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Revision 1.107 by root, Fri Jun 1 05:52:59 2007 UTC vs.
Revision 1.208 by root, Mon Sep 26 20:19:08 2011 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
10	my $fh = shift	10	my $fh = shift
11	or die "/etc/passwd: $!";	11	or die "/etc/passwd: $!";
12	...	12	...
13	};	13	};
14		14
…		…
26	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
27		27
28	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
29	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
30		30
31	# AnyEvent integration
32	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
33	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
34
35	# Event integration
36	Event->io (fd => IO::AIO::poll_fileno,
37	poll => 'r',
38	cb => \&IO::AIO::poll_cb);
39
40	# Glib/Gtk2 integration
41	add_watch Glib::IO IO::AIO::poll_fileno,
42	in => sub { IO::AIO::poll_cb; 1 };
43
44	# Tk integration
45	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
46	readable => \&IO::AIO::poll_cb);
47
48	# Danga::Socket integration
49	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
50	\&IO::AIO::poll_cb);
51
52	=head1 DESCRIPTION	31	=head1 DESCRIPTION
53		32
54	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
55	operating system supports.	34	operating system supports. It is implemented as an interface to C<libeio>
		35	(L<http://software.schmorp.de/pkg/libeio.html>).
56		36
57	Asynchronous means that operations that can normally block your program	37	Asynchronous means that operations that can normally block your program
58	(e.g. reading from disk) will be done asynchronously: the operation	38	(e.g. reading from disk) will be done asynchronously: the operation
59	will still block, but you can do something else in the meantime. This	39	will still block, but you can do something else in the meantime. This
60	is extremely useful for programs that need to stay interactive even	40	is extremely useful for programs that need to stay interactive even
…		…
62	etc.), but can also be used to easily do operations in parallel that are	42	etc.), but can also be used to easily do operations in parallel that are
63	normally done sequentially, e.g. stat'ing many files, which is much faster	43	normally done sequentially, e.g. stat'ing many files, which is much faster
64	on a RAID volume or over NFS when you do a number of stat operations	44	on a RAID volume or over NFS when you do a number of stat operations
65	concurrently.	45	concurrently.
66		46
67	While most of this works on all types of file descriptors (for example	47	While most of this works on all types of file descriptors (for
68	sockets), using these functions on file descriptors that support	48	example sockets), using these functions on file descriptors that
69	nonblocking operation (again, sockets, pipes etc.) is very inefficient or	49	support nonblocking operation (again, sockets, pipes etc.) is
70	might not work (aio_read fails on sockets/pipes/fifos). Use an event loop	50	very inefficient. Use an event loop for that (such as the L<EV>
71	for that (such as the L<Event|Event> module): IO::AIO will naturally fit	51	module): IO::AIO will naturally fit into such an event loop itself.
72	into such an event loop itself.
73		52
74	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
75	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
76	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
77	to perl. In the future, this module might make use of the native aio	56	to perl. In the future, this module might make use of the native aio
…		…
79	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
80	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
81	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
82	using threads anyway.	61	using threads anyway.
83		62
84	Although the module will work with in the presence of other (Perl-)	63	Although the module will work in the presence of other (Perl-) threads,
85	threads, it is currently not reentrant in any way, so use appropriate	64	it is currently not reentrant in any way, so use appropriate locking
86	locking yourself, always call C<poll_cb> from within the same thread, or	65	yourself, always call C<poll_cb> from within the same thread, or never
87	never call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
88		67
89	=head2 EXAMPLE	68	=head2 EXAMPLE
90		69
91	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
92	F</etc/passwd> asynchronously:	71	F</etc/passwd> asynchronously:
93		72
94	use Fcntl;	73	use Fcntl;
95	use Event;	74	use EV;
96	use IO::AIO;	75	use IO::AIO;
97		76
98	# register the IO::AIO callback with Event	77	# register the IO::AIO callback with EV
99	Event->io (fd => IO::AIO::poll_fileno,	78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
100	poll => 'r',
101	cb => \&IO::AIO::poll_cb);
102		79
103	# queue the request to open /etc/passwd	80	# queue the request to open /etc/passwd
104	aio_open "/etc/passwd", O_RDONLY, 0, sub {	81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
105	my $fh = shift	82	my $fh = shift
106	or die "error while opening: $!";	83	or die "error while opening: $!";
107		84
108	# stat'ing filehandles is generally non-blocking	85	# stat'ing filehandles is generally non-blocking
109	my $size = -s $fh;	86	my $size = -s $fh;
…		…
118		95
119	# file contents now in $contents	96	# file contents now in $contents
120	print $contents;	97	print $contents;
121		98
122	# exit event loop and program	99	# exit event loop and program
123	Event::unloop;	100	EV::unloop;
124	};	101	};
125	};	102	};
126		103
127	# possibly queue up other requests, or open GUI windows,	104	# possibly queue up other requests, or open GUI windows,
128	# check for sockets etc. etc.	105	# check for sockets etc. etc.
129		106
130	# process events as long as there are some:	107	# process events as long as there are some:
131	Event::loop;	108	EV::loop;
132		109
133	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
134		111
135	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
136	directly visible to Perl.	113	directly visible to Perl.
…		…
184		161
185	=cut	162	=cut
186		163
187	package IO::AIO;	164	package IO::AIO;
188		165
189	no warnings;	166	use Carp ();
190	use strict 'vars';	167
		168	use common::sense;
191		169
192	use base 'Exporter';	170	use base 'Exporter';
193		171
194	BEGIN {	172	BEGIN {
195	our $VERSION = '2.4';	173	our $VERSION = '4.0';
196		174
197	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
198	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
199	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync
		178	aio_fsync aio_syncfs aio_fdatasync aio_sync_file_range aio_fallocate
		179	aio_pathsync aio_readahead
		180	aio_rename aio_link aio_move aio_copy aio_group
200	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir	181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
201	aio_chown aio_chmod aio_utime);	182	aio_chmod aio_utime aio_truncate
		183	aio_msync aio_mtouch aio_mlock aio_mlockall
		184	aio_statvfs
		185	aio_wd);
		186
202	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));	187	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
203	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	188	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
204	min_parallel max_parallel max_idle	189	min_parallel max_parallel max_idle idle_timeout
205	nreqs nready npending nthreads	190	nreqs nready npending nthreads
206	max_poll_time max_poll_reqs);	191	max_poll_time max_poll_reqs
		192	sendfile fadvise madvise
		193	mmap munmap munlock munlockall);
		194
		195	push @AIO_REQ, qw(aio_busy); # not exported
207		196
208	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	197	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
209		198
210	require XSLoader;	199	require XSLoader;
211	XSLoader::load ("IO::AIO", $VERSION);	200	XSLoader::load ("IO::AIO", $VERSION);
212	}	201	}
213		202
214	=head1 FUNCTIONS	203	=head1 FUNCTIONS
		204
		205	=head2 QUICK OVERVIEW
		206
		207	This section simply lists the prototypes of the most important functions
		208	for quick reference. See the following sections for function-by-function
		209	documentation.
		210
		211	aio_wd $pathname, $callback->($wd)
		212	aio_open $pathname, $flags, $mode, $callback->($fh)
		213	aio_close $fh, $callback->($status)
		214	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		215	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		216	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		217	aio_readahead $fh,$offset,$length, $callback->($retval)
		218	aio_stat $fh_or_path, $callback->($status)
		219	aio_lstat $fh, $callback->($status)
		220	aio_statvfs $fh_or_path, $callback->($statvfs)
		221	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		222	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		223	aio_truncate $fh_or_path, $offset, $callback->($status)
		224	aio_chmod $fh_or_path, $mode, $callback->($status)
		225	aio_unlink $pathname, $callback->($status)
		226	aio_mknod $path, $mode, $dev, $callback->($status)
		227	aio_link $srcpath, $dstpath, $callback->($status)
		228	aio_symlink $srcpath, $dstpath, $callback->($status)
		229	aio_readlink $path, $callback->($link)
		230	aio_realpath $path, $callback->($link)
		231	aio_rename $srcpath, $dstpath, $callback->($status)
		232	aio_mkdir $pathname, $mode, $callback->($status)
		233	aio_rmdir $pathname, $callback->($status)
		234	aio_readdir $pathname, $callback->($entries)
		235	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		236	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		237	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		238	aio_load $path, $data, $callback->($status)
		239	aio_copy $srcpath, $dstpath, $callback->($status)
		240	aio_move $srcpath, $dstpath, $callback->($status)
		241	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		242	aio_rmtree $path, $callback->($status)
		243	aio_sync $callback->($status)
		244	aio_syncfs $fh, $callback->($status)
		245	aio_fsync $fh, $callback->($status)
		246	aio_fdatasync $fh, $callback->($status)
		247	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		248	aio_pathsync $path, $callback->($status)
		249	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		250	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		251	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		252	aio_mlockall $flags, $callback->($status)
		253	aio_group $callback->(...)
		254	aio_nop $callback->()
		255
		256	$prev_pri = aioreq_pri [$pri]
		257	aioreq_nice $pri_adjust
		258
		259	IO::AIO::poll_wait
		260	IO::AIO::poll_cb
		261	IO::AIO::poll
		262	IO::AIO::flush
		263	IO::AIO::max_poll_reqs $nreqs
		264	IO::AIO::max_poll_time $seconds
		265	IO::AIO::min_parallel $nthreads
		266	IO::AIO::max_parallel $nthreads
		267	IO::AIO::max_idle $nthreads
		268	IO::AIO::idle_timeout $seconds
		269	IO::AIO::max_outstanding $maxreqs
		270	IO::AIO::nreqs
		271	IO::AIO::nready
		272	IO::AIO::npending
		273
		274	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		275	IO::AIO::fadvise $fh, $offset, $len, $advice
		276	IO::AIO::madvise $scalar, $offset, $length, $advice
		277	IO::AIO::mprotect $scalar, $offset, $length, $protect
		278	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		279	IO::AIO::munlockall
215		280
216	=head2 AIO REQUEST FUNCTIONS	281	=head2 AIO REQUEST FUNCTIONS
217		282
218	All the C<aio_*> calls are more or less thin wrappers around the syscall	283	All the C<aio_*> calls are more or less thin wrappers around the syscall
219	with the same name (sans C<aio_>). The arguments are similar or identical,	284	with the same name (sans C<aio_>). The arguments are similar or identical,
220	and they all accept an additional (and optional) C<$callback> argument	285	and they all accept an additional (and optional) C<$callback> argument
221	which must be a code reference. This code reference will get called with	286	which must be a code reference. This code reference will get called with
222	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	287	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
223	perl, which usually delivers "false") as it's sole argument when the given	288	perl, which usually delivers "false") as its sole argument after the given
224	syscall has been executed asynchronously.	289	syscall has been executed asynchronously.
225		290
226	All functions expecting a filehandle keep a copy of the filehandle	291	All functions expecting a filehandle keep a copy of the filehandle
227	internally until the request has finished.	292	internally until the request has finished.
228		293
…		…
242	your pathnames to the locale (or other) encoding in effect in the user	307	your pathnames to the locale (or other) encoding in effect in the user
243	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	308	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
244	use something else to ensure your scalar has the correct contents.	309	use something else to ensure your scalar has the correct contents.
245		310
246	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	311	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
247	handles correctly wether it is set or not.	312	handles correctly whether it is set or not.
248		313
249	=over 4	314	=over 4
250		315
251	=item $prev_pri = aioreq_pri [$pri]	316	=item $prev_pri = aioreq_pri [$pri]
252		317
…		…
299	by the umask in effect then the request is being executed, so better never	364	by the umask in effect then the request is being executed, so better never
300	change the umask.	365	change the umask.
301		366
302	Example:	367	Example:
303		368
304	aio_open "/etc/passwd", O_RDONLY, 0, sub {	369	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
305	if ($_[0]) {	370	if ($_[0]) {
306	print "open successful, fh is $_[0]\n";	371	print "open successful, fh is $_[0]\n";
307	...	372	...
308	} else {	373	} else {
309	die "open failed: $!\n";	374	die "open failed: $!\n";
310	}	375	}
311	};	376	};
312		377
		378	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		379	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		380	following POSIX and non-POSIX constants are available (missing ones on
		381	your system are, as usual, C<0>):
		382
		383	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		384	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		385	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		386
313		387
314	=item aio_close $fh, $callback->($status)	388	=item aio_close $fh, $callback->($status)
315		389
316	Asynchronously close a file and call the callback with the result	390	Asynchronously close a file and call the callback with the result
317	code. I<WARNING:> although accepted, you should not pass in a perl	391	code.
318	filehandle here, as perl will likely close the file descriptor another
319	time when the filehandle is destroyed. Normally, you can safely call perls
320	C<close> or just let filehandles go out of scope.
321		392
322	This is supposed to be a bug in the API, so that might change. It's	393	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
323	therefore best to avoid this function.	394	closing the file descriptor associated with the filehandle itself.
324		395
		396	Therefore, C<aio_close> will not close the filehandle - instead it will
		397	use dup2 to overwrite the file descriptor with the write-end of a pipe
		398	(the pipe fd will be created on demand and will be cached).
		399
		400	Or in other words: the file descriptor will be closed, but it will not be
		401	free for reuse until the perl filehandle is closed.
		402
		403	=cut
325		404
326	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	405	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
327		406
328	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	407	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
329		408
330	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	409	Reads or writes C<$length> bytes from or to the specified C<$fh> and
331	into the scalar given by C<data> and offset C<dataoffset> and calls the	410	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
332	callback without the actual number of bytes read (or -1 on error, just	411	and calls the callback without the actual number of bytes read (or -1 on
333	like the syscall).	412	error, just like the syscall).
		413
		414	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		415	offset plus the actual number of bytes read.
		416
		417	If C<$offset> is undefined, then the current file descriptor offset will
		418	be used (and updated), otherwise the file descriptor offset will not be
		419	changed by these calls.
		420
		421	If C<$length> is undefined in C<aio_write>, use the remaining length of
		422	C<$data>.
		423
		424	If C<$dataoffset> is less than zero, it will be counted from the end of
		425	C<$data>.
334		426
335	The C<$data> scalar I<MUST NOT> be modified in any way while the request	427	The C<$data> scalar I<MUST NOT> be modified in any way while the request
336	is outstanding. Modifying it can result in segfaults or WW3 (if the	428	is outstanding. Modifying it can result in segfaults or World War III (if
337	necessary/optional hardware is installed).	429	the necessary/optional hardware is installed).
338		430
339	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	431	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
340	offset C<0> within the scalar:	432	offset C<0> within the scalar:
341		433
342	aio_read $fh, 7, 15, $buffer, 0, sub {	434	aio_read $fh, 7, 15, $buffer, 0, sub {
…		…
349		441
350	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	442	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
351	reading at byte offset C<$in_offset>, and starts writing at the current	443	reading at byte offset C<$in_offset>, and starts writing at the current
352	file offset of C<$out_fh>. Because of that, it is not safe to issue more	444	file offset of C<$out_fh>. Because of that, it is not safe to issue more
353	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	445	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
354	other.	446	other. The same C<$in_fh> works fine though, as this function does not
		447	move or use the file offset of C<$in_fh>.
355		448
		449	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		450	are written, and there is no way to find out how many more bytes have been
		451	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		452	number of bytes written to C<$out_fh>. Only if the result value equals
		453	C<$length> one can assume that C<$length> bytes have been read.
		454
		455	Unlike with other C<aio_> functions, it makes a lot of sense to use
		456	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		457	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		458	the socket I/O will be non-blocking. Note, however, that you can run
		459	into a trap where C<aio_sendfile> reads some data with readahead, then
		460	fails to write all data, and when the socket is ready the next time, the
		461	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		462	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		463	resource usage.
		464
356	This call tries to make use of a native C<sendfile> syscall to provide	465	This call tries to make use of a native C<sendfile>-like syscall to
357	zero-copy operation. For this to work, C<$out_fh> should refer to a	466	provide zero-copy operation. For this to work, C<$out_fh> should refer to
358	socket, and C<$in_fh> should refer to mmap'able file.	467	a socket, and C<$in_fh> should refer to an mmap'able file.
359		468
360	If the native sendfile call fails or is not implemented, it will be	469	If a native sendfile cannot be found or it fails with C<ENOSYS>,
361	emulated, so you can call C<aio_sendfile> on any type of filehandle	470	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		471	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
362	regardless of the limitations of the operating system.	472	type of filehandle regardless of the limitations of the operating system.
363		473
364	Please note, however, that C<aio_sendfile> can read more bytes from	474	As native sendfile syscalls (as practically any non-POSIX interface hacked
365	C<$in_fh> than are written, and there is no way to find out how many	475	together in a hurry to improve benchmark numbers) tend to be rather buggy
366	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	476	on many systems, this implementation tries to work around some known bugs
367	provides the number of bytes written to C<$out_fh>. Only if the result	477	in Linux and FreeBSD kernels (probably others, too), but that might fail,
368	value equals C<$length> one can assume that C<$length> bytes have been	478	so you really really should check the return value of C<aio_sendfile> -
369	read.	479	fewre bytes than expected might have been transferred.
370		480
371		481
372	=item aio_readahead $fh,$offset,$length, $callback->($retval)	482	=item aio_readahead $fh,$offset,$length, $callback->($retval)
373		483
374	C<aio_readahead> populates the page cache with data from a file so that	484	C<aio_readahead> populates the page cache with data from a file so that
…		…
397		507
398	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	508	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
399	error when stat'ing a large file, the results will be silently truncated	509	error when stat'ing a large file, the results will be silently truncated
400	unless perl itself is compiled with large file support.	510	unless perl itself is compiled with large file support.
401		511
		512	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		513	following constants and functions (if not implemented, the constants will
		514	be C<0> and the functions will either C<croak> or fall back on traditional
		515	behaviour).
		516
		517	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		518	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		519	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
		520
402	Example: Print the length of F</etc/passwd>:	521	Example: Print the length of F</etc/passwd>:
403		522
404	aio_stat "/etc/passwd", sub {	523	aio_stat "/etc/passwd", sub {
405	$_[0] and die "stat failed: $!";	524	$_[0] and die "stat failed: $!";
406	print "size is ", -s _, "\n";	525	print "size is ", -s _, "\n";
407	};	526	};
408		527
409		528
		529	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		530
		531	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		532	whether a file handle or path was passed.
		533
		534	On success, the callback is passed a hash reference with the following
		535	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		536	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		537	is passed.
		538
		539	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		540	C<ST_NOSUID>.
		541
		542	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		543	their correct value when available, or to C<0> on systems that do
		544	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		545	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		546	C<ST_NODIRATIME> and C<ST_RELATIME>.
		547
		548	Example: stat C</wd> and dump out the data if successful.
		549
		550	aio_statvfs "/wd", sub {
		551	my $f = $_[0]
		552	or die "statvfs: $!";
		553
		554	use Data::Dumper;
		555	say Dumper $f;
		556	};
		557
		558	# result:
		559	{
		560	bsize => 1024,
		561	bfree => 4333064312,
		562	blocks => 10253828096,
		563	files => 2050765568,
		564	flag => 4096,
		565	favail => 2042092649,
		566	bavail => 4333064312,
		567	ffree => 2042092649,
		568	namemax => 255,
		569	frsize => 1024,
		570	fsid => 1810
		571	}
		572
		573
410	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	574	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
411		575
412	Works like perl's C<utime> function (including the special case of $atime	576	Works like perl's C<utime> function (including the special case of $atime
413	and $mtime being undef). Fractional times are supported if the underlying	577	and $mtime being undef). Fractional times are supported if the underlying
414	syscalls support them.	578	syscalls support them.
…		…
436	aio_chown "path", 0, -1;	600	aio_chown "path", 0, -1;
437	# same as above:	601	# same as above:
438	aio_chown "path", 0, undef;	602	aio_chown "path", 0, undef;
439		603
440		604
		605	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		606
		607	Works like truncate(2) or ftruncate(2).
		608
		609
441	=item aio_chmod $fh_or_path, $mode, $callback->($status)	610	=item aio_chmod $fh_or_path, $mode, $callback->($status)
442		611
443	Works like perl's C<chmod> function.	612	Works like perl's C<chmod> function.
444		613
445		614
…		…
457		626
458	The only (POSIX-) portable way of calling this function is:	627	The only (POSIX-) portable way of calling this function is:
459		628
460	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	629	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
461		630
		631	See C<aio_stat> for info about some potentially helpful extra constants
		632	and functions.
462		633
463	=item aio_link $srcpath, $dstpath, $callback->($status)	634	=item aio_link $srcpath, $dstpath, $callback->($status)
464		635
465	Asynchronously create a new link to the existing object at C<$srcpath> at	636	Asynchronously create a new link to the existing object at C<$srcpath> at
466	the path C<$dstpath> and call the callback with the result code.	637	the path C<$dstpath> and call the callback with the result code.
…		…
477	Asynchronously read the symlink specified by C<$path> and pass it to	648	Asynchronously read the symlink specified by C<$path> and pass it to
478	the callback. If an error occurs, nothing or undef gets passed to the	649	the callback. If an error occurs, nothing or undef gets passed to the
479	callback.	650	callback.
480		651
481		652
		653	=item aio_realpath $path, $callback->($path)
		654
		655	Asynchronously make the path absolute and resolve any symlinks in
		656	C<$path>. The resulting path only consists of directories (Same as
		657	L<Cwd::realpath>).
		658
		659	This request can be used to get the absolute path of the current working
		660	directory by passing it a path of F<.> (a single dot).
		661
		662
482	=item aio_rename $srcpath, $dstpath, $callback->($status)	663	=item aio_rename $srcpath, $dstpath, $callback->($status)
483		664
484	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	665	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
485	rename(2) and call the callback with the result code.	666	rename(2) and call the callback with the result code.
486		667
…		…
502		683
503	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	684	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
504	directory (i.e. opendir + readdir + closedir). The entries will not be	685	directory (i.e. opendir + readdir + closedir). The entries will not be
505	sorted, and will B<NOT> include the C<.> and C<..> entries.	686	sorted, and will B<NOT> include the C<.> and C<..> entries.
506		687
507	The callback a single argument which is either C<undef> or an array-ref	688	The callback is passed a single argument which is either C<undef> or an
508	with the filenames.	689	array-ref with the filenames.
		690
		691
		692	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		693
		694	Quite similar to C<aio_readdir>, but the C<$flags> argument allows one to
		695	tune behaviour and output format. In case of an error, C<$entries> will be
		696	C<undef>.
		697
		698	The flags are a combination of the following constants, ORed together (the
		699	flags will also be passed to the callback, possibly modified):
		700
		701	=over 4
		702
		703	=item IO::AIO::READDIR_DENTS
		704
		705	When this flag is off, then the callback gets an arrayref consisting of
		706	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		707	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		708	entry in more detail.
		709
		710	C<$name> is the name of the entry.
		711
		712	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		713
		714	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		715	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		716	C<IO::AIO::DT_WHT>.
		717
		718	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		719	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		720	scalars are read-only: you can not modify them.
		721
		722	C<$inode> is the inode number (which might not be exact on systems with 64
		723	bit inode numbers and 32 bit perls). This field has unspecified content on
		724	systems that do not deliver the inode information.
		725
		726	=item IO::AIO::READDIR_DIRS_FIRST
		727
		728	When this flag is set, then the names will be returned in an order where
		729	likely directories come first, in optimal stat order. This is useful when
		730	you need to quickly find directories, or you want to find all directories
		731	while avoiding to stat() each entry.
		732
		733	If the system returns type information in readdir, then this is used
		734	to find directories directly. Otherwise, likely directories are names
		735	beginning with ".", or otherwise names with no dots, of which names with
		736	short names are tried first.
		737
		738	=item IO::AIO::READDIR_STAT_ORDER
		739
		740	When this flag is set, then the names will be returned in an order
		741	suitable for stat()'ing each one. That is, when you plan to stat()
		742	all files in the given directory, then the returned order will likely
		743	be fastest.
		744
		745	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		746	the likely dirs come first, resulting in a less optimal stat order.
		747
		748	=item IO::AIO::READDIR_FOUND_UNKNOWN
		749
		750	This flag should not be set when calling C<aio_readdirx>. Instead, it
		751	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		752	C<IO::AIO::DT_UNKNOWN>. The absence of this flag therefore indicates that all
		753	C<$type>'s are known, which can be used to speed up some algorithms.
		754
		755	=back
509		756
510		757
511	=item aio_load $path, $data, $callback->($status)	758	=item aio_load $path, $data, $callback->($status)
512		759
513	This is a composite request that tries to fully load the given file into	760	This is a composite request that tries to fully load the given file into
514	memory. Status is the same as with aio_read.	761	memory. Status is the same as with aio_read.
515		762
516	=cut	763	=cut
517		764
518	sub aio_load($$;$) {	765	sub aio_load($$;$) {
519	aio_block {
520	my ($path, undef, $cb) = @_;	766	my ($path, undef, $cb) = @_;
521	my $data = \$_[1];	767	my $data = \$_[1];
522		768
523	my $pri = aioreq_pri;	769	my $pri = aioreq_pri;
524	my $grp = aio_group $cb;	770	my $grp = aio_group $cb;
		771
		772	aioreq_pri $pri;
		773	add $grp aio_open $path, O_RDONLY, 0, sub {
		774	my $fh = shift
		775	or return $grp->result (-1);
525		776
526	aioreq_pri $pri;	777	aioreq_pri $pri;
527	add $grp aio_open $path, O_RDONLY, 0, sub {
528	my $fh = shift
529	or return $grp->result (-1);
530
531	aioreq_pri $pri;
532	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {	778	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
533	$grp->result ($_[0]);	779	$grp->result ($_[0]);
534	};
535	};	780	};
536
537	$grp
538	}	781	};
		782
		783	$grp
539	}	784	}
540		785
541	=item aio_copy $srcpath, $dstpath, $callback->($status)	786	=item aio_copy $srcpath, $dstpath, $callback->($status)
542		787
543	Try to copy the I<file> (directories not supported as either source or	788	Try to copy the I<file> (directories not supported as either source or
544	destination) from C<$srcpath> to C<$dstpath> and call the callback with	789	destination) from C<$srcpath> to C<$dstpath> and call the callback with
545	the C<0> (error) or C<-1> ok.	790	a status of C<0> (ok) or C<-1> (error, see C<$!>).
546		791
547	This is a composite request that it creates the destination file with	792	This is a composite request that creates the destination file with
548	mode 0200 and copies the contents of the source file into it using	793	mode 0200 and copies the contents of the source file into it using
549	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	794	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
550	uid/gid, in that order.	795	uid/gid, in that order.
551		796
552	If an error occurs, the partial destination file will be unlinked, if	797	If an error occurs, the partial destination file will be unlinked, if
…		…
554	errors are being ignored.	799	errors are being ignored.
555		800
556	=cut	801	=cut
557		802
558	sub aio_copy($$;$) {	803	sub aio_copy($$;$) {
559	aio_block {
560	my ($src, $dst, $cb) = @_;	804	my ($src, $dst, $cb) = @_;
561		805
562	my $pri = aioreq_pri;	806	my $pri = aioreq_pri;
563	my $grp = aio_group $cb;	807	my $grp = aio_group $cb;
564		808
565	aioreq_pri $pri;	809	aioreq_pri $pri;
566	add $grp aio_open $src, O_RDONLY, 0, sub {	810	add $grp aio_open $src, O_RDONLY, 0, sub {
567	if (my $src_fh = $_[0]) {	811	if (my $src_fh = $_[0]) {
568	my @stat = stat $src_fh;	812	my @stat = stat $src_fh; # hmm, might block over nfs?
569		813
570	aioreq_pri $pri;	814	aioreq_pri $pri;
571	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	815	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
572	if (my $dst_fh = $_[0]) {	816	if (my $dst_fh = $_[0]) {
573	aioreq_pri $pri;	817	aioreq_pri $pri;
574	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	818	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
575	if ($_[0] == $stat[7]) {	819	if ($_[0] == $stat[7]) {
576	$grp->result (0);	820	$grp->result (0);
577	close $src_fh;	821	close $src_fh;
578		822
579	# those should not normally block. should. should.
580	utime $stat[8], $stat[9], $dst;
581	chmod $stat[2] & 07777, $dst_fh;
582	chown $stat[4], $stat[5], $dst_fh;
583	close $dst_fh;
584	} else {	823	my $ch = sub {
585	$grp->result (-1);
586	close $src_fh;
587	close $dst_fh;
588
589	aioreq $pri;	824	aioreq_pri $pri;
		825	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		826	aioreq_pri $pri;
		827	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		828	aioreq_pri $pri;
590	add $grp aio_unlink $dst;	829	add $grp aio_close $dst_fh;
		830	}
		831	};
591	}	832	};
		833
		834	aioreq_pri $pri;
		835	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		836	if ($_[0] < 0 && $! == ENOSYS) {
		837	aioreq_pri $pri;
		838	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		839	} else {
		840	$ch->();
		841	}
		842	};
		843	} else {
		844	$grp->result (-1);
		845	close $src_fh;
		846	close $dst_fh;
		847
		848	aioreq $pri;
		849	add $grp aio_unlink $dst;
592	};	850	}
593	} else {
594	$grp->result (-1);
595	}	851	};
		852	} else {
		853	$grp->result (-1);
596	},	854	}
597
598	} else {
599	$grp->result (-1);
600	}	855	},
		856
		857	} else {
		858	$grp->result (-1);
601	};	859	}
602
603	$grp
604	}	860	};
		861
		862	$grp
605	}	863	}
606		864
607	=item aio_move $srcpath, $dstpath, $callback->($status)	865	=item aio_move $srcpath, $dstpath, $callback->($status)
608		866
609	Try to move the I<file> (directories not supported as either source or	867	Try to move the I<file> (directories not supported as either source or
610	destination) from C<$srcpath> to C<$dstpath> and call the callback with	868	destination) from C<$srcpath> to C<$dstpath> and call the callback with
611	the C<0> (error) or C<-1> ok.	869	a status of C<0> (ok) or C<-1> (error, see C<$!>).
612		870
613	This is a composite request that tries to rename(2) the file first. If	871	This is a composite request that tries to rename(2) the file first; if
614	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	872	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
615	that is successful, unlinking the C<$srcpath>.	873	that is successful, unlinks the C<$srcpath>.
616		874
617	=cut	875	=cut
618		876
619	sub aio_move($$;$) {	877	sub aio_move($$;$) {
620	aio_block {
621	my ($src, $dst, $cb) = @_;	878	my ($src, $dst, $cb) = @_;
622		879
623	my $pri = aioreq_pri;	880	my $pri = aioreq_pri;
624	my $grp = aio_group $cb;	881	my $grp = aio_group $cb;
625		882
626	aioreq_pri $pri;	883	aioreq_pri $pri;
627	add $grp aio_rename $src, $dst, sub {	884	add $grp aio_rename $src, $dst, sub {
628	if ($_[0] && $! == EXDEV) {	885	if ($_[0] && $! == EXDEV) {
629	aioreq_pri $pri;	886	aioreq_pri $pri;
630	add $grp aio_copy $src, $dst, sub {	887	add $grp aio_copy $src, $dst, sub {
631	$grp->result ($_[0]);
632
633	if (!$_[0]) {
634	aioreq_pri $pri;
635	add $grp aio_unlink $src;
636	}
637	};
638	} else {
639	$grp->result ($_[0]);	888	$grp->result ($_[0]);
		889
		890	unless ($_[0]) {
		891	aioreq_pri $pri;
		892	add $grp aio_unlink $src;
		893	}
640	}	894	};
		895	} else {
		896	$grp->result ($_[0]);
641	};	897	}
642
643	$grp
644	}	898	};
		899
		900	$grp
645	}	901	}
646		902
647	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	903	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
648		904
649	Scans a directory (similar to C<aio_readdir>) but additionally tries to	905	Scans a directory (similar to C<aio_readdir>) but additionally tries to
…		…
669		925
670	Implementation notes.	926	Implementation notes.
671		927
672	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	928	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
673		929
		930	If readdir returns file type information, then this is used directly to
		931	find directories.
		932
674	After reading the directory, the modification time, size etc. of the	933	Otherwise, after reading the directory, the modification time, size etc.
675	directory before and after the readdir is checked, and if they match (and	934	of the directory before and after the readdir is checked, and if they
676	isn't the current time), the link count will be used to decide how many	935	match (and isn't the current time), the link count will be used to decide
677	entries are directories (if >= 2). Otherwise, no knowledge of the number	936	how many entries are directories (if >= 2). Otherwise, no knowledge of the
678	of subdirectories will be assumed.	937	number of subdirectories will be assumed.
679		938
680	Then entries will be sorted into likely directories (everything without	939	Then entries will be sorted into likely directories a non-initial dot
681	a non-initial dot currently) and likely non-directories (everything	940	currently) and likely non-directories (see C<aio_readdirx>). Then every
682	else). Then every entry plus an appended C</.> will be C<stat>'ed,	941	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
683	likely directories first. If that succeeds, it assumes that the entry	942	in order of their inode numbers. If that succeeds, it assumes that the
684	is a directory or a symlink to directory (which will be checked	943	entry is a directory or a symlink to directory (which will be checked
685	seperately). This is often faster than stat'ing the entry itself because	944	separately). This is often faster than stat'ing the entry itself because
686	filesystems might detect the type of the entry without reading the inode	945	filesystems might detect the type of the entry without reading the inode
687	data (e.g. ext2fs filetype feature).	946	data (e.g. ext2fs filetype feature), even on systems that cannot return
		947	the filetype information on readdir.
688		948
689	If the known number of directories (link count - 2) has been reached, the	949	If the known number of directories (link count - 2) has been reached, the
690	rest of the entries is assumed to be non-directories.	950	rest of the entries is assumed to be non-directories.
691		951
692	This only works with certainty on POSIX (= UNIX) filesystems, which	952	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
697	directory counting heuristic.	957	directory counting heuristic.
698		958
699	=cut	959	=cut
700		960
701	sub aio_scandir($$;$) {	961	sub aio_scandir($$;$) {
702	aio_block {
703	my ($path, $maxreq, $cb) = @_;	962	my ($path, $maxreq, $cb) = @_;
704		963
705	my $pri = aioreq_pri;	964	my $pri = aioreq_pri;
706		965
707	my $grp = aio_group $cb;	966	my $grp = aio_group $cb;
708		967
709	$maxreq = 4 if $maxreq <= 0;	968	$maxreq = 4 if $maxreq <= 0;
710		969
711	# stat once	970	# stat once
		971	aioreq_pri $pri;
		972	add $grp aio_stat $path, sub {
		973	return $grp->result () if $_[0];
		974	my $now = time;
		975	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		976
		977	# read the directory entries
712	aioreq_pri $pri;	978	aioreq_pri $pri;
713	add $grp aio_stat $path, sub {	979	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
		980	my $entries = shift
714	return $grp->result () if $_[0];	981	or return $grp->result ();
715	my $now = time;
716	my $hash1 = join ":", (stat _)[0,1,3,7,9];
717		982
718	# read the directory entries	983	# stat the dir another time
719	aioreq_pri $pri;	984	aioreq_pri $pri;
720	add $grp aio_readdir $path, sub {
721	my $entries = shift
722	or return $grp->result ();
723
724	# stat the dir another time
725	aioreq_pri $pri;
726	add $grp aio_stat $path, sub {	985	add $grp aio_stat $path, sub {
727	my $hash2 = join ":", (stat _)[0,1,3,7,9];	986	my $hash2 = join ":", (stat _)[0,1,3,7,9];
728		987
729	my $ndirs;	988	my $ndirs;
730		989
731	# take the slow route if anything looks fishy	990	# take the slow route if anything looks fishy
732	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	991	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
733	$ndirs = -1;	992	$ndirs = -1;
734	} else {	993	} else {
735	# if nlink == 2, we are finished	994	# if nlink == 2, we are finished
736	# on non-posix-fs's, we rely on nlink < 2	995	# for non-posix-fs's, we rely on nlink < 2
737	$ndirs = (stat _)[3] - 2	996	$ndirs = (stat _)[3] - 2
738	or return $grp->result ([], $entries);	997	or return $grp->result ([], $entries);
739	}	998	}
740		999
741	# sort into likely dirs and likely nondirs
742	# dirs == files without ".", short entries first
743	$entries = [map $_->[0],
744	sort { $b->[1] cmp $a->[1] }
745	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
746	@$entries];
747
748	my (@dirs, @nondirs);	1000	my (@dirs, @nondirs);
749		1001
750	my $statgrp = add $grp aio_group sub {	1002	my $statgrp = add $grp aio_group sub {
751	$grp->result (\@dirs, \@nondirs);	1003	$grp->result (\@dirs, \@nondirs);
752	};	1004	};
753		1005
754	limit $statgrp $maxreq;	1006	limit $statgrp $maxreq;
755	feed $statgrp sub {	1007	feed $statgrp sub {
756	return unless @$entries;	1008	return unless @$entries;
757	my $entry = pop @$entries;	1009	my $entry = shift @$entries;
758		1010
759	aioreq_pri $pri;	1011	aioreq_pri $pri;
760	add $statgrp aio_stat "$path/$entry/.", sub {	1012	add $statgrp aio_stat "$path/$entry/.", sub {
761	if ($_[0] < 0) {	1013	if ($_[0] < 0) {
762	push @nondirs, $entry;	1014	push @nondirs, $entry;
763	} else {	1015	} else {
764	# need to check for real directory	1016	# need to check for real directory
765	aioreq_pri $pri;	1017	aioreq_pri $pri;
766	add $statgrp aio_lstat "$path/$entry", sub {	1018	add $statgrp aio_lstat "$path/$entry", sub {
767	if (-d _) {	1019	if (-d _) {
768	push @dirs, $entry;	1020	push @dirs, $entry;
769		1021
770	unless (--$ndirs) {	1022	unless (--$ndirs) {
771	push @nondirs, @$entries;	1023	push @nondirs, @$entries;
772	feed $statgrp;	1024	feed $statgrp;
773	}
774	} else {
775	push @nondirs, $entry;
776	}	1025	}
		1026	} else {
		1027	push @nondirs, $entry;
777	}	1028	}
778	}	1029	}
779	};	1030	}
780	};	1031	};
781	};	1032	};
782	};	1033	};
783	};	1034	};
784
785	$grp
786	}	1035	};
		1036
		1037	$grp
787	}	1038	}
788		1039
789	=item aio_rmtree $path, $callback->($status)	1040	=item aio_rmtree $path, $callback->($status)
790		1041
791	Delete a directory tree starting (and including) C<$path>, return the	1042	Delete a directory tree starting (and including) C<$path>, return the
…		…
795		1046
796	=cut	1047	=cut
797		1048
798	sub aio_rmtree;	1049	sub aio_rmtree;
799	sub aio_rmtree($;$) {	1050	sub aio_rmtree($;$) {
800	aio_block {
801	my ($path, $cb) = @_;	1051	my ($path, $cb) = @_;
802		1052
803	my $pri = aioreq_pri;	1053	my $pri = aioreq_pri;
804	my $grp = aio_group $cb;	1054	my $grp = aio_group $cb;
805		1055
806	aioreq_pri $pri;	1056	aioreq_pri $pri;
807	add $grp aio_scandir $path, 0, sub {	1057	add $grp aio_scandir $path, 0, sub {
808	my ($dirs, $nondirs) = @_;	1058	my ($dirs, $nondirs) = @_;
809		1059
810	my $dirgrp = aio_group sub {	1060	my $dirgrp = aio_group sub {
811	add $grp aio_rmdir $path, sub {	1061	add $grp aio_rmdir $path, sub {
812	$grp->result ($_[0]);	1062	$grp->result ($_[0]);
813	};
814	};	1063	};
815
816	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
817	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
818
819	add $grp $dirgrp;
820	};	1064	};
821		1065
822	$grp	1066	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1067	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1068
		1069	add $grp $dirgrp;
823	}	1070	};
		1071
		1072	$grp
824	}	1073	}
		1074
		1075	=item aio_sync $callback->($status)
		1076
		1077	Asynchronously call sync and call the callback when finished.
825		1078
826	=item aio_fsync $fh, $callback->($status)	1079	=item aio_fsync $fh, $callback->($status)
827		1080
828	Asynchronously call fsync on the given filehandle and call the callback	1081	Asynchronously call fsync on the given filehandle and call the callback
829	with the fsync result code.	1082	with the fsync result code.
…		…
833	Asynchronously call fdatasync on the given filehandle and call the	1086	Asynchronously call fdatasync on the given filehandle and call the
834	callback with the fdatasync result code.	1087	callback with the fdatasync result code.
835		1088
836	If this call isn't available because your OS lacks it or it couldn't be	1089	If this call isn't available because your OS lacks it or it couldn't be
837	detected, it will be emulated by calling C<fsync> instead.	1090	detected, it will be emulated by calling C<fsync> instead.
		1091
		1092	=item aio_syncfs $fh, $callback->($status)
		1093
		1094	Asynchronously call the syncfs syscall to sync the filesystem associated
		1095	to the given filehandle and call the callback with the syncfs result
		1096	code. If syncfs is not available, calls sync(), but returns C<-1> and sets
		1097	errno to C<ENOSYS> nevertheless.
		1098
		1099	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1100
		1101	Sync the data portion of the file specified by C<$offset> and C<$length>
		1102	to disk (but NOT the metadata), by calling the Linux-specific
		1103	sync_file_range call. If sync_file_range is not available or it returns
		1104	ENOSYS, then fdatasync or fsync is being substituted.
		1105
		1106	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1107	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1108	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1109	manpage for details.
		1110
		1111	=item aio_pathsync $path, $callback->($status)
		1112
		1113	This request tries to open, fsync and close the given path. This is a
		1114	composite request intended to sync directories after directory operations
		1115	(E.g. rename). This might not work on all operating systems or have any
		1116	specific effect, but usually it makes sure that directory changes get
		1117	written to disc. It works for anything that can be opened for read-only,
		1118	not just directories.
		1119
		1120	Future versions of this function might fall back to other methods when
		1121	C<fsync> on the directory fails (such as calling C<sync>).
		1122
		1123	Passes C<0> when everything went ok, and C<-1> on error.
		1124
		1125	=cut
		1126
		1127	sub aio_pathsync($;$) {
		1128	my ($path, $cb) = @_;
		1129
		1130	my $pri = aioreq_pri;
		1131	my $grp = aio_group $cb;
		1132
		1133	aioreq_pri $pri;
		1134	add $grp aio_open $path, O_RDONLY, 0, sub {
		1135	my ($fh) = @_;
		1136	if ($fh) {
		1137	aioreq_pri $pri;
		1138	add $grp aio_fsync $fh, sub {
		1139	$grp->result ($_[0]);
		1140
		1141	aioreq_pri $pri;
		1142	add $grp aio_close $fh;
		1143	};
		1144	} else {
		1145	$grp->result (-1);
		1146	}
		1147	};
		1148
		1149	$grp
		1150	}
		1151
		1152	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1153
		1154	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1155	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1156	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1157	scalar must only be modified in-place while an aio operation is pending on
		1158	it).
		1159
		1160	It calls the C<msync> function of your OS, if available, with the memory
		1161	area starting at C<$offset> in the string and ending C<$length> bytes
		1162	later. If C<$length> is negative, counts from the end, and if C<$length>
		1163	is C<undef>, then it goes till the end of the string. The flags can be
		1164	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1165	C<IO::AIO::MS_SYNC>.
		1166
		1167	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1168
		1169	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1170	scalars.
		1171
		1172	It touches (reads or writes) all memory pages in the specified
		1173	range inside the scalar. All caveats and parameters are the same
		1174	as for C<aio_msync>, above, except for flags, which must be either
		1175	C<0> (which reads all pages and ensures they are instantiated) or
		1176	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1177	writing an octet from it, which dirties the page).
		1178
		1179	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1180
		1181	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1182	scalars.
		1183
		1184	It reads in all the pages of the underlying storage into memory (if any)
		1185	and locks them, so they are not getting swapped/paged out or removed.
		1186
		1187	If C<$length> is undefined, then the scalar will be locked till the end.
		1188
		1189	On systems that do not implement C<mlock>, this function returns C<-1>
		1190	and sets errno to C<ENOSYS>.
		1191
		1192	Note that the corresponding C<munlock> is synchronous and is
		1193	documented under L<MISCELLANEOUS FUNCTIONS>.
		1194
		1195	Example: open a file, mmap and mlock it - both will be undone when
		1196	C<$data> gets destroyed.
		1197
		1198	open my $fh, "<", $path or die "$path: $!";
		1199	my $data;
		1200	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1201	aio_mlock $data; # mlock in background
		1202
		1203	=item aio_mlockall $flags, $callback->($status)
		1204
		1205	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1206	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1207
		1208	On systems that do not implement C<mlockall>, this function returns C<-1>
		1209	and sets errno to C<ENOSYS>.
		1210
		1211	Note that the corresponding C<munlockall> is synchronous and is
		1212	documented under L<MISCELLANEOUS FUNCTIONS>.
		1213
		1214	Example: asynchronously lock all current and future pages into memory.
		1215
		1216	aio_mlockall IO::AIO::MCL_FUTURE;
838		1217
839	=item aio_group $callback->(...)	1218	=item aio_group $callback->(...)
840		1219
841	This is a very special aio request: Instead of doing something, it is a	1220	This is a very special aio request: Instead of doing something, it is a
842	container for other aio requests, which is useful if you want to bundle	1221	container for other aio requests, which is useful if you want to bundle
…		…
892	=item cancel $req	1271	=item cancel $req
893		1272
894	Cancels the request, if possible. Has the effect of skipping execution	1273	Cancels the request, if possible. Has the effect of skipping execution
895	when entering the B<execute> state and skipping calling the callback when	1274	when entering the B<execute> state and skipping calling the callback when
896	entering the the B<result> state, but will leave the request otherwise	1275	entering the the B<result> state, but will leave the request otherwise
897	untouched. That means that requests that currently execute will not be	1276	untouched (with the exception of readdir). That means that requests that
898	stopped and resources held by the request will not be freed prematurely.	1277	currently execute will not be stopped and resources held by the request
		1278	will not be freed prematurely.
899		1279
900	=item cb $req $callback->(...)	1280	=item cb $req $callback->(...)
901		1281
902	Replace (or simply set) the callback registered to the request.	1282	Replace (or simply set) the callback registered to the request.
903		1283
…		…
954	Their lifetime, simplified, looks like this: when they are empty, they	1334	Their lifetime, simplified, looks like this: when they are empty, they
955	will finish very quickly. If they contain only requests that are in the	1335	will finish very quickly. If they contain only requests that are in the
956	C<done> state, they will also finish. Otherwise they will continue to	1336	C<done> state, they will also finish. Otherwise they will continue to
957	exist.	1337	exist.
958		1338
959	That means after creating a group you have some time to add requests. And	1339	That means after creating a group you have some time to add requests
960	in the callbacks of those requests, you can add further requests to the	1340	(precisely before the callback has been invoked, which is only done within
961	group. And only when all those requests have finished will the the group	1341	the C<poll_cb>). And in the callbacks of those requests, you can add
962	itself finish.	1342	further requests to the group. And only when all those requests have
		1343	finished will the the group itself finish.
963		1344
964	=over 4	1345	=over 4
965		1346
966	=item add $grp ...	1347	=item add $grp ...
967		1348
…		…
976	=item $grp->cancel_subs	1357	=item $grp->cancel_subs
977		1358
978	Cancel all subrequests and clears any feeder, but not the group request	1359	Cancel all subrequests and clears any feeder, but not the group request
979	itself. Useful when you queued a lot of events but got a result early.	1360	itself. Useful when you queued a lot of events but got a result early.
980		1361
		1362	The group request will finish normally (you cannot add requests to the
		1363	group).
		1364
981	=item $grp->result (...)	1365	=item $grp->result (...)
982		1366
983	Set the result value(s) that will be passed to the group callback when all	1367	Set the result value(s) that will be passed to the group callback when all
984	subrequests have finished and set thre groups errno to the current value	1368	subrequests have finished and set the groups errno to the current value
985	of errno (just like calling C<errno> without an error number). By default,	1369	of errno (just like calling C<errno> without an error number). By default,
986	no argument will be passed and errno is zero.	1370	no argument will be passed and errno is zero.
987		1371
988	=item $grp->errno ([$errno])	1372	=item $grp->errno ([$errno])
989		1373
…		…
1000	=item feed $grp $callback->($grp)	1384	=item feed $grp $callback->($grp)
1001		1385
1002	Sets a feeder/generator on this group: every group can have an attached	1386	Sets a feeder/generator on this group: every group can have an attached
1003	generator that generates requests if idle. The idea behind this is that,	1387	generator that generates requests if idle. The idea behind this is that,
1004	although you could just queue as many requests as you want in a group,	1388	although you could just queue as many requests as you want in a group,
1005	this might starve other requests for a potentially long time. For	1389	this might starve other requests for a potentially long time. For example,
1006	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1390	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
1007	requests, delaying any later requests for a long time.	1391	delaying any later requests for a long time.
1008		1392
1009	To avoid this, and allow incremental generation of requests, you can	1393	To avoid this, and allow incremental generation of requests, you can
1010	instead a group and set a feeder on it that generates those requests. The	1394	instead a group and set a feeder on it that generates those requests. The
1011	feed callback will be called whenever there are few enough (see C<limit>,	1395	feed callback will be called whenever there are few enough (see C<limit>,
1012	below) requests active in the group itself and is expected to queue more	1396	below) requests active in the group itself and is expected to queue more
…		…
1016	not impose any limits).	1400	not impose any limits).
1017		1401
1018	If the feed does not queue more requests when called, it will be	1402	If the feed does not queue more requests when called, it will be
1019	automatically removed from the group.	1403	automatically removed from the group.
1020		1404
1021	If the feed limit is C<0>, it will be set to C<2> automatically.	1405	If the feed limit is C<0> when this method is called, it will be set to
		1406	C<2> automatically.
1022		1407
1023	Example:	1408	Example:
1024		1409
1025	# stat all files in @files, but only ever use four aio requests concurrently:	1410	# stat all files in @files, but only ever use four aio requests concurrently:
1026		1411
…		…
1038	Sets the feeder limit for the group: The feeder will be called whenever	1423	Sets the feeder limit for the group: The feeder will be called whenever
1039	the group contains less than this many requests.	1424	the group contains less than this many requests.
1040		1425
1041	Setting the limit to C<0> will pause the feeding process.	1426	Setting the limit to C<0> will pause the feeding process.
1042		1427
		1428	The default value for the limit is C<0>, but note that setting a feeder
		1429	automatically bumps it up to C<2>.
		1430
1043	=back	1431	=back
1044		1432
1045	=head2 SUPPORT FUNCTIONS	1433	=head2 SUPPORT FUNCTIONS
1046		1434
1047	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1435	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
…		…
1049	=over 4	1437	=over 4
1050		1438
1051	=item $fileno = IO::AIO::poll_fileno	1439	=item $fileno = IO::AIO::poll_fileno
1052		1440
1053	Return the I<request result pipe file descriptor>. This filehandle must be	1441	Return the I<request result pipe file descriptor>. This filehandle must be
1054	polled for reading by some mechanism outside this module (e.g. Event or	1442	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1055	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1443	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1056	to call C<poll_cb> to check the results.	1444	you have to call C<poll_cb> to check the results.
1057		1445
1058	See C<poll_cb> for an example.	1446	See C<poll_cb> for an example.
1059		1447
1060	=item IO::AIO::poll_cb	1448	=item IO::AIO::poll_cb
1061		1449
1062	Process some outstanding events on the result pipe. You have to call this	1450	Process some outstanding events on the result pipe. You have to call
1063	regularly. Returns the number of events processed. Returns immediately	1451	this regularly. Returns C<0> if all events could be processed (or there
1064	when no events are outstanding. The amount of events processed depends on	1452	were no events to process), or C<-1> if it returned earlier for whatever
1065	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1453	reason. Returns immediately when no events are outstanding. The amount of
		1454	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1455	C<IO::AIO::max_poll_time>.
1066		1456
1067	If not all requests were processed for whatever reason, the filehandle	1457	If not all requests were processed for whatever reason, the filehandle
1068	will still be ready when C<poll_cb> returns.	1458	will still be ready when C<poll_cb> returns, so normally you don't have to
		1459	do anything special to have it called later.
		1460
		1461	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1462	ready, it can be beneficial to call this function from loops which submit
		1463	a lot of requests, to make sure the results get processed when they become
		1464	available and not just when the loop is finished and the event loop takes
		1465	over again. This function returns very fast when there are no outstanding
		1466	requests.
1069		1467
1070	Example: Install an Event watcher that automatically calls	1468	Example: Install an Event watcher that automatically calls
1071	IO::AIO::poll_cb with high priority:	1469	IO::AIO::poll_cb with high priority (more examples can be found in the
		1470	SYNOPSIS section, at the top of this document):
1072		1471
1073	Event->io (fd => IO::AIO::poll_fileno,	1472	Event->io (fd => IO::AIO::poll_fileno,
1074	poll => 'r', async => 1,	1473	poll => 'r', async => 1,
1075	cb => \&IO::AIO::poll_cb);	1474	cb => \&IO::AIO::poll_cb);
		1475
		1476	=item IO::AIO::poll_wait
		1477
		1478	If there are any outstanding requests and none of them in the result
		1479	phase, wait till the result filehandle becomes ready for reading (simply
		1480	does a C<select> on the filehandle. This is useful if you want to
		1481	synchronously wait for some requests to finish).
		1482
		1483	See C<nreqs> for an example.
		1484
		1485	=item IO::AIO::poll
		1486
		1487	Waits until some requests have been handled.
		1488
		1489	Returns the number of requests processed, but is otherwise strictly
		1490	equivalent to:
		1491
		1492	IO::AIO::poll_wait, IO::AIO::poll_cb
		1493
		1494	=item IO::AIO::flush
		1495
		1496	Wait till all outstanding AIO requests have been handled.
		1497
		1498	Strictly equivalent to:
		1499
		1500	IO::AIO::poll_wait, IO::AIO::poll_cb
		1501	while IO::AIO::nreqs;
1076		1502
1077	=item IO::AIO::max_poll_reqs $nreqs	1503	=item IO::AIO::max_poll_reqs $nreqs
1078		1504
1079	=item IO::AIO::max_poll_time $seconds	1505	=item IO::AIO::max_poll_time $seconds
1080		1506
…		…
1105	# use a low priority so other tasks have priority	1531	# use a low priority so other tasks have priority
1106	Event->io (fd => IO::AIO::poll_fileno,	1532	Event->io (fd => IO::AIO::poll_fileno,
1107	poll => 'r', nice => 1,	1533	poll => 'r', nice => 1,
1108	cb => &IO::AIO::poll_cb);	1534	cb => &IO::AIO::poll_cb);
1109		1535
1110	=item IO::AIO::poll_wait
1111
1112	If there are any outstanding requests and none of them in the result
1113	phase, wait till the result filehandle becomes ready for reading (simply
1114	does a C<select> on the filehandle. This is useful if you want to
1115	synchronously wait for some requests to finish).
1116
1117	See C<nreqs> for an example.
1118
1119	=item IO::AIO::poll
1120
1121	Waits until some requests have been handled.
1122
1123	Returns the number of requests processed, but is otherwise strictly
1124	equivalent to:
1125
1126	IO::AIO::poll_wait, IO::AIO::poll_cb
1127
1128	=item IO::AIO::flush
1129
1130	Wait till all outstanding AIO requests have been handled.
1131
1132	Strictly equivalent to:
1133
1134	IO::AIO::poll_wait, IO::AIO::poll_cb
1135	while IO::AIO::nreqs;
1136
1137	=back	1536	=back
1138		1537
1139	=head3 CONTROLLING THE NUMBER OF THREADS	1538	=head3 CONTROLLING THE NUMBER OF THREADS
1140		1539
1141	=over	1540	=over
…		…
1174		1573
1175	Under normal circumstances you don't need to call this function.	1574	Under normal circumstances you don't need to call this function.
1176		1575
1177	=item IO::AIO::max_idle $nthreads	1576	=item IO::AIO::max_idle $nthreads
1178		1577
1179	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1578	Limit the number of threads (default: 4) that are allowed to idle
1180	threads that did not get a request to process within 10 seconds). That	1579	(i.e., threads that did not get a request to process within the idle
1181	means if a thread becomes idle while C<$nthreads> other threads are also	1580	timeout (default: 10 seconds). That means if a thread becomes idle while
1182	idle, it will free its resources and exit.	1581	C<$nthreads> other threads are also idle, it will free its resources and
		1582	exit.
1183		1583
1184	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1584	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1185	to allow for extremely high load situations, but want to free resources	1585	to allow for extremely high load situations, but want to free resources
1186	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1586	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1187		1587
1188	The default is probably ok in most situations, especially if thread	1588	The default is probably ok in most situations, especially if thread
1189	creation is fast. If thread creation is very slow on your system you might	1589	creation is fast. If thread creation is very slow on your system you might
1190	want to use larger values.	1590	want to use larger values.
1191		1591
		1592	=item IO::AIO::idle_timeout $seconds
		1593
		1594	Sets the minimum idle timeout (default 10) after which worker threads are
		1595	allowed to exit. SEe C<IO::AIO::max_idle>.
		1596
1192	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1597	=item IO::AIO::max_outstanding $maxreqs
		1598
		1599	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1600	you do queue up more than this number of requests, the next call to
		1601	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1602	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1603	longer exceeded.
		1604
		1605	In other words, this setting does not enforce a queue limit, but can be
		1606	used to make poll functions block if the limit is exceeded.
1193		1607
1194	This is a very bad function to use in interactive programs because it	1608	This is a very bad function to use in interactive programs because it
1195	blocks, and a bad way to reduce concurrency because it is inexact: Better	1609	blocks, and a bad way to reduce concurrency because it is inexact: Better
1196	use an C<aio_group> together with a feed callback.	1610	use an C<aio_group> together with a feed callback.
1197		1611
1198	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1612	It's main use is in scripts without an event loop - when you want to stat
1199	to queue up more than this number of requests, the next call to the	1613	a lot of files, you can write somehting like this:
1200	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1201	function will block until the limit is no longer exceeded.
1202		1614
1203	The default value is very large, so there is no practical limit on the	1615	IO::AIO::max_outstanding 32;
1204	number of outstanding requests.
1205		1616
1206	You can still queue as many requests as you want. Therefore,	1617	for my $path (...) {
1207	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1618	aio_stat $path , ...;
1208	as a stop gap to shield against fatal memory overflow (with large values).	1619	IO::AIO::poll_cb;
		1620	}
		1621
		1622	IO::AIO::flush;
		1623
		1624	The call to C<poll_cb> inside the loop will normally return instantly, but
		1625	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1626	some requests have been handled. This keeps the loop from pushing a large
		1627	number of C<aio_stat> requests onto the queue.
		1628
		1629	The default value for C<max_outstanding> is very large, so there is no
		1630	practical limit on the number of outstanding requests.
1209		1631
1210	=back	1632	=back
1211		1633
1212	=head3 STATISTICAL INFORMATION	1634	=head3 STATISTICAL INFORMATION
1213		1635
…		…
1233	Returns the number of requests currently in the pending state (executed,	1655	Returns the number of requests currently in the pending state (executed,
1234	but not yet processed by poll_cb).	1656	but not yet processed by poll_cb).
1235		1657
1236	=back	1658	=back
1237		1659
		1660	=head3 MISCELLANEOUS FUNCTIONS
		1661
		1662	IO::AIO implements some functions that might be useful, but are not
		1663	asynchronous.
		1664
		1665	=over 4
		1666
		1667	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1668
		1669	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1670	but is blocking (this makes most sense if you know the input data is
		1671	likely cached already and the output filehandle is set to non-blocking
		1672	operations).
		1673
		1674	Returns the number of bytes copied, or C<-1> on error.
		1675
		1676	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1677
		1678	Simply calls the C<posix_fadvise> function (see its
		1679	manpage for details). The following advice constants are
		1680	available: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1681	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1682	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1683
		1684	On systems that do not implement C<posix_fadvise>, this function returns
		1685	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1686
		1687	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1688
		1689	Simply calls the C<posix_madvise> function (see its
		1690	manpage for details). The following advice constants are
		1691	available: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1692	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1693
		1694	On systems that do not implement C<posix_madvise>, this function returns
		1695	ENOSYS, otherwise the return value of C<posix_madvise>.
		1696
		1697	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1698
		1699	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1700	$scalar (see its manpage for details). The following protect
		1701	constants are available: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1702	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1703
		1704	On systems that do not implement C<mprotect>, this function returns
		1705	ENOSYS, otherwise the return value of C<mprotect>.
		1706
		1707	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1708
		1709	Memory-maps a file (or anonymous memory range) and attaches it to the
		1710	given C<$scalar>, which will act like a string scalar.
		1711
		1712	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1713	change the string length, and most read-only operations such as copying it
		1714	or searching it with regexes and so on.
		1715
		1716	Anything else is unsafe and will, at best, result in memory leaks.
		1717
		1718	The memory map associated with the C<$scalar> is automatically removed
		1719	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1720	C<IO::AIO::munmap> functions are called.
		1721
		1722	This calls the C<mmap>(2) function internally. See your system's manual
		1723	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1724
		1725	The C<$length> must be larger than zero and smaller than the actual
		1726	filesize.
		1727
		1728	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1729	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1730
		1731	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1732	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1733	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1734	(which is set to C<MAP_ANON> if your system only provides this
		1735	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1736	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1737	C<IO::AIO::MAP_NONBLOCK>
		1738
		1739	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1740
		1741	C<$offset> is the offset from the start of the file - it generally must be
		1742	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1743
		1744	Example:
		1745
		1746	use Digest::MD5;
		1747	use IO::AIO;
		1748
		1749	open my $fh, "<verybigfile"
		1750	or die "$!";
		1751
		1752	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1753	or die "verybigfile: $!";
		1754
		1755	my $fast_md5 = md5 $data;
		1756
		1757	=item IO::AIO::munmap $scalar
		1758
		1759	Removes a previous mmap and undefines the C<$scalar>.
		1760
		1761	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1762
		1763	Calls the C<munlock> function, undoing the effects of a previous
		1764	C<aio_mlock> call (see its description for details).
		1765
		1766	=item IO::AIO::munlockall
		1767
		1768	Calls the C<munlockall> function.
		1769
		1770	On systems that do not implement C<munlockall>, this function returns
		1771	ENOSYS, otherwise the return value of C<munlockall>.
		1772
		1773	=back
		1774
1238	=cut	1775	=cut
1239		1776
1240	# support function to convert a fd into a perl filehandle
1241	sub _fd2fh {
1242	return undef if $_[0] < 0;
1243
1244	# try to generate nice filehandles
1245	my $sym = "IO::AIO::fd#$_[0]";
1246	local *$sym;
1247
1248	open *$sym, "+<&=$_[0]" # usually works under any unix
1249	or open *$sym, "<&=$_[0]" # cygwin needs this
1250	or open *$sym, ">&=$_[0]" # or this
1251	or return undef;
1252
1253	*$sym
1254	}
1255
1256	min_parallel 8;	1777	min_parallel 8;
1257		1778
1258	END { flush }	1779	END { flush }
1259		1780
1260	1;	1781	1;
1261		1782
		1783	=head1 EVENT LOOP INTEGRATION
		1784
		1785	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1786	automatically into many event loops:
		1787
		1788	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1789	use AnyEvent::AIO;
		1790
		1791	You can also integrate IO::AIO manually into many event loops, here are
		1792	some examples of how to do this:
		1793
		1794	# EV integration
		1795	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1796
		1797	# Event integration
		1798	Event->io (fd => IO::AIO::poll_fileno,
		1799	poll => 'r',
		1800	cb => \&IO::AIO::poll_cb);
		1801
		1802	# Glib/Gtk2 integration
		1803	add_watch Glib::IO IO::AIO::poll_fileno,
		1804	in => sub { IO::AIO::poll_cb; 1 };
		1805
		1806	# Tk integration
		1807	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1808	readable => \&IO::AIO::poll_cb);
		1809
		1810	# Danga::Socket integration
		1811	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1812	\&IO::AIO::poll_cb);
		1813
1262	=head2 FORK BEHAVIOUR	1814	=head2 FORK BEHAVIOUR
1263		1815
1264	This module should do "the right thing" when the process using it forks:	1816	Usage of pthreads in a program changes the semantics of fork
		1817	considerably. Specifically, only async-safe functions can be called after
		1818	fork. Perl doesn't know about this, so in general, you cannot call fork
		1819	with defined behaviour in perl if pthreads are involved. IO::AIO uses
		1820	pthreads, so this applies, but many other extensions and (for inexplicable
		1821	reasons) perl itself often is linked against pthreads, so this limitation
		1822	applies to quite a lot of perls.
1265		1823
1266	Before the fork, IO::AIO enters a quiescent state where no requests	1824	This module no longer tries to fight your OS, or POSIX. That means IO::AIO
1267	can be added in other threads and no results will be processed. After	1825	only works in the process that loaded it. Forking is fully supported, but
1268	the fork the parent simply leaves the quiescent state and continues	1826	using IO::AIO in the child is not.
1269	request/result processing, while the child frees the request/result queue
1270	(so that the requests started before the fork will only be handled in the
1271	parent). Threads will be started on demand until the limit set in the
1272	parent process has been reached again.
1273		1827
1274	In short: the parent will, after a short pause, continue as if fork had	1828	You might get around by not I<using> IO::AIO before (or after)
1275	not been called, while the child will act as if IO::AIO has not been used	1829	forking. You could also try to call the L<IO::AIO::reinit> function in the
1276	yet.	1830	child:
		1831
		1832	=over 4
		1833
		1834	=item IO::AIO::reinit
		1835
		1836	Abandons all current requests and I/O threads and simply reinitialises all
		1837	data structures. This is not an operation supported by any standards, but
		1838	happens to work on GNU/Linux and some newer BSD systems.
		1839
		1840	The only reasonable use for this function is to call it after forking, if
		1841	C<IO::AIO> was used in the parent. Calling it while IO::AIO is active in
		1842	the process will result in undefined behaviour. Calling it at any time
		1843	will also result in any undefined (by POSIX) behaviour.
		1844
		1845	=back
1277		1846
1278	=head2 MEMORY USAGE	1847	=head2 MEMORY USAGE
1279		1848
1280	Per-request usage:	1849	Per-request usage:
1281		1850
…		…
1283	bytes of memory. In addition, stat requests need a stat buffer (possibly	1852	bytes of memory. In addition, stat requests need a stat buffer (possibly
1284	a few hundred bytes), readdir requires a result buffer and so on. Perl	1853	a few hundred bytes), readdir requires a result buffer and so on. Perl
1285	scalars and other data passed into aio requests will also be locked and	1854	scalars and other data passed into aio requests will also be locked and
1286	will consume memory till the request has entered the done state.	1855	will consume memory till the request has entered the done state.
1287		1856
1288	This is now awfully much, so queuing lots of requests is not usually a	1857	This is not awfully much, so queuing lots of requests is not usually a
1289	problem.	1858	problem.
1290		1859
1291	Per-thread usage:	1860	Per-thread usage:
1292		1861
1293	In the execution phase, some aio requests require more memory for	1862	In the execution phase, some aio requests require more memory for
…		…
1298		1867
1299	Known bugs will be fixed in the next release.	1868	Known bugs will be fixed in the next release.
1300		1869
1301	=head1 SEE ALSO	1870	=head1 SEE ALSO
1302		1871
1303	L<Coro::AIO>.	1872	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1873	more natural syntax.
1304		1874
1305	=head1 AUTHOR	1875	=head1 AUTHOR
1306		1876
1307	Marc Lehmann <schmorp@schmorp.de>	1877	Marc Lehmann <schmorp@schmorp.de>
1308	http://home.schmorp.de/	1878	http://home.schmorp.de/

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