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         protected function doSet( $key, $value, $exptime = 0, $flags = 0 ) {
 110                 list( $server, $conn ) = $this->getConnection( $key );
 111                 if ( !$conn ) {
 112                         return false;
 113                 }
 114                 $ttl = $this->convertToRelative( $exptime );
 115                 try {
 116                         if ( $ttl ) {
 117                                 $result = $conn->setex( $key, $ttl, $this->serialize( $value ) );
 118                         } else {
 119                                 $result = $conn->set( $key, $this->serialize( $value ) );
 120                         }
 121                 } catch ( RedisException $e ) {
 122                         $result = false;
 123                         $this->handleException( $conn, $e );
 124                 }
 125
 126                 $this->logRequest( 'set', $key, $server, $result );
 127                 return $result;
 128         }
 129
 130         protected function doDelete( $key, $flags = 0 ) {
 131                 list( $server, $conn ) = $this->getConnection( $key );
 132                 if ( !$conn ) {
 133                         return false;
 134                 }
 135                 try {
 136                         $conn->delete( $key );
 137                         // Return true even if the key didn't exist
 138                         $result = true;
 139                 } catch ( RedisException $e ) {
 140                         $result = false;
 141                         $this->handleException( $conn, $e );
 142                 }
 143
 144                 $this->logRequest( 'delete', $key, $server, $result );
 145                 return $result;
 146         }
 147
 148         protected function doGetMulti( array $keys, $flags = 0 ) {
 149                 $batches = [];
 150                 $conns = [];
 151                 foreach ( $keys as $key ) {
 152                         list( $server, $conn ) = $this->getConnection( $key );
 153                         if ( !$conn ) {
 154                                 continue;
 155                         }
 156                         $conns[$server] = $conn;
 157                         $batches[$server][] = $key;
 158                 }
 159                 $result = [];
 160                 foreach ( $batches as $server => $batchKeys ) {
 161                         $conn = $conns[$server];
 162                         try {
 163                                 $conn->multi( Redis::PIPELINE );
 164                                 foreach ( $batchKeys as $key ) {
 165                                         $conn->get( $key );
 166                                 }
 167                                 $batchResult = $conn->exec();
 168                                 if ( $batchResult === false ) {
 169                                         $this->debug( "multi request to $server failed" );
 170                                         continue;
 171                                 }
 172                                 foreach ( $batchResult as $i => $value ) {
 173                                         if ( $value !== false ) {
 174                                                 $result[$batchKeys[$i]] = $this->unserialize( $value );
 175                                         }
 176                                 }
 177                         } catch ( RedisException $e ) {
 178                                 $this->handleException( $conn, $e );
 179                         }
 180                 }
 181
 182                 $this->debug( "getMulti for " . count( $keys ) . " keys " .
 183                         "returned " . count( $result ) . " results" );
 184                 return $result;
 185         }
 186
 187         protected function doSetMulti( array $data, $expiry = 0, $flags = 0 ) {
 188                 $batches = [];
 189                 $conns = [];
 190                 foreach ( $data as $key => $value ) {
 191                         list( $server, $conn ) = $this->getConnection( $key );
 192                         if ( !$conn ) {
 193                                 continue;
 194                         }
 195                         $conns[$server] = $conn;
 196                         $batches[$server][] = $key;
 197                 }
 198
 199                 $expiry = $this->convertToRelative( $expiry );
 200                 $result = true;
 201                 foreach ( $batches as $server => $batchKeys ) {
 202                         $conn = $conns[$server];
 203                         try {
 204                                 $conn->multi( Redis::PIPELINE );
 205                                 foreach ( $batchKeys as $key ) {
 206                                         if ( $expiry ) {
 207                                                 $conn->setex( $key, $expiry, $this->serialize( $data[$key] ) );
 208                                         } else {
 209                                                 $conn->set( $key, $this->serialize( $data[$key] ) );
 210                                         }
 211                                 }
 212                                 $batchResult = $conn->exec();
 213                                 if ( $batchResult === false ) {
 214                                         $this->debug( "setMulti request to $server failed" );
 215                                         continue;
 216                                 }
 217                                 $result = $result && !in_array( false, $batchResult, true );
 218                         } catch ( RedisException $e ) {
 219                                 $this->handleException( $conn, $e );
 220                                 $result = false;
 221                         }
 222                 }
 223
 224                 return $result;
 225         }
 226
 227         protected function doDeleteMulti( array $keys, $flags = 0 ) {
 228                 $batches = [];
 229                 $conns = [];
 230                 foreach ( $keys as $key ) {
 231                         list( $server, $conn ) = $this->getConnection( $key );
 232                         if ( !$conn ) {
 233                                 continue;
 234                         }
 235                         $conns[$server] = $conn;
 236                         $batches[$server][] = $key;
 237                 }
 238
 239                 $result = true;
 240                 foreach ( $batches as $server => $batchKeys ) {
 241                         $conn = $conns[$server];
 242                         try {
 243                                 $conn->multi( Redis::PIPELINE );
 244                                 foreach ( $batchKeys as $key ) {
 245                                         $conn->delete( $key );
 246                                 }
 247                                 $batchResult = $conn->exec();
 248                                 if ( $batchResult === false ) {
 249                                         $this->debug( "deleteMulti request to $server failed" );
 250                                         continue;
 251                                 }
 252                                 $result = $result && !in_array( false, $batchResult, true );
 253                         } catch ( RedisException $e ) {
 254                                 $this->handleException( $conn, $e );
 255                                 $result = false;
 256                         }
 257                 }
 258
 259                 return $result;
 260         }
 261
 262         public function add( $key, $value, $expiry = 0, $flags = 0 ) {
 263                 list( $server, $conn ) = $this->getConnection( $key );
 264                 if ( !$conn ) {
 265                         return false;
 266                 }
 267
 268                 $ttl = $this->convertToRelative( $expiry );
 269                 try {
 270                         $result = $conn->set(
 271                                 $key,
 272                                 $this->serialize( $value ),
 273                                 $ttl ? [ 'nx', 'ex' => $ttl ] : [ 'nx' ]
 274                         );
 275                 } catch ( RedisException $e ) {
 276                         $result = false;
 277                         $this->handleException( $conn, $e );
 278                 }
 279
 280                 $this->logRequest( 'add', $key, $server, $result );
 281
 282                 return $result;
 283         }
 284
 285         public function incr( $key, $value = 1 ) {
 286                 list( $server, $conn ) = $this->getConnection( $key );
 287                 if ( !$conn ) {
 288                         return false;
 289                 }
 290
 291                 try {
 292                         $conn->watch( $key );
 293                         if ( $conn->exists( $key ) ) {
 294                                 $conn->multi( Redis::MULTI );
 295                                 $conn->incrBy( $key, $value );
 296                                 $batchResult = $conn->exec();
 297                                 if ( $batchResult === false ) {
 298                                         $result = false;
 299                                 } else {
 300                                         $result = end( $batchResult );
 301                                 }
 302                         } else {
 303                                 $result = false;
 304                                 $conn->unwatch();
 305                         }
 306                 } catch ( RedisException $e ) {
 307                         try {
 308                                 $conn->unwatch(); // sanity
 309                         } catch ( RedisException $ex ) {
 310                                 // already errored
 311                         }
 312                         $result = false;
 313                         $this->handleException( $conn, $e );
 314                 }
 315
 316                 $this->logRequest( 'incr', $key, $server, $result );
 317
 318                 return $result;
 319         }
 320
 321         public function incrWithInit( $key, $exptime, $value = 1, $init = 1 ) {
 322                 list( $server, $conn ) = $this->getConnection( $key );
 323                 if ( !$conn ) {
 324                         return false;
 325                 }
 326
 327                 $ttl = $this->convertToRelative( $exptime );
 328                 $preIncrInit = $init - $value;
 329                 try {
 330                         $conn->multi( Redis::MULTI );
 331                         $conn->set( $key, $preIncrInit, $ttl ? [ 'nx', 'ex' => $ttl ] : [ 'nx' ] );
 332                         $conn->incrBy( $key, $value );
 333                         $batchResult = $conn->exec();
 334                         if ( $batchResult === false ) {
 335                                 $result = false;
 336                                 $this->debug( "incrWithInit request to $server failed" );
 337                         } else {
 338                                 $result = end( $batchResult );
 339                         }
 340                 } catch ( RedisException $e ) {
 341                         $result = false;
 342                         $this->handleException( $conn, $e );
 343                 }
 344
 345                 $this->logRequest( 'incr', $key, $server, $result );
 346
 347                 return $result;
 348         }
 349
 350         protected function doChangeTTL( $key, $exptime, $flags ) {
 351                 list( $server, $conn ) = $this->getConnection( $key );
 352                 if ( !$conn ) {
 353                         return false;
 354                 }
 355
 356                 $relative = $this->expiryIsRelative( $exptime );
 357                 try {
 358                         if ( $exptime == 0 ) {
 359                                 $result = $conn->persist( $key );
 360                                 $this->logRequest( 'persist', $key, $server, $result );
 361                         } elseif ( $relative ) {
 362                                 $result = $conn->expire( $key, $this->convertToRelative( $exptime ) );
 363                                 $this->logRequest( 'expire', $key, $server, $result );
 364                         } else {
 365                                 $result = $conn->expireAt( $key, $this->convertToExpiry( $exptime ) );
 366                                 $this->logRequest( 'expireAt', $key, $server, $result );
 367                         }
 368                 } catch ( RedisException $e ) {
 369                         $result = false;
 370                         $this->handleException( $conn, $e );
 371                 }
 372
 373                 return $result;
 374         }
 375
 376         /**
 377          * Get a Redis object with a connection suitable for fetching the specified key
 378          * @param string $key
 379          * @return array (server, RedisConnRef) or (false, false)
 380          */
 381         protected function getConnection( $key ) {
 382                 $candidates = array_keys( $this->serverTagMap );
 383
 384                 if ( count( $this->servers ) > 1 ) {
 385                         ArrayUtils::consistentHashSort( $candidates, $key, '/' );
 386                         if ( !$this->automaticFailover ) {
 387                                 $candidates = array_slice( $candidates, 0, 1 );
 388                         }
 389                 }
 390
 391                 while ( ( $tag = array_shift( $candidates ) ) !== null ) {
 392                         $server = $this->serverTagMap[$tag];
 393                         $conn = $this->redisPool->getConnection( $server, $this->logger );
 394                         if ( !$conn ) {
 395                                 continue;
 396                         }
 397
 398                         // If automatic failover is enabled, check that the server's link
 399                         // to its master (if any) is up -- but only if there are other
 400                         // viable candidates left to consider. Also, getMasterLinkStatus()
 401                         // does not work with twemproxy, though $candidates will be empty
 402                         // by now in such cases.
 403                         if ( $this->automaticFailover && $candidates ) {
 404                                 try {
 405                                         if ( $this->getMasterLinkStatus( $conn ) === 'down' ) {
 406                                                 // If the master cannot be reached, fail-over to the next server.
 407                                                 // If masters are in data-center A, and replica DBs in data-center B,
 408                                                 // this helps avoid the case were fail-over happens in A but not
 409                                                 // to the corresponding server in B (e.g. read/write mismatch).
 410                                                 continue;
 411                                         }
 412                                 } catch ( RedisException $e ) {
 413                                         // Server is not accepting commands
 414                                         $this->handleException( $conn, $e );
 415                                         continue;
 416                                 }
 417                         }
 418
 419                         return [ $server, $conn ];
 420                 }
 421
 422                 $this->setLastError( BagOStuff::ERR_UNREACHABLE );
 423
 424                 return [ false, false ];
 425         }
 426
 427         /**
 428          * Check the master link status of a Redis server that is configured as a replica DB.
 429          * @param RedisConnRef $conn
 430          * @return string|null Master link status (either 'up' or 'down'), or null
 431          *  if the server is not a replica DB.
 432          */
 433         protected function getMasterLinkStatus( RedisConnRef $conn ) {
 434                 $info = $conn->info();
 435                 return $info['master_link_status'] ?? null;
 436         }
 437
 438         /**
 439          * Log a fatal error
 440          * @param string $msg
 441          */
 442         protected function logError( $msg ) {
 443                 $this->logger->error( "Redis error: $msg" );
 444         }
 445
 446         /**
 447          * The redis extension throws an exception in response to various read, write
 448          * and protocol errors. Sometimes it also closes the connection, sometimes
 449          * not. The safest response for us is to explicitly destroy the connection
 450          * object and let it be reopened during the next request.
 451          * @param RedisConnRef $conn
 452          * @param RedisException $e
 453          */
 454         protected function handleException( RedisConnRef $conn, $e ) {
 455                 $this->setLastError( BagOStuff::ERR_UNEXPECTED );
 456                 $this->redisPool->handleError( $conn, $e );
 457         }
 458
 459         /**
 460          * Send information about a single request to the debug log
 461          * @param string $method
 462          * @param string $key
 463          * @param string $server
 464          * @param bool $result
 465          */
 466         public function logRequest( $method, $key, $server, $result ) {
 467                 $this->debug( "$method $key on $server: " .
 468                         ( $result === false ? "failure" : "success" ) );
 469         }
 470 }