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356 lines
11 KiB
PHP
356 lines
11 KiB
PHP
<?php
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/**
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* Redis client connection pooling manager.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @defgroup Redis Redis
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* @author Aaron Schulz
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*/
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/**
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* Helper class to manage Redis connections.
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*
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* This can be used to get handle wrappers that free the handle when the wrapper
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* leaves scope. The maximum number of free handles (connections) is configurable.
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* This provides an easy way to cache connection handles that may also have state,
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* such as a handle does between multi() and exec(), and without hoarding connections.
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* The wrappers use PHP magic methods so that calling functions on them calls the
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* function of the actual Redis object handle.
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*
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* @ingroup Redis
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* @since 1.21
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*/
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class RedisConnectionPool {
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/**
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* @name Pool settings.
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* Settings there are shared for any connection made in this pool.
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* See the singleton() method documentation for more details.
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* @{
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*/
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/** @var string Connection timeout in seconds */
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protected $connectTimeout;
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/** @var string Plaintext auth password */
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protected $password;
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/** @var bool Whether connections persist */
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protected $persistent;
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/** @var integer Serializer to use (Redis::SERIALIZER_*) */
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protected $serializer;
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/** @} */
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/** @var integer Current idle pool size */
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protected $idlePoolSize = 0;
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/** @var Array (server name => ((connection info array),...) */
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protected $connections = array();
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/** @var Array (server name => UNIX timestamp) */
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protected $downServers = array();
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/** @var Array (pool ID => RedisConnectionPool) */
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protected static $instances = array();
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/** integer; seconds to cache servers as "down". */
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const SERVER_DOWN_TTL = 30;
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/**
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* @param array $options
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*/
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protected function __construct( array $options ) {
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if ( !class_exists( 'Redis' ) ) {
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throw new MWException( __CLASS__ . ' requires a Redis client library. ' .
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'See https://www.mediawiki.org/wiki/Redis#Setup' );
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}
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$this->connectTimeout = $options['connectTimeout'];
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$this->persistent = $options['persistent'];
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$this->password = $options['password'];
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if ( !isset( $options['serializer'] ) || $options['serializer'] === 'php' ) {
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$this->serializer = Redis::SERIALIZER_PHP;
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} elseif ( $options['serializer'] === 'igbinary' ) {
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$this->serializer = Redis::SERIALIZER_IGBINARY;
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} elseif ( $options['serializer'] === 'none' ) {
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$this->serializer = Redis::SERIALIZER_NONE;
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} else {
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throw new MWException( "Invalid serializer specified." );
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}
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}
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/**
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* @param $options Array
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* @return Array
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*/
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protected static function applyDefaultConfig( array $options ) {
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if ( !isset( $options['connectTimeout'] ) ) {
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$options['connectTimeout'] = 1;
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}
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if ( !isset( $options['persistent'] ) ) {
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$options['persistent'] = false;
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}
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if ( !isset( $options['password'] ) ) {
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$options['password'] = null;
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}
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return $options;
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}
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/**
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* @param $options Array
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* $options include:
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* - connectTimeout : The timeout for new connections, in seconds.
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* Optional, default is 1 second.
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* - persistent : Set this to true to allow connections to persist across
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* multiple web requests. False by default.
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* - password : The authentication password, will be sent to Redis in clear text.
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* Optional, if it is unspecified, no AUTH command will be sent.
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* - serializer : Set to "php", "igbinary", or "none". Default is "php".
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* @return RedisConnectionPool
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*/
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public static function singleton( array $options ) {
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$options = self::applyDefaultConfig( $options );
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// Map the options to a unique hash...
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ksort( $options ); // normalize to avoid pool fragmentation
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$id = sha1( serialize( $options ) );
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// Initialize the object at the hash as needed...
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if ( !isset( self::$instances[$id] ) ) {
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self::$instances[$id] = new self( $options );
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wfDebug( "Creating a new " . __CLASS__ . " instance with id $id." );
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}
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return self::$instances[$id];
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}
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/**
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* Get a connection to a redis server. Based on code in RedisBagOStuff.php.
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*
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* @param string $server A hostname/port combination or the absolute path of a UNIX socket.
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* If a hostname is specified but no port, port 6379 will be used.
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* @return RedisConnRef|bool Returns false on failure
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* @throws MWException
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*/
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public function getConnection( $server ) {
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// Check the listing "dead" servers which have had a connection errors.
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// Servers are marked dead for a limited period of time, to
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// avoid excessive overhead from repeated connection timeouts.
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if ( isset( $this->downServers[$server] ) ) {
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$now = time();
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if ( $now > $this->downServers[$server] ) {
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// Dead time expired
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unset( $this->downServers[$server] );
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} else {
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// Server is dead
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wfDebug( "server $server is marked down for another " .
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( $this->downServers[$server] - $now ) . " seconds, can't get connection" );
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return false;
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}
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}
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// Check if a connection is already free for use
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if ( isset( $this->connections[$server] ) ) {
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foreach ( $this->connections[$server] as &$connection ) {
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if ( $connection['free'] ) {
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$connection['free'] = false;
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--$this->idlePoolSize;
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return new RedisConnRef( $this, $server, $connection['conn'] );
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}
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}
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}
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if ( substr( $server, 0, 1 ) === '/' ) {
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// UNIX domain socket
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// These are required by the redis extension to start with a slash, but
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// we still need to set the port to a special value to make it work.
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$host = $server;
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$port = 0;
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} else {
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// TCP connection
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$hostPort = IP::splitHostAndPort( $server );
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if ( !$hostPort ) {
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throw new MWException( __CLASS__ . ": invalid configured server \"$server\"" );
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}
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list( $host, $port ) = $hostPort;
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if ( $port === false ) {
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$port = 6379;
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}
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}
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$conn = new Redis();
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try {
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if ( $this->persistent ) {
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$result = $conn->pconnect( $host, $port, $this->connectTimeout );
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} else {
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$result = $conn->connect( $host, $port, $this->connectTimeout );
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}
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if ( !$result ) {
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wfDebugLog( 'redis', "Could not connect to server $server" );
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// Mark server down for some time to avoid further timeouts
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$this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
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return false;
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}
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if ( $this->password !== null ) {
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if ( !$conn->auth( $this->password ) ) {
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wfDebugLog( 'redis', "Authentication error connecting to $server" );
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}
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}
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} catch ( RedisException $e ) {
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$this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
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wfDebugLog( 'redis', "Redis exception: " . $e->getMessage() . "\n" );
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return false;
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}
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if ( $conn ) {
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$conn->setOption( Redis::OPT_SERIALIZER, $this->serializer );
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$this->connections[$server][] = array( 'conn' => $conn, 'free' => false );
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return new RedisConnRef( $this, $server, $conn );
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} else {
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return false;
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}
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}
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/**
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* Mark a connection to a server as free to return to the pool
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*
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* @param $server string
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* @param $conn Redis
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* @return boolean
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*/
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public function freeConnection( $server, Redis $conn ) {
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$found = false;
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foreach ( $this->connections[$server] as &$connection ) {
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if ( $connection['conn'] === $conn && !$connection['free'] ) {
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$connection['free'] = true;
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++$this->idlePoolSize;
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break;
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}
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}
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$this->closeExcessIdleConections();
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return $found;
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}
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/**
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* Close any extra idle connections if there are more than the limit
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*
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* @return void
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*/
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protected function closeExcessIdleConections() {
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if ( $this->idlePoolSize <= count( $this->connections ) ) {
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return; // nothing to do (no more connections than servers)
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}
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foreach ( $this->connections as $server => &$serverConnections ) {
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foreach ( $serverConnections as $key => &$connection ) {
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if ( $connection['free'] ) {
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unset( $serverConnections[$key] );
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if ( --$this->idlePoolSize <= count( $this->connections ) ) {
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return; // done (no more connections than servers)
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}
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}
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}
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}
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}
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/**
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* The redis extension throws an exception in response to various read, write
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* and protocol errors. Sometimes it also closes the connection, sometimes
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* not. The safest response for us is to explicitly destroy the connection
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* object and let it be reopened during the next request.
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*
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* @param $server string
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* @param $cref RedisConnRef
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* @param $e RedisException
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* @return void
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*/
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public function handleException( $server, RedisConnRef $cref, RedisException $e ) {
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wfDebugLog( 'redis', "Redis exception on server $server: " . $e->getMessage() . "\n" );
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foreach ( $this->connections[$server] as $key => $connection ) {
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if ( $cref->isConnIdentical( $connection['conn'] ) ) {
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$this->idlePoolSize -= $connection['free'] ? 1 : 0;
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unset( $this->connections[$server][$key] );
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break;
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}
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}
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}
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}
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/**
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* Helper class to handle automatically marking connectons as reusable (via RAII pattern)
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*
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* @ingroup Redis
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* @since 1.21
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*/
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class RedisConnRef {
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/** @var RedisConnectionPool */
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protected $pool;
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/** @var Redis */
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protected $conn;
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protected $server; // string
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/**
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* @param $pool RedisConnectionPool
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* @param $server string
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* @param $conn Redis
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*/
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public function __construct( RedisConnectionPool $pool, $server, Redis $conn ) {
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$this->pool = $pool;
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$this->server = $server;
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$this->conn = $conn;
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}
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public function __call( $name, $arguments ) {
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return call_user_func_array( array( $this->conn, $name ), $arguments );
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}
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/**
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* @param string $script
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* @param array $params
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* @param integer $numKeys
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* @return mixed
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* @throws RedisException
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*/
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public function luaEval( $script, array $params, $numKeys ) {
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$sha1 = sha1( $script ); // 40 char hex
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$conn = $this->conn; // convenience
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// Try to run the server-side cached copy of the script
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$conn->clearLastError();
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$res = $conn->evalSha( $sha1, $params, $numKeys );
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// If the script is not in cache, use eval() to retry and cache it
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if ( preg_match( '/^NOSCRIPT/', $conn->getLastError() ) ) {
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$conn->clearLastError();
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$res = $conn->eval( $script, $params, $numKeys );
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wfDebugLog( 'redis', "Used eval() for Lua script $sha1." );
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}
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if ( $conn->getLastError() ) { // script bug?
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wfDebugLog( 'redis', "Lua script error: " . $conn->getLastError() );
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}
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return $res;
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}
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/**
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* @param RedisConnRef $conn
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* @return bool
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*/
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public function isConnIdentical( Redis $conn ) {
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return $this->conn === $conn;
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}
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function __destruct() {
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$this->pool->freeConnection( $this->server, $this->conn );
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}
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}
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