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Comparing BDB/BDB.pm (file contents):
Revision 1.17 by root, Tue Dec 4 10:13:50 2007 UTC vs.
Revision 1.67 by root, Tue Feb 2 04:07:06 2016 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 = '1.91';
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 db_env_reset_lsn
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)
208 db_env_lsn_reset (DB_ENV *env, bdb_filename db, U32 flags = 0, SV *callback = 0)
142 209
143 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 210 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
144 flags: XA_CREATE 211 flags: XA_CREATE
145 212
146 db_open (DB *db, DB_TXN_ornull *txnid, octetstring file, octetstring database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef) 213 db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = 0)
147 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
148 db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 215 db_close (DB *db, U32 flags = 0, SV *callback = 0)
149 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)
218 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) 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)
151 flags: FREELIST_ONLY FREE_SPACE 220 flags: FREELIST_ONLY FREE_SPACE
152 db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 221 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) 222 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) 223 db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
155 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)
156 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)
157 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
158 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)
159 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
160 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)
161 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)
162 flags: TXN_NOSYNC TXN_SYNC 232 flags: TXN_NOSYNC TXN_SYNC
163 db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef) 233 db_txn_abort (DB_TXN *txn, SV *callback = 0)
164 234
165 db_c_close (DBC *dbc, SV *callback = &PL_sv_undef) 235 db_c_close (DBC *dbc, SV *callback = 0)
166 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)
167 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)
168 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA 238 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) 239 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 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
171 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)
172 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)
173 243
174 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)
175 flags: CREATE EXCL 245 flags: CREATE EXCL
176 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)
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) 247 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 248 flags: TXN_NOSYNC
179 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)
180 flags: TXN_NOSYNC 250 flags: TXN_NOSYNC
181 251
182=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)
183 253
184This is not actually a Berkeley DB function but a BDB module 254This is not actually a Berkeley DB function but a BDB module
185extension. The background for this exytension is: It is very annoying to 255extension. The background for this exytension is: It is very annoying to
186have 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
187codepath out of your transaction. While the BDB module still makes this 257codepath out of your transaction. While the BDB module still makes this
… …
213 283
214You can use the C<< $txn->failed >> method to check wether a transaction 284You can use the C<< $txn->failed >> method to check wether a transaction
215has failed in this way and abort further processing (excluding 285has failed in this way and abort further processing (excluding
216C<db_txn_finish>). 286C<db_txn_finish>).
217 287
288
218=head3 DB_ENV/database environment methods 289=head2 DB_ENV/database environment methods
219 290
220Methods available on DB_ENV/$env handles: 291Methods available on DB_ENV/$env handles:
221 292
222 DESTROY (DB_ENV_ornull *env) 293 DESTROY (DB_ENV_ornull *env)
223 CODE: 294 CODE:
… …
227 $int = $env->set_data_dir (const char *dir) 298 $int = $env->set_data_dir (const char *dir)
228 $int = $env->set_tmp_dir (const char *dir) 299 $int = $env->set_tmp_dir (const char *dir)
229 $int = $env->set_lg_dir (const char *dir) 300 $int = $env->set_lg_dir (const char *dir)
230 $int = $env->set_shm_key (long shm_key) 301 $int = $env->set_shm_key (long shm_key)
231 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 302 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
232 $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)
233 $env->set_errfile (FILE *errfile = 0) 306 $env->set_errfile (FILE *errfile = 0)
234 $env->set_msgfile (FILE *msgfile = 0) 307 $env->set_msgfile (FILE *msgfile = 0)
235 $int = $env->set_verbose (U32 which, int onoff = 1) 308 $int = $env->set_verbose (U32 which, int onoff = 1)
236 $int = $env->set_encrypt (const char *password, U32 flags = 0) 309 $int = $env->set_encrypt (const char *password, U32 flags = 0)
237 $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)
… …
242 $int = $env->set_lk_max_lockers (U32 max) 315 $int = $env->set_lk_max_lockers (U32 max)
243 $int = $env->set_lk_max_locks (U32 max) 316 $int = $env->set_lk_max_locks (U32 max)
244 $int = $env->set_lk_max_objects (U32 max) 317 $int = $env->set_lk_max_objects (U32 max)
245 $int = $env->set_lg_bsize (U32 max) 318 $int = $env->set_lg_bsize (U32 max)
246 $int = $env->set_lg_max (U32 max) 319 $int = $env->set_lg_max (U32 max)
320 $int = $env->mutex_set_increment (U32 increment)
321 $int = $env->mutex_set_tas_spins (U32 tas_spins)
322 $int = $env->mutex_set_max (U32 max)
323 $int = $env->mutex_set_align (U32 align)
247 324
248 $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)
249 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)
250 328
251=head4 Example: 329=head3 Example:
252 330
253 use AnyEvent; 331 use AnyEvent;
254 use BDB; 332 use BDB;
255 333
256 our $FH; open $FH, "<&=" . BDB::poll_fileno; 334 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
268 0600; 346 0600;
269 347
270 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); 348 $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
271 349
272 350
273=head3 DB/database methods 351=head2 DB/database methods
274 352
275Methods available on DB/$db handles: 353Methods available on DB/$db handles:
276 354
277 DESTROY (DB_ornull *db) 355 DESTROY (DB_ornull *db)
278 CODE: 356 CODE:
… …
304 382
305 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 383 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
306 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT 384 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
307 $seq = $db->sequence (U32 flags = 0) 385 $seq = $db->sequence (U32 flags = 0)
308 386
309=head4 Example: 387=head3 Example:
310 388
311 my $db = db_create $env; 389 my $db = db_create $env;
312 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;
313 391
314 for (1..1000) { 392 for (1..1000) {
… …
321 db_del $db, undef, "key $_" for 1..1000; 399 db_del $db, undef, "key $_" for 1..1000;
322 400
323 db_sync $db; 401 db_sync $db;
324 402
325 403
326=head3 DB_TXN/transaction methods 404=head2 DB_TXN/transaction methods
327 405
328Methods available on DB_TXN/$txn handles: 406Methods available on DB_TXN/$txn handles:
329 407
330 DESTROY (DB_TXN_ornull *txn) 408 DESTROY (DB_TXN_ornull *txn)
331 CODE: 409 CODE:
… …
337 415
338 $bool = $txn->failed 416 $bool = $txn->failed
339 # see db_txn_finish documentation, above 417 # see db_txn_finish documentation, above
340 418
341 419
342=head3 DBC/cursor methods 420=head2 DBC/cursor methods
343 421
344Methods available on DBC/$dbc handles: 422Methods available on DBC/$dbc handles:
345 423
346 DESTROY (DBC_ornull *dbc) 424 DESTROY (DBC_ornull *dbc)
347 CODE: 425 CODE:
348 if (dbc) 426 if (dbc)
349 dbc->c_close (dbc); 427 dbc->c_close (dbc);
350 428
429 $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
430
351=head4 Example: 431=head3 Example:
352 432
353 my $c = $db->cursor; 433 my $c = $db->cursor;
354 434
355 for (;;) { 435 for (;;) {
356 db_c_get $c, my $key, my $data, BDB::NEXT; 436 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
359 } 439 }
360 440
361 db_c_close $c; 441 db_c_close $c;
362 442
363 443
364=head3 DB_SEQUENCE/sequence methods 444=head2 DB_SEQUENCE/sequence methods
365 445
366Methods available on DB_SEQUENCE/$seq handles: 446Methods available on DB_SEQUENCE/$seq handles:
367 447
368 DESTROY (DB_SEQUENCE_ornull *seq) 448 DESTROY (DB_SEQUENCE_ornull *seq)
369 CODE: 449 CODE:
… …
374 $int = $seq->set_cachesize (U32 size) 454 $int = $seq->set_cachesize (U32 size)
375 $int = $seq->set_flags (U32 flags) 455 $int = $seq->set_flags (U32 flags)
376 flags: SEQ_DEC SEQ_INC SEQ_WRAP 456 flags: SEQ_DEC SEQ_INC SEQ_WRAP
377 $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)
378 458
379=head4 Example: 459=head3 Example:
380 460
381 my $seq = $db->sequence; 461 my $seq = $db->sequence;
382 462
383 db_sequence_open $seq, undef, "seq", BDB::CREATE; 463 db_sequence_open $seq, undef, "seq", BDB::CREATE;
384 db_sequence_get $seq, undef, 1, my $value; 464 db_sequence_get $seq, undef, 1, my $value;
385 465
386 466
387=head2 SUPPORT FUNCTIONS 467=head1 SUPPORT FUNCTIONS
388 468
389=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 469=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
390 470
391=over 4 471=over 4
472
473=item $msg = BDB::strerror [$errno]
474
475Returns the string corresponding to the given errno value. If no argument
476is given, use C<$!>.
477
478Note that the BDB module also patches the C<$!> variable directly, so you
479should be able to get a bdb error string by simply stringifying C<$!>.
392 480
393=item $fileno = BDB::poll_fileno 481=item $fileno = BDB::poll_fileno
394 482
395Return the I<request result pipe file descriptor>. This filehandle must be 483Return the I<request result pipe file descriptor>. This filehandle must be
396polled for reading by some mechanism outside this module (e.g. Event or 484polled for reading by some mechanism outside this module (e.g. Event or
… …
435interactiveness when perl is not fast enough to process all requests in 523interactiveness when perl is not fast enough to process all requests in
436time. 524time.
437 525
438For interactive programs, values such as C<0.01> to C<0.1> should be fine. 526For interactive programs, values such as C<0.01> to C<0.1> should be fine.
439 527
440Example: Install an Event watcher that automatically calls 528Example: Install an EV watcher that automatically calls
441BDB::poll_cb with low priority, to ensure that other parts of the 529BDB::poll_cb with low priority, to ensure that other parts of the
442program get the CPU sometimes even under high AIO load. 530program get the CPU sometimes even under high load.
443 531
444 # try not to spend much more than 0.1s in poll_cb 532 # try not to spend much more than 0.1s in poll_cb
445 BDB::max_poll_time 0.1; 533 BDB::max_poll_time 0.1;
446 534
447 # use a low priority so other tasks have priority 535 my $bdb_poll = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb);
448 Event->io (fd => BDB::poll_fileno,
449 poll => 'r', nice => 1,
450 cb => &BDB::poll_cb);
451 536
452=item BDB::poll_wait 537=item BDB::poll_wait
453 538
454If there are any outstanding requests and none of them in the result 539If there are any outstanding requests and none of them in the result
455phase, wait till the result filehandle becomes ready for reading (simply 540phase, wait till the result filehandle becomes ready for reading (simply
… …
467 552
468 BDB::poll_wait, BDB::poll_cb 553 BDB::poll_wait, BDB::poll_cb
469 554
470=item BDB::flush 555=item BDB::flush
471 556
472Wait till all outstanding AIO requests have been handled. 557Wait till all outstanding BDB requests have been handled.
473 558
474Strictly equivalent to: 559Strictly equivalent to:
475 560
476 BDB::poll_wait, BDB::poll_cb 561 BDB::poll_wait, BDB::poll_cb
477 while BDB::nreqs; 562 while BDB::nreqs;
478 563
479=back 564=back
480 565
481=head3 CONTROLLING THE NUMBER OF THREADS 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 $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;
482 578
483=over 4 579=over 4
484 580
581=item BDB::VERSION
582
583The C<BDB::VERSION> function, when called without arguments, returns the
584Berkeley DB version as a v-string (usually with 3 components). You should
585use C<lt> and C<ge> operators exclusively to make comparisons.
586
587Example: check for at least version 4.7.
588
589 BDB::VERSION ge v4.7 or die;
590
591=item BDB::VERSION min-version
592
593Returns true if the BDB version is at least the given version (specified
594as a v-string), false otherwise.
595
596Example: check for at least version 4.5.
597
598 BDB::VERSION v4.7 or die;
599
600=item BDB::VERSION min-version, max-version
601
602Returns true of the BDB version is at least version C<min-version> (specify C<undef> or C<v0> for any minimum version)
603and less then C<max-version>.
604
605Example: check wether version is strictly less then v4.7.
606
607 BDB::VERSION v0, v4.7
608 or die "version 4.7 is not yet supported";
609
610=back
611
612=cut
613
614sub VERSION {
615 # I was dumb enough to override the VERSION method here, so let's try
616 # to fix it up.
617
618 if ($_[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
632=head2 CONTROLLING THE NUMBER OF THREADS
633
634=over 4
635
485=item BDB::min_parallel $nthreads 636=item BDB::min_parallel $nthreads
486 637
487Set the minimum number of AIO threads to C<$nthreads>. The current 638Set the minimum number of BDB threads to C<$nthreads>. The current
488default is C<8>, which means eight asynchronous operations can execute 639default is C<8>, which means eight asynchronous operations can execute
489concurrently at any one time (the number of outstanding requests, 640concurrently at any one time (the number of outstanding requests,
490however, is unlimited). 641however, is unlimited).
491 642
492BDB starts threads only on demand, when an AIO request is queued and 643BDB starts threads only on demand, when an BDB request is queued and
493no free thread exists. Please note that queueing up a hundred requests can 644no free thread exists. Please note that queueing up a hundred requests can
494create demand for a hundred threads, even if it turns out that everything 645create demand for a hundred threads, even if it turns out that everything
495is in the cache and could have been processed faster by a single thread. 646is in the cache and could have been processed faster by a single thread.
496 647
497It is recommended to keep the number of threads relatively low, as some 648It is recommended to keep the number of threads relatively low, as some
… …
502Under most circumstances you don't need to call this function, as the 653Under most circumstances you don't need to call this function, as the
503module selects a default that is suitable for low to moderate load. 654module selects a default that is suitable for low to moderate load.
504 655
505=item BDB::max_parallel $nthreads 656=item BDB::max_parallel $nthreads
506 657
507Sets the maximum number of AIO threads to C<$nthreads>. If more than the 658Sets the maximum number of BDB threads to C<$nthreads>. If more than the
508specified number of threads are currently running, this function kills 659specified number of threads are currently running, this function kills
509them. This function blocks until the limit is reached. 660them. This function blocks until the limit is reached.
510 661
511While C<$nthreads> are zero, aio requests get queued but not executed 662While C<$nthreads> are zero, aio requests get queued but not executed
512until the number of threads has been increased again. 663until the number of threads has been increased again.
… …
547 698
548You can still queue as many requests as you want. Therefore, 699You can still queue as many requests as you want. Therefore,
549C<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
550as 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).
551 702
552=item BDB::set_sync_prepare $cb 703=item $old_cb = BDB::set_sync_prepare $cb
553 704
554Sets a callback that is called whenever a request is created without an 705Sets a callback that is called whenever a request is created without an
555explicit callback. It has to return two code references. The first is used 706explicit callback. It has to return two code references. The first is used
556as the request callback, and the second is called to wait until the first 707as the request callback (it should save the return status), and the second
557callback has been called. The default implementation works like this: 708is called to wait until the first callback has been called (it must set
709C<$!> to the return status).
710
711This mechanism can be used to include BDB into other event mechanisms,
712such as L<Coro::BDB>.
713
714To allow other, callback-based, events to be executed while callback-less
715ones are run, you could use this sync prepare function:
558 716
559 sub { 717 sub {
560 my $status; 718 my $status;
561 ( 719 (
562 sub { $status = $! }, 720 sub { $status = $! },
563 sub { BDB::poll while !defined $status; $! = $status }, 721 sub { BDB::poll while !defined $status; $! = $status },
564 ) 722 )
565 } 723 }
566 724
725It works by polling for results till the request has finished and then
726sets C<$!> to the return value. This means that if you don't use a
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.
732
567=back 733=back
568 734
569=head3 STATISTICAL INFORMATION 735=head2 STATISTICAL INFORMATION
570 736
571=over 4 737=over 4
572 738
573=item BDB::nreqs 739=item BDB::nreqs
574 740
… …
592 758
593=back 759=back
594 760
595=cut 761=cut
596 762
597set_sync_prepare { 763set_sync_prepare (undef);
598 my $status;
599 (
600 sub {
601 $status = $!;
602 },
603 sub {
604 BDB::poll while !defined $status;
605 $! = $status;
606 },
607 )
608};
609 764
610min_parallel 8; 765min_parallel 8;
611 766
612END { flush } 767END { flush }
613 768
6141; 7691;
615 770
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 the same 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 (unless you use threads).
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
616=head2 FORK BEHAVIOUR 794=head1 FORK BEHAVIOUR
617 795
618This 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:
619 797
620Before the fork, IO::AIO enters a quiescent state where no requests 798Before the fork, BDB enters a quiescent state where no requests
621can 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
622the fork the parent simply leaves the quiescent state and continues 800the fork the parent simply leaves the quiescent state and continues
623request/result processing, while the child frees the request/result queue 801request/result processing, while the child frees the request/result queue
624(so that the requests started before the fork will only be handled in the 802(so that the requests started before the fork will only be handled in the
625parent). Threads will be started on demand until the limit set in the 803parent). Threads will be started on demand until the limit set in the
626parent process has been reached again. 804parent process has been reached again.
627 805
628In short: the parent will, after a short pause, continue as if fork had 806In short: the parent will, after a short pause, continue as if fork had
629not been called, while the child will act as if IO::AIO has not been used 807not been called, while the child will act as if BDB has not been used
630yet. 808yet.
631 809
810Win32 note: there is no fork on win32, and perls emulation of it is too
811broken to be supported, so do not use BDB in a windows pseudo-fork, better
812yet, switch to a more capable platform.
813
632=head2 MEMORY USAGE 814=head1 MEMORY USAGE
633 815
634Per-request usage: 816Per-request usage:
635 817
636Each aio request uses - depending on your architecture - around 100-200 818Each aio request uses - depending on your architecture - around 100-200
637bytes of memory. In addition, stat requests need a stat buffer (possibly 819bytes of memory. In addition, stat requests need a stat buffer (possibly
… …
646 828
647In the execution phase, some aio requests require more memory for 829In the execution phase, some aio requests require more memory for
648temporary buffers, and each thread requires a stack and other data 830temporary buffers, and each thread requires a stack and other data
649structures (usually around 16k-128k, depending on the OS). 831structures (usually around 16k-128k, depending on the OS).
650 832
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
651=head1 KNOWN BUGS 842=head1 KNOWN BUGS
652 843
653Known bugs will be fixed in the next release, except: 844Known bugs will be fixed in the next release, except:
654 845
655 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
… …
657 TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>, 848 TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>,
658 above. 849 above.
659 850
660=head1 SEE ALSO 851=head1 SEE ALSO
661 852
662L<Coro::AIO>. 853L<AnyEvent::BDB> (event loop integration), L<Coro::BDB> (more natural
854syntax), L<IO::AIO> (nice to have).
663 855
664=head1 AUTHOR 856=head1 AUTHOR
665 857
666 Marc Lehmann <schmorp@schmorp.de> 858 Marc Lehmann <schmorp@schmorp.de>
667 http://home.schmorp.de/ 859 http://home.schmorp.de/

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