persist
protected $password; // string; plaintext auth password
protected $serializer; // integer; the serializer to use (Redis::SERIALIZER_*)
protected $idlePoolSize = 0; // integer; current idle pool size
/** @var Array (server name => ((connection info array),...) */
protected $connections = array();
/** @var Array (server name => UNIX timestamp) */
protected $downServers = array();
/** @var Array */
protected static $instances = array(); // (pool ID => RedisConnectionPool)
const SERVER_DOWN_TTL = 30; // integer; seconds to cache servers as "down"
/**
* $options include:
* - connectTimeout : The timeout for new connections, in seconds.
* Optional, default is 1 second.
* - persistent : Set this to true to allow connections to persist across
* multiple web requests. False by default.
* - password : The authentication password, will be sent to Redis in clear text.
* Optional, if it is unspecified, no AUTH command will be sent.
* - serializer : Set to "php", "igbinary", or "none". Default is "php".
* @param array $options
*/
protected function __construct( array $options ) {
if ( !extension_loaded( 'redis' ) ) {
throw new MWException( __CLASS__. ' requires the phpredis extension: ' .
'https://github.com/nicolasff/phpredis' );
}
$this->connectTimeout = $options['connectTimeout'];
$this->persistent = $options['persistent'];
$this->password = $options['password'];
if ( !isset( $options['serializer'] ) || $options['serializer'] === 'php' ) {
$this->serializer = Redis::SERIALIZER_PHP;
} elseif ( $options['serializer'] === 'igbinary' ) {
$this->serializer = Redis::SERIALIZER_IGBINARY;
} elseif ( $options['serializer'] === 'none' ) {
$this->serializer = Redis::SERIALIZER_NONE;
} else {
throw new MWException( "Invalid serializer specified." );
}
}
/**
* @param $options Array
* @return Array
*/
protected static function applyDefaultConfig( array $options ) {
if ( !isset( $options['connectTimeout'] ) ) {
$options['connectTimeout'] = 1;
}
if ( !isset( $options['persistent'] ) ) {
$options['persistent'] = false;
}
if ( !isset( $options['password'] ) ) {
$options['password'] = null;
}
return $options;
}
/**
* @param $options Array
* @return RedisConnectionPool
*/
public static function singleton( array $options ) {
$options = self::applyDefaultConfig( $options );
// Map the options to a unique hash...
ksort( $options ); // normalize to avoid pool fragmentation
$id = sha1( serialize( $options ) );
// Initialize the object at the hash as needed...
if ( !isset( self::$instances[$id] ) ) {
self::$instances[$id] = new self( $options );
wfDebug( "Creating a new " . __CLASS__ . " instance with id $id." );
}
return self::$instances[$id];
}
/**
* Get a connection to a redis server. Based on code in RedisBagOStuff.php.
*
* @param string $server A hostname/port combination or the absolute path of a UNIX socket.
* If a hostname is specified but no port, port 6379 will be used.
* @return RedisConnRef|bool Returns false on failure
* @throws MWException
*/
public function getConnection( $server ) {
// Check the listing "dead" servers which have had a connection errors.
// Servers are marked dead for a limited period of time, to
// avoid excessive overhead from repeated connection timeouts.
if ( isset( $this->downServers[$server] ) ) {
$now = time();
if ( $now > $this->downServers[$server] ) {
// Dead time expired
unset( $this->downServers[$server] );
} else {
// Server is dead
wfDebug( "server $server is marked down for another " .
( $this->downServers[$server] - $now ) . " seconds, can't get connection" );
return false;
}
}
// Check if a connection is already free for use
if ( isset( $this->connections[$server] ) ) {
foreach ( $this->connections[$server] as &$connection ) {
if ( $connection['free'] ) {
$connection['free'] = false;
--$this->idlePoolSize;
return new RedisConnRef( $this, $server, $connection['conn'] );
}
}
}
if ( substr( $server, 0, 1 ) === '/' ) {
// UNIX domain socket
// These are required by the redis extension to start with a slash, but
// we still need to set the port to a special value to make it work.
$host = $server;
$port = 0;
} else {
// TCP connection
$hostPort = IP::splitHostAndPort( $server );
if ( !$hostPort ) {
throw new MWException( __CLASS__.": invalid configured server \"$server\"" );
}
list( $host, $port ) = $hostPort;
if ( $port === false ) {
$port = 6379;
}
}
$conn = new Redis();
try {
if ( $this->persistent ) {
$result = $conn->pconnect( $host, $port, $this->connectTimeout );
} else {
$result = $conn->connect( $host, $port, $this->connectTimeout );
}
if ( !$result ) {
wfDebugLog( 'redis', "Could not connect to server $server" );
// Mark server down for some time to avoid further timeouts
$this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
return false;
}
if ( $this->password !== null ) {
if ( !$conn->auth( $this->password ) ) {
wfDebugLog( 'redis', "Authentication error connecting to $server" );
}
}
} catch ( RedisException $e ) {
$this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
wfDebugLog( 'redis', "Redis exception: " . $e->getMessage() . "\n" );
return false;
}
if ( $conn ) {
$conn->setOption( Redis::OPT_SERIALIZER, $this->serializer );
$this->connections[$server][] = array( 'conn' => $conn, 'free' => false );
return new RedisConnRef( $this, $server, $conn );
} else {
return false;
}
}
/**
* Mark a connection to a server as free to return to the pool
*
* @param $server string
* @param $conn Redis
* @return boolean
*/
public function freeConnection( $server, Redis $conn ) {
$found = false;
foreach ( $this->connections[$server] as &$connection ) {
if ( $connection['conn'] === $conn && !$connection['free'] ) {
$connection['free'] = true;
++$this->idlePoolSize;
break;
}
}
$this->closeExcessIdleConections();
return $found;
}
/**
* Close any extra idle connections if there are more than the limit
*
* @return void
*/
protected function closeExcessIdleConections() {
if ( $this->idlePoolSize <= count( $this->connections ) ) {
return; // nothing to do (no more connections than servers)
}
foreach ( $this->connections as $server => &$serverConnections ) {
foreach ( $serverConnections as $key => &$connection ) {
if ( $connection['free'] ) {
unset( $serverConnections[$key] );
if ( --$this->idlePoolSize <= count( $this->connections ) ) {
return; // done (no more connections than servers)
}
}
}
}
}
/**
* The redis extension throws an exception in response to various read, write
* and protocol errors. Sometimes it also closes the connection, sometimes
* not. The safest response for us is to explicitly destroy the connection
* object and let it be reopened during the next request.
*
* @param $server string
* @param $cref RedisConnRef
* @param $e RedisException
* @return void
*/
public function handleException( $server, RedisConnRef $cref, RedisException $e ) {
wfDebugLog( 'redis', "Redis exception on server $server: " . $e->getMessage() . "\n" );
foreach ( $this->connections[$server] as $key => $connection ) {
if ( $cref->isConnIdentical( $connection['conn'] ) ) {
$this->idlePoolSize -= $connection['free'] ? 1 : 0;
unset( $this->connections[$server][$key] );
break;
}
}
}
}
/**
* Helper class to handle automatically marking connectons as reusable (via RAII pattern)
*
* @ingroup Redis
* @since 1.21
*/
class RedisConnRef {
/** @var RedisConnectionPool */
protected $pool;
/** @var Redis */
protected $conn;
protected $server; // string
/**
* @param $pool RedisConnectionPool
* @param $server string
* @param $conn Redis
*/
public function __construct( RedisConnectionPool $pool, $server, Redis $conn ) {
$this->pool = $pool;
$this->server = $server;
$this->conn = $conn;
}
public function __call( $name, $arguments ) {
return call_user_func_array( array( $this->conn, $name ), $arguments );
}
public function isConnIdentical( Redis $conn ) {
return $this->conn === $conn;
}
function __destruct() {
$this->pool->freeConnection( $this->server, $this->conn );
}
}