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Comparing BDB/BDB.pm (file contents):
Revision 1.10 by root, Mon Aug 13 12:01:45 2007 UTC vs.
Revision 1.40 by root, Tue Jul 8 08:35:12 2008 UTC

… …
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use BDB; 7 use BDB;
8 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
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 ahs been very faithful). 49The BDB API is very similar to the C API (the translation has been very faithful).
13 50
14See also the example sections in the document below and possibly the eg/ 51See also the example sections in the document below and possibly the eg/
15subdirectory of the BDB distribution. Last not least see the IO::AIO 52subdirectory of the BDB distribution. Last not least see the IO::AIO
16documentation, as that module uses almost the same asynchronous request 53documentation, as that module uses almost the same asynchronous request
17model as this module. 54model as this module.
… …
72use strict 'vars'; 109use strict 'vars';
73 110
74use base 'Exporter'; 111use base 'Exporter';
75 112
76BEGIN { 113BEGIN {
77 our $VERSION = '0.6'; 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 165The 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), and the C<SV *callback> is the optional callback function to call
119when the request is completed. 167when the request is completed.
120 168
121The various C<DB_ENV> etc. arguments are handles return by db_env_create>, 169The various C<DB_ENV> etc. arguments are handles return by
122C<C<db_create>, C<txn_begin> and so on. If they have an appended _ornull> 170C<db_env_create>, C<db_create>, C<txn_begin> and so on. If they have an
123C<this means they are optional and you can pass C<undef> for them, 171appended C<_ornull> this means they are optional and you can pass C<undef>
124C<resulting a NULL pointer on the C level. 172for them, resulting a NULL pointer on the C level.
125 173
126=head3 BDB functions 174=head3 BDB functions
127 175
128Functions in the BDB namespace, exported by default: 176Functions in the BDB namespace, exported by default:
129 177
130 $env = db_env_create (U32 env_flags = 0) 178 $env = db_env_create (U32 env_flags = 0)
179 flags: RPCCLIENT
131 180
132 db_env_open (DB_ENV *env, octetstring db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef) 181 db_env_open (DB_ENV *env, bdb_filename db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef)
182 open_flags: INIT_CDB INIT_LOCK INIT_LOG INIT_MPOOL INIT_REP INIT_TXN RECOVER RECOVER_FATAL USE_ENVIRON USE_ENVIRON_ROOT CREATE LOCKDOWN PRIVATE REGISTER SYSTEM_MEM
133 db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef) 183 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) 184 db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
185 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) 186 db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef)
187 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) 188 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) 189 db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef)
190 db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = &PL_sv_undef)
191 db_env_dbrename (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, bdb_filename newname, U32 flags = 0, SV *callback = &PL_sv_undef)
138 192
139 $db = db_create (DB_ENV *env = 0, U32 flags = 0) 193 $db = db_create (DB_ENV *env = 0, U32 flags = 0)
194 flags: XA_CREATE
140 195
141 db_open (DB *db, DB_TXN_ornull *txnid, octetstring file, octetstring database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef) 196 db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef)
197 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) 198 db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef)
199 flags: DB_NOSYNC
200 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_unde 201 db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = &PL_sv_undef)
202 flags: FREELIST_ONLY FREE_SPACE
144 db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) 203 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) 204 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) 205 db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
206 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) 207 db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
208 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) 209 db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
210 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) 211 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) 212 db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef)
213 flags: TXN_NOSYNC TXN_SYNC
151 db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef) 214 db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef)
215
152 db_c_close (DBC *dbc, SV *callback = &PL_sv_undef) 216 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) 217 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) 218 db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
219 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) 220 db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
221 flags: CURRENT FIRST GET_BOTH GET_BOTH_RANGE GET_RECNO JOIN_ITEM LAST NEXT NEXT_DUP NEXT_NODUP PREV PREV_DUP PREV_NODUP SET SET_RANGE SET_RECNO READ_UNCOMMITTED MULTIPLE MULTIPLE_KEY RMW
156 db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) 222 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) 223 db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef)
158 224
159 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) 225 db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef)
226 flags: CREATE EXCL
160 db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef) 227 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) 228 db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = &PL_sv_undef)
229 flags: TXN_NOSYNC
162 db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) 230 db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
231 flags: TXN_NOSYNC
163 232
233=head4 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef)
234
235This is not actually a Berkeley DB function but a BDB module
236extension. The background for this exytension is: It is very annoying to
237have to check every single BDB function for error returns and provide a
238codepath out of your transaction. While the BDB module still makes this
239possible, it contains the following extensions:
240
241When a transaction-protected function returns any operating system
242error (errno > 0), BDB will set the C<TXN_DEADLOCK> flag on the
243transaction. This flag is also set by Berkeley DB functions themselves
244when an operation fails with LOCK_DEADLOCK, and it causes all further
245operations on that transaction (including C<db_txn_commit>) to fail.
246
247The C<db_txn_finish> request will look at this flag, and, if it is set,
248will automatically call C<db_txn_abort> (setting errno to C<LOCK_DEADLOCK>
249if it isn't set to something else yet). If it isn't set, it will call
250C<db_txn_commit> and return the error normally.
251
252How to use this? Easy: just write your transaction normally:
253
254 my $txn = $db_env->txn_begin;
255 db_get $db, $txn, "key", my $data;
256 db_put $db, $txn, "key", $data + 1 unless $! == BDB::NOTFOUND;
257 db_txn_finish $txn;
258 die "transaction failed" if $!;
259
260That is, handle only the expected errors. If something unexpected happens
261(EIO, LOCK_NOTGRANTED or a deadlock in either db_get or db_put), then the remaining
262requests (db_put in this case) will simply be skipped (they will fail with
263LOCK_DEADLOCK) and the transaction will be aborted.
264
265You can use the C<< $txn->failed >> method to check wether a transaction
266has failed in this way and abort further processing (excluding
267C<db_txn_finish>).
164 268
165=head3 DB_ENV/database environment methods 269=head3 DB_ENV/database environment methods
166 270
167Methods available on DB_ENV/$env handles: 271Methods available on DB_ENV/$env handles:
168 272
… …
174 $int = $env->set_data_dir (const char *dir) 278 $int = $env->set_data_dir (const char *dir)
175 $int = $env->set_tmp_dir (const char *dir) 279 $int = $env->set_tmp_dir (const char *dir)
176 $int = $env->set_lg_dir (const char *dir) 280 $int = $env->set_lg_dir (const char *dir)
177 $int = $env->set_shm_key (long shm_key) 281 $int = $env->set_shm_key (long shm_key)
178 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 282 $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
179 $int = $env->set_flags (U32 flags, int onoff) 283 $int = $env->set_flags (U32 flags, int onoff = 1)
284 $int = $env->log_set_config (U32 flags, int onoff = 1) [v4.7]
285 $int = $env->set_intermediate_dir_mode (const char *modestring) [v4.7]
180 $env->set_errfile (FILE *errfile = 0) 286 $env->set_errfile (FILE *errfile = 0)
181 $env->set_msgfile (FILE *msgfile = 0) 287 $env->set_msgfile (FILE *msgfile = 0)
182 $int = $env->set_verbose (U32 which, int onoff = 1) 288 $int = $env->set_verbose (U32 which, int onoff = 1)
183 $int = $env->set_encrypt (const char *password, U32 flags = 0) 289 $int = $env->set_encrypt (const char *password, U32 flags = 0)
184 $int = $env->set_timeout (NV timeout, U32 flags) 290 $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT)
185 $int = $env->set_mp_max_openfd (int maxopenfd); 291 $int = $env->set_mp_max_openfd (int maxopenfd);
186 $int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep); 292 $int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep);
187 $int = $env->set_mp_mmapsize (int mmapsize_mb) 293 $int = $env->set_mp_mmapsize (int mmapsize_mb)
188 $int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT) 294 $int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT)
189 $int = $env->set_lk_max_lockers (U32 max) 295 $int = $env->set_lk_max_lockers (U32 max)
190 $int = $env->set_lk_max_locks (U32 max) 296 $int = $env->set_lk_max_locks (U32 max)
191 $int = $env->set_lk_max_objects (U32 max) 297 $int = $env->set_lk_max_objects (U32 max)
192 $int = $env->set_lg_bsize (U32 max) 298 $int = $env->set_lg_bsize (U32 max)
193 $int = $env->set_lg_max (U32 max) 299 $int = $env->set_lg_max (U32 max)
300 $int = $env->mutex_set_increment (U32 increment)
301 $int = $env->mutex_set_tas_spins (U32 tas_spins)
302 $int = $env->mutex_set_max (U32 max)
303 $int = $env->mutex_set_align (U32 align)
194 304
195 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) 305 $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0)
306 flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC
196 307
197=head4 example 308=head4 Example:
198 309
199 use AnyEvent; 310 use AnyEvent;
200 use BDB; 311 use BDB;
201 312
202 our $FH; open $FH, "<&=" . BDB::poll_fileno; 313 our $FH; open $FH, "<&=" . BDB::poll_fileno;
… …
229 SvREFCNT_dec (env); 340 SvREFCNT_dec (env);
230 } 341 }
231 342
232 $int = $db->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) 343 $int = $db->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
233 $int = $db->set_flags (U32 flags) 344 $int = $db->set_flags (U32 flags)
345 flags: CHKSUM ENCRYPT TXN_NOT_DURABLE
346 Btree: DUP DUPSORT RECNUM REVSPLITOFF
347 Hash: DUP DUPSORT
348 Queue: INORDER
349 Recno: RENUMBER SNAPSHOT
350
234 $int = $db->set_encrypt (const char *password, U32 flags) 351 $int = $db->set_encrypt (const char *password, U32 flags)
235 $int = $db->set_lorder (int lorder) 352 $int = $db->set_lorder (int lorder)
236 $int = $db->set_bt_minkey (U32 minkey) 353 $int = $db->set_bt_minkey (U32 minkey)
237 $int = $db->set_re_delim (int delim) 354 $int = $db->set_re_delim (int delim)
238 $int = $db->set_re_pad (int re_pad) 355 $int = $db->set_re_pad (int re_pad)
… …
241 $int = $db->set_h_ffactor (U32 h_ffactor) 358 $int = $db->set_h_ffactor (U32 h_ffactor)
242 $int = $db->set_h_nelem (U32 h_nelem) 359 $int = $db->set_h_nelem (U32 h_nelem)
243 $int = $db->set_q_extentsize (U32 extentsize) 360 $int = $db->set_q_extentsize (U32 extentsize)
244 361
245 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) 362 $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
363 flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
246 $seq = $db->sequence (U32 flags = 0) 364 $seq = $db->sequence (U32 flags = 0)
247 365
248=head4 example 366=head4 Example:
249 367
250 my $db = db_create $env; 368 my $db = db_create $env;
251 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600; 369 db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600;
252 370
253 for (1..1000) { 371 for (1..1000) {
… …
269 DESTROY (DB_TXN_ornull *txn) 387 DESTROY (DB_TXN_ornull *txn)
270 CODE: 388 CODE:
271 if (txn) 389 if (txn)
272 txn->abort (txn); 390 txn->abort (txn);
273 391
274 $int = $txn->set_timeout (NV timeout, U32 flags) 392 $int = $txn->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT)
393 flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT
394
395 $bool = $txn->failed
396 # see db_txn_finish documentation, above
275 397
276 398
277=head3 DBC/cursor methods 399=head3 DBC/cursor methods
278 400
279Methods available on DBC/$dbc handles: 401Methods available on DBC/$dbc handles:
… …
281 DESTROY (DBC_ornull *dbc) 403 DESTROY (DBC_ornull *dbc)
282 CODE: 404 CODE:
283 if (dbc) 405 if (dbc)
284 dbc->c_close (dbc); 406 dbc->c_close (dbc);
285 407
408 $int = $cursor->set_priority ($priority = PRIORITY_*)
409
286=head4 example 410=head4 Example:
287 411
288 my $c = $db->cursor; 412 my $c = $db->cursor;
289 413
290 for (;;) { 414 for (;;) {
291 db_c_get $c, my $key, my $data, BDB::NEXT; 415 db_c_get $c, my $key, my $data, BDB::NEXT;
… …
293 last if $!; 417 last if $!;
294 } 418 }
295 419
296 db_c_close $c; 420 db_c_close $c;
297 421
422
298=head3 DB_SEQUENCE/sequence methods 423=head3 DB_SEQUENCE/sequence methods
299 424
300Methods available on DB_SEQUENCE/$seq handles: 425Methods available on DB_SEQUENCE/$seq handles:
301 426
302 DESTROY (DB_SEQUENCE_ornull *seq) 427 DESTROY (DB_SEQUENCE_ornull *seq)
… …
305 seq->close (seq, 0); 430 seq->close (seq, 0);
306 431
307 $int = $seq->initial_value (db_seq_t value) 432 $int = $seq->initial_value (db_seq_t value)
308 $int = $seq->set_cachesize (U32 size) 433 $int = $seq->set_cachesize (U32 size)
309 $int = $seq->set_flags (U32 flags) 434 $int = $seq->set_flags (U32 flags)
435 flags: SEQ_DEC SEQ_INC SEQ_WRAP
310 $int = $seq->set_range (db_seq_t min, db_seq_t max) 436 $int = $seq->set_range (db_seq_t min, db_seq_t max)
311 437
312=head4 example 438=head4 Example:
313 439
314 my $seq = $db->sequence; 440 my $seq = $db->sequence;
315 441
316 db_sequence_open $seq, undef, "seq", BDB::CREATE; 442 db_sequence_open $seq, undef, "seq", BDB::CREATE;
317 db_sequence_get $seq, undef, 1, my $value; 443 db_sequence_get $seq, undef, 1, my $value;
… …
320=head2 SUPPORT FUNCTIONS 446=head2 SUPPORT FUNCTIONS
321 447
322=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION 448=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
323 449
324=over 4 450=over 4
451
452=item $msg = BDB::strerror [$errno]
453
454Returns the string corresponding to the given errno value. If no argument
455is given, use C<$!>.
456
457Note that the BDB module also patches the C<$!> variable directly, so you
458should be able to get a bdb error string by simply stringifying C<$!>.
325 459
326=item $fileno = BDB::poll_fileno 460=item $fileno = BDB::poll_fileno
327 461
328Return the I<request result pipe file descriptor>. This filehandle must be 462Return the I<request result pipe file descriptor>. This filehandle must be
329polled for reading by some mechanism outside this module (e.g. Event or 463polled for reading by some mechanism outside this module (e.g. Event or
… …
368interactiveness when perl is not fast enough to process all requests in 502interactiveness when perl is not fast enough to process all requests in
369time. 503time.
370 504
371For interactive programs, values such as C<0.01> to C<0.1> should be fine. 505For interactive programs, values such as C<0.01> to C<0.1> should be fine.
372 506
373Example: Install an Event watcher that automatically calls 507Example: Install an EV watcher that automatically calls
374BDB::poll_cb with low priority, to ensure that other parts of the 508BDB::poll_cb with low priority, to ensure that other parts of the
375program get the CPU sometimes even under high AIO load. 509program get the CPU sometimes even under high load.
376 510
377 # try not to spend much more than 0.1s in poll_cb 511 # try not to spend much more than 0.1s in poll_cb
378 BDB::max_poll_time 0.1; 512 BDB::max_poll_time 0.1;
379 513
380 # use a low priority so other tasks have priority 514 my $bdb_poll = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb);
381 Event->io (fd => BDB::poll_fileno,
382 poll => 'r', nice => 1,
383 cb => &BDB::poll_cb);
384 515
385=item BDB::poll_wait 516=item BDB::poll_wait
386 517
387If there are any outstanding requests and none of them in the result 518If there are any outstanding requests and none of them in the result
388phase, wait till the result filehandle becomes ready for reading (simply 519phase, wait till the result filehandle becomes ready for reading (simply
… …
400 531
401 BDB::poll_wait, BDB::poll_cb 532 BDB::poll_wait, BDB::poll_cb
402 533
403=item BDB::flush 534=item BDB::flush
404 535
405Wait till all outstanding AIO requests have been handled. 536Wait till all outstanding BDB requests have been handled.
406 537
407Strictly equivalent to: 538Strictly equivalent to:
408 539
409 BDB::poll_wait, BDB::poll_cb 540 BDB::poll_wait, BDB::poll_cb
410 while BDB::nreqs; 541 while BDB::nreqs;
411 542
412=back 543=back
413 544
545=head3 VERSION CHECKING
546
547BerkeleyDB comes in various versions, many of them have minor
548incompatibilities. This means that traditional "at least version x.x"
549checks are often not sufficient.
550
551Example: set the log_autoremove option in a way compatible with <v.47 and
552v4.7. Note the use of & on the constants to avoid triggering a compiletime
553bug when the symbol isn't available.
554
555 $DB_ENV->set_flags (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7;
556 $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;
557
558=over 4
559
560=item BDB::VERSION
561
562The C<BDB::VERSION> function, when called without arguments, returns the
563Berkeley DB version as a v-string (usually with 3 components). You should
564use C<lt> and C<ge> operators exclusively to make comparisons.
565
566Example: check for at least version 4.7.
567
568 BDB::VERSION ge v4.7 or die;
569
570=item BDB::VERSION min-version
571
572Returns true if the BDB version is at least the given version (specified
573as a v-string), false otherwise.
574
575Example: check for at least version 4.5.
576
577 BDB::VERSION v4.7 or die;
578
579=item BDB::VERSION min-version, max-version
580
581Returns true of the BDB version is at least version C<min-version> (specify C<undef> or C<v0> for any minimum version)
582and less then C<max-version>.
583
584Example: check wether version is strictly less then v4.7.
585
586 BDB::VERSION v0, v4.7
587 or die "version 4.7 is not yet supported";
588
589=back
590
591=cut
592
593sub VERSION {
594 if (@_ > 0) {
595 return undef if VERSION_v lt $_[0];
596 if (@_ > 1) {
597 return undef if VERSION_v ge $_[1];
598 }
599 }
600
601 VERSION_v
602}
603
414=head3 CONTROLLING THE NUMBER OF THREADS 604=head3 CONTROLLING THE NUMBER OF THREADS
415 605
416=over 4 606=over 4
417 607
418=item BDB::min_parallel $nthreads 608=item BDB::min_parallel $nthreads
419 609
420Set the minimum number of AIO threads to C<$nthreads>. The current 610Set the minimum number of BDB threads to C<$nthreads>. The current
421default is C<8>, which means eight asynchronous operations can execute 611default is C<8>, which means eight asynchronous operations can execute
422concurrently at any one time (the number of outstanding requests, 612concurrently at any one time (the number of outstanding requests,
423however, is unlimited). 613however, is unlimited).
424 614
425BDB starts threads only on demand, when an AIO request is queued and 615BDB starts threads only on demand, when an BDB request is queued and
426no free thread exists. Please note that queueing up a hundred requests can 616no free thread exists. Please note that queueing up a hundred requests can
427create demand for a hundred threads, even if it turns out that everything 617create demand for a hundred threads, even if it turns out that everything
428is in the cache and could have been processed faster by a single thread. 618is in the cache and could have been processed faster by a single thread.
429 619
430It is recommended to keep the number of threads relatively low, as some 620It is recommended to keep the number of threads relatively low, as some
… …
435Under most circumstances you don't need to call this function, as the 625Under most circumstances you don't need to call this function, as the
436module selects a default that is suitable for low to moderate load. 626module selects a default that is suitable for low to moderate load.
437 627
438=item BDB::max_parallel $nthreads 628=item BDB::max_parallel $nthreads
439 629
440Sets the maximum number of AIO threads to C<$nthreads>. If more than the 630Sets the maximum number of BDB threads to C<$nthreads>. If more than the
441specified number of threads are currently running, this function kills 631specified number of threads are currently running, this function kills
442them. This function blocks until the limit is reached. 632them. This function blocks until the limit is reached.
443 633
444While C<$nthreads> are zero, aio requests get queued but not executed 634While C<$nthreads> are zero, aio requests get queued but not executed
445until the number of threads has been increased again. 635until the number of threads has been increased again.
… …
484 674
485=item BDB::set_sync_prepare $cb 675=item BDB::set_sync_prepare $cb
486 676
487Sets a callback that is called whenever a request is created without an 677Sets a callback that is called whenever a request is created without an
488explicit callback. It has to return two code references. The first is used 678explicit callback. It has to return two code references. The first is used
489as the request callback, and the second is called to wait until the first 679as the request callback (it should save the return status), and the second
680is called to wait until the first callback has been called (it must set
681C<$!> to the return status).
682
683This mechanism can be used to include BDB into other event mechanisms,
684such as L<AnyEvent::BDB> or L<Coro::BDB>.
685
490callback has been called. The default implementation works like this: 686The default implementation works like this:
491 687
492 sub { 688 sub {
493 my $status; 689 my $status;
494 ( 690 (
495 sub { $status = $! }, 691 sub { $status = $! },
496 sub { BDB::poll while !defined $status; $! = $status }, 692 sub { BDB::poll while !defined $status; $! = $status },
497 ) 693 )
498 } 694 }
695
696It simply blocks the process till the request has finished and then sets
697C<$!> to the return value. This means that if you don't use a callback,
698BDB will simply fall back to synchronous operations.
499 699
500=back 700=back
501 701
502=head3 STATISTICAL INFORMATION 702=head3 STATISTICAL INFORMATION
503 703
… …
548 748
549=head2 FORK BEHAVIOUR 749=head2 FORK BEHAVIOUR
550 750
551This module should do "the right thing" when the process using it forks: 751This module should do "the right thing" when the process using it forks:
552 752
553Before the fork, IO::AIO enters a quiescent state where no requests 753Before the fork, BDB enters a quiescent state where no requests
554can be added in other threads and no results will be processed. After 754can be added in other threads and no results will be processed. After
555the fork the parent simply leaves the quiescent state and continues 755the fork the parent simply leaves the quiescent state and continues
556request/result processing, while the child frees the request/result queue 756request/result processing, while the child frees the request/result queue
557(so that the requests started before the fork will only be handled in the 757(so that the requests started before the fork will only be handled in the
558parent). Threads will be started on demand until the limit set in the 758parent). Threads will be started on demand until the limit set in the
559parent process has been reached again. 759parent process has been reached again.
560 760
561In short: the parent will, after a short pause, continue as if fork had 761In short: the parent will, after a short pause, continue as if fork had
562not been called, while the child will act as if IO::AIO has not been used 762not been called, while the child will act as if BDB has not been used
563yet. 763yet.
764
765Win32 note: there is no fork on win32, and perls emulation of it is too
766broken to be supported, so do not use BDB in a windows pseudo-fork, better
767yet, switch to a more capable platform.
564 768
565=head2 MEMORY USAGE 769=head2 MEMORY USAGE
566 770
567Per-request usage: 771Per-request usage:
568 772
… …
570bytes of memory. In addition, stat requests need a stat buffer (possibly 774bytes of memory. In addition, stat requests need a stat buffer (possibly
571a few hundred bytes), readdir requires a result buffer and so on. Perl 775a few hundred bytes), readdir requires a result buffer and so on. Perl
572scalars and other data passed into aio requests will also be locked and 776scalars and other data passed into aio requests will also be locked and
573will consume memory till the request has entered the done state. 777will consume memory till the request has entered the done state.
574 778
575This is now awfully much, so queuing lots of requests is not usually a 779This is not awfully much, so queuing lots of requests is not usually a
576problem. 780problem.
577 781
578Per-thread usage: 782Per-thread usage:
579 783
580In the execution phase, some aio requests require more memory for 784In the execution phase, some aio requests require more memory for
581temporary buffers, and each thread requires a stack and other data 785temporary buffers, and each thread requires a stack and other data
582structures (usually around 16k-128k, depending on the OS). 786structures (usually around 16k-128k, depending on the OS).
583 787
584=head1 KNOWN BUGS 788=head1 KNOWN BUGS
585 789
586Known bugs will be fixed in the next release. 790Known bugs will be fixed in the next release, except:
791
792 If you use a transaction in any request, and the request returns
793 with an operating system error or DB_LOCK_NOTGRANTED, the internal
794 TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>,
795 above.
587 796
588=head1 SEE ALSO 797=head1 SEE ALSO
589 798
590L<Coro::AIO>. 799L<AnyEvent::BDB> (event loop integration), L<Coro::BDB> (more natural
800syntax), L<IO::AIO> (nice to have).
591 801
592=head1 AUTHOR 802=head1 AUTHOR
593 803
594 Marc Lehmann <schmorp@schmorp.de> 804 Marc Lehmann <schmorp@schmorp.de>
595 http://home.schmorp.de/ 805 http://home.schmorp.de/

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