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