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' => 'php' );
  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                 wfProfileIn( __METHOD__ );
  76                 list( $server, $conn ) = $this->getConnection( $key );
  77                 if ( !$conn ) {
  78                         wfProfileOut( __METHOD__ );
  79                         return false;
  80                 }
  81                 try {
  82                         $result = $conn->get( $key );
  83                 } catch ( RedisException $e ) {
  84                         $result = false;
  85                         $this->handleException( $server, $conn, $e );
  86                 }
  87                 $casToken = $result;
  88                 $this->logRequest( 'get', $key, $server, $result );
  89                 wfProfileOut( __METHOD__ );
  90                 return $result;
  91         }
  92
  93         public function set( $key, $value, $expiry = 0 ) {
  94                 wfProfileIn( __METHOD__ );
  95                 list( $server, $conn ) = $this->getConnection( $key );
  96                 if ( !$conn ) {
  97                         wfProfileOut( __METHOD__ );
  98                         return false;
  99                 }
 100                 $expiry = $this->convertToRelative( $expiry );
 101                 try {
 102                         if ( !$expiry ) {
 103                                 // No expiry, that is very different from zero expiry in Redis
 104                                 $result = $conn->set( $key, $value );
 105                         } else {
 106                                 $result = $conn->setex( $key, $expiry, $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                 wfProfileOut( __METHOD__ );
 115                 return $result;
 116         }
 117
 118         public function cas( $casToken, $key, $value, $expiry = 0 ) {
 119                 wfProfileIn( __METHOD__ );
 120                 list( $server, $conn ) = $this->getConnection( $key );
 121                 if ( !$conn ) {
 122                         wfProfileOut( __METHOD__ );
 123                         return false;
 124                 }
 125                 $expiry = $this->convertToRelative( $expiry );
 126                 try {
 127                         $conn->watch( $key );
 128
 129                         if ( $this->get( $key ) !== $casToken ) {
 130                                 wfProfileOut( __METHOD__ );
 131                                 return false;
 132                         }
 133
 134                         $conn->multi();
 135
 136                         if ( !$expiry ) {
 137                                 // No expiry, that is very different from zero expiry in Redis
 138                                 $conn->set( $key, $value );
 139                         } else {
 140                                 $conn->setex( $key, $expiry, $value );
 141                         }
 142
 143                         /*
 144                          * multi()/exec() (transactional mode) allows multiple values to
 145                          * be set/get at once and will return an array of results, in
 146                          * the order they were set/get. In this case, we only set 1
 147                          * value, which should (in case of success) result in true.
 148                          */
 149                         $result = ( $conn->exec() == array( true ) );
 150                 } catch ( RedisException $e ) {
 151                         $result = false;
 152                         $this->handleException( $server, $conn, $e );
 153                 }
 154
 155                 $this->logRequest( 'cas', $key, $server, $result );
 156                 wfProfileOut( __METHOD__ );
 157                 return $result;
 158         }
 159
 160         public function delete( $key, $time = 0 ) {
 161                 wfProfileIn( __METHOD__ );
 162                 list( $server, $conn ) = $this->getConnection( $key );
 163                 if ( !$conn ) {
 164                         wfProfileOut( __METHOD__ );
 165                         return false;
 166                 }
 167                 try {
 168                         $conn->delete( $key );
 169                         // Return true even if the key didn't exist
 170                         $result = true;
 171                 } catch ( RedisException $e ) {
 172                         $result = false;
 173                         $this->handleException( $server, $conn, $e );
 174                 }
 175                 $this->logRequest( 'delete', $key, $server, $result );
 176                 wfProfileOut( __METHOD__ );
 177                 return $result;
 178         }
 179
 180         public function getMulti( array $keys ) {
 181                 wfProfileIn( __METHOD__ );
 182                 $batches = array();
 183                 $conns = array();
 184                 foreach ( $keys as $key ) {
 185                         list( $server, $conn ) = $this->getConnection( $key );
 186                         if ( !$conn ) {
 187                                 continue;
 188                         }
 189                         $conns[$server] = $conn;
 190                         $batches[$server][] = $key;
 191                 }
 192                 $result = array();
 193                 foreach ( $batches as $server => $batchKeys ) {
 194                         $conn = $conns[$server];
 195                         try {
 196                                 $conn->multi( Redis::PIPELINE );
 197                                 foreach ( $batchKeys as $key ) {
 198                                         $conn->get( $key );
 199                                 }
 200                                 $batchResult = $conn->exec();
 201                                 if ( $batchResult === false ) {
 202                                         $this->debug( "multi request to $server failed" );
 203                                         continue;
 204                                 }
 205                                 foreach ( $batchResult as $i => $value ) {
 206                                         if ( $value !== false ) {
 207                                                 $result[$batchKeys[$i]] = $value;
 208                                         }
 209                                 }
 210                         } catch ( RedisException $e ) {
 211                                 $this->handleException( $server, $conn, $e );
 212                         }
 213                 }
 214
 215                 $this->debug( "getMulti for " . count( $keys ) . " keys " .
 216                         "returned " . count( $result ) . " results" );
 217                 wfProfileOut( __METHOD__ );
 218                 return $result;
 219         }
 220
 221         public function add( $key, $value, $expiry = 0 ) {
 222                 wfProfileIn( __METHOD__ );
 223                 list( $server, $conn ) = $this->getConnection( $key );
 224                 if ( !$conn ) {
 225                         wfProfileOut( __METHOD__ );
 226                         return false;
 227                 }
 228                 $expiry = $this->convertToRelative( $expiry );
 229                 try {
 230                         $result = $conn->setnx( $key, $value );
 231                         if ( $result && $expiry ) {
 232                                 $conn->expire( $key, $expiry );
 233                         }
 234                 } catch ( RedisException $e ) {
 235                         $result = false;
 236                         $this->handleException( $server, $conn, $e );
 237                 }
 238                 $this->logRequest( 'add', $key, $server, $result );
 239                 wfProfileOut( __METHOD__ );
 240                 return $result;
 241         }
 242
 243         /**
 244          * Non-atomic implementation of replace(). Could perhaps be done atomically
 245          * with WATCH or scripting, but this function is rarely used.
 246          */
 247         public function replace( $key, $value, $expiry = 0 ) {
 248                 wfProfileIn( __METHOD__ );
 249                 list( $server, $conn ) = $this->getConnection( $key );
 250                 if ( !$conn ) {
 251                         wfProfileOut( __METHOD__ );
 252                         return false;
 253                 }
 254                 if ( !$conn->exists( $key ) ) {
 255                         wfProfileOut( __METHOD__ );
 256                         return false;
 257                 }
 258
 259                 $expiry = $this->convertToRelative( $expiry );
 260                 try {
 261                         if ( !$expiry ) {
 262                                 $result = $conn->set( $key, $value );
 263                         } else {
 264                                 $result = $conn->setex( $key, $expiry, $value );
 265                         }
 266                 } catch ( RedisException $e ) {
 267                         $result = false;
 268                         $this->handleException( $server, $conn, $e );
 269                 }
 270
 271                 $this->logRequest( 'replace', $key, $server, $result );
 272                 wfProfileOut( __METHOD__ );
 273                 return $result;
 274         }
 275
 276         /**
 277          * Get a Redis object with a connection suitable for fetching the specified key
 278          * @return Array (server, RedisConnRef) or (false, false)
 279          */
 280         protected function getConnection( $key ) {
 281                 if ( count( $this->servers ) === 1 ) {
 282                         $candidates = $this->servers;
 283                 } else {
 284                         $candidates = $this->servers;
 285                         ArrayUtils::consistentHashSort( $candidates, $key, '/' );
 286                         if ( !$this->automaticFailover ) {
 287                                 $candidates = array_slice( $candidates, 0, 1 );
 288                         }
 289                 }
 290
 291                 foreach ( $candidates as $server ) {
 292                         $conn = $this->redisPool->getConnection( $server );
 293                         if ( $conn ) {
 294                                 return array( $server, $conn );
 295                         }
 296                 }
 297                 return array( false, false );
 298         }
 299
 300         /**
 301          * Log a fatal error
 302          */
 303         protected function logError( $msg ) {
 304                 wfDebugLog( 'redis', "Redis error: $msg\n" );
 305         }
 306
 307         /**
 308          * The redis extension throws an exception in response to various read, write
 309          * and protocol errors. Sometimes it also closes the connection, sometimes
 310          * not. The safest response for us is to explicitly destroy the connection
 311          * object and let it be reopened during the next request.
 312          */
 313         protected function handleException( $server, RedisConnRef $conn, $e ) {
 314                 $this->redisPool->handleException( $server, $conn, $e );
 315         }
 316
 317         /**
 318          * Send information about a single request to the debug log
 319          */
 320         public function logRequest( $method, $key, $server, $result ) {
 321                 $this->debug( "$method $key on $server: " .
 322                         ( $result === false ? "failure" : "success" ) );
 323         }
 324 }