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