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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 1.57 by root, Tue Jul 14 19:29:23 2009 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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104 103
105=cut 104=cut
106 105
107package BDB; 106package BDB;
108 107
109no warnings; 108use common::sense;
110use strict 'vars';
111 109
112use base 'Exporter'; 110use base 'Exporter';
113 111
112our $VERSION;
113
114BEGIN { 114BEGIN {
115 our $VERSION = '1.44'; 115 $VERSION = '1.84';
116 116
117 our @BDB_REQ = qw( 117 our @BDB_REQ = qw(
118 db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect 118 db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect
119 db_env_memp_sync db_env_memp_trickle 119 db_env_memp_sync db_env_memp_trickle db_env_dbrename db_env_dbremove
120 db_env_log_archive
120 db_open db_close db_compact db_sync db_upgrade 121 db_open db_close db_compact db_sync db_verify db_upgrade
121 db_put db_get db_pget db_del db_key_range 122 db_put db_exists db_get db_pget db_del db_key_range
122 db_txn_commit db_txn_abort db_txn_finish 123 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 124 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 125 db_sequence_open db_sequence_close
125 db_sequence_get db_sequence_remove 126 db_sequence_get db_sequence_remove
126 ); 127 );
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134 135
135 require XSLoader; 136 require XSLoader;
136 XSLoader::load ("BDB", $VERSION); 137 XSLoader::load ("BDB", $VERSION);
137} 138}
138 139
139=head2 FILENAMES/DATABASE NAMES
140
141The BDB expects "binary" filenames (octet strings) for pathnames on POSIX
142systems, and "unicode" filenames (strings with characters potentially
143>255) on Win32 (expecting a Unicode win32 build - win32 is a total mess).
144
145=head2 BERKELEYDB FUNCTIONS 140=head1 BERKELEYDB FUNCTIONS
146 141
147All of these are functions. The create functions simply return a new 142All of these are functions. The create functions simply return a new
148object and never block. All the remaining functions take an optional 143object and never block. All the remaining functions take an optional
149callback as last argument. If it is missing, then the function will be 144callback as last argument. If it is missing, then the function will be
150executed synchronously. In both cases, C<$!> will reflect the return value 145executed synchronously. In both cases, C<$!> will reflect the return value
… …
154settings) are method calls on the relevant objects, so the rule of thumb 149settings) are method calls on the relevant objects, so the rule of thumb
155is: if it's a method, it's not blocking, if it's a function, it takes a 150is: if it's a method, it's not blocking, if it's a function, it takes a
156callback as last argument. 151callback as last argument.
157 152
158In the following, C<$int> signifies an integer return value, 153In the following, C<$int> signifies an integer return value,
159C<octetstring> is a "binary string" (i.e. a perl string with no character 154C<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 155C<U32> is an unsigned 32 bit integer, C<int> is some integer, C<NV> is a
161integer, C<NV> is a floating point value. 156floating point value.
162 157
163The C<SV *> types are generic perl scalars (for input and output of data 158Most 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 159values).
165when the request is completed.
166 160
167The various C<DB_ENV> etc. arguments are handles return by 161The 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 162C<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> 163appended C<_ornull> this means they are optional and you can pass C<undef>
170for them, resulting a NULL pointer on the C level. 164for them, resulting a NULL pointer on the C level.
171 165
166The C<SV *callback> is the optional callback function to call when the
167request is completed. This last callback argument is special: the callback
168is simply the last argument passed. If there are "optional" arguments
169before the callback they can be left out. The callback itself can be left
170out or specified as C<undef>, in which case the function will be executed
171synchronously.
172
173For example, C<db_env_txn_checkpoint> usually is called with all integer
174arguments zero. These can be left out, so all of these specify a call
175to C<< DB_ENV->txn_checkpoint >>, to be executed asynchronously with a
176callback to be called:
177
178 db_env_txn_checkpoint $db_env, 0, 0, 0, sub { };
179 db_env_txn_checkpoint $db_env, 0, 0, sub { };
180 db_env_txn_checkpoint $db_env, sub { };
181
182While these all specify a call to C<< DB_ENV->txn_checkpoint >> to be
183executed synchronously:
184
185 db_env_txn_checkpoint $db_env, 0, 0, 0, undef;
186 db_env_txn_checkpoint $db_env, 0, 0, 0;
187 db_env_txn_checkpoint $db_env, 0;
188
172=head3 BDB functions 189=head2 BDB functions
173 190
174Functions in the BDB namespace, exported by default: 191Functions in the BDB namespace, exported by default:
175 192
176 $env = db_env_create (U32 env_flags = 0) 193 $env = db_env_create (U32 env_flags = 0)
177 flags: RPCCLIENT 194 flags: RPCCLIENT
178 195
179 db_env_open (DB_ENV *env, octetstring db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef) 196 db_env_open (DB_ENV *env, bdb_filename db_home, U32 open_flags, int mode, SV *callback = 0)
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 197 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) 198 db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = 0)
182 db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef) 199 db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = 0)
183 flags: FORCE 200 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) 201 db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = 0)
185 atype: LOCK_DEFAULT LOCK_EXPIRE LOCK_MAXLOCKS LOCK_MAXWRITE LOCK_MINLOCKS LOCK_MINWRITE LOCK_OLDEST LOCK_RANDOM LOCK_YOUNGEST 202 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) 203 db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = 0)
187 db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef) 204 db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = 0)
205 db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = 0)
206 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)
207 db_env_log_archive (DB_ENV *env, SV *listp, U32 flags = 0, SV *callback = 0)
188 208
189 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 209 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
190 flags: XA_CREATE 210 flags: XA_CREATE
191 211
192 db_open (DB *db, DB_TXN_ornull *txnid, octetstring file, octetstring database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef) 212 db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = 0)
193 flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE 213 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) 214 db_close (DB *db, U32 flags = 0, SV *callback = 0)
195 flags: DB_NOSYNC 215 flags: DB_NOSYNC
216 db_verify (DB *db, bdb_filename file, bdb_filename database = 0, SV *dummy = 0, U32 flags = 0, SV *callback = 0)
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 = 0)
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 = 0)
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 = 0)
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 = 0)
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 = 0)
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 = 0)
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 = 0)
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 = 0)
208 db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) 230 db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = 0)
209 flags: TXN_NOSYNC TXN_SYNC 231 flags: TXN_NOSYNC TXN_SYNC
210 db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef) 232 db_txn_abort (DB_TXN *txn, SV *callback = 0)
211 233
212 db_c_close (DBC *dbc, SV *callback = &PL_sv_undef) 234 db_c_close (DBC *dbc, SV *callback = 0)
213 db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = &PL_sv_undef) 235 db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = 0)
214 db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 236 db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
215 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA 237 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA
216 db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 238 db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
217 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 239 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
218 db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 240 db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0)
219 db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef) 241 db_c_del (DBC *dbc, U32 flags = 0, SV *callback = 0)
220 242
221 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) 243 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = 0)
222 flags: CREATE EXCL 244 flags: CREATE EXCL
223 db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef) 245 db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = 0)
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 = 0)
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 = 0)
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 = 0)
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
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260 282
261You can use the C<< $txn->failed >> method to check wether a transaction 283You can use the C<< $txn->failed >> method to check wether a transaction
262has failed in this way and abort further processing (excluding 284has failed in this way and abort further processing (excluding
263C<db_txn_finish>). 285C<db_txn_finish>).
264 286
287
265=head3 DB_ENV/database environment methods 288=head2 DB_ENV/database environment methods
266 289
267Methods available on DB_ENV/$env handles: 290Methods available on DB_ENV/$env handles:
268 291
269 DESTROY (DB_ENV_ornull *env) 292 DESTROY (DB_ENV_ornull *env)
270 CODE: 293 CODE:
… …
274 $int = $env->set_data_dir (const char *dir) 297 $int = $env->set_data_dir (const char *dir)
275 $int = $env->set_tmp_dir (const char *dir) 298 $int = $env->set_tmp_dir (const char *dir)
276 $int = $env->set_lg_dir (const char *dir) 299 $int = $env->set_lg_dir (const char *dir)
277 $int = $env->set_shm_key (long shm_key) 300 $int = $env->set_shm_key (long shm_key)
278 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 301 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
279 $int = $env->set_flags (U32 flags, int onoff) 302 $int = $env->set_flags (U32 flags, int onoff = 1)
303 $int = $env->log_set_config (U32 flags, int onoff = 1) (v4.7)
304 $int = $env->set_intermediate_dir_mode (const char *modestring) (v4.7)
280 $env->set_errfile (FILE *errfile = 0) 305 $env->set_errfile (FILE *errfile = 0)
281 $env->set_msgfile (FILE *msgfile = 0) 306 $env->set_msgfile (FILE *msgfile = 0)
282 $int = $env->set_verbose (U32 which, int onoff = 1) 307 $int = $env->set_verbose (U32 which, int onoff = 1)
283 $int = $env->set_encrypt (const char *password, U32 flags = 0) 308 $int = $env->set_encrypt (const char *password, U32 flags = 0)
284 $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT) 309 $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT)
… …
296 $int = $env->mutex_set_max (U32 max) 321 $int = $env->mutex_set_max (U32 max)
297 $int = $env->mutex_set_align (U32 align) 322 $int = $env->mutex_set_align (U32 align)
298 323
299 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) 324 $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 325 flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC
326 $txn = $env->cdsgroup_begin; (v4.5)
301 327
302=head4 Example: 328=head3 Example:
303 329
304 use AnyEvent; 330 use AnyEvent;
305 use BDB; 331 use BDB;
306 332
307 our $FH; open $FH, "<&=" . BDB::poll_fileno; 333 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
319 0600; 345 0600;
320 346
321 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); 347 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
322 348
323 349
324=head3 DB/database methods 350=head2 DB/database methods
325 351
326Methods available on DB/$db handles: 352Methods available on DB/$db handles:
327 353
328 DESTROY (DB_ornull *db) 354 DESTROY (DB_ornull *db)
329 CODE: 355 CODE:
… …
355 381
356 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 382 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
357 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT 383 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
358 $seq = $db->sequence (U32 flags = 0) 384 $seq = $db->sequence (U32 flags = 0)
359 385
360=head4 Example: 386=head3 Example:
361 387
362 my $db = db_create $env; 388 my $db = db_create $env;
363 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600; 389 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600;
364 390
365 for (1..1000) { 391 for (1..1000) {
… …
372 db_del $db, undef, "key $_" for 1..1000; 398 db_del $db, undef, "key $_" for 1..1000;
373 399
374 db_sync $db; 400 db_sync $db;
375 401
376 402
377=head3 DB_TXN/transaction methods 403=head2 DB_TXN/transaction methods
378 404
379Methods available on DB_TXN/$txn handles: 405Methods available on DB_TXN/$txn handles:
380 406
381 DESTROY (DB_TXN_ornull *txn) 407 DESTROY (DB_TXN_ornull *txn)
382 CODE: 408 CODE:
… …
388 414
389 $bool = $txn->failed 415 $bool = $txn->failed
390 # see db_txn_finish documentation, above 416 # see db_txn_finish documentation, above
391 417
392 418
393=head3 DBC/cursor methods 419=head2 DBC/cursor methods
394 420
395Methods available on DBC/$dbc handles: 421Methods available on DBC/$dbc handles:
396 422
397 DESTROY (DBC_ornull *dbc) 423 DESTROY (DBC_ornull *dbc)
398 CODE: 424 CODE:
399 if (dbc) 425 if (dbc)
400 dbc->c_close (dbc); 426 dbc->c_close (dbc);
401 427
402 $int = $cursor->set_priority ($priority = PRIORITY_*) 428 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
403 429
404=head4 Example: 430=head3 Example:
405 431
406 my $c = $db->cursor; 432 my $c = $db->cursor;
407 433
408 for (;;) { 434 for (;;) {
409 db_c_get $c, my $key, my $data, BDB::NEXT; 435 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
412 } 438 }
413 439
414 db_c_close $c; 440 db_c_close $c;
415 441
416 442
417=head3 DB_SEQUENCE/sequence methods 443=head2 DB_SEQUENCE/sequence methods
418 444
419Methods available on DB_SEQUENCE/$seq handles: 445Methods available on DB_SEQUENCE/$seq handles:
420 446
421 DESTROY (DB_SEQUENCE_ornull *seq) 447 DESTROY (DB_SEQUENCE_ornull *seq)
422 CODE: 448 CODE:
… …
427 $int = $seq->set_cachesize (U32 size) 453 $int = $seq->set_cachesize (U32 size)
428 $int = $seq->set_flags (U32 flags) 454 $int = $seq->set_flags (U32 flags)
429 flags: SEQ_DEC SEQ_INC SEQ_WRAP 455 flags: SEQ_DEC SEQ_INC SEQ_WRAP
430 $int = $seq->set_range (db_seq_t min, db_seq_t max) 456 $int = $seq->set_range (db_seq_t min, db_seq_t max)
431 457
432=head4 Example: 458=head3 Example:
433 459
434 my $seq = $db->sequence; 460 my $seq = $db->sequence;
435 461
436 db_sequence_open $seq, undef, "seq", BDB::CREATE; 462 db_sequence_open $seq, undef, "seq", BDB::CREATE;
437 db_sequence_get $seq, undef, 1, my $value; 463 db_sequence_get $seq, undef, 1, my $value;
438 464
439 465
440=head2 SUPPORT FUNCTIONS 466=head1 SUPPORT FUNCTIONS
441 467
442=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 468=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
443 469
444=over 4 470=over 4
445 471
446=item $msg = BDB::strerror [$errno] 472=item $msg = BDB::strerror [$errno]
447 473
… …
534 BDB::poll_wait, BDB::poll_cb 560 BDB::poll_wait, BDB::poll_cb
535 while BDB::nreqs; 561 while BDB::nreqs;
536 562
537=back 563=back
538 564
565=head2 VERSION CHECKING
566
567BerkeleyDB comes in various versions, many of them have minor
568incompatibilities. This means that traditional "at least version x.x"
569checks are often not sufficient.
570
571Example: set the log_autoremove option in a way compatible with <v4.7 and
572v4.7. Note the use of & on the constants to avoid triggering a compiletime
573bug when the symbol isn't available.
574
575 $DB_ENV->set_flags (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7;
576 $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;
577
578=over 4
579
580=item BDB::VERSION
581
582The C<BDB::VERSION> function, when called without arguments, returns the
583Berkeley DB version as a v-string (usually with 3 components). You should
584use C<lt> and C<ge> operators exclusively to make comparisons.
585
586Example: check for at least version 4.7.
587
588 BDB::VERSION ge v4.7 or die;
589
590=item BDB::VERSION min-version
591
592Returns true if the BDB version is at least the given version (specified
593as a v-string), false otherwise.
594
595Example: check for at least version 4.5.
596
597 BDB::VERSION v4.7 or die;
598
599=item BDB::VERSION min-version, max-version
600
601Returns true of the BDB version is at least version C<min-version> (specify C<undef> or C<v0> for any minimum version)
602and less then C<max-version>.
603
604Example: check wether version is strictly less then v4.7.
605
606 BDB::VERSION v0, v4.7
607 or die "version 4.7 is not yet supported";
608
609=back
610
611=cut
612
613sub VERSION {
614 # I was dumb enough to override the VERSION method here, so let's try
615 # to fix it up.
616
617 if ($_[0] eq __PACKAGE__) {
618 $VERSION
619 } else {
620 if (@_ > 0) {
621 return undef if VERSION_v lt $_[0];
622 if (@_ > 1) {
623 return undef if VERSION_v ge $_[1];
624 }
625 }
626
627 VERSION_v
628 }
629}
630
539=head3 CONTROLLING THE NUMBER OF THREADS 631=head2 CONTROLLING THE NUMBER OF THREADS
540 632
541=over 4 633=over 4
542 634
543=item BDB::min_parallel $nthreads 635=item BDB::min_parallel $nthreads
544 636
… …
605 697
606You can still queue as many requests as you want. Therefore, 698You can still queue as many requests as you want. Therefore,
607C<max_oustsanding> is mainly useful in simple scripts (with low values) or 699C<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). 700as a stop gap to shield against fatal memory overflow (with large values).
609 701
610=item BDB::set_sync_prepare $cb 702=item $old_cb = BDB::set_sync_prepare $cb
611 703
612Sets a callback that is called whenever a request is created without an 704Sets a callback that is called whenever a request is created without an
613explicit callback. It has to return two code references. The first is used 705explicit callback. It has to return two code references. The first is used
614as the request callback, and the second is called to wait until the first 706as the request callback (it should save the return status), and the second
615callback has been called. The default implementation works like this: 707is called to wait until the first callback has been called (it must set
708C<$!> to the return status).
709
710This mechanism can be used to include BDB into other event mechanisms,
711such as L<Coro::BDB>.
712
713To allow other, callback-based, events to be executed while callback-less
714ones are run, you could use this sync prepare function:
616 715
617 sub { 716 sub {
618 my $status; 717 my $status;
619 ( 718 (
620 sub { $status = $! }, 719 sub { $status = $! },
621 sub { BDB::poll while !defined $status; $! = $status }, 720 sub { BDB::poll while !defined $status; $! = $status },
622 ) 721 )
623 } 722 }
624 723
724It works by polling for results till the request has finished and then
725sets C<$!> to the return value. This means that if you don't use a
726callback, BDB would simply fall back to synchronous operations.
727
728By default, or if the sync prepare function is set to C<undef>, is to
729execute callback-less BDB requests in the foreground thread, setting C<$!>
730to the return value, without polling for other events.
731
625=back 732=back
626 733
627=head3 STATISTICAL INFORMATION 734=head2 STATISTICAL INFORMATION
628 735
629=over 4 736=over 4
630 737
631=item BDB::nreqs 738=item BDB::nreqs
632 739
… …
650 757
651=back 758=back
652 759
653=cut 760=cut
654 761
655set_sync_prepare { 762set_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};
667 763
668min_parallel 8; 764min_parallel 8;
669 765
670END { flush } 766END { flush }
671 767
6721; 7681;
673 769
770=head1 COMMON PITFALLS
771
772=head2 Unexpected Crashes
773
774Remember that, by default, BDB will execute requests in parallel, in
775somewhat random order. That means that it is easy to run a C<db_get>
776request on thesa me database as a concurrent C<db_close> request, leading
777to a crash, silent data corruption, eventually the next world war on
778terrorism.
779
780If you only ever use foreground requests (without a callback), this will
781not be an issue.
782
783=head2 Unexpected Freezes or Deadlocks
784
785Remember that, by default, BDB will execute requests in parallel, which
786easily leads to deadlocks (even concurrent put's on the same database can
787deadlock).
788
789You either need to run deadlock detection (and handle the resulting
790errors), or make sure only one process ever updates the database, ine one
791thread, e.g. by using only foreground requests (without a callback).
792
674=head2 FORK BEHAVIOUR 793=head1 FORK BEHAVIOUR
675 794
676This module should do "the right thing" when the process using it forks: 795This module should do "the right thing" when the process using it forks:
677 796
678Before the fork, BDB enters a quiescent state where no requests 797Before the fork, BDB enters a quiescent state where no requests
679can be added in other threads and no results will be processed. After 798can be added in other threads and no results will be processed. After
… …
689 808
690Win32 note: there is no fork on win32, and perls emulation of it is too 809Win32 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 810broken to be supported, so do not use BDB in a windows pseudo-fork, better
692yet, switch to a more capable platform. 811yet, switch to a more capable platform.
693 812
694=head2 MEMORY USAGE 813=head1 MEMORY USAGE
695 814
696Per-request usage: 815Per-request usage:
697 816
698Each aio request uses - depending on your architecture - around 100-200 817Each aio request uses - depending on your architecture - around 100-200
699bytes of memory. In addition, stat requests need a stat buffer (possibly 818bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
708 827
709In the execution phase, some aio requests require more memory for 828In the execution phase, some aio requests require more memory for
710temporary buffers, and each thread requires a stack and other data 829temporary buffers, and each thread requires a stack and other data
711structures (usually around 16k-128k, depending on the OS). 830structures (usually around 16k-128k, depending on the OS).
712 831
832=head1 WIN32 FILENAMES/DATABASE NAME MESS
833
834Perl on Win32 supports only ASCII filenames (the reason is that it abuses
835an internal flag to store wether a filename is Unicode or ANSI, but that
836flag is used for somethign else in the perl core, so there is no way to
837detect wether a filename is ANSI or Unicode-encoded). The BDB module
838tries to work around this issue by assuming that the filename is an ANSI
839filename and BDB was built for unicode support.
840
713=head1 KNOWN BUGS 841=head1 KNOWN BUGS
714 842
715Known bugs will be fixed in the next release, except: 843Known bugs will be fixed in the next release, except:
716 844
717 If you use a transaction in any request, and the request returns 845 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>, 847 TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>,
720 above. 848 above.
721 849
722=head1 SEE ALSO 850=head1 SEE ALSO
723 851
724L<Coro::BDB>, L<IO::AIO>. 852L<AnyEvent::BDB> (event loop integration), L<Coro::BDB> (more natural
853syntax), L<IO::AIO> (nice to have).
725 854
726=head1 AUTHOR 855=head1 AUTHOR
727 856
728 Marc Lehmann <schmorp@schmorp.de> 857 Marc Lehmann <schmorp@schmorp.de>
729 http://home.schmorp.de/ 858 http://home.schmorp.de/

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