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Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC vs.
Revision 1.201 by root, Tue Jul 5 09:24:11 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) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
25	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
26		27
27	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
28	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
29		30
30	# AnyEvent integration
31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
33
34	# Event integration
35	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',
37	cb => \&IO::AIO::poll_cb);
38
39	# Glib/Gtk2 integration
40	add_watch Glib::IO IO::AIO::poll_fileno,
41	in => sub { IO::AIO::poll_cb; 1 };
42
43	# Tk integration
44	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
45	readable => \&IO::AIO::poll_cb);
46
47	# Danga::Socket integration
48	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
49	\&IO::AIO::poll_cb);
50
51	=head1 DESCRIPTION	31	=head1 DESCRIPTION
52		32
53	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
54	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>).
		36
		37	Asynchronous means that operations that can normally block your program
		38	(e.g. reading from disk) will be done asynchronously: the operation
		39	will still block, but you can do something else in the meantime. This
		40	is extremely useful for programs that need to stay interactive even
		41	when doing heavy I/O (GUI programs, high performance network servers
		42	etc.), but can also be used to easily do operations in parallel that are
		43	normally done sequentially, e.g. stat'ing many files, which is much faster
		44	on a RAID volume or over NFS when you do a number of stat operations
		45	concurrently.
		46
		47	While most of this works on all types of file descriptors (for
		48	example sockets), using these functions on file descriptors that
		49	support nonblocking operation (again, sockets, pipes etc.) is
		50	very inefficient. Use an event loop for that (such as the L<EV>
		51	module): IO::AIO will naturally fit into such an event loop itself.
55		52
56	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
57	requests and signal their completion. You don't need thread support	54	requests and signal their completion. You don't need thread support
58	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
59	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
60	functions available on many operating systems. However, they are often	57	functions available on many operating systems. However, they are often
61	not well-supported or restricted (Linux doesn't allow them on normal	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	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
63	aio_write, so the remaining functionality would have to be implemented	60	aio_write, so the remaining functionality would have to be implemented
64	using threads anyway.	61	using threads anyway.
65		62
66	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,
67	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
68	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
69	never call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
		67
		68	=head2 EXAMPLE
		69
		70	This is a simple example that uses the EV module and loads
		71	F</etc/passwd> asynchronously:
		72
		73	use Fcntl;
		74	use EV;
		75	use IO::AIO;
		76
		77	# register the IO::AIO callback with EV
		78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		79
		80	# queue the request to open /etc/passwd
		81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
		82	my $fh = shift
		83	or die "error while opening: $!";
		84
		85	# stat'ing filehandles is generally non-blocking
		86	my $size = -s $fh;
		87
		88	# queue a request to read the file
		89	my $contents;
		90	aio_read $fh, 0, $size, $contents, 0, sub {
		91	$_[0] == $size
		92	or die "short read: $!";
		93
		94	close $fh;
		95
		96	# file contents now in $contents
		97	print $contents;
		98
		99	# exit event loop and program
		100	EV::unloop;
		101	};
		102	};
		103
		104	# possibly queue up other requests, or open GUI windows,
		105	# check for sockets etc. etc.
		106
		107	# process events as long as there are some:
		108	EV::loop;
70		109
71	=head1 REQUEST ANATOMY AND LIFETIME	110	=head1 REQUEST ANATOMY AND LIFETIME
72		111
73	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
74	directly visible to Perl.	113	directly visible to Perl.
…		…
116	Request has reached the end of its lifetime and holds no resources anymore	155	Request has reached the end of its lifetime and holds no resources anymore
117	(except possibly for the Perl object, but its connection to the actual	156	(except possibly for the Perl object, but its connection to the actual
118	aio request is severed and calling its methods will either do nothing or	157	aio request is severed and calling its methods will either do nothing or
119	result in a runtime error).	158	result in a runtime error).
120		159
		160	=back
		161
121	=cut	162	=cut
122		163
123	package IO::AIO;	164	package IO::AIO;
124		165
125	no warnings;	166	use Carp ();
126	use strict 'vars';	167
		168	use common::sense;
127		169
128	use base 'Exporter';	170	use base 'Exporter';
129		171
130	BEGIN {	172	BEGIN {
131	our $VERSION = '2.0';	173	our $VERSION = '3.93';
132		174
133	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
134	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
135	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	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
		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
136	aio_group aio_nop);	183	aio_statvfs);
		184
137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139	min_parallel max_parallel nreqs nready npending);	187	min_parallel max_parallel max_idle idle_timeout
		188	nreqs nready npending nthreads
		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
140		194
141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142		196
143	require XSLoader;	197	require XSLoader;
144	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
145	}	199	}
146		200
147	=head1 FUNCTIONS	201	=head1 FUNCTIONS
148		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, $length = undef
		275	IO::AIO::munlockall
		276
149	=head2 AIO FUNCTIONS	277	=head2 AIO REQUEST FUNCTIONS
150		278
151	All the C<aio_*> calls are more or less thin wrappers around the syscall	279	All the C<aio_*> calls are more or less thin wrappers around the syscall
152	with the same name (sans C<aio_>). The arguments are similar or identical,	280	with the same name (sans C<aio_>). The arguments are similar or identical,
153	and they all accept an additional (and optional) C<$callback> argument	281	and they all accept an additional (and optional) C<$callback> argument
154	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
155	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
156	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
157	syscall has been executed asynchronously.	285	syscall has been executed asynchronously.
158		286
159	All functions expecting a filehandle keep a copy of the filehandle	287	All functions expecting a filehandle keep a copy of the filehandle
160	internally until the request has finished.	288	internally until the request has finished.
161		289
162	All requests return objects of type L<IO::AIO::REQ> that allow further	290	All functions return request objects of type L<IO::AIO::REQ> that allow
163	manipulation of those requests while they are in-flight.	291	further manipulation of those requests while they are in-flight.
164		292
165	The pathnames you pass to these routines I<must> be absolute and	293	The pathnames you pass to these routines I<must> be absolute and
166	encoded in byte form. The reason for the former is that at the time the	294	encoded as octets. The reason for the former is that at the time the
167	request is being executed, the current working directory could have	295	request is being executed, the current working directory could have
168	changed. Alternatively, you can make sure that you never change the	296	changed. Alternatively, you can make sure that you never change the
169	current working directory.	297	current working directory anywhere in the program and then use relative
		298	paths.
170		299
171	To encode pathnames to byte form, either make sure you either: a)	300	To encode pathnames as octets, either make sure you either: a) always pass
172	always pass in filenames you got from outside (command line, readdir	301	in filenames you got from outside (command line, readdir etc.) without
173	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	302	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
174	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
175	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)
176	use something else.	305	use something else to ensure your scalar has the correct contents.
		306
		307	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		308	handles correctly whether it is set or not.
177		309
178	=over 4	310	=over 4
179		311
180	=item $prev_pri = aioreq_pri [$pri]	312	=item $prev_pri = aioreq_pri [$pri]
181		313
…		…
201	aio_read $_[0], ..., sub {	333	aio_read $_[0], ..., sub {
202	...	334	...
203	};	335	};
204	};	336	};
205		337
		338
206	=item aioreq_nice $pri_adjust	339	=item aioreq_nice $pri_adjust
207		340
208	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
209	priority, so effects are cumulative.	342	priority, so the effect is cumulative.
		343
210		344
211	=item aio_open $pathname, $flags, $mode, $callback->($fh)	345	=item aio_open $pathname, $flags, $mode, $callback->($fh)
212		346
213	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
214	created filehandle for the file.	348	created filehandle for the file.
…		…
220	list. They are the same as used by C<sysopen>.	354	list. They are the same as used by C<sysopen>.
221		355
222	Likewise, C<$mode> specifies the mode of the newly created file, if it	356	Likewise, C<$mode> specifies the mode of the newly created file, if it
223	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	357	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
224	except that it is mandatory (i.e. use C<0> if you don't create new files,	358	except that it is mandatory (i.e. use C<0> if you don't create new files,
225	and C<0666> or C<0777> if you do).	359	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		360	by the umask in effect then the request is being executed, so better never
		361	change the umask.
226		362
227	Example:	363	Example:
228		364
229	aio_open "/etc/passwd", O_RDONLY, 0, sub {	365	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
230	if ($_[0]) {	366	if ($_[0]) {
231	print "open successful, fh is $_[0]\n";	367	print "open successful, fh is $_[0]\n";
232	...	368	...
233	} else {	369	} else {
234	die "open failed: $!\n";	370	die "open failed: $!\n";
235	}	371	}
236	};	372	};
237		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
238	=item aio_close $fh, $callback->($status)	384	=item aio_close $fh, $callback->($status)
239		385
240	Asynchronously close a file and call the callback with the result	386	Asynchronously close a file and call the callback with the result
241	code. I<WARNING:> although accepted, you should not pass in a perl	387	code.
242	filehandle here, as perl will likely close the file descriptor another
243	time when the filehandle is destroyed. Normally, you can safely call perls
244	C<close> or just let filehandles go out of scope.
245		388
246	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
247	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
248		400
249	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	401	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250		402
251	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	403	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252		404
253	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
254	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<$dataoffset>
255	callback without the actual number of bytes read (or -1 on error, just	407	and calls the callback without the actual number of bytes read (or -1 on
256	like the syscall).	408	error, just like the syscall).
		409
		410	C<aio_read> will, like C<sysread>, shrink or grow the C<$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<$data>.
257		422
258	The C<$data> scalar I<MUST NOT> be modified in any way while the request	423	The C<$data> scalar I<MUST NOT> be modified in any way while the request
259	is outstanding. Modifying it can result in segfaults or WW3 (if the	424	is outstanding. Modifying it can result in segfaults or World War III (if
260	necessary/optional hardware is installed).	425	the necessary/optional hardware is installed).
261		426
262	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	427	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263	offset C<0> within the scalar:	428	offset C<0> within the scalar:
264		429
265	aio_read $fh, 7, 15, $buffer, 0, sub {	430	aio_read $fh, 7, 15, $buffer, 0, sub {
266	$_[0] > 0 or die "read error: $!";	431	$_[0] > 0 or die "read error: $!";
267	print "read $_[0] bytes: <$buffer>\n";	432	print "read $_[0] bytes: <$buffer>\n";
268	};	433	};
269		434
270	=item aio_move $srcpath, $dstpath, $callback->($status)
271
272	Try to move the I<file> (directories not supported as either source or
273	destination) from C<$srcpath> to C<$dstpath> and call the callback with
274	the C<0> (error) or C<-1> ok.
275
276	This is a composite request that tries to rename(2) the file first. If
277	rename files with C<EXDEV>, it creates the destination file with mode 0200
278	and copies the contents of the source file into it using C<aio_sendfile>,
279	followed by restoring atime, mtime, access mode and uid/gid, in that
280	order, and unlinking the C<$srcpath>.
281
282	If an error occurs, the partial destination file will be unlinked, if
283	possible, except when setting atime, mtime, access mode and uid/gid, where
284	errors are being ignored.
285
286	=cut
287
288	sub aio_move($$$) {
289	my ($src, $dst, $cb) = @_;
290
291	my $pri = aioreq_pri;
292	my $grp = aio_group $cb;
293
294	aioreq_pri $pri;
295	add $grp aio_rename $src, $dst, sub {
296	if ($_[0] && $! == EXDEV) {
297	aioreq_pri $pri;
298	add $grp aio_open $src, O_RDONLY, 0, sub {
299	if (my $src_fh = $_[0]) {
300	my @stat = stat $src_fh;
301
302	aioreq_pri $pri;
303	add $grp aio_open $dst, O_WRONLY, 0200, sub {
304	if (my $dst_fh = $_[0]) {
305	aioreq_pri $pri;
306	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
307	close $src_fh;
308
309	if ($_[0] == $stat[7]) {
310	utime $stat[8], $stat[9], $dst;
311	chmod $stat[2] & 07777, $dst_fh;
312	chown $stat[4], $stat[5], $dst_fh;
313	close $dst_fh;
314
315	aioreq_pri $pri;
316	add $grp aio_unlink $src, sub {
317	$grp->result ($_[0]);
318	};
319	} else {
320	my $errno = $!;
321	aioreq_pri $pri;
322	add $grp aio_unlink $dst, sub {
323	$! = $errno;
324	$grp->result (-1);
325	};
326	}
327	};
328	} else {
329	$grp->result (-1);
330	}
331	},
332
333	} else {
334	$grp->result (-1);
335	}
336	};
337	} else {
338	$grp->result ($_[0]);
339	}
340	};
341
342	$grp
343	}
344		435
345	=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)
346		437
347	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
348	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
349	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
350	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
351	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>.
352		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
353	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
354	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
355	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.
356		464
357	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>,
358	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
359	regardless of the limitations of the operating system.	468	type of filehandle regardless of the limitations of the operating system.
360		469
361	Please note, however, that C<aio_sendfile> can read more bytes from	470	As native sendfile syscalls (as practically any non-POSIX interface hacked
362	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
363	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
364	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,
365	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> -
366	read.	475	fewre bytes than expected might have been transferred.
		476
367		477
368	=item aio_readahead $fh,$offset,$length, $callback->($retval)	478	=item aio_readahead $fh,$offset,$length, $callback->($retval)
369		479
370	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
371	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>
…		…
377	file. The current file offset of the file is left unchanged.	487	file. The current file offset of the file is left unchanged.
378		488
379	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
380	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.
381		491
		492
382	=item aio_stat $fh_or_path, $callback->($status)	493	=item aio_stat $fh_or_path, $callback->($status)
383		494
384	=item aio_lstat $fh, $callback->($status)	495	=item aio_lstat $fh, $callback->($status)
385		496
386	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
…		…
391	for an explanation.	502	for an explanation.
392		503
393	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
394	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
395	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>.
396		516
397	Example: Print the length of F</etc/passwd>:	517	Example: Print the length of F</etc/passwd>:
398		518
399	aio_stat "/etc/passwd", sub {	519	aio_stat "/etc/passwd", sub {
400	$_[0] and die "stat failed: $!";	520	$_[0] and die "stat failed: $!";
401	print "size is ", -s _, "\n";	521	print "size is ", -s _, "\n";
402	};	522	};
403		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
404	=item aio_unlink $pathname, $callback->($status)	611	=item aio_unlink $pathname, $callback->($status)
405		612
406	Asynchronously unlink (delete) a file and call the callback with the	613	Asynchronously unlink (delete) a file and call the callback with the
407	result code.	614	result code.
408		615
		616
		617	=item aio_mknod $path, $mode, $dev, $callback->($status)
		618
		619	[EXPERIMENTAL]
		620
		621	Asynchronously create a device node (or fifo). See mknod(2).
		622
		623	The only (POSIX-) portable way of calling this function is:
		624
		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.
		629
409	=item aio_link $srcpath, $dstpath, $callback->($status)	630	=item aio_link $srcpath, $dstpath, $callback->($status)
410		631
411	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
412	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.
413		634
		635
414	=item aio_symlink $srcpath, $dstpath, $callback->($status)	636	=item aio_symlink $srcpath, $dstpath, $callback->($status)
415		637
416	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
417	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.
418		640
		641
		642	=item aio_readlink $path, $callback->($link)
		643
		644	Asynchronously read the symlink specified by C<$path> and pass it to
		645	the callback. If an error occurs, nothing or undef gets passed to the
		646	callback.
		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.
		653
		654	This request can be used to get the absolute path of the current working
		655	directory by passing it a path of F<.> (a single dot).
		656
		657
419	=item aio_rename $srcpath, $dstpath, $callback->($status)	658	=item aio_rename $srcpath, $dstpath, $callback->($status)
420		659
421	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	660	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
422	rename(2) and call the callback with the result code.	661	rename(2) and call the callback with the result code.
423		662
		663
		664	=item aio_mkdir $pathname, $mode, $callback->($status)
		665
		666	Asynchronously mkdir (create) a directory and call the callback with
		667	the result code. C<$mode> will be modified by the umask at the time the
		668	request is executed, so do not change your umask.
		669
		670
424	=item aio_rmdir $pathname, $callback->($status)	671	=item aio_rmdir $pathname, $callback->($status)
425		672
426	Asynchronously rmdir (delete) a directory and call the callback with the	673	Asynchronously rmdir (delete) a directory and call the callback with the
427	result code.	674	result code.
		675
428		676
429	=item aio_readdir $pathname, $callback->($entries)	677	=item aio_readdir $pathname, $callback->($entries)
430		678
431	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	679	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
432	directory (i.e. opendir + readdir + closedir). The entries will not be	680	directory (i.e. opendir + readdir + closedir). The entries will not be
433	sorted, and will B<NOT> include the C<.> and C<..> entries.	681	sorted, and will B<NOT> include the C<.> and C<..> entries.
434		682
435	The callback a single argument which is either C<undef> or an array-ref	683	The callback is passed a single argument which is either C<undef> or an
436	with the filenames.	684	array-ref with the filenames.
		685
		686
		687	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		688
		689	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		690	behaviour and output format. In case of an error, C<$entries> will be
		691	C<undef>.
		692
		693	The flags are a combination of the following constants, ORed together (the
		694	flags will also be passed to the callback, possibly modified):
		695
		696	=over 4
		697
		698	=item IO::AIO::READDIR_DENTS
		699
		700	When this flag is off, then the callback gets an arrayref consisting of
		701	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		702	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		703	entry in more detail.
		704
		705	C<$name> is the name of the entry.
		706
		707	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		708
		709	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		710	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		711	C<IO::AIO::DT_WHT>.
		712
		713	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		714	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		715	scalars are read-only: you can not modify them.
		716
		717	C<$inode> is the inode number (which might not be exact on systems with 64
		718	bit inode numbers and 32 bit perls). This field has unspecified content on
		719	systems that do not deliver the inode information.
		720
		721	=item IO::AIO::READDIR_DIRS_FIRST
		722
		723	When this flag is set, then the names will be returned in an order where
		724	likely directories come first, in optimal stat order. This is useful when
		725	you need to quickly find directories, or you want to find all directories
		726	while avoiding to stat() each entry.
		727
		728	If the system returns type information in readdir, then this is used
		729	to find directories directly. Otherwise, likely directories are names
		730	beginning with ".", or otherwise names with no dots, of which names with
		731	short names are tried first.
		732
		733	=item IO::AIO::READDIR_STAT_ORDER
		734
		735	When this flag is set, then the names will be returned in an order
		736	suitable for stat()'ing each one. That is, when you plan to stat()
		737	all files in the given directory, then the returned order will likely
		738	be fastest.
		739
		740	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		741	the likely dirs come first, resulting in a less optimal stat order.
		742
		743	=item IO::AIO::READDIR_FOUND_UNKNOWN
		744
		745	This flag should not be set when calling C<aio_readdirx>. Instead, it
		746	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		747	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		748	C<$type>'s are known, which can be used to speed up some algorithms.
		749
		750	=back
		751
		752
		753	=item aio_load $path, $data, $callback->($status)
		754
		755	This is a composite request that tries to fully load the given file into
		756	memory. Status is the same as with aio_read.
		757
		758	=cut
		759
		760	sub aio_load($$;$) {
		761	my ($path, undef, $cb) = @_;
		762	my $data = \$_[1];
		763
		764	my $pri = aioreq_pri;
		765	my $grp = aio_group $cb;
		766
		767	aioreq_pri $pri;
		768	add $grp aio_open $path, O_RDONLY, 0, sub {
		769	my $fh = shift
		770	or return $grp->result (-1);
		771
		772	aioreq_pri $pri;
		773	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		774	$grp->result ($_[0]);
		775	};
		776	};
		777
		778	$grp
		779	}
		780
		781	=item aio_copy $srcpath, $dstpath, $callback->($status)
		782
		783	Try to copy the I<file> (directories not supported as either source or
		784	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		785	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		786
		787	This is a composite request that creates the destination file with
		788	mode 0200 and copies the contents of the source file into it using
		789	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		790	uid/gid, in that order.
		791
		792	If an error occurs, the partial destination file will be unlinked, if
		793	possible, except when setting atime, mtime, access mode and uid/gid, where
		794	errors are being ignored.
		795
		796	=cut
		797
		798	sub aio_copy($$;$) {
		799	my ($src, $dst, $cb) = @_;
		800
		801	my $pri = aioreq_pri;
		802	my $grp = aio_group $cb;
		803
		804	aioreq_pri $pri;
		805	add $grp aio_open $src, O_RDONLY, 0, sub {
		806	if (my $src_fh = $_[0]) {
		807	my @stat = stat $src_fh; # hmm, might block over nfs?
		808
		809	aioreq_pri $pri;
		810	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		811	if (my $dst_fh = $_[0]) {
		812	aioreq_pri $pri;
		813	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		814	if ($_[0] == $stat[7]) {
		815	$grp->result (0);
		816	close $src_fh;
		817
		818	my $ch = sub {
		819	aioreq_pri $pri;
		820	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		821	aioreq_pri $pri;
		822	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		823	aioreq_pri $pri;
		824	add $grp aio_close $dst_fh;
		825	}
		826	};
		827	};
		828
		829	aioreq_pri $pri;
		830	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		831	if ($_[0] < 0 && $! == ENOSYS) {
		832	aioreq_pri $pri;
		833	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		834	} else {
		835	$ch->();
		836	}
		837	};
		838	} else {
		839	$grp->result (-1);
		840	close $src_fh;
		841	close $dst_fh;
		842
		843	aioreq $pri;
		844	add $grp aio_unlink $dst;
		845	}
		846	};
		847	} else {
		848	$grp->result (-1);
		849	}
		850	},
		851
		852	} else {
		853	$grp->result (-1);
		854	}
		855	};
		856
		857	$grp
		858	}
		859
		860	=item aio_move $srcpath, $dstpath, $callback->($status)
		861
		862	Try to move the I<file> (directories not supported as either source or
		863	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		864	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		865
		866	This is a composite request that tries to rename(2) the file first; if
		867	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		868	that is successful, unlinks the C<$srcpath>.
		869
		870	=cut
		871
		872	sub aio_move($$;$) {
		873	my ($src, $dst, $cb) = @_;
		874
		875	my $pri = aioreq_pri;
		876	my $grp = aio_group $cb;
		877
		878	aioreq_pri $pri;
		879	add $grp aio_rename $src, $dst, sub {
		880	if ($_[0] && $! == EXDEV) {
		881	aioreq_pri $pri;
		882	add $grp aio_copy $src, $dst, sub {
		883	$grp->result ($_[0]);
		884
		885	unless ($_[0]) {
		886	aioreq_pri $pri;
		887	add $grp aio_unlink $src;
		888	}
		889	};
		890	} else {
		891	$grp->result ($_[0]);
		892	}
		893	};
		894
		895	$grp
		896	}
437		897
438	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	898	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
439		899
440	Scans a directory (similar to C<aio_readdir>) but additionally tries to	900	Scans a directory (similar to C<aio_readdir>) but additionally tries to
441	efficiently separate the entries of directory C<$path> into two sets of	901	efficiently separate the entries of directory C<$path> into two sets of
…		…
460		920
461	Implementation notes.	921	Implementation notes.
462		922
463	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	923	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
464		924
		925	If readdir returns file type information, then this is used directly to
		926	find directories.
		927
465	After reading the directory, the modification time, size etc. of the	928	Otherwise, after reading the directory, the modification time, size etc.
466	directory before and after the readdir is checked, and if they match (and	929	of the directory before and after the readdir is checked, and if they
467	isn't the current time), the link count will be used to decide how many	930	match (and isn't the current time), the link count will be used to decide
468	entries are directories (if >= 2). Otherwise, no knowledge of the number	931	how many entries are directories (if >= 2). Otherwise, no knowledge of the
469	of subdirectories will be assumed.	932	number of subdirectories will be assumed.
470		933
471	Then entries will be sorted into likely directories (everything without	934	Then entries will be sorted into likely directories a non-initial dot
472	a non-initial dot currently) and likely non-directories (everything	935	currently) and likely non-directories (see C<aio_readdirx>). Then every
473	else). Then every entry plus an appended C</.> will be C<stat>'ed,	936	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
474	likely directories first. If that succeeds, it assumes that the entry	937	in order of their inode numbers. If that succeeds, it assumes that the
475	is a directory or a symlink to directory (which will be checked	938	entry is a directory or a symlink to directory (which will be checked
476	seperately). This is often faster than stat'ing the entry itself because	939	seperately). This is often faster than stat'ing the entry itself because
477	filesystems might detect the type of the entry without reading the inode	940	filesystems might detect the type of the entry without reading the inode
478	data (e.g. ext2fs filetype feature).	941	data (e.g. ext2fs filetype feature), even on systems that cannot return
		942	the filetype information on readdir.
479		943
480	If the known number of directories (link count - 2) has been reached, the	944	If the known number of directories (link count - 2) has been reached, the
481	rest of the entries is assumed to be non-directories.	945	rest of the entries is assumed to be non-directories.
482		946
483	This only works with certainty on POSIX (= UNIX) filesystems, which	947	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
487	as those tend to return 0 or 1 as link counts, which disables the	951	as those tend to return 0 or 1 as link counts, which disables the
488	directory counting heuristic.	952	directory counting heuristic.
489		953
490	=cut	954	=cut
491		955
492	sub aio_scandir($$$) {	956	sub aio_scandir($$;$) {
493	my ($path, $maxreq, $cb) = @_;	957	my ($path, $maxreq, $cb) = @_;
494		958
495	my $pri = aioreq_pri;	959	my $pri = aioreq_pri;
496		960
497	my $grp = aio_group $cb;	961	my $grp = aio_group $cb;
…		…
505	my $now = time;	969	my $now = time;
506	my $hash1 = join ":", (stat _)[0,1,3,7,9];	970	my $hash1 = join ":", (stat _)[0,1,3,7,9];
507		971
508	# read the directory entries	972	# read the directory entries
509	aioreq_pri $pri;	973	aioreq_pri $pri;
510	add $grp aio_readdir $path, sub {	974	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
511	my $entries = shift	975	my $entries = shift
512	or return $grp->result ();	976	or return $grp->result ();
513		977
514	# stat the dir another time	978	# stat the dir another time
515	aioreq_pri $pri;	979	aioreq_pri $pri;
…		…
521	# take the slow route if anything looks fishy	985	# take the slow route if anything looks fishy
522	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	986	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
523	$ndirs = -1;	987	$ndirs = -1;
524	} else {	988	} else {
525	# if nlink == 2, we are finished	989	# if nlink == 2, we are finished
526	# on non-posix-fs's, we rely on nlink < 2	990	# for non-posix-fs's, we rely on nlink < 2
527	$ndirs = (stat _)[3] - 2	991	$ndirs = (stat _)[3] - 2
528	or return $grp->result ([], $entries);	992	or return $grp->result ([], $entries);
529	}	993	}
530		994
531	# sort into likely dirs and likely nondirs
532	# dirs == files without ".", short entries first
533	$entries = [map $_->[0],
534	sort { $b->[1] cmp $a->[1] }
535	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
536	@$entries];
537
538	my (@dirs, @nondirs);	995	my (@dirs, @nondirs);
539		996
540	my $statgrp = add $grp aio_group sub {	997	my $statgrp = add $grp aio_group sub {
541	$grp->result (\@dirs, \@nondirs);	998	$grp->result (\@dirs, \@nondirs);
542	};	999	};
543		1000
544	limit $statgrp $maxreq;	1001	limit $statgrp $maxreq;
545	feed $statgrp sub {	1002	feed $statgrp sub {
546	return unless @$entries;	1003	return unless @$entries;
547	my $entry = pop @$entries;	1004	my $entry = shift @$entries;
548		1005
549	aioreq_pri $pri;	1006	aioreq_pri $pri;
550	add $statgrp aio_stat "$path/$entry/.", sub {	1007	add $statgrp aio_stat "$path/$entry/.", sub {
551	if ($_[0] < 0) {	1008	if ($_[0] < 0) {
552	push @nondirs, $entry;	1009	push @nondirs, $entry;
…		…
573	};	1030	};
574		1031
575	$grp	1032	$grp
576	}	1033	}
577		1034
		1035	=item aio_rmtree $path, $callback->($status)
		1036
		1037	Delete a directory tree starting (and including) C<$path>, return the
		1038	status of the final C<rmdir> only. This is a composite request that
		1039	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		1040	everything else.
		1041
		1042	=cut
		1043
		1044	sub aio_rmtree;
		1045	sub aio_rmtree($;$) {
		1046	my ($path, $cb) = @_;
		1047
		1048	my $pri = aioreq_pri;
		1049	my $grp = aio_group $cb;
		1050
		1051	aioreq_pri $pri;
		1052	add $grp aio_scandir $path, 0, sub {
		1053	my ($dirs, $nondirs) = @_;
		1054
		1055	my $dirgrp = aio_group sub {
		1056	add $grp aio_rmdir $path, sub {
		1057	$grp->result ($_[0]);
		1058	};
		1059	};
		1060
		1061	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1062	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1063
		1064	add $grp $dirgrp;
		1065	};
		1066
		1067	$grp
		1068	}
		1069
		1070	=item aio_sync $callback->($status)
		1071
		1072	Asynchronously call sync and call the callback when finished.
		1073
578	=item aio_fsync $fh, $callback->($status)	1074	=item aio_fsync $fh, $callback->($status)
579		1075
580	Asynchronously call fsync on the given filehandle and call the callback	1076	Asynchronously call fsync on the given filehandle and call the callback
581	with the fsync result code.	1077	with the fsync result code.
582		1078
…		…
585	Asynchronously call fdatasync on the given filehandle and call the	1081	Asynchronously call fdatasync on the given filehandle and call the
586	callback with the fdatasync result code.	1082	callback with the fdatasync result code.
587		1083
588	If this call isn't available because your OS lacks it or it couldn't be	1084	If this call isn't available because your OS lacks it or it couldn't be
589	detected, it will be emulated by calling C<fsync> instead.	1085	detected, it will be emulated by calling C<fsync> instead.
		1086
		1087	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1088
		1089	Sync the data portion of the file specified by C<$offset> and C<$length>
		1090	to disk (but NOT the metadata), by calling the Linux-specific
		1091	sync_file_range call. If sync_file_range is not available or it returns
		1092	ENOSYS, then fdatasync or fsync is being substituted.
		1093
		1094	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1095	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1096	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1097	manpage for details.
		1098
		1099	=item aio_pathsync $path, $callback->($status)
		1100
		1101	This request tries to open, fsync and close the given path. This is a
		1102	composite request intended to sync directories after directory operations
		1103	(E.g. rename). This might not work on all operating systems or have any
		1104	specific effect, but usually it makes sure that directory changes get
		1105	written to disc. It works for anything that can be opened for read-only,
		1106	not just directories.
		1107
		1108	Future versions of this function might fall back to other methods when
		1109	C<fsync> on the directory fails (such as calling C<sync>).
		1110
		1111	Passes C<0> when everything went ok, and C<-1> on error.
		1112
		1113	=cut
		1114
		1115	sub aio_pathsync($;$) {
		1116	my ($path, $cb) = @_;
		1117
		1118	my $pri = aioreq_pri;
		1119	my $grp = aio_group $cb;
		1120
		1121	aioreq_pri $pri;
		1122	add $grp aio_open $path, O_RDONLY, 0, sub {
		1123	my ($fh) = @_;
		1124	if ($fh) {
		1125	aioreq_pri $pri;
		1126	add $grp aio_fsync $fh, sub {
		1127	$grp->result ($_[0]);
		1128
		1129	aioreq_pri $pri;
		1130	add $grp aio_close $fh;
		1131	};
		1132	} else {
		1133	$grp->result (-1);
		1134	}
		1135	};
		1136
		1137	$grp
		1138	}
		1139
		1140	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1141
		1142	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1143	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1144	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1145	scalar must only be modified in-place while an aio operation is pending on
		1146	it).
		1147
		1148	It calls the C<msync> function of your OS, if available, with the memory
		1149	area starting at C<$offset> in the string and ending C<$length> bytes
		1150	later. If C<$length> is negative, counts from the end, and if C<$length>
		1151	is C<undef>, then it goes till the end of the string. The flags can be
		1152	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1153	C<IO::AIO::MS_SYNC>.
		1154
		1155	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1156
		1157	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1158	scalars.
		1159
		1160	It touches (reads or writes) all memory pages in the specified
		1161	range inside the scalar. All caveats and parameters are the same
		1162	as for C<aio_msync>, above, except for flags, which must be either
		1163	C<0> (which reads all pages and ensures they are instantiated) or
		1164	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1165	writing an octet from it, which dirties the page).
		1166
		1167	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1168
		1169	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1170	scalars.
		1171
		1172	It reads in all the pages of the underlying storage into memory (if any)
		1173	and locks them, so they are not getting swapped/paged out or removed.
		1174
		1175	If C<$length> is undefined, then the scalar will be locked till the end.
		1176
		1177	On systems that do not implement C<mlock>, this function returns C<-1>
		1178	and sets errno to C<ENOSYS>.
		1179
		1180	Note that the corresponding C<munlock> is synchronous and is
		1181	documented under L<MISCELLANEOUS FUNCTIONS>.
		1182
		1183	Example: open a file, mmap and mlock it - both will be undone when
		1184	C<$data> gets destroyed.
		1185
		1186	open my $fh, "<", $path or die "$path: $!";
		1187	my $data;
		1188	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1189	aio_mlock $data; # mlock in background
		1190
		1191	=item aio_mlockall $flags, $callback->($status)
		1192
		1193	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1194	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1195
		1196	On systems that do not implement C<mlockall>, this function returns C<-1>
		1197	and sets errno to C<ENOSYS>.
		1198
		1199	Note that the corresponding C<munlockall> is synchronous and is
		1200	documented under L<MISCELLANEOUS FUNCTIONS>.
		1201
		1202	Example: asynchronously lock all current and future pages into memory.
		1203
		1204	aio_mlockall IO::AIO::MCL_FUTURE;
590		1205
591	=item aio_group $callback->(...)	1206	=item aio_group $callback->(...)
592		1207
593	This is a very special aio request: Instead of doing something, it is a	1208	This is a very special aio request: Instead of doing something, it is a
594	container for other aio requests, which is useful if you want to bundle	1209	container for other aio requests, which is useful if you want to bundle
…		…
644	=item cancel $req	1259	=item cancel $req
645		1260
646	Cancels the request, if possible. Has the effect of skipping execution	1261	Cancels the request, if possible. Has the effect of skipping execution
647	when entering the B<execute> state and skipping calling the callback when	1262	when entering the B<execute> state and skipping calling the callback when
648	entering the the B<result> state, but will leave the request otherwise	1263	entering the the B<result> state, but will leave the request otherwise
649	untouched. That means that requests that currently execute will not be	1264	untouched (with the exception of readdir). That means that requests that
650	stopped and resources held by the request will not be freed prematurely.	1265	currently execute will not be stopped and resources held by the request
		1266	will not be freed prematurely.
651		1267
652	=item cb $req $callback->(...)	1268	=item cb $req $callback->(...)
653		1269
654	Replace (or simply set) the callback registered to the request.	1270	Replace (or simply set) the callback registered to the request.
655		1271
…		…
706	Their lifetime, simplified, looks like this: when they are empty, they	1322	Their lifetime, simplified, looks like this: when they are empty, they
707	will finish very quickly. If they contain only requests that are in the	1323	will finish very quickly. If they contain only requests that are in the
708	C<done> state, they will also finish. Otherwise they will continue to	1324	C<done> state, they will also finish. Otherwise they will continue to
709	exist.	1325	exist.
710		1326
711	That means after creating a group you have some time to add requests. And	1327	That means after creating a group you have some time to add requests
712	in the callbacks of those requests, you can add further requests to the	1328	(precisely before the callback has been invoked, which is only done within
713	group. And only when all those requests have finished will the the group	1329	the C<poll_cb>). And in the callbacks of those requests, you can add
714	itself finish.	1330	further requests to the group. And only when all those requests have
		1331	finished will the the group itself finish.
715		1332
716	=over 4	1333	=over 4
717		1334
718	=item add $grp ...	1335	=item add $grp ...
719		1336
…		…
728	=item $grp->cancel_subs	1345	=item $grp->cancel_subs
729		1346
730	Cancel all subrequests and clears any feeder, but not the group request	1347	Cancel all subrequests and clears any feeder, but not the group request
731	itself. Useful when you queued a lot of events but got a result early.	1348	itself. Useful when you queued a lot of events but got a result early.
732		1349
		1350	The group request will finish normally (you cannot add requests to the
		1351	group).
		1352
733	=item $grp->result (...)	1353	=item $grp->result (...)
734		1354
735	Set the result value(s) that will be passed to the group callback when all	1355	Set the result value(s) that will be passed to the group callback when all
736	subrequests have finished and set thre groups errno to the current value	1356	subrequests have finished and set the groups errno to the current value
737	of errno (just like calling C<errno> without an error number). By default,	1357	of errno (just like calling C<errno> without an error number). By default,
738	no argument will be passed and errno is zero.	1358	no argument will be passed and errno is zero.
739		1359
740	=item $grp->errno ([$errno])	1360	=item $grp->errno ([$errno])
741		1361
…		…
752	=item feed $grp $callback->($grp)	1372	=item feed $grp $callback->($grp)
753		1373
754	Sets a feeder/generator on this group: every group can have an attached	1374	Sets a feeder/generator on this group: every group can have an attached
755	generator that generates requests if idle. The idea behind this is that,	1375	generator that generates requests if idle. The idea behind this is that,
756	although you could just queue as many requests as you want in a group,	1376	although you could just queue as many requests as you want in a group,
757	this might starve other requests for a potentially long time. For	1377	this might starve other requests for a potentially long time. For example,
758	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1378	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
759	requests, delaying any later requests for a long time.	1379	delaying any later requests for a long time.
760		1380
761	To avoid this, and allow incremental generation of requests, you can	1381	To avoid this, and allow incremental generation of requests, you can
762	instead a group and set a feeder on it that generates those requests. The	1382	instead a group and set a feeder on it that generates those requests. The
763	feed callback will be called whenever there are few enough (see C<limit>,	1383	feed callback will be called whenever there are few enough (see C<limit>,
764	below) requests active in the group itself and is expected to queue more	1384	below) requests active in the group itself and is expected to queue more
…		…
768	not impose any limits).	1388	not impose any limits).
769		1389
770	If the feed does not queue more requests when called, it will be	1390	If the feed does not queue more requests when called, it will be
771	automatically removed from the group.	1391	automatically removed from the group.
772		1392
773	If the feed limit is C<0>, it will be set to C<2> automatically.	1393	If the feed limit is C<0> when this method is called, it will be set to
		1394	C<2> automatically.
774		1395
775	Example:	1396	Example:
776		1397
777	# stat all files in @files, but only ever use four aio requests concurrently:	1398	# stat all files in @files, but only ever use four aio requests concurrently:
778		1399
…		…
790	Sets the feeder limit for the group: The feeder will be called whenever	1411	Sets the feeder limit for the group: The feeder will be called whenever
791	the group contains less than this many requests.	1412	the group contains less than this many requests.
792		1413
793	Setting the limit to C<0> will pause the feeding process.	1414	Setting the limit to C<0> will pause the feeding process.
794		1415
		1416	The default value for the limit is C<0>, but note that setting a feeder
		1417	automatically bumps it up to C<2>.
		1418
795	=back	1419	=back
796		1420
797	=head2 SUPPORT FUNCTIONS	1421	=head2 SUPPORT FUNCTIONS
798		1422
		1423	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1424
799	=over 4	1425	=over 4
800		1426
801	=item $fileno = IO::AIO::poll_fileno	1427	=item $fileno = IO::AIO::poll_fileno
802		1428
803	Return the I<request result pipe file descriptor>. This filehandle must be	1429	Return the I<request result pipe file descriptor>. This filehandle must be
804	polled for reading by some mechanism outside this module (e.g. Event or	1430	polled for reading by some mechanism outside this module (e.g. EV, Glib,
805	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1431	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
806	to call C<poll_cb> to check the results.	1432	you have to call C<poll_cb> to check the results.
807		1433
808	See C<poll_cb> for an example.	1434	See C<poll_cb> for an example.
809		1435
810	=item IO::AIO::poll_cb	1436	=item IO::AIO::poll_cb
811		1437
812	Process all outstanding events on the result pipe. You have to call this	1438	Process some outstanding events on the result pipe. You have to call
813	regularly. Returns the number of events processed. Returns immediately	1439	this regularly. Returns C<0> if all events could be processed (or there
814	when no events are outstanding.	1440	were no events to process), or C<-1> if it returned earlier for whatever
		1441	reason. Returns immediately when no events are outstanding. The amount of
		1442	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1443	C<IO::AIO::max_poll_time>.
815		1444
816	If not all requests were processed for whatever reason, the filehandle	1445	If not all requests were processed for whatever reason, the filehandle
817	will still be ready when C<poll_cb> returns.	1446	will still be ready when C<poll_cb> returns, so normally you don't have to
		1447	do anything special to have it called later.
		1448
		1449	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1450	ready, it can be beneficial to call this function from loops which submit
		1451	a lot of requests, to make sure the results get processed when they become
		1452	available and not just when the loop is finished and the event loop takes
		1453	over again. This function returns very fast when there are no outstanding
		1454	requests.
818		1455
819	Example: Install an Event watcher that automatically calls	1456	Example: Install an Event watcher that automatically calls
820	IO::AIO::poll_cb with high priority:	1457	IO::AIO::poll_cb with high priority (more examples can be found in the
		1458	SYNOPSIS section, at the top of this document):
821		1459
822	Event->io (fd => IO::AIO::poll_fileno,	1460	Event->io (fd => IO::AIO::poll_fileno,
823	poll => 'r', async => 1,	1461	poll => 'r', async => 1,
824	cb => \&IO::AIO::poll_cb);	1462	cb => \&IO::AIO::poll_cb);
825		1463
826	=item IO::AIO::poll_some $max_requests	1464	=item IO::AIO::poll_wait
827		1465
828	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests	1466	If there are any outstanding requests and none of them in the result
829	at a time.	1467	phase, wait till the result filehandle becomes ready for reading (simply
		1468	does a C<select> on the filehandle. This is useful if you want to
		1469	synchronously wait for some requests to finish).
830		1470
831	Useful if you want to ensure some level of interactiveness when perl is	1471	See C<nreqs> for an example.
832	not fast enough to process all requests in time.	1472
		1473	=item IO::AIO::poll
		1474
		1475	Waits until some requests have been handled.
		1476
		1477	Returns the number of requests processed, but is otherwise strictly
		1478	equivalent to:
		1479
		1480	IO::AIO::poll_wait, IO::AIO::poll_cb
		1481
		1482	=item IO::AIO::flush
		1483
		1484	Wait till all outstanding AIO requests have been handled.
		1485
		1486	Strictly equivalent to:
		1487
		1488	IO::AIO::poll_wait, IO::AIO::poll_cb
		1489	while IO::AIO::nreqs;
		1490
		1491	=item IO::AIO::max_poll_reqs $nreqs
		1492
		1493	=item IO::AIO::max_poll_time $seconds
		1494
		1495	These set the maximum number of requests (default C<0>, meaning infinity)
		1496	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1497	the maximum amount of time (default C<0>, meaning infinity) spent in
		1498	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1499	of time C<poll_cb> is allowed to use).
		1500
		1501	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1502	syscall per request processed, which is not normally a problem unless your
		1503	callbacks are really really fast or your OS is really really slow (I am
		1504	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1505
		1506	Setting these is useful if you want to ensure some level of
		1507	interactiveness when perl is not fast enough to process all requests in
		1508	time.
		1509
		1510	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
833		1511
834	Example: Install an Event watcher that automatically calls	1512	Example: Install an Event watcher that automatically calls
835	IO::AIO::poll_some with low priority, to ensure that other parts of the	1513	IO::AIO::poll_cb with low priority, to ensure that other parts of the
836	program get the CPU sometimes even under high AIO load.	1514	program get the CPU sometimes even under high AIO load.
837		1515
		1516	# try not to spend much more than 0.1s in poll_cb
		1517	IO::AIO::max_poll_time 0.1;
		1518
		1519	# use a low priority so other tasks have priority
838	Event->io (fd => IO::AIO::poll_fileno,	1520	Event->io (fd => IO::AIO::poll_fileno,
839	poll => 'r', nice => 1,	1521	poll => 'r', nice => 1,
840	cb => sub { IO::AIO::poll_some 256 });	1522	cb => &IO::AIO::poll_cb);
841		1523
842	=item IO::AIO::poll_wait	1524	=back
843		1525
844	Wait till the result filehandle becomes ready for reading (simply does a	1526	=head3 CONTROLLING THE NUMBER OF THREADS
845	C<select> on the filehandle. This is useful if you want to synchronously wait
846	for some requests to finish).
847		1527
848	See C<nreqs> for an example.	1528	=over
849
850	=item IO::AIO::nreqs
851
852	Returns the number of requests currently in the ready, execute or pending
853	states (i.e. for which their callback has not been invoked yet).
854
855	Example: wait till there are no outstanding requests anymore:
856
857	IO::AIO::poll_wait, IO::AIO::poll_cb
858	while IO::AIO::nreqs;
859
860	=item IO::AIO::nready
861
862	Returns the number of requests currently in the ready state (not yet
863	executed).
864
865	=item IO::AIO::npending
866
867	Returns the number of requests currently in the pending state (executed,
868	but not yet processed by poll_cb).
869
870	=item IO::AIO::flush
871
872	Wait till all outstanding AIO requests have been handled.
873
874	Strictly equivalent to:
875
876	IO::AIO::poll_wait, IO::AIO::poll_cb
877	while IO::AIO::nreqs;
878
879	=item IO::AIO::poll
880
881	Waits until some requests have been handled.
882
883	Strictly equivalent to:
884
885	IO::AIO::poll_wait, IO::AIO::poll_cb
886	if IO::AIO::nreqs;
887		1529
888	=item IO::AIO::min_parallel $nthreads	1530	=item IO::AIO::min_parallel $nthreads
889		1531
890	Set the minimum number of AIO threads to C<$nthreads>. The current	1532	Set the minimum number of AIO threads to C<$nthreads>. The current
891	default is C<8>, which means eight asynchronous operations can execute	1533	default is C<8>, which means eight asynchronous operations can execute
892	concurrently at any one time (the number of outstanding requests,	1534	concurrently at any one time (the number of outstanding requests,
893	however, is unlimited).	1535	however, is unlimited).
894		1536
895	IO::AIO starts threads only on demand, when an AIO request is queued and	1537	IO::AIO starts threads only on demand, when an AIO request is queued and
896	no free thread exists.	1538	no free thread exists. Please note that queueing up a hundred requests can
		1539	create demand for a hundred threads, even if it turns out that everything
		1540	is in the cache and could have been processed faster by a single thread.
897		1541
898	It is recommended to keep the number of threads relatively low, as some	1542	It is recommended to keep the number of threads relatively low, as some
899	Linux kernel versions will scale negatively with the number of threads	1543	Linux kernel versions will scale negatively with the number of threads
900	(higher parallelity => MUCH higher latency). With current Linux 2.6	1544	(higher parallelity => MUCH higher latency). With current Linux 2.6
901	versions, 4-32 threads should be fine.	1545	versions, 4-32 threads should be fine.
…		…
915	This module automatically runs C<max_parallel 0> at program end, to ensure	1559	This module automatically runs C<max_parallel 0> at program end, to ensure
916	that all threads are killed and that there are no outstanding requests.	1560	that all threads are killed and that there are no outstanding requests.
917		1561
918	Under normal circumstances you don't need to call this function.	1562	Under normal circumstances you don't need to call this function.
919		1563
		1564	=item IO::AIO::max_idle $nthreads
		1565
		1566	Limit the number of threads (default: 4) that are allowed to idle
		1567	(i.e., threads that did not get a request to process within the idle
		1568	timeout (default: 10 seconds). That means if a thread becomes idle while
		1569	C<$nthreads> other threads are also idle, it will free its resources and
		1570	exit.
		1571
		1572	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1573	to allow for extremely high load situations, but want to free resources
		1574	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1575
		1576	The default is probably ok in most situations, especially if thread
		1577	creation is fast. If thread creation is very slow on your system you might
		1578	want to use larger values.
		1579
		1580	=item IO::AIO::idle_timeout $seconds
		1581
		1582	Sets the minimum idle timeout (default 10) after which worker threads are
		1583	allowed to exit. SEe C<IO::AIO::max_idle>.
		1584
920	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1585	=item IO::AIO::max_outstanding $maxreqs
		1586
		1587	Sets the maximum number of outstanding requests to C<$nreqs>. If
		1588	you do queue up more than this number of requests, the next call to
		1589	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1590	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1591	longer exceeded.
		1592
		1593	In other words, this setting does not enforce a queue limit, but can be
		1594	used to make poll functions block if the limit is exceeded.
921		1595
922	This is a very bad function to use in interactive programs because it	1596	This is a very bad function to use in interactive programs because it
923	blocks, and a bad way to reduce concurrency because it is inexact: Better	1597	blocks, and a bad way to reduce concurrency because it is inexact: Better
924	use an C<aio_group> together with a feed callback.	1598	use an C<aio_group> together with a feed callback.
925		1599
926	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1600	It's main use is in scripts without an event loop - when you want to stat
927	to queue up more than this number of requests, the next call to the	1601	a lot of files, you can write somehting like this:
928	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
929	function will block until the limit is no longer exceeded.
930		1602
931	The default value is very large, so there is no practical limit on the	1603	IO::AIO::max_outstanding 32;
932	number of outstanding requests.
933		1604
934	You can still queue as many requests as you want. Therefore,	1605	for my $path (...) {
935	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1606	aio_stat $path , ...;
936	as a stop gap to shield against fatal memory overflow (with large values).	1607	IO::AIO::poll_cb;
		1608	}
		1609
		1610	IO::AIO::flush;
		1611
		1612	The call to C<poll_cb> inside the loop will normally return instantly, but
		1613	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1614	some requests have been handled. This keeps the loop from pushing a large
		1615	number of C<aio_stat> requests onto the queue.
		1616
		1617	The default value for C<max_outstanding> is very large, so there is no
		1618	practical limit on the number of outstanding requests.
937		1619
938	=back	1620	=back
939		1621
		1622	=head3 STATISTICAL INFORMATION
		1623
		1624	=over
		1625
		1626	=item IO::AIO::nreqs
		1627
		1628	Returns the number of requests currently in the ready, execute or pending
		1629	states (i.e. for which their callback has not been invoked yet).
		1630
		1631	Example: wait till there are no outstanding requests anymore:
		1632
		1633	IO::AIO::poll_wait, IO::AIO::poll_cb
		1634	while IO::AIO::nreqs;
		1635
		1636	=item IO::AIO::nready
		1637
		1638	Returns the number of requests currently in the ready state (not yet
		1639	executed).
		1640
		1641	=item IO::AIO::npending
		1642
		1643	Returns the number of requests currently in the pending state (executed,
		1644	but not yet processed by poll_cb).
		1645
		1646	=back
		1647
		1648	=head3 MISCELLANEOUS FUNCTIONS
		1649
		1650	IO::AIO implements some functions that might be useful, but are not
		1651	asynchronous.
		1652
		1653	=over 4
		1654
		1655	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1656
		1657	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1658	but is blocking (this makes most sense if you know the input data is
		1659	likely cached already and the output filehandle is set to non-blocking
		1660	operations).
		1661
		1662	Returns the number of bytes copied, or C<-1> on error.
		1663
		1664	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1665
		1666	Simply calls the C<posix_fadvise> function (see its
		1667	manpage for details). The following advice constants are
		1668	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1669	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1670	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1671
		1672	On systems that do not implement C<posix_fadvise>, this function returns
		1673	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1674
		1675	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1676
		1677	Simply calls the C<posix_madvise> function (see its
		1678	manpage for details). The following advice constants are
		1679	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1680	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1681
		1682	On systems that do not implement C<posix_madvise>, this function returns
		1683	ENOSYS, otherwise the return value of C<posix_madvise>.
		1684
		1685	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1686
		1687	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1688	$scalar (see its manpage for details). The following protect
		1689	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1690	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1691
		1692	On systems that do not implement C<mprotect>, this function returns
		1693	ENOSYS, otherwise the return value of C<mprotect>.
		1694
		1695	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1696
		1697	Memory-maps a file (or anonymous memory range) and attaches it to the
		1698	given C<$scalar>, which will act like a string scalar.
		1699
		1700	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1701	change the string length, and most read-only operations such as copying it
		1702	or searching it with regexes and so on.
		1703
		1704	Anything else is unsafe and will, at best, result in memory leaks.
		1705
		1706	The memory map associated with the C<$scalar> is automatically removed
		1707	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1708	C<IO::AIO::munmap> functions are called.
		1709
		1710	This calls the C<mmap>(2) function internally. See your system's manual
		1711	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1712
		1713	The C<$length> must be larger than zero and smaller than the actual
		1714	filesize.
		1715
		1716	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1717	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1718
		1719	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1720	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1721	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1722	(which is set to C<MAP_ANON> if your system only provides this
		1723	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1724	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1725	C<IO::AIO::MAP_NONBLOCK>
		1726
		1727	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1728
		1729	C<$offset> is the offset from the start of the file - it generally must be
		1730	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1731
		1732	Example:
		1733
		1734	use Digest::MD5;
		1735	use IO::AIO;
		1736
		1737	open my $fh, "<verybigfile"
		1738	or die "$!";
		1739
		1740	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1741	or die "verybigfile: $!";
		1742
		1743	my $fast_md5 = md5 $data;
		1744
		1745	=item IO::AIO::munmap $scalar
		1746
		1747	Removes a previous mmap and undefines the C<$scalar>.
		1748
		1749	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1750
		1751	Calls the C<munlock> function, undoing the effects of a previous
		1752	C<aio_mlock> call (see its description for details).
		1753
		1754	=item IO::AIO::munlockall
		1755
		1756	Calls the C<munlockall> function.
		1757
		1758	On systems that do not implement C<munlockall>, this function returns
		1759	ENOSYS, otherwise the return value of C<munlockall>.
		1760
		1761	=back
		1762
940	=cut	1763	=cut
941		1764
942	# support function to convert a fd into a perl filehandle
943	sub _fd2fh {
944	return undef if $_[0] < 0;
945
946	# try to generate nice filehandles
947	my $sym = "IO::AIO::fd#$_[0]";
948	local *$sym;
949
950	open *$sym, "+<&=$_[0]" # usually works under any unix
951	or open *$sym, "<&=$_[0]" # cygwin needs this
952	or open *$sym, ">&=$_[0]" # or this
953	or return undef;
954
955	*$sym
956	}
957
958	min_parallel 8;	1765	min_parallel 8;
959		1766
		1767	END { flush }
		1768
960	1;	1769	1;
961		1770
		1771	=head1 EVENT LOOP INTEGRATION
		1772
		1773	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1774	automatically into many event loops:
		1775
		1776	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1777	use AnyEvent::AIO;
		1778
		1779	You can also integrate IO::AIO manually into many event loops, here are
		1780	some examples of how to do this:
		1781
		1782	# EV integration
		1783	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1784
		1785	# Event integration
		1786	Event->io (fd => IO::AIO::poll_fileno,
		1787	poll => 'r',
		1788	cb => \&IO::AIO::poll_cb);
		1789
		1790	# Glib/Gtk2 integration
		1791	add_watch Glib::IO IO::AIO::poll_fileno,
		1792	in => sub { IO::AIO::poll_cb; 1 };
		1793
		1794	# Tk integration
		1795	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1796	readable => \&IO::AIO::poll_cb);
		1797
		1798	# Danga::Socket integration
		1799	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1800	\&IO::AIO::poll_cb);
		1801
962	=head2 FORK BEHAVIOUR	1802	=head2 FORK BEHAVIOUR
963		1803
964	This module should do "the right thing" when the process using it forks:	1804	Usage of pthreads in a program changes the semantics of fork
		1805	considerably. Specifically, only async-safe functions can be called after
		1806	fork. Perl doesn't know about this, so in general, you cannot call fork
		1807	with defined behaviour in perl. IO::AIO uses pthreads, so this applies,
		1808	but many other extensions and (for inexplicable reasons) perl itself often
		1809	is linked against pthreads, so this limitation applies.
965		1810
966	Before the fork, IO::AIO enters a quiescent state where no requests	1811	Some operating systems have extensions that allow safe use of fork, and
967	can be added in other threads and no results will be processed. After	1812	this module should do "the right thing" on those, and tries on others. At
968	the fork the parent simply leaves the quiescent state and continues	1813	the time of this writing (2011) only GNU/Linux supports these extensions
969	request/result processing, while the child frees the request/result queue	1814	to POSIX.
970	(so that the requests started before the fork will only be handled in the
971	parent). Threads will be started on demand until the limit set in the
972	parent process has been reached again.
973
974	In short: the parent will, after a short pause, continue as if fork had
975	not been called, while the child will act as if IO::AIO has not been used
976	yet.
977		1815
978	=head2 MEMORY USAGE	1816	=head2 MEMORY USAGE
979		1817
980	Per-request usage:	1818	Per-request usage:
981		1819
…		…
983	bytes of memory. In addition, stat requests need a stat buffer (possibly	1821	bytes of memory. In addition, stat requests need a stat buffer (possibly
984	a few hundred bytes), readdir requires a result buffer and so on. Perl	1822	a few hundred bytes), readdir requires a result buffer and so on. Perl
985	scalars and other data passed into aio requests will also be locked and	1823	scalars and other data passed into aio requests will also be locked and
986	will consume memory till the request has entered the done state.	1824	will consume memory till the request has entered the done state.
987		1825
988	This is now awfully much, so queuing lots of requests is not usually a	1826	This is not awfully much, so queuing lots of requests is not usually a
989	problem.	1827	problem.
990		1828
991	Per-thread usage:	1829	Per-thread usage:
992		1830
993	In the execution phase, some aio requests require more memory for	1831	In the execution phase, some aio requests require more memory for
…		…
998		1836
999	Known bugs will be fixed in the next release.	1837	Known bugs will be fixed in the next release.
1000		1838
1001	=head1 SEE ALSO	1839	=head1 SEE ALSO
1002		1840
1003	L<Coro::AIO>.	1841	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1842	more natural syntax.
1004		1843
1005	=head1 AUTHOR	1844	=head1 AUTHOR
1006		1845
1007	Marc Lehmann <schmorp@schmorp.de>	1846	Marc Lehmann <schmorp@schmorp.de>
1008	http://home.schmorp.de/	1847	http://home.schmorp.de/

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