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+<?php
+/**
+ * Object caching using Redis (http://redis.io/).
+ *
+ * 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
+ */
+
+
+class RedisBagOStuff extends BagOStuff {
+ protected $connectTimeout, $persistent, $password, $automaticFailover;
+
+ /**
+ * A list of server names, from $params['servers']
+ */
+ protected $servers;
+
+ /**
+ * A cache of Redis objects, representing connections to Redis servers.
+ * The key is the server name.
+ */
+ protected $conns = array();
+
+ /**
+ * An array listing "dead" servers which have had a connection error in
+ * the past. Servers are marked dead for a limited period of time, to
+ * avoid excessive overhead from repeated connection timeouts. The key in
+ * the array is the server name, the value is the UNIX timestamp at which
+ * the server is resurrected.
+ */
+ protected $deadServers = array();
+
+ /**
+ * Construct a RedisBagOStuff object. Parameters are:
+ *
+ * - servers: An array of server names. A server name may be a hostname,
+ * a hostname/port combination or the absolute path of a UNIX socket.
+ * If a hostname is specified but no port, the standard port number
+ * 6379 will be used. Required.
+ *
+ * - 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.
+ *
+ * - automaticFailover: If this is false, then each key will be mapped to
+ * a single server, and if that server is down, any requests for that key
+ * will fail. If this is true, a connection failure will cause the client
+ * to immediately try the next server in the list (as determined by a
+ * consistent hashing algorithm). True by default. This has the
+ * potential to create consistency issues if a server is slow enough to
+ * flap, for example if it is in swap death.
+ */
+ function __construct( $params ) {
+ if ( !extension_loaded( 'redis' ) ) {
+ throw new MWException( __CLASS__. ' requires the phpredis extension: ' .
+ 'https://github.com/nicolasff/phpredis' );
+ }
+
+ $this->servers = $params['servers'];
+ $this->connectTimeout = isset( $params['connectTimeout'] )
+ ? $params['connectTimeout'] : 1;
+ $this->persistent = !empty( $params['persistent'] );
+ if ( isset( $params['password'] ) ) {
+ $this->password = $params['password'];
+ }
+ if ( isset( $params['automaticFailover'] ) ) {
+ $this->automaticFailover = $params['automaticFailover'];
+ } else {
+ $this->automaticFailover = true;
+ }
+ }
+
+ public function get( $key ) {
+ wfProfileIn( __METHOD__ );
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ wfProfileOut( __METHOD__ );
+ return false;
+ }
+ try {
+ $result = $conn->get( $key );
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $server, $e );
+ }
+ $this->logRequest( 'get', $key, $server, $result );
+ wfProfileOut( __METHOD__ );
+ return $result;
+ }
+
+ public function set( $key, $value, $expiry = 0 ) {
+ wfProfileIn( __METHOD__ );
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ wfProfileOut( __METHOD__ );
+ return false;
+ }
+ $expiry = $this->convertToRelative( $expiry );
+ try {
+ if ( !$expiry ) {
+ // No expiry, that is very different from zero expiry in Redis
+ $result = $conn->set( $key, $value );
+ } else {
+ $result = $conn->setex( $key, $expiry, $value );
+ }
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $server, $e );
+ }
+
+ $this->logRequest( 'set', $key, $server, $result );
+ wfProfileOut( __METHOD__ );
+ return $result;
+ }
+
+ public function delete( $key, $time = 0 ) {
+ wfProfileIn( __METHOD__ );
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ wfProfileOut( __METHOD__ );
+ return false;
+ }
+ try {
+ $conn->delete( $key );
+ // Return true even if the key didn't exist
+ $result = true;
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $server, $e );
+ }
+ $this->logRequest( 'delete', $key, $server, $result );
+ wfProfileOut( __METHOD__ );
+ return $result;
+ }
+
+ public function getMulti( array $keys ) {
+ wfProfileIn( __METHOD__ );
+ $batches = array();
+ $conns = array();
+ foreach ( $keys as $key ) {
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ continue;
+ }
+ $conns[$server] = $conn;
+ $batches[$server][] = $key;
+ }
+ $result = array();
+ foreach ( $batches as $server => $batchKeys ) {
+ $conn = $conns[$server];
+ try {
+ $conn->multi( Redis::PIPELINE );
+ foreach ( $batchKeys as $key ) {
+ $conn->get( $key );
+ }
+ $batchResult = $conn->exec();
+ if ( $batchResult === false ) {
+ $this->debug( "multi request to $server failed" );
+ continue;
+ }
+ foreach ( $batchResult as $i => $value ) {
+ if ( $value !== false ) {
+ $result[$batchKeys[$i]] = $value;
+ }
+ }
+ } catch ( RedisException $e ) {
+ $this->handleException( $server, $e );
+ }
+ }
+
+ $this->debug( "getMulti for " . count( $keys ) . " keys " .
+ "returned " . count( $result ) . " results" );
+ wfProfileOut( __METHOD__ );
+ return $result;
+ }
+
+ public function add( $key, $value, $expiry = 0 ) {
+ wfProfileIn( __METHOD__ );
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ wfProfileOut( __METHOD__ );
+ return false;
+ }
+ $expiry = $this->convertToRelative( $expiry );
+ try {
+ $result = $conn->setnx( $key, $value );
+ if ( $result && $expiry ) {
+ $conn->expire( $key, $expiry );
+ }
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $server, $e );
+ }
+ $this->logRequest( 'add', $key, $server, $result );
+ wfProfileOut( __METHOD__ );
+ return $result;
+ }
+
+ /**
+ * Non-atomic implementation of replace(). Could perhaps be done atomically
+ * with WATCH or scripting, but this function is rarely used.
+ */
+ public function replace( $key, $value, $expiry = 0 ) {
+ wfProfileIn( __METHOD__ );
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ wfProfileOut( __METHOD__ );
+ return false;
+ }
+ if ( !$conn->exists( $key ) ) {
+ wfProfileOut( __METHOD__ );
+ return false;
+ }
+
+ $expiry = $this->convertToRelative( $expiry );
+ try {
+ if ( !$expiry ) {
+ $result = $conn->set( $key, $value );
+ } else {
+ $result = $conn->setex( $key, $expiry, $value );
+ }
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $server, $e );
+ }
+
+ $this->logRequest( 'replace', $key, $server, $result );
+ wfProfileOut( __METHOD__ );
+ return $result;
+ }
+
+ /**
+ * Non-atomic implementation of incr().
+ *
+ * Probably all callers actually want incr() to atomically initialise
+ * values to zero if they don't exist, as provided by the Redis INCR
+ * command. But we are constrained by the memcached-like interface to
+ * return null in that case. Once the key exists, further increments are
+ * atomic.
+ */
+ public function incr( $key, $value = 1 ) {
+ wfProfileIn( __METHOD__ );
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ wfProfileOut( __METHOD__ );
+ return false;
+ }
+ if ( !$conn->exists( $key ) ) {
+ wfProfileOut( __METHOD__ );
+ return null;
+ }
+ try {
+ $result = $conn->incrBy( $key, $value );
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $server, $e );
+ }
+
+ $this->logRequest( 'incr', $key, $server, $result );
+ wfProfileOut( __METHOD__ );
+ return $result;
+ }
+
+ /**
+ * Get a Redis object with a connection suitable for fetching the specified key
+ */
+ protected function getConnection( $key ) {
+ if ( count( $this->servers ) === 1 ) {
+ $candidates = $this->servers;
+ } else {
+ // Use consistent hashing
+ $hashes = array();
+ foreach ( $this->servers as $server ) {
+ $hashes[$server] = md5( $server . '/' . $key );
+ }
+ asort( $hashes );
+ if ( !$this->automaticFailover ) {
+ reset( $hashes );
+ $candidates = array( key( $hashes ) );
+ } else {
+ $candidates = array_keys( $hashes );
+ }
+ }
+
+ foreach ( $candidates as $server ) {
+ $conn = $this->getConnectionToServer( $server );
+ if ( $conn ) {
+ return array( $server, $conn );
+ }
+ }
+ return array( false, false );
+ }
+
+ /**
+ * Get a connection to the server with the specified name. Connections
+ * are cached, and failures are persistent to avoid multiple timeouts.
+ *
+ * @return Redis object, or false on failure
+ */
+ protected function getConnectionToServer( $server ) {
+ if ( isset( $this->deadServers[$server] ) ) {
+ $now = time();
+ if ( $now > $this->deadServers[$server] ) {
+ // Dead time expired
+ unset( $this->deadServers[$server] );
+ } else {
+ // Server is dead
+ $this->debug( "server $server is marked down for another " .
+ ($this->deadServers[$server] - $now ) .
+ " seconds, can't get connection" );
+ return false;
+ }
+ }
+
+ if ( isset( $this->conns[$server] ) ) {
+ return $this->conns[$server];
+ }
+
+ 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 ) {
+ $this->debug( "opening persistent connection to $host:$port" );
+ $result = $conn->pconnect( $host, $port, $this->connectTimeout );
+ } else {
+ $this->debug( "opening non-persistent connection to $host:$port" );
+ $result = $conn->connect( $host, $port, $this->connectTimeout );
+ }
+ if ( !$result ) {
+ $this->logError( "could not connect to server $server" );
+ // Mark server down for 30s to avoid further timeouts
+ $this->deadServers[$server] = time() + 30;
+ return false;
+ }
+ if ( $this->password !== null ) {
+ if ( !$conn->auth( $this->password ) ) {
+ $this->logError( "authentication error connecting to $server" );
+ }
+ }
+ } catch ( RedisException $e ) {
+ $this->deadServers[$server] = time() + 30;
+ wfDebugLog( 'redis', "Redis exception: " . $e->getMessage() . "\n" );
+ return false;
+ }
+
+ $conn->setOption( Redis::OPT_SERIALIZER, Redis::SERIALIZER_PHP );
+ $this->conns[$server] = $conn;
+ return $conn;
+ }
+
+ /**
+ * Log a fatal error
+ */
+ protected function logError( $msg ) {
+ wfDebugLog( 'redis', "Redis error: $msg\n" );
+ }
+
+ /**
+ * 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.
+ */
+ protected function handleException( $server, $e ) {
+ wfDebugLog( 'redis', "Redis exception on server $server: " . $e->getMessage() . "\n" );
+ unset( $this->conns[$server] );
+ }
+
+ /**
+ * Send information about a single request to the debug log
+ */
+ public function logRequest( $method, $key, $server, $result ) {
+ $this->debug( "$method $key on $server: " .
+ ( $result === false ? "failure" : "success" ) );
+ }
+}
+
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