… | |
… | |
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 event loop intergration with AnyEvent: |
30 | # automatic event loop integration with AnyEvent: |
31 | use AnyEvent::BDB; |
31 | use AnyEvent::BDB; |
32 | |
32 | |
33 | # automatic result processing with EV: |
33 | # automatic result processing with EV: |
34 | 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; |
35 | |
35 | |
… | |
… | |
86 | 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 |
87 | anymore (except possibly for the Perl object, but its connection to |
87 | anymore (except possibly for the Perl object, but its connection to |
88 | the actual aio request is severed and calling its methods will |
88 | the actual aio request is severed and calling its methods will |
89 | either do nothing or result in a runtime error). |
89 | either do nothing or result in a runtime error). |
90 | |
90 | |
91 | WIN32 FILENAMES/DATABASE NAME MESS |
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92 | Perl on Win32 supports only ASCII filenames (the reason is that it |
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93 | abuses an internal flag to store wether a filename is Unicode or ANSI, |
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94 | but that flag is used for somethign else in the perl core, so there is |
|
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95 | no way to detect wether a filename is ANSI or Unicode-encoded). The BDB |
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96 | module tries to work around this issue by assuming that the filename is |
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97 | an ANSI filename and BDB was built for unicode support. |
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98 | |
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99 | BERKELEYDB FUNCTIONS |
91 | BERKELEYDB FUNCTIONS |
100 | 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 |
101 | object and never block. All the remaining functions take an optional |
93 | object and never block. All the remaining functions take an optional |
102 | 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 |
103 | executed synchronously. In both cases, $! will reflect the return value |
95 | executed synchronously. In both cases, $! will reflect the return value |
104 | of the function. |
96 | of the function. |
… | |
… | |
142 | |
134 | |
143 | db_env_txn_checkpoint $db_env, 0, 0, 0, undef; |
135 | db_env_txn_checkpoint $db_env, 0, 0, 0, undef; |
144 | db_env_txn_checkpoint $db_env, 0, 0, 0; |
136 | db_env_txn_checkpoint $db_env, 0, 0, 0; |
145 | db_env_txn_checkpoint $db_env, 0; |
137 | db_env_txn_checkpoint $db_env, 0; |
146 | |
138 | |
147 | BDB functions |
139 | BDB functions |
148 | Functions in the BDB namespace, exported by default: |
140 | Functions in the BDB namespace, exported by default: |
149 | |
141 | |
150 | $env = db_env_create (U32 env_flags = 0) |
142 | $env = db_env_create (U32 env_flags = 0) |
151 | flags: RPCCLIENT |
143 | flags: RPCCLIENT |
152 | |
144 | |
153 | db_env_open (DB_ENV *env, bdb_filename 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 = 0) |
154 | 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 |
155 | 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 = 0) |
156 | 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 = 0) |
157 | flags: FORCE |
149 | flags: FORCE |
158 | 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 = 0) |
159 | 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 |
160 | 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 = 0) |
161 | 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 = 0) |
162 | db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 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 = 0) |
163 | 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) |
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 = 0) |
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156 | db_env_log_archive (DB_ENV *env, SV *listp, U32 flags = 0, SV *callback = 0) |
164 | |
157 | |
165 | $db = db_create (DB_ENV *env = 0, U32 flags = 0) |
158 | $db = db_create (DB_ENV *env = 0, U32 flags = 0) |
166 | flags: XA_CREATE |
159 | flags: XA_CREATE |
167 | |
160 | |
168 | 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) |
161 | db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = 0) |
169 | 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 |
170 | db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
163 | db_close (DB *db, U32 flags = 0, SV *callback = 0) |
171 | flags: DB_NOSYNC |
164 | flags: DB_NOSYNC |
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165 | db_verify (DB *db, bdb_filename file, bdb_filename database = 0, SV *dummy = 0, U32 flags = 0, SV *callback = 0) |
172 | db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = &PL_sv_undef) |
166 | db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = 0) |
173 | 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) |
167 | db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = 0) |
174 | flags: FREELIST_ONLY FREE_SPACE |
168 | flags: FREELIST_ONLY FREE_SPACE |
175 | db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
169 | db_sync (DB *db, U32 flags = 0, SV *callback = 0) |
176 | db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef) |
170 | db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = 0) |
177 | db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
171 | db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = 0) |
178 | flags: APPEND NODUPDATA NOOVERWRITE |
172 | flags: APPEND NODUPDATA NOOVERWRITE |
179 | db_exists (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0) (v4.6) |
173 | db_exists (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0) (v4.6) |
180 | db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
174 | db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = 0) |
181 | flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW |
175 | flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW |
182 | db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
176 | db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0) |
183 | flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW |
177 | flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW |
184 | db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) |
178 | db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0) |
185 | db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) |
179 | db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = 0) |
186 | flags: TXN_NOSYNC TXN_SYNC |
180 | flags: TXN_NOSYNC TXN_SYNC |
187 | db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef) |
181 | db_txn_abort (DB_TXN *txn, SV *callback = 0) |
188 | |
182 | |
189 | db_c_close (DBC *dbc, SV *callback = &PL_sv_undef) |
183 | db_c_close (DBC *dbc, SV *callback = 0) |
190 | db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = &PL_sv_undef) |
184 | db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = 0) |
191 | db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
185 | db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0) |
192 | flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA |
186 | flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA |
193 | db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
187 | db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0) |
194 | 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 |
188 | 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 |
195 | db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
189 | db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0) |
196 | db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef) |
190 | db_c_del (DBC *dbc, U32 flags = 0, SV *callback = 0) |
197 | |
191 | |
198 | db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) |
192 | db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = 0) |
199 | flags: CREATE EXCL |
193 | flags: CREATE EXCL |
200 | db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef) |
194 | db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = 0) |
201 | 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) |
195 | db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = 0) |
202 | flags: TXN_NOSYNC |
196 | flags: TXN_NOSYNC |
203 | db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) |
197 | db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = 0) |
204 | flags: TXN_NOSYNC |
198 | flags: TXN_NOSYNC |
205 | |
199 | |
206 | db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) |
200 | db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = 0) |
207 | This is not actually a Berkeley DB function but a BDB module extension. |
201 | This is not actually a Berkeley DB function but a BDB module extension. |
208 | The background for this exytension is: It is very annoying to have to |
202 | The background for this exytension is: It is very annoying to have to |
209 | check every single BDB function for error returns and provide a codepath |
203 | check every single BDB function for error returns and provide a codepath |
210 | out of your transaction. While the BDB module still makes this possible, |
204 | out of your transaction. While the BDB module still makes this possible, |
211 | it contains the following extensions: |
205 | it contains the following extensions: |
… | |
… | |
236 | |
230 | |
237 | You can use the "$txn->failed" method to check wether a transaction has |
231 | You can use the "$txn->failed" method to check wether a transaction has |
238 | failed in this way and abort further processing (excluding |
232 | failed in this way and abort further processing (excluding |
239 | "db_txn_finish"). |
233 | "db_txn_finish"). |
240 | |
234 | |
241 | DB_ENV/database environment methods |
235 | DB_ENV/database environment methods |
242 | Methods available on DB_ENV/$env handles: |
236 | Methods available on DB_ENV/$env handles: |
243 | |
237 | |
244 | DESTROY (DB_ENV_ornull *env) |
238 | DESTROY (DB_ENV_ornull *env) |
245 | CODE: |
239 | CODE: |
246 | if (env) |
240 | if (env) |
… | |
… | |
295 | BDB::INIT_LOCK | BDB::INIT_LOG | BDB::INIT_MPOOL | BDB::INIT_TXN | BDB::RECOVER | BDB::USE_ENVIRON | BDB::CREATE, |
289 | BDB::INIT_LOCK | BDB::INIT_LOG | BDB::INIT_MPOOL | BDB::INIT_TXN | BDB::RECOVER | BDB::USE_ENVIRON | BDB::CREATE, |
296 | 0600; |
290 | 0600; |
297 | |
291 | |
298 | $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); |
292 | $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); |
299 | |
293 | |
300 | DB/database methods |
294 | DB/database methods |
301 | Methods available on DB/$db handles: |
295 | Methods available on DB/$db handles: |
302 | |
296 | |
303 | DESTROY (DB_ornull *db) |
297 | DESTROY (DB_ornull *db) |
304 | CODE: |
298 | CODE: |
305 | if (db) |
299 | if (db) |
… | |
… | |
345 | |
339 | |
346 | db_del $db, undef, "key $_" for 1..1000; |
340 | db_del $db, undef, "key $_" for 1..1000; |
347 | |
341 | |
348 | db_sync $db; |
342 | db_sync $db; |
349 | |
343 | |
350 | DB_TXN/transaction methods |
344 | DB_TXN/transaction methods |
351 | Methods available on DB_TXN/$txn handles: |
345 | Methods available on DB_TXN/$txn handles: |
352 | |
346 | |
353 | DESTROY (DB_TXN_ornull *txn) |
347 | DESTROY (DB_TXN_ornull *txn) |
354 | CODE: |
348 | CODE: |
355 | if (txn) |
349 | if (txn) |
… | |
… | |
359 | flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT |
353 | flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT |
360 | |
354 | |
361 | $bool = $txn->failed |
355 | $bool = $txn->failed |
362 | # see db_txn_finish documentation, above |
356 | # see db_txn_finish documentation, above |
363 | |
357 | |
364 | DBC/cursor methods |
358 | DBC/cursor methods |
365 | Methods available on DBC/$dbc handles: |
359 | Methods available on DBC/$dbc handles: |
366 | |
360 | |
367 | DESTROY (DBC_ornull *dbc) |
361 | DESTROY (DBC_ornull *dbc) |
368 | CODE: |
362 | CODE: |
369 | if (dbc) |
363 | if (dbc) |
… | |
… | |
380 | last if $!; |
374 | last if $!; |
381 | } |
375 | } |
382 | |
376 | |
383 | db_c_close $c; |
377 | db_c_close $c; |
384 | |
378 | |
385 | DB_SEQUENCE/sequence methods |
379 | DB_SEQUENCE/sequence methods |
386 | Methods available on DB_SEQUENCE/$seq handles: |
380 | Methods available on DB_SEQUENCE/$seq handles: |
387 | |
381 | |
388 | DESTROY (DB_SEQUENCE_ornull *seq) |
382 | DESTROY (DB_SEQUENCE_ornull *seq) |
389 | CODE: |
383 | CODE: |
390 | if (seq) |
384 | if (seq) |
… | |
… | |
396 | flags: SEQ_DEC SEQ_INC SEQ_WRAP |
390 | flags: SEQ_DEC SEQ_INC SEQ_WRAP |
397 | $int = $seq->set_range (db_seq_t min, db_seq_t max) |
391 | $int = $seq->set_range (db_seq_t min, db_seq_t max) |
398 | |
392 | |
399 | Example: |
393 | Example: |
400 | my $seq = $db->sequence; |
394 | my $seq = $db->sequence; |
401 | |
395 | |
402 | db_sequence_open $seq, undef, "seq", BDB::CREATE; |
396 | db_sequence_open $seq, undef, "seq", BDB::CREATE; |
403 | db_sequence_get $seq, undef, 1, my $value; |
397 | db_sequence_get $seq, undef, 1, my $value; |
404 | |
398 | |
405 | SUPPORT FUNCTIONS |
399 | SUPPORT FUNCTIONS |
406 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
400 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
407 | $msg = BDB::strerror [$errno] |
401 | $msg = BDB::strerror [$errno] |
408 | Returns the string corresponding to the given errno value. If no |
402 | Returns the string corresponding to the given errno value. If no |
409 | argument is given, use $!. |
403 | argument is given, use $!. |
410 | |
404 | |
411 | Note that the BDB module also patches the $! variable directly, so |
405 | Note that the BDB module also patches the $! variable directly, so |
… | |
… | |
488 | Strictly equivalent to: |
482 | Strictly equivalent to: |
489 | |
483 | |
490 | BDB::poll_wait, BDB::poll_cb |
484 | BDB::poll_wait, BDB::poll_cb |
491 | while BDB::nreqs; |
485 | while BDB::nreqs; |
492 | |
486 | |
493 | VERSION CHECKING |
487 | VERSION CHECKING |
494 | BerkeleyDB comes in various versions, many of them have minor |
488 | BerkeleyDB comes in various versions, many of them have minor |
495 | incompatibilities. This means that traditional "at least version x.x" |
489 | incompatibilities. This means that traditional "at least version x.x" |
496 | checks are often not sufficient. |
490 | checks are often not sufficient. |
497 | |
491 | |
498 | Example: set the log_autoremove option in a way compatible with <v4.7 |
492 | Example: set the log_autoremove option in a way compatible with <v4.7 |
… | |
… | |
528 | Example: check wether version is strictly less then v4.7. |
522 | Example: check wether version is strictly less then v4.7. |
529 | |
523 | |
530 | BDB::VERSION v0, v4.7 |
524 | BDB::VERSION v0, v4.7 |
531 | or die "version 4.7 is not yet supported"; |
525 | or die "version 4.7 is not yet supported"; |
532 | |
526 | |
533 | CONTROLLING THE NUMBER OF THREADS |
527 | CONTROLLING THE NUMBER OF THREADS |
534 | BDB::min_parallel $nthreads |
528 | BDB::min_parallel $nthreads |
535 | Set the minimum number of BDB threads to $nthreads. The current |
529 | Set the minimum number of BDB threads to $nthreads. The current |
536 | default is 8, which means eight asynchronous operations can execute |
530 | default is 8, which means eight asynchronous operations can execute |
537 | concurrently at any one time (the number of outstanding requests, |
531 | concurrently at any one time (the number of outstanding requests, |
538 | however, is unlimited). |
532 | however, is unlimited). |
… | |
… | |
627 | |
621 | |
628 | By default, or if the sync prepare function is set to "undef", is to |
622 | By default, or if the sync prepare function is set to "undef", is to |
629 | execute callback-less BDB requests in the foreground thread, setting |
623 | execute callback-less BDB requests in the foreground thread, setting |
630 | $! to the return value, without polling for other events. |
624 | $! to the return value, without polling for other events. |
631 | |
625 | |
632 | STATISTICAL INFORMATION |
626 | STATISTICAL INFORMATION |
633 | BDB::nreqs |
627 | BDB::nreqs |
634 | Returns the number of requests currently in the ready, execute or |
628 | Returns the number of requests currently in the ready, execute or |
635 | pending states (i.e. for which their callback has not been invoked |
629 | pending states (i.e. for which their callback has not been invoked |
636 | yet). |
630 | yet). |
637 | |
631 | |
… | |
… | |
646 | |
640 | |
647 | BDB::npending |
641 | BDB::npending |
648 | Returns the number of requests currently in the pending state |
642 | Returns the number of requests currently in the pending state |
649 | (executed, but not yet processed by poll_cb). |
643 | (executed, but not yet processed by poll_cb). |
650 | |
644 | |
|
|
645 | COMMON PITFALLS |
|
|
646 | Unexpected Crashes |
|
|
647 | Remember that, by default, BDB will execute requests in parallel, in |
|
|
648 | somewhat random order. That means that it is easy to run a "db_get" |
|
|
649 | request on the same database as a concurrent "db_close" request, leading |
|
|
650 | to a crash, silent data corruption, eventually the next world war on |
|
|
651 | terrorism. |
|
|
652 | |
|
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653 | If you only ever use foreground requests (without a callback), this will |
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654 | not be an issue (unless you use threads). |
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655 | |
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656 | Unexpected Freezes or Deadlocks |
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657 | Remember that, by default, BDB will execute requests in parallel, which |
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658 | easily leads to deadlocks (even concurrent put's on the same database |
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659 | can deadlock). |
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660 | |
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661 | You either need to run deadlock detection (and handle the resulting |
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662 | errors), or make sure only one process ever updates the database, ine |
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663 | one thread, e.g. by using only foreground requests (without a callback). |
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664 | |
651 | FORK BEHAVIOUR |
665 | FORK BEHAVIOUR |
652 | This module should do "the right thing" when the process using it forks: |
666 | This module should do "the right thing" when the process using it forks: |
653 | |
667 | |
654 | Before the fork, BDB enters a quiescent state where no requests can be |
668 | Before the fork, BDB enters a quiescent state where no requests can be |
655 | added in other threads and no results will be processed. After the fork |
669 | added in other threads and no results will be processed. After the fork |
656 | the parent simply leaves the quiescent state and continues |
670 | the parent simply leaves the quiescent state and continues |
… | |
… | |
665 | |
679 | |
666 | Win32 note: there is no fork on win32, and perls emulation of it is too |
680 | Win32 note: there is no fork on win32, and perls emulation of it is too |
667 | broken to be supported, so do not use BDB in a windows pseudo-fork, |
681 | broken to be supported, so do not use BDB in a windows pseudo-fork, |
668 | better yet, switch to a more capable platform. |
682 | better yet, switch to a more capable platform. |
669 | |
683 | |
670 | MEMORY USAGE |
684 | MEMORY USAGE |
671 | Per-request usage: |
685 | Per-request usage: |
672 | |
686 | |
673 | Each aio request uses - depending on your architecture - around 100-200 |
687 | Each aio request uses - depending on your architecture - around 100-200 |
674 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
688 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
675 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
689 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
… | |
… | |
683 | |
697 | |
684 | In the execution phase, some aio requests require more memory for |
698 | In the execution phase, some aio requests require more memory for |
685 | temporary buffers, and each thread requires a stack and other data |
699 | temporary buffers, and each thread requires a stack and other data |
686 | structures (usually around 16k-128k, depending on the OS). |
700 | structures (usually around 16k-128k, depending on the OS). |
687 | |
701 | |
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702 | WIN32 FILENAMES/DATABASE NAME MESS |
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703 | Perl on Win32 supports only ASCII filenames (the reason is that it |
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704 | abuses an internal flag to store wether a filename is Unicode or ANSI, |
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705 | but that flag is used for somethign else in the perl core, so there is |
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706 | no way to detect wether a filename is ANSI or Unicode-encoded). The BDB |
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707 | module tries to work around this issue by assuming that the filename is |
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708 | an ANSI filename and BDB was built for unicode support. |
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709 | |
688 | KNOWN BUGS |
710 | KNOWN BUGS |
689 | Known bugs will be fixed in the next release, except: |
711 | Known bugs will be fixed in the next release, except: |
690 | |
712 | |
691 | If you use a transaction in any request, and the request returns |
713 | If you use a transaction in any request, and the request returns |
692 | with an operating system error or DB_LOCK_NOTGRANTED, the internal |
714 | with an operating system error or DB_LOCK_NOTGRANTED, the internal |