Current File : /www/varak.net/wiki.varak.net/includes/objectcache/RedisBagOStuff.php
<?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 (bug 60563)
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( $server );
if ( !$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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