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Revision 1.147 by root, Wed Jun 3 12:24:49 2009 UTC vs.
Revision 1.215 by root, Tue Oct 4 18:22:37 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 (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 = '4.0';
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_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
		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_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		217	aio_readahead $fh,$offset,$length, $callback->($retval)
		218	aio_stat $fh_or_path, $callback->($status)
		219	aio_lstat $fh, $callback->($status)
		220	aio_statvfs $fh_or_path, $callback->($statvfs)
		221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		223	aio_truncate $fh_or_path, $offset, $callback->($status)
		224	aio_chmod $fh_or_path, $mode, $callback->($status)
		225	aio_unlink $pathname, $callback->($status)
		226	aio_mknod $pathname, $mode, $dev, $callback->($status)
		227	aio_link $srcpath, $dstpath, $callback->($status)
		228	aio_symlink $srcpath, $dstpath, $callback->($status)
		229	aio_readlink $pathname, $callback->($link)
		230	aio_realpath $pathname, $callback->($link)
		231	aio_rename $srcpath, $dstpath, $callback->($status)
		232	aio_mkdir $pathname, $mode, $callback->($status)
		233	aio_rmdir $pathname, $callback->($status)
		234	aio_readdir $pathname, $callback->($entries)
		235	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		236	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		237	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		238	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		239	aio_load $pathname, $data, $callback->($status)
		240	aio_copy $srcpath, $dstpath, $callback->($status)
		241	aio_move $srcpath, $dstpath, $callback->($status)
		242	aio_rmtree $pathname, $callback->($status)
		243	aio_sync $callback->($status)
		244	aio_syncfs $fh, $callback->($status)
		245	aio_fsync $fh, $callback->($status)
		246	aio_fdatasync $fh, $callback->($status)
		247	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		248	aio_pathsync $pathname, $callback->($status)
		249	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		250	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		251	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		252	aio_mlockall $flags, $callback->($status)
		253	aio_group $callback->(...)
		254	aio_nop $callback->()
		255
		256	$prev_pri = aioreq_pri [$pri]
		257	aioreq_nice $pri_adjust
		258
		259	IO::AIO::poll_wait
		260	IO::AIO::poll_cb
		261	IO::AIO::poll
		262	IO::AIO::flush
		263	IO::AIO::max_poll_reqs $nreqs
		264	IO::AIO::max_poll_time $seconds
		265	IO::AIO::min_parallel $nthreads
		266	IO::AIO::max_parallel $nthreads
		267	IO::AIO::max_idle $nthreads
		268	IO::AIO::idle_timeout $seconds
		269	IO::AIO::max_outstanding $maxreqs
		270	IO::AIO::nreqs
		271	IO::AIO::nready
		272	IO::AIO::npending
		273
		274	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		275	IO::AIO::fadvise $fh, $offset, $len, $advice
		276	IO::AIO::madvise $scalar, $offset, $length, $advice
		277	IO::AIO::mprotect $scalar, $offset, $length, $protect
		278	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		279	IO::AIO::munlockall
		280
224	=head2 AIO REQUEST FUNCTIONS	281	=head2 AIO REQUEST FUNCTIONS
225		282
226	All the C<aio_*> calls are more or less thin wrappers around the syscall	283	All the C<aio_*> calls are more or less thin wrappers around the syscall
227	with the same name (sans C<aio_>). The arguments are similar or identical,	284	with the same name (sans C<aio_>). The arguments are similar or identical,
228	and they all accept an additional (and optional) C<$callback> argument	285	and they all accept an additional (and optional) C<$callback> argument
229	which must be a code reference. This code reference will get called with	286	which must be a code reference. This code reference will be called after
230	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	287	the syscall has been executed in an asynchronous fashion. The results
231	perl, which usually delivers "false") as its sole argument after the given	288	of the request will be passed as arguments to the callback (and, if an
232	syscall has been executed asynchronously.	289	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		290	most syscalls return C<-1> on error, unlike perl, which usually delivers
		291	"false").
		292
		293	Some requests (such as C<aio_readdir>) pass the actual results and
		294	communicate failures by passing C<undef>.
233		295
234	All functions expecting a filehandle keep a copy of the filehandle	296	All functions expecting a filehandle keep a copy of the filehandle
235	internally until the request has finished.	297	internally until the request has finished.
236		298
237	All functions return request objects of type L<IO::AIO::REQ> that allow	299	All functions return request objects of type L<IO::AIO::REQ> that allow
238	further manipulation of those requests while they are in-flight.	300	further manipulation of those requests while they are in-flight.
239		301
240	The pathnames you pass to these routines I<must> be absolute and	302	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	303	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	304	current working directory could have changed. Alternatively, you can
243	changed. Alternatively, you can make sure that you never change the	305	make sure that you never change the current working directory anywhere
244	current working directory anywhere in the program and then use relative	306	in the program and then use relative paths. You can also take advantage
245	paths.	307	of IO::AIOs working directory abstraction, that lets you specify paths
		308	relative to some previously-opened "working directory object" - see the
		309	description of the C<IO::AIO::WD> class later in this document.
246		310
247	To encode pathnames as octets, either make sure you either: a) always pass	311	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	312	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	313	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	314	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)	315	effect in the user environment, d) use Glib::filename_from_unicode on
252	use something else to ensure your scalar has the correct contents.	316	unicode filenames or e) use something else to ensure your scalar has the
		317	correct contents.
253		318
254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	319	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255	handles correctly whether it is set or not.	320	handles correctly whether it is set or not.
256		321
257	=over 4	322	=over 4
…		…
307	by the umask in effect then the request is being executed, so better never	372	by the umask in effect then the request is being executed, so better never
308	change the umask.	373	change the umask.
309		374
310	Example:	375	Example:
311		376
312	aio_open "/etc/passwd", O_RDONLY, 0, sub {	377	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313	if ($_[0]) {	378	if ($_[0]) {
314	print "open successful, fh is $_[0]\n";	379	print "open successful, fh is $_[0]\n";
315	...	380	...
316	} else {	381	} else {
317	die "open failed: $!\n";	382	die "open failed: $!\n";
318	}	383	}
319	};	384	};
320		385
		386	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		387	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		388	following POSIX and non-POSIX constants are available (missing ones on
		389	your system are, as usual, C<0>):
		390
		391	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		392	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		393	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		394
321		395
322	=item aio_close $fh, $callback->($status)	396	=item aio_close $fh, $callback->($status)
323		397
324	Asynchronously close a file and call the callback with the result	398	Asynchronously close a file and call the callback with the result
325	code.	399	code.
…		…
375		449
376	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	450	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
377	reading at byte offset C<$in_offset>, and starts writing at the current	451	reading at byte offset C<$in_offset>, and starts writing at the current
378	file offset of C<$out_fh>. Because of that, it is not safe to issue more	452	file offset of C<$out_fh>. Because of that, it is not safe to issue more
379	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	453	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
380	other.	454	other. The same C<$in_fh> works fine though, as this function does not
		455	move or use the file offset of C<$in_fh>.
381		456
		457	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		458	are written, and there is no way to find out how many more bytes have been
		459	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		460	number of bytes written to C<$out_fh>. Only if the result value equals
		461	C<$length> one can assume that C<$length> bytes have been read.
		462
		463	Unlike with other C<aio_> functions, it makes a lot of sense to use
		464	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		465	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		466	the socket I/O will be non-blocking. Note, however, that you can run
		467	into a trap where C<aio_sendfile> reads some data with readahead, then
		468	fails to write all data, and when the socket is ready the next time, the
		469	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		470	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		471	resource usage.
		472
382	This call tries to make use of a native C<sendfile> syscall to provide	473	This call tries to make use of a native C<sendfile>-like syscall to
383	zero-copy operation. For this to work, C<$out_fh> should refer to a	474	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.	475	a socket, and C<$in_fh> should refer to an mmap'able file.
385		476
386	If the native sendfile call fails or is not implemented, it will be	477	If a native sendfile cannot be found or it fails with C<ENOSYS>,
387	emulated, so you can call C<aio_sendfile> on any type of filehandle	478	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		479	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
388	regardless of the limitations of the operating system.	480	type of filehandle regardless of the limitations of the operating system.
389		481
390	Please note, however, that C<aio_sendfile> can read more bytes from	482	As native sendfile syscalls (as practically any non-POSIX interface hacked
391	C<$in_fh> than are written, and there is no way to find out how many	483	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	484	on many systems, this implementation tries to work around some known bugs
393	provides the number of bytes written to C<$out_fh>. Only if the result	485	in Linux and FreeBSD kernels (probably others, too), but that might fail,
394	value equals C<$length> one can assume that C<$length> bytes have been	486	so you really really should check the return value of C<aio_sendfile> -
395	read.	487	fewre bytes than expected might have been transferred.
396		488
397		489
398	=item aio_readahead $fh,$offset,$length, $callback->($retval)	490	=item aio_readahead $fh,$offset,$length, $callback->($retval)
399		491
400	C<aio_readahead> populates the page cache with data from a file so that	492	C<aio_readahead> populates the page cache with data from a file so that
…		…
423		515
424	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	516	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	517	error when stat'ing a large file, the results will be silently truncated
426	unless perl itself is compiled with large file support.	518	unless perl itself is compiled with large file support.
427		519
		520	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		521	following constants and functions (if not implemented, the constants will
		522	be C<0> and the functions will either C<croak> or fall back on traditional
		523	behaviour).
		524
		525	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		526	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		527	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		528
428	Example: Print the length of F</etc/passwd>:	529	Example: Print the length of F</etc/passwd>:
429		530
430	aio_stat "/etc/passwd", sub {	531	aio_stat "/etc/passwd", sub {
431	$_[0] and die "stat failed: $!";	532	$_[0] and die "stat failed: $!";
432	print "size is ", -s _, "\n";	533	print "size is ", -s _, "\n";
433	};	534	};
434		535
435		536
		537	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		538
		539	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		540	whether a file handle or path was passed.
		541
		542	On success, the callback is passed a hash reference with the following
		543	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		544	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		545	is passed.
		546
		547	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		548	C<ST_NOSUID>.
		549
		550	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		551	their correct value when available, or to C<0> on systems that do
		552	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		553	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		554	C<ST_NODIRATIME> and C<ST_RELATIME>.
		555
		556	Example: stat C</wd> and dump out the data if successful.
		557
		558	aio_statvfs "/wd", sub {
		559	my $f = $_[0]
		560	or die "statvfs: $!";
		561
		562	use Data::Dumper;
		563	say Dumper $f;
		564	};
		565
		566	# result:
		567	{
		568	bsize => 1024,
		569	bfree => 4333064312,
		570	blocks => 10253828096,
		571	files => 2050765568,
		572	flag => 4096,
		573	favail => 2042092649,
		574	bavail => 4333064312,
		575	ffree => 2042092649,
		576	namemax => 255,
		577	frsize => 1024,
		578	fsid => 1810
		579	}
		580
		581
436	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	582	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
437		583
438	Works like perl's C<utime> function (including the special case of $atime	584	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	585	and $mtime being undef). Fractional times are supported if the underlying
440	syscalls support them.	586	syscalls support them.
…		…
478		624
479	Asynchronously unlink (delete) a file and call the callback with the	625	Asynchronously unlink (delete) a file and call the callback with the
480	result code.	626	result code.
481		627
482		628
483	=item aio_mknod $path, $mode, $dev, $callback->($status)	629	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
484		630
485	[EXPERIMENTAL]	631	[EXPERIMENTAL]
486		632
487	Asynchronously create a device node (or fifo). See mknod(2).	633	Asynchronously create a device node (or fifo). See mknod(2).
488		634
489	The only (POSIX-) portable way of calling this function is:	635	The only (POSIX-) portable way of calling this function is:
490		636
491	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	637	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
492		638
		639	See C<aio_stat> for info about some potentially helpful extra constants
		640	and functions.
493		641
494	=item aio_link $srcpath, $dstpath, $callback->($status)	642	=item aio_link $srcpath, $dstpath, $callback->($status)
495		643
496	Asynchronously create a new link to the existing object at C<$srcpath> at	644	Asynchronously create a new link to the existing object at C<$srcpath> at
497	the path C<$dstpath> and call the callback with the result code.	645	the path C<$dstpath> and call the callback with the result code.
…		…
501		649
502	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	650	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
503	the path C<$dstpath> and call the callback with the result code.	651	the path C<$dstpath> and call the callback with the result code.
504		652
505		653
506	=item aio_readlink $path, $callback->($link)	654	=item aio_readlink $pathname, $callback->($link)
507		655
508	Asynchronously read the symlink specified by C<$path> and pass it to	656	Asynchronously read the symlink specified by C<$path> and pass it to
509	the callback. If an error occurs, nothing or undef gets passed to the	657	the callback. If an error occurs, nothing or undef gets passed to the
510	callback.	658	callback.
511		659
512		660
		661	=item aio_realpath $pathname, $callback->($path)
		662
		663	Asynchronously make the path absolute and resolve any symlinks in
		664	C<$path>. The resulting path only consists of directories (Same as
		665	L<Cwd::realpath>).
		666
		667	This request can be used to get the absolute path of the current working
		668	directory by passing it a path of F<.> (a single dot).
		669
		670
513	=item aio_rename $srcpath, $dstpath, $callback->($status)	671	=item aio_rename $srcpath, $dstpath, $callback->($status)
514		672
515	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	673	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
516	rename(2) and call the callback with the result code.	674	rename(2) and call the callback with the result code.
517		675
…		…
533		691
534	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	692	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	693	directory (i.e. opendir + readdir + closedir). The entries will not be
536	sorted, and will B<NOT> include the C<.> and C<..> entries.	694	sorted, and will B<NOT> include the C<.> and C<..> entries.
537		695
538	The callback a single argument which is either C<undef> or an array-ref	696	The callback is passed a single argument which is either C<undef> or an
539	with the filenames.	697	array-ref with the filenames.
540		698
541		699
		700	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		701
		702	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		703	tune behaviour and output format. In case of an error, C<$entries> will be
		704	C<undef>.
		705
		706	The flags are a combination of the following constants, ORed together (the
		707	flags will also be passed to the callback, possibly modified):
		708
		709	=over 4
		710
		711	=item IO::AIO::READDIR_DENTS
		712
		713	When this flag is off, then the callback gets an arrayref consisting of
		714	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		715	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		716	entry in more detail.
		717
		718	C<$name> is the name of the entry.
		719
		720	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		721
		722	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		723	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		724	C<IO::AIO::DT_WHT>.
		725
		726	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		727	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		728	scalars are read-only: you can not modify them.
		729
		730	C<$inode> is the inode number (which might not be exact on systems with 64
		731	bit inode numbers and 32 bit perls). This field has unspecified content on
		732	systems that do not deliver the inode information.
		733
		734	=item IO::AIO::READDIR_DIRS_FIRST
		735
		736	When this flag is set, then the names will be returned in an order where
		737	likely directories come first, in optimal stat order. This is useful when
		738	you need to quickly find directories, or you want to find all directories
		739	while avoiding to stat() each entry.
		740
		741	If the system returns type information in readdir, then this is used
		742	to find directories directly. Otherwise, likely directories are names
		743	beginning with ".", or otherwise names with no dots, of which names with
		744	short names are tried first.
		745
		746	=item IO::AIO::READDIR_STAT_ORDER
		747
		748	When this flag is set, then the names will be returned in an order
		749	suitable for stat()'ing each one. That is, when you plan to stat()
		750	all files in the given directory, then the returned order will likely
		751	be fastest.
		752
		753	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		754	the likely dirs come first, resulting in a less optimal stat order.
		755
		756	=item IO::AIO::READDIR_FOUND_UNKNOWN
		757
		758	This flag should not be set when calling C<aio_readdirx>. Instead, it
		759	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		760	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		761	C<$type>'s are known, which can be used to speed up some algorithms.
		762
		763	=back
		764
		765
542	=item aio_load $path, $data, $callback->($status)	766	=item aio_load $pathname, $data, $callback->($status)
543		767
544	This is a composite request that tries to fully load the given file into	768	This is a composite request that tries to fully load the given file into
545	memory. Status is the same as with aio_read.	769	memory. Status is the same as with aio_read.
546		770
547	=cut	771	=cut
…		…
569		793
570	=item aio_copy $srcpath, $dstpath, $callback->($status)	794	=item aio_copy $srcpath, $dstpath, $callback->($status)
571		795
572	Try to copy the I<file> (directories not supported as either source or	796	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	797	destination) from C<$srcpath> to C<$dstpath> and call the callback with
574	the C<0> (error) or C<-1> ok.	798	a status of C<0> (ok) or C<-1> (error, see C<$!>).
575		799
576	This is a composite request that creates the destination file with	800	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	801	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	802	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
579	uid/gid, in that order.	803	uid/gid, in that order.
…		…
591	my $grp = aio_group $cb;	815	my $grp = aio_group $cb;
592		816
593	aioreq_pri $pri;	817	aioreq_pri $pri;
594	add $grp aio_open $src, O_RDONLY, 0, sub {	818	add $grp aio_open $src, O_RDONLY, 0, sub {
595	if (my $src_fh = $_[0]) {	819	if (my $src_fh = $_[0]) {
596	my @stat = stat $src_fh; # hmm, might bock over nfs?	820	my @stat = stat $src_fh; # hmm, might block over nfs?
597		821
598	aioreq_pri $pri;	822	aioreq_pri $pri;
599	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	823	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
600	if (my $dst_fh = $_[0]) {	824	if (my $dst_fh = $_[0]) {
601	aioreq_pri $pri;	825	aioreq_pri $pri;
…		…
648		872
649	=item aio_move $srcpath, $dstpath, $callback->($status)	873	=item aio_move $srcpath, $dstpath, $callback->($status)
650		874
651	Try to move the I<file> (directories not supported as either source or	875	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	876	destination) from C<$srcpath> to C<$dstpath> and call the callback with
653	the C<0> (error) or C<-1> ok.	877	a status of C<0> (ok) or C<-1> (error, see C<$!>).
654		878
655	This is a composite request that tries to rename(2) the file first; if	879	This is a composite request that tries to rename(2) the file first; if
656	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if	880	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
657	that is successful, unlinks the C<$srcpath>.	881	that is successful, unlinks the C<$srcpath>.
658		882
…		…
669	if ($_[0] && $! == EXDEV) {	893	if ($_[0] && $! == EXDEV) {
670	aioreq_pri $pri;	894	aioreq_pri $pri;
671	add $grp aio_copy $src, $dst, sub {	895	add $grp aio_copy $src, $dst, sub {
672	$grp->result ($_[0]);	896	$grp->result ($_[0]);
673		897
674	if (!$_[0]) {	898	unless ($_[0]) {
675	aioreq_pri $pri;	899	aioreq_pri $pri;
676	add $grp aio_unlink $src;	900	add $grp aio_unlink $src;
677	}	901	}
678	};	902	};
679	} else {	903	} else {
…		…
682	};	906	};
683		907
684	$grp	908	$grp
685	}	909	}
686		910
687	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	911	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
688		912
689	Scans a directory (similar to C<aio_readdir>) but additionally tries to	913	Scans a directory (similar to C<aio_readdir>) but additionally tries to
690	efficiently separate the entries of directory C<$path> into two sets of	914	efficiently separate the entries of directory C<$path> into two sets of
691	names, directories you can recurse into (directories), and ones you cannot	915	names, directories you can recurse into (directories), and ones you cannot
692	recurse into (everything else, including symlinks to directories).	916	recurse into (everything else, including symlinks to directories).
…		…
709		933
710	Implementation notes.	934	Implementation notes.
711		935
712	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	936	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
713		937
		938	If readdir returns file type information, then this is used directly to
		939	find directories.
		940
714	After reading the directory, the modification time, size etc. of the	941	Otherwise, after reading the directory, the modification time, size etc.
715	directory before and after the readdir is checked, and if they match (and	942	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	943	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	944	how many entries are directories (if >= 2). Otherwise, no knowledge of the
718	of subdirectories will be assumed.	945	number of subdirectories will be assumed.
719		946
720	Then entries will be sorted into likely directories (everything without	947	Then entries will be sorted into likely directories a non-initial dot
721	a non-initial dot currently) and likely non-directories (everything	948	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,	949	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	950	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	951	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	952	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	953	filesystems might detect the type of the entry without reading the inode
727	data (e.g. ext2fs filetype feature).	954	data (e.g. ext2fs filetype feature), even on systems that cannot return
		955	the filetype information on readdir.
728		956
729	If the known number of directories (link count - 2) has been reached, the	957	If the known number of directories (link count - 2) has been reached, the
730	rest of the entries is assumed to be non-directories.	958	rest of the entries is assumed to be non-directories.
731		959
732	This only works with certainty on POSIX (= UNIX) filesystems, which	960	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
745		973
746	my $grp = aio_group $cb;	974	my $grp = aio_group $cb;
747		975
748	$maxreq = 4 if $maxreq <= 0;	976	$maxreq = 4 if $maxreq <= 0;
749		977
750	# stat once	978	# get a wd object
751	aioreq_pri $pri;	979	aioreq_pri $pri;
752	add $grp aio_stat $path, sub {	980	add $grp aio_wd $path, sub {
		981	$_[0]
753	return $grp->result () if $_[0];	982	or return $grp->result ();
754	my $now = time;
755	my $hash1 = join ":", (stat _)[0,1,3,7,9];
756		983
757	# read the directory entries	984	my $wd = [shift, "."];
		985
		986	# stat once
758	aioreq_pri $pri;	987	aioreq_pri $pri;
759	add $grp aio_readdir $path, sub {	988	add $grp aio_stat $wd, sub {
760	my $entries = shift
761	or return $grp->result ();	989	return $grp->result () if $_[0];
		990	my $now = time;
		991	my $hash1 = join ":", (stat _)[0,1,3,7,9];
762		992
763	# stat the dir another time	993	# read the directory entries
764	aioreq_pri $pri;	994	aioreq_pri $pri;
		995	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		996	my $entries = shift
		997	or return $grp->result ();
		998
		999	# stat the dir another time
		1000	aioreq_pri $pri;
765	add $grp aio_stat $path, sub {	1001	add $grp aio_stat $wd, sub {
766	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1002	my $hash2 = join ":", (stat _)[0,1,3,7,9];
767		1003
768	my $ndirs;	1004	my $ndirs;
769		1005
770	# take the slow route if anything looks fishy	1006	# take the slow route if anything looks fishy
771	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1007	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
772	$ndirs = -1;	1008	$ndirs = -1;
773	} else {	1009	} else {
774	# if nlink == 2, we are finished	1010	# if nlink == 2, we are finished
775	# on non-posix-fs's, we rely on nlink < 2	1011	# for non-posix-fs's, we rely on nlink < 2
776	$ndirs = (stat _)[3] - 2	1012	$ndirs = (stat _)[3] - 2
777	or return $grp->result ([], $entries);	1013	or return $grp->result ([], $entries);
778	}	1014	}
779		1015
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);	1016	my (@dirs, @nondirs);
788		1017
789	my $statgrp = add $grp aio_group sub {	1018	my $statgrp = add $grp aio_group sub {
790	$grp->result (\@dirs, \@nondirs);	1019	$grp->result (\@dirs, \@nondirs);
791	};	1020	};
792		1021
793	limit $statgrp $maxreq;	1022	limit $statgrp $maxreq;
794	feed $statgrp sub {	1023	feed $statgrp sub {
795	return unless @$entries;	1024	return unless @$entries;
796	my $entry = pop @$entries;	1025	my $entry = shift @$entries;
797		1026
798	aioreq_pri $pri;	1027	aioreq_pri $pri;
		1028	$wd->[1] = "$entry/.";
799	add $statgrp aio_stat "$path/$entry/.", sub {	1029	add $statgrp aio_stat $wd, sub {
800	if ($_[0] < 0) {	1030	if ($_[0] < 0) {
801	push @nondirs, $entry;	1031	push @nondirs, $entry;
802	} else {	1032	} else {
803	# need to check for real directory	1033	# need to check for real directory
804	aioreq_pri $pri;	1034	aioreq_pri $pri;
		1035	$wd->[1] = $entry;
805	add $statgrp aio_lstat "$path/$entry", sub {	1036	add $statgrp aio_lstat $wd, sub {
806	if (-d _) {	1037	if (-d _) {
807	push @dirs, $entry;	1038	push @dirs, $entry;
808		1039
809	unless (--$ndirs) {	1040	unless (--$ndirs) {
810	push @nondirs, @$entries;	1041	push @nondirs, @$entries;
811	feed $statgrp;	1042	feed $statgrp;
		1043	}
		1044	} else {
		1045	push @nondirs, $entry;
812	}	1046	}
813	} else {
814	push @nondirs, $entry;
815	}	1047	}
816	}	1048	}
817	}	1049	};
818	};	1050	};
819	};	1051	};
820	};	1052	};
821	};	1053	};
822	};	1054	};
823		1055
824	$grp	1056	$grp
825	}	1057	}
826		1058
827	=item aio_rmtree $path, $callback->($status)	1059	=item aio_rmtree $pathname, $callback->($status)
828		1060
829	Delete a directory tree starting (and including) C<$path>, return the	1061	Delete a directory tree starting (and including) C<$path>, return the
830	status of the final C<rmdir> only. This is a composite request that	1062	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	1063	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
832	everything else.	1064	everything else.
…		…
874	callback with the fdatasync result code.	1106	callback with the fdatasync result code.
875		1107
876	If this call isn't available because your OS lacks it or it couldn't be	1108	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.	1109	detected, it will be emulated by calling C<fsync> instead.
878		1110
		1111	=item aio_syncfs $fh, $callback->($status)
		1112
		1113	Asynchronously call the syncfs syscall to sync the filesystem associated
		1114	to the given filehandle and call the callback with the syncfs result
		1115	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1116	errno to C<ENOSYS> nevertheless.
		1117
879	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1118	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
880		1119
881	Sync the data portion of the file specified by C<$offset> and C<$length>	1120	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	1121	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	1122	sync_file_range call. If sync_file_range is not available or it returns
…		…
886	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1125	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
887	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1126	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
888	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1127	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
889	manpage for details.	1128	manpage for details.
890		1129
891	=item aio_pathsync $path, $callback->($status)	1130	=item aio_pathsync $pathname, $callback->($status)
892		1131
893	This request tries to open, fsync and close the given path. This is a	1132	This request tries to open, fsync and close the given path. This is a
894	composite request intended to sync directories after directory operations	1133	composite request intended to sync directories after directory operations
895	(E.g. rename). This might not work on all operating systems or have any	1134	(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	1135	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,	1136	written to disc. It works for anything that can be opened for read-only,
898	not just directories.	1137	not just directories.
		1138
		1139	Future versions of this function might fall back to other methods when
		1140	C<fsync> on the directory fails (such as calling C<sync>).
899		1141
900	Passes C<0> when everything went ok, and C<-1> on error.	1142	Passes C<0> when everything went ok, and C<-1> on error.
901		1143
902	=cut	1144	=cut
903		1145
…		…
924	};	1166	};
925		1167
926	$grp	1168	$grp
927	}	1169	}
928		1170
		1171	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1172
		1173	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1174	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1175	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1176	scalar must only be modified in-place while an aio operation is pending on
		1177	it).
		1178
		1179	It calls the C<msync> function of your OS, if available, with the memory
		1180	area starting at C<$offset> in the string and ending C<$length> bytes
		1181	later. If C<$length> is negative, counts from the end, and if C<$length>
		1182	is C<undef>, then it goes till the end of the string. The flags can be
		1183	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1184	C<IO::AIO::MS_SYNC>.
		1185
		1186	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1187
		1188	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1189	scalars.
		1190
		1191	It touches (reads or writes) all memory pages in the specified
		1192	range inside the scalar. All caveats and parameters are the same
		1193	as for C<aio_msync>, above, except for flags, which must be either
		1194	C<0> (which reads all pages and ensures they are instantiated) or
		1195	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1196	writing an octet from it, which dirties the page).
		1197
		1198	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1199
		1200	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1201	scalars.
		1202
		1203	It reads in all the pages of the underlying storage into memory (if any)
		1204	and locks them, so they are not getting swapped/paged out or removed.
		1205
		1206	If C<$length> is undefined, then the scalar will be locked till the end.
		1207
		1208	On systems that do not implement C<mlock>, this function returns C<-1>
		1209	and sets errno to C<ENOSYS>.
		1210
		1211	Note that the corresponding C<munlock> is synchronous and is
		1212	documented under L<MISCELLANEOUS FUNCTIONS>.
		1213
		1214	Example: open a file, mmap and mlock it - both will be undone when
		1215	C<$data> gets destroyed.
		1216
		1217	open my $fh, "<", $path or die "$path: $!";
		1218	my $data;
		1219	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1220	aio_mlock $data; # mlock in background
		1221
		1222	=item aio_mlockall $flags, $callback->($status)
		1223
		1224	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1225	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1226
		1227	On systems that do not implement C<mlockall>, this function returns C<-1>
		1228	and sets errno to C<ENOSYS>.
		1229
		1230	Note that the corresponding C<munlockall> is synchronous and is
		1231	documented under L<MISCELLANEOUS FUNCTIONS>.
		1232
		1233	Example: asynchronously lock all current and future pages into memory.
		1234
		1235	aio_mlockall IO::AIO::MCL_FUTURE;
		1236
929	=item aio_group $callback->(...)	1237	=item aio_group $callback->(...)
930		1238
931	This is a very special aio request: Instead of doing something, it is a	1239	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	1240	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	1241	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	1278	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.	1279	except to put your application under artificial I/O pressure.
972		1280
973	=back	1281	=back
974		1282
		1283
		1284	=head2 IO::AIO::WD - multiple working directories
		1285
		1286	Your process only has one current working directory, which is used by all
		1287	threads. This makes it hard to use relative paths (some other component
		1288	could call C<chdir> at any time, and it is hard to control when the path
		1289	will be used by IO::AIO).
		1290
		1291	One solution for this is to always use absolute paths. This usually works,
		1292	but can be quite slow (the kernel has to walk the whole path on every
		1293	access), and can also be a hassle to implement.
		1294
		1295	Newer POSIX systems have a number of functions (openat, fdopendir,
		1296	futimensat and so on) that make it possible to specify working directories
		1297	per operation.
		1298
		1299	For portability, and because the clowns who "designed", or shall I write,
		1300	perpetrated this new interface were obviously half-drunk, this abstraction
		1301	cannot be perfect, though.
		1302
		1303	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1304	object. This object stores the canonicalised, absolute version of the
		1305	path, and on systems that allow it, also a directory file descriptor.
		1306
		1307	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1308	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1309	object and a pathname instead (or the IO::AIO::WD object alone, which
		1310	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1311	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1312	to that IO::AIO::WD object.
		1313
		1314	For example, to get a wd object for F</etc> and then stat F<passwd>
		1315	inside, you would write:
		1316
		1317	aio_wd "/etc", sub {
		1318	my $etcdir = shift;
		1319
		1320	# although $etcdir can be undef on error, there is generally no reason
		1321	# to check for errors here, as aio_stat will fail with ENOENT
		1322	# when $etcdir is undef.
		1323
		1324	aio_stat [$etcdir, "passwd"], sub {
		1325	# yay
		1326	};
		1327	};
		1328
		1329	That C<aio_wd> is a request and not a normal function shows that creating
		1330	an IO::AIO::WD object is itself a potentially blocking operation, which is
		1331	why it is done asynchronously.
		1332
		1333	To stat the directory obtained with C<aio_wd> above, one could write
		1334	either of the following three request calls:
		1335
		1336	aio_lstat "/etc" , sub { ... # pathname as normal string
		1337	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1338	aio_lstat $wd , sub { ... # shorthand for the previous
		1339
		1340	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1341	object and the pathname string, so you could write the following without
		1342	causing any issues due to C<$path> getting reused:
		1343
		1344	my $path = [$wd, undef];
		1345
		1346	for my $name (qw(abc def ghi)) {
		1347	$path->[1] = $name;
		1348	aio_stat $path, sub {
		1349	# ...
		1350	};
		1351	}
		1352
		1353	There are some caveats: when directories get renamed (or deleted), the
		1354	pathname string doesn't change, so will point to the new directory (or
		1355	nowhere at all), while the directory fd, if available on the system,
		1356	will still point to the original directory. Most functions accepting a
		1357	pathname will use the directory fd on newer systems, and the string on
		1358	older systems. Some functions (such as realpath) will always rely on the
		1359	string form of the pathname.
		1360
		1361	So this fucntionality is mainly useful to get some protection against
		1362	C<chdir>, to easily get an absolute path out of a relative path for future
		1363	reference, and to speed up doing many operations in the same directory
		1364	(e.g. when stat'ing all files in a directory).
		1365
		1366	The following functions implement this working directory abstraction:
		1367
		1368	=over 4
		1369
		1370	=item aio_wd $pathname, $callback->($wd)
		1371
		1372	Asynchonously canonicalise the given pathname and convert it to an
		1373	IO::AIO::WD object representing it. If possible and supported on the
		1374	system, also open a directory fd to speed up pathname resolution relative
		1375	to this working directory.
		1376
		1377	If something goes wrong, then C<undef> is passwd to the callback instead
		1378	of a working directory object and C<$!> is set appropriately. Since
		1379	passing C<undef> as working directory component of a pathname fails the
		1380	request with C<ENOENT>, there is often no need for error checking in the
		1381	C<aio_wd> callback, as future requests using the value will fail in the
		1382	expected way.
		1383
		1384	If this call isn't available because your OS lacks it or it couldn't be
		1385	detected, it will be emulated by calling C<fsync> instead.
		1386
		1387	=item IO::AIO::CWD
		1388
		1389	This is a compiletime constant (object) that represents the process
		1390	current working directory.
		1391
		1392	Specifying this object as working directory object for a pathname is as
		1393	if the pathname would be specified directly, without a directory object,
		1394	e.g., these calls are functionally identical:
		1395
		1396	aio_stat "somefile", sub { ... };
		1397	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1398
		1399	=back
		1400
		1401
975	=head2 IO::AIO::REQ CLASS	1402	=head2 IO::AIO::REQ CLASS
976		1403
977	All non-aggregate C<aio_*> functions return an object of this class when	1404	All non-aggregate C<aio_*> functions return an object of this class when
978	called in non-void context.	1405	called in non-void context.
979		1406
…		…
982	=item cancel $req	1409	=item cancel $req
983		1410
984	Cancels the request, if possible. Has the effect of skipping execution	1411	Cancels the request, if possible. Has the effect of skipping execution
985	when entering the B<execute> state and skipping calling the callback when	1412	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	1413	entering the the B<result> state, but will leave the request otherwise
987	untouched. That means that requests that currently execute will not be	1414	untouched (with the exception of readdir). That means that requests that
988	stopped and resources held by the request will not be freed prematurely.	1415	currently execute will not be stopped and resources held by the request
		1416	will not be freed prematurely.
989		1417
990	=item cb $req $callback->(...)	1418	=item cb $req $callback->(...)
991		1419
992	Replace (or simply set) the callback registered to the request.	1420	Replace (or simply set) the callback registered to the request.
993		1421
…		…
1067	=item $grp->cancel_subs	1495	=item $grp->cancel_subs
1068		1496
1069	Cancel all subrequests and clears any feeder, but not the group request	1497	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.	1498	itself. Useful when you queued a lot of events but got a result early.
1071		1499
		1500	The group request will finish normally (you cannot add requests to the
		1501	group).
		1502
1072	=item $grp->result (...)	1503	=item $grp->result (...)
1073		1504
1074	Set the result value(s) that will be passed to the group callback when all	1505	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	1506	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,	1507	of errno (just like calling C<errno> without an error number). By default,
…		…
1092		1523
1093	Sets a feeder/generator on this group: every group can have an attached	1524	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,	1525	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,	1526	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,	1527	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,	1528	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1098	delaying any later requests for a long time.	1529	requests, delaying any later requests for a long time.
1099		1530
1100	To avoid this, and allow incremental generation of requests, you can	1531	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	1532	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>,	1533	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	1534	below) requests active in the group itself and is expected to queue more
…		…
1144	=over 4	1575	=over 4
1145		1576
1146	=item $fileno = IO::AIO::poll_fileno	1577	=item $fileno = IO::AIO::poll_fileno
1147		1578
1148	Return the I<request result pipe file descriptor>. This filehandle must be	1579	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	1580	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	1581	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1151	to call C<poll_cb> to check the results.	1582	you have to call C<poll_cb> to check the results.
1152		1583
1153	See C<poll_cb> for an example.	1584	See C<poll_cb> for an example.
1154		1585
1155	=item IO::AIO::poll_cb	1586	=item IO::AIO::poll_cb
1156		1587
1157	Process some outstanding events on the result pipe. You have to call this	1588	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	1589	this regularly. Returns C<0> if all events could be processed (or there
1159	returned earlier for whatever reason. Returns immediately when no events	1590	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	1591	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>.	1592	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1593	C<IO::AIO::max_poll_time>.
1162		1594
1163	If not all requests were processed for whatever reason, the filehandle	1595	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	1596	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.	1597	do anything special to have it called later.
1166		1598
		1599	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1600	ready, it can be beneficial to call this function from loops which submit
		1601	a lot of requests, to make sure the results get processed when they become
		1602	available and not just when the loop is finished and the event loop takes
		1603	over again. This function returns very fast when there are no outstanding
		1604	requests.
		1605
1167	Example: Install an Event watcher that automatically calls	1606	Example: Install an Event watcher that automatically calls
1168	IO::AIO::poll_cb with high priority:	1607	IO::AIO::poll_cb with high priority (more examples can be found in the
		1608	SYNOPSIS section, at the top of this document):
1169		1609
1170	Event->io (fd => IO::AIO::poll_fileno,	1610	Event->io (fd => IO::AIO::poll_fileno,
1171	poll => 'r', async => 1,	1611	poll => 'r', async => 1,
1172	cb => \&IO::AIO::poll_cb);	1612	cb => \&IO::AIO::poll_cb);
		1613
		1614	=item IO::AIO::poll_wait
		1615
		1616	If there are any outstanding requests and none of them in the result
		1617	phase, wait till the result filehandle becomes ready for reading (simply
		1618	does a C<select> on the filehandle. This is useful if you want to
		1619	synchronously wait for some requests to finish).
		1620
		1621	See C<nreqs> for an example.
		1622
		1623	=item IO::AIO::poll
		1624
		1625	Waits until some requests have been handled.
		1626
		1627	Returns the number of requests processed, but is otherwise strictly
		1628	equivalent to:
		1629
		1630	IO::AIO::poll_wait, IO::AIO::poll_cb
		1631
		1632	=item IO::AIO::flush
		1633
		1634	Wait till all outstanding AIO requests have been handled.
		1635
		1636	Strictly equivalent to:
		1637
		1638	IO::AIO::poll_wait, IO::AIO::poll_cb
		1639	while IO::AIO::nreqs;
1173		1640
1174	=item IO::AIO::max_poll_reqs $nreqs	1641	=item IO::AIO::max_poll_reqs $nreqs
1175		1642
1176	=item IO::AIO::max_poll_time $seconds	1643	=item IO::AIO::max_poll_time $seconds
1177		1644
…		…
1202	# use a low priority so other tasks have priority	1669	# use a low priority so other tasks have priority
1203	Event->io (fd => IO::AIO::poll_fileno,	1670	Event->io (fd => IO::AIO::poll_fileno,
1204	poll => 'r', nice => 1,	1671	poll => 'r', nice => 1,
1205	cb => &IO::AIO::poll_cb);	1672	cb => &IO::AIO::poll_cb);
1206		1673
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	1674	=back
1235		1675
1236	=head3 CONTROLLING THE NUMBER OF THREADS	1676	=head3 CONTROLLING THE NUMBER OF THREADS
1237		1677
1238	=over	1678	=over
…		…
1271		1711
1272	Under normal circumstances you don't need to call this function.	1712	Under normal circumstances you don't need to call this function.
1273		1713
1274	=item IO::AIO::max_idle $nthreads	1714	=item IO::AIO::max_idle $nthreads
1275		1715
1276	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1716	Limit the number of threads (default: 4) that are allowed to idle
1277	threads that did not get a request to process within 10 seconds). That	1717	(i.e., threads that did not get a request to process within the idle
1278	means if a thread becomes idle while C<$nthreads> other threads are also	1718	timeout (default: 10 seconds). That means if a thread becomes idle while
1279	idle, it will free its resources and exit.	1719	C<$nthreads> other threads are also idle, it will free its resources and
		1720	exit.
1280		1721
1281	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1722	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	1723	to allow for extremely high load situations, but want to free resources
1283	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1724	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1284		1725
1285	The default is probably ok in most situations, especially if thread	1726	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	1727	creation is fast. If thread creation is very slow on your system you might
1287	want to use larger values.	1728	want to use larger values.
1288		1729
		1730	=item IO::AIO::idle_timeout $seconds
		1731
		1732	Sets the minimum idle timeout (default 10) after which worker threads are
		1733	allowed to exit. SEe C<IO::AIO::max_idle>.
		1734
1289	=item IO::AIO::max_outstanding $maxreqs	1735	=item IO::AIO::max_outstanding $maxreqs
		1736
		1737	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1738	you do queue up more than this number of requests, the next call to
		1739	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1740	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1741	longer exceeded.
		1742
		1743	In other words, this setting does not enforce a queue limit, but can be
		1744	used to make poll functions block if the limit is exceeded.
1290		1745
1291	This is a very bad function to use in interactive programs because it	1746	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	1747	blocks, and a bad way to reduce concurrency because it is inexact: Better
1293	use an C<aio_group> together with a feed callback.	1748	use an C<aio_group> together with a feed callback.
1294		1749
1295	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1750	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	1751	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		1752
1300	The default value is very large, so there is no practical limit on the	1753	IO::AIO::max_outstanding 32;
1301	number of outstanding requests.
1302		1754
1303	You can still queue as many requests as you want. Therefore,	1755	for my $path (...) {
1304	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1756	aio_stat $path , ...;
1305	as a stop gap to shield against fatal memory overflow (with large values).	1757	IO::AIO::poll_cb;
		1758	}
		1759
		1760	IO::AIO::flush;
		1761
		1762	The call to C<poll_cb> inside the loop will normally return instantly, but
		1763	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1764	some requests have been handled. This keeps the loop from pushing a large
		1765	number of C<aio_stat> requests onto the queue.
		1766
		1767	The default value for C<max_outstanding> is very large, so there is no
		1768	practical limit on the number of outstanding requests.
1306		1769
1307	=back	1770	=back
1308		1771
1309	=head3 STATISTICAL INFORMATION	1772	=head3 STATISTICAL INFORMATION
1310		1773
…		…
1330	Returns the number of requests currently in the pending state (executed,	1793	Returns the number of requests currently in the pending state (executed,
1331	but not yet processed by poll_cb).	1794	but not yet processed by poll_cb).
1332		1795
1333	=back	1796	=back
1334		1797
		1798	=head3 MISCELLANEOUS FUNCTIONS
		1799
		1800	IO::AIO implements some functions that might be useful, but are not
		1801	asynchronous.
		1802
		1803	=over 4
		1804
		1805	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1806
		1807	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1808	but is blocking (this makes most sense if you know the input data is
		1809	likely cached already and the output filehandle is set to non-blocking
		1810	operations).
		1811
		1812	Returns the number of bytes copied, or C<-1> on error.
		1813
		1814	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1815
		1816	Simply calls the C<posix_fadvise> function (see its
		1817	manpage for details). The following advice constants are
		1818	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1819	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1820	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1821
		1822	On systems that do not implement C<posix_fadvise>, this function returns
		1823	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1824
		1825	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1826
		1827	Simply calls the C<posix_madvise> function (see its
		1828	manpage for details). The following advice constants are
		1829	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1830	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1831
		1832	On systems that do not implement C<posix_madvise>, this function returns
		1833	ENOSYS, otherwise the return value of C<posix_madvise>.
		1834
		1835	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1836
		1837	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1838	$scalar (see its manpage for details). The following protect
		1839	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1840	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1841
		1842	On systems that do not implement C<mprotect>, this function returns
		1843	ENOSYS, otherwise the return value of C<mprotect>.
		1844
		1845	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1846
		1847	Memory-maps a file (or anonymous memory range) and attaches it to the
		1848	given C<$scalar>, which will act like a string scalar.
		1849
		1850	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1851	change the string length, and most read-only operations such as copying it
		1852	or searching it with regexes and so on.
		1853
		1854	Anything else is unsafe and will, at best, result in memory leaks.
		1855
		1856	The memory map associated with the C<$scalar> is automatically removed
		1857	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1858	C<IO::AIO::munmap> functions are called.
		1859
		1860	This calls the C<mmap>(2) function internally. See your system's manual
		1861	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1862
		1863	The C<$length> must be larger than zero and smaller than the actual
		1864	filesize.
		1865
		1866	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1867	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1868
		1869	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1870	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1871	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1872	(which is set to C<MAP_ANON> if your system only provides this
		1873	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1874	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1875	C<IO::AIO::MAP_NONBLOCK>
		1876
		1877	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1878
		1879	C<$offset> is the offset from the start of the file - it generally must be
		1880	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1881
		1882	Example:
		1883
		1884	use Digest::MD5;
		1885	use IO::AIO;
		1886
		1887	open my $fh, "<verybigfile"
		1888	or die "$!";
		1889
		1890	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1891	or die "verybigfile: $!";
		1892
		1893	my $fast_md5 = md5 $data;
		1894
		1895	=item IO::AIO::munmap $scalar
		1896
		1897	Removes a previous mmap and undefines the C<$scalar>.
		1898
		1899	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1900
		1901	Calls the C<munlock> function, undoing the effects of a previous
		1902	C<aio_mlock> call (see its description for details).
		1903
		1904	=item IO::AIO::munlockall
		1905
		1906	Calls the C<munlockall> function.
		1907
		1908	On systems that do not implement C<munlockall>, this function returns
		1909	ENOSYS, otherwise the return value of C<munlockall>.
		1910
		1911	=back
		1912
1335	=cut	1913	=cut
1336		1914
1337	min_parallel 8;	1915	min_parallel 8;
1338		1916
1339	END { flush }	1917	END { flush }
1340		1918
1341	1;	1919	1;
1342		1920
		1921	=head1 EVENT LOOP INTEGRATION
		1922
		1923	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1924	automatically into many event loops:
		1925
		1926	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1927	use AnyEvent::AIO;
		1928
		1929	You can also integrate IO::AIO manually into many event loops, here are
		1930	some examples of how to do this:
		1931
		1932	# EV integration
		1933	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1934
		1935	# Event integration
		1936	Event->io (fd => IO::AIO::poll_fileno,
		1937	poll => 'r',
		1938	cb => \&IO::AIO::poll_cb);
		1939
		1940	# Glib/Gtk2 integration
		1941	add_watch Glib::IO IO::AIO::poll_fileno,
		1942	in => sub { IO::AIO::poll_cb; 1 };
		1943
		1944	# Tk integration
		1945	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1946	readable => \&IO::AIO::poll_cb);
		1947
		1948	# Danga::Socket integration
		1949	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1950	\&IO::AIO::poll_cb);
		1951
1343	=head2 FORK BEHAVIOUR	1952	=head2 FORK BEHAVIOUR
1344		1953
1345	This module should do "the right thing" when the process using it forks:	1954	Usage of pthreads in a program changes the semantics of fork
		1955	considerably. Specifically, only async-safe functions can be called after
		1956	fork. Perl doesn't know about this, so in general, you cannot call fork
		1957	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		1958	pthreads, so this applies, but many other extensions and (for inexplicable
		1959	reasons) perl itself often is linked against pthreads, so this limitation
		1960	applies to quite a lot of perls.
1346		1961
1347	Before the fork, IO::AIO enters a quiescent state where no requests	1962	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	1963	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	1964	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		1965
1355	In short: the parent will, after a short pause, continue as if fork had	1966	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	1967	forking. You could also try to call the L<IO::AIO::reinit> function in the
1357	yet.	1968	child:
		1969
		1970	=over 4
		1971
		1972	=item IO::AIO::reinit
		1973
		1974	Abandons all current requests and I/O threads and simply reinitialises all
		1975	data structures. This is not an operation supported by any standards, but
		1976	happens to work on GNU/Linux and some newer BSD systems.
		1977
		1978	The only reasonable use for this function is to call it after forking, if
		1979	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		1980	the process will result in undefined behaviour. Calling it at any time
		1981	will also result in any undefined (by POSIX) behaviour.
		1982
		1983	=back
1358		1984
1359	=head2 MEMORY USAGE	1985	=head2 MEMORY USAGE
1360		1986
1361	Per-request usage:	1987	Per-request usage:
1362		1988

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