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