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Revision 1.45 by root, Wed Jul 9 21:16:14 2008 UTC vs.
Revision 1.68 by root, Tue Feb 2 04:17:03 2016 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
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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
112our $VERSION;
113
113BEGIN { 114BEGIN {
114 our $VERSION = '1.7'; 115 $VERSION = '1.91';
115 116
116 our @BDB_REQ = qw( 117 our @BDB_REQ = qw(
117 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
118 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 db_env_lsn_reset
119 db_open db_close db_compact db_sync db_upgrade 121 db_open db_close db_compact db_sync db_verify db_upgrade
120 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
121 db_txn_commit db_txn_abort db_txn_finish 123 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 124 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 125 db_sequence_open db_sequence_close
124 db_sequence_get db_sequence_remove 126 db_sequence_get db_sequence_remove
… …
133 135
134 require XSLoader; 136 require XSLoader;
135 XSLoader::load ("BDB", $VERSION); 137 XSLoader::load ("BDB", $VERSION);
136} 138}
137 139
138=head2 WIN32 FILENAMES/DATABASE NAME MESS
139
140Perl on Win32 supports only ASCII filenames (the reason is that it abuses
141an internal flag to store wether a filename is Unicode or ANSI, but that
142flag is used for somethign else in the perl core, so there is no way to
143detect wether a filename is ANSI or Unicode-encoded). The BDB module
144tries to work around this issue by assuming that the filename is an ANSI
145filename and BDB was built for unicode support.
146
147=head2 BERKELEYDB FUNCTIONS 140=head1 BERKELEYDB FUNCTIONS
148 141
149All of these are functions. The create functions simply return a new 142All of these are functions. The create functions simply return a new
150object and never block. All the remaining functions take an optional 143object and never block. All the remaining functions take an optional
151callback as last argument. If it is missing, then the function will be 144callback as last argument. If it is missing, then the function will be
152executed synchronously. In both cases, C<$!> will reflect the return value 145executed synchronously. In both cases, C<$!> will reflect the return value
… …
191 184
192 db_env_txn_checkpoint $db_env, 0, 0, 0, undef; 185 db_env_txn_checkpoint $db_env, 0, 0, 0, undef;
193 db_env_txn_checkpoint $db_env, 0, 0, 0; 186 db_env_txn_checkpoint $db_env, 0, 0, 0;
194 db_env_txn_checkpoint $db_env, 0; 187 db_env_txn_checkpoint $db_env, 0;
195 188
196=head3 BDB functions 189=head2 BDB functions
197 190
198Functions in the BDB namespace, exported by default: 191Functions in the BDB namespace, exported by default:
199 192
200 $env = db_env_create (U32 env_flags = 0) 193 $env = db_env_create (U32 env_flags = 0)
201 flags: RPCCLIENT 194 flags: RPCCLIENT
202 195
203 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)
204 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
205 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)
206 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)
207 flags: FORCE 200 flags: FORCE
208 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)
209 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
210 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)
211 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)
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) 205 db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = 0)
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) 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)
208 db_env_lsn_reset (DB_ENV *env, bdb_filename db, U32 flags = 0, SV *callback = 0)
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 = 0)
219 flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE 214 flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE
220 db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 215 db_close (DB *db, U32 flags = 0, SV *callback = 0)
221 flags: DB_NOSYNC 216 flags: DB_NOSYNC
217 db_verify (DB *db, bdb_filename file, bdb_filename database = 0, SV *dummy = 0, U32 flags = 0, SV *callback = 0)
222 db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = &PL_sv_undef) 218 db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = 0)
223 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) 219 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)
224 flags: FREELIST_ONLY FREE_SPACE 220 flags: FREELIST_ONLY FREE_SPACE
225 db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 221 db_sync (DB *db, U32 flags = 0, SV *callback = 0)
226 db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef) 222 db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = 0)
227 db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 223 db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
228 flags: APPEND NODUPDATA NOOVERWRITE 224 flags: APPEND NODUPDATA NOOVERWRITE
229 db_exists (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0) (v4.6) 225 db_exists (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0) (v4.6)
230 db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 226 db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
231 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW 227 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
232 db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 228 db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0)
233 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW 229 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
234 db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) 230 db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0)
235 db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) 231 db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = 0)
236 flags: TXN_NOSYNC TXN_SYNC 232 flags: TXN_NOSYNC TXN_SYNC
237 db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef) 233 db_txn_abort (DB_TXN *txn, SV *callback = 0)
238 234
239 db_c_close (DBC *dbc, SV *callback = &PL_sv_undef) 235 db_c_close (DBC *dbc, SV *callback = 0)
240 db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = &PL_sv_undef) 236 db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = 0)
241 db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 237 db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
242 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA 238 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA
243 db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 239 db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
244 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 240 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
245 db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 241 db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0)
246 db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef) 242 db_c_del (DBC *dbc, U32 flags = 0, SV *callback = 0)
247 243
248 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) 244 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = 0)
249 flags: CREATE EXCL 245 flags: CREATE EXCL
250 db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef) 246 db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = 0)
251 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) 247 db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = 0)
252 flags: TXN_NOSYNC 248 flags: TXN_NOSYNC
253 db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) 249 db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = 0)
254 flags: TXN_NOSYNC 250 flags: TXN_NOSYNC
255 251
256=head4 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) 252=head3 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = 0)
257 253
258This is not actually a Berkeley DB function but a BDB module 254This is not actually a Berkeley DB function but a BDB module
259extension. The background for this exytension is: It is very annoying to 255extension. The background for this exytension is: It is very annoying to
260have to check every single BDB function for error returns and provide a 256have to check every single BDB function for error returns and provide a
261codepath out of your transaction. While the BDB module still makes this 257codepath out of your transaction. While the BDB module still makes this
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287 283
288You can use the C<< $txn->failed >> method to check wether a transaction 284You can use the C<< $txn->failed >> method to check wether a transaction
289has failed in this way and abort further processing (excluding 285has failed in this way and abort further processing (excluding
290C<db_txn_finish>). 286C<db_txn_finish>).
291 287
288
292=head3 DB_ENV/database environment methods 289=head2 DB_ENV/database environment methods
293 290
294Methods available on DB_ENV/$env handles: 291Methods available on DB_ENV/$env handles:
295 292
296 DESTROY (DB_ENV_ornull *env) 293 DESTROY (DB_ENV_ornull *env)
297 CODE: 294 CODE:
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327 324
328 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) 325 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0)
329 flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC 326 flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC
330 $txn = $env->cdsgroup_begin; (v4.5) 327 $txn = $env->cdsgroup_begin; (v4.5)
331 328
332=head4 Example: 329=head3 Example:
333 330
334 use AnyEvent; 331 use AnyEvent;
335 use BDB; 332 use BDB;
336 333
337 our $FH; open $FH, "<&=" . BDB::poll_fileno; 334 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
349 0600; 346 0600;
350 347
351 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); 348 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
352 349
353 350
354=head3 DB/database methods 351=head2 DB/database methods
355 352
356Methods available on DB/$db handles: 353Methods available on DB/$db handles:
357 354
358 DESTROY (DB_ornull *db) 355 DESTROY (DB_ornull *db)
359 CODE: 356 CODE:
… …
385 382
386 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 383 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
387 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT 384 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
388 $seq = $db->sequence (U32 flags = 0) 385 $seq = $db->sequence (U32 flags = 0)
389 386
390=head4 Example: 387=head3 Example:
391 388
392 my $db = db_create $env; 389 my $db = db_create $env;
393 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600; 390 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600;
394 391
395 for (1..1000) { 392 for (1..1000) {
… …
402 db_del $db, undef, "key $_" for 1..1000; 399 db_del $db, undef, "key $_" for 1..1000;
403 400
404 db_sync $db; 401 db_sync $db;
405 402
406 403
407=head3 DB_TXN/transaction methods 404=head2 DB_TXN/transaction methods
408 405
409Methods available on DB_TXN/$txn handles: 406Methods available on DB_TXN/$txn handles:
410 407
411 DESTROY (DB_TXN_ornull *txn) 408 DESTROY (DB_TXN_ornull *txn)
412 CODE: 409 CODE:
… …
418 415
419 $bool = $txn->failed 416 $bool = $txn->failed
420 # see db_txn_finish documentation, above 417 # see db_txn_finish documentation, above
421 418
422 419
423=head3 DBC/cursor methods 420=head2 DBC/cursor methods
424 421
425Methods available on DBC/$dbc handles: 422Methods available on DBC/$dbc handles:
426 423
427 DESTROY (DBC_ornull *dbc) 424 DESTROY (DBC_ornull *dbc)
428 CODE: 425 CODE:
429 if (dbc) 426 if (dbc)
430 dbc->c_close (dbc); 427 dbc->c_close (dbc);
431 428
432 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6) 429 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
433 430
434=head4 Example: 431=head3 Example:
435 432
436 my $c = $db->cursor; 433 my $c = $db->cursor;
437 434
438 for (;;) { 435 for (;;) {
439 db_c_get $c, my $key, my $data, BDB::NEXT; 436 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
442 } 439 }
443 440
444 db_c_close $c; 441 db_c_close $c;
445 442
446 443
447=head3 DB_SEQUENCE/sequence methods 444=head2 DB_SEQUENCE/sequence methods
448 445
449Methods available on DB_SEQUENCE/$seq handles: 446Methods available on DB_SEQUENCE/$seq handles:
450 447
451 DESTROY (DB_SEQUENCE_ornull *seq) 448 DESTROY (DB_SEQUENCE_ornull *seq)
452 CODE: 449 CODE:
… …
457 $int = $seq->set_cachesize (U32 size) 454 $int = $seq->set_cachesize (U32 size)
458 $int = $seq->set_flags (U32 flags) 455 $int = $seq->set_flags (U32 flags)
459 flags: SEQ_DEC SEQ_INC SEQ_WRAP 456 flags: SEQ_DEC SEQ_INC SEQ_WRAP
460 $int = $seq->set_range (db_seq_t min, db_seq_t max) 457 $int = $seq->set_range (db_seq_t min, db_seq_t max)
461 458
462=head4 Example: 459=head3 Example:
463 460
464 my $seq = $db->sequence; 461 my $seq = $db->sequence;
465 462
466 db_sequence_open $seq, undef, "seq", BDB::CREATE; 463 db_sequence_open $seq, undef, "seq", BDB::CREATE;
467 db_sequence_get $seq, undef, 1, my $value; 464 db_sequence_get $seq, undef, 1, my $value;
468 465
469 466
470=head2 SUPPORT FUNCTIONS 467=head1 SUPPORT FUNCTIONS
471 468
472=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 469=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
473 470
474=over 4 471=over 4
475 472
476=item $msg = BDB::strerror [$errno] 473=item $msg = BDB::strerror [$errno]
477 474
… …
564 BDB::poll_wait, BDB::poll_cb 561 BDB::poll_wait, BDB::poll_cb
565 while BDB::nreqs; 562 while BDB::nreqs;
566 563
567=back 564=back
568 565
569=head3 VERSION CHECKING 566=head2 VERSION CHECKING
570 567
571BerkeleyDB comes in various versions, many of them have minor 568BerkeleyDB comes in various versions, many of them have minor
572incompatibilities. This means that traditional "at least version x.x" 569incompatibilities. This means that traditional "at least version x.x"
573checks are often not sufficient. 570checks are often not sufficient.
574 571
575Example: set the log_autoremove option in a way compatible with <v.47 and 572Example: set the log_autoremove option in a way compatible with <v4.7 and
576v4.7. Note the use of & on the constants to avoid triggering a compiletime 573v4.7. Note the use of & on the constants to avoid triggering a compiletime
577bug when the symbol isn't available. 574bug when the symbol isn't available.
578 575
579 $DB_ENV->set_flags (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7; 576 $DB_ENV->set_flags (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7;
580 $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7; 577 $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;
… …
613=back 610=back
614 611
615=cut 612=cut
616 613
617sub VERSION { 614sub VERSION {
615 # I was dumb enough to override the VERSION method here, so let's try
616 # to fix it up.
617
618 if ($_[0] eq __PACKAGE__) {
619 $VERSION
620 } else {
618 if (@_ > 0) { 621 if (@_ > 0) {
619 return undef if VERSION_v lt $_[0]; 622 return undef if VERSION_v lt $_[0];
620 if (@_ > 1) { 623 if (@_ > 1) {
621 return undef if VERSION_v ge $_[1]; 624 return undef if VERSION_v ge $_[1];
625 }
622 } 626 }
627
628 VERSION_v
623 } 629 }
624
625 VERSION_v
626} 630}
627 631
628=head3 CONTROLLING THE NUMBER OF THREADS 632=head2 CONTROLLING THE NUMBER OF THREADS
629 633
630=over 4 634=over 4
631 635
632=item BDB::min_parallel $nthreads 636=item BDB::min_parallel $nthreads
633 637
… …
694 698
695You can still queue as many requests as you want. Therefore, 699You can still queue as many requests as you want. Therefore,
696C<max_oustsanding> is mainly useful in simple scripts (with low values) or 700C<max_oustsanding> is mainly useful in simple scripts (with low values) or
697as a stop gap to shield against fatal memory overflow (with large values). 701as a stop gap to shield against fatal memory overflow (with large values).
698 702
699=item BDB::set_sync_prepare $cb 703=item $old_cb = BDB::set_sync_prepare $cb
700 704
701Sets a callback that is called whenever a request is created without an 705Sets a callback that is called whenever a request is created without an
702explicit callback. It has to return two code references. The first is used 706explicit callback. It has to return two code references. The first is used
703as the request callback (it should save the return status), and the second 707as the request callback (it should save the return status), and the second
704is called to wait until the first callback has been called (it must set 708is called to wait until the first callback has been called (it must set
705C<$!> to the return status). 709C<$!> to the return status).
706 710
707This mechanism can be used to include BDB into other event mechanisms, 711This mechanism can be used to include BDB into other event mechanisms,
708such as L<AnyEvent::BDB> or L<Coro::BDB>. 712such as L<Coro::BDB>.
709 713
710The default implementation works like this: 714To allow other, callback-based, events to be executed while callback-less
715ones are run, you could use this sync prepare function:
711 716
712 sub { 717 sub {
713 my $status; 718 my $status;
714 ( 719 (
715 sub { $status = $! }, 720 sub { $status = $! },
716 sub { BDB::poll while !defined $status; $! = $status }, 721 sub { BDB::poll while !defined $status; $! = $status },
717 ) 722 )
718 } 723 }
719 724
720It simply blocks the process till the request has finished and then sets 725It works by polling for results till the request has finished and then
721C<$!> to the return value. This means that if you don't use a callback, 726sets C<$!> to the return value. This means that if you don't use a
722BDB will simply fall back to synchronous operations. 727callback, BDB would simply fall back to synchronous operations.
728
729By default, or if the sync prepare function is set to C<undef>, is to
730execute callback-less BDB requests in the foreground thread, setting C<$!>
731to the return value, without polling for other events.
723 732
724=back 733=back
725 734
726=head3 STATISTICAL INFORMATION 735=head2 STATISTICAL INFORMATION
727 736
728=over 4 737=over 4
729 738
730=item BDB::nreqs 739=item BDB::nreqs
731 740
… …
749 758
750=back 759=back
751 760
752=cut 761=cut
753 762
754set_sync_prepare { 763set_sync_prepare (undef);
755 my $status;
756 (
757 sub {
758 $status = $!;
759 },
760 sub {
761 BDB::poll while !defined $status;
762 $! = $status;
763 },
764 )
765};
766 764
767min_parallel 8; 765min_parallel 8;
768 766
769END { flush } 767END { flush }
770 768
7711; 7691;
772 770
771=head1 COMMON PITFALLS
772
773=head2 Unexpected Crashes
774
775Remember that, by default, BDB will execute requests in parallel, in
776somewhat random order. That means that it is easy to run a C<db_get>
777request on the same database as a concurrent C<db_close> request, leading
778to a crash, silent data corruption, eventually the next world war on
779terrorism.
780
781If you only ever use foreground requests (without a callback), this will
782not be an issue (unless you use threads).
783
784=head2 Unexpected Freezes or Deadlocks
785
786Remember that, by default, BDB will execute requests in parallel, which
787easily leads to deadlocks (even concurrent put's on the same database can
788deadlock).
789
790You either need to run deadlock detection (and handle the resulting
791errors), or make sure only one process ever updates the database, ine one
792thread, e.g. by using only foreground requests (without a callback).
793
773=head2 FORK BEHAVIOUR 794=head1 FORK BEHAVIOUR
774 795
775This module should do "the right thing" when the process using it forks: 796This module should do "the right thing" when the process using it forks:
776 797
777Before the fork, BDB enters a quiescent state where no requests 798Before the fork, BDB enters a quiescent state where no requests
778can be added in other threads and no results will be processed. After 799can be added in other threads and no results will be processed. After
… …
788 809
789Win32 note: there is no fork on win32, and perls emulation of it is too 810Win32 note: there is no fork on win32, and perls emulation of it is too
790broken to be supported, so do not use BDB in a windows pseudo-fork, better 811broken to be supported, so do not use BDB in a windows pseudo-fork, better
791yet, switch to a more capable platform. 812yet, switch to a more capable platform.
792 813
793=head2 MEMORY USAGE 814=head1 MEMORY USAGE
794 815
795Per-request usage: 816Per-request usage:
796 817
797Each aio request uses - depending on your architecture - around 100-200 818Each aio request uses - depending on your architecture - around 100-200
798bytes of memory. In addition, stat requests need a stat buffer (possibly 819bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
807 828
808In the execution phase, some aio requests require more memory for 829In the execution phase, some aio requests require more memory for
809temporary buffers, and each thread requires a stack and other data 830temporary buffers, and each thread requires a stack and other data
810structures (usually around 16k-128k, depending on the OS). 831structures (usually around 16k-128k, depending on the OS).
811 832
833=head1 WIN32 FILENAMES/DATABASE NAME MESS
834
835Perl on Win32 supports only ASCII filenames (the reason is that it abuses
836an internal flag to store wether a filename is Unicode or ANSI, but that
837flag is used for somethign else in the perl core, so there is no way to
838detect wether a filename is ANSI or Unicode-encoded). The BDB module
839tries to work around this issue by assuming that the filename is an ANSI
840filename and BDB was built for unicode support.
841
812=head1 KNOWN BUGS 842=head1 KNOWN BUGS
813 843
814Known bugs will be fixed in the next release, except: 844Known bugs will be fixed in the next release, except:
815 845
816 If you use a transaction in any request, and the request returns 846 If you use a transaction in any request, and the request returns

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