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                 ksort( $options ); // normalize
 102                 $id = sha1( serialize( $options ) );
 103                 if ( !isset( self::$instances[$id] ) ) {
 104                         self::$instances[$id] = new self( $options );
 105                         wfDebug( "Creating a new " . __CLASS__ . " instance with id $id." );
 106                 }
 107                 return self::$instances[$id];
 108         }
 109
 110         /**
 111          * Get a connection to a redis server. Based on code in RedisBagOStuff.php.
 112          *
 113          * @param $server string A hostname/port combination or the absolute path of a UNIX socket.
 114          *                       If a hostname is specified but no port, port 6379 will be used.
 115          * @return RedisConnRef|bool Returns false on failure
 116          * @throws MWException
 117          */
 118         public function getConnection( $server ) {
 119                 // Check the listing "dead" servers which have had a connection errors.
 120                 // Servers are marked dead for a limited period of time, to
 121                 // avoid excessive overhead from repeated connection timeouts.
 122                 if ( isset( $this->downServers[$server] ) ) {
 123                         $now = time();
 124                         if ( $now > $this->downServers[$server] ) {
 125                                 // Dead time expired
 126                                 unset( $this->downServers[$server] );
 127                         } else {
 128                                 // Server is dead
 129                                 wfDebug( "server $server is marked down for another " .
 130                                         ( $this->downServers[$server] - $now ) . " seconds, can't get connection" );
 131                                 return false;
 132                         }
 133                 }
 134
 135                 // Check if a connection is already free for use
 136                 if ( isset( $this->connections[$server] ) ) {
 137                         foreach ( $this->connections[$server] as &$connection ) {
 138                                 if ( $connection['free'] ) {
 139                                         $connection['free'] = false;
 140                                         --$this->idlePoolSize;
 141                                         return new RedisConnRef( $this, $server, $connection['conn'] );
 142                                 }
 143                         }
 144                 }
 145
 146                 if ( substr( $server, 0, 1 ) === '/' ) {
 147                         // UNIX domain socket
 148                         // These are required by the redis extension to start with a slash, but
 149                         // we still need to set the port to a special value to make it work.
 150                         $host = $server;
 151                         $port = 0;
 152                 } else {
 153                         // TCP connection
 154                         $hostPort = IP::splitHostAndPort( $server );
 155                         if ( !$hostPort ) {
 156                                 throw new MWException( __CLASS__.": invalid configured server \"$server\"" );
 157                         }
 158                         list( $host, $port ) = $hostPort;
 159                         if ( $port === false ) {
 160                                 $port = 6379;
 161                         }
 162                 }
 163
 164                 $conn = new Redis();
 165                 try {
 166                         if ( $this->persistent ) {
 167                                 $result = $conn->pconnect( $host, $port, $this->connectTimeout );
 168                         } else {
 169                                 $result = $conn->connect( $host, $port, $this->connectTimeout );
 170                         }
 171                         if ( !$result ) {
 172                                 wfDebugLog( 'redis', "Could not connect to server $server" );
 173                                 // Mark server down for some time to avoid further timeouts
 174                                 $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 175                                 return false;
 176                         }
 177                         if ( $this->password !== null ) {
 178                                 if ( !$conn->auth( $this->password ) ) {
 179                                         wfDebugLog( 'redis', "Authentication error connecting to $server" );
 180                                 }
 181                         }
 182                 } catch ( RedisException $e ) {
 183                         $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 184                         wfDebugLog( 'redis', "Redis exception: " . $e->getMessage() . "\n" );
 185                         return false;
 186                 }
 187
 188                 if ( $conn ) {
 189                         $conn->setOption( Redis::OPT_SERIALIZER, $this->serializer );
 190                         $this->connections[$server][] = array( 'conn' => $conn, 'free' => false );
 191                         return new RedisConnRef( $this, $server, $conn );
 192                 } else {
 193                         return false;
 194                 }
 195         }
 196
 197         /**
 198          * Mark a connection to a server as free to return to the pool
 199          *
 200          * @param $server string
 201          * @param $conn Redis
 202          * @return boolean
 203          */
 204         public function freeConnection( $server, Redis $conn ) {
 205                 $found = false;
 206
 207                 foreach ( $this->connections[$server] as &$connection ) {
 208                         if ( $connection['conn'] === $conn && !$connection['free'] ) {
 209                                 $connection['free'] = true;
 210                                 ++$this->idlePoolSize;
 211                                 break;
 212                         }
 213                 }
 214
 215                 $this->closeExcessIdleConections();
 216
 217                 return $found;
 218         }
 219
 220         /**
 221          * Close any extra idle connections if there are more than the limit
 222          *
 223          * @return void
 224          */
 225         protected function closeExcessIdleConections() {
 226                 if ( $this->idlePoolSize <= $this->poolSize ) {
 227                         return; // nothing to do
 228                 }
 229
 230                 foreach ( $this->connections as $server => &$serverConnections ) {
 231                         foreach ( $serverConnections as $key => &$connection ) {
 232                                 if ( $connection['free'] ) {
 233                                         unset( $serverConnections[$key] );
 234                                         if ( --$this->idlePoolSize <= $this->poolSize ) {
 235                                                 return; // done
 236                                         }
 237                                 }
 238                         }
 239                 }
 240         }
 241
 242         /**
 243          * The redis extension throws an exception in response to various read, write
 244          * and protocol errors. Sometimes it also closes the connection, sometimes
 245          * not. The safest response for us is to explicitly destroy the connection
 246          * object and let it be reopened during the next request.
 247          *
 248          * @param $server string
 249          * @param $conn RedisConnRef
 250          * @param $e RedisException
 251          * @return void
 252          */
 253         public function handleException( $server, RedisConnRef $conn, RedisException $e ) {
 254                 wfDebugLog( 'redis',
 255                         "Redis exception on server $server: " . $e->getMessage() . "\n" );
 256                 foreach ( $this->connections[$server] as $key => $connection ) {
 257                         if ( $connection['conn'] === $conn ) {
 258                                 $this->idlePoolSize -= $connection['free'] ? 1 : 0;
 259                                 unset( $this->connections[$server][$key] );
 260                                 break;
 261                         }
 262                 }
 263         }
 264 }
 265
 266 /**
 267  * Helper class to handle automatically marking connectons as reusable (via RAII pattern)
 268  *
 269  * @ingroup Redis
 270  * @since 1.21
 271  */
 272 class RedisConnRef {
 273         /** @var RedisConnectionPool */
 274         protected $pool;
 275
 276         protected $server; // string
 277
 278         /** @var Redis */
 279         protected $conn;
 280
 281         /**
 282          * @param $pool RedisConnectionPool
 283          * @param $server string
 284          * @param $conn Redis
 285          */
 286         public function __construct( RedisConnectionPool $pool, $server, Redis $conn ) {
 287                 $this->pool = $pool;
 288                 $this->server = $server;
 289                 $this->conn = $conn;
 290         }
 291
 292         public function __call( $name, $arguments ) {
 293                 return call_user_func_array( array( $this->conn, $name ), $arguments );
 294         }
 295
 296         function __destruct() {
 297                 $this->pool->freeConnection( $this->server, $this->conn );
 298         }
 299 }