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Revision 1.147 by root, Wed Jun 3 12:24:49 2009 UTC vs.
Revision 1.220 by root, Sun Apr 1 17:46:02 2012 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 (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32	use AnyEvent::AIO;
33
34	# EV integration
35	my $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
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.	34	operating system supports. It is implemented as an interface to C<libeio>
		35	(L<http://software.schmorp.de/pkg/libeio.html>).
58		36
59	Asynchronous means that operations that can normally block your program	37	Asynchronous means that operations that can normally block your program
60	(e.g. reading from disk) will be done asynchronously: the operation	38	(e.g. reading from disk) will be done asynchronously: the operation
61	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
62	is extremely useful for programs that need to stay interactive even	40	is extremely useful for programs that need to stay interactive even
…		…
66	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
67	concurrently.	45	concurrently.
68		46
69	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
70	example sockets), using these functions on file descriptors that	48	example sockets), using these functions on file descriptors that
71	support nonblocking operation (again, sockets, pipes etc.) is very	49	support nonblocking operation (again, sockets, pipes etc.) is
72	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>
73	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.
74		52
75	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
76	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
77	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
…		…
87	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
88	call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
89		67
90	=head2 EXAMPLE	68	=head2 EXAMPLE
91		69
92	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
93	F</etc/passwd> asynchronously:	71	F</etc/passwd> asynchronously:
94		72
95	use Fcntl;	73	use Fcntl;
96	use Event;	74	use EV;
97	use IO::AIO;	75	use IO::AIO;
98		76
99	# register the IO::AIO callback with Event	77	# register the IO::AIO callback with EV
100	Event->io (fd => IO::AIO::poll_fileno,	78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
101	poll => 'r',
102	cb => \&IO::AIO::poll_cb);
103		79
104	# queue the request to open /etc/passwd	80	# queue the request to open /etc/passwd
105	aio_open "/etc/passwd", O_RDONLY, 0, sub {	81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
106	my $fh = shift	82	my $fh = shift
107	or die "error while opening: $!";	83	or die "error while opening: $!";
108		84
109	# stat'ing filehandles is generally non-blocking	85	# stat'ing filehandles is generally non-blocking
110	my $size = -s $fh;	86	my $size = -s $fh;
…		…
119		95
120	# file contents now in $contents	96	# file contents now in $contents
121	print $contents;	97	print $contents;
122		98
123	# exit event loop and program	99	# exit event loop and program
124	Event::unloop;	100	EV::unloop;
125	};	101	};
126	};	102	};
127		103
128	# possibly queue up other requests, or open GUI windows,	104	# possibly queue up other requests, or open GUI windows,
129	# check for sockets etc. etc.	105	# check for sockets etc. etc.
130		106
131	# process events as long as there are some:	107	# process events as long as there are some:
132	Event::loop;	108	EV::loop;
133		109
134	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
135		111
136	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
137	directly visible to Perl.	113	directly visible to Perl.
…		…
187		163
188	package IO::AIO;	164	package IO::AIO;
189		165
190	use Carp ();	166	use Carp ();
191		167
192	no warnings;	168	use common::sense;
193	use strict 'vars';
194		169
195	use base 'Exporter';	170	use base 'Exporter';
196		171
197	BEGIN {	172	BEGIN {
198	our $VERSION = '3.19';	173	our $VERSION = '4.13';
199		174
200	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	175	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
201	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
202	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
203	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
		179	aio_pathsync aio_readahead
204	aio_rename aio_link aio_move aio_copy aio_group	180	aio_rename aio_link aio_move aio_copy aio_group
205	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
206	aio_chmod aio_utime aio_truncate);	182	aio_chmod aio_utime aio_truncate
		183	aio_msync aio_mtouch aio_mlock aio_mlockall
		184	aio_statvfs
		185	aio_wd);
207		186
208	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
209	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
210	min_parallel max_parallel max_idle	189	min_parallel max_parallel max_idle idle_timeout
211	nreqs nready npending nthreads	190	nreqs nready npending nthreads
212	max_poll_time max_poll_reqs);	191	max_poll_time max_poll_reqs
		192	sendfile fadvise madvise
		193	mmap munmap munlock munlockall);
213		194
214	push @AIO_REQ, qw(aio_busy); # not exported	195	push @AIO_REQ, qw(aio_busy); # not exported
215		196
216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
217		198
…		…
219	XSLoader::load ("IO::AIO", $VERSION);	200	XSLoader::load ("IO::AIO", $VERSION);
220	}	201	}
221		202
222	=head1 FUNCTIONS	203	=head1 FUNCTIONS
223		204
224	=head2 AIO REQUEST FUNCTIONS	205	=head2 QUICK OVERVIEW
		206
		207	This section simply lists the prototypes of the most important functions
		208	for quick reference. See the following sections for function-by-function
		209	documentation.
		210
		211	aio_wd $pathname, $callback->($wd)
		212	aio_open $pathname, $flags, $mode, $callback->($fh)
		213	aio_close $fh, $callback->($status)
		214	aio_seek $fh,$offset,$whence, $callback->($offs)
		215	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		216	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		217	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		218	aio_readahead $fh,$offset,$length, $callback->($retval)
		219	aio_stat $fh_or_path, $callback->($status)
		220	aio_lstat $fh, $callback->($status)
		221	aio_statvfs $fh_or_path, $callback->($statvfs)
		222	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		223	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		224	aio_chmod $fh_or_path, $mode, $callback->($status)
		225	aio_truncate $fh_or_path, $offset, $callback->($status)
		226	aio_unlink $pathname, $callback->($status)
		227	aio_mknod $pathname, $mode, $dev, $callback->($status)
		228	aio_link $srcpath, $dstpath, $callback->($status)
		229	aio_symlink $srcpath, $dstpath, $callback->($status)
		230	aio_readlink $pathname, $callback->($link)
		231	aio_realpath $pathname, $callback->($link)
		232	aio_rename $srcpath, $dstpath, $callback->($status)
		233	aio_mkdir $pathname, $mode, $callback->($status)
		234	aio_rmdir $pathname, $callback->($status)
		235	aio_readdir $pathname, $callback->($entries)
		236	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		237	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		238	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		239	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		240	aio_load $pathname, $data, $callback->($status)
		241	aio_copy $srcpath, $dstpath, $callback->($status)
		242	aio_move $srcpath, $dstpath, $callback->($status)
		243	aio_rmtree $pathname, $callback->($status)
		244	aio_sync $callback->($status)
		245	aio_syncfs $fh, $callback->($status)
		246	aio_fsync $fh, $callback->($status)
		247	aio_fdatasync $fh, $callback->($status)
		248	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		249	aio_pathsync $pathname, $callback->($status)
		250	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		251	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		252	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		253	aio_mlockall $flags, $callback->($status)
		254	aio_group $callback->(...)
		255	aio_nop $callback->()
		256
		257	$prev_pri = aioreq_pri [$pri]
		258	aioreq_nice $pri_adjust
		259
		260	IO::AIO::poll_wait
		261	IO::AIO::poll_cb
		262	IO::AIO::poll
		263	IO::AIO::flush
		264	IO::AIO::max_poll_reqs $nreqs
		265	IO::AIO::max_poll_time $seconds
		266	IO::AIO::min_parallel $nthreads
		267	IO::AIO::max_parallel $nthreads
		268	IO::AIO::max_idle $nthreads
		269	IO::AIO::idle_timeout $seconds
		270	IO::AIO::max_outstanding $maxreqs
		271	IO::AIO::nreqs
		272	IO::AIO::nready
		273	IO::AIO::npending
		274
		275	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		276	IO::AIO::fadvise $fh, $offset, $len, $advice
		277	IO::AIO::madvise $scalar, $offset, $length, $advice
		278	IO::AIO::mprotect $scalar, $offset, $length, $protect
		279	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		280	IO::AIO::munlockall
		281
		282	=head2 API NOTES
225		283
226	All the C<aio_*> calls are more or less thin wrappers around the syscall	284	All the C<aio_*> calls are more or less thin wrappers around the syscall
227	with the same name (sans C<aio_>). The arguments are similar or identical,	285	with the same name (sans C<aio_>). The arguments are similar or identical,
228	and they all accept an additional (and optional) C<$callback> argument	286	and they all accept an additional (and optional) C<$callback> argument
229	which must be a code reference. This code reference will get called with	287	which must be a code reference. This code reference will be called after
230	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	288	the syscall has been executed in an asynchronous fashion. The results
231	perl, which usually delivers "false") as its sole argument after the given	289	of the request will be passed as arguments to the callback (and, if an
232	syscall has been executed asynchronously.	290	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		291	most syscalls return C<-1> on error, unlike perl, which usually delivers
		292	"false").
		293
		294	Some requests (such as C<aio_readdir>) pass the actual results and
		295	communicate failures by passing C<undef>.
233		296
234	All functions expecting a filehandle keep a copy of the filehandle	297	All functions expecting a filehandle keep a copy of the filehandle
235	internally until the request has finished.	298	internally until the request has finished.
236		299
237	All functions return request objects of type L<IO::AIO::REQ> that allow	300	All functions return request objects of type L<IO::AIO::REQ> that allow
238	further manipulation of those requests while they are in-flight.	301	further manipulation of those requests while they are in-flight.
239		302
240	The pathnames you pass to these routines I<must> be absolute and	303	The pathnames you pass to these routines I<should> be absolute. The
241	encoded as octets. The reason for the former is that at the time the	304	reason for this is that at the time the request is being executed, the
242	request is being executed, the current working directory could have	305	current working directory could have changed. Alternatively, you can
243	changed. Alternatively, you can make sure that you never change the	306	make sure that you never change the current working directory anywhere
244	current working directory anywhere in the program and then use relative	307	in the program and then use relative paths. You can also take advantage
245	paths.	308	of IO::AIOs working directory abstraction, that lets you specify paths
		309	relative to some previously-opened "working directory object" - see the
		310	description of the C<IO::AIO::WD> class later in this document.
246		311
247	To encode pathnames as octets, either make sure you either: a) always pass	312	To encode pathnames as octets, either make sure you either: a) always pass
248	in filenames you got from outside (command line, readdir etc.) without	313	in filenames you got from outside (command line, readdir etc.) without
249	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	314	tinkering, b) are in your native filesystem encoding, c) use the Encode
250	your pathnames to the locale (or other) encoding in effect in the user	315	module and encode your pathnames to the locale (or other) encoding in
251	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	316	effect in the user environment, d) use Glib::filename_from_unicode on
252	use something else to ensure your scalar has the correct contents.	317	unicode filenames or e) use something else to ensure your scalar has the
		318	correct contents.
253		319
254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	320	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255	handles correctly whether it is set or not.	321	handles correctly whether it is set or not.
		322
		323	=head2 AIO REQUEST FUNCTIONS
256		324
257	=over 4	325	=over 4
258		326
259	=item $prev_pri = aioreq_pri [$pri]	327	=item $prev_pri = aioreq_pri [$pri]
260		328
…		…
307	by the umask in effect then the request is being executed, so better never	375	by the umask in effect then the request is being executed, so better never
308	change the umask.	376	change the umask.
309		377
310	Example:	378	Example:
311		379
312	aio_open "/etc/passwd", O_RDONLY, 0, sub {	380	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313	if ($_[0]) {	381	if ($_[0]) {
314	print "open successful, fh is $_[0]\n";	382	print "open successful, fh is $_[0]\n";
315	...	383	...
316	} else {	384	} else {
317	die "open failed: $!\n";	385	die "open failed: $!\n";
318	}	386	}
319	};	387	};
320		388
		389	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		390	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		391	following POSIX and non-POSIX constants are available (missing ones on
		392	your system are, as usual, C<0>):
		393
		394	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		395	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		396	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		397
321		398
322	=item aio_close $fh, $callback->($status)	399	=item aio_close $fh, $callback->($status)
323		400
324	Asynchronously close a file and call the callback with the result	401	Asynchronously close a file and call the callback with the result
325	code.	402	code.
…		…
333		410
334	Or in other words: the file descriptor will be closed, but it will not be	411	Or in other words: the file descriptor will be closed, but it will not be
335	free for reuse until the perl filehandle is closed.	412	free for reuse until the perl filehandle is closed.
336		413
337	=cut	414	=cut
		415
		416	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		417
		418	Seeks the filehandle to the new C<$offset>, similarly to perl'S
		419	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		420	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		421	C<IO::AIO::SEEK_END>).
		422
		423	The resulting absolute offset will be passed to the callback, or C<-1> in
		424	case of an error.
		425
		426	In theory, the C<$whence> constants could be different than the
		427	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		428	so don't panic.
338		429
339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	430	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340		431
341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	432	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
342		433
…		…
375		466
376	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	467	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
377	reading at byte offset C<$in_offset>, and starts writing at the current	468	reading at byte offset C<$in_offset>, and starts writing at the current
378	file offset of C<$out_fh>. Because of that, it is not safe to issue more	469	file offset of C<$out_fh>. Because of that, it is not safe to issue more
379	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	470	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
380	other.	471	other. The same C<$in_fh> works fine though, as this function does not
		472	move or use the file offset of C<$in_fh>.
381		473
		474	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		475	are written, and there is no way to find out how many more bytes have been
		476	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		477	number of bytes written to C<$out_fh>. Only if the result value equals
		478	C<$length> one can assume that C<$length> bytes have been read.
		479
		480	Unlike with other C<aio_> functions, it makes a lot of sense to use
		481	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		482	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		483	the socket I/O will be non-blocking. Note, however, that you can run
		484	into a trap where C<aio_sendfile> reads some data with readahead, then
		485	fails to write all data, and when the socket is ready the next time, the
		486	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		487	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		488	resource usage.
		489
382	This call tries to make use of a native C<sendfile> syscall to provide	490	This call tries to make use of a native C<sendfile>-like syscall to
383	zero-copy operation. For this to work, C<$out_fh> should refer to a	491	provide zero-copy operation. For this to work, C<$out_fh> should refer to
384	socket, and C<$in_fh> should refer to mmap'able file.	492	a socket, and C<$in_fh> should refer to an mmap'able file.
385		493
386	If the native sendfile call fails or is not implemented, it will be	494	If a native sendfile cannot be found or it fails with C<ENOSYS>,
387	emulated, so you can call C<aio_sendfile> on any type of filehandle	495	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		496	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
388	regardless of the limitations of the operating system.	497	type of filehandle regardless of the limitations of the operating system.
389		498
390	Please note, however, that C<aio_sendfile> can read more bytes from	499	As native sendfile syscalls (as practically any non-POSIX interface hacked
391	C<$in_fh> than are written, and there is no way to find out how many	500	together in a hurry to improve benchmark numbers) tend to be rather buggy
392	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	501	on many systems, this implementation tries to work around some known bugs
393	provides the number of bytes written to C<$out_fh>. Only if the result	502	in Linux and FreeBSD kernels (probably others, too), but that might fail,
394	value equals C<$length> one can assume that C<$length> bytes have been	503	so you really really should check the return value of C<aio_sendfile> -
395	read.	504	fewre bytes than expected might have been transferred.
396		505
397		506
398	=item aio_readahead $fh,$offset,$length, $callback->($retval)	507	=item aio_readahead $fh,$offset,$length, $callback->($retval)
399		508
400	C<aio_readahead> populates the page cache with data from a file so that	509	C<aio_readahead> populates the page cache with data from a file so that
…		…
423		532
424	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	533	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
425	error when stat'ing a large file, the results will be silently truncated	534	error when stat'ing a large file, the results will be silently truncated
426	unless perl itself is compiled with large file support.	535	unless perl itself is compiled with large file support.
427		536
		537	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		538	following constants and functions (if not implemented, the constants will
		539	be C<0> and the functions will either C<croak> or fall back on traditional
		540	behaviour).
		541
		542	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		543	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		544	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		545
428	Example: Print the length of F</etc/passwd>:	546	Example: Print the length of F</etc/passwd>:
429		547
430	aio_stat "/etc/passwd", sub {	548	aio_stat "/etc/passwd", sub {
431	$_[0] and die "stat failed: $!";	549	$_[0] and die "stat failed: $!";
432	print "size is ", -s _, "\n";	550	print "size is ", -s _, "\n";
433	};	551	};
434		552
435		553
		554	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		555
		556	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		557	whether a file handle or path was passed.
		558
		559	On success, the callback is passed a hash reference with the following
		560	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		561	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		562	is passed.
		563
		564	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		565	C<ST_NOSUID>.
		566
		567	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		568	their correct value when available, or to C<0> on systems that do
		569	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		570	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		571	C<ST_NODIRATIME> and C<ST_RELATIME>.
		572
		573	Example: stat C</wd> and dump out the data if successful.
		574
		575	aio_statvfs "/wd", sub {
		576	my $f = $_[0]
		577	or die "statvfs: $!";
		578
		579	use Data::Dumper;
		580	say Dumper $f;
		581	};
		582
		583	# result:
		584	{
		585	bsize => 1024,
		586	bfree => 4333064312,
		587	blocks => 10253828096,
		588	files => 2050765568,
		589	flag => 4096,
		590	favail => 2042092649,
		591	bavail => 4333064312,
		592	ffree => 2042092649,
		593	namemax => 255,
		594	frsize => 1024,
		595	fsid => 1810
		596	}
		597
		598
436	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	599	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
437		600
438	Works like perl's C<utime> function (including the special case of $atime	601	Works like perl's C<utime> function (including the special case of $atime
439	and $mtime being undef). Fractional times are supported if the underlying	602	and $mtime being undef). Fractional times are supported if the underlying
440	syscalls support them.	603	syscalls support them.
…		…
478		641
479	Asynchronously unlink (delete) a file and call the callback with the	642	Asynchronously unlink (delete) a file and call the callback with the
480	result code.	643	result code.
481		644
482		645
483	=item aio_mknod $path, $mode, $dev, $callback->($status)	646	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
484		647
485	[EXPERIMENTAL]	648	[EXPERIMENTAL]
486		649
487	Asynchronously create a device node (or fifo). See mknod(2).	650	Asynchronously create a device node (or fifo). See mknod(2).
488		651
489	The only (POSIX-) portable way of calling this function is:	652	The only (POSIX-) portable way of calling this function is:
490		653
491	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	654	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
492		655
		656	See C<aio_stat> for info about some potentially helpful extra constants
		657	and functions.
493		658
494	=item aio_link $srcpath, $dstpath, $callback->($status)	659	=item aio_link $srcpath, $dstpath, $callback->($status)
495		660
496	Asynchronously create a new link to the existing object at C<$srcpath> at	661	Asynchronously create a new link to the existing object at C<$srcpath> at
497	the path C<$dstpath> and call the callback with the result code.	662	the path C<$dstpath> and call the callback with the result code.
…		…
501		666
502	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	667	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
503	the path C<$dstpath> and call the callback with the result code.	668	the path C<$dstpath> and call the callback with the result code.
504		669
505		670
506	=item aio_readlink $path, $callback->($link)	671	=item aio_readlink $pathname, $callback->($link)
507		672
508	Asynchronously read the symlink specified by C<$path> and pass it to	673	Asynchronously read the symlink specified by C<$path> and pass it to
509	the callback. If an error occurs, nothing or undef gets passed to the	674	the callback. If an error occurs, nothing or undef gets passed to the
510	callback.	675	callback.
511		676
512		677
		678	=item aio_realpath $pathname, $callback->($path)
		679
		680	Asynchronously make the path absolute and resolve any symlinks in
		681	C<$path>. The resulting path only consists of directories (Same as
		682	L<Cwd::realpath>).
		683
		684	This request can be used to get the absolute path of the current working
		685	directory by passing it a path of F<.> (a single dot).
		686
		687
513	=item aio_rename $srcpath, $dstpath, $callback->($status)	688	=item aio_rename $srcpath, $dstpath, $callback->($status)
514		689
515	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	690	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
516	rename(2) and call the callback with the result code.	691	rename(2) and call the callback with the result code.
517		692
…		…
533		708
534	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	709	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
535	directory (i.e. opendir + readdir + closedir). The entries will not be	710	directory (i.e. opendir + readdir + closedir). The entries will not be
536	sorted, and will B<NOT> include the C<.> and C<..> entries.	711	sorted, and will B<NOT> include the C<.> and C<..> entries.
537		712
538	The callback a single argument which is either C<undef> or an array-ref	713	The callback is passed a single argument which is either C<undef> or an
539	with the filenames.	714	array-ref with the filenames.
540		715
541		716
		717	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		718
		719	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		720	tune behaviour and output format. In case of an error, C<$entries> will be
		721	C<undef>.
		722
		723	The flags are a combination of the following constants, ORed together (the
		724	flags will also be passed to the callback, possibly modified):
		725
		726	=over 4
		727
		728	=item IO::AIO::READDIR_DENTS
		729
		730	When this flag is off, then the callback gets an arrayref consisting of
		731	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		732	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		733	entry in more detail.
		734
		735	C<$name> is the name of the entry.
		736
		737	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		738
		739	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		740	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		741	C<IO::AIO::DT_WHT>.
		742
		743	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		744	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		745	scalars are read-only: you can not modify them.
		746
		747	C<$inode> is the inode number (which might not be exact on systems with 64
		748	bit inode numbers and 32 bit perls). This field has unspecified content on
		749	systems that do not deliver the inode information.
		750
		751	=item IO::AIO::READDIR_DIRS_FIRST
		752
		753	When this flag is set, then the names will be returned in an order where
		754	likely directories come first, in optimal stat order. This is useful when
		755	you need to quickly find directories, or you want to find all directories
		756	while avoiding to stat() each entry.
		757
		758	If the system returns type information in readdir, then this is used
		759	to find directories directly. Otherwise, likely directories are names
		760	beginning with ".", or otherwise names with no dots, of which names with
		761	short names are tried first.
		762
		763	=item IO::AIO::READDIR_STAT_ORDER
		764
		765	When this flag is set, then the names will be returned in an order
		766	suitable for stat()'ing each one. That is, when you plan to stat()
		767	all files in the given directory, then the returned order will likely
		768	be fastest.
		769
		770	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		771	the likely dirs come first, resulting in a less optimal stat order.
		772
		773	=item IO::AIO::READDIR_FOUND_UNKNOWN
		774
		775	This flag should not be set when calling C<aio_readdirx>. Instead, it
		776	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		777	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		778	C<$type>'s are known, which can be used to speed up some algorithms.
		779
		780	=back
		781
		782
542	=item aio_load $path, $data, $callback->($status)	783	=item aio_load $pathname, $data, $callback->($status)
543		784
544	This is a composite request that tries to fully load the given file into	785	This is a composite request that tries to fully load the given file into
545	memory. Status is the same as with aio_read.	786	memory. Status is the same as with aio_read.
546		787
547	=cut	788	=cut
…		…
569		810
570	=item aio_copy $srcpath, $dstpath, $callback->($status)	811	=item aio_copy $srcpath, $dstpath, $callback->($status)
571		812
572	Try to copy the I<file> (directories not supported as either source or	813	Try to copy the I<file> (directories not supported as either source or
573	destination) from C<$srcpath> to C<$dstpath> and call the callback with	814	destination) from C<$srcpath> to C<$dstpath> and call the callback with
574	the C<0> (error) or C<-1> ok.	815	a status of C<0> (ok) or C<-1> (error, see C<$!>).
575		816
576	This is a composite request that creates the destination file with	817	This is a composite request that creates the destination file with
577	mode 0200 and copies the contents of the source file into it using	818	mode 0200 and copies the contents of the source file into it using
578	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	819	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
579	uid/gid, in that order.	820	uid/gid, in that order.
…		…
591	my $grp = aio_group $cb;	832	my $grp = aio_group $cb;
592		833
593	aioreq_pri $pri;	834	aioreq_pri $pri;
594	add $grp aio_open $src, O_RDONLY, 0, sub {	835	add $grp aio_open $src, O_RDONLY, 0, sub {
595	if (my $src_fh = $_[0]) {	836	if (my $src_fh = $_[0]) {
596	my @stat = stat $src_fh; # hmm, might bock over nfs?	837	my @stat = stat $src_fh; # hmm, might block over nfs?
597		838
598	aioreq_pri $pri;	839	aioreq_pri $pri;
599	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	840	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
600	if (my $dst_fh = $_[0]) {	841	if (my $dst_fh = $_[0]) {
601	aioreq_pri $pri;	842	aioreq_pri $pri;
…		…
648		889
649	=item aio_move $srcpath, $dstpath, $callback->($status)	890	=item aio_move $srcpath, $dstpath, $callback->($status)
650		891
651	Try to move the I<file> (directories not supported as either source or	892	Try to move the I<file> (directories not supported as either source or
652	destination) from C<$srcpath> to C<$dstpath> and call the callback with	893	destination) from C<$srcpath> to C<$dstpath> and call the callback with
653	the C<0> (error) or C<-1> ok.	894	a status of C<0> (ok) or C<-1> (error, see C<$!>).
654		895
655	This is a composite request that tries to rename(2) the file first; if	896	This is a composite request that tries to rename(2) the file first; if
656	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if	897	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
657	that is successful, unlinks the C<$srcpath>.	898	that is successful, unlinks the C<$srcpath>.
658		899
…		…
669	if ($_[0] && $! == EXDEV) {	910	if ($_[0] && $! == EXDEV) {
670	aioreq_pri $pri;	911	aioreq_pri $pri;
671	add $grp aio_copy $src, $dst, sub {	912	add $grp aio_copy $src, $dst, sub {
672	$grp->result ($_[0]);	913	$grp->result ($_[0]);
673		914
674	if (!$_[0]) {	915	unless ($_[0]) {
675	aioreq_pri $pri;	916	aioreq_pri $pri;
676	add $grp aio_unlink $src;	917	add $grp aio_unlink $src;
677	}	918	}
678	};	919	};
679	} else {	920	} else {
…		…
682	};	923	};
683		924
684	$grp	925	$grp
685	}	926	}
686		927
687	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	928	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
688		929
689	Scans a directory (similar to C<aio_readdir>) but additionally tries to	930	Scans a directory (similar to C<aio_readdir>) but additionally tries to
690	efficiently separate the entries of directory C<$path> into two sets of	931	efficiently separate the entries of directory C<$path> into two sets of
691	names, directories you can recurse into (directories), and ones you cannot	932	names, directories you can recurse into (directories), and ones you cannot
692	recurse into (everything else, including symlinks to directories).	933	recurse into (everything else, including symlinks to directories).
…		…
709		950
710	Implementation notes.	951	Implementation notes.
711		952
712	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	953	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
713		954
		955	If readdir returns file type information, then this is used directly to
		956	find directories.
		957
714	After reading the directory, the modification time, size etc. of the	958	Otherwise, after reading the directory, the modification time, size etc.
715	directory before and after the readdir is checked, and if they match (and	959	of the directory before and after the readdir is checked, and if they
716	isn't the current time), the link count will be used to decide how many	960	match (and isn't the current time), the link count will be used to decide
717	entries are directories (if >= 2). Otherwise, no knowledge of the number	961	how many entries are directories (if >= 2). Otherwise, no knowledge of the
718	of subdirectories will be assumed.	962	number of subdirectories will be assumed.
719		963
720	Then entries will be sorted into likely directories (everything without	964	Then entries will be sorted into likely directories a non-initial dot
721	a non-initial dot currently) and likely non-directories (everything	965	currently) and likely non-directories (see C<aio_readdirx>). Then every
722	else). Then every entry plus an appended C</.> will be C<stat>'ed,	966	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
723	likely directories first. If that succeeds, it assumes that the entry	967	in order of their inode numbers. If that succeeds, it assumes that the
724	is a directory or a symlink to directory (which will be checked	968	entry is a directory or a symlink to directory (which will be checked
725	seperately). This is often faster than stat'ing the entry itself because	969	separately). This is often faster than stat'ing the entry itself because
726	filesystems might detect the type of the entry without reading the inode	970	filesystems might detect the type of the entry without reading the inode
727	data (e.g. ext2fs filetype feature).	971	data (e.g. ext2fs filetype feature), even on systems that cannot return
		972	the filetype information on readdir.
728		973
729	If the known number of directories (link count - 2) has been reached, the	974	If the known number of directories (link count - 2) has been reached, the
730	rest of the entries is assumed to be non-directories.	975	rest of the entries is assumed to be non-directories.
731		976
732	This only works with certainty on POSIX (= UNIX) filesystems, which	977	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
745		990
746	my $grp = aio_group $cb;	991	my $grp = aio_group $cb;
747		992
748	$maxreq = 4 if $maxreq <= 0;	993	$maxreq = 4 if $maxreq <= 0;
749		994
750	# stat once	995	# get a wd object
751	aioreq_pri $pri;	996	aioreq_pri $pri;
752	add $grp aio_stat $path, sub {	997	add $grp aio_wd $path, sub {
		998	$_[0]
753	return $grp->result () if $_[0];	999	or return $grp->result ();
754	my $now = time;
755	my $hash1 = join ":", (stat _)[0,1,3,7,9];
756		1000
757	# read the directory entries	1001	my $wd = [shift, "."];
		1002
		1003	# stat once
758	aioreq_pri $pri;	1004	aioreq_pri $pri;
759	add $grp aio_readdir $path, sub {	1005	add $grp aio_stat $wd, sub {
760	my $entries = shift
761	or return $grp->result ();	1006	return $grp->result () if $_[0];
		1007	my $now = time;
		1008	my $hash1 = join ":", (stat _)[0,1,3,7,9];
762		1009
763	# stat the dir another time	1010	# read the directory entries
764	aioreq_pri $pri;	1011	aioreq_pri $pri;
		1012	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1013	my $entries = shift
		1014	or return $grp->result ();
		1015
		1016	# stat the dir another time
		1017	aioreq_pri $pri;
765	add $grp aio_stat $path, sub {	1018	add $grp aio_stat $wd, sub {
766	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1019	my $hash2 = join ":", (stat _)[0,1,3,7,9];
767		1020
768	my $ndirs;	1021	my $ndirs;
769		1022
770	# take the slow route if anything looks fishy	1023	# take the slow route if anything looks fishy
771	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1024	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
772	$ndirs = -1;	1025	$ndirs = -1;
773	} else {	1026	} else {
774	# if nlink == 2, we are finished	1027	# if nlink == 2, we are finished
775	# on non-posix-fs's, we rely on nlink < 2	1028	# for non-posix-fs's, we rely on nlink < 2
776	$ndirs = (stat _)[3] - 2	1029	$ndirs = (stat _)[3] - 2
777	or return $grp->result ([], $entries);	1030	or return $grp->result ([], $entries);
778	}	1031	}
779		1032
780	# sort into likely dirs and likely nondirs
781	# dirs == files without ".", short entries first
782	$entries = [map $_->[0],
783	sort { $b->[1] cmp $a->[1] }
784	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
785	@$entries];
786
787	my (@dirs, @nondirs);	1033	my (@dirs, @nondirs);
788		1034
789	my $statgrp = add $grp aio_group sub {	1035	my $statgrp = add $grp aio_group sub {
790	$grp->result (\@dirs, \@nondirs);	1036	$grp->result (\@dirs, \@nondirs);
791	};	1037	};
792		1038
793	limit $statgrp $maxreq;	1039	limit $statgrp $maxreq;
794	feed $statgrp sub {	1040	feed $statgrp sub {
795	return unless @$entries;	1041	return unless @$entries;
796	my $entry = pop @$entries;	1042	my $entry = shift @$entries;
797		1043
798	aioreq_pri $pri;	1044	aioreq_pri $pri;
		1045	$wd->[1] = "$entry/.";
799	add $statgrp aio_stat "$path/$entry/.", sub {	1046	add $statgrp aio_stat $wd, sub {
800	if ($_[0] < 0) {	1047	if ($_[0] < 0) {
801	push @nondirs, $entry;	1048	push @nondirs, $entry;
802	} else {	1049	} else {
803	# need to check for real directory	1050	# need to check for real directory
804	aioreq_pri $pri;	1051	aioreq_pri $pri;
		1052	$wd->[1] = $entry;
805	add $statgrp aio_lstat "$path/$entry", sub {	1053	add $statgrp aio_lstat $wd, sub {
806	if (-d _) {	1054	if (-d _) {
807	push @dirs, $entry;	1055	push @dirs, $entry;
808		1056
809	unless (--$ndirs) {	1057	unless (--$ndirs) {
810	push @nondirs, @$entries;	1058	push @nondirs, @$entries;
811	feed $statgrp;	1059	feed $statgrp;
		1060	}
		1061	} else {
		1062	push @nondirs, $entry;
812	}	1063	}
813	} else {
814	push @nondirs, $entry;
815	}	1064	}
816	}	1065	}
817	}	1066	};
818	};	1067	};
819	};	1068	};
820	};	1069	};
821	};	1070	};
822	};	1071	};
823		1072
824	$grp	1073	$grp
825	}	1074	}
826		1075
827	=item aio_rmtree $path, $callback->($status)	1076	=item aio_rmtree $pathname, $callback->($status)
828		1077
829	Delete a directory tree starting (and including) C<$path>, return the	1078	Delete a directory tree starting (and including) C<$path>, return the
830	status of the final C<rmdir> only. This is a composite request that	1079	status of the final C<rmdir> only. This is a composite request that
831	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1080	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
832	everything else.	1081	everything else.
…		…
874	callback with the fdatasync result code.	1123	callback with the fdatasync result code.
875		1124
876	If this call isn't available because your OS lacks it or it couldn't be	1125	If this call isn't available because your OS lacks it or it couldn't be
877	detected, it will be emulated by calling C<fsync> instead.	1126	detected, it will be emulated by calling C<fsync> instead.
878		1127
		1128	=item aio_syncfs $fh, $callback->($status)
		1129
		1130	Asynchronously call the syncfs syscall to sync the filesystem associated
		1131	to the given filehandle and call the callback with the syncfs result
		1132	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1133	errno to C<ENOSYS> nevertheless.
		1134
879	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1135	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
880		1136
881	Sync the data portion of the file specified by C<$offset> and C<$length>	1137	Sync the data portion of the file specified by C<$offset> and C<$length>
882	to disk (but NOT the metadata), by calling the Linux-specific	1138	to disk (but NOT the metadata), by calling the Linux-specific
883	sync_file_range call. If sync_file_range is not available or it returns	1139	sync_file_range call. If sync_file_range is not available or it returns
…		…
886	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1142	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
887	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1143	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
888	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1144	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
889	manpage for details.	1145	manpage for details.
890		1146
891	=item aio_pathsync $path, $callback->($status)	1147	=item aio_pathsync $pathname, $callback->($status)
892		1148
893	This request tries to open, fsync and close the given path. This is a	1149	This request tries to open, fsync and close the given path. This is a
894	composite request intended to sync directories after directory operations	1150	composite request intended to sync directories after directory operations
895	(E.g. rename). This might not work on all operating systems or have any	1151	(E.g. rename). This might not work on all operating systems or have any
896	specific effect, but usually it makes sure that directory changes get	1152	specific effect, but usually it makes sure that directory changes get
897	written to disc. It works for anything that can be opened for read-only,	1153	written to disc. It works for anything that can be opened for read-only,
898	not just directories.	1154	not just directories.
		1155
		1156	Future versions of this function might fall back to other methods when
		1157	C<fsync> on the directory fails (such as calling C<sync>).
899		1158
900	Passes C<0> when everything went ok, and C<-1> on error.	1159	Passes C<0> when everything went ok, and C<-1> on error.
901		1160
902	=cut	1161	=cut
903		1162
…		…
924	};	1183	};
925		1184
926	$grp	1185	$grp
927	}	1186	}
928		1187
		1188	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1189
		1190	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1191	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1192	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1193	scalar must only be modified in-place while an aio operation is pending on
		1194	it).
		1195
		1196	It calls the C<msync> function of your OS, if available, with the memory
		1197	area starting at C<$offset> in the string and ending C<$length> bytes
		1198	later. If C<$length> is negative, counts from the end, and if C<$length>
		1199	is C<undef>, then it goes till the end of the string. The flags can be
		1200	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1201	C<IO::AIO::MS_SYNC>.
		1202
		1203	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1204
		1205	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1206	scalars.
		1207
		1208	It touches (reads or writes) all memory pages in the specified
		1209	range inside the scalar. All caveats and parameters are the same
		1210	as for C<aio_msync>, above, except for flags, which must be either
		1211	C<0> (which reads all pages and ensures they are instantiated) or
		1212	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1213	writing an octet from it, which dirties the page).
		1214
		1215	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1216
		1217	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1218	scalars.
		1219
		1220	It reads in all the pages of the underlying storage into memory (if any)
		1221	and locks them, so they are not getting swapped/paged out or removed.
		1222
		1223	If C<$length> is undefined, then the scalar will be locked till the end.
		1224
		1225	On systems that do not implement C<mlock>, this function returns C<-1>
		1226	and sets errno to C<ENOSYS>.
		1227
		1228	Note that the corresponding C<munlock> is synchronous and is
		1229	documented under L<MISCELLANEOUS FUNCTIONS>.
		1230
		1231	Example: open a file, mmap and mlock it - both will be undone when
		1232	C<$data> gets destroyed.
		1233
		1234	open my $fh, "<", $path or die "$path: $!";
		1235	my $data;
		1236	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1237	aio_mlock $data; # mlock in background
		1238
		1239	=item aio_mlockall $flags, $callback->($status)
		1240
		1241	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1242	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1243
		1244	On systems that do not implement C<mlockall>, this function returns C<-1>
		1245	and sets errno to C<ENOSYS>.
		1246
		1247	Note that the corresponding C<munlockall> is synchronous and is
		1248	documented under L<MISCELLANEOUS FUNCTIONS>.
		1249
		1250	Example: asynchronously lock all current and future pages into memory.
		1251
		1252	aio_mlockall IO::AIO::MCL_FUTURE;
		1253
929	=item aio_group $callback->(...)	1254	=item aio_group $callback->(...)
930		1255
931	This is a very special aio request: Instead of doing something, it is a	1256	This is a very special aio request: Instead of doing something, it is a
932	container for other aio requests, which is useful if you want to bundle	1257	container for other aio requests, which is useful if you want to bundle
933	many requests into a single, composite, request with a definite callback	1258	many requests into a single, composite, request with a definite callback
…		…
970	immense (it blocks a thread for a long time) so do not use this function	1295	immense (it blocks a thread for a long time) so do not use this function
971	except to put your application under artificial I/O pressure.	1296	except to put your application under artificial I/O pressure.
972		1297
973	=back	1298	=back
974		1299
		1300
		1301	=head2 IO::AIO::WD - multiple working directories
		1302
		1303	Your process only has one current working directory, which is used by all
		1304	threads. This makes it hard to use relative paths (some other component
		1305	could call C<chdir> at any time, and it is hard to control when the path
		1306	will be used by IO::AIO).
		1307
		1308	One solution for this is to always use absolute paths. This usually works,
		1309	but can be quite slow (the kernel has to walk the whole path on every
		1310	access), and can also be a hassle to implement.
		1311
		1312	Newer POSIX systems have a number of functions (openat, fdopendir,
		1313	futimensat and so on) that make it possible to specify working directories
		1314	per operation.
		1315
		1316	For portability, and because the clowns who "designed", or shall I write,
		1317	perpetrated this new interface were obviously half-drunk, this abstraction
		1318	cannot be perfect, though.
		1319
		1320	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1321	object. This object stores the canonicalised, absolute version of the
		1322	path, and on systems that allow it, also a directory file descriptor.
		1323
		1324	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1325	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1326	object and a pathname instead (or the IO::AIO::WD object alone, which
		1327	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1328	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1329	to that IO::AIO::WD object.
		1330
		1331	For example, to get a wd object for F</etc> and then stat F<passwd>
		1332	inside, you would write:
		1333
		1334	aio_wd "/etc", sub {
		1335	my $etcdir = shift;
		1336
		1337	# although $etcdir can be undef on error, there is generally no reason
		1338	# to check for errors here, as aio_stat will fail with ENOENT
		1339	# when $etcdir is undef.
		1340
		1341	aio_stat [$etcdir, "passwd"], sub {
		1342	# yay
		1343	};
		1344	};
		1345
		1346	That C<aio_wd> is a request and not a normal function shows that creating
		1347	an IO::AIO::WD object is itself a potentially blocking operation, which is
		1348	why it is done asynchronously.
		1349
		1350	To stat the directory obtained with C<aio_wd> above, one could write
		1351	either of the following three request calls:
		1352
		1353	aio_lstat "/etc" , sub { ... # pathname as normal string
		1354	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1355	aio_lstat $wd , sub { ... # shorthand for the previous
		1356
		1357	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1358	object and the pathname string, so you could write the following without
		1359	causing any issues due to C<$path> getting reused:
		1360
		1361	my $path = [$wd, undef];
		1362
		1363	for my $name (qw(abc def ghi)) {
		1364	$path->[1] = $name;
		1365	aio_stat $path, sub {
		1366	# ...
		1367	};
		1368	}
		1369
		1370	There are some caveats: when directories get renamed (or deleted), the
		1371	pathname string doesn't change, so will point to the new directory (or
		1372	nowhere at all), while the directory fd, if available on the system,
		1373	will still point to the original directory. Most functions accepting a
		1374	pathname will use the directory fd on newer systems, and the string on
		1375	older systems. Some functions (such as realpath) will always rely on the
		1376	string form of the pathname.
		1377
		1378	So this fucntionality is mainly useful to get some protection against
		1379	C<chdir>, to easily get an absolute path out of a relative path for future
		1380	reference, and to speed up doing many operations in the same directory
		1381	(e.g. when stat'ing all files in a directory).
		1382
		1383	The following functions implement this working directory abstraction:
		1384
		1385	=over 4
		1386
		1387	=item aio_wd $pathname, $callback->($wd)
		1388
		1389	Asynchonously canonicalise the given pathname and convert it to an
		1390	IO::AIO::WD object representing it. If possible and supported on the
		1391	system, also open a directory fd to speed up pathname resolution relative
		1392	to this working directory.
		1393
		1394	If something goes wrong, then C<undef> is passwd to the callback instead
		1395	of a working directory object and C<$!> is set appropriately. Since
		1396	passing C<undef> as working directory component of a pathname fails the
		1397	request with C<ENOENT>, there is often no need for error checking in the
		1398	C<aio_wd> callback, as future requests using the value will fail in the
		1399	expected way.
		1400
		1401	If this call isn't available because your OS lacks it or it couldn't be
		1402	detected, it will be emulated by calling C<fsync> instead.
		1403
		1404	=item IO::AIO::CWD
		1405
		1406	This is a compiletime constant (object) that represents the process
		1407	current working directory.
		1408
		1409	Specifying this object as working directory object for a pathname is as
		1410	if the pathname would be specified directly, without a directory object,
		1411	e.g., these calls are functionally identical:
		1412
		1413	aio_stat "somefile", sub { ... };
		1414	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1415
		1416	=back
		1417
		1418
975	=head2 IO::AIO::REQ CLASS	1419	=head2 IO::AIO::REQ CLASS
976		1420
977	All non-aggregate C<aio_*> functions return an object of this class when	1421	All non-aggregate C<aio_*> functions return an object of this class when
978	called in non-void context.	1422	called in non-void context.
979		1423
…		…
982	=item cancel $req	1426	=item cancel $req
983		1427
984	Cancels the request, if possible. Has the effect of skipping execution	1428	Cancels the request, if possible. Has the effect of skipping execution
985	when entering the B<execute> state and skipping calling the callback when	1429	when entering the B<execute> state and skipping calling the callback when
986	entering the the B<result> state, but will leave the request otherwise	1430	entering the the B<result> state, but will leave the request otherwise
987	untouched. That means that requests that currently execute will not be	1431	untouched (with the exception of readdir). That means that requests that
988	stopped and resources held by the request will not be freed prematurely.	1432	currently execute will not be stopped and resources held by the request
		1433	will not be freed prematurely.
989		1434
990	=item cb $req $callback->(...)	1435	=item cb $req $callback->(...)
991		1436
992	Replace (or simply set) the callback registered to the request.	1437	Replace (or simply set) the callback registered to the request.
993		1438
…		…
1067	=item $grp->cancel_subs	1512	=item $grp->cancel_subs
1068		1513
1069	Cancel all subrequests and clears any feeder, but not the group request	1514	Cancel all subrequests and clears any feeder, but not the group request
1070	itself. Useful when you queued a lot of events but got a result early.	1515	itself. Useful when you queued a lot of events but got a result early.
1071		1516
		1517	The group request will finish normally (you cannot add requests to the
		1518	group).
		1519
1072	=item $grp->result (...)	1520	=item $grp->result (...)
1073		1521
1074	Set the result value(s) that will be passed to the group callback when all	1522	Set the result value(s) that will be passed to the group callback when all
1075	subrequests have finished and set the groups errno to the current value	1523	subrequests have finished and set the groups errno to the current value
1076	of errno (just like calling C<errno> without an error number). By default,	1524	of errno (just like calling C<errno> without an error number). By default,
…		…
1092		1540
1093	Sets a feeder/generator on this group: every group can have an attached	1541	Sets a feeder/generator on this group: every group can have an attached
1094	generator that generates requests if idle. The idea behind this is that,	1542	generator that generates requests if idle. The idea behind this is that,
1095	although you could just queue as many requests as you want in a group,	1543	although you could just queue as many requests as you want in a group,
1096	this might starve other requests for a potentially long time. For example,	1544	this might starve other requests for a potentially long time. For example,
1097	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1545	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1098	delaying any later requests for a long time.	1546	requests, delaying any later requests for a long time.
1099		1547
1100	To avoid this, and allow incremental generation of requests, you can	1548	To avoid this, and allow incremental generation of requests, you can
1101	instead a group and set a feeder on it that generates those requests. The	1549	instead a group and set a feeder on it that generates those requests. The
1102	feed callback will be called whenever there are few enough (see C<limit>,	1550	feed callback will be called whenever there are few enough (see C<limit>,
1103	below) requests active in the group itself and is expected to queue more	1551	below) requests active in the group itself and is expected to queue more
…		…
1144	=over 4	1592	=over 4
1145		1593
1146	=item $fileno = IO::AIO::poll_fileno	1594	=item $fileno = IO::AIO::poll_fileno
1147		1595
1148	Return the I<request result pipe file descriptor>. This filehandle must be	1596	Return the I<request result pipe file descriptor>. This filehandle must be
1149	polled for reading by some mechanism outside this module (e.g. Event or	1597	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1150	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1598	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1151	to call C<poll_cb> to check the results.	1599	you have to call C<poll_cb> to check the results.
1152		1600
1153	See C<poll_cb> for an example.	1601	See C<poll_cb> for an example.
1154		1602
1155	=item IO::AIO::poll_cb	1603	=item IO::AIO::poll_cb
1156		1604
1157	Process some outstanding events on the result pipe. You have to call this	1605	Process some outstanding events on the result pipe. You have to call
1158	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1606	this regularly. Returns C<0> if all events could be processed (or there
1159	returned earlier for whatever reason. Returns immediately when no events	1607	were no events to process), or C<-1> if it returned earlier for whatever
1160	are outstanding. The amount of events processed depends on the settings of	1608	reason. Returns immediately when no events are outstanding. The amount of
1161	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1609	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1610	C<IO::AIO::max_poll_time>.
1162		1611
1163	If not all requests were processed for whatever reason, the filehandle	1612	If not all requests were processed for whatever reason, the filehandle
1164	will still be ready when C<poll_cb> returns, so normally you don't have to	1613	will still be ready when C<poll_cb> returns, so normally you don't have to
1165	do anything special to have it called later.	1614	do anything special to have it called later.
1166		1615
		1616	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1617	ready, it can be beneficial to call this function from loops which submit
		1618	a lot of requests, to make sure the results get processed when they become
		1619	available and not just when the loop is finished and the event loop takes
		1620	over again. This function returns very fast when there are no outstanding
		1621	requests.
		1622
1167	Example: Install an Event watcher that automatically calls	1623	Example: Install an Event watcher that automatically calls
1168	IO::AIO::poll_cb with high priority:	1624	IO::AIO::poll_cb with high priority (more examples can be found in the
		1625	SYNOPSIS section, at the top of this document):
1169		1626
1170	Event->io (fd => IO::AIO::poll_fileno,	1627	Event->io (fd => IO::AIO::poll_fileno,
1171	poll => 'r', async => 1,	1628	poll => 'r', async => 1,
1172	cb => \&IO::AIO::poll_cb);	1629	cb => \&IO::AIO::poll_cb);
		1630
		1631	=item IO::AIO::poll_wait
		1632
		1633	If there are any outstanding requests and none of them in the result
		1634	phase, wait till the result filehandle becomes ready for reading (simply
		1635	does a C<select> on the filehandle. This is useful if you want to
		1636	synchronously wait for some requests to finish).
		1637
		1638	See C<nreqs> for an example.
		1639
		1640	=item IO::AIO::poll
		1641
		1642	Waits until some requests have been handled.
		1643
		1644	Returns the number of requests processed, but is otherwise strictly
		1645	equivalent to:
		1646
		1647	IO::AIO::poll_wait, IO::AIO::poll_cb
		1648
		1649	=item IO::AIO::flush
		1650
		1651	Wait till all outstanding AIO requests have been handled.
		1652
		1653	Strictly equivalent to:
		1654
		1655	IO::AIO::poll_wait, IO::AIO::poll_cb
		1656	while IO::AIO::nreqs;
1173		1657
1174	=item IO::AIO::max_poll_reqs $nreqs	1658	=item IO::AIO::max_poll_reqs $nreqs
1175		1659
1176	=item IO::AIO::max_poll_time $seconds	1660	=item IO::AIO::max_poll_time $seconds
1177		1661
…		…
1202	# use a low priority so other tasks have priority	1686	# use a low priority so other tasks have priority
1203	Event->io (fd => IO::AIO::poll_fileno,	1687	Event->io (fd => IO::AIO::poll_fileno,
1204	poll => 'r', nice => 1,	1688	poll => 'r', nice => 1,
1205	cb => &IO::AIO::poll_cb);	1689	cb => &IO::AIO::poll_cb);
1206		1690
1207	=item IO::AIO::poll_wait
1208
1209	If there are any outstanding requests and none of them in the result
1210	phase, wait till the result filehandle becomes ready for reading (simply
1211	does a C<select> on the filehandle. This is useful if you want to
1212	synchronously wait for some requests to finish).
1213
1214	See C<nreqs> for an example.
1215
1216	=item IO::AIO::poll
1217
1218	Waits until some requests have been handled.
1219
1220	Returns the number of requests processed, but is otherwise strictly
1221	equivalent to:
1222
1223	IO::AIO::poll_wait, IO::AIO::poll_cb
1224
1225	=item IO::AIO::flush
1226
1227	Wait till all outstanding AIO requests have been handled.
1228
1229	Strictly equivalent to:
1230
1231	IO::AIO::poll_wait, IO::AIO::poll_cb
1232	while IO::AIO::nreqs;
1233
1234	=back	1691	=back
1235		1692
1236	=head3 CONTROLLING THE NUMBER OF THREADS	1693	=head3 CONTROLLING THE NUMBER OF THREADS
1237		1694
1238	=over	1695	=over
…		…
1271		1728
1272	Under normal circumstances you don't need to call this function.	1729	Under normal circumstances you don't need to call this function.
1273		1730
1274	=item IO::AIO::max_idle $nthreads	1731	=item IO::AIO::max_idle $nthreads
1275		1732
1276	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1733	Limit the number of threads (default: 4) that are allowed to idle
1277	threads that did not get a request to process within 10 seconds). That	1734	(i.e., threads that did not get a request to process within the idle
1278	means if a thread becomes idle while C<$nthreads> other threads are also	1735	timeout (default: 10 seconds). That means if a thread becomes idle while
1279	idle, it will free its resources and exit.	1736	C<$nthreads> other threads are also idle, it will free its resources and
		1737	exit.
1280		1738
1281	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1739	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1282	to allow for extremely high load situations, but want to free resources	1740	to allow for extremely high load situations, but want to free resources
1283	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1741	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1284		1742
1285	The default is probably ok in most situations, especially if thread	1743	The default is probably ok in most situations, especially if thread
1286	creation is fast. If thread creation is very slow on your system you might	1744	creation is fast. If thread creation is very slow on your system you might
1287	want to use larger values.	1745	want to use larger values.
1288		1746
		1747	=item IO::AIO::idle_timeout $seconds
		1748
		1749	Sets the minimum idle timeout (default 10) after which worker threads are
		1750	allowed to exit. SEe C<IO::AIO::max_idle>.
		1751
1289	=item IO::AIO::max_outstanding $maxreqs	1752	=item IO::AIO::max_outstanding $maxreqs
		1753
		1754	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1755	you do queue up more than this number of requests, the next call to
		1756	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1757	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1758	longer exceeded.
		1759
		1760	In other words, this setting does not enforce a queue limit, but can be
		1761	used to make poll functions block if the limit is exceeded.
1290		1762
1291	This is a very bad function to use in interactive programs because it	1763	This is a very bad function to use in interactive programs because it
1292	blocks, and a bad way to reduce concurrency because it is inexact: Better	1764	blocks, and a bad way to reduce concurrency because it is inexact: Better
1293	use an C<aio_group> together with a feed callback.	1765	use an C<aio_group> together with a feed callback.
1294		1766
1295	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1767	It's main use is in scripts without an event loop - when you want to stat
1296	do queue up more than this number of requests, the next call to the	1768	a lot of files, you can write somehting like this:
1297	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1298	function will block until the limit is no longer exceeded.
1299		1769
1300	The default value is very large, so there is no practical limit on the	1770	IO::AIO::max_outstanding 32;
1301	number of outstanding requests.
1302		1771
1303	You can still queue as many requests as you want. Therefore,	1772	for my $path (...) {
1304	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1773	aio_stat $path , ...;
1305	as a stop gap to shield against fatal memory overflow (with large values).	1774	IO::AIO::poll_cb;
		1775	}
		1776
		1777	IO::AIO::flush;
		1778
		1779	The call to C<poll_cb> inside the loop will normally return instantly, but
		1780	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1781	some requests have been handled. This keeps the loop from pushing a large
		1782	number of C<aio_stat> requests onto the queue.
		1783
		1784	The default value for C<max_outstanding> is very large, so there is no
		1785	practical limit on the number of outstanding requests.
1306		1786
1307	=back	1787	=back
1308		1788
1309	=head3 STATISTICAL INFORMATION	1789	=head3 STATISTICAL INFORMATION
1310		1790
…		…
1330	Returns the number of requests currently in the pending state (executed,	1810	Returns the number of requests currently in the pending state (executed,
1331	but not yet processed by poll_cb).	1811	but not yet processed by poll_cb).
1332		1812
1333	=back	1813	=back
1334		1814
		1815	=head3 MISCELLANEOUS FUNCTIONS
		1816
		1817	IO::AIO implements some functions that might be useful, but are not
		1818	asynchronous.
		1819
		1820	=over 4
		1821
		1822	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1823
		1824	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1825	but is blocking (this makes most sense if you know the input data is
		1826	likely cached already and the output filehandle is set to non-blocking
		1827	operations).
		1828
		1829	Returns the number of bytes copied, or C<-1> on error.
		1830
		1831	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1832
		1833	Simply calls the C<posix_fadvise> function (see its
		1834	manpage for details). The following advice constants are
		1835	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1836	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1837	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1838
		1839	On systems that do not implement C<posix_fadvise>, this function returns
		1840	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1841
		1842	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1843
		1844	Simply calls the C<posix_madvise> function (see its
		1845	manpage for details). The following advice constants are
		1846	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1847	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1848
		1849	On systems that do not implement C<posix_madvise>, this function returns
		1850	ENOSYS, otherwise the return value of C<posix_madvise>.
		1851
		1852	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1853
		1854	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1855	$scalar (see its manpage for details). The following protect
		1856	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1857	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1858
		1859	On systems that do not implement C<mprotect>, this function returns
		1860	ENOSYS, otherwise the return value of C<mprotect>.
		1861
		1862	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1863
		1864	Memory-maps a file (or anonymous memory range) and attaches it to the
		1865	given C<$scalar>, which will act like a string scalar.
		1866
		1867	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1868	change the string length, and most read-only operations such as copying it
		1869	or searching it with regexes and so on.
		1870
		1871	Anything else is unsafe and will, at best, result in memory leaks.
		1872
		1873	The memory map associated with the C<$scalar> is automatically removed
		1874	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1875	C<IO::AIO::munmap> functions are called.
		1876
		1877	This calls the C<mmap>(2) function internally. See your system's manual
		1878	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1879
		1880	The C<$length> must be larger than zero and smaller than the actual
		1881	filesize.
		1882
		1883	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1884	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1885
		1886	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1887	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1888	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1889	(which is set to C<MAP_ANON> if your system only provides this
		1890	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1891	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1892	C<IO::AIO::MAP_NONBLOCK>
		1893
		1894	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1895
		1896	C<$offset> is the offset from the start of the file - it generally must be
		1897	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1898
		1899	Example:
		1900
		1901	use Digest::MD5;
		1902	use IO::AIO;
		1903
		1904	open my $fh, "<verybigfile"
		1905	or die "$!";
		1906
		1907	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1908	or die "verybigfile: $!";
		1909
		1910	my $fast_md5 = md5 $data;
		1911
		1912	=item IO::AIO::munmap $scalar
		1913
		1914	Removes a previous mmap and undefines the C<$scalar>.
		1915
		1916	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1917
		1918	Calls the C<munlock> function, undoing the effects of a previous
		1919	C<aio_mlock> call (see its description for details).
		1920
		1921	=item IO::AIO::munlockall
		1922
		1923	Calls the C<munlockall> function.
		1924
		1925	On systems that do not implement C<munlockall>, this function returns
		1926	ENOSYS, otherwise the return value of C<munlockall>.
		1927
		1928	=back
		1929
1335	=cut	1930	=cut
1336		1931
1337	min_parallel 8;	1932	min_parallel 8;
1338		1933
1339	END { flush }	1934	END { flush }
1340		1935
1341	1;	1936	1;
1342		1937
		1938	=head1 EVENT LOOP INTEGRATION
		1939
		1940	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1941	automatically into many event loops:
		1942
		1943	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1944	use AnyEvent::AIO;
		1945
		1946	You can also integrate IO::AIO manually into many event loops, here are
		1947	some examples of how to do this:
		1948
		1949	# EV integration
		1950	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1951
		1952	# Event integration
		1953	Event->io (fd => IO::AIO::poll_fileno,
		1954	poll => 'r',
		1955	cb => \&IO::AIO::poll_cb);
		1956
		1957	# Glib/Gtk2 integration
		1958	add_watch Glib::IO IO::AIO::poll_fileno,
		1959	in => sub { IO::AIO::poll_cb; 1 };
		1960
		1961	# Tk integration
		1962	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1963	readable => \&IO::AIO::poll_cb);
		1964
		1965	# Danga::Socket integration
		1966	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1967	\&IO::AIO::poll_cb);
		1968
1343	=head2 FORK BEHAVIOUR	1969	=head2 FORK BEHAVIOUR
1344		1970
1345	This module should do "the right thing" when the process using it forks:	1971	Usage of pthreads in a program changes the semantics of fork
		1972	considerably. Specifically, only async-safe functions can be called after
		1973	fork. Perl doesn't know about this, so in general, you cannot call fork
		1974	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		1975	pthreads, so this applies, but many other extensions and (for inexplicable
		1976	reasons) perl itself often is linked against pthreads, so this limitation
		1977	applies to quite a lot of perls.
1346		1978
1347	Before the fork, IO::AIO enters a quiescent state where no requests	1979	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1348	can be added in other threads and no results will be processed. After	1980	only works in the process that loaded it. Forking is fully supported, but
1349	the fork the parent simply leaves the quiescent state and continues	1981	using IO::AIO in the child is not.
1350	request/result processing, while the child frees the request/result queue
1351	(so that the requests started before the fork will only be handled in the
1352	parent). Threads will be started on demand until the limit set in the
1353	parent process has been reached again.
1354		1982
1355	In short: the parent will, after a short pause, continue as if fork had	1983	You might get around by not I<using> IO::AIO before (or after)
1356	not been called, while the child will act as if IO::AIO has not been used	1984	forking. You could also try to call the L<IO::AIO::reinit> function in the
1357	yet.	1985	child:
		1986
		1987	=over 4
		1988
		1989	=item IO::AIO::reinit
		1990
		1991	Abandons all current requests and I/O threads and simply reinitialises all
		1992	data structures. This is not an operation supported by any standards, but
		1993	happens to work on GNU/Linux and some newer BSD systems.
		1994
		1995	The only reasonable use for this function is to call it after forking, if
		1996	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		1997	the process will result in undefined behaviour. Calling it at any time
		1998	will also result in any undefined (by POSIX) behaviour.
		1999
		2000	=back
1358		2001
1359	=head2 MEMORY USAGE	2002	=head2 MEMORY USAGE
1360		2003
1361	Per-request usage:	2004	Per-request usage:
1362		2005

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