--- /dev/null
+<?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
+ */
+
+/**
+ * Redis-based caching module for redis server >= 2.6.12
+ *
+ * @note: avoid use of Redis::MULTI transactions for twemproxy support
+ */
+class RedisBagOStuff extends BagOStuff {
+ /** @var RedisConnectionPool */
+ protected $redisPool;
+ /** @var array List of server names */
+ protected $servers;
+ /** @var array Map of (tag => server name) */
+ protected $serverTagMap;
+ /** @var bool */
+ protected $automaticFailover;
+
+ /**
+ * 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. Arrays keys can be used to specify the tag to
+ * hash on in place of the host/port. 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.
+ * @param array $params
+ */
+ function __construct( $params ) {
+ parent::__construct( $params );
+ $redisConf = [ 'serializer' => 'none' ]; // manage that in this class
+ foreach ( [ 'connectTimeout', 'persistent', 'password' ] as $opt ) {
+ if ( isset( $params[$opt] ) ) {
+ $redisConf[$opt] = $params[$opt];
+ }
+ }
+ $this->redisPool = RedisConnectionPool::singleton( $redisConf );
+
+ $this->servers = $params['servers'];
+ foreach ( $this->servers as $key => $server ) {
+ $this->serverTagMap[is_int( $key ) ? $server : $key] = $server;
+ }
+
+ if ( isset( $params['automaticFailover'] ) ) {
+ $this->automaticFailover = $params['automaticFailover'];
+ } else {
+ $this->automaticFailover = true;
+ }
+
+ $this->attrMap[self::ATTR_SYNCWRITES] = self::QOS_SYNCWRITES_NONE;
+ }
+
+ protected function doGet( $key, $flags = 0 ) {
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ return false;
+ }
+ try {
+ $value = $conn->get( $key );
+ $result = $this->unserialize( $value );
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $conn, $e );
+ }
+
+ $this->logRequest( 'get', $key, $server, $result );
+ return $result;
+ }
+
+ public function set( $key, $value, $expiry = 0, $flags = 0 ) {
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ return false;
+ }
+ $expiry = $this->convertToRelative( $expiry );
+ try {
+ if ( $expiry ) {
+ $result = $conn->setex( $key, $expiry, $this->serialize( $value ) );
+ } else {
+ // No expiry, that is very different from zero expiry in Redis
+ $result = $conn->set( $key, $this->serialize( $value ) );
+ }
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $conn, $e );
+ }
+
+ $this->logRequest( 'set', $key, $server, $result );
+ return $result;
+ }
+
+ public function delete( $key ) {
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ return false;
+ }
+ try {
+ $conn->delete( $key );
+ // Return true even if the key didn't exist
+ $result = true;
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $conn, $e );
+ }
+
+ $this->logRequest( 'delete', $key, $server, $result );
+ return $result;
+ }
+
+ public function getMulti( array $keys, $flags = 0 ) {
+ $batches = [];
+ $conns = [];
+ foreach ( $keys as $key ) {
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ continue;
+ }
+ $conns[$server] = $conn;
+ $batches[$server][] = $key;
+ }
+ $result = [];
+ 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]] = $this->unserialize( $value );
+ }
+ }
+ } catch ( RedisException $e ) {
+ $this->handleException( $conn, $e );
+ }
+ }
+
+ $this->debug( "getMulti for " . count( $keys ) . " keys " .
+ "returned " . count( $result ) . " results" );
+ return $result;
+ }
+
+ /**
+ * @param array $data
+ * @param int $expiry
+ * @return bool
+ */
+ public function setMulti( array $data, $expiry = 0 ) {
+ $batches = [];
+ $conns = [];
+ foreach ( $data as $key => $value ) {
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ continue;
+ }
+ $conns[$server] = $conn;
+ $batches[$server][] = $key;
+ }
+
+ $expiry = $this->convertToRelative( $expiry );
+ $result = true;
+ foreach ( $batches as $server => $batchKeys ) {
+ $conn = $conns[$server];
+ try {
+ $conn->multi( Redis::PIPELINE );
+ foreach ( $batchKeys as $key ) {
+ if ( $expiry ) {
+ $conn->setex( $key, $expiry, $this->serialize( $data[$key] ) );
+ } else {
+ $conn->set( $key, $this->serialize( $data[$key] ) );
+ }
+ }
+ $batchResult = $conn->exec();
+ if ( $batchResult === false ) {
+ $this->debug( "setMulti request to $server failed" );
+ continue;
+ }
+ foreach ( $batchResult as $value ) {
+ if ( $value === false ) {
+ $result = false;
+ }
+ }
+ } catch ( RedisException $e ) {
+ $this->handleException( $server, $conn, $e );
+ $result = false;
+ }
+ }
+
+ return $result;
+ }
+
+ public function add( $key, $value, $expiry = 0 ) {
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ return false;
+ }
+ $expiry = $this->convertToRelative( $expiry );
+ try {
+ if ( $expiry ) {
+ $result = $conn->set(
+ $key,
+ $this->serialize( $value ),
+ [ 'nx', 'ex' => $expiry ]
+ );
+ } else {
+ $result = $conn->setnx( $key, $this->serialize( $value ) );
+ }
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $conn, $e );
+ }
+
+ $this->logRequest( 'add', $key, $server, $result );
+ 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.
+ * @param string $key Key to increase
+ * @param int $value Value to add to $key (Default 1)
+ * @return int|bool New value or false on failure
+ */
+ public function incr( $key, $value = 1 ) {
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ return false;
+ }
+ try {
+ if ( !$conn->exists( $key ) ) {
+ return null;
+ }
+ // @FIXME: on races, the key may have a 0 TTL
+ $result = $conn->incrBy( $key, $value );
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $conn, $e );
+ }
+
+ $this->logRequest( 'incr', $key, $server, $result );
+ return $result;
+ }
+
+ public function changeTTL( $key, $expiry = 0 ) {
+ list( $server, $conn ) = $this->getConnection( $key );
+ if ( !$conn ) {
+ return false;
+ }
+
+ $expiry = $this->convertToRelative( $expiry );
+ try {
+ $result = $conn->expire( $key, $expiry );
+ } catch ( RedisException $e ) {
+ $result = false;
+ $this->handleException( $conn, $e );
+ }
+
+ $this->logRequest( 'expire', $key, $server, $result );
+ return $result;
+ }
+
+ public function modifySimpleRelayEvent( array $event ) {
+ if ( array_key_exists( 'val', $event ) ) {
+ $event['val'] = serialize( $event['val'] ); // this class uses PHP serialization
+ }
+
+ return $event;
+ }
+
+ /**
+ * @param mixed $data
+ * @return string
+ */
+ protected function serialize( $data ) {
+ // Serialize anything but integers so INCR/DECR work
+ // Do not store integer-like strings as integers to avoid type confusion (T62563)
+ return is_int( $data ) ? $data : serialize( $data );
+ }
+
+ /**
+ * @param string $data
+ * @return mixed
+ */
+ protected function unserialize( $data ) {
+ $int = intval( $data );
+ return $data === (string)$int ? $int : unserialize( $data );
+ }
+
+ /**
+ * Get a Redis object with a connection suitable for fetching the specified key
+ * @param string $key
+ * @return array (server, RedisConnRef) or (false, false)
+ */
+ protected function getConnection( $key ) {
+ $candidates = array_keys( $this->serverTagMap );
+
+ if ( count( $this->servers ) > 1 ) {
+ ArrayUtils::consistentHashSort( $candidates, $key, '/' );
+ if ( !$this->automaticFailover ) {
+ $candidates = array_slice( $candidates, 0, 1 );
+ }
+ }
+
+ while ( ( $tag = array_shift( $candidates ) ) !== null ) {
+ $server = $this->serverTagMap[$tag];
+ $conn = $this->redisPool->getConnection( $server, $this->logger );
+ if ( !$conn ) {
+ continue;
+ }
+
+ // If automatic failover is enabled, check that the server's link
+ // to its master (if any) is up -- but only if there are other
+ // viable candidates left to consider. Also, getMasterLinkStatus()
+ // does not work with twemproxy, though $candidates will be empty
+ // by now in such cases.
+ if ( $this->automaticFailover && $candidates ) {
+ try {
+ if ( $this->getMasterLinkStatus( $conn ) === 'down' ) {
+ // If the master cannot be reached, fail-over to the next server.
+ // If masters are in data-center A, and replica DBs in data-center B,
+ // this helps avoid the case were fail-over happens in A but not
+ // to the corresponding server in B (e.g. read/write mismatch).
+ continue;
+ }
+ } catch ( RedisException $e ) {
+ // Server is not accepting commands
+ $this->handleException( $conn, $e );
+ continue;
+ }
+ }
+
+ return [ $server, $conn ];
+ }
+
+ $this->setLastError( BagOStuff::ERR_UNREACHABLE );
+
+ return [ false, false ];
+ }
+
+ /**
+ * Check the master link status of a Redis server that is configured as a replica DB.
+ * @param RedisConnRef $conn
+ * @return string|null Master link status (either 'up' or 'down'), or null
+ * if the server is not a replica DB.
+ */
+ protected function getMasterLinkStatus( RedisConnRef $conn ) {
+ $info = $conn->info();
+ return isset( $info['master_link_status'] )
+ ? $info['master_link_status']
+ : null;
+ }
+
+ /**
+ * Log a fatal error
+ * @param string $msg
+ */
+ protected function logError( $msg ) {
+ $this->logger->error( "Redis error: $msg" );
+ }
+
+ /**
+ * 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 RedisConnRef $conn
+ * @param Exception $e
+ */
+ protected function handleException( RedisConnRef $conn, $e ) {
+ $this->setLastError( BagOStuff::ERR_UNEXPECTED );
+ $this->redisPool->handleError( $conn, $e );
+ }
+
+ /**
+ * Send information about a single request to the debug log
+ * @param string $method
+ * @param string $key
+ * @param string $server
+ * @param bool $result
+ */
+ public function logRequest( $method, $key, $server, $result ) {
+ $this->debug( "$method $key on $server: " .
+ ( $result === false ? "failure" : "success" ) );
+ }
+}
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