ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.124 by root, Sat May 10 19:25:33 2008 UTC vs.
Revision 1.271 by root, Fri Jun 23 21:43:51 2017 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous/Advanced Input/Output
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, urxvt, pureperl...)
32	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
33	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
34
35	# EV integration
36	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
37
38	# Event integration
39	Event->io (fd => IO::AIO::poll_fileno,
40	poll => 'r',
41	cb => \&IO::AIO::poll_cb);
42
43	# Glib/Gtk2 integration
44	add_watch Glib::IO IO::AIO::poll_fileno,
45	in => sub { IO::AIO::poll_cb; 1 };
46
47	# Tk integration
48	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
49	readable => \&IO::AIO::poll_cb);
50
51	# Danga::Socket integration
52	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
53	\&IO::AIO::poll_cb);
54
55	=head1 DESCRIPTION	31	=head1 DESCRIPTION
56		32
57	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
58	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>).
59		36
60	Asynchronous means that operations that can normally block your program	37	Asynchronous means that operations that can normally block your program
61	(e.g. reading from disk) will be done asynchronously: the operation	38	(e.g. reading from disk) will be done asynchronously: the operation
62	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
63	is extremely useful for programs that need to stay interactive even	40	is extremely useful for programs that need to stay interactive even
…		…
67	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
68	concurrently.	45	concurrently.
69		46
70	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
71	example sockets), using these functions on file descriptors that	48	example sockets), using these functions on file descriptors that
72	support nonblocking operation (again, sockets, pipes etc.) is very	49	support nonblocking operation (again, sockets, pipes etc.) is
73	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>
74	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.
75		52
76	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
77	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
78	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
…		…
81	not well-supported or restricted (GNU/Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
82	files currently, for example), and they would only support aio_read and	59	files currently, for example), and they would only support aio_read and
83	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
84	using threads anyway.	61	using threads anyway.
85		62
		63	In addition to asynchronous I/O, this module also exports some rather
		64	arcane interfaces, such as C<madvise> or linux's C<splice> system call,
		65	which is why the C<A> in C<AIO> can also mean I<advanced>.
		66
86	Although the module will work in the presence of other (Perl-) threads,	67	Although the module will work in the presence of other (Perl-) threads,
87	it is currently not reentrant in any way, so use appropriate locking	68	it is currently not reentrant in any way, so use appropriate locking
88	yourself, always call C<poll_cb> from within the same thread, or never	69	yourself, always call C<poll_cb> from within the same thread, or never
89	call C<poll_cb> (or other C<aio_> functions) recursively.	70	call C<poll_cb> (or other C<aio_> functions) recursively.
90		71
91	=head2 EXAMPLE	72	=head2 EXAMPLE
92		73
93	This is a simple example that uses the Event module and loads	74	This is a simple example that uses the EV module and loads
94	F</etc/passwd> asynchronously:	75	F</etc/passwd> asynchronously:
95		76
96	use Fcntl;
97	use Event;	77	use EV;
98	use IO::AIO;	78	use IO::AIO;
99		79
100	# register the IO::AIO callback with Event	80	# register the IO::AIO callback with EV
101	Event->io (fd => IO::AIO::poll_fileno,	81	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
102	poll => 'r',
103	cb => \&IO::AIO::poll_cb);
104		82
105	# queue the request to open /etc/passwd	83	# queue the request to open /etc/passwd
106	aio_open "/etc/passwd", O_RDONLY, 0, sub {	84	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
107	my $fh = shift	85	my $fh = shift
108	or die "error while opening: $!";	86	or die "error while opening: $!";
109		87
110	# stat'ing filehandles is generally non-blocking	88	# stat'ing filehandles is generally non-blocking
111	my $size = -s $fh;	89	my $size = -s $fh;
…		…
120		98
121	# file contents now in $contents	99	# file contents now in $contents
122	print $contents;	100	print $contents;
123		101
124	# exit event loop and program	102	# exit event loop and program
125	Event::unloop;	103	EV::break;
126	};	104	};
127	};	105	};
128		106
129	# possibly queue up other requests, or open GUI windows,	107	# possibly queue up other requests, or open GUI windows,
130	# check for sockets etc. etc.	108	# check for sockets etc. etc.
131		109
132	# process events as long as there are some:	110	# process events as long as there are some:
133	Event::loop;	111	EV::run;
134		112
135	=head1 REQUEST ANATOMY AND LIFETIME	113	=head1 REQUEST ANATOMY AND LIFETIME
136		114
137	Every C<aio_*> function creates a request. which is a C data structure not	115	Every C<aio_*> function creates a request. which is a C data structure not
138	directly visible to Perl.	116	directly visible to Perl.
…		…
188		166
189	package IO::AIO;	167	package IO::AIO;
190		168
191	use Carp ();	169	use Carp ();
192		170
193	no warnings;	171	use common::sense;
194	use strict 'vars';
195		172
196	use base 'Exporter';	173	use base 'Exporter';
197		174
198	BEGIN {	175	BEGIN {
199	our $VERSION = '3.0';	176	our $VERSION = 4.35;
200		177
201	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	178	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
202	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir	179	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
203	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	180	aio_scandir aio_symlink aio_readlink aio_realpath aio_fcntl aio_ioctl
204	aio_fdatasync aio_pathsync aio_readahead	181	aio_sync aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range
		182	aio_pathsync aio_readahead aio_fiemap aio_allocate
205	aio_rename aio_link aio_move aio_copy aio_group	183	aio_rename aio_rename2 aio_link aio_move aio_copy aio_group
206	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	184	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
207	aio_chmod aio_utime aio_truncate);	185	aio_chmod aio_utime aio_truncate
		186	aio_msync aio_mtouch aio_mlock aio_mlockall
		187	aio_statvfs
		188	aio_wd);
208		189
209	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	190	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
210	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	191	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
211	min_parallel max_parallel max_idle	192	min_parallel max_parallel max_idle idle_timeout
212	nreqs nready npending nthreads	193	nreqs nready npending nthreads
213	max_poll_time max_poll_reqs);	194	max_poll_time max_poll_reqs
		195	sendfile fadvise madvise
		196	mmap munmap munlock munlockall);
		197
		198	push @AIO_REQ, qw(aio_busy); # not exported
214		199
215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	200	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
216		201
217	require XSLoader;	202	require XSLoader;
218	XSLoader::load ("IO::AIO", $VERSION);	203	XSLoader::load ("IO::AIO", $VERSION);
219	}	204	}
220		205
221	=head1 FUNCTIONS	206	=head1 FUNCTIONS
222		207
223	=head2 AIO REQUEST FUNCTIONS	208	=head2 QUICK OVERVIEW
		209
		210	This section simply lists the prototypes most of the functions for
		211	quick reference. See the following sections for function-by-function
		212	documentation.
		213
		214	aio_wd $pathname, $callback->($wd)
		215	aio_open $pathname, $flags, $mode, $callback->($fh)
		216	aio_close $fh, $callback->($status)
		217	aio_seek $fh,$offset,$whence, $callback->($offs)
		218	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		219	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		220	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		221	aio_readahead $fh,$offset,$length, $callback->($retval)
		222	aio_stat $fh_or_path, $callback->($status)
		223	aio_lstat $fh, $callback->($status)
		224	aio_statvfs $fh_or_path, $callback->($statvfs)
		225	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		226	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		227	aio_chmod $fh_or_path, $mode, $callback->($status)
		228	aio_truncate $fh_or_path, $offset, $callback->($status)
		229	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		230	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		231	aio_unlink $pathname, $callback->($status)
		232	aio_mknod $pathname, $mode, $dev, $callback->($status)
		233	aio_link $srcpath, $dstpath, $callback->($status)
		234	aio_symlink $srcpath, $dstpath, $callback->($status)
		235	aio_readlink $pathname, $callback->($link)
		236	aio_realpath $pathname, $callback->($path)
		237	aio_rename $srcpath, $dstpath, $callback->($status)
		238	aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		239	aio_mkdir $pathname, $mode, $callback->($status)
		240	aio_rmdir $pathname, $callback->($status)
		241	aio_readdir $pathname, $callback->($entries)
		242	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		243	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		244	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		245	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		246	aio_load $pathname, $data, $callback->($status)
		247	aio_copy $srcpath, $dstpath, $callback->($status)
		248	aio_move $srcpath, $dstpath, $callback->($status)
		249	aio_rmtree $pathname, $callback->($status)
		250	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		251	aio_ioctl $fh, $request, $buf, $callback->($status)
		252	aio_sync $callback->($status)
		253	aio_syncfs $fh, $callback->($status)
		254	aio_fsync $fh, $callback->($status)
		255	aio_fdatasync $fh, $callback->($status)
		256	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		257	aio_pathsync $pathname, $callback->($status)
		258	aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
		259	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		260	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		261	aio_mlockall $flags, $callback->($status)
		262	aio_group $callback->(...)
		263	aio_nop $callback->()
		264
		265	$prev_pri = aioreq_pri [$pri]
		266	aioreq_nice $pri_adjust
		267
		268	IO::AIO::poll_wait
		269	IO::AIO::poll_cb
		270	IO::AIO::poll
		271	IO::AIO::flush
		272	IO::AIO::max_poll_reqs $nreqs
		273	IO::AIO::max_poll_time $seconds
		274	IO::AIO::min_parallel $nthreads
		275	IO::AIO::max_parallel $nthreads
		276	IO::AIO::max_idle $nthreads
		277	IO::AIO::idle_timeout $seconds
		278	IO::AIO::max_outstanding $maxreqs
		279	IO::AIO::nreqs
		280	IO::AIO::nready
		281	IO::AIO::npending
		282
		283	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		284	IO::AIO::fadvise $fh, $offset, $len, $advice
		285	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		286	IO::AIO::munmap $scalar
		287	IO::AIO::madvise $scalar, $offset, $length, $advice
		288	IO::AIO::mprotect $scalar, $offset, $length, $protect
		289	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		290	IO::AIO::munlockall
		291
		292	=head2 API NOTES
224		293
225	All the C<aio_*> calls are more or less thin wrappers around the syscall	294	All the C<aio_*> calls are more or less thin wrappers around the syscall
226	with the same name (sans C<aio_>). The arguments are similar or identical,	295	with the same name (sans C<aio_>). The arguments are similar or identical,
227	and they all accept an additional (and optional) C<$callback> argument	296	and they all accept an additional (and optional) C<$callback> argument
228	which must be a code reference. This code reference will get called with	297	which must be a code reference. This code reference will be called after
229	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	298	the syscall has been executed in an asynchronous fashion. The results
230	perl, which usually delivers "false") as it's sole argument when the given	299	of the request will be passed as arguments to the callback (and, if an
231	syscall has been executed asynchronously.	300	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		301	most syscalls return C<-1> on error, unlike perl, which usually delivers
		302	"false").
		303
		304	Some requests (such as C<aio_readdir>) pass the actual results and
		305	communicate failures by passing C<undef>.
232		306
233	All functions expecting a filehandle keep a copy of the filehandle	307	All functions expecting a filehandle keep a copy of the filehandle
234	internally until the request has finished.	308	internally until the request has finished.
235		309
236	All functions return request objects of type L<IO::AIO::REQ> that allow	310	All functions return request objects of type L<IO::AIO::REQ> that allow
237	further manipulation of those requests while they are in-flight.	311	further manipulation of those requests while they are in-flight.
238		312
239	The pathnames you pass to these routines I<must> be absolute and	313	The pathnames you pass to these routines I<should> be absolute. The
240	encoded as octets. The reason for the former is that at the time the	314	reason for this is that at the time the request is being executed, the
241	request is being executed, the current working directory could have	315	current working directory could have changed. Alternatively, you can
242	changed. Alternatively, you can make sure that you never change the	316	make sure that you never change the current working directory anywhere
243	current working directory anywhere in the program and then use relative	317	in the program and then use relative paths. You can also take advantage
244	paths.	318	of IO::AIOs working directory abstraction, that lets you specify paths
		319	relative to some previously-opened "working directory object" - see the
		320	description of the C<IO::AIO::WD> class later in this document.
245		321
246	To encode pathnames as octets, either make sure you either: a) always pass	322	To encode pathnames as octets, either make sure you either: a) always pass
247	in filenames you got from outside (command line, readdir etc.) without	323	in filenames you got from outside (command line, readdir etc.) without
248	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	324	tinkering, b) are in your native filesystem encoding, c) use the Encode
249	your pathnames to the locale (or other) encoding in effect in the user	325	module and encode your pathnames to the locale (or other) encoding in
250	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	326	effect in the user environment, d) use Glib::filename_from_unicode on
251	use something else to ensure your scalar has the correct contents.	327	unicode filenames or e) use something else to ensure your scalar has the
		328	correct contents.
252		329
253	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	330	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
254	handles correctly wether it is set or not.	331	handles correctly whether it is set or not.
		332
		333	=head2 AIO REQUEST FUNCTIONS
255		334
256	=over 4	335	=over 4
257		336
258	=item $prev_pri = aioreq_pri [$pri]	337	=item $prev_pri = aioreq_pri [$pri]
259		338
…		…
289		368
290		369
291	=item aio_open $pathname, $flags, $mode, $callback->($fh)	370	=item aio_open $pathname, $flags, $mode, $callback->($fh)
292		371
293	Asynchronously open or create a file and call the callback with a newly	372	Asynchronously open or create a file and call the callback with a newly
294	created filehandle for the file.	373	created filehandle for the file (or C<undef> in case of an error).
295		374
296	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	375	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
297	for an explanation.	376	for an explanation.
298		377
299	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a	378	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
…		…
306	by the umask in effect then the request is being executed, so better never	385	by the umask in effect then the request is being executed, so better never
307	change the umask.	386	change the umask.
308		387
309	Example:	388	Example:
310		389
311	aio_open "/etc/passwd", O_RDONLY, 0, sub {	390	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
312	if ($_[0]) {	391	if ($_[0]) {
313	print "open successful, fh is $_[0]\n";	392	print "open successful, fh is $_[0]\n";
314	...	393	...
315	} else {	394	} else {
316	die "open failed: $!\n";	395	die "open failed: $!\n";
317	}	396	}
318	};	397	};
319		398
		399	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		400	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		401	following POSIX and non-POSIX constants are available (missing ones on
		402	your system are, as usual, C<0>):
		403
		404	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		405	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		406	C<O_RSYNC>, C<O_SYNC>, C<O_PATH>, C<O_TMPFILE>, and C<O_TTY_INIT>.
		407
320		408
321	=item aio_close $fh, $callback->($status)	409	=item aio_close $fh, $callback->($status)
322		410
323	Asynchronously close a file and call the callback with the result	411	Asynchronously close a file and call the callback with the result
324	code.	412	code.
…		…
333	Or in other words: the file descriptor will be closed, but it will not be	421	Or in other words: the file descriptor will be closed, but it will not be
334	free for reuse until the perl filehandle is closed.	422	free for reuse until the perl filehandle is closed.
335		423
336	=cut	424	=cut
337		425
		426	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		427
		428	Seeks the filehandle to the new C<$offset>, similarly to perl's
		429	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		430	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		431	C<IO::AIO::SEEK_END>).
		432
		433	The resulting absolute offset will be passed to the callback, or C<-1> in
		434	case of an error.
		435
		436	In theory, the C<$whence> constants could be different than the
		437	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		438	so don't panic.
		439
		440	As a GNU/Linux (and maybe Solaris) extension, also the constants
		441	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		442	could be found. No guarantees about suitability for use in C<aio_seek> or
		443	Perl's C<sysseek> can be made though, although I would naively assume they
		444	"just work".
		445
338	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	446	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
339		447
340	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	448	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
341		449
342	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>	450	Reads or writes C<$length> bytes from or to the specified C<$fh> and
343	into the scalar given by C<$data> and offset C<$dataoffset> and calls the	451	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset> and
344	callback without the actual number of bytes read (or -1 on error, just	452	calls the callback with the actual number of bytes transferred (or -1 on
345	like the syscall).	453	error, just like the syscall).
		454
		455	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		456	offset plus the actual number of bytes read.
346		457
347	If C<$offset> is undefined, then the current file descriptor offset will	458	If C<$offset> is undefined, then the current file descriptor offset will
348	be used (and updated), otherwise the file descriptor offset will not be	459	be used (and updated), otherwise the file descriptor offset will not be
349	changed by these calls.	460	changed by these calls.
350		461
351	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.	462	If C<$length> is undefined in C<aio_write>, use the remaining length of
		463	C<$data>.
352		464
353	If C<$dataoffset> is less than zero, it will be counted from the end of	465	If C<$dataoffset> is less than zero, it will be counted from the end of
354	C<$data>.	466	C<$data>.
355		467
356	The C<$data> scalar I<MUST NOT> be modified in any way while the request	468	The C<$data> scalar I<MUST NOT> be modified in any way while the request
…		…
370		482
371	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	483	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
372	reading at byte offset C<$in_offset>, and starts writing at the current	484	reading at byte offset C<$in_offset>, and starts writing at the current
373	file offset of C<$out_fh>. Because of that, it is not safe to issue more	485	file offset of C<$out_fh>. Because of that, it is not safe to issue more
374	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	486	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
375	other.	487	other. The same C<$in_fh> works fine though, as this function does not
		488	move or use the file offset of C<$in_fh>.
376		489
		490	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		491	are written, and there is no way to find out how many more bytes have been
		492	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		493	number of bytes written to C<$out_fh>. Only if the result value equals
		494	C<$length> one can assume that C<$length> bytes have been read.
		495
		496	Unlike with other C<aio_> functions, it makes a lot of sense to use
		497	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		498	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		499	the socket I/O will be non-blocking. Note, however, that you can run
		500	into a trap where C<aio_sendfile> reads some data with readahead, then
		501	fails to write all data, and when the socket is ready the next time, the
		502	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		503	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		504	resource usage.
		505
377	This call tries to make use of a native C<sendfile> syscall to provide	506	This call tries to make use of a native C<sendfile>-like syscall to
378	zero-copy operation. For this to work, C<$out_fh> should refer to a	507	provide zero-copy operation. For this to work, C<$out_fh> should refer to
379	socket, and C<$in_fh> should refer to mmap'able file.	508	a socket, and C<$in_fh> should refer to an mmap'able file.
380		509
381	If the native sendfile call fails or is not implemented, it will be	510	If a native sendfile cannot be found or it fails with C<ENOSYS>,
382	emulated, so you can call C<aio_sendfile> on any type of filehandle	511	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		512	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
383	regardless of the limitations of the operating system.	513	type of filehandle regardless of the limitations of the operating system.
384		514
385	Please note, however, that C<aio_sendfile> can read more bytes from	515	As native sendfile syscalls (as practically any non-POSIX interface hacked
386	C<$in_fh> than are written, and there is no way to find out how many	516	together in a hurry to improve benchmark numbers) tend to be rather buggy
387	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	517	on many systems, this implementation tries to work around some known bugs
388	provides the number of bytes written to C<$out_fh>. Only if the result	518	in Linux and FreeBSD kernels (probably others, too), but that might fail,
389	value equals C<$length> one can assume that C<$length> bytes have been	519	so you really really should check the return value of C<aio_sendfile> -
390	read.	520	fewer bytes than expected might have been transferred.
391		521
392		522
393	=item aio_readahead $fh,$offset,$length, $callback->($retval)	523	=item aio_readahead $fh,$offset,$length, $callback->($retval)
394		524
395	C<aio_readahead> populates the page cache with data from a file so that	525	C<aio_readahead> populates the page cache with data from a file so that
…		…
399	whole pages, so that offset is effectively rounded down to a page boundary	529	whole pages, so that offset is effectively rounded down to a page boundary
400	and bytes are read up to the next page boundary greater than or equal to	530	and bytes are read up to the next page boundary greater than or equal to
401	(off-set+length). C<aio_readahead> does not read beyond the end of the	531	(off-set+length). C<aio_readahead> does not read beyond the end of the
402	file. The current file offset of the file is left unchanged.	532	file. The current file offset of the file is left unchanged.
403		533
404	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	534	If that syscall doesn't exist (likely if your kernel isn't Linux) it will
405	emulated by simply reading the data, which would have a similar effect.	535	be emulated by simply reading the data, which would have a similar effect.
406		536
407		537
408	=item aio_stat $fh_or_path, $callback->($status)	538	=item aio_stat $fh_or_path, $callback->($status)
409		539
410	=item aio_lstat $fh, $callback->($status)	540	=item aio_lstat $fh, $callback->($status)
…		…
417	for an explanation.	547	for an explanation.
418		548
419	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	549	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
420	error when stat'ing a large file, the results will be silently truncated	550	error when stat'ing a large file, the results will be silently truncated
421	unless perl itself is compiled with large file support.	551	unless perl itself is compiled with large file support.
		552
		553	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		554	following constants and functions (if not implemented, the constants will
		555	be C<0> and the functions will either C<croak> or fall back on traditional
		556	behaviour).
		557
		558	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		559	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		560	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
422		561
423	Example: Print the length of F</etc/passwd>:	562	Example: Print the length of F</etc/passwd>:
424		563
425	aio_stat "/etc/passwd", sub {	564	aio_stat "/etc/passwd", sub {
426	$_[0] and die "stat failed: $!";	565	$_[0] and die "stat failed: $!";
427	print "size is ", -s _, "\n";	566	print "size is ", -s _, "\n";
428	};	567	};
429		568
430		569
		570	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		571
		572	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		573	whether a file handle or path was passed.
		574
		575	On success, the callback is passed a hash reference with the following
		576	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		577	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		578	is passed.
		579
		580	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		581	C<ST_NOSUID>.
		582
		583	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		584	their correct value when available, or to C<0> on systems that do
		585	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		586	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		587	C<ST_NODIRATIME> and C<ST_RELATIME>.
		588
		589	Example: stat C</wd> and dump out the data if successful.
		590
		591	aio_statvfs "/wd", sub {
		592	my $f = $_[0]
		593	or die "statvfs: $!";
		594
		595	use Data::Dumper;
		596	say Dumper $f;
		597	};
		598
		599	# result:
		600	{
		601	bsize => 1024,
		602	bfree => 4333064312,
		603	blocks => 10253828096,
		604	files => 2050765568,
		605	flag => 4096,
		606	favail => 2042092649,
		607	bavail => 4333064312,
		608	ffree => 2042092649,
		609	namemax => 255,
		610	frsize => 1024,
		611	fsid => 1810
		612	}
		613
		614	Here is a (likely partial - send me updates!) list of fsid values used by
		615	Linux - it is safe to hardcode these when C<$^O> is C<linux>:
		616
		617	0x0000adf5 adfs
		618	0x0000adff affs
		619	0x5346414f afs
		620	0x09041934 anon-inode filesystem
		621	0x00000187 autofs
		622	0x42465331 befs
		623	0x1badface bfs
		624	0x42494e4d binfmt_misc
		625	0x9123683e btrfs
		626	0x0027e0eb cgroupfs
		627	0xff534d42 cifs
		628	0x73757245 coda
		629	0x012ff7b7 coh
		630	0x28cd3d45 cramfs
		631	0x453dcd28 cramfs-wend (wrong endianness)
		632	0x64626720 debugfs
		633	0x00001373 devfs
		634	0x00001cd1 devpts
		635	0x0000f15f ecryptfs
		636	0x00414a53 efs
		637	0x0000137d ext
		638	0x0000ef53 ext2/ext3/ext4
		639	0x0000ef51 ext2
		640	0xf2f52010 f2fs
		641	0x00004006 fat
		642	0x65735546 fuseblk
		643	0x65735543 fusectl
		644	0x0bad1dea futexfs
		645	0x01161970 gfs2
		646	0x47504653 gpfs
		647	0x00004244 hfs
		648	0xf995e849 hpfs
		649	0x00c0ffee hostfs
		650	0x958458f6 hugetlbfs
		651	0x2bad1dea inotifyfs
		652	0x00009660 isofs
		653	0x000072b6 jffs2
		654	0x3153464a jfs
		655	0x6b414653 k-afs
		656	0x0bd00bd0 lustre
		657	0x0000137f minix
		658	0x0000138f minix 30 char names
		659	0x00002468 minix v2
		660	0x00002478 minix v2 30 char names
		661	0x00004d5a minix v3
		662	0x19800202 mqueue
		663	0x00004d44 msdos
		664	0x0000564c novell
		665	0x00006969 nfs
		666	0x6e667364 nfsd
		667	0x00003434 nilfs
		668	0x5346544e ntfs
		669	0x00009fa1 openprom
		670	0x7461636F ocfs2
		671	0x00009fa0 proc
		672	0x6165676c pstorefs
		673	0x0000002f qnx4
		674	0x68191122 qnx6
		675	0x858458f6 ramfs
		676	0x52654973 reiserfs
		677	0x00007275 romfs
		678	0x67596969 rpc_pipefs
		679	0x73636673 securityfs
		680	0xf97cff8c selinux
		681	0x0000517b smb
		682	0x534f434b sockfs
		683	0x73717368 squashfs
		684	0x62656572 sysfs
		685	0x012ff7b6 sysv2
		686	0x012ff7b5 sysv4
		687	0x01021994 tmpfs
		688	0x15013346 udf
		689	0x00011954 ufs
		690	0x54190100 ufs byteswapped
		691	0x00009fa2 usbdevfs
		692	0x01021997 v9fs
		693	0xa501fcf5 vxfs
		694	0xabba1974 xenfs
		695	0x012ff7b4 xenix
		696	0x58465342 xfs
		697	0x012fd16d xia
		698
431	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	699	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
432		700
433	Works like perl's C<utime> function (including the special case of $atime	701	Works like perl's C<utime> function (including the special case of $atime
434	and $mtime being undef). Fractional times are supported if the underlying	702	and $mtime being undef). Fractional times are supported if the underlying
435	syscalls support them.	703	syscalls support them.
…		…
462	=item aio_truncate $fh_or_path, $offset, $callback->($status)	730	=item aio_truncate $fh_or_path, $offset, $callback->($status)
463		731
464	Works like truncate(2) or ftruncate(2).	732	Works like truncate(2) or ftruncate(2).
465		733
466		734
		735	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		736
		737	Allocates or frees disk space according to the C<$mode> argument. See the
		738	linux C<fallocate> documentation for details.
		739
		740	C<$mode> is usually C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE> to allocate
		741	space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE | IO::AIO::FALLOC_FL_KEEP_SIZE>,
		742	to deallocate a file range.
		743
		744	IO::AIO also supports C<FALLOC_FL_COLLAPSE_RANGE>, to remove a range
		745	(without leaving a hole) and C<FALLOC_FL_ZERO_RANGE>, to zero a range (see
		746	your L<fallocate(2)> manpage).
		747
		748	The file system block size used by C<fallocate> is presumably the
		749	C<f_bsize> returned by C<statvfs>.
		750
		751	If C<fallocate> isn't available or cannot be emulated (currently no
		752	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		753
		754
467	=item aio_chmod $fh_or_path, $mode, $callback->($status)	755	=item aio_chmod $fh_or_path, $mode, $callback->($status)
468		756
469	Works like perl's C<chmod> function.	757	Works like perl's C<chmod> function.
470		758
471		759
…		…
473		761
474	Asynchronously unlink (delete) a file and call the callback with the	762	Asynchronously unlink (delete) a file and call the callback with the
475	result code.	763	result code.
476		764
477		765
478	=item aio_mknod $path, $mode, $dev, $callback->($status)	766	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
479		767
480	[EXPERIMENTAL]	768	[EXPERIMENTAL]
481		769
482	Asynchronously create a device node (or fifo). See mknod(2).	770	Asynchronously create a device node (or fifo). See mknod(2).
483		771
484	The only (POSIX-) portable way of calling this function is:	772	The only (POSIX-) portable way of calling this function is:
485		773
486	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	774	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
487		775
		776	See C<aio_stat> for info about some potentially helpful extra constants
		777	and functions.
488		778
489	=item aio_link $srcpath, $dstpath, $callback->($status)	779	=item aio_link $srcpath, $dstpath, $callback->($status)
490		780
491	Asynchronously create a new link to the existing object at C<$srcpath> at	781	Asynchronously create a new link to the existing object at C<$srcpath> at
492	the path C<$dstpath> and call the callback with the result code.	782	the path C<$dstpath> and call the callback with the result code.
…		…
496		786
497	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	787	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
498	the path C<$dstpath> and call the callback with the result code.	788	the path C<$dstpath> and call the callback with the result code.
499		789
500		790
501	=item aio_readlink $path, $callback->($link)	791	=item aio_readlink $pathname, $callback->($link)
502		792
503	Asynchronously read the symlink specified by C<$path> and pass it to	793	Asynchronously read the symlink specified by C<$path> and pass it to
504	the callback. If an error occurs, nothing or undef gets passed to the	794	the callback. If an error occurs, nothing or undef gets passed to the
505	callback.	795	callback.
506		796
507		797
		798	=item aio_realpath $pathname, $callback->($path)
		799
		800	Asynchronously make the path absolute and resolve any symlinks in
		801	C<$path>. The resulting path only consists of directories (same as
		802	L<Cwd::realpath>).
		803
		804	This request can be used to get the absolute path of the current working
		805	directory by passing it a path of F<.> (a single dot).
		806
		807
508	=item aio_rename $srcpath, $dstpath, $callback->($status)	808	=item aio_rename $srcpath, $dstpath, $callback->($status)
509		809
510	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	810	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
511	rename(2) and call the callback with the result code.	811	rename(2) and call the callback with the result code.
		812
		813	On systems that support the AIO::WD working directory abstraction
		814	natively, the case C<[$wd, "."]> as C<$srcpath> is specialcased - instead
		815	of failing, C<rename> is called on the absolute path of C<$wd>.
		816
		817
		818	=item aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
		819
		820	Basically a version of C<aio_rename> with an additional C<$flags>
		821	argument. Calling this with C<$flags=0> is the same as calling
		822	C<aio_rename>.
		823
		824	Non-zero flags are currently only supported on GNU/Linux systems that
		825	support renameat2. Other systems fail with C<ENOSYS> in this case.
		826
		827	The following constants are available (missing ones are, as usual C<0>),
		828	see renameat2(2) for details:
		829
		830	C<IO::AIO::RENAME_NOREPLACE>, C<IO::AIO::RENAME_EXCHANGE>
		831	and C<IO::AIO::RENAME_WHITEOUT>.
512		832
513		833
514	=item aio_mkdir $pathname, $mode, $callback->($status)	834	=item aio_mkdir $pathname, $mode, $callback->($status)
515		835
516	Asynchronously mkdir (create) a directory and call the callback with	836	Asynchronously mkdir (create) a directory and call the callback with
…		…
521	=item aio_rmdir $pathname, $callback->($status)	841	=item aio_rmdir $pathname, $callback->($status)
522		842
523	Asynchronously rmdir (delete) a directory and call the callback with the	843	Asynchronously rmdir (delete) a directory and call the callback with the
524	result code.	844	result code.
525		845
		846	On systems that support the AIO::WD working directory abstraction
		847	natively, the case C<[$wd, "."]> is specialcased - instead of failing,
		848	C<rmdir> is called on the absolute path of C<$wd>.
		849
526		850
527	=item aio_readdir $pathname, $callback->($entries)	851	=item aio_readdir $pathname, $callback->($entries)
528		852
529	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	853	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
530	directory (i.e. opendir + readdir + closedir). The entries will not be	854	directory (i.e. opendir + readdir + closedir). The entries will not be
531	sorted, and will B<NOT> include the C<.> and C<..> entries.	855	sorted, and will B<NOT> include the C<.> and C<..> entries.
532		856
533	The callback a single argument which is either C<undef> or an array-ref	857	The callback is passed a single argument which is either C<undef> or an
534	with the filenames.	858	array-ref with the filenames.
535		859
536		860
		861	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		862
		863	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		864	tune behaviour and output format. In case of an error, C<$entries> will be
		865	C<undef>.
		866
		867	The flags are a combination of the following constants, ORed together (the
		868	flags will also be passed to the callback, possibly modified):
		869
		870	=over 4
		871
		872	=item IO::AIO::READDIR_DENTS
		873
		874	When this flag is off, then the callback gets an arrayref consisting of
		875	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		876	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		877	entry in more detail.
		878
		879	C<$name> is the name of the entry.
		880
		881	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		882
		883	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		884	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		885	C<IO::AIO::DT_WHT>.
		886
		887	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		888	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		889	scalars are read-only: you can not modify them.
		890
		891	C<$inode> is the inode number (which might not be exact on systems with 64
		892	bit inode numbers and 32 bit perls). This field has unspecified content on
		893	systems that do not deliver the inode information.
		894
		895	=item IO::AIO::READDIR_DIRS_FIRST
		896
		897	When this flag is set, then the names will be returned in an order where
		898	likely directories come first, in optimal stat order. This is useful when
		899	you need to quickly find directories, or you want to find all directories
		900	while avoiding to stat() each entry.
		901
		902	If the system returns type information in readdir, then this is used
		903	to find directories directly. Otherwise, likely directories are names
		904	beginning with ".", or otherwise names with no dots, of which names with
		905	short names are tried first.
		906
		907	=item IO::AIO::READDIR_STAT_ORDER
		908
		909	When this flag is set, then the names will be returned in an order
		910	suitable for stat()'ing each one. That is, when you plan to stat()
		911	all files in the given directory, then the returned order will likely
		912	be fastest.
		913
		914	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		915	the likely dirs come first, resulting in a less optimal stat order.
		916
		917	=item IO::AIO::READDIR_FOUND_UNKNOWN
		918
		919	This flag should not be set when calling C<aio_readdirx>. Instead, it
		920	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		921	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		922	C<$type>'s are known, which can be used to speed up some algorithms.
		923
		924	=back
		925
		926
537	=item aio_load $path, $data, $callback->($status)	927	=item aio_load $pathname, $data, $callback->($status)
538		928
539	This is a composite request that tries to fully load the given file into	929	This is a composite request that tries to fully load the given file into
540	memory. Status is the same as with aio_read.	930	memory. Status is the same as with aio_read.
541		931
542	=cut	932	=cut
…		…
564		954
565	=item aio_copy $srcpath, $dstpath, $callback->($status)	955	=item aio_copy $srcpath, $dstpath, $callback->($status)
566		956
567	Try to copy the I<file> (directories not supported as either source or	957	Try to copy the I<file> (directories not supported as either source or
568	destination) from C<$srcpath> to C<$dstpath> and call the callback with	958	destination) from C<$srcpath> to C<$dstpath> and call the callback with
569	the C<0> (error) or C<-1> ok.	959	a status of C<0> (ok) or C<-1> (error, see C<$!>).
570		960
571	This is a composite request that it creates the destination file with	961	This is a composite request that creates the destination file with
572	mode 0200 and copies the contents of the source file into it using	962	mode 0200 and copies the contents of the source file into it using
573	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	963	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
574	uid/gid, in that order.	964	uid/gid, in that order.
575		965
576	If an error occurs, the partial destination file will be unlinked, if	966	If an error occurs, the partial destination file will be unlinked, if
…		…
586	my $grp = aio_group $cb;	976	my $grp = aio_group $cb;
587		977
588	aioreq_pri $pri;	978	aioreq_pri $pri;
589	add $grp aio_open $src, O_RDONLY, 0, sub {	979	add $grp aio_open $src, O_RDONLY, 0, sub {
590	if (my $src_fh = $_[0]) {	980	if (my $src_fh = $_[0]) {
591	my @stat = stat $src_fh;	981	my @stat = stat $src_fh; # hmm, might block over nfs?
592		982
593	aioreq_pri $pri;	983	aioreq_pri $pri;
594	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	984	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
595	if (my $dst_fh = $_[0]) {	985	if (my $dst_fh = $_[0]) {
596	aioreq_pri $pri;	986	aioreq_pri $pri;
597	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	987	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
598	if ($_[0] == $stat[7]) {	988	if ($_[0] == $stat[7]) {
599	$grp->result (0);	989	$grp->result (0);
600	close $src_fh;	990	close $src_fh;
601		991
602	# those should not normally block. should. should.	992	my $ch = sub {
603	utime $stat[8], $stat[9], $dst;	993	aioreq_pri $pri;
604	chmod $stat[2] & 07777, $dst_fh;	994	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
605	chown $stat[4], $stat[5], $dst_fh;	995	aioreq_pri $pri;
		996	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		997	aioreq_pri $pri;
		998	add $grp aio_close $dst_fh;
		999	}
		1000	};
		1001	};
606		1002
607	aioreq_pri $pri;	1003	aioreq_pri $pri;
608	add $grp aio_close $dst_fh;	1004	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		1005	if ($_[0] < 0 && $! == ENOSYS) {
		1006	aioreq_pri $pri;
		1007	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		1008	} else {
		1009	$ch->();
		1010	}
		1011	};
609	} else {	1012	} else {
610	$grp->result (-1);	1013	$grp->result (-1);
611	close $src_fh;	1014	close $src_fh;
612	close $dst_fh;	1015	close $dst_fh;
613		1016
…		…
630		1033
631	=item aio_move $srcpath, $dstpath, $callback->($status)	1034	=item aio_move $srcpath, $dstpath, $callback->($status)
632		1035
633	Try to move the I<file> (directories not supported as either source or	1036	Try to move the I<file> (directories not supported as either source or
634	destination) from C<$srcpath> to C<$dstpath> and call the callback with	1037	destination) from C<$srcpath> to C<$dstpath> and call the callback with
635	the C<0> (error) or C<-1> ok.	1038	a status of C<0> (ok) or C<-1> (error, see C<$!>).
636		1039
637	This is a composite request that tries to rename(2) the file first. If	1040	This is a composite request that tries to rename(2) the file first; if
638	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	1041	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
639	that is successful, unlinking the C<$srcpath>.	1042	that is successful, unlinks the C<$srcpath>.
640		1043
641	=cut	1044	=cut
642		1045
643	sub aio_move($$;$) {	1046	sub aio_move($$;$) {
644	my ($src, $dst, $cb) = @_;	1047	my ($src, $dst, $cb) = @_;
…		…
651	if ($_[0] && $! == EXDEV) {	1054	if ($_[0] && $! == EXDEV) {
652	aioreq_pri $pri;	1055	aioreq_pri $pri;
653	add $grp aio_copy $src, $dst, sub {	1056	add $grp aio_copy $src, $dst, sub {
654	$grp->result ($_[0]);	1057	$grp->result ($_[0]);
655		1058
656	if (!$_[0]) {	1059	unless ($_[0]) {
657	aioreq_pri $pri;	1060	aioreq_pri $pri;
658	add $grp aio_unlink $src;	1061	add $grp aio_unlink $src;
659	}	1062	}
660	};	1063	};
661	} else {	1064	} else {
…		…
664	};	1067	};
665		1068
666	$grp	1069	$grp
667	}	1070	}
668		1071
669	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	1072	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
670		1073
671	Scans a directory (similar to C<aio_readdir>) but additionally tries to	1074	Scans a directory (similar to C<aio_readdir>) but additionally tries to
672	efficiently separate the entries of directory C<$path> into two sets of	1075	efficiently separate the entries of directory C<$path> into two sets of
673	names, directories you can recurse into (directories), and ones you cannot	1076	names, directories you can recurse into (directories), and ones you cannot
674	recurse into (everything else, including symlinks to directories).	1077	recurse into (everything else, including symlinks to directories).
…		…
691		1094
692	Implementation notes.	1095	Implementation notes.
693		1096
694	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	1097	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
695		1098
		1099	If readdir returns file type information, then this is used directly to
		1100	find directories.
		1101
696	After reading the directory, the modification time, size etc. of the	1102	Otherwise, after reading the directory, the modification time, size etc.
697	directory before and after the readdir is checked, and if they match (and	1103	of the directory before and after the readdir is checked, and if they
698	isn't the current time), the link count will be used to decide how many	1104	match (and isn't the current time), the link count will be used to decide
699	entries are directories (if >= 2). Otherwise, no knowledge of the number	1105	how many entries are directories (if >= 2). Otherwise, no knowledge of the
700	of subdirectories will be assumed.	1106	number of subdirectories will be assumed.
701		1107
702	Then entries will be sorted into likely directories (everything without	1108	Then entries will be sorted into likely directories a non-initial dot
703	a non-initial dot currently) and likely non-directories (everything	1109	currently) and likely non-directories (see C<aio_readdirx>). Then every
704	else). Then every entry plus an appended C</.> will be C<stat>'ed,	1110	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
705	likely directories first. If that succeeds, it assumes that the entry	1111	in order of their inode numbers. If that succeeds, it assumes that the
706	is a directory or a symlink to directory (which will be checked	1112	entry is a directory or a symlink to directory (which will be checked
707	seperately). This is often faster than stat'ing the entry itself because	1113	separately). This is often faster than stat'ing the entry itself because
708	filesystems might detect the type of the entry without reading the inode	1114	filesystems might detect the type of the entry without reading the inode
709	data (e.g. ext2fs filetype feature).	1115	data (e.g. ext2fs filetype feature), even on systems that cannot return
		1116	the filetype information on readdir.
710		1117
711	If the known number of directories (link count - 2) has been reached, the	1118	If the known number of directories (link count - 2) has been reached, the
712	rest of the entries is assumed to be non-directories.	1119	rest of the entries is assumed to be non-directories.
713		1120
714	This only works with certainty on POSIX (= UNIX) filesystems, which	1121	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
727		1134
728	my $grp = aio_group $cb;	1135	my $grp = aio_group $cb;
729		1136
730	$maxreq = 4 if $maxreq <= 0;	1137	$maxreq = 4 if $maxreq <= 0;
731		1138
732	# stat once	1139	# get a wd object
733	aioreq_pri $pri;	1140	aioreq_pri $pri;
734	add $grp aio_stat $path, sub {	1141	add $grp aio_wd $path, sub {
		1142	$_[0]
735	return $grp->result () if $_[0];	1143	or return $grp->result ();
736	my $now = time;
737	my $hash1 = join ":", (stat _)[0,1,3,7,9];
738		1144
739	# read the directory entries	1145	my $wd = [shift, "."];
		1146
		1147	# stat once
740	aioreq_pri $pri;	1148	aioreq_pri $pri;
741	add $grp aio_readdir $path, sub {	1149	add $grp aio_stat $wd, sub {
742	my $entries = shift
743	or return $grp->result ();	1150	return $grp->result () if $_[0];
		1151	my $now = time;
		1152	my $hash1 = join ":", (stat _)[0,1,3,7,9];
744		1153
745	# stat the dir another time	1154	# read the directory entries
746	aioreq_pri $pri;	1155	aioreq_pri $pri;
		1156	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1157	my $entries = shift
		1158	or return $grp->result ();
		1159
		1160	# stat the dir another time
		1161	aioreq_pri $pri;
747	add $grp aio_stat $path, sub {	1162	add $grp aio_stat $wd, sub {
748	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1163	my $hash2 = join ":", (stat _)[0,1,3,7,9];
749		1164
750	my $ndirs;	1165	my $ndirs;
751		1166
752	# take the slow route if anything looks fishy	1167	# take the slow route if anything looks fishy
753	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1168	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
754	$ndirs = -1;	1169	$ndirs = -1;
755	} else {	1170	} else {
756	# if nlink == 2, we are finished	1171	# if nlink == 2, we are finished
757	# on non-posix-fs's, we rely on nlink < 2	1172	# for non-posix-fs's, we rely on nlink < 2
758	$ndirs = (stat _)[3] - 2	1173	$ndirs = (stat _)[3] - 2
759	or return $grp->result ([], $entries);	1174	or return $grp->result ([], $entries);
760	}	1175	}
761		1176
762	# sort into likely dirs and likely nondirs
763	# dirs == files without ".", short entries first
764	$entries = [map $_->[0],
765	sort { $b->[1] cmp $a->[1] }
766	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
767	@$entries];
768
769	my (@dirs, @nondirs);	1177	my (@dirs, @nondirs);
770		1178
771	my $statgrp = add $grp aio_group sub {	1179	my $statgrp = add $grp aio_group sub {
772	$grp->result (\@dirs, \@nondirs);	1180	$grp->result (\@dirs, \@nondirs);
773	};	1181	};
774		1182
775	limit $statgrp $maxreq;	1183	limit $statgrp $maxreq;
776	feed $statgrp sub {	1184	feed $statgrp sub {
777	return unless @$entries;	1185	return unless @$entries;
778	my $entry = pop @$entries;	1186	my $entry = shift @$entries;
779		1187
780	aioreq_pri $pri;	1188	aioreq_pri $pri;
		1189	$wd->[1] = "$entry/.";
781	add $statgrp aio_stat "$path/$entry/.", sub {	1190	add $statgrp aio_stat $wd, sub {
782	if ($_[0] < 0) {	1191	if ($_[0] < 0) {
783	push @nondirs, $entry;	1192	push @nondirs, $entry;
784	} else {	1193	} else {
785	# need to check for real directory	1194	# need to check for real directory
786	aioreq_pri $pri;	1195	aioreq_pri $pri;
		1196	$wd->[1] = $entry;
787	add $statgrp aio_lstat "$path/$entry", sub {	1197	add $statgrp aio_lstat $wd, sub {
788	if (-d _) {	1198	if (-d _) {
789	push @dirs, $entry;	1199	push @dirs, $entry;
790		1200
791	unless (--$ndirs) {	1201	unless (--$ndirs) {
792	push @nondirs, @$entries;	1202	push @nondirs, @$entries;
793	feed $statgrp;	1203	feed $statgrp;
		1204	}
		1205	} else {
		1206	push @nondirs, $entry;
794	}	1207	}
795	} else {
796	push @nondirs, $entry;
797	}	1208	}
798	}	1209	}
799	}	1210	};
800	};	1211	};
801	};	1212	};
802	};	1213	};
803	};	1214	};
804	};	1215	};
805		1216
806	$grp	1217	$grp
807	}	1218	}
808		1219
809	=item aio_rmtree $path, $callback->($status)	1220	=item aio_rmtree $pathname, $callback->($status)
810		1221
811	Delete a directory tree starting (and including) C<$path>, return the	1222	Delete a directory tree starting (and including) C<$path>, return the
812	status of the final C<rmdir> only. This is a composite request that	1223	status of the final C<rmdir> only. This is a composite request that
813	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1224	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
814	everything else.	1225	everything else.
815		1226
816	=cut	1227	=cut
817		1228
…		…
839	};	1250	};
840		1251
841	$grp	1252	$grp
842	}	1253	}
843		1254
		1255	=item aio_fcntl $fh, $cmd, $arg, $callback->($status)
		1256
		1257	=item aio_ioctl $fh, $request, $buf, $callback->($status)
		1258
		1259	These work just like the C<fcntl> and C<ioctl> built-in functions, except
		1260	they execute asynchronously and pass the return value to the callback.
		1261
		1262	Both calls can be used for a lot of things, some of which make more sense
		1263	to run asynchronously in their own thread, while some others make less
		1264	sense. For example, calls that block waiting for external events, such
		1265	as locking, will also lock down an I/O thread while it is waiting, which
		1266	can deadlock the whole I/O system. At the same time, there might be no
		1267	alternative to using a thread to wait.
		1268
		1269	So in general, you should only use these calls for things that do
		1270	(filesystem) I/O, not for things that wait for other events (network,
		1271	other processes), although if you are careful and know what you are doing,
		1272	you still can.
		1273
		1274	The following constants are available (missing ones are, as usual C<0>):
		1275
		1276	C<F_DUPFD_CLOEXEC>,
		1277
		1278	C<F_OFD_GETLK>, C<F_OFD_SETLK>, C<F_OFD_GETLKW>,
		1279
		1280	C<FIFREEZE>, C<FITHAW>, C<FITRIM>, C<FICLONE>, C<FICLONERANGE>, C<FIDEDUPERANGE>.
		1281
		1282	C<FS_IOC_GETFLAGS>, C<FS_IOC_SETFLAGS>, C<FS_IOC_GETVERSION>, C<FS_IOC_SETVERSION>,
		1283	C<FS_IOC_FIEMAP>.
		1284
		1285	C<FS_IOC_FSGETXATTR>, C<FS_IOC_FSSETXATTR>, C<FS_IOC_SET_ENCRYPTION_POLICY>,
		1286	C<FS_IOC_GET_ENCRYPTION_PWSALT>, C<FS_IOC_GET_ENCRYPTION_POLICY>, C<FS_KEY_DESCRIPTOR_SIZE>.
		1287
		1288	C<FS_SECRM_FL>, C<FS_UNRM_FL>, C<FS_COMPR_FL>, C<FS_SYNC_FL>, C<FS_IMMUTABLE_FL>,
		1289	C<FS_APPEND_FL>, C<FS_NODUMP_FL>, C<FS_NOATIME_FL>, C<FS_DIRTY_FL>,
		1290	C<FS_COMPRBLK_FL>, C<FS_NOCOMP_FL>, C<FS_ENCRYPT_FL>, C<FS_BTREE_FL>,
		1291	C<FS_INDEX_FL>, C<FS_JOURNAL_DATA_FL>, C<FS_NOTAIL_FL>, C<FS_DIRSYNC_FL>, C<FS_TOPDIR_FL>,
		1292	C<FS_FL_USER_MODIFIABLE>.
		1293
		1294	C<FS_XFLAG_REALTIME>, C<FS_XFLAG_PREALLOC>, C<FS_XFLAG_IMMUTABLE>, C<FS_XFLAG_APPEND>,
		1295	C<FS_XFLAG_SYNC>, C<FS_XFLAG_NOATIME>, C<FS_XFLAG_NODUMP>, C<FS_XFLAG_RTINHERIT>,
		1296	C<FS_XFLAG_PROJINHERIT>, C<FS_XFLAG_NOSYMLINKS>, C<FS_XFLAG_EXTSIZE>, C<FS_XFLAG_EXTSZINHERIT>,
		1297	C<FS_XFLAG_NODEFRAG>, C<FS_XFLAG_FILESTREAM>, C<FS_XFLAG_DAX>, C<FS_XFLAG_HASATTR>,
		1298
844	=item aio_sync $callback->($status)	1299	=item aio_sync $callback->($status)
845		1300
846	Asynchronously call sync and call the callback when finished.	1301	Asynchronously call sync and call the callback when finished.
847		1302
848	=item aio_fsync $fh, $callback->($status)	1303	=item aio_fsync $fh, $callback->($status)
…		…
856	callback with the fdatasync result code.	1311	callback with the fdatasync result code.
857		1312
858	If this call isn't available because your OS lacks it or it couldn't be	1313	If this call isn't available because your OS lacks it or it couldn't be
859	detected, it will be emulated by calling C<fsync> instead.	1314	detected, it will be emulated by calling C<fsync> instead.
860		1315
		1316	=item aio_syncfs $fh, $callback->($status)
		1317
		1318	Asynchronously call the syncfs syscall to sync the filesystem associated
		1319	to the given filehandle and call the callback with the syncfs result
		1320	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1321	errno to C<ENOSYS> nevertheless.
		1322
		1323	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1324
		1325	Sync the data portion of the file specified by C<$offset> and C<$length>
		1326	to disk (but NOT the metadata), by calling the Linux-specific
		1327	sync_file_range call. If sync_file_range is not available or it returns
		1328	ENOSYS, then fdatasync or fsync is being substituted.
		1329
		1330	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1331	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1332	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1333	manpage for details.
		1334
861	=item aio_pathsync $path, $callback->($status)	1335	=item aio_pathsync $pathname, $callback->($status)
862		1336
863	This request tries to open, fsync and close the given path. This is a	1337	This request tries to open, fsync and close the given path. This is a
864	composite request intended tosync directories after directory operations	1338	composite request intended to sync directories after directory operations
865	(E.g. rename). This might not work on all operating systems or have any	1339	(E.g. rename). This might not work on all operating systems or have any
866	specific effect, but usually it makes sure that directory changes get	1340	specific effect, but usually it makes sure that directory changes get
867	written to disc. It works for anything that can be opened for read-only,	1341	written to disc. It works for anything that can be opened for read-only,
868	not just directories.	1342	not just directories.
		1343
		1344	Future versions of this function might fall back to other methods when
		1345	C<fsync> on the directory fails (such as calling C<sync>).
869		1346
870	Passes C<0> when everything went ok, and C<-1> on error.	1347	Passes C<0> when everything went ok, and C<-1> on error.
871		1348
872	=cut	1349	=cut
873		1350
…		…
894	};	1371	};
895		1372
896	$grp	1373	$grp
897	}	1374	}
898		1375
		1376	=item aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
		1377
		1378	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1379	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1380	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1381	scalar must only be modified in-place while an aio operation is pending on
		1382	it).
		1383
		1384	It calls the C<msync> function of your OS, if available, with the memory
		1385	area starting at C<$offset> in the string and ending C<$length> bytes
		1386	later. If C<$length> is negative, counts from the end, and if C<$length>
		1387	is C<undef>, then it goes till the end of the string. The flags can be
		1388	either C<IO::AIO::MS_ASYNC> or C<IO::AIO::MS_SYNC>, plus an optional
		1389	C<IO::AIO::MS_INVALIDATE>.
		1390
		1391	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1392
		1393	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1394	scalars.
		1395
		1396	It touches (reads or writes) all memory pages in the specified
		1397	range inside the scalar. All caveats and parameters are the same
		1398	as for C<aio_msync>, above, except for flags, which must be either
		1399	C<0> (which reads all pages and ensures they are instantiated) or
		1400	C<IO::AIO::MT_MODIFY>, which modifies the memory pages (by reading and
		1401	writing an octet from it, which dirties the page).
		1402
		1403	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1404
		1405	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1406	scalars.
		1407
		1408	It reads in all the pages of the underlying storage into memory (if any)
		1409	and locks them, so they are not getting swapped/paged out or removed.
		1410
		1411	If C<$length> is undefined, then the scalar will be locked till the end.
		1412
		1413	On systems that do not implement C<mlock>, this function returns C<-1>
		1414	and sets errno to C<ENOSYS>.
		1415
		1416	Note that the corresponding C<munlock> is synchronous and is
		1417	documented under L<MISCELLANEOUS FUNCTIONS>.
		1418
		1419	Example: open a file, mmap and mlock it - both will be undone when
		1420	C<$data> gets destroyed.
		1421
		1422	open my $fh, "<", $path or die "$path: $!";
		1423	my $data;
		1424	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1425	aio_mlock $data; # mlock in background
		1426
		1427	=item aio_mlockall $flags, $callback->($status)
		1428
		1429	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1430	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1431
		1432	On systems that do not implement C<mlockall>, this function returns C<-1>
		1433	and sets errno to C<ENOSYS>.
		1434
		1435	Note that the corresponding C<munlockall> is synchronous and is
		1436	documented under L<MISCELLANEOUS FUNCTIONS>.
		1437
		1438	Example: asynchronously lock all current and future pages into memory.
		1439
		1440	aio_mlockall IO::AIO::MCL_FUTURE;
		1441
		1442	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1443
		1444	Queries the extents of the given file (by calling the Linux C<FIEMAP>
		1445	ioctl, see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If
		1446	the ioctl is not available on your OS, then this request will fail with
		1447	C<ENOSYS>.
		1448
		1449	C<$start> is the starting offset to query extents for, C<$length> is the
		1450	size of the range to query - if it is C<undef>, then the whole file will
		1451	be queried.
		1452
		1453	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1454	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1455	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1456	the data portion.
		1457
		1458	C<$count> is the maximum number of extent records to return. If it is
		1459	C<undef>, then IO::AIO queries all extents of the range. As a very special
		1460	case, if it is C<0>, then the callback receives the number of extents
		1461	instead of the extents themselves (which is unreliable, see below).
		1462
		1463	If an error occurs, the callback receives no arguments. The special
		1464	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1465
		1466	Otherwise, the callback receives an array reference with extent
		1467	structures. Each extent structure is an array reference itself, with the
		1468	following members:
		1469
		1470	[$logical, $physical, $length, $flags]
		1471
		1472	Flags is any combination of the following flag values (typically either C<0>
		1473	or C<IO::AIO::FIEMAP_EXTENT_LAST> (1)):
		1474
		1475	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1476	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1477	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1478	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1479	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1480	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1481
		1482	At the time of this writing (Linux 3.2), this requets is unreliable unless
		1483	C<$count> is C<undef>, as the kernel has all sorts of bugs preventing
		1484	it to return all extents of a range for files with large number of
		1485	extents. The code works around all these issues if C<$count> is undef.
		1486
899	=item aio_group $callback->(...)	1487	=item aio_group $callback->(...)
900		1488
901	This is a very special aio request: Instead of doing something, it is a	1489	This is a very special aio request: Instead of doing something, it is a
902	container for other aio requests, which is useful if you want to bundle	1490	container for other aio requests, which is useful if you want to bundle
903	many requests into a single, composite, request with a definite callback	1491	many requests into a single, composite, request with a definite callback
…		…
940	immense (it blocks a thread for a long time) so do not use this function	1528	immense (it blocks a thread for a long time) so do not use this function
941	except to put your application under artificial I/O pressure.	1529	except to put your application under artificial I/O pressure.
942		1530
943	=back	1531	=back
944		1532
		1533
		1534	=head2 IO::AIO::WD - multiple working directories
		1535
		1536	Your process only has one current working directory, which is used by all
		1537	threads. This makes it hard to use relative paths (some other component
		1538	could call C<chdir> at any time, and it is hard to control when the path
		1539	will be used by IO::AIO).
		1540
		1541	One solution for this is to always use absolute paths. This usually works,
		1542	but can be quite slow (the kernel has to walk the whole path on every
		1543	access), and can also be a hassle to implement.
		1544
		1545	Newer POSIX systems have a number of functions (openat, fdopendir,
		1546	futimensat and so on) that make it possible to specify working directories
		1547	per operation.
		1548
		1549	For portability, and because the clowns who "designed", or shall I write,
		1550	perpetrated this new interface were obviously half-drunk, this abstraction
		1551	cannot be perfect, though.
		1552
		1553	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1554	object. This object stores the canonicalised, absolute version of the
		1555	path, and on systems that allow it, also a directory file descriptor.
		1556
		1557	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1558	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1559	object and a pathname instead (or the IO::AIO::WD object alone, which
		1560	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1561	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1562	to that IO::AIO::WD object.
		1563
		1564	For example, to get a wd object for F</etc> and then stat F<passwd>
		1565	inside, you would write:
		1566
		1567	aio_wd "/etc", sub {
		1568	my $etcdir = shift;
		1569
		1570	# although $etcdir can be undef on error, there is generally no reason
		1571	# to check for errors here, as aio_stat will fail with ENOENT
		1572	# when $etcdir is undef.
		1573
		1574	aio_stat [$etcdir, "passwd"], sub {
		1575	# yay
		1576	};
		1577	};
		1578
		1579	The fact that C<aio_wd> is a request and not a normal function shows that
		1580	creating an IO::AIO::WD object is itself a potentially blocking operation,
		1581	which is why it is done asynchronously.
		1582
		1583	To stat the directory obtained with C<aio_wd> above, one could write
		1584	either of the following three request calls:
		1585
		1586	aio_lstat "/etc" , sub { ... # pathname as normal string
		1587	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1588	aio_lstat $wd , sub { ... # shorthand for the previous
		1589
		1590	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1591	object and the pathname string, so you could write the following without
		1592	causing any issues due to C<$path> getting reused:
		1593
		1594	my $path = [$wd, undef];
		1595
		1596	for my $name (qw(abc def ghi)) {
		1597	$path->[1] = $name;
		1598	aio_stat $path, sub {
		1599	# ...
		1600	};
		1601	}
		1602
		1603	There are some caveats: when directories get renamed (or deleted), the
		1604	pathname string doesn't change, so will point to the new directory (or
		1605	nowhere at all), while the directory fd, if available on the system,
		1606	will still point to the original directory. Most functions accepting a
		1607	pathname will use the directory fd on newer systems, and the string on
		1608	older systems. Some functions (such as realpath) will always rely on the
		1609	string form of the pathname.
		1610
		1611	So this functionality is mainly useful to get some protection against
		1612	C<chdir>, to easily get an absolute path out of a relative path for future
		1613	reference, and to speed up doing many operations in the same directory
		1614	(e.g. when stat'ing all files in a directory).
		1615
		1616	The following functions implement this working directory abstraction:
		1617
		1618	=over 4
		1619
		1620	=item aio_wd $pathname, $callback->($wd)
		1621
		1622	Asynchonously canonicalise the given pathname and convert it to an
		1623	IO::AIO::WD object representing it. If possible and supported on the
		1624	system, also open a directory fd to speed up pathname resolution relative
		1625	to this working directory.
		1626
		1627	If something goes wrong, then C<undef> is passwd to the callback instead
		1628	of a working directory object and C<$!> is set appropriately. Since
		1629	passing C<undef> as working directory component of a pathname fails the
		1630	request with C<ENOENT>, there is often no need for error checking in the
		1631	C<aio_wd> callback, as future requests using the value will fail in the
		1632	expected way.
		1633
		1634	=item IO::AIO::CWD
		1635
		1636	This is a compiletime constant (object) that represents the process
		1637	current working directory.
		1638
		1639	Specifying this object as working directory object for a pathname is as if
		1640	the pathname would be specified directly, without a directory object. For
		1641	example, these calls are functionally identical:
		1642
		1643	aio_stat "somefile", sub { ... };
		1644	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1645
		1646	=back
		1647
		1648	To recover the path associated with an IO::AIO::WD object, you can use
		1649	C<aio_realpath>:
		1650
		1651	aio_realpath $wd, sub {
		1652	warn "path is $_[0]\n";
		1653	};
		1654
		1655	Currently, C<aio_statvfs> always, and C<aio_rename> and C<aio_rmdir>
		1656	sometimes, fall back to using an absolue path.
		1657
945	=head2 IO::AIO::REQ CLASS	1658	=head2 IO::AIO::REQ CLASS
946		1659
947	All non-aggregate C<aio_*> functions return an object of this class when	1660	All non-aggregate C<aio_*> functions return an object of this class when
948	called in non-void context.	1661	called in non-void context.
949		1662
…		…
952	=item cancel $req	1665	=item cancel $req
953		1666
954	Cancels the request, if possible. Has the effect of skipping execution	1667	Cancels the request, if possible. Has the effect of skipping execution
955	when entering the B<execute> state and skipping calling the callback when	1668	when entering the B<execute> state and skipping calling the callback when
956	entering the the B<result> state, but will leave the request otherwise	1669	entering the the B<result> state, but will leave the request otherwise
957	untouched. That means that requests that currently execute will not be	1670	untouched (with the exception of readdir). That means that requests that
958	stopped and resources held by the request will not be freed prematurely.	1671	currently execute will not be stopped and resources held by the request
		1672	will not be freed prematurely.
959		1673
960	=item cb $req $callback->(...)	1674	=item cb $req $callback->(...)
961		1675
962	Replace (or simply set) the callback registered to the request.	1676	Replace (or simply set) the callback registered to the request.
963		1677
…		…
1014	Their lifetime, simplified, looks like this: when they are empty, they	1728	Their lifetime, simplified, looks like this: when they are empty, they
1015	will finish very quickly. If they contain only requests that are in the	1729	will finish very quickly. If they contain only requests that are in the
1016	C<done> state, they will also finish. Otherwise they will continue to	1730	C<done> state, they will also finish. Otherwise they will continue to
1017	exist.	1731	exist.
1018		1732
1019	That means after creating a group you have some time to add requests. And	1733	That means after creating a group you have some time to add requests
1020	in the callbacks of those requests, you can add further requests to the	1734	(precisely before the callback has been invoked, which is only done within
1021	group. And only when all those requests have finished will the the group	1735	the C<poll_cb>). And in the callbacks of those requests, you can add
1022	itself finish.	1736	further requests to the group. And only when all those requests have
		1737	finished will the the group itself finish.
1023		1738
1024	=over 4	1739	=over 4
1025		1740
1026	=item add $grp ...	1741	=item add $grp ...
1027		1742
…		…
1035		1750
1036	=item $grp->cancel_subs	1751	=item $grp->cancel_subs
1037		1752
1038	Cancel all subrequests and clears any feeder, but not the group request	1753	Cancel all subrequests and clears any feeder, but not the group request
1039	itself. Useful when you queued a lot of events but got a result early.	1754	itself. Useful when you queued a lot of events but got a result early.
		1755
		1756	The group request will finish normally (you cannot add requests to the
		1757	group).
1040		1758
1041	=item $grp->result (...)	1759	=item $grp->result (...)
1042		1760
1043	Set the result value(s) that will be passed to the group callback when all	1761	Set the result value(s) that will be passed to the group callback when all
1044	subrequests have finished and set the groups errno to the current value	1762	subrequests have finished and set the groups errno to the current value
…		…
1060	=item feed $grp $callback->($grp)	1778	=item feed $grp $callback->($grp)
1061		1779
1062	Sets a feeder/generator on this group: every group can have an attached	1780	Sets a feeder/generator on this group: every group can have an attached
1063	generator that generates requests if idle. The idea behind this is that,	1781	generator that generates requests if idle. The idea behind this is that,
1064	although you could just queue as many requests as you want in a group,	1782	although you could just queue as many requests as you want in a group,
1065	this might starve other requests for a potentially long time. For	1783	this might starve other requests for a potentially long time. For example,
1066	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1784	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1067	requests, delaying any later requests for a long time.	1785	requests, delaying any later requests for a long time.
1068		1786
1069	To avoid this, and allow incremental generation of requests, you can	1787	To avoid this, and allow incremental generation of requests, you can
1070	instead a group and set a feeder on it that generates those requests. The	1788	instead a group and set a feeder on it that generates those requests. The
1071	feed callback will be called whenever there are few enough (see C<limit>,	1789	feed callback will be called whenever there are few enough (see C<limit>,
…		…
1076	not impose any limits).	1794	not impose any limits).
1077		1795
1078	If the feed does not queue more requests when called, it will be	1796	If the feed does not queue more requests when called, it will be
1079	automatically removed from the group.	1797	automatically removed from the group.
1080		1798
1081	If the feed limit is C<0>, it will be set to C<2> automatically.	1799	If the feed limit is C<0> when this method is called, it will be set to
		1800	C<2> automatically.
1082		1801
1083	Example:	1802	Example:
1084		1803
1085	# stat all files in @files, but only ever use four aio requests concurrently:	1804	# stat all files in @files, but only ever use four aio requests concurrently:
1086		1805
…		…
1098	Sets the feeder limit for the group: The feeder will be called whenever	1817	Sets the feeder limit for the group: The feeder will be called whenever
1099	the group contains less than this many requests.	1818	the group contains less than this many requests.
1100		1819
1101	Setting the limit to C<0> will pause the feeding process.	1820	Setting the limit to C<0> will pause the feeding process.
1102		1821
		1822	The default value for the limit is C<0>, but note that setting a feeder
		1823	automatically bumps it up to C<2>.
		1824
1103	=back	1825	=back
1104		1826
1105	=head2 SUPPORT FUNCTIONS	1827	=head2 SUPPORT FUNCTIONS
1106		1828
1107	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1829	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
…		…
1109	=over 4	1831	=over 4
1110		1832
1111	=item $fileno = IO::AIO::poll_fileno	1833	=item $fileno = IO::AIO::poll_fileno
1112		1834
1113	Return the I<request result pipe file descriptor>. This filehandle must be	1835	Return the I<request result pipe file descriptor>. This filehandle must be
1114	polled for reading by some mechanism outside this module (e.g. Event or	1836	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1115	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1837	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1116	to call C<poll_cb> to check the results.	1838	you have to call C<poll_cb> to check the results.
1117		1839
1118	See C<poll_cb> for an example.	1840	See C<poll_cb> for an example.
1119		1841
1120	=item IO::AIO::poll_cb	1842	=item IO::AIO::poll_cb
1121		1843
1122	Process some outstanding events on the result pipe. You have to call this	1844	Process some requests that have reached the result phase (i.e. they have
1123	regularly. Returns the number of events processed. Returns immediately	1845	been executed but the results are not yet reported). You have to call
1124	when no events are outstanding. The amount of events processed depends on	1846	this "regularly" to finish outstanding requests.
1125	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
1126		1847
		1848	Returns C<0> if all events could be processed (or there were no
		1849	events to process), or C<-1> if it returned earlier for whatever
		1850	reason. Returns immediately when no events are outstanding. The amount
		1851	of events processed depends on the settings of C<IO::AIO::max_poll_req>,
		1852	C<IO::AIO::max_poll_time> and C<IO::AIO::max_outstanding>.
		1853
1127	If not all requests were processed for whatever reason, the filehandle	1854	If not all requests were processed for whatever reason, the poll file
1128	will still be ready when C<poll_cb> returns.	1855	descriptor will still be ready when C<poll_cb> returns, so normally you
		1856	don't have to do anything special to have it called later.
		1857
		1858	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1859	ready, it can be beneficial to call this function from loops which submit
		1860	a lot of requests, to make sure the results get processed when they become
		1861	available and not just when the loop is finished and the event loop takes
		1862	over again. This function returns very fast when there are no outstanding
		1863	requests.
1129		1864
1130	Example: Install an Event watcher that automatically calls	1865	Example: Install an Event watcher that automatically calls
1131	IO::AIO::poll_cb with high priority:	1866	IO::AIO::poll_cb with high priority (more examples can be found in the
		1867	SYNOPSIS section, at the top of this document):
1132		1868
1133	Event->io (fd => IO::AIO::poll_fileno,	1869	Event->io (fd => IO::AIO::poll_fileno,
1134	poll => 'r', async => 1,	1870	poll => 'r', async => 1,
1135	cb => \&IO::AIO::poll_cb);	1871	cb => \&IO::AIO::poll_cb);
		1872
		1873	=item IO::AIO::poll_wait
		1874
		1875	Wait until either at least one request is in the result phase or no
		1876	requests are outstanding anymore.
		1877
		1878	This is useful if you want to synchronously wait for some requests to
		1879	become ready, without actually handling them.
		1880
		1881	See C<nreqs> for an example.
		1882
		1883	=item IO::AIO::poll
		1884
		1885	Waits until some requests have been handled.
		1886
		1887	Returns the number of requests processed, but is otherwise strictly
		1888	equivalent to:
		1889
		1890	IO::AIO::poll_wait, IO::AIO::poll_cb
		1891
		1892	=item IO::AIO::flush
		1893
		1894	Wait till all outstanding AIO requests have been handled.
		1895
		1896	Strictly equivalent to:
		1897
		1898	IO::AIO::poll_wait, IO::AIO::poll_cb
		1899	while IO::AIO::nreqs;
1136		1900
1137	=item IO::AIO::max_poll_reqs $nreqs	1901	=item IO::AIO::max_poll_reqs $nreqs
1138		1902
1139	=item IO::AIO::max_poll_time $seconds	1903	=item IO::AIO::max_poll_time $seconds
1140		1904
…		…
1165	# use a low priority so other tasks have priority	1929	# use a low priority so other tasks have priority
1166	Event->io (fd => IO::AIO::poll_fileno,	1930	Event->io (fd => IO::AIO::poll_fileno,
1167	poll => 'r', nice => 1,	1931	poll => 'r', nice => 1,
1168	cb => &IO::AIO::poll_cb);	1932	cb => &IO::AIO::poll_cb);
1169		1933
1170	=item IO::AIO::poll_wait
1171
1172	If there are any outstanding requests and none of them in the result
1173	phase, wait till the result filehandle becomes ready for reading (simply
1174	does a C<select> on the filehandle. This is useful if you want to
1175	synchronously wait for some requests to finish).
1176
1177	See C<nreqs> for an example.
1178
1179	=item IO::AIO::poll
1180
1181	Waits until some requests have been handled.
1182
1183	Returns the number of requests processed, but is otherwise strictly
1184	equivalent to:
1185
1186	IO::AIO::poll_wait, IO::AIO::poll_cb
1187
1188	=item IO::AIO::flush
1189
1190	Wait till all outstanding AIO requests have been handled.
1191
1192	Strictly equivalent to:
1193
1194	IO::AIO::poll_wait, IO::AIO::poll_cb
1195	while IO::AIO::nreqs;
1196
1197	=back	1934	=back
1198		1935
1199	=head3 CONTROLLING THE NUMBER OF THREADS	1936	=head3 CONTROLLING THE NUMBER OF THREADS
1200		1937
1201	=over	1938	=over
…		…
1234		1971
1235	Under normal circumstances you don't need to call this function.	1972	Under normal circumstances you don't need to call this function.
1236		1973
1237	=item IO::AIO::max_idle $nthreads	1974	=item IO::AIO::max_idle $nthreads
1238		1975
1239	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1976	Limit the number of threads (default: 4) that are allowed to idle
1240	threads that did not get a request to process within 10 seconds). That	1977	(i.e., threads that did not get a request to process within the idle
1241	means if a thread becomes idle while C<$nthreads> other threads are also	1978	timeout (default: 10 seconds). That means if a thread becomes idle while
1242	idle, it will free its resources and exit.	1979	C<$nthreads> other threads are also idle, it will free its resources and
		1980	exit.
1243		1981
1244	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1982	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1245	to allow for extremely high load situations, but want to free resources	1983	to allow for extremely high load situations, but want to free resources
1246	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1984	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1247		1985
1248	The default is probably ok in most situations, especially if thread	1986	The default is probably ok in most situations, especially if thread
1249	creation is fast. If thread creation is very slow on your system you might	1987	creation is fast. If thread creation is very slow on your system you might
1250	want to use larger values.	1988	want to use larger values.
1251		1989
		1990	=item IO::AIO::idle_timeout $seconds
		1991
		1992	Sets the minimum idle timeout (default 10) after which worker threads are
		1993	allowed to exit. SEe C<IO::AIO::max_idle>.
		1994
1252	=item IO::AIO::max_outstanding $maxreqs	1995	=item IO::AIO::max_outstanding $maxreqs
		1996
		1997	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1998	you do queue up more than this number of requests, the next call to
		1999	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		2000	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		2001	longer exceeded.
		2002
		2003	In other words, this setting does not enforce a queue limit, but can be
		2004	used to make poll functions block if the limit is exceeded.
1253		2005
1254	This is a very bad function to use in interactive programs because it	2006	This is a very bad function to use in interactive programs because it
1255	blocks, and a bad way to reduce concurrency because it is inexact: Better	2007	blocks, and a bad way to reduce concurrency because it is inexact: Better
1256	use an C<aio_group> together with a feed callback.	2008	use an C<aio_group> together with a feed callback.
1257		2009
1258	Sets the maximum number of outstanding requests to C<$nreqs>. If you	2010	Its main use is in scripts without an event loop - when you want to stat
1259	do queue up more than this number of requests, the next call to the	2011	a lot of files, you can write somehting like this:
1260	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1261	function will block until the limit is no longer exceeded.
1262		2012
1263	The default value is very large, so there is no practical limit on the	2013	IO::AIO::max_outstanding 32;
1264	number of outstanding requests.
1265		2014
1266	You can still queue as many requests as you want. Therefore,	2015	for my $path (...) {
1267	C<max_outstanding> is mainly useful in simple scripts (with low values) or	2016	aio_stat $path , ...;
1268	as a stop gap to shield against fatal memory overflow (with large values).	2017	IO::AIO::poll_cb;
		2018	}
		2019
		2020	IO::AIO::flush;
		2021
		2022	The call to C<poll_cb> inside the loop will normally return instantly, but
		2023	as soon as more thna C<32> reqeusts are in-flight, it will block until
		2024	some requests have been handled. This keeps the loop from pushing a large
		2025	number of C<aio_stat> requests onto the queue.
		2026
		2027	The default value for C<max_outstanding> is very large, so there is no
		2028	practical limit on the number of outstanding requests.
1269		2029
1270	=back	2030	=back
1271		2031
1272	=head3 STATISTICAL INFORMATION	2032	=head3 STATISTICAL INFORMATION
1273		2033
…		…
1293	Returns the number of requests currently in the pending state (executed,	2053	Returns the number of requests currently in the pending state (executed,
1294	but not yet processed by poll_cb).	2054	but not yet processed by poll_cb).
1295		2055
1296	=back	2056	=back
1297		2057
		2058	=head3 MISCELLANEOUS FUNCTIONS
		2059
		2060	IO::AIO implements some functions that are useful when you want to use
		2061	some "Advanced I/O" function not available to in Perl, without going the
		2062	"Asynchronous I/O" route. Many of these have an asynchronous C<aio_*>
		2063	counterpart.
		2064
		2065	=over 4
		2066
		2067	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		2068
		2069	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		2070	but is blocking (this makes most sense if you know the input data is
		2071	likely cached already and the output filehandle is set to non-blocking
		2072	operations).
		2073
		2074	Returns the number of bytes copied, or C<-1> on error.
		2075
		2076	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		2077
		2078	Simply calls the C<posix_fadvise> function (see its
		2079	manpage for details). The following advice constants are
		2080	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		2081	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		2082	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		2083
		2084	On systems that do not implement C<posix_fadvise>, this function returns
		2085	ENOSYS, otherwise the return value of C<posix_fadvise>.
		2086
		2087	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		2088
		2089	Simply calls the C<posix_madvise> function (see its
		2090	manpage for details). The following advice constants are
		2091	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		2092	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>,
		2093	C<IO::AIO::MADV_FREE>.
		2094
		2095	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2096	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2097	will be reduced to fit into the C<$scalar>.
		2098
		2099	On systems that do not implement C<posix_madvise>, this function returns
		2100	ENOSYS, otherwise the return value of C<posix_madvise>.
		2101
		2102	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		2103
		2104	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		2105	$scalar (see its manpage for details). The following protect
		2106	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		2107	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		2108
		2109	If C<$offset> is negative, counts from the end. If C<$length> is negative,
		2110	the remaining length of the C<$scalar> is used. If possible, C<$length>
		2111	will be reduced to fit into the C<$scalar>.
		2112
		2113	On systems that do not implement C<mprotect>, this function returns
		2114	ENOSYS, otherwise the return value of C<mprotect>.
		2115
		2116	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		2117
		2118	Memory-maps a file (or anonymous memory range) and attaches it to the
		2119	given C<$scalar>, which will act like a string scalar. Returns true on
		2120	success, and false otherwise.
		2121
		2122	The scalar must exist, but its contents do not matter - this means you
		2123	cannot use a nonexistant array or hash element. When in doubt, C<undef>
		2124	the scalar first.
		2125
		2126	The only operations allowed on the mmapped scalar are C<substr>/C<vec>,
		2127	which don't change the string length, and most read-only operations such
		2128	as copying it or searching it with regexes and so on.
		2129
		2130	Anything else is unsafe and will, at best, result in memory leaks.
		2131
		2132	The memory map associated with the C<$scalar> is automatically removed
		2133	when the C<$scalar> is undef'd or destroyed, or when the C<IO::AIO::mmap>
		2134	or C<IO::AIO::munmap> functions are called on it.
		2135
		2136	This calls the C<mmap>(2) function internally. See your system's manual
		2137	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		2138
		2139	The C<$length> must be larger than zero and smaller than the actual
		2140	filesize.
		2141
		2142	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		2143	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		2144
		2145	C<$flags> can be a combination of
		2146	C<IO::AIO::MAP_SHARED> or
		2147	C<IO::AIO::MAP_PRIVATE>,
		2148	or a number of system-specific flags (when not available, the are C<0>):
		2149	C<IO::AIO::MAP_ANONYMOUS> (which is set to C<MAP_ANON> if your system only provides this constant),
		2150	C<IO::AIO::MAP_LOCKED>,
		2151	C<IO::AIO::MAP_NORESERVE>,
		2152	C<IO::AIO::MAP_POPULATE>,
		2153	C<IO::AIO::MAP_NONBLOCK>,
		2154	C<IO::AIO::MAP_FIXED>,
		2155	C<IO::AIO::MAP_GROWSDOWN>,
		2156	C<IO::AIO::MAP_32BIT>,
		2157	C<IO::AIO::MAP_HUGETLB> or
		2158	C<IO::AIO::MAP_STACK>.
		2159
		2160	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		2161
		2162	C<$offset> is the offset from the start of the file - it generally must be
		2163	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		2164
		2165	Example:
		2166
		2167	use Digest::MD5;
		2168	use IO::AIO;
		2169
		2170	open my $fh, "<verybigfile"
		2171	or die "$!";
		2172
		2173	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		2174	or die "verybigfile: $!";
		2175
		2176	my $fast_md5 = md5 $data;
		2177
		2178	=item IO::AIO::munmap $scalar
		2179
		2180	Removes a previous mmap and undefines the C<$scalar>.
		2181
		2182	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		2183
		2184	Calls the C<munlock> function, undoing the effects of a previous
		2185	C<aio_mlock> call (see its description for details).
		2186
		2187	=item IO::AIO::munlockall
		2188
		2189	Calls the C<munlockall> function.
		2190
		2191	On systems that do not implement C<munlockall>, this function returns
		2192	ENOSYS, otherwise the return value of C<munlockall>.
		2193
		2194	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		2195
		2196	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		2197	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		2198	should be the file offset.
		2199
		2200	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2201	silently corrupt the data in this case.
		2202
		2203	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2204	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2205	C<IO::AIO::SPLICE_F_GIFT>.
		2206
		2207	See the C<splice(2)> manpage for details.
		2208
		2209	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2210
		2211	Calls the GNU/Linux C<tee(2)> syscall, see its manpage and the
		2212	description for C<IO::AIO::splice> above for details.
		2213
		2214	=item $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		2215
		2216	Attempts to query or change the pipe buffer size. Obviously works only
		2217	on pipes, and currently works only on GNU/Linux systems, and fails with
		2218	C<-1>/C<ENOSYS> everywhere else. If anybody knows how to influence pipe buffer
		2219	size on other systems, drop me a note.
		2220
		2221	=item ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		2222
		2223	This is a direct interface to the Linux L<pipe2(2)> system call. If
		2224	C<$flags> is missing or C<0>, then this should be the same as a call to
		2225	perl's built-in C<pipe> function and create a new pipe, and works on
		2226	systems that lack the pipe2 syscall. On win32, this case invokes C<_pipe
		2227	(..., 4096, O_BINARY)>.
		2228
		2229	If C<$flags> is non-zero, it tries to invoke the pipe2 system call with
		2230	the given flags (Linux 2.6.27, glibc 2.9).
		2231
		2232	On success, the read and write file handles are returned.
		2233
		2234	On error, nothing will be returned. If the pipe2 syscall is missing and
		2235	C<$flags> is non-zero, fails with C<ENOSYS>.
		2236
		2237	Please refer to L<pipe2(2)> for more info on the C<$flags>, but at the
		2238	time of this writing, C<IO::AIO::O_CLOEXEC>, C<IO::AIO::O_NONBLOCK> and
		2239	C<IO::AIO::O_DIRECT> (Linux 3.4, for packet-based pipes) were supported.
		2240
		2241	=back
		2242
1298	=cut	2243	=cut
1299		2244
1300	min_parallel 8;	2245	min_parallel 8;
1301		2246
1302	END { flush }	2247	END { flush }
1303		2248
1304	1;	2249	1;
1305		2250
		2251	=head1 EVENT LOOP INTEGRATION
		2252
		2253	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2254	automatically into many event loops:
		2255
		2256	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2257	use AnyEvent::AIO;
		2258
		2259	You can also integrate IO::AIO manually into many event loops, here are
		2260	some examples of how to do this:
		2261
		2262	# EV integration
		2263	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2264
		2265	# Event integration
		2266	Event->io (fd => IO::AIO::poll_fileno,
		2267	poll => 'r',
		2268	cb => \&IO::AIO::poll_cb);
		2269
		2270	# Glib/Gtk2 integration
		2271	add_watch Glib::IO IO::AIO::poll_fileno,
		2272	in => sub { IO::AIO::poll_cb; 1 };
		2273
		2274	# Tk integration
		2275	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2276	readable => \&IO::AIO::poll_cb);
		2277
		2278	# Danga::Socket integration
		2279	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2280	\&IO::AIO::poll_cb);
		2281
1306	=head2 FORK BEHAVIOUR	2282	=head2 FORK BEHAVIOUR
1307		2283
1308	This module should do "the right thing" when the process using it forks:	2284	Usage of pthreads in a program changes the semantics of fork
		2285	considerably. Specifically, only async-safe functions can be called after
		2286	fork. Perl doesn't know about this, so in general, you cannot call fork
		2287	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2288	pthreads, so this applies, but many other extensions and (for inexplicable
		2289	reasons) perl itself often is linked against pthreads, so this limitation
		2290	applies to quite a lot of perls.
1309		2291
1310	Before the fork, IO::AIO enters a quiescent state where no requests	2292	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1311	can be added in other threads and no results will be processed. After	2293	only works in the process that loaded it. Forking is fully supported, but
1312	the fork the parent simply leaves the quiescent state and continues	2294	using IO::AIO in the child is not.
1313	request/result processing, while the child frees the request/result queue
1314	(so that the requests started before the fork will only be handled in the
1315	parent). Threads will be started on demand until the limit set in the
1316	parent process has been reached again.
1317		2295
1318	In short: the parent will, after a short pause, continue as if fork had	2296	You might get around by not I<using> IO::AIO before (or after)
1319	not been called, while the child will act as if IO::AIO has not been used	2297	forking. You could also try to call the L<IO::AIO::reinit> function in the
1320	yet.	2298	child:
		2299
		2300	=over 4
		2301
		2302	=item IO::AIO::reinit
		2303
		2304	Abandons all current requests and I/O threads and simply reinitialises all
		2305	data structures. This is not an operation supported by any standards, but
		2306	happens to work on GNU/Linux and some newer BSD systems.
		2307
		2308	The only reasonable use for this function is to call it after forking, if
		2309	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2310	the process will result in undefined behaviour. Calling it at any time
		2311	will also result in any undefined (by POSIX) behaviour.
		2312
		2313	=back
1321		2314
1322	=head2 MEMORY USAGE	2315	=head2 MEMORY USAGE
1323		2316
1324	Per-request usage:	2317	Per-request usage:
1325		2318
…		…
1342		2335
1343	Known bugs will be fixed in the next release.	2336	Known bugs will be fixed in the next release.
1344		2337
1345	=head1 SEE ALSO	2338	=head1 SEE ALSO
1346		2339
1347	L<Coro::AIO>.	2340	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		2341	more natural syntax.
1348		2342
1349	=head1 AUTHOR	2343	=head1 AUTHOR
1350		2344
1351	Marc Lehmann <schmorp@schmorp.de>	2345	Marc Lehmann <schmorp@schmorp.de>
1352	http://home.schmorp.de/	2346	http://home.schmorp.de/

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines