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                 $section = new ProfileSection( __METHOD__ );
  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                 $section = new ProfileSection( __METHOD__ );
  97
  98                 list( $server, $conn ) = $this->getConnection( $key );
  99                 if ( !$conn ) {
 100                         return false;
 101                 }
 102                 $expiry = $this->convertToRelative( $expiry );
 103                 try {
 104                         if ( $expiry ) {
 105                                 $result = $conn->setex( $key, $expiry, $this->serialize( $value ) );
 106                         } else {
 107                                 // No expiry, that is very different from zero expiry in Redis
 108                                 $result = $conn->set( $key, $this->serialize( $value ) );
 109                         }
 110                 } catch ( RedisException $e ) {
 111                         $result = false;
 112                         $this->handleException( $conn, $e );
 113                 }
 114
 115                 $this->logRequest( 'set', $key, $server, $result );
 116                 return $result;
 117         }
 118
 119         public function cas( $casToken, $key, $value, $expiry = 0 ) {
 120                 $section = new ProfileSection( __METHOD__ );
 121
 122                 list( $server, $conn ) = $this->getConnection( $key );
 123                 if ( !$conn ) {
 124                         return false;
 125                 }
 126                 $expiry = $this->convertToRelative( $expiry );
 127                 try {
 128                         $conn->watch( $key );
 129
 130                         if ( $this->serialize( $this->get( $key ) ) !== $casToken ) {
 131                                 $conn->unwatch();
 132                                 return false;
 133                         }
 134
 135                         // multi()/exec() will fail atomically if the key changed since watch()
 136                         $conn->multi();
 137                         if ( $expiry ) {
 138                                 $conn->setex( $key, $expiry, $this->serialize( $value ) );
 139                         } else {
 140                                 // No expiry, that is very different from zero expiry in Redis
 141                                 $conn->set( $key, $this->serialize( $value ) );
 142                         }
 143                         $result = ( $conn->exec() == array( true ) );
 144                 } catch ( RedisException $e ) {
 145                         $result = false;
 146                         $this->handleException( $conn, $e );
 147                 }
 148
 149                 $this->logRequest( 'cas', $key, $server, $result );
 150                 return $result;
 151         }
 152
 153         public function delete( $key, $time = 0 ) {
 154                 $section = new ProfileSection( __METHOD__ );
 155
 156                 list( $server, $conn ) = $this->getConnection( $key );
 157                 if ( !$conn ) {
 158                         return false;
 159                 }
 160                 try {
 161                         $conn->delete( $key );
 162                         // Return true even if the key didn't exist
 163                         $result = true;
 164                 } catch ( RedisException $e ) {
 165                         $result = false;
 166                         $this->handleException( $conn, $e );
 167                 }
 168
 169                 $this->logRequest( 'delete', $key, $server, $result );
 170                 return $result;
 171         }
 172
 173         public function getMulti( array $keys ) {
 174                 $section = new ProfileSection( __METHOD__ );
 175
 176                 $batches = array();
 177                 $conns = array();
 178                 foreach ( $keys as $key ) {
 179                         list( $server, $conn ) = $this->getConnection( $key );
 180                         if ( !$conn ) {
 181                                 continue;
 182                         }
 183                         $conns[$server] = $conn;
 184                         $batches[$server][] = $key;
 185                 }
 186                 $result = array();
 187                 foreach ( $batches as $server => $batchKeys ) {
 188                         $conn = $conns[$server];
 189                         try {
 190                                 $conn->multi( Redis::PIPELINE );
 191                                 foreach ( $batchKeys as $key ) {
 192                                         $conn->get( $key );
 193                                 }
 194                                 $batchResult = $conn->exec();
 195                                 if ( $batchResult === false ) {
 196                                         $this->debug( "multi request to $server failed" );
 197                                         continue;
 198                                 }
 199                                 foreach ( $batchResult as $i => $value ) {
 200                                         if ( $value !== false ) {
 201                                                 $result[$batchKeys[$i]] = $this->unserialize( $value );
 202                                         }
 203                                 }
 204                         } catch ( RedisException $e ) {
 205                                 $this->handleException( $conn, $e );
 206                         }
 207                 }
 208
 209                 $this->debug( "getMulti for " . count( $keys ) . " keys " .
 210                         "returned " . count( $result ) . " results" );
 211                 return $result;
 212         }
 213
 214         /**
 215          * @param array $data
 216          * @param int $expiry
 217          * @return bool
 218          */
 219         public function setMulti( array $data, $expiry = 0 ) {
 220                 $section = new ProfileSection( __METHOD__ );
 221
 222                 $batches = array();
 223                 $conns = array();
 224                 foreach ( $data as $key => $value ) {
 225                         list( $server, $conn ) = $this->getConnection( $key );
 226                         if ( !$conn ) {
 227                                 continue;
 228                         }
 229                         $conns[$server] = $conn;
 230                         $batches[$server][] = $key;
 231                 }
 232
 233                 $expiry = $this->convertToRelative( $expiry );
 234                 $result = true;
 235                 foreach ( $batches as $server => $batchKeys ) {
 236                         $conn = $conns[$server];
 237                         try {
 238                                 $conn->multi( Redis::PIPELINE );
 239                                 foreach ( $batchKeys as $key ) {
 240                                         if ( $expiry ) {
 241                                                 $conn->setex( $key, $expiry, $this->serialize( $data[$key] ) );
 242                                         } else {
 243                                                 $conn->set( $key, $this->serialize( $data[$key] ) );
 244                                         }
 245                                 }
 246                                 $batchResult = $conn->exec();
 247                                 if ( $batchResult === false ) {
 248                                         $this->debug( "setMulti request to $server failed" );
 249                                         continue;
 250                                 }
 251                                 foreach ( $batchResult as $value ) {
 252                                         if ( $value === false ) {
 253                                                 $result = false;
 254                                         }
 255                                 }
 256                         } catch ( RedisException $e ) {
 257                                 $this->handleException( $server, $conn, $e );
 258                                 $result = false;
 259                         }
 260                 }
 261
 262                 return $result;
 263         }
 264
 265
 266
 267         public function add( $key, $value, $expiry = 0 ) {
 268                 $section = new ProfileSection( __METHOD__ );
 269
 270                 list( $server, $conn ) = $this->getConnection( $key );
 271                 if ( !$conn ) {
 272                         return false;
 273                 }
 274                 $expiry = $this->convertToRelative( $expiry );
 275                 try {
 276                         if ( $expiry ) {
 277                                 $conn->multi();
 278                                 $conn->setnx( $key, $this->serialize( $value ) );
 279                                 $conn->expire( $key, $expiry );
 280                                 $result = ( $conn->exec() == array( true, true ) );
 281                         } else {
 282                                 $result = $conn->setnx( $key, $this->serialize( $value ) );
 283                         }
 284                 } catch ( RedisException $e ) {
 285                         $result = false;
 286                         $this->handleException( $conn, $e );
 287                 }
 288
 289                 $this->logRequest( 'add', $key, $server, $result );
 290                 return $result;
 291         }
 292
 293         /**
 294          * Non-atomic implementation of incr().
 295          *
 296          * Probably all callers actually want incr() to atomically initialise
 297          * values to zero if they don't exist, as provided by the Redis INCR
 298          * command. But we are constrained by the memcached-like interface to
 299          * return null in that case. Once the key exists, further increments are
 300          * atomic.
 301          * @param string $key Key to increase
 302          * @param int $value Value to add to $key (Default 1)
 303          * @return int|bool New value or false on failure
 304          */
 305         public function incr( $key, $value = 1 ) {
 306                 $section = new ProfileSection( __METHOD__ );
 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          * @param mixed $data
 327          * @return string
 328          */
 329         protected function serialize( $data ) {
 330                 // Serialize anything but integers so INCR/DECR work
 331                 // Do not store integer-like strings as integers to avoid type confusion (bug 60563)
 332                 return is_int( $data ) ? $data : serialize( $data );
 333         }
 334
 335         /**
 336          * @param string $data
 337          * @return mixed
 338          */
 339         protected function unserialize( $data ) {
 340                 return ctype_digit( $data ) ? intval( $data ) : unserialize( $data );
 341         }
 342
 343         /**
 344          * Get a Redis object with a connection suitable for fetching the specified key
 345          * @param string $key
 346          * @return array (server, RedisConnRef) or (false, false)
 347          */
 348         protected function getConnection( $key ) {
 349                 if ( count( $this->servers ) === 1 ) {
 350                         $candidates = $this->servers;
 351                 } else {
 352                         $candidates = $this->servers;
 353                         ArrayUtils::consistentHashSort( $candidates, $key, '/' );
 354                         if ( !$this->automaticFailover ) {
 355                                 $candidates = array_slice( $candidates, 0, 1 );
 356                         }
 357                 }
 358
 359                 foreach ( $candidates as $server ) {
 360                         $conn = $this->redisPool->getConnection( $server );
 361                         if ( $conn ) {
 362                                 return array( $server, $conn );
 363                         }
 364                 }
 365                 $this->setLastError( BagOStuff::ERR_UNREACHABLE );
 366                 return array( false, false );
 367         }
 368
 369         /**
 370          * Log a fatal error
 371          * @param string $msg
 372          */
 373         protected function logError( $msg ) {
 374                 wfDebugLog( 'redis', "Redis error: $msg" );
 375         }
 376
 377         /**
 378          * The redis extension throws an exception in response to various read, write
 379          * and protocol errors. Sometimes it also closes the connection, sometimes
 380          * not. The safest response for us is to explicitly destroy the connection
 381          * object and let it be reopened during the next request.
 382          * @param RedisConnRef $conn
 383          * @param Exception $e
 384          */
 385         protected function handleException( RedisConnRef $conn, $e ) {
 386                 $this->setLastError( BagOStuff::ERR_UNEXPECTED );
 387                 $this->redisPool->handleError( $conn, $e );
 388         }
 389
 390         /**
 391          * Send information about a single request to the debug log
 392          * @param string $method
 393          * @param string $key
 394          * @param string $server
 395          * @param bool $result
 396          */
 397         public function logRequest( $method, $key, $server, $result ) {
 398                 $this->debug( "$method $key on $server: " .
 399                         ( $result === false ? "failure" : "success" ) );
 400         }
 401 }