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          */
  57         function __construct( $params ) {
  58                 $redisConf = array( 'serializer' => 'none' ); // manage that in this class
  59                 foreach ( array( 'connectTimeout', 'persistent', 'password' ) as $opt ) {
  60                         if ( isset( $params[$opt] ) ) {
  61                                 $redisConf[$opt] = $params[$opt];
  62                         }
  63                 }
  64                 $this->redisPool = RedisConnectionPool::singleton( $redisConf );
  65
  66                 $this->servers = $params['servers'];
  67                 if ( isset( $params['automaticFailover'] ) ) {
  68                         $this->automaticFailover = $params['automaticFailover'];
  69                 } else {
  70                         $this->automaticFailover = true;
  71                 }
  72         }
  73
  74         public function get( $key, &$casToken = null ) {
  75                 $section = new ProfileSection( __METHOD__ );
  76
  77                 list( $server, $conn ) = $this->getConnection( $key );
  78                 if ( !$conn ) {
  79                         return false;
  80                 }
  81                 try {
  82                         $result = $this->unserialize( $conn->get( $key ) );
  83                 } catch ( RedisException $e ) {
  84                         $result = false;
  85                         $this->handleException( $server, $conn, $e );
  86                 }
  87                 $casToken = $result;
  88
  89                 $this->logRequest( 'get', $key, $server, $result );
  90                 return $result;
  91         }
  92
  93         public function set( $key, $value, $expiry = 0 ) {
  94                 $section = new ProfileSection( __METHOD__ );
  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( $server, $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                 $section = new ProfileSection( __METHOD__ );
 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->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( $server, $conn, $e );
 145                 }
 146
 147                 $this->logRequest( 'cas', $key, $server, $result );
 148                 return $result;
 149         }
 150
 151         public function delete( $key, $time = 0 ) {
 152                 $section = new ProfileSection( __METHOD__ );
 153
 154                 list( $server, $conn ) = $this->getConnection( $key );
 155                 if ( !$conn ) {
 156                         return false;
 157                 }
 158                 try {
 159                         $conn->delete( $key );
 160                         // Return true even if the key didn't exist
 161                         $result = true;
 162                 } catch ( RedisException $e ) {
 163                         $result = false;
 164                         $this->handleException( $server, $conn, $e );
 165                 }
 166
 167                 $this->logRequest( 'delete', $key, $server, $result );
 168                 return $result;
 169         }
 170
 171         public function getMulti( array $keys ) {
 172                 $section = new ProfileSection( __METHOD__ );
 173
 174                 $batches = array();
 175                 $conns = array();
 176                 foreach ( $keys as $key ) {
 177                         list( $server, $conn ) = $this->getConnection( $key );
 178                         if ( !$conn ) {
 179                                 continue;
 180                         }
 181                         $conns[$server] = $conn;
 182                         $batches[$server][] = $key;
 183                 }
 184                 $result = array();
 185                 foreach ( $batches as $server => $batchKeys ) {
 186                         $conn = $conns[$server];
 187                         try {
 188                                 $conn->multi( Redis::PIPELINE );
 189                                 foreach ( $batchKeys as $key ) {
 190                                         $conn->get( $key );
 191                                 }
 192                                 $batchResult = $conn->exec();
 193                                 if ( $batchResult === false ) {
 194                                         $this->debug( "multi request to $server failed" );
 195                                         continue;
 196                                 }
 197                                 foreach ( $batchResult as $i => $value ) {
 198                                         if ( $value !== false ) {
 199                                                 $result[$batchKeys[$i]] = $this->unserialize( $value );
 200                                         }
 201                                 }
 202                         } catch ( RedisException $e ) {
 203                                 $this->handleException( $server, $conn, $e );
 204                         }
 205                 }
 206
 207                 $this->debug( "getMulti for " . count( $keys ) . " keys " .
 208                         "returned " . count( $result ) . " results" );
 209                 return $result;
 210         }
 211
 212         public function add( $key, $value, $expiry = 0 ) {
 213                 $section = new ProfileSection( __METHOD__ );
 214
 215                 list( $server, $conn ) = $this->getConnection( $key );
 216                 if ( !$conn ) {
 217                         return false;
 218                 }
 219                 $expiry = $this->convertToRelative( $expiry );
 220                 try {
 221                         if ( $expiry ) {
 222                                 $conn->multi();
 223                                 $conn->setnx( $key, $this->serialize( $value ) );
 224                                 $conn->expire( $key, $expiry );
 225                                 $result = ( $conn->exec() == array( true, true ) );
 226                         } else {
 227                                 $result = $conn->setnx( $key, $this->serialize( $value ) );
 228                         }
 229                 } catch ( RedisException $e ) {
 230                         $result = false;
 231                         $this->handleException( $server, $conn, $e );
 232                 }
 233
 234                 $this->logRequest( 'add', $key, $server, $result );
 235                 return $result;
 236         }
 237
 238         /**
 239          * Non-atomic implementation of replace(). Could perhaps be done atomically
 240          * with WATCH or scripting, but this function is rarely used.
 241          */
 242         public function replace( $key, $value, $expiry = 0 ) {
 243                 $section = new ProfileSection( __METHOD__ );
 244
 245                 list( $server, $conn ) = $this->getConnection( $key );
 246                 if ( !$conn ) {
 247                         return false;
 248                 }
 249                 if ( !$conn->exists( $key ) ) {
 250                         return false;
 251                 }
 252
 253                 $expiry = $this->convertToRelative( $expiry );
 254                 try {
 255                         if ( !$expiry ) {
 256                                 $result = $conn->set( $key, $this->serialize( $value ) );
 257                         } else {
 258                                 $result = $conn->setex( $key, $expiry, $this->serialize( $value ) );
 259                         }
 260                 } catch ( RedisException $e ) {
 261                         $result = false;
 262                         $this->handleException( $server, $conn, $e );
 263                 }
 264
 265                 $this->logRequest( 'replace', $key, $server, $result );
 266                 return $result;
 267         }
 268
 269         /**
 270          * Non-atomic implementation of incr().
 271          *
 272          * Probably all callers actually want incr() to atomically initialise
 273          * values to zero if they don't exist, as provided by the Redis INCR
 274          * command. But we are constrained by the memcached-like interface to
 275          * return null in that case. Once the key exists, further increments are
 276          * atomic.
 277          */
 278         public function incr( $key, $value = 1 ) {
 279                 $section = new ProfileSection( __METHOD__ );
 280
 281                 list( $server, $conn ) = $this->getConnection( $key );
 282                 if ( !$conn ) {
 283                         return false;
 284                 }
 285                 if ( !$conn->exists( $key ) ) {
 286                         return null;
 287                 }
 288                 try {
 289                         $result = $this->unserialize( $conn->incrBy( $key, $value ) );
 290                 } catch ( RedisException $e ) {
 291                         $result = false;
 292                         $this->handleException( $server, $conn, $e );
 293                 }
 294
 295                 $this->logRequest( 'incr', $key, $server, $result );
 296                 return $result;
 297         }
 298
 299         /**
 300          * @param mixed $data
 301          * @return string
 302          */
 303         protected function serialize( $data ) {
 304                 // Ignore digit strings and ints so INCR/DECR work
 305                 return ( is_int( $data ) || ctype_digit( $data ) ) ? $data : serialize( $data );
 306         }
 307
 308         /**
 309          * @param string $data
 310          * @return mixed
 311          */
 312         protected function unserialize( $data ) {
 313                 // Ignore digit strings and ints so INCR/DECR work
 314                 return ( is_int( $data ) || ctype_digit( $data ) ) ? $data : unserialize( $data );
 315         }
 316
 317         /**
 318          * Get a Redis object with a connection suitable for fetching the specified key
 319          * @return Array (server, RedisConnRef) or (false, false)
 320          */
 321         protected function getConnection( $key ) {
 322                 if ( count( $this->servers ) === 1 ) {
 323                         $candidates = $this->servers;
 324                 } else {
 325                         $candidates = $this->servers;
 326                         ArrayUtils::consistentHashSort( $candidates, $key, '/' );
 327                         if ( !$this->automaticFailover ) {
 328                                 $candidates = array_slice( $candidates, 0, 1 );
 329                         }
 330                 }
 331
 332                 foreach ( $candidates as $server ) {
 333                         $conn = $this->redisPool->getConnection( $server );
 334                         if ( $conn ) {
 335                                 return array( $server, $conn );
 336                         }
 337                 }
 338                 return array( false, false );
 339         }
 340
 341         /**
 342          * Log a fatal error
 343          */
 344         protected function logError( $msg ) {
 345                 wfDebugLog( 'redis', "Redis error: $msg\n" );
 346         }
 347
 348         /**
 349          * The redis extension throws an exception in response to various read, write
 350          * and protocol errors. Sometimes it also closes the connection, sometimes
 351          * not. The safest response for us is to explicitly destroy the connection
 352          * object and let it be reopened during the next request.
 353          */
 354         protected function handleException( $server, RedisConnRef $conn, $e ) {
 355                 $this->redisPool->handleException( $server, $conn, $e );
 356         }
 357
 358         /**
 359          * Send information about a single request to the debug log
 360          */
 361         public function logRequest( $method, $key, $server, $result ) {
 362                 $this->debug( "$method $key on $server: " .
 363                         ( $result === false ? "failure" : "success" ) );
 364         }
 365 }