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Comparing BDB/BDB.pm (file contents):
Revision 1.38 by root, Mon Jul 7 22:11:04 2008 UTC vs.
Revision 1.56 by root, Fri Jan 9 22:32:12 2009 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 = '1.83';
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 db_env_dbrename db_env_dbremove 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_verify 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<$!> will reflect the return value
… …
160In the following, C<$int> signifies an integer return value, 154In the following, C<$int> signifies an integer return value,
161C<bdb_filename> is a "filename" (octets on unix, madness on windows), 155C<bdb_filename> is a "filename" (octets on unix, madness on windows),
162C<U32> is an unsigned 32 bit integer, C<int> is some integer, C<NV> is a 156C<U32> is an unsigned 32 bit integer, C<int> is some integer, C<NV> is a
163floating 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, bdb_filename 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 = 0)
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 = 0)
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 = 0)
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 = 0)
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 = 0)
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 = 0)
190 db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 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 = 0)
191 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) 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 = 0)
208 db_env_log_archive (DB_ENV *env, SV *listp, U32 flags = 0, SV *callback = 0)
192 209
193 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 210 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
194 flags: XA_CREATE 211 flags: XA_CREATE
195 212
196 db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef) 213 db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = 0)
197 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
198 db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 215 db_close (DB *db, U32 flags = 0, SV *callback = 0)
199 flags: DB_NOSYNC 216 flags: DB_NOSYNC
217 db_verify (DB *db, bdb_filename file, bdb_filename database = 0, SV *dummy = 0, U32 flags = 0, SV *callback = 0)
200 db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = &PL_sv_undef) 218 db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = 0)
201 db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = &PL_sv_undef) 219 db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = 0)
202 flags: FREELIST_ONLY FREE_SPACE 220 flags: FREELIST_ONLY FREE_SPACE
203 db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 221 db_sync (DB *db, U32 flags = 0, SV *callback = 0)
204 db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef) 222 db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = 0)
205 db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 223 db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
206 flags: APPEND NODUPDATA NOOVERWRITE 224 flags: APPEND NODUPDATA NOOVERWRITE
225 db_exists (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0) (v4.6)
207 db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 226 db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
208 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW 227 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
209 db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 228 db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0)
210 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW 229 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
211 db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) 230 db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0)
212 db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) 231 db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = 0)
213 flags: TXN_NOSYNC TXN_SYNC 232 flags: TXN_NOSYNC TXN_SYNC
214 db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef) 233 db_txn_abort (DB_TXN *txn, SV *callback = 0)
215 234
216 db_c_close (DBC *dbc, SV *callback = &PL_sv_undef) 235 db_c_close (DBC *dbc, SV *callback = 0)
217 db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = &PL_sv_undef) 236 db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = 0)
218 db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 237 db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
219 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA 238 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA
220 db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 239 db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
221 flags: CURRENT FIRST GET_BOTH GET_BOTH_RANGE GET_RECNO JOIN_ITEM LAST NEXT NEXT_DUP NEXT_NODUP PREV PREV_DUP PREV_NODUP SET SET_RANGE SET_RECNO READ_UNCOMMITTED MULTIPLE MULTIPLE_KEY RMW 240 flags: CURRENT FIRST GET_BOTH GET_BOTH_RANGE GET_RECNO JOIN_ITEM LAST NEXT NEXT_DUP NEXT_NODUP PREV PREV_DUP PREV_NODUP SET SET_RANGE SET_RECNO READ_UNCOMMITTED MULTIPLE MULTIPLE_KEY RMW
222 db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 241 db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0)
223 db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef) 242 db_c_del (DBC *dbc, U32 flags = 0, SV *callback = 0)
224 243
225 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) 244 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = 0)
226 flags: CREATE EXCL 245 flags: CREATE EXCL
227 db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef) 246 db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = 0)
228 db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = &PL_sv_undef) 247 db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = 0)
229 flags: TXN_NOSYNC 248 flags: TXN_NOSYNC
230 db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) 249 db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = 0)
231 flags: TXN_NOSYNC 250 flags: TXN_NOSYNC
232 251
233=head4 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) 252=head3 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = 0)
234 253
235This is not actually a Berkeley DB function but a BDB module 254This is not actually a Berkeley DB function but a BDB module
236extension. The background for this exytension is: It is very annoying to 255extension. The background for this exytension is: It is very annoying to
237have to check every single BDB function for error returns and provide a 256have to check every single BDB function for error returns and provide a
238codepath out of your transaction. While the BDB module still makes this 257codepath out of your transaction. While the BDB module still makes this
… …
264 283
265You can use the C<< $txn->failed >> method to check wether a transaction 284You can use the C<< $txn->failed >> method to check wether a transaction
266has failed in this way and abort further processing (excluding 285has failed in this way and abort further processing (excluding
267C<db_txn_finish>). 286C<db_txn_finish>).
268 287
288
269=head3 DB_ENV/database environment methods 289=head2 DB_ENV/database environment methods
270 290
271Methods available on DB_ENV/$env handles: 291Methods available on DB_ENV/$env handles:
272 292
273 DESTROY (DB_ENV_ornull *env) 293 DESTROY (DB_ENV_ornull *env)
274 CODE: 294 CODE:
… …
278 $int = $env->set_data_dir (const char *dir) 298 $int = $env->set_data_dir (const char *dir)
279 $int = $env->set_tmp_dir (const char *dir) 299 $int = $env->set_tmp_dir (const char *dir)
280 $int = $env->set_lg_dir (const char *dir) 300 $int = $env->set_lg_dir (const char *dir)
281 $int = $env->set_shm_key (long shm_key) 301 $int = $env->set_shm_key (long shm_key)
282 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 302 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
283 $int = $env->set_flags (U32 flags, int onoff) 303 $int = $env->set_flags (U32 flags, int onoff = 1)
304 $int = $env->log_set_config (U32 flags, int onoff = 1) (v4.7)
305 $int = $env->set_intermediate_dir_mode (const char *modestring) (v4.7)
284 $env->set_errfile (FILE *errfile = 0) 306 $env->set_errfile (FILE *errfile = 0)
285 $env->set_msgfile (FILE *msgfile = 0) 307 $env->set_msgfile (FILE *msgfile = 0)
286 $int = $env->set_verbose (U32 which, int onoff = 1) 308 $int = $env->set_verbose (U32 which, int onoff = 1)
287 $int = $env->set_encrypt (const char *password, U32 flags = 0) 309 $int = $env->set_encrypt (const char *password, U32 flags = 0)
288 $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT) 310 $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT)
… …
300 $int = $env->mutex_set_max (U32 max) 322 $int = $env->mutex_set_max (U32 max)
301 $int = $env->mutex_set_align (U32 align) 323 $int = $env->mutex_set_align (U32 align)
302 324
303 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) 325 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0)
304 flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC 326 flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC
327 $txn = $env->cdsgroup_begin; (v4.5)
305 328
306=head4 Example: 329=head3 Example:
307 330
308 use AnyEvent; 331 use AnyEvent;
309 use BDB; 332 use BDB;
310 333
311 our $FH; open $FH, "<&=" . BDB::poll_fileno; 334 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
323 0600; 346 0600;
324 347
325 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); 348 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
326 349
327 350
328=head3 DB/database methods 351=head2 DB/database methods
329 352
330Methods available on DB/$db handles: 353Methods available on DB/$db handles:
331 354
332 DESTROY (DB_ornull *db) 355 DESTROY (DB_ornull *db)
333 CODE: 356 CODE:
… …
359 382
360 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 383 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
361 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT 384 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
362 $seq = $db->sequence (U32 flags = 0) 385 $seq = $db->sequence (U32 flags = 0)
363 386
364=head4 Example: 387=head3 Example:
365 388
366 my $db = db_create $env; 389 my $db = db_create $env;
367 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600; 390 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600;
368 391
369 for (1..1000) { 392 for (1..1000) {
… …
376 db_del $db, undef, "key $_" for 1..1000; 399 db_del $db, undef, "key $_" for 1..1000;
377 400
378 db_sync $db; 401 db_sync $db;
379 402
380 403
381=head3 DB_TXN/transaction methods 404=head2 DB_TXN/transaction methods
382 405
383Methods available on DB_TXN/$txn handles: 406Methods available on DB_TXN/$txn handles:
384 407
385 DESTROY (DB_TXN_ornull *txn) 408 DESTROY (DB_TXN_ornull *txn)
386 CODE: 409 CODE:
… …
392 415
393 $bool = $txn->failed 416 $bool = $txn->failed
394 # see db_txn_finish documentation, above 417 # see db_txn_finish documentation, above
395 418
396 419
397=head3 DBC/cursor methods 420=head2 DBC/cursor methods
398 421
399Methods available on DBC/$dbc handles: 422Methods available on DBC/$dbc handles:
400 423
401 DESTROY (DBC_ornull *dbc) 424 DESTROY (DBC_ornull *dbc)
402 CODE: 425 CODE:
403 if (dbc) 426 if (dbc)
404 dbc->c_close (dbc); 427 dbc->c_close (dbc);
405 428
406 $int = $cursor->set_priority ($priority = PRIORITY_*) 429 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
407 430
408=head4 Example: 431=head3 Example:
409 432
410 my $c = $db->cursor; 433 my $c = $db->cursor;
411 434
412 for (;;) { 435 for (;;) {
413 db_c_get $c, my $key, my $data, BDB::NEXT; 436 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
416 } 439 }
417 440
418 db_c_close $c; 441 db_c_close $c;
419 442
420 443
421=head3 DB_SEQUENCE/sequence methods 444=head2 DB_SEQUENCE/sequence methods
422 445
423Methods available on DB_SEQUENCE/$seq handles: 446Methods available on DB_SEQUENCE/$seq handles:
424 447
425 DESTROY (DB_SEQUENCE_ornull *seq) 448 DESTROY (DB_SEQUENCE_ornull *seq)
426 CODE: 449 CODE:
… …
431 $int = $seq->set_cachesize (U32 size) 454 $int = $seq->set_cachesize (U32 size)
432 $int = $seq->set_flags (U32 flags) 455 $int = $seq->set_flags (U32 flags)
433 flags: SEQ_DEC SEQ_INC SEQ_WRAP 456 flags: SEQ_DEC SEQ_INC SEQ_WRAP
434 $int = $seq->set_range (db_seq_t min, db_seq_t max) 457 $int = $seq->set_range (db_seq_t min, db_seq_t max)
435 458
436=head4 Example: 459=head3 Example:
437 460
438 my $seq = $db->sequence; 461 my $seq = $db->sequence;
439 462
440 db_sequence_open $seq, undef, "seq", BDB::CREATE; 463 db_sequence_open $seq, undef, "seq", BDB::CREATE;
441 db_sequence_get $seq, undef, 1, my $value; 464 db_sequence_get $seq, undef, 1, my $value;
442 465
443 466
444=head2 SUPPORT FUNCTIONS 467=head1 SUPPORT FUNCTIONS
445 468
446=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 469=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
447 470
448=over 4 471=over 4
449 472
450=item $msg = BDB::strerror [$errno] 473=item $msg = BDB::strerror [$errno]
451 474
… …
538 BDB::poll_wait, BDB::poll_cb 561 BDB::poll_wait, BDB::poll_cb
539 while BDB::nreqs; 562 while BDB::nreqs;
540 563
541=back 564=back
542 565
566=head2 VERSION CHECKING
567
568BerkeleyDB comes in various versions, many of them have minor
569incompatibilities. This means that traditional "at least version x.x"
570checks are often not sufficient.
571
572Example: set the log_autoremove option in a way compatible with <v4.7 and
573v4.7. Note the use of & on the constants to avoid triggering a compiletime
574bug when the symbol isn't available.
575
576 $DB_ENV->set_flags (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7;
577 $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;
578
579=over 4
580
581=item BDB::VERSION
582
583The C<BDB::VERSION> function, when called without arguments, returns the
584Berkeley DB version as a v-string (usually with 3 components). You should
585use C<lt> and C<ge> operators exclusively to make comparisons.
586
587Example: check for at least version 4.7.
588
589 BDB::VERSION ge v4.7 or die;
590
591=item BDB::VERSION min-version
592
593Returns true if the BDB version is at least the given version (specified
594as a v-string), false otherwise.
595
596Example: check for at least version 4.5.
597
598 BDB::VERSION v4.7 or die;
599
600=item BDB::VERSION min-version, max-version
601
602Returns true of the BDB version is at least version C<min-version> (specify C<undef> or C<v0> for any minimum version)
603and less then C<max-version>.
604
605Example: check wether version is strictly less then v4.7.
606
607 BDB::VERSION v0, v4.7
608 or die "version 4.7 is not yet supported";
609
610=back
611
612=cut
613
614sub VERSION {
615 # I was dumb enough to override the VERSION method here, so let's try
616 # to fix it up.
617
618 if ($_[0] eq __PACKAGE__) {
619 $VERSION
620 } else {
621 if (@_ > 0) {
622 return undef if VERSION_v lt $_[0];
623 if (@_ > 1) {
624 return undef if VERSION_v ge $_[1];
625 }
626 }
627
628 VERSION_v
629 }
630}
631
543=head3 CONTROLLING THE NUMBER OF THREADS 632=head2 CONTROLLING THE NUMBER OF THREADS
544 633
545=over 4 634=over 4
546 635
547=item BDB::min_parallel $nthreads 636=item BDB::min_parallel $nthreads
548 637
… …
609 698
610You can still queue as many requests as you want. Therefore, 699You can still queue as many requests as you want. Therefore,
611C<max_oustsanding> is mainly useful in simple scripts (with low values) or 700C<max_oustsanding> is mainly useful in simple scripts (with low values) or
612as a stop gap to shield against fatal memory overflow (with large values). 701as a stop gap to shield against fatal memory overflow (with large values).
613 702
614=item BDB::set_sync_prepare $cb 703=item $old_cb = BDB::set_sync_prepare $cb
615 704
616Sets a callback that is called whenever a request is created without an 705Sets a callback that is called whenever a request is created without an
617explicit callback. It has to return two code references. The first is used 706explicit callback. It has to return two code references. The first is used
618as the request callback (it should save the return status), and the second 707as the request callback (it should save the return status), and the second
619is called to wait until the first callback has been called (it must set 708is called to wait until the first callback has been called (it must set
620C<$!> to the return status). 709C<$!> to the return status).
621 710
622This mechanism can be used to include BDB into other event mechanisms, 711This mechanism can be used to include BDB into other event mechanisms,
623such as L<AnyEvent::BDB> or L<Coro::BDB>. 712such as L<Coro::BDB>.
624 713
625The default implementation works like this: 714To allow other, callback-based, events to be executed while callback-less
715ones are run, you could use this sync prepare function:
626 716
627 sub { 717 sub {
628 my $status; 718 my $status;
629 ( 719 (
630 sub { $status = $! }, 720 sub { $status = $! },
631 sub { BDB::poll while !defined $status; $! = $status }, 721 sub { BDB::poll while !defined $status; $! = $status },
632 ) 722 )
633 } 723 }
634 724
635It simply blocks the process till the request has finished and then sets 725It works by polling for results till the request has finished and then
636C<$!> to the return value. This means that if you don't use a callback, 726sets C<$!> to the return value. This means that if you don't use a
637BDB will simply fall back to synchronous operations. 727callback, BDB would simply fall back to synchronous operations.
728
729By default, or if the sync prepare function is set to C<undef>, is to
730execute callback-less BDB requests in the foreground thread, setting C<$!>
731to the return value, without polling for other events.
638 732
639=back 733=back
640 734
641=head3 STATISTICAL INFORMATION 735=head2 STATISTICAL INFORMATION
642 736
643=over 4 737=over 4
644 738
645=item BDB::nreqs 739=item BDB::nreqs
646 740
… …
664 758
665=back 759=back
666 760
667=cut 761=cut
668 762
669set_sync_prepare { 763set_sync_prepare (undef);
670 my $status;
671 (
672 sub {
673 $status = $!;
674 },
675 sub {
676 BDB::poll while !defined $status;
677 $! = $status;
678 },
679 )
680};
681 764
682min_parallel 8; 765min_parallel 8;
683 766
684END { flush } 767END { flush }
685 768
6861; 7691;
687 770
771=head1 COMMON PITFALLS
772
773=head2 Unexpected Crashes
774
775Remember that, by default, BDB will execute requests in parallel, in
776somewhat random order. That means that it is easy to run a C<db_get>
777request on thesa me database as a concurrent C<db_close> request, leading
778to a crash, silent data corruption, eventually the next world war on
779terrorism.
780
781If you only ever use foreground requests (without a callback), this will
782not be an issue.
783
784=head2 Unexpected Freezes or Deadlocks
785
786Remember that, by default, BDB will execute requests in parallel, which
787easily leads to deadlocks (even concurrent put's on the same database can
788deadlock).
789
790You either need to run deadlock detection (and handle the resulting
791errors), or make sure only one process ever updates the database, ine one
792thread, e.g. by using only foreground requests (without a callback).
793
688=head2 FORK BEHAVIOUR 794=head1 FORK BEHAVIOUR
689 795
690This module should do "the right thing" when the process using it forks: 796This module should do "the right thing" when the process using it forks:
691 797
692Before the fork, BDB enters a quiescent state where no requests 798Before the fork, BDB enters a quiescent state where no requests
693can be added in other threads and no results will be processed. After 799can be added in other threads and no results will be processed. After
… …
703 809
704Win32 note: there is no fork on win32, and perls emulation of it is too 810Win32 note: there is no fork on win32, and perls emulation of it is too
705broken to be supported, so do not use BDB in a windows pseudo-fork, better 811broken to be supported, so do not use BDB in a windows pseudo-fork, better
706yet, switch to a more capable platform. 812yet, switch to a more capable platform.
707 813
708=head2 MEMORY USAGE 814=head1 MEMORY USAGE
709 815
710Per-request usage: 816Per-request usage:
711 817
712Each aio request uses - depending on your architecture - around 100-200 818Each aio request uses - depending on your architecture - around 100-200
713bytes of memory. In addition, stat requests need a stat buffer (possibly 819bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
722 828
723In the execution phase, some aio requests require more memory for 829In the execution phase, some aio requests require more memory for
724temporary buffers, and each thread requires a stack and other data 830temporary buffers, and each thread requires a stack and other data
725structures (usually around 16k-128k, depending on the OS). 831structures (usually around 16k-128k, depending on the OS).
726 832
833=head1 WIN32 FILENAMES/DATABASE NAME MESS
834
835Perl on Win32 supports only ASCII filenames (the reason is that it abuses
836an internal flag to store wether a filename is Unicode or ANSI, but that
837flag is used for somethign else in the perl core, so there is no way to
838detect wether a filename is ANSI or Unicode-encoded). The BDB module
839tries to work around this issue by assuming that the filename is an ANSI
840filename and BDB was built for unicode support.
841
727=head1 KNOWN BUGS 842=head1 KNOWN BUGS
728 843
729Known bugs will be fixed in the next release, except: 844Known bugs will be fixed in the next release, except:
730 845
731 If you use a transaction in any request, and the request returns 846 If you use a transaction in any request, and the request returns

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