includes/clientpool/RedisConnectionPool.php

   1 <?php
   2 /**
   3  * Redis 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.
  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         /**
  40          * @name Pool settings.
  41          * Settings there are shared for any connection made in this pool.
  42          * See the singleton() method documentation for more details.
  43          * @{
  44          */
  45         /** @var string Connection timeout in seconds */
  46         protected $connectTimeout;
  47         /** @var string Plaintext auth password */
  48         protected $password;
  49         /** @var bool Whether connections persist */
  50         protected $persistent;
  51         /** @var integer Serializer to use (Redis::SERIALIZER_*) */
  52         protected $serializer;
  53         /** @} */
  54
  55         /** @var integer Current idle pool size */
  56         protected $idlePoolSize = 0;
  57
  58         /** @var Array (server name => ((connection info array),...) */
  59         protected $connections = array();
  60         /** @var Array (server name => UNIX timestamp) */
  61         protected $downServers = array();
  62
  63         /** @var Array (pool ID => RedisConnectionPool) */
  64         protected static $instances = array();
  65
  66         /** integer; seconds to cache servers as "down". */
  67         const SERVER_DOWN_TTL = 30;
  68
  69         /**
  70          * @param array $options
  71          */
  72         protected function __construct( array $options ) {
  73                 if ( !class_exists( 'Redis' ) ) {
  74                         throw new MWException( __CLASS__ . ' requires a Redis client library. ' .
  75                                 'See https://www.mediawiki.org/wiki/Redis#Setup' );
  76                 }
  77                 $this->connectTimeout = $options['connectTimeout'];
  78                 $this->persistent = $options['persistent'];
  79                 $this->password = $options['password'];
  80                 if ( !isset( $options['serializer'] ) || $options['serializer'] === 'php' ) {
  81                         $this->serializer = Redis::SERIALIZER_PHP;
  82                 } elseif ( $options['serializer'] === 'igbinary' ) {
  83                         $this->serializer = Redis::SERIALIZER_IGBINARY;
  84                 } elseif ( $options['serializer'] === 'none' ) {
  85                         $this->serializer = Redis::SERIALIZER_NONE;
  86                 } else {
  87                         throw new MWException( "Invalid serializer specified." );
  88                 }
  89         }
  90
  91         /**
  92          * @param $options Array
  93          * @return Array
  94          */
  95         protected static function applyDefaultConfig( array $options ) {
  96                 if ( !isset( $options['connectTimeout'] ) ) {
  97                         $options['connectTimeout'] = 1;
  98                 }
  99                 if ( !isset( $options['persistent'] ) ) {
 100                         $options['persistent'] = false;
 101                 }
 102                 if ( !isset( $options['password'] ) ) {
 103                         $options['password'] = null;
 104                 }
 105                 return $options;
 106         }
 107
 108         /**
 109          * @param $options Array
 110          * $options include:
 111          *   - connectTimeout : The timeout for new connections, in seconds.
 112          *                      Optional, default is 1 second.
 113          *   - persistent     : Set this to true to allow connections to persist across
 114          *                      multiple web requests. False by default.
 115          *   - password       : The authentication password, will be sent to Redis in clear text.
 116          *                      Optional, if it is unspecified, no AUTH command will be sent.
 117          *   - serializer     : Set to "php", "igbinary", or "none". Default is "php".
 118          * @return RedisConnectionPool
 119          */
 120         public static function singleton( array $options ) {
 121                 $options = self::applyDefaultConfig( $options );
 122                 // Map the options to a unique hash...
 123                 ksort( $options ); // normalize to avoid pool fragmentation
 124                 $id = sha1( serialize( $options ) );
 125                 // Initialize the object at the hash as needed...
 126                 if ( !isset( self::$instances[$id] ) ) {
 127                         self::$instances[$id] = new self( $options );
 128                         wfDebug( "Creating a new " . __CLASS__ . " instance with id $id." );
 129                 }
 130                 return self::$instances[$id];
 131         }
 132
 133         /**
 134          * Get a connection to a redis server. Based on code in RedisBagOStuff.php.
 135          *
 136          * @param string $server A hostname/port combination or the absolute path of a UNIX socket.
 137          *                       If a hostname is specified but no port, port 6379 will be used.
 138          * @return RedisConnRef|bool Returns false on failure
 139          * @throws MWException
 140          */
 141         public function getConnection( $server ) {
 142                 // Check the listing "dead" servers which have had a connection errors.
 143                 // Servers are marked dead for a limited period of time, to
 144                 // avoid excessive overhead from repeated connection timeouts.
 145                 if ( isset( $this->downServers[$server] ) ) {
 146                         $now = time();
 147                         if ( $now > $this->downServers[$server] ) {
 148                                 // Dead time expired
 149                                 unset( $this->downServers[$server] );
 150                         } else {
 151                                 // Server is dead
 152                                 wfDebug( "server $server is marked down for another " .
 153                                         ( $this->downServers[$server] - $now ) . " seconds, can't get connection" );
 154                                 return false;
 155                         }
 156                 }
 157
 158                 // Check if a connection is already free for use
 159                 if ( isset( $this->connections[$server] ) ) {
 160                         foreach ( $this->connections[$server] as &$connection ) {
 161                                 if ( $connection['free'] ) {
 162                                         $connection['free'] = false;
 163                                         --$this->idlePoolSize;
 164                                         return new RedisConnRef( $this, $server, $connection['conn'] );
 165                                 }
 166                         }
 167                 }
 168
 169                 if ( substr( $server, 0, 1 ) === '/' ) {
 170                         // UNIX domain socket
 171                         // These are required by the redis extension to start with a slash, but
 172                         // we still need to set the port to a special value to make it work.
 173                         $host = $server;
 174                         $port = 0;
 175                 } else {
 176                         // TCP connection
 177                         $hostPort = IP::splitHostAndPort( $server );
 178                         if ( !$hostPort ) {
 179                                 throw new MWException( __CLASS__ . ": invalid configured server \"$server\"" );
 180                         }
 181                         list( $host, $port ) = $hostPort;
 182                         if ( $port === false ) {
 183                                 $port = 6379;
 184                         }
 185                 }
 186
 187                 $conn = new Redis();
 188                 try {
 189                         if ( $this->persistent ) {
 190                                 $result = $conn->pconnect( $host, $port, $this->connectTimeout );
 191                         } else {
 192                                 $result = $conn->connect( $host, $port, $this->connectTimeout );
 193                         }
 194                         if ( !$result ) {
 195                                 wfDebugLog( 'redis', "Could not connect to server $server" );
 196                                 // Mark server down for some time to avoid further timeouts
 197                                 $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 198                                 return false;
 199                         }
 200                         if ( $this->password !== null ) {
 201                                 if ( !$conn->auth( $this->password ) ) {
 202                                         wfDebugLog( 'redis', "Authentication error connecting to $server" );
 203                                 }
 204                         }
 205                 } catch ( RedisException $e ) {
 206                         $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 207                         wfDebugLog( 'redis', "Redis exception: " . $e->getMessage() . "\n" );
 208                         return false;
 209                 }
 210
 211                 if ( $conn ) {
 212                         $conn->setOption( Redis::OPT_SERIALIZER, $this->serializer );
 213                         $this->connections[$server][] = array( 'conn' => $conn, 'free' => false );
 214                         return new RedisConnRef( $this, $server, $conn );
 215                 } else {
 216                         return false;
 217                 }
 218         }
 219
 220         /**
 221          * Mark a connection to a server as free to return to the pool
 222          *
 223          * @param $server string
 224          * @param $conn Redis
 225          * @return boolean
 226          */
 227         public function freeConnection( $server, Redis $conn ) {
 228                 $found = false;
 229
 230                 foreach ( $this->connections[$server] as &$connection ) {
 231                         if ( $connection['conn'] === $conn && !$connection['free'] ) {
 232                                 $connection['free'] = true;
 233                                 ++$this->idlePoolSize;
 234                                 break;
 235                         }
 236                 }
 237
 238                 $this->closeExcessIdleConections();
 239
 240                 return $found;
 241         }
 242
 243         /**
 244          * Close any extra idle connections if there are more than the limit
 245          *
 246          * @return void
 247          */
 248         protected function closeExcessIdleConections() {
 249                 if ( $this->idlePoolSize <= count( $this->connections ) ) {
 250                         return; // nothing to do (no more connections than servers)
 251                 }
 252
 253                 foreach ( $this->connections as $server => &$serverConnections ) {
 254                         foreach ( $serverConnections as $key => &$connection ) {
 255                                 if ( $connection['free'] ) {
 256                                         unset( $serverConnections[$key] );
 257                                         if ( --$this->idlePoolSize <= count( $this->connections ) ) {
 258                                                 return; // done (no more connections than servers)
 259                                         }
 260                                 }
 261                         }
 262                 }
 263         }
 264
 265         /**
 266          * The redis extension throws an exception in response to various read, write
 267          * and protocol errors. Sometimes it also closes the connection, sometimes
 268          * not. The safest response for us is to explicitly destroy the connection
 269          * object and let it be reopened during the next request.
 270          *
 271          * @param $server string
 272          * @param $cref RedisConnRef
 273          * @param $e RedisException
 274          * @return void
 275          */
 276         public function handleException( $server, RedisConnRef $cref, RedisException $e ) {
 277                 wfDebugLog( 'redis', "Redis exception on server $server: " . $e->getMessage() . "\n" );
 278                 foreach ( $this->connections[$server] as $key => $connection ) {
 279                         if ( $cref->isConnIdentical( $connection['conn'] ) ) {
 280                                 $this->idlePoolSize -= $connection['free'] ? 1 : 0;
 281                                 unset( $this->connections[$server][$key] );
 282                                 break;
 283                         }
 284                 }
 285         }
 286
 287         /**
 288          * Re-send an AUTH request to the redis server (useful after disconnects).
 289          *
 290          * This works around an upstream bug in phpredis. phpredis hides disconnects by transparently
 291          * reconnecting, but it neglects to re-authenticate the new connection. To the user of the
 292          * phpredis client API this manifests as a seemingly random tendency of connections to lose
 293          * their authentication status.
 294          *
 295          * This method is for internal use only.
 296          *
 297          * @see https://github.com/nicolasff/phpredis/issues/403
 298          *
 299          * @param string $server
 300          * @param Redis $conn
 301          * @return bool Success
 302          */
 303         public function reauthenticateConnection( $server, Redis $conn ) {
 304                 if ( $this->password !== null ) {
 305                         if ( !$conn->auth( $this->password ) ) {
 306                                 wfDebugLog( 'redis', "Authentication error connecting to $server" );
 307                                 return false;
 308                         }
 309                 }
 310                 return true;
 311         }
 312 }
 313
 314 /**
 315  * Helper class to handle automatically marking connectons as reusable (via RAII pattern)
 316  *
 317  * This class simply wraps the Redis class and can be used the same way
 318  *
 319  * @ingroup Redis
 320  * @since 1.21
 321  */
 322 class RedisConnRef {
 323         /** @var RedisConnectionPool */
 324         protected $pool;
 325         /** @var Redis */
 326         protected $conn;
 327
 328         protected $server; // string
 329         protected $lastError; // string
 330
 331         /**
 332          * @param $pool RedisConnectionPool
 333          * @param $server string
 334          * @param $conn Redis
 335          */
 336         public function __construct( RedisConnectionPool $pool, $server, Redis $conn ) {
 337                 $this->pool = $pool;
 338                 $this->server = $server;
 339                 $this->conn = $conn;
 340         }
 341
 342         /**
 343          * @return string
 344          * @since 1.23
 345          */
 346         public function getServer() {
 347                 return $this->server;
 348         }
 349
 350         public function getLastError() {
 351                 return $this->lastError;
 352         }
 353
 354         public function clearLastError() {
 355                 $this->lastError = null;
 356         }
 357
 358         public function __call( $name, $arguments ) {
 359                 $conn = $this->conn; // convenience
 360
 361                 $conn->clearLastError();
 362                 $res = call_user_func_array( array( $conn, $name ), $arguments );
 363                 if ( preg_match( '/^ERR operation not permitted\b/', $conn->getLastError() ) ) {
 364                         $this->pool->reauthenticateConnection( $this->server, $conn );
 365                         $conn->clearLastError();
 366                         $res = call_user_func_array( array( $conn, $name ), $arguments );
 367                         wfDebugLog( 'redis', "Used automatic re-authentication for method '$name'." );
 368                 }
 369
 370                 $this->lastError = $conn->getLastError() ?: $this->lastError;
 371
 372                 return $res;
 373         }
 374
 375         /**
 376          * @param string $script
 377          * @param array $params
 378          * @param integer $numKeys
 379          * @return mixed
 380          * @throws RedisException
 381          */
 382         public function luaEval( $script, array $params, $numKeys ) {
 383                 $sha1 = sha1( $script ); // 40 char hex
 384                 $conn = $this->conn; // convenience
 385                 $server = $this->server; // convenience
 386
 387                 // Try to run the server-side cached copy of the script
 388                 $conn->clearLastError();
 389                 $res = $conn->evalSha( $sha1, $params, $numKeys );
 390                 // If we got a permission error reply that means that (a) we are not in
 391                 // multi()/pipeline() and (b) some connection problem likely occured. If
 392                 // the password the client gave was just wrong, an exception should have
 393                 // been thrown back in getConnection() previously.
 394                 if ( preg_match( '/^ERR operation not permitted\b/', $conn->getLastError() ) ) {
 395                         $this->pool->reauthenticateConnection( $server, $conn );
 396                         $conn->clearLastError();
 397                         $res = $conn->eval( $script, $params, $numKeys );
 398                         wfDebugLog( 'redis', "Used automatic re-authentication for Lua script $sha1." );
 399                 }
 400                 // If the script is not in cache, use eval() to retry and cache it
 401                 if ( preg_match( '/^NOSCRIPT/', $conn->getLastError() ) ) {
 402                         $conn->clearLastError();
 403                         $res = $conn->eval( $script, $params, $numKeys );
 404                         wfDebugLog( 'redis', "Used eval() for Lua script $sha1." );
 405                 }
 406
 407                 if ( $conn->getLastError() ) { // script bug?
 408                         wfDebugLog( 'redis', "Lua script error on server $server: " . $conn->getLastError() );
 409                 }
 410
 411                 $this->lastError = $conn->getLastError() ?: $this->lastError;
 412
 413                 return $res;
 414         }
 415
 416         /**
 417          * @param RedisConnRef $conn
 418          * @return bool
 419          */
 420         public function isConnIdentical( Redis $conn ) {
 421                 return $this->conn === $conn;
 422         }
 423
 424         function __destruct() {
 425                 $this->pool->freeConnection( $this->server, $this->conn );
 426         }
 427 }