RedisConnectionPool.php

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<?php
class RedisConnectionPool {
    protected $connectTimeout;
    protected $password;
    protected $persistent;
    protected $serializer;
    protected $idlePoolSize = 0;

    protected $connections = array();
    protected $downServers = array();

    protected static $instances = array();

    const SERVER_DOWN_TTL = 30;

    protected function __construct( array $options ) {
        if ( !class_exists( 'Redis' ) ) {
            throw new MWException( __CLASS__ . ' requires a Redis client library. ' .
                'See https://www.mediawiki.org/wiki/Redis#Setup' );
        }
        $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." );
        }
    }

    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;
    }

    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];
    }

    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;
        }
    }

    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;
    }

    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)
                    }
                }
            }
        }
    }

    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;
            }
        }
    }
}

class RedisConnRef {
    protected $pool;
    protected $conn;

    protected $server; // string

    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 luaEval( $script, array $params, $numKeys ) {
        $sha1 = sha1( $script ); // 40 char hex
        $conn = $this->conn; // convenience

        // Try to run the server-side cached copy of the script
        $conn->clearLastError();
        $res = $conn->evalSha( $sha1, $params, $numKeys );
        // If the script is not in cache, use eval() to retry and cache it
        if ( preg_match( '/^NOSCRIPT/', $conn->getLastError() ) ) {
            $conn->clearLastError();
            $res = $conn->eval( $script, $params, $numKeys );
            wfDebugLog( 'redis', "Used eval() for Lua script $sha1." );
        }

        if ( $conn->getLastError() ) { // script bug?
            wfDebugLog( 'redis', "Lua script error: " . $conn->getLastError() );
        }

        return $res;
    }

    public function isConnIdentical( Redis $conn ) {
        return $this->conn === $conn;
    }

    function __destruct() {
        $this->pool->freeConnection( $this->server, $this->conn );
    }
}