… | |
… | |
25 | db_sync $db; |
25 | db_sync $db; |
26 | |
26 | |
27 | # when you also use Coro, management is easy: |
27 | # when you also use Coro, management is easy: |
28 | use Coro::BDB; |
28 | use Coro::BDB; |
29 | |
29 | |
30 | # automatic result processing with AnyEvent: |
30 | # automatic event loop intergration with AnyEvent: |
31 | our $FH; open $FH, "<&=" . BDB::poll_fileno; |
31 | use AnyEvent::BDB; |
32 | our $WATCHER = AnyEvent->io (fh => $FH, poll => 'r', cb => \&BDB::poll_cb); |
|
|
33 | |
32 | |
34 | # automatic result processing with EV: |
33 | # automatic result processing with EV: |
35 | my $WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb; |
34 | my $WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb; |
36 | |
35 | |
37 | # with Glib: |
36 | # with Glib: |
… | |
… | |
87 | 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 |
88 | anymore (except possibly for the Perl object, but its connection to |
87 | anymore (except possibly for the Perl object, but its connection to |
89 | the actual aio request is severed and calling its methods will |
88 | the actual aio request is severed and calling its methods will |
90 | either do nothing or result in a runtime error). |
89 | either do nothing or result in a runtime error). |
91 | |
90 | |
92 | FILENAMES/DATABASE NAMES |
|
|
93 | The BDB expects "binary" filenames (octet strings) for pathnames on |
|
|
94 | POSIX systems, and "unicode" filenames (strings with characters |
|
|
95 | potentially >255) on Win32 (expecting a Unicode win32 build - win32 is a |
|
|
96 | total mess). |
|
|
97 | |
|
|
98 | BERKELEYDB FUNCTIONS |
91 | BERKELEYDB FUNCTIONS |
99 | 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 |
100 | object and never block. All the remaining functions take an optional |
93 | object and never block. All the remaining functions take an optional |
101 | callback as last argument. If it is missing, then the function will be |
94 | callback as last argument. If it is missing, then the function will be |
102 | executed synchronously. In both cases, $! will reflect the return value |
95 | executed synchronously. In both cases, $! will reflect the return value |
103 | of the function. |
96 | of the function. |
… | |
… | |
105 | BDB functions that cannot block (mostly functions that manipulate |
98 | BDB functions that cannot block (mostly functions that manipulate |
106 | 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 |
107 | is: if it's a method, it's not blocking, if it's a function, it takes a |
100 | is: if it's a method, it's not blocking, if it's a function, it takes a |
108 | callback as last argument. |
101 | callback as last argument. |
109 | |
102 | |
110 | In the following, $int signifies an integer return value, "octetstring" |
103 | In the following, $int signifies an integer return value, "bdb_filename" |
111 | 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 |
112 | >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 |
113 | is a floating point value. |
106 | value. |
114 | |
107 | |
115 | 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 |
116 | values), and the "SV *callback" is the optional callback function to |
109 | values). |
117 | call when the request is completed. |
|
|
118 | |
110 | |
119 | The various "DB_ENV" etc. arguments are handles return by |
111 | The various "DB_ENV" etc. arguments are handles return by |
120 | "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 |
121 | 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" |
122 | for them, resulting a NULL pointer on the C level. |
114 | for them, resulting a NULL pointer on the C level. |
123 | |
115 | |
|
|
116 | The "SV *callback" is the optional callback function to call when the |
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117 | request is completed. This last callback argument is special: the |
|
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118 | callback is simply the last argument passed. If there are "optional" |
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119 | arguments before the callback they can be left out. The callback itself |
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120 | can be left out or specified as "undef", in which case the function will |
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121 | be executed synchronously. |
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122 | |
|
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123 | For example, "db_env_txn_checkpoint" usually is called with all integer |
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124 | arguments zero. These can be left out, so all of these specify a call to |
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125 | "DB_ENV->txn_checkpoint", to be executed asynchronously with a callback |
|
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126 | to be called: |
|
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127 | |
|
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128 | db_env_txn_checkpoint $db_env, 0, 0, 0, sub { }; |
|
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129 | db_env_txn_checkpoint $db_env, 0, 0, sub { }; |
|
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130 | db_env_txn_checkpoint $db_env, sub { }; |
|
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131 | |
|
|
132 | While these all specify a call to "DB_ENV->txn_checkpoint" to be |
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133 | executed synchronously: |
|
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134 | |
|
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135 | db_env_txn_checkpoint $db_env, 0, 0, 0, undef; |
|
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136 | db_env_txn_checkpoint $db_env, 0, 0, 0; |
|
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137 | db_env_txn_checkpoint $db_env, 0; |
|
|
138 | |
124 | BDB functions |
139 | BDB functions |
125 | Functions in the BDB namespace, exported by default: |
140 | Functions in the BDB namespace, exported by default: |
126 | |
141 | |
127 | $env = db_env_create (U32 env_flags = 0) |
142 | $env = db_env_create (U32 env_flags = 0) |
128 | flags: RPCCLIENT |
143 | flags: RPCCLIENT |
129 | |
144 | |
130 | 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) |
131 | 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 |
132 | 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) |
133 | 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) |
134 | flags: FORCE |
149 | 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) |
150 | db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef) |
136 | 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 |
137 | 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) |
138 | 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) |
|
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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) |
139 | |
157 | |
140 | $db = db_create (DB_ENV *env = 0, U32 flags = 0) |
158 | $db = db_create (DB_ENV *env = 0, U32 flags = 0) |
141 | flags: XA_CREATE |
159 | flags: XA_CREATE |
142 | |
160 | |
143 | 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) |
144 | 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 |
145 | 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) |
146 | flags: DB_NOSYNC |
164 | flags: DB_NOSYNC |
147 | db_upgrade (DB *db, octetstring file, U32 flags = 0, SV *callback = &PL_sv_undef) |
165 | db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = &PL_sv_undef) |
148 | 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) |
149 | flags: FREELIST_ONLY FREE_SPACE |
167 | flags: FREELIST_ONLY FREE_SPACE |
150 | 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) |
151 | 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) |
152 | 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) |
153 | 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) |
154 | 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) |
155 | 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 |
156 | 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) |
157 | 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 |
158 | 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) |
… | |
… | |
210 | |
229 | |
211 | You can use the "$txn->failed" method to check wether a transaction has |
230 | You can use the "$txn->failed" method to check wether a transaction has |
212 | failed in this way and abort further processing (excluding |
231 | failed in this way and abort further processing (excluding |
213 | "db_txn_finish"). |
232 | "db_txn_finish"). |
214 | |
233 | |
215 | DB_ENV/database environment methods |
234 | DB_ENV/database environment methods |
216 | Methods available on DB_ENV/$env handles: |
235 | Methods available on DB_ENV/$env handles: |
217 | |
236 | |
218 | DESTROY (DB_ENV_ornull *env) |
237 | DESTROY (DB_ENV_ornull *env) |
219 | CODE: |
238 | CODE: |
220 | if (env) |
239 | if (env) |
… | |
… | |
223 | $int = $env->set_data_dir (const char *dir) |
242 | $int = $env->set_data_dir (const char *dir) |
224 | $int = $env->set_tmp_dir (const char *dir) |
243 | $int = $env->set_tmp_dir (const char *dir) |
225 | $int = $env->set_lg_dir (const char *dir) |
244 | $int = $env->set_lg_dir (const char *dir) |
226 | $int = $env->set_shm_key (long shm_key) |
245 | $int = $env->set_shm_key (long shm_key) |
227 | $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) |
246 | $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) |
228 | $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) |
229 | $env->set_errfile (FILE *errfile = 0) |
250 | $env->set_errfile (FILE *errfile = 0) |
230 | $env->set_msgfile (FILE *msgfile = 0) |
251 | $env->set_msgfile (FILE *msgfile = 0) |
231 | $int = $env->set_verbose (U32 which, int onoff = 1) |
252 | $int = $env->set_verbose (U32 which, int onoff = 1) |
232 | $int = $env->set_encrypt (const char *password, U32 flags = 0) |
253 | $int = $env->set_encrypt (const char *password, U32 flags = 0) |
233 | $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) |
… | |
… | |
245 | $int = $env->mutex_set_max (U32 max) |
266 | $int = $env->mutex_set_max (U32 max) |
246 | $int = $env->mutex_set_align (U32 align) |
267 | $int = $env->mutex_set_align (U32 align) |
247 | |
268 | |
248 | $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) |
249 | 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) |
250 | |
272 | |
251 | Example: |
273 | Example: |
252 | use AnyEvent; |
274 | use AnyEvent; |
253 | use BDB; |
275 | use BDB; |
254 | |
276 | |
… | |
… | |
266 | 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, |
267 | 0600; |
289 | 0600; |
268 | |
290 | |
269 | $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); |
291 | $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); |
270 | |
292 | |
271 | DB/database methods |
293 | DB/database methods |
272 | Methods available on DB/$db handles: |
294 | Methods available on DB/$db handles: |
273 | |
295 | |
274 | DESTROY (DB_ornull *db) |
296 | DESTROY (DB_ornull *db) |
275 | CODE: |
297 | CODE: |
276 | if (db) |
298 | if (db) |
… | |
… | |
316 | |
338 | |
317 | db_del $db, undef, "key $_" for 1..1000; |
339 | db_del $db, undef, "key $_" for 1..1000; |
318 | |
340 | |
319 | db_sync $db; |
341 | db_sync $db; |
320 | |
342 | |
321 | DB_TXN/transaction methods |
343 | DB_TXN/transaction methods |
322 | Methods available on DB_TXN/$txn handles: |
344 | Methods available on DB_TXN/$txn handles: |
323 | |
345 | |
324 | DESTROY (DB_TXN_ornull *txn) |
346 | DESTROY (DB_TXN_ornull *txn) |
325 | CODE: |
347 | CODE: |
326 | if (txn) |
348 | if (txn) |
… | |
… | |
330 | flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT |
352 | flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT |
331 | |
353 | |
332 | $bool = $txn->failed |
354 | $bool = $txn->failed |
333 | # see db_txn_finish documentation, above |
355 | # see db_txn_finish documentation, above |
334 | |
356 | |
335 | DBC/cursor methods |
357 | DBC/cursor methods |
336 | Methods available on DBC/$dbc handles: |
358 | Methods available on DBC/$dbc handles: |
337 | |
359 | |
338 | DESTROY (DBC_ornull *dbc) |
360 | DESTROY (DBC_ornull *dbc) |
339 | CODE: |
361 | CODE: |
340 | if (dbc) |
362 | if (dbc) |
341 | dbc->c_close (dbc); |
363 | dbc->c_close (dbc); |
342 | |
364 | |
343 | $int = $cursor->set_priority ($priority = PRIORITY_*) |
365 | $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6) |
344 | |
366 | |
345 | Example: |
367 | Example: |
346 | my $c = $db->cursor; |
368 | my $c = $db->cursor; |
347 | |
369 | |
348 | for (;;) { |
370 | for (;;) { |
… | |
… | |
351 | last if $!; |
373 | last if $!; |
352 | } |
374 | } |
353 | |
375 | |
354 | db_c_close $c; |
376 | db_c_close $c; |
355 | |
377 | |
356 | DB_SEQUENCE/sequence methods |
378 | DB_SEQUENCE/sequence methods |
357 | Methods available on DB_SEQUENCE/$seq handles: |
379 | Methods available on DB_SEQUENCE/$seq handles: |
358 | |
380 | |
359 | DESTROY (DB_SEQUENCE_ornull *seq) |
381 | DESTROY (DB_SEQUENCE_ornull *seq) |
360 | CODE: |
382 | CODE: |
361 | if (seq) |
383 | if (seq) |
… | |
… | |
371 | my $seq = $db->sequence; |
393 | my $seq = $db->sequence; |
372 | |
394 | |
373 | db_sequence_open $seq, undef, "seq", BDB::CREATE; |
395 | db_sequence_open $seq, undef, "seq", BDB::CREATE; |
374 | db_sequence_get $seq, undef, 1, my $value; |
396 | db_sequence_get $seq, undef, 1, my $value; |
375 | |
397 | |
376 | SUPPORT FUNCTIONS |
398 | SUPPORT FUNCTIONS |
377 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
399 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
378 | $msg = BDB::strerror [$errno] |
400 | $msg = BDB::strerror [$errno] |
379 | Returns the string corresponding to the given errno value. If no |
401 | Returns the string corresponding to the given errno value. If no |
380 | argument is given, use $!. |
402 | argument is given, use $!. |
381 | |
403 | |
382 | Note that the BDB module also patches the $! variable directly, so |
404 | Note that the BDB module also patches the $! variable directly, so |
… | |
… | |
459 | Strictly equivalent to: |
481 | Strictly equivalent to: |
460 | |
482 | |
461 | BDB::poll_wait, BDB::poll_cb |
483 | BDB::poll_wait, BDB::poll_cb |
462 | while BDB::nreqs; |
484 | while BDB::nreqs; |
463 | |
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". |
|
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520 | |
|
|
521 | Example: check wether version is strictly less then v4.7. |
|
|
522 | |
|
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523 | BDB::VERSION v0, v4.7 |
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|
524 | or die "version 4.7 is not yet supported"; |
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|
525 | |
464 | CONTROLLING THE NUMBER OF THREADS |
526 | CONTROLLING THE NUMBER OF THREADS |
465 | BDB::min_parallel $nthreads |
527 | BDB::min_parallel $nthreads |
466 | Set the minimum number of BDB threads to $nthreads. The current |
528 | Set the minimum number of BDB threads to $nthreads. The current |
467 | default is 8, which means eight asynchronous operations can execute |
529 | default is 8, which means eight asynchronous operations can execute |
468 | concurrently at any one time (the number of outstanding requests, |
530 | concurrently at any one time (the number of outstanding requests, |
469 | however, is unlimited). |
531 | however, is unlimited). |
… | |
… | |
528 | You can still queue as many requests as you want. Therefore, |
590 | You can still queue as many requests as you want. Therefore, |
529 | "max_oustsanding" is mainly useful in simple scripts (with low |
591 | "max_oustsanding" is mainly useful in simple scripts (with low |
530 | 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 |
531 | (with large values). |
593 | (with large values). |
532 | |
594 | |
533 | BDB::set_sync_prepare $cb |
595 | $old_cb = BDB::set_sync_prepare $cb |
534 | 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 |
535 | an explicit callback. It has to return two code references. The |
597 | an explicit callback. It has to return two code references. The |
536 | 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 |
537 | wait until the first callback has been called. The default |
599 | status), and the second is called to wait until the first callback |
538 | implementation works like this: |
600 | has been called (it must set $! to the return status). |
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601 | |
|
|
602 | This mechanism can be used to include BDB into other event |
|
|
603 | mechanisms, such as Coro::BDB. |
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|
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: |
539 | |
608 | |
540 | sub { |
609 | sub { |
541 | my $status; |
610 | my $status; |
542 | ( |
611 | ( |
543 | sub { $status = $! }, |
612 | sub { $status = $! }, |
544 | sub { BDB::poll while !defined $status; $! = $status }, |
613 | sub { BDB::poll while !defined $status; $! = $status }, |
545 | ) |
614 | ) |
546 | } |
615 | } |
547 | |
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 | |
548 | STATISTICAL INFORMATION |
625 | STATISTICAL INFORMATION |
549 | BDB::nreqs |
626 | BDB::nreqs |
550 | Returns the number of requests currently in the ready, execute or |
627 | Returns the number of requests currently in the ready, execute or |
551 | 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 |
552 | yet). |
629 | yet). |
553 | |
630 | |
… | |
… | |
562 | |
639 | |
563 | BDB::npending |
640 | BDB::npending |
564 | Returns the number of requests currently in the pending state |
641 | Returns the number of requests currently in the pending state |
565 | (executed, but not yet processed by poll_cb). |
642 | (executed, but not yet processed by poll_cb). |
566 | |
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 | |
567 | FORK BEHAVIOUR |
664 | FORK BEHAVIOUR |
568 | 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: |
569 | |
666 | |
570 | Before the fork, BDB enters a quiescent state where no requests can be |
667 | Before the fork, BDB enters a quiescent state where no requests can be |
571 | added in other threads and no results will be processed. After the fork |
668 | added in other threads and no results will be processed. After the fork |
572 | the parent simply leaves the quiescent state and continues |
669 | the parent simply leaves the quiescent state and continues |
… | |
… | |
581 | |
678 | |
582 | Win32 note: there is no fork on win32, and perls emulation of it is too |
679 | Win32 note: there is no fork on win32, and perls emulation of it is too |
583 | broken to be supported, so do not use BDB in a windows pseudo-fork, |
680 | broken to be supported, so do not use BDB in a windows pseudo-fork, |
584 | better yet, switch to a more capable platform. |
681 | better yet, switch to a more capable platform. |
585 | |
682 | |
586 | MEMORY USAGE |
683 | MEMORY USAGE |
587 | Per-request usage: |
684 | Per-request usage: |
588 | |
685 | |
589 | Each aio request uses - depending on your architecture - around 100-200 |
686 | Each aio request uses - depending on your architecture - around 100-200 |
590 | 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 |
591 | 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 |
… | |
… | |
599 | |
696 | |
600 | In the execution phase, some aio requests require more memory for |
697 | In the execution phase, some aio requests require more memory for |
601 | temporary buffers, and each thread requires a stack and other data |
698 | temporary buffers, and each thread requires a stack and other data |
602 | structures (usually around 16k-128k, depending on the OS). |
699 | structures (usually around 16k-128k, depending on the OS). |
603 | |
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 | |
604 | KNOWN BUGS |
709 | KNOWN BUGS |
605 | Known bugs will be fixed in the next release, except: |
710 | Known bugs will be fixed in the next release, except: |
606 | |
711 | |
607 | 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 |
608 | with an operating system error or DB_LOCK_NOTGRANTED, the internal |
713 | with an operating system error or DB_LOCK_NOTGRANTED, the internal |
609 | 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>, |
610 | above. |
715 | above. |
611 | |
716 | |
612 | SEE ALSO |
717 | SEE ALSO |
613 | Coro::BDB, IO::AIO. |
718 | AnyEvent::BDB (event loop integration), Coro::BDB (more natural syntax), |
|
|
719 | IO::AIO (nice to have). |
614 | |
720 | |
615 | AUTHOR |
721 | AUTHOR |
616 | Marc Lehmann <schmorp@schmorp.de> |
722 | Marc Lehmann <schmorp@schmorp.de> |
617 | http://home.schmorp.de/ |
723 | http://home.schmorp.de/ |
618 | |
724 | |