includes/BagOStuff.php

   1 <?php
   2 #
   3 # Copyright (C) 2003-2004 Brion Vibber <brion@pobox.com>
   4 # http://www.mediawiki.org/
   5 #
   6 # This program is free software; you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation; either version 2 of the License, or
   9 # (at your option) any later version.
  10 #
  11 # This program is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14 # GNU General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU General Public License along
  17 # with this program; if not, write to the Free Software Foundation, Inc.,
  18 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  19 # http://www.gnu.org/copyleft/gpl.html
  20
  21 /**
  22  * @defgroup Cache Cache
  23  *
  24  * @file
  25  * @ingroup Cache
  26  */
  27
  28 /**
  29  * interface is intended to be more or less compatible with
  30  * the PHP memcached client.
  31  *
  32  * backends for local hash array and SQL table included:
  33  * <code>
  34  *   $bag = new HashBagOStuff();
  35  *   $bag = new SqlBagOStuff(); # connect to db first
  36  * </code>
  37  *
  38  * @ingroup Cache
  39  */
  40 abstract class BagOStuff {
  41         var $debugMode = false;
  42
  43         public function set_debug( $bool ) {
  44                 $this->debugMode = $bool;
  45         }
  46
  47         /* *** THE GUTS OF THE OPERATION *** */
  48         /* Override these with functional things in subclasses */
  49
  50         /**
  51          * Get an item with the given key. Returns false if it does not exist.
  52          * @param $key string
  53          */
  54         abstract public function get( $key );
  55
  56         /**
  57          * Set an item.
  58          * @param $key string
  59          * @param $value mixed
  60          * @param $exptime int Either an interval in seconds or a unix timestamp for expiry
  61          */
  62         abstract public function set( $key, $value, $exptime = 0 );
  63
  64         /*
  65          * Delete an item.
  66          * @param $key string
  67          * @param $time int Amount of time to delay the operation (mostly memcached-specific)
  68          */
  69         abstract public function delete( $key, $time = 0 );
  70
  71         public function lock( $key, $timeout = 0 ) {
  72                 /* stub */
  73                 return true;
  74         }
  75
  76         public function unlock( $key ) {
  77                 /* stub */
  78                 return true;
  79         }
  80
  81         public function keys() {
  82                 /* stub */
  83                 return array();
  84         }
  85
  86         /* *** Emulated functions *** */
  87         /* Better performance can likely be got with custom written versions */
  88         public function get_multi( $keys ) {
  89                 $out = array();
  90
  91                 foreach ( $keys as $key ) {
  92                         $out[$key] = $this->get( $key );
  93                 }
  94
  95                 return $out;
  96         }
  97
  98         public function set_multi( $hash, $exptime = 0 ) {
  99                 foreach ( $hash as $key => $value ) {
 100                         $this->set( $key, $value, $exptime );
 101                 }
 102         }
 103
 104         public function add( $key, $value, $exptime = 0 ) {
 105                 if ( !$this->get( $key ) ) {
 106                         $this->set( $key, $value, $exptime );
 107
 108                         return true;
 109                 }
 110         }
 111
 112         public function add_multi( $hash, $exptime = 0 ) {
 113                 foreach ( $hash as $key => $value ) {
 114                         $this->add( $key, $value, $exptime );
 115                 }
 116         }
 117
 118         public function delete_multi( $keys, $time = 0 ) {
 119                 foreach ( $keys as $key ) {
 120                         $this->delete( $key, $time );
 121                 }
 122         }
 123
 124         public function replace( $key, $value, $exptime = 0 ) {
 125                 if ( $this->get( $key ) !== false ) {
 126                         $this->set( $key, $value, $exptime );
 127                 }
 128         }
 129
 130         public function incr( $key, $value = 1 ) {
 131                 if ( !$this->lock( $key ) ) {
 132                         return false;
 133                 }
 134
 135                 $value = intval( $value );
 136
 137                 $n = false;
 138                 if ( ( $n = $this->get( $key ) ) !== false ) {
 139                         $n += $value;
 140                         $this->set( $key, $n ); // exptime?
 141                 }
 142                 $this->unlock( $key );
 143
 144                 return $n;
 145         }
 146
 147         public function decr( $key, $value = 1 ) {
 148                 return $this->incr( $key, - $value );
 149         }
 150
 151         public function debug( $text ) {
 152                 if ( $this->debugMode ) {
 153                         wfDebug( "BagOStuff debug: $text\n" );
 154                 }
 155         }
 156
 157         /**
 158          * Convert an optionally relative time to an absolute time
 159          */
 160         protected function convertExpiry( $exptime ) {
 161                 if ( ( $exptime != 0 ) && ( $exptime < 86400 * 3650 /* 10 years */ ) ) {
 162                         return time() + $exptime;
 163                 } else {
 164                         return $exptime;
 165                 }
 166         }
 167 }
 168
 169 /**
 170  * Functional versions!
 171  * This is a test of the interface, mainly. It stores things in an associative
 172  * array, which is not going to persist between program runs.
 173  *
 174  * @ingroup Cache
 175  */
 176 class HashBagOStuff extends BagOStuff {
 177         var $bag;
 178
 179         function __construct() {
 180                 $this->bag = array();
 181         }
 182
 183         protected function expire( $key ) {
 184                 $et = $this->bag[$key][1];
 185
 186                 if ( ( $et == 0 ) || ( $et > time() ) ) {
 187                         return false;
 188                 }
 189
 190                 $this->delete( $key );
 191
 192                 return true;
 193         }
 194
 195         function get( $key ) {
 196                 if ( !isset( $this->bag[$key] ) ) {
 197                         return false;
 198                 }
 199
 200                 if ( $this->expire( $key ) ) {
 201                         return false;
 202                 }
 203
 204                 return $this->bag[$key][0];
 205         }
 206
 207         function set( $key, $value, $exptime = 0 ) {
 208                 $this->bag[$key] = array( $value, $this->convertExpiry( $exptime ) );
 209         }
 210
 211         function delete( $key, $time = 0 ) {
 212                 if ( !isset( $this->bag[$key] ) ) {
 213                         return false;
 214                 }
 215
 216                 unset( $this->bag[$key] );
 217
 218                 return true;
 219         }
 220
 221         function keys() {
 222                 return array_keys( $this->bag );
 223         }
 224 }
 225
 226 /**
 227  * Class to store objects in the database
 228  *
 229  * @ingroup Cache
 230  */
 231 class SqlBagOStuff extends BagOStuff {
 232         var $lb, $db;
 233         var $lastExpireAll = 0;
 234
 235         protected function getDB() {
 236                 global $wgDBtype;
 237
 238                 if ( !isset( $this->db ) ) {
 239                         /* We must keep a separate connection to MySQL in order to avoid deadlocks
 240                          * However, SQLite has an opposite behaviour.
 241                          * @todo Investigate behaviour for other databases
 242                          */
 243                         if ( $wgDBtype == 'sqlite' ) {
 244                                 $this->db = wfGetDB( DB_MASTER );
 245                         } else {
 246                                 $this->lb = wfGetLBFactory()->newMainLB();
 247                                 $this->db = $this->lb->getConnection( DB_MASTER );
 248                                 $this->db->clearFlag( DBO_TRX );
 249                         }
 250                 }
 251
 252                 return $this->db;
 253         }
 254
 255         public function get( $key ) {
 256                 # expire old entries if any
 257                 $this->garbageCollect();
 258                 $db = $this->getDB();
 259                 $row = $db->selectRow( 'objectcache', array( 'value', 'exptime' ),
 260                         array( 'keyname' => $key ), __METHOD__ );
 261
 262                 if ( !$row ) {
 263                         $this->debug( 'get: no matching rows' );
 264                         return false;
 265                 }
 266
 267                 $this->debug( "get: retrieved data; expiry time is " . $row->exptime );
 268
 269                 if ( $this->isExpired( $row->exptime ) ) {
 270                         $this->debug( "get: key has expired, deleting" );
 271                         try {
 272                                 $db->begin();
 273                                 # Put the expiry time in the WHERE condition to avoid deleting a
 274                                 # newly-inserted value
 275                                 $db->delete( 'objectcache',
 276                                         array(
 277                                                 'keyname' => $key,
 278                                                 'exptime' => $row->exptime
 279                                         ), __METHOD__ );
 280                                 $db->commit();
 281                         } catch ( DBQueryError $e ) {
 282                                 $this->handleWriteError( $e );
 283                         }
 284
 285                         return false;
 286                 }
 287
 288                 return $this->unserialize( $db->decodeBlob( $row->value ) );
 289         }
 290
 291         public function set( $key, $value, $exptime = 0 ) {
 292                 $db = $this->getDB();
 293                 $exptime = intval( $exptime );
 294
 295                 if ( $exptime < 0 ) {
 296                         $exptime = 0;
 297                 }
 298
 299                 if ( $exptime == 0 ) {
 300                         $encExpiry = $this->getMaxDateTime();
 301                 } else {
 302                         if ( $exptime < 3.16e8 ) { # ~10 years
 303                                 $exptime += time();
 304                         }
 305
 306                         $encExpiry = $db->timestamp( $exptime );
 307                 }
 308                 try {
 309                         $db->begin();
 310                         $db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
 311                         $db->insert( 'objectcache',
 312                                 array(
 313                                         'keyname' => $key,
 314                                         'value' => $db->encodeBlob( $this->serialize( $value ) ),
 315                                         'exptime' => $encExpiry
 316                                 ), __METHOD__ );
 317                         $db->commit();
 318                 } catch ( DBQueryError $e ) {
 319                         $this->handleWriteError( $e );
 320
 321                         return false;
 322                 }
 323
 324                 return true;
 325         }
 326
 327         public function delete( $key, $time = 0 ) {
 328                 $db = $this->getDB();
 329
 330                 try {
 331                         $db->begin();
 332                         $db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
 333                         $db->commit();
 334                 } catch ( DBQueryError $e ) {
 335                         $this->handleWriteError( $e );
 336
 337                         return false;
 338                 }
 339
 340                 return true;
 341         }
 342
 343         public function incr( $key, $step = 1 ) {
 344                 $db = $this->getDB();
 345                 $step = intval( $step );
 346
 347                 try {
 348                         $db->begin();
 349                         $row = $db->selectRow( 'objectcache', array( 'value', 'exptime' ),
 350                                 array( 'keyname' => $key ), __METHOD__, array( 'FOR UPDATE' ) );
 351                         if ( $row === false ) {
 352                                 // Missing
 353                                 $db->commit();
 354
 355                                 return false;
 356                         }
 357                         $db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
 358                         if ( $this->isExpired( $row->exptime ) ) {
 359                                 // Expired, do not reinsert
 360                                 $db->commit();
 361
 362                                 return false;
 363                         }
 364
 365                         $oldValue = intval( $this->unserialize( $db->decodeBlob( $row->value ) ) );
 366                         $newValue = $oldValue + $step;
 367                         $db->insert( 'objectcache',
 368                                 array(
 369                                         'keyname' => $key,
 370                                         'value' => $db->encodeBlob( $this->serialize( $newValue ) ),
 371                                         'exptime' => $row->exptime
 372                                 ), __METHOD__ );
 373                         $db->commit();
 374                 } catch ( DBQueryError $e ) {
 375                         $this->handleWriteError( $e );
 376
 377                         return false;
 378                 }
 379
 380                 return $newValue;
 381         }
 382
 383         public function keys() {
 384                 $db = $this->getDB();
 385                 $res = $db->select( 'objectcache', array( 'keyname' ), false, __METHOD__ );
 386                 $result = array();
 387
 388                 foreach ( $res as $row ) {
 389                         $result[] = $row->keyname;
 390                 }
 391
 392                 return $result;
 393         }
 394
 395         protected function isExpired( $exptime ) {
 396                 return $exptime != $this->getMaxDateTime() && wfTimestamp( TS_UNIX, $exptime ) < time();
 397         }
 398
 399         protected function getMaxDateTime() {
 400                 if ( time() > 0x7fffffff ) {
 401                         return $this->getDB()->timestamp( 1 << 62 );
 402                 } else {
 403                         return $this->getDB()->timestamp( 0x7fffffff );
 404                 }
 405         }
 406
 407         protected function garbageCollect() {
 408                 /* Ignore 99% of requests */
 409                 if ( !mt_rand( 0, 100 ) ) {
 410                         $now = time();
 411                         /* Avoid repeating the delete within a few seconds */
 412                         if ( $now > ( $this->lastExpireAll + 1 ) ) {
 413                                 $this->lastExpireAll = $now;
 414                                 $this->expireAll();
 415                         }
 416                 }
 417         }
 418
 419         public function expireAll() {
 420                 $db = $this->getDB();
 421                 $now = $db->timestamp();
 422
 423                 try {
 424                         $db->begin();
 425                         $db->delete( 'objectcache', array( 'exptime < ' . $db->addQuotes( $now ) ), __METHOD__ );
 426                         $db->commit();
 427                 } catch ( DBQueryError $e ) {
 428                         $this->handleWriteError( $e );
 429                 }
 430         }
 431
 432         public function deleteAll() {
 433                 $db = $this->getDB();
 434
 435                 try {
 436                         $db->begin();
 437                         $db->delete( 'objectcache', '*', __METHOD__ );
 438                         $db->commit();
 439                 } catch ( DBQueryError $e ) {
 440                         $this->handleWriteError( $e );
 441                 }
 442         }
 443
 444         /**
 445          * Serialize an object and, if possible, compress the representation.
 446          * On typical message and page data, this can provide a 3X decrease
 447          * in storage requirements.
 448          *
 449          * @param $data mixed
 450          * @return string
 451          */
 452         protected function serialize( &$data ) {
 453                 $serial = serialize( $data );
 454
 455                 if ( function_exists( 'gzdeflate' ) ) {
 456                         return gzdeflate( $serial );
 457                 } else {
 458                         return $serial;
 459                 }
 460         }
 461
 462         /**
 463          * Unserialize and, if necessary, decompress an object.
 464          * @param $serial string
 465          * @return mixed
 466          */
 467         protected function unserialize( $serial ) {
 468                 if ( function_exists( 'gzinflate' ) ) {
 469                         $decomp = @gzinflate( $serial );
 470
 471                         if ( false !== $decomp ) {
 472                                 $serial = $decomp;
 473                         }
 474                 }
 475
 476                 $ret = unserialize( $serial );
 477
 478                 return $ret;
 479         }
 480
 481         /**
 482          * Handle a DBQueryError which occurred during a write operation.
 483          * Ignore errors which are due to a read-only database, rethrow others.
 484          */
 485         protected function handleWriteError( $exception ) {
 486                 $db = $this->getDB();
 487
 488                 if ( !$db->wasReadOnlyError() ) {
 489                         throw $exception;
 490                 }
 491
 492                 try {
 493                         $db->rollback();
 494                 } catch ( DBQueryError $e ) {
 495                 }
 496
 497                 wfDebug( __METHOD__ . ": ignoring query error\n" );
 498                 $db->ignoreErrors( false );
 499         }
 500 }
 501
 502 /**
 503  * Backwards compatibility alias
 504  */
 505 class MediaWikiBagOStuff extends SqlBagOStuff { }
 506
 507 /**
 508  * This is a wrapper for APC's shared memory functions
 509  *
 510  * @ingroup Cache
 511  */
 512 class APCBagOStuff extends BagOStuff {
 513         public function get( $key ) {
 514                 $val = apc_fetch( $key );
 515
 516                 if ( is_string( $val ) ) {
 517                         $val = unserialize( $val );
 518                 }
 519
 520                 return $val;
 521         }
 522
 523         public function set( $key, $value, $exptime = 0 ) {
 524                 apc_store( $key, serialize( $value ), $exptime );
 525
 526                 return true;
 527         }
 528
 529         public function delete( $key, $time = 0 ) {
 530                 apc_delete( $key );
 531
 532                 return true;
 533         }
 534
 535         public function keys() {
 536                 $info = apc_cache_info( 'user' );
 537                 $list = $info['cache_list'];
 538                 $keys = array();
 539
 540                 foreach ( $list as $entry ) {
 541                         $keys[] = $entry['info'];
 542                 }
 543
 544                 return $keys;
 545         }
 546 }
 547
 548 /**
 549  * This is a wrapper for eAccelerator's shared memory functions.
 550  *
 551  * This is basically identical to the deceased Turck MMCache version,
 552  * mostly because eAccelerator is based on Turck MMCache.
 553  *
 554  * @ingroup Cache
 555  */
 556 class eAccelBagOStuff extends BagOStuff {
 557         public function get( $key ) {
 558                 $val = eaccelerator_get( $key );
 559
 560                 if ( is_string( $val ) ) {
 561                         $val = unserialize( $val );
 562                 }
 563
 564                 return $val;
 565         }
 566
 567         public function set( $key, $value, $exptime = 0 ) {
 568                 eaccelerator_put( $key, serialize( $value ), $exptime );
 569
 570                 return true;
 571         }
 572
 573         public function delete( $key, $time = 0 ) {
 574                 eaccelerator_rm( $key );
 575
 576                 return true;
 577         }
 578
 579         public function lock( $key, $waitTimeout = 0 ) {
 580                 eaccelerator_lock( $key );
 581
 582                 return true;
 583         }
 584
 585         public function unlock( $key ) {
 586                 eaccelerator_unlock( $key );
 587
 588                 return true;
 589         }
 590 }
 591
 592 /**
 593  * Wrapper for XCache object caching functions; identical interface
 594  * to the APC wrapper
 595  *
 596  * @ingroup Cache
 597  */
 598 class XCacheBagOStuff extends BagOStuff {
 599         /**
 600          * Get a value from the XCache object cache
 601          *
 602          * @param $key String: cache key
 603          * @return mixed
 604          */
 605         public function get( $key ) {
 606                 $val = xcache_get( $key );
 607
 608                 if ( is_string( $val ) ) {
 609                         $val = unserialize( $val );
 610                 }
 611
 612                 return $val;
 613         }
 614
 615         /**
 616          * Store a value in the XCache object cache
 617          *
 618          * @param $key String: cache key
 619          * @param $value Mixed: object to store
 620          * @param $expire Int: expiration time
 621          * @return bool
 622          */
 623         public function set( $key, $value, $expire = 0 ) {
 624                 xcache_set( $key, serialize( $value ), $expire );
 625
 626                 return true;
 627         }
 628
 629         /**
 630          * Remove a value from the XCache object cache
 631          *
 632          * @param $key String: cache key
 633          * @param $time Int: not used in this implementation
 634          * @return bool
 635          */
 636         public function delete( $key, $time = 0 ) {
 637                 xcache_unset( $key );
 638
 639                 return true;
 640         }
 641 }
 642
 643 /**
 644  * Cache that uses DBA as a backend.
 645  * Slow due to the need to constantly open and close the file to avoid holding
 646  * writer locks. Intended for development use only,  as a memcached workalike
 647  * for systems that don't have it.
 648  *
 649  * @ingroup Cache
 650  */
 651 class DBABagOStuff extends BagOStuff {
 652         var $mHandler, $mFile, $mReader, $mWriter, $mDisabled;
 653
 654         public function __construct( $dir = false ) {
 655                 global $wgDBAhandler;
 656
 657                 if ( $dir === false ) {
 658                         global $wgTmpDirectory;
 659                         $dir = $wgTmpDirectory;
 660                 }
 661
 662                 $this->mFile = "$dir/mw-cache-" . wfWikiID();
 663                 $this->mFile .= '.db';
 664                 wfDebug( __CLASS__ . ": using cache file {$this->mFile}\n" );
 665                 $this->mHandler = $wgDBAhandler;
 666         }
 667
 668         /**
 669          * Encode value and expiry for storage
 670          */
 671         function encode( $value, $expiry ) {
 672                 # Convert to absolute time
 673                 $expiry = $this->convertExpiry( $expiry );
 674
 675                 return sprintf( '%010u', intval( $expiry ) ) . ' ' . serialize( $value );
 676         }
 677
 678         /**
 679          * @return list containing value first and expiry second
 680          */
 681         function decode( $blob ) {
 682                 if ( !is_string( $blob ) ) {
 683                         return array( null, 0 );
 684                 } else {
 685                         return array(
 686                                 unserialize( substr( $blob, 11 ) ),
 687                                 intval( substr( $blob, 0, 10 ) )
 688                         );
 689                 }
 690         }
 691
 692         function getReader() {
 693                 if ( file_exists( $this->mFile ) ) {
 694                         $handle = dba_open( $this->mFile, 'rl', $this->mHandler );
 695                 } else {
 696                         $handle = $this->getWriter();
 697                 }
 698
 699                 if ( !$handle ) {
 700                         wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
 701                 }
 702
 703                 return $handle;
 704         }
 705
 706         function getWriter() {
 707                 $handle = dba_open( $this->mFile, 'cl', $this->mHandler );
 708
 709                 if ( !$handle ) {
 710                         wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
 711                 }
 712
 713                 return $handle;
 714         }
 715
 716         function get( $key ) {
 717                 wfProfileIn( __METHOD__ );
 718                 wfDebug( __METHOD__ . "($key)\n" );
 719
 720                 $handle = $this->getReader();
 721                 if ( !$handle ) {
 722                         return null;
 723                 }
 724
 725                 $val = dba_fetch( $key, $handle );
 726                 list( $val, $expiry ) = $this->decode( $val );
 727
 728                 # Must close ASAP because locks are held
 729                 dba_close( $handle );
 730
 731                 if ( !is_null( $val ) && $expiry && $expiry < time() ) {
 732                         # Key is expired, delete it
 733                         $handle = $this->getWriter();
 734                         dba_delete( $key, $handle );
 735                         dba_close( $handle );
 736                         wfDebug( __METHOD__ . ": $key expired\n" );
 737                         $val = null;
 738                 }
 739
 740                 wfProfileOut( __METHOD__ );
 741                 return $val;
 742         }
 743
 744         function set( $key, $value, $exptime = 0 ) {
 745                 wfProfileIn( __METHOD__ );
 746                 wfDebug( __METHOD__ . "($key)\n" );
 747
 748                 $blob = $this->encode( $value, $exptime );
 749
 750                 $handle = $this->getWriter();
 751                 if ( !$handle ) {
 752                         return false;
 753                 }
 754
 755                 $ret = dba_replace( $key, $blob, $handle );
 756                 dba_close( $handle );
 757
 758                 wfProfileOut( __METHOD__ );
 759                 return $ret;
 760         }
 761
 762         function delete( $key, $time = 0 ) {
 763                 wfProfileIn( __METHOD__ );
 764                 wfDebug( __METHOD__ . "($key)\n" );
 765
 766                 $handle = $this->getWriter();
 767                 if ( !$handle ) {
 768                         return false;
 769                 }
 770
 771                 $ret = dba_delete( $key, $handle );
 772                 dba_close( $handle );
 773
 774                 wfProfileOut( __METHOD__ );
 775                 return $ret;
 776         }
 777
 778         function add( $key, $value, $exptime = 0 ) {
 779                 wfProfileIn( __METHOD__ );
 780
 781                 $blob = $this->encode( $value, $exptime );
 782
 783                 $handle = $this->getWriter();
 784
 785                 if ( !$handle ) {
 786                         return false;
 787                 }
 788
 789                 $ret = dba_insert( $key, $blob, $handle );
 790
 791                 # Insert failed, check to see if it failed due to an expired key
 792                 if ( !$ret ) {
 793                         list( $value, $expiry ) = $this->decode( dba_fetch( $key, $handle ) );
 794
 795                         if ( $expiry < time() ) {
 796                                 # Yes expired, delete and try again
 797                                 dba_delete( $key, $handle );
 798                                 $ret = dba_insert( $key, $blob, $handle );
 799                                 # This time if it failed then it will be handled by the caller like any other race
 800                         }
 801                 }
 802
 803                 dba_close( $handle );
 804
 805                 wfProfileOut( __METHOD__ );
 806                 return $ret;
 807         }
 808
 809         function keys() {
 810                 $reader = $this->getReader();
 811                 $k1 = dba_firstkey( $reader );
 812
 813                 if ( !$k1 ) {
 814                         return array();
 815                 }
 816
 817                 $result[] = $k1;
 818
 819                 while ( $key = dba_nextkey( $reader ) ) {
 820                         $result[] = $key;
 821                 }
 822
 823                 return $result;
 824         }
 825 }
 826
 827 /**
 828  * Wrapper for WinCache object caching functions; identical interface
 829  * to the APC wrapper
 830  *
 831  * @ingroup Cache
 832  */
 833 class WinCacheBagOStuff extends BagOStuff {
 834
 835         /**
 836          * Get a value from the WinCache object cache
 837          *
 838          * @param $key String: cache key
 839          * @return mixed
 840          */
 841         public function get( $key ) {
 842                 $val = wincache_ucache_get( $key );
 843
 844                 if ( is_string( $val ) ) {
 845                         $val = unserialize( $val );
 846                 }
 847
 848                 return $val;
 849         }
 850
 851         /**
 852          * Store a value in the WinCache object cache
 853          *
 854          * @param $key String: cache key
 855          * @param $value Mixed: object to store
 856          * @param $expire Int: expiration time
 857          * @return bool
 858          */
 859         public function set( $key, $value, $expire = 0 ) {
 860                 wincache_ucache_set( $key, serialize( $value ), $expire );
 861
 862                 return true;
 863         }
 864
 865         /**
 866          * Remove a value from the WinCache object cache
 867          *
 868          * @param $key String: cache key
 869          * @param $time Int: not used in this implementation
 870          * @return bool
 871          */
 872         public function delete( $key, $time = 0 ) {
 873                 wincache_ucache_delete( $key );
 874
 875                 return true;
 876         }
 877
 878         public function keys() {
 879                 $info = wincache_ucache_info();
 880                 $list = $info['ucache_entries'];
 881                 $keys = array();
 882
 883                 foreach ( $list as $entry ) {
 884                         $keys[] = $entry['key_name'];
 885                 }
 886
 887                 return $keys;
 888         }
 889 }