includes/clientpool/RedisConnectionPool.php

   1 <?php
   2 /**
   3  * PhpRedis client connection pooling manager.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @defgroup Redis Redis
  22  * @author Aaron Schulz
  23  */
  24
  25 /**
  26  * Helper class to manage redis connections using PhpRedis.
  27  *
  28  * This can be used to get handle wrappers that free the handle when the wrapper
  29  * leaves scope. The maximum number of free handles (connections) is configurable.
  30  * This provides an easy way to cache connection handles that may also have state,
  31  * such as a handle does between multi() and exec(), and without hoarding connections.
  32  * The wrappers use PHP magic methods so that calling functions on them calls the
  33  * function of the actual Redis object handle.
  34  *
  35  * @ingroup Redis
  36  * @since 1.21
  37  */
  38 class RedisConnectionPool {
  39         // Settings for all connections in this pool
  40         protected $connectTimeout; // string; connection timeout
  41         protected $persistent; // bool; whether connections persist
  42         protected $password; // string; plaintext auth password
  43         protected $poolSize; // integer; maximum number of idle connections
  44         protected $serializer; // integer; the serializer to use (Redis::SERIALIZER_*)
  45
  46         protected $idlePoolSize = 0; // integer; current idle pool size
  47
  48         /** @var Array (server name => ((connection info array),...) */
  49         protected $connections = array();
  50         /** @var Array (server name => UNIX timestamp) */
  51         protected $downServers = array();
  52
  53         /** @var Array */
  54         protected static $instances = array(); // (pool ID => RedisConnectionPool)
  55
  56         const SERVER_DOWN_TTL = 30; // integer; seconds to cache servers as "down"
  57
  58         /**
  59          * $options include:
  60          *   - connectTimeout : The timeout for new connections, in seconds.
  61          *                      Optional, default is 1 second.
  62          *   - persistent     : Set this to true to allow connections to persist across
  63          *                      multiple web requests. False by default.
  64          *   - poolSize       : Maximim number of idle connections. Default is 5.
  65          *   - password       : The authentication password, will be sent to Redis in clear text.
  66          *                      Optional, if it is unspecified, no AUTH command will be sent.
  67          *   - serializer     : Set to "php" or "igbinary". Default is "php".
  68          * @param array $options
  69          */
  70         protected function __construct( array $options ) {
  71                 if ( !extension_loaded( 'redis' ) ) {
  72                         throw new MWException( __CLASS__. ' requires the phpredis extension: ' .
  73                                 'https://github.com/nicolasff/phpredis' );
  74                 }
  75                 $this->connectTimeout = isset( $options['connectTimeout'] )
  76                         ? $options['connectTimeout']
  77                         : 1;
  78                 $this->persistent = isset( $options['persistent'] )
  79                         ? $options['persistent']
  80                         : false;
  81                 $this->password = isset( $options['password'] )
  82                         ? $options['password']
  83                         : '';
  84                 $this->poolSize = isset( $options['poolSize'] )
  85                         ? $options['poolSize']
  86                         : 5;
  87                 if ( !isset( $options['serializer'] ) || $options['serializer'] === 'php' ) {
  88                         $this->serializer = Redis::SERIALIZER_PHP;
  89                 } elseif ( $options['serializer'] === 'igbinary' ) {
  90                         $this->serializer = Redis::SERIALIZER_IGBINARY;
  91                 } else {
  92                         throw new MWException( "Invalid serializer specified." );
  93                 }
  94         }
  95
  96         /**
  97          * @param $options Array
  98          * @return RedisConnectionPool
  99          */
 100         public static function singleton( array $options ) {
 101                 // Map the options to a unique hash...
 102                 $poolOptions = $options;
 103                 unset( $poolOptions['poolSize'] ); // avoid pool fragmentation
 104                 ksort( $poolOptions ); // normalize to avoid pool fragmentation
 105                 $id = sha1( serialize( $poolOptions ) );
 106                 // Initialize the object at the hash as needed...
 107                 if ( !isset( self::$instances[$id] ) ) {
 108                         self::$instances[$id] = new self( $options );
 109                         wfDebug( "Creating a new " . __CLASS__ . " instance with id $id." );
 110                 }
 111                 // Simply grow the pool size if the existing one is too small
 112                 $psize = isset( $options['poolSize'] ) ? $options['poolSize'] : 1; // size requested
 113                 self::$instances[$id]->poolSize = max( $psize, self::$instances[$id]->poolSize );
 114
 115                 return self::$instances[$id];
 116         }
 117
 118         /**
 119          * Get a connection to a redis server. Based on code in RedisBagOStuff.php.
 120          *
 121          * @param $server string A hostname/port combination or the absolute path of a UNIX socket.
 122          *                       If a hostname is specified but no port, port 6379 will be used.
 123          * @return RedisConnRef|bool Returns false on failure
 124          * @throws MWException
 125          */
 126         public function getConnection( $server ) {
 127                 // Check the listing "dead" servers which have had a connection errors.
 128                 // Servers are marked dead for a limited period of time, to
 129                 // avoid excessive overhead from repeated connection timeouts.
 130                 if ( isset( $this->downServers[$server] ) ) {
 131                         $now = time();
 132                         if ( $now > $this->downServers[$server] ) {
 133                                 // Dead time expired
 134                                 unset( $this->downServers[$server] );
 135                         } else {
 136                                 // Server is dead
 137                                 wfDebug( "server $server is marked down for another " .
 138                                         ( $this->downServers[$server] - $now ) . " seconds, can't get connection" );
 139                                 return false;
 140                         }
 141                 }
 142
 143                 // Check if a connection is already free for use
 144                 if ( isset( $this->connections[$server] ) ) {
 145                         foreach ( $this->connections[$server] as &$connection ) {
 146                                 if ( $connection['free'] ) {
 147                                         $connection['free'] = false;
 148                                         --$this->idlePoolSize;
 149                                         return new RedisConnRef( $this, $server, $connection['conn'] );
 150                                 }
 151                         }
 152                 }
 153
 154                 if ( substr( $server, 0, 1 ) === '/' ) {
 155                         // UNIX domain socket
 156                         // These are required by the redis extension to start with a slash, but
 157                         // we still need to set the port to a special value to make it work.
 158                         $host = $server;
 159                         $port = 0;
 160                 } else {
 161                         // TCP connection
 162                         $hostPort = IP::splitHostAndPort( $server );
 163                         if ( !$hostPort ) {
 164                                 throw new MWException( __CLASS__.": invalid configured server \"$server\"" );
 165                         }
 166                         list( $host, $port ) = $hostPort;
 167                         if ( $port === false ) {
 168                                 $port = 6379;
 169                         }
 170                 }
 171
 172                 $conn = new Redis();
 173                 try {
 174                         if ( $this->persistent ) {
 175                                 $result = $conn->pconnect( $host, $port, $this->connectTimeout );
 176                         } else {
 177                                 $result = $conn->connect( $host, $port, $this->connectTimeout );
 178                         }
 179                         if ( !$result ) {
 180                                 wfDebugLog( 'redis', "Could not connect to server $server" );
 181                                 // Mark server down for some time to avoid further timeouts
 182                                 $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 183                                 return false;
 184                         }
 185                         if ( $this->password !== null ) {
 186                                 if ( !$conn->auth( $this->password ) ) {
 187                                         wfDebugLog( 'redis', "Authentication error connecting to $server" );
 188                                 }
 189                         }
 190                 } catch ( RedisException $e ) {
 191                         $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 192                         wfDebugLog( 'redis', "Redis exception: " . $e->getMessage() . "\n" );
 193                         return false;
 194                 }
 195
 196                 if ( $conn ) {
 197                         $conn->setOption( Redis::OPT_SERIALIZER, $this->serializer );
 198                         $this->connections[$server][] = array( 'conn' => $conn, 'free' => false );
 199                         return new RedisConnRef( $this, $server, $conn );
 200                 } else {
 201                         return false;
 202                 }
 203         }
 204
 205         /**
 206          * Mark a connection to a server as free to return to the pool
 207          *
 208          * @param $server string
 209          * @param $conn Redis
 210          * @return boolean
 211          */
 212         public function freeConnection( $server, Redis $conn ) {
 213                 $found = false;
 214
 215                 foreach ( $this->connections[$server] as &$connection ) {
 216                         if ( $connection['conn'] === $conn && !$connection['free'] ) {
 217                                 $connection['free'] = true;
 218                                 ++$this->idlePoolSize;
 219                                 break;
 220                         }
 221                 }
 222
 223                 $this->closeExcessIdleConections();
 224
 225                 return $found;
 226         }
 227
 228         /**
 229          * Close any extra idle connections if there are more than the limit
 230          *
 231          * @return void
 232          */
 233         protected function closeExcessIdleConections() {
 234                 if ( $this->idlePoolSize <= $this->poolSize ) {
 235                         return; // nothing to do
 236                 }
 237
 238                 foreach ( $this->connections as $server => &$serverConnections ) {
 239                         foreach ( $serverConnections as $key => &$connection ) {
 240                                 if ( $connection['free'] ) {
 241                                         unset( $serverConnections[$key] );
 242                                         if ( --$this->idlePoolSize <= $this->poolSize ) {
 243                                                 return; // done
 244                                         }
 245                                 }
 246                         }
 247                 }
 248         }
 249
 250         /**
 251          * The redis extension throws an exception in response to various read, write
 252          * and protocol errors. Sometimes it also closes the connection, sometimes
 253          * not. The safest response for us is to explicitly destroy the connection
 254          * object and let it be reopened during the next request.
 255          *
 256          * @param $server string
 257          * @param $conn RedisConnRef
 258          * @param $e RedisException
 259          * @return void
 260          */
 261         public function handleException( $server, RedisConnRef $conn, RedisException $e ) {
 262                 wfDebugLog( 'redis',
 263                         "Redis exception on server $server: " . $e->getMessage() . "\n" );
 264                 foreach ( $this->connections[$server] as $key => $connection ) {
 265                         if ( $connection['conn'] === $conn ) {
 266                                 $this->idlePoolSize -= $connection['free'] ? 1 : 0;
 267                                 unset( $this->connections[$server][$key] );
 268                                 break;
 269                         }
 270                 }
 271         }
 272 }
 273
 274 /**
 275  * Helper class to handle automatically marking connectons as reusable (via RAII pattern)
 276  *
 277  * @ingroup Redis
 278  * @since 1.21
 279  */
 280 class RedisConnRef {
 281         /** @var RedisConnectionPool */
 282         protected $pool;
 283
 284         protected $server; // string
 285
 286         /** @var Redis */
 287         protected $conn;
 288
 289         /**
 290          * @param $pool RedisConnectionPool
 291          * @param $server string
 292          * @param $conn Redis
 293          */
 294         public function __construct( RedisConnectionPool $pool, $server, Redis $conn ) {
 295                 $this->pool = $pool;
 296                 $this->server = $server;
 297                 $this->conn = $conn;
 298         }
 299
 300         public function __call( $name, $arguments ) {
 301                 return call_user_func_array( array( $this->conn, $name ), $arguments );
 302         }
 303
 304         function __destruct() {
 305                 $this->pool->freeConnection( $this->server, $this->conn );
 306         }
 307 }