includes/objectcache/RedisBagOStuff.php

   1 <?php
   2 /**
   3  * Object caching using Redis (http://redis.io/).
   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  */
  22
  23 class RedisBagOStuff extends BagOStuff {
  24         /** @var RedisConnectionPool */
  25         protected $redisPool;
  26         /** @var array List of server names */
  27         protected $servers;
  28         /** @var array Map of (tag => server name) */
  29         protected $serverTagMap;
  30         /** @var bool */
  31         protected $automaticFailover;
  32
  33         /**
  34          * Construct a RedisBagOStuff object. Parameters are:
  35          *
  36          *   - servers: An array of server names. A server name may be a hostname,
  37          *     a hostname/port combination or the absolute path of a UNIX socket.
  38          *     If a hostname is specified but no port, the standard port number
  39          *     6379 will be used. Arrays keys can be used to specify the tag to
  40          *     hash on in place of the host/port. Required.
  41          *
  42          *   - connectTimeout: The timeout for new connections, in seconds. Optional,
  43          *     default is 1 second.
  44          *
  45          *   - persistent: Set this to true to allow connections to persist across
  46          *     multiple web requests. False by default.
  47          *
  48          *   - password: The authentication password, will be sent to Redis in
  49          *     clear text. Optional, if it is unspecified, no AUTH command will be
  50          *     sent.
  51          *
  52          *   - automaticFailover: If this is false, then each key will be mapped to
  53          *     a single server, and if that server is down, any requests for that key
  54          *     will fail. If this is true, a connection failure will cause the client
  55          *     to immediately try the next server in the list (as determined by a
  56          *     consistent hashing algorithm). True by default. This has the
  57          *     potential to create consistency issues if a server is slow enough to
  58          *     flap, for example if it is in swap death.
  59          * @param array $params
  60          */
  61         function __construct( $params ) {
  62                 parent::__construct( $params );
  63                 $redisConf = array( 'serializer' => 'none' ); // manage that in this class
  64                 foreach ( array( 'connectTimeout', 'persistent', 'password' ) as $opt ) {
  65                         if ( isset( $params[$opt] ) ) {
  66                                 $redisConf[$opt] = $params[$opt];
  67                         }
  68                 }
  69                 $this->redisPool = RedisConnectionPool::singleton( $redisConf );
  70
  71                 $this->servers = $params['servers'];
  72                 foreach ( $this->servers as $key => $server ) {
  73                         $this->serverTagMap[is_int( $key ) ? $server : $key] = $server;
  74                 }
  75
  76                 if ( isset( $params['automaticFailover'] ) ) {
  77                         $this->automaticFailover = $params['automaticFailover'];
  78                 } else {
  79                         $this->automaticFailover = true;
  80                 }
  81         }
  82
  83         public function get( $key, &$casToken = null ) {
  84
  85                 list( $server, $conn ) = $this->getConnection( $key );
  86                 if ( !$conn ) {
  87                         return false;
  88                 }
  89                 try {
  90                         $value = $conn->get( $key );
  91                         $casToken = $value;
  92                         $result = $this->unserialize( $value );
  93                 } catch ( RedisException $e ) {
  94                         $result = false;
  95                         $this->handleException( $conn, $e );
  96                 }
  97
  98                 $this->logRequest( 'get', $key, $server, $result );
  99                 return $result;
 100         }
 101
 102         public function set( $key, $value, $expiry = 0 ) {
 103
 104                 list( $server, $conn ) = $this->getConnection( $key );
 105                 if ( !$conn ) {
 106                         return false;
 107                 }
 108                 $expiry = $this->convertToRelative( $expiry );
 109                 try {
 110                         if ( $expiry ) {
 111                                 $result = $conn->setex( $key, $expiry, $this->serialize( $value ) );
 112                         } else {
 113                                 // No expiry, that is very different from zero expiry in Redis
 114                                 $result = $conn->set( $key, $this->serialize( $value ) );
 115                         }
 116                 } catch ( RedisException $e ) {
 117                         $result = false;
 118                         $this->handleException( $conn, $e );
 119                 }
 120
 121                 $this->logRequest( 'set', $key, $server, $result );
 122                 return $result;
 123         }
 124
 125         protected function cas( $casToken, $key, $value, $expiry = 0 ) {
 126
 127                 list( $server, $conn ) = $this->getConnection( $key );
 128                 if ( !$conn ) {
 129                         return false;
 130                 }
 131                 $expiry = $this->convertToRelative( $expiry );
 132                 try {
 133                         $conn->watch( $key );
 134
 135                         if ( $this->serialize( $this->get( $key ) ) !== $casToken ) {
 136                                 $conn->unwatch();
 137                                 return false;
 138                         }
 139
 140                         // multi()/exec() will fail atomically if the key changed since watch()
 141                         $conn->multi();
 142                         if ( $expiry ) {
 143                                 $conn->setex( $key, $expiry, $this->serialize( $value ) );
 144                         } else {
 145                                 // No expiry, that is very different from zero expiry in Redis
 146                                 $conn->set( $key, $this->serialize( $value ) );
 147                         }
 148                         $result = ( $conn->exec() == array( true ) );
 149                 } catch ( RedisException $e ) {
 150                         $result = false;
 151                         $this->handleException( $conn, $e );
 152                 }
 153
 154                 $this->logRequest( 'cas', $key, $server, $result );
 155                 return $result;
 156         }
 157
 158         public function delete( $key ) {
 159
 160                 list( $server, $conn ) = $this->getConnection( $key );
 161                 if ( !$conn ) {
 162                         return false;
 163                 }
 164                 try {
 165                         $conn->delete( $key );
 166                         // Return true even if the key didn't exist
 167                         $result = true;
 168                 } catch ( RedisException $e ) {
 169                         $result = false;
 170                         $this->handleException( $conn, $e );
 171                 }
 172
 173                 $this->logRequest( 'delete', $key, $server, $result );
 174                 return $result;
 175         }
 176
 177         public function getMulti( array $keys ) {
 178
 179                 $batches = array();
 180                 $conns = array();
 181                 foreach ( $keys as $key ) {
 182                         list( $server, $conn ) = $this->getConnection( $key );
 183                         if ( !$conn ) {
 184                                 continue;
 185                         }
 186                         $conns[$server] = $conn;
 187                         $batches[$server][] = $key;
 188                 }
 189                 $result = array();
 190                 foreach ( $batches as $server => $batchKeys ) {
 191                         $conn = $conns[$server];
 192                         try {
 193                                 $conn->multi( Redis::PIPELINE );
 194                                 foreach ( $batchKeys as $key ) {
 195                                         $conn->get( $key );
 196                                 }
 197                                 $batchResult = $conn->exec();
 198                                 if ( $batchResult === false ) {
 199                                         $this->debug( "multi request to $server failed" );
 200                                         continue;
 201                                 }
 202                                 foreach ( $batchResult as $i => $value ) {
 203                                         if ( $value !== false ) {
 204                                                 $result[$batchKeys[$i]] = $this->unserialize( $value );
 205                                         }
 206                                 }
 207                         } catch ( RedisException $e ) {
 208                                 $this->handleException( $conn, $e );
 209                         }
 210                 }
 211
 212                 $this->debug( "getMulti for " . count( $keys ) . " keys " .
 213                         "returned " . count( $result ) . " results" );
 214                 return $result;
 215         }
 216
 217         /**
 218          * @param array $data
 219          * @param int $expiry
 220          * @return bool
 221          */
 222         public function setMulti( array $data, $expiry = 0 ) {
 223
 224                 $batches = array();
 225                 $conns = array();
 226                 foreach ( $data as $key => $value ) {
 227                         list( $server, $conn ) = $this->getConnection( $key );
 228                         if ( !$conn ) {
 229                                 continue;
 230                         }
 231                         $conns[$server] = $conn;
 232                         $batches[$server][] = $key;
 233                 }
 234
 235                 $expiry = $this->convertToRelative( $expiry );
 236                 $result = true;
 237                 foreach ( $batches as $server => $batchKeys ) {
 238                         $conn = $conns[$server];
 239                         try {
 240                                 $conn->multi( Redis::PIPELINE );
 241                                 foreach ( $batchKeys as $key ) {
 242                                         if ( $expiry ) {
 243                                                 $conn->setex( $key, $expiry, $this->serialize( $data[$key] ) );
 244                                         } else {
 245                                                 $conn->set( $key, $this->serialize( $data[$key] ) );
 246                                         }
 247                                 }
 248                                 $batchResult = $conn->exec();
 249                                 if ( $batchResult === false ) {
 250                                         $this->debug( "setMulti request to $server failed" );
 251                                         continue;
 252                                 }
 253                                 foreach ( $batchResult as $value ) {
 254                                         if ( $value === false ) {
 255                                                 $result = false;
 256                                         }
 257                                 }
 258                         } catch ( RedisException $e ) {
 259                                 $this->handleException( $server, $conn, $e );
 260                                 $result = false;
 261                         }
 262                 }
 263
 264                 return $result;
 265         }
 266
 267
 268
 269         public function add( $key, $value, $expiry = 0 ) {
 270
 271                 list( $server, $conn ) = $this->getConnection( $key );
 272                 if ( !$conn ) {
 273                         return false;
 274                 }
 275                 $expiry = $this->convertToRelative( $expiry );
 276                 try {
 277                         if ( $expiry ) {
 278                                 $conn->multi();
 279                                 $conn->setnx( $key, $this->serialize( $value ) );
 280                                 $conn->expire( $key, $expiry );
 281                                 $result = ( $conn->exec() == array( true, true ) );
 282                         } else {
 283                                 $result = $conn->setnx( $key, $this->serialize( $value ) );
 284                         }
 285                 } catch ( RedisException $e ) {
 286                         $result = false;
 287                         $this->handleException( $conn, $e );
 288                 }
 289
 290                 $this->logRequest( 'add', $key, $server, $result );
 291                 return $result;
 292         }
 293
 294         /**
 295          * Non-atomic implementation of incr().
 296          *
 297          * Probably all callers actually want incr() to atomically initialise
 298          * values to zero if they don't exist, as provided by the Redis INCR
 299          * command. But we are constrained by the memcached-like interface to
 300          * return null in that case. Once the key exists, further increments are
 301          * atomic.
 302          * @param string $key Key to increase
 303          * @param int $value Value to add to $key (Default 1)
 304          * @return int|bool New value or false on failure
 305          */
 306         public function incr( $key, $value = 1 ) {
 307
 308                 list( $server, $conn ) = $this->getConnection( $key );
 309                 if ( !$conn ) {
 310                         return false;
 311                 }
 312                 if ( !$conn->exists( $key ) ) {
 313                         return null;
 314                 }
 315                 try {
 316                         $result = $conn->incrBy( $key, $value );
 317                 } catch ( RedisException $e ) {
 318                         $result = false;
 319                         $this->handleException( $conn, $e );
 320                 }
 321
 322                 $this->logRequest( 'incr', $key, $server, $result );
 323                 return $result;
 324         }
 325
 326         public function merge( $key, $callback, $exptime = 0, $attempts = 10 ) {
 327                 if ( !is_callable( $callback ) ) {
 328                         throw new Exception( "Got invalid callback." );
 329                 }
 330
 331                 return $this->mergeViaCas( $key, $callback, $exptime, $attempts );
 332         }
 333
 334         public function modifySimpleRelayEvent( array $event ) {
 335                 if ( array_key_exists( 'val', $event ) ) {
 336                         $event['val'] = serialize( $event['val'] ); // this class uses PHP serialization
 337                 }
 338
 339                 return $event;
 340         }
 341
 342         /**
 343          * @param mixed $data
 344          * @return string
 345          */
 346         protected function serialize( $data ) {
 347                 // Serialize anything but integers so INCR/DECR work
 348                 // Do not store integer-like strings as integers to avoid type confusion (bug 60563)
 349                 return is_int( $data ) ? $data : serialize( $data );
 350         }
 351
 352         /**
 353          * @param string $data
 354          * @return mixed
 355          */
 356         protected function unserialize( $data ) {
 357                 return ctype_digit( $data ) ? intval( $data ) : unserialize( $data );
 358         }
 359
 360         /**
 361          * Get a Redis object with a connection suitable for fetching the specified key
 362          * @param string $key
 363          * @return array (server, RedisConnRef) or (false, false)
 364          */
 365         protected function getConnection( $key ) {
 366                 $candidates = array_keys( $this->serverTagMap );
 367
 368                 if ( count( $this->servers ) > 1 ) {
 369                         ArrayUtils::consistentHashSort( $candidates, $key, '/' );
 370                         if ( !$this->automaticFailover ) {
 371                                 $candidates = array_slice( $candidates, 0, 1 );
 372                         }
 373                 }
 374
 375                 foreach ( $candidates as $tag ) {
 376                         $server = $this->serverTagMap[$tag];
 377                         $conn = $this->redisPool->getConnection( $server );
 378                         if ( $conn ) {
 379                                 return array( $server, $conn );
 380                         }
 381                 }
 382
 383                 $this->setLastError( BagOStuff::ERR_UNREACHABLE );
 384
 385                 return array( false, false );
 386         }
 387
 388         /**
 389          * Log a fatal error
 390          * @param string $msg
 391          */
 392         protected function logError( $msg ) {
 393                 $this->logger->error( "Redis error: $msg" );
 394         }
 395
 396         /**
 397          * The redis extension throws an exception in response to various read, write
 398          * and protocol errors. Sometimes it also closes the connection, sometimes
 399          * not. The safest response for us is to explicitly destroy the connection
 400          * object and let it be reopened during the next request.
 401          * @param RedisConnRef $conn
 402          * @param Exception $e
 403          */
 404         protected function handleException( RedisConnRef $conn, $e ) {
 405                 $this->setLastError( BagOStuff::ERR_UNEXPECTED );
 406                 $this->redisPool->handleError( $conn, $e );
 407         }
 408
 409         /**
 410          * Send information about a single request to the debug log
 411          * @param string $method
 412          * @param string $key
 413          * @param string $server
 414          * @param bool $result
 415          */
 416         public function logRequest( $method, $key, $server, $result ) {
 417                 $this->debug( "$method $key on $server: " .
 418                         ( $result === false ? "failure" : "success" ) );
 419         }
 420 }