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Comparing BDB/BDB.pm (file contents):
Revision 1.18 by root, Tue Dec 4 11:07:39 2007 UTC vs.
Revision 1.62 by root, Wed Mar 31 00:44:51 2010 UTC

… …
3BDB - Asynchronous Berkeley DB access 3BDB - Asynchronous Berkeley DB access
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use BDB; 7 use BDB;
8
9 my $env = db_env_create;
10
11 mkdir "bdtest", 0700;
12 db_env_open
13 $env,
14 "bdtest",
15 BDB::INIT_LOCK | BDB::INIT_LOG | BDB::INIT_MPOOL
16 | BDB::INIT_TXN | BDB::RECOVER | BDB::USE_ENVIRON | BDB::CREATE,
17 0600;
18
19 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
20
21 my $db = db_create $env;
22 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE
23 | BDB::READ_UNCOMMITTED, 0600;
24 db_put $db, undef, "key", "data", 0, sub {
25 db_del $db, undef, "key";
26 };
27 db_sync $db;
28
29 # when you also use Coro, management is easy:
30 use Coro::BDB;
31
32 # automatic event loop integration with AnyEvent:
33 use AnyEvent::BDB;
34
35 # automatic result processing with EV:
36 my $WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb;
37
38 # with Glib:
39 add_watch Glib::IO BDB::poll_fileno,
40 in => sub { BDB::poll_cb; 1 };
41
42 # or simply flush manually
43 BDB::flush;
44
8 45
9=head1 DESCRIPTION 46=head1 DESCRIPTION
10 47
11See the BerkeleyDB documentation (L<http://www.oracle.com/technology/documentation/berkeley-db/db/index.html>). 48See the BerkeleyDB documentation (L<http://www.oracle.com/technology/documentation/berkeley-db/db/index.html>).
12The BDB API is very similar to the C API (the translation has been very faithful). 49The BDB API is very similar to the C API (the translation has been very faithful).
… …
66 103
67=cut 104=cut
68 105
69package BDB; 106package BDB;
70 107
71no warnings; 108use common::sense;
72use strict 'vars';
73 109
74use base 'Exporter'; 110use base 'Exporter';
75 111
112our $VERSION;
113
76BEGIN { 114BEGIN {
77 our $VERSION = '1.2'; 115 $VERSION = '1.88';
78 116
79 our @BDB_REQ = qw( 117 our @BDB_REQ = qw(
80 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
81 db_env_memp_sync db_env_memp_trickle 119 db_env_memp_sync db_env_memp_trickle db_env_dbrename db_env_dbremove
82 db_open db_close db_compact db_sync db_put db_get db_pget db_del db_key_range 120 db_env_log_archive
121 db_open db_close db_compact db_sync db_verify db_upgrade
122 db_put db_exists db_get db_pget db_del db_key_range
83 db_txn_commit db_txn_abort db_txn_finish 123 db_txn_commit db_txn_abort db_txn_finish
84 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
85 db_sequence_open db_sequence_close 125 db_sequence_open db_sequence_close
86 db_sequence_get db_sequence_remove 126 db_sequence_get db_sequence_remove
87 ); 127 );
… …
95 135
96 require XSLoader; 136 require XSLoader;
97 XSLoader::load ("BDB", $VERSION); 137 XSLoader::load ("BDB", $VERSION);
98} 138}
99 139
100=head2 BERKELEYDB FUNCTIONS 140=head1 BERKELEYDB FUNCTIONS
101 141
102All of these are functions. The create functions simply return a new 142All of these are functions. The create functions simply return a new
103object and never block. All the remaining functions all take an optional 143object and never block. All the remaining functions take an optional
104callback as last argument. If it is missing, then the fucntion will be 144callback as last argument. If it is missing, then the function will be
105executed synchronously. 145executed synchronously. In both cases, C<$!> will reflect the return value
146of the function.
106 147
107BDB functions that cannot block (mostly functions that manipulate 148BDB functions that cannot block (mostly functions that manipulate
108settings) 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
109is: if its a method, its not blocking, if its a function, it takes a 150is: if it's a method, it's not blocking, if it's a function, it takes a
110callback as last argument. 151callback as last argument.
111 152
112In the following, C<$int> signifies an integer return value, 153In the following, C<$int> signifies an integer return value,
113C<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),
114indices >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
115integer, C<NV> is a floating point value. 156floating point value.
116 157
117The 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
118values), and the C<SV *callback> is the optional callback function to call 159values).
119when the request is completed.
120 160
121The various C<DB_ENV> etc. arguments are handles return by 161The various C<DB_ENV> etc. arguments are handles return by
122C<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
123appended 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>
124for them, resulting a NULL pointer on the C level. 164for them, resulting a NULL pointer on the C level.
125 165
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
126=head3 BDB functions 189=head2 BDB functions
127 190
128Functions in the BDB namespace, exported by default: 191Functions in the BDB namespace, exported by default:
129 192
130 $env = db_env_create (U32 env_flags = 0) 193 $env = db_env_create (U32 env_flags = 0)
131 flags: RPCCLIENT 194 flags: RPCCLIENT
132 195
133 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)
134 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
135 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)
136 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)
137 flags: FORCE 200 flags: FORCE
138 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)
139 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
140 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)
141 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)
142 208
143 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 209 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
144 flags: XA_CREATE 210 flags: XA_CREATE
145 211
146 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)
147 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
148 db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 214 db_close (DB *db, U32 flags = 0, SV *callback = 0)
149 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)
217 db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = 0)
150 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)
151 flags: FREELIST_ONLY FREE_SPACE 219 flags: FREELIST_ONLY FREE_SPACE
152 db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 220 db_sync (DB *db, U32 flags = 0, SV *callback = 0)
153 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)
154 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)
155 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)
156 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)
157 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
158 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)
159 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
160 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)
161 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)
162 flags: TXN_NOSYNC TXN_SYNC 231 flags: TXN_NOSYNC TXN_SYNC
163 db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef) 232 db_txn_abort (DB_TXN *txn, SV *callback = 0)
164 233
165 db_c_close (DBC *dbc, SV *callback = &PL_sv_undef) 234 db_c_close (DBC *dbc, SV *callback = 0)
166 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)
167 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)
168 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA 237 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA
169 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)
170 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
171 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)
172 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)
173 242
174 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)
175 flags: CREATE EXCL 244 flags: CREATE EXCL
176 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)
177 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)
178 flags: TXN_NOSYNC 247 flags: TXN_NOSYNC
179 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)
180 flags: TXN_NOSYNC 249 flags: TXN_NOSYNC
181 250
182=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)
183 252
184This is not actually a Berkeley DB function but a BDB module 253This is not actually a Berkeley DB function but a BDB module
185extension. The background for this exytension is: It is very annoying to 254extension. The background for this exytension is: It is very annoying to
186have 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
187codepath out of your transaction. While the BDB module still makes this 256codepath out of your transaction. While the BDB module still makes this
… …
213 282
214You can use the C<< $txn->failed >> method to check wether a transaction 283You can use the C<< $txn->failed >> method to check wether a transaction
215has failed in this way and abort further processing (excluding 284has failed in this way and abort further processing (excluding
216C<db_txn_finish>). 285C<db_txn_finish>).
217 286
287
218=head3 DB_ENV/database environment methods 288=head2 DB_ENV/database environment methods
219 289
220Methods available on DB_ENV/$env handles: 290Methods available on DB_ENV/$env handles:
221 291
222 DESTROY (DB_ENV_ornull *env) 292 DESTROY (DB_ENV_ornull *env)
223 CODE: 293 CODE:
… …
227 $int = $env->set_data_dir (const char *dir) 297 $int = $env->set_data_dir (const char *dir)
228 $int = $env->set_tmp_dir (const char *dir) 298 $int = $env->set_tmp_dir (const char *dir)
229 $int = $env->set_lg_dir (const char *dir) 299 $int = $env->set_lg_dir (const char *dir)
230 $int = $env->set_shm_key (long shm_key) 300 $int = $env->set_shm_key (long shm_key)
231 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 301 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
232 $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)
233 $env->set_errfile (FILE *errfile = 0) 305 $env->set_errfile (FILE *errfile = 0)
234 $env->set_msgfile (FILE *msgfile = 0) 306 $env->set_msgfile (FILE *msgfile = 0)
235 $int = $env->set_verbose (U32 which, int onoff = 1) 307 $int = $env->set_verbose (U32 which, int onoff = 1)
236 $int = $env->set_encrypt (const char *password, U32 flags = 0) 308 $int = $env->set_encrypt (const char *password, U32 flags = 0)
237 $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)
… …
242 $int = $env->set_lk_max_lockers (U32 max) 314 $int = $env->set_lk_max_lockers (U32 max)
243 $int = $env->set_lk_max_locks (U32 max) 315 $int = $env->set_lk_max_locks (U32 max)
244 $int = $env->set_lk_max_objects (U32 max) 316 $int = $env->set_lk_max_objects (U32 max)
245 $int = $env->set_lg_bsize (U32 max) 317 $int = $env->set_lg_bsize (U32 max)
246 $int = $env->set_lg_max (U32 max) 318 $int = $env->set_lg_max (U32 max)
319 $int = $env->mutex_set_increment (U32 increment)
320 $int = $env->mutex_set_tas_spins (U32 tas_spins)
321 $int = $env->mutex_set_max (U32 max)
322 $int = $env->mutex_set_align (U32 align)
247 323
248 $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)
249 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)
250 327
251=head4 Example: 328=head3 Example:
252 329
253 use AnyEvent; 330 use AnyEvent;
254 use BDB; 331 use BDB;
255 332
256 our $FH; open $FH, "<&=" . BDB::poll_fileno; 333 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
268 0600; 345 0600;
269 346
270 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); 347 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
271 348
272 349
273=head3 DB/database methods 350=head2 DB/database methods
274 351
275Methods available on DB/$db handles: 352Methods available on DB/$db handles:
276 353
277 DESTROY (DB_ornull *db) 354 DESTROY (DB_ornull *db)
278 CODE: 355 CODE:
… …
304 381
305 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 382 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
306 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT 383 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
307 $seq = $db->sequence (U32 flags = 0) 384 $seq = $db->sequence (U32 flags = 0)
308 385
309=head4 Example: 386=head3 Example:
310 387
311 my $db = db_create $env; 388 my $db = db_create $env;
312 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;
313 390
314 for (1..1000) { 391 for (1..1000) {
… …
321 db_del $db, undef, "key $_" for 1..1000; 398 db_del $db, undef, "key $_" for 1..1000;
322 399
323 db_sync $db; 400 db_sync $db;
324 401
325 402
326=head3 DB_TXN/transaction methods 403=head2 DB_TXN/transaction methods
327 404
328Methods available on DB_TXN/$txn handles: 405Methods available on DB_TXN/$txn handles:
329 406
330 DESTROY (DB_TXN_ornull *txn) 407 DESTROY (DB_TXN_ornull *txn)
331 CODE: 408 CODE:
… …
337 414
338 $bool = $txn->failed 415 $bool = $txn->failed
339 # see db_txn_finish documentation, above 416 # see db_txn_finish documentation, above
340 417
341 418
342=head3 DBC/cursor methods 419=head2 DBC/cursor methods
343 420
344Methods available on DBC/$dbc handles: 421Methods available on DBC/$dbc handles:
345 422
346 DESTROY (DBC_ornull *dbc) 423 DESTROY (DBC_ornull *dbc)
347 CODE: 424 CODE:
348 if (dbc) 425 if (dbc)
349 dbc->c_close (dbc); 426 dbc->c_close (dbc);
350 427
428 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
429
351=head4 Example: 430=head3 Example:
352 431
353 my $c = $db->cursor; 432 my $c = $db->cursor;
354 433
355 for (;;) { 434 for (;;) {
356 db_c_get $c, my $key, my $data, BDB::NEXT; 435 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
359 } 438 }
360 439
361 db_c_close $c; 440 db_c_close $c;
362 441
363 442
364=head3 DB_SEQUENCE/sequence methods 443=head2 DB_SEQUENCE/sequence methods
365 444
366Methods available on DB_SEQUENCE/$seq handles: 445Methods available on DB_SEQUENCE/$seq handles:
367 446
368 DESTROY (DB_SEQUENCE_ornull *seq) 447 DESTROY (DB_SEQUENCE_ornull *seq)
369 CODE: 448 CODE:
… …
374 $int = $seq->set_cachesize (U32 size) 453 $int = $seq->set_cachesize (U32 size)
375 $int = $seq->set_flags (U32 flags) 454 $int = $seq->set_flags (U32 flags)
376 flags: SEQ_DEC SEQ_INC SEQ_WRAP 455 flags: SEQ_DEC SEQ_INC SEQ_WRAP
377 $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)
378 457
379=head4 Example: 458=head3 Example:
380 459
381 my $seq = $db->sequence; 460 my $seq = $db->sequence;
382 461
383 db_sequence_open $seq, undef, "seq", BDB::CREATE; 462 db_sequence_open $seq, undef, "seq", BDB::CREATE;
384 db_sequence_get $seq, undef, 1, my $value; 463 db_sequence_get $seq, undef, 1, my $value;
385 464
386 465
387=head2 SUPPORT FUNCTIONS 466=head1 SUPPORT FUNCTIONS
388 467
389=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 468=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
390 469
391=over 4 470=over 4
471
472=item $msg = BDB::strerror [$errno]
473
474Returns the string corresponding to the given errno value. If no argument
475is given, use C<$!>.
476
477Note that the BDB module also patches the C<$!> variable directly, so you
478should be able to get a bdb error string by simply stringifying C<$!>.
392 479
393=item $fileno = BDB::poll_fileno 480=item $fileno = BDB::poll_fileno
394 481
395Return the I<request result pipe file descriptor>. This filehandle must be 482Return the I<request result pipe file descriptor>. This filehandle must be
396polled for reading by some mechanism outside this module (e.g. Event or 483polled for reading by some mechanism outside this module (e.g. Event or
… …
473 BDB::poll_wait, BDB::poll_cb 560 BDB::poll_wait, BDB::poll_cb
474 while BDB::nreqs; 561 while BDB::nreqs;
475 562
476=back 563=back
477 564
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
478=head3 CONTROLLING THE NUMBER OF THREADS 631=head2 CONTROLLING THE NUMBER OF THREADS
479 632
480=over 4 633=over 4
481 634
482=item BDB::min_parallel $nthreads 635=item BDB::min_parallel $nthreads
483 636
… …
544 697
545You can still queue as many requests as you want. Therefore, 698You can still queue as many requests as you want. Therefore,
546C<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
547as 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).
548 701
549=item BDB::set_sync_prepare $cb 702=item $old_cb = BDB::set_sync_prepare $cb
550 703
551Sets a callback that is called whenever a request is created without an 704Sets a callback that is called whenever a request is created without an
552explicit callback. It has to return two code references. The first is used 705explicit callback. It has to return two code references. The first is used
553as the request callback, and the second is called to wait until the first 706as the request callback (it should save the return status), and the second
554callback has been called. The default implementation works like this: 707is called to wait until the first callback has been called (it must set
708C<$!> 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:
555 715
556 sub { 716 sub {
557 my $status; 717 my $status;
558 ( 718 (
559 sub { $status = $! }, 719 sub { $status = $! },
560 sub { BDB::poll while !defined $status; $! = $status }, 720 sub { BDB::poll while !defined $status; $! = $status },
561 ) 721 )
562 } 722 }
563 723
724It works by polling for results till the request has finished and then
725sets C<$!> 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
564=back 732=back
565 733
566=head3 STATISTICAL INFORMATION 734=head2 STATISTICAL INFORMATION
567 735
568=over 4 736=over 4
569 737
570=item BDB::nreqs 738=item BDB::nreqs
571 739
… …
589 757
590=back 758=back
591 759
592=cut 760=cut
593 761
594set_sync_prepare { 762set_sync_prepare (undef);
595 my $status;
596 (
597 sub {
598 $status = $!;
599 },
600 sub {
601 BDB::poll while !defined $status;
602 $! = $status;
603 },
604 )
605};
606 763
607min_parallel 8; 764min_parallel 8;
608 765
609END { flush } 766END { flush }
610 767
6111; 7681;
612 769
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
613=head2 FORK BEHAVIOUR 793=head1 FORK BEHAVIOUR
614 794
615This 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:
616 796
617Before the fork, BDB enters a quiescent state where no requests 797Before the fork, BDB enters a quiescent state where no requests
618can 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
… …
624 804
625In short: the parent will, after a short pause, continue as if fork had 805In short: the parent will, after a short pause, continue as if fork had
626not been called, while the child will act as if BDB has not been used 806not been called, while the child will act as if BDB has not been used
627yet. 807yet.
628 808
809Win32 note: there is no fork on win32, and perls emulation of it is too
810broken to be supported, so do not use BDB in a windows pseudo-fork, better
811yet, switch to a more capable platform.
812
629=head2 MEMORY USAGE 813=head1 MEMORY USAGE
630 814
631Per-request usage: 815Per-request usage:
632 816
633Each aio request uses - depending on your architecture - around 100-200 817Each aio request uses - depending on your architecture - around 100-200
634bytes of memory. In addition, stat requests need a stat buffer (possibly 818bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
643 827
644In the execution phase, some aio requests require more memory for 828In the execution phase, some aio requests require more memory for
645temporary buffers, and each thread requires a stack and other data 829temporary buffers, and each thread requires a stack and other data
646structures (usually around 16k-128k, depending on the OS). 830structures (usually around 16k-128k, depending on the OS).
647 831
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
648=head1 KNOWN BUGS 841=head1 KNOWN BUGS
649 842
650Known bugs will be fixed in the next release, except: 843Known bugs will be fixed in the next release, except:
651 844
652 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
… …
654 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>,
655 above. 848 above.
656 849
657=head1 SEE ALSO 850=head1 SEE ALSO
658 851
659L<Coro::BDB>, L<IO::AIO>. 852L<AnyEvent::BDB> (event loop integration), L<Coro::BDB> (more natural
853syntax), L<IO::AIO> (nice to have).
660 854
661=head1 AUTHOR 855=head1 AUTHOR
662 856
663 Marc Lehmann <schmorp@schmorp.de> 857 Marc Lehmann <schmorp@schmorp.de>
664 http://home.schmorp.de/ 858 http://home.schmorp.de/

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