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 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                 foreach ( $keys as $key ) {
  91                         $out[$key] = $this->get( $key );
  92                 }
  93                 return $out;
  94         }
  95
  96         public function set_multi( $hash, $exptime = 0 ) {
  97                 foreach ( $hash as $key => $value ) {
  98                         $this->set( $key, $value, $exptime );
  99                 }
 100         }
 101
 102         public function add( $key, $value, $exptime = 0 ) {
 103                 if ( $this->get( $key ) == false ) {
 104                         $this->set( $key, $value, $exptime );
 105                         return true;
 106                 }
 107         }
 108
 109         public function add_multi( $hash, $exptime = 0 ) {
 110                 foreach ( $hash as $key => $value ) {
 111                         $this->add( $key, $value, $exptime );
 112                 }
 113         }
 114
 115         public function delete_multi( $keys, $time = 0 ) {
 116                 foreach ( $keys as $key ) {
 117                         $this->delete( $key, $time );
 118                 }
 119         }
 120
 121         public function replace( $key, $value, $exptime = 0 ) {
 122                 if ( $this->get( $key ) !== false ) {
 123                         $this->set( $key, $value, $exptime );
 124                 }
 125         }
 126
 127         public function incr( $key, $value = 1 ) {
 128                 if ( !$this->lock( $key ) ) {
 129                         return false;
 130                 }
 131                 $value = intval( $value );
 132
 133                 $n = false;
 134                 if ( ( $n = $this->get( $key ) ) !== false ) {
 135                         $n += $value;
 136                         $this->set( $key, $n ); // exptime?
 137                 }
 138                 $this->unlock( $key );
 139                 return $n;
 140         }
 141
 142         public function decr( $key, $value = 1 ) {
 143                 return $this->incr( $key, -$value );
 144         }
 145
 146         public function debug( $text ) {
 147                 if ( $this->debugMode )
 148                         wfDebug( "BagOStuff debug: $text\n" );
 149         }
 150
 151         /**
 152          * Convert an optionally relative time to an absolute time
 153          */
 154         protected function convertExpiry( $exptime ) {
 155                 if ( ( $exptime != 0 ) && ( $exptime < 3600 * 24 * 30 ) ) {
 156                         return time() + $exptime;
 157                 } else {
 158                         return $exptime;
 159                 }
 160         }
 161 }
 162
 163
 164 /**
 165  * Functional versions!
 166  * This is a test of the interface, mainly. It stores things in an associative
 167  * array, which is not going to persist between program runs.
 168  *
 169  * @ingroup Cache
 170  */
 171 class HashBagOStuff extends BagOStuff {
 172         var $bag;
 173
 174         function __construct() {
 175                 $this->bag = array();
 176         }
 177
 178         protected function expire( $key ) {
 179                 $et = $this->bag[$key][1];
 180                 if ( ( $et == 0 ) || ( $et > time() ) ) {
 181                         return false;
 182                 }
 183                 $this->delete( $key );
 184                 return true;
 185         }
 186
 187         function get( $key ) {
 188                 if ( !isset( $this->bag[$key] ) ) {
 189                         return false;
 190                 }
 191                 if ( $this->expire( $key ) ) {
 192                         return false;
 193                 }
 194                 return $this->bag[$key][0];
 195         }
 196
 197         function set( $key, $value, $exptime = 0 ) {
 198                 $this->bag[$key] = array( $value, $this->convertExpiry( $exptime ) );
 199         }
 200
 201         function delete( $key, $time = 0 ) {
 202                 if ( !isset( $this->bag[$key] ) ) {
 203                         return false;
 204                 }
 205                 unset( $this->bag[$key] );
 206                 return true;
 207         }
 208
 209         function keys() {
 210                 return array_keys( $this->bag );
 211         }
 212 }
 213
 214 /**
 215  * Class to store objects in the database
 216  *
 217  * @ingroup Cache
 218  */
 219 class SqlBagOStuff extends BagOStuff {
 220         var $lb, $db;
 221         var $lastExpireAll = 0;
 222
 223         protected function getDB() {
 224                 if ( !isset( $this->lb ) ) {
 225                         $this->lb = wfGetLBFactory()->newMainLB();
 226                         $this->db = $this->lb->getConnection( DB_MASTER );
 227                         $this->db->clearFlag( DBO_TRX );
 228                 }
 229                 return $this->db;
 230         }
 231
 232         public function get( $key ) {
 233                 # expire old entries if any
 234                 $this->garbageCollect();
 235                 $db = $this->getDB();
 236                 $row = $db->selectRow( 'objectcache', array( 'value', 'exptime' ),
 237                         array( 'keyname' => $key ), __METHOD__ );
 238                 if ( !$row ) {
 239                         $this->debug( 'get: no matching rows' );
 240                         return false;
 241                 }
 242
 243                 $this->debug( "get: retrieved data; expiry time is " . $row->exptime );
 244                 if ( $this->isExpired( $row->exptime ) ) {
 245                         $this->debug( "get: key has expired, deleting" );
 246                         try {
 247                                 $db->begin();
 248                                 # Put the expiry time in the WHERE condition to avoid deleting a
 249                                 # newly-inserted value
 250                                 $db->delete( 'objectcache',
 251                                         array(
 252                                                 'keyname' => $key,
 253                                                 'exptime' => $row->exptime
 254                                         ), __METHOD__ );
 255                                 $db->commit();
 256                         } catch ( DBQueryError $e ) {
 257                                 $this->handleWriteError( $e );
 258                         }
 259                         return false;
 260                 }
 261                 return $this->unserialize( $db->decodeBlob( $row->value ) );
 262         }
 263
 264         public function set( $key, $value, $exptime = 0 ) {
 265                 $db = $this->getDB();
 266                 $exptime = intval( $exptime );
 267                 if ( $exptime < 0 ) $exptime = 0;
 268                 if ( $exptime == 0 ) {
 269                         $encExpiry = $this->getMaxDateTime();
 270                 } else {
 271                         if ( $exptime < 3.16e8 ) # ~10 years
 272                                 $exptime += time();
 273                         $encExpiry = $db->timestamp( $exptime );
 274                 }
 275                 try {
 276                         $db->begin();
 277                         $db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
 278                         $db->insert( 'objectcache',
 279                                 array(
 280                                         'keyname' => $key,
 281                                         'value' => $db->encodeBlob( $this->serialize( $value ) ),
 282                                         'exptime' => $encExpiry
 283                                 ), __METHOD__ );
 284                         $db->commit();
 285                 } catch ( DBQueryError $e ) {
 286                         $this->handleWriteError( $e );
 287                         return false;
 288                 }
 289                 return true;
 290         }
 291
 292         public function delete( $key, $time = 0 ) {
 293                 $db = $this->getDB();
 294                 try {
 295                         $db->begin();
 296                         $db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
 297                         $db->commit();
 298                 } catch ( DBQueryError $e ) {
 299                         $this->handleWriteError( $e );
 300                         return false;
 301                 }
 302                 return true;
 303         }
 304
 305         public function incr( $key, $step = 1 ) {
 306                 $db = $this->getDB();
 307                 $step = intval( $step );
 308
 309                 try {
 310                         $db->begin();
 311                         $row = $db->selectRow( 'objectcache', array( 'value', 'exptime' ),
 312                                 array( 'keyname' => $key ), __METHOD__, array( 'FOR UPDATE' ) );
 313                         if ( $row === false ) {
 314                                 // Missing
 315                                 $db->commit();
 316                                 return false;
 317                         }
 318                         $db->delete( 'objectcache', array( 'keyname' => $key ), __METHOD__ );
 319                         if ( $this->isExpired( $row->exptime ) ) {
 320                                 // Expired, do not reinsert
 321                                 $db->commit();
 322                                 return false;
 323                         }
 324
 325                         $oldValue = intval( $this->unserialize( $db->decodeBlob( $row->value ) ) );
 326                         $newValue = $oldValue + $step;
 327                         $db->insert( 'objectcache',
 328                                 array(
 329                                         'keyname' => $key,
 330                                         'value' => $db->encodeBlob( $this->serialize( $newValue ) ),
 331                                         'exptime' => $row->exptime
 332                                 ), __METHOD__ );
 333                         $db->commit();
 334                 } catch ( DBQueryError $e ) {
 335                         $this->handleWriteError( $e );
 336                         return false;
 337                 }
 338                 return $newValue;
 339         }
 340
 341         public function keys() {
 342                 $db = $this->getDB();
 343                 $res = $db->select( 'objectcache', array( 'keyname' ), false, __METHOD__ );
 344                 $result = array();
 345                 foreach ( $res as $row ) {
 346                         $result[] = $row->keyname;
 347                 }
 348                 return $result;
 349         }
 350
 351         protected function isExpired( $exptime ) {
 352                 return $exptime != $this->getMaxDateTime() && wfTimestamp( TS_UNIX, $exptime ) < time();
 353         }
 354
 355         protected function getMaxDateTime() {
 356                 if ( time() > 0x7fffffff ) {
 357                         return $this->getDB()->timestamp( 1 << 62 );
 358                 } else {
 359                         return $this->getDB()->timestamp( 0x7fffffff );
 360                 }
 361         }
 362
 363         protected function garbageCollect() {
 364                 /* Ignore 99% of requests */
 365                 if ( !mt_rand( 0, 100 ) ) {
 366                         $now = time();
 367                         /* Avoid repeating the delete within a few seconds */
 368                         if ( $now > ( $this->lastExpireAll + 1 ) ) {
 369                                 $this->lastExpireAll = $now;
 370                                 $this->expireAll();
 371                         }
 372                 }
 373         }
 374
 375         public function expireAll() {
 376                 $db = $this->getDB();
 377                 $now = $db->timestamp();
 378                 try {
 379                         $db->begin();
 380                         $db->delete( 'objectcache', array( 'exptime < ' . $db->addQuotes( $now ) ), __METHOD__ );
 381                         $db->commit();
 382                 } catch ( DBQueryError $e ) {
 383                         $this->handleWriteError( $e );
 384                 }
 385         }
 386
 387         public function deleteAll() {
 388                 $db = $this->getDB();
 389                 try {
 390                         $db->begin();
 391                         $db->delete( 'objectcache', '*', __METHOD__ );
 392                         $db->commit();
 393                 } catch ( DBQueryError $e ) {
 394                         $this->handleWriteError( $e );
 395                 }
 396         }
 397
 398         /**
 399          * Serialize an object and, if possible, compress the representation.
 400          * On typical message and page data, this can provide a 3X decrease
 401          * in storage requirements.
 402          *
 403          * @param $data mixed
 404          * @return string
 405          */
 406         protected function serialize( &$data ) {
 407                 $serial = serialize( $data );
 408                 if ( function_exists( 'gzdeflate' ) ) {
 409                         return gzdeflate( $serial );
 410                 } else {
 411                         return $serial;
 412                 }
 413         }
 414
 415         /**
 416          * Unserialize and, if necessary, decompress an object.
 417          * @param $serial string
 418          * @return mixed
 419          */
 420         protected function unserialize( $serial ) {
 421                 if ( function_exists( 'gzinflate' ) ) {
 422                         $decomp = @gzinflate( $serial );
 423                         if ( false !== $decomp ) {
 424                                 $serial = $decomp;
 425                         }
 426                 }
 427                 $ret = unserialize( $serial );
 428                 return $ret;
 429         }
 430
 431         /**
 432          * Handle a DBQueryError which occurred during a write operation.
 433          * Ignore errors which are due to a read-only database, rethrow others.
 434          */
 435         protected function handleWriteError( $exception ) {
 436                 $db = $this->getDB();
 437                 if ( !$db->wasReadOnlyError() ) {
 438                         throw $exception;
 439                 }
 440                 try {
 441                         $db->rollback();
 442                 } catch ( DBQueryError $e ) {
 443                 }
 444                 wfDebug( __METHOD__ . ": ignoring query error\n" );
 445                 $db->ignoreErrors( false );
 446         }
 447 }
 448
 449 /**
 450  * Backwards compatibility alias
 451  */
 452 class MediaWikiBagOStuff extends SqlBagOStuff {}
 453
 454 /**
 455  * This is a wrapper for Turck MMCache's shared memory functions.
 456  *
 457  * You can store objects with mmcache_put() and mmcache_get(), but Turck seems
 458  * to use a weird custom serializer that randomly segfaults. So we wrap calls
 459  * with serialize()/unserialize().
 460  *
 461  * The thing I noticed about the Turck serialized data was that unlike ordinary
 462  * serialize(), it contained the names of methods, and judging by the amount of
 463  * binary data, perhaps even the bytecode of the methods themselves. It may be
 464  * that Turck's serializer is faster, so a possible future extension would be
 465  * to use it for arrays but not for objects.
 466  *
 467  * @ingroup Cache
 468  */
 469 class TurckBagOStuff extends BagOStuff {
 470         public function get( $key ) {
 471                 $val = mmcache_get( $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                 mmcache_put( $key, serialize( $value ), $exptime );
 480                 return true;
 481         }
 482
 483         public function delete( $key, $time = 0 ) {
 484                 mmcache_rm( $key );
 485                 return true;
 486         }
 487
 488         public function lock( $key, $waitTimeout = 0 ) {
 489                 mmcache_lock( $key );
 490                 return true;
 491         }
 492
 493         public function unlock( $key ) {
 494                 mmcache_unlock( $key );
 495                 return true;
 496         }
 497 }
 498
 499 /**
 500  * This is a wrapper for APC's shared memory functions
 501  *
 502  * @ingroup Cache
 503  */
 504 class APCBagOStuff extends BagOStuff {
 505         public function get( $key ) {
 506                 $val = apc_fetch( $key );
 507                 if ( is_string( $val ) ) {
 508                         $val = unserialize( $val );
 509                 }
 510                 return $val;
 511         }
 512
 513         public function set( $key, $value, $exptime = 0 ) {
 514                 apc_store( $key, serialize( $value ), $exptime );
 515                 return true;
 516         }
 517
 518         public function delete( $key, $time = 0 ) {
 519                 apc_delete( $key );
 520                 return true;
 521         }
 522 }
 523
 524
 525 /**
 526  * This is a wrapper for eAccelerator's shared memory functions.
 527  *
 528  * This is basically identical to the Turck MMCache version,
 529  * mostly because eAccelerator is based on Turck MMCache.
 530  *
 531  * @ingroup Cache
 532  */
 533 class eAccelBagOStuff extends BagOStuff {
 534         public function get( $key ) {
 535                 $val = eaccelerator_get( $key );
 536                 if ( is_string( $val ) ) {
 537                         $val = unserialize( $val );
 538                 }
 539                 return $val;
 540         }
 541
 542         public function set( $key, $value, $exptime = 0 ) {
 543                 eaccelerator_put( $key, serialize( $value ), $exptime );
 544                 return true;
 545         }
 546
 547         public function delete( $key, $time = 0 ) {
 548                 eaccelerator_rm( $key );
 549                 return true;
 550         }
 551
 552         public function lock( $key, $waitTimeout = 0 ) {
 553                 eaccelerator_lock( $key );
 554                 return true;
 555         }
 556
 557         public function unlock( $key ) {
 558                 eaccelerator_unlock( $key );
 559                 return true;
 560         }
 561 }
 562
 563 /**
 564  * Wrapper for XCache object caching functions; identical interface
 565  * to the APC wrapper
 566  *
 567  * @ingroup Cache
 568  */
 569 class XCacheBagOStuff extends BagOStuff {
 570
 571         /**
 572          * Get a value from the XCache object cache
 573          *
 574          * @param $key String: cache key
 575          * @return mixed
 576          */
 577         public function get( $key ) {
 578                 $val = xcache_get( $key );
 579                 if ( is_string( $val ) )
 580                         $val = unserialize( $val );
 581                 return $val;
 582         }
 583
 584         /**
 585          * Store a value in the XCache object cache
 586          *
 587          * @param $key String: cache key
 588          * @param $value Mixed: object to store
 589          * @param $expire Int: expiration time
 590          * @return bool
 591          */
 592         public function set( $key, $value, $expire = 0 ) {
 593                 xcache_set( $key, serialize( $value ), $expire );
 594                 return true;
 595         }
 596
 597         /**
 598          * Remove a value from the XCache object cache
 599          *
 600          * @param $key String: cache key
 601          * @param $time Int: not used in this implementation
 602          * @return bool
 603          */
 604         public function delete( $key, $time = 0 ) {
 605                 xcache_unset( $key );
 606                 return true;
 607         }
 608
 609 }
 610
 611 /**
 612  * Cache that uses DBA as a backend.
 613  * Slow due to the need to constantly open and close the file to avoid holding
 614  * writer locks. Intended for development use only,  as a memcached workalike
 615  * for systems that don't have it.
 616  *
 617  * @ingroup Cache
 618  */
 619 class DBABagOStuff extends BagOStuff {
 620         var $mHandler, $mFile, $mReader, $mWriter, $mDisabled;
 621
 622         public function __construct( $handler = 'db3', $dir = false ) {
 623                 if ( $dir === false ) {
 624                         global $wgTmpDirectory;
 625                         $dir = $wgTmpDirectory;
 626                 }
 627                 $this->mFile = "$dir/mw-cache-" . wfWikiID();
 628                 $this->mFile .= '.db';
 629                 wfDebug( __CLASS__ . ": using cache file {$this->mFile}\n" );
 630                 $this->mHandler = $handler;
 631         }
 632
 633         /**
 634          * Encode value and expiry for storage
 635          */
 636         function encode( $value, $expiry ) {
 637                 # Convert to absolute time
 638                 $expiry = $this->convertExpiry( $expiry );
 639                 return sprintf( '%010u', intval( $expiry ) ) . ' ' . serialize( $value );
 640         }
 641
 642         /**
 643          * @return list containing value first and expiry second
 644          */
 645         function decode( $blob ) {
 646                 if ( !is_string( $blob ) ) {
 647                         return array( null, 0 );
 648                 } else {
 649                         return array(
 650                                 unserialize( substr( $blob, 11 ) ),
 651                                 intval( substr( $blob, 0, 10 ) )
 652                         );
 653                 }
 654         }
 655
 656         function getReader() {
 657                 if ( file_exists( $this->mFile ) ) {
 658                         $handle = dba_open( $this->mFile, 'rl', $this->mHandler );
 659                 } else {
 660                         $handle = $this->getWriter();
 661                 }
 662                 if ( !$handle ) {
 663                         wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
 664                 }
 665                 return $handle;
 666         }
 667
 668         function getWriter() {
 669                 $handle = dba_open( $this->mFile, 'cl', $this->mHandler );
 670                 if ( !$handle ) {
 671                         wfDebug( "Unable to open DBA cache file {$this->mFile}\n" );
 672                 }
 673                 return $handle;
 674         }
 675
 676         function get( $key ) {
 677                 wfProfileIn( __METHOD__ );
 678                 wfDebug( __METHOD__ . "($key)\n" );
 679                 $handle = $this->getReader();
 680                 if ( !$handle ) {
 681                         return null;
 682                 }
 683                 $val = dba_fetch( $key, $handle );
 684                 list( $val, $expiry ) = $this->decode( $val );
 685                 # Must close ASAP because locks are held
 686                 dba_close( $handle );
 687
 688                 if ( !is_null( $val ) && $expiry && $expiry < time() ) {
 689                         # Key is expired, delete it
 690                         $handle = $this->getWriter();
 691                         dba_delete( $key, $handle );
 692                         dba_close( $handle );
 693                         wfDebug( __METHOD__ . ": $key expired\n" );
 694                         $val = null;
 695                 }
 696                 wfProfileOut( __METHOD__ );
 697                 return $val;
 698         }
 699
 700         function set( $key, $value, $exptime = 0 ) {
 701                 wfProfileIn( __METHOD__ );
 702                 wfDebug( __METHOD__ . "($key)\n" );
 703                 $blob = $this->encode( $value, $exptime );
 704                 $handle = $this->getWriter();
 705                 if ( !$handle ) {
 706                         return false;
 707                 }
 708                 $ret = dba_replace( $key, $blob, $handle );
 709                 dba_close( $handle );
 710                 wfProfileOut( __METHOD__ );
 711                 return $ret;
 712         }
 713
 714         function delete( $key, $time = 0 ) {
 715                 wfProfileIn( __METHOD__ );
 716                 wfDebug( __METHOD__ . "($key)\n" );
 717                 $handle = $this->getWriter();
 718                 if ( !$handle ) {
 719                         return false;
 720                 }
 721                 $ret = dba_delete( $key, $handle );
 722                 dba_close( $handle );
 723                 wfProfileOut( __METHOD__ );
 724                 return $ret;
 725         }
 726
 727         function add( $key, $value, $exptime = 0 ) {
 728                 wfProfileIn( __METHOD__ );
 729                 $blob = $this->encode( $value, $exptime );
 730                 $handle = $this->getWriter();
 731                 if ( !$handle ) {
 732                         return false;
 733                 }
 734                 $ret = dba_insert( $key, $blob, $handle );
 735                 # Insert failed, check to see if it failed due to an expired key
 736                 if ( !$ret ) {
 737                         list( $value, $expiry ) = $this->decode( dba_fetch( $key, $handle ) );
 738                         if ( $expiry < time() ) {
 739                                 # Yes expired, delete and try again
 740                                 dba_delete( $key, $handle );
 741                                 $ret = dba_insert( $key, $blob, $handle );
 742                                 # This time if it failed then it will be handled by the caller like any other race
 743                         }
 744                 }
 745
 746                 dba_close( $handle );
 747                 wfProfileOut( __METHOD__ );
 748                 return $ret;
 749         }
 750
 751         function keys() {
 752                 $reader = $this->getReader();
 753                 $k1 = dba_firstkey( $reader );
 754                 if ( !$k1 ) {
 755                         return array();
 756                 }
 757                 $result[] = $k1;
 758                 while ( $key = dba_nextkey( $reader ) ) {
 759                         $result[] = $key;
 760                 }
 761                 return $result;
 762         }
 763 }