441 lines
13 KiB
PHP
441 lines
13 KiB
PHP
<?php
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/**
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* Object caching using Redis (http://redis.io/).
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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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*/
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/**
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* Redis-based caching module for redis server >= 2.6.12
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*
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* @note Avoid use of Redis::MULTI transactions for twemproxy support
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*
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* @ingroup Cache
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* @ingroup Redis
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*/
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class RedisBagOStuff extends BagOStuff {
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/** @var RedisConnectionPool */
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protected $redisPool;
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/** @var array List of server names */
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protected $servers;
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/** @var array Map of (tag => server name) */
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protected $serverTagMap;
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/** @var bool */
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protected $automaticFailover;
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/**
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* Construct a RedisBagOStuff object. Parameters are:
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*
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* - servers: An array of server names. A server name may be a hostname,
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* a hostname/port combination or the absolute path of a UNIX socket.
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* If a hostname is specified but no port, the standard port number
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* 6379 will be used. Arrays keys can be used to specify the tag to
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* hash on in place of the host/port. Required.
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*
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* - connectTimeout: The timeout for new connections, in seconds. Optional,
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* default is 1 second.
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*
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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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*
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* - password: The authentication password, will be sent to Redis in
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* clear text. Optional, if it is unspecified, no AUTH command will be
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* sent.
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*
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* - automaticFailover: If this is false, then each key will be mapped to
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* a single server, and if that server is down, any requests for that key
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* will fail. If this is true, a connection failure will cause the client
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* to immediately try the next server in the list (as determined by a
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* consistent hashing algorithm). True by default. This has the
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* potential to create consistency issues if a server is slow enough to
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* flap, for example if it is in swap death.
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* @param array $params
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*/
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function __construct( $params ) {
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parent::__construct( $params );
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$redisConf = [ 'serializer' => 'none' ]; // manage that in this class
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foreach ( [ 'connectTimeout', 'persistent', 'password' ] as $opt ) {
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if ( isset( $params[$opt] ) ) {
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$redisConf[$opt] = $params[$opt];
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}
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}
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$this->redisPool = RedisConnectionPool::singleton( $redisConf );
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$this->servers = $params['servers'];
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foreach ( $this->servers as $key => $server ) {
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$this->serverTagMap[is_int( $key ) ? $server : $key] = $server;
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}
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$this->automaticFailover = $params['automaticFailover'] ?? true;
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$this->attrMap[self::ATTR_SYNCWRITES] = self::QOS_SYNCWRITES_NONE;
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}
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protected function doGet( $key, $flags = 0 ) {
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$casToken = null;
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return $this->getWithToken( $key, $casToken, $flags );
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}
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protected function getWithToken( $key, &$casToken, $flags = 0 ) {
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list( $server, $conn ) = $this->getConnection( $key );
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if ( !$conn ) {
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return false;
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}
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try {
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$value = $conn->get( $key );
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$casToken = $value;
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$result = $this->unserialize( $value );
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} catch ( RedisException $e ) {
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$result = false;
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$this->handleException( $conn, $e );
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}
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$this->logRequest( 'get', $key, $server, $result );
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return $result;
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}
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public function set( $key, $value, $expiry = 0, $flags = 0 ) {
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list( $server, $conn ) = $this->getConnection( $key );
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if ( !$conn ) {
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return false;
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}
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$expiry = $this->convertToRelative( $expiry );
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try {
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if ( $expiry ) {
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$result = $conn->setex( $key, $expiry, $this->serialize( $value ) );
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} else {
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// No expiry, that is very different from zero expiry in Redis
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$result = $conn->set( $key, $this->serialize( $value ) );
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}
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} catch ( RedisException $e ) {
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$result = false;
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$this->handleException( $conn, $e );
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}
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$this->logRequest( 'set', $key, $server, $result );
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return $result;
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}
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public function delete( $key ) {
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list( $server, $conn ) = $this->getConnection( $key );
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if ( !$conn ) {
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return false;
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}
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try {
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$conn->delete( $key );
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// Return true even if the key didn't exist
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$result = true;
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} catch ( RedisException $e ) {
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$result = false;
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$this->handleException( $conn, $e );
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}
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$this->logRequest( 'delete', $key, $server, $result );
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return $result;
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}
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public function getMulti( array $keys, $flags = 0 ) {
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$batches = [];
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$conns = [];
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foreach ( $keys as $key ) {
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list( $server, $conn ) = $this->getConnection( $key );
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if ( !$conn ) {
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continue;
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}
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$conns[$server] = $conn;
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$batches[$server][] = $key;
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}
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$result = [];
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foreach ( $batches as $server => $batchKeys ) {
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$conn = $conns[$server];
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try {
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$conn->multi( Redis::PIPELINE );
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foreach ( $batchKeys as $key ) {
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$conn->get( $key );
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}
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$batchResult = $conn->exec();
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if ( $batchResult === false ) {
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$this->debug( "multi request to $server failed" );
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continue;
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}
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foreach ( $batchResult as $i => $value ) {
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if ( $value !== false ) {
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$result[$batchKeys[$i]] = $this->unserialize( $value );
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}
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}
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} catch ( RedisException $e ) {
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$this->handleException( $conn, $e );
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}
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}
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$this->debug( "getMulti for " . count( $keys ) . " keys " .
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"returned " . count( $result ) . " results" );
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return $result;
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}
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/**
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* @param array $data
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* @param int $expiry
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* @return bool
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*/
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public function setMulti( array $data, $expiry = 0 ) {
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$batches = [];
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$conns = [];
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foreach ( $data as $key => $value ) {
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list( $server, $conn ) = $this->getConnection( $key );
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if ( !$conn ) {
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continue;
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}
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$conns[$server] = $conn;
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$batches[$server][] = $key;
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}
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$expiry = $this->convertToRelative( $expiry );
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$result = true;
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foreach ( $batches as $server => $batchKeys ) {
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$conn = $conns[$server];
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try {
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$conn->multi( Redis::PIPELINE );
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foreach ( $batchKeys as $key ) {
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if ( $expiry ) {
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$conn->setex( $key, $expiry, $this->serialize( $data[$key] ) );
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} else {
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$conn->set( $key, $this->serialize( $data[$key] ) );
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}
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}
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$batchResult = $conn->exec();
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if ( $batchResult === false ) {
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$this->debug( "setMulti request to $server failed" );
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continue;
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}
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foreach ( $batchResult as $value ) {
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if ( $value === false ) {
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$result = false;
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}
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}
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} catch ( RedisException $e ) {
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$this->handleException( $conn, $e );
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$result = false;
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}
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}
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return $result;
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}
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public function add( $key, $value, $expiry = 0 ) {
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list( $server, $conn ) = $this->getConnection( $key );
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if ( !$conn ) {
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return false;
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}
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$expiry = $this->convertToRelative( $expiry );
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try {
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if ( $expiry ) {
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$result = $conn->set(
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$key,
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$this->serialize( $value ),
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[ 'nx', 'ex' => $expiry ]
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);
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} else {
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$result = $conn->setnx( $key, $this->serialize( $value ) );
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}
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} catch ( RedisException $e ) {
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$result = false;
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$this->handleException( $conn, $e );
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}
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$this->logRequest( 'add', $key, $server, $result );
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return $result;
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}
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public function merge( $key, callable $callback, $exptime = 0, $attempts = 10, $flags = 0 ) {
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return $this->mergeViaCas( $key, $callback, $exptime, $attempts );
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}
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/**
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* Non-atomic implementation of incr().
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*
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* Probably all callers actually want incr() to atomically initialise
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* values to zero if they don't exist, as provided by the Redis INCR
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* command. But we are constrained by the memcached-like interface to
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* return null in that case. Once the key exists, further increments are
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* atomic.
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* @param string $key Key to increase
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* @param int $value Value to add to $key (Default 1)
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* @return int|bool New value or false on failure
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*/
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public function incr( $key, $value = 1 ) {
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list( $server, $conn ) = $this->getConnection( $key );
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if ( !$conn ) {
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return false;
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}
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try {
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if ( !$conn->exists( $key ) ) {
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return false;
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}
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// @FIXME: on races, the key may have a 0 TTL
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$result = $conn->incrBy( $key, $value );
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} catch ( RedisException $e ) {
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$result = false;
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$this->handleException( $conn, $e );
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}
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$this->logRequest( 'incr', $key, $server, $result );
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return $result;
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}
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public function changeTTL( $key, $expiry = 0 ) {
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list( $server, $conn ) = $this->getConnection( $key );
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if ( !$conn ) {
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return false;
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}
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$expiry = $this->convertToRelative( $expiry );
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try {
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$result = $conn->expire( $key, $expiry );
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} catch ( RedisException $e ) {
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$result = false;
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$this->handleException( $conn, $e );
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}
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$this->logRequest( 'expire', $key, $server, $result );
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return $result;
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}
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public function modifySimpleRelayEvent( array $event ) {
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if ( array_key_exists( 'val', $event ) ) {
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$event['val'] = serialize( $event['val'] ); // this class uses PHP serialization
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}
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return $event;
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}
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/**
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* @param mixed $data
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* @return string
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*/
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protected function serialize( $data ) {
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// Serialize anything but integers so INCR/DECR work
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// Do not store integer-like strings as integers to avoid type confusion (T62563)
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return is_int( $data ) ? $data : serialize( $data );
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}
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/**
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* @param string $data
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* @return mixed
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*/
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protected function unserialize( $data ) {
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$int = intval( $data );
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return $data === (string)$int ? $int : unserialize( $data );
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}
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/**
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* Get a Redis object with a connection suitable for fetching the specified key
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* @param string $key
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* @return array (server, RedisConnRef) or (false, false)
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*/
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protected function getConnection( $key ) {
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$candidates = array_keys( $this->serverTagMap );
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if ( count( $this->servers ) > 1 ) {
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ArrayUtils::consistentHashSort( $candidates, $key, '/' );
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if ( !$this->automaticFailover ) {
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$candidates = array_slice( $candidates, 0, 1 );
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}
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}
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while ( ( $tag = array_shift( $candidates ) ) !== null ) {
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$server = $this->serverTagMap[$tag];
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$conn = $this->redisPool->getConnection( $server, $this->logger );
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if ( !$conn ) {
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continue;
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}
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// If automatic failover is enabled, check that the server's link
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// to its master (if any) is up -- but only if there are other
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// viable candidates left to consider. Also, getMasterLinkStatus()
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// does not work with twemproxy, though $candidates will be empty
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// by now in such cases.
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if ( $this->automaticFailover && $candidates ) {
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try {
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if ( $this->getMasterLinkStatus( $conn ) === 'down' ) {
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// If the master cannot be reached, fail-over to the next server.
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// If masters are in data-center A, and replica DBs in data-center B,
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// this helps avoid the case were fail-over happens in A but not
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// to the corresponding server in B (e.g. read/write mismatch).
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continue;
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}
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} catch ( RedisException $e ) {
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// Server is not accepting commands
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$this->handleException( $conn, $e );
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continue;
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}
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}
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return [ $server, $conn ];
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}
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$this->setLastError( BagOStuff::ERR_UNREACHABLE );
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return [ false, false ];
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}
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/**
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* Check the master link status of a Redis server that is configured as a replica DB.
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* @param RedisConnRef $conn
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* @return string|null Master link status (either 'up' or 'down'), or null
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* if the server is not a replica DB.
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*/
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protected function getMasterLinkStatus( RedisConnRef $conn ) {
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$info = $conn->info();
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return $info['master_link_status'] ?? null;
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}
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/**
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* Log a fatal error
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* @param string $msg
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*/
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protected function logError( $msg ) {
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$this->logger->error( "Redis error: $msg" );
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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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* @param RedisConnRef $conn
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* @param Exception $e
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*/
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protected function handleException( RedisConnRef $conn, $e ) {
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$this->setLastError( BagOStuff::ERR_UNEXPECTED );
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$this->redisPool->handleError( $conn, $e );
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}
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/**
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* Send information about a single request to the debug log
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* @param string $method
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* @param string $key
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* @param string $server
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* @param bool $result
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*/
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public function logRequest( $method, $key, $server, $result ) {
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$this->debug( "$method $key on $server: " .
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( $result === false ? "failure" : "success" ) );
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}
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}
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