… | |
… | |
18 | }; |
18 | }; |
19 | |
19 | |
20 | # version 2+ has request and group objects |
20 | # version 2+ has request and group objects |
21 | use IO::AIO 2; |
21 | use IO::AIO 2; |
22 | |
22 | |
|
|
23 | aioreq_pri 4; # give next request a very high priority |
23 | my $req = aio_unlink "/tmp/file", sub { }; |
24 | my $req = aio_unlink "/tmp/file", sub { }; |
24 | $req->cancel; # cancel request if still in queue |
25 | $req->cancel; # cancel request if still in queue |
25 | |
26 | |
26 | my $grp = aio_group sub { print "all stats done\n" }; |
27 | my $grp = aio_group sub { print "all stats done\n" }; |
27 | add $grp aio_stat "..." for ...; |
28 | add $grp aio_stat "..." for ...; |
… | |
… | |
50 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
51 | |
52 | |
52 | This module implements asynchronous I/O using whatever means your |
53 | This module implements asynchronous I/O using whatever means your |
53 | operating system supports. |
54 | operating system supports. |
54 | |
55 | |
55 | Currently, a number of threads are started that execute your read/writes |
56 | In this version, a number of threads are started that execute your |
56 | and signal their completion. You don't need thread support in your libc or |
57 | requests and signal their completion. You don't need thread support |
57 | perl, and the threads created by this module will not be visible to the |
58 | in perl, and the threads created by this module will not be visible |
58 | pthreads library. In the future, this module might make use of the native |
59 | to perl. In the future, this module might make use of the native aio |
59 | aio functions available on many operating systems. However, they are often |
60 | functions available on many operating systems. However, they are often |
60 | not well-supported (Linux doesn't allow them on normal files currently, |
61 | not well-supported or restricted (Linux doesn't allow them on normal |
61 | for example), and they would only support aio_read and aio_write, so the |
62 | files currently, for example), and they would only support aio_read and |
62 | remaining functionality would have to be implemented using threads anyway. |
63 | aio_write, so the remaining functionality would have to be implemented |
|
|
64 | using threads anyway. |
63 | |
65 | |
64 | Although the module will work with in the presence of other threads, it is |
66 | Although the module will work with in the presence of other (Perl-) |
65 | currently not reentrant, so use appropriate locking yourself, always call |
67 | threads, it is currently not reentrant in any way, so use appropriate |
66 | C<poll_cb> from within the same thread, or never call C<poll_cb> (or other |
68 | locking yourself, always call C<poll_cb> from within the same thread, or |
67 | C<aio_> functions) recursively. |
69 | never call C<poll_cb> (or other C<aio_> functions) recursively. |
|
|
70 | |
|
|
71 | =head1 REQUEST ANATOMY AND LIFETIME |
|
|
72 | |
|
|
73 | Every C<aio_*> function creates a request. which is a C data structure not |
|
|
74 | directly visible to Perl. |
|
|
75 | |
|
|
76 | If called in non-void context, every request function returns a Perl |
|
|
77 | object representing the request. In void context, nothing is returned, |
|
|
78 | which saves a bit of memory. |
|
|
79 | |
|
|
80 | The perl object is a fairly standard ref-to-hash object. The hash contents |
|
|
81 | are not used by IO::AIO so you are free to store anything you like in it. |
|
|
82 | |
|
|
83 | During their existance, aio requests travel through the following states, |
|
|
84 | in order: |
|
|
85 | |
|
|
86 | =over 4 |
|
|
87 | |
|
|
88 | =item ready |
|
|
89 | |
|
|
90 | Immediately after a request is created it is put into the ready state, |
|
|
91 | waiting for a thread to execute it. |
|
|
92 | |
|
|
93 | =item execute |
|
|
94 | |
|
|
95 | A thread has accepted the request for processing and is currently |
|
|
96 | executing it (e.g. blocking in read). |
|
|
97 | |
|
|
98 | =item pending |
|
|
99 | |
|
|
100 | The request has been executed and is waiting for result processing. |
|
|
101 | |
|
|
102 | While request submission and execution is fully asynchronous, result |
|
|
103 | processing is not and relies on the perl interpreter calling C<poll_cb> |
|
|
104 | (or another function with the same effect). |
|
|
105 | |
|
|
106 | =item result |
|
|
107 | |
|
|
108 | The request results are processed synchronously by C<poll_cb>. |
|
|
109 | |
|
|
110 | The C<poll_cb> function will process all outstanding aio requests by |
|
|
111 | calling their callbacks, freeing memory associated with them and managing |
|
|
112 | any groups they are contained in. |
|
|
113 | |
|
|
114 | =item done |
|
|
115 | |
|
|
116 | Request has reached the end of its lifetime and holds no resources anymore |
|
|
117 | (except possibly for the Perl object, but its connection to the actual |
|
|
118 | aio request is severed and calling its methods will either do nothing or |
|
|
119 | result in a runtime error). |
68 | |
120 | |
69 | =cut |
121 | =cut |
70 | |
122 | |
71 | package IO::AIO; |
123 | package IO::AIO; |
72 | |
124 | |
… | |
… | |
76 | use base 'Exporter'; |
128 | use base 'Exporter'; |
77 | |
129 | |
78 | BEGIN { |
130 | BEGIN { |
79 | our $VERSION = '2.0'; |
131 | our $VERSION = '2.0'; |
80 | |
132 | |
81 | our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat |
133 | our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat |
82 | aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink |
134 | aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink |
83 | aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move |
135 | aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move |
84 | aio_group); |
136 | aio_group aio_nop); |
85 | our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); |
137 | our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); |
|
|
138 | our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush |
|
|
139 | min_parallel max_parallel max_outstanding nreqs); |
86 | |
140 | |
87 | @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; |
141 | @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; |
88 | |
142 | |
89 | require XSLoader; |
143 | require XSLoader; |
90 | XSLoader::load ("IO::AIO", $VERSION); |
144 | XSLoader::load ("IO::AIO", $VERSION); |
… | |
… | |
121 | environment, d) use Glib::filename_from_unicode on unicode filenames or e) |
175 | environment, d) use Glib::filename_from_unicode on unicode filenames or e) |
122 | use something else. |
176 | use something else. |
123 | |
177 | |
124 | =over 4 |
178 | =over 4 |
125 | |
179 | |
|
|
180 | =item aioreq_pri $pri |
|
|
181 | |
|
|
182 | Sets the priority for the next aio request. The default priority |
|
|
183 | is C<0>, the minimum and maximum priorities are C<-4> and C<4>, |
|
|
184 | respectively. Requests with higher priority will be serviced first. |
|
|
185 | |
|
|
186 | The priority will be reset to C<0> after each call to one of the C<aio_> |
|
|
187 | functions. |
|
|
188 | |
|
|
189 | Example: open a file with low priority, then read something from it with |
|
|
190 | higher priority so the read request is serviced before other low priority |
|
|
191 | open requests (potentially spamming the cache): |
|
|
192 | |
|
|
193 | aioreq_pri -3; |
|
|
194 | aio_open ..., sub { |
|
|
195 | return unless $_[0]; |
|
|
196 | |
|
|
197 | aioreq_pri -2; |
|
|
198 | aio_read $_[0], ..., sub { |
|
|
199 | ... |
|
|
200 | }; |
|
|
201 | }; |
|
|
202 | |
|
|
203 | =item aioreq_nice $pri_adjust |
|
|
204 | |
|
|
205 | Similar to C<aioreq_pri>, but subtracts the given value from the current |
|
|
206 | priority, so effects are cumulative. |
|
|
207 | |
126 | =item aio_open $pathname, $flags, $mode, $callback->($fh) |
208 | =item aio_open $pathname, $flags, $mode, $callback->($fh) |
127 | |
209 | |
128 | Asynchronously open or create a file and call the callback with a newly |
210 | Asynchronously open or create a file and call the callback with a newly |
129 | created filehandle for the file. |
211 | created filehandle for the file. |
130 | |
212 | |
… | |
… | |
181 | $_[0] > 0 or die "read error: $!"; |
263 | $_[0] > 0 or die "read error: $!"; |
182 | print "read $_[0] bytes: <$buffer>\n"; |
264 | print "read $_[0] bytes: <$buffer>\n"; |
183 | }; |
265 | }; |
184 | |
266 | |
185 | =item aio_move $srcpath, $dstpath, $callback->($status) |
267 | =item aio_move $srcpath, $dstpath, $callback->($status) |
186 | |
|
|
187 | [EXPERIMENTAL due to internal aio_group use] |
|
|
188 | |
268 | |
189 | Try to move the I<file> (directories not supported as either source or |
269 | Try to move the I<file> (directories not supported as either source or |
190 | destination) from C<$srcpath> to C<$dstpath> and call the callback with |
270 | destination) from C<$srcpath> to C<$dstpath> and call the callback with |
191 | the C<0> (error) or C<-1> ok. |
271 | the C<0> (error) or C<-1> ok. |
192 | |
272 | |
… | |
… | |
345 | The callback a single argument which is either C<undef> or an array-ref |
425 | The callback a single argument which is either C<undef> or an array-ref |
346 | with the filenames. |
426 | with the filenames. |
347 | |
427 | |
348 | =item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
428 | =item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
349 | |
429 | |
350 | [EXPERIMENTAL due to internal aio_group use] |
|
|
351 | |
|
|
352 | Scans a directory (similar to C<aio_readdir>) but additionally tries to |
430 | Scans a directory (similar to C<aio_readdir>) but additionally tries to |
353 | separate the entries of directory C<$path> into two sets of names, ones |
431 | separate the entries of directory C<$path> into two sets of names, ones |
354 | you can recurse into (directories or links to them), and ones you cannot |
432 | you can recurse into (directories or links to them), and ones you cannot |
355 | recurse into (everything else). |
433 | recurse into (everything else). |
356 | |
434 | |
357 | C<aio_scandir> is a composite request that consists of many sub |
435 | C<aio_scandir> is a composite request that creates of many sub requests_ |
358 | requests. C<$maxreq> specifies the maximum number of outstanding aio |
436 | C<$maxreq> specifies the maximum number of outstanding aio requests that |
359 | requests that this function generates. If it is C<< <= 0 >>, then a |
437 | this function generates. If it is C<< <= 0 >>, then a suitable default |
360 | suitable default will be chosen (currently 8). |
438 | will be chosen (currently 6). |
361 | |
439 | |
362 | On error, the callback is called without arguments, otherwise it receives |
440 | On error, the callback is called without arguments, otherwise it receives |
363 | two array-refs with path-relative entry names. |
441 | two array-refs with path-relative entry names. |
364 | |
442 | |
365 | Example: |
443 | Example: |
… | |
… | |
404 | sub aio_scandir($$$) { |
482 | sub aio_scandir($$$) { |
405 | my ($path, $maxreq, $cb) = @_; |
483 | my ($path, $maxreq, $cb) = @_; |
406 | |
484 | |
407 | my $grp = aio_group $cb; |
485 | my $grp = aio_group $cb; |
408 | |
486 | |
409 | $maxreq = 8 if $maxreq <= 0; |
487 | $maxreq = 6 if $maxreq <= 0; |
410 | |
488 | |
411 | # stat once |
489 | # stat once |
412 | add $grp aio_stat $path, sub { |
490 | add $grp aio_stat $path, sub { |
413 | return $grp->result () if $_[0]; |
491 | return $grp->result () if $_[0]; |
414 | my $now = time; |
492 | my $now = time; |
… | |
… | |
442 | map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], |
520 | map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length], |
443 | @$entries]; |
521 | @$entries]; |
444 | |
522 | |
445 | my (@dirs, @nondirs); |
523 | my (@dirs, @nondirs); |
446 | |
524 | |
447 | my ($statcb, $schedcb); |
|
|
448 | my $nreq = 0; |
|
|
449 | |
|
|
450 | my $statgrp = add $grp aio_group; |
525 | my $statgrp = add $grp aio_group sub { |
|
|
526 | $grp->result (\@dirs, \@nondirs); |
|
|
527 | }; |
451 | |
528 | |
452 | $schedcb = sub { |
529 | limit $statgrp $maxreq; |
453 | if (@$entries) { |
530 | feed $statgrp sub { |
454 | if ($nreq < $maxreq) { |
531 | return unless @$entries; |
455 | my $ent = pop @$entries; |
532 | my $entry = pop @$entries; |
|
|
533 | |
|
|
534 | add $statgrp aio_stat "$path/$entry/.", sub { |
|
|
535 | if ($_[0] < 0) { |
|
|
536 | push @nondirs, $entry; |
|
|
537 | } else { |
|
|
538 | # need to check for real directory |
|
|
539 | add $statgrp aio_lstat "$path/$entry", sub { |
|
|
540 | if (-d _) { |
|
|
541 | push @dirs, $entry; |
|
|
542 | |
|
|
543 | unless (--$ndirs) { |
|
|
544 | push @nondirs, @$entries; |
|
|
545 | feed $statgrp; |
|
|
546 | } |
|
|
547 | } else { |
|
|
548 | push @nondirs, $entry; |
|
|
549 | } |
456 | $nreq++; |
550 | } |
457 | add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) }; |
|
|
458 | } |
551 | } |
459 | } elsif (!$nreq) { |
|
|
460 | # finished |
|
|
461 | $statgrp->cancel; |
|
|
462 | undef $statcb; |
|
|
463 | undef $schedcb; |
|
|
464 | $grp->result (\@dirs, \@nondirs); |
|
|
465 | } |
552 | }; |
466 | }; |
553 | }; |
467 | $statcb = sub { |
|
|
468 | my ($status, $entry) = @_; |
|
|
469 | |
|
|
470 | if ($status < 0) { |
|
|
471 | $nreq--; |
|
|
472 | push @nondirs, $entry; |
|
|
473 | &$schedcb; |
|
|
474 | } else { |
|
|
475 | # need to check for real directory |
|
|
476 | add $grp aio_lstat "$path/$entry", sub { |
|
|
477 | $nreq--; |
|
|
478 | |
|
|
479 | if (-d _) { |
|
|
480 | push @dirs, $entry; |
|
|
481 | |
|
|
482 | if (!--$ndirs) { |
|
|
483 | push @nondirs, @$entries; |
|
|
484 | $entries = []; |
|
|
485 | } |
|
|
486 | } else { |
|
|
487 | push @nondirs, $entry; |
|
|
488 | } |
|
|
489 | |
|
|
490 | &$schedcb; |
|
|
491 | } |
|
|
492 | } |
|
|
493 | }; |
|
|
494 | |
|
|
495 | &$schedcb while @$entries && $nreq < $maxreq; |
|
|
496 | }; |
554 | }; |
497 | }; |
555 | }; |
498 | }; |
556 | }; |
499 | |
557 | |
500 | $grp |
558 | $grp |
… | |
… | |
513 | If this call isn't available because your OS lacks it or it couldn't be |
571 | If this call isn't available because your OS lacks it or it couldn't be |
514 | detected, it will be emulated by calling C<fsync> instead. |
572 | detected, it will be emulated by calling C<fsync> instead. |
515 | |
573 | |
516 | =item aio_group $callback->(...) |
574 | =item aio_group $callback->(...) |
517 | |
575 | |
518 | [EXPERIMENTAL] |
|
|
519 | |
|
|
520 | This is a very special aio request: Instead of doing something, it is a |
576 | This is a very special aio request: Instead of doing something, it is a |
521 | container for other aio requests, which is useful if you want to bundle |
577 | container for other aio requests, which is useful if you want to bundle |
522 | many requests into a single, composite, request. |
578 | many requests into a single, composite, request with a definite callback |
|
|
579 | and the ability to cancel the whole request with its subrequests. |
523 | |
580 | |
524 | Returns an object of class L<IO::AIO::GRP>. See its documentation below |
581 | Returns an object of class L<IO::AIO::GRP>. See its documentation below |
525 | for more info. |
582 | for more info. |
526 | |
583 | |
527 | Example: |
584 | Example: |
… | |
… | |
533 | add $grp |
590 | add $grp |
534 | (aio_stat ...), |
591 | (aio_stat ...), |
535 | (aio_stat ...), |
592 | (aio_stat ...), |
536 | ...; |
593 | ...; |
537 | |
594 | |
|
|
595 | =item aio_nop $callback->() |
|
|
596 | |
|
|
597 | This is a special request - it does nothing in itself and is only used for |
|
|
598 | side effects, such as when you want to add a dummy request to a group so |
|
|
599 | that finishing the requests in the group depends on executing the given |
|
|
600 | code. |
|
|
601 | |
|
|
602 | While this request does nothing, it still goes through the execution |
|
|
603 | phase and still requires a worker thread. Thus, the callback will not |
|
|
604 | be executed immediately but only after other requests in the queue have |
|
|
605 | entered their execution phase. This can be used to measure request |
|
|
606 | latency. |
|
|
607 | |
538 | =item IO::AIO::aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED* |
608 | =item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
539 | |
609 | |
540 | Mainly used for debugging and benchmarking, this aio request puts one of |
610 | Mainly used for debugging and benchmarking, this aio request puts one of |
541 | the request workers to sleep for the given time. |
611 | the request workers to sleep for the given time. |
542 | |
612 | |
543 | While it is theoretically handy to have simple I/O scheduling requests |
613 | While it is theoretically handy to have simple I/O scheduling requests |
544 | like sleep and file handle readable/writable, the overhead this creates |
614 | like sleep and file handle readable/writable, the overhead this creates is |
545 | is immense, so do not use this function except to put your application |
615 | immense (it blocks a thread for a long time) so do not use this function |
546 | under artificial I/O pressure. |
616 | except to put your application under artificial I/O pressure. |
547 | |
617 | |
548 | =back |
618 | =back |
549 | |
619 | |
550 | =head2 IO::AIO::REQ CLASS |
620 | =head2 IO::AIO::REQ CLASS |
551 | |
621 | |
552 | All non-aggregate C<aio_*> functions return an object of this class when |
622 | All non-aggregate C<aio_*> functions return an object of this class when |
553 | called in non-void context. |
623 | called in non-void context. |
554 | |
624 | |
555 | A request always moves through the following five states in its lifetime, |
|
|
556 | in order: B<ready> (request has been created, but has not been executed |
|
|
557 | yet), B<execute> (request is currently being executed), B<pending> |
|
|
558 | (request has been executed but callback has not been called yet), |
|
|
559 | B<result> (results are being processed synchronously, includes calling the |
|
|
560 | callback) and B<done> (request has reached the end of its lifetime and |
|
|
561 | holds no resources anymore). |
|
|
562 | |
|
|
563 | =over 4 |
625 | =over 4 |
564 | |
626 | |
565 | =item $req->cancel |
627 | =item cancel $req |
566 | |
628 | |
567 | Cancels the request, if possible. Has the effect of skipping execution |
629 | Cancels the request, if possible. Has the effect of skipping execution |
568 | when entering the B<execute> state and skipping calling the callback when |
630 | when entering the B<execute> state and skipping calling the callback when |
569 | entering the the B<result> state, but will leave the request otherwise |
631 | entering the the B<result> state, but will leave the request otherwise |
570 | untouched. That means that requests that currently execute will not be |
632 | untouched. That means that requests that currently execute will not be |
571 | stopped and resources held by the request will not be freed prematurely. |
633 | stopped and resources held by the request will not be freed prematurely. |
572 | |
634 | |
|
|
635 | =item cb $req $callback->(...) |
|
|
636 | |
|
|
637 | Replace (or simply set) the callback registered to the request. |
|
|
638 | |
573 | =back |
639 | =back |
574 | |
640 | |
575 | =head2 IO::AIO::GRP CLASS |
641 | =head2 IO::AIO::GRP CLASS |
576 | |
642 | |
577 | This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to |
643 | This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to |
… | |
… | |
603 | }; |
669 | }; |
604 | |
670 | |
605 | This makes it very easy to create composite requests (see the source of |
671 | This makes it very easy to create composite requests (see the source of |
606 | C<aio_move> for an application) that work and feel like simple requests. |
672 | C<aio_move> for an application) that work and feel like simple requests. |
607 | |
673 | |
|
|
674 | =over 4 |
|
|
675 | |
608 | The IO::AIO::GRP objects will be cleaned up during calls to |
676 | =item * The IO::AIO::GRP objects will be cleaned up during calls to |
609 | C<IO::AIO::poll_cb>, just like any other request. |
677 | C<IO::AIO::poll_cb>, just like any other request. |
610 | |
678 | |
611 | They can be canceled like any other request. Canceling will cancel not |
679 | =item * They can be canceled like any other request. Canceling will cancel not |
612 | only the request itself, but also all requests it contains. |
680 | only the request itself, but also all requests it contains. |
613 | |
681 | |
614 | They can also can also be added to other IO::AIO::GRP objects. |
682 | =item * They can also can also be added to other IO::AIO::GRP objects. |
615 | |
683 | |
616 | You must not add requests to a group from within the group callback (or |
684 | =item * You must not add requests to a group from within the group callback (or |
617 | any later time). |
685 | any later time). |
|
|
686 | |
|
|
687 | =item * This does not harmonise well with C<max_outstanding>, so best do |
|
|
688 | not combine C<aio_group> with it. Groups and feeders are recommended for |
|
|
689 | this kind of concurrency-limiting. |
|
|
690 | |
|
|
691 | =back |
618 | |
692 | |
619 | Their lifetime, simplified, looks like this: when they are empty, they |
693 | Their lifetime, simplified, looks like this: when they are empty, they |
620 | will finish very quickly. If they contain only requests that are in the |
694 | will finish very quickly. If they contain only requests that are in the |
621 | C<done> state, they will also finish. Otherwise they will continue to |
695 | C<done> state, they will also finish. Otherwise they will continue to |
622 | exist. |
696 | exist. |
… | |
… | |
626 | group. And only when all those requests have finished will the the group |
700 | group. And only when all those requests have finished will the the group |
627 | itself finish. |
701 | itself finish. |
628 | |
702 | |
629 | =over 4 |
703 | =over 4 |
630 | |
704 | |
|
|
705 | =item add $grp ... |
|
|
706 | |
631 | =item $grp->add (...) |
707 | =item $grp->add (...) |
632 | |
|
|
633 | =item add $grp ... |
|
|
634 | |
708 | |
635 | Add one or more requests to the group. Any type of L<IO::AIO::REQ> can |
709 | Add one or more requests to the group. Any type of L<IO::AIO::REQ> can |
636 | be added, including other groups, as long as you do not create circular |
710 | be added, including other groups, as long as you do not create circular |
637 | dependencies. |
711 | dependencies. |
638 | |
712 | |
639 | Returns all its arguments. |
713 | Returns all its arguments. |
640 | |
714 | |
|
|
715 | =item $grp->cancel_subs |
|
|
716 | |
|
|
717 | Cancel all subrequests and clears any feeder, but not the group request |
|
|
718 | itself. Useful when you queued a lot of events but got a result early. |
|
|
719 | |
641 | =item $grp->result (...) |
720 | =item $grp->result (...) |
642 | |
721 | |
643 | Set the result value(s) that will be passed to the group callback when all |
722 | Set the result value(s) that will be passed to the group callback when all |
644 | subrequests have finished. By default, no argument will be passed. |
723 | subrequests have finished. By default, no argument will be passed. |
645 | |
724 | |
646 | =item $grp->set_feeder ($callback->($grp)) |
725 | =item feed $grp $callback->($grp) |
647 | |
|
|
648 | [VERY EXPERIMENTAL] |
|
|
649 | |
726 | |
650 | Sets a feeder/generator on this group: every group can have an attached |
727 | Sets a feeder/generator on this group: every group can have an attached |
651 | generator that generates requests if idle. The idea behind this is that, |
728 | generator that generates requests if idle. The idea behind this is that, |
652 | although you could just queue as many requests as you want in a group, |
729 | although you could just queue as many requests as you want in a group, |
653 | this might starve other requests for a potentially long time. For |
730 | this might starve other requests for a potentially long time. For |
654 | example, C<aio_scandir> might generate hundreds of thousands C<aio_stat> |
731 | example, C<aio_scandir> might generate hundreds of thousands C<aio_stat> |
655 | requests, delaying any later requests for a long time. |
732 | requests, delaying any later requests for a long time. |
656 | |
733 | |
657 | To avoid this, and allow incremental generation of requests, you can |
734 | To avoid this, and allow incremental generation of requests, you can |
658 | instead a group and set a feeder on it that generates those requests. The |
735 | instead a group and set a feeder on it that generates those requests. The |
659 | feeder will be called whenever there are few enough (see C<feeder_limit>, |
736 | feed callback will be called whenever there are few enough (see C<limit>, |
660 | below) requests active in the group itself and is expected to queue more |
737 | below) requests active in the group itself and is expected to queue more |
661 | requests. |
738 | requests. |
662 | |
739 | |
663 | The feeder can queue as many requests as it likes (i.e. C<add> does not |
740 | The feed callback can queue as many requests as it likes (i.e. C<add> does |
664 | impose any limits). |
741 | not impose any limits). |
665 | |
742 | |
666 | If the feeder does not queue more requests when called, it will be |
743 | If the feed does not queue more requests when called, it will be |
667 | automatically removed from the group. |
744 | automatically removed from the group. |
668 | |
745 | |
669 | If the feeder limit is C<0>, it will be set to C<2> automatically. |
746 | If the feed limit is C<0>, it will be set to C<2> automatically. |
670 | |
747 | |
671 | Example: |
748 | Example: |
672 | |
749 | |
673 | # stat all files in @files, but only ever use four aio requests concurrently: |
750 | # stat all files in @files, but only ever use four aio requests concurrently: |
674 | |
751 | |
675 | my $grp = aio_group sub { print "finished\n" }; |
752 | my $grp = aio_group sub { print "finished\n" }; |
676 | $grp->feeder_limit (4); |
753 | limit $grp 4; |
677 | $grp->set_feeder (sub { |
754 | feed $grp sub { |
678 | my $file = pop @files |
755 | my $file = pop @files |
679 | or return; |
756 | or return; |
680 | |
757 | |
681 | add $grp aio_stat $file, sub { ... }; |
758 | add $grp aio_stat $file, sub { ... }; |
682 | }); |
759 | }; |
683 | |
760 | |
684 | =item $grp->feeder_limit ($num) |
761 | =item limit $grp $num |
685 | |
762 | |
686 | Sets the feeder limit for the group: The feeder will be called whenever |
763 | Sets the feeder limit for the group: The feeder will be called whenever |
687 | the group contains less than this many requests. |
764 | the group contains less than this many requests. |
688 | |
765 | |
689 | Setting the limit to C<0> will pause the feeding process. |
766 | Setting the limit to C<0> will pause the feeding process. |
… | |
… | |
752 | IO::AIO::poll_wait, IO::AIO::poll_cb |
829 | IO::AIO::poll_wait, IO::AIO::poll_cb |
753 | if IO::AIO::nreqs; |
830 | if IO::AIO::nreqs; |
754 | |
831 | |
755 | =item IO::AIO::min_parallel $nthreads |
832 | =item IO::AIO::min_parallel $nthreads |
756 | |
833 | |
757 | Set the minimum number of AIO threads to C<$nthreads>. The current default |
834 | Set the minimum number of AIO threads to C<$nthreads>. The current |
758 | is C<4>, which means four asynchronous operations can be done at one time |
835 | default is C<8>, which means eight asynchronous operations can execute |
759 | (the number of outstanding operations, however, is unlimited). |
836 | concurrently at any one time (the number of outstanding requests, |
|
|
837 | however, is unlimited). |
760 | |
838 | |
761 | IO::AIO starts threads only on demand, when an AIO request is queued and |
839 | IO::AIO starts threads only on demand, when an AIO request is queued and |
762 | no free thread exists. |
840 | no free thread exists. |
763 | |
841 | |
764 | It is recommended to keep the number of threads low, as some Linux |
842 | It is recommended to keep the number of threads relatively low, as some |
765 | kernel versions will scale negatively with the number of threads (higher |
843 | Linux kernel versions will scale negatively with the number of threads |
766 | parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 |
844 | (higher parallelity => MUCH higher latency). With current Linux 2.6 |
767 | threads should be fine. |
845 | versions, 4-32 threads should be fine. |
768 | |
846 | |
769 | Under most circumstances you don't need to call this function, as the |
847 | Under most circumstances you don't need to call this function, as the |
770 | module selects a default that is suitable for low to moderate load. |
848 | module selects a default that is suitable for low to moderate load. |
771 | |
849 | |
772 | =item IO::AIO::max_parallel $nthreads |
850 | =item IO::AIO::max_parallel $nthreads |
… | |
… | |
783 | |
861 | |
784 | Under normal circumstances you don't need to call this function. |
862 | Under normal circumstances you don't need to call this function. |
785 | |
863 | |
786 | =item $oldnreqs = IO::AIO::max_outstanding $nreqs |
864 | =item $oldnreqs = IO::AIO::max_outstanding $nreqs |
787 | |
865 | |
|
|
866 | [DEPRECATED] |
|
|
867 | |
788 | Sets the maximum number of outstanding requests to C<$nreqs>. If you |
868 | Sets the maximum number of outstanding requests to C<$nreqs>. If you |
789 | try to queue up more than this number of requests, the caller will block until |
869 | try to queue up more than this number of requests, the caller will block until |
790 | some requests have been handled. |
870 | some requests have been handled. |
791 | |
871 | |
792 | The default is very large, so normally there is no practical limit. If you |
872 | The default is very large, so normally there is no practical limit. If you |
793 | queue up many requests in a loop it often improves speed if you set |
873 | queue up many requests in a loop it often improves speed if you set |
794 | this to a relatively low number, such as C<100>. |
874 | this to a relatively low number, such as C<100>. |
|
|
875 | |
|
|
876 | This function does not work well together with C<aio_group>'s, and their |
|
|
877 | feeder interface is better suited to limiting concurrency, so do not use |
|
|
878 | this function. |
795 | |
879 | |
796 | Under normal circumstances you don't need to call this function. |
880 | Under normal circumstances you don't need to call this function. |
797 | |
881 | |
798 | =back |
882 | =back |
799 | |
883 | |
… | |
… | |
813 | or return undef; |
897 | or return undef; |
814 | |
898 | |
815 | *$sym |
899 | *$sym |
816 | } |
900 | } |
817 | |
901 | |
818 | min_parallel 4; |
902 | min_parallel 8; |
819 | |
903 | |
820 | END { |
904 | END { |
821 | max_parallel 0; |
905 | max_parallel 0; |
822 | } |
906 | } |
823 | |
907 | |
… | |
… | |
828 | This module should do "the right thing" when the process using it forks: |
912 | This module should do "the right thing" when the process using it forks: |
829 | |
913 | |
830 | Before the fork, IO::AIO enters a quiescent state where no requests |
914 | Before the fork, IO::AIO enters a quiescent state where no requests |
831 | can be added in other threads and no results will be processed. After |
915 | can be added in other threads and no results will be processed. After |
832 | the fork the parent simply leaves the quiescent state and continues |
916 | the fork the parent simply leaves the quiescent state and continues |
833 | request/result processing, while the child clears the request/result |
917 | request/result processing, while the child frees the request/result queue |
834 | queue (so the requests started before the fork will only be handled in |
918 | (so that the requests started before the fork will only be handled in the |
835 | the parent). Threads will be started on demand until the limit ste in the |
919 | parent). Threads will be started on demand until the limit set in the |
836 | parent process has been reached again. |
920 | parent process has been reached again. |
837 | |
921 | |
838 | In short: the parent will, after a short pause, continue as if fork had |
922 | In short: the parent will, after a short pause, continue as if fork had |
839 | not been called, while the child will act as if IO::AIO has not been used |
923 | not been called, while the child will act as if IO::AIO has not been used |
840 | yet. |
924 | yet. |
841 | |
925 | |
842 | =head2 MEMORY USAGE |
926 | =head2 MEMORY USAGE |
843 | |
927 | |
|
|
928 | Per-request usage: |
|
|
929 | |
844 | Each aio request uses - depending on your architecture - around 128 bytes |
930 | Each aio request uses - depending on your architecture - around 100-200 |
845 | of memory. In addition, stat requests need a stat buffer (possibly a few |
931 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
846 | hundred bytes). Perl scalars and other data passed into aio requests will |
932 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
847 | also be locked. |
933 | scalars and other data passed into aio requests will also be locked and |
|
|
934 | will consume memory till the request has entered the done state. |
848 | |
935 | |
849 | This is now awfully much, so queuing lots of requests is not usually a |
936 | This is now awfully much, so queuing lots of requests is not usually a |
850 | problem. |
937 | problem. |
851 | |
938 | |
852 | Each thread needs a stack area which is usually around 16k, sometimes much |
939 | Per-thread usage: |
853 | larger, depending on the OS. |
940 | |
|
|
941 | In the execution phase, some aio requests require more memory for |
|
|
942 | temporary buffers, and each thread requires a stack and other data |
|
|
943 | structures (usually around 16k-128k, depending on the OS). |
|
|
944 | |
|
|
945 | =head1 KNOWN BUGS |
|
|
946 | |
|
|
947 | Known bugs will be fixed in the next release. |
854 | |
948 | |
855 | =head1 SEE ALSO |
949 | =head1 SEE ALSO |
856 | |
950 | |
857 | L<Coro>, L<Linux::AIO> (obsolete). |
951 | L<Coro::AIO>. |
858 | |
952 | |
859 | =head1 AUTHOR |
953 | =head1 AUTHOR |
860 | |
954 | |
861 | Marc Lehmann <schmorp@schmorp.de> |
955 | Marc Lehmann <schmorp@schmorp.de> |
862 | http://home.schmorp.de/ |
956 | http://home.schmorp.de/ |