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Revision 1.110 by root, Sun Jul 8 09:09:34 2007 UTC vs.
Revision 1.199 by root, Wed Jun 29 12:46:36 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
…		…
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		30
31	# AnyEvent integration
32	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
33	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
34
35	# Event integration
36	Event->io (fd => IO::AIO::poll_fileno,
37	poll => 'r',
38	cb => \&IO::AIO::poll_cb);
39
40	# Glib/Gtk2 integration
41	add_watch Glib::IO IO::AIO::poll_fileno,
42	in => sub { IO::AIO::poll_cb; 1 };
43
44	# Tk integration
45	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
46	readable => \&IO::AIO::poll_cb);
47
48	# Danga::Socket integration
49	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
50	\&IO::AIO::poll_cb);
51
52	=head1 DESCRIPTION	31	=head1 DESCRIPTION
53		32
54	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
55	operating system supports.	34	operating system supports. It is implemented as an interface to C<libeio>
		35	(L<http://software.schmorp.de/pkg/libeio.html>).
56		36
57	Asynchronous means that operations that can normally block your program	37	Asynchronous means that operations that can normally block your program
58	(e.g. reading from disk) will be done asynchronously: the operation	38	(e.g. reading from disk) will be done asynchronously: the operation
59	will still block, but you can do something else in the meantime. This	39	will still block, but you can do something else in the meantime. This
60	is extremely useful for programs that need to stay interactive even	40	is extremely useful for programs that need to stay interactive even
…		…
64	on a RAID volume or over NFS when you do a number of stat operations	44	on a RAID volume or over NFS when you do a number of stat operations
65	concurrently.	45	concurrently.
66		46
67	While most of this works on all types of file descriptors (for	47	While most of this works on all types of file descriptors (for
68	example sockets), using these functions on file descriptors that	48	example sockets), using these functions on file descriptors that
69	support nonblocking operation (again, sockets, pipes etc.) is very	49	support nonblocking operation (again, sockets, pipes etc.) is
70	inefficient. Use an event loop for that (such as the L<Event|Event>	50	very inefficient. Use an event loop for that (such as the L<EV>
71	module): IO::AIO will naturally fit into such an event loop itself.	51	module): IO::AIO will naturally fit into such an event loop itself.
72		52
73	In this version, a number of threads are started that execute your	53	In this version, a number of threads are started that execute your
74	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
75	in perl, and the threads created by this module will not be visible	55	in perl, and the threads created by this module will not be visible
…		…
85	yourself, always call C<poll_cb> from within the same thread, or never	65	yourself, always call C<poll_cb> from within the same thread, or never
86	call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
87		67
88	=head2 EXAMPLE	68	=head2 EXAMPLE
89		69
90	This is a simple example that uses the Event module and loads	70	This is a simple example that uses the EV module and loads
91	F</etc/passwd> asynchronously:	71	F</etc/passwd> asynchronously:
92		72
93	use Fcntl;	73	use Fcntl;
94	use Event;	74	use EV;
95	use IO::AIO;	75	use IO::AIO;
96		76
97	# register the IO::AIO callback with Event	77	# register the IO::AIO callback with EV
98	Event->io (fd => IO::AIO::poll_fileno,	78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
99	poll => 'r',
100	cb => \&IO::AIO::poll_cb);
101		79
102	# queue the request to open /etc/passwd	80	# queue the request to open /etc/passwd
103	aio_open "/etc/passwd", O_RDONLY, 0, sub {	81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
104	my $fh = shift	82	my $fh = shift
105	or die "error while opening: $!";	83	or die "error while opening: $!";
106		84
107	# stat'ing filehandles is generally non-blocking	85	# stat'ing filehandles is generally non-blocking
108	my $size = -s $fh;	86	my $size = -s $fh;
…		…
117		95
118	# file contents now in $contents	96	# file contents now in $contents
119	print $contents;	97	print $contents;
120		98
121	# exit event loop and program	99	# exit event loop and program
122	Event::unloop;	100	EV::unloop;
123	};	101	};
124	};	102	};
125		103
126	# possibly queue up other requests, or open GUI windows,	104	# possibly queue up other requests, or open GUI windows,
127	# check for sockets etc. etc.	105	# check for sockets etc. etc.
128		106
129	# process events as long as there are some:	107	# process events as long as there are some:
130	Event::loop;	108	EV::loop;
131		109
132	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
133		111
134	Every C<aio_*> function creates a request. which is a C data structure not	112	Every C<aio_*> function creates a request. which is a C data structure not
135	directly visible to Perl.	113	directly visible to Perl.
…		…
183		161
184	=cut	162	=cut
185		163
186	package IO::AIO;	164	package IO::AIO;
187		165
188	no warnings;	166	use Carp ();
189	use strict 'vars';	167
		168	use common::sense;
190		169
191	use base 'Exporter';	170	use base 'Exporter';
192		171
193	BEGIN {	172	BEGIN {
194	our $VERSION = '2.4';	173	our $VERSION = '3.92';
195		174
196	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
197	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
198	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link	177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
		178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		179	aio_rename aio_link aio_move aio_copy aio_group
199	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir	180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
200	aio_chown 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);
		184
201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));	185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
203	min_parallel max_parallel max_idle	187	min_parallel max_parallel max_idle idle_timeout
204	nreqs nready npending nthreads	188	nreqs nready npending nthreads
205	max_poll_time max_poll_reqs);	189	max_poll_time max_poll_reqs
		190	sendfile fadvise madvise
		191	mmap munmap munlock munlockall);
		192
		193	push @AIO_REQ, qw(aio_busy); # not exported
206		194
207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
208		196
209	require XSLoader;	197	require XSLoader;
210	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
211	}	199	}
212		200
213	=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_rename $srcpath, $dstpath, $callback->($status)
		228	aio_mkdir $pathname, $mode, $callback->($status)
		229	aio_rmdir $pathname, $callback->($status)
		230	aio_readdir $pathname, $callback->($entries)
		231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		233	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		234	aio_load $path, $data, $callback->($status)
		235	aio_copy $srcpath, $dstpath, $callback->($status)
		236	aio_move $srcpath, $dstpath, $callback->($status)
		237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		238	aio_rmtree $path, $callback->($status)
		239	aio_sync $callback->($status)
		240	aio_fsync $fh, $callback->($status)
		241	aio_fdatasync $fh, $callback->($status)
		242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		243	aio_pathsync $path, $callback->($status)
		244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		247	aio_mlockall $flags, $callback->($status)
		248	aio_group $callback->(...)
		249	aio_nop $callback->()
		250
		251	$prev_pri = aioreq_pri [$pri]
		252	aioreq_nice $pri_adjust
		253
		254	IO::AIO::poll_wait
		255	IO::AIO::poll_cb
		256	IO::AIO::poll
		257	IO::AIO::flush
		258	IO::AIO::max_poll_reqs $nreqs
		259	IO::AIO::max_poll_time $seconds
		260	IO::AIO::min_parallel $nthreads
		261	IO::AIO::max_parallel $nthreads
		262	IO::AIO::max_idle $nthreads
		263	IO::AIO::idle_timeout $seconds
		264	IO::AIO::max_outstanding $maxreqs
		265	IO::AIO::nreqs
		266	IO::AIO::nready
		267	IO::AIO::npending
		268
		269	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		270	IO::AIO::fadvise $fh, $offset, $len, $advice
		271	IO::AIO::madvise $scalar, $offset, $length, $advice
		272	IO::AIO::mprotect $scalar, $offset, $length, $protect
		273	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		274	IO::AIO::munlockall
214		275
215	=head2 AIO REQUEST FUNCTIONS	276	=head2 AIO REQUEST FUNCTIONS
216		277
217	All the C<aio_*> calls are more or less thin wrappers around the syscall	278	All the C<aio_*> calls are more or less thin wrappers around the syscall
218	with the same name (sans C<aio_>). The arguments are similar or identical,	279	with the same name (sans C<aio_>). The arguments are similar or identical,
219	and they all accept an additional (and optional) C<$callback> argument	280	and they all accept an additional (and optional) C<$callback> argument
220	which must be a code reference. This code reference will get called with	281	which must be a code reference. This code reference will get called with
221	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	282	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
222	perl, which usually delivers "false") as it's sole argument when the given	283	perl, which usually delivers "false") as its sole argument after the given
223	syscall has been executed asynchronously.	284	syscall has been executed asynchronously.
224		285
225	All functions expecting a filehandle keep a copy of the filehandle	286	All functions expecting a filehandle keep a copy of the filehandle
226	internally until the request has finished.	287	internally until the request has finished.
227		288
…		…
241	your pathnames to the locale (or other) encoding in effect in the user	302	your pathnames to the locale (or other) encoding in effect in the user
242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	303	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
243	use something else to ensure your scalar has the correct contents.	304	use something else to ensure your scalar has the correct contents.
244		305
245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	306	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
246	handles correctly wether it is set or not.	307	handles correctly whether it is set or not.
247		308
248	=over 4	309	=over 4
249		310
250	=item $prev_pri = aioreq_pri [$pri]	311	=item $prev_pri = aioreq_pri [$pri]
251		312
…		…
298	by the umask in effect then the request is being executed, so better never	359	by the umask in effect then the request is being executed, so better never
299	change the umask.	360	change the umask.
300		361
301	Example:	362	Example:
302		363
303	aio_open "/etc/passwd", O_RDONLY, 0, sub {	364	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
304	if ($_[0]) {	365	if ($_[0]) {
305	print "open successful, fh is $_[0]\n";	366	print "open successful, fh is $_[0]\n";
306	...	367	...
307	} else {	368	} else {
308	die "open failed: $!\n";	369	die "open failed: $!\n";
309	}	370	}
310	};	371	};
311		372
		373	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		374	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		375	following POSIX and non-POSIX constants are available (missing ones on
		376	your system are, as usual, C<0>):
		377
		378	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		379	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		380	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		381
312		382
313	=item aio_close $fh, $callback->($status)	383	=item aio_close $fh, $callback->($status)
314		384
315	Asynchronously close a file and call the callback with the result	385	Asynchronously close a file and call the callback with the result
316	code. I<WARNING:> although accepted, you should not pass in a perl	386	code.
317	filehandle here, as perl will likely close the file descriptor another
318	time when the filehandle is destroyed. Normally, you can safely call perls
319	C<close> or just let filehandles go out of scope.
320		387
321	This is supposed to be a bug in the API, so that might change. It's	388	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
322	therefore best to avoid this function.	389	closing the file descriptor associated with the filehandle itself.
323		390
		391	Therefore, C<aio_close> will not close the filehandle - instead it will
		392	use dup2 to overwrite the file descriptor with the write-end of a pipe
		393	(the pipe fd will be created on demand and will be cached).
		394
		395	Or in other words: the file descriptor will be closed, but it will not be
		396	free for reuse until the perl filehandle is closed.
		397
		398	=cut
324		399
325	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	400	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
326		401
327	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	402	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
328		403
329	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>	404	Reads or writes C<$length> bytes from or to the specified C<$fh> and
330	into the scalar given by C<$data> and offset C<$dataoffset> and calls the	405	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
331	callback without the actual number of bytes read (or -1 on error, just	406	and calls the callback without the actual number of bytes read (or -1 on
332	like the syscall).	407	error, just like the syscall).
333		408
		409	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		410	offset plus the actual number of bytes read.
		411
334	If C<$offset> is undefined, then the current file offset will be used (and	412	If C<$offset> is undefined, then the current file descriptor offset will
335	updated), otherwise the file offset will not be changed by these calls.	413	be used (and updated), otherwise the file descriptor offset will not be
		414	changed by these calls.
336		415
337	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.	416	If C<$length> is undefined in C<aio_write>, use the remaining length of
		417	C<$data>.
338		418
339	If C<$dataoffset> is less than zero, it will be counted from the end of	419	If C<$dataoffset> is less than zero, it will be counted from the end of
340	C<$data>.	420	C<$data>.
341		421
342	The C<$data> scalar I<MUST NOT> be modified in any way while the request	422	The C<$data> scalar I<MUST NOT> be modified in any way while the request
…		…
356		436
357	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	437	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
358	reading at byte offset C<$in_offset>, and starts writing at the current	438	reading at byte offset C<$in_offset>, and starts writing at the current
359	file offset of C<$out_fh>. Because of that, it is not safe to issue more	439	file offset of C<$out_fh>. Because of that, it is not safe to issue more
360	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	440	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
361	other.	441	other. The same C<$in_fh> works fine though, as this function does not
		442	move or use the file offset of C<$in_fh>.
362		443
		444	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		445	are written, and there is no way to find out how many more bytes have been
		446	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		447	number of bytes written to C<$out_fh>. Only if the result value equals
		448	C<$length> one can assume that C<$length> bytes have been read.
		449
		450	Unlike with other C<aio_> functions, it makes a lot of sense to use
		451	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		452	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		453	the socket I/O will be non-blocking. Note, however, that you can run
		454	into a trap where C<aio_sendfile> reads some data with readahead, then
		455	fails to write all data, and when the socket is ready the next time, the
		456	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		457	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		458	resource usage.
		459
363	This call tries to make use of a native C<sendfile> syscall to provide	460	This call tries to make use of a native C<sendfile>-like syscall to
364	zero-copy operation. For this to work, C<$out_fh> should refer to a	461	provide zero-copy operation. For this to work, C<$out_fh> should refer to
365	socket, and C<$in_fh> should refer to mmap'able file.	462	a socket, and C<$in_fh> should refer to an mmap'able file.
366		463
367	If the native sendfile call fails or is not implemented, it will be	464	If a native sendfile cannot be found or it fails with C<ENOSYS>,
368	emulated, so you can call C<aio_sendfile> on any type of filehandle	465	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		466	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
369	regardless of the limitations of the operating system.	467	type of filehandle regardless of the limitations of the operating system.
370		468
371	Please note, however, that C<aio_sendfile> can read more bytes from	469	As native sendfile syscalls (as practically any non-POSIX interface hacked
372	C<$in_fh> than are written, and there is no way to find out how many	470	together in a hurry to improve benchmark numbers) tend to be rather buggy
373	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	471	on many systems, this implementation tries to work around some known bugs
374	provides the number of bytes written to C<$out_fh>. Only if the result	472	in Linux and FreeBSD kernels (probably others, too), but that might fail,
375	value equals C<$length> one can assume that C<$length> bytes have been	473	so you really really should check the return value of C<aio_sendfile> -
376	read.	474	fewre bytes than expected might have been transferred.
377		475
378		476
379	=item aio_readahead $fh,$offset,$length, $callback->($retval)	477	=item aio_readahead $fh,$offset,$length, $callback->($retval)
380		478
381	C<aio_readahead> populates the page cache with data from a file so that	479	C<aio_readahead> populates the page cache with data from a file so that
…		…
404		502
405	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	503	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
406	error when stat'ing a large file, the results will be silently truncated	504	error when stat'ing a large file, the results will be silently truncated
407	unless perl itself is compiled with large file support.	505	unless perl itself is compiled with large file support.
408		506
		507	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		508	following constants and functions (if not implemented, the constants will
		509	be C<0> and the functions will either C<croak> or fall back on traditional
		510	behaviour).
		511
		512	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		513	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		514	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		515
409	Example: Print the length of F</etc/passwd>:	516	Example: Print the length of F</etc/passwd>:
410		517
411	aio_stat "/etc/passwd", sub {	518	aio_stat "/etc/passwd", sub {
412	$_[0] and die "stat failed: $!";	519	$_[0] and die "stat failed: $!";
413	print "size is ", -s _, "\n";	520	print "size is ", -s _, "\n";
414	};	521	};
415		522
416		523
		524	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		525
		526	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		527	whether a file handle or path was passed.
		528
		529	On success, the callback is passed a hash reference with the following
		530	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		531	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		532	is passed.
		533
		534	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		535	C<ST_NOSUID>.
		536
		537	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		538	their correct value when available, or to C<0> on systems that do
		539	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		540	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		541	C<ST_NODIRATIME> and C<ST_RELATIME>.
		542
		543	Example: stat C</wd> and dump out the data if successful.
		544
		545	aio_statvfs "/wd", sub {
		546	my $f = $_[0]
		547	or die "statvfs: $!";
		548
		549	use Data::Dumper;
		550	say Dumper $f;
		551	};
		552
		553	# result:
		554	{
		555	bsize => 1024,
		556	bfree => 4333064312,
		557	blocks => 10253828096,
		558	files => 2050765568,
		559	flag => 4096,
		560	favail => 2042092649,
		561	bavail => 4333064312,
		562	ffree => 2042092649,
		563	namemax => 255,
		564	frsize => 1024,
		565	fsid => 1810
		566	}
		567
		568
417	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	569	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
418		570
419	Works like perl's C<utime> function (including the special case of $atime	571	Works like perl's C<utime> function (including the special case of $atime
420	and $mtime being undef). Fractional times are supported if the underlying	572	and $mtime being undef). Fractional times are supported if the underlying
421	syscalls support them.	573	syscalls support them.
…		…
469		621
470	The only (POSIX-) portable way of calling this function is:	622	The only (POSIX-) portable way of calling this function is:
471		623
472	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	624	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
473		625
		626	See C<aio_stat> for info about some potentially helpful extra constants
		627	and functions.
474		628
475	=item aio_link $srcpath, $dstpath, $callback->($status)	629	=item aio_link $srcpath, $dstpath, $callback->($status)
476		630
477	Asynchronously create a new link to the existing object at C<$srcpath> at	631	Asynchronously create a new link to the existing object at C<$srcpath> at
478	the path C<$dstpath> and call the callback with the result code.	632	the path C<$dstpath> and call the callback with the result code.
…		…
514		668
515	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	669	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
516	directory (i.e. opendir + readdir + closedir). The entries will not be	670	directory (i.e. opendir + readdir + closedir). The entries will not be
517	sorted, and will B<NOT> include the C<.> and C<..> entries.	671	sorted, and will B<NOT> include the C<.> and C<..> entries.
518		672
519	The callback a single argument which is either C<undef> or an array-ref	673	The callback is passed a single argument which is either C<undef> or an
520	with the filenames.	674	array-ref with the filenames.
		675
		676
		677	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		678
		679	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		680	behaviour and output format. In case of an error, C<$entries> will be
		681	C<undef>.
		682
		683	The flags are a combination of the following constants, ORed together (the
		684	flags will also be passed to the callback, possibly modified):
		685
		686	=over 4
		687
		688	=item IO::AIO::READDIR_DENTS
		689
		690	When this flag is off, then the callback gets an arrayref consisting of
		691	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		692	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		693	entry in more detail.
		694
		695	C<$name> is the name of the entry.
		696
		697	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		698
		699	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		700	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		701	C<IO::AIO::DT_WHT>.
		702
		703	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		704	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		705	scalars are read-only: you can not modify them.
		706
		707	C<$inode> is the inode number (which might not be exact on systems with 64
		708	bit inode numbers and 32 bit perls). This field has unspecified content on
		709	systems that do not deliver the inode information.
		710
		711	=item IO::AIO::READDIR_DIRS_FIRST
		712
		713	When this flag is set, then the names will be returned in an order where
		714	likely directories come first, in optimal stat order. This is useful when
		715	you need to quickly find directories, or you want to find all directories
		716	while avoiding to stat() each entry.
		717
		718	If the system returns type information in readdir, then this is used
		719	to find directories directly. Otherwise, likely directories are names
		720	beginning with ".", or otherwise names with no dots, of which names with
		721	short names are tried first.
		722
		723	=item IO::AIO::READDIR_STAT_ORDER
		724
		725	When this flag is set, then the names will be returned in an order
		726	suitable for stat()'ing each one. That is, when you plan to stat()
		727	all files in the given directory, then the returned order will likely
		728	be fastest.
		729
		730	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		731	the likely dirs come first, resulting in a less optimal stat order.
		732
		733	=item IO::AIO::READDIR_FOUND_UNKNOWN
		734
		735	This flag should not be set when calling C<aio_readdirx>. Instead, it
		736	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		737	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		738	C<$type>'s are known, which can be used to speed up some algorithms.
		739
		740	=back
521		741
522		742
523	=item aio_load $path, $data, $callback->($status)	743	=item aio_load $path, $data, $callback->($status)
524		744
525	This is a composite request that tries to fully load the given file into	745	This is a composite request that tries to fully load the given file into
526	memory. Status is the same as with aio_read.	746	memory. Status is the same as with aio_read.
527		747
528	=cut	748	=cut
529		749
530	sub aio_load($$;$) {	750	sub aio_load($$;$) {
531	aio_block {
532	my ($path, undef, $cb) = @_;	751	my ($path, undef, $cb) = @_;
533	my $data = \$_[1];	752	my $data = \$_[1];
534		753
535	my $pri = aioreq_pri;	754	my $pri = aioreq_pri;
536	my $grp = aio_group $cb;	755	my $grp = aio_group $cb;
		756
		757	aioreq_pri $pri;
		758	add $grp aio_open $path, O_RDONLY, 0, sub {
		759	my $fh = shift
		760	or return $grp->result (-1);
537		761
538	aioreq_pri $pri;	762	aioreq_pri $pri;
539	add $grp aio_open $path, O_RDONLY, 0, sub {
540	my $fh = shift
541	or return $grp->result (-1);
542
543	aioreq_pri $pri;
544	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {	763	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
545	$grp->result ($_[0]);	764	$grp->result ($_[0]);
546	};
547	};	765	};
548
549	$grp
550	}	766	};
		767
		768	$grp
551	}	769	}
552		770
553	=item aio_copy $srcpath, $dstpath, $callback->($status)	771	=item aio_copy $srcpath, $dstpath, $callback->($status)
554		772
555	Try to copy the I<file> (directories not supported as either source or	773	Try to copy the I<file> (directories not supported as either source or
556	destination) from C<$srcpath> to C<$dstpath> and call the callback with	774	destination) from C<$srcpath> to C<$dstpath> and call the callback with
557	the C<0> (error) or C<-1> ok.	775	a status of C<0> (ok) or C<-1> (error, see C<$!>).
558		776
559	This is a composite request that it creates the destination file with	777	This is a composite request that creates the destination file with
560	mode 0200 and copies the contents of the source file into it using	778	mode 0200 and copies the contents of the source file into it using
561	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	779	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
562	uid/gid, in that order.	780	uid/gid, in that order.
563		781
564	If an error occurs, the partial destination file will be unlinked, if	782	If an error occurs, the partial destination file will be unlinked, if
…		…
566	errors are being ignored.	784	errors are being ignored.
567		785
568	=cut	786	=cut
569		787
570	sub aio_copy($$;$) {	788	sub aio_copy($$;$) {
571	aio_block {
572	my ($src, $dst, $cb) = @_;	789	my ($src, $dst, $cb) = @_;
573		790
574	my $pri = aioreq_pri;	791	my $pri = aioreq_pri;
575	my $grp = aio_group $cb;	792	my $grp = aio_group $cb;
576		793
577	aioreq_pri $pri;	794	aioreq_pri $pri;
578	add $grp aio_open $src, O_RDONLY, 0, sub {	795	add $grp aio_open $src, O_RDONLY, 0, sub {
579	if (my $src_fh = $_[0]) {	796	if (my $src_fh = $_[0]) {
580	my @stat = stat $src_fh;	797	my @stat = stat $src_fh; # hmm, might block over nfs?
581		798
582	aioreq_pri $pri;	799	aioreq_pri $pri;
583	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	800	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
584	if (my $dst_fh = $_[0]) {	801	if (my $dst_fh = $_[0]) {
585	aioreq_pri $pri;	802	aioreq_pri $pri;
586	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	803	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
587	if ($_[0] == $stat[7]) {	804	if ($_[0] == $stat[7]) {
588	$grp->result (0);	805	$grp->result (0);
589	close $src_fh;	806	close $src_fh;
590		807
591	# those should not normally block. should. should.
592	utime $stat[8], $stat[9], $dst;
593	chmod $stat[2] & 07777, $dst_fh;
594	chown $stat[4], $stat[5], $dst_fh;
595	close $dst_fh;
596	} else {	808	my $ch = sub {
597	$grp->result (-1);
598	close $src_fh;
599	close $dst_fh;
600
601	aioreq $pri;	809	aioreq_pri $pri;
		810	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		811	aioreq_pri $pri;
		812	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		813	aioreq_pri $pri;
602	add $grp aio_unlink $dst;	814	add $grp aio_close $dst_fh;
		815	}
		816	};
603	}	817	};
		818
		819	aioreq_pri $pri;
		820	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		821	if ($_[0] < 0 && $! == ENOSYS) {
		822	aioreq_pri $pri;
		823	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		824	} else {
		825	$ch->();
		826	}
		827	};
		828	} else {
		829	$grp->result (-1);
		830	close $src_fh;
		831	close $dst_fh;
		832
		833	aioreq $pri;
		834	add $grp aio_unlink $dst;
604	};	835	}
605	} else {
606	$grp->result (-1);
607	}	836	};
		837	} else {
		838	$grp->result (-1);
608	},	839	}
609
610	} else {
611	$grp->result (-1);
612	}	840	},
		841
		842	} else {
		843	$grp->result (-1);
613	};	844	}
614
615	$grp
616	}	845	};
		846
		847	$grp
617	}	848	}
618		849
619	=item aio_move $srcpath, $dstpath, $callback->($status)	850	=item aio_move $srcpath, $dstpath, $callback->($status)
620		851
621	Try to move the I<file> (directories not supported as either source or	852	Try to move the I<file> (directories not supported as either source or
622	destination) from C<$srcpath> to C<$dstpath> and call the callback with	853	destination) from C<$srcpath> to C<$dstpath> and call the callback with
623	the C<0> (error) or C<-1> ok.	854	a status of C<0> (ok) or C<-1> (error, see C<$!>).
624		855
625	This is a composite request that tries to rename(2) the file first. If	856	This is a composite request that tries to rename(2) the file first; if
626	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	857	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
627	that is successful, unlinking the C<$srcpath>.	858	that is successful, unlinks the C<$srcpath>.
628		859
629	=cut	860	=cut
630		861
631	sub aio_move($$;$) {	862	sub aio_move($$;$) {
632	aio_block {
633	my ($src, $dst, $cb) = @_;	863	my ($src, $dst, $cb) = @_;
634		864
635	my $pri = aioreq_pri;	865	my $pri = aioreq_pri;
636	my $grp = aio_group $cb;	866	my $grp = aio_group $cb;
637		867
638	aioreq_pri $pri;	868	aioreq_pri $pri;
639	add $grp aio_rename $src, $dst, sub {	869	add $grp aio_rename $src, $dst, sub {
640	if ($_[0] && $! == EXDEV) {	870	if ($_[0] && $! == EXDEV) {
641	aioreq_pri $pri;	871	aioreq_pri $pri;
642	add $grp aio_copy $src, $dst, sub {	872	add $grp aio_copy $src, $dst, sub {
643	$grp->result ($_[0]);
644
645	if (!$_[0]) {
646	aioreq_pri $pri;
647	add $grp aio_unlink $src;
648	}
649	};
650	} else {
651	$grp->result ($_[0]);	873	$grp->result ($_[0]);
		874
		875	unless ($_[0]) {
		876	aioreq_pri $pri;
		877	add $grp aio_unlink $src;
		878	}
652	}	879	};
		880	} else {
		881	$grp->result ($_[0]);
653	};	882	}
654
655	$grp
656	}	883	};
		884
		885	$grp
657	}	886	}
658		887
659	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	888	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
660		889
661	Scans a directory (similar to C<aio_readdir>) but additionally tries to	890	Scans a directory (similar to C<aio_readdir>) but additionally tries to
…		…
681		910
682	Implementation notes.	911	Implementation notes.
683		912
684	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	913	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
685		914
		915	If readdir returns file type information, then this is used directly to
		916	find directories.
		917
686	After reading the directory, the modification time, size etc. of the	918	Otherwise, after reading the directory, the modification time, size etc.
687	directory before and after the readdir is checked, and if they match (and	919	of the directory before and after the readdir is checked, and if they
688	isn't the current time), the link count will be used to decide how many	920	match (and isn't the current time), the link count will be used to decide
689	entries are directories (if >= 2). Otherwise, no knowledge of the number	921	how many entries are directories (if >= 2). Otherwise, no knowledge of the
690	of subdirectories will be assumed.	922	number of subdirectories will be assumed.
691		923
692	Then entries will be sorted into likely directories (everything without	924	Then entries will be sorted into likely directories a non-initial dot
693	a non-initial dot currently) and likely non-directories (everything	925	currently) and likely non-directories (see C<aio_readdirx>). Then every
694	else). Then every entry plus an appended C</.> will be C<stat>'ed,	926	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
695	likely directories first. If that succeeds, it assumes that the entry	927	in order of their inode numbers. If that succeeds, it assumes that the
696	is a directory or a symlink to directory (which will be checked	928	entry is a directory or a symlink to directory (which will be checked
697	seperately). This is often faster than stat'ing the entry itself because	929	seperately). This is often faster than stat'ing the entry itself because
698	filesystems might detect the type of the entry without reading the inode	930	filesystems might detect the type of the entry without reading the inode
699	data (e.g. ext2fs filetype feature).	931	data (e.g. ext2fs filetype feature), even on systems that cannot return
		932	the filetype information on readdir.
700		933
701	If the known number of directories (link count - 2) has been reached, the	934	If the known number of directories (link count - 2) has been reached, the
702	rest of the entries is assumed to be non-directories.	935	rest of the entries is assumed to be non-directories.
703		936
704	This only works with certainty on POSIX (= UNIX) filesystems, which	937	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
709	directory counting heuristic.	942	directory counting heuristic.
710		943
711	=cut	944	=cut
712		945
713	sub aio_scandir($$;$) {	946	sub aio_scandir($$;$) {
714	aio_block {
715	my ($path, $maxreq, $cb) = @_;	947	my ($path, $maxreq, $cb) = @_;
716		948
717	my $pri = aioreq_pri;	949	my $pri = aioreq_pri;
718		950
719	my $grp = aio_group $cb;	951	my $grp = aio_group $cb;
720		952
721	$maxreq = 4 if $maxreq <= 0;	953	$maxreq = 4 if $maxreq <= 0;
722		954
723	# stat once	955	# stat once
		956	aioreq_pri $pri;
		957	add $grp aio_stat $path, sub {
		958	return $grp->result () if $_[0];
		959	my $now = time;
		960	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		961
		962	# read the directory entries
724	aioreq_pri $pri;	963	aioreq_pri $pri;
725	add $grp aio_stat $path, sub {	964	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
		965	my $entries = shift
726	return $grp->result () if $_[0];	966	or return $grp->result ();
727	my $now = time;
728	my $hash1 = join ":", (stat _)[0,1,3,7,9];
729		967
730	# read the directory entries	968	# stat the dir another time
731	aioreq_pri $pri;	969	aioreq_pri $pri;
732	add $grp aio_readdir $path, sub {
733	my $entries = shift
734	or return $grp->result ();
735
736	# stat the dir another time
737	aioreq_pri $pri;
738	add $grp aio_stat $path, sub {	970	add $grp aio_stat $path, sub {
739	my $hash2 = join ":", (stat _)[0,1,3,7,9];	971	my $hash2 = join ":", (stat _)[0,1,3,7,9];
740		972
741	my $ndirs;	973	my $ndirs;
742		974
743	# take the slow route if anything looks fishy	975	# take the slow route if anything looks fishy
744	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	976	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
745	$ndirs = -1;	977	$ndirs = -1;
746	} else {	978	} else {
747	# if nlink == 2, we are finished	979	# if nlink == 2, we are finished
748	# on non-posix-fs's, we rely on nlink < 2	980	# for non-posix-fs's, we rely on nlink < 2
749	$ndirs = (stat _)[3] - 2	981	$ndirs = (stat _)[3] - 2
750	or return $grp->result ([], $entries);	982	or return $grp->result ([], $entries);
751	}	983	}
752		984
753	# sort into likely dirs and likely nondirs
754	# dirs == files without ".", short entries first
755	$entries = [map $_->[0],
756	sort { $b->[1] cmp $a->[1] }
757	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
758	@$entries];
759
760	my (@dirs, @nondirs);	985	my (@dirs, @nondirs);
761		986
762	my $statgrp = add $grp aio_group sub {	987	my $statgrp = add $grp aio_group sub {
763	$grp->result (\@dirs, \@nondirs);	988	$grp->result (\@dirs, \@nondirs);
764	};	989	};
765		990
766	limit $statgrp $maxreq;	991	limit $statgrp $maxreq;
767	feed $statgrp sub {	992	feed $statgrp sub {
768	return unless @$entries;	993	return unless @$entries;
769	my $entry = pop @$entries;	994	my $entry = shift @$entries;
770		995
771	aioreq_pri $pri;	996	aioreq_pri $pri;
772	add $statgrp aio_stat "$path/$entry/.", sub {	997	add $statgrp aio_stat "$path/$entry/.", sub {
773	if ($_[0] < 0) {	998	if ($_[0] < 0) {
774	push @nondirs, $entry;	999	push @nondirs, $entry;
775	} else {	1000	} else {
776	# need to check for real directory	1001	# need to check for real directory
777	aioreq_pri $pri;	1002	aioreq_pri $pri;
778	add $statgrp aio_lstat "$path/$entry", sub {	1003	add $statgrp aio_lstat "$path/$entry", sub {
779	if (-d _) {	1004	if (-d _) {
780	push @dirs, $entry;	1005	push @dirs, $entry;
781		1006
782	unless (--$ndirs) {	1007	unless (--$ndirs) {
783	push @nondirs, @$entries;	1008	push @nondirs, @$entries;
784	feed $statgrp;	1009	feed $statgrp;
785	}
786	} else {
787	push @nondirs, $entry;
788	}	1010	}
		1011	} else {
		1012	push @nondirs, $entry;
789	}	1013	}
790	}	1014	}
791	};	1015	}
792	};	1016	};
793	};	1017	};
794	};	1018	};
795	};	1019	};
796
797	$grp
798	}	1020	};
		1021
		1022	$grp
799	}	1023	}
800		1024
801	=item aio_rmtree $path, $callback->($status)	1025	=item aio_rmtree $path, $callback->($status)
802		1026
803	Delete a directory tree starting (and including) C<$path>, return the	1027	Delete a directory tree starting (and including) C<$path>, return the
…		…
807		1031
808	=cut	1032	=cut
809		1033
810	sub aio_rmtree;	1034	sub aio_rmtree;
811	sub aio_rmtree($;$) {	1035	sub aio_rmtree($;$) {
812	aio_block {
813	my ($path, $cb) = @_;	1036	my ($path, $cb) = @_;
814		1037
815	my $pri = aioreq_pri;	1038	my $pri = aioreq_pri;
816	my $grp = aio_group $cb;	1039	my $grp = aio_group $cb;
817		1040
818	aioreq_pri $pri;	1041	aioreq_pri $pri;
819	add $grp aio_scandir $path, 0, sub {	1042	add $grp aio_scandir $path, 0, sub {
820	my ($dirs, $nondirs) = @_;	1043	my ($dirs, $nondirs) = @_;
821		1044
822	my $dirgrp = aio_group sub {	1045	my $dirgrp = aio_group sub {
823	add $grp aio_rmdir $path, sub {	1046	add $grp aio_rmdir $path, sub {
824	$grp->result ($_[0]);	1047	$grp->result ($_[0]);
825	};
826	};	1048	};
827
828	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
829	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
830
831	add $grp $dirgrp;
832	};	1049	};
833		1050
834	$grp	1051	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1052	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1053
		1054	add $grp $dirgrp;
835	}	1055	};
		1056
		1057	$grp
836	}	1058	}
		1059
		1060	=item aio_sync $callback->($status)
		1061
		1062	Asynchronously call sync and call the callback when finished.
837		1063
838	=item aio_fsync $fh, $callback->($status)	1064	=item aio_fsync $fh, $callback->($status)
839		1065
840	Asynchronously call fsync on the given filehandle and call the callback	1066	Asynchronously call fsync on the given filehandle and call the callback
841	with the fsync result code.	1067	with the fsync result code.
…		…
845	Asynchronously call fdatasync on the given filehandle and call the	1071	Asynchronously call fdatasync on the given filehandle and call the
846	callback with the fdatasync result code.	1072	callback with the fdatasync result code.
847		1073
848	If this call isn't available because your OS lacks it or it couldn't be	1074	If this call isn't available because your OS lacks it or it couldn't be
849	detected, it will be emulated by calling C<fsync> instead.	1075	detected, it will be emulated by calling C<fsync> instead.
		1076
		1077	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1078
		1079	Sync the data portion of the file specified by C<$offset> and C<$length>
		1080	to disk (but NOT the metadata), by calling the Linux-specific
		1081	sync_file_range call. If sync_file_range is not available or it returns
		1082	ENOSYS, then fdatasync or fsync is being substituted.
		1083
		1084	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1085	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1086	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1087	manpage for details.
		1088
		1089	=item aio_pathsync $path, $callback->($status)
		1090
		1091	This request tries to open, fsync and close the given path. This is a
		1092	composite request intended to sync directories after directory operations
		1093	(E.g. rename). This might not work on all operating systems or have any
		1094	specific effect, but usually it makes sure that directory changes get
		1095	written to disc. It works for anything that can be opened for read-only,
		1096	not just directories.
		1097
		1098	Future versions of this function might fall back to other methods when
		1099	C<fsync> on the directory fails (such as calling C<sync>).
		1100
		1101	Passes C<0> when everything went ok, and C<-1> on error.
		1102
		1103	=cut
		1104
		1105	sub aio_pathsync($;$) {
		1106	my ($path, $cb) = @_;
		1107
		1108	my $pri = aioreq_pri;
		1109	my $grp = aio_group $cb;
		1110
		1111	aioreq_pri $pri;
		1112	add $grp aio_open $path, O_RDONLY, 0, sub {
		1113	my ($fh) = @_;
		1114	if ($fh) {
		1115	aioreq_pri $pri;
		1116	add $grp aio_fsync $fh, sub {
		1117	$grp->result ($_[0]);
		1118
		1119	aioreq_pri $pri;
		1120	add $grp aio_close $fh;
		1121	};
		1122	} else {
		1123	$grp->result (-1);
		1124	}
		1125	};
		1126
		1127	$grp
		1128	}
		1129
		1130	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1131
		1132	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1133	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1134	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1135	scalar must only be modified in-place while an aio operation is pending on
		1136	it).
		1137
		1138	It calls the C<msync> function of your OS, if available, with the memory
		1139	area starting at C<$offset> in the string and ending C<$length> bytes
		1140	later. If C<$length> is negative, counts from the end, and if C<$length>
		1141	is C<undef>, then it goes till the end of the string. The flags can be
		1142	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1143	C<IO::AIO::MS_SYNC>.
		1144
		1145	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1146
		1147	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1148	scalars.
		1149
		1150	It touches (reads or writes) all memory pages in the specified
		1151	range inside the scalar. All caveats and parameters are the same
		1152	as for C<aio_msync>, above, except for flags, which must be either
		1153	C<0> (which reads all pages and ensures they are instantiated) or
		1154	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1155	writing an octet from it, which dirties the page).
		1156
		1157	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1158
		1159	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1160	scalars.
		1161
		1162	It reads in all the pages of the underlying storage into memory (if any)
		1163	and locks them, so they are not getting swapped/paged out or removed.
		1164
		1165	If C<$length> is undefined, then the scalar will be locked till the end.
		1166
		1167	On systems that do not implement C<mlock>, this function returns C<-1>
		1168	and sets errno to C<ENOSYS>.
		1169
		1170	Note that the corresponding C<munlock> is synchronous and is
		1171	documented under L<MISCELLANEOUS FUNCTIONS>.
		1172
		1173	Example: open a file, mmap and mlock it - both will be undone when
		1174	C<$data> gets destroyed.
		1175
		1176	open my $fh, "<", $path or die "$path: $!";
		1177	my $data;
		1178	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1179	aio_mlock $data; # mlock in background
		1180
		1181	=item aio_mlockall $flags, $callback->($status)
		1182
		1183	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1184	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1185
		1186	On systems that do not implement C<mlockall>, this function returns C<-1>
		1187	and sets errno to C<ENOSYS>.
		1188
		1189	Note that the corresponding C<munlockall> is synchronous and is
		1190	documented under L<MISCELLANEOUS FUNCTIONS>.
		1191
		1192	Example: asynchronously lock all current and future pages into memory.
		1193
		1194	aio_mlockall IO::AIO::MCL_FUTURE;
850		1195
851	=item aio_group $callback->(...)	1196	=item aio_group $callback->(...)
852		1197
853	This is a very special aio request: Instead of doing something, it is a	1198	This is a very special aio request: Instead of doing something, it is a
854	container for other aio requests, which is useful if you want to bundle	1199	container for other aio requests, which is useful if you want to bundle
…		…
904	=item cancel $req	1249	=item cancel $req
905		1250
906	Cancels the request, if possible. Has the effect of skipping execution	1251	Cancels the request, if possible. Has the effect of skipping execution
907	when entering the B<execute> state and skipping calling the callback when	1252	when entering the B<execute> state and skipping calling the callback when
908	entering the the B<result> state, but will leave the request otherwise	1253	entering the the B<result> state, but will leave the request otherwise
909	untouched. That means that requests that currently execute will not be	1254	untouched (with the exception of readdir). That means that requests that
910	stopped and resources held by the request will not be freed prematurely.	1255	currently execute will not be stopped and resources held by the request
		1256	will not be freed prematurely.
911		1257
912	=item cb $req $callback->(...)	1258	=item cb $req $callback->(...)
913		1259
914	Replace (or simply set) the callback registered to the request.	1260	Replace (or simply set) the callback registered to the request.
915		1261
…		…
966	Their lifetime, simplified, looks like this: when they are empty, they	1312	Their lifetime, simplified, looks like this: when they are empty, they
967	will finish very quickly. If they contain only requests that are in the	1313	will finish very quickly. If they contain only requests that are in the
968	C<done> state, they will also finish. Otherwise they will continue to	1314	C<done> state, they will also finish. Otherwise they will continue to
969	exist.	1315	exist.
970		1316
971	That means after creating a group you have some time to add requests. And	1317	That means after creating a group you have some time to add requests
972	in the callbacks of those requests, you can add further requests to the	1318	(precisely before the callback has been invoked, which is only done within
973	group. And only when all those requests have finished will the the group	1319	the C<poll_cb>). And in the callbacks of those requests, you can add
974	itself finish.	1320	further requests to the group. And only when all those requests have
		1321	finished will the the group itself finish.
975		1322
976	=over 4	1323	=over 4
977		1324
978	=item add $grp ...	1325	=item add $grp ...
979		1326
…		…
988	=item $grp->cancel_subs	1335	=item $grp->cancel_subs
989		1336
990	Cancel all subrequests and clears any feeder, but not the group request	1337	Cancel all subrequests and clears any feeder, but not the group request
991	itself. Useful when you queued a lot of events but got a result early.	1338	itself. Useful when you queued a lot of events but got a result early.
992		1339
		1340	The group request will finish normally (you cannot add requests to the
		1341	group).
		1342
993	=item $grp->result (...)	1343	=item $grp->result (...)
994		1344
995	Set the result value(s) that will be passed to the group callback when all	1345	Set the result value(s) that will be passed to the group callback when all
996	subrequests have finished and set thre groups errno to the current value	1346	subrequests have finished and set the groups errno to the current value
997	of errno (just like calling C<errno> without an error number). By default,	1347	of errno (just like calling C<errno> without an error number). By default,
998	no argument will be passed and errno is zero.	1348	no argument will be passed and errno is zero.
999		1349
1000	=item $grp->errno ([$errno])	1350	=item $grp->errno ([$errno])
1001		1351
…		…
1012	=item feed $grp $callback->($grp)	1362	=item feed $grp $callback->($grp)
1013		1363
1014	Sets a feeder/generator on this group: every group can have an attached	1364	Sets a feeder/generator on this group: every group can have an attached
1015	generator that generates requests if idle. The idea behind this is that,	1365	generator that generates requests if idle. The idea behind this is that,
1016	although you could just queue as many requests as you want in a group,	1366	although you could just queue as many requests as you want in a group,
1017	this might starve other requests for a potentially long time. For	1367	this might starve other requests for a potentially long time. For example,
1018	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1368	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
1019	requests, delaying any later requests for a long time.	1369	delaying any later requests for a long time.
1020		1370
1021	To avoid this, and allow incremental generation of requests, you can	1371	To avoid this, and allow incremental generation of requests, you can
1022	instead a group and set a feeder on it that generates those requests. The	1372	instead a group and set a feeder on it that generates those requests. The
1023	feed callback will be called whenever there are few enough (see C<limit>,	1373	feed callback will be called whenever there are few enough (see C<limit>,
1024	below) requests active in the group itself and is expected to queue more	1374	below) requests active in the group itself and is expected to queue more
…		…
1028	not impose any limits).	1378	not impose any limits).
1029		1379
1030	If the feed does not queue more requests when called, it will be	1380	If the feed does not queue more requests when called, it will be
1031	automatically removed from the group.	1381	automatically removed from the group.
1032		1382
1033	If the feed limit is C<0>, it will be set to C<2> automatically.	1383	If the feed limit is C<0> when this method is called, it will be set to
		1384	C<2> automatically.
1034		1385
1035	Example:	1386	Example:
1036		1387
1037	# stat all files in @files, but only ever use four aio requests concurrently:	1388	# stat all files in @files, but only ever use four aio requests concurrently:
1038		1389
…		…
1050	Sets the feeder limit for the group: The feeder will be called whenever	1401	Sets the feeder limit for the group: The feeder will be called whenever
1051	the group contains less than this many requests.	1402	the group contains less than this many requests.
1052		1403
1053	Setting the limit to C<0> will pause the feeding process.	1404	Setting the limit to C<0> will pause the feeding process.
1054		1405
		1406	The default value for the limit is C<0>, but note that setting a feeder
		1407	automatically bumps it up to C<2>.
		1408
1055	=back	1409	=back
1056		1410
1057	=head2 SUPPORT FUNCTIONS	1411	=head2 SUPPORT FUNCTIONS
1058		1412
1059	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1413	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
…		…
1061	=over 4	1415	=over 4
1062		1416
1063	=item $fileno = IO::AIO::poll_fileno	1417	=item $fileno = IO::AIO::poll_fileno
1064		1418
1065	Return the I<request result pipe file descriptor>. This filehandle must be	1419	Return the I<request result pipe file descriptor>. This filehandle must be
1066	polled for reading by some mechanism outside this module (e.g. Event or	1420	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1067	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1421	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1068	to call C<poll_cb> to check the results.	1422	you have to call C<poll_cb> to check the results.
1069		1423
1070	See C<poll_cb> for an example.	1424	See C<poll_cb> for an example.
1071		1425
1072	=item IO::AIO::poll_cb	1426	=item IO::AIO::poll_cb
1073		1427
1074	Process some outstanding events on the result pipe. You have to call this	1428	Process some outstanding events on the result pipe. You have to call
1075	regularly. Returns the number of events processed. Returns immediately	1429	this regularly. Returns C<0> if all events could be processed (or there
1076	when no events are outstanding. The amount of events processed depends on	1430	were no events to process), or C<-1> if it returned earlier for whatever
1077	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1431	reason. Returns immediately when no events are outstanding. The amount of
		1432	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1433	C<IO::AIO::max_poll_time>.
1078		1434
1079	If not all requests were processed for whatever reason, the filehandle	1435	If not all requests were processed for whatever reason, the filehandle
1080	will still be ready when C<poll_cb> returns.	1436	will still be ready when C<poll_cb> returns, so normally you don't have to
		1437	do anything special to have it called later.
		1438
		1439	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1440	ready, it can be beneficial to call this function from loops which submit
		1441	a lot of requests, to make sure the results get processed when they become
		1442	available and not just when the loop is finished and the event loop takes
		1443	over again. This function returns very fast when there are no outstanding
		1444	requests.
1081		1445
1082	Example: Install an Event watcher that automatically calls	1446	Example: Install an Event watcher that automatically calls
1083	IO::AIO::poll_cb with high priority:	1447	IO::AIO::poll_cb with high priority (more examples can be found in the
		1448	SYNOPSIS section, at the top of this document):
1084		1449
1085	Event->io (fd => IO::AIO::poll_fileno,	1450	Event->io (fd => IO::AIO::poll_fileno,
1086	poll => 'r', async => 1,	1451	poll => 'r', async => 1,
1087	cb => \&IO::AIO::poll_cb);	1452	cb => \&IO::AIO::poll_cb);
		1453
		1454	=item IO::AIO::poll_wait
		1455
		1456	If there are any outstanding requests and none of them in the result
		1457	phase, wait till the result filehandle becomes ready for reading (simply
		1458	does a C<select> on the filehandle. This is useful if you want to
		1459	synchronously wait for some requests to finish).
		1460
		1461	See C<nreqs> for an example.
		1462
		1463	=item IO::AIO::poll
		1464
		1465	Waits until some requests have been handled.
		1466
		1467	Returns the number of requests processed, but is otherwise strictly
		1468	equivalent to:
		1469
		1470	IO::AIO::poll_wait, IO::AIO::poll_cb
		1471
		1472	=item IO::AIO::flush
		1473
		1474	Wait till all outstanding AIO requests have been handled.
		1475
		1476	Strictly equivalent to:
		1477
		1478	IO::AIO::poll_wait, IO::AIO::poll_cb
		1479	while IO::AIO::nreqs;
1088		1480
1089	=item IO::AIO::max_poll_reqs $nreqs	1481	=item IO::AIO::max_poll_reqs $nreqs
1090		1482
1091	=item IO::AIO::max_poll_time $seconds	1483	=item IO::AIO::max_poll_time $seconds
1092		1484
…		…
1117	# use a low priority so other tasks have priority	1509	# use a low priority so other tasks have priority
1118	Event->io (fd => IO::AIO::poll_fileno,	1510	Event->io (fd => IO::AIO::poll_fileno,
1119	poll => 'r', nice => 1,	1511	poll => 'r', nice => 1,
1120	cb => &IO::AIO::poll_cb);	1512	cb => &IO::AIO::poll_cb);
1121		1513
1122	=item IO::AIO::poll_wait
1123
1124	If there are any outstanding requests and none of them in the result
1125	phase, wait till the result filehandle becomes ready for reading (simply
1126	does a C<select> on the filehandle. This is useful if you want to
1127	synchronously wait for some requests to finish).
1128
1129	See C<nreqs> for an example.
1130
1131	=item IO::AIO::poll
1132
1133	Waits until some requests have been handled.
1134
1135	Returns the number of requests processed, but is otherwise strictly
1136	equivalent to:
1137
1138	IO::AIO::poll_wait, IO::AIO::poll_cb
1139
1140	=item IO::AIO::flush
1141
1142	Wait till all outstanding AIO requests have been handled.
1143
1144	Strictly equivalent to:
1145
1146	IO::AIO::poll_wait, IO::AIO::poll_cb
1147	while IO::AIO::nreqs;
1148
1149	=back	1514	=back
1150		1515
1151	=head3 CONTROLLING THE NUMBER OF THREADS	1516	=head3 CONTROLLING THE NUMBER OF THREADS
1152		1517
1153	=over	1518	=over
…		…
1186		1551
1187	Under normal circumstances you don't need to call this function.	1552	Under normal circumstances you don't need to call this function.
1188		1553
1189	=item IO::AIO::max_idle $nthreads	1554	=item IO::AIO::max_idle $nthreads
1190		1555
1191	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1556	Limit the number of threads (default: 4) that are allowed to idle
1192	threads that did not get a request to process within 10 seconds). That	1557	(i.e., threads that did not get a request to process within the idle
1193	means if a thread becomes idle while C<$nthreads> other threads are also	1558	timeout (default: 10 seconds). That means if a thread becomes idle while
1194	idle, it will free its resources and exit.	1559	C<$nthreads> other threads are also idle, it will free its resources and
		1560	exit.
1195		1561
1196	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1562	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1197	to allow for extremely high load situations, but want to free resources	1563	to allow for extremely high load situations, but want to free resources
1198	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1564	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1199		1565
1200	The default is probably ok in most situations, especially if thread	1566	The default is probably ok in most situations, especially if thread
1201	creation is fast. If thread creation is very slow on your system you might	1567	creation is fast. If thread creation is very slow on your system you might
1202	want to use larger values.	1568	want to use larger values.
1203		1569
		1570	=item IO::AIO::idle_timeout $seconds
		1571
		1572	Sets the minimum idle timeout (default 10) after which worker threads are
		1573	allowed to exit. SEe C<IO::AIO::max_idle>.
		1574
1204	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1575	=item IO::AIO::max_outstanding $maxreqs
		1576
		1577	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1578	you do queue up more than this number of requests, the next call to
		1579	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1580	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1581	longer exceeded.
		1582
		1583	In other words, this setting does not enforce a queue limit, but can be
		1584	used to make poll functions block if the limit is exceeded.
1205		1585
1206	This is a very bad function to use in interactive programs because it	1586	This is a very bad function to use in interactive programs because it
1207	blocks, and a bad way to reduce concurrency because it is inexact: Better	1587	blocks, and a bad way to reduce concurrency because it is inexact: Better
1208	use an C<aio_group> together with a feed callback.	1588	use an C<aio_group> together with a feed callback.
1209		1589
1210	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1590	It's main use is in scripts without an event loop - when you want to stat
1211	to queue up more than this number of requests, the next call to the	1591	a lot of files, you can write somehting like this:
1212	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1213	function will block until the limit is no longer exceeded.
1214		1592
1215	The default value is very large, so there is no practical limit on the	1593	IO::AIO::max_outstanding 32;
1216	number of outstanding requests.
1217		1594
1218	You can still queue as many requests as you want. Therefore,	1595	for my $path (...) {
1219	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1596	aio_stat $path , ...;
1220	as a stop gap to shield against fatal memory overflow (with large values).	1597	IO::AIO::poll_cb;
		1598	}
		1599
		1600	IO::AIO::flush;
		1601
		1602	The call to C<poll_cb> inside the loop will normally return instantly, but
		1603	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1604	some requests have been handled. This keeps the loop from pushing a large
		1605	number of C<aio_stat> requests onto the queue.
		1606
		1607	The default value for C<max_outstanding> is very large, so there is no
		1608	practical limit on the number of outstanding requests.
1221		1609
1222	=back	1610	=back
1223		1611
1224	=head3 STATISTICAL INFORMATION	1612	=head3 STATISTICAL INFORMATION
1225		1613
…		…
1245	Returns the number of requests currently in the pending state (executed,	1633	Returns the number of requests currently in the pending state (executed,
1246	but not yet processed by poll_cb).	1634	but not yet processed by poll_cb).
1247		1635
1248	=back	1636	=back
1249		1637
		1638	=head3 MISCELLANEOUS FUNCTIONS
		1639
		1640	IO::AIO implements some functions that might be useful, but are not
		1641	asynchronous.
		1642
		1643	=over 4
		1644
		1645	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1646
		1647	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1648	but is blocking (this makes most sense if you know the input data is
		1649	likely cached already and the output filehandle is set to non-blocking
		1650	operations).
		1651
		1652	Returns the number of bytes copied, or C<-1> on error.
		1653
		1654	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1655
		1656	Simply calls the C<posix_fadvise> function (see its
		1657	manpage for details). The following advice constants are
		1658	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1659	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1660	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1661
		1662	On systems that do not implement C<posix_fadvise>, this function returns
		1663	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1664
		1665	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1666
		1667	Simply calls the C<posix_madvise> function (see its
		1668	manpage for details). The following advice constants are
		1669	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1670	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1671
		1672	On systems that do not implement C<posix_madvise>, this function returns
		1673	ENOSYS, otherwise the return value of C<posix_madvise>.
		1674
		1675	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1676
		1677	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1678	$scalar (see its manpage for details). The following protect
		1679	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1680	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1681
		1682	On systems that do not implement C<mprotect>, this function returns
		1683	ENOSYS, otherwise the return value of C<mprotect>.
		1684
		1685	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1686
		1687	Memory-maps a file (or anonymous memory range) and attaches it to the
		1688	given C<$scalar>, which will act like a string scalar.
		1689
		1690	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1691	change the string length, and most read-only operations such as copying it
		1692	or searching it with regexes and so on.
		1693
		1694	Anything else is unsafe and will, at best, result in memory leaks.
		1695
		1696	The memory map associated with the C<$scalar> is automatically removed
		1697	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1698	C<IO::AIO::munmap> functions are called.
		1699
		1700	This calls the C<mmap>(2) function internally. See your system's manual
		1701	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1702
		1703	The C<$length> must be larger than zero and smaller than the actual
		1704	filesize.
		1705
		1706	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1707	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1708
		1709	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1710	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1711	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1712	(which is set to C<MAP_ANON> if your system only provides this
		1713	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1714	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1715	C<IO::AIO::MAP_NONBLOCK>
		1716
		1717	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1718
		1719	C<$offset> is the offset from the start of the file - it generally must be
		1720	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1721
		1722	Example:
		1723
		1724	use Digest::MD5;
		1725	use IO::AIO;
		1726
		1727	open my $fh, "<verybigfile"
		1728	or die "$!";
		1729
		1730	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1731	or die "verybigfile: $!";
		1732
		1733	my $fast_md5 = md5 $data;
		1734
		1735	=item IO::AIO::munmap $scalar
		1736
		1737	Removes a previous mmap and undefines the C<$scalar>.
		1738
		1739	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1740
		1741	Calls the C<munlock> function, undoing the effects of a previous
		1742	C<aio_mlock> call (see its description for details).
		1743
		1744	=item IO::AIO::munlockall
		1745
		1746	Calls the C<munlockall> function.
		1747
		1748	On systems that do not implement C<munlockall>, this function returns
		1749	ENOSYS, otherwise the return value of C<munlockall>.
		1750
		1751	=back
		1752
1250	=cut	1753	=cut
1251		1754
1252	# support function to convert a fd into a perl filehandle
1253	sub _fd2fh {
1254	return undef if $_[0] < 0;
1255
1256	# try to generate nice filehandles
1257	my $sym = "IO::AIO::fd#$_[0]";
1258	local *$sym;
1259
1260	open *$sym, "+<&=$_[0]" # usually works under any unix
1261	or open *$sym, "<&=$_[0]" # cygwin needs this
1262	or open *$sym, ">&=$_[0]" # or this
1263	or return undef;
1264
1265	*$sym
1266	}
1267
1268	min_parallel 8;	1755	min_parallel 8;
1269		1756
1270	END { flush }	1757	END { flush }
1271		1758
1272	1;	1759	1;
1273		1760
		1761	=head1 EVENT LOOP INTEGRATION
		1762
		1763	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1764	automatically into many event loops:
		1765
		1766	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1767	use AnyEvent::AIO;
		1768
		1769	You can also integrate IO::AIO manually into many event loops, here are
		1770	some examples of how to do this:
		1771
		1772	# EV integration
		1773	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1774
		1775	# Event integration
		1776	Event->io (fd => IO::AIO::poll_fileno,
		1777	poll => 'r',
		1778	cb => \&IO::AIO::poll_cb);
		1779
		1780	# Glib/Gtk2 integration
		1781	add_watch Glib::IO IO::AIO::poll_fileno,
		1782	in => sub { IO::AIO::poll_cb; 1 };
		1783
		1784	# Tk integration
		1785	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1786	readable => \&IO::AIO::poll_cb);
		1787
		1788	# Danga::Socket integration
		1789	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1790	\&IO::AIO::poll_cb);
		1791
1274	=head2 FORK BEHAVIOUR	1792	=head2 FORK BEHAVIOUR
1275		1793
1276	This module should do "the right thing" when the process using it forks:	1794	Usage of pthreads in a program changes the semantics of fork
		1795	considerably. Specifically, only async-safe functions can be called after
		1796	fork. Perl doesn't know about this, so in general, you cannot call fork
		1797	with defined behaviour in perl. IO::AIO uses pthreads, so this applies,
		1798	but many other extensions and (for inexplicable reasons) perl itself often
		1799	is linked against pthreads, so this limitation applies.
1277		1800
1278	Before the fork, IO::AIO enters a quiescent state where no requests	1801	Some operating systems have extensions that allow safe use of fork, and
1279	can be added in other threads and no results will be processed. After	1802	this module should do "the right thing" on those, and tries on others. At
1280	the fork the parent simply leaves the quiescent state and continues	1803	the time of this writing (2011) only GNU/Linux supports these extensions
1281	request/result processing, while the child frees the request/result queue	1804	to POSIX.
1282	(so that the requests started before the fork will only be handled in the
1283	parent). Threads will be started on demand until the limit set in the
1284	parent process has been reached again.
1285
1286	In short: the parent will, after a short pause, continue as if fork had
1287	not been called, while the child will act as if IO::AIO has not been used
1288	yet.
1289		1805
1290	=head2 MEMORY USAGE	1806	=head2 MEMORY USAGE
1291		1807
1292	Per-request usage:	1808	Per-request usage:
1293		1809
…		…
1295	bytes of memory. In addition, stat requests need a stat buffer (possibly	1811	bytes of memory. In addition, stat requests need a stat buffer (possibly
1296	a few hundred bytes), readdir requires a result buffer and so on. Perl	1812	a few hundred bytes), readdir requires a result buffer and so on. Perl
1297	scalars and other data passed into aio requests will also be locked and	1813	scalars and other data passed into aio requests will also be locked and
1298	will consume memory till the request has entered the done state.	1814	will consume memory till the request has entered the done state.
1299		1815
1300	This is now awfully much, so queuing lots of requests is not usually a	1816	This is not awfully much, so queuing lots of requests is not usually a
1301	problem.	1817	problem.
1302		1818
1303	Per-thread usage:	1819	Per-thread usage:
1304		1820
1305	In the execution phase, some aio requests require more memory for	1821	In the execution phase, some aio requests require more memory for
…		…
1310		1826
1311	Known bugs will be fixed in the next release.	1827	Known bugs will be fixed in the next release.
1312		1828
1313	=head1 SEE ALSO	1829	=head1 SEE ALSO
1314		1830
1315	L<Coro::AIO>.	1831	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1832	more natural syntax.
1316		1833
1317	=head1 AUTHOR	1834	=head1 AUTHOR
1318		1835
1319	Marc Lehmann <schmorp@schmorp.de>	1836	Marc Lehmann <schmorp@schmorp.de>
1320	http://home.schmorp.de/	1837	http://home.schmorp.de/

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