… | |
… | |
352 | Scans a directory (similar to C<aio_readdir>) but additionally tries to |
352 | Scans a directory (similar to C<aio_readdir>) but additionally tries to |
353 | separate the entries of directory C<$path> into two sets of names, ones |
353 | separate the entries of directory C<$path> into two sets of names, ones |
354 | you can recurse into (directories or links to them), and ones you cannot |
354 | you can recurse into (directories or links to them), and ones you cannot |
355 | recurse into (everything else). |
355 | recurse into (everything else). |
356 | |
356 | |
357 | C<aio_scandir> is a composite request that consists of many sub |
357 | C<aio_scandir> is a composite request that creates of many sub requests_ |
358 | requests. C<$maxreq> specifies the maximum number of outstanding aio |
358 | C<$maxreq> specifies the maximum number of outstanding aio requests that |
359 | requests that this function generates. If it is C<< <= 0 >>, then a |
359 | this function generates. If it is C<< <= 0 >>, then a suitable default |
360 | suitable default will be chosen (currently 8). |
360 | will be chosen (currently 6). |
361 | |
361 | |
362 | On error, the callback is called without arguments, otherwise it receives |
362 | On error, the callback is called without arguments, otherwise it receives |
363 | two array-refs with path-relative entry names. |
363 | two array-refs with path-relative entry names. |
364 | |
364 | |
365 | Example: |
365 | Example: |
… | |
… | |
404 | sub aio_scandir($$$) { |
404 | sub aio_scandir($$$) { |
405 | my ($path, $maxreq, $cb) = @_; |
405 | my ($path, $maxreq, $cb) = @_; |
406 | |
406 | |
407 | my $grp = aio_group $cb; |
407 | my $grp = aio_group $cb; |
408 | |
408 | |
409 | $maxreq = 8 if $maxreq <= 0; |
409 | $maxreq = 6 if $maxreq <= 0; |
410 | |
410 | |
411 | # stat once |
411 | # stat once |
412 | add $grp aio_stat $path, sub { |
412 | add $grp aio_stat $path, sub { |
413 | return $grp->result () if $_[0]; |
413 | return $grp->result () if $_[0]; |
414 | my $now = time; |
414 | my $now = time; |
… | |
… | |
445 | my (@dirs, @nondirs); |
445 | my (@dirs, @nondirs); |
446 | |
446 | |
447 | my ($statcb, $schedcb); |
447 | my ($statcb, $schedcb); |
448 | my $nreq = 0; |
448 | my $nreq = 0; |
449 | |
449 | |
|
|
450 | my $statgrp = add $grp aio_group; |
|
|
451 | |
450 | $schedcb = sub { |
452 | $schedcb = sub { |
451 | if (@$entries) { |
453 | if (@$entries) { |
452 | if ($nreq < $maxreq) { |
454 | if ($nreq < $maxreq) { |
453 | my $ent = pop @$entries; |
455 | my $ent = pop @$entries; |
454 | $nreq++; |
456 | $nreq++; |
455 | add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) }; |
457 | add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) }; |
456 | } |
458 | } |
457 | } elsif (!$nreq) { |
459 | } elsif (!$nreq) { |
458 | # finished |
460 | # finished |
|
|
461 | $statgrp->cancel; |
459 | undef $statcb; |
462 | undef $statcb; |
460 | undef $schedcb; |
463 | undef $schedcb; |
461 | $grp->result (\@dirs, \@nondirs) if $cb; |
464 | $grp->result (\@dirs, \@nondirs); |
462 | undef $cb; |
|
|
463 | } |
465 | } |
464 | }; |
466 | }; |
465 | $statcb = sub { |
467 | $statcb = sub { |
466 | my ($status, $entry) = @_; |
468 | my ($status, $entry) = @_; |
467 | |
469 | |
… | |
… | |
605 | |
607 | |
606 | The IO::AIO::GRP objects will be cleaned up during calls to |
608 | The IO::AIO::GRP objects will be cleaned up during calls to |
607 | C<IO::AIO::poll_cb>, just like any other request. |
609 | C<IO::AIO::poll_cb>, just like any other request. |
608 | |
610 | |
609 | They can be canceled like any other request. Canceling will cancel not |
611 | They can be canceled like any other request. Canceling will cancel not |
610 | just the request itself, but also all requests it contains. |
612 | only the request itself, but also all requests it contains. |
611 | |
613 | |
612 | They can also can also be added to other IO::AIO::GRP objects. |
614 | They can also can also be added to other IO::AIO::GRP objects. |
|
|
615 | |
|
|
616 | You must not add requests to a group from within the group callback (or |
|
|
617 | any later time). |
613 | |
618 | |
614 | Their lifetime, simplified, looks like this: when they are empty, they |
619 | Their lifetime, simplified, looks like this: when they are empty, they |
615 | will finish very quickly. If they contain only requests that are in the |
620 | will finish very quickly. If they contain only requests that are in the |
616 | C<done> state, they will also finish. Otherwise they will continue to |
621 | C<done> state, they will also finish. Otherwise they will continue to |
617 | exist. |
622 | exist. |
… | |
… | |
636 | =item $grp->result (...) |
641 | =item $grp->result (...) |
637 | |
642 | |
638 | Set the result value(s) that will be passed to the group callback when all |
643 | Set the result value(s) that will be passed to the group callback when all |
639 | subrequests have finished. By default, no argument will be passed. |
644 | subrequests have finished. By default, no argument will be passed. |
640 | |
645 | |
|
|
646 | =item $grp->set_feeder ($callback->($grp)) |
|
|
647 | |
|
|
648 | [VERY EXPERIMENTAL] |
|
|
649 | |
|
|
650 | 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, |
|
|
652 | 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 |
|
|
654 | example, C<aio_scandir> might generate hundreds of thousands C<aio_stat> |
|
|
655 | requests, delaying any later requests for a long time. |
|
|
656 | |
|
|
657 | 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 |
|
|
659 | feeder will be called whenever there are few enough (see C<feeder_limit>, |
|
|
660 | below) requests active in the group itself and is expected to queue more |
|
|
661 | requests. |
|
|
662 | |
|
|
663 | The feeder can queue as many requests as it likes (i.e. C<add> does not |
|
|
664 | impose any limits). |
|
|
665 | |
|
|
666 | If the feeder does not queue more requests when called, it will be |
|
|
667 | automatically removed from the group. |
|
|
668 | |
|
|
669 | If the feeder limit is C<0>, it will be set to C<2> automatically. |
|
|
670 | |
|
|
671 | Example: |
|
|
672 | |
|
|
673 | # stat all files in @files, but only ever use four aio requests concurrently: |
|
|
674 | |
|
|
675 | my $grp = aio_group sub { print "finished\n" }; |
|
|
676 | $grp->feeder_limit (4); |
|
|
677 | $grp->set_feeder (sub { |
|
|
678 | my $file = pop @files |
|
|
679 | or return; |
|
|
680 | |
|
|
681 | add $grp aio_stat $file, sub { ... }; |
|
|
682 | }); |
|
|
683 | |
|
|
684 | =item $grp->feeder_limit ($num) |
|
|
685 | |
|
|
686 | Sets the feeder limit for the group: The feeder will be called whenever |
|
|
687 | the group contains less than this many requests. |
|
|
688 | |
|
|
689 | Setting the limit to C<0> will pause the feeding process. |
|
|
690 | |
641 | =back |
691 | =back |
642 | |
692 | |
643 | =head2 SUPPORT FUNCTIONS |
693 | =head2 SUPPORT FUNCTIONS |
644 | |
694 | |
645 | =over 4 |
695 | =over 4 |
… | |
… | |
702 | IO::AIO::poll_wait, IO::AIO::poll_cb |
752 | IO::AIO::poll_wait, IO::AIO::poll_cb |
703 | if IO::AIO::nreqs; |
753 | if IO::AIO::nreqs; |
704 | |
754 | |
705 | =item IO::AIO::min_parallel $nthreads |
755 | =item IO::AIO::min_parallel $nthreads |
706 | |
756 | |
707 | Set the minimum number of AIO threads to C<$nthreads>. The current default |
757 | Set the minimum number of AIO threads to C<$nthreads>. The current |
708 | is C<4>, which means four asynchronous operations can be done at one time |
758 | default is C<8>, which means eight asynchronous operations can execute |
709 | (the number of outstanding operations, however, is unlimited). |
759 | concurrently at any one time (the number of outstanding requests, |
|
|
760 | however, is unlimited). |
710 | |
761 | |
711 | IO::AIO starts threads only on demand, when an AIO request is queued and |
762 | IO::AIO starts threads only on demand, when an AIO request is queued and |
712 | no free thread exists. |
763 | no free thread exists. |
713 | |
764 | |
714 | It is recommended to keep the number of threads low, as some Linux |
765 | It is recommended to keep the number of threads relatively low, as some |
715 | kernel versions will scale negatively with the number of threads (higher |
766 | Linux kernel versions will scale negatively with the number of threads |
716 | parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 |
767 | (higher parallelity => MUCH higher latency). With current Linux 2.6 |
717 | threads should be fine. |
768 | versions, 4-32 threads should be fine. |
718 | |
769 | |
719 | Under most circumstances you don't need to call this function, as the |
770 | Under most circumstances you don't need to call this function, as the |
720 | module selects a default that is suitable for low to moderate load. |
771 | module selects a default that is suitable for low to moderate load. |
721 | |
772 | |
722 | =item IO::AIO::max_parallel $nthreads |
773 | =item IO::AIO::max_parallel $nthreads |
… | |
… | |
763 | or return undef; |
814 | or return undef; |
764 | |
815 | |
765 | *$sym |
816 | *$sym |
766 | } |
817 | } |
767 | |
818 | |
768 | min_parallel 4; |
819 | min_parallel 8; |
769 | |
820 | |
770 | END { |
821 | END { |
771 | max_parallel 0; |
822 | max_parallel 0; |
772 | } |
823 | } |
773 | |
824 | |
… | |
… | |
787 | |
838 | |
788 | In short: the parent will, after a short pause, continue as if fork had |
839 | In short: the parent will, after a short pause, continue as if fork had |
789 | not been called, while the child will act as if IO::AIO has not been used |
840 | not been called, while the child will act as if IO::AIO has not been used |
790 | yet. |
841 | yet. |
791 | |
842 | |
|
|
843 | =head2 MEMORY USAGE |
|
|
844 | |
|
|
845 | Each aio request uses - depending on your architecture - around 128 bytes |
|
|
846 | of memory. In addition, stat requests need a stat buffer (possibly a few |
|
|
847 | hundred bytes). Perl scalars and other data passed into aio requests will |
|
|
848 | also be locked. |
|
|
849 | |
|
|
850 | This is now awfully much, so queuing lots of requests is not usually a |
|
|
851 | problem. |
|
|
852 | |
|
|
853 | Each thread needs a stack area which is usually around 16k, sometimes much |
|
|
854 | larger, depending on the OS. |
|
|
855 | |
792 | =head1 SEE ALSO |
856 | =head1 SEE ALSO |
793 | |
857 | |
794 | L<Coro>, L<Linux::AIO> (obsolete). |
858 | L<Coro>, L<Linux::AIO> (obsolete). |
795 | |
859 | |
796 | =head1 AUTHOR |
860 | =head1 AUTHOR |