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 MediumSpecificBagOStuff {
  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                 $conn = $this->getConnection( $key );
  93                 if ( !$conn ) {
  94                         return false;
  95                 }
  96
  97                 $e = null;
  98                 try {
  99                         $value = $conn->get( $key );
 100                         $casToken = $value;
 101                         $result = $this->unserialize( $value );
 102                 } catch ( RedisException $e ) {
 103                         $result = false;
 104                         $this->handleException( $conn, $e );
 105                 }
 106
 107                 $this->logRequest( 'get', $key, $conn->getServer(), $e );
 108
 109                 return $result;
 110         }
 111
 112         protected function doSet( $key, $value, $exptime = 0, $flags = 0 ) {
 113                 $conn = $this->getConnection( $key );
 114                 if ( !$conn ) {
 115                         return false;
 116                 }
 117
 118                 $ttl = $this->convertToRelative( $exptime );
 119
 120                 $e = null;
 121                 try {
 122                         if ( $ttl ) {
 123                                 $result = $conn->setex( $key, $ttl, $this->serialize( $value ) );
 124                         } else {
 125                                 $result = $conn->set( $key, $this->serialize( $value ) );
 126                         }
 127                 } catch ( RedisException $e ) {
 128                         $result = false;
 129                         $this->handleException( $conn, $e );
 130                 }
 131
 132                 $this->logRequest( 'set', $key, $conn->getServer(), $e );
 133
 134                 return $result;
 135         }
 136
 137         protected function doDelete( $key, $flags = 0 ) {
 138                 $conn = $this->getConnection( $key );
 139                 if ( !$conn ) {
 140                         return false;
 141                 }
 142
 143                 $e = null;
 144                 try {
 145                         // Note that redis does not return false if the key was not there
 146                         $result = ( $conn->delete( $key ) !== false );
 147                 } catch ( RedisException $e ) {
 148                         $result = false;
 149                         $this->handleException( $conn, $e );
 150                 }
 151
 152                 $this->logRequest( 'delete', $key, $conn->getServer(), $e );
 153
 154                 return $result;
 155         }
 156
 157         protected function doGetMulti( array $keys, $flags = 0 ) {
 158                 /** @var RedisConnRef[]|Redis[] $conns */
 159                 $conns = [];
 160                 $batches = [];
 161                 foreach ( $keys as $key ) {
 162                         $conn = $this->getConnection( $key );
 163                         if ( $conn ) {
 164                                 $server = $conn->getServer();
 165                                 $conns[$server] = $conn;
 166                                 $batches[$server][] = $key;
 167                         }
 168                 }
 169
 170                 $result = [];
 171                 foreach ( $batches as $server => $batchKeys ) {
 172                         $conn = $conns[$server];
 173
 174                         $e = null;
 175                         try {
 176                                 // Avoid mget() to reduce CPU hogging from a single request
 177                                 $conn->multi( Redis::PIPELINE );
 178                                 foreach ( $batchKeys as $key ) {
 179                                         $conn->get( $key );
 180                                 }
 181                                 $batchResult = $conn->exec();
 182                                 if ( $batchResult === false ) {
 183                                         $this->logRequest( 'get', implode( ',', $batchKeys ), $server, true );
 184                                         continue;
 185                                 }
 186
 187                                 foreach ( $batchResult as $i => $value ) {
 188                                         if ( $value !== false ) {
 189                                                 $result[$batchKeys[$i]] = $this->unserialize( $value );
 190                                         }
 191                                 }
 192                         } catch ( RedisException $e ) {
 193                                 $this->handleException( $conn, $e );
 194                         }
 195
 196                         $this->logRequest( 'get', implode( ',', $batchKeys ), $server, $e );
 197                 }
 198
 199                 return $result;
 200         }
 201
 202         protected function doSetMulti( array $data, $exptime = 0, $flags = 0 ) {
 203                 /** @var RedisConnRef[]|Redis[] $conns */
 204                 $conns = [];
 205                 $batches = [];
 206                 foreach ( $data as $key => $value ) {
 207                         $conn = $this->getConnection( $key );
 208                         if ( $conn ) {
 209                                 $server = $conn->getServer();
 210                                 $conns[$server] = $conn;
 211                                 $batches[$server][] = $key;
 212                         }
 213                 }
 214
 215                 $ttl = $this->convertToRelative( $exptime );
 216                 $op = $ttl ? 'setex' : 'set';
 217
 218                 $result = true;
 219                 foreach ( $batches as $server => $batchKeys ) {
 220                         $conn = $conns[$server];
 221
 222                         $e = null;
 223                         try {
 224                                 // Avoid mset() to reduce CPU hogging from a single request
 225                                 $conn->multi( Redis::PIPELINE );
 226                                 foreach ( $batchKeys as $key ) {
 227                                         if ( $ttl ) {
 228                                                 $conn->setex( $key, $ttl, $this->serialize( $data[$key] ) );
 229                                         } else {
 230                                                 $conn->set( $key, $this->serialize( $data[$key] ) );
 231                                         }
 232                                 }
 233                                 $batchResult = $conn->exec();
 234                                 if ( $batchResult === false ) {
 235                                         $this->logRequest( $op, implode( ',', $batchKeys ), $server, true );
 236                                         continue;
 237                                 }
 238                                 $result = $result && !in_array( false, $batchResult, true );
 239                         } catch ( RedisException $e ) {
 240                                 $this->handleException( $conn, $e );
 241                                 $result = false;
 242                         }
 243
 244                         $this->logRequest( $op, implode( ',', $batchKeys ), $server, $e );
 245                 }
 246
 247                 return $result;
 248         }
 249
 250         protected function doDeleteMulti( array $keys, $flags = 0 ) {
 251                 /** @var RedisConnRef[]|Redis[] $conns */
 252                 $conns = [];
 253                 $batches = [];
 254                 foreach ( $keys as $key ) {
 255                         $conn = $this->getConnection( $key );
 256                         if ( $conn ) {
 257                                 $server = $conn->getServer();
 258                                 $conns[$server] = $conn;
 259                                 $batches[$server][] = $key;
 260                         }
 261                 }
 262
 263                 $result = true;
 264                 foreach ( $batches as $server => $batchKeys ) {
 265                         $conn = $conns[$server];
 266
 267                         $e = null;
 268                         try {
 269                                 // Avoid delete() with array to reduce CPU hogging from a single request
 270                                 $conn->multi( Redis::PIPELINE );
 271                                 foreach ( $batchKeys as $key ) {
 272                                         $conn->delete( $key );
 273                                 }
 274                                 $batchResult = $conn->exec();
 275                                 if ( $batchResult === false ) {
 276                                         $this->logRequest( 'delete', implode( ',', $batchKeys ), $server, true );
 277                                         continue;
 278                                 }
 279                                 // Note that redis does not return false if the key was not there
 280                                 $result = $result && !in_array( false, $batchResult, true );
 281                         } catch ( RedisException $e ) {
 282                                 $this->handleException( $conn, $e );
 283                                 $result = false;
 284                         }
 285
 286                         $this->logRequest( 'delete', implode( ',', $batchKeys ), $server, $e );
 287                 }
 288
 289                 return $result;
 290         }
 291
 292         public function changeTTLMulti( array $keys, $exptime, $flags = 0 ) {
 293                 /** @var RedisConnRef[]|Redis[] $conns */
 294                 $conns = [];
 295                 $batches = [];
 296                 foreach ( $keys as $key ) {
 297                         $conn = $this->getConnection( $key );
 298                         if ( $conn ) {
 299                                 $server = $conn->getServer();
 300                                 $conns[$server] = $conn;
 301                                 $batches[$server][] = $key;
 302                         }
 303                 }
 304
 305                 $relative = $this->expiryIsRelative( $exptime );
 306                 $op = ( $exptime == 0 ) ? 'persist' : ( $relative ? 'expire' : 'expireAt' );
 307
 308                 $result = true;
 309                 foreach ( $batches as $server => $batchKeys ) {
 310                         $conn = $conns[$server];
 311
 312                         $e = null;
 313                         try {
 314                                 $conn->multi( Redis::PIPELINE );
 315                                 foreach ( $batchKeys as $key ) {
 316                                         if ( $exptime == 0 ) {
 317                                                 $conn->persist( $key );
 318                                         } elseif ( $relative ) {
 319                                                 $conn->expire( $key, $this->convertToRelative( $exptime ) );
 320                                         } else {
 321                                                 $conn->expireAt( $key, $this->convertToExpiry( $exptime ) );
 322                                         }
 323                                 }
 324                                 $batchResult = $conn->exec();
 325                                 if ( $batchResult === false ) {
 326                                         $this->logRequest( $op, implode( ',', $batchKeys ), $server, true );
 327                                         continue;
 328                                 }
 329                                 $result = in_array( false, $batchResult, true ) ? false : $result;
 330                         } catch ( RedisException $e ) {
 331                                 $this->handleException( $conn, $e );
 332                                 $result = false;
 333                         }
 334
 335                         $this->logRequest( $op, implode( ',', $batchKeys ), $server, $e );
 336                 }
 337
 338                 return $result;
 339         }
 340
 341         public function add( $key, $value, $expiry = 0, $flags = 0 ) {
 342                 $conn = $this->getConnection( $key );
 343                 if ( !$conn ) {
 344                         return false;
 345                 }
 346
 347                 $ttl = $this->convertToRelative( $expiry );
 348                 try {
 349                         $result = $conn->set(
 350                                 $key,
 351                                 $this->serialize( $value ),
 352                                 $ttl ? [ 'nx', 'ex' => $ttl ] : [ 'nx' ]
 353                         );
 354                 } catch ( RedisException $e ) {
 355                         $result = false;
 356                         $this->handleException( $conn, $e );
 357                 }
 358
 359                 $this->logRequest( 'add', $key, $conn->getServer(), $result );
 360
 361                 return $result;
 362         }
 363
 364         public function incr( $key, $value = 1 ) {
 365                 $conn = $this->getConnection( $key );
 366                 if ( !$conn ) {
 367                         return false;
 368                 }
 369
 370                 try {
 371                         if ( !$conn->exists( $key ) ) {
 372                                 return false;
 373                         }
 374                         // @FIXME: on races, the key may have a 0 TTL
 375                         $result = $conn->incrBy( $key, $value );
 376                 } catch ( RedisException $e ) {
 377                         $result = false;
 378                         $this->handleException( $conn, $e );
 379                 }
 380
 381                 $this->logRequest( 'incr', $key, $conn->getServer(), $result );
 382
 383                 return $result;
 384         }
 385
 386         protected function doChangeTTL( $key, $exptime, $flags ) {
 387                 $conn = $this->getConnection( $key );
 388                 if ( !$conn ) {
 389                         return false;
 390                 }
 391
 392                 $relative = $this->expiryIsRelative( $exptime );
 393                 try {
 394                         if ( $exptime == 0 ) {
 395                                 $result = $conn->persist( $key );
 396                                 $this->logRequest( 'persist', $key, $conn->getServer(), $result );
 397                         } elseif ( $relative ) {
 398                                 $result = $conn->expire( $key, $this->convertToRelative( $exptime ) );
 399                                 $this->logRequest( 'expire', $key, $conn->getServer(), $result );
 400                         } else {
 401                                 $result = $conn->expireAt( $key, $this->convertToExpiry( $exptime ) );
 402                                 $this->logRequest( 'expireAt', $key, $conn->getServer(), $result );
 403                         }
 404                 } catch ( RedisException $e ) {
 405                         $result = false;
 406                         $this->handleException( $conn, $e );
 407                 }
 408
 409                 return $result;
 410         }
 411
 412         /**
 413          * @param string $key
 414          * @return RedisConnRef|Redis|null Redis handle wrapper for the key or null on failure
 415          */
 416         protected function getConnection( $key ) {
 417                 $candidates = array_keys( $this->serverTagMap );
 418
 419                 if ( count( $this->servers ) > 1 ) {
 420                         ArrayUtils::consistentHashSort( $candidates, $key, '/' );
 421                         if ( !$this->automaticFailover ) {
 422                                 $candidates = array_slice( $candidates, 0, 1 );
 423                         }
 424                 }
 425
 426                 while ( ( $tag = array_shift( $candidates ) ) !== null ) {
 427                         $server = $this->serverTagMap[$tag];
 428                         $conn = $this->redisPool->getConnection( $server, $this->logger );
 429                         if ( !$conn ) {
 430                                 continue;
 431                         }
 432
 433                         // If automatic failover is enabled, check that the server's link
 434                         // to its master (if any) is up -- but only if there are other
 435                         // viable candidates left to consider. Also, getMasterLinkStatus()
 436                         // does not work with twemproxy, though $candidates will be empty
 437                         // by now in such cases.
 438                         if ( $this->automaticFailover && $candidates ) {
 439                                 try {
 440                                         /** @var string[] $info */
 441                                         $info = $conn->info();
 442                                         if ( ( $info['master_link_status'] ?? null ) === 'down' ) {
 443                                                 // If the master cannot be reached, fail-over to the next server.
 444                                                 // If masters are in data-center A, and replica DBs in data-center B,
 445                                                 // this helps avoid the case were fail-over happens in A but not
 446                                                 // to the corresponding server in B (e.g. read/write mismatch).
 447                                                 continue;
 448                                         }
 449                                 } catch ( RedisException $e ) {
 450                                         // Server is not accepting commands
 451                                         $this->redisPool->handleError( $conn, $e );
 452                                         continue;
 453                                 }
 454                         }
 455
 456                         return $conn;
 457                 }
 458
 459                 $this->setLastError( BagOStuff::ERR_UNREACHABLE );
 460
 461                 return null;
 462         }
 463
 464         /**
 465          * Log a fatal error
 466          * @param string $msg
 467          */
 468         protected function logError( $msg ) {
 469                 $this->logger->error( "Redis error: $msg" );
 470         }
 471
 472         /**
 473          * The redis extension throws an exception in response to various read, write
 474          * and protocol errors. Sometimes it also closes the connection, sometimes
 475          * not. The safest response for us is to explicitly destroy the connection
 476          * object and let it be reopened during the next request.
 477          * @param RedisConnRef $conn
 478          * @param RedisException $e
 479          */
 480         protected function handleException( RedisConnRef $conn, RedisException $e ) {
 481                 $this->setLastError( BagOStuff::ERR_UNEXPECTED );
 482                 $this->redisPool->handleError( $conn, $e );
 483         }
 484
 485         /**
 486          * Send information about a single request to the debug log
 487          * @param string $op
 488          * @param string $keys
 489          * @param string $server
 490          * @param Exception|bool|null $e
 491          */
 492         public function logRequest( $op, $keys, $server, $e = null ) {
 493                 $this->debug( "$op($keys) on $server: " . ( $e ? "failure" : "success" ) );
 494         }
 495 }