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Comparing BDB/BDB.pm (file contents):
Revision 1.33 by root, Sun Mar 30 04:57:55 2008 UTC vs.
Revision 1.53 by root, Tue Oct 21 02:21:25 2008 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 result processing with AnyEvent: 32 # automatic event loop intergration with AnyEvent:
33 our $FH; open $FH, "<&=" . BDB::poll_fileno; 33 use AnyEvent::BDB;
34 our $WATCHER = AnyEvent->io (fh => $FH, poll => 'r', cb => \&BDB::poll_cb);
35 34
36 # automatic result processing with EV: 35 # automatic result processing with EV:
37 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;
38 37
39 # with Glib: 38 # with Glib:
… …
109no warnings; 108no warnings;
110use strict 'vars'; 109use strict 'vars';
111 110
112use base 'Exporter'; 111use base 'Exporter';
113 112
113our $VERSION;
114
114BEGIN { 115BEGIN {
115 our $VERSION = '1.44'; 116 $VERSION = '1.81';
116 117
117 our @BDB_REQ = qw( 118 our @BDB_REQ = qw(
118 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
119 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
120 db_open db_close db_compact db_sync db_upgrade 122 db_open db_close db_compact db_sync db_upgrade
121 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
122 db_txn_commit db_txn_abort db_txn_finish 124 db_txn_commit db_txn_abort db_txn_finish
123 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
124 db_sequence_open db_sequence_close 126 db_sequence_open db_sequence_close
125 db_sequence_get db_sequence_remove 127 db_sequence_get db_sequence_remove
126 ); 128 );
… …
134 136
135 require XSLoader; 137 require XSLoader;
136 XSLoader::load ("BDB", $VERSION); 138 XSLoader::load ("BDB", $VERSION);
137} 139}
138 140
139=head2 BERKELEYDB FUNCTIONS 141=head1 BERKELEYDB FUNCTIONS
140 142
141All of these are functions. The create functions simply return a new 143All of these are functions. The create functions simply return a new
142object and never block. All the remaining functions all take an optional 144object and never block. All the remaining functions take an optional
143callback as last argument. If it is missing, then the function will be 145callback as last argument. If it is missing, then the function will be
144executed synchronously. In both cases, C<$!> will reflect the return value 146executed synchronously. In both cases, C<$!> will reflect the return value
145of the function. 147of the function.
146 148
147BDB functions that cannot block (mostly functions that manipulate 149BDB functions that cannot block (mostly functions that manipulate
148settings) are method calls on the relevant objects, so the rule of thumb 150settings) are method calls on the relevant objects, so the rule of thumb
149is: if its a method, its not blocking, if its a function, it takes a 151is: if it's a method, it's not blocking, if it's a function, it takes a
150callback as last argument. 152callback as last argument.
151 153
152In the following, C<$int> signifies an integer return value, 154In the following, C<$int> signifies an integer return value,
153C<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),
154indices >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
155integer, C<NV> is a floating point value. 157floating point value.
156 158
157The 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
158values), and the C<SV *callback> is the optional callback function to call 160values).
159when the request is completed.
160 161
161The various C<DB_ENV> etc. arguments are handles return by 162The various C<DB_ENV> etc. arguments are handles return by
162C<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
163appended 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>
164for them, resulting a NULL pointer on the C level. 165for them, resulting a NULL pointer on the C level.
165 166
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
166=head3 BDB functions 190=head2 BDB functions
167 191
168Functions in the BDB namespace, exported by default: 192Functions in the BDB namespace, exported by default:
169 193
170 $env = db_env_create (U32 env_flags = 0) 194 $env = db_env_create (U32 env_flags = 0)
171 flags: RPCCLIENT 195 flags: RPCCLIENT
172 196
173 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)
174 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
175 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)
176 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)
177 flags: FORCE 201 flags: FORCE
178 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)
179 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
180 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)
181 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)
182 209
183 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 210 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
184 flags: XA_CREATE 211 flags: XA_CREATE
185 212
186 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)
187 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
188 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)
189 flags: DB_NOSYNC 216 flags: DB_NOSYNC
190 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)
191 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)
192 flags: FREELIST_ONLY FREE_SPACE 219 flags: FREELIST_ONLY FREE_SPACE
193 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)
194 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)
195 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)
196 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)
197 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)
198 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
199 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)
200 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
201 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)
… …
218 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)
219 flags: TXN_NOSYNC 247 flags: TXN_NOSYNC
220 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)
221 flags: TXN_NOSYNC 249 flags: TXN_NOSYNC
222 250
223=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)
224 252
225This is not actually a Berkeley DB function but a BDB module 253This is not actually a Berkeley DB function but a BDB module
226extension. The background for this exytension is: It is very annoying to 254extension. The background for this exytension is: It is very annoying to
227have 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
228codepath out of your transaction. While the BDB module still makes this 256codepath out of your transaction. While the BDB module still makes this
… …
254 282
255You can use the C<< $txn->failed >> method to check wether a transaction 283You can use the C<< $txn->failed >> method to check wether a transaction
256has failed in this way and abort further processing (excluding 284has failed in this way and abort further processing (excluding
257C<db_txn_finish>). 285C<db_txn_finish>).
258 286
259=head3 DB_ENV/database environment methods 287=head2 DB_ENV/database environment methods
260 288
261Methods available on DB_ENV/$env handles: 289Methods available on DB_ENV/$env handles:
262 290
263 DESTROY (DB_ENV_ornull *env) 291 DESTROY (DB_ENV_ornull *env)
264 CODE: 292 CODE:
… …
268 $int = $env->set_data_dir (const char *dir) 296 $int = $env->set_data_dir (const char *dir)
269 $int = $env->set_tmp_dir (const char *dir) 297 $int = $env->set_tmp_dir (const char *dir)
270 $int = $env->set_lg_dir (const char *dir) 298 $int = $env->set_lg_dir (const char *dir)
271 $int = $env->set_shm_key (long shm_key) 299 $int = $env->set_shm_key (long shm_key)
272 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 300 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
273 $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)
274 $env->set_errfile (FILE *errfile = 0) 304 $env->set_errfile (FILE *errfile = 0)
275 $env->set_msgfile (FILE *msgfile = 0) 305 $env->set_msgfile (FILE *msgfile = 0)
276 $int = $env->set_verbose (U32 which, int onoff = 1) 306 $int = $env->set_verbose (U32 which, int onoff = 1)
277 $int = $env->set_encrypt (const char *password, U32 flags = 0) 307 $int = $env->set_encrypt (const char *password, U32 flags = 0)
278 $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)
… …
290 $int = $env->mutex_set_max (U32 max) 320 $int = $env->mutex_set_max (U32 max)
291 $int = $env->mutex_set_align (U32 align) 321 $int = $env->mutex_set_align (U32 align)
292 322
293 $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)
294 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)
295 326
296=head4 Example: 327=head3 Example:
297 328
298 use AnyEvent; 329 use AnyEvent;
299 use BDB; 330 use BDB;
300 331
301 our $FH; open $FH, "<&=" . BDB::poll_fileno; 332 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
313 0600; 344 0600;
314 345
315 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); 346 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
316 347
317 348
318=head3 DB/database methods 349=head2 DB/database methods
319 350
320Methods available on DB/$db handles: 351Methods available on DB/$db handles:
321 352
322 DESTROY (DB_ornull *db) 353 DESTROY (DB_ornull *db)
323 CODE: 354 CODE:
… …
349 380
350 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 381 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
351 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT 382 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
352 $seq = $db->sequence (U32 flags = 0) 383 $seq = $db->sequence (U32 flags = 0)
353 384
354=head4 Example: 385=head3 Example:
355 386
356 my $db = db_create $env; 387 my $db = db_create $env;
357 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;
358 389
359 for (1..1000) { 390 for (1..1000) {
… …
366 db_del $db, undef, "key $_" for 1..1000; 397 db_del $db, undef, "key $_" for 1..1000;
367 398
368 db_sync $db; 399 db_sync $db;
369 400
370 401
371=head3 DB_TXN/transaction methods 402=head2 DB_TXN/transaction methods
372 403
373Methods available on DB_TXN/$txn handles: 404Methods available on DB_TXN/$txn handles:
374 405
375 DESTROY (DB_TXN_ornull *txn) 406 DESTROY (DB_TXN_ornull *txn)
376 CODE: 407 CODE:
… …
382 413
383 $bool = $txn->failed 414 $bool = $txn->failed
384 # see db_txn_finish documentation, above 415 # see db_txn_finish documentation, above
385 416
386 417
387=head3 DBC/cursor methods 418=head2 DBC/cursor methods
388 419
389Methods available on DBC/$dbc handles: 420Methods available on DBC/$dbc handles:
390 421
391 DESTROY (DBC_ornull *dbc) 422 DESTROY (DBC_ornull *dbc)
392 CODE: 423 CODE:
393 if (dbc) 424 if (dbc)
394 dbc->c_close (dbc); 425 dbc->c_close (dbc);
395 426
396 $int = $cursor->set_priority ($priority = PRIORITY_*) 427 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
397 428
398=head4 Example: 429=head3 Example:
399 430
400 my $c = $db->cursor; 431 my $c = $db->cursor;
401 432
402 for (;;) { 433 for (;;) {
403 db_c_get $c, my $key, my $data, BDB::NEXT; 434 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
406 } 437 }
407 438
408 db_c_close $c; 439 db_c_close $c;
409 440
410 441
411=head3 DB_SEQUENCE/sequence methods 442=head2 DB_SEQUENCE/sequence methods
412 443
413Methods available on DB_SEQUENCE/$seq handles: 444Methods available on DB_SEQUENCE/$seq handles:
414 445
415 DESTROY (DB_SEQUENCE_ornull *seq) 446 DESTROY (DB_SEQUENCE_ornull *seq)
416 CODE: 447 CODE:
… …
421 $int = $seq->set_cachesize (U32 size) 452 $int = $seq->set_cachesize (U32 size)
422 $int = $seq->set_flags (U32 flags) 453 $int = $seq->set_flags (U32 flags)
423 flags: SEQ_DEC SEQ_INC SEQ_WRAP 454 flags: SEQ_DEC SEQ_INC SEQ_WRAP
424 $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)
425 456
426=head4 Example: 457=head3 Example:
427 458
428 my $seq = $db->sequence; 459 my $seq = $db->sequence;
429 460
430 db_sequence_open $seq, undef, "seq", BDB::CREATE; 461 db_sequence_open $seq, undef, "seq", BDB::CREATE;
431 db_sequence_get $seq, undef, 1, my $value; 462 db_sequence_get $seq, undef, 1, my $value;
432 463
433 464
434=head2 SUPPORT FUNCTIONS 465=head1 SUPPORT FUNCTIONS
435 466
436=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 467=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
437 468
438=over 4 469=over 4
439 470
440=item $msg = BDB::strerror [$errno] 471=item $msg = BDB::strerror [$errno]
441 472
… …
528 BDB::poll_wait, BDB::poll_cb 559 BDB::poll_wait, BDB::poll_cb
529 while BDB::nreqs; 560 while BDB::nreqs;
530 561
531=back 562=back
532 563
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
533=head3 CONTROLLING THE NUMBER OF THREADS 630=head2 CONTROLLING THE NUMBER OF THREADS
534 631
535=over 4 632=over 4
536 633
537=item BDB::min_parallel $nthreads 634=item BDB::min_parallel $nthreads
538 635
… …
599 696
600You can still queue as many requests as you want. Therefore, 697You can still queue as many requests as you want. Therefore,
601C<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
602as 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).
603 700
604=item BDB::set_sync_prepare $cb 701=item $old_cb = BDB::set_sync_prepare $cb
605 702
606Sets a callback that is called whenever a request is created without an 703Sets a callback that is called whenever a request is created without an
607explicit callback. It has to return two code references. The first is used 704explicit callback. It has to return two code references. The first is used
608as the request callback, and the second is called to wait until the first 705as the request callback (it should save the return status), and the second
609callback has been called. The default implementation works like this: 706is called to wait until the first callback has been called (it must set
707C<$!> to the return status).
708
709This mechanism can be used to include BDB into other event mechanisms,
710such as L<Coro::BDB>.
711
712To allow other, callback-based, events to be executed while callback-less
713ones are run, you could use this sync prepare function:
610 714
611 sub { 715 sub {
612 my $status; 716 my $status;
613 ( 717 (
614 sub { $status = $! }, 718 sub { $status = $! },
615 sub { BDB::poll while !defined $status; $! = $status }, 719 sub { BDB::poll while !defined $status; $! = $status },
616 ) 720 )
617 } 721 }
618 722
723It works by polling for results till the request has finished and then
724sets C<$!> to the return value. This means that if you don't use a
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.
730
619=back 731=back
620 732
621=head3 STATISTICAL INFORMATION 733=head2 STATISTICAL INFORMATION
622 734
623=over 4 735=over 4
624 736
625=item BDB::nreqs 737=item BDB::nreqs
626 738
… …
644 756
645=back 757=back
646 758
647=cut 759=cut
648 760
649set_sync_prepare { 761set_sync_prepare (undef);
650 my $status;
651 (
652 sub {
653 $status = $!;
654 },
655 sub {
656 BDB::poll while !defined $status;
657 $! = $status;
658 },
659 )
660};
661 762
662min_parallel 8; 763min_parallel 8;
663 764
664END { flush } 765END { flush }
665 766
6661; 7671;
667 768
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
668=head2 FORK BEHAVIOUR 792=head1 FORK BEHAVIOUR
669 793
670This 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:
671 795
672Before the fork, BDB enters a quiescent state where no requests 796Before the fork, BDB enters a quiescent state where no requests
673can 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
… …
683 807
684Win32 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
685broken 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
686yet, switch to a more capable platform. 810yet, switch to a more capable platform.
687 811
688=head2 MEMORY USAGE 812=head1 MEMORY USAGE
689 813
690Per-request usage: 814Per-request usage:
691 815
692Each aio request uses - depending on your architecture - around 100-200 816Each aio request uses - depending on your architecture - around 100-200
693bytes of memory. In addition, stat requests need a stat buffer (possibly 817bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
702 826
703In the execution phase, some aio requests require more memory for 827In the execution phase, some aio requests require more memory for
704temporary buffers, and each thread requires a stack and other data 828temporary buffers, and each thread requires a stack and other data
705structures (usually around 16k-128k, depending on the OS). 829structures (usually around 16k-128k, depending on the OS).
706 830
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
707=head1 KNOWN BUGS 840=head1 KNOWN BUGS
708 841
709Known bugs will be fixed in the next release, except: 842Known bugs will be fixed in the next release, except:
710 843
711 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
… …
713 TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>, 846 TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>,
714 above. 847 above.
715 848
716=head1 SEE ALSO 849=head1 SEE ALSO
717 850
718L<Coro::BDB>, L<IO::AIO>. 851L<AnyEvent::BDB> (event loop integration), L<Coro::BDB> (more natural
852syntax), L<IO::AIO> (nice to have).
719 853
720=head1 AUTHOR 854=head1 AUTHOR
721 855
722 Marc Lehmann <schmorp@schmorp.de> 856 Marc Lehmann <schmorp@schmorp.de>
723 http://home.schmorp.de/ 857 http://home.schmorp.de/

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