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 ) == false ) {
 106                         $this->set( $key, $value, $exptime );
 107                         return true;
 108                 }
 109         }
 110
 111         public function add_multi( $hash, $exptime = 0 ) {
 112                 foreach ( $hash as $key => $value ) {
 113                         $this->add( $key, $value, $exptime );
 114                 }
 115         }
 116
 117         public function delete_multi( $keys, $time = 0 ) {
 118                 foreach ( $keys as $key ) {
 119                         $this->delete( $key, $time );
 120                 }
 121         }
 122
 123         public function replace( $key, $value, $exptime = 0 ) {
 124                 if ( $this->get( $key ) !== false ) {
 125                         $this->set( $key, $value, $exptime );
 126                 }
 127         }
 128
 129         public function incr( $key, $value = 1 ) {
 130                 if ( !$this->lock( $key ) ) {
 131                         return false;
 132                 }
 133                 $value = intval( $value );
 134
 135                 $n = false;
 136                 if ( ( $n = $this->get( $key ) ) !== false ) {
 137                         $n += $value;
 138                         $this->set( $key, $n ); // exptime?
 139                 }
 140                 $this->unlock( $key );
 141                 return $n;
 142         }
 143
 144         public function decr( $key, $value = 1 ) {
 145                 return $this->incr( $key, - $value );
 146         }
 147
 148         public function debug( $text ) {
 149                 if ( $this->debugMode )
 150                         wfDebug( "BagOStuff debug: $text\n" );
 151         }
 152
 153         /**
 154          * Convert an optionally relative time to an absolute time
 155          */
 156         protected function convertExpiry( $exptime ) {
 157                 if ( ( $exptime != 0 ) && ( $exptime < 3600 * 24 * 30 ) ) {
 158                         return time() + $exptime;
 159                 } else {
 160                         return $exptime;
 161                 }
 162         }
 163 }
 164
 165 /**
 166  * Functional versions!
 167  * This is a test of the interface, mainly. It stores things in an associative
 168  * array, which is not going to persist between program runs.
 169  *
 170  * @ingroup Cache
 171  */
 172 class HashBagOStuff extends BagOStuff {
 173         var $bag;
 174
 175         function __construct() {
 176                 $this->bag = array();
 177         }
 178
 179         protected function expire( $key ) {
 180                 $et = $this->bag[$key][1];
 181                 if ( ( $et == 0 ) || ( $et > time() ) ) {
 182                         return false;
 183                 }
 184                 $this->delete( $key );
 185                 return true;
 186         }
 187
 188         function get( $key ) {
 189                 if ( !isset( $this->bag[$key] ) ) {
 190                         return false;
 191                 }
 192                 if ( $this->expire( $key ) ) {
 193                         return false;
 194                 }
 195                 return $this->bag[$key][0];
 196         }
 197
 198         function set( $key, $value, $exptime = 0 ) {
 199                 $this->bag[$key] = array( $value, $this->convertExpiry( $exptime ) );
 200         }
 201
 202         function delete( $key, $time = 0 ) {
 203                 if ( !isset( $this->bag[$key] ) ) {
 204                         return false;
 205                 }
 206                 unset( $this->bag[$key] );
 207                 return true;
 208         }
 209
 210         function keys() {
 211                 return array_keys( $this->bag );
 212         }
 213 }
 214
 215 /**
 216  * Class to store objects in the database
 217  *
 218  * @ingroup Cache
 219  */
 220 class SqlBagOStuff extends BagOStuff {
 221         var $lb, $db;
 222         var $lastExpireAll = 0;
 223
 224         protected function getDB() {
 225                 global $wgDBtype;
 226                 if ( !isset( $this->db ) ) {
 227                         /* We must keep a separate connection to MySQL in order to avoid deadlocks
 228                          * However, SQLite has an opposite behaviour.
 229                          * @todo Investigate behaviour for other databases
 230                          */
 231                         if ( $wgDBtype == 'sqlite' ) {
 232                                 $this->db = wfGetDB( DB_MASTER );
 233                         } else {
 234                                 $this->lb = wfGetLBFactory()->newMainLB();
 235                                 $this->db = $this->lb->getConnection( DB_MASTER );
 236                                 $this->db->clearFlag( DBO_TRX );
 237                         }
 238                 }
 239                 return $this->db;
 240         }
 241
 242         public function get( $key ) {
 243                 # expire old entries if any
 244                 $this->garbageCollect();
 245                 $db = $this->getDB();
 246                 $row = $db->selectRow( 'objectcache', array( 'value', 'exptime' ),
 247                         array( 'keyname' => $key ), __METHOD__ );
 248                 if ( !$row ) {
 249                         $this->debug( 'get: no matching rows' );
 250                         return false;
 251                 }
 252
 253                 $this->debug( "get: retrieved data; expiry time is " . $row->exptime );
 254                 if ( $this->isExpired( $row->exptime ) ) {
 255                         $this->debug( "get: key has expired, deleting" );
 256                         try {
 257                                 $db->begin();
 258                                 # Put the expiry time in the WHERE condition to avoid deleting a
 259                                 # newly-inserted value
 260                                 $db->delete( 'objectcache',
 261                                         array(
 262                                                 'keyname' => $key,
 263                                                 'exptime' => $row->exptime
 264                                         ), __METHOD__ );
 265                                 $db->commit();
 266                         } catch ( DBQueryError $e ) {
 267                                 $this->handleWriteError( $e );
 268                         }
 269                         return false;
 270                 }
 271                 return $this->unserialize( $db->decodeBlob( $row->value ) );
 272         }
 273
 274         public function set( $key, $value, $exptime = 0 ) {
 275                 $db = $this->getDB();
 276                 $exptime = intval( $exptime );
 277                 if ( $exptime < 0 ) $exptime = 0;
 278                 if ( $exptime == 0 ) {
 279                         $encExpiry = $this->getMaxDateTime();
 280                 } else {
 281                         if ( $exptime < 3.16e8 ) # ~10 years
 282                                 $exptime += time();
 283                         $encExpiry = $db->timestamp( $exptime );
 284                 }
 285                 try {
 286                         $db->begin();
 287                         $db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
 288                         $db->insert( 'objectcache',
 289                                 array(
 290                                         'keyname' => $key,
 291                                         'value' => $db->encodeBlob( $this->serialize( $value ) ),
 292                                         'exptime' => $encExpiry
 293                                 ), __METHOD__ );
 294                         $db->commit();
 295                 } catch ( DBQueryError $e ) {
 296                         $this->handleWriteError( $e );
 297                         return false;
 298                 }
 299                 return true;
 300         }
 301
 302         public function delete( $key, $time = 0 ) {
 303                 $db = $this->getDB();
 304                 try {
 305                         $db->begin();
 306                         $db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
 307                         $db->commit();
 308                 } catch ( DBQueryError $e ) {
 309                         $this->handleWriteError( $e );
 310                         return false;
 311                 }
 312                 return true;
 313         }
 314
 315         public function incr( $key, $step = 1 ) {
 316                 $db = $this->getDB();
 317                 $step = intval( $step );
 318
 319                 try {
 320                         $db->begin();
 321                         $row = $db->selectRow( 'objectcache', array( 'value', 'exptime' ),
 322                                 array( 'keyname' => $key ), __METHOD__, array( 'FOR UPDATE' ) );
 323                         if ( $row === false ) {
 324                                 // Missing
 325                                 $db->commit();
 326                                 return false;
 327                         }
 328                         $db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
 329                         if ( $this->isExpired( $row->exptime ) ) {
 330                                 // Expired, do not reinsert
 331                                 $db->commit();
 332                                 return false;
 333                         }
 334
 335                         $oldValue = intval( $this->unserialize( $db->decodeBlob( $row->value ) ) );
 336                         $newValue = $oldValue + $step;
 337                         $db->insert( 'objectcache',
 338                                 array(
 339                                         'keyname' => $key,
 340                                         'value' => $db->encodeBlob( $this->serialize( $newValue ) ),
 341                                         'exptime' => $row->exptime
 342                                 ), __METHOD__ );
 343                         $db->commit();
 344                 } catch ( DBQueryError $e ) {
 345                         $this->handleWriteError( $e );
 346                         return false;
 347                 }
 348                 return $newValue;
 349         }
 350
 351         public function keys() {
 352                 $db = $this->getDB();
 353                 $res = $db->select( 'objectcache', array( 'keyname' ), false, __METHOD__ );
 354                 $result = array();
 355                 foreach ( $res as $row ) {
 356                         $result[] = $row->keyname;
 357                 }
 358                 return $result;
 359         }
 360
 361         protected function isExpired( $exptime ) {
 362                 return $exptime != $this->getMaxDateTime() && wfTimestamp( TS_UNIX, $exptime ) < time();
 363         }
 364
 365         protected function getMaxDateTime() {
 366                 if ( time() > 0x7fffffff ) {
 367                         return $this->getDB()->timestamp( 1 << 62 );
 368                 } else {
 369                         return $this->getDB()->timestamp( 0x7fffffff );
 370                 }
 371         }
 372
 373         protected function garbageCollect() {
 374                 /* Ignore 99% of requests */
 375                 if ( !mt_rand( 0, 100 ) ) {
 376                         $now = time();
 377                         /* Avoid repeating the delete within a few seconds */
 378                         if ( $now > ( $this->lastExpireAll + 1 ) ) {
 379                                 $this->lastExpireAll = $now;
 380                                 $this->expireAll();
 381                         }
 382                 }
 383         }
 384
 385         public function expireAll() {
 386                 $db = $this->getDB();
 387                 $now = $db->timestamp();
 388                 try {
 389                         $db->begin();
 390                         $db->delete( 'objectcache', array( 'exptime < ' . $db->addQuotes( $now ) ), __METHOD__ );
 391                         $db->commit();
 392                 } catch ( DBQueryError $e ) {
 393                         $this->handleWriteError( $e );
 394                 }
 395         }
 396
 397         public function deleteAll() {
 398                 $db = $this->getDB();
 399                 try {
 400                         $db->begin();
 401                         $db->delete( 'objectcache', '*', __METHOD__ );
 402                         $db->commit();
 403                 } catch ( DBQueryError $e ) {
 404                         $this->handleWriteError( $e );
 405                 }
 406         }
 407
 408         /**
 409          * Serialize an object and, if possible, compress the representation.
 410          * On typical message and page data, this can provide a 3X decrease
 411          * in storage requirements.
 412          *
 413          * @param $data mixed
 414          * @return string
 415          */
 416         protected function serialize( &$data ) {
 417                 $serial = serialize( $data );
 418                 if ( function_exists( 'gzdeflate' ) ) {
 419                         return gzdeflate( $serial );
 420                 } else {
 421                         return $serial;
 422                 }
 423         }
 424
 425         /**
 426          * Unserialize and, if necessary, decompress an object.
 427          * @param $serial string
 428          * @return mixed
 429          */
 430         protected function unserialize( $serial ) {
 431                 if ( function_exists( 'gzinflate' ) ) {
 432                         $decomp = @gzinflate( $serial );
 433                         if ( false !== $decomp ) {
 434                                 $serial = $decomp;
 435                         }
 436                 }
 437                 $ret = unserialize( $serial );
 438                 return $ret;
 439         }
 440
 441         /**
 442          * Handle a DBQueryError which occurred during a write operation.
 443          * Ignore errors which are due to a read-only database, rethrow others.
 444          */
 445         protected function handleWriteError( $exception ) {
 446                 $db = $this->getDB();
 447                 if ( !$db->wasReadOnlyError() ) {
 448                         throw $exception;
 449                 }
 450                 try {
 451                         $db->rollback();
 452                 } catch ( DBQueryError $e ) {
 453                 }
 454                 wfDebug( __METHOD__ . ": ignoring query error\n" );
 455                 $db->ignoreErrors( false );
 456         }
 457 }
 458
 459 /**
 460  * Backwards compatibility alias
 461  */
 462 class MediaWikiBagOStuff extends SqlBagOStuff { }
 463
 464 /**
 465  * This is a wrapper for APC's shared memory functions
 466  *
 467  * @ingroup Cache
 468  */
 469 class APCBagOStuff extends BagOStuff {
 470         public function get( $key ) {
 471                 $val = apc_fetch( $key );
 472                 if ( is_string( $val ) ) {
 473                         $val = unserialize( $val );
 474                 }
 475                 return $val;
 476         }
 477
 478         public function set( $key, $value, $exptime = 0 ) {
 479                 apc_store( $key, serialize( $value ), $exptime );
 480                 return true;
 481         }
 482
 483         public function delete( $key, $time = 0 ) {
 484                 apc_delete( $key );
 485                 return true;
 486         }
 487
 488         public function keys() {
 489                 $info = apc_cache_info( 'user' );
 490                 $list = $info['cache_list'];
 491                 $keys = array();
 492                 foreach ( $list as $entry ) {
 493                         $keys[] = $entry['info'];
 494                 }
 495                 return $keys;
 496         }
 497 }
 498
 499 /**
 500  * This is a wrapper for eAccelerator's shared memory functions.
 501  *
 502  * This is basically identical to the deceased Turck MMCache version,
 503  * mostly because eAccelerator is based on Turck MMCache.
 504  *
 505  * @ingroup Cache
 506  */
 507 class eAccelBagOStuff extends BagOStuff {
 508         public function get( $key ) {
 509                 $val = eaccelerator_get( $key );
 510                 if ( is_string( $val ) ) {
 511                         $val = unserialize( $val );
 512                 }
 513                 return $val;
 514         }
 515
 516         public function set( $key, $value, $exptime = 0 ) {
 517                 eaccelerator_put( $key, serialize( $value ), $exptime );
 518                 return true;
 519         }
 520
 521         public function delete( $key, $time = 0 ) {
 522                 eaccelerator_rm( $key );
 523                 return true;
 524         }
 525
 526         public function lock( $key, $waitTimeout = 0 ) {
 527                 eaccelerator_lock( $key );
 528                 return true;
 529         }
 530
 531         public function unlock( $key ) {
 532                 eaccelerator_unlock( $key );
 533                 return true;
 534         }
 535 }
 536
 537 /**
 538  * Wrapper for XCache object caching functions; identical interface
 539  * to the APC wrapper
 540  *
 541  * @ingroup Cache
 542  */
 543 class XCacheBagOStuff extends BagOStuff {
 544
 545         /**
 546          * Get a value from the XCache object cache
 547          *
 548          * @param $key String: cache key
 549          * @return mixed
 550          */
 551         public function get( $key ) {
 552                 $val = xcache_get( $key );
 553                 if ( is_string( $val ) )
 554                         $val = unserialize( $val );
 555                 return $val;
 556         }
 557
 558         /**
 559          * Store a value in the XCache object cache
 560          *
 561          * @param $key String: cache key
 562          * @param $value Mixed: object to store
 563          * @param $expire Int: expiration time
 564          * @return bool
 565          */
 566         public function set( $key, $value, $expire = 0 ) {
 567                 xcache_set( $key, serialize( $value ), $expire );
 568                 return true;
 569         }
 570
 571         /**
 572          * Remove a value from the XCache object cache
 573          *
 574          * @param $key String: cache key
 575          * @param $time Int: not used in this implementation
 576          * @return bool
 577          */
 578         public function delete( $key, $time = 0 ) {
 579                 xcache_unset( $key );
 580                 return true;
 581         }
 582 }
 583
 584 /**
 585  * Cache that uses DBA as a backend.
 586  * Slow due to the need to constantly open and close the file to avoid holding
 587  * writer locks. Intended for development use only,  as a memcached workalike
 588  * for systems that don't have it.
 589  *
 590  * @ingroup Cache
 591  */
 592 class DBABagOStuff extends BagOStuff {
 593         var $mHandler, $mFile, $mReader, $mWriter, $mDisabled;
 594
 595         public function __construct( $dir = false ) {
 596                 global $wgDBAhandler;
 597                 if ( $dir === false ) {
 598                         global $wgTmpDirectory;
 599                         $dir = $wgTmpDirectory;
 600                 }
 601                 $this->mFile = "$dir/mw-cache-" . wfWikiID();
 602                 $this->mFile .= '.db';
 603                 wfDebug( __CLASS__ . ": using cache file {$this->mFile}\n" );
 604                 $this->mHandler = $wgDBAhandler;
 605         }
 606
 607         /**
 608          * Encode value and expiry for storage
 609          */
 610         function encode( $value, $expiry ) {
 611                 # Convert to absolute time
 612                 $expiry = $this->convertExpiry( $expiry );
 613                 return sprintf( '%010u', intval( $expiry ) ) . ' ' . serialize( $value );
 614         }
 615
 616         /**
 617          * @return list containing value first and expiry second
 618          */
 619         function decode( $blob ) {
 620                 if ( !is_string( $blob ) ) {
 621                         return array( null, 0 );
 622                 } else {
 623                         return array(
 624                                 unserialize( substr( $blob, 11 ) ),
 625                                 intval( substr( $blob, 0, 10 ) )
 626                         );
 627                 }
 628         }
 629
 630         function getReader() {
 631                 if ( file_exists( $this->mFile ) ) {
 632                         $handle = dba_open( $this->mFile, 'rl', $this->mHandler );
 633                 } else {
 634                         $handle = $this->getWriter();
 635                 }
 636                 if ( !$handle ) {
 637                         wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
 638                 }
 639                 return $handle;
 640         }
 641
 642         function getWriter() {
 643                 $handle = dba_open( $this->mFile, 'cl', $this->mHandler );
 644                 if ( !$handle ) {
 645                         wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
 646                 }
 647                 return $handle;
 648         }
 649
 650         function get( $key ) {
 651                 wfProfileIn( __METHOD__ );
 652                 wfDebug( __METHOD__ . "($key)\n" );
 653                 $handle = $this->getReader();
 654                 if ( !$handle ) {
 655                         return null;
 656                 }
 657                 $val = dba_fetch( $key, $handle );
 658                 list( $val, $expiry ) = $this->decode( $val );
 659                 # Must close ASAP because locks are held
 660                 dba_close( $handle );
 661
 662                 if ( !is_null( $val ) && $expiry && $expiry < time() ) {
 663                         # Key is expired, delete it
 664                         $handle = $this->getWriter();
 665                         dba_delete( $key, $handle );
 666                         dba_close( $handle );
 667                         wfDebug( __METHOD__ . ": $key expired\n" );
 668                         $val = null;
 669                 }
 670                 wfProfileOut( __METHOD__ );
 671                 return $val;
 672         }
 673
 674         function set( $key, $value, $exptime = 0 ) {
 675                 wfProfileIn( __METHOD__ );
 676                 wfDebug( __METHOD__ . "($key)\n" );
 677                 $blob = $this->encode( $value, $exptime );
 678                 $handle = $this->getWriter();
 679                 if ( !$handle ) {
 680                         return false;
 681                 }
 682                 $ret = dba_replace( $key, $blob, $handle );
 683                 dba_close( $handle );
 684                 wfProfileOut( __METHOD__ );
 685                 return $ret;
 686         }
 687
 688         function delete( $key, $time = 0 ) {
 689                 wfProfileIn( __METHOD__ );
 690                 wfDebug( __METHOD__ . "($key)\n" );
 691                 $handle = $this->getWriter();
 692                 if ( !$handle ) {
 693                         return false;
 694                 }
 695                 $ret = dba_delete( $key, $handle );
 696                 dba_close( $handle );
 697                 wfProfileOut( __METHOD__ );
 698                 return $ret;
 699         }
 700
 701         function add( $key, $value, $exptime = 0 ) {
 702                 wfProfileIn( __METHOD__ );
 703                 $blob = $this->encode( $value, $exptime );
 704                 $handle = $this->getWriter();
 705                 if ( !$handle ) {
 706                         return false;
 707                 }
 708                 $ret = dba_insert( $key, $blob, $handle );
 709                 # Insert failed, check to see if it failed due to an expired key
 710                 if ( !$ret ) {
 711                         list( $value, $expiry ) = $this->decode( dba_fetch( $key, $handle ) );
 712                         if ( $expiry < time() ) {
 713                                 # Yes expired, delete and try again
 714                                 dba_delete( $key, $handle );
 715                                 $ret = dba_insert( $key, $blob, $handle );
 716                                 # This time if it failed then it will be handled by the caller like any other race
 717                         }
 718                 }
 719
 720                 dba_close( $handle );
 721                 wfProfileOut( __METHOD__ );
 722                 return $ret;
 723         }
 724
 725         function keys() {
 726                 $reader = $this->getReader();
 727                 $k1 = dba_firstkey( $reader );
 728                 if ( !$k1 ) {
 729                         return array();
 730                 }
 731                 $result[] = $k1;
 732                 while ( $key = dba_nextkey( $reader ) ) {
 733                         $result[] = $key;
 734                 }
 735                 return $result;
 736         }
 737 }
 738
 739 /**
 740  * Wrapper for WinCache object caching functions; identical interface
 741  * to the APC wrapper
 742  *
 743  * @ingroup Cache
 744  */
 745 class WinCacheBagOStuff extends BagOStuff {
 746
 747         /**
 748          * Get a value from the WinCache object cache
 749          *
 750          * @param $key String: cache key
 751          * @return mixed
 752          */
 753         public function get( $key ) {
 754                 $val = wincache_ucache_get( $key );
 755                 if ( is_string( $val ) )
 756                         $val = unserialize( $val );
 757                 return $val;
 758         }
 759
 760         /**
 761          * Store a value in the WinCache object cache
 762          *
 763          * @param $key String: cache key
 764          * @param $value Mixed: object to store
 765          * @param $expire Int: expiration time
 766          * @return bool
 767          */
 768         public function set( $key, $value, $expire = 0 ) {
 769                 wincache_ucache_set( $key, serialize( $value ), $expire );
 770                 return true;
 771         }
 772
 773         /**
 774          * Remove a value from the WinCache object cache
 775          *
 776          * @param $key String: cache key
 777          * @param $time Int: not used in this implementation
 778          * @return bool
 779          */
 780         public function delete( $key, $time = 0 ) {
 781                 wincache_ucache_delete( $key );
 782                 return true;
 783         }
 784
 785         public function keys() {
 786                 $info = wincache_ucache_info();
 787                 $list = $info['ucache_entries'];
 788                 $keys = array();
 789                 foreach ( $list as $entry ) {
 790                         $keys[] = $entry['key_name'];
 791                 }
 792                 return $keys;
 793         }
 794 }