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 int 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          * @throws MWException
  72          */
  73         protected function __construct( array $options ) {
  74                 if ( !class_exists( 'Redis' ) ) {
  75                         throw new MWException( __CLASS__ . ' requires a Redis client library. ' .
  76                                 'See https://www.mediawiki.org/wiki/Redis#Setup' );
  77                 }
  78                 $this->connectTimeout = $options['connectTimeout'];
  79                 $this->persistent = $options['persistent'];
  80                 $this->password = $options['password'];
  81                 if ( !isset( $options['serializer'] ) || $options['serializer'] === 'php' ) {
  82                         $this->serializer = Redis::SERIALIZER_PHP;
  83                 } elseif ( $options['serializer'] === 'igbinary' ) {
  84                         $this->serializer = Redis::SERIALIZER_IGBINARY;
  85                 } elseif ( $options['serializer'] === 'none' ) {
  86                         $this->serializer = Redis::SERIALIZER_NONE;
  87                 } else {
  88                         throw new MWException( "Invalid serializer specified." );
  89                 }
  90         }
  91
  92         /**
  93          * @param array $options
  94          * @return array
  95          */
  96         protected static function applyDefaultConfig( array $options ) {
  97                 if ( !isset( $options['connectTimeout'] ) ) {
  98                         $options['connectTimeout'] = 1;
  99                 }
 100                 if ( !isset( $options['persistent'] ) ) {
 101                         $options['persistent'] = false;
 102                 }
 103                 if ( !isset( $options['password'] ) ) {
 104                         $options['password'] = null;
 105                 }
 106
 107                 return $options;
 108         }
 109
 110         /**
 111          * @param array $options
 112          * $options include:
 113          *   - connectTimeout : The timeout for new connections, in seconds.
 114          *                      Optional, default is 1 second.
 115          *   - persistent     : Set this to true to allow connections to persist across
 116          *                      multiple web requests. False by default.
 117          *   - password       : The authentication password, will be sent to Redis in clear text.
 118          *                      Optional, if it is unspecified, no AUTH command will be sent.
 119          *   - serializer     : Set to "php", "igbinary", or "none". Default is "php".
 120          * @return RedisConnectionPool
 121          */
 122         public static function singleton( array $options ) {
 123                 $options = self::applyDefaultConfig( $options );
 124                 // Map the options to a unique hash...
 125                 ksort( $options ); // normalize to avoid pool fragmentation
 126                 $id = sha1( serialize( $options ) );
 127                 // Initialize the object at the hash as needed...
 128                 if ( !isset( self::$instances[$id] ) ) {
 129                         self::$instances[$id] = new self( $options );
 130                         wfDebug( "Creating a new " . __CLASS__ . " instance with id $id." );
 131                 }
 132
 133                 return self::$instances[$id];
 134         }
 135
 136         /**
 137          * Get a connection to a redis server. Based on code in RedisBagOStuff.php.
 138          *
 139          * @param string $server A hostname/port combination or the absolute path of a UNIX socket.
 140          *                       If a hostname is specified but no port, port 6379 will be used.
 141          * @return RedisConnRef|bool Returns false on failure
 142          * @throws MWException
 143          */
 144         public function getConnection( $server ) {
 145                 // Check the listing "dead" servers which have had a connection errors.
 146                 // Servers are marked dead for a limited period of time, to
 147                 // avoid excessive overhead from repeated connection timeouts.
 148                 if ( isset( $this->downServers[$server] ) ) {
 149                         $now = time();
 150                         if ( $now > $this->downServers[$server] ) {
 151                                 // Dead time expired
 152                                 unset( $this->downServers[$server] );
 153                         } else {
 154                                 // Server is dead
 155                                 wfDebug( "server $server is marked down for another " .
 156                                         ( $this->downServers[$server] - $now ) . " seconds, can't get connection" );
 157
 158                                 return false;
 159                         }
 160                 }
 161
 162                 // Check if a connection is already free for use
 163                 if ( isset( $this->connections[$server] ) ) {
 164                         foreach ( $this->connections[$server] as &$connection ) {
 165                                 if ( $connection['free'] ) {
 166                                         $connection['free'] = false;
 167                                         --$this->idlePoolSize;
 168
 169                                         return new RedisConnRef( $this, $server, $connection['conn'] );
 170                                 }
 171                         }
 172                 }
 173
 174                 if ( substr( $server, 0, 1 ) === '/' ) {
 175                         // UNIX domain socket
 176                         // These are required by the redis extension to start with a slash, but
 177                         // we still need to set the port to a special value to make it work.
 178                         $host = $server;
 179                         $port = 0;
 180                 } else {
 181                         // TCP connection
 182                         $hostPort = IP::splitHostAndPort( $server );
 183                         if ( !$hostPort ) {
 184                                 throw new MWException( __CLASS__ . ": invalid configured server \"$server\"" );
 185                         }
 186                         list( $host, $port ) = $hostPort;
 187                         if ( $port === false ) {
 188                                 $port = 6379;
 189                         }
 190                 }
 191
 192                 $conn = new Redis();
 193                 try {
 194                         if ( $this->persistent ) {
 195                                 $result = $conn->pconnect( $host, $port, $this->connectTimeout );
 196                         } else {
 197                                 $result = $conn->connect( $host, $port, $this->connectTimeout );
 198                         }
 199                         if ( !$result ) {
 200                                 wfDebugLog( 'redis', "Could not connect to server $server" );
 201                                 // Mark server down for some time to avoid further timeouts
 202                                 $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 203
 204                                 return false;
 205                         }
 206                         if ( $this->password !== null ) {
 207                                 if ( !$conn->auth( $this->password ) ) {
 208                                         wfDebugLog( 'redis', "Authentication error connecting to $server" );
 209                                 }
 210                         }
 211                 } catch ( RedisException $e ) {
 212                         $this->downServers[$server] = time() + self::SERVER_DOWN_TTL;
 213                         wfDebugLog( 'redis', "Redis exception connecting to $server: " . $e->getMessage() );
 214
 215                         return false;
 216                 }
 217
 218                 if ( $conn ) {
 219                         $conn->setOption( Redis::OPT_SERIALIZER, $this->serializer );
 220                         $this->connections[$server][] = array( 'conn' => $conn, 'free' => false );
 221
 222                         return new RedisConnRef( $this, $server, $conn );
 223                 } else {
 224                         return false;
 225                 }
 226         }
 227
 228         /**
 229          * Mark a connection to a server as free to return to the pool
 230          *
 231          * @param string $server
 232          * @param Redis $conn
 233          * @return bool
 234          */
 235         public function freeConnection( $server, Redis $conn ) {
 236                 $found = false;
 237
 238                 foreach ( $this->connections[$server] as &$connection ) {
 239                         if ( $connection['conn'] === $conn && !$connection['free'] ) {
 240                                 $connection['free'] = true;
 241                                 ++$this->idlePoolSize;
 242                                 break;
 243                         }
 244                 }
 245
 246                 $this->closeExcessIdleConections();
 247
 248                 return $found;
 249         }
 250
 251         /**
 252          * Close any extra idle connections if there are more than the limit
 253          */
 254         protected function closeExcessIdleConections() {
 255                 if ( $this->idlePoolSize <= count( $this->connections ) ) {
 256                         return; // nothing to do (no more connections than servers)
 257                 }
 258
 259                 foreach ( $this->connections as &$serverConnections ) {
 260                         foreach ( $serverConnections as $key => &$connection ) {
 261                                 if ( $connection['free'] ) {
 262                                         unset( $serverConnections[$key] );
 263                                         if ( --$this->idlePoolSize <= count( $this->connections ) ) {
 264                                                 return; // done (no more connections than servers)
 265                                         }
 266                                 }
 267                         }
 268                 }
 269         }
 270
 271         /**
 272          * The redis extension throws an exception in response to various read, write
 273          * and protocol errors. Sometimes it also closes the connection, sometimes
 274          * not. The safest response for us is to explicitly destroy the connection
 275          * object and let it be reopened during the next request.
 276          *
 277          * @param string $server
 278          * @param RedisConnRef $cref
 279          * @param RedisException $e
 280          */
 281         public function handleException( $server, RedisConnRef $cref, RedisException $e ) {
 282                 wfDebugLog( 'redis', "Redis exception on server $server: " . $e->getMessage() );
 283                 foreach ( $this->connections[$server] as $key => $connection ) {
 284                         if ( $cref->isConnIdentical( $connection['conn'] ) ) {
 285                                 $this->idlePoolSize -= $connection['free'] ? 1 : 0;
 286                                 unset( $this->connections[$server][$key] );
 287                                 break;
 288                         }
 289                 }
 290         }
 291
 292         /**
 293          * Re-send an AUTH request to the redis server (useful after disconnects).
 294          *
 295          * This works around an upstream bug in phpredis. phpredis hides disconnects by transparently
 296          * reconnecting, but it neglects to re-authenticate the new connection. To the user of the
 297          * phpredis client API this manifests as a seemingly random tendency of connections to lose
 298          * their authentication status.
 299          *
 300          * This method is for internal use only.
 301          *
 302          * @see https://github.com/nicolasff/phpredis/issues/403
 303          *
 304          * @param string $server
 305          * @param Redis $conn
 306          * @return bool Success
 307          */
 308         public function reauthenticateConnection( $server, Redis $conn ) {
 309                 if ( $this->password !== null ) {
 310                         if ( !$conn->auth( $this->password ) ) {
 311                                 wfDebugLog( 'redis', "Authentication error connecting to $server" );
 312
 313                                 return false;
 314                         }
 315                 }
 316
 317                 return true;
 318         }
 319
 320         /**
 321          * Make sure connections are closed for sanity
 322          */
 323         function __destruct() {
 324                 foreach ( $this->connections as $server => &$serverConnections ) {
 325                         foreach ( $serverConnections as $key => &$connection ) {
 326                                 $connection['conn']->close();
 327                         }
 328                 }
 329         }
 330 }
 331
 332 /**
 333  * Helper class to handle automatically marking connectons as reusable (via RAII pattern)
 334  *
 335  * This class simply wraps the Redis class and can be used the same way
 336  *
 337  * @ingroup Redis
 338  * @since 1.21
 339  */
 340 class RedisConnRef {
 341         /** @var RedisConnectionPool */
 342         protected $pool;
 343         /** @var Redis */
 344         protected $conn;
 345
 346         protected $server; // string
 347         protected $lastError; // string
 348
 349         /**
 350          * @param RedisConnectionPool $pool
 351          * @param string $server
 352          * @param Redis $conn
 353          */
 354         public function __construct( RedisConnectionPool $pool, $server, Redis $conn ) {
 355                 $this->pool = $pool;
 356                 $this->server = $server;
 357                 $this->conn = $conn;
 358         }
 359
 360         /**
 361          * @return string
 362          * @since 1.23
 363          */
 364         public function getServer() {
 365                 return $this->server;
 366         }
 367
 368         public function getLastError() {
 369                 return $this->lastError;
 370         }
 371
 372         public function clearLastError() {
 373                 $this->lastError = null;
 374         }
 375
 376         public function __call( $name, $arguments ) {
 377                 $conn = $this->conn; // convenience
 378
 379                 $conn->clearLastError();
 380                 $res = call_user_func_array( array( $conn, $name ), $arguments );
 381                 if ( preg_match( '/^ERR operation not permitted\b/', $conn->getLastError() ) ) {
 382                         $this->pool->reauthenticateConnection( $this->server, $conn );
 383                         $conn->clearLastError();
 384                         $res = call_user_func_array( array( $conn, $name ), $arguments );
 385                         wfDebugLog( 'redis', "Used automatic re-authentication for method '$name'." );
 386                 }
 387
 388                 $this->lastError = $conn->getLastError() ?: $this->lastError;
 389
 390                 return $res;
 391         }
 392
 393         /**
 394          * @param string $script
 395          * @param array $params
 396          * @param integer $numKeys
 397          * @return mixed
 398          * @throws RedisException
 399          */
 400         public function luaEval( $script, array $params, $numKeys ) {
 401                 $sha1 = sha1( $script ); // 40 char hex
 402                 $conn = $this->conn; // convenience
 403                 $server = $this->server; // convenience
 404
 405                 // Try to run the server-side cached copy of the script
 406                 $conn->clearLastError();
 407                 $res = $conn->evalSha( $sha1, $params, $numKeys );
 408                 // If we got a permission error reply that means that (a) we are not in
 409                 // multi()/pipeline() and (b) some connection problem likely occured. If
 410                 // the password the client gave was just wrong, an exception should have
 411                 // been thrown back in getConnection() previously.
 412                 if ( preg_match( '/^ERR operation not permitted\b/', $conn->getLastError() ) ) {
 413                         $this->pool->reauthenticateConnection( $server, $conn );
 414                         $conn->clearLastError();
 415                         $res = $conn->eval( $script, $params, $numKeys );
 416                         wfDebugLog( 'redis', "Used automatic re-authentication for Lua script $sha1." );
 417                 }
 418                 // If the script is not in cache, use eval() to retry and cache it
 419                 if ( preg_match( '/^NOSCRIPT/', $conn->getLastError() ) ) {
 420                         $conn->clearLastError();
 421                         $res = $conn->eval( $script, $params, $numKeys );
 422                         wfDebugLog( 'redis', "Used eval() for Lua script $sha1." );
 423                 }
 424
 425                 if ( $conn->getLastError() ) { // script bug?
 426                         wfDebugLog( 'redis', "Lua script error on server $server: " . $conn->getLastError() );
 427                 }
 428
 429                 $this->lastError = $conn->getLastError() ?: $this->lastError;
 430
 431                 return $res;
 432         }
 433
 434         /**
 435          * @param Redis $conn
 436          * @return bool
 437          */
 438         public function isConnIdentical( Redis $conn ) {
 439                 return $this->conn === $conn;
 440         }
 441
 442         function __destruct() {
 443                 $this->pool->freeConnection( $this->server, $this->conn );
 444         }
 445 }