1 | NAME |
1 | NAME |
2 | BDB - Asynchronous Berkeley DB access |
2 | BDB - Asynchronous Berkeley DB access |
3 | |
3 | |
4 | SYNOPSIS |
4 | SYNOPSIS |
5 | use BDB; |
5 | use BDB; |
|
|
6 | |
|
|
7 | my $env = db_env_create; |
|
|
8 | |
|
|
9 | mkdir "bdtest", 0700; |
|
|
10 | db_env_open |
|
|
11 | $env, |
|
|
12 | "bdtest", |
|
|
13 | BDB::INIT_LOCK | BDB::INIT_LOG | BDB::INIT_MPOOL |
|
|
14 | | BDB::INIT_TXN | BDB::RECOVER | BDB::USE_ENVIRON | BDB::CREATE, |
|
|
15 | 0600; |
|
|
16 | |
|
|
17 | $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); |
|
|
18 | |
|
|
19 | my $db = db_create $env; |
|
|
20 | db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE |
|
|
21 | | BDB::READ_UNCOMMITTED, 0600; |
|
|
22 | db_put $db, undef, "key", "data", 0, sub { |
|
|
23 | db_del $db, undef, "key"; |
|
|
24 | }; |
|
|
25 | db_sync $db; |
|
|
26 | |
|
|
27 | # when you also use Coro, management is easy: |
|
|
28 | use Coro::BDB; |
|
|
29 | |
|
|
30 | # automatic event loop intergration with AnyEvent: |
|
|
31 | use AnyEvent::BDB; |
|
|
32 | |
|
|
33 | # automatic result processing with EV: |
|
|
34 | my $WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb; |
|
|
35 | |
|
|
36 | # with Glib: |
|
|
37 | add_watch Glib::IO BDB::poll_fileno, |
|
|
38 | in => sub { BDB::poll_cb; 1 }; |
|
|
39 | |
|
|
40 | # or simply flush manually |
|
|
41 | BDB::flush; |
6 | |
42 | |
7 | DESCRIPTION |
43 | DESCRIPTION |
8 | See the BerkeleyDB documentation |
44 | See the BerkeleyDB documentation |
9 | (<http://www.oracle.com/technology/documentation/berkeley-db/db/index.ht |
45 | (<http://www.oracle.com/technology/documentation/berkeley-db/db/index.ht |
10 | ml>). The BDB API is very similar to the C API (the translation has been |
46 | ml>). The BDB API is very similar to the C API (the translation has been |
… | |
… | |
50 | Request has reached the end of its lifetime and holds no resources |
86 | Request has reached the end of its lifetime and holds no resources |
51 | anymore (except possibly for the Perl object, but its connection to |
87 | anymore (except possibly for the Perl object, but its connection to |
52 | the actual aio request is severed and calling its methods will |
88 | the actual aio request is severed and calling its methods will |
53 | either do nothing or result in a runtime error). |
89 | either do nothing or result in a runtime error). |
54 | |
90 | |
55 | BERKELEYDB FUNCTIONS |
91 | BERKELEYDB FUNCTIONS |
56 | All of these are functions. The create functions simply return a new |
92 | All of these are functions. The create functions simply return a new |
57 | object and never block. All the remaining functions all take an optional |
93 | object and never block. All the remaining functions take an optional |
58 | callback as last argument. If it is missing, then the fucntion will be |
94 | callback as last argument. If it is missing, then the function will be |
59 | executed synchronously. |
95 | executed synchronously. In both cases, $! will reflect the return value |
|
|
96 | of the function. |
60 | |
97 | |
61 | BDB functions that cannot block (mostly functions that manipulate |
98 | BDB functions that cannot block (mostly functions that manipulate |
62 | settings) are method calls on the relevant objects, so the rule of thumb |
99 | settings) are method calls on the relevant objects, so the rule of thumb |
63 | is: if its a method, its not blocking, if its a function, it takes a |
100 | is: if it's a method, it's not blocking, if it's a function, it takes a |
64 | callback as last argument. |
101 | callback as last argument. |
65 | |
102 | |
66 | In the following, $int signifies an integer return value, "octetstring" |
103 | In the following, $int signifies an integer return value, "bdb_filename" |
67 | is a "binary string" (i.e. a perl string with no character indices |
104 | is a "filename" (octets on unix, madness on windows), "U32" is an |
68 | >255), "U32" is an unsigned 32 bit integer, "int" is some integer, "NV" |
105 | unsigned 32 bit integer, "int" is some integer, "NV" is a floating point |
69 | is a floating point value. |
106 | value. |
70 | |
107 | |
71 | The "SV *" types are generic perl scalars (for input and output of data |
108 | Most "SV *" types are generic perl scalars (for input and output of data |
72 | values), and the "SV *callback" is the optional callback function to |
109 | values). |
73 | call when the request is completed. |
|
|
74 | |
110 | |
75 | The various "DB_ENV" etc. arguments are handles return by |
111 | The various "DB_ENV" etc. arguments are handles return by |
76 | "db_env_create", "db_create", "txn_begin" and so on. If they have an |
112 | "db_env_create", "db_create", "txn_begin" and so on. If they have an |
77 | appended "_ornull" this means they are optional and you can pass "undef" |
113 | appended "_ornull" this means they are optional and you can pass "undef" |
78 | for them, resulting a NULL pointer on the C level. |
114 | for them, resulting a NULL pointer on the C level. |
79 | |
115 | |
|
|
116 | The "SV *callback" is the optional callback function to call when the |
|
|
117 | request is completed. This last callback argument is special: the |
|
|
118 | callback is simply the last argument passed. If there are "optional" |
|
|
119 | arguments before the callback they can be left out. The callback itself |
|
|
120 | can be left out or specified as "undef", in which case the function will |
|
|
121 | be executed synchronously. |
|
|
122 | |
|
|
123 | For example, "db_env_txn_checkpoint" usually is called with all integer |
|
|
124 | arguments zero. These can be left out, so all of these specify a call to |
|
|
125 | "DB_ENV->txn_checkpoint", to be executed asynchronously with a callback |
|
|
126 | to be called: |
|
|
127 | |
|
|
128 | db_env_txn_checkpoint $db_env, 0, 0, 0, sub { }; |
|
|
129 | db_env_txn_checkpoint $db_env, 0, 0, sub { }; |
|
|
130 | db_env_txn_checkpoint $db_env, sub { }; |
|
|
131 | |
|
|
132 | While these all specify a call to "DB_ENV->txn_checkpoint" to be |
|
|
133 | executed synchronously: |
|
|
134 | |
|
|
135 | db_env_txn_checkpoint $db_env, 0, 0, 0, undef; |
|
|
136 | db_env_txn_checkpoint $db_env, 0, 0, 0; |
|
|
137 | db_env_txn_checkpoint $db_env, 0; |
|
|
138 | |
80 | BDB functions |
139 | BDB functions |
81 | Functions in the BDB namespace, exported by default: |
140 | Functions in the BDB namespace, exported by default: |
82 | |
141 | |
83 | $env = db_env_create (U32 env_flags = 0) |
142 | $env = db_env_create (U32 env_flags = 0) |
84 | flags: RPCCLIENT |
143 | flags: RPCCLIENT |
85 | |
144 | |
86 | db_env_open (DB_ENV *env, octetstring db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef) |
145 | db_env_open (DB_ENV *env, bdb_filename db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef) |
87 | 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 |
146 | 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 |
88 | db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef) |
147 | db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef) |
89 | db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef) |
148 | db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef) |
90 | flags: FORCE |
149 | flags: FORCE |
91 | db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef) |
150 | db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef) |
92 | atype: LOCK_DEFAULT LOCK_EXPIRE LOCK_MAXLOCKS LOCK_MAXWRITE LOCK_MINLOCKS LOCK_MINWRITE LOCK_OLDEST LOCK_RANDOM LOCK_YOUNGEST |
151 | atype: LOCK_DEFAULT LOCK_EXPIRE LOCK_MAXLOCKS LOCK_MAXWRITE LOCK_MINLOCKS LOCK_MINWRITE LOCK_OLDEST LOCK_RANDOM LOCK_YOUNGEST |
93 | db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = &PL_sv_undef) |
152 | db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = &PL_sv_undef) |
94 | db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef) |
153 | db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef) |
|
|
154 | db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = &PL_sv_undef) |
|
|
155 | 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) |
|
|
156 | db_env_log_archive (DB_ENV *env, SV *listp, U32 flags = 0, SV *callback = &PL_sv_undef) |
95 | |
157 | |
96 | $db = db_create (DB_ENV *env = 0, U32 flags = 0) |
158 | $db = db_create (DB_ENV *env = 0, U32 flags = 0) |
97 | flags: XA_CREATE |
159 | flags: XA_CREATE |
98 | |
160 | |
99 | db_open (DB *db, DB_TXN_ornull *txnid, octetstring file, octetstring database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef) |
161 | 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) |
100 | flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE |
162 | flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE |
101 | db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
163 | db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
102 | flags: DB_NOSYNC |
164 | flags: DB_NOSYNC |
|
|
165 | db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = &PL_sv_undef) |
103 | 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) |
166 | 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) |
104 | flags: FREELIST_ONLY FREE_SPACE |
167 | flags: FREELIST_ONLY FREE_SPACE |
105 | db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
168 | db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
106 | db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef) |
169 | db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef) |
107 | db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
170 | db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
108 | flags: APPEND NODUPDATA NOOVERWRITE |
171 | flags: APPEND NODUPDATA NOOVERWRITE |
|
|
172 | db_exists (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0) (v4.6) |
109 | db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
173 | db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
110 | flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW |
174 | flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW |
111 | db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
175 | db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
112 | flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW |
176 | flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW |
113 | db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) |
177 | db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) |
… | |
… | |
165 | |
229 | |
166 | You can use the "$txn->failed" method to check wether a transaction has |
230 | You can use the "$txn->failed" method to check wether a transaction has |
167 | failed in this way and abort further processing (excluding |
231 | failed in this way and abort further processing (excluding |
168 | "db_txn_finish"). |
232 | "db_txn_finish"). |
169 | |
233 | |
170 | DB_ENV/database environment methods |
234 | DB_ENV/database environment methods |
171 | Methods available on DB_ENV/$env handles: |
235 | Methods available on DB_ENV/$env handles: |
172 | |
236 | |
173 | DESTROY (DB_ENV_ornull *env) |
237 | DESTROY (DB_ENV_ornull *env) |
174 | CODE: |
238 | CODE: |
175 | if (env) |
239 | if (env) |
… | |
… | |
178 | $int = $env->set_data_dir (const char *dir) |
242 | $int = $env->set_data_dir (const char *dir) |
179 | $int = $env->set_tmp_dir (const char *dir) |
243 | $int = $env->set_tmp_dir (const char *dir) |
180 | $int = $env->set_lg_dir (const char *dir) |
244 | $int = $env->set_lg_dir (const char *dir) |
181 | $int = $env->set_shm_key (long shm_key) |
245 | $int = $env->set_shm_key (long shm_key) |
182 | $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) |
246 | $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) |
183 | $int = $env->set_flags (U32 flags, int onoff) |
247 | $int = $env->set_flags (U32 flags, int onoff = 1) |
|
|
248 | $int = $env->log_set_config (U32 flags, int onoff = 1) (v4.7) |
|
|
249 | $int = $env->set_intermediate_dir_mode (const char *modestring) (v4.7) |
184 | $env->set_errfile (FILE *errfile = 0) |
250 | $env->set_errfile (FILE *errfile = 0) |
185 | $env->set_msgfile (FILE *msgfile = 0) |
251 | $env->set_msgfile (FILE *msgfile = 0) |
186 | $int = $env->set_verbose (U32 which, int onoff = 1) |
252 | $int = $env->set_verbose (U32 which, int onoff = 1) |
187 | $int = $env->set_encrypt (const char *password, U32 flags = 0) |
253 | $int = $env->set_encrypt (const char *password, U32 flags = 0) |
188 | $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT) |
254 | $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT) |
… | |
… | |
193 | $int = $env->set_lk_max_lockers (U32 max) |
259 | $int = $env->set_lk_max_lockers (U32 max) |
194 | $int = $env->set_lk_max_locks (U32 max) |
260 | $int = $env->set_lk_max_locks (U32 max) |
195 | $int = $env->set_lk_max_objects (U32 max) |
261 | $int = $env->set_lk_max_objects (U32 max) |
196 | $int = $env->set_lg_bsize (U32 max) |
262 | $int = $env->set_lg_bsize (U32 max) |
197 | $int = $env->set_lg_max (U32 max) |
263 | $int = $env->set_lg_max (U32 max) |
|
|
264 | $int = $env->mutex_set_increment (U32 increment) |
|
|
265 | $int = $env->mutex_set_tas_spins (U32 tas_spins) |
|
|
266 | $int = $env->mutex_set_max (U32 max) |
|
|
267 | $int = $env->mutex_set_align (U32 align) |
198 | |
268 | |
199 | $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) |
269 | $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) |
200 | flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC |
270 | flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC |
|
|
271 | $txn = $env->cdsgroup_begin; (v4.5) |
201 | |
272 | |
202 | Example: |
273 | Example: |
203 | use AnyEvent; |
274 | use AnyEvent; |
204 | use BDB; |
275 | use BDB; |
205 | |
276 | |
… | |
… | |
217 | BDB::INIT_LOCK | BDB::INIT_LOG | BDB::INIT_MPOOL | BDB::INIT_TXN | BDB::RECOVER | BDB::USE_ENVIRON | BDB::CREATE, |
288 | BDB::INIT_LOCK | BDB::INIT_LOG | BDB::INIT_MPOOL | BDB::INIT_TXN | BDB::RECOVER | BDB::USE_ENVIRON | BDB::CREATE, |
218 | 0600; |
289 | 0600; |
219 | |
290 | |
220 | $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); |
291 | $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); |
221 | |
292 | |
222 | DB/database methods |
293 | DB/database methods |
223 | Methods available on DB/$db handles: |
294 | Methods available on DB/$db handles: |
224 | |
295 | |
225 | DESTROY (DB_ornull *db) |
296 | DESTROY (DB_ornull *db) |
226 | CODE: |
297 | CODE: |
227 | if (db) |
298 | if (db) |
… | |
… | |
267 | |
338 | |
268 | db_del $db, undef, "key $_" for 1..1000; |
339 | db_del $db, undef, "key $_" for 1..1000; |
269 | |
340 | |
270 | db_sync $db; |
341 | db_sync $db; |
271 | |
342 | |
272 | DB_TXN/transaction methods |
343 | DB_TXN/transaction methods |
273 | Methods available on DB_TXN/$txn handles: |
344 | Methods available on DB_TXN/$txn handles: |
274 | |
345 | |
275 | DESTROY (DB_TXN_ornull *txn) |
346 | DESTROY (DB_TXN_ornull *txn) |
276 | CODE: |
347 | CODE: |
277 | if (txn) |
348 | if (txn) |
… | |
… | |
281 | flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT |
352 | flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT |
282 | |
353 | |
283 | $bool = $txn->failed |
354 | $bool = $txn->failed |
284 | # see db_txn_finish documentation, above |
355 | # see db_txn_finish documentation, above |
285 | |
356 | |
286 | DBC/cursor methods |
357 | DBC/cursor methods |
287 | Methods available on DBC/$dbc handles: |
358 | Methods available on DBC/$dbc handles: |
288 | |
359 | |
289 | DESTROY (DBC_ornull *dbc) |
360 | DESTROY (DBC_ornull *dbc) |
290 | CODE: |
361 | CODE: |
291 | if (dbc) |
362 | if (dbc) |
292 | dbc->c_close (dbc); |
363 | dbc->c_close (dbc); |
|
|
364 | |
|
|
365 | $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6) |
293 | |
366 | |
294 | Example: |
367 | Example: |
295 | my $c = $db->cursor; |
368 | my $c = $db->cursor; |
296 | |
369 | |
297 | for (;;) { |
370 | for (;;) { |
… | |
… | |
300 | last if $!; |
373 | last if $!; |
301 | } |
374 | } |
302 | |
375 | |
303 | db_c_close $c; |
376 | db_c_close $c; |
304 | |
377 | |
305 | DB_SEQUENCE/sequence methods |
378 | DB_SEQUENCE/sequence methods |
306 | Methods available on DB_SEQUENCE/$seq handles: |
379 | Methods available on DB_SEQUENCE/$seq handles: |
307 | |
380 | |
308 | DESTROY (DB_SEQUENCE_ornull *seq) |
381 | DESTROY (DB_SEQUENCE_ornull *seq) |
309 | CODE: |
382 | CODE: |
310 | if (seq) |
383 | if (seq) |
… | |
… | |
316 | flags: SEQ_DEC SEQ_INC SEQ_WRAP |
389 | flags: SEQ_DEC SEQ_INC SEQ_WRAP |
317 | $int = $seq->set_range (db_seq_t min, db_seq_t max) |
390 | $int = $seq->set_range (db_seq_t min, db_seq_t max) |
318 | |
391 | |
319 | Example: |
392 | Example: |
320 | my $seq = $db->sequence; |
393 | my $seq = $db->sequence; |
321 | |
394 | |
322 | db_sequence_open $seq, undef, "seq", BDB::CREATE; |
395 | db_sequence_open $seq, undef, "seq", BDB::CREATE; |
323 | db_sequence_get $seq, undef, 1, my $value; |
396 | db_sequence_get $seq, undef, 1, my $value; |
324 | |
397 | |
325 | SUPPORT FUNCTIONS |
398 | SUPPORT FUNCTIONS |
326 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
399 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
|
|
400 | $msg = BDB::strerror [$errno] |
|
|
401 | Returns the string corresponding to the given errno value. If no |
|
|
402 | argument is given, use $!. |
|
|
403 | |
|
|
404 | Note that the BDB module also patches the $! variable directly, so |
|
|
405 | you should be able to get a bdb error string by simply stringifying |
|
|
406 | $!. |
|
|
407 | |
327 | $fileno = BDB::poll_fileno |
408 | $fileno = BDB::poll_fileno |
328 | Return the *request result pipe file descriptor*. This filehandle |
409 | Return the *request result pipe file descriptor*. This filehandle |
329 | must be polled for reading by some mechanism outside this module |
410 | must be polled for reading by some mechanism outside this module |
330 | (e.g. Event or select, see below or the SYNOPSIS). If the pipe |
411 | (e.g. Event or select, see below or the SYNOPSIS). If the pipe |
331 | becomes readable you have to call "poll_cb" to check the results. |
412 | becomes readable you have to call "poll_cb" to check the results. |
… | |
… | |
367 | interactiveness when perl is not fast enough to process all requests |
448 | interactiveness when perl is not fast enough to process all requests |
368 | in time. |
449 | in time. |
369 | |
450 | |
370 | For interactive programs, values such as 0.01 to 0.1 should be fine. |
451 | For interactive programs, values such as 0.01 to 0.1 should be fine. |
371 | |
452 | |
372 | Example: Install an Event watcher that automatically calls |
453 | Example: Install an EV watcher that automatically calls BDB::poll_cb |
373 | BDB::poll_cb with low priority, to ensure that other parts of the |
454 | with low priority, to ensure that other parts of the program get the |
374 | program get the CPU sometimes even under high AIO load. |
455 | CPU sometimes even under high load. |
375 | |
456 | |
376 | # try not to spend much more than 0.1s in poll_cb |
457 | # try not to spend much more than 0.1s in poll_cb |
377 | BDB::max_poll_time 0.1; |
458 | BDB::max_poll_time 0.1; |
378 | |
459 | |
379 | # use a low priority so other tasks have priority |
460 | my $bdb_poll = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb); |
380 | Event->io (fd => BDB::poll_fileno, |
|
|
381 | poll => 'r', nice => 1, |
|
|
382 | cb => &BDB::poll_cb); |
|
|
383 | |
461 | |
384 | BDB::poll_wait |
462 | BDB::poll_wait |
385 | If there are any outstanding requests and none of them in the result |
463 | If there are any outstanding requests and none of them in the result |
386 | phase, wait till the result filehandle becomes ready for reading |
464 | phase, wait till the result filehandle becomes ready for reading |
387 | (simply does a "select" on the filehandle. This is useful if you |
465 | (simply does a "select" on the filehandle. This is useful if you |
… | |
… | |
396 | equivalent to: |
474 | equivalent to: |
397 | |
475 | |
398 | BDB::poll_wait, BDB::poll_cb |
476 | BDB::poll_wait, BDB::poll_cb |
399 | |
477 | |
400 | BDB::flush |
478 | BDB::flush |
401 | Wait till all outstanding AIO requests have been handled. |
479 | Wait till all outstanding BDB requests have been handled. |
402 | |
480 | |
403 | Strictly equivalent to: |
481 | Strictly equivalent to: |
404 | |
482 | |
405 | BDB::poll_wait, BDB::poll_cb |
483 | BDB::poll_wait, BDB::poll_cb |
406 | while BDB::nreqs; |
484 | while BDB::nreqs; |
407 | |
485 | |
|
|
486 | VERSION CHECKING |
|
|
487 | BerkeleyDB comes in various versions, many of them have minor |
|
|
488 | incompatibilities. This means that traditional "at least version x.x" |
|
|
489 | checks are often not sufficient. |
|
|
490 | |
|
|
491 | Example: set the log_autoremove option in a way compatible with <v4.7 |
|
|
492 | and v4.7. Note the use of & on the constants to avoid triggering a |
|
|
493 | compiletime bug when the symbol isn't available. |
|
|
494 | |
|
|
495 | $DB_ENV->set_flags (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7; |
|
|
496 | $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7; |
|
|
497 | |
|
|
498 | BDB::VERSION |
|
|
499 | The "BDB::VERSION" function, when called without arguments, returns |
|
|
500 | the Berkeley DB version as a v-string (usually with 3 components). |
|
|
501 | You should use "lt" and "ge" operators exclusively to make |
|
|
502 | comparisons. |
|
|
503 | |
|
|
504 | Example: check for at least version 4.7. |
|
|
505 | |
|
|
506 | BDB::VERSION ge v4.7 or die; |
|
|
507 | |
|
|
508 | BDB::VERSION min-version |
|
|
509 | Returns true if the BDB version is at least the given version |
|
|
510 | (specified as a v-string), false otherwise. |
|
|
511 | |
|
|
512 | Example: check for at least version 4.5. |
|
|
513 | |
|
|
514 | BDB::VERSION v4.7 or die; |
|
|
515 | |
|
|
516 | BDB::VERSION min-version, max-version |
|
|
517 | Returns true of the BDB version is at least version "min-version" |
|
|
518 | (specify "undef" or "v0" for any minimum version) and less then |
|
|
519 | "max-version". |
|
|
520 | |
|
|
521 | Example: check wether version is strictly less then v4.7. |
|
|
522 | |
|
|
523 | BDB::VERSION v0, v4.7 |
|
|
524 | or die "version 4.7 is not yet supported"; |
|
|
525 | |
408 | CONTROLLING THE NUMBER OF THREADS |
526 | CONTROLLING THE NUMBER OF THREADS |
409 | BDB::min_parallel $nthreads |
527 | BDB::min_parallel $nthreads |
410 | Set the minimum number of AIO threads to $nthreads. The current |
528 | Set the minimum number of BDB threads to $nthreads. The current |
411 | default is 8, which means eight asynchronous operations can execute |
529 | default is 8, which means eight asynchronous operations can execute |
412 | concurrently at any one time (the number of outstanding requests, |
530 | concurrently at any one time (the number of outstanding requests, |
413 | however, is unlimited). |
531 | however, is unlimited). |
414 | |
532 | |
415 | BDB starts threads only on demand, when an AIO request is queued and |
533 | BDB starts threads only on demand, when an BDB request is queued and |
416 | no free thread exists. Please note that queueing up a hundred |
534 | no free thread exists. Please note that queueing up a hundred |
417 | requests can create demand for a hundred threads, even if it turns |
535 | requests can create demand for a hundred threads, even if it turns |
418 | out that everything is in the cache and could have been processed |
536 | out that everything is in the cache and could have been processed |
419 | faster by a single thread. |
537 | faster by a single thread. |
420 | |
538 | |
… | |
… | |
426 | Under most circumstances you don't need to call this function, as |
544 | Under most circumstances you don't need to call this function, as |
427 | the module selects a default that is suitable for low to moderate |
545 | the module selects a default that is suitable for low to moderate |
428 | load. |
546 | load. |
429 | |
547 | |
430 | BDB::max_parallel $nthreads |
548 | BDB::max_parallel $nthreads |
431 | Sets the maximum number of AIO threads to $nthreads. If more than |
549 | Sets the maximum number of BDB threads to $nthreads. If more than |
432 | the specified number of threads are currently running, this function |
550 | the specified number of threads are currently running, this function |
433 | kills them. This function blocks until the limit is reached. |
551 | kills them. This function blocks until the limit is reached. |
434 | |
552 | |
435 | While $nthreads are zero, aio requests get queued but not executed |
553 | While $nthreads are zero, aio requests get queued but not executed |
436 | until the number of threads has been increased again. |
554 | until the number of threads has been increased again. |
… | |
… | |
472 | You can still queue as many requests as you want. Therefore, |
590 | You can still queue as many requests as you want. Therefore, |
473 | "max_oustsanding" is mainly useful in simple scripts (with low |
591 | "max_oustsanding" is mainly useful in simple scripts (with low |
474 | values) or as a stop gap to shield against fatal memory overflow |
592 | values) or as a stop gap to shield against fatal memory overflow |
475 | (with large values). |
593 | (with large values). |
476 | |
594 | |
477 | BDB::set_sync_prepare $cb |
595 | $old_cb = BDB::set_sync_prepare $cb |
478 | Sets a callback that is called whenever a request is created without |
596 | Sets a callback that is called whenever a request is created without |
479 | an explicit callback. It has to return two code references. The |
597 | an explicit callback. It has to return two code references. The |
480 | first is used as the request callback, and the second is called to |
598 | first is used as the request callback (it should save the return |
481 | wait until the first callback has been called. The default |
599 | status), and the second is called to wait until the first callback |
482 | implementation works like this: |
600 | has been called (it must set $! to the return status). |
|
|
601 | |
|
|
602 | This mechanism can be used to include BDB into other event |
|
|
603 | mechanisms, such as Coro::BDB. |
|
|
604 | |
|
|
605 | To allow other, callback-based, events to be executed while |
|
|
606 | callback-less ones are run, you could use this sync prepare |
|
|
607 | function: |
483 | |
608 | |
484 | sub { |
609 | sub { |
485 | my $status; |
610 | my $status; |
486 | ( |
611 | ( |
487 | sub { $status = $! }, |
612 | sub { $status = $! }, |
488 | sub { BDB::poll while !defined $status; $! = $status }, |
613 | sub { BDB::poll while !defined $status; $! = $status }, |
489 | ) |
614 | ) |
490 | } |
615 | } |
491 | |
616 | |
|
|
617 | It works by polling for results till the request has finished and |
|
|
618 | then sets $! to the return value. This means that if you don't use a |
|
|
619 | callback, BDB would simply fall back to synchronous operations. |
|
|
620 | |
|
|
621 | By default, or if the sync prepare function is set to "undef", is to |
|
|
622 | execute callback-less BDB requests in the foreground thread, setting |
|
|
623 | $! to the return value, without polling for other events. |
|
|
624 | |
492 | STATISTICAL INFORMATION |
625 | STATISTICAL INFORMATION |
493 | BDB::nreqs |
626 | BDB::nreqs |
494 | Returns the number of requests currently in the ready, execute or |
627 | Returns the number of requests currently in the ready, execute or |
495 | pending states (i.e. for which their callback has not been invoked |
628 | pending states (i.e. for which their callback has not been invoked |
496 | yet). |
629 | yet). |
497 | |
630 | |
… | |
… | |
506 | |
639 | |
507 | BDB::npending |
640 | BDB::npending |
508 | Returns the number of requests currently in the pending state |
641 | Returns the number of requests currently in the pending state |
509 | (executed, but not yet processed by poll_cb). |
642 | (executed, but not yet processed by poll_cb). |
510 | |
643 | |
|
|
644 | COMMON PITFALLS |
|
|
645 | Unexpected Crashes |
|
|
646 | Remember that, by default, BDB will execute requests in parallel, in |
|
|
647 | somewhat random order. That means that it is easy to run a "db_get" |
|
|
648 | request on thesa me database as a concurrent "db_close" request, leading |
|
|
649 | to a crash, silent data corruption, eventually the next world war on |
|
|
650 | terrorism. |
|
|
651 | |
|
|
652 | If you only ever use foreground requests (without a callback), this will |
|
|
653 | not be an issue. |
|
|
654 | |
|
|
655 | Unexpected Freezes or Deadlocks |
|
|
656 | Remember that, by default, BDB will execute requests in parallel, which |
|
|
657 | easily leads to deadlocks (even concurrent put's on the same database |
|
|
658 | can deadlock). |
|
|
659 | |
|
|
660 | You either need to run deadlock detection (and handle the resulting |
|
|
661 | errors), or make sure only one process ever updates the database, ine |
|
|
662 | one thread, e.g. by using only foreground requests (without a callback). |
|
|
663 | |
511 | FORK BEHAVIOUR |
664 | FORK BEHAVIOUR |
512 | This module should do "the right thing" when the process using it forks: |
665 | This module should do "the right thing" when the process using it forks: |
513 | |
666 | |
514 | Before the fork, IO::AIO enters a quiescent state where no requests can |
667 | Before the fork, BDB enters a quiescent state where no requests can be |
515 | be added in other threads and no results will be processed. After the |
668 | added in other threads and no results will be processed. After the fork |
516 | fork the parent simply leaves the quiescent state and continues |
669 | the parent simply leaves the quiescent state and continues |
517 | request/result processing, while the child frees the request/result |
670 | request/result processing, while the child frees the request/result |
518 | queue (so that the requests started before the fork will only be handled |
671 | queue (so that the requests started before the fork will only be handled |
519 | in the parent). Threads will be started on demand until the limit set in |
672 | in the parent). Threads will be started on demand until the limit set in |
520 | the parent process has been reached again. |
673 | the parent process has been reached again. |
521 | |
674 | |
522 | In short: the parent will, after a short pause, continue as if fork had |
675 | In short: the parent will, after a short pause, continue as if fork had |
523 | not been called, while the child will act as if IO::AIO has not been |
676 | not been called, while the child will act as if BDB has not been used |
524 | used yet. |
677 | yet. |
525 | |
678 | |
|
|
679 | Win32 note: there is no fork on win32, and perls emulation of it is too |
|
|
680 | broken to be supported, so do not use BDB in a windows pseudo-fork, |
|
|
681 | better yet, switch to a more capable platform. |
|
|
682 | |
526 | MEMORY USAGE |
683 | MEMORY USAGE |
527 | Per-request usage: |
684 | Per-request usage: |
528 | |
685 | |
529 | Each aio request uses - depending on your architecture - around 100-200 |
686 | Each aio request uses - depending on your architecture - around 100-200 |
530 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
687 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
531 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
688 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
… | |
… | |
539 | |
696 | |
540 | In the execution phase, some aio requests require more memory for |
697 | In the execution phase, some aio requests require more memory for |
541 | temporary buffers, and each thread requires a stack and other data |
698 | temporary buffers, and each thread requires a stack and other data |
542 | structures (usually around 16k-128k, depending on the OS). |
699 | structures (usually around 16k-128k, depending on the OS). |
543 | |
700 | |
|
|
701 | WIN32 FILENAMES/DATABASE NAME MESS |
|
|
702 | Perl on Win32 supports only ASCII filenames (the reason is that it |
|
|
703 | abuses an internal flag to store wether a filename is Unicode or ANSI, |
|
|
704 | but that flag is used for somethign else in the perl core, so there is |
|
|
705 | no way to detect wether a filename is ANSI or Unicode-encoded). The BDB |
|
|
706 | module tries to work around this issue by assuming that the filename is |
|
|
707 | an ANSI filename and BDB was built for unicode support. |
|
|
708 | |
544 | KNOWN BUGS |
709 | KNOWN BUGS |
545 | Known bugs will be fixed in the next release, except: |
710 | Known bugs will be fixed in the next release, except: |
546 | |
711 | |
547 | If you use a transaction in any request, and the request returns |
712 | If you use a transaction in any request, and the request returns |
548 | with an operating system error or DB_LOCK_NOTGRANTED, the internal |
713 | with an operating system error or DB_LOCK_NOTGRANTED, the internal |
549 | TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>, |
714 | TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>, |
550 | above. |
715 | above. |
551 | |
716 | |
552 | SEE ALSO |
717 | SEE ALSO |
553 | Coro::AIO. |
718 | AnyEvent::BDB (event loop integration), Coro::BDB (more natural syntax), |
|
|
719 | IO::AIO (nice to have). |
554 | |
720 | |
555 | AUTHOR |
721 | AUTHOR |
556 | Marc Lehmann <schmorp@schmorp.de> |
722 | Marc Lehmann <schmorp@schmorp.de> |
557 | http://home.schmorp.de/ |
723 | http://home.schmorp.de/ |
558 | |
724 | |