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Revision 1.153 by root, Sat Jun 13 13:33:00 2009 UTC vs.
Revision 1.230 by root, Fri Jul 27 17:24:06 2012 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10	my $fh = shift	10	my $fh = shift
11	or die "/etc/passwd: $!";	11	or die "/etc/passwd: $!";
12	...	12	...
13	};	13	};
14		14
…		…
26	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
27		27
28	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
29	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
30		30
31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
32	use AnyEvent::AIO;
33
34	# EV integration
35	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
36
37	# Event integration
38	Event->io (fd => IO::AIO::poll_fileno,
39	poll => 'r',
40	cb => \&IO::AIO::poll_cb);
41
42	# Glib/Gtk2 integration
43	add_watch Glib::IO IO::AIO::poll_fileno,
44	in => sub { IO::AIO::poll_cb; 1 };
45
46	# Tk integration
47	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
48	readable => \&IO::AIO::poll_cb);
49
50	# Danga::Socket integration
51	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
52	\&IO::AIO::poll_cb);
53
54	=head1 DESCRIPTION	31	=head1 DESCRIPTION
55		32
56	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
57	operating system supports.	34	operating system supports. It is implemented as an interface to C<libeio>
		35	(L<http://software.schmorp.de/pkg/libeio.html>).
58		36
59	Asynchronous means that operations that can normally block your program	37	Asynchronous means that operations that can normally block your program
60	(e.g. reading from disk) will be done asynchronously: the operation	38	(e.g. reading from disk) will be done asynchronously: the operation
61	will still block, but you can do something else in the meantime. This	39	will still block, but you can do something else in the meantime. This
62	is extremely useful for programs that need to stay interactive even	40	is extremely useful for programs that need to stay interactive even
…		…
66	on a RAID volume or over NFS when you do a number of stat operations	44	on a RAID volume or over NFS when you do a number of stat operations
67	concurrently.	45	concurrently.
68		46
69	While most of this works on all types of file descriptors (for	47	While most of this works on all types of file descriptors (for
70	example sockets), using these functions on file descriptors that	48	example sockets), using these functions on file descriptors that
71	support nonblocking operation (again, sockets, pipes etc.) is very	49	support nonblocking operation (again, sockets, pipes etc.) is
72	inefficient. Use an event loop for that (such as the L<Event|Event>	50	very inefficient. Use an event loop for that (such as the L<EV>
73	module): IO::AIO will naturally fit into such an event loop itself.	51	module): IO::AIO will naturally fit into such an event loop itself.
74		52
75	In this version, a number of threads are started that execute your	53	In this version, a number of threads are started that execute your
76	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
77	in perl, and the threads created by this module will not be visible	55	in perl, and the threads created by this module will not be visible
…		…
87	yourself, always call C<poll_cb> from within the same thread, or never	65	yourself, always call C<poll_cb> from within the same thread, or never
88	call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
89		67
90	=head2 EXAMPLE	68	=head2 EXAMPLE
91		69
92	This is a simple example that uses the Event module and loads	70	This is a simple example that uses the EV module and loads
93	F</etc/passwd> asynchronously:	71	F</etc/passwd> asynchronously:
94		72
95	use Fcntl;	73	use Fcntl;
96	use Event;	74	use EV;
97	use IO::AIO;	75	use IO::AIO;
98		76
99	# register the IO::AIO callback with Event	77	# register the IO::AIO callback with EV
100	Event->io (fd => IO::AIO::poll_fileno,	78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
101	poll => 'r',
102	cb => \&IO::AIO::poll_cb);
103		79
104	# queue the request to open /etc/passwd	80	# queue the request to open /etc/passwd
105	aio_open "/etc/passwd", O_RDONLY, 0, sub {	81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
106	my $fh = shift	82	my $fh = shift
107	or die "error while opening: $!";	83	or die "error while opening: $!";
108		84
109	# stat'ing filehandles is generally non-blocking	85	# stat'ing filehandles is generally non-blocking
110	my $size = -s $fh;	86	my $size = -s $fh;
…		…
119		95
120	# file contents now in $contents	96	# file contents now in $contents
121	print $contents;	97	print $contents;
122		98
123	# exit event loop and program	99	# exit event loop and program
124	Event::unloop;	100	EV::unloop;
125	};	101	};
126	};	102	};
127		103
128	# possibly queue up other requests, or open GUI windows,	104	# possibly queue up other requests, or open GUI windows,
129	# check for sockets etc. etc.	105	# check for sockets etc. etc.
130		106
131	# process events as long as there are some:	107	# process events as long as there are some:
132	Event::loop;	108	EV::loop;
133		109
134	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
135		111
136	Every C<aio_*> function creates a request. which is a C data structure not	112	Every C<aio_*> function creates a request. which is a C data structure not
137	directly visible to Perl.	113	directly visible to Perl.
…		…
187		163
188	package IO::AIO;	164	package IO::AIO;
189		165
190	use Carp ();	166	use Carp ();
191		167
192	no warnings;	168	use common::sense;
193	use strict 'vars';
194		169
195	use base 'Exporter';	170	use base 'Exporter';
196		171
197	BEGIN {	172	BEGIN {
198	our $VERSION = '3.22';	173	our $VERSION = '4.15';
199		174
200	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close	175	our @AIO_REQ = qw(aio_sendfile aio_seek aio_read aio_write aio_open aio_close
201	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
202	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
203	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead	178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
		179	aio_pathsync aio_readahead aio_fiemap
204	aio_rename aio_link aio_move aio_copy aio_group	180	aio_rename aio_link aio_move aio_copy aio_group
205	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown	181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
206	aio_chmod aio_utime aio_truncate);	182	aio_chmod aio_utime aio_truncate
		183	aio_msync aio_mtouch aio_mlock aio_mlockall
		184	aio_statvfs
		185	aio_wd);
207		186
208	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
209	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
210	min_parallel max_parallel max_idle	189	min_parallel max_parallel max_idle idle_timeout
211	nreqs nready npending nthreads	190	nreqs nready npending nthreads
212	max_poll_time max_poll_reqs);	191	max_poll_time max_poll_reqs
		192	sendfile fadvise madvise
		193	mmap munmap munlock munlockall);
213		194
214	push @AIO_REQ, qw(aio_busy); # not exported	195	push @AIO_REQ, qw(aio_busy); # not exported
215		196
216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
217		198
…		…
219	XSLoader::load ("IO::AIO", $VERSION);	200	XSLoader::load ("IO::AIO", $VERSION);
220	}	201	}
221		202
222	=head1 FUNCTIONS	203	=head1 FUNCTIONS
223		204
224	=head2 AIO REQUEST FUNCTIONS	205	=head2 QUICK OVERVIEW
		206
		207	This section simply lists the prototypes most of the functions for
		208	quick reference. See the following sections for function-by-function
		209	documentation.
		210
		211	aio_wd $pathname, $callback->($wd)
		212	aio_open $pathname, $flags, $mode, $callback->($fh)
		213	aio_close $fh, $callback->($status)
		214	aio_seek $fh,$offset,$whence, $callback->($offs)
		215	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		216	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		217	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		218	aio_readahead $fh,$offset,$length, $callback->($retval)
		219	aio_stat $fh_or_path, $callback->($status)
		220	aio_lstat $fh, $callback->($status)
		221	aio_statvfs $fh_or_path, $callback->($statvfs)
		222	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		223	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		224	aio_chmod $fh_or_path, $mode, $callback->($status)
		225	aio_truncate $fh_or_path, $offset, $callback->($status)
		226	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		227	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		228	aio_unlink $pathname, $callback->($status)
		229	aio_mknod $pathname, $mode, $dev, $callback->($status)
		230	aio_link $srcpath, $dstpath, $callback->($status)
		231	aio_symlink $srcpath, $dstpath, $callback->($status)
		232	aio_readlink $pathname, $callback->($link)
		233	aio_realpath $pathname, $callback->($link)
		234	aio_rename $srcpath, $dstpath, $callback->($status)
		235	aio_mkdir $pathname, $mode, $callback->($status)
		236	aio_rmdir $pathname, $callback->($status)
		237	aio_readdir $pathname, $callback->($entries)
		238	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		239	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		240	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		241	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		242	aio_load $pathname, $data, $callback->($status)
		243	aio_copy $srcpath, $dstpath, $callback->($status)
		244	aio_move $srcpath, $dstpath, $callback->($status)
		245	aio_rmtree $pathname, $callback->($status)
		246	aio_sync $callback->($status)
		247	aio_syncfs $fh, $callback->($status)
		248	aio_fsync $fh, $callback->($status)
		249	aio_fdatasync $fh, $callback->($status)
		250	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		251	aio_pathsync $pathname, $callback->($status)
		252	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		253	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		254	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		255	aio_mlockall $flags, $callback->($status)
		256	aio_group $callback->(...)
		257	aio_nop $callback->()
		258
		259	$prev_pri = aioreq_pri [$pri]
		260	aioreq_nice $pri_adjust
		261
		262	IO::AIO::poll_wait
		263	IO::AIO::poll_cb
		264	IO::AIO::poll
		265	IO::AIO::flush
		266	IO::AIO::max_poll_reqs $nreqs
		267	IO::AIO::max_poll_time $seconds
		268	IO::AIO::min_parallel $nthreads
		269	IO::AIO::max_parallel $nthreads
		270	IO::AIO::max_idle $nthreads
		271	IO::AIO::idle_timeout $seconds
		272	IO::AIO::max_outstanding $maxreqs
		273	IO::AIO::nreqs
		274	IO::AIO::nready
		275	IO::AIO::npending
		276
		277	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		278	IO::AIO::fadvise $fh, $offset, $len, $advice
		279	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		280	IO::AIO::munmap $scalar
		281	IO::AIO::madvise $scalar, $offset, $length, $advice
		282	IO::AIO::mprotect $scalar, $offset, $length, $protect
		283	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		284	IO::AIO::munlockall
		285
		286	=head2 API NOTES
225		287
226	All the C<aio_*> calls are more or less thin wrappers around the syscall	288	All the C<aio_*> calls are more or less thin wrappers around the syscall
227	with the same name (sans C<aio_>). The arguments are similar or identical,	289	with the same name (sans C<aio_>). The arguments are similar or identical,
228	and they all accept an additional (and optional) C<$callback> argument	290	and they all accept an additional (and optional) C<$callback> argument
229	which must be a code reference. This code reference will get called with	291	which must be a code reference. This code reference will be called after
230	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	292	the syscall has been executed in an asynchronous fashion. The results
231	perl, which usually delivers "false") as its sole argument after the given	293	of the request will be passed as arguments to the callback (and, if an
232	syscall has been executed asynchronously.	294	error occured, in C<$!>) - for most requests the syscall return code (e.g.
		295	most syscalls return C<-1> on error, unlike perl, which usually delivers
		296	"false").
		297
		298	Some requests (such as C<aio_readdir>) pass the actual results and
		299	communicate failures by passing C<undef>.
233		300
234	All functions expecting a filehandle keep a copy of the filehandle	301	All functions expecting a filehandle keep a copy of the filehandle
235	internally until the request has finished.	302	internally until the request has finished.
236		303
237	All functions return request objects of type L<IO::AIO::REQ> that allow	304	All functions return request objects of type L<IO::AIO::REQ> that allow
238	further manipulation of those requests while they are in-flight.	305	further manipulation of those requests while they are in-flight.
239		306
240	The pathnames you pass to these routines I<must> be absolute and	307	The pathnames you pass to these routines I<should> be absolute. The
241	encoded as octets. The reason for the former is that at the time the	308	reason for this is that at the time the request is being executed, the
242	request is being executed, the current working directory could have	309	current working directory could have changed. Alternatively, you can
243	changed. Alternatively, you can make sure that you never change the	310	make sure that you never change the current working directory anywhere
244	current working directory anywhere in the program and then use relative	311	in the program and then use relative paths. You can also take advantage
245	paths.	312	of IO::AIOs working directory abstraction, that lets you specify paths
		313	relative to some previously-opened "working directory object" - see the
		314	description of the C<IO::AIO::WD> class later in this document.
246		315
247	To encode pathnames as octets, either make sure you either: a) always pass	316	To encode pathnames as octets, either make sure you either: a) always pass
248	in filenames you got from outside (command line, readdir etc.) without	317	in filenames you got from outside (command line, readdir etc.) without
249	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode	318	tinkering, b) are in your native filesystem encoding, c) use the Encode
250	your pathnames to the locale (or other) encoding in effect in the user	319	module and encode your pathnames to the locale (or other) encoding in
251	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	320	effect in the user environment, d) use Glib::filename_from_unicode on
252	use something else to ensure your scalar has the correct contents.	321	unicode filenames or e) use something else to ensure your scalar has the
		322	correct contents.
253		323
254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	324	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
255	handles correctly whether it is set or not.	325	handles correctly whether it is set or not.
		326
		327	=head2 AIO REQUEST FUNCTIONS
256		328
257	=over 4	329	=over 4
258		330
259	=item $prev_pri = aioreq_pri [$pri]	331	=item $prev_pri = aioreq_pri [$pri]
260		332
…		…
307	by the umask in effect then the request is being executed, so better never	379	by the umask in effect then the request is being executed, so better never
308	change the umask.	380	change the umask.
309		381
310	Example:	382	Example:
311		383
312	aio_open "/etc/passwd", O_RDONLY, 0, sub {	384	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
313	if ($_[0]) {	385	if ($_[0]) {
314	print "open successful, fh is $_[0]\n";	386	print "open successful, fh is $_[0]\n";
315	...	387	...
316	} else {	388	} else {
317	die "open failed: $!\n";	389	die "open failed: $!\n";
318	}	390	}
319	};	391	};
320		392
		393	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		394	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		395	following POSIX and non-POSIX constants are available (missing ones on
		396	your system are, as usual, C<0>):
		397
		398	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		399	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		400	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		401
321		402
322	=item aio_close $fh, $callback->($status)	403	=item aio_close $fh, $callback->($status)
323		404
324	Asynchronously close a file and call the callback with the result	405	Asynchronously close a file and call the callback with the result
325	code.	406	code.
…		…
333		414
334	Or in other words: the file descriptor will be closed, but it will not be	415	Or in other words: the file descriptor will be closed, but it will not be
335	free for reuse until the perl filehandle is closed.	416	free for reuse until the perl filehandle is closed.
336		417
337	=cut	418	=cut
		419
		420	=item aio_seek $fh, $offset, $whence, $callback->($offs)
		421
		422	Seeks the filehandle to the new C<$offset>, similarly to perl's
		423	C<sysseek>. The C<$whence> can use the traditional values (C<0> for
		424	C<IO::AIO::SEEK_SET>, C<1> for C<IO::AIO::SEEK_CUR> or C<2> for
		425	C<IO::AIO::SEEK_END>).
		426
		427	The resulting absolute offset will be passed to the callback, or C<-1> in
		428	case of an error.
		429
		430	In theory, the C<$whence> constants could be different than the
		431	corresponding values from L<Fcntl>, but perl guarantees they are the same,
		432	so don't panic.
		433
		434	As a GNU/Linux (and maybe Solaris) extension, also the constants
		435	C<IO::AIO::SEEK_DATA> and C<IO::AIO::SEEK_HOLE> are available, if they
		436	could be found. No guarantees about suitability for use in C<aio_seek> or
		437	Perl's C<sysseek> can be made though, although I would naively assume they
		438	"just work".
338		439
339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	440	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
340		441
341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	442	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
342		443
…		…
375		476
376	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	477	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
377	reading at byte offset C<$in_offset>, and starts writing at the current	478	reading at byte offset C<$in_offset>, and starts writing at the current
378	file offset of C<$out_fh>. Because of that, it is not safe to issue more	479	file offset of C<$out_fh>. Because of that, it is not safe to issue more
379	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	480	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
380	other.	481	other. The same C<$in_fh> works fine though, as this function does not
		482	move or use the file offset of C<$in_fh>.
381		483
		484	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		485	are written, and there is no way to find out how many more bytes have been
		486	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		487	number of bytes written to C<$out_fh>. Only if the result value equals
		488	C<$length> one can assume that C<$length> bytes have been read.
		489
		490	Unlike with other C<aio_> functions, it makes a lot of sense to use
		491	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		492	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		493	the socket I/O will be non-blocking. Note, however, that you can run
		494	into a trap where C<aio_sendfile> reads some data with readahead, then
		495	fails to write all data, and when the socket is ready the next time, the
		496	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		497	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		498	resource usage.
		499
382	This call tries to make use of a native C<sendfile> syscall to provide	500	This call tries to make use of a native C<sendfile>-like syscall to
383	zero-copy operation. For this to work, C<$out_fh> should refer to a	501	provide zero-copy operation. For this to work, C<$out_fh> should refer to
384	socket, and C<$in_fh> should refer to mmap'able file.	502	a socket, and C<$in_fh> should refer to an mmap'able file.
385		503
386	If the native sendfile call fails or is not implemented, it will be	504	If a native sendfile cannot be found or it fails with C<ENOSYS>,
387	emulated, so you can call C<aio_sendfile> on any type of filehandle	505	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		506	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
388	regardless of the limitations of the operating system.	507	type of filehandle regardless of the limitations of the operating system.
389		508
390	Please note, however, that C<aio_sendfile> can read more bytes from	509	As native sendfile syscalls (as practically any non-POSIX interface hacked
391	C<$in_fh> than are written, and there is no way to find out how many	510	together in a hurry to improve benchmark numbers) tend to be rather buggy
392	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	511	on many systems, this implementation tries to work around some known bugs
393	provides the number of bytes written to C<$out_fh>. Only if the result	512	in Linux and FreeBSD kernels (probably others, too), but that might fail,
394	value equals C<$length> one can assume that C<$length> bytes have been	513	so you really really should check the return value of C<aio_sendfile> -
395	read.	514	fewre bytes than expected might have been transferred.
396		515
397		516
398	=item aio_readahead $fh,$offset,$length, $callback->($retval)	517	=item aio_readahead $fh,$offset,$length, $callback->($retval)
399		518
400	C<aio_readahead> populates the page cache with data from a file so that	519	C<aio_readahead> populates the page cache with data from a file so that
…		…
423		542
424	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	543	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
425	error when stat'ing a large file, the results will be silently truncated	544	error when stat'ing a large file, the results will be silently truncated
426	unless perl itself is compiled with large file support.	545	unless perl itself is compiled with large file support.
427		546
		547	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		548	following constants and functions (if not implemented, the constants will
		549	be C<0> and the functions will either C<croak> or fall back on traditional
		550	behaviour).
		551
		552	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		553	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		554	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		555
428	Example: Print the length of F</etc/passwd>:	556	Example: Print the length of F</etc/passwd>:
429		557
430	aio_stat "/etc/passwd", sub {	558	aio_stat "/etc/passwd", sub {
431	$_[0] and die "stat failed: $!";	559	$_[0] and die "stat failed: $!";
432	print "size is ", -s _, "\n";	560	print "size is ", -s _, "\n";
433	};	561	};
434		562
435		563
		564	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		565
		566	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		567	whether a file handle or path was passed.
		568
		569	On success, the callback is passed a hash reference with the following
		570	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		571	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		572	is passed.
		573
		574	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		575	C<ST_NOSUID>.
		576
		577	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		578	their correct value when available, or to C<0> on systems that do
		579	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		580	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		581	C<ST_NODIRATIME> and C<ST_RELATIME>.
		582
		583	Example: stat C</wd> and dump out the data if successful.
		584
		585	aio_statvfs "/wd", sub {
		586	my $f = $_[0]
		587	or die "statvfs: $!";
		588
		589	use Data::Dumper;
		590	say Dumper $f;
		591	};
		592
		593	# result:
		594	{
		595	bsize => 1024,
		596	bfree => 4333064312,
		597	blocks => 10253828096,
		598	files => 2050765568,
		599	flag => 4096,
		600	favail => 2042092649,
		601	bavail => 4333064312,
		602	ffree => 2042092649,
		603	namemax => 255,
		604	frsize => 1024,
		605	fsid => 1810
		606	}
		607
		608
436	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	609	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
437		610
438	Works like perl's C<utime> function (including the special case of $atime	611	Works like perl's C<utime> function (including the special case of $atime
439	and $mtime being undef). Fractional times are supported if the underlying	612	and $mtime being undef). Fractional times are supported if the underlying
440	syscalls support them.	613	syscalls support them.
…		…
467	=item aio_truncate $fh_or_path, $offset, $callback->($status)	640	=item aio_truncate $fh_or_path, $offset, $callback->($status)
468		641
469	Works like truncate(2) or ftruncate(2).	642	Works like truncate(2) or ftruncate(2).
470		643
471		644
		645	=item aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		646
		647	Allocates or freed disk space according to the C<$mode> argument. See the
		648	linux C<fallocate> docuemntation for details.
		649
		650	C<$mode> can currently be C<0> or C<IO::AIO::FALLOC_FL_KEEP_SIZE>
		651	to allocate space, or C<IO::AIO::FALLOC_FL_PUNCH_HOLE |
		652	IO::AIO::FALLOC_FL_KEEP_SIZE>, to deallocate a file range.
		653
		654	The file system block size used by C<fallocate> is presumably the
		655	C<f_bsize> returned by C<statvfs>.
		656
		657	If C<fallocate> isn't available or cannot be emulated (currently no
		658	emulation will be attempted), passes C<-1> and sets C<$!> to C<ENOSYS>.
		659
		660
472	=item aio_chmod $fh_or_path, $mode, $callback->($status)	661	=item aio_chmod $fh_or_path, $mode, $callback->($status)
473		662
474	Works like perl's C<chmod> function.	663	Works like perl's C<chmod> function.
475		664
476		665
…		…
478		667
479	Asynchronously unlink (delete) a file and call the callback with the	668	Asynchronously unlink (delete) a file and call the callback with the
480	result code.	669	result code.
481		670
482		671
483	=item aio_mknod $path, $mode, $dev, $callback->($status)	672	=item aio_mknod $pathname, $mode, $dev, $callback->($status)
484		673
485	[EXPERIMENTAL]	674	[EXPERIMENTAL]
486		675
487	Asynchronously create a device node (or fifo). See mknod(2).	676	Asynchronously create a device node (or fifo). See mknod(2).
488		677
489	The only (POSIX-) portable way of calling this function is:	678	The only (POSIX-) portable way of calling this function is:
490		679
491	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	680	aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
492		681
		682	See C<aio_stat> for info about some potentially helpful extra constants
		683	and functions.
493		684
494	=item aio_link $srcpath, $dstpath, $callback->($status)	685	=item aio_link $srcpath, $dstpath, $callback->($status)
495		686
496	Asynchronously create a new link to the existing object at C<$srcpath> at	687	Asynchronously create a new link to the existing object at C<$srcpath> at
497	the path C<$dstpath> and call the callback with the result code.	688	the path C<$dstpath> and call the callback with the result code.
…		…
501		692
502	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	693	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
503	the path C<$dstpath> and call the callback with the result code.	694	the path C<$dstpath> and call the callback with the result code.
504		695
505		696
506	=item aio_readlink $path, $callback->($link)	697	=item aio_readlink $pathname, $callback->($link)
507		698
508	Asynchronously read the symlink specified by C<$path> and pass it to	699	Asynchronously read the symlink specified by C<$path> and pass it to
509	the callback. If an error occurs, nothing or undef gets passed to the	700	the callback. If an error occurs, nothing or undef gets passed to the
510	callback.	701	callback.
511		702
512		703
		704	=item aio_realpath $pathname, $callback->($path)
		705
		706	Asynchronously make the path absolute and resolve any symlinks in
		707	C<$path>. The resulting path only consists of directories (Same as
		708	L<Cwd::realpath>).
		709
		710	This request can be used to get the absolute path of the current working
		711	directory by passing it a path of F<.> (a single dot).
		712
		713
513	=item aio_rename $srcpath, $dstpath, $callback->($status)	714	=item aio_rename $srcpath, $dstpath, $callback->($status)
514		715
515	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	716	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
516	rename(2) and call the callback with the result code.	717	rename(2) and call the callback with the result code.
517		718
…		…
539	array-ref with the filenames.	740	array-ref with the filenames.
540		741
541		742
542	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)	743	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
543		744
544	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune	745	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
545	behaviour and output format. In case of an error, C<$entries> will be	746	tune behaviour and output format. In case of an error, C<$entries> will be
546	C<undef>.	747	C<undef>.
547		748
548	The flags are a combination of the following constants, ORed together (the	749	The flags are a combination of the following constants, ORed together (the
549	flags will also be passed to the callback, possibly modified):	750	flags will also be passed to the callback, possibly modified):
550		751
551	=over 4	752	=over 4
552		753
553	=item IO::AIO::READDIR_DENTS	754	=item IO::AIO::READDIR_DENTS
554		755
555	When this flag is off, then the callback gets an arrayref with of names	756	When this flag is off, then the callback gets an arrayref consisting of
556	only (as with C<aio_readdir>), otherwise it gets an arrayref with	757	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
557	C<[$name, $type, $inode]> arrayrefs, each describing a single directory	758	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
558	entry in more detail.	759	entry in more detail.
559		760
560	C<$name> is the name of the entry.	761	C<$name> is the name of the entry.
561		762
…		…
568	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to	769	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
569	know, you have to run stat yourself. Also, for speed reasons, the C<$type>	770	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
570	scalars are read-only: you can not modify them.	771	scalars are read-only: you can not modify them.
571		772
572	C<$inode> is the inode number (which might not be exact on systems with 64	773	C<$inode> is the inode number (which might not be exact on systems with 64
573	bit inode numbers and 32 bit perls). On systems that do not deliver the	774	bit inode numbers and 32 bit perls). This field has unspecified content on
574	inode information, this will always be zero.	775	systems that do not deliver the inode information.
575		776
576	=item IO::AIO::READDIR_DIRS_FIRST	777	=item IO::AIO::READDIR_DIRS_FIRST
577		778
578	When this flag is set, then the names will be returned in an order where	779	When this flag is set, then the names will be returned in an order where
579	likely directories come first. This is useful when you need to quickly	780	likely directories come first, in optimal stat order. This is useful when
580	find directories, or you want to find all directories while avoiding to	781	you need to quickly find directories, or you want to find all directories
581	stat() each entry.	782	while avoiding to stat() each entry.
582		783
583	If the system returns type information in readdir, then this is used	784	If the system returns type information in readdir, then this is used
584	to find directories directly. Otherwise, likely directories are files	785	to find directories directly. Otherwise, likely directories are names
585	beginning with ".", or otherwise files with no dots, of which files with	786	beginning with ".", or otherwise names with no dots, of which names with
586	short names are tried first.	787	short names are tried first.
587		788
588	=item IO::AIO::READDIR_STAT_ORDER	789	=item IO::AIO::READDIR_STAT_ORDER
589		790
590	When this flag is set, then the names will be returned in an order	791	When this flag is set, then the names will be returned in an order
…		…
597		798
598	=item IO::AIO::READDIR_FOUND_UNKNOWN	799	=item IO::AIO::READDIR_FOUND_UNKNOWN
599		800
600	This flag should not be set when calling C<aio_readdirx>. Instead, it	801	This flag should not be set when calling C<aio_readdirx>. Instead, it
601	is being set by C<aio_readdirx>, when any of the C<$type>'s found were	802	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
602	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all	803	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
603	C<$type>'s are known, which can be used to speed up some algorithms.	804	C<$type>'s are known, which can be used to speed up some algorithms.
604		805
605	=back	806	=back
606		807
607		808
608	=item aio_load $path, $data, $callback->($status)	809	=item aio_load $pathname, $data, $callback->($status)
609		810
610	This is a composite request that tries to fully load the given file into	811	This is a composite request that tries to fully load the given file into
611	memory. Status is the same as with aio_read.	812	memory. Status is the same as with aio_read.
612		813
613	=cut	814	=cut
…		…
635		836
636	=item aio_copy $srcpath, $dstpath, $callback->($status)	837	=item aio_copy $srcpath, $dstpath, $callback->($status)
637		838
638	Try to copy the I<file> (directories not supported as either source or	839	Try to copy the I<file> (directories not supported as either source or
639	destination) from C<$srcpath> to C<$dstpath> and call the callback with	840	destination) from C<$srcpath> to C<$dstpath> and call the callback with
640	the C<0> (error) or C<-1> ok.	841	a status of C<0> (ok) or C<-1> (error, see C<$!>).
641		842
642	This is a composite request that creates the destination file with	843	This is a composite request that creates the destination file with
643	mode 0200 and copies the contents of the source file into it using	844	mode 0200 and copies the contents of the source file into it using
644	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	845	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
645	uid/gid, in that order.	846	uid/gid, in that order.
…		…
657	my $grp = aio_group $cb;	858	my $grp = aio_group $cb;
658		859
659	aioreq_pri $pri;	860	aioreq_pri $pri;
660	add $grp aio_open $src, O_RDONLY, 0, sub {	861	add $grp aio_open $src, O_RDONLY, 0, sub {
661	if (my $src_fh = $_[0]) {	862	if (my $src_fh = $_[0]) {
662	my @stat = stat $src_fh; # hmm, might bock over nfs?	863	my @stat = stat $src_fh; # hmm, might block over nfs?
663		864
664	aioreq_pri $pri;	865	aioreq_pri $pri;
665	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	866	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
666	if (my $dst_fh = $_[0]) {	867	if (my $dst_fh = $_[0]) {
667	aioreq_pri $pri;	868	aioreq_pri $pri;
…		…
714		915
715	=item aio_move $srcpath, $dstpath, $callback->($status)	916	=item aio_move $srcpath, $dstpath, $callback->($status)
716		917
717	Try to move the I<file> (directories not supported as either source or	918	Try to move the I<file> (directories not supported as either source or
718	destination) from C<$srcpath> to C<$dstpath> and call the callback with	919	destination) from C<$srcpath> to C<$dstpath> and call the callback with
719	the C<0> (error) or C<-1> ok.	920	a status of C<0> (ok) or C<-1> (error, see C<$!>).
720		921
721	This is a composite request that tries to rename(2) the file first; if	922	This is a composite request that tries to rename(2) the file first; if
722	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if	923	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
723	that is successful, unlinks the C<$srcpath>.	924	that is successful, unlinks the C<$srcpath>.
724		925
…		…
735	if ($_[0] && $! == EXDEV) {	936	if ($_[0] && $! == EXDEV) {
736	aioreq_pri $pri;	937	aioreq_pri $pri;
737	add $grp aio_copy $src, $dst, sub {	938	add $grp aio_copy $src, $dst, sub {
738	$grp->result ($_[0]);	939	$grp->result ($_[0]);
739		940
740	if (!$_[0]) {	941	unless ($_[0]) {
741	aioreq_pri $pri;	942	aioreq_pri $pri;
742	add $grp aio_unlink $src;	943	add $grp aio_unlink $src;
743	}	944	}
744	};	945	};
745	} else {	946	} else {
…		…
748	};	949	};
749		950
750	$grp	951	$grp
751	}	952	}
752		953
753	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	954	=item aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
754		955
755	Scans a directory (similar to C<aio_readdir>) but additionally tries to	956	Scans a directory (similar to C<aio_readdir>) but additionally tries to
756	efficiently separate the entries of directory C<$path> into two sets of	957	efficiently separate the entries of directory C<$path> into two sets of
757	names, directories you can recurse into (directories), and ones you cannot	958	names, directories you can recurse into (directories), and ones you cannot
758	recurse into (everything else, including symlinks to directories).	959	recurse into (everything else, including symlinks to directories).
…		…
789	Then entries will be sorted into likely directories a non-initial dot	990	Then entries will be sorted into likely directories a non-initial dot
790	currently) and likely non-directories (see C<aio_readdirx>). Then every	991	currently) and likely non-directories (see C<aio_readdirx>). Then every
791	entry plus an appended C</.> will be C<stat>'ed, likely directories first,	992	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
792	in order of their inode numbers. If that succeeds, it assumes that the	993	in order of their inode numbers. If that succeeds, it assumes that the
793	entry is a directory or a symlink to directory (which will be checked	994	entry is a directory or a symlink to directory (which will be checked
794	seperately). This is often faster than stat'ing the entry itself because	995	separately). This is often faster than stat'ing the entry itself because
795	filesystems might detect the type of the entry without reading the inode	996	filesystems might detect the type of the entry without reading the inode
796	data (e.g. ext2fs filetype feature), even on systems that cannot return	997	data (e.g. ext2fs filetype feature), even on systems that cannot return
797	the filetype information on readdir.	998	the filetype information on readdir.
798		999
799	If the known number of directories (link count - 2) has been reached, the	1000	If the known number of directories (link count - 2) has been reached, the
…		…
815		1016
816	my $grp = aio_group $cb;	1017	my $grp = aio_group $cb;
817		1018
818	$maxreq = 4 if $maxreq <= 0;	1019	$maxreq = 4 if $maxreq <= 0;
819		1020
820	# stat once	1021	# get a wd object
821	aioreq_pri $pri;	1022	aioreq_pri $pri;
822	add $grp aio_stat $path, sub {	1023	add $grp aio_wd $path, sub {
		1024	$_[0]
823	return $grp->result () if $_[0];	1025	or return $grp->result ();
824	my $now = time;
825	my $hash1 = join ":", (stat _)[0,1,3,7,9];
826		1026
827	# read the directory entries	1027	my $wd = [shift, "."];
		1028
		1029	# stat once
828	aioreq_pri $pri;	1030	aioreq_pri $pri;
829	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {	1031	add $grp aio_stat $wd, sub {
830	my $entries = shift
831	or return $grp->result ();	1032	return $grp->result () if $_[0];
		1033	my $now = time;
		1034	my $hash1 = join ":", (stat _)[0,1,3,7,9];
832		1035
833	# stat the dir another time	1036	# read the directory entries
834	aioreq_pri $pri;	1037	aioreq_pri $pri;
		1038	add $grp aio_readdirx $wd, READDIR_DIRS_FIRST, sub {
		1039	my $entries = shift
		1040	or return $grp->result ();
		1041
		1042	# stat the dir another time
		1043	aioreq_pri $pri;
835	add $grp aio_stat $path, sub {	1044	add $grp aio_stat $wd, sub {
836	my $hash2 = join ":", (stat _)[0,1,3,7,9];	1045	my $hash2 = join ":", (stat _)[0,1,3,7,9];
837		1046
838	my $ndirs;	1047	my $ndirs;
839		1048
840	# take the slow route if anything looks fishy	1049	# take the slow route if anything looks fishy
841	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	1050	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
842	$ndirs = -1;	1051	$ndirs = -1;
843	} else {	1052	} else {
844	# if nlink == 2, we are finished	1053	# if nlink == 2, we are finished
845	# for non-posix-fs's, we rely on nlink < 2	1054	# for non-posix-fs's, we rely on nlink < 2
846	$ndirs = (stat _)[3] - 2	1055	$ndirs = (stat _)[3] - 2
847	or return $grp->result ([], $entries);	1056	or return $grp->result ([], $entries);
848	}	1057	}
849		1058
850	my (@dirs, @nondirs);	1059	my (@dirs, @nondirs);
851		1060
852	my $statgrp = add $grp aio_group sub {	1061	my $statgrp = add $grp aio_group sub {
853	$grp->result (\@dirs, \@nondirs);	1062	$grp->result (\@dirs, \@nondirs);
854	};	1063	};
855		1064
856	limit $statgrp $maxreq;	1065	limit $statgrp $maxreq;
857	feed $statgrp sub {	1066	feed $statgrp sub {
858	return unless @$entries;	1067	return unless @$entries;
859	my $entry = shift @$entries;	1068	my $entry = shift @$entries;
860		1069
861	aioreq_pri $pri;	1070	aioreq_pri $pri;
		1071	$wd->[1] = "$entry/.";
862	add $statgrp aio_stat "$path/$entry/.", sub {	1072	add $statgrp aio_stat $wd, sub {
863	if ($_[0] < 0) {	1073	if ($_[0] < 0) {
864	push @nondirs, $entry;	1074	push @nondirs, $entry;
865	} else {	1075	} else {
866	# need to check for real directory	1076	# need to check for real directory
867	aioreq_pri $pri;	1077	aioreq_pri $pri;
		1078	$wd->[1] = $entry;
868	add $statgrp aio_lstat "$path/$entry", sub {	1079	add $statgrp aio_lstat $wd, sub {
869	if (-d _) {	1080	if (-d _) {
870	push @dirs, $entry;	1081	push @dirs, $entry;
871		1082
872	unless (--$ndirs) {	1083	unless (--$ndirs) {
873	push @nondirs, @$entries;	1084	push @nondirs, @$entries;
874	feed $statgrp;	1085	feed $statgrp;
		1086	}
		1087	} else {
		1088	push @nondirs, $entry;
875	}	1089	}
876	} else {
877	push @nondirs, $entry;
878	}	1090	}
879	}	1091	}
880	}	1092	};
881	};	1093	};
882	};	1094	};
883	};	1095	};
884	};	1096	};
885	};	1097	};
886		1098
887	$grp	1099	$grp
888	}	1100	}
889		1101
890	=item aio_rmtree $path, $callback->($status)	1102	=item aio_rmtree $pathname, $callback->($status)
891		1103
892	Delete a directory tree starting (and including) C<$path>, return the	1104	Delete a directory tree starting (and including) C<$path>, return the
893	status of the final C<rmdir> only. This is a composite request that	1105	status of the final C<rmdir> only. This is a composite request that
894	uses C<aio_scandir> to recurse into and rmdir directories, and unlink	1106	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
895	everything else.	1107	everything else.
…		…
937	callback with the fdatasync result code.	1149	callback with the fdatasync result code.
938		1150
939	If this call isn't available because your OS lacks it or it couldn't be	1151	If this call isn't available because your OS lacks it or it couldn't be
940	detected, it will be emulated by calling C<fsync> instead.	1152	detected, it will be emulated by calling C<fsync> instead.
941		1153
		1154	=item aio_syncfs $fh, $callback->($status)
		1155
		1156	Asynchronously call the syncfs syscall to sync the filesystem associated
		1157	to the given filehandle and call the callback with the syncfs result
		1158	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1159	errno to C<ENOSYS> nevertheless.
		1160
942	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	1161	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
943		1162
944	Sync the data portion of the file specified by C<$offset> and C<$length>	1163	Sync the data portion of the file specified by C<$offset> and C<$length>
945	to disk (but NOT the metadata), by calling the Linux-specific	1164	to disk (but NOT the metadata), by calling the Linux-specific
946	sync_file_range call. If sync_file_range is not available or it returns	1165	sync_file_range call. If sync_file_range is not available or it returns
…		…
949	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,	1168	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
950	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and	1169	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
951	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range	1170	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
952	manpage for details.	1171	manpage for details.
953		1172
954	=item aio_pathsync $path, $callback->($status)	1173	=item aio_pathsync $pathname, $callback->($status)
955		1174
956	This request tries to open, fsync and close the given path. This is a	1175	This request tries to open, fsync and close the given path. This is a
957	composite request intended to sync directories after directory operations	1176	composite request intended to sync directories after directory operations
958	(E.g. rename). This might not work on all operating systems or have any	1177	(E.g. rename). This might not work on all operating systems or have any
959	specific effect, but usually it makes sure that directory changes get	1178	specific effect, but usually it makes sure that directory changes get
960	written to disc. It works for anything that can be opened for read-only,	1179	written to disc. It works for anything that can be opened for read-only,
961	not just directories.	1180	not just directories.
		1181
		1182	Future versions of this function might fall back to other methods when
		1183	C<fsync> on the directory fails (such as calling C<sync>).
962		1184
963	Passes C<0> when everything went ok, and C<-1> on error.	1185	Passes C<0> when everything went ok, and C<-1> on error.
964		1186
965	=cut	1187	=cut
966		1188
…		…
987	};	1209	};
988		1210
989	$grp	1211	$grp
990	}	1212	}
991		1213
		1214	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1215
		1216	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1217	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1218	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1219	scalar must only be modified in-place while an aio operation is pending on
		1220	it).
		1221
		1222	It calls the C<msync> function of your OS, if available, with the memory
		1223	area starting at C<$offset> in the string and ending C<$length> bytes
		1224	later. If C<$length> is negative, counts from the end, and if C<$length>
		1225	is C<undef>, then it goes till the end of the string. The flags can be
		1226	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1227	C<IO::AIO::MS_SYNC>.
		1228
		1229	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1230
		1231	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1232	scalars.
		1233
		1234	It touches (reads or writes) all memory pages in the specified
		1235	range inside the scalar. All caveats and parameters are the same
		1236	as for C<aio_msync>, above, except for flags, which must be either
		1237	C<0> (which reads all pages and ensures they are instantiated) or
		1238	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1239	writing an octet from it, which dirties the page).
		1240
		1241	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1242
		1243	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1244	scalars.
		1245
		1246	It reads in all the pages of the underlying storage into memory (if any)
		1247	and locks them, so they are not getting swapped/paged out or removed.
		1248
		1249	If C<$length> is undefined, then the scalar will be locked till the end.
		1250
		1251	On systems that do not implement C<mlock>, this function returns C<-1>
		1252	and sets errno to C<ENOSYS>.
		1253
		1254	Note that the corresponding C<munlock> is synchronous and is
		1255	documented under L<MISCELLANEOUS FUNCTIONS>.
		1256
		1257	Example: open a file, mmap and mlock it - both will be undone when
		1258	C<$data> gets destroyed.
		1259
		1260	open my $fh, "<", $path or die "$path: $!";
		1261	my $data;
		1262	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1263	aio_mlock $data; # mlock in background
		1264
		1265	=item aio_mlockall $flags, $callback->($status)
		1266
		1267	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1268	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1269
		1270	On systems that do not implement C<mlockall>, this function returns C<-1>
		1271	and sets errno to C<ENOSYS>.
		1272
		1273	Note that the corresponding C<munlockall> is synchronous and is
		1274	documented under L<MISCELLANEOUS FUNCTIONS>.
		1275
		1276	Example: asynchronously lock all current and future pages into memory.
		1277
		1278	aio_mlockall IO::AIO::MCL_FUTURE;
		1279
		1280	=item aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1281
		1282	Queries the extents of the given file (by calling the Linux FIEMAP ioctl,
		1283	see L<http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for details). If the
		1284	C<ioctl> is not available on your OS, then this request will fail with
		1285	C<ENOSYS>.
		1286
		1287	C<$start> is the starting offset to query extents for, C<$length> is the
		1288	size of the range to query - if it is C<undef>, then the whole file will
		1289	be queried.
		1290
		1291	C<$flags> is a combination of flags (C<IO::AIO::FIEMAP_FLAG_SYNC> or
		1292	C<IO::AIO::FIEMAP_FLAG_XATTR> - C<IO::AIO::FIEMAP_FLAGS_COMPAT> is also
		1293	exported), and is normally C<0> or C<IO::AIO::FIEMAP_FLAG_SYNC> to query
		1294	the data portion.
		1295
		1296	C<$count> is the maximum number of extent records to return. If it is
		1297	C<undef>, then IO::AIO queries all extents of the file. As a very special
		1298	case, if it is C<0>, then the callback receives the number of extents
		1299	instead of the extents themselves.
		1300
		1301	If an error occurs, the callback receives no arguments. The special
		1302	C<errno> value C<IO::AIO::EBADR> is available to test for flag errors.
		1303
		1304	Otherwise, the callback receives an array reference with extent
		1305	structures. Each extent structure is an array reference itself, with the
		1306	following members:
		1307
		1308	[$logical, $physical, $length, $flags]
		1309
		1310	Flags is any combination of the following flag values (typically either C<0>
		1311	or C<IO::AIO::FIEMAP_EXTENT_LAST>):
		1312
		1313	C<IO::AIO::FIEMAP_EXTENT_LAST>, C<IO::AIO::FIEMAP_EXTENT_UNKNOWN>,
		1314	C<IO::AIO::FIEMAP_EXTENT_DELALLOC>, C<IO::AIO::FIEMAP_EXTENT_ENCODED>,
		1315	C<IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED>, C<IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED>,
		1316	C<IO::AIO::FIEMAP_EXTENT_DATA_INLINE>, C<IO::AIO::FIEMAP_EXTENT_DATA_TAIL>,
		1317	C<IO::AIO::FIEMAP_EXTENT_UNWRITTEN>, C<IO::AIO::FIEMAP_EXTENT_MERGED> or
		1318	C<IO::AIO::FIEMAP_EXTENT_SHARED>.
		1319
992	=item aio_group $callback->(...)	1320	=item aio_group $callback->(...)
993		1321
994	This is a very special aio request: Instead of doing something, it is a	1322	This is a very special aio request: Instead of doing something, it is a
995	container for other aio requests, which is useful if you want to bundle	1323	container for other aio requests, which is useful if you want to bundle
996	many requests into a single, composite, request with a definite callback	1324	many requests into a single, composite, request with a definite callback
…		…
1032	like sleep and file handle readable/writable, the overhead this creates is	1360	like sleep and file handle readable/writable, the overhead this creates is
1033	immense (it blocks a thread for a long time) so do not use this function	1361	immense (it blocks a thread for a long time) so do not use this function
1034	except to put your application under artificial I/O pressure.	1362	except to put your application under artificial I/O pressure.
1035		1363
1036	=back	1364	=back
		1365
		1366
		1367	=head2 IO::AIO::WD - multiple working directories
		1368
		1369	Your process only has one current working directory, which is used by all
		1370	threads. This makes it hard to use relative paths (some other component
		1371	could call C<chdir> at any time, and it is hard to control when the path
		1372	will be used by IO::AIO).
		1373
		1374	One solution for this is to always use absolute paths. This usually works,
		1375	but can be quite slow (the kernel has to walk the whole path on every
		1376	access), and can also be a hassle to implement.
		1377
		1378	Newer POSIX systems have a number of functions (openat, fdopendir,
		1379	futimensat and so on) that make it possible to specify working directories
		1380	per operation.
		1381
		1382	For portability, and because the clowns who "designed", or shall I write,
		1383	perpetrated this new interface were obviously half-drunk, this abstraction
		1384	cannot be perfect, though.
		1385
		1386	IO::AIO allows you to convert directory paths into a so-called IO::AIO::WD
		1387	object. This object stores the canonicalised, absolute version of the
		1388	path, and on systems that allow it, also a directory file descriptor.
		1389
		1390	Everywhere where a pathname is accepted by IO::AIO (e.g. in C<aio_stat>
		1391	or C<aio_unlink>), one can specify an array reference with an IO::AIO::WD
		1392	object and a pathname instead (or the IO::AIO::WD object alone, which
		1393	gets interpreted as C<[$wd, "."]>). If the pathname is absolute, the
		1394	IO::AIO::WD object is ignored, otherwise the pathname is resolved relative
		1395	to that IO::AIO::WD object.
		1396
		1397	For example, to get a wd object for F</etc> and then stat F<passwd>
		1398	inside, you would write:
		1399
		1400	aio_wd "/etc", sub {
		1401	my $etcdir = shift;
		1402
		1403	# although $etcdir can be undef on error, there is generally no reason
		1404	# to check for errors here, as aio_stat will fail with ENOENT
		1405	# when $etcdir is undef.
		1406
		1407	aio_stat [$etcdir, "passwd"], sub {
		1408	# yay
		1409	};
		1410	};
		1411
		1412	That C<aio_wd> is a request and not a normal function shows that creating
		1413	an IO::AIO::WD object is itself a potentially blocking operation, which is
		1414	why it is done asynchronously.
		1415
		1416	To stat the directory obtained with C<aio_wd> above, one could write
		1417	either of the following three request calls:
		1418
		1419	aio_lstat "/etc" , sub { ... # pathname as normal string
		1420	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1421	aio_lstat $wd , sub { ... # shorthand for the previous
		1422
		1423	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1424	object and the pathname string, so you could write the following without
		1425	causing any issues due to C<$path> getting reused:
		1426
		1427	my $path = [$wd, undef];
		1428
		1429	for my $name (qw(abc def ghi)) {
		1430	$path->[1] = $name;
		1431	aio_stat $path, sub {
		1432	# ...
		1433	};
		1434	}
		1435
		1436	There are some caveats: when directories get renamed (or deleted), the
		1437	pathname string doesn't change, so will point to the new directory (or
		1438	nowhere at all), while the directory fd, if available on the system,
		1439	will still point to the original directory. Most functions accepting a
		1440	pathname will use the directory fd on newer systems, and the string on
		1441	older systems. Some functions (such as realpath) will always rely on the
		1442	string form of the pathname.
		1443
		1444	So this fucntionality is mainly useful to get some protection against
		1445	C<chdir>, to easily get an absolute path out of a relative path for future
		1446	reference, and to speed up doing many operations in the same directory
		1447	(e.g. when stat'ing all files in a directory).
		1448
		1449	The following functions implement this working directory abstraction:
		1450
		1451	=over 4
		1452
		1453	=item aio_wd $pathname, $callback->($wd)
		1454
		1455	Asynchonously canonicalise the given pathname and convert it to an
		1456	IO::AIO::WD object representing it. If possible and supported on the
		1457	system, also open a directory fd to speed up pathname resolution relative
		1458	to this working directory.
		1459
		1460	If something goes wrong, then C<undef> is passwd to the callback instead
		1461	of a working directory object and C<$!> is set appropriately. Since
		1462	passing C<undef> as working directory component of a pathname fails the
		1463	request with C<ENOENT>, there is often no need for error checking in the
		1464	C<aio_wd> callback, as future requests using the value will fail in the
		1465	expected way.
		1466
		1467	If this call isn't available because your OS lacks it or it couldn't be
		1468	detected, it will be emulated by calling C<fsync> instead.
		1469
		1470	=item IO::AIO::CWD
		1471
		1472	This is a compiletime constant (object) that represents the process
		1473	current working directory.
		1474
		1475	Specifying this object as working directory object for a pathname is as
		1476	if the pathname would be specified directly, without a directory object,
		1477	e.g., these calls are functionally identical:
		1478
		1479	aio_stat "somefile", sub { ... };
		1480	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1481
		1482	=back
		1483
1037		1484
1038	=head2 IO::AIO::REQ CLASS	1485	=head2 IO::AIO::REQ CLASS
1039		1486
1040	All non-aggregate C<aio_*> functions return an object of this class when	1487	All non-aggregate C<aio_*> functions return an object of this class when
1041	called in non-void context.	1488	called in non-void context.
…		…
1131	=item $grp->cancel_subs	1578	=item $grp->cancel_subs
1132		1579
1133	Cancel all subrequests and clears any feeder, but not the group request	1580	Cancel all subrequests and clears any feeder, but not the group request
1134	itself. Useful when you queued a lot of events but got a result early.	1581	itself. Useful when you queued a lot of events but got a result early.
1135		1582
		1583	The group request will finish normally (you cannot add requests to the
		1584	group).
		1585
1136	=item $grp->result (...)	1586	=item $grp->result (...)
1137		1587
1138	Set the result value(s) that will be passed to the group callback when all	1588	Set the result value(s) that will be passed to the group callback when all
1139	subrequests have finished and set the groups errno to the current value	1589	subrequests have finished and set the groups errno to the current value
1140	of errno (just like calling C<errno> without an error number). By default,	1590	of errno (just like calling C<errno> without an error number). By default,
…		…
1156		1606
1157	Sets a feeder/generator on this group: every group can have an attached	1607	Sets a feeder/generator on this group: every group can have an attached
1158	generator that generates requests if idle. The idea behind this is that,	1608	generator that generates requests if idle. The idea behind this is that,
1159	although you could just queue as many requests as you want in a group,	1609	although you could just queue as many requests as you want in a group,
1160	this might starve other requests for a potentially long time. For example,	1610	this might starve other requests for a potentially long time. For example,
1161	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,	1611	C<aio_scandir> might generate hundreds of thousands of C<aio_stat>
1162	delaying any later requests for a long time.	1612	requests, delaying any later requests for a long time.
1163		1613
1164	To avoid this, and allow incremental generation of requests, you can	1614	To avoid this, and allow incremental generation of requests, you can
1165	instead a group and set a feeder on it that generates those requests. The	1615	instead a group and set a feeder on it that generates those requests. The
1166	feed callback will be called whenever there are few enough (see C<limit>,	1616	feed callback will be called whenever there are few enough (see C<limit>,
1167	below) requests active in the group itself and is expected to queue more	1617	below) requests active in the group itself and is expected to queue more
…		…
1208	=over 4	1658	=over 4
1209		1659
1210	=item $fileno = IO::AIO::poll_fileno	1660	=item $fileno = IO::AIO::poll_fileno
1211		1661
1212	Return the I<request result pipe file descriptor>. This filehandle must be	1662	Return the I<request result pipe file descriptor>. This filehandle must be
1213	polled for reading by some mechanism outside this module (e.g. Event or	1663	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1214	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1664	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1215	to call C<poll_cb> to check the results.	1665	you have to call C<poll_cb> to check the results.
1216		1666
1217	See C<poll_cb> for an example.	1667	See C<poll_cb> for an example.
1218		1668
1219	=item IO::AIO::poll_cb	1669	=item IO::AIO::poll_cb
1220		1670
1221	Process some outstanding events on the result pipe. You have to call this	1671	Process some outstanding events on the result pipe. You have to call
1222	regularly. Returns C<0> if all events could be processed, or C<-1> if it	1672	this regularly. Returns C<0> if all events could be processed (or there
1223	returned earlier for whatever reason. Returns immediately when no events	1673	were no events to process), or C<-1> if it returned earlier for whatever
1224	are outstanding. The amount of events processed depends on the settings of	1674	reason. Returns immediately when no events are outstanding. The amount of
1225	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1675	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1676	C<IO::AIO::max_poll_time>.
1226		1677
1227	If not all requests were processed for whatever reason, the filehandle	1678	If not all requests were processed for whatever reason, the filehandle
1228	will still be ready when C<poll_cb> returns, so normally you don't have to	1679	will still be ready when C<poll_cb> returns, so normally you don't have to
1229	do anything special to have it called later.	1680	do anything special to have it called later.
1230		1681
		1682	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1683	ready, it can be beneficial to call this function from loops which submit
		1684	a lot of requests, to make sure the results get processed when they become
		1685	available and not just when the loop is finished and the event loop takes
		1686	over again. This function returns very fast when there are no outstanding
		1687	requests.
		1688
1231	Example: Install an Event watcher that automatically calls	1689	Example: Install an Event watcher that automatically calls
1232	IO::AIO::poll_cb with high priority:	1690	IO::AIO::poll_cb with high priority (more examples can be found in the
		1691	SYNOPSIS section, at the top of this document):
1233		1692
1234	Event->io (fd => IO::AIO::poll_fileno,	1693	Event->io (fd => IO::AIO::poll_fileno,
1235	poll => 'r', async => 1,	1694	poll => 'r', async => 1,
1236	cb => \&IO::AIO::poll_cb);	1695	cb => \&IO::AIO::poll_cb);
		1696
		1697	=item IO::AIO::poll_wait
		1698
		1699	If there are any outstanding requests and none of them in the result
		1700	phase, wait till the result filehandle becomes ready for reading (simply
		1701	does a C<select> on the filehandle. This is useful if you want to
		1702	synchronously wait for some requests to finish).
		1703
		1704	See C<nreqs> for an example.
		1705
		1706	=item IO::AIO::poll
		1707
		1708	Waits until some requests have been handled.
		1709
		1710	Returns the number of requests processed, but is otherwise strictly
		1711	equivalent to:
		1712
		1713	IO::AIO::poll_wait, IO::AIO::poll_cb
		1714
		1715	=item IO::AIO::flush
		1716
		1717	Wait till all outstanding AIO requests have been handled.
		1718
		1719	Strictly equivalent to:
		1720
		1721	IO::AIO::poll_wait, IO::AIO::poll_cb
		1722	while IO::AIO::nreqs;
1237		1723
1238	=item IO::AIO::max_poll_reqs $nreqs	1724	=item IO::AIO::max_poll_reqs $nreqs
1239		1725
1240	=item IO::AIO::max_poll_time $seconds	1726	=item IO::AIO::max_poll_time $seconds
1241		1727
…		…
1266	# use a low priority so other tasks have priority	1752	# use a low priority so other tasks have priority
1267	Event->io (fd => IO::AIO::poll_fileno,	1753	Event->io (fd => IO::AIO::poll_fileno,
1268	poll => 'r', nice => 1,	1754	poll => 'r', nice => 1,
1269	cb => &IO::AIO::poll_cb);	1755	cb => &IO::AIO::poll_cb);
1270		1756
1271	=item IO::AIO::poll_wait
1272
1273	If there are any outstanding requests and none of them in the result
1274	phase, wait till the result filehandle becomes ready for reading (simply
1275	does a C<select> on the filehandle. This is useful if you want to
1276	synchronously wait for some requests to finish).
1277
1278	See C<nreqs> for an example.
1279
1280	=item IO::AIO::poll
1281
1282	Waits until some requests have been handled.
1283
1284	Returns the number of requests processed, but is otherwise strictly
1285	equivalent to:
1286
1287	IO::AIO::poll_wait, IO::AIO::poll_cb
1288
1289	=item IO::AIO::flush
1290
1291	Wait till all outstanding AIO requests have been handled.
1292
1293	Strictly equivalent to:
1294
1295	IO::AIO::poll_wait, IO::AIO::poll_cb
1296	while IO::AIO::nreqs;
1297
1298	=back	1757	=back
1299		1758
1300	=head3 CONTROLLING THE NUMBER OF THREADS	1759	=head3 CONTROLLING THE NUMBER OF THREADS
1301		1760
1302	=over	1761	=over
…		…
1335		1794
1336	Under normal circumstances you don't need to call this function.	1795	Under normal circumstances you don't need to call this function.
1337		1796
1338	=item IO::AIO::max_idle $nthreads	1797	=item IO::AIO::max_idle $nthreads
1339		1798
1340	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1799	Limit the number of threads (default: 4) that are allowed to idle
1341	threads that did not get a request to process within 10 seconds). That	1800	(i.e., threads that did not get a request to process within the idle
1342	means if a thread becomes idle while C<$nthreads> other threads are also	1801	timeout (default: 10 seconds). That means if a thread becomes idle while
1343	idle, it will free its resources and exit.	1802	C<$nthreads> other threads are also idle, it will free its resources and
		1803	exit.
1344		1804
1345	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1805	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1346	to allow for extremely high load situations, but want to free resources	1806	to allow for extremely high load situations, but want to free resources
1347	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1807	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1348		1808
1349	The default is probably ok in most situations, especially if thread	1809	The default is probably ok in most situations, especially if thread
1350	creation is fast. If thread creation is very slow on your system you might	1810	creation is fast. If thread creation is very slow on your system you might
1351	want to use larger values.	1811	want to use larger values.
1352		1812
		1813	=item IO::AIO::idle_timeout $seconds
		1814
		1815	Sets the minimum idle timeout (default 10) after which worker threads are
		1816	allowed to exit. SEe C<IO::AIO::max_idle>.
		1817
1353	=item IO::AIO::max_outstanding $maxreqs	1818	=item IO::AIO::max_outstanding $maxreqs
		1819
		1820	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1821	you do queue up more than this number of requests, the next call to
		1822	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1823	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1824	longer exceeded.
		1825
		1826	In other words, this setting does not enforce a queue limit, but can be
		1827	used to make poll functions block if the limit is exceeded.
1354		1828
1355	This is a very bad function to use in interactive programs because it	1829	This is a very bad function to use in interactive programs because it
1356	blocks, and a bad way to reduce concurrency because it is inexact: Better	1830	blocks, and a bad way to reduce concurrency because it is inexact: Better
1357	use an C<aio_group> together with a feed callback.	1831	use an C<aio_group> together with a feed callback.
1358		1832
1359	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1833	It's main use is in scripts without an event loop - when you want to stat
1360	do queue up more than this number of requests, the next call to the	1834	a lot of files, you can write somehting like this:
1361	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1362	function will block until the limit is no longer exceeded.
1363		1835
1364	The default value is very large, so there is no practical limit on the	1836	IO::AIO::max_outstanding 32;
1365	number of outstanding requests.
1366		1837
1367	You can still queue as many requests as you want. Therefore,	1838	for my $path (...) {
1368	C<max_outstanding> is mainly useful in simple scripts (with low values) or	1839	aio_stat $path , ...;
1369	as a stop gap to shield against fatal memory overflow (with large values).	1840	IO::AIO::poll_cb;
		1841	}
		1842
		1843	IO::AIO::flush;
		1844
		1845	The call to C<poll_cb> inside the loop will normally return instantly, but
		1846	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1847	some requests have been handled. This keeps the loop from pushing a large
		1848	number of C<aio_stat> requests onto the queue.
		1849
		1850	The default value for C<max_outstanding> is very large, so there is no
		1851	practical limit on the number of outstanding requests.
1370		1852
1371	=back	1853	=back
1372		1854
1373	=head3 STATISTICAL INFORMATION	1855	=head3 STATISTICAL INFORMATION
1374		1856
…		…
1394	Returns the number of requests currently in the pending state (executed,	1876	Returns the number of requests currently in the pending state (executed,
1395	but not yet processed by poll_cb).	1877	but not yet processed by poll_cb).
1396		1878
1397	=back	1879	=back
1398		1880
		1881	=head3 MISCELLANEOUS FUNCTIONS
		1882
		1883	IO::AIO implements some functions that might be useful, but are not
		1884	asynchronous.
		1885
		1886	=over 4
		1887
		1888	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1889
		1890	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1891	but is blocking (this makes most sense if you know the input data is
		1892	likely cached already and the output filehandle is set to non-blocking
		1893	operations).
		1894
		1895	Returns the number of bytes copied, or C<-1> on error.
		1896
		1897	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1898
		1899	Simply calls the C<posix_fadvise> function (see its
		1900	manpage for details). The following advice constants are
		1901	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1902	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1903	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1904
		1905	On systems that do not implement C<posix_fadvise>, this function returns
		1906	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1907
		1908	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1909
		1910	Simply calls the C<posix_madvise> function (see its
		1911	manpage for details). The following advice constants are
		1912	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1913	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1914
		1915	On systems that do not implement C<posix_madvise>, this function returns
		1916	ENOSYS, otherwise the return value of C<posix_madvise>.
		1917
		1918	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1919
		1920	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1921	$scalar (see its manpage for details). The following protect
		1922	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1923	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1924
		1925	On systems that do not implement C<mprotect>, this function returns
		1926	ENOSYS, otherwise the return value of C<mprotect>.
		1927
		1928	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1929
		1930	Memory-maps a file (or anonymous memory range) and attaches it to the
		1931	given C<$scalar>, which will act like a string scalar. Returns true on
		1932	success, and false otherwise.
		1933
		1934	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1935	change the string length, and most read-only operations such as copying it
		1936	or searching it with regexes and so on.
		1937
		1938	Anything else is unsafe and will, at best, result in memory leaks.
		1939
		1940	The memory map associated with the C<$scalar> is automatically removed
		1941	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1942	C<IO::AIO::munmap> functions are called.
		1943
		1944	This calls the C<mmap>(2) function internally. See your system's manual
		1945	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1946
		1947	The C<$length> must be larger than zero and smaller than the actual
		1948	filesize.
		1949
		1950	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1951	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1952
		1953	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1954	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1955	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1956	(which is set to C<MAP_ANON> if your system only provides this
		1957	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1958	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1959	C<IO::AIO::MAP_NONBLOCK>
		1960
		1961	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1962
		1963	C<$offset> is the offset from the start of the file - it generally must be
		1964	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1965
		1966	Example:
		1967
		1968	use Digest::MD5;
		1969	use IO::AIO;
		1970
		1971	open my $fh, "<verybigfile"
		1972	or die "$!";
		1973
		1974	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1975	or die "verybigfile: $!";
		1976
		1977	my $fast_md5 = md5 $data;
		1978
		1979	=item IO::AIO::munmap $scalar
		1980
		1981	Removes a previous mmap and undefines the C<$scalar>.
		1982
		1983	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1984
		1985	Calls the C<munlock> function, undoing the effects of a previous
		1986	C<aio_mlock> call (see its description for details).
		1987
		1988	=item IO::AIO::munlockall
		1989
		1990	Calls the C<munlockall> function.
		1991
		1992	On systems that do not implement C<munlockall>, this function returns
		1993	ENOSYS, otherwise the return value of C<munlockall>.
		1994
		1995	=item IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		1996
		1997	Calls the GNU/Linux C<splice(2)> syscall, if available. If C<$r_off> or
		1998	C<$w_off> are C<undef>, then C<NULL> is passed for these, otherwise they
		1999	should be the file offset.
		2000
		2001	C<$r_fh> and C<$w_fh> should not refer to the same file, as splice might
		2002	silently corrupt the data in this case.
		2003
		2004	The following symbol flag values are available: C<IO::AIO::SPLICE_F_MOVE>,
		2005	C<IO::AIO::SPLICE_F_NONBLOCK>, C<IO::AIO::SPLICE_F_MORE> and
		2006	C<IO::AIO::SPLICE_F_GIFT>.
		2007
		2008	See the C<splice(2)> manpage for details.
		2009
		2010	=item IO::AIO::tee $r_fh, $w_fh, $length, $flags
		2011
		2012	Calls the GNU/Linux C<tee(2)> syscall, see it's manpage and the
		2013	description for C<IO::AIO::splice> above for details.
		2014
		2015	=back
		2016
1399	=cut	2017	=cut
1400		2018
1401	min_parallel 8;	2019	min_parallel 8;
1402		2020
1403	END { flush }	2021	END { flush }
1404		2022
1405	1;	2023	1;
1406		2024
		2025	=head1 EVENT LOOP INTEGRATION
		2026
		2027	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		2028	automatically into many event loops:
		2029
		2030	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		2031	use AnyEvent::AIO;
		2032
		2033	You can also integrate IO::AIO manually into many event loops, here are
		2034	some examples of how to do this:
		2035
		2036	# EV integration
		2037	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		2038
		2039	# Event integration
		2040	Event->io (fd => IO::AIO::poll_fileno,
		2041	poll => 'r',
		2042	cb => \&IO::AIO::poll_cb);
		2043
		2044	# Glib/Gtk2 integration
		2045	add_watch Glib::IO IO::AIO::poll_fileno,
		2046	in => sub { IO::AIO::poll_cb; 1 };
		2047
		2048	# Tk integration
		2049	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		2050	readable => \&IO::AIO::poll_cb);
		2051
		2052	# Danga::Socket integration
		2053	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		2054	\&IO::AIO::poll_cb);
		2055
1407	=head2 FORK BEHAVIOUR	2056	=head2 FORK BEHAVIOUR
1408		2057
1409	This module should do "the right thing" when the process using it forks:	2058	Usage of pthreads in a program changes the semantics of fork
		2059	considerably. Specifically, only async-safe functions can be called after
		2060	fork. Perl doesn't know about this, so in general, you cannot call fork
		2061	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		2062	pthreads, so this applies, but many other extensions and (for inexplicable
		2063	reasons) perl itself often is linked against pthreads, so this limitation
		2064	applies to quite a lot of perls.
1410		2065
1411	Before the fork, IO::AIO enters a quiescent state where no requests	2066	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1412	can be added in other threads and no results will be processed. After	2067	only works in the process that loaded it. Forking is fully supported, but
1413	the fork the parent simply leaves the quiescent state and continues	2068	using IO::AIO in the child is not.
1414	request/result processing, while the child frees the request/result queue
1415	(so that the requests started before the fork will only be handled in the
1416	parent). Threads will be started on demand until the limit set in the
1417	parent process has been reached again.
1418		2069
1419	In short: the parent will, after a short pause, continue as if fork had	2070	You might get around by not I<using> IO::AIO before (or after)
1420	not been called, while the child will act as if IO::AIO has not been used	2071	forking. You could also try to call the L<IO::AIO::reinit> function in the
1421	yet.	2072	child:
		2073
		2074	=over 4
		2075
		2076	=item IO::AIO::reinit
		2077
		2078	Abandons all current requests and I/O threads and simply reinitialises all
		2079	data structures. This is not an operation supported by any standards, but
		2080	happens to work on GNU/Linux and some newer BSD systems.
		2081
		2082	The only reasonable use for this function is to call it after forking, if
		2083	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		2084	the process will result in undefined behaviour. Calling it at any time
		2085	will also result in any undefined (by POSIX) behaviour.
		2086
		2087	=back
1422		2088
1423	=head2 MEMORY USAGE	2089	=head2 MEMORY USAGE
1424		2090
1425	Per-request usage:	2091	Per-request usage:
1426		2092

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