ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/BDB/BDB.pm
(Generate patch)

Comparing BDB/BDB.pm (file contents):
Revision 1.49 by root, Thu Sep 25 13:30:14 2008 UTC vs.
Revision 1.58 by root, Fri Jul 17 04:18:49 2009 UTC

… …
27 db_sync $db; 27 db_sync $db;
28 28
29 # when you also use Coro, management is easy: 29 # when you also use Coro, management is easy:
30 use Coro::BDB; 30 use Coro::BDB;
31 31
32 # automatic event loop intergration with AnyEvent: 32 # automatic event loop integration with AnyEvent:
33 use AnyEvent::BDB; 33 use AnyEvent::BDB;
34 34
35 # automatic result processing with EV: 35 # automatic result processing with EV:
36 my $WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb; 36 my $WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb;
37 37
… …
103 103
104=cut 104=cut
105 105
106package BDB; 106package BDB;
107 107
108no warnings; 108use common::sense;
109use strict 'vars';
110 109
111use base 'Exporter'; 110use base 'Exporter';
112 111
113our $VERSION; 112our $VERSION;
114 113
115BEGIN { 114BEGIN {
116 $VERSION = '1.8'; 115 $VERSION = '1.84';
117 116
118 our @BDB_REQ = qw( 117 our @BDB_REQ = qw(
119 db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect 118 db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect
120 db_env_memp_sync db_env_memp_trickle db_env_dbrename db_env_dbremove 119 db_env_memp_sync db_env_memp_trickle db_env_dbrename db_env_dbremove
120 db_env_log_archive
121 db_open db_close db_compact db_sync db_upgrade 121 db_open db_close db_compact db_sync db_verify db_upgrade
122 db_put db_exists db_get db_pget db_del db_key_range 122 db_put db_exists db_get db_pget db_del db_key_range
123 db_txn_commit db_txn_abort db_txn_finish 123 db_txn_commit db_txn_abort db_txn_finish
124 db_c_close db_c_count db_c_put db_c_get db_c_pget db_c_del 124 db_c_close db_c_count db_c_put db_c_get db_c_pget db_c_del
125 db_sequence_open db_sequence_close 125 db_sequence_open db_sequence_close
126 db_sequence_get db_sequence_remove 126 db_sequence_get db_sequence_remove
… …
135 135
136 require XSLoader; 136 require XSLoader;
137 XSLoader::load ("BDB", $VERSION); 137 XSLoader::load ("BDB", $VERSION);
138} 138}
139 139
140=head2 WIN32 FILENAMES/DATABASE NAME MESS
141
142Perl on Win32 supports only ASCII filenames (the reason is that it abuses
143an internal flag to store wether a filename is Unicode or ANSI, but that
144flag is used for somethign else in the perl core, so there is no way to
145detect wether a filename is ANSI or Unicode-encoded). The BDB module
146tries to work around this issue by assuming that the filename is an ANSI
147filename and BDB was built for unicode support.
148
149=head2 BERKELEYDB FUNCTIONS 140=head1 BERKELEYDB FUNCTIONS
150 141
151All of these are functions. The create functions simply return a new 142All of these are functions. The create functions simply return a new
152object and never block. All the remaining functions take an optional 143object and never block. All the remaining functions take an optional
153callback as last argument. If it is missing, then the function will be 144callback as last argument. If it is missing, then the function will be
154executed synchronously. In both cases, C<$!> will reflect the return value 145executed synchronously. In both cases, C<$!> will reflect the return value
… …
193 184
194 db_env_txn_checkpoint $db_env, 0, 0, 0, undef; 185 db_env_txn_checkpoint $db_env, 0, 0, 0, undef;
195 db_env_txn_checkpoint $db_env, 0, 0, 0; 186 db_env_txn_checkpoint $db_env, 0, 0, 0;
196 db_env_txn_checkpoint $db_env, 0; 187 db_env_txn_checkpoint $db_env, 0;
197 188
198=head3 BDB functions 189=head2 BDB functions
199 190
200Functions in the BDB namespace, exported by default: 191Functions in the BDB namespace, exported by default:
201 192
202 $env = db_env_create (U32 env_flags = 0) 193 $env = db_env_create (U32 env_flags = 0)
203 flags: RPCCLIENT 194 flags: RPCCLIENT
204 195
205 db_env_open (DB_ENV *env, bdb_filename db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef) 196 db_env_open (DB_ENV *env, bdb_filename db_home, U32 open_flags, int mode, SV *callback = 0)
206 open_flags: INIT_CDB INIT_LOCK INIT_LOG INIT_MPOOL INIT_REP INIT_TXN RECOVER RECOVER_FATAL USE_ENVIRON USE_ENVIRON_ROOT CREATE LOCKDOWN PRIVATE REGISTER SYSTEM_MEM 197 open_flags: INIT_CDB INIT_LOCK INIT_LOG INIT_MPOOL INIT_REP INIT_TXN RECOVER RECOVER_FATAL USE_ENVIRON USE_ENVIRON_ROOT CREATE LOCKDOWN PRIVATE REGISTER SYSTEM_MEM
207 db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef) 198 db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = 0)
208 db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef) 199 db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = 0)
209 flags: FORCE 200 flags: FORCE
210 db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef) 201 db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = 0)
211 atype: LOCK_DEFAULT LOCK_EXPIRE LOCK_MAXLOCKS LOCK_MAXWRITE LOCK_MINLOCKS LOCK_MINWRITE LOCK_OLDEST LOCK_RANDOM LOCK_YOUNGEST 202 atype: LOCK_DEFAULT LOCK_EXPIRE LOCK_MAXLOCKS LOCK_MAXWRITE LOCK_MINLOCKS LOCK_MINWRITE LOCK_OLDEST LOCK_RANDOM LOCK_YOUNGEST
212 db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = &PL_sv_undef) 203 db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = 0)
213 db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef) 204 db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = 0)
214 db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = &PL_sv_undef) 205 db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = 0)
215 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) 206 db_env_dbrename (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, bdb_filename newname, U32 flags = 0, SV *callback = 0)
207 db_env_log_archive (DB_ENV *env, SV *listp, U32 flags = 0, SV *callback = 0)
216 208
217 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 209 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
218 flags: XA_CREATE 210 flags: XA_CREATE
219 211
220 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) 212 db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = 0)
221 flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE 213 flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE
222 db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 214 db_close (DB *db, U32 flags = 0, SV *callback = 0)
223 flags: DB_NOSYNC 215 flags: DB_NOSYNC
216 db_verify (DB *db, bdb_filename file, bdb_filename database = 0, SV *dummy = 0, U32 flags = 0, SV *callback = 0)
224 db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = &PL_sv_undef) 217 db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = 0)
225 db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = &PL_sv_undef) 218 db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = 0)
226 flags: FREELIST_ONLY FREE_SPACE 219 flags: FREELIST_ONLY FREE_SPACE
227 db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 220 db_sync (DB *db, U32 flags = 0, SV *callback = 0)
228 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 = 0)
229 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 = 0)
230 flags: APPEND NODUPDATA NOOVERWRITE 223 flags: APPEND NODUPDATA NOOVERWRITE
231 db_exists (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0) (v4.6) 224 db_exists (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0) (v4.6)
232 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 = 0)
233 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
234 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 = 0)
235 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
236 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 = 0)
237 db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) 230 db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = 0)
238 flags: TXN_NOSYNC TXN_SYNC 231 flags: TXN_NOSYNC TXN_SYNC
239 db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef) 232 db_txn_abort (DB_TXN *txn, SV *callback = 0)
240 233
241 db_c_close (DBC *dbc, SV *callback = &PL_sv_undef) 234 db_c_close (DBC *dbc, SV *callback = 0)
242 db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = &PL_sv_undef) 235 db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = 0)
243 db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 236 db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
244 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA 237 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA
245 db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 238 db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
246 flags: CURRENT FIRST GET_BOTH GET_BOTH_RANGE GET_RECNO JOIN_ITEM LAST NEXT NEXT_DUP NEXT_NODUP PREV PREV_DUP PREV_NODUP SET SET_RANGE SET_RECNO READ_UNCOMMITTED MULTIPLE MULTIPLE_KEY RMW 239 flags: CURRENT FIRST GET_BOTH GET_BOTH_RANGE GET_RECNO JOIN_ITEM LAST NEXT NEXT_DUP NEXT_NODUP PREV PREV_DUP PREV_NODUP SET SET_RANGE SET_RECNO READ_UNCOMMITTED MULTIPLE MULTIPLE_KEY RMW
247 db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 240 db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0)
248 db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef) 241 db_c_del (DBC *dbc, U32 flags = 0, SV *callback = 0)
249 242
250 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) 243 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = 0)
251 flags: CREATE EXCL 244 flags: CREATE EXCL
252 db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef) 245 db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = 0)
253 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 = 0)
254 flags: TXN_NOSYNC 247 flags: TXN_NOSYNC
255 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 = 0)
256 flags: TXN_NOSYNC 249 flags: TXN_NOSYNC
257 250
258=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 = 0)
259 252
260This is not actually a Berkeley DB function but a BDB module 253This is not actually a Berkeley DB function but a BDB module
261extension. The background for this exytension is: It is very annoying to 254extension. The background for this exytension is: It is very annoying to
262have 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
263codepath out of your transaction. While the BDB module still makes this 256codepath out of your transaction. While the BDB module still makes this
… …
289 282
290You can use the C<< $txn->failed >> method to check wether a transaction 283You can use the C<< $txn->failed >> method to check wether a transaction
291has failed in this way and abort further processing (excluding 284has failed in this way and abort further processing (excluding
292C<db_txn_finish>). 285C<db_txn_finish>).
293 286
287
294=head3 DB_ENV/database environment methods 288=head2 DB_ENV/database environment methods
295 289
296Methods available on DB_ENV/$env handles: 290Methods available on DB_ENV/$env handles:
297 291
298 DESTROY (DB_ENV_ornull *env) 292 DESTROY (DB_ENV_ornull *env)
299 CODE: 293 CODE:
… …
329 323
330 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) 324 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0)
331 flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC 325 flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC
332 $txn = $env->cdsgroup_begin; (v4.5) 326 $txn = $env->cdsgroup_begin; (v4.5)
333 327
334=head4 Example: 328=head3 Example:
335 329
336 use AnyEvent; 330 use AnyEvent;
337 use BDB; 331 use BDB;
338 332
339 our $FH; open $FH, "<&=" . BDB::poll_fileno; 333 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
351 0600; 345 0600;
352 346
353 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); 347 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
354 348
355 349
356=head3 DB/database methods 350=head2 DB/database methods
357 351
358Methods available on DB/$db handles: 352Methods available on DB/$db handles:
359 353
360 DESTROY (DB_ornull *db) 354 DESTROY (DB_ornull *db)
361 CODE: 355 CODE:
… …
387 381
388 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 382 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
389 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT 383 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
390 $seq = $db->sequence (U32 flags = 0) 384 $seq = $db->sequence (U32 flags = 0)
391 385
392=head4 Example: 386=head3 Example:
393 387
394 my $db = db_create $env; 388 my $db = db_create $env;
395 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600; 389 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600;
396 390
397 for (1..1000) { 391 for (1..1000) {
… …
404 db_del $db, undef, "key $_" for 1..1000; 398 db_del $db, undef, "key $_" for 1..1000;
405 399
406 db_sync $db; 400 db_sync $db;
407 401
408 402
409=head3 DB_TXN/transaction methods 403=head2 DB_TXN/transaction methods
410 404
411Methods available on DB_TXN/$txn handles: 405Methods available on DB_TXN/$txn handles:
412 406
413 DESTROY (DB_TXN_ornull *txn) 407 DESTROY (DB_TXN_ornull *txn)
414 CODE: 408 CODE:
… …
420 414
421 $bool = $txn->failed 415 $bool = $txn->failed
422 # see db_txn_finish documentation, above 416 # see db_txn_finish documentation, above
423 417
424 418
425=head3 DBC/cursor methods 419=head2 DBC/cursor methods
426 420
427Methods available on DBC/$dbc handles: 421Methods available on DBC/$dbc handles:
428 422
429 DESTROY (DBC_ornull *dbc) 423 DESTROY (DBC_ornull *dbc)
430 CODE: 424 CODE:
431 if (dbc) 425 if (dbc)
432 dbc->c_close (dbc); 426 dbc->c_close (dbc);
433 427
434 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6) 428 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
435 429
436=head4 Example: 430=head3 Example:
437 431
438 my $c = $db->cursor; 432 my $c = $db->cursor;
439 433
440 for (;;) { 434 for (;;) {
441 db_c_get $c, my $key, my $data, BDB::NEXT; 435 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
444 } 438 }
445 439
446 db_c_close $c; 440 db_c_close $c;
447 441
448 442
449=head3 DB_SEQUENCE/sequence methods 443=head2 DB_SEQUENCE/sequence methods
450 444
451Methods available on DB_SEQUENCE/$seq handles: 445Methods available on DB_SEQUENCE/$seq handles:
452 446
453 DESTROY (DB_SEQUENCE_ornull *seq) 447 DESTROY (DB_SEQUENCE_ornull *seq)
454 CODE: 448 CODE:
… …
459 $int = $seq->set_cachesize (U32 size) 453 $int = $seq->set_cachesize (U32 size)
460 $int = $seq->set_flags (U32 flags) 454 $int = $seq->set_flags (U32 flags)
461 flags: SEQ_DEC SEQ_INC SEQ_WRAP 455 flags: SEQ_DEC SEQ_INC SEQ_WRAP
462 $int = $seq->set_range (db_seq_t min, db_seq_t max) 456 $int = $seq->set_range (db_seq_t min, db_seq_t max)
463 457
464=head4 Example: 458=head3 Example:
465 459
466 my $seq = $db->sequence; 460 my $seq = $db->sequence;
467 461
468 db_sequence_open $seq, undef, "seq", BDB::CREATE; 462 db_sequence_open $seq, undef, "seq", BDB::CREATE;
469 db_sequence_get $seq, undef, 1, my $value; 463 db_sequence_get $seq, undef, 1, my $value;
470 464
471 465
472=head2 SUPPORT FUNCTIONS 466=head1 SUPPORT FUNCTIONS
473 467
474=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 468=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
475 469
476=over 4 470=over 4
477 471
478=item $msg = BDB::strerror [$errno] 472=item $msg = BDB::strerror [$errno]
479 473
… …
566 BDB::poll_wait, BDB::poll_cb 560 BDB::poll_wait, BDB::poll_cb
567 while BDB::nreqs; 561 while BDB::nreqs;
568 562
569=back 563=back
570 564
571=head3 VERSION CHECKING 565=head2 VERSION CHECKING
572 566
573BerkeleyDB comes in various versions, many of them have minor 567BerkeleyDB comes in various versions, many of them have minor
574incompatibilities. This means that traditional "at least version x.x" 568incompatibilities. This means that traditional "at least version x.x"
575checks are often not sufficient. 569checks are often not sufficient.
576 570
… …
632 626
633 VERSION_v 627 VERSION_v
634 } 628 }
635} 629}
636 630
637=head3 CONTROLLING THE NUMBER OF THREADS 631=head2 CONTROLLING THE NUMBER OF THREADS
638 632
639=over 4 633=over 4
640 634
641=item BDB::min_parallel $nthreads 635=item BDB::min_parallel $nthreads
642 636
… …
703 697
704You can still queue as many requests as you want. Therefore, 698You can still queue as many requests as you want. Therefore,
705C<max_oustsanding> is mainly useful in simple scripts (with low values) or 699C<max_oustsanding> is mainly useful in simple scripts (with low values) or
706as a stop gap to shield against fatal memory overflow (with large values). 700as a stop gap to shield against fatal memory overflow (with large values).
707 701
708=item BDB::set_sync_prepare $cb 702=item $old_cb = BDB::set_sync_prepare $cb
709 703
710Sets a callback that is called whenever a request is created without an 704Sets a callback that is called whenever a request is created without an
711explicit callback. It has to return two code references. The first is used 705explicit callback. It has to return two code references. The first is used
712as the request callback (it should save the return status), and the second 706as the request callback (it should save the return status), and the second
713is called to wait until the first callback has been called (it must set 707is called to wait until the first callback has been called (it must set
714C<$!> to the return status). 708C<$!> to the return status).
715 709
716This mechanism can be used to include BDB into other event mechanisms, 710This mechanism can be used to include BDB into other event mechanisms,
717such as L<AnyEvent::BDB> or L<Coro::BDB>. 711such as L<Coro::BDB>.
718 712
719The default implementation works like this: 713To allow other, callback-based, events to be executed while callback-less
714ones are run, you could use this sync prepare function:
720 715
721 sub { 716 sub {
722 my $status; 717 my $status;
723 ( 718 (
724 sub { $status = $! }, 719 sub { $status = $! },
725 sub { BDB::poll while !defined $status; $! = $status }, 720 sub { BDB::poll while !defined $status; $! = $status },
726 ) 721 )
727 } 722 }
728 723
729It simply blocks the process till the request has finished and then sets 724It works by polling for results till the request has finished and then
730C<$!> to the return value. This means that if you don't use a callback, 725sets C<$!> to the return value. This means that if you don't use a
731BDB will simply fall back to synchronous operations. 726callback, BDB would simply fall back to synchronous operations.
727
728By default, or if the sync prepare function is set to C<undef>, is to
729execute callback-less BDB requests in the foreground thread, setting C<$!>
730to the return value, without polling for other events.
732 731
733=back 732=back
734 733
735=head3 STATISTICAL INFORMATION 734=head2 STATISTICAL INFORMATION
736 735
737=over 4 736=over 4
738 737
739=item BDB::nreqs 738=item BDB::nreqs
740 739
… …
758 757
759=back 758=back
760 759
761=cut 760=cut
762 761
763set_sync_prepare { 762set_sync_prepare (undef);
764 my $status;
765 (
766 sub {
767 $status = $!;
768 },
769 sub {
770 BDB::poll while !defined $status;
771 $! = $status;
772 },
773 )
774};
775 763
776min_parallel 8; 764min_parallel 8;
777 765
778END { flush } 766END { flush }
779 767
7801; 7681;
781 769
770=head1 COMMON PITFALLS
771
772=head2 Unexpected Crashes
773
774Remember that, by default, BDB will execute requests in parallel, in
775somewhat random order. That means that it is easy to run a C<db_get>
776request on thesa me database as a concurrent C<db_close> request, leading
777to a crash, silent data corruption, eventually the next world war on
778terrorism.
779
780If you only ever use foreground requests (without a callback), this will
781not be an issue.
782
783=head2 Unexpected Freezes or Deadlocks
784
785Remember that, by default, BDB will execute requests in parallel, which
786easily leads to deadlocks (even concurrent put's on the same database can
787deadlock).
788
789You either need to run deadlock detection (and handle the resulting
790errors), or make sure only one process ever updates the database, ine one
791thread, e.g. by using only foreground requests (without a callback).
792
782=head2 FORK BEHAVIOUR 793=head1 FORK BEHAVIOUR
783 794
784This module should do "the right thing" when the process using it forks: 795This module should do "the right thing" when the process using it forks:
785 796
786Before the fork, BDB enters a quiescent state where no requests 797Before the fork, BDB enters a quiescent state where no requests
787can be added in other threads and no results will be processed. After 798can be added in other threads and no results will be processed. After
… …
797 808
798Win32 note: there is no fork on win32, and perls emulation of it is too 809Win32 note: there is no fork on win32, and perls emulation of it is too
799broken to be supported, so do not use BDB in a windows pseudo-fork, better 810broken to be supported, so do not use BDB in a windows pseudo-fork, better
800yet, switch to a more capable platform. 811yet, switch to a more capable platform.
801 812
802=head2 MEMORY USAGE 813=head1 MEMORY USAGE
803 814
804Per-request usage: 815Per-request usage:
805 816
806Each aio request uses - depending on your architecture - around 100-200 817Each aio request uses - depending on your architecture - around 100-200
807bytes of memory. In addition, stat requests need a stat buffer (possibly 818bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
816 827
817In the execution phase, some aio requests require more memory for 828In the execution phase, some aio requests require more memory for
818temporary buffers, and each thread requires a stack and other data 829temporary buffers, and each thread requires a stack and other data
819structures (usually around 16k-128k, depending on the OS). 830structures (usually around 16k-128k, depending on the OS).
820 831
832=head1 WIN32 FILENAMES/DATABASE NAME MESS
833
834Perl on Win32 supports only ASCII filenames (the reason is that it abuses
835an internal flag to store wether a filename is Unicode or ANSI, but that
836flag is used for somethign else in the perl core, so there is no way to
837detect wether a filename is ANSI or Unicode-encoded). The BDB module
838tries to work around this issue by assuming that the filename is an ANSI
839filename and BDB was built for unicode support.
840
821=head1 KNOWN BUGS 841=head1 KNOWN BUGS
822 842
823Known bugs will be fixed in the next release, except: 843Known bugs will be fixed in the next release, except:
824 844
825 If you use a transaction in any request, and the request returns 845 If you use a transaction in any request, and the request returns

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines