ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/IO-AIO/README
(Generate patch)

Comparing IO-AIO/README (file contents):
Revision 1.24 by root, Sun Aug 5 16:45:54 2007 UTC vs.
Revision 1.31 by root, Thu May 29 03:35:03 2008 UTC

24 $req->cancel; # cancel request if still in queue 24 $req->cancel; # cancel request if still in queue
25 25
26 my $grp = aio_group sub { print "all stats done\n" }; 26 my $grp = aio_group sub { print "all stats done\n" };
27 add $grp aio_stat "..." for ...; 27 add $grp aio_stat "..." for ...;
28 28
29 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
30 use AnyEvent::AIO;
31
29 # AnyEvent integration 32 # EV integration
30 open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; 33 my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
31 my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
32 34
33 # Event integration 35 # Event integration
34 Event->io (fd => IO::AIO::poll_fileno, 36 Event->io (fd => IO::AIO::poll_fileno,
35 poll => 'r', 37 poll => 'r',
36 cb => \&IO::AIO::poll_cb); 38 cb => \&IO::AIO::poll_cb);
258 } 260 }
259 }; 261 };
260 262
261 aio_close $fh, $callback->($status) 263 aio_close $fh, $callback->($status)
262 Asynchronously close a file and call the callback with the result 264 Asynchronously close a file and call the callback with the result
263 code. *WARNING:* although accepted, you should not pass in a perl 265 code.
264 filehandle here, as perl will likely close the file descriptor
265 another time when the filehandle is destroyed. Normally, you can
266 safely call perls "close" or just let filehandles go out of scope.
267 266
268 This is supposed to be a bug in the API, so that might change. It's 267 Unfortunately, you can't do this to perl. Perl *insists* very
269 therefore best to avoid this function. 268 strongly on closing the file descriptor associated with the
269 filehandle itself.
270
271 Therefore, "aio_close" will not close the filehandle - instead it
272 will use dup2 to overwrite the file descriptor with the write-end of
273 a pipe (the pipe fd will be created on demand and will be cached).
274
275 Or in other words: the file descriptor will be closed, but it will
276 not be free for reuse until the perl filehandle is closed.
270 277
271 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 278 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
272 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 279 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
273 Reads or writes $length bytes from the specified $fh and $offset 280 Reads or writes $length bytes from the specified $fh and $offset
274 into the scalar given by $data and offset $dataoffset and calls the 281 into the scalar given by $data and offset $dataoffset and calls the
275 callback without the actual number of bytes read (or -1 on error, 282 callback without the actual number of bytes read (or -1 on error,
276 just like the syscall). 283 just like the syscall).
277 284
278 If $offset is undefined, then the current file offset will be used 285 If $offset is undefined, then the current file descriptor offset
279 (and updated), otherwise the file offset will not be changed by 286 will be used (and updated), otherwise the file descriptor offset
280 these calls. 287 will not be changed by these calls.
281 288
282 If $length is undefined in "aio_write", use the remaining length of 289 If $length is undefined in "aio_write", use the remaining length of
283 $data. 290 $data.
284 291
285 If $dataoffset is less than zero, it will be counted from the end of 292 If $dataoffset is less than zero, it will be counted from the end of
521 Delete a directory tree starting (and including) $path, return the 528 Delete a directory tree starting (and including) $path, return the
522 status of the final "rmdir" only. This is a composite request that 529 status of the final "rmdir" only. This is a composite request that
523 uses "aio_scandir" to recurse into and rmdir directories, and unlink 530 uses "aio_scandir" to recurse into and rmdir directories, and unlink
524 everything else. 531 everything else.
525 532
533 aio_sync $callback->($status)
534 Asynchronously call sync and call the callback when finished.
535
526 aio_fsync $fh, $callback->($status) 536 aio_fsync $fh, $callback->($status)
527 Asynchronously call fsync on the given filehandle and call the 537 Asynchronously call fsync on the given filehandle and call the
528 callback with the fsync result code. 538 callback with the fsync result code.
529 539
530 aio_fdatasync $fh, $callback->($status) 540 aio_fdatasync $fh, $callback->($status)
531 Asynchronously call fdatasync on the given filehandle and call the 541 Asynchronously call fdatasync on the given filehandle and call the
532 callback with the fdatasync result code. 542 callback with the fdatasync result code.
533 543
534 If this call isn't available because your OS lacks it or it couldn't 544 If this call isn't available because your OS lacks it or it couldn't
535 be detected, it will be emulated by calling "fsync" instead. 545 be detected, it will be emulated by calling "fsync" instead.
546
547 aio_pathsync $path, $callback->($status)
548 This request tries to open, fsync and close the given path. This is
549 a composite request intended tosync directories after directory
550 operations (E.g. rename). This might not work on all operating
551 systems or have any specific effect, but usually it makes sure that
552 directory changes get written to disc. It works for anything that
553 can be opened for read-only, not just directories.
554
555 Passes 0 when everything went ok, and -1 on error.
536 556
537 aio_group $callback->(...) 557 aio_group $callback->(...)
538 This is a very special aio request: Instead of doing something, it 558 This is a very special aio request: Instead of doing something, it
539 is a container for other aio requests, which is useful if you want 559 is a container for other aio requests, which is useful if you want
540 to bundle many requests into a single, composite, request with a 560 to bundle many requests into a single, composite, request with a
622 }; 642 };
623 643
624 This makes it very easy to create composite requests (see the source of 644 This makes it very easy to create composite requests (see the source of
625 "aio_move" for an application) that work and feel like simple requests. 645 "aio_move" for an application) that work and feel like simple requests.
626 646
627 * The IO::AIO::GRP objects will be cleaned up during calls to 647 * The IO::AIO::GRP objects will be cleaned up during calls to
628 "IO::AIO::poll_cb", just like any other request. 648 "IO::AIO::poll_cb", just like any other request.
649
629 * They can be canceled like any other request. Canceling will cancel not 650 * They can be canceled like any other request. Canceling will cancel
630 only the request itself, but also all requests it contains. 651 not only the request itself, but also all requests it contains.
652
631 * They can also can also be added to other IO::AIO::GRP objects. 653 * They can also can also be added to other IO::AIO::GRP objects.
654
632 * You must not add requests to a group from within the group callback 655 * You must not add requests to a group from within the group callback
633 (or any later time). 656 (or any later time).
634 657
635 Their lifetime, simplified, looks like this: when they are empty, they 658 Their lifetime, simplified, looks like this: when they are empty, they
636 will finish very quickly. If they contain only requests that are in the 659 will finish very quickly. If they contain only requests that are in the
637 "done" state, they will also finish. Otherwise they will continue to 660 "done" state, they will also finish. Otherwise they will continue to
638 exist. 661 exist.
655 request itself. Useful when you queued a lot of events but got a 678 request itself. Useful when you queued a lot of events but got a
656 result early. 679 result early.
657 680
658 $grp->result (...) 681 $grp->result (...)
659 Set the result value(s) that will be passed to the group callback 682 Set the result value(s) that will be passed to the group callback
660 when all subrequests have finished and set thre groups errno to the 683 when all subrequests have finished and set the groups errno to the
661 current value of errno (just like calling "errno" without an error 684 current value of errno (just like calling "errno" without an error
662 number). By default, no argument will be passed and errno is zero. 685 number). By default, no argument will be passed and errno is zero.
663 686
664 $grp->errno ([$errno]) 687 $grp->errno ([$errno])
665 Sets the group errno value to $errno, or the current value of errno 688 Sets the group errno value to $errno, or the current value of errno
724 747
725 See "poll_cb" for an example. 748 See "poll_cb" for an example.
726 749
727 IO::AIO::poll_cb 750 IO::AIO::poll_cb
728 Process some outstanding events on the result pipe. You have to call 751 Process some outstanding events on the result pipe. You have to call
729 this regularly. Returns the number of events processed. Returns 752 this regularly. Returns 0 if all events could be processed, or -1 if
730 immediately when no events are outstanding. The amount of events 753 it returned earlier for whatever reason. Returns immediately when no
754 events are outstanding. The amount of events processed depends on
731 processed depends on the settings of "IO::AIO::max_poll_req" and 755 the settings of "IO::AIO::max_poll_req" and
732 "IO::AIO::max_poll_time". 756 "IO::AIO::max_poll_time".
733 757
734 If not all requests were processed for whatever reason, the 758 If not all requests were processed for whatever reason, the
735 filehandle will still be ready when "poll_cb" returns. 759 filehandle will still be ready when "poll_cb" returns, so normally
760 you don't have to do anything special to have it called later.
736 761
737 Example: Install an Event watcher that automatically calls 762 Example: Install an Event watcher that automatically calls
738 IO::AIO::poll_cb with high priority: 763 IO::AIO::poll_cb with high priority:
739 764
740 Event->io (fd => IO::AIO::poll_fileno, 765 Event->io (fd => IO::AIO::poll_fileno,
846 871
847 The default is probably ok in most situations, especially if thread 872 The default is probably ok in most situations, especially if thread
848 creation is fast. If thread creation is very slow on your system you 873 creation is fast. If thread creation is very slow on your system you
849 might want to use larger values. 874 might want to use larger values.
850 875
851 $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 876 IO::AIO::max_outstanding $maxreqs
852 This is a very bad function to use in interactive programs because 877 This is a very bad function to use in interactive programs because
853 it blocks, and a bad way to reduce concurrency because it is 878 it blocks, and a bad way to reduce concurrency because it is
854 inexact: Better use an "aio_group" together with a feed callback. 879 inexact: Better use an "aio_group" together with a feed callback.
855 880
856 Sets the maximum number of outstanding requests to $nreqs. If you to 881 Sets the maximum number of outstanding requests to $nreqs. If you do
857 queue up more than this number of requests, the next call to the 882 queue up more than this number of requests, the next call to the
858 "poll_cb" (and "poll_some" and other functions calling "poll_cb") 883 "poll_cb" (and "poll_some" and other functions calling "poll_cb")
859 function will block until the limit is no longer exceeded. 884 function will block until the limit is no longer exceeded.
860 885
861 The default value is very large, so there is no practical limit on 886 The default value is very large, so there is no practical limit on
862 the number of outstanding requests. 887 the number of outstanding requests.
863 888
864 You can still queue as many requests as you want. Therefore, 889 You can still queue as many requests as you want. Therefore,
865 "max_oustsanding" is mainly useful in simple scripts (with low 890 "max_outstanding" is mainly useful in simple scripts (with low
866 values) or as a stop gap to shield against fatal memory overflow 891 values) or as a stop gap to shield against fatal memory overflow
867 (with large values). 892 (with large values).
868 893
869 STATISTICAL INFORMATION 894 STATISTICAL INFORMATION
870 IO::AIO::nreqs 895 IO::AIO::nreqs
907 bytes of memory. In addition, stat requests need a stat buffer (possibly 932 bytes of memory. In addition, stat requests need a stat buffer (possibly
908 a few hundred bytes), readdir requires a result buffer and so on. Perl 933 a few hundred bytes), readdir requires a result buffer and so on. Perl
909 scalars and other data passed into aio requests will also be locked and 934 scalars and other data passed into aio requests will also be locked and
910 will consume memory till the request has entered the done state. 935 will consume memory till the request has entered the done state.
911 936
912 This is now awfully much, so queuing lots of requests is not usually a 937 This is not awfully much, so queuing lots of requests is not usually a
913 problem. 938 problem.
914 939
915 Per-thread usage: 940 Per-thread usage:
916 941
917 In the execution phase, some aio requests require more memory for 942 In the execution phase, some aio requests require more memory for
920 945
921KNOWN BUGS 946KNOWN BUGS
922 Known bugs will be fixed in the next release. 947 Known bugs will be fixed in the next release.
923 948
924SEE ALSO 949SEE ALSO
925 Coro::AIO. 950 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
951 more natural syntax.
926 952
927AUTHOR 953AUTHOR
928 Marc Lehmann <schmorp@schmorp.de> 954 Marc Lehmann <schmorp@schmorp.de>
929 http://home.schmorp.de/ 955 http://home.schmorp.de/
930 956

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines