includes/libs/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 /**
  24  * Redis-based caching module for redis server >= 2.6.12
  25  *
  26  * @note Avoid use of Redis::MULTI transactions for twemproxy support
  27  *
  28  * @ingroup Cache
  29  * @ingroup Redis
  30  */
  31 class RedisBagOStuff extends BagOStuff {
  32         /** @var RedisConnectionPool */
  33         protected $redisPool;
  34         /** @var array List of server names */
  35         protected $servers;
  36         /** @var array Map of (tag => server name) */
  37         protected $serverTagMap;
  38         /** @var bool */
  39         protected $automaticFailover;
  40
  41         /**
  42          * Construct a RedisBagOStuff object. Parameters are:
  43          *
  44          *   - servers: An array of server names. A server name may be a hostname,
  45          *     a hostname/port combination or the absolute path of a UNIX socket.
  46          *     If a hostname is specified but no port, the standard port number
  47          *     6379 will be used. Arrays keys can be used to specify the tag to
  48          *     hash on in place of the host/port. Required.
  49          *
  50          *   - connectTimeout: The timeout for new connections, in seconds. Optional,
  51          *     default is 1 second.
  52          *
  53          *   - persistent: Set this to true to allow connections to persist across
  54          *     multiple web requests. False by default.
  55          *
  56          *   - password: The authentication password, will be sent to Redis in
  57          *     clear text. Optional, if it is unspecified, no AUTH command will be
  58          *     sent.
  59          *
  60          *   - automaticFailover: If this is false, then each key will be mapped to
  61          *     a single server, and if that server is down, any requests for that key
  62          *     will fail. If this is true, a connection failure will cause the client
  63          *     to immediately try the next server in the list (as determined by a
  64          *     consistent hashing algorithm). True by default. This has the
  65          *     potential to create consistency issues if a server is slow enough to
  66          *     flap, for example if it is in swap death.
  67          * @param array $params
  68          */
  69         function __construct( $params ) {
  70                 parent::__construct( $params );
  71                 $redisConf = [ 'serializer' => 'none' ]; // manage that in this class
  72                 foreach ( [ 'connectTimeout', 'persistent', 'password' ] as $opt ) {
  73                         if ( isset( $params[$opt] ) ) {
  74                                 $redisConf[$opt] = $params[$opt];
  75                         }
  76                 }
  77                 $this->redisPool = RedisConnectionPool::singleton( $redisConf );
  78
  79                 $this->servers = $params['servers'];
  80                 foreach ( $this->servers as $key => $server ) {
  81                         $this->serverTagMap[is_int( $key ) ? $server : $key] = $server;
  82                 }
  83
  84                 $this->automaticFailover = $params['automaticFailover'] ?? true;
  85
  86                 $this->attrMap[self::ATTR_SYNCWRITES] = self::QOS_SYNCWRITES_NONE;
  87         }
  88
  89         protected function doGet( $key, $flags = 0, &$casToken = null ) {
  90                 $casToken = null;
  91
  92                 list( $server, $conn ) = $this->getConnection( $key );
  93                 if ( !$conn ) {
  94                         return false;
  95                 }
  96                 try {
  97                         $value = $conn->get( $key );
  98                         $casToken = $value;
  99                         $result = $this->unserialize( $value );
 100                 } catch ( RedisException $e ) {
 101                         $result = false;
 102                         $this->handleException( $conn, $e );
 103                 }
 104
 105                 $this->logRequest( 'get', $key, $server, $result );
 106                 return $result;
 107         }
 108
 109         public function set( $key, $value, $expiry = 0, $flags = 0 ) {
 110                 list( $server, $conn ) = $this->getConnection( $key );
 111                 if ( !$conn ) {
 112                         return false;
 113                 }
 114                 $expiry = $this->convertToRelative( $expiry );
 115                 try {
 116                         if ( $expiry ) {
 117                                 $result = $conn->setex( $key, $expiry, $this->serialize( $value ) );
 118                         } else {
 119                                 // No expiry, that is very different from zero expiry in Redis
 120                                 $result = $conn->set( $key, $this->serialize( $value ) );
 121                         }
 122                 } catch ( RedisException $e ) {
 123                         $result = false;
 124                         $this->handleException( $conn, $e );
 125                 }
 126
 127                 $this->logRequest( 'set', $key, $server, $result );
 128                 return $result;
 129         }
 130
 131         public function delete( $key, $flags = 0 ) {
 132                 list( $server, $conn ) = $this->getConnection( $key );
 133                 if ( !$conn ) {
 134                         return false;
 135                 }
 136                 try {
 137                         $conn->delete( $key );
 138                         // Return true even if the key didn't exist
 139                         $result = true;
 140                 } catch ( RedisException $e ) {
 141                         $result = false;
 142                         $this->handleException( $conn, $e );
 143                 }
 144
 145                 $this->logRequest( 'delete', $key, $server, $result );
 146                 return $result;
 147         }
 148
 149         public function getMulti( array $keys, $flags = 0 ) {
 150                 $batches = [];
 151                 $conns = [];
 152                 foreach ( $keys as $key ) {
 153                         list( $server, $conn ) = $this->getConnection( $key );
 154                         if ( !$conn ) {
 155                                 continue;
 156                         }
 157                         $conns[$server] = $conn;
 158                         $batches[$server][] = $key;
 159                 }
 160                 $result = [];
 161                 foreach ( $batches as $server => $batchKeys ) {
 162                         $conn = $conns[$server];
 163                         try {
 164                                 $conn->multi( Redis::PIPELINE );
 165                                 foreach ( $batchKeys as $key ) {
 166                                         $conn->get( $key );
 167                                 }
 168                                 $batchResult = $conn->exec();
 169                                 if ( $batchResult === false ) {
 170                                         $this->debug( "multi request to $server failed" );
 171                                         continue;
 172                                 }
 173                                 foreach ( $batchResult as $i => $value ) {
 174                                         if ( $value !== false ) {
 175                                                 $result[$batchKeys[$i]] = $this->unserialize( $value );
 176                                         }
 177                                 }
 178                         } catch ( RedisException $e ) {
 179                                 $this->handleException( $conn, $e );
 180                         }
 181                 }
 182
 183                 $this->debug( "getMulti for " . count( $keys ) . " keys " .
 184                         "returned " . count( $result ) . " results" );
 185                 return $result;
 186         }
 187
 188         public function setMulti( array $data, $expiry = 0, $flags = 0 ) {
 189                 $batches = [];
 190                 $conns = [];
 191                 foreach ( $data as $key => $value ) {
 192                         list( $server, $conn ) = $this->getConnection( $key );
 193                         if ( !$conn ) {
 194                                 continue;
 195                         }
 196                         $conns[$server] = $conn;
 197                         $batches[$server][] = $key;
 198                 }
 199
 200                 $expiry = $this->convertToRelative( $expiry );
 201                 $result = true;
 202                 foreach ( $batches as $server => $batchKeys ) {
 203                         $conn = $conns[$server];
 204                         try {
 205                                 $conn->multi( Redis::PIPELINE );
 206                                 foreach ( $batchKeys as $key ) {
 207                                         if ( $expiry ) {
 208                                                 $conn->setex( $key, $expiry, $this->serialize( $data[$key] ) );
 209                                         } else {
 210                                                 $conn->set( $key, $this->serialize( $data[$key] ) );
 211                                         }
 212                                 }
 213                                 $batchResult = $conn->exec();
 214                                 if ( $batchResult === false ) {
 215                                         $this->debug( "setMulti request to $server failed" );
 216                                         continue;
 217                                 }
 218                                 foreach ( $batchResult as $value ) {
 219                                         if ( $value === false ) {
 220                                                 $result = false;
 221                                         }
 222                                 }
 223                         } catch ( RedisException $e ) {
 224                                 $this->handleException( $conn, $e );
 225                                 $result = false;
 226                         }
 227                 }
 228
 229                 return $result;
 230         }
 231
 232         public function deleteMulti( array $keys, $flags = 0 ) {
 233                 $batches = [];
 234                 $conns = [];
 235                 foreach ( $keys as $key ) {
 236                         list( $server, $conn ) = $this->getConnection( $key );
 237                         if ( !$conn ) {
 238                                 continue;
 239                         }
 240                         $conns[$server] = $conn;
 241                         $batches[$server][] = $key;
 242                 }
 243
 244                 $result = true;
 245                 foreach ( $batches as $server => $batchKeys ) {
 246                         $conn = $conns[$server];
 247                         try {
 248                                 $conn->multi( Redis::PIPELINE );
 249                                 foreach ( $batchKeys as $key ) {
 250                                         $conn->delete( $key );
 251                                 }
 252                                 $batchResult = $conn->exec();
 253                                 if ( $batchResult === false ) {
 254                                         $this->debug( "deleteMulti request to $server failed" );
 255                                         continue;
 256                                 }
 257                                 foreach ( $batchResult as $value ) {
 258                                         if ( $value === false ) {
 259                                                 $result = false;
 260                                         }
 261                                 }
 262                         } catch ( RedisException $e ) {
 263                                 $this->handleException( $conn, $e );
 264                                 $result = false;
 265                         }
 266                 }
 267
 268                 return $result;
 269         }
 270
 271         public function add( $key, $value, $expiry = 0, $flags = 0 ) {
 272                 list( $server, $conn ) = $this->getConnection( $key );
 273                 if ( !$conn ) {
 274                         return false;
 275                 }
 276                 $expiry = $this->convertToRelative( $expiry );
 277                 try {
 278                         if ( $expiry ) {
 279                                 $result = $conn->set(
 280                                         $key,
 281                                         $this->serialize( $value ),
 282                                         [ 'nx', 'ex' => $expiry ]
 283                                 );
 284                         } else {
 285                                 $result = $conn->setnx( $key, $this->serialize( $value ) );
 286                         }
 287                 } catch ( RedisException $e ) {
 288                         $result = false;
 289                         $this->handleException( $conn, $e );
 290                 }
 291
 292                 $this->logRequest( 'add', $key, $server, $result );
 293                 return $result;
 294         }
 295
 296         /**
 297          * Non-atomic implementation of incr().
 298          *
 299          * Probably all callers actually want incr() to atomically initialise
 300          * values to zero if they don't exist, as provided by the Redis INCR
 301          * command. But we are constrained by the memcached-like interface to
 302          * return null in that case. Once the key exists, further increments are
 303          * atomic.
 304          * @param string $key Key to increase
 305          * @param int $value Value to add to $key (Default 1)
 306          * @return int|bool New value or false on failure
 307          */
 308         public function incr( $key, $value = 1 ) {
 309                 list( $server, $conn ) = $this->getConnection( $key );
 310                 if ( !$conn ) {
 311                         return false;
 312                 }
 313                 try {
 314                         if ( !$conn->exists( $key ) ) {
 315                                 return false;
 316                         }
 317                         // @FIXME: on races, the key may have a 0 TTL
 318                         $result = $conn->incrBy( $key, $value );
 319                 } catch ( RedisException $e ) {
 320                         $result = false;
 321                         $this->handleException( $conn, $e );
 322                 }
 323
 324                 $this->logRequest( 'incr', $key, $server, $result );
 325                 return $result;
 326         }
 327
 328         public function changeTTL( $key, $exptime = 0, $flags = 0 ) {
 329                 list( $server, $conn ) = $this->getConnection( $key );
 330                 if ( !$conn ) {
 331                         return false;
 332                 }
 333
 334                 $relative = $this->expiryIsRelative( $exptime );
 335                 try {
 336                         if ( $exptime == 0 ) {
 337                                 $result = $conn->persist( $key );
 338                                 $this->logRequest( 'persist', $key, $server, $result );
 339                         } elseif ( $relative ) {
 340                                 $result = $conn->expire( $key, $this->convertToRelative( $exptime ) );
 341                                 $this->logRequest( 'expire', $key, $server, $result );
 342                         } else {
 343                                 $result = $conn->expireAt( $key, $this->convertToExpiry( $exptime ) );
 344                                 $this->logRequest( 'expireAt', $key, $server, $result );
 345                         }
 346                 } catch ( RedisException $e ) {
 347                         $result = false;
 348                         $this->handleException( $conn, $e );
 349                 }
 350
 351                 return $result;
 352         }
 353
 354         /**
 355          * @param mixed $data
 356          * @return string
 357          */
 358         protected function serialize( $data ) {
 359                 // Serialize anything but integers so INCR/DECR work
 360                 // Do not store integer-like strings as integers to avoid type confusion (T62563)
 361                 return is_int( $data ) ? $data : serialize( $data );
 362         }
 363
 364         /**
 365          * @param string $data
 366          * @return mixed
 367          */
 368         protected function unserialize( $data ) {
 369                 $int = intval( $data );
 370                 return $data === (string)$int ? $int : unserialize( $data );
 371         }
 372
 373         /**
 374          * Get a Redis object with a connection suitable for fetching the specified key
 375          * @param string $key
 376          * @return array (server, RedisConnRef) or (false, false)
 377          */
 378         protected function getConnection( $key ) {
 379                 $candidates = array_keys( $this->serverTagMap );
 380
 381                 if ( count( $this->servers ) > 1 ) {
 382                         ArrayUtils::consistentHashSort( $candidates, $key, '/' );
 383                         if ( !$this->automaticFailover ) {
 384                                 $candidates = array_slice( $candidates, 0, 1 );
 385                         }
 386                 }
 387
 388                 while ( ( $tag = array_shift( $candidates ) ) !== null ) {
 389                         $server = $this->serverTagMap[$tag];
 390                         $conn = $this->redisPool->getConnection( $server, $this->logger );
 391                         if ( !$conn ) {
 392                                 continue;
 393                         }
 394
 395                         // If automatic failover is enabled, check that the server's link
 396                         // to its master (if any) is up -- but only if there are other
 397                         // viable candidates left to consider. Also, getMasterLinkStatus()
 398                         // does not work with twemproxy, though $candidates will be empty
 399                         // by now in such cases.
 400                         if ( $this->automaticFailover && $candidates ) {
 401                                 try {
 402                                         if ( $this->getMasterLinkStatus( $conn ) === 'down' ) {
 403                                                 // If the master cannot be reached, fail-over to the next server.
 404                                                 // If masters are in data-center A, and replica DBs in data-center B,
 405                                                 // this helps avoid the case were fail-over happens in A but not
 406                                                 // to the corresponding server in B (e.g. read/write mismatch).
 407                                                 continue;
 408                                         }
 409                                 } catch ( RedisException $e ) {
 410                                         // Server is not accepting commands
 411                                         $this->handleException( $conn, $e );
 412                                         continue;
 413                                 }
 414                         }
 415
 416                         return [ $server, $conn ];
 417                 }
 418
 419                 $this->setLastError( BagOStuff::ERR_UNREACHABLE );
 420
 421                 return [ false, false ];
 422         }
 423
 424         /**
 425          * Check the master link status of a Redis server that is configured as a replica DB.
 426          * @param RedisConnRef $conn
 427          * @return string|null Master link status (either 'up' or 'down'), or null
 428          *  if the server is not a replica DB.
 429          */
 430         protected function getMasterLinkStatus( RedisConnRef $conn ) {
 431                 $info = $conn->info();
 432                 return $info['master_link_status'] ?? null;
 433         }
 434
 435         /**
 436          * Log a fatal error
 437          * @param string $msg
 438          */
 439         protected function logError( $msg ) {
 440                 $this->logger->error( "Redis error: $msg" );
 441         }
 442
 443         /**
 444          * The redis extension throws an exception in response to various read, write
 445          * and protocol errors. Sometimes it also closes the connection, sometimes
 446          * not. The safest response for us is to explicitly destroy the connection
 447          * object and let it be reopened during the next request.
 448          * @param RedisConnRef $conn
 449          * @param Exception $e
 450          */
 451         protected function handleException( RedisConnRef $conn, $e ) {
 452                 $this->setLastError( BagOStuff::ERR_UNEXPECTED );
 453                 $this->redisPool->handleError( $conn, $e );
 454         }
 455
 456         /**
 457          * Send information about a single request to the debug log
 458          * @param string $method
 459          * @param string $key
 460          * @param string $server
 461          * @param bool $result
 462          */
 463         public function logRequest( $method, $key, $server, $result ) {
 464                 $this->debug( "$method $key on $server: " .
 465                         ( $result === false ? "failure" : "success" ) );
 466         }
 467 }