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Comparing BDB/BDB.pm (file contents):
Revision 1.35 by root, Sun Mar 30 08:01:58 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:
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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 = '1.45'; 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 );
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134 136
135 require XSLoader; 137 require XSLoader;
136 XSLoader::load ("BDB", $VERSION); 138 XSLoader::load ("BDB", $VERSION);
137} 139}
138 140
139=head2 WIN32 FILENAMES/DATABASE NAME MESS
140
141Perl on Win32 supports only ASCII filenames (the reason is that it abuses
142an internal flag to store wether a filename is Unicode or ANSI, but that
143flag is used for somethign else in the perl core, so there is no way to
144detect wether a filename is ANSI or Unicode-encoded). The BDB module
145tries to work around this issue by assuming that the filename is an ANSI
146filename and BDB was built for unicode support.
147
148=head2 BERKELEYDB FUNCTIONS 141=head1 BERKELEYDB FUNCTIONS
149 142
150All of these are functions. The create functions simply return a new 143All of these are functions. The create functions simply return a new
151object and never block. All the remaining functions take an optional 144object and never block. All the remaining functions take an optional
152callback as last argument. If it is missing, then the function will be 145callback as last argument. If it is missing, then the function will be
153executed synchronously. In both cases, C<$!> will reflect the return value 146executed synchronously. In both cases, C<$!> will reflect the return value
… …
157settings) are method calls on the relevant objects, so the rule of thumb 150settings) are method calls on the relevant objects, so the rule of thumb
158is: if it's a method, it's not blocking, if it's a function, it takes a 151is: if it's a method, it's not blocking, if it's a function, it takes a
159callback as last argument. 152callback as last argument.
160 153
161In the following, C<$int> signifies an integer return value, 154In the following, C<$int> signifies an integer return value,
162C<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),
163indices >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
164integer, C<NV> is a floating point value. 157floating point value.
165 158
166The 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
167values), and the C<SV *callback> is the optional callback function to call 160values).
168when the request is completed.
169 161
170The various C<DB_ENV> etc. arguments are handles return by 162The various C<DB_ENV> etc. arguments are handles return by
171C<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
172appended 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>
173for them, resulting a NULL pointer on the C level. 165for them, resulting a NULL pointer on the C level.
174 166
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
175=head3 BDB functions 190=head2 BDB functions
176 191
177Functions in the BDB namespace, exported by default: 192Functions in the BDB namespace, exported by default:
178 193
179 $env = db_env_create (U32 env_flags = 0) 194 $env = db_env_create (U32 env_flags = 0)
180 flags: RPCCLIENT 195 flags: RPCCLIENT
181 196
182 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)
183 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
184 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)
185 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)
186 flags: FORCE 201 flags: FORCE
187 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)
188 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
189 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)
190 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)
191 209
192 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 210 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
193 flags: XA_CREATE 211 flags: XA_CREATE
194 212
195 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)
196 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
197 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)
198 flags: DB_NOSYNC 216 flags: DB_NOSYNC
199 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)
200 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)
201 flags: FREELIST_ONLY FREE_SPACE 219 flags: FREELIST_ONLY FREE_SPACE
202 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)
203 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)
204 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)
205 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)
206 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)
207 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
208 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)
209 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
210 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)
… …
227 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)
228 flags: TXN_NOSYNC 247 flags: TXN_NOSYNC
229 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)
230 flags: TXN_NOSYNC 249 flags: TXN_NOSYNC
231 250
232=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)
233 252
234This is not actually a Berkeley DB function but a BDB module 253This is not actually a Berkeley DB function but a BDB module
235extension. The background for this exytension is: It is very annoying to 254extension. The background for this exytension is: It is very annoying to
236have 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
237codepath out of your transaction. While the BDB module still makes this 256codepath out of your transaction. While the BDB module still makes this
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263 282
264You can use the C<< $txn->failed >> method to check wether a transaction 283You can use the C<< $txn->failed >> method to check wether a transaction
265has failed in this way and abort further processing (excluding 284has failed in this way and abort further processing (excluding
266C<db_txn_finish>). 285C<db_txn_finish>).
267 286
268=head3 DB_ENV/database environment methods 287=head2 DB_ENV/database environment methods
269 288
270Methods available on DB_ENV/$env handles: 289Methods available on DB_ENV/$env handles:
271 290
272 DESTROY (DB_ENV_ornull *env) 291 DESTROY (DB_ENV_ornull *env)
273 CODE: 292 CODE:
… …
277 $int = $env->set_data_dir (const char *dir) 296 $int = $env->set_data_dir (const char *dir)
278 $int = $env->set_tmp_dir (const char *dir) 297 $int = $env->set_tmp_dir (const char *dir)
279 $int = $env->set_lg_dir (const char *dir) 298 $int = $env->set_lg_dir (const char *dir)
280 $int = $env->set_shm_key (long shm_key) 299 $int = $env->set_shm_key (long shm_key)
281 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 300 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
282 $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)
283 $env->set_errfile (FILE *errfile = 0) 304 $env->set_errfile (FILE *errfile = 0)
284 $env->set_msgfile (FILE *msgfile = 0) 305 $env->set_msgfile (FILE *msgfile = 0)
285 $int = $env->set_verbose (U32 which, int onoff = 1) 306 $int = $env->set_verbose (U32 which, int onoff = 1)
286 $int = $env->set_encrypt (const char *password, U32 flags = 0) 307 $int = $env->set_encrypt (const char *password, U32 flags = 0)
287 $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)
… …
299 $int = $env->mutex_set_max (U32 max) 320 $int = $env->mutex_set_max (U32 max)
300 $int = $env->mutex_set_align (U32 align) 321 $int = $env->mutex_set_align (U32 align)
301 322
302 $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)
303 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)
304 326
305=head4 Example: 327=head3 Example:
306 328
307 use AnyEvent; 329 use AnyEvent;
308 use BDB; 330 use BDB;
309 331
310 our $FH; open $FH, "<&=" . BDB::poll_fileno; 332 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
322 0600; 344 0600;
323 345
324 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); 346 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
325 347
326 348
327=head3 DB/database methods 349=head2 DB/database methods
328 350
329Methods available on DB/$db handles: 351Methods available on DB/$db handles:
330 352
331 DESTROY (DB_ornull *db) 353 DESTROY (DB_ornull *db)
332 CODE: 354 CODE:
… …
358 380
359 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 381 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
360 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT 382 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
361 $seq = $db->sequence (U32 flags = 0) 383 $seq = $db->sequence (U32 flags = 0)
362 384
363=head4 Example: 385=head3 Example:
364 386
365 my $db = db_create $env; 387 my $db = db_create $env;
366 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;
367 389
368 for (1..1000) { 390 for (1..1000) {
… …
375 db_del $db, undef, "key $_" for 1..1000; 397 db_del $db, undef, "key $_" for 1..1000;
376 398
377 db_sync $db; 399 db_sync $db;
378 400
379 401
380=head3 DB_TXN/transaction methods 402=head2 DB_TXN/transaction methods
381 403
382Methods available on DB_TXN/$txn handles: 404Methods available on DB_TXN/$txn handles:
383 405
384 DESTROY (DB_TXN_ornull *txn) 406 DESTROY (DB_TXN_ornull *txn)
385 CODE: 407 CODE:
… …
391 413
392 $bool = $txn->failed 414 $bool = $txn->failed
393 # see db_txn_finish documentation, above 415 # see db_txn_finish documentation, above
394 416
395 417
396=head3 DBC/cursor methods 418=head2 DBC/cursor methods
397 419
398Methods available on DBC/$dbc handles: 420Methods available on DBC/$dbc handles:
399 421
400 DESTROY (DBC_ornull *dbc) 422 DESTROY (DBC_ornull *dbc)
401 CODE: 423 CODE:
402 if (dbc) 424 if (dbc)
403 dbc->c_close (dbc); 425 dbc->c_close (dbc);
404 426
405 $int = $cursor->set_priority ($priority = PRIORITY_*) 427 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
406 428
407=head4 Example: 429=head3 Example:
408 430
409 my $c = $db->cursor; 431 my $c = $db->cursor;
410 432
411 for (;;) { 433 for (;;) {
412 db_c_get $c, my $key, my $data, BDB::NEXT; 434 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
415 } 437 }
416 438
417 db_c_close $c; 439 db_c_close $c;
418 440
419 441
420=head3 DB_SEQUENCE/sequence methods 442=head2 DB_SEQUENCE/sequence methods
421 443
422Methods available on DB_SEQUENCE/$seq handles: 444Methods available on DB_SEQUENCE/$seq handles:
423 445
424 DESTROY (DB_SEQUENCE_ornull *seq) 446 DESTROY (DB_SEQUENCE_ornull *seq)
425 CODE: 447 CODE:
… …
430 $int = $seq->set_cachesize (U32 size) 452 $int = $seq->set_cachesize (U32 size)
431 $int = $seq->set_flags (U32 flags) 453 $int = $seq->set_flags (U32 flags)
432 flags: SEQ_DEC SEQ_INC SEQ_WRAP 454 flags: SEQ_DEC SEQ_INC SEQ_WRAP
433 $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)
434 456
435=head4 Example: 457=head3 Example:
436 458
437 my $seq = $db->sequence; 459 my $seq = $db->sequence;
438 460
439 db_sequence_open $seq, undef, "seq", BDB::CREATE; 461 db_sequence_open $seq, undef, "seq", BDB::CREATE;
440 db_sequence_get $seq, undef, 1, my $value; 462 db_sequence_get $seq, undef, 1, my $value;
441 463
442 464
443=head2 SUPPORT FUNCTIONS 465=head1 SUPPORT FUNCTIONS
444 466
445=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 467=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
446 468
447=over 4 469=over 4
448 470
449=item $msg = BDB::strerror [$errno] 471=item $msg = BDB::strerror [$errno]
450 472
… …
537 BDB::poll_wait, BDB::poll_cb 559 BDB::poll_wait, BDB::poll_cb
538 while BDB::nreqs; 560 while BDB::nreqs;
539 561
540=back 562=back
541 563
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
542=head3 CONTROLLING THE NUMBER OF THREADS 630=head2 CONTROLLING THE NUMBER OF THREADS
543 631
544=over 4 632=over 4
545 633
546=item BDB::min_parallel $nthreads 634=item BDB::min_parallel $nthreads
547 635
… …
608 696
609You can still queue as many requests as you want. Therefore, 697You can still queue as many requests as you want. Therefore,
610C<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
611as 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).
612 700
613=item BDB::set_sync_prepare $cb 701=item $old_cb = BDB::set_sync_prepare $cb
614 702
615Sets a callback that is called whenever a request is created without an 703Sets a callback that is called whenever a request is created without an
616explicit callback. It has to return two code references. The first is used 704explicit callback. It has to return two code references. The first is used
617as the request callback, and the second is called to wait until the first 705as the request callback (it should save the return status), and the second
618callback has been called. The default implementation works like this: 706is called to wait until the first callback has been called (it must set
707C<$!> 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:
619 714
620 sub { 715 sub {
621 my $status; 716 my $status;
622 ( 717 (
623 sub { $status = $! }, 718 sub { $status = $! },
624 sub { BDB::poll while !defined $status; $! = $status }, 719 sub { BDB::poll while !defined $status; $! = $status },
625 ) 720 )
626 } 721 }
627 722
723It works by polling for results till the request has finished and then
724sets C<$!> 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
628=back 731=back
629 732
630=head3 STATISTICAL INFORMATION 733=head2 STATISTICAL INFORMATION
631 734
632=over 4 735=over 4
633 736
634=item BDB::nreqs 737=item BDB::nreqs
635 738
… …
653 756
654=back 757=back
655 758
656=cut 759=cut
657 760
658set_sync_prepare { 761set_sync_prepare (undef);
659 my $status;
660 (
661 sub {
662 $status = $!;
663 },
664 sub {
665 BDB::poll while !defined $status;
666 $! = $status;
667 },
668 )
669};
670 762
671min_parallel 8; 763min_parallel 8;
672 764
673END { flush } 765END { flush }
674 766
6751; 7671;
676 768
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
677=head2 FORK BEHAVIOUR 792=head1 FORK BEHAVIOUR
678 793
679This 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:
680 795
681Before the fork, BDB enters a quiescent state where no requests 796Before the fork, BDB enters a quiescent state where no requests
682can 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
… …
692 807
693Win32 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
694broken 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
695yet, switch to a more capable platform. 810yet, switch to a more capable platform.
696 811
697=head2 MEMORY USAGE 812=head1 MEMORY USAGE
698 813
699Per-request usage: 814Per-request usage:
700 815
701Each aio request uses - depending on your architecture - around 100-200 816Each aio request uses - depending on your architecture - around 100-200
702bytes of memory. In addition, stat requests need a stat buffer (possibly 817bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
711 826
712In the execution phase, some aio requests require more memory for 827In the execution phase, some aio requests require more memory for
713temporary buffers, and each thread requires a stack and other data 828temporary buffers, and each thread requires a stack and other data
714structures (usually around 16k-128k, depending on the OS). 829structures (usually around 16k-128k, depending on the OS).
715 830
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
716=head1 KNOWN BUGS 840=head1 KNOWN BUGS
717 841
718Known bugs will be fixed in the next release, except: 842Known bugs will be fixed in the next release, except:
719 843
720 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
… …
722 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>,
723 above. 847 above.
724 848
725=head1 SEE ALSO 849=head1 SEE ALSO
726 850
727L<Coro::BDB>, L<IO::AIO>. 851L<AnyEvent::BDB> (event loop integration), L<Coro::BDB> (more natural
852syntax), L<IO::AIO> (nice to have).
728 853
729=head1 AUTHOR 854=head1 AUTHOR
730 855
731 Marc Lehmann <schmorp@schmorp.de> 856 Marc Lehmann <schmorp@schmorp.de>
732 http://home.schmorp.de/ 857 http://home.schmorp.de/

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