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Revision 1.105 by root, Sun Mar 25 00:20:27 2007 UTC vs.
Revision 1.202 by root, Tue Jul 5 14:02:15 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 = '2.33';	173	our $VERSION = '3.93';
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 aio_fsync
		178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		179	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);	180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		181	aio_chmod aio_utime aio_truncate
		182	aio_msync aio_mtouch aio_mlock aio_mlockall
		183	aio_statvfs);
		184
201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));	185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
203	min_parallel max_parallel max_idle	187	min_parallel max_parallel max_idle idle_timeout
204	nreqs nready npending nthreads	188	nreqs nready npending nthreads
205	max_poll_time max_poll_reqs);	189	max_poll_time max_poll_reqs
		190	sendfile fadvise madvise
		191	mmap munmap munlock munlockall);
		192
		193	push @AIO_REQ, qw(aio_busy); # not exported
206		194
207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
208		196
209	require XSLoader;	197	require XSLoader;
210	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
211	}	199	}
212		200
213	=head1 FUNCTIONS	201	=head1 FUNCTIONS
		202
		203	=head2 QUICK OVERVIEW
		204
		205	This section simply lists the prototypes of the most important functions
		206	for quick reference. See the following sections for function-by-function
		207	documentation.
		208
		209	aio_open $pathname, $flags, $mode, $callback->($fh)
		210	aio_close $fh, $callback->($status)
		211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		214	aio_readahead $fh,$offset,$length, $callback->($retval)
		215	aio_stat $fh_or_path, $callback->($status)
		216	aio_lstat $fh, $callback->($status)
		217	aio_statvfs $fh_or_path, $callback->($statvfs)
		218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		220	aio_truncate $fh_or_path, $offset, $callback->($status)
		221	aio_chmod $fh_or_path, $mode, $callback->($status)
		222	aio_unlink $pathname, $callback->($status)
		223	aio_mknod $path, $mode, $dev, $callback->($status)
		224	aio_link $srcpath, $dstpath, $callback->($status)
		225	aio_symlink $srcpath, $dstpath, $callback->($status)
		226	aio_readlink $path, $callback->($link)
		227	aio_realpath $path, $callback->($link)
		228	aio_rename $srcpath, $dstpath, $callback->($status)
		229	aio_mkdir $pathname, $mode, $callback->($status)
		230	aio_rmdir $pathname, $callback->($status)
		231	aio_readdir $pathname, $callback->($entries)
		232	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		233	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		234	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		235	aio_load $path, $data, $callback->($status)
		236	aio_copy $srcpath, $dstpath, $callback->($status)
		237	aio_move $srcpath, $dstpath, $callback->($status)
		238	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		239	aio_rmtree $path, $callback->($status)
		240	aio_sync $callback->($status)
		241	aio_fsync $fh, $callback->($status)
		242	aio_fdatasync $fh, $callback->($status)
		243	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		244	aio_pathsync $path, $callback->($status)
		245	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		246	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		247	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		248	aio_mlockall $flags, $callback->($status)
		249	aio_group $callback->(...)
		250	aio_nop $callback->()
		251
		252	$prev_pri = aioreq_pri [$pri]
		253	aioreq_nice $pri_adjust
		254
		255	IO::AIO::poll_wait
		256	IO::AIO::poll_cb
		257	IO::AIO::poll
		258	IO::AIO::flush
		259	IO::AIO::max_poll_reqs $nreqs
		260	IO::AIO::max_poll_time $seconds
		261	IO::AIO::min_parallel $nthreads
		262	IO::AIO::max_parallel $nthreads
		263	IO::AIO::max_idle $nthreads
		264	IO::AIO::idle_timeout $seconds
		265	IO::AIO::max_outstanding $maxreqs
		266	IO::AIO::nreqs
		267	IO::AIO::nready
		268	IO::AIO::npending
		269
		270	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		271	IO::AIO::fadvise $fh, $offset, $len, $advice
		272	IO::AIO::madvise $scalar, $offset, $length, $advice
		273	IO::AIO::mprotect $scalar, $offset, $length, $protect
		274	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		275	IO::AIO::munlockall
214		276
215	=head2 AIO REQUEST FUNCTIONS	277	=head2 AIO REQUEST FUNCTIONS
216		278
217	All the C<aio_*> calls are more or less thin wrappers around the syscall	279	All the C<aio_*> calls are more or less thin wrappers around the syscall
218	with the same name (sans C<aio_>). The arguments are similar or identical,	280	with the same name (sans C<aio_>). The arguments are similar or identical,
219	and they all accept an additional (and optional) C<$callback> argument	281	and they all accept an additional (and optional) C<$callback> argument
220	which must be a code reference. This code reference will get called with	282	which must be a code reference. This code reference will get called with
221	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	283	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
222	perl, which usually delivers "false") as it's sole argument when the given	284	perl, which usually delivers "false") as its sole argument after the given
223	syscall has been executed asynchronously.	285	syscall has been executed asynchronously.
224		286
225	All functions expecting a filehandle keep a copy of the filehandle	287	All functions expecting a filehandle keep a copy of the filehandle
226	internally until the request has finished.	288	internally until the request has finished.
227		289
…		…
241	your pathnames to the locale (or other) encoding in effect in the user	303	your pathnames to the locale (or other) encoding in effect in the user
242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	304	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
243	use something else to ensure your scalar has the correct contents.	305	use something else to ensure your scalar has the correct contents.
244		306
245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	307	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
246	handles correctly wether it is set or not.	308	handles correctly whether it is set or not.
247		309
248	=over 4	310	=over 4
249		311
250	=item $prev_pri = aioreq_pri [$pri]	312	=item $prev_pri = aioreq_pri [$pri]
251		313
…		…
271	aio_read $_[0], ..., sub {	333	aio_read $_[0], ..., sub {
272	...	334	...
273	};	335	};
274	};	336	};
275		337
		338
276	=item aioreq_nice $pri_adjust	339	=item aioreq_nice $pri_adjust
277		340
278	Similar to C<aioreq_pri>, but subtracts the given value from the current	341	Similar to C<aioreq_pri>, but subtracts the given value from the current
279	priority, so the effect is cumulative.	342	priority, so the effect is cumulative.
		343
280		344
281	=item aio_open $pathname, $flags, $mode, $callback->($fh)	345	=item aio_open $pathname, $flags, $mode, $callback->($fh)
282		346
283	Asynchronously open or create a file and call the callback with a newly	347	Asynchronously open or create a file and call the callback with a newly
284	created filehandle for the file.	348	created filehandle for the file.
…		…
296	by the umask in effect then the request is being executed, so better never	360	by the umask in effect then the request is being executed, so better never
297	change the umask.	361	change the umask.
298		362
299	Example:	363	Example:
300		364
301	aio_open "/etc/passwd", O_RDONLY, 0, sub {	365	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
302	if ($_[0]) {	366	if ($_[0]) {
303	print "open successful, fh is $_[0]\n";	367	print "open successful, fh is $_[0]\n";
304	...	368	...
305	} else {	369	} else {
306	die "open failed: $!\n";	370	die "open failed: $!\n";
307	}	371	}
308	};	372	};
309		373
		374	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		375	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		376	following POSIX and non-POSIX constants are available (missing ones on
		377	your system are, as usual, C<0>):
		378
		379	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		380	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		381	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		382
		383
310	=item aio_close $fh, $callback->($status)	384	=item aio_close $fh, $callback->($status)
311		385
312	Asynchronously close a file and call the callback with the result	386	Asynchronously close a file and call the callback with the result
313	code. I<WARNING:> although accepted, you should not pass in a perl	387	code.
314	filehandle here, as perl will likely close the file descriptor another
315	time when the filehandle is destroyed. Normally, you can safely call perls
316	C<close> or just let filehandles go out of scope.
317		388
318	This is supposed to be a bug in the API, so that might change. It's	389	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
319	therefore best to avoid this function.	390	closing the file descriptor associated with the filehandle itself.
		391
		392	Therefore, C<aio_close> will not close the filehandle - instead it will
		393	use dup2 to overwrite the file descriptor with the write-end of a pipe
		394	(the pipe fd will be created on demand and will be cached).
		395
		396	Or in other words: the file descriptor will be closed, but it will not be
		397	free for reuse until the perl filehandle is closed.
		398
		399	=cut
320		400
321	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	401	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
322		402
323	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	403	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
324		404
325	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	405	Reads or writes C<$length> bytes from or to the specified C<$fh> and
326	into the scalar given by C<data> and offset C<dataoffset> and calls the	406	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
327	callback without the actual number of bytes read (or -1 on error, just	407	and calls the callback without the actual number of bytes read (or -1 on
328	like the syscall).	408	error, just like the syscall).
		409
		410	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		411	offset plus the actual number of bytes read.
		412
		413	If C<$offset> is undefined, then the current file descriptor offset will
		414	be used (and updated), otherwise the file descriptor offset will not be
		415	changed by these calls.
		416
		417	If C<$length> is undefined in C<aio_write>, use the remaining length of
		418	C<$data>.
		419
		420	If C<$dataoffset> is less than zero, it will be counted from the end of
		421	C<$data>.
329		422
330	The C<$data> scalar I<MUST NOT> be modified in any way while the request	423	The C<$data> scalar I<MUST NOT> be modified in any way while the request
331	is outstanding. Modifying it can result in segfaults or WW3 (if the	424	is outstanding. Modifying it can result in segfaults or World War III (if
332	necessary/optional hardware is installed).	425	the necessary/optional hardware is installed).
333		426
334	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	427	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
335	offset C<0> within the scalar:	428	offset C<0> within the scalar:
336		429
337	aio_read $fh, 7, 15, $buffer, 0, sub {	430	aio_read $fh, 7, 15, $buffer, 0, sub {
338	$_[0] > 0 or die "read error: $!";	431	$_[0] > 0 or die "read error: $!";
339	print "read $_[0] bytes: <$buffer>\n";	432	print "read $_[0] bytes: <$buffer>\n";
340	};	433	};
341		434
		435
342	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	436	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
343		437
344	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	438	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
345	reading at byte offset C<$in_offset>, and starts writing at the current	439	reading at byte offset C<$in_offset>, and starts writing at the current
346	file offset of C<$out_fh>. Because of that, it is not safe to issue more	440	file offset of C<$out_fh>. Because of that, it is not safe to issue more
347	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	441	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
348	other.	442	other. The same C<$in_fh> works fine though, as this function does not
		443	move or use the file offset of C<$in_fh>.
349		444
		445	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		446	are written, and there is no way to find out how many more bytes have been
		447	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		448	number of bytes written to C<$out_fh>. Only if the result value equals
		449	C<$length> one can assume that C<$length> bytes have been read.
		450
		451	Unlike with other C<aio_> functions, it makes a lot of sense to use
		452	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		453	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		454	the socket I/O will be non-blocking. Note, however, that you can run
		455	into a trap where C<aio_sendfile> reads some data with readahead, then
		456	fails to write all data, and when the socket is ready the next time, the
		457	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		458	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		459	resource usage.
		460
350	This call tries to make use of a native C<sendfile> syscall to provide	461	This call tries to make use of a native C<sendfile>-like syscall to
351	zero-copy operation. For this to work, C<$out_fh> should refer to a	462	provide zero-copy operation. For this to work, C<$out_fh> should refer to
352	socket, and C<$in_fh> should refer to mmap'able file.	463	a socket, and C<$in_fh> should refer to an mmap'able file.
353		464
354	If the native sendfile call fails or is not implemented, it will be	465	If a native sendfile cannot be found or it fails with C<ENOSYS>,
355	emulated, so you can call C<aio_sendfile> on any type of filehandle	466	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		467	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
356	regardless of the limitations of the operating system.	468	type of filehandle regardless of the limitations of the operating system.
357		469
358	Please note, however, that C<aio_sendfile> can read more bytes from	470	As native sendfile syscalls (as practically any non-POSIX interface hacked
359	C<$in_fh> than are written, and there is no way to find out how many	471	together in a hurry to improve benchmark numbers) tend to be rather buggy
360	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	472	on many systems, this implementation tries to work around some known bugs
361	provides the number of bytes written to C<$out_fh>. Only if the result	473	in Linux and FreeBSD kernels (probably others, too), but that might fail,
362	value equals C<$length> one can assume that C<$length> bytes have been	474	so you really really should check the return value of C<aio_sendfile> -
363	read.	475	fewre bytes than expected might have been transferred.
		476
364		477
365	=item aio_readahead $fh,$offset,$length, $callback->($retval)	478	=item aio_readahead $fh,$offset,$length, $callback->($retval)
366		479
367	C<aio_readahead> populates the page cache with data from a file so that	480	C<aio_readahead> populates the page cache with data from a file so that
368	subsequent reads from that file will not block on disk I/O. The C<$offset>	481	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
374	file. The current file offset of the file is left unchanged.	487	file. The current file offset of the file is left unchanged.
375		488
376	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	489	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
377	emulated by simply reading the data, which would have a similar effect.	490	emulated by simply reading the data, which would have a similar effect.
378		491
		492
379	=item aio_stat $fh_or_path, $callback->($status)	493	=item aio_stat $fh_or_path, $callback->($status)
380		494
381	=item aio_lstat $fh, $callback->($status)	495	=item aio_lstat $fh, $callback->($status)
382		496
383	Works like perl's C<stat> or C<lstat> in void context. The callback will	497	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
388	for an explanation.	502	for an explanation.
389		503
390	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	504	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
391	error when stat'ing a large file, the results will be silently truncated	505	error when stat'ing a large file, the results will be silently truncated
392	unless perl itself is compiled with large file support.	506	unless perl itself is compiled with large file support.
		507
		508	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		509	following constants and functions (if not implemented, the constants will
		510	be C<0> and the functions will either C<croak> or fall back on traditional
		511	behaviour).
		512
		513	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		514	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		515	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
393		516
394	Example: Print the length of F</etc/passwd>:	517	Example: Print the length of F</etc/passwd>:
395		518
396	aio_stat "/etc/passwd", sub {	519	aio_stat "/etc/passwd", sub {
397	$_[0] and die "stat failed: $!";	520	$_[0] and die "stat failed: $!";
398	print "size is ", -s _, "\n";	521	print "size is ", -s _, "\n";
399	};	522	};
400		523
		524
		525	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		526
		527	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		528	whether a file handle or path was passed.
		529
		530	On success, the callback is passed a hash reference with the following
		531	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		532	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		533	is passed.
		534
		535	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		536	C<ST_NOSUID>.
		537
		538	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		539	their correct value when available, or to C<0> on systems that do
		540	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		541	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		542	C<ST_NODIRATIME> and C<ST_RELATIME>.
		543
		544	Example: stat C</wd> and dump out the data if successful.
		545
		546	aio_statvfs "/wd", sub {
		547	my $f = $_[0]
		548	or die "statvfs: $!";
		549
		550	use Data::Dumper;
		551	say Dumper $f;
		552	};
		553
		554	# result:
		555	{
		556	bsize => 1024,
		557	bfree => 4333064312,
		558	blocks => 10253828096,
		559	files => 2050765568,
		560	flag => 4096,
		561	favail => 2042092649,
		562	bavail => 4333064312,
		563	ffree => 2042092649,
		564	namemax => 255,
		565	frsize => 1024,
		566	fsid => 1810
		567	}
		568
		569
		570	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		571
		572	Works like perl's C<utime> function (including the special case of $atime
		573	and $mtime being undef). Fractional times are supported if the underlying
		574	syscalls support them.
		575
		576	When called with a pathname, uses utimes(2) if available, otherwise
		577	utime(2). If called on a file descriptor, uses futimes(2) if available,
		578	otherwise returns ENOSYS, so this is not portable.
		579
		580	Examples:
		581
		582	# set atime and mtime to current time (basically touch(1)):
		583	aio_utime "path", undef, undef;
		584	# set atime to current time and mtime to beginning of the epoch:
		585	aio_utime "path", time, undef; # undef==0
		586
		587
		588	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		589
		590	Works like perl's C<chown> function, except that C<undef> for either $uid
		591	or $gid is being interpreted as "do not change" (but -1 can also be used).
		592
		593	Examples:
		594
		595	# same as "chown root path" in the shell:
		596	aio_chown "path", 0, -1;
		597	# same as above:
		598	aio_chown "path", 0, undef;
		599
		600
		601	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		602
		603	Works like truncate(2) or ftruncate(2).
		604
		605
		606	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		607
		608	Works like perl's C<chmod> function.
		609
		610
401	=item aio_unlink $pathname, $callback->($status)	611	=item aio_unlink $pathname, $callback->($status)
402		612
403	Asynchronously unlink (delete) a file and call the callback with the	613	Asynchronously unlink (delete) a file and call the callback with the
404	result code.	614	result code.
405		615
		616
406	=item aio_mknod $path, $mode, $dev, $callback->($status)	617	=item aio_mknod $path, $mode, $dev, $callback->($status)
407		618
408	[EXPERIMENTAL]	619	[EXPERIMENTAL]
409		620
410	Asynchronously create a device node (or fifo). See mknod(2).	621	Asynchronously create a device node (or fifo). See mknod(2).
411		622
412	The only (POSIX-) portable way of calling this function is:	623	The only (POSIX-) portable way of calling this function is:
413		624
414	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...	625	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		626
		627	See C<aio_stat> for info about some potentially helpful extra constants
		628	and functions.
415		629
416	=item aio_link $srcpath, $dstpath, $callback->($status)	630	=item aio_link $srcpath, $dstpath, $callback->($status)
417		631
418	Asynchronously create a new link to the existing object at C<$srcpath> at	632	Asynchronously create a new link to the existing object at C<$srcpath> at
419	the path C<$dstpath> and call the callback with the result code.	633	the path C<$dstpath> and call the callback with the result code.
420		634
		635
421	=item aio_symlink $srcpath, $dstpath, $callback->($status)	636	=item aio_symlink $srcpath, $dstpath, $callback->($status)
422		637
423	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	638	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
424	the path C<$dstpath> and call the callback with the result code.	639	the path C<$dstpath> and call the callback with the result code.
		640
425		641
426	=item aio_readlink $path, $callback->($link)	642	=item aio_readlink $path, $callback->($link)
427		643
428	Asynchronously read the symlink specified by C<$path> and pass it to	644	Asynchronously read the symlink specified by C<$path> and pass it to
429	the callback. If an error occurs, nothing or undef gets passed to the	645	the callback. If an error occurs, nothing or undef gets passed to the
430	callback.	646	callback.
431		647
		648
		649	=item aio_realpath $path, $callback->($path)
		650
		651	Asynchronously make the path absolute and resolve any symlinks in
		652	C<$path>. The resulting path only consists of directories (Same as
		653	L<Cwd::realpath>).
		654
		655	This request can be used to get the absolute path of the current working
		656	directory by passing it a path of F<.> (a single dot).
		657
		658
432	=item aio_rename $srcpath, $dstpath, $callback->($status)	659	=item aio_rename $srcpath, $dstpath, $callback->($status)
433		660
434	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	661	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
435	rename(2) and call the callback with the result code.	662	rename(2) and call the callback with the result code.
		663
436		664
437	=item aio_mkdir $pathname, $mode, $callback->($status)	665	=item aio_mkdir $pathname, $mode, $callback->($status)
438		666
439	Asynchronously mkdir (create) a directory and call the callback with	667	Asynchronously mkdir (create) a directory and call the callback with
440	the result code. C<$mode> will be modified by the umask at the time the	668	the result code. C<$mode> will be modified by the umask at the time the
441	request is executed, so do not change your umask.	669	request is executed, so do not change your umask.
442		670
		671
443	=item aio_rmdir $pathname, $callback->($status)	672	=item aio_rmdir $pathname, $callback->($status)
444		673
445	Asynchronously rmdir (delete) a directory and call the callback with the	674	Asynchronously rmdir (delete) a directory and call the callback with the
446	result code.	675	result code.
		676
447		677
448	=item aio_readdir $pathname, $callback->($entries)	678	=item aio_readdir $pathname, $callback->($entries)
449		679
450	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	680	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
451	directory (i.e. opendir + readdir + closedir). The entries will not be	681	directory (i.e. opendir + readdir + closedir). The entries will not be
452	sorted, and will B<NOT> include the C<.> and C<..> entries.	682	sorted, and will B<NOT> include the C<.> and C<..> entries.
453		683
454	The callback a single argument which is either C<undef> or an array-ref	684	The callback is passed a single argument which is either C<undef> or an
455	with the filenames.	685	array-ref with the filenames.
		686
		687
		688	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		689
		690	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		691	behaviour and output format. In case of an error, C<$entries> will be
		692	C<undef>.
		693
		694	The flags are a combination of the following constants, ORed together (the
		695	flags will also be passed to the callback, possibly modified):
		696
		697	=over 4
		698
		699	=item IO::AIO::READDIR_DENTS
		700
		701	When this flag is off, then the callback gets an arrayref consisting of
		702	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		703	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		704	entry in more detail.
		705
		706	C<$name> is the name of the entry.
		707
		708	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		709
		710	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		711	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		712	C<IO::AIO::DT_WHT>.
		713
		714	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		715	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		716	scalars are read-only: you can not modify them.
		717
		718	C<$inode> is the inode number (which might not be exact on systems with 64
		719	bit inode numbers and 32 bit perls). This field has unspecified content on
		720	systems that do not deliver the inode information.
		721
		722	=item IO::AIO::READDIR_DIRS_FIRST
		723
		724	When this flag is set, then the names will be returned in an order where
		725	likely directories come first, in optimal stat order. This is useful when
		726	you need to quickly find directories, or you want to find all directories
		727	while avoiding to stat() each entry.
		728
		729	If the system returns type information in readdir, then this is used
		730	to find directories directly. Otherwise, likely directories are names
		731	beginning with ".", or otherwise names with no dots, of which names with
		732	short names are tried first.
		733
		734	=item IO::AIO::READDIR_STAT_ORDER
		735
		736	When this flag is set, then the names will be returned in an order
		737	suitable for stat()'ing each one. That is, when you plan to stat()
		738	all files in the given directory, then the returned order will likely
		739	be fastest.
		740
		741	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		742	the likely dirs come first, resulting in a less optimal stat order.
		743
		744	=item IO::AIO::READDIR_FOUND_UNKNOWN
		745
		746	This flag should not be set when calling C<aio_readdirx>. Instead, it
		747	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		748	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		749	C<$type>'s are known, which can be used to speed up some algorithms.
		750
		751	=back
		752
456		753
457	=item aio_load $path, $data, $callback->($status)	754	=item aio_load $path, $data, $callback->($status)
458		755
459	This is a composite request that tries to fully load the given file into	756	This is a composite request that tries to fully load the given file into
460	memory. Status is the same as with aio_read.	757	memory. Status is the same as with aio_read.
461		758
462	=cut	759	=cut
463		760
464	sub aio_load($$;$) {	761	sub aio_load($$;$) {
465	aio_block {
466	my ($path, undef, $cb) = @_;	762	my ($path, undef, $cb) = @_;
467	my $data = \$_[1];	763	my $data = \$_[1];
468		764
469	my $pri = aioreq_pri;	765	my $pri = aioreq_pri;
470	my $grp = aio_group $cb;	766	my $grp = aio_group $cb;
		767
		768	aioreq_pri $pri;
		769	add $grp aio_open $path, O_RDONLY, 0, sub {
		770	my $fh = shift
		771	or return $grp->result (-1);
471		772
472	aioreq_pri $pri;	773	aioreq_pri $pri;
473	add $grp aio_open $path, O_RDONLY, 0, sub {
474	my $fh = shift
475	or return $grp->result (-1);
476
477	aioreq_pri $pri;
478	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {	774	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
479	$grp->result ($_[0]);	775	$grp->result ($_[0]);
480	};
481	};	776	};
482
483	$grp
484	}	777	};
		778
		779	$grp
485	}	780	}
486		781
487	=item aio_copy $srcpath, $dstpath, $callback->($status)	782	=item aio_copy $srcpath, $dstpath, $callback->($status)
488		783
489	Try to copy the I<file> (directories not supported as either source or	784	Try to copy the I<file> (directories not supported as either source or
490	destination) from C<$srcpath> to C<$dstpath> and call the callback with	785	destination) from C<$srcpath> to C<$dstpath> and call the callback with
491	the C<0> (error) or C<-1> ok.	786	a status of C<0> (ok) or C<-1> (error, see C<$!>).
492		787
493	This is a composite request that it creates the destination file with	788	This is a composite request that creates the destination file with
494	mode 0200 and copies the contents of the source file into it using	789	mode 0200 and copies the contents of the source file into it using
495	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	790	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
496	uid/gid, in that order.	791	uid/gid, in that order.
497		792
498	If an error occurs, the partial destination file will be unlinked, if	793	If an error occurs, the partial destination file will be unlinked, if
…		…
500	errors are being ignored.	795	errors are being ignored.
501		796
502	=cut	797	=cut
503		798
504	sub aio_copy($$;$) {	799	sub aio_copy($$;$) {
505	aio_block {
506	my ($src, $dst, $cb) = @_;	800	my ($src, $dst, $cb) = @_;
507		801
508	my $pri = aioreq_pri;	802	my $pri = aioreq_pri;
509	my $grp = aio_group $cb;	803	my $grp = aio_group $cb;
510		804
511	aioreq_pri $pri;	805	aioreq_pri $pri;
512	add $grp aio_open $src, O_RDONLY, 0, sub {	806	add $grp aio_open $src, O_RDONLY, 0, sub {
513	if (my $src_fh = $_[0]) {	807	if (my $src_fh = $_[0]) {
514	my @stat = stat $src_fh;	808	my @stat = stat $src_fh; # hmm, might block over nfs?
515		809
516	aioreq_pri $pri;	810	aioreq_pri $pri;
517	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {	811	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
518	if (my $dst_fh = $_[0]) {	812	if (my $dst_fh = $_[0]) {
519	aioreq_pri $pri;	813	aioreq_pri $pri;
520	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	814	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
521	if ($_[0] == $stat[7]) {	815	if ($_[0] == $stat[7]) {
522	$grp->result (0);	816	$grp->result (0);
523	close $src_fh;	817	close $src_fh;
524		818
525	# those should not normally block. should. should.
526	utime $stat[8], $stat[9], $dst;
527	chmod $stat[2] & 07777, $dst_fh;
528	chown $stat[4], $stat[5], $dst_fh;
529	close $dst_fh;
530	} else {	819	my $ch = sub {
531	$grp->result (-1);
532	close $src_fh;
533	close $dst_fh;
534
535	aioreq $pri;	820	aioreq_pri $pri;
		821	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		822	aioreq_pri $pri;
		823	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		824	aioreq_pri $pri;
536	add $grp aio_unlink $dst;	825	add $grp aio_close $dst_fh;
		826	}
		827	};
537	}	828	};
		829
		830	aioreq_pri $pri;
		831	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		832	if ($_[0] < 0 && $! == ENOSYS) {
		833	aioreq_pri $pri;
		834	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		835	} else {
		836	$ch->();
		837	}
		838	};
		839	} else {
		840	$grp->result (-1);
		841	close $src_fh;
		842	close $dst_fh;
		843
		844	aioreq $pri;
		845	add $grp aio_unlink $dst;
538	};	846	}
539	} else {
540	$grp->result (-1);
541	}	847	};
		848	} else {
		849	$grp->result (-1);
542	},	850	}
543
544	} else {
545	$grp->result (-1);
546	}	851	},
		852
		853	} else {
		854	$grp->result (-1);
547	};	855	}
548
549	$grp
550	}	856	};
		857
		858	$grp
551	}	859	}
552		860
553	=item aio_move $srcpath, $dstpath, $callback->($status)	861	=item aio_move $srcpath, $dstpath, $callback->($status)
554		862
555	Try to move the I<file> (directories not supported as either source or	863	Try to move the I<file> (directories not supported as either source or
556	destination) from C<$srcpath> to C<$dstpath> and call the callback with	864	destination) from C<$srcpath> to C<$dstpath> and call the callback with
557	the C<0> (error) or C<-1> ok.	865	a status of C<0> (ok) or C<-1> (error, see C<$!>).
558		866
559	This is a composite request that tries to rename(2) the file first. If	867	This is a composite request that tries to rename(2) the file first; if
560	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	868	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
561	that is successful, unlinking the C<$srcpath>.	869	that is successful, unlinks the C<$srcpath>.
562		870
563	=cut	871	=cut
564		872
565	sub aio_move($$;$) {	873	sub aio_move($$;$) {
566	aio_block {
567	my ($src, $dst, $cb) = @_;	874	my ($src, $dst, $cb) = @_;
568		875
569	my $pri = aioreq_pri;	876	my $pri = aioreq_pri;
570	my $grp = aio_group $cb;	877	my $grp = aio_group $cb;
571		878
572	aioreq_pri $pri;	879	aioreq_pri $pri;
573	add $grp aio_rename $src, $dst, sub {	880	add $grp aio_rename $src, $dst, sub {
574	if ($_[0] && $! == EXDEV) {	881	if ($_[0] && $! == EXDEV) {
575	aioreq_pri $pri;	882	aioreq_pri $pri;
576	add $grp aio_copy $src, $dst, sub {	883	add $grp aio_copy $src, $dst, sub {
577	$grp->result ($_[0]);
578
579	if (!$_[0]) {
580	aioreq_pri $pri;
581	add $grp aio_unlink $src;
582	}
583	};
584	} else {
585	$grp->result ($_[0]);	884	$grp->result ($_[0]);
		885
		886	unless ($_[0]) {
		887	aioreq_pri $pri;
		888	add $grp aio_unlink $src;
		889	}
586	}	890	};
		891	} else {
		892	$grp->result ($_[0]);
587	};	893	}
588
589	$grp
590	}	894	};
		895
		896	$grp
591	}	897	}
592		898
593	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	899	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
594		900
595	Scans a directory (similar to C<aio_readdir>) but additionally tries to	901	Scans a directory (similar to C<aio_readdir>) but additionally tries to
…		…
615		921
616	Implementation notes.	922	Implementation notes.
617		923
618	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	924	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
619		925
		926	If readdir returns file type information, then this is used directly to
		927	find directories.
		928
620	After reading the directory, the modification time, size etc. of the	929	Otherwise, after reading the directory, the modification time, size etc.
621	directory before and after the readdir is checked, and if they match (and	930	of the directory before and after the readdir is checked, and if they
622	isn't the current time), the link count will be used to decide how many	931	match (and isn't the current time), the link count will be used to decide
623	entries are directories (if >= 2). Otherwise, no knowledge of the number	932	how many entries are directories (if >= 2). Otherwise, no knowledge of the
624	of subdirectories will be assumed.	933	number of subdirectories will be assumed.
625		934
626	Then entries will be sorted into likely directories (everything without	935	Then entries will be sorted into likely directories a non-initial dot
627	a non-initial dot currently) and likely non-directories (everything	936	currently) and likely non-directories (see C<aio_readdirx>). Then every
628	else). Then every entry plus an appended C</.> will be C<stat>'ed,	937	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
629	likely directories first. If that succeeds, it assumes that the entry	938	in order of their inode numbers. If that succeeds, it assumes that the
630	is a directory or a symlink to directory (which will be checked	939	entry is a directory or a symlink to directory (which will be checked
631	seperately). This is often faster than stat'ing the entry itself because	940	seperately). This is often faster than stat'ing the entry itself because
632	filesystems might detect the type of the entry without reading the inode	941	filesystems might detect the type of the entry without reading the inode
633	data (e.g. ext2fs filetype feature).	942	data (e.g. ext2fs filetype feature), even on systems that cannot return
		943	the filetype information on readdir.
634		944
635	If the known number of directories (link count - 2) has been reached, the	945	If the known number of directories (link count - 2) has been reached, the
636	rest of the entries is assumed to be non-directories.	946	rest of the entries is assumed to be non-directories.
637		947
638	This only works with certainty on POSIX (= UNIX) filesystems, which	948	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
643	directory counting heuristic.	953	directory counting heuristic.
644		954
645	=cut	955	=cut
646		956
647	sub aio_scandir($$;$) {	957	sub aio_scandir($$;$) {
648	aio_block {
649	my ($path, $maxreq, $cb) = @_;	958	my ($path, $maxreq, $cb) = @_;
650		959
651	my $pri = aioreq_pri;	960	my $pri = aioreq_pri;
652		961
653	my $grp = aio_group $cb;	962	my $grp = aio_group $cb;
654		963
655	$maxreq = 4 if $maxreq <= 0;	964	$maxreq = 4 if $maxreq <= 0;
656		965
657	# stat once	966	# stat once
		967	aioreq_pri $pri;
		968	add $grp aio_stat $path, sub {
		969	return $grp->result () if $_[0];
		970	my $now = time;
		971	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		972
		973	# read the directory entries
658	aioreq_pri $pri;	974	aioreq_pri $pri;
659	add $grp aio_stat $path, sub {	975	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
		976	my $entries = shift
660	return $grp->result () if $_[0];	977	or return $grp->result ();
661	my $now = time;
662	my $hash1 = join ":", (stat _)[0,1,3,7,9];
663		978
664	# read the directory entries	979	# stat the dir another time
665	aioreq_pri $pri;	980	aioreq_pri $pri;
666	add $grp aio_readdir $path, sub {
667	my $entries = shift
668	or return $grp->result ();
669
670	# stat the dir another time
671	aioreq_pri $pri;
672	add $grp aio_stat $path, sub {	981	add $grp aio_stat $path, sub {
673	my $hash2 = join ":", (stat _)[0,1,3,7,9];	982	my $hash2 = join ":", (stat _)[0,1,3,7,9];
674		983
675	my $ndirs;	984	my $ndirs;
676		985
677	# take the slow route if anything looks fishy	986	# take the slow route if anything looks fishy
678	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	987	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
679	$ndirs = -1;	988	$ndirs = -1;
680	} else {	989	} else {
681	# if nlink == 2, we are finished	990	# if nlink == 2, we are finished
682	# on non-posix-fs's, we rely on nlink < 2	991	# for non-posix-fs's, we rely on nlink < 2
683	$ndirs = (stat _)[3] - 2	992	$ndirs = (stat _)[3] - 2
684	or return $grp->result ([], $entries);	993	or return $grp->result ([], $entries);
685	}	994	}
686		995
687	# sort into likely dirs and likely nondirs
688	# dirs == files without ".", short entries first
689	$entries = [map $_->[0],
690	sort { $b->[1] cmp $a->[1] }
691	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
692	@$entries];
693
694	my (@dirs, @nondirs);	996	my (@dirs, @nondirs);
695		997
696	my $statgrp = add $grp aio_group sub {	998	my $statgrp = add $grp aio_group sub {
697	$grp->result (\@dirs, \@nondirs);	999	$grp->result (\@dirs, \@nondirs);
698	};	1000	};
699		1001
700	limit $statgrp $maxreq;	1002	limit $statgrp $maxreq;
701	feed $statgrp sub {	1003	feed $statgrp sub {
702	return unless @$entries;	1004	return unless @$entries;
703	my $entry = pop @$entries;	1005	my $entry = shift @$entries;
704		1006
705	aioreq_pri $pri;	1007	aioreq_pri $pri;
706	add $statgrp aio_stat "$path/$entry/.", sub {	1008	add $statgrp aio_stat "$path/$entry/.", sub {
707	if ($_[0] < 0) {	1009	if ($_[0] < 0) {
708	push @nondirs, $entry;	1010	push @nondirs, $entry;
709	} else {	1011	} else {
710	# need to check for real directory	1012	# need to check for real directory
711	aioreq_pri $pri;	1013	aioreq_pri $pri;
712	add $statgrp aio_lstat "$path/$entry", sub {	1014	add $statgrp aio_lstat "$path/$entry", sub {
713	if (-d _) {	1015	if (-d _) {
714	push @dirs, $entry;	1016	push @dirs, $entry;
715		1017
716	unless (--$ndirs) {	1018	unless (--$ndirs) {
717	push @nondirs, @$entries;	1019	push @nondirs, @$entries;
718	feed $statgrp;	1020	feed $statgrp;
719	}
720	} else {
721	push @nondirs, $entry;
722	}	1021	}
		1022	} else {
		1023	push @nondirs, $entry;
723	}	1024	}
724	}	1025	}
725	};	1026	}
726	};	1027	};
727	};	1028	};
728	};	1029	};
729	};	1030	};
730
731	$grp
732	}	1031	};
		1032
		1033	$grp
733	}	1034	}
734		1035
735	=item aio_rmtree $path, $callback->($status)	1036	=item aio_rmtree $path, $callback->($status)
736		1037
737	Delete a directory tree starting (and including) C<$path>, return the	1038	Delete a directory tree starting (and including) C<$path>, return the
…		…
741		1042
742	=cut	1043	=cut
743		1044
744	sub aio_rmtree;	1045	sub aio_rmtree;
745	sub aio_rmtree($;$) {	1046	sub aio_rmtree($;$) {
746	aio_block {
747	my ($path, $cb) = @_;	1047	my ($path, $cb) = @_;
748		1048
749	my $pri = aioreq_pri;	1049	my $pri = aioreq_pri;
750	my $grp = aio_group $cb;	1050	my $grp = aio_group $cb;
751		1051
752	aioreq_pri $pri;	1052	aioreq_pri $pri;
753	add $grp aio_scandir $path, 0, sub {	1053	add $grp aio_scandir $path, 0, sub {
754	my ($dirs, $nondirs) = @_;	1054	my ($dirs, $nondirs) = @_;
755		1055
756	my $dirgrp = aio_group sub {	1056	my $dirgrp = aio_group sub {
757	add $grp aio_rmdir $path, sub {	1057	add $grp aio_rmdir $path, sub {
758	$grp->result ($_[0]);	1058	$grp->result ($_[0]);
759	};
760	};	1059	};
761
762	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
763	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
764
765	add $grp $dirgrp;
766	};	1060	};
767		1061
768	$grp	1062	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1063	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1064
		1065	add $grp $dirgrp;
769	}	1066	};
		1067
		1068	$grp
770	}	1069	}
		1070
		1071	=item aio_sync $callback->($status)
		1072
		1073	Asynchronously call sync and call the callback when finished.
771		1074
772	=item aio_fsync $fh, $callback->($status)	1075	=item aio_fsync $fh, $callback->($status)
773		1076
774	Asynchronously call fsync on the given filehandle and call the callback	1077	Asynchronously call fsync on the given filehandle and call the callback
775	with the fsync result code.	1078	with the fsync result code.
…		…
779	Asynchronously call fdatasync on the given filehandle and call the	1082	Asynchronously call fdatasync on the given filehandle and call the
780	callback with the fdatasync result code.	1083	callback with the fdatasync result code.
781		1084
782	If this call isn't available because your OS lacks it or it couldn't be	1085	If this call isn't available because your OS lacks it or it couldn't be
783	detected, it will be emulated by calling C<fsync> instead.	1086	detected, it will be emulated by calling C<fsync> instead.
		1087
		1088	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1089
		1090	Sync the data portion of the file specified by C<$offset> and C<$length>
		1091	to disk (but NOT the metadata), by calling the Linux-specific
		1092	sync_file_range call. If sync_file_range is not available or it returns
		1093	ENOSYS, then fdatasync or fsync is being substituted.
		1094
		1095	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1096	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1097	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1098	manpage for details.
		1099
		1100	=item aio_pathsync $path, $callback->($status)
		1101
		1102	This request tries to open, fsync and close the given path. This is a
		1103	composite request intended to sync directories after directory operations
		1104	(E.g. rename). This might not work on all operating systems or have any
		1105	specific effect, but usually it makes sure that directory changes get
		1106	written to disc. It works for anything that can be opened for read-only,
		1107	not just directories.
		1108
		1109	Future versions of this function might fall back to other methods when
		1110	C<fsync> on the directory fails (such as calling C<sync>).
		1111
		1112	Passes C<0> when everything went ok, and C<-1> on error.
		1113
		1114	=cut
		1115
		1116	sub aio_pathsync($;$) {
		1117	my ($path, $cb) = @_;
		1118
		1119	my $pri = aioreq_pri;
		1120	my $grp = aio_group $cb;
		1121
		1122	aioreq_pri $pri;
		1123	add $grp aio_open $path, O_RDONLY, 0, sub {
		1124	my ($fh) = @_;
		1125	if ($fh) {
		1126	aioreq_pri $pri;
		1127	add $grp aio_fsync $fh, sub {
		1128	$grp->result ($_[0]);
		1129
		1130	aioreq_pri $pri;
		1131	add $grp aio_close $fh;
		1132	};
		1133	} else {
		1134	$grp->result (-1);
		1135	}
		1136	};
		1137
		1138	$grp
		1139	}
		1140
		1141	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1142
		1143	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1144	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1145	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1146	scalar must only be modified in-place while an aio operation is pending on
		1147	it).
		1148
		1149	It calls the C<msync> function of your OS, if available, with the memory
		1150	area starting at C<$offset> in the string and ending C<$length> bytes
		1151	later. If C<$length> is negative, counts from the end, and if C<$length>
		1152	is C<undef>, then it goes till the end of the string. The flags can be
		1153	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1154	C<IO::AIO::MS_SYNC>.
		1155
		1156	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1157
		1158	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1159	scalars.
		1160
		1161	It touches (reads or writes) all memory pages in the specified
		1162	range inside the scalar. All caveats and parameters are the same
		1163	as for C<aio_msync>, above, except for flags, which must be either
		1164	C<0> (which reads all pages and ensures they are instantiated) or
		1165	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1166	writing an octet from it, which dirties the page).
		1167
		1168	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1169
		1170	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1171	scalars.
		1172
		1173	It reads in all the pages of the underlying storage into memory (if any)
		1174	and locks them, so they are not getting swapped/paged out or removed.
		1175
		1176	If C<$length> is undefined, then the scalar will be locked till the end.
		1177
		1178	On systems that do not implement C<mlock>, this function returns C<-1>
		1179	and sets errno to C<ENOSYS>.
		1180
		1181	Note that the corresponding C<munlock> is synchronous and is
		1182	documented under L<MISCELLANEOUS FUNCTIONS>.
		1183
		1184	Example: open a file, mmap and mlock it - both will be undone when
		1185	C<$data> gets destroyed.
		1186
		1187	open my $fh, "<", $path or die "$path: $!";
		1188	my $data;
		1189	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1190	aio_mlock $data; # mlock in background
		1191
		1192	=item aio_mlockall $flags, $callback->($status)
		1193
		1194	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1195	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1196
		1197	On systems that do not implement C<mlockall>, this function returns C<-1>
		1198	and sets errno to C<ENOSYS>.
		1199
		1200	Note that the corresponding C<munlockall> is synchronous and is
		1201	documented under L<MISCELLANEOUS FUNCTIONS>.
		1202
		1203	Example: asynchronously lock all current and future pages into memory.
		1204
		1205	aio_mlockall IO::AIO::MCL_FUTURE;
784		1206
785	=item aio_group $callback->(...)	1207	=item aio_group $callback->(...)
786		1208
787	This is a very special aio request: Instead of doing something, it is a	1209	This is a very special aio request: Instead of doing something, it is a
788	container for other aio requests, which is useful if you want to bundle	1210	container for other aio requests, which is useful if you want to bundle
…		…
838	=item cancel $req	1260	=item cancel $req
839		1261
840	Cancels the request, if possible. Has the effect of skipping execution	1262	Cancels the request, if possible. Has the effect of skipping execution
841	when entering the B<execute> state and skipping calling the callback when	1263	when entering the B<execute> state and skipping calling the callback when
842	entering the the B<result> state, but will leave the request otherwise	1264	entering the the B<result> state, but will leave the request otherwise
843	untouched. That means that requests that currently execute will not be	1265	untouched (with the exception of readdir). That means that requests that
844	stopped and resources held by the request will not be freed prematurely.	1266	currently execute will not be stopped and resources held by the request
		1267	will not be freed prematurely.
845		1268
846	=item cb $req $callback->(...)	1269	=item cb $req $callback->(...)
847		1270
848	Replace (or simply set) the callback registered to the request.	1271	Replace (or simply set) the callback registered to the request.
849		1272
…		…
900	Their lifetime, simplified, looks like this: when they are empty, they	1323	Their lifetime, simplified, looks like this: when they are empty, they
901	will finish very quickly. If they contain only requests that are in the	1324	will finish very quickly. If they contain only requests that are in the
902	C<done> state, they will also finish. Otherwise they will continue to	1325	C<done> state, they will also finish. Otherwise they will continue to
903	exist.	1326	exist.
904		1327
905	That means after creating a group you have some time to add requests. And	1328	That means after creating a group you have some time to add requests
906	in the callbacks of those requests, you can add further requests to the	1329	(precisely before the callback has been invoked, which is only done within
907	group. And only when all those requests have finished will the the group	1330	the C<poll_cb>). And in the callbacks of those requests, you can add
908	itself finish.	1331	further requests to the group. And only when all those requests have
		1332	finished will the the group itself finish.
909		1333
910	=over 4	1334	=over 4
911		1335
912	=item add $grp ...	1336	=item add $grp ...
913		1337
…		…
922	=item $grp->cancel_subs	1346	=item $grp->cancel_subs
923		1347
924	Cancel all subrequests and clears any feeder, but not the group request	1348	Cancel all subrequests and clears any feeder, but not the group request
925	itself. Useful when you queued a lot of events but got a result early.	1349	itself. Useful when you queued a lot of events but got a result early.
926		1350
		1351	The group request will finish normally (you cannot add requests to the
		1352	group).
		1353
927	=item $grp->result (...)	1354	=item $grp->result (...)
928		1355
929	Set the result value(s) that will be passed to the group callback when all	1356	Set the result value(s) that will be passed to the group callback when all
930	subrequests have finished and set thre groups errno to the current value	1357	subrequests have finished and set the groups errno to the current value
931	of errno (just like calling C<errno> without an error number). By default,	1358	of errno (just like calling C<errno> without an error number). By default,
932	no argument will be passed and errno is zero.	1359	no argument will be passed and errno is zero.
933		1360
934	=item $grp->errno ([$errno])	1361	=item $grp->errno ([$errno])
935		1362
…		…
946	=item feed $grp $callback->($grp)	1373	=item feed $grp $callback->($grp)
947		1374
948	Sets a feeder/generator on this group: every group can have an attached	1375	Sets a feeder/generator on this group: every group can have an attached
949	generator that generates requests if idle. The idea behind this is that,	1376	generator that generates requests if idle. The idea behind this is that,
950	although you could just queue as many requests as you want in a group,	1377	although you could just queue as many requests as you want in a group,
951	this might starve other requests for a potentially long time. For	1378	this might starve other requests for a potentially long time. For example,
952	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1379	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
953	requests, delaying any later requests for a long time.	1380	delaying any later requests for a long time.
954		1381
955	To avoid this, and allow incremental generation of requests, you can	1382	To avoid this, and allow incremental generation of requests, you can
956	instead a group and set a feeder on it that generates those requests. The	1383	instead a group and set a feeder on it that generates those requests. The
957	feed callback will be called whenever there are few enough (see C<limit>,	1384	feed callback will be called whenever there are few enough (see C<limit>,
958	below) requests active in the group itself and is expected to queue more	1385	below) requests active in the group itself and is expected to queue more
…		…
962	not impose any limits).	1389	not impose any limits).
963		1390
964	If the feed does not queue more requests when called, it will be	1391	If the feed does not queue more requests when called, it will be
965	automatically removed from the group.	1392	automatically removed from the group.
966		1393
967	If the feed limit is C<0>, it will be set to C<2> automatically.	1394	If the feed limit is C<0> when this method is called, it will be set to
		1395	C<2> automatically.
968		1396
969	Example:	1397	Example:
970		1398
971	# stat all files in @files, but only ever use four aio requests concurrently:	1399	# stat all files in @files, but only ever use four aio requests concurrently:
972		1400
…		…
984	Sets the feeder limit for the group: The feeder will be called whenever	1412	Sets the feeder limit for the group: The feeder will be called whenever
985	the group contains less than this many requests.	1413	the group contains less than this many requests.
986		1414
987	Setting the limit to C<0> will pause the feeding process.	1415	Setting the limit to C<0> will pause the feeding process.
988		1416
		1417	The default value for the limit is C<0>, but note that setting a feeder
		1418	automatically bumps it up to C<2>.
		1419
989	=back	1420	=back
990		1421
991	=head2 SUPPORT FUNCTIONS	1422	=head2 SUPPORT FUNCTIONS
992		1423
993	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	1424	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
…		…
995	=over 4	1426	=over 4
996		1427
997	=item $fileno = IO::AIO::poll_fileno	1428	=item $fileno = IO::AIO::poll_fileno
998		1429
999	Return the I<request result pipe file descriptor>. This filehandle must be	1430	Return the I<request result pipe file descriptor>. This filehandle must be
1000	polled for reading by some mechanism outside this module (e.g. Event or	1431	polled for reading by some mechanism outside this module (e.g. EV, Glib,
1001	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1432	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
1002	to call C<poll_cb> to check the results.	1433	you have to call C<poll_cb> to check the results.
1003		1434
1004	See C<poll_cb> for an example.	1435	See C<poll_cb> for an example.
1005		1436
1006	=item IO::AIO::poll_cb	1437	=item IO::AIO::poll_cb
1007		1438
1008	Process some outstanding events on the result pipe. You have to call this	1439	Process some outstanding events on the result pipe. You have to call
1009	regularly. Returns the number of events processed. Returns immediately	1440	this regularly. Returns C<0> if all events could be processed (or there
1010	when no events are outstanding. The amount of events processed depends on	1441	were no events to process), or C<-1> if it returned earlier for whatever
1011	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.	1442	reason. Returns immediately when no events are outstanding. The amount of
		1443	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1444	C<IO::AIO::max_poll_time>.
1012		1445
1013	If not all requests were processed for whatever reason, the filehandle	1446	If not all requests were processed for whatever reason, the filehandle
1014	will still be ready when C<poll_cb> returns.	1447	will still be ready when C<poll_cb> returns, so normally you don't have to
		1448	do anything special to have it called later.
		1449
		1450	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1451	ready, it can be beneficial to call this function from loops which submit
		1452	a lot of requests, to make sure the results get processed when they become
		1453	available and not just when the loop is finished and the event loop takes
		1454	over again. This function returns very fast when there are no outstanding
		1455	requests.
1015		1456
1016	Example: Install an Event watcher that automatically calls	1457	Example: Install an Event watcher that automatically calls
1017	IO::AIO::poll_cb with high priority:	1458	IO::AIO::poll_cb with high priority (more examples can be found in the
		1459	SYNOPSIS section, at the top of this document):
1018		1460
1019	Event->io (fd => IO::AIO::poll_fileno,	1461	Event->io (fd => IO::AIO::poll_fileno,
1020	poll => 'r', async => 1,	1462	poll => 'r', async => 1,
1021	cb => \&IO::AIO::poll_cb);	1463	cb => \&IO::AIO::poll_cb);
		1464
		1465	=item IO::AIO::poll_wait
		1466
		1467	If there are any outstanding requests and none of them in the result
		1468	phase, wait till the result filehandle becomes ready for reading (simply
		1469	does a C<select> on the filehandle. This is useful if you want to
		1470	synchronously wait for some requests to finish).
		1471
		1472	See C<nreqs> for an example.
		1473
		1474	=item IO::AIO::poll
		1475
		1476	Waits until some requests have been handled.
		1477
		1478	Returns the number of requests processed, but is otherwise strictly
		1479	equivalent to:
		1480
		1481	IO::AIO::poll_wait, IO::AIO::poll_cb
		1482
		1483	=item IO::AIO::flush
		1484
		1485	Wait till all outstanding AIO requests have been handled.
		1486
		1487	Strictly equivalent to:
		1488
		1489	IO::AIO::poll_wait, IO::AIO::poll_cb
		1490	while IO::AIO::nreqs;
1022		1491
1023	=item IO::AIO::max_poll_reqs $nreqs	1492	=item IO::AIO::max_poll_reqs $nreqs
1024		1493
1025	=item IO::AIO::max_poll_time $seconds	1494	=item IO::AIO::max_poll_time $seconds
1026		1495
…		…
1051	# use a low priority so other tasks have priority	1520	# use a low priority so other tasks have priority
1052	Event->io (fd => IO::AIO::poll_fileno,	1521	Event->io (fd => IO::AIO::poll_fileno,
1053	poll => 'r', nice => 1,	1522	poll => 'r', nice => 1,
1054	cb => &IO::AIO::poll_cb);	1523	cb => &IO::AIO::poll_cb);
1055		1524
1056	=item IO::AIO::poll_wait
1057
1058	If there are any outstanding requests and none of them in the result
1059	phase, wait till the result filehandle becomes ready for reading (simply
1060	does a C<select> on the filehandle. This is useful if you want to
1061	synchronously wait for some requests to finish).
1062
1063	See C<nreqs> for an example.
1064
1065	=item IO::AIO::poll
1066
1067	Waits until some requests have been handled.
1068
1069	Returns the number of requests processed, but is otherwise strictly
1070	equivalent to:
1071
1072	IO::AIO::poll_wait, IO::AIO::poll_cb
1073
1074	=item IO::AIO::flush
1075
1076	Wait till all outstanding AIO requests have been handled.
1077
1078	Strictly equivalent to:
1079
1080	IO::AIO::poll_wait, IO::AIO::poll_cb
1081	while IO::AIO::nreqs;
1082
1083	=back	1525	=back
1084		1526
1085	=head3 CONTROLLING THE NUMBER OF THREADS	1527	=head3 CONTROLLING THE NUMBER OF THREADS
1086		1528
1087	=over	1529	=over
…		…
1120		1562
1121	Under normal circumstances you don't need to call this function.	1563	Under normal circumstances you don't need to call this function.
1122		1564
1123	=item IO::AIO::max_idle $nthreads	1565	=item IO::AIO::max_idle $nthreads
1124		1566
1125	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	1567	Limit the number of threads (default: 4) that are allowed to idle
1126	threads that did not get a request to process within 10 seconds). That	1568	(i.e., threads that did not get a request to process within the idle
1127	means if a thread becomes idle while C<$nthreads> other threads are also	1569	timeout (default: 10 seconds). That means if a thread becomes idle while
1128	idle, it will free its resources and exit.	1570	C<$nthreads> other threads are also idle, it will free its resources and
		1571	exit.
1129		1572
1130	This is useful when you allow a large number of threads (e.g. 100 or 1000)	1573	This is useful when you allow a large number of threads (e.g. 100 or 1000)
1131	to allow for extremely high load situations, but want to free resources	1574	to allow for extremely high load situations, but want to free resources
1132	under normal circumstances (1000 threads can easily consume 30MB of RAM).	1575	under normal circumstances (1000 threads can easily consume 30MB of RAM).
1133		1576
1134	The default is probably ok in most situations, especially if thread	1577	The default is probably ok in most situations, especially if thread
1135	creation is fast. If thread creation is very slow on your system you might	1578	creation is fast. If thread creation is very slow on your system you might
1136	want to use larger values.	1579	want to use larger values.
1137		1580
		1581	=item IO::AIO::idle_timeout $seconds
		1582
		1583	Sets the minimum idle timeout (default 10) after which worker threads are
		1584	allowed to exit. SEe C<IO::AIO::max_idle>.
		1585
1138	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1586	=item IO::AIO::max_outstanding $maxreqs
		1587
		1588	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1589	you do queue up more than this number of requests, the next call to
		1590	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1591	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1592	longer exceeded.
		1593
		1594	In other words, this setting does not enforce a queue limit, but can be
		1595	used to make poll functions block if the limit is exceeded.
1139		1596
1140	This is a very bad function to use in interactive programs because it	1597	This is a very bad function to use in interactive programs because it
1141	blocks, and a bad way to reduce concurrency because it is inexact: Better	1598	blocks, and a bad way to reduce concurrency because it is inexact: Better
1142	use an C<aio_group> together with a feed callback.	1599	use an C<aio_group> together with a feed callback.
1143		1600
1144	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1601	It's main use is in scripts without an event loop - when you want to stat
1145	to queue up more than this number of requests, the next call to the	1602	a lot of files, you can write somehting like this:
1146	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
1147	function will block until the limit is no longer exceeded.
1148		1603
1149	The default value is very large, so there is no practical limit on the	1604	IO::AIO::max_outstanding 32;
1150	number of outstanding requests.
1151		1605
1152	You can still queue as many requests as you want. Therefore,	1606	for my $path (...) {
1153	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1607	aio_stat $path , ...;
1154	as a stop gap to shield against fatal memory overflow (with large values).	1608	IO::AIO::poll_cb;
		1609	}
		1610
		1611	IO::AIO::flush;
		1612
		1613	The call to C<poll_cb> inside the loop will normally return instantly, but
		1614	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1615	some requests have been handled. This keeps the loop from pushing a large
		1616	number of C<aio_stat> requests onto the queue.
		1617
		1618	The default value for C<max_outstanding> is very large, so there is no
		1619	practical limit on the number of outstanding requests.
1155		1620
1156	=back	1621	=back
1157		1622
1158	=head3 STATISTICAL INFORMATION	1623	=head3 STATISTICAL INFORMATION
1159		1624
…		…
1179	Returns the number of requests currently in the pending state (executed,	1644	Returns the number of requests currently in the pending state (executed,
1180	but not yet processed by poll_cb).	1645	but not yet processed by poll_cb).
1181		1646
1182	=back	1647	=back
1183		1648
		1649	=head3 MISCELLANEOUS FUNCTIONS
		1650
		1651	IO::AIO implements some functions that might be useful, but are not
		1652	asynchronous.
		1653
		1654	=over 4
		1655
		1656	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1657
		1658	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1659	but is blocking (this makes most sense if you know the input data is
		1660	likely cached already and the output filehandle is set to non-blocking
		1661	operations).
		1662
		1663	Returns the number of bytes copied, or C<-1> on error.
		1664
		1665	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1666
		1667	Simply calls the C<posix_fadvise> function (see its
		1668	manpage for details). The following advice constants are
		1669	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1670	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1671	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1672
		1673	On systems that do not implement C<posix_fadvise>, this function returns
		1674	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1675
		1676	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1677
		1678	Simply calls the C<posix_madvise> function (see its
		1679	manpage for details). The following advice constants are
		1680	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1681	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1682
		1683	On systems that do not implement C<posix_madvise>, this function returns
		1684	ENOSYS, otherwise the return value of C<posix_madvise>.
		1685
		1686	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1687
		1688	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1689	$scalar (see its manpage for details). The following protect
		1690	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1691	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1692
		1693	On systems that do not implement C<mprotect>, this function returns
		1694	ENOSYS, otherwise the return value of C<mprotect>.
		1695
		1696	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1697
		1698	Memory-maps a file (or anonymous memory range) and attaches it to the
		1699	given C<$scalar>, which will act like a string scalar.
		1700
		1701	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1702	change the string length, and most read-only operations such as copying it
		1703	or searching it with regexes and so on.
		1704
		1705	Anything else is unsafe and will, at best, result in memory leaks.
		1706
		1707	The memory map associated with the C<$scalar> is automatically removed
		1708	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1709	C<IO::AIO::munmap> functions are called.
		1710
		1711	This calls the C<mmap>(2) function internally. See your system's manual
		1712	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1713
		1714	The C<$length> must be larger than zero and smaller than the actual
		1715	filesize.
		1716
		1717	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1718	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1719
		1720	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1721	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1722	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1723	(which is set to C<MAP_ANON> if your system only provides this
		1724	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1725	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1726	C<IO::AIO::MAP_NONBLOCK>
		1727
		1728	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1729
		1730	C<$offset> is the offset from the start of the file - it generally must be
		1731	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1732
		1733	Example:
		1734
		1735	use Digest::MD5;
		1736	use IO::AIO;
		1737
		1738	open my $fh, "<verybigfile"
		1739	or die "$!";
		1740
		1741	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1742	or die "verybigfile: $!";
		1743
		1744	my $fast_md5 = md5 $data;
		1745
		1746	=item IO::AIO::munmap $scalar
		1747
		1748	Removes a previous mmap and undefines the C<$scalar>.
		1749
		1750	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1751
		1752	Calls the C<munlock> function, undoing the effects of a previous
		1753	C<aio_mlock> call (see its description for details).
		1754
		1755	=item IO::AIO::munlockall
		1756
		1757	Calls the C<munlockall> function.
		1758
		1759	On systems that do not implement C<munlockall>, this function returns
		1760	ENOSYS, otherwise the return value of C<munlockall>.
		1761
		1762	=back
		1763
1184	=cut	1764	=cut
1185		1765
1186	# support function to convert a fd into a perl filehandle
1187	sub _fd2fh {
1188	return undef if $_[0] < 0;
1189
1190	# try to generate nice filehandles
1191	my $sym = "IO::AIO::fd#$_[0]";
1192	local *$sym;
1193
1194	open *$sym, "+<&=$_[0]" # usually works under any unix
1195	or open *$sym, "<&=$_[0]" # cygwin needs this
1196	or open *$sym, ">&=$_[0]" # or this
1197	or return undef;
1198
1199	*$sym
1200	}
1201
1202	min_parallel 8;	1766	min_parallel 8;
1203		1767
1204	END { flush }	1768	END { flush }
1205		1769
1206	1;	1770	1;
1207		1771
		1772	=head1 EVENT LOOP INTEGRATION
		1773
		1774	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1775	automatically into many event loops:
		1776
		1777	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1778	use AnyEvent::AIO;
		1779
		1780	You can also integrate IO::AIO manually into many event loops, here are
		1781	some examples of how to do this:
		1782
		1783	# EV integration
		1784	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1785
		1786	# Event integration
		1787	Event->io (fd => IO::AIO::poll_fileno,
		1788	poll => 'r',
		1789	cb => \&IO::AIO::poll_cb);
		1790
		1791	# Glib/Gtk2 integration
		1792	add_watch Glib::IO IO::AIO::poll_fileno,
		1793	in => sub { IO::AIO::poll_cb; 1 };
		1794
		1795	# Tk integration
		1796	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1797	readable => \&IO::AIO::poll_cb);
		1798
		1799	# Danga::Socket integration
		1800	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1801	\&IO::AIO::poll_cb);
		1802
1208	=head2 FORK BEHAVIOUR	1803	=head2 FORK BEHAVIOUR
1209		1804
1210	This module should do "the right thing" when the process using it forks:	1805	Usage of pthreads in a program changes the semantics of fork
		1806	considerably. Specifically, only async-safe functions can be called after
		1807	fork. Perl doesn't know about this, so in general, you cannot call fork
		1808	with defined behaviour in perl. IO::AIO uses pthreads, so this applies,
		1809	but many other extensions and (for inexplicable reasons) perl itself often
		1810	is linked against pthreads, so this limitation applies.
1211		1811
1212	Before the fork, IO::AIO enters a quiescent state where no requests	1812	Some operating systems have extensions that allow safe use of fork, and
1213	can be added in other threads and no results will be processed. After	1813	this module should do "the right thing" on those, and tries on others. At
1214	the fork the parent simply leaves the quiescent state and continues	1814	the time of this writing (2011) only GNU/Linux supports these extensions
1215	request/result processing, while the child frees the request/result queue	1815	to POSIX.
1216	(so that the requests started before the fork will only be handled in the
1217	parent). Threads will be started on demand until the limit set in the
1218	parent process has been reached again.
1219
1220	In short: the parent will, after a short pause, continue as if fork had
1221	not been called, while the child will act as if IO::AIO has not been used
1222	yet.
1223		1816
1224	=head2 MEMORY USAGE	1817	=head2 MEMORY USAGE
1225		1818
1226	Per-request usage:	1819	Per-request usage:
1227		1820
…		…
1229	bytes of memory. In addition, stat requests need a stat buffer (possibly	1822	bytes of memory. In addition, stat requests need a stat buffer (possibly
1230	a few hundred bytes), readdir requires a result buffer and so on. Perl	1823	a few hundred bytes), readdir requires a result buffer and so on. Perl
1231	scalars and other data passed into aio requests will also be locked and	1824	scalars and other data passed into aio requests will also be locked and
1232	will consume memory till the request has entered the done state.	1825	will consume memory till the request has entered the done state.
1233		1826
1234	This is now awfully much, so queuing lots of requests is not usually a	1827	This is not awfully much, so queuing lots of requests is not usually a
1235	problem.	1828	problem.
1236		1829
1237	Per-thread usage:	1830	Per-thread usage:
1238		1831
1239	In the execution phase, some aio requests require more memory for	1832	In the execution phase, some aio requests require more memory for
…		…
1244		1837
1245	Known bugs will be fixed in the next release.	1838	Known bugs will be fixed in the next release.
1246		1839
1247	=head1 SEE ALSO	1840	=head1 SEE ALSO
1248		1841
1249	L<Coro::AIO>.	1842	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1843	more natural syntax.
1250		1844
1251	=head1 AUTHOR	1845	=head1 AUTHOR
1252		1846
1253	Marc Lehmann <schmorp@schmorp.de>	1847	Marc Lehmann <schmorp@schmorp.de>
1254	http://home.schmorp.de/	1848	http://home.schmorp.de/

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