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  *   $bag = new MediaWikiBagOStuff($tablename); # connect to db first
  36  * </code>
  37  *
  38  * @ingroup Cache
  39  */
  40 class BagOStuff {
  41         var $debugmode;
  42
  43         function __construct() {
  44                 $this->set_debug( false );
  45         }
  46
  47         function set_debug($bool) {
  48                 $this->debugmode = $bool;
  49         }
  50
  51         /* *** THE GUTS OF THE OPERATION *** */
  52         /* Override these with functional things in subclasses */
  53
  54         function get($key) {
  55                 /* stub */
  56                 return false;
  57         }
  58
  59         function set($key, $value, $exptime=0) {
  60                 /* stub */
  61                 return false;
  62         }
  63
  64         function delete($key, $time=0) {
  65                 /* stub */
  66                 return false;
  67         }
  68
  69         function lock($key, $timeout = 0) {
  70                 /* stub */
  71                 return true;
  72         }
  73
  74         function unlock($key) {
  75                 /* stub */
  76                 return true;
  77         }
  78
  79         function keys() {
  80                 /* stub */
  81                 return array();
  82         }
  83
  84         /* *** Emulated functions *** */
  85         /* Better performance can likely be got with custom written versions */
  86         function get_multi($keys) {
  87                 $out = array();
  88                 foreach($keys as $key)
  89                         $out[$key] = $this->get($key);
  90                 return $out;
  91         }
  92
  93         function set_multi($hash, $exptime=0) {
  94                 foreach($hash as $key => $value)
  95                         $this->set($key, $value, $exptime);
  96         }
  97
  98         function add($key, $value, $exptime=0) {
  99                 if( $this->get($key) == false ) {
 100                         $this->set($key, $value, $exptime);
 101                         return true;
 102                 }
 103         }
 104
 105         function add_multi($hash, $exptime=0) {
 106                 foreach($hash as $key => $value)
 107                         $this->add($key, $value, $exptime);
 108         }
 109
 110         function delete_multi($keys, $time=0) {
 111                 foreach($keys as $key)
 112                         $this->delete($key, $time);
 113         }
 114
 115         function replace($key, $value, $exptime=0) {
 116                 if( $this->get($key) !== false )
 117                         $this->set($key, $value, $exptime);
 118         }
 119
 120         function incr($key, $value=1) {
 121                 if ( !$this->lock($key) ) {
 122                         return false;
 123                 }
 124                 $value = intval($value);
 125                 if($value < 0) $value = 0;
 126
 127                 $n = false;
 128                 if( ($n = $this->get($key)) !== false ) {
 129                         $n += $value;
 130                         $this->set($key, $n); // exptime?
 131                 }
 132                 $this->unlock($key);
 133                 return $n;
 134         }
 135
 136         function decr($key, $value=1) {
 137                 if ( !$this->lock($key) ) {
 138                         return false;
 139                 }
 140                 $value = intval($value);
 141                 if($value < 0) $value = 0;
 142
 143                 $m = false;
 144                 if( ($n = $this->get($key)) !== false ) {
 145                         $m = $n - $value;
 146                         if($m < 0) $m = 0;
 147                         $this->set($key, $m); // exptime?
 148                 }
 149                 $this->unlock($key);
 150                 return $m;
 151         }
 152
 153         function _debug($text) {
 154                 if($this->debugmode)
 155                         wfDebug("BagOStuff debug: $text\n");
 156         }
 157
 158         /**
 159          * Convert an optionally relative time to an absolute time
 160          */
 161         static function convertExpiry( $exptime ) {
 162                 if(($exptime != 0) && ($exptime < 3600*24*30)) {
 163                         return time() + $exptime;
 164                 } else {
 165                         return $exptime;
 166                 }
 167         }
 168 }
 169
 170
 171 /**
 172  * Functional versions!
 173  * This is a test of the interface, mainly. It stores things in an associative
 174  * array, which is not going to persist between program runs.
 175  *
 176  * @ingroup Cache
 177  */
 178 class HashBagOStuff extends BagOStuff {
 179         var $bag;
 180
 181         function __construct() {
 182                 $this->bag = array();
 183         }
 184
 185         function _expire($key) {
 186                 $et = $this->bag[$key][1];
 187                 if(($et == 0) || ($et > time()))
 188                         return false;
 189                 $this->delete($key);
 190                 return true;
 191         }
 192
 193         function get($key) {
 194                 if(!$this->bag[$key])
 195                         return false;
 196                 if($this->_expire($key))
 197                         return false;
 198                 return $this->bag[$key][0];
 199         }
 200
 201         function set($key,$value,$exptime=0) {
 202                 $this->bag[$key] = array( $value, BagOStuff::convertExpiry( $exptime ) );
 203         }
 204
 205         function delete($key,$time=0) {
 206                 if(!$this->bag[$key])
 207                         return false;
 208                 unset($this->bag[$key]);
 209                 return true;
 210         }
 211
 212         function keys() {
 213                 return array_keys( $this->bag );
 214         }
 215 }
 216
 217 /**
 218  * Generic class to store objects in a database
 219  *
 220  * @ingroup Cache
 221  */
 222 abstract class SqlBagOStuff extends BagOStuff {
 223         var $table;
 224         var $lastexpireall = 0;
 225
 226         /**
 227          * Constructor
 228          *
 229          * @param $tablename String: name of the table to use
 230          */
 231         function __construct($tablename = 'objectcache') {
 232                 $this->table = $tablename;
 233         }
 234
 235         function get($key) {
 236                 /* expire old entries if any */
 237                 $this->garbageCollect();
 238
 239                 $res = $this->_query(
 240                         "SELECT value,exptime FROM $0 WHERE keyname='$1'", $key);
 241                 if(!$res) {
 242                         $this->_debug("get: ** error: " . $this->_dberror($res) . " **");
 243                         return false;
 244                 }
 245                 if($row=$this->_fetchobject($res)) {
 246                         $this->_debug("get: retrieved data; exp time is " . $row->exptime);
 247                         if ( $row->exptime != $this->_maxdatetime() &&
 248                           wfTimestamp( TS_UNIX, $row->exptime ) < time() )
 249                         {
 250                                 $this->_debug("get: key has expired, deleting");
 251                                 $this->delete($key);
 252                                 return false;
 253                         }
 254                         return $this->_unserialize($this->_blobdecode($row->value));
 255                 } else {
 256                         $this->_debug('get: no matching rows');
 257                 }
 258                 return false;
 259         }
 260
 261         function set($key,$value,$exptime=0) {
 262                 if ( $this->_readonly() ) {
 263                         return false;
 264                 }
 265                 $exptime = intval($exptime);
 266                 if($exptime < 0) $exptime = 0;
 267                 if($exptime == 0) {
 268                         $exp = $this->_maxdatetime();
 269                 } else {
 270                         if($exptime < 3.16e8) # ~10 years
 271                                 $exptime += time();
 272                         $exp = $this->_fromunixtime($exptime);
 273                 }
 274                 $this->_begin();
 275                 $this->_query(
 276                         "DELETE FROM $0 WHERE keyname='$1'", $key );
 277                 $this->_doinsert($this->getTableName(), array(
 278                                         'keyname' => $key,
 279                                         'value' => $this->_blobencode($this->_serialize($value)),
 280                                         'exptime' => $exp
 281                                 ));
 282                 $this->_commit();
 283                 return true; /* ? */
 284         }
 285
 286         function delete($key,$time=0) {
 287                 if ( $this->_readonly() ) {
 288                         return false;
 289                 }
 290                 $this->_begin();
 291                 $this->_query(
 292                         "DELETE FROM $0 WHERE keyname='$1'", $key );
 293                 $this->_commit();
 294                 return true; /* ? */
 295         }
 296
 297         function keys() {
 298                 $res = $this->_query( "SELECT keyname FROM $0" );
 299                 if(!$res) {
 300                         $this->_debug("keys: ** error: " . $this->_dberror($res) . " **");
 301                         return array();
 302                 }
 303                 $result = array();
 304                 while( $row = $this->_fetchobject($res) ) {
 305                         $result[] = $row->keyname;
 306                 }
 307                 return $result;
 308         }
 309
 310         function getTableName() {
 311                 return $this->table;
 312         }
 313
 314         function _query($sql) {
 315                 $reps = func_get_args();
 316                 $reps[0] = $this->getTableName();
 317                 // ewwww
 318                 for($i=0;$i<count($reps);$i++) {
 319                         $sql = str_replace(
 320                                 '$' . $i,
 321                                 $i > 0 ? $this->_strencode($reps[$i]) : $reps[$i],
 322                                 $sql);
 323                 }
 324                 $res = $this->_doquery($sql);
 325                 if($res == false) {
 326                         $this->_debug('query failed: ' . $this->_dberror($res));
 327                 }
 328                 return $res;
 329         }
 330
 331         function _strencode($str) {
 332                 /* Protect strings in SQL */
 333                 return str_replace( "'", "''", $str );
 334         }
 335         function _blobencode($str) {
 336                 return $str;
 337         }
 338         function _blobdecode($str) {
 339                 return $str;
 340         }
 341
 342         abstract function _doinsert($table, $vals);
 343         abstract function _doquery($sql);
 344
 345         abstract function _readonly();
 346
 347         function _begin() {}
 348         function _commit() {}
 349
 350         function _freeresult($result) {
 351                 /* stub */
 352                 return false;
 353         }
 354
 355         function _dberror($result) {
 356                 /* stub */
 357                 return 'unknown error';
 358         }
 359
 360         abstract function _maxdatetime();
 361         abstract function _fromunixtime($ts);
 362
 363         function garbageCollect() {
 364                 /* Ignore 99% of requests */
 365                 if ( !mt_rand( 0, 100 ) ) {
 366                         $nowtime = time();
 367                         /* Avoid repeating the delete within a few seconds */
 368                         if ( $nowtime > ($this->lastexpireall + 1) ) {
 369                                 $this->lastexpireall = $nowtime;
 370                                 $this->expireall();
 371                         }
 372                 }
 373         }
 374
 375         function expireall() {
 376                 /* Remove any items that have expired */
 377                 if ( $this->_readonly() ) {
 378                         return false;
 379                 }
 380                 $now = $this->_fromunixtime( time() );
 381                 $this->_begin();
 382                 $this->_query( "DELETE FROM $0 WHERE exptime < '$now'" );
 383                 $this->_commit();
 384         }
 385
 386         function deleteall() {
 387                 /* Clear *all* items from cache table */
 388                 if ( $this->_readonly() ) {
 389                         return false;
 390                 }
 391                 $this->_begin();
 392                 $this->_query( "DELETE FROM $0" );
 393                 $this->_commit();
 394         }
 395
 396         /**
 397          * Serialize an object and, if possible, compress the representation.
 398          * On typical message and page data, this can provide a 3X decrease
 399          * in storage requirements.
 400          *
 401          * @param $data mixed
 402          * @return string
 403          */
 404         function _serialize( &$data ) {
 405                 $serial = serialize( $data );
 406                 if( function_exists( 'gzdeflate' ) ) {
 407                         return gzdeflate( $serial );
 408                 } else {
 409                         return $serial;
 410                 }
 411         }
 412
 413         /**
 414          * Unserialize and, if necessary, decompress an object.
 415          * @param $serial string
 416          * @return mixed
 417          */
 418         function _unserialize( $serial ) {
 419                 if( function_exists( 'gzinflate' ) ) {
 420                         $decomp = @gzinflate( $serial );
 421                         if( false !== $decomp ) {
 422                                 $serial = $decomp;
 423                         }
 424                 }
 425                 $ret = unserialize( $serial );
 426                 return $ret;
 427         }
 428 }
 429
 430 /**
 431  * Stores objects in the main database of the wiki
 432  *
 433  * @ingroup Cache
 434  */
 435 class MediaWikiBagOStuff extends SqlBagOStuff {
 436         var $tableInitialised = false;
 437         var $lb, $db;
 438
 439         function _getDB(){
 440                 if ( !isset( $this->lb ) ) {
 441                         $this->lb = wfGetLBFactory()->newMainLB();
 442                         $this->db = $this->lb->getConnection( DB_MASTER );
 443                         $this->db->clearFlag( DBO_TRX );
 444                 }
 445                 return $this->db;
 446         }
 447         function _begin() {
 448                 $this->_getDB()->begin();
 449         }
 450         function _commit() {
 451                 $this->_getDB()->commit();
 452         }
 453         function _doquery($sql) {
 454                 return $this->_getDB()->query( $sql, __METHOD__ );
 455         }
 456         function _doinsert($t, $v) {
 457                 return $this->_getDB()->insert($t, $v, __METHOD__, array( 'IGNORE' ) );
 458         }
 459         function _fetchobject($result) {
 460                 return $this->_getDB()->fetchObject($result);
 461         }
 462         function _freeresult($result) {
 463                 return $this->_getDB()->freeResult($result);
 464         }
 465         function _dberror($result) {
 466                 return $this->_getDB()->lastError();
 467         }
 468         function _maxdatetime() {
 469                 if ( time() > 0x7fffffff ) {
 470                         return $this->_fromunixtime( 1<<62 );
 471                 } else {
 472                         return $this->_fromunixtime( 0x7fffffff );
 473                 }
 474         }
 475         function _fromunixtime($ts) {
 476                 return $this->_getDB()->timestamp($ts);
 477         }
 478         /***
 479          * Note -- this should *not* check wfReadOnly().
 480          * Read-only mode has been repurposed from the original
 481          * "nothing must write to the database" to "users should not
 482          * be able to edit or alter anything user-visible".
 483          *
 484          * Backend bits like the object cache should continue
 485          * to work in this mode, otherwise things will blow up
 486          * like the message cache failing to save its state,
 487          * causing long delays (bug 11533).
 488          */
 489         function _readonly(){
 490                 return false;
 491         }
 492         function _strencode($s) {
 493                 return $this->_getDB()->strencode($s);
 494         }
 495         function _blobencode($s) {
 496                 return $this->_getDB()->encodeBlob($s);
 497         }
 498         function _blobdecode($s) {
 499                 return $this->_getDB()->decodeBlob($s);
 500         }
 501         function getTableName() {
 502                 if ( !$this->tableInitialised ) {
 503                         $dbw = $this->_getDB();
 504                         /* This is actually a hack, we should be able
 505                            to use Language classes here... or not */
 506                         if (!$dbw)
 507                                 throw new MWException("Could not connect to database");
 508                         $this->table = $dbw->tableName( $this->table );
 509                         $this->tableInitialised = true;
 510                 }
 511                 return $this->table;
 512         }
 513 }
 514
 515 /**
 516  * This is a wrapper for Turck MMCache's shared memory functions.
 517  *
 518  * You can store objects with mmcache_put() and mmcache_get(), but Turck seems
 519  * to use a weird custom serializer that randomly segfaults. So we wrap calls
 520  * with serialize()/unserialize().
 521  *
 522  * The thing I noticed about the Turck serialized data was that unlike ordinary
 523  * serialize(), it contained the names of methods, and judging by the amount of
 524  * binary data, perhaps even the bytecode of the methods themselves. It may be
 525  * that Turck's serializer is faster, so a possible future extension would be
 526  * to use it for arrays but not for objects.
 527  *
 528  * @ingroup Cache
 529  */
 530 class TurckBagOStuff extends BagOStuff {
 531         function get($key) {
 532                 $val = mmcache_get( $key );
 533                 if ( is_string( $val ) ) {
 534                         $val = unserialize( $val );
 535                 }
 536                 return $val;
 537         }
 538
 539         function set($key, $value, $exptime=0) {
 540                 mmcache_put( $key, serialize( $value ), $exptime );
 541                 return true;
 542         }
 543
 544         function delete($key, $time=0) {
 545                 mmcache_rm( $key );
 546                 return true;
 547         }
 548
 549         function lock($key, $waitTimeout = 0 ) {
 550                 mmcache_lock( $key );
 551                 return true;
 552         }
 553
 554         function unlock($key) {
 555                 mmcache_unlock( $key );
 556                 return true;
 557         }
 558 }
 559
 560 /**
 561  * This is a wrapper for APC's shared memory functions
 562  *
 563  * @ingroup Cache
 564  */
 565 class APCBagOStuff extends BagOStuff {
 566         function get($key) {
 567                 $val = apc_fetch($key);
 568                 if ( is_string( $val ) ) {
 569                         $val = unserialize( $val );
 570                 }
 571                 return $val;
 572         }
 573
 574         function set($key, $value, $exptime=0) {
 575                 apc_store($key, serialize($value), $exptime);
 576                 return true;
 577         }
 578
 579         function delete($key, $time=0) {
 580                 apc_delete($key);
 581                 return true;
 582         }
 583 }
 584
 585
 586 /**
 587  * This is a wrapper for eAccelerator's shared memory functions.
 588  *
 589  * This is basically identical to the Turck MMCache version,
 590  * mostly because eAccelerator is based on Turck MMCache.
 591  *
 592  * @ingroup Cache
 593  */
 594 class eAccelBagOStuff extends BagOStuff {
 595         function get($key) {
 596                 $val = eaccelerator_get( $key );
 597                 if ( is_string( $val ) ) {
 598                         $val = unserialize( $val );
 599                 }
 600                 return $val;
 601         }
 602
 603         function set($key, $value, $exptime=0) {
 604                 eaccelerator_put( $key, serialize( $value ), $exptime );
 605                 return true;
 606         }
 607
 608         function delete($key, $time=0) {
 609                 eaccelerator_rm( $key );
 610                 return true;
 611         }
 612
 613         function lock($key, $waitTimeout = 0 ) {
 614                 eaccelerator_lock( $key );
 615                 return true;
 616         }
 617
 618         function unlock($key) {
 619                 eaccelerator_unlock( $key );
 620                 return true;
 621         }
 622 }
 623
 624 /**
 625  * Wrapper for XCache object caching functions; identical interface
 626  * to the APC wrapper
 627  *
 628  * @ingroup Cache
 629  */
 630 class XCacheBagOStuff extends BagOStuff {
 631
 632         /**
 633          * Get a value from the XCache object cache
 634          *
 635          * @param $key String: cache key
 636          * @return mixed
 637          */
 638         public function get( $key ) {
 639                 $val = xcache_get( $key );
 640                 if( is_string( $val ) )
 641                         $val = unserialize( $val );
 642                 return $val;
 643         }
 644
 645         /**
 646          * Store a value in the XCache object cache
 647          *
 648          * @param $key String: cache key
 649          * @param $value Mixed: object to store
 650          * @param $expire Int: expiration time
 651          * @return bool
 652          */
 653         public function set( $key, $value, $expire = 0 ) {
 654                 xcache_set( $key, serialize( $value ), $expire );
 655                 return true;
 656         }
 657
 658         /**
 659          * Remove a value from the XCache object cache
 660          *
 661          * @param $key String: cache key
 662          * @param $time Int: not used in this implementation
 663          * @return bool
 664          */
 665         public function delete( $key, $time = 0 ) {
 666                 xcache_unset( $key );
 667                 return true;
 668         }
 669
 670 }
 671
 672 /**
 673  * @todo document
 674  * @ingroup Cache
 675  */
 676 class DBABagOStuff extends BagOStuff {
 677         var $mHandler, $mFile, $mReader, $mWriter, $mDisabled;
 678
 679         function __construct( $handler = 'db3', $dir = false ) {
 680                 if ( $dir === false ) {
 681                         global $wgTmpDirectory;
 682                         $dir = $wgTmpDirectory;
 683                 }
 684                 $this->mFile = "$dir/mw-cache-" . wfWikiID();
 685                 $this->mFile .= '.db';
 686                 wfDebug( __CLASS__.": using cache file {$this->mFile}\n" );
 687                 $this->mHandler = $handler;
 688         }
 689
 690         /**
 691          * Encode value and expiry for storage
 692          */
 693         function encode( $value, $expiry ) {
 694                 # Convert to absolute time
 695                 $expiry = BagOStuff::convertExpiry( $expiry );
 696                 return sprintf( '%010u', intval( $expiry ) ) . ' ' . serialize( $value );
 697         }
 698
 699         /**
 700          * @return list containing value first and expiry second
 701          */
 702         function decode( $blob ) {
 703                 if ( !is_string( $blob ) ) {
 704                         return array( null, 0 );
 705                 } else {
 706                         return array(
 707                                 unserialize( substr( $blob, 11 ) ),
 708                                 intval( substr( $blob, 0, 10 ) )
 709                         );
 710                 }
 711         }
 712
 713         function getReader() {
 714                 if ( file_exists( $this->mFile ) ) {
 715                         $handle = dba_open( $this->mFile, 'rl', $this->mHandler );
 716                 } else {
 717                         $handle = $this->getWriter();
 718                 }
 719                 if ( !$handle ) {
 720                         wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
 721                 }
 722                 return $handle;
 723         }
 724
 725         function getWriter() {
 726                 $handle = dba_open( $this->mFile, 'cl', $this->mHandler );
 727                 if ( !$handle ) {
 728                         wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
 729                 }
 730                 return $handle;
 731         }
 732
 733         function get( $key ) {
 734                 wfProfileIn( __METHOD__ );
 735                 wfDebug( __METHOD__."($key)\n" );
 736                 $handle = $this->getReader();
 737                 if ( !$handle ) {
 738                         return null;
 739                 }
 740                 $val = dba_fetch( $key, $handle );
 741                 list( $val, $expiry ) = $this->decode( $val );
 742                 # Must close ASAP because locks are held
 743                 dba_close( $handle );
 744
 745                 if ( !is_null( $val ) && $expiry && $expiry < time() ) {
 746                         # Key is expired, delete it
 747                         $handle = $this->getWriter();
 748                         dba_delete( $key, $handle );
 749                         dba_close( $handle );
 750                         wfDebug( __METHOD__.": $key expired\n" );
 751                         $val = null;
 752                 }
 753                 wfProfileOut( __METHOD__ );
 754                 return $val;
 755         }
 756
 757         function set( $key, $value, $exptime=0 ) {
 758                 wfProfileIn( __METHOD__ );
 759                 wfDebug( __METHOD__."($key)\n" );
 760                 $blob = $this->encode( $value, $exptime );
 761                 $handle = $this->getWriter();
 762                 if ( !$handle ) {
 763                         return false;
 764                 }
 765                 $ret = dba_replace( $key, $blob, $handle );
 766                 dba_close( $handle );
 767                 wfProfileOut( __METHOD__ );
 768                 return $ret;
 769         }
 770
 771         function delete( $key, $time = 0 ) {
 772                 wfProfileIn( __METHOD__ );
 773                 wfDebug( __METHOD__."($key)\n" );
 774                 $handle = $this->getWriter();
 775                 if ( !$handle ) {
 776                         return false;
 777                 }
 778                 $ret = dba_delete( $key, $handle );
 779                 dba_close( $handle );
 780                 wfProfileOut( __METHOD__ );
 781                 return $ret;
 782         }
 783
 784         function add( $key, $value, $exptime = 0 ) {
 785                 wfProfileIn( __METHOD__ );
 786                 $blob = $this->encode( $value, $exptime );
 787                 $handle = $this->getWriter();
 788                 if ( !$handle ) {
 789                         return false;
 790                 }
 791                 $ret = dba_insert( $key, $blob, $handle );
 792                 # Insert failed, check to see if it failed due to an expired key
 793                 if ( !$ret ) {
 794                         list( $value, $expiry ) = $this->decode( dba_fetch( $key, $handle ) );
 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                 wfProfileOut( __METHOD__ );
 805                 return $ret;
 806         }
 807
 808         function keys() {
 809                 $reader = $this->getReader();
 810                 $k1 = dba_firstkey( $reader );
 811                 if( !$k1 ) {
 812                         return array();
 813                 }
 814                 $result[] = $k1;
 815                 while( $key = dba_nextkey( $reader ) ) {
 816                         $result[] = $key;
 817                 }
 818                 return $result;
 819         }
 820 }