MemcachedPeclBagOStuff.php

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<?php
class MemcachedPeclBagOStuff extends MemcachedBagOStuff {
    protected $syncClient;
    protected $asyncClient;
 
    protected $syncClientIsBuffering = false;
    protected $hasUnflushedChanges = false;
 
    private static $OPTS_SYNC_WRITES = [
        Memcached::OPT_NO_BLOCK => false, // async I/O (using TCP buffers)
        Memcached::OPT_BUFFER_WRITES => false // libmemcached buffers
    ];
    private static $OPTS_ASYNC_WRITES = [
        Memcached::OPT_NO_BLOCK => true, // async I/O (using TCP buffers)
        Memcached::OPT_BUFFER_WRITES => true // libmemcached buffers
    ];
 
    public function __construct( $params ) {
        parent::__construct( $params );
 
        // Default class-specific parameters
        $params += [
            'compress_threshold' => 1500,
            'connect_timeout' => 0.5,
            'serializer' => 'php',
            'use_binary_protocol' => false,
            'allow_tcp_nagle_delay' => true
        ];
 
        if ( $params['persistent'] ) {
            // The pool ID must be unique to the server/option combination.
            // The Memcached object is essentially shared for each pool ID.
            // We can only reuse a pool ID if we keep the config consistent.
            $connectionPoolId = md5( serialize( $params ) );
            $syncClient = new Memcached( "$connectionPoolId-sync" );
            // Avoid clobbering the main thread-shared Memcached instance
            $asyncClient = new Memcached( "$connectionPoolId-async" );
        } else {
            $syncClient = new Memcached();
            $asyncClient = null;
        }
 
        $this->initializeClient( $syncClient, $params, self::$OPTS_SYNC_WRITES );
        if ( $asyncClient ) {
            $this->initializeClient( $asyncClient, $params, self::$OPTS_ASYNC_WRITES );
        }
 
        // Set the main client and any dedicated one for buffered writes
        $this->syncClient = $syncClient;
        $this->asyncClient = $asyncClient;
        // The compression threshold is an undocumented php.ini option for some
        // reason. There's probably not much harm in setting it globally, for
        // compatibility with the settings for the PHP client.
        ini_set( 'memcached.compression_threshold', $params['compress_threshold'] );
    }
 
    private function initializeClient( Memcached $client, array $params, array $options ) {
        if ( $client->getServerList() ) {
            $this->logger->debug( __METHOD__ . ": pre-initialized client instance." );
 
            return; // preserve persistent handle
        }
 
        $this->logger->debug( __METHOD__ . ": initializing new client instance." );
 
        $options += [
            Memcached::OPT_NO_BLOCK => false,
            Memcached::OPT_BUFFER_WRITES => false,
            // Network protocol (ASCII or binary)
            Memcached::OPT_BINARY_PROTOCOL => $params['use_binary_protocol'],
            // Set various network timeouts
            Memcached::OPT_CONNECT_TIMEOUT => $params['connect_timeout'] * 1000,
            Memcached::OPT_SEND_TIMEOUT => $params['timeout'],
            Memcached::OPT_RECV_TIMEOUT => $params['timeout'],
            Memcached::OPT_POLL_TIMEOUT => $params['timeout'] / 1000,
            // Avoid pointless delay when sending/fetching large blobs
            Memcached::OPT_TCP_NODELAY => !$params['allow_tcp_nagle_delay'],
            // Set libketama mode since it's recommended by the documentation
            Memcached::OPT_LIBKETAMA_COMPATIBLE => true
        ];
        if ( isset( $params['retry_timeout'] ) ) {
            $options[Memcached::OPT_RETRY_TIMEOUT] = $params['retry_timeout'];
        }
        if ( isset( $params['server_failure_limit'] ) ) {
            $options[Memcached::OPT_SERVER_FAILURE_LIMIT] = $params['server_failure_limit'];
        }
        if ( $params['serializer'] === 'php' ) {
            $options[Memcached::OPT_SERIALIZER] = Memcached::SERIALIZER_PHP;
        } elseif ( $params['serializer'] === 'igbinary' ) {
            // @phan-suppress-next-line PhanImpossibleCondition
            if ( !Memcached::HAVE_IGBINARY ) {
                throw new RuntimeException(
                    __CLASS__ . ': the igbinary extension is not available ' .
                    'but igbinary serialization was requested.'
                );
            }
            $options[Memcached::OPT_SERIALIZER] = Memcached::SERIALIZER_IGBINARY;
        }
 
        if ( !$client->setOptions( $options ) ) {
            throw new RuntimeException(
                "Invalid options: " . json_encode( $options, JSON_PRETTY_PRINT )
            );
        }
 
        $servers = [];
        foreach ( $params['servers'] as $host ) {
            if ( preg_match( '/^\[(.+)\]:(\d+)$/', $host, $m ) ) {
                $servers[] = [ $m[1], (int)$m[2] ]; // (ip, port)
            } elseif ( preg_match( '/^([^:]+):(\d+)$/', $host, $m ) ) {
                $servers[] = [ $m[1], (int)$m[2] ]; // (ip or path, port)
            } else {
                $servers[] = [ $host, false ]; // (ip or path, port)
            }
        }
 
        if ( !$client->addServers( $servers ) ) {
            throw new RuntimeException( "Failed to inject server address list" );
        }
    }
 
    protected function doGet( $key, $flags = 0, &$casToken = null ) {
        $getToken = ( $casToken === self::PASS_BY_REF );
        $casToken = null;
 
        $this->debug( "get($key)" );
 
        $routeKey = $this->validateKeyAndPrependRoute( $key );
 
        $client = $this->acquireSyncClient();
        // T257003: only require "gets" (instead of "get") when a CAS token is needed
        if ( $getToken ) {
            $flags = Memcached::GET_EXTENDED;
            $res = $client->get( $routeKey, null, $flags );
            if ( is_array( $res ) ) {
                $result = $res['value'];
                $casToken = $res['cas'];
            } else {
                $result = false;
                $casToken = null;
            }
        } else {
            $result = $client->get( $routeKey );
        }
 
        return $this->checkResult( $key, $result );
    }
 
    protected function doSet( $key, $value, $exptime = 0, $flags = 0 ) {
        $this->debug( "set($key)" );
 
        $routeKey = $this->validateKeyAndPrependRoute( $key );
        $client = $this->acquireSyncClient();
        $result = $client->set( $routeKey, $value, $this->fixExpiry( $exptime ) );
 
        return ( $result === false && $client->getResultCode() === Memcached::RES_NOTSTORED )
            // "Not stored" is always used as the mcrouter response with AllAsyncRoute
            ? true
            : $this->checkResult( $key, $result );
    }
 
    protected function doCas( $casToken, $key, $value, $exptime = 0, $flags = 0 ) {
        $this->debug( "cas($key)" );
 
        $routeKey = $this->validateKeyAndPrependRoute( $key );
        $result = $this->acquireSyncClient()->cas(
            $casToken,
            $routeKey,
            $value, $this->fixExpiry( $exptime )
        );
 
        return $this->checkResult( $key, $result );
    }
 
    protected function doDelete( $key, $flags = 0 ) {
        $this->debug( "delete($key)" );
 
        $routeKey = $this->validateKeyAndPrependRoute( $key );
        $client = $this->acquireSyncClient();
        $result = $client->delete( $routeKey );
 
        return ( $result === false && $client->getResultCode() === Memcached::RES_NOTFOUND )
            // "Not found" is counted as success in our interface
            ? true
            : $this->checkResult( $key, $result );
    }
 
    protected function doAdd( $key, $value, $exptime = 0, $flags = 0 ) {
        $this->debug( "add($key)" );
 
        $routeKey = $this->validateKeyAndPrependRoute( $key );
        $result = $this->acquireSyncClient()->add(
            $routeKey,
            $value,
            $this->fixExpiry( $exptime )
        );
 
        return $this->checkResult( $key, $result );
    }
 
    public function incr( $key, $value = 1, $flags = 0 ) {
        $this->debug( "incr($key)" );
 
        $routeKey = $this->validateKeyAndPrependRoute( $key );
        $result = $this->acquireSyncClient()->increment( $routeKey, $value );
 
        return $this->checkResult( $key, $result );
    }
 
    public function decr( $key, $value = 1, $flags = 0 ) {
        $this->debug( "decr($key)" );
 
        $routeKey = $this->validateKeyAndPrependRoute( $key );
        $result = $this->acquireSyncClient()->decrement( $routeKey, $value );
 
        return $this->checkResult( $key, $result );
    }
 
    public function setNewPreparedValues( array $valueByKey ) {
        // The PECL driver does the serializing and will not reuse anything from here
        $sizes = [];
        foreach ( $valueByKey as $value ) {
            $sizes[] = $this->guessSerialValueSize( $value );
        }
 
        return $sizes;
    }
 
    protected function checkResult( $key, $result ) {
        if ( $result !== false ) {
            return $result;
        }
 
        $client = $this->syncClient;
        switch ( $client->getResultCode() ) {
            case Memcached::RES_SUCCESS:
                break;
            case Memcached::RES_DATA_EXISTS:
            case Memcached::RES_NOTSTORED:
            case Memcached::RES_NOTFOUND:
                $this->debug( "result: " . $client->getResultMessage() );
                break;
            default:
                $msg = $client->getResultMessage();
                $logCtx = [];
                if ( $key !== false ) {
                    $server = $client->getServerByKey( $key );
                    $logCtx['memcached-server'] = "{$server['host']}:{$server['port']}";
                    $logCtx['memcached-key'] = $key;
                    $msg = "Memcached error for key \"{memcached-key}\" " .
                        "on server \"{memcached-server}\": $msg";
                } else {
                    $msg = "Memcached error: $msg";
                }
                $this->logger->error( $msg, $logCtx );
                $this->setLastError( BagOStuff::ERR_UNEXPECTED );
        }
        return $result;
    }
 
    protected function doGetMulti( array $keys, $flags = 0 ) {
        $this->debug( 'getMulti(' . implode( ', ', $keys ) . ')' );
 
        $routeKeys = [];
        foreach ( $keys as $key ) {
            $routeKeys[] = $this->validateKeyAndPrependRoute( $key );
        }
 
        // The PECL implementation uses multi-key "get"/"gets"; no need to pipeline.
        // T257003: avoid Memcached::GET_EXTENDED; no tokens are needed and that requires "gets"
        // https://github.com/libmemcached/libmemcached/blob/eda2becbec24363f56115fa5d16d38a2d1f54775/libmemcached/get.cc#L272
        $resByRouteKey = $this->acquireSyncClient()->getMulti( $routeKeys ) ?: [];
 
        if ( is_array( $resByRouteKey ) ) {
            $res = [];
            foreach ( $resByRouteKey as $routeKey => $value ) {
                $res[$this->stripRouteFromKey( $routeKey )] = $value;
            }
        } else {
            $res = false;
        }
 
        return $this->checkResult( false, $res );
    }
 
    protected function doSetMulti( array $data, $exptime = 0, $flags = 0 ) {
        $this->debug( 'setMulti(' . implode( ', ', array_keys( $data ) ) . ')' );
 
        $exptime = $this->fixExpiry( $exptime );
        $dataByRouteKey = [];
        foreach ( $data as $key => $value ) {
            $dataByRouteKey[$this->validateKeyAndPrependRoute( $key )] = $value;
        }
 
        // The PECL implementation is a naïve for-loop so use async I/O to pipeline;
        // https://github.com/php-memcached-dev/php-memcached/blob/master/php_memcached.c#L1852
        if ( $this->fieldHasFlags( $flags, self::WRITE_BACKGROUND ) ) {
            $client = $this->acquireAsyncClient();
            $result = $client->setMulti( $dataByRouteKey, $exptime );
            $this->releaseAsyncClient( $client );
        } else {
            $result = $this->acquireSyncClient()->setMulti( $dataByRouteKey, $exptime );
        }
 
        return $this->checkResult( false, $result );
    }
 
    protected function doDeleteMulti( array $keys, $flags = 0 ) {
        $this->debug( 'deleteMulti(' . implode( ', ', $keys ) . ')' );
 
        $routeKeys = [];
        foreach ( $keys as $key ) {
            $routeKeys[] = $this->validateKeyAndPrependRoute( $key );
        }
 
        // The PECL implementation is a naïve for-loop so use async I/O to pipeline;
        // https://github.com/php-memcached-dev/php-memcached/blob/7443d16d02fb73cdba2e90ae282446f80969229c/php_memcached.c#L1852
        if ( $this->fieldHasFlags( $flags, self::WRITE_BACKGROUND ) ) {
            $client = $this->acquireAsyncClient();
            $resultArray = $client->deleteMulti( $routeKeys ) ?: [];
            $this->releaseAsyncClient( $client );
        } else {
            $resultArray = $this->acquireSyncClient()->deleteMulti( $routeKeys ) ?: [];
        }
 
        $result = true;
        foreach ( $resultArray as $code ) {
            if ( !in_array( $code, [ true, Memcached::RES_NOTFOUND ], true ) ) {
                // "Not found" is counted as success in our interface
                $result = false;
            }
        }
 
        return $this->checkResult( false, $result );
    }
 
    protected function doChangeTTL( $key, $exptime, $flags ) {
        $this->debug( "touch($key)" );
 
        $routeKey = $this->validateKeyAndPrependRoute( $key );
        $result = $this->acquireSyncClient()->touch( $routeKey, $this->fixExpiry( $exptime ) );
 
        return $this->checkResult( $key, $result );
    }
 
    protected function serialize( $value ) {
        if ( is_int( $value ) ) {
            return $value;
        }
 
        $serializer = $this->syncClient->getOption( Memcached::OPT_SERIALIZER );
        if ( $serializer === Memcached::SERIALIZER_PHP ) {
            return serialize( $value );
        } elseif ( $serializer === Memcached::SERIALIZER_IGBINARY ) {
            return igbinary_serialize( $value );
        }
 
        throw new UnexpectedValueException( __METHOD__ . ": got serializer '$serializer'." );
    }
 
    protected function unserialize( $value ) {
        if ( $this->isInteger( $value ) ) {
            return (int)$value;
        }
 
        $serializer = $this->syncClient->getOption( Memcached::OPT_SERIALIZER );
        if ( $serializer === Memcached::SERIALIZER_PHP ) {
            return unserialize( $value );
        } elseif ( $serializer === Memcached::SERIALIZER_IGBINARY ) {
            return igbinary_unserialize( $value );
        }
 
        throw new UnexpectedValueException( __METHOD__ . ": got serializer '$serializer'." );
    }
 
    private function acquireSyncClient() {
        if ( $this->syncClientIsBuffering ) {
            throw new RuntimeException( "The main (unbuffered I/O) client is locked" );
        }
 
        if ( $this->hasUnflushedChanges ) {
            // Force a synchronous flush of async writes so that their changes are visible
            $this->syncClient->fetch();
            if ( $this->asyncClient ) {
                $this->asyncClient->fetch();
            }
            $this->hasUnflushedChanges = false;
        }
 
        return $this->syncClient;
    }
 
    private function acquireAsyncClient() {
        if ( $this->asyncClient ) {
            return $this->asyncClient; // dedicated buffering instance
        }
 
        // Modify the main instance to temporarily buffer writes
        $this->syncClientIsBuffering = true;
        $this->syncClient->setOptions( self::$OPTS_ASYNC_WRITES );
 
        return $this->syncClient;
    }
 
    private function releaseAsyncClient( $client ) {
        $this->hasUnflushedChanges = true;
 
        if ( !$this->asyncClient ) {
            // This is the main instance; make it stop buffering writes again
            $client->setOptions( self::$OPTS_SYNC_WRITES );
            $this->syncClientIsBuffering = false;
        }
    }
}