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Comparing BDB/BDB.pm (file contents):
Revision 1.13 by root, Mon Aug 13 12:07:55 2007 UTC vs.
Revision 1.41 by root, Wed Jul 9 12:15:36 2008 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 intergration 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).
… …
72use strict 'vars'; 109use strict 'vars';
73 110
74use base 'Exporter'; 111use base 'Exporter';
75 112
76BEGIN { 113BEGIN {
77 our $VERSION = '1.0'; 114 our $VERSION = '1.6';
78 115
79 our @BDB_REQ = qw( 116 our @BDB_REQ = qw(
80 db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect 117 db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect
81 db_env_memp_sync db_env_memp_trickle 118 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 119 db_open db_close db_compact db_sync db_upgrade
120 db_put db_get db_pget db_del db_key_range
83 db_txn_commit db_txn_abort 121 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 122 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 123 db_sequence_open db_sequence_close
86 db_sequence_get db_sequence_remove 124 db_sequence_get db_sequence_remove
87 ); 125 );
88 our @EXPORT = (@BDB_REQ, qw(dbreq_pri dbreq_nice db_env_create db_create)); 126 our @EXPORT = (@BDB_REQ, qw(dbreq_pri dbreq_nice db_env_create db_create));
… …
95 133
96 require XSLoader; 134 require XSLoader;
97 XSLoader::load ("BDB", $VERSION); 135 XSLoader::load ("BDB", $VERSION);
98} 136}
99 137
138=head2 WIN32 FILENAMES/DATABASE NAME MESS
139
140Perl on Win32 supports only ASCII filenames (the reason is that it abuses
141an internal flag to store wether a filename is Unicode or ANSI, but that
142flag is used for somethign else in the perl core, so there is no way to
143detect wether a filename is ANSI or Unicode-encoded). The BDB module
144tries to work around this issue by assuming that the filename is an ANSI
145filename and BDB was built for unicode support.
146
100=head2 BERKELEYDB FUNCTIONS 147=head2 BERKELEYDB FUNCTIONS
101 148
102All of these are functions. The create functions simply return a new 149All of these are functions. The create functions simply return a new
103object and never block. All the remaining functions all take an optional 150object and never block. All the remaining functions take an optional
104callback as last argument. If it is missing, then the fucntion will be 151callback as last argument. If it is missing, then the function will be
105executed synchronously. 152executed synchronously. In both cases, C<$!> will reflect the return value
153of the function.
106 154
107BDB functions that cannot block (mostly functions that manipulate 155BDB functions that cannot block (mostly functions that manipulate
108settings) are method calls on the relevant objects, so the rule of thumb 156settings) 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 157is: if it's a method, it's not blocking, if it's a function, it takes a
110callback as last argument. 158callback as last argument.
111 159
112In the following, C<$int> signifies an integer return value, 160In the following, C<$int> signifies an integer return value,
113C<octetstring> is a "binary string" (i.e. a perl string with no character 161C<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 162C<U32> is an unsigned 32 bit integer, C<int> is some integer, C<NV> is a
115integer, C<NV> is a floating point value. 163floating point value.
116 164
117The C<SV *> types are generic perl scalars (for input and output of data 165Most 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 166values).
119when the request is completed.
120 167
121The various C<DB_ENV> etc. arguments are handles return by 168The 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 169C<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> 170appended C<_ornull> this means they are optional and you can pass C<undef>
124for them, resulting a NULL pointer on the C level. 171for them, resulting a NULL pointer on the C level.
125 172
173The C<SV *callback> is the optional callback function to call when the
174request is completed. This last callback argument is special: the callback
175is simply the last argument passed. If there are "optional" arguments
176before the callback they can be left out. The callback itself can be left
177out or specified as C<undef>, in which case the function will be executed
178synchronously.
179
180For example, C<db_env_txn_checkpoint> usually is called with all integer
181arguments zero. These can be left out, so all of these specify a call
182to C<< DB_ENV->txn_checkpoint >>, to be executed asynchronously with a
183callback to be called:
184
185 db_env_txn_checkpoint $db_env, 0, 0, 0, sub { };
186 db_env_txn_checkpoint $db_env, 0, 0, sub { };
187 db_env_txn_checkpoint $db_env, sub { };
188
189While these all specify a call to C<< DB_ENV->txn_checkpoint >> to be
190executed synchronously:
191
192 db_env_txn_checkpoint $db_env, 0, 0, 0, undef;
193 db_env_txn_checkpoint $db_env, 0, 0, 0;
194 db_env_txn_checkpoint $db_env, 0;
195
126=head3 BDB functions 196=head3 BDB functions
127 197
128Functions in the BDB namespace, exported by default: 198Functions in the BDB namespace, exported by default:
129 199
130 $env = db_env_create (U32 env_flags = 0) 200 $env = db_env_create (U32 env_flags = 0)
201 flags: RPCCLIENT
131 202
132 db_env_open (DB_ENV *env, octetstring db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef) 203 db_env_open (DB_ENV *env, bdb_filename db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef)
204 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
133 db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef) 205 db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef)
134 db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef) 206 db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
207 flags: FORCE
135 db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef) 208 db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef)
209 atype: LOCK_DEFAULT LOCK_EXPIRE LOCK_MAXLOCKS LOCK_MAXWRITE LOCK_MINLOCKS LOCK_MINWRITE LOCK_OLDEST LOCK_RANDOM LOCK_YOUNGEST
136 db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = &PL_sv_undef) 210 db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = &PL_sv_undef)
137 db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef) 211 db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef)
212 db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = &PL_sv_undef)
213 db_env_dbrename (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, bdb_filename newname, U32 flags = 0, SV *callback = &PL_sv_undef)
138 214
139 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 215 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
216 flags: XA_CREATE
140 217
141 db_open (DB *db, DB_TXN_ornull *txnid, octetstring file, octetstring database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef) 218 db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef)
219 flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE
142 db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 220 db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef)
221 flags: DB_NOSYNC
222 db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = &PL_sv_undef)
143 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) 223 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)
224 flags: FREELIST_ONLY FREE_SPACE
144 db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 225 db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef)
145 db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef) 226 db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef)
146 db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 227 db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
228 flags: APPEND NODUPDATA NOOVERWRITE
147 db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 229 db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
230 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
148 db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 231 db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
232 flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
149 db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) 233 db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef)
150 db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) 234 db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef)
235 flags: TXN_NOSYNC TXN_SYNC
151 db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef) 236 db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef)
237
152 db_c_close (DBC *dbc, SV *callback = &PL_sv_undef) 238 db_c_close (DBC *dbc, SV *callback = &PL_sv_undef)
153 db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = &PL_sv_undef) 239 db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = &PL_sv_undef)
154 db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 240 db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
241 flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA
155 db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 242 db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
243 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
156 db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 244 db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
157 db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef) 245 db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef)
158 246
159 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) 247 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef)
248 flags: CREATE EXCL
160 db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef) 249 db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef)
161 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) 250 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)
251 flags: TXN_NOSYNC
162 db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) 252 db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
253 flags: TXN_NOSYNC
163 254
255=head4 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef)
256
257This is not actually a Berkeley DB function but a BDB module
258extension. The background for this exytension is: It is very annoying to
259have to check every single BDB function for error returns and provide a
260codepath out of your transaction. While the BDB module still makes this
261possible, it contains the following extensions:
262
263When a transaction-protected function returns any operating system
264error (errno > 0), BDB will set the C<TXN_DEADLOCK> flag on the
265transaction. This flag is also set by Berkeley DB functions themselves
266when an operation fails with LOCK_DEADLOCK, and it causes all further
267operations on that transaction (including C<db_txn_commit>) to fail.
268
269The C<db_txn_finish> request will look at this flag, and, if it is set,
270will automatically call C<db_txn_abort> (setting errno to C<LOCK_DEADLOCK>
271if it isn't set to something else yet). If it isn't set, it will call
272C<db_txn_commit> and return the error normally.
273
274How to use this? Easy: just write your transaction normally:
275
276 my $txn = $db_env->txn_begin;
277 db_get $db, $txn, "key", my $data;
278 db_put $db, $txn, "key", $data + 1 unless $! == BDB::NOTFOUND;
279 db_txn_finish $txn;
280 die "transaction failed" if $!;
281
282That is, handle only the expected errors. If something unexpected happens
283(EIO, LOCK_NOTGRANTED or a deadlock in either db_get or db_put), then the remaining
284requests (db_put in this case) will simply be skipped (they will fail with
285LOCK_DEADLOCK) and the transaction will be aborted.
286
287You can use the C<< $txn->failed >> method to check wether a transaction
288has failed in this way and abort further processing (excluding
289C<db_txn_finish>).
164 290
165=head3 DB_ENV/database environment methods 291=head3 DB_ENV/database environment methods
166 292
167Methods available on DB_ENV/$env handles: 293Methods available on DB_ENV/$env handles:
168 294
… …
174 $int = $env->set_data_dir (const char *dir) 300 $int = $env->set_data_dir (const char *dir)
175 $int = $env->set_tmp_dir (const char *dir) 301 $int = $env->set_tmp_dir (const char *dir)
176 $int = $env->set_lg_dir (const char *dir) 302 $int = $env->set_lg_dir (const char *dir)
177 $int = $env->set_shm_key (long shm_key) 303 $int = $env->set_shm_key (long shm_key)
178 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 304 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
179 $int = $env->set_flags (U32 flags, int onoff) 305 $int = $env->set_flags (U32 flags, int onoff = 1)
306 $int = $env->log_set_config (U32 flags, int onoff = 1) [v4.7]
307 $int = $env->set_intermediate_dir_mode (const char *modestring) [v4.7]
180 $env->set_errfile (FILE *errfile = 0) 308 $env->set_errfile (FILE *errfile = 0)
181 $env->set_msgfile (FILE *msgfile = 0) 309 $env->set_msgfile (FILE *msgfile = 0)
182 $int = $env->set_verbose (U32 which, int onoff = 1) 310 $int = $env->set_verbose (U32 which, int onoff = 1)
183 $int = $env->set_encrypt (const char *password, U32 flags = 0) 311 $int = $env->set_encrypt (const char *password, U32 flags = 0)
184 $int = $env->set_timeout (NV timeout, U32 flags) 312 $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT)
185 $int = $env->set_mp_max_openfd (int maxopenfd); 313 $int = $env->set_mp_max_openfd (int maxopenfd);
186 $int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep); 314 $int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep);
187 $int = $env->set_mp_mmapsize (int mmapsize_mb) 315 $int = $env->set_mp_mmapsize (int mmapsize_mb)
188 $int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT) 316 $int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT)
189 $int = $env->set_lk_max_lockers (U32 max) 317 $int = $env->set_lk_max_lockers (U32 max)
190 $int = $env->set_lk_max_locks (U32 max) 318 $int = $env->set_lk_max_locks (U32 max)
191 $int = $env->set_lk_max_objects (U32 max) 319 $int = $env->set_lk_max_objects (U32 max)
192 $int = $env->set_lg_bsize (U32 max) 320 $int = $env->set_lg_bsize (U32 max)
193 $int = $env->set_lg_max (U32 max) 321 $int = $env->set_lg_max (U32 max)
322 $int = $env->mutex_set_increment (U32 increment)
323 $int = $env->mutex_set_tas_spins (U32 tas_spins)
324 $int = $env->mutex_set_max (U32 max)
325 $int = $env->mutex_set_align (U32 align)
194 326
195 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) 327 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0)
328 flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC
196 329
197=head4 Example: 330=head4 Example:
198 331
199 use AnyEvent; 332 use AnyEvent;
200 use BDB; 333 use BDB;
… …
229 SvREFCNT_dec (env); 362 SvREFCNT_dec (env);
230 } 363 }
231 364
232 $int = $db->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 365 $int = $db->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
233 $int = $db->set_flags (U32 flags) 366 $int = $db->set_flags (U32 flags)
367 flags: CHKSUM ENCRYPT TXN_NOT_DURABLE
368 Btree: DUP DUPSORT RECNUM REVSPLITOFF
369 Hash: DUP DUPSORT
370 Queue: INORDER
371 Recno: RENUMBER SNAPSHOT
372
234 $int = $db->set_encrypt (const char *password, U32 flags) 373 $int = $db->set_encrypt (const char *password, U32 flags)
235 $int = $db->set_lorder (int lorder) 374 $int = $db->set_lorder (int lorder)
236 $int = $db->set_bt_minkey (U32 minkey) 375 $int = $db->set_bt_minkey (U32 minkey)
237 $int = $db->set_re_delim (int delim) 376 $int = $db->set_re_delim (int delim)
238 $int = $db->set_re_pad (int re_pad) 377 $int = $db->set_re_pad (int re_pad)
… …
241 $int = $db->set_h_ffactor (U32 h_ffactor) 380 $int = $db->set_h_ffactor (U32 h_ffactor)
242 $int = $db->set_h_nelem (U32 h_nelem) 381 $int = $db->set_h_nelem (U32 h_nelem)
243 $int = $db->set_q_extentsize (U32 extentsize) 382 $int = $db->set_q_extentsize (U32 extentsize)
244 383
245 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 384 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
385 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
246 $seq = $db->sequence (U32 flags = 0) 386 $seq = $db->sequence (U32 flags = 0)
247 387
248=head4 Example: 388=head4 Example:
249 389
250 my $db = db_create $env; 390 my $db = db_create $env;
… …
269 DESTROY (DB_TXN_ornull *txn) 409 DESTROY (DB_TXN_ornull *txn)
270 CODE: 410 CODE:
271 if (txn) 411 if (txn)
272 txn->abort (txn); 412 txn->abort (txn);
273 413
274 $int = $txn->set_timeout (NV timeout, U32 flags) 414 $int = $txn->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT)
415 flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT
416
417 $bool = $txn->failed
418 # see db_txn_finish documentation, above
275 419
276 420
277=head3 DBC/cursor methods 421=head3 DBC/cursor methods
278 422
279Methods available on DBC/$dbc handles: 423Methods available on DBC/$dbc handles:
280 424
281 DESTROY (DBC_ornull *dbc) 425 DESTROY (DBC_ornull *dbc)
282 CODE: 426 CODE:
283 if (dbc) 427 if (dbc)
284 dbc->c_close (dbc); 428 dbc->c_close (dbc);
429
430 $int = $cursor->set_priority ($priority = PRIORITY_*)
285 431
286=head4 Example: 432=head4 Example:
287 433
288 my $c = $db->cursor; 434 my $c = $db->cursor;
289 435
… …
306 seq->close (seq, 0); 452 seq->close (seq, 0);
307 453
308 $int = $seq->initial_value (db_seq_t value) 454 $int = $seq->initial_value (db_seq_t value)
309 $int = $seq->set_cachesize (U32 size) 455 $int = $seq->set_cachesize (U32 size)
310 $int = $seq->set_flags (U32 flags) 456 $int = $seq->set_flags (U32 flags)
457 flags: SEQ_DEC SEQ_INC SEQ_WRAP
311 $int = $seq->set_range (db_seq_t min, db_seq_t max) 458 $int = $seq->set_range (db_seq_t min, db_seq_t max)
312 459
313=head4 Example: 460=head4 Example:
314 461
315 my $seq = $db->sequence; 462 my $seq = $db->sequence;
… …
321=head2 SUPPORT FUNCTIONS 468=head2 SUPPORT FUNCTIONS
322 469
323=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 470=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
324 471
325=over 4 472=over 4
473
474=item $msg = BDB::strerror [$errno]
475
476Returns the string corresponding to the given errno value. If no argument
477is given, use C<$!>.
478
479Note that the BDB module also patches the C<$!> variable directly, so you
480should be able to get a bdb error string by simply stringifying C<$!>.
326 481
327=item $fileno = BDB::poll_fileno 482=item $fileno = BDB::poll_fileno
328 483
329Return the I<request result pipe file descriptor>. This filehandle must be 484Return the I<request result pipe file descriptor>. This filehandle must be
330polled for reading by some mechanism outside this module (e.g. Event or 485polled for reading by some mechanism outside this module (e.g. Event or
… …
369interactiveness when perl is not fast enough to process all requests in 524interactiveness when perl is not fast enough to process all requests in
370time. 525time.
371 526
372For interactive programs, values such as C<0.01> to C<0.1> should be fine. 527For interactive programs, values such as C<0.01> to C<0.1> should be fine.
373 528
374Example: Install an Event watcher that automatically calls 529Example: Install an EV watcher that automatically calls
375BDB::poll_cb with low priority, to ensure that other parts of the 530BDB::poll_cb with low priority, to ensure that other parts of the
376program get the CPU sometimes even under high AIO load. 531program get the CPU sometimes even under high load.
377 532
378 # try not to spend much more than 0.1s in poll_cb 533 # try not to spend much more than 0.1s in poll_cb
379 BDB::max_poll_time 0.1; 534 BDB::max_poll_time 0.1;
380 535
381 # use a low priority so other tasks have priority 536 my $bdb_poll = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb);
382 Event->io (fd => BDB::poll_fileno,
383 poll => 'r', nice => 1,
384 cb => &BDB::poll_cb);
385 537
386=item BDB::poll_wait 538=item BDB::poll_wait
387 539
388If there are any outstanding requests and none of them in the result 540If there are any outstanding requests and none of them in the result
389phase, wait till the result filehandle becomes ready for reading (simply 541phase, wait till the result filehandle becomes ready for reading (simply
… …
401 553
402 BDB::poll_wait, BDB::poll_cb 554 BDB::poll_wait, BDB::poll_cb
403 555
404=item BDB::flush 556=item BDB::flush
405 557
406Wait till all outstanding AIO requests have been handled. 558Wait till all outstanding BDB requests have been handled.
407 559
408Strictly equivalent to: 560Strictly equivalent to:
409 561
410 BDB::poll_wait, BDB::poll_cb 562 BDB::poll_wait, BDB::poll_cb
411 while BDB::nreqs; 563 while BDB::nreqs;
412 564
413=back 565=back
414 566
567=head3 VERSION CHECKING
568
569BerkeleyDB comes in various versions, many of them have minor
570incompatibilities. This means that traditional "at least version x.x"
571checks are often not sufficient.
572
573Example: set the log_autoremove option in a way compatible with <v.47 and
574v4.7. Note the use of & on the constants to avoid triggering a compiletime
575bug when the symbol isn't available.
576
577 $DB_ENV->set_flags (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7;
578 $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;
579
580=over 4
581
582=item BDB::VERSION
583
584The C<BDB::VERSION> function, when called without arguments, returns the
585Berkeley DB version as a v-string (usually with 3 components). You should
586use C<lt> and C<ge> operators exclusively to make comparisons.
587
588Example: check for at least version 4.7.
589
590 BDB::VERSION ge v4.7 or die;
591
592=item BDB::VERSION min-version
593
594Returns true if the BDB version is at least the given version (specified
595as a v-string), false otherwise.
596
597Example: check for at least version 4.5.
598
599 BDB::VERSION v4.7 or die;
600
601=item BDB::VERSION min-version, max-version
602
603Returns true of the BDB version is at least version C<min-version> (specify C<undef> or C<v0> for any minimum version)
604and less then C<max-version>.
605
606Example: check wether version is strictly less then v4.7.
607
608 BDB::VERSION v0, v4.7
609 or die "version 4.7 is not yet supported";
610
611=back
612
613=cut
614
615sub VERSION {
616 if (@_ > 0) {
617 return undef if VERSION_v lt $_[0];
618 if (@_ > 1) {
619 return undef if VERSION_v ge $_[1];
620 }
621 }
622
623 VERSION_v
624}
625
415=head3 CONTROLLING THE NUMBER OF THREADS 626=head3 CONTROLLING THE NUMBER OF THREADS
416 627
417=over 4 628=over 4
418 629
419=item BDB::min_parallel $nthreads 630=item BDB::min_parallel $nthreads
420 631
421Set the minimum number of AIO threads to C<$nthreads>. The current 632Set the minimum number of BDB threads to C<$nthreads>. The current
422default is C<8>, which means eight asynchronous operations can execute 633default is C<8>, which means eight asynchronous operations can execute
423concurrently at any one time (the number of outstanding requests, 634concurrently at any one time (the number of outstanding requests,
424however, is unlimited). 635however, is unlimited).
425 636
426BDB starts threads only on demand, when an AIO request is queued and 637BDB starts threads only on demand, when an BDB request is queued and
427no free thread exists. Please note that queueing up a hundred requests can 638no free thread exists. Please note that queueing up a hundred requests can
428create demand for a hundred threads, even if it turns out that everything 639create demand for a hundred threads, even if it turns out that everything
429is in the cache and could have been processed faster by a single thread. 640is in the cache and could have been processed faster by a single thread.
430 641
431It is recommended to keep the number of threads relatively low, as some 642It is recommended to keep the number of threads relatively low, as some
… …
436Under most circumstances you don't need to call this function, as the 647Under most circumstances you don't need to call this function, as the
437module selects a default that is suitable for low to moderate load. 648module selects a default that is suitable for low to moderate load.
438 649
439=item BDB::max_parallel $nthreads 650=item BDB::max_parallel $nthreads
440 651
441Sets the maximum number of AIO threads to C<$nthreads>. If more than the 652Sets the maximum number of BDB threads to C<$nthreads>. If more than the
442specified number of threads are currently running, this function kills 653specified number of threads are currently running, this function kills
443them. This function blocks until the limit is reached. 654them. This function blocks until the limit is reached.
444 655
445While C<$nthreads> are zero, aio requests get queued but not executed 656While C<$nthreads> are zero, aio requests get queued but not executed
446until the number of threads has been increased again. 657until the number of threads has been increased again.
… …
485 696
486=item BDB::set_sync_prepare $cb 697=item BDB::set_sync_prepare $cb
487 698
488Sets a callback that is called whenever a request is created without an 699Sets a callback that is called whenever a request is created without an
489explicit callback. It has to return two code references. The first is used 700explicit callback. It has to return two code references. The first is used
490as the request callback, and the second is called to wait until the first 701as the request callback (it should save the return status), and the second
702is called to wait until the first callback has been called (it must set
703C<$!> to the return status).
704
705This mechanism can be used to include BDB into other event mechanisms,
706such as L<AnyEvent::BDB> or L<Coro::BDB>.
707
491callback has been called. The default implementation works like this: 708The default implementation works like this:
492 709
493 sub { 710 sub {
494 my $status; 711 my $status;
495 ( 712 (
496 sub { $status = $! }, 713 sub { $status = $! },
497 sub { BDB::poll while !defined $status; $! = $status }, 714 sub { BDB::poll while !defined $status; $! = $status },
498 ) 715 )
499 } 716 }
717
718It simply blocks the process till the request has finished and then sets
719C<$!> to the return value. This means that if you don't use a callback,
720BDB will simply fall back to synchronous operations.
500 721
501=back 722=back
502 723
503=head3 STATISTICAL INFORMATION 724=head3 STATISTICAL INFORMATION
504 725
… …
549 770
550=head2 FORK BEHAVIOUR 771=head2 FORK BEHAVIOUR
551 772
552This module should do "the right thing" when the process using it forks: 773This module should do "the right thing" when the process using it forks:
553 774
554Before the fork, IO::AIO enters a quiescent state where no requests 775Before the fork, BDB enters a quiescent state where no requests
555can be added in other threads and no results will be processed. After 776can be added in other threads and no results will be processed. After
556the fork the parent simply leaves the quiescent state and continues 777the fork the parent simply leaves the quiescent state and continues
557request/result processing, while the child frees the request/result queue 778request/result processing, while the child frees the request/result queue
558(so that the requests started before the fork will only be handled in the 779(so that the requests started before the fork will only be handled in the
559parent). Threads will be started on demand until the limit set in the 780parent). Threads will be started on demand until the limit set in the
560parent process has been reached again. 781parent process has been reached again.
561 782
562In short: the parent will, after a short pause, continue as if fork had 783In short: the parent will, after a short pause, continue as if fork had
563not been called, while the child will act as if IO::AIO has not been used 784not been called, while the child will act as if BDB has not been used
564yet. 785yet.
786
787Win32 note: there is no fork on win32, and perls emulation of it is too
788broken to be supported, so do not use BDB in a windows pseudo-fork, better
789yet, switch to a more capable platform.
565 790
566=head2 MEMORY USAGE 791=head2 MEMORY USAGE
567 792
568Per-request usage: 793Per-request usage:
569 794
… …
582temporary buffers, and each thread requires a stack and other data 807temporary buffers, and each thread requires a stack and other data
583structures (usually around 16k-128k, depending on the OS). 808structures (usually around 16k-128k, depending on the OS).
584 809
585=head1 KNOWN BUGS 810=head1 KNOWN BUGS
586 811
587Known bugs will be fixed in the next release. 812Known bugs will be fixed in the next release, except:
813
814 If you use a transaction in any request, and the request returns
815 with an operating system error or DB_LOCK_NOTGRANTED, the internal
816 TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>,
817 above.
588 818
589=head1 SEE ALSO 819=head1 SEE ALSO
590 820
591L<Coro::AIO>. 821L<AnyEvent::BDB> (event loop integration), L<Coro::BDB> (more natural
822syntax), L<IO::AIO> (nice to have).
592 823
593=head1 AUTHOR 824=head1 AUTHOR
594 825
595 Marc Lehmann <schmorp@schmorp.de> 826 Marc Lehmann <schmorp@schmorp.de>
596 http://home.schmorp.de/ 827 http://home.schmorp.de/

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