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Comparing BDB/BDB.pm (file contents):
Revision 1.37 by root, Mon Jul 7 14:28:53 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 = '1.5'; 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 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<$!> will reflect the return value
… …
156settings) are method calls on the relevant objects, so the rule of thumb 150settings) are method calls on the relevant objects, so the rule of thumb
157is: if it's a method, it's not blocking, if it's a function, it takes a 151is: if it's a method, it's not blocking, if it's a function, it takes a
158callback as last argument. 152callback as last argument.
159 153
160In the following, C<$int> signifies an integer return value, 154In the following, C<$int> signifies an integer return value,
161C<octetstring> is a "binary string" (i.e. a perl string with no character 155C<bdb_filename> is a "filename" (octets on unix, madness on windows),
162indices >255), C<U32> is an unsigned 32 bit integer, C<int> is some 156C<U32> is an unsigned 32 bit integer, C<int> is some integer, C<NV> is a
163integer, C<NV> is a floating point value. 157floating point value.
164 158
165The C<SV *> types are generic perl scalars (for input and output of data 159Most C<SV *> types are generic perl scalars (for input and output of data
166values), and the C<SV *callback> is the optional callback function to call 160values).
167when the request is completed.
168 161
169The various C<DB_ENV> etc. arguments are handles return by 162The various C<DB_ENV> etc. arguments are handles return by
170C<db_env_create>, C<db_create>, C<txn_begin> and so on. If they have an 163C<db_env_create>, C<db_create>, C<txn_begin> and so on. If they have an
171appended C<_ornull> this means they are optional and you can pass C<undef> 164appended C<_ornull> this means they are optional and you can pass C<undef>
172for them, resulting a NULL pointer on the C level. 165for them, resulting a NULL pointer on the C level.
173 166
167The C<SV *callback> is the optional callback function to call when the
168request is completed. This last callback argument is special: the callback
169is simply the last argument passed. If there are "optional" arguments
170before the callback they can be left out. The callback itself can be left
171out or specified as C<undef>, in which case the function will be executed
172synchronously.
173
174For example, C<db_env_txn_checkpoint> usually is called with all integer
175arguments zero. These can be left out, so all of these specify a call
176to C<< DB_ENV->txn_checkpoint >>, to be executed asynchronously with a
177callback to be called:
178
179 db_env_txn_checkpoint $db_env, 0, 0, 0, sub { };
180 db_env_txn_checkpoint $db_env, 0, 0, sub { };
181 db_env_txn_checkpoint $db_env, sub { };
182
183While these all specify a call to C<< DB_ENV->txn_checkpoint >> to be
184executed synchronously:
185
186 db_env_txn_checkpoint $db_env, 0, 0, 0, undef;
187 db_env_txn_checkpoint $db_env, 0, 0, 0;
188 db_env_txn_checkpoint $db_env, 0;
189
174=head3 BDB functions 190=head2 BDB functions
175 191
176Functions in the BDB namespace, exported by default: 192Functions in the BDB namespace, exported by default:
177 193
178 $env = db_env_create (U32 env_flags = 0) 194 $env = db_env_create (U32 env_flags = 0)
179 flags: RPCCLIENT 195 flags: RPCCLIENT
180 196
181 db_env_open (DB_ENV *env, octetstring db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef) 197 db_env_open (DB_ENV *env, bdb_filename db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef)
182 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 198 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
183 db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef) 199 db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef)
184 db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef) 200 db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
185 flags: FORCE 201 flags: FORCE
186 db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef) 202 db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef)
187 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
188 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)
189 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)
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)
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)
190 209
191 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 210 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
192 flags: XA_CREATE 211 flags: XA_CREATE
193 212
194 db_open (DB *db, DB_TXN_ornull *txnid, octetstring file, octetstring 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)
195 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
196 db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 215 db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef)
197 flags: DB_NOSYNC 216 flags: DB_NOSYNC
198 db_upgrade (DB *db, octetstring file, U32 flags = 0, SV *callback = &PL_sv_undef) 217 db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = &PL_sv_undef)
199 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 = &PL_sv_undef)
200 flags: FREELIST_ONLY FREE_SPACE 219 flags: FREELIST_ONLY FREE_SPACE
201 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)
202 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)
203 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)
204 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)
205 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)
206 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
207 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)
208 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
209 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)
… …
226 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)
227 flags: TXN_NOSYNC 247 flags: TXN_NOSYNC
228 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)
229 flags: TXN_NOSYNC 249 flags: TXN_NOSYNC
230 250
231=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)
232 252
233This is not actually a Berkeley DB function but a BDB module 253This is not actually a Berkeley DB function but a BDB module
234extension. The background for this exytension is: It is very annoying to 254extension. The background for this exytension is: It is very annoying to
235have 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
236codepath out of your transaction. While the BDB module still makes this 256codepath out of your transaction. While the BDB module still makes this
… …
262 282
263You can use the C<< $txn->failed >> method to check wether a transaction 283You can use the C<< $txn->failed >> method to check wether a transaction
264has failed in this way and abort further processing (excluding 284has failed in this way and abort further processing (excluding
265C<db_txn_finish>). 285C<db_txn_finish>).
266 286
267=head3 DB_ENV/database environment methods 287=head2 DB_ENV/database environment methods
268 288
269Methods available on DB_ENV/$env handles: 289Methods available on DB_ENV/$env handles:
270 290
271 DESTROY (DB_ENV_ornull *env) 291 DESTROY (DB_ENV_ornull *env)
272 CODE: 292 CODE:
… …
276 $int = $env->set_data_dir (const char *dir) 296 $int = $env->set_data_dir (const char *dir)
277 $int = $env->set_tmp_dir (const char *dir) 297 $int = $env->set_tmp_dir (const char *dir)
278 $int = $env->set_lg_dir (const char *dir) 298 $int = $env->set_lg_dir (const char *dir)
279 $int = $env->set_shm_key (long shm_key) 299 $int = $env->set_shm_key (long shm_key)
280 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 300 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
281 $int = $env->set_flags (U32 flags, int onoff) 301 $int = $env->set_flags (U32 flags, int onoff = 1)
302 $int = $env->log_set_config (U32 flags, int onoff = 1) (v4.7)
303 $int = $env->set_intermediate_dir_mode (const char *modestring) (v4.7)
282 $env->set_errfile (FILE *errfile = 0) 304 $env->set_errfile (FILE *errfile = 0)
283 $env->set_msgfile (FILE *msgfile = 0) 305 $env->set_msgfile (FILE *msgfile = 0)
284 $int = $env->set_verbose (U32 which, int onoff = 1) 306 $int = $env->set_verbose (U32 which, int onoff = 1)
285 $int = $env->set_encrypt (const char *password, U32 flags = 0) 307 $int = $env->set_encrypt (const char *password, U32 flags = 0)
286 $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)
… …
298 $int = $env->mutex_set_max (U32 max) 320 $int = $env->mutex_set_max (U32 max)
299 $int = $env->mutex_set_align (U32 align) 321 $int = $env->mutex_set_align (U32 align)
300 322
301 $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)
302 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
325 $txn = $env->cdsgroup_begin; (v4.5)
303 326
304=head4 Example: 327=head3 Example:
305 328
306 use AnyEvent; 329 use AnyEvent;
307 use BDB; 330 use BDB;
308 331
309 our $FH; open $FH, "<&=" . BDB::poll_fileno; 332 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
321 0600; 344 0600;
322 345
323 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); 346 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
324 347
325 348
326=head3 DB/database methods 349=head2 DB/database methods
327 350
328Methods available on DB/$db handles: 351Methods available on DB/$db handles:
329 352
330 DESTROY (DB_ornull *db) 353 DESTROY (DB_ornull *db)
331 CODE: 354 CODE:
… …
357 380
358 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 381 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
359 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT 382 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
360 $seq = $db->sequence (U32 flags = 0) 383 $seq = $db->sequence (U32 flags = 0)
361 384
362=head4 Example: 385=head3 Example:
363 386
364 my $db = db_create $env; 387 my $db = db_create $env;
365 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;
366 389
367 for (1..1000) { 390 for (1..1000) {
… …
374 db_del $db, undef, "key $_" for 1..1000; 397 db_del $db, undef, "key $_" for 1..1000;
375 398
376 db_sync $db; 399 db_sync $db;
377 400
378 401
379=head3 DB_TXN/transaction methods 402=head2 DB_TXN/transaction methods
380 403
381Methods available on DB_TXN/$txn handles: 404Methods available on DB_TXN/$txn handles:
382 405
383 DESTROY (DB_TXN_ornull *txn) 406 DESTROY (DB_TXN_ornull *txn)
384 CODE: 407 CODE:
… …
390 413
391 $bool = $txn->failed 414 $bool = $txn->failed
392 # see db_txn_finish documentation, above 415 # see db_txn_finish documentation, above
393 416
394 417
395=head3 DBC/cursor methods 418=head2 DBC/cursor methods
396 419
397Methods available on DBC/$dbc handles: 420Methods available on DBC/$dbc handles:
398 421
399 DESTROY (DBC_ornull *dbc) 422 DESTROY (DBC_ornull *dbc)
400 CODE: 423 CODE:
401 if (dbc) 424 if (dbc)
402 dbc->c_close (dbc); 425 dbc->c_close (dbc);
403 426
404 $int = $cursor->set_priority ($priority = PRIORITY_*) 427 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
405 428
406=head4 Example: 429=head3 Example:
407 430
408 my $c = $db->cursor; 431 my $c = $db->cursor;
409 432
410 for (;;) { 433 for (;;) {
411 db_c_get $c, my $key, my $data, BDB::NEXT; 434 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
414 } 437 }
415 438
416 db_c_close $c; 439 db_c_close $c;
417 440
418 441
419=head3 DB_SEQUENCE/sequence methods 442=head2 DB_SEQUENCE/sequence methods
420 443
421Methods available on DB_SEQUENCE/$seq handles: 444Methods available on DB_SEQUENCE/$seq handles:
422 445
423 DESTROY (DB_SEQUENCE_ornull *seq) 446 DESTROY (DB_SEQUENCE_ornull *seq)
424 CODE: 447 CODE:
… …
429 $int = $seq->set_cachesize (U32 size) 452 $int = $seq->set_cachesize (U32 size)
430 $int = $seq->set_flags (U32 flags) 453 $int = $seq->set_flags (U32 flags)
431 flags: SEQ_DEC SEQ_INC SEQ_WRAP 454 flags: SEQ_DEC SEQ_INC SEQ_WRAP
432 $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)
433 456
434=head4 Example: 457=head3 Example:
435 458
436 my $seq = $db->sequence; 459 my $seq = $db->sequence;
437 460
438 db_sequence_open $seq, undef, "seq", BDB::CREATE; 461 db_sequence_open $seq, undef, "seq", BDB::CREATE;
439 db_sequence_get $seq, undef, 1, my $value; 462 db_sequence_get $seq, undef, 1, my $value;
440 463
441 464
442=head2 SUPPORT FUNCTIONS 465=head1 SUPPORT FUNCTIONS
443 466
444=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 467=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
445 468
446=over 4 469=over 4
447 470
448=item $msg = BDB::strerror [$errno] 471=item $msg = BDB::strerror [$errno]
449 472
… …
536 BDB::poll_wait, BDB::poll_cb 559 BDB::poll_wait, BDB::poll_cb
537 while BDB::nreqs; 560 while BDB::nreqs;
538 561
539=back 562=back
540 563
564=head2 VERSION CHECKING
565
566BerkeleyDB comes in various versions, many of them have minor
567incompatibilities. This means that traditional "at least version x.x"
568checks are often not sufficient.
569
570Example: set the log_autoremove option in a way compatible with <v4.7 and
571v4.7. Note the use of & on the constants to avoid triggering a compiletime
572bug when the symbol isn't available.
573
574 $DB_ENV->set_flags (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7;
575 $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;
576
577=over 4
578
579=item BDB::VERSION
580
581The C<BDB::VERSION> function, when called without arguments, returns the
582Berkeley DB version as a v-string (usually with 3 components). You should
583use C<lt> and C<ge> operators exclusively to make comparisons.
584
585Example: check for at least version 4.7.
586
587 BDB::VERSION ge v4.7 or die;
588
589=item BDB::VERSION min-version
590
591Returns true if the BDB version is at least the given version (specified
592as a v-string), false otherwise.
593
594Example: check for at least version 4.5.
595
596 BDB::VERSION v4.7 or die;
597
598=item BDB::VERSION min-version, max-version
599
600Returns true of the BDB version is at least version C<min-version> (specify C<undef> or C<v0> for any minimum version)
601and less then C<max-version>.
602
603Example: check wether version is strictly less then v4.7.
604
605 BDB::VERSION v0, v4.7
606 or die "version 4.7 is not yet supported";
607
608=back
609
610=cut
611
612sub VERSION {
613 # I was dumb enough to override the VERSION method here, so let's try
614 # to fix it up.
615
616 if ($_[0] eq __PACKAGE__) {
617 $VERSION
618 } else {
619 if (@_ > 0) {
620 return undef if VERSION_v lt $_[0];
621 if (@_ > 1) {
622 return undef if VERSION_v ge $_[1];
623 }
624 }
625
626 VERSION_v
627 }
628}
629
541=head3 CONTROLLING THE NUMBER OF THREADS 630=head2 CONTROLLING THE NUMBER OF THREADS
542 631
543=over 4 632=over 4
544 633
545=item BDB::min_parallel $nthreads 634=item BDB::min_parallel $nthreads
546 635
… …
607 696
608You can still queue as many requests as you want. Therefore, 697You can still queue as many requests as you want. Therefore,
609C<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
610as 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).
611 700
612=item BDB::set_sync_prepare $cb 701=item $old_cb = BDB::set_sync_prepare $cb
613 702
614Sets a callback that is called whenever a request is created without an 703Sets a callback that is called whenever a request is created without an
615explicit callback. It has to return two code references. The first is used 704explicit callback. It has to return two code references. The first is used
616as the request callback (it should save the return status), and the second 705as the request callback (it should save the return status), and the second
617is called to wait until the first callback has been called (it must set 706is called to wait until the first callback has been called (it must set
618C<$!> to the return status). 707C<$!> to the return status).
619 708
620This mechanism can be used to include BDB into other event mechanisms, 709This mechanism can be used to include BDB into other event mechanisms,
621such as L<AnyEvent::BDB> or L<Coro::BDB>. 710such as L<Coro::BDB>.
622 711
623The 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:
624 714
625 sub { 715 sub {
626 my $status; 716 my $status;
627 ( 717 (
628 sub { $status = $! }, 718 sub { $status = $! },
629 sub { BDB::poll while !defined $status; $! = $status }, 719 sub { BDB::poll while !defined $status; $! = $status },
630 ) 720 )
631 } 721 }
632 722
633It simply blocks the process till the request has finished and then sets 723It works by polling for results till the request has finished and then
634C<$!> to the return value. This means that if you don't use a callback, 724sets C<$!> to the return value. This means that if you don't use a
635BDB will simply fall back to synchronous operations. 725callback, BDB would simply fall back to synchronous operations.
726
727By default, or if the sync prepare function is set to C<undef>, is to
728execute callback-less BDB requests in the foreground thread, setting C<$!>
729to the return value, without polling for other events.
636 730
637=back 731=back
638 732
639=head3 STATISTICAL INFORMATION 733=head2 STATISTICAL INFORMATION
640 734
641=over 4 735=over 4
642 736
643=item BDB::nreqs 737=item BDB::nreqs
644 738
… …
662 756
663=back 757=back
664 758
665=cut 759=cut
666 760
667set_sync_prepare { 761set_sync_prepare (undef);
668 my $status;
669 (
670 sub {
671 $status = $!;
672 },
673 sub {
674 BDB::poll while !defined $status;
675 $! = $status;
676 },
677 )
678};
679 762
680min_parallel 8; 763min_parallel 8;
681 764
682END { flush } 765END { flush }
683 766
6841; 7671;
685 768
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
686=head2 FORK BEHAVIOUR 792=head1 FORK BEHAVIOUR
687 793
688This 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:
689 795
690Before the fork, BDB enters a quiescent state where no requests 796Before the fork, BDB enters a quiescent state where no requests
691can 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
… …
701 807
702Win32 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
703broken 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
704yet, switch to a more capable platform. 810yet, switch to a more capable platform.
705 811
706=head2 MEMORY USAGE 812=head1 MEMORY USAGE
707 813
708Per-request usage: 814Per-request usage:
709 815
710Each aio request uses - depending on your architecture - around 100-200 816Each aio request uses - depending on your architecture - around 100-200
711bytes of memory. In addition, stat requests need a stat buffer (possibly 817bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
720 826
721In the execution phase, some aio requests require more memory for 827In the execution phase, some aio requests require more memory for
722temporary buffers, and each thread requires a stack and other data 828temporary buffers, and each thread requires a stack and other data
723structures (usually around 16k-128k, depending on the OS). 829structures (usually around 16k-128k, depending on the OS).
724 830
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
725=head1 KNOWN BUGS 840=head1 KNOWN BUGS
726 841
727Known bugs will be fixed in the next release, except: 842Known bugs will be fixed in the next release, except:
728 843
729 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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