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 = $options['connectTimeout'];
  76                 $this->persistent = $options['persistent'];
  77                 $this->password = $options['password'];
  78                 $this->poolSize = $options['poolSize'];
  79                 if ( !isset( $options['serializer'] ) || $options['serializer'] === 'php' ) {
  80                         $this->serializer = Redis::SERIALIZER_PHP;
  81                 } elseif ( $options['serializer'] === 'igbinary' ) {
  82                         $this->serializer = Redis::SERIALIZER_IGBINARY;
  83                 } else {
  84                         throw new MWException( "Invalid serializer specified." );
  85                 }
  86         }
  87
  88         /**
  89          * @param $options Array
  90          * @return Array
  91          */
  92         protected static function applyDefaultConfig( array $options ) {
  93                 if ( !isset( $options['connectTimeout'] ) ) {
  94                         $options['connectTimeout'] = 1;
  95                 }
  96                 if ( !isset( $options['persistent'] ) ) {
  97                         $options['persistent'] = false;
  98                 }
  99                 if ( !isset( $options['password'] ) ) {
 100                         $options['password'] = '';
 101                 }
 102                 if ( !isset( $options['poolSize'] ) ) {
 103                         $options['poolSize'] = 1;
 104                 }
 105                 return $options;
 106         }
 107
 108         /**
 109          * @param $options Array
 110          * @return RedisConnectionPool
 111          */
 112         public static function singleton( array $options ) {
 113                 $options = self::applyDefaultConfig( $options );
 114                 // Map the options to a unique hash...
 115                 $poolOptions = $options;
 116                 unset( $poolOptions['poolSize'] ); // avoid pool fragmentation
 117                 ksort( $poolOptions ); // normalize to avoid pool fragmentation
 118                 $id = sha1( serialize( $poolOptions ) );
 119                 // Initialize the object at the hash as needed...
 120                 if ( !isset( self::$instances[$id] ) ) {
 121                         self::$instances[$id] = new self( $options );
 122                         wfDebug( "Creating a new " . __CLASS__ . " instance with id $id." );
 123                 }
 124                 // Simply grow the pool size if the existing one is too small
 125                 $psize = $options['poolSize']; // size requested
 126                 self::$instances[$id]->poolSize = max( $psize, self::$instances[$id]->poolSize );
 127
 128                 return self::$instances[$id];
 129         }
 130
 131         /**
 132          * Get a connection to a redis server. Based on code in RedisBagOStuff.php.
 133          *
 134          * @param $server string A hostname/port combination or the absolute path of a UNIX socket.
 135          *                       If a hostname is specified but no port, port 6379 will be used.
 136          * @return RedisConnRef|bool Returns false on failure
 137          * @throws MWException
 138          */
 139         public function getConnection( $server ) {
 140                 // Check the listing "dead" servers which have had a connection errors.
 141                 // Servers are marked dead for a limited period of time, to
 142                 // avoid excessive overhead from repeated connection timeouts.
 143                 if ( isset( $this->downServers[$server] ) ) {
 144                         $now = time();
 145                         if ( $now > $this->downServers[$server] ) {
 146                                 // Dead time expired
 147                                 unset( $this->downServers[$server] );
 148                         } else {
 149                                 // Server is dead
 150                                 wfDebug( "server $server is marked down for another " .
 151                                         ( $this->downServers[$server] - $now ) . " seconds, can't get connection" );
 152                                 return false;
 153                         }
 154                 }
 155
 156                 // Check if a connection is already free for use
 157                 if ( isset( $this->connections[$server] ) ) {
 158                         foreach ( $this->connections[$server] as &$connection ) {
 159                                 if ( $connection['free'] ) {
 160                                         $connection['free'] = false;
 161                                         --$this->idlePoolSize;
 162                                         return new RedisConnRef( $this, $server, $connection['conn'] );
 163                                 }
 164                         }
 165                 }
 166
 167                 if ( substr( $server, 0, 1 ) === '/' ) {
 168                         // UNIX domain socket
 169                         // These are required by the redis extension to start with a slash, but
 170                         // we still need to set the port to a special value to make it work.
 171                         $host = $server;
 172                         $port = 0;
 173                 } else {
 174                         // TCP connection
 175                         $hostPort = IP::splitHostAndPort( $server );
 176                         if ( !$hostPort ) {
 177                                 throw new MWException( __CLASS__.": invalid configured server \"$server\"" );
 178                         }
 179                         list( $host, $port ) = $hostPort;
 180                         if ( $port === false ) {
 181                                 $port = 6379;
 182                         }
 183                 }
 184
 185                 $conn = new Redis();
 186                 try {
 187                         if ( $this->persistent ) {
 188                                 $result = $conn->pconnect( $host, $port, $this->connectTimeout );
 189                         } else {
 190                                 $result = $conn->connect( $host, $port, $this->connectTimeout );
 191                         }
 192                         if ( !$result ) {
 193                                 wfDebugLog( 'redis', "Could not connect to server $server" );
 194                                 // Mark server down for some time to avoid further timeouts
 195                                 $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 196                                 return false;
 197                         }
 198                         if ( $this->password !== null ) {
 199                                 if ( !$conn->auth( $this->password ) ) {
 200                                         wfDebugLog( 'redis', "Authentication error connecting to $server" );
 201                                 }
 202                         }
 203                 } catch ( RedisException $e ) {
 204                         $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 205                         wfDebugLog( 'redis', "Redis exception: " . $e->getMessage() . "\n" );
 206                         return false;
 207                 }
 208
 209                 if ( $conn ) {
 210                         $conn->setOption( Redis::OPT_SERIALIZER, $this->serializer );
 211                         $this->connections[$server][] = array( 'conn' => $conn, 'free' => false );
 212                         return new RedisConnRef( $this, $server, $conn );
 213                 } else {
 214                         return false;
 215                 }
 216         }
 217
 218         /**
 219          * Mark a connection to a server as free to return to the pool
 220          *
 221          * @param $server string
 222          * @param $conn Redis
 223          * @return boolean
 224          */
 225         public function freeConnection( $server, Redis $conn ) {
 226                 $found = false;
 227
 228                 foreach ( $this->connections[$server] as &$connection ) {
 229                         if ( $connection['conn'] === $conn && !$connection['free'] ) {
 230                                 $connection['free'] = true;
 231                                 ++$this->idlePoolSize;
 232                                 break;
 233                         }
 234                 }
 235
 236                 $this->closeExcessIdleConections();
 237
 238                 return $found;
 239         }
 240
 241         /**
 242          * Close any extra idle connections if there are more than the limit
 243          *
 244          * @return void
 245          */
 246         protected function closeExcessIdleConections() {
 247                 if ( $this->idlePoolSize <= $this->poolSize ) {
 248                         return; // nothing to do
 249                 }
 250
 251                 foreach ( $this->connections as $server => &$serverConnections ) {
 252                         foreach ( $serverConnections as $key => &$connection ) {
 253                                 if ( $connection['free'] ) {
 254                                         unset( $serverConnections[$key] );
 255                                         if ( --$this->idlePoolSize <= $this->poolSize ) {
 256                                                 return; // done
 257                                         }
 258                                 }
 259                         }
 260                 }
 261         }
 262
 263         /**
 264          * The redis extension throws an exception in response to various read, write
 265          * and protocol errors. Sometimes it also closes the connection, sometimes
 266          * not. The safest response for us is to explicitly destroy the connection
 267          * object and let it be reopened during the next request.
 268          *
 269          * @param $server string
 270          * @param $conn RedisConnRef
 271          * @param $e RedisException
 272          * @return void
 273          */
 274         public function handleException( $server, RedisConnRef $conn, RedisException $e ) {
 275                 wfDebugLog( 'redis',
 276                         "Redis exception on server $server: " . $e->getMessage() . "\n" );
 277                 foreach ( $this->connections[$server] as $key => $connection ) {
 278                         if ( $connection['conn'] === $conn ) {
 279                                 $this->idlePoolSize -= $connection['free'] ? 1 : 0;
 280                                 unset( $this->connections[$server][$key] );
 281                                 break;
 282                         }
 283                 }
 284         }
 285 }
 286
 287 /**
 288  * Helper class to handle automatically marking connectons as reusable (via RAII pattern)
 289  *
 290  * @ingroup Redis
 291  * @since 1.21
 292  */
 293 class RedisConnRef {
 294         /** @var RedisConnectionPool */
 295         protected $pool;
 296
 297         protected $server; // string
 298
 299         /** @var Redis */
 300         protected $conn;
 301
 302         /**
 303          * @param $pool RedisConnectionPool
 304          * @param $server string
 305          * @param $conn Redis
 306          */
 307         public function __construct( RedisConnectionPool $pool, $server, Redis $conn ) {
 308                 $this->pool = $pool;
 309                 $this->server = $server;
 310                 $this->conn = $conn;
 311         }
 312
 313         public function __call( $name, $arguments ) {
 314                 return call_user_func_array( array( $this->conn, $name ), $arguments );
 315         }
 316
 317         function __destruct() {
 318                 $this->pool->freeConnection( $this->server, $this->conn );
 319         }
 320 }