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72 | use strict 'vars'; |
72 | use strict 'vars'; |
73 | |
73 | |
74 | use base 'Exporter'; |
74 | use base 'Exporter'; |
75 | |
75 | |
76 | BEGIN { |
76 | BEGIN { |
77 | our $VERSION = '1.0'; |
77 | our $VERSION = '1.2'; |
78 | |
78 | |
79 | our @BDB_REQ = qw( |
79 | our @BDB_REQ = qw( |
80 | db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect |
80 | db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect |
81 | db_env_memp_sync db_env_memp_trickle |
81 | db_env_memp_sync db_env_memp_trickle |
82 | db_open db_close db_compact db_sync db_put db_get db_pget db_del db_key_range |
82 | db_open db_close db_compact db_sync db_put db_get db_pget db_del db_key_range |
83 | db_txn_commit db_txn_abort |
83 | 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 |
84 | 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 |
85 | db_sequence_open db_sequence_close |
86 | db_sequence_get db_sequence_remove |
86 | db_sequence_get db_sequence_remove |
87 | ); |
87 | ); |
88 | our @EXPORT = (@BDB_REQ, qw(dbreq_pri dbreq_nice db_env_create db_create)); |
88 | our @EXPORT = (@BDB_REQ, qw(dbreq_pri dbreq_nice db_env_create db_create)); |
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177 | 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) |
177 | 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) |
178 | flags: TXN_NOSYNC |
178 | flags: TXN_NOSYNC |
179 | db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) |
179 | db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) |
180 | flags: TXN_NOSYNC |
180 | flags: TXN_NOSYNC |
181 | |
181 | |
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182 | =head4 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) |
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183 | |
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184 | This is not actually a Berkeley DB function but a BDB module |
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185 | extension. The background for this exytension is: It is very annoying to |
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186 | have to check every single BDB function for error returns and provide a |
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187 | codepath out of your transaction. While the BDB module still makes this |
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188 | possible, it contains the following extensions: |
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189 | |
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190 | When a transaction-protected function returns any operating system |
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191 | error (errno > 0), BDB will set the C<TXN_DEADLOCK> flag on the |
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192 | transaction. This flag is also set by Berkeley DB functions themselves |
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193 | when an operation fails with LOCK_DEADLOCK, and it causes all further |
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194 | operations on that transaction (including C<db_txn_commit>) to fail. |
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195 | |
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196 | The C<db_txn_finish> request will look at this flag, and, if it is set, |
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197 | will automatically call C<db_txn_abort> (setting errno to C<LOCK_DEADLOCK> |
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198 | if it isn't set to something else yet). If it isn't set, it will call |
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199 | C<db_txn_commit> and return the error normally. |
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200 | |
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201 | How to use this? Easy: just write your transaction normally: |
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202 | |
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203 | my $txn = $db_env->txn_begin; |
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204 | db_get $db, $txn, "key", my $data; |
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205 | db_put $db, $txn, "key", $data + 1 unless $! == BDB::NOTFOUND; |
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206 | db_txn_finish $txn; |
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207 | die "transaction failed" if $!; |
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208 | |
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209 | That is, handle only the expected errors. If something unexpected happens |
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210 | (EIO, LOCK_NOTGRANTED or a deadlock in either db_get or db_put), then the remaining |
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211 | requests (db_put in this case) will simply be skipped (they will fail with |
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212 | LOCK_DEADLOCK) and the transaction will be aborted. |
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213 | |
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214 | You can use the C<< $txn->failed >> method to check wether a transaction |
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215 | has failed in this way and abort further processing (excluding |
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216 | C<db_txn_finish>). |
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217 | |
182 | =head3 DB_ENV/database environment methods |
218 | =head3 DB_ENV/database environment methods |
183 | |
219 | |
184 | Methods available on DB_ENV/$env handles: |
220 | Methods available on DB_ENV/$env handles: |
185 | |
221 | |
186 | DESTROY (DB_ENV_ornull *env) |
222 | DESTROY (DB_ENV_ornull *env) |
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196 | $int = $env->set_flags (U32 flags, int onoff) |
232 | $int = $env->set_flags (U32 flags, int onoff) |
197 | $env->set_errfile (FILE *errfile = 0) |
233 | $env->set_errfile (FILE *errfile = 0) |
198 | $env->set_msgfile (FILE *msgfile = 0) |
234 | $env->set_msgfile (FILE *msgfile = 0) |
199 | $int = $env->set_verbose (U32 which, int onoff = 1) |
235 | $int = $env->set_verbose (U32 which, int onoff = 1) |
200 | $int = $env->set_encrypt (const char *password, U32 flags = 0) |
236 | $int = $env->set_encrypt (const char *password, U32 flags = 0) |
201 | $int = $env->set_timeout (NV timeout, U32 flags) |
237 | $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT) |
202 | $int = $env->set_mp_max_openfd (int maxopenfd); |
238 | $int = $env->set_mp_max_openfd (int maxopenfd); |
203 | $int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep); |
239 | $int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep); |
204 | $int = $env->set_mp_mmapsize (int mmapsize_mb) |
240 | $int = $env->set_mp_mmapsize (int mmapsize_mb) |
205 | $int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT) |
241 | $int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT) |
206 | $int = $env->set_lk_max_lockers (U32 max) |
242 | $int = $env->set_lk_max_lockers (U32 max) |
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294 | DESTROY (DB_TXN_ornull *txn) |
330 | DESTROY (DB_TXN_ornull *txn) |
295 | CODE: |
331 | CODE: |
296 | if (txn) |
332 | if (txn) |
297 | txn->abort (txn); |
333 | txn->abort (txn); |
298 | |
334 | |
299 | $int = $txn->set_timeout (NV timeout, U32 flags) |
335 | $int = $txn->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT) |
300 | flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT |
336 | flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT |
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337 | |
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338 | $bool = $txn->failed |
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339 | # see db_txn_finish documentation, above |
301 | |
340 | |
302 | |
341 | |
303 | =head3 DBC/cursor methods |
342 | =head3 DBC/cursor methods |
304 | |
343 | |
305 | Methods available on DBC/$dbc handles: |
344 | Methods available on DBC/$dbc handles: |
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396 | interactiveness when perl is not fast enough to process all requests in |
435 | interactiveness when perl is not fast enough to process all requests in |
397 | time. |
436 | time. |
398 | |
437 | |
399 | For interactive programs, values such as C<0.01> to C<0.1> should be fine. |
438 | For interactive programs, values such as C<0.01> to C<0.1> should be fine. |
400 | |
439 | |
401 | Example: Install an Event watcher that automatically calls |
440 | Example: Install an EV watcher that automatically calls |
402 | BDB::poll_cb with low priority, to ensure that other parts of the |
441 | BDB::poll_cb with low priority, to ensure that other parts of the |
403 | program get the CPU sometimes even under high AIO load. |
442 | program get the CPU sometimes even under high load. |
404 | |
443 | |
405 | # try not to spend much more than 0.1s in poll_cb |
444 | # try not to spend much more than 0.1s in poll_cb |
406 | BDB::max_poll_time 0.1; |
445 | BDB::max_poll_time 0.1; |
407 | |
446 | |
408 | # use a low priority so other tasks have priority |
447 | my $bdb_poll = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb); |
409 | Event->io (fd => BDB::poll_fileno, |
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410 | poll => 'r', nice => 1, |
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411 | cb => &BDB::poll_cb); |
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412 | |
448 | |
413 | =item BDB::poll_wait |
449 | =item BDB::poll_wait |
414 | |
450 | |
415 | If there are any outstanding requests and none of them in the result |
451 | If there are any outstanding requests and none of them in the result |
416 | phase, wait till the result filehandle becomes ready for reading (simply |
452 | phase, wait till the result filehandle becomes ready for reading (simply |
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428 | |
464 | |
429 | BDB::poll_wait, BDB::poll_cb |
465 | BDB::poll_wait, BDB::poll_cb |
430 | |
466 | |
431 | =item BDB::flush |
467 | =item BDB::flush |
432 | |
468 | |
433 | Wait till all outstanding AIO requests have been handled. |
469 | Wait till all outstanding BDB requests have been handled. |
434 | |
470 | |
435 | Strictly equivalent to: |
471 | Strictly equivalent to: |
436 | |
472 | |
437 | BDB::poll_wait, BDB::poll_cb |
473 | BDB::poll_wait, BDB::poll_cb |
438 | while BDB::nreqs; |
474 | while BDB::nreqs; |
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443 | |
479 | |
444 | =over 4 |
480 | =over 4 |
445 | |
481 | |
446 | =item BDB::min_parallel $nthreads |
482 | =item BDB::min_parallel $nthreads |
447 | |
483 | |
448 | Set the minimum number of AIO threads to C<$nthreads>. The current |
484 | Set the minimum number of BDB threads to C<$nthreads>. The current |
449 | default is C<8>, which means eight asynchronous operations can execute |
485 | default is C<8>, which means eight asynchronous operations can execute |
450 | concurrently at any one time (the number of outstanding requests, |
486 | concurrently at any one time (the number of outstanding requests, |
451 | however, is unlimited). |
487 | however, is unlimited). |
452 | |
488 | |
453 | BDB starts threads only on demand, when an AIO request is queued and |
489 | BDB starts threads only on demand, when an BDB request is queued and |
454 | no free thread exists. Please note that queueing up a hundred requests can |
490 | no free thread exists. Please note that queueing up a hundred requests can |
455 | create demand for a hundred threads, even if it turns out that everything |
491 | create demand for a hundred threads, even if it turns out that everything |
456 | is in the cache and could have been processed faster by a single thread. |
492 | is in the cache and could have been processed faster by a single thread. |
457 | |
493 | |
458 | It is recommended to keep the number of threads relatively low, as some |
494 | It is recommended to keep the number of threads relatively low, as some |
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463 | Under most circumstances you don't need to call this function, as the |
499 | Under most circumstances you don't need to call this function, as the |
464 | module selects a default that is suitable for low to moderate load. |
500 | module selects a default that is suitable for low to moderate load. |
465 | |
501 | |
466 | =item BDB::max_parallel $nthreads |
502 | =item BDB::max_parallel $nthreads |
467 | |
503 | |
468 | Sets the maximum number of AIO threads to C<$nthreads>. If more than the |
504 | Sets the maximum number of BDB threads to C<$nthreads>. If more than the |
469 | specified number of threads are currently running, this function kills |
505 | specified number of threads are currently running, this function kills |
470 | them. This function blocks until the limit is reached. |
506 | them. This function blocks until the limit is reached. |
471 | |
507 | |
472 | While C<$nthreads> are zero, aio requests get queued but not executed |
508 | While C<$nthreads> are zero, aio requests get queued but not executed |
473 | until the number of threads has been increased again. |
509 | until the number of threads has been increased again. |
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576 | |
612 | |
577 | =head2 FORK BEHAVIOUR |
613 | =head2 FORK BEHAVIOUR |
578 | |
614 | |
579 | This module should do "the right thing" when the process using it forks: |
615 | This module should do "the right thing" when the process using it forks: |
580 | |
616 | |
581 | Before the fork, IO::AIO enters a quiescent state where no requests |
617 | Before the fork, BDB enters a quiescent state where no requests |
582 | can be added in other threads and no results will be processed. After |
618 | can be added in other threads and no results will be processed. After |
583 | the fork the parent simply leaves the quiescent state and continues |
619 | the fork the parent simply leaves the quiescent state and continues |
584 | request/result processing, while the child frees the request/result queue |
620 | request/result processing, while the child frees the request/result queue |
585 | (so that the requests started before the fork will only be handled in the |
621 | (so that the requests started before the fork will only be handled in the |
586 | parent). Threads will be started on demand until the limit set in the |
622 | parent). Threads will be started on demand until the limit set in the |
587 | parent process has been reached again. |
623 | parent process has been reached again. |
588 | |
624 | |
589 | In short: the parent will, after a short pause, continue as if fork had |
625 | In short: the parent will, after a short pause, continue as if fork had |
590 | not been called, while the child will act as if IO::AIO has not been used |
626 | not been called, while the child will act as if BDB has not been used |
591 | yet. |
627 | yet. |
592 | |
628 | |
593 | =head2 MEMORY USAGE |
629 | =head2 MEMORY USAGE |
594 | |
630 | |
595 | Per-request usage: |
631 | Per-request usage: |
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609 | temporary buffers, and each thread requires a stack and other data |
645 | temporary buffers, and each thread requires a stack and other data |
610 | structures (usually around 16k-128k, depending on the OS). |
646 | structures (usually around 16k-128k, depending on the OS). |
611 | |
647 | |
612 | =head1 KNOWN BUGS |
648 | =head1 KNOWN BUGS |
613 | |
649 | |
614 | Known bugs will be fixed in the next release. |
650 | Known bugs will be fixed in the next release, except: |
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651 | |
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652 | If you use a transaction in any request, and the request returns |
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653 | with an operating system error or DB_LOCK_NOTGRANTED, the internal |
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654 | TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>, |
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655 | above. |
615 | |
656 | |
616 | =head1 SEE ALSO |
657 | =head1 SEE ALSO |
617 | |
658 | |
618 | L<Coro::AIO>. |
659 | L<Coro::BDB>, L<IO::AIO>. |
619 | |
660 | |
620 | =head1 AUTHOR |
661 | =head1 AUTHOR |
621 | |
662 | |
622 | Marc Lehmann <schmorp@schmorp.de> |
663 | Marc Lehmann <schmorp@schmorp.de> |
623 | http://home.schmorp.de/ |
664 | http://home.schmorp.de/ |