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Revision 1.43 by root, Wed Jul 9 21:00:13 2008 UTC vs.
Revision 1.53 by root, Tue Oct 21 02:21:25 2008 UTC

… …
108no warnings; 108no warnings;
109use strict 'vars'; 109use strict 'vars';
110 110
111use base 'Exporter'; 111use base 'Exporter';
112 112
113our $VERSION;
114
113BEGIN { 115BEGIN {
114 our $VERSION = '1.7'; 116 $VERSION = '1.81';
115 117
116 our @BDB_REQ = qw( 118 our @BDB_REQ = qw(
117 db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect 119 db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect
118 db_env_memp_sync db_env_memp_trickle db_env_dbrename db_env_dbremove 120 db_env_memp_sync db_env_memp_trickle db_env_dbrename db_env_dbremove
121 db_env_log_archive
119 db_open db_close db_compact db_sync db_upgrade 122 db_open db_close db_compact db_sync db_upgrade
120 db_put db_get db_pget db_del db_key_range 123 db_put db_exists db_get db_pget db_del db_key_range
121 db_txn_commit db_txn_abort db_txn_finish 124 db_txn_commit db_txn_abort db_txn_finish
122 db_c_close db_c_count db_c_put db_c_get db_c_pget db_c_del 125 db_c_close db_c_count db_c_put db_c_get db_c_pget db_c_del
123 db_sequence_open db_sequence_close 126 db_sequence_open db_sequence_close
124 db_sequence_get db_sequence_remove 127 db_sequence_get db_sequence_remove
125 ); 128 );
… …
133 136
134 require XSLoader; 137 require XSLoader;
135 XSLoader::load ("BDB", $VERSION); 138 XSLoader::load ("BDB", $VERSION);
136} 139}
137 140
138=head2 WIN32 FILENAMES/DATABASE NAME MESS
139
140Perl on Win32 supports only ASCII filenames (the reason is that it abuses
141an internal flag to store wether a filename is Unicode or ANSI, but that
142flag is used for somethign else in the perl core, so there is no way to
143detect wether a filename is ANSI or Unicode-encoded). The BDB module
144tries to work around this issue by assuming that the filename is an ANSI
145filename and BDB was built for unicode support.
146
147=head2 BERKELEYDB FUNCTIONS 141=head1 BERKELEYDB FUNCTIONS
148 142
149All of these are functions. The create functions simply return a new 143All of these are functions. The create functions simply return a new
150object and never block. All the remaining functions take an optional 144object and never block. All the remaining functions take an optional
151callback as last argument. If it is missing, then the function will be 145callback as last argument. If it is missing, then the function will be
152executed synchronously. In both cases, C<$!> will reflect the return value 146executed synchronously. In both cases, C<$!> will reflect the return value
… …
191 185
192 db_env_txn_checkpoint $db_env, 0, 0, 0, undef; 186 db_env_txn_checkpoint $db_env, 0, 0, 0, undef;
193 db_env_txn_checkpoint $db_env, 0, 0, 0; 187 db_env_txn_checkpoint $db_env, 0, 0, 0;
194 db_env_txn_checkpoint $db_env, 0; 188 db_env_txn_checkpoint $db_env, 0;
195 189
196=head3 BDB functions 190=head2 BDB functions
197 191
198Functions in the BDB namespace, exported by default: 192Functions in the BDB namespace, exported by default:
199 193
200 $env = db_env_create (U32 env_flags = 0) 194 $env = db_env_create (U32 env_flags = 0)
201 flags: RPCCLIENT 195 flags: RPCCLIENT
… …
209 atype: LOCK_DEFAULT LOCK_EXPIRE LOCK_MAXLOCKS LOCK_MAXWRITE LOCK_MINLOCKS LOCK_MINWRITE LOCK_OLDEST LOCK_RANDOM LOCK_YOUNGEST 203 atype: LOCK_DEFAULT LOCK_EXPIRE LOCK_MAXLOCKS LOCK_MAXWRITE LOCK_MINLOCKS LOCK_MINWRITE LOCK_OLDEST LOCK_RANDOM LOCK_YOUNGEST
210 db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = &PL_sv_undef) 204 db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = &PL_sv_undef)
211 db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef) 205 db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef)
212 db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = &PL_sv_undef) 206 db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = &PL_sv_undef)
213 db_env_dbrename (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, bdb_filename newname, U32 flags = 0, SV *callback = &PL_sv_undef) 207 db_env_dbrename (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, bdb_filename newname, U32 flags = 0, SV *callback = &PL_sv_undef)
208 db_env_log_archive (DB_ENV *env, SV *listp, U32 flags = 0, SV *callback = &PL_sv_undef)
214 209
215 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 210 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
216 flags: XA_CREATE 211 flags: XA_CREATE
217 212
218 db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef) 213 db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef)
… …
224 flags: FREELIST_ONLY FREE_SPACE 219 flags: FREELIST_ONLY FREE_SPACE
225 db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 220 db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef)
226 db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef) 221 db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef)
227 db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 222 db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
228 flags: APPEND NODUPDATA NOOVERWRITE 223 flags: APPEND NODUPDATA NOOVERWRITE
224 db_exists (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0) (v4.6)
229 db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 225 db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
230 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW 226 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
231 db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 227 db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
232 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW 228 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
233 db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) 229 db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef)
… …
250 db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = &PL_sv_undef) 246 db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = &PL_sv_undef)
251 flags: TXN_NOSYNC 247 flags: TXN_NOSYNC
252 db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) 248 db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
253 flags: TXN_NOSYNC 249 flags: TXN_NOSYNC
254 250
255=head4 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) 251=head3 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef)
256 252
257This is not actually a Berkeley DB function but a BDB module 253This is not actually a Berkeley DB function but a BDB module
258extension. The background for this exytension is: It is very annoying to 254extension. The background for this exytension is: It is very annoying to
259have to check every single BDB function for error returns and provide a 255have to check every single BDB function for error returns and provide a
260codepath out of your transaction. While the BDB module still makes this 256codepath out of your transaction. While the BDB module still makes this
… …
286 282
287You can use the C<< $txn->failed >> method to check wether a transaction 283You can use the C<< $txn->failed >> method to check wether a transaction
288has failed in this way and abort further processing (excluding 284has failed in this way and abort further processing (excluding
289C<db_txn_finish>). 285C<db_txn_finish>).
290 286
291=head3 DB_ENV/database environment methods 287=head2 DB_ENV/database environment methods
292 288
293Methods available on DB_ENV/$env handles: 289Methods available on DB_ENV/$env handles:
294 290
295 DESTROY (DB_ENV_ornull *env) 291 DESTROY (DB_ENV_ornull *env)
296 CODE: 292 CODE:
… …
301 $int = $env->set_tmp_dir (const char *dir) 297 $int = $env->set_tmp_dir (const char *dir)
302 $int = $env->set_lg_dir (const char *dir) 298 $int = $env->set_lg_dir (const char *dir)
303 $int = $env->set_shm_key (long shm_key) 299 $int = $env->set_shm_key (long shm_key)
304 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 300 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
305 $int = $env->set_flags (U32 flags, int onoff = 1) 301 $int = $env->set_flags (U32 flags, int onoff = 1)
306 $int = $env->log_set_config (U32 flags, int onoff = 1) [v4.7] 302 $int = $env->log_set_config (U32 flags, int onoff = 1) (v4.7)
307 $int = $env->set_intermediate_dir_mode (const char *modestring) [v4.7] 303 $int = $env->set_intermediate_dir_mode (const char *modestring) (v4.7)
308 $env->set_errfile (FILE *errfile = 0) 304 $env->set_errfile (FILE *errfile = 0)
309 $env->set_msgfile (FILE *msgfile = 0) 305 $env->set_msgfile (FILE *msgfile = 0)
310 $int = $env->set_verbose (U32 which, int onoff = 1) 306 $int = $env->set_verbose (U32 which, int onoff = 1)
311 $int = $env->set_encrypt (const char *password, U32 flags = 0) 307 $int = $env->set_encrypt (const char *password, U32 flags = 0)
312 $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT) 308 $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT)
… …
324 $int = $env->mutex_set_max (U32 max) 320 $int = $env->mutex_set_max (U32 max)
325 $int = $env->mutex_set_align (U32 align) 321 $int = $env->mutex_set_align (U32 align)
326 322
327 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) 323 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0)
328 flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC 324 flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC
329 $txn = $env->cdsgroup_begin; 325 $txn = $env->cdsgroup_begin; (v4.5)
330 326
331=head4 Example: 327=head3 Example:
332 328
333 use AnyEvent; 329 use AnyEvent;
334 use BDB; 330 use BDB;
335 331
336 our $FH; open $FH, "<&=" . BDB::poll_fileno; 332 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
348 0600; 344 0600;
349 345
350 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); 346 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
351 347
352 348
353=head3 DB/database methods 349=head2 DB/database methods
354 350
355Methods available on DB/$db handles: 351Methods available on DB/$db handles:
356 352
357 DESTROY (DB_ornull *db) 353 DESTROY (DB_ornull *db)
358 CODE: 354 CODE:
… …
384 380
385 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 381 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
386 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT 382 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
387 $seq = $db->sequence (U32 flags = 0) 383 $seq = $db->sequence (U32 flags = 0)
388 384
389=head4 Example: 385=head3 Example:
390 386
391 my $db = db_create $env; 387 my $db = db_create $env;
392 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600; 388 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600;
393 389
394 for (1..1000) { 390 for (1..1000) {
… …
401 db_del $db, undef, "key $_" for 1..1000; 397 db_del $db, undef, "key $_" for 1..1000;
402 398
403 db_sync $db; 399 db_sync $db;
404 400
405 401
406=head3 DB_TXN/transaction methods 402=head2 DB_TXN/transaction methods
407 403
408Methods available on DB_TXN/$txn handles: 404Methods available on DB_TXN/$txn handles:
409 405
410 DESTROY (DB_TXN_ornull *txn) 406 DESTROY (DB_TXN_ornull *txn)
411 CODE: 407 CODE:
… …
417 413
418 $bool = $txn->failed 414 $bool = $txn->failed
419 # see db_txn_finish documentation, above 415 # see db_txn_finish documentation, above
420 416
421 417
422=head3 DBC/cursor methods 418=head2 DBC/cursor methods
423 419
424Methods available on DBC/$dbc handles: 420Methods available on DBC/$dbc handles:
425 421
426 DESTROY (DBC_ornull *dbc) 422 DESTROY (DBC_ornull *dbc)
427 CODE: 423 CODE:
428 if (dbc) 424 if (dbc)
429 dbc->c_close (dbc); 425 dbc->c_close (dbc);
430 426
431 $int = $cursor->set_priority ($priority = PRIORITY_*) 427 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
432 428
433=head4 Example: 429=head3 Example:
434 430
435 my $c = $db->cursor; 431 my $c = $db->cursor;
436 432
437 for (;;) { 433 for (;;) {
438 db_c_get $c, my $key, my $data, BDB::NEXT; 434 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
441 } 437 }
442 438
443 db_c_close $c; 439 db_c_close $c;
444 440
445 441
446=head3 DB_SEQUENCE/sequence methods 442=head2 DB_SEQUENCE/sequence methods
447 443
448Methods available on DB_SEQUENCE/$seq handles: 444Methods available on DB_SEQUENCE/$seq handles:
449 445
450 DESTROY (DB_SEQUENCE_ornull *seq) 446 DESTROY (DB_SEQUENCE_ornull *seq)
451 CODE: 447 CODE:
… …
456 $int = $seq->set_cachesize (U32 size) 452 $int = $seq->set_cachesize (U32 size)
457 $int = $seq->set_flags (U32 flags) 453 $int = $seq->set_flags (U32 flags)
458 flags: SEQ_DEC SEQ_INC SEQ_WRAP 454 flags: SEQ_DEC SEQ_INC SEQ_WRAP
459 $int = $seq->set_range (db_seq_t min, db_seq_t max) 455 $int = $seq->set_range (db_seq_t min, db_seq_t max)
460 456
461=head4 Example: 457=head3 Example:
462 458
463 my $seq = $db->sequence; 459 my $seq = $db->sequence;
464 460
465 db_sequence_open $seq, undef, "seq", BDB::CREATE; 461 db_sequence_open $seq, undef, "seq", BDB::CREATE;
466 db_sequence_get $seq, undef, 1, my $value; 462 db_sequence_get $seq, undef, 1, my $value;
467 463
468 464
469=head2 SUPPORT FUNCTIONS 465=head1 SUPPORT FUNCTIONS
470 466
471=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 467=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
472 468
473=over 4 469=over 4
474 470
475=item $msg = BDB::strerror [$errno] 471=item $msg = BDB::strerror [$errno]
476 472
… …
563 BDB::poll_wait, BDB::poll_cb 559 BDB::poll_wait, BDB::poll_cb
564 while BDB::nreqs; 560 while BDB::nreqs;
565 561
566=back 562=back
567 563
568=head3 VERSION CHECKING 564=head2 VERSION CHECKING
569 565
570BerkeleyDB comes in various versions, many of them have minor 566BerkeleyDB comes in various versions, many of them have minor
571incompatibilities. This means that traditional "at least version x.x" 567incompatibilities. This means that traditional "at least version x.x"
572checks are often not sufficient. 568checks are often not sufficient.
573 569
574Example: set the log_autoremove option in a way compatible with <v.47 and 570Example: set the log_autoremove option in a way compatible with <v4.7 and
575v4.7. Note the use of & on the constants to avoid triggering a compiletime 571v4.7. Note the use of & on the constants to avoid triggering a compiletime
576bug when the symbol isn't available. 572bug when the symbol isn't available.
577 573
578 $DB_ENV->set_flags (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7; 574 $DB_ENV->set_flags (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7;
579 $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7; 575 $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;
… …
612=back 608=back
613 609
614=cut 610=cut
615 611
616sub VERSION { 612sub VERSION {
613 # I was dumb enough to override the VERSION method here, so let's try
614 # to fix it up.
615
616 if ($_[0] eq __PACKAGE__) {
617 $VERSION
618 } else {
617 if (@_ > 0) { 619 if (@_ > 0) {
618 return undef if VERSION_v lt $_[0]; 620 return undef if VERSION_v lt $_[0];
619 if (@_ > 1) { 621 if (@_ > 1) {
620 return undef if VERSION_v ge $_[1]; 622 return undef if VERSION_v ge $_[1];
623 }
621 } 624 }
625
626 VERSION_v
622 } 627 }
623
624 VERSION_v
625} 628}
626 629
627=head3 CONTROLLING THE NUMBER OF THREADS 630=head2 CONTROLLING THE NUMBER OF THREADS
628 631
629=over 4 632=over 4
630 633
631=item BDB::min_parallel $nthreads 634=item BDB::min_parallel $nthreads
632 635
… …
693 696
694You can still queue as many requests as you want. Therefore, 697You can still queue as many requests as you want. Therefore,
695C<max_oustsanding> is mainly useful in simple scripts (with low values) or 698C<max_oustsanding> is mainly useful in simple scripts (with low values) or
696as a stop gap to shield against fatal memory overflow (with large values). 699as a stop gap to shield against fatal memory overflow (with large values).
697 700
698=item BDB::set_sync_prepare $cb 701=item $old_cb = BDB::set_sync_prepare $cb
699 702
700Sets a callback that is called whenever a request is created without an 703Sets a callback that is called whenever a request is created without an
701explicit callback. It has to return two code references. The first is used 704explicit callback. It has to return two code references. The first is used
702as the request callback (it should save the return status), and the second 705as the request callback (it should save the return status), and the second
703is called to wait until the first callback has been called (it must set 706is called to wait until the first callback has been called (it must set
704C<$!> to the return status). 707C<$!> to the return status).
705 708
706This mechanism can be used to include BDB into other event mechanisms, 709This mechanism can be used to include BDB into other event mechanisms,
707such as L<AnyEvent::BDB> or L<Coro::BDB>. 710such as L<Coro::BDB>.
708 711
709The default implementation works like this: 712To allow other, callback-based, events to be executed while callback-less
713ones are run, you could use this sync prepare function:
710 714
711 sub { 715 sub {
712 my $status; 716 my $status;
713 ( 717 (
714 sub { $status = $! }, 718 sub { $status = $! },
715 sub { BDB::poll while !defined $status; $! = $status }, 719 sub { BDB::poll while !defined $status; $! = $status },
716 ) 720 )
717 } 721 }
718 722
719It simply blocks the process till the request has finished and then sets 723It works by polling for results till the request has finished and then
720C<$!> to the return value. This means that if you don't use a callback, 724sets C<$!> to the return value. This means that if you don't use a
721BDB will simply fall back to synchronous operations. 725callback, BDB would simply fall back to synchronous operations.
726
727By default, or if the sync prepare function is set to C<undef>, is to
728execute callback-less BDB requests in the foreground thread, setting C<$!>
729to the return value, without polling for other events.
722 730
723=back 731=back
724 732
725=head3 STATISTICAL INFORMATION 733=head2 STATISTICAL INFORMATION
726 734
727=over 4 735=over 4
728 736
729=item BDB::nreqs 737=item BDB::nreqs
730 738
… …
748 756
749=back 757=back
750 758
751=cut 759=cut
752 760
753set_sync_prepare { 761set_sync_prepare (undef);
754 my $status;
755 (
756 sub {
757 $status = $!;
758 },
759 sub {
760 BDB::poll while !defined $status;
761 $! = $status;
762 },
763 )
764};
765 762
766min_parallel 8; 763min_parallel 8;
767 764
768END { flush } 765END { flush }
769 766
7701; 7671;
771 768
769=head1 COMMON PITFALLS
770
771=head2 Unexpected Crashes
772
773Remember that, by default, BDB will execute requests in parallel, in
774somewhat random order. That means that it is easy to run a C<db_get>
775request on thesa me database as a concurrent C<db_close> request, leading
776to a crash, silent data corruption, eventually the next world war on
777terrorism.
778
779If you only ever use foreground requests (without a callback), this will
780not be an issue.
781
782=head2 Unexpected Freezes or Deadlocks
783
784Remember that, by default, BDB will execute requests in parallel, which
785easily leads to deadlocks (even concurrent put's on the same database can
786deadlock).
787
788You either need to run deadlock detection (and handle the resulting
789errors), or make sure only one process ever updates the database, ine one
790thread, e.g. by using only foreground requests (without a callback).
791
772=head2 FORK BEHAVIOUR 792=head1 FORK BEHAVIOUR
773 793
774This module should do "the right thing" when the process using it forks: 794This module should do "the right thing" when the process using it forks:
775 795
776Before the fork, BDB enters a quiescent state where no requests 796Before the fork, BDB enters a quiescent state where no requests
777can be added in other threads and no results will be processed. After 797can be added in other threads and no results will be processed. After
… …
787 807
788Win32 note: there is no fork on win32, and perls emulation of it is too 808Win32 note: there is no fork on win32, and perls emulation of it is too
789broken to be supported, so do not use BDB in a windows pseudo-fork, better 809broken to be supported, so do not use BDB in a windows pseudo-fork, better
790yet, switch to a more capable platform. 810yet, switch to a more capable platform.
791 811
792=head2 MEMORY USAGE 812=head1 MEMORY USAGE
793 813
794Per-request usage: 814Per-request usage:
795 815
796Each aio request uses - depending on your architecture - around 100-200 816Each aio request uses - depending on your architecture - around 100-200
797bytes of memory. In addition, stat requests need a stat buffer (possibly 817bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
806 826
807In the execution phase, some aio requests require more memory for 827In the execution phase, some aio requests require more memory for
808temporary buffers, and each thread requires a stack and other data 828temporary buffers, and each thread requires a stack and other data
809structures (usually around 16k-128k, depending on the OS). 829structures (usually around 16k-128k, depending on the OS).
810 830
831=head1 WIN32 FILENAMES/DATABASE NAME MESS
832
833Perl on Win32 supports only ASCII filenames (the reason is that it abuses
834an internal flag to store wether a filename is Unicode or ANSI, but that
835flag is used for somethign else in the perl core, so there is no way to
836detect wether a filename is ANSI or Unicode-encoded). The BDB module
837tries to work around this issue by assuming that the filename is an ANSI
838filename and BDB was built for unicode support.
839
811=head1 KNOWN BUGS 840=head1 KNOWN BUGS
812 841
813Known bugs will be fixed in the next release, except: 842Known bugs will be fixed in the next release, except:
814 843
815 If you use a transaction in any request, and the request returns 844 If you use a transaction in any request, and the request returns

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