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Comparing BDB/BDB.pm (file contents):
Revision 1.34 by root, Sun Mar 30 06:17:31 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", $VERSION);
137} 139}
138 140
139=head2 FILENAMES/DATABASE NAMES
140
141The BDB expects "binary" filenames (octet strings) for pathnames on POSIX
142systems, and "unicode" filenames (strings with characters potentially
143>255) on Win32 (expecting a Unicode win32 build - win32 is a total mess).
144
145=head2 BERKELEYDB FUNCTIONS 141=head1 BERKELEYDB FUNCTIONS
146 142
147All of these are functions. The create functions simply return a new 143All of these are functions. The create functions simply return a new
148object and never block. All the remaining functions take an optional 144object and never block. All the remaining functions take an optional
149callback as last argument. If it is missing, then the function will be 145callback as last argument. If it is missing, then the function will be
150executed synchronously. In both cases, C<$!> will reflect the return value 146executed synchronously. In both cases, C<$!> will reflect the return value
… …
154settings) are method calls on the relevant objects, so the rule of thumb 150settings) are method calls on the relevant objects, so the rule of thumb
155is: if it's a method, it's not blocking, if it's a function, it takes a 151is: if it's a method, it's not blocking, if it's a function, it takes a
156callback as last argument. 152callback as last argument.
157 153
158In the following, C<$int> signifies an integer return value, 154In the following, C<$int> signifies an integer return value,
159C<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),
160indices >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
161integer, C<NV> is a floating point value. 157floating point value.
162 158
163The 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
164values), and the C<SV *callback> is the optional callback function to call 160values).
165when the request is completed.
166 161
167The various C<DB_ENV> etc. arguments are handles return by 162The various C<DB_ENV> etc. arguments are handles return by
168C<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
169appended 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>
170for them, resulting a NULL pointer on the C level. 165for them, resulting a NULL pointer on the C level.
171 166
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
172=head3 BDB functions 190=head2 BDB functions
173 191
174Functions in the BDB namespace, exported by default: 192Functions in the BDB namespace, exported by default:
175 193
176 $env = db_env_create (U32 env_flags = 0) 194 $env = db_env_create (U32 env_flags = 0)
177 flags: RPCCLIENT 195 flags: RPCCLIENT
178 196
179 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)
180 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
181 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)
182 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)
183 flags: FORCE 201 flags: FORCE
184 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)
185 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
186 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)
187 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)
188 209
189 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 210 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
190 flags: XA_CREATE 211 flags: XA_CREATE
191 212
192 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)
193 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
194 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)
195 flags: DB_NOSYNC 216 flags: DB_NOSYNC
196 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)
197 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)
198 flags: FREELIST_ONLY FREE_SPACE 219 flags: FREELIST_ONLY FREE_SPACE
199 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)
200 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)
201 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)
202 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)
203 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)
204 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
205 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)
206 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
207 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)
… …
224 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)
225 flags: TXN_NOSYNC 247 flags: TXN_NOSYNC
226 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)
227 flags: TXN_NOSYNC 249 flags: TXN_NOSYNC
228 250
229=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)
230 252
231This is not actually a Berkeley DB function but a BDB module 253This is not actually a Berkeley DB function but a BDB module
232extension. The background for this exytension is: It is very annoying to 254extension. The background for this exytension is: It is very annoying to
233have 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
234codepath out of your transaction. While the BDB module still makes this 256codepath out of your transaction. While the BDB module still makes this
… …
260 282
261You can use the C<< $txn->failed >> method to check wether a transaction 283You can use the C<< $txn->failed >> method to check wether a transaction
262has failed in this way and abort further processing (excluding 284has failed in this way and abort further processing (excluding
263C<db_txn_finish>). 285C<db_txn_finish>).
264 286
265=head3 DB_ENV/database environment methods 287=head2 DB_ENV/database environment methods
266 288
267Methods available on DB_ENV/$env handles: 289Methods available on DB_ENV/$env handles:
268 290
269 DESTROY (DB_ENV_ornull *env) 291 DESTROY (DB_ENV_ornull *env)
270 CODE: 292 CODE:
… …
274 $int = $env->set_data_dir (const char *dir) 296 $int = $env->set_data_dir (const char *dir)
275 $int = $env->set_tmp_dir (const char *dir) 297 $int = $env->set_tmp_dir (const char *dir)
276 $int = $env->set_lg_dir (const char *dir) 298 $int = $env->set_lg_dir (const char *dir)
277 $int = $env->set_shm_key (long shm_key) 299 $int = $env->set_shm_key (long shm_key)
278 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 300 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
279 $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)
280 $env->set_errfile (FILE *errfile = 0) 304 $env->set_errfile (FILE *errfile = 0)
281 $env->set_msgfile (FILE *msgfile = 0) 305 $env->set_msgfile (FILE *msgfile = 0)
282 $int = $env->set_verbose (U32 which, int onoff = 1) 306 $int = $env->set_verbose (U32 which, int onoff = 1)
283 $int = $env->set_encrypt (const char *password, U32 flags = 0) 307 $int = $env->set_encrypt (const char *password, U32 flags = 0)
284 $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)
… …
296 $int = $env->mutex_set_max (U32 max) 320 $int = $env->mutex_set_max (U32 max)
297 $int = $env->mutex_set_align (U32 align) 321 $int = $env->mutex_set_align (U32 align)
298 322
299 $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)
300 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)
301 326
302=head4 Example: 327=head3 Example:
303 328
304 use AnyEvent; 329 use AnyEvent;
305 use BDB; 330 use BDB;
306 331
307 our $FH; open $FH, "<&=" . BDB::poll_fileno; 332 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
319 0600; 344 0600;
320 345
321 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); 346 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
322 347
323 348
324=head3 DB/database methods 349=head2 DB/database methods
325 350
326Methods available on DB/$db handles: 351Methods available on DB/$db handles:
327 352
328 DESTROY (DB_ornull *db) 353 DESTROY (DB_ornull *db)
329 CODE: 354 CODE:
… …
355 380
356 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 381 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
357 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT 382 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
358 $seq = $db->sequence (U32 flags = 0) 383 $seq = $db->sequence (U32 flags = 0)
359 384
360=head4 Example: 385=head3 Example:
361 386
362 my $db = db_create $env; 387 my $db = db_create $env;
363 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;
364 389
365 for (1..1000) { 390 for (1..1000) {
… …
372 db_del $db, undef, "key $_" for 1..1000; 397 db_del $db, undef, "key $_" for 1..1000;
373 398
374 db_sync $db; 399 db_sync $db;
375 400
376 401
377=head3 DB_TXN/transaction methods 402=head2 DB_TXN/transaction methods
378 403
379Methods available on DB_TXN/$txn handles: 404Methods available on DB_TXN/$txn handles:
380 405
381 DESTROY (DB_TXN_ornull *txn) 406 DESTROY (DB_TXN_ornull *txn)
382 CODE: 407 CODE:
… …
388 413
389 $bool = $txn->failed 414 $bool = $txn->failed
390 # see db_txn_finish documentation, above 415 # see db_txn_finish documentation, above
391 416
392 417
393=head3 DBC/cursor methods 418=head2 DBC/cursor methods
394 419
395Methods available on DBC/$dbc handles: 420Methods available on DBC/$dbc handles:
396 421
397 DESTROY (DBC_ornull *dbc) 422 DESTROY (DBC_ornull *dbc)
398 CODE: 423 CODE:
399 if (dbc) 424 if (dbc)
400 dbc->c_close (dbc); 425 dbc->c_close (dbc);
401 426
402 $int = $cursor->set_priority ($priority = PRIORITY_*) 427 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
403 428
404=head4 Example: 429=head3 Example:
405 430
406 my $c = $db->cursor; 431 my $c = $db->cursor;
407 432
408 for (;;) { 433 for (;;) {
409 db_c_get $c, my $key, my $data, BDB::NEXT; 434 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
412 } 437 }
413 438
414 db_c_close $c; 439 db_c_close $c;
415 440
416 441
417=head3 DB_SEQUENCE/sequence methods 442=head2 DB_SEQUENCE/sequence methods
418 443
419Methods available on DB_SEQUENCE/$seq handles: 444Methods available on DB_SEQUENCE/$seq handles:
420 445
421 DESTROY (DB_SEQUENCE_ornull *seq) 446 DESTROY (DB_SEQUENCE_ornull *seq)
422 CODE: 447 CODE:
… …
427 $int = $seq->set_cachesize (U32 size) 452 $int = $seq->set_cachesize (U32 size)
428 $int = $seq->set_flags (U32 flags) 453 $int = $seq->set_flags (U32 flags)
429 flags: SEQ_DEC SEQ_INC SEQ_WRAP 454 flags: SEQ_DEC SEQ_INC SEQ_WRAP
430 $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)
431 456
432=head4 Example: 457=head3 Example:
433 458
434 my $seq = $db->sequence; 459 my $seq = $db->sequence;
435 460
436 db_sequence_open $seq, undef, "seq", BDB::CREATE; 461 db_sequence_open $seq, undef, "seq", BDB::CREATE;
437 db_sequence_get $seq, undef, 1, my $value; 462 db_sequence_get $seq, undef, 1, my $value;
438 463
439 464
440=head2 SUPPORT FUNCTIONS 465=head1 SUPPORT FUNCTIONS
441 466
442=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 467=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
443 468
444=over 4 469=over 4
445 470
446=item $msg = BDB::strerror [$errno] 471=item $msg = BDB::strerror [$errno]
447 472
… …
534 BDB::poll_wait, BDB::poll_cb 559 BDB::poll_wait, BDB::poll_cb
535 while BDB::nreqs; 560 while BDB::nreqs;
536 561
537=back 562=back
538 563
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
539=head3 CONTROLLING THE NUMBER OF THREADS 630=head2 CONTROLLING THE NUMBER OF THREADS
540 631
541=over 4 632=over 4
542 633
543=item BDB::min_parallel $nthreads 634=item BDB::min_parallel $nthreads
544 635
… …
605 696
606You can still queue as many requests as you want. Therefore, 697You can still queue as many requests as you want. Therefore,
607C<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
608as 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).
609 700
610=item BDB::set_sync_prepare $cb 701=item $old_cb = BDB::set_sync_prepare $cb
611 702
612Sets a callback that is called whenever a request is created without an 703Sets a callback that is called whenever a request is created without an
613explicit callback. It has to return two code references. The first is used 704explicit callback. It has to return two code references. The first is used
614as the request callback, and the second is called to wait until the first 705as the request callback (it should save the return status), and the second
615callback has been called. The default implementation works like this: 706is called to wait until the first callback has been called (it must set
707C<$!> 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:
616 714
617 sub { 715 sub {
618 my $status; 716 my $status;
619 ( 717 (
620 sub { $status = $! }, 718 sub { $status = $! },
621 sub { BDB::poll while !defined $status; $! = $status }, 719 sub { BDB::poll while !defined $status; $! = $status },
622 ) 720 )
623 } 721 }
624 722
723It works by polling for results till the request has finished and then
724sets C<$!> 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
625=back 731=back
626 732
627=head3 STATISTICAL INFORMATION 733=head2 STATISTICAL INFORMATION
628 734
629=over 4 735=over 4
630 736
631=item BDB::nreqs 737=item BDB::nreqs
632 738
… …
650 756
651=back 757=back
652 758
653=cut 759=cut
654 760
655set_sync_prepare { 761set_sync_prepare (undef);
656 my $status;
657 (
658 sub {
659 $status = $!;
660 },
661 sub {
662 BDB::poll while !defined $status;
663 $! = $status;
664 },
665 )
666};
667 762
668min_parallel 8; 763min_parallel 8;
669 764
670END { flush } 765END { flush }
671 766
6721; 7671;
673 768
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
674=head2 FORK BEHAVIOUR 792=head1 FORK BEHAVIOUR
675 793
676This 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:
677 795
678Before the fork, BDB enters a quiescent state where no requests 796Before the fork, BDB enters a quiescent state where no requests
679can 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
… …
689 807
690Win32 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
691broken 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
692yet, switch to a more capable platform. 810yet, switch to a more capable platform.
693 811
694=head2 MEMORY USAGE 812=head1 MEMORY USAGE
695 813
696Per-request usage: 814Per-request usage:
697 815
698Each aio request uses - depending on your architecture - around 100-200 816Each aio request uses - depending on your architecture - around 100-200
699bytes of memory. In addition, stat requests need a stat buffer (possibly 817bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
708 826
709In the execution phase, some aio requests require more memory for 827In the execution phase, some aio requests require more memory for
710temporary buffers, and each thread requires a stack and other data 828temporary buffers, and each thread requires a stack and other data
711structures (usually around 16k-128k, depending on the OS). 829structures (usually around 16k-128k, depending on the OS).
712 830
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
713=head1 KNOWN BUGS 840=head1 KNOWN BUGS
714 841
715Known bugs will be fixed in the next release, except: 842Known bugs will be fixed in the next release, except:
716 843
717 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
… …
719 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>,
720 above. 847 above.
721 848
722=head1 SEE ALSO 849=head1 SEE ALSO
723 850
724L<Coro::BDB>, L<IO::AIO>. 851L<AnyEvent::BDB> (event loop integration), L<Coro::BDB> (more natural
852syntax), L<IO::AIO> (nice to have).
725 853
726=head1 AUTHOR 854=head1 AUTHOR
727 855
728 Marc Lehmann <schmorp@schmorp.de> 856 Marc Lehmann <schmorp@schmorp.de>
729 http://home.schmorp.de/ 857 http://home.schmorp.de/

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