[ViewVC] Diff of: cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.156 by root, Tue Jun 16 23:41:59 2009 UTC vs.
Revision 1.201 by root, Tue Jul 5 09:24:11 2011 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10	my $fh = shift	10	my $fh = shift
11	or die "/etc/passwd: $!";	11	or die "/etc/passwd: $!";
12	...	12	...
13	};	13	};
14		14
…		…
25	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
26	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
27		27
28	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
29	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
30
31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32	use AnyEvent::AIO;
33
34	# EV integration
35	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
36
37	# Event integration
38	Event->io (fd => IO::AIO::poll_fileno,
39	poll => 'r',
40	cb => \&IO::AIO::poll_cb);
41
42	# Glib/Gtk2 integration
43	add_watch Glib::IO IO::AIO::poll_fileno,
44	in => sub { IO::AIO::poll_cb; 1 };
45
46	# Tk integration
47	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
48	readable => \&IO::AIO::poll_cb);
49
50	# Danga::Socket integration
51	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
52	\&IO::AIO::poll_cb);
53		30
54	=head1 DESCRIPTION	31	=head1 DESCRIPTION
55		32
56	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
57	operating system supports. It is implemented as an interface to C<libeio>	34	operating system supports. It is implemented as an interface to C<libeio>
…		…
99		76
100	# register the IO::AIO callback with EV	77	# register the IO::AIO callback with EV
101	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
102		79
103	# queue the request to open /etc/passwd	80	# queue the request to open /etc/passwd
104	aio_open "/etc/passwd", O_RDONLY, 0, sub {	81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
105	my $fh = shift	82	my $fh = shift
106	or die "error while opening: $!";	83	or die "error while opening: $!";
107		84
108	# stat'ing filehandles is generally non-blocking	85	# stat'ing filehandles is generally non-blocking
109	my $size = -s $fh;	86	my $size = -s $fh;
…		…
186		163
187	package IO::AIO;	164	package IO::AIO;
188		165
189	use Carp ();	166	use Carp ();
190		167
191	no warnings;	168	use common::sense;
192	use strict 'vars';
193		169
194	use base 'Exporter';	170	use base 'Exporter';
195		171
196	BEGIN {	172	BEGIN {
197	our $VERSION = '3.23';	173	our $VERSION = '3.93';
198		174
199	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
200	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
201	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync aio_fsync
202	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
203	aio_rename aio_link aio_move aio_copy aio_group	179	aio_rename aio_link aio_move aio_copy aio_group
204	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
205	aio_chmod aio_utime aio_truncate);	181	aio_chmod aio_utime aio_truncate
		182	aio_msync aio_mtouch aio_mlock aio_mlockall
		183	aio_statvfs);
206		184
207	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
208	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
209	min_parallel max_parallel max_idle	187	min_parallel max_parallel max_idle idle_timeout
210	nreqs nready npending nthreads	188	nreqs nready npending nthreads
211	max_poll_time max_poll_reqs);	189	max_poll_time max_poll_reqs
		190	sendfile fadvise madvise
		191	mmap munmap munlock munlockall);
212		192
213	push @AIO_REQ, qw(aio_busy); # not exported	193	push @AIO_REQ, qw(aio_busy); # not exported
214		194
215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
216		196
217	require XSLoader;	197	require XSLoader;
218	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
219	}	199	}
220		200
221	=head1 FUNCTIONS	201	=head1 FUNCTIONS
		202
		203	=head2 QUICK OVERVIEW
		204
		205	This section simply lists the prototypes of the most important functions
		206	for quick reference. See the following sections for function-by-function
		207	documentation.
		208
		209	aio_open $pathname, $flags, $mode, $callback->($fh)
		210	aio_close $fh, $callback->($status)
		211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		214	aio_readahead $fh,$offset,$length, $callback->($retval)
		215	aio_stat $fh_or_path, $callback->($status)
		216	aio_lstat $fh, $callback->($status)
		217	aio_statvfs $fh_or_path, $callback->($statvfs)
		218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		220	aio_truncate $fh_or_path, $offset, $callback->($status)
		221	aio_chmod $fh_or_path, $mode, $callback->($status)
		222	aio_unlink $pathname, $callback->($status)
		223	aio_mknod $path, $mode, $dev, $callback->($status)
		224	aio_link $srcpath, $dstpath, $callback->($status)
		225	aio_symlink $srcpath, $dstpath, $callback->($status)
		226	aio_readlink $path, $callback->($link)
		227	aio_realpath $path, $callback->($link)
		228	aio_rename $srcpath, $dstpath, $callback->($status)
		229	aio_mkdir $pathname, $mode, $callback->($status)
		230	aio_rmdir $pathname, $callback->($status)
		231	aio_readdir $pathname, $callback->($entries)
		232	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		233	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		234	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		235	aio_load $path, $data, $callback->($status)
		236	aio_copy $srcpath, $dstpath, $callback->($status)
		237	aio_move $srcpath, $dstpath, $callback->($status)
		238	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		239	aio_rmtree $path, $callback->($status)
		240	aio_sync $callback->($status)
		241	aio_fsync $fh, $callback->($status)
		242	aio_fdatasync $fh, $callback->($status)
		243	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		244	aio_pathsync $path, $callback->($status)
		245	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		246	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		247	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		248	aio_mlockall $flags, $callback->($status)
		249	aio_group $callback->(...)
		250	aio_nop $callback->()
		251
		252	$prev_pri = aioreq_pri [$pri]
		253	aioreq_nice $pri_adjust
		254
		255	IO::AIO::poll_wait
		256	IO::AIO::poll_cb
		257	IO::AIO::poll
		258	IO::AIO::flush
		259	IO::AIO::max_poll_reqs $nreqs
		260	IO::AIO::max_poll_time $seconds
		261	IO::AIO::min_parallel $nthreads
		262	IO::AIO::max_parallel $nthreads
		263	IO::AIO::max_idle $nthreads
		264	IO::AIO::idle_timeout $seconds
		265	IO::AIO::max_outstanding $maxreqs
		266	IO::AIO::nreqs
		267	IO::AIO::nready
		268	IO::AIO::npending
		269
		270	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		271	IO::AIO::fadvise $fh, $offset, $len, $advice
		272	IO::AIO::madvise $scalar, $offset, $length, $advice
		273	IO::AIO::mprotect $scalar, $offset, $length, $protect
		274	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		275	IO::AIO::munlockall
222		276
223	=head2 AIO REQUEST FUNCTIONS	277	=head2 AIO REQUEST FUNCTIONS
224		278
225	All the C<aio_*> calls are more or less thin wrappers around the syscall	279	All the C<aio_*> calls are more or less thin wrappers around the syscall
226	with the same name (sans C<aio_>). The arguments are similar or identical,	280	with the same name (sans C<aio_>). The arguments are similar or identical,
…		…
306	by the umask in effect then the request is being executed, so better never	360	by the umask in effect then the request is being executed, so better never
307	change the umask.	361	change the umask.
308		362
309	Example:	363	Example:
310		364
311	aio_open "/etc/passwd", O_RDONLY, 0, sub {	365	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
312	if ($_[0]) {	366	if ($_[0]) {
313	print "open successful, fh is $_[0]\n";	367	print "open successful, fh is $_[0]\n";
314	...	368	...
315	} else {	369	} else {
316	die "open failed: $!\n";	370	die "open failed: $!\n";
317	}	371	}
318	};	372	};
319		373
		374	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		375	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		376	following POSIX and non-POSIX constants are available (missing ones on
		377	your system are, as usual, C<0>):
		378
		379	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		380	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		381	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		382
320		383
321	=item aio_close $fh, $callback->($status)	384	=item aio_close $fh, $callback->($status)
322		385
323	Asynchronously close a file and call the callback with the result	386	Asynchronously close a file and call the callback with the result
324	code.	387	code.
…		…
374		437
375	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	438	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
376	reading at byte offset C<$in_offset>, and starts writing at the current	439	reading at byte offset C<$in_offset>, and starts writing at the current
377	file offset of C<$out_fh>. Because of that, it is not safe to issue more	440	file offset of C<$out_fh>. Because of that, it is not safe to issue more
378	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	441	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
379	other.	442	other. The same C<$in_fh> works fine though, as this function does not
		443	move or use the file offset of C<$in_fh>.
380		444
		445	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		446	are written, and there is no way to find out how many more bytes have been
		447	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		448	number of bytes written to C<$out_fh>. Only if the result value equals
		449	C<$length> one can assume that C<$length> bytes have been read.
		450
		451	Unlike with other C<aio_> functions, it makes a lot of sense to use
		452	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		453	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		454	the socket I/O will be non-blocking. Note, however, that you can run
		455	into a trap where C<aio_sendfile> reads some data with readahead, then
		456	fails to write all data, and when the socket is ready the next time, the
		457	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		458	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		459	resource usage.
		460
381	This call tries to make use of a native C<sendfile> syscall to provide	461	This call tries to make use of a native C<sendfile>-like syscall to
382	zero-copy operation. For this to work, C<$out_fh> should refer to a	462	provide zero-copy operation. For this to work, C<$out_fh> should refer to
383	socket, and C<$in_fh> should refer to mmap'able file.	463	a socket, and C<$in_fh> should refer to an mmap'able file.
384		464
385	If the native sendfile call fails or is not implemented, it will be	465	If a native sendfile cannot be found or it fails with C<ENOSYS>,
386	emulated, so you can call C<aio_sendfile> on any type of filehandle	466	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		467	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
387	regardless of the limitations of the operating system.	468	type of filehandle regardless of the limitations of the operating system.
388		469
389	Please note, however, that C<aio_sendfile> can read more bytes from	470	As native sendfile syscalls (as practically any non-POSIX interface hacked
390	C<$in_fh> than are written, and there is no way to find out how many	471	together in a hurry to improve benchmark numbers) tend to be rather buggy
391	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	472	on many systems, this implementation tries to work around some known bugs
392	provides the number of bytes written to C<$out_fh>. Only if the result	473	in Linux and FreeBSD kernels (probably others, too), but that might fail,
393	value equals C<$length> one can assume that C<$length> bytes have been	474	so you really really should check the return value of C<aio_sendfile> -
394	read.	475	fewre bytes than expected might have been transferred.
395		476
396		477
397	=item aio_readahead $fh,$offset,$length, $callback->($retval)	478	=item aio_readahead $fh,$offset,$length, $callback->($retval)
398		479
399	C<aio_readahead> populates the page cache with data from a file so that	480	C<aio_readahead> populates the page cache with data from a file so that
…		…
422		503
423	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	504	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
424	error when stat'ing a large file, the results will be silently truncated	505	error when stat'ing a large file, the results will be silently truncated
425	unless perl itself is compiled with large file support.	506	unless perl itself is compiled with large file support.
426		507
		508	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		509	following constants and functions (if not implemented, the constants will
		510	be C<0> and the functions will either C<croak> or fall back on traditional
		511	behaviour).
		512
		513	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		514	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		515	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		516
427	Example: Print the length of F</etc/passwd>:	517	Example: Print the length of F</etc/passwd>:
428		518
429	aio_stat "/etc/passwd", sub {	519	aio_stat "/etc/passwd", sub {
430	$_[0] and die "stat failed: $!";	520	$_[0] and die "stat failed: $!";
431	print "size is ", -s _, "\n";	521	print "size is ", -s _, "\n";
432	};	522	};
433		523
434		524
		525	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		526
		527	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		528	whether a file handle or path was passed.
		529
		530	On success, the callback is passed a hash reference with the following
		531	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		532	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		533	is passed.
		534
		535	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		536	C<ST_NOSUID>.
		537
		538	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		539	their correct value when available, or to C<0> on systems that do
		540	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		541	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		542	C<ST_NODIRATIME> and C<ST_RELATIME>.
		543
		544	Example: stat C</wd> and dump out the data if successful.
		545
		546	aio_statvfs "/wd", sub {
		547	my $f = $_[0]
		548	or die "statvfs: $!";
		549
		550	use Data::Dumper;
		551	say Dumper $f;
		552	};
		553
		554	# result:
		555	{
		556	bsize => 1024,
		557	bfree => 4333064312,
		558	blocks => 10253828096,
		559	files => 2050765568,
		560	flag => 4096,
		561	favail => 2042092649,
		562	bavail => 4333064312,
		563	ffree => 2042092649,
		564	namemax => 255,
		565	frsize => 1024,
		566	fsid => 1810
		567	}
		568
		569
435	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	570	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
436		571
437	Works like perl's C<utime> function (including the special case of $atime	572	Works like perl's C<utime> function (including the special case of $atime
438	and $mtime being undef). Fractional times are supported if the underlying	573	and $mtime being undef). Fractional times are supported if the underlying
439	syscalls support them.	574	syscalls support them.
…		…
487		622
488	The only (POSIX-) portable way of calling this function is:	623	The only (POSIX-) portable way of calling this function is:
489		624
490	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	625	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
491		626
		627	See C<aio_stat> for info about some potentially helpful extra constants
		628	and functions.
492		629
493	=item aio_link $srcpath, $dstpath, $callback->($status)	630	=item aio_link $srcpath, $dstpath, $callback->($status)
494		631
495	Asynchronously create a new link to the existing object at C<$srcpath> at	632	Asynchronously create a new link to the existing object at C<$srcpath> at
496	the path C<$dstpath> and call the callback with the result code.	633	the path C<$dstpath> and call the callback with the result code.
…		…
507	Asynchronously read the symlink specified by C<$path> and pass it to	644	Asynchronously read the symlink specified by C<$path> and pass it to
508	the callback. If an error occurs, nothing or undef gets passed to the	645	the callback. If an error occurs, nothing or undef gets passed to the
509	callback.	646	callback.
510		647
511		648
		649	=item aio_realpath $path, $callback->($path)
		650
		651	Asynchronously make the path absolute and resolve any symlinks in
		652	C<$path>. The resulting path only consists of directories.
		653
		654	This request can be used to get the absolute path of the current working
		655	directory by passing it a path of F<.> (a single dot).
		656
		657
512	=item aio_rename $srcpath, $dstpath, $callback->($status)	658	=item aio_rename $srcpath, $dstpath, $callback->($status)
513		659
514	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	660	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
515	rename(2) and call the callback with the result code.	661	rename(2) and call the callback with the result code.
516		662
…		…
549		695
550	=over 4	696	=over 4
551		697
552	=item IO::AIO::READDIR_DENTS	698	=item IO::AIO::READDIR_DENTS
553		699
554	When this flag is off, then the callback gets an arrayref with of names	700	When this flag is off, then the callback gets an arrayref consisting of
555	only (as with C<aio_readdir>), otherwise it gets an arrayref with	701	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
556	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	702	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
557	entry in more detail.	703	entry in more detail.
558		704
559	C<$name> is the name of the entry.	705	C<$name> is the name of the entry.
560		706
…		…
573	systems that do not deliver the inode information.	719	systems that do not deliver the inode information.
574		720
575	=item IO::AIO::READDIR_DIRS_FIRST	721	=item IO::AIO::READDIR_DIRS_FIRST
576		722
577	When this flag is set, then the names will be returned in an order where	723	When this flag is set, then the names will be returned in an order where
578	likely directories come first. This is useful when you need to quickly	724	likely directories come first, in optimal stat order. This is useful when
579	find directories, or you want to find all directories while avoiding to	725	you need to quickly find directories, or you want to find all directories
580	stat() each entry.	726	while avoiding to stat() each entry.
581		727
582	If the system returns type information in readdir, then this is used	728	If the system returns type information in readdir, then this is used
583	to find directories directly. Otherwise, likely directories are files	729	to find directories directly. Otherwise, likely directories are names
584	beginning with ".", or otherwise files with no dots, of which files with	730	beginning with ".", or otherwise names with no dots, of which names with
585	short names are tried first.	731	short names are tried first.
586		732
587	=item IO::AIO::READDIR_STAT_ORDER	733	=item IO::AIO::READDIR_STAT_ORDER
588		734
589	When this flag is set, then the names will be returned in an order	735	When this flag is set, then the names will be returned in an order
…		…
634		780
635	=item aio_copy $srcpath, $dstpath, $callback->($status)	781	=item aio_copy $srcpath, $dstpath, $callback->($status)
636		782
637	Try to copy the I<file> (directories not supported as either source or	783	Try to copy the I<file> (directories not supported as either source or
638	destination) from C<$srcpath> to C<$dstpath> and call the callback with	784	destination) from C<$srcpath> to C<$dstpath> and call the callback with
639	the C<0> (error) or C<-1> ok.	785	a status of C<0> (ok) or C<-1> (error, see C<$!>).
640		786
641	This is a composite request that creates the destination file with	787	This is a composite request that creates the destination file with
642	mode 0200 and copies the contents of the source file into it using	788	mode 0200 and copies the contents of the source file into it using
643	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	789	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
644	uid/gid, in that order.	790	uid/gid, in that order.
…		…
656	my $grp = aio_group $cb;	802	my $grp = aio_group $cb;
657		803
658	aioreq_pri $pri;	804	aioreq_pri $pri;
659	add $grp aio_open $src, O_RDONLY, 0, sub {	805	add $grp aio_open $src, O_RDONLY, 0, sub {
660	if (my $src_fh = $_[0]) {	806	if (my $src_fh = $_[0]) {
661	my @stat = stat $src_fh; # hmm, might bock over nfs?	807	my @stat = stat $src_fh; # hmm, might block over nfs?
662		808
663	aioreq_pri $pri;	809	aioreq_pri $pri;
664	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {	810	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
665	if (my $dst_fh = $_[0]) {	811	if (my $dst_fh = $_[0]) {
666	aioreq_pri $pri;	812	aioreq_pri $pri;
…		…
713		859
714	=item aio_move $srcpath, $dstpath, $callback->($status)	860	=item aio_move $srcpath, $dstpath, $callback->($status)
715		861
716	Try to move the I<file> (directories not supported as either source or	862	Try to move the I<file> (directories not supported as either source or
717	destination) from C<$srcpath> to C<$dstpath> and call the callback with	863	destination) from C<$srcpath> to C<$dstpath> and call the callback with
718	the C<0> (error) or C<-1> ok.	864	a status of C<0> (ok) or C<-1> (error, see C<$!>).
719		865
720	This is a composite request that tries to rename(2) the file first; if	866	This is a composite request that tries to rename(2) the file first; if
721	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if	867	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
722	that is successful, unlinks the C<$srcpath>.	868	that is successful, unlinks the C<$srcpath>.
723		869
…		…
734	if ($_[0] && $! == EXDEV) {	880	if ($_[0] && $! == EXDEV) {
735	aioreq_pri $pri;	881	aioreq_pri $pri;
736	add $grp aio_copy $src, $dst, sub {	882	add $grp aio_copy $src, $dst, sub {
737	$grp->result ($_[0]);	883	$grp->result ($_[0]);
738		884
739	if (!$_[0]) {	885	unless ($_[0]) {
740	aioreq_pri $pri;	886	aioreq_pri $pri;
741	add $grp aio_unlink $src;	887	add $grp aio_unlink $src;
742	}	888	}
743	};	889	};
744	} else {	890	} else {
…		…
957	(E.g. rename). This might not work on all operating systems or have any	1103	(E.g. rename). This might not work on all operating systems or have any
958	specific effect, but usually it makes sure that directory changes get	1104	specific effect, but usually it makes sure that directory changes get
959	written to disc. It works for anything that can be opened for read-only,	1105	written to disc. It works for anything that can be opened for read-only,
960	not just directories.	1106	not just directories.
961		1107
		1108	Future versions of this function might fall back to other methods when
		1109	C<fsync> on the directory fails (such as calling C<sync>).
		1110
962	Passes C<0> when everything went ok, and C<-1> on error.	1111	Passes C<0> when everything went ok, and C<-1> on error.
963		1112
964	=cut	1113	=cut
965		1114
966	sub aio_pathsync($;$) {	1115	sub aio_pathsync($;$) {
…		…
986	};	1135	};
987		1136
988	$grp	1137	$grp
989	}	1138	}
990		1139
		1140	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1141
		1142	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1143	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1144	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1145	scalar must only be modified in-place while an aio operation is pending on
		1146	it).
		1147
		1148	It calls the C<msync> function of your OS, if available, with the memory
		1149	area starting at C<$offset> in the string and ending C<$length> bytes
		1150	later. If C<$length> is negative, counts from the end, and if C<$length>
		1151	is C<undef>, then it goes till the end of the string. The flags can be
		1152	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1153	C<IO::AIO::MS_SYNC>.
		1154
		1155	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1156
		1157	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1158	scalars.
		1159
		1160	It touches (reads or writes) all memory pages in the specified
		1161	range inside the scalar. All caveats and parameters are the same
		1162	as for C<aio_msync>, above, except for flags, which must be either
		1163	C<0> (which reads all pages and ensures they are instantiated) or
		1164	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1165	writing an octet from it, which dirties the page).
		1166
		1167	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1168
		1169	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1170	scalars.
		1171
		1172	It reads in all the pages of the underlying storage into memory (if any)
		1173	and locks them, so they are not getting swapped/paged out or removed.
		1174
		1175	If C<$length> is undefined, then the scalar will be locked till the end.
		1176
		1177	On systems that do not implement C<mlock>, this function returns C<-1>
		1178	and sets errno to C<ENOSYS>.
		1179
		1180	Note that the corresponding C<munlock> is synchronous and is
		1181	documented under L<MISCELLANEOUS FUNCTIONS>.
		1182
		1183	Example: open a file, mmap and mlock it - both will be undone when
		1184	C<$data> gets destroyed.
		1185
		1186	open my $fh, "<", $path or die "$path: $!";
		1187	my $data;
		1188	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1189	aio_mlock $data; # mlock in background
		1190
		1191	=item aio_mlockall $flags, $callback->($status)
		1192
		1193	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1194	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1195
		1196	On systems that do not implement C<mlockall>, this function returns C<-1>
		1197	and sets errno to C<ENOSYS>.
		1198
		1199	Note that the corresponding C<munlockall> is synchronous and is
		1200	documented under L<MISCELLANEOUS FUNCTIONS>.
		1201
		1202	Example: asynchronously lock all current and future pages into memory.
		1203
		1204	aio_mlockall IO::AIO::MCL_FUTURE;
		1205
991	=item aio_group $callback->(...)	1206	=item aio_group $callback->(...)
992		1207
993	This is a very special aio request: Instead of doing something, it is a	1208	This is a very special aio request: Instead of doing something, it is a
994	container for other aio requests, which is useful if you want to bundle	1209	container for other aio requests, which is useful if you want to bundle
995	many requests into a single, composite, request with a definite callback	1210	many requests into a single, composite, request with a definite callback
…		…
1130	=item $grp->cancel_subs	1345	=item $grp->cancel_subs
1131		1346
1132	Cancel all subrequests and clears any feeder, but not the group request	1347	Cancel all subrequests and clears any feeder, but not the group request
1133	itself. Useful when you queued a lot of events but got a result early.	1348	itself. Useful when you queued a lot of events but got a result early.
1134		1349
		1350	The group request will finish normally (you cannot add requests to the
		1351	group).
		1352
1135	=item $grp->result (...)	1353	=item $grp->result (...)
1136		1354
1137	Set the result value(s) that will be passed to the group callback when all	1355	Set the result value(s) that will be passed to the group callback when all
1138	subrequests have finished and set the groups errno to the current value	1356	subrequests have finished and set the groups errno to the current value
1139	of errno (just like calling C<errno> without an error number). By default,	1357	of errno (just like calling C<errno> without an error number). By default,
…		…
1215		1433
1216	See C<poll_cb> for an example.	1434	See C<poll_cb> for an example.
1217		1435
1218	=item IO::AIO::poll_cb	1436	=item IO::AIO::poll_cb
1219		1437
1220	Process some outstanding events on the result pipe. You have to call this	1438	Process some outstanding events on the result pipe. You have to call
1221	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1439	this regularly. Returns C<0> if all events could be processed (or there
1222	returned earlier for whatever reason. Returns immediately when no events	1440	were no events to process), or C<-1> if it returned earlier for whatever
1223	are outstanding. The amount of events processed depends on the settings of	1441	reason. Returns immediately when no events are outstanding. The amount of
1224	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1442	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1443	C<IO::AIO::max_poll_time>.
1225		1444
1226	If not all requests were processed for whatever reason, the filehandle	1445	If not all requests were processed for whatever reason, the filehandle
1227	will still be ready when C<poll_cb> returns, so normally you don't have to	1446	will still be ready when C<poll_cb> returns, so normally you don't have to
1228	do anything special to have it called later.	1447	do anything special to have it called later.
1229		1448
		1449	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1450	ready, it can be beneficial to call this function from loops which submit
		1451	a lot of requests, to make sure the results get processed when they become
		1452	available and not just when the loop is finished and the event loop takes
		1453	over again. This function returns very fast when there are no outstanding
		1454	requests.
		1455
1230	Example: Install an Event watcher that automatically calls	1456	Example: Install an Event watcher that automatically calls
1231	IO::AIO::poll_cb with high priority (more examples can be found in the	1457	IO::AIO::poll_cb with high priority (more examples can be found in the
1232	SYNOPSIS section, at the top of this document):	1458	SYNOPSIS section, at the top of this document):
1233		1459
1234	Event->io (fd => IO::AIO::poll_fileno,	1460	Event->io (fd => IO::AIO::poll_fileno,
1235	poll => 'r', async => 1,	1461	poll => 'r', async => 1,
1236	cb => \&IO::AIO::poll_cb);	1462	cb => \&IO::AIO::poll_cb);
		1463
		1464	=item IO::AIO::poll_wait
		1465
		1466	If there are any outstanding requests and none of them in the result
		1467	phase, wait till the result filehandle becomes ready for reading (simply
		1468	does a C<select> on the filehandle. This is useful if you want to
		1469	synchronously wait for some requests to finish).
		1470
		1471	See C<nreqs> for an example.
		1472
		1473	=item IO::AIO::poll
		1474
		1475	Waits until some requests have been handled.
		1476
		1477	Returns the number of requests processed, but is otherwise strictly
		1478	equivalent to:
		1479
		1480	IO::AIO::poll_wait, IO::AIO::poll_cb
		1481
		1482	=item IO::AIO::flush
		1483
		1484	Wait till all outstanding AIO requests have been handled.
		1485
		1486	Strictly equivalent to:
		1487
		1488	IO::AIO::poll_wait, IO::AIO::poll_cb
		1489	while IO::AIO::nreqs;
1237		1490
1238	=item IO::AIO::max_poll_reqs $nreqs	1491	=item IO::AIO::max_poll_reqs $nreqs
1239		1492
1240	=item IO::AIO::max_poll_time $seconds	1493	=item IO::AIO::max_poll_time $seconds
1241		1494
…		…
1266	# use a low priority so other tasks have priority	1519	# use a low priority so other tasks have priority
1267	Event->io (fd => IO::AIO::poll_fileno,	1520	Event->io (fd => IO::AIO::poll_fileno,
1268	poll => 'r', nice => 1,	1521	poll => 'r', nice => 1,
1269	cb => &IO::AIO::poll_cb);	1522	cb => &IO::AIO::poll_cb);
1270		1523
1271	=item IO::AIO::poll_wait
1272
1273	If there are any outstanding requests and none of them in the result
1274	phase, wait till the result filehandle becomes ready for reading (simply
1275	does a C<select> on the filehandle. This is useful if you want to
1276	synchronously wait for some requests to finish).
1277
1278	See C<nreqs> for an example.
1279
1280	=item IO::AIO::poll
1281
1282	Waits until some requests have been handled.
1283
1284	Returns the number of requests processed, but is otherwise strictly
1285	equivalent to:
1286
1287	IO::AIO::poll_wait, IO::AIO::poll_cb
1288
1289	=item IO::AIO::flush
1290
1291	Wait till all outstanding AIO requests have been handled.
1292
1293	Strictly equivalent to:
1294
1295	IO::AIO::poll_wait, IO::AIO::poll_cb
1296	while IO::AIO::nreqs;
1297
1298	=back	1524	=back
1299		1525
1300	=head3 CONTROLLING THE NUMBER OF THREADS	1526	=head3 CONTROLLING THE NUMBER OF THREADS
1301		1527
1302	=over	1528	=over
…		…
1335		1561
1336	Under normal circumstances you don't need to call this function.	1562	Under normal circumstances you don't need to call this function.
1337		1563
1338	=item IO::AIO::max_idle $nthreads	1564	=item IO::AIO::max_idle $nthreads
1339		1565
1340	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1566	Limit the number of threads (default: 4) that are allowed to idle
1341	threads that did not get a request to process within 10 seconds). That	1567	(i.e., threads that did not get a request to process within the idle
1342	means if a thread becomes idle while C<$nthreads> other threads are also	1568	timeout (default: 10 seconds). That means if a thread becomes idle while
1343	idle, it will free its resources and exit.	1569	C<$nthreads> other threads are also idle, it will free its resources and
		1570	exit.
1344		1571
1345	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1572	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1346	to allow for extremely high load situations, but want to free resources	1573	to allow for extremely high load situations, but want to free resources
1347	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1574	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1348		1575
1349	The default is probably ok in most situations, especially if thread	1576	The default is probably ok in most situations, especially if thread
1350	creation is fast. If thread creation is very slow on your system you might	1577	creation is fast. If thread creation is very slow on your system you might
1351	want to use larger values.	1578	want to use larger values.
1352		1579
		1580	=item IO::AIO::idle_timeout $seconds
		1581
		1582	Sets the minimum idle timeout (default 10) after which worker threads are
		1583	allowed to exit. SEe C<IO::AIO::max_idle>.
		1584
1353	=item IO::AIO::max_outstanding $maxreqs	1585	=item IO::AIO::max_outstanding $maxreqs
		1586
		1587	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1588	you do queue up more than this number of requests, the next call to
		1589	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1590	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1591	longer exceeded.
		1592
		1593	In other words, this setting does not enforce a queue limit, but can be
		1594	used to make poll functions block if the limit is exceeded.
1354		1595
1355	This is a very bad function to use in interactive programs because it	1596	This is a very bad function to use in interactive programs because it
1356	blocks, and a bad way to reduce concurrency because it is inexact: Better	1597	blocks, and a bad way to reduce concurrency because it is inexact: Better
1357	use an C<aio_group> together with a feed callback.	1598	use an C<aio_group> together with a feed callback.
1358		1599
1359	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1600	It's main use is in scripts without an event loop - when you want to stat
1360	do queue up more than this number of requests, the next call to the	1601	a lot of files, you can write somehting like this:
1361	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1362	function will block until the limit is no longer exceeded.
1363		1602
1364	The default value is very large, so there is no practical limit on the	1603	IO::AIO::max_outstanding 32;
1365	number of outstanding requests.
1366		1604
1367	You can still queue as many requests as you want. Therefore,	1605	for my $path (...) {
1368	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1606	aio_stat $path , ...;
1369	as a stop gap to shield against fatal memory overflow (with large values).	1607	IO::AIO::poll_cb;
		1608	}
		1609
		1610	IO::AIO::flush;
		1611
		1612	The call to C<poll_cb> inside the loop will normally return instantly, but
		1613	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1614	some requests have been handled. This keeps the loop from pushing a large
		1615	number of C<aio_stat> requests onto the queue.
		1616
		1617	The default value for C<max_outstanding> is very large, so there is no
		1618	practical limit on the number of outstanding requests.
1370		1619
1371	=back	1620	=back
1372		1621
1373	=head3 STATISTICAL INFORMATION	1622	=head3 STATISTICAL INFORMATION
1374		1623
…		…
1394	Returns the number of requests currently in the pending state (executed,	1643	Returns the number of requests currently in the pending state (executed,
1395	but not yet processed by poll_cb).	1644	but not yet processed by poll_cb).
1396		1645
1397	=back	1646	=back
1398		1647
		1648	=head3 MISCELLANEOUS FUNCTIONS
		1649
		1650	IO::AIO implements some functions that might be useful, but are not
		1651	asynchronous.
		1652
		1653	=over 4
		1654
		1655	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1656
		1657	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1658	but is blocking (this makes most sense if you know the input data is
		1659	likely cached already and the output filehandle is set to non-blocking
		1660	operations).
		1661
		1662	Returns the number of bytes copied, or C<-1> on error.
		1663
		1664	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1665
		1666	Simply calls the C<posix_fadvise> function (see its
		1667	manpage for details). The following advice constants are
		1668	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1669	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1670	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1671
		1672	On systems that do not implement C<posix_fadvise>, this function returns
		1673	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1674
		1675	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1676
		1677	Simply calls the C<posix_madvise> function (see its
		1678	manpage for details). The following advice constants are
		1679	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1680	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1681
		1682	On systems that do not implement C<posix_madvise>, this function returns
		1683	ENOSYS, otherwise the return value of C<posix_madvise>.
		1684
		1685	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1686
		1687	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1688	$scalar (see its manpage for details). The following protect
		1689	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1690	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1691
		1692	On systems that do not implement C<mprotect>, this function returns
		1693	ENOSYS, otherwise the return value of C<mprotect>.
		1694
		1695	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1696
		1697	Memory-maps a file (or anonymous memory range) and attaches it to the
		1698	given C<$scalar>, which will act like a string scalar.
		1699
		1700	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1701	change the string length, and most read-only operations such as copying it
		1702	or searching it with regexes and so on.
		1703
		1704	Anything else is unsafe and will, at best, result in memory leaks.
		1705
		1706	The memory map associated with the C<$scalar> is automatically removed
		1707	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1708	C<IO::AIO::munmap> functions are called.
		1709
		1710	This calls the C<mmap>(2) function internally. See your system's manual
		1711	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1712
		1713	The C<$length> must be larger than zero and smaller than the actual
		1714	filesize.
		1715
		1716	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1717	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1718
		1719	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1720	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1721	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1722	(which is set to C<MAP_ANON> if your system only provides this
		1723	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1724	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1725	C<IO::AIO::MAP_NONBLOCK>
		1726
		1727	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1728
		1729	C<$offset> is the offset from the start of the file - it generally must be
		1730	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1731
		1732	Example:
		1733
		1734	use Digest::MD5;
		1735	use IO::AIO;
		1736
		1737	open my $fh, "<verybigfile"
		1738	or die "$!";
		1739
		1740	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1741	or die "verybigfile: $!";
		1742
		1743	my $fast_md5 = md5 $data;
		1744
		1745	=item IO::AIO::munmap $scalar
		1746
		1747	Removes a previous mmap and undefines the C<$scalar>.
		1748
		1749	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1750
		1751	Calls the C<munlock> function, undoing the effects of a previous
		1752	C<aio_mlock> call (see its description for details).
		1753
		1754	=item IO::AIO::munlockall
		1755
		1756	Calls the C<munlockall> function.
		1757
		1758	On systems that do not implement C<munlockall>, this function returns
		1759	ENOSYS, otherwise the return value of C<munlockall>.
		1760
		1761	=back
		1762
1399	=cut	1763	=cut
1400		1764
1401	min_parallel 8;	1765	min_parallel 8;
1402		1766
1403	END { flush }	1767	END { flush }
1404		1768
1405	1;	1769	1;
1406		1770
		1771	=head1 EVENT LOOP INTEGRATION
		1772
		1773	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1774	automatically into many event loops:
		1775
		1776	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1777	use AnyEvent::AIO;
		1778
		1779	You can also integrate IO::AIO manually into many event loops, here are
		1780	some examples of how to do this:
		1781
		1782	# EV integration
		1783	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1784
		1785	# Event integration
		1786	Event->io (fd => IO::AIO::poll_fileno,
		1787	poll => 'r',
		1788	cb => \&IO::AIO::poll_cb);
		1789
		1790	# Glib/Gtk2 integration
		1791	add_watch Glib::IO IO::AIO::poll_fileno,
		1792	in => sub { IO::AIO::poll_cb; 1 };
		1793
		1794	# Tk integration
		1795	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1796	readable => \&IO::AIO::poll_cb);
		1797
		1798	# Danga::Socket integration
		1799	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1800	\&IO::AIO::poll_cb);
		1801
1407	=head2 FORK BEHAVIOUR	1802	=head2 FORK BEHAVIOUR
1408		1803
1409	This module should do "the right thing" when the process using it forks:	1804	Usage of pthreads in a program changes the semantics of fork
		1805	considerably. Specifically, only async-safe functions can be called after
		1806	fork. Perl doesn't know about this, so in general, you cannot call fork
		1807	with defined behaviour in perl. IO::AIO uses pthreads, so this applies,
		1808	but many other extensions and (for inexplicable reasons) perl itself often
		1809	is linked against pthreads, so this limitation applies.
1410		1810
1411	Before the fork, IO::AIO enters a quiescent state where no requests	1811	Some operating systems have extensions that allow safe use of fork, and
1412	can be added in other threads and no results will be processed. After	1812	this module should do "the right thing" on those, and tries on others. At
1413	the fork the parent simply leaves the quiescent state and continues	1813	the time of this writing (2011) only GNU/Linux supports these extensions
1414	request/result processing, while the child frees the request/result queue	1814	to POSIX.
1415	(so that the requests started before the fork will only be handled in the
1416	parent). Threads will be started on demand until the limit set in the
1417	parent process has been reached again.
1418
1419	In short: the parent will, after a short pause, continue as if fork had
1420	not been called, while the child will act as if IO::AIO has not been used
1421	yet.
1422		1815
1423	=head2 MEMORY USAGE	1816	=head2 MEMORY USAGE
1424		1817
1425	Per-request usage:	1818	Per-request usage:
1426		1819

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.156 by root, Tue Jun 16 23:41:59 2009 UTC vs. Revision 1.201 by root, Tue Jul 5 09:24:11 2011 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.156 by root, Tue Jun 16 23:41:59 2009 UTC vs.
Revision 1.201 by root, Tue Jul 5 09:24:11 2011 UTC