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 $serializer; // integer; the serializer to use (Redis::SERIALIZER_*)
  44
  45         protected $idlePoolSize = 0; // integer; current idle pool size
  46
  47         /** @var Array (server name => ((connection info array),...) */
  48         protected $connections = array();
  49         /** @var Array (server name => UNIX timestamp) */
  50         protected $downServers = array();
  51
  52         /** @var Array */
  53         protected static $instances = array(); // (pool ID => RedisConnectionPool)
  54
  55         const SERVER_DOWN_TTL = 30; // integer; seconds to cache servers as "down"
  56
  57         /**
  58          * @param array $options
  59          */
  60         protected function __construct( array $options ) {
  61                 if ( !extension_loaded( 'redis' ) ) {
  62                         throw new MWException( __CLASS__. ' requires the phpredis extension: ' .
  63                                 'https://github.com/nicolasff/phpredis' );
  64                 }
  65                 $this->connectTimeout = $options['connectTimeout'];
  66                 $this->persistent = $options['persistent'];
  67                 $this->password = $options['password'];
  68                 if ( !isset( $options['serializer'] ) || $options['serializer'] === 'php' ) {
  69                         $this->serializer = Redis::SERIALIZER_PHP;
  70                 } elseif ( $options['serializer'] === 'igbinary' ) {
  71                         $this->serializer = Redis::SERIALIZER_IGBINARY;
  72                 } elseif ( $options['serializer'] === 'none' ) {
  73                         $this->serializer = Redis::SERIALIZER_NONE;
  74                 } else {
  75                         throw new MWException( "Invalid serializer specified." );
  76                 }
  77         }
  78
  79         /**
  80          * @param $options Array
  81          * @return Array
  82          */
  83         protected static function applyDefaultConfig( array $options ) {
  84                 if ( !isset( $options['connectTimeout'] ) ) {
  85                         $options['connectTimeout'] = 1;
  86                 }
  87                 if ( !isset( $options['persistent'] ) ) {
  88                         $options['persistent'] = false;
  89                 }
  90                 if ( !isset( $options['password'] ) ) {
  91                         $options['password'] = null;
  92                 }
  93                 return $options;
  94         }
  95
  96         /**
  97          * @param $options Array
  98          * $options include:
  99          *   - connectTimeout : The timeout for new connections, in seconds.
 100          *                      Optional, default is 1 second.
 101          *   - persistent     : Set this to true to allow connections to persist across
 102          *                      multiple web requests. False by default.
 103          *   - password       : The authentication password, will be sent to Redis in clear text.
 104          *                      Optional, if it is unspecified, no AUTH command will be sent.
 105          *   - serializer     : Set to "php", "igbinary", or "none". Default is "php".
 106          * @return RedisConnectionPool
 107          */
 108         public static function singleton( array $options ) {
 109                 $options = self::applyDefaultConfig( $options );
 110                 // Map the options to a unique hash...
 111                 ksort( $options ); // normalize to avoid pool fragmentation
 112                 $id = sha1( serialize( $options ) );
 113                 // Initialize the object at the hash as needed...
 114                 if ( !isset( self::$instances[$id] ) ) {
 115                         self::$instances[$id] = new self( $options );
 116                         wfDebug( "Creating a new " . __CLASS__ . " instance with id $id." );
 117                 }
 118                 return self::$instances[$id];
 119         }
 120
 121         /**
 122          * Get a connection to a redis server. Based on code in RedisBagOStuff.php.
 123          *
 124          * @param string $server A hostname/port combination or the absolute path of a UNIX socket.
 125          *                       If a hostname is specified but no port, port 6379 will be used.
 126          * @return RedisConnRef|bool Returns false on failure
 127          * @throws MWException
 128          */
 129         public function getConnection( $server ) {
 130                 // Check the listing "dead" servers which have had a connection errors.
 131                 // Servers are marked dead for a limited period of time, to
 132                 // avoid excessive overhead from repeated connection timeouts.
 133                 if ( isset( $this->downServers[$server] ) ) {
 134                         $now = time();
 135                         if ( $now > $this->downServers[$server] ) {
 136                                 // Dead time expired
 137                                 unset( $this->downServers[$server] );
 138                         } else {
 139                                 // Server is dead
 140                                 wfDebug( "server $server is marked down for another " .
 141                                         ( $this->downServers[$server] - $now ) . " seconds, can't get connection" );
 142                                 return false;
 143                         }
 144                 }
 145
 146                 // Check if a connection is already free for use
 147                 if ( isset( $this->connections[$server] ) ) {
 148                         foreach ( $this->connections[$server] as &$connection ) {
 149                                 if ( $connection['free'] ) {
 150                                         $connection['free'] = false;
 151                                         --$this->idlePoolSize;
 152                                         return new RedisConnRef( $this, $server, $connection['conn'] );
 153                                 }
 154                         }
 155                 }
 156
 157                 if ( substr( $server, 0, 1 ) === '/' ) {
 158                         // UNIX domain socket
 159                         // These are required by the redis extension to start with a slash, but
 160                         // we still need to set the port to a special value to make it work.
 161                         $host = $server;
 162                         $port = 0;
 163                 } else {
 164                         // TCP connection
 165                         $hostPort = IP::splitHostAndPort( $server );
 166                         if ( !$hostPort ) {
 167                                 throw new MWException( __CLASS__.": invalid configured server \"$server\"" );
 168                         }
 169                         list( $host, $port ) = $hostPort;
 170                         if ( $port === false ) {
 171                                 $port = 6379;
 172                         }
 173                 }
 174
 175                 $conn = new Redis();
 176                 try {
 177                         if ( $this->persistent ) {
 178                                 $result = $conn->pconnect( $host, $port, $this->connectTimeout );
 179                         } else {
 180                                 $result = $conn->connect( $host, $port, $this->connectTimeout );
 181                         }
 182                         if ( !$result ) {
 183                                 wfDebugLog( 'redis', "Could not connect to server $server" );
 184                                 // Mark server down for some time to avoid further timeouts
 185                                 $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 186                                 return false;
 187                         }
 188                         if ( $this->password !== null ) {
 189                                 if ( !$conn->auth( $this->password ) ) {
 190                                         wfDebugLog( 'redis', "Authentication error connecting to $server" );
 191                                 }
 192                         }
 193                 } catch ( RedisException $e ) {
 194                         $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 195                         wfDebugLog( 'redis', "Redis exception: " . $e->getMessage() . "\n" );
 196                         return false;
 197                 }
 198
 199                 if ( $conn ) {
 200                         $conn->setOption( Redis::OPT_SERIALIZER, $this->serializer );
 201                         $this->connections[$server][] = array( 'conn' => $conn, 'free' => false );
 202                         return new RedisConnRef( $this, $server, $conn );
 203                 } else {
 204                         return false;
 205                 }
 206         }
 207
 208         /**
 209          * Mark a connection to a server as free to return to the pool
 210          *
 211          * @param $server string
 212          * @param $conn Redis
 213          * @return boolean
 214          */
 215         public function freeConnection( $server, Redis $conn ) {
 216                 $found = false;
 217
 218                 foreach ( $this->connections[$server] as &$connection ) {
 219                         if ( $connection['conn'] === $conn && !$connection['free'] ) {
 220                                 $connection['free'] = true;
 221                                 ++$this->idlePoolSize;
 222                                 break;
 223                         }
 224                 }
 225
 226                 $this->closeExcessIdleConections();
 227
 228                 return $found;
 229         }
 230
 231         /**
 232          * Close any extra idle connections if there are more than the limit
 233          *
 234          * @return void
 235          */
 236         protected function closeExcessIdleConections() {
 237                 if ( $this->idlePoolSize <= count( $this->connections ) ) {
 238                         return; // nothing to do (no more connections than servers)
 239                 }
 240
 241                 foreach ( $this->connections as $server => &$serverConnections ) {
 242                         foreach ( $serverConnections as $key => &$connection ) {
 243                                 if ( $connection['free'] ) {
 244                                         unset( $serverConnections[$key] );
 245                                         if ( --$this->idlePoolSize <= count( $this->connections ) ) {
 246                                                 return; // done (no more connections than servers)
 247                                         }
 248                                 }
 249                         }
 250                 }
 251         }
 252
 253         /**
 254          * The redis extension throws an exception in response to various read, write
 255          * and protocol errors. Sometimes it also closes the connection, sometimes
 256          * not. The safest response for us is to explicitly destroy the connection
 257          * object and let it be reopened during the next request.
 258          *
 259          * @param $server string
 260          * @param $cref RedisConnRef
 261          * @param $e RedisException
 262          * @return void
 263          */
 264         public function handleException( $server, RedisConnRef $cref, RedisException $e ) {
 265                 wfDebugLog( 'redis', "Redis exception on server $server: " . $e->getMessage() . "\n" );
 266                 foreach ( $this->connections[$server] as $key => $connection ) {
 267                         if ( $cref->isConnIdentical( $connection['conn'] ) ) {
 268                                 $this->idlePoolSize -= $connection['free'] ? 1 : 0;
 269                                 unset( $this->connections[$server][$key] );
 270                                 break;
 271                         }
 272                 }
 273         }
 274 }
 275
 276 /**
 277  * Helper class to handle automatically marking connectons as reusable (via RAII pattern)
 278  *
 279  * @ingroup Redis
 280  * @since 1.21
 281  */
 282 class RedisConnRef {
 283         /** @var RedisConnectionPool */
 284         protected $pool;
 285         /** @var Redis */
 286         protected $conn;
 287
 288         protected $server; // string
 289
 290         /**
 291          * @param $pool RedisConnectionPool
 292          * @param $server string
 293          * @param $conn Redis
 294          */
 295         public function __construct( RedisConnectionPool $pool, $server, Redis $conn ) {
 296                 $this->pool = $pool;
 297                 $this->server = $server;
 298                 $this->conn = $conn;
 299         }
 300
 301         public function __call( $name, $arguments ) {
 302                 return call_user_func_array( array( $this->conn, $name ), $arguments );
 303         }
 304
 305         public function isConnIdentical( Redis $conn ) {
 306                 return $this->conn === $conn;
 307         }
 308
 309         function __destruct() {
 310                 $this->pool->freeConnection( $this->server, $this->conn );
 311         }
 312 }