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Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC vs.
Revision 1.182 by root, Sun Sep 12 03:36:27 2010 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 = '3.65';
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_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
		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_rename $srcpath, $dstpath, $callback->($status)
		228	aio_mkdir $pathname, $mode, $callback->($status)
		229	aio_rmdir $pathname, $callback->($status)
		230	aio_readdir $pathname, $callback->($entries)
		231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		233	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		234	aio_load $path, $data, $callback->($status)
		235	aio_copy $srcpath, $dstpath, $callback->($status)
		236	aio_move $srcpath, $dstpath, $callback->($status)
		237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		238	aio_rmtree $path, $callback->($status)
		239	aio_sync $callback->($status)
		240	aio_fsync $fh, $callback->($status)
		241	aio_fdatasync $fh, $callback->($status)
		242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		243	aio_pathsync $path, $callback->($status)
		244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		247	aio_mlockall $flags, $callback->($status)
		248	aio_group $callback->(...)
		249	aio_nop $callback->()
		250
		251	$prev_pri = aioreq_pri [$pri]
		252	aioreq_nice $pri_adjust
		253
		254	IO::AIO::poll_wait
		255	IO::AIO::poll_cb
		256	IO::AIO::poll
		257	IO::AIO::flush
		258	IO::AIO::max_poll_reqs $nreqs
		259	IO::AIO::max_poll_time $seconds
		260	IO::AIO::min_parallel $nthreads
		261	IO::AIO::max_parallel $nthreads
		262	IO::AIO::max_idle $nthreads
		263	IO::AIO::max_outstanding $maxreqs
		264	IO::AIO::nreqs
		265	IO::AIO::nready
		266	IO::AIO::npending
		267
		268	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		269	IO::AIO::fadvise $fh, $offset, $len, $advice
		270	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		271	IO::AIO::munlockall
		272
149	=head2 AIO FUNCTIONS	273	=head2 AIO REQUEST FUNCTIONS
150		274
151	All the C<aio_*> calls are more or less thin wrappers around the syscall	275	All the C<aio_*> calls are more or less thin wrappers around the syscall
152	with the same name (sans C<aio_>). The arguments are similar or identical,	276	with the same name (sans C<aio_>). The arguments are similar or identical,
153	and they all accept an additional (and optional) C<$callback> argument	277	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	278	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	279	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	280	perl, which usually delivers "false") as its sole argument after the given
157	syscall has been executed asynchronously.	281	syscall has been executed asynchronously.
158		282
159	All functions expecting a filehandle keep a copy of the filehandle	283	All functions expecting a filehandle keep a copy of the filehandle
160	internally until the request has finished.	284	internally until the request has finished.
161		285
162	All requests return objects of type L<IO::AIO::REQ> that allow further	286	All functions return request objects of type L<IO::AIO::REQ> that allow
163	manipulation of those requests while they are in-flight.	287	further manipulation of those requests while they are in-flight.
164		288
165	The pathnames you pass to these routines I<must> be absolute and	289	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	290	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	291	request is being executed, the current working directory could have
168	changed. Alternatively, you can make sure that you never change the	292	changed. Alternatively, you can make sure that you never change the
169	current working directory.	293	current working directory anywhere in the program and then use relative
		294	paths.
170		295
171	To encode pathnames to byte form, either make sure you either: a)	296	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	297	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	298	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	299	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)	300	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176	use something else.	301	use something else to ensure your scalar has the correct contents.
		302
		303	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		304	handles correctly whether it is set or not.
177		305
178	=over 4	306	=over 4
179		307
180	=item $prev_pri = aioreq_pri [$pri]	308	=item $prev_pri = aioreq_pri [$pri]
181		309
…		…
201	aio_read $_[0], ..., sub {	329	aio_read $_[0], ..., sub {
202	...	330	...
203	};	331	};
204	};	332	};
205		333
		334
206	=item aioreq_nice $pri_adjust	335	=item aioreq_nice $pri_adjust
207		336
208	Similar to C<aioreq_pri>, but subtracts the given value from the current	337	Similar to C<aioreq_pri>, but subtracts the given value from the current
209	priority, so effects are cumulative.	338	priority, so the effect is cumulative.
		339
210		340
211	=item aio_open $pathname, $flags, $mode, $callback->($fh)	341	=item aio_open $pathname, $flags, $mode, $callback->($fh)
212		342
213	Asynchronously open or create a file and call the callback with a newly	343	Asynchronously open or create a file and call the callback with a newly
214	created filehandle for the file.	344	created filehandle for the file.
…		…
220	list. They are the same as used by C<sysopen>.	350	list. They are the same as used by C<sysopen>.
221		351
222	Likewise, C<$mode> specifies the mode of the newly created file, if it	352	Likewise, C<$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>,	353	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,	354	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).	355	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		356	by the umask in effect then the request is being executed, so better never
		357	change the umask.
226		358
227	Example:	359	Example:
228		360
229	aio_open "/etc/passwd", O_RDONLY, 0, sub {	361	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
230	if ($_[0]) {	362	if ($_[0]) {
231	print "open successful, fh is $_[0]\n";	363	print "open successful, fh is $_[0]\n";
232	...	364	...
233	} else {	365	} else {
234	die "open failed: $!\n";	366	die "open failed: $!\n";
235	}	367	}
236	};	368	};
237		369
		370
238	=item aio_close $fh, $callback->($status)	371	=item aio_close $fh, $callback->($status)
239		372
240	Asynchronously close a file and call the callback with the result	373	Asynchronously close a file and call the callback with the result
241	code. I<WARNING:> although accepted, you should not pass in a perl	374	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		375
246	This is supposed to be a bug in the API, so that might change. It's	376	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
247	therefore best to avoid this function.	377	closing the file descriptor associated with the filehandle itself.
		378
		379	Therefore, C<aio_close> will not close the filehandle - instead it will
		380	use dup2 to overwrite the file descriptor with the write-end of a pipe
		381	(the pipe fd will be created on demand and will be cached).
		382
		383	Or in other words: the file descriptor will be closed, but it will not be
		384	free for reuse until the perl filehandle is closed.
		385
		386	=cut
248		387
249	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	388	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250		389
251	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	390	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252		391
253	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	392	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	393	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
255	callback without the actual number of bytes read (or -1 on error, just	394	and calls the callback without the actual number of bytes read (or -1 on
256	like the syscall).	395	error, just like the syscall).
		396
		397	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		398	offset plus the actual number of bytes read.
		399
		400	If C<$offset> is undefined, then the current file descriptor offset will
		401	be used (and updated), otherwise the file descriptor offset will not be
		402	changed by these calls.
		403
		404	If C<$length> is undefined in C<aio_write>, use the remaining length of
		405	C<$data>.
		406
		407	If C<$dataoffset> is less than zero, it will be counted from the end of
		408	C<$data>.
257		409
258	The C<$data> scalar I<MUST NOT> be modified in any way while the request	410	The C<$data> scalar I<MUST NOT> be modified in any way while the request
259	is outstanding. Modifying it can result in segfaults or WW3 (if the	411	is outstanding. Modifying it can result in segfaults or World War III (if
260	necessary/optional hardware is installed).	412	the necessary/optional hardware is installed).
261		413
262	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	414	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263	offset C<0> within the scalar:	415	offset C<0> within the scalar:
264		416
265	aio_read $fh, 7, 15, $buffer, 0, sub {	417	aio_read $fh, 7, 15, $buffer, 0, sub {
266	$_[0] > 0 or die "read error: $!";	418	$_[0] > 0 or die "read error: $!";
267	print "read $_[0] bytes: <$buffer>\n";	419	print "read $_[0] bytes: <$buffer>\n";
268	};	420	};
269		421
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		422
345	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	423	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
346		424
347	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	425	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	426	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
350	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	428	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
351	other.	429	other.
352		430
353	This call tries to make use of a native C<sendfile> syscall to provide	431	This call tries to make use of a native C<sendfile> syscall to provide
354	zero-copy operation. For this to work, C<$out_fh> should refer to a	432	zero-copy operation. For this to work, C<$out_fh> should refer to a
355	socket, and C<$in_fh> should refer to mmap'able file.	433	socket, and C<$in_fh> should refer to an mmap'able file.
356		434
357	If the native sendfile call fails or is not implemented, it will be	435	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		436	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
358	emulated, so you can call C<aio_sendfile> on any type of filehandle	437	it will be emulated, so you can call C<aio_sendfile> on any type of
359	regardless of the limitations of the operating system.	438	filehandle regardless of the limitations of the operating system.
360		439
361	Please note, however, that C<aio_sendfile> can read more bytes from	440	Please note, however, that C<aio_sendfile> can read more bytes from
362	C<$in_fh> than are written, and there is no way to find out how many	441	C<$in_fh> than are written, and there is no way to find out how many
363	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	442	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
364	provides the number of bytes written to C<$out_fh>. Only if the result	443	provides the number of bytes written to C<$out_fh>. Only if the result
365	value equals C<$length> one can assume that C<$length> bytes have been	444	value equals C<$length> one can assume that C<$length> bytes have been
366	read.	445	read.
		446
367		447
368	=item aio_readahead $fh,$offset,$length, $callback->($retval)	448	=item aio_readahead $fh,$offset,$length, $callback->($retval)
369		449
370	C<aio_readahead> populates the page cache with data from a file so that	450	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>	451	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.	457	file. The current file offset of the file is left unchanged.
378		458
379	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	459	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.	460	emulated by simply reading the data, which would have a similar effect.
381		461
		462
382	=item aio_stat $fh_or_path, $callback->($status)	463	=item aio_stat $fh_or_path, $callback->($status)
383		464
384	=item aio_lstat $fh, $callback->($status)	465	=item aio_lstat $fh, $callback->($status)
385		466
386	Works like perl's C<stat> or C<lstat> in void context. The callback will	467	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
399	aio_stat "/etc/passwd", sub {	480	aio_stat "/etc/passwd", sub {
400	$_[0] and die "stat failed: $!";	481	$_[0] and die "stat failed: $!";
401	print "size is ", -s _, "\n";	482	print "size is ", -s _, "\n";
402	};	483	};
403		484
		485
		486	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		487
		488	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		489	whether a file handle or path was passed.
		490
		491	On success, the callback is passed a hash reference with the following
		492	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		493	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		494	is passed.
		495
		496	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		497	C<ST_NOSUID>.
		498
		499	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		500	their correct value when available, or to C<0> on systems that do
		501	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		502	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		503	C<ST_NODIRATIME> and C<ST_RELATIME>.
		504
		505	Example: stat C</wd> and dump out the data if successful.
		506
		507	aio_statvfs "/wd", sub {
		508	my $f = $_[0]
		509	or die "statvfs: $!";
		510
		511	use Data::Dumper;
		512	say Dumper $f;
		513	};
		514
		515	# result:
		516	{
		517	bsize => 1024,
		518	bfree => 4333064312,
		519	blocks => 10253828096,
		520	files => 2050765568,
		521	flag => 4096,
		522	favail => 2042092649,
		523	bavail => 4333064312,
		524	ffree => 2042092649,
		525	namemax => 255,
		526	frsize => 1024,
		527	fsid => 1810
		528	}
		529
		530
		531	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		532
		533	Works like perl's C<utime> function (including the special case of $atime
		534	and $mtime being undef). Fractional times are supported if the underlying
		535	syscalls support them.
		536
		537	When called with a pathname, uses utimes(2) if available, otherwise
		538	utime(2). If called on a file descriptor, uses futimes(2) if available,
		539	otherwise returns ENOSYS, so this is not portable.
		540
		541	Examples:
		542
		543	# set atime and mtime to current time (basically touch(1)):
		544	aio_utime "path", undef, undef;
		545	# set atime to current time and mtime to beginning of the epoch:
		546	aio_utime "path", time, undef; # undef==0
		547
		548
		549	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		550
		551	Works like perl's C<chown> function, except that C<undef> for either $uid
		552	or $gid is being interpreted as "do not change" (but -1 can also be used).
		553
		554	Examples:
		555
		556	# same as "chown root path" in the shell:
		557	aio_chown "path", 0, -1;
		558	# same as above:
		559	aio_chown "path", 0, undef;
		560
		561
		562	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		563
		564	Works like truncate(2) or ftruncate(2).
		565
		566
		567	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		568
		569	Works like perl's C<chmod> function.
		570
		571
404	=item aio_unlink $pathname, $callback->($status)	572	=item aio_unlink $pathname, $callback->($status)
405		573
406	Asynchronously unlink (delete) a file and call the callback with the	574	Asynchronously unlink (delete) a file and call the callback with the
407	result code.	575	result code.
408		576
		577
		578	=item aio_mknod $path, $mode, $dev, $callback->($status)
		579
		580	[EXPERIMENTAL]
		581
		582	Asynchronously create a device node (or fifo). See mknod(2).
		583
		584	The only (POSIX-) portable way of calling this function is:
		585
		586	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		587
		588
409	=item aio_link $srcpath, $dstpath, $callback->($status)	589	=item aio_link $srcpath, $dstpath, $callback->($status)
410		590
411	Asynchronously create a new link to the existing object at C<$srcpath> at	591	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.	592	the path C<$dstpath> and call the callback with the result code.
413		593
		594
414	=item aio_symlink $srcpath, $dstpath, $callback->($status)	595	=item aio_symlink $srcpath, $dstpath, $callback->($status)
415		596
416	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	597	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.	598	the path C<$dstpath> and call the callback with the result code.
418		599
		600
		601	=item aio_readlink $path, $callback->($link)
		602
		603	Asynchronously read the symlink specified by C<$path> and pass it to
		604	the callback. If an error occurs, nothing or undef gets passed to the
		605	callback.
		606
		607
419	=item aio_rename $srcpath, $dstpath, $callback->($status)	608	=item aio_rename $srcpath, $dstpath, $callback->($status)
420		609
421	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	610	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
422	rename(2) and call the callback with the result code.	611	rename(2) and call the callback with the result code.
423		612
		613
		614	=item aio_mkdir $pathname, $mode, $callback->($status)
		615
		616	Asynchronously mkdir (create) a directory and call the callback with
		617	the result code. C<$mode> will be modified by the umask at the time the
		618	request is executed, so do not change your umask.
		619
		620
424	=item aio_rmdir $pathname, $callback->($status)	621	=item aio_rmdir $pathname, $callback->($status)
425		622
426	Asynchronously rmdir (delete) a directory and call the callback with the	623	Asynchronously rmdir (delete) a directory and call the callback with the
427	result code.	624	result code.
		625
428		626
429	=item aio_readdir $pathname, $callback->($entries)	627	=item aio_readdir $pathname, $callback->($entries)
430		628
431	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	629	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	630	directory (i.e. opendir + readdir + closedir). The entries will not be
433	sorted, and will B<NOT> include the C<.> and C<..> entries.	631	sorted, and will B<NOT> include the C<.> and C<..> entries.
434		632
435	The callback a single argument which is either C<undef> or an array-ref	633	The callback is passed a single argument which is either C<undef> or an
436	with the filenames.	634	array-ref with the filenames.
		635
		636
		637	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		638
		639	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		640	behaviour and output format. In case of an error, C<$entries> will be
		641	C<undef>.
		642
		643	The flags are a combination of the following constants, ORed together (the
		644	flags will also be passed to the callback, possibly modified):
		645
		646	=over 4
		647
		648	=item IO::AIO::READDIR_DENTS
		649
		650	When this flag is off, then the callback gets an arrayref with of names
		651	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		652	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		653	entry in more detail.
		654
		655	C<$name> is the name of the entry.
		656
		657	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		658
		659	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		660	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		661	C<IO::AIO::DT_WHT>.
		662
		663	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		664	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		665	scalars are read-only: you can not modify them.
		666
		667	C<$inode> is the inode number (which might not be exact on systems with 64
		668	bit inode numbers and 32 bit perls). This field has unspecified content on
		669	systems that do not deliver the inode information.
		670
		671	=item IO::AIO::READDIR_DIRS_FIRST
		672
		673	When this flag is set, then the names will be returned in an order where
		674	likely directories come first. This is useful when you need to quickly
		675	find directories, or you want to find all directories while avoiding to
		676	stat() each entry.
		677
		678	If the system returns type information in readdir, then this is used
		679	to find directories directly. Otherwise, likely directories are files
		680	beginning with ".", or otherwise files with no dots, of which files with
		681	short names are tried first.
		682
		683	=item IO::AIO::READDIR_STAT_ORDER
		684
		685	When this flag is set, then the names will be returned in an order
		686	suitable for stat()'ing each one. That is, when you plan to stat()
		687	all files in the given directory, then the returned order will likely
		688	be fastest.
		689
		690	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		691	the likely dirs come first, resulting in a less optimal stat order.
		692
		693	=item IO::AIO::READDIR_FOUND_UNKNOWN
		694
		695	This flag should not be set when calling C<aio_readdirx>. Instead, it
		696	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		697	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		698	C<$type>'s are known, which can be used to speed up some algorithms.
		699
		700	=back
		701
		702
		703	=item aio_load $path, $data, $callback->($status)
		704
		705	This is a composite request that tries to fully load the given file into
		706	memory. Status is the same as with aio_read.
		707
		708	=cut
		709
		710	sub aio_load($$;$) {
		711	my ($path, undef, $cb) = @_;
		712	my $data = \$_[1];
		713
		714	my $pri = aioreq_pri;
		715	my $grp = aio_group $cb;
		716
		717	aioreq_pri $pri;
		718	add $grp aio_open $path, O_RDONLY, 0, sub {
		719	my $fh = shift
		720	or return $grp->result (-1);
		721
		722	aioreq_pri $pri;
		723	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		724	$grp->result ($_[0]);
		725	};
		726	};
		727
		728	$grp
		729	}
		730
		731	=item aio_copy $srcpath, $dstpath, $callback->($status)
		732
		733	Try to copy the I<file> (directories not supported as either source or
		734	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		735	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		736
		737	This is a composite request that creates the destination file with
		738	mode 0200 and copies the contents of the source file into it using
		739	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		740	uid/gid, in that order.
		741
		742	If an error occurs, the partial destination file will be unlinked, if
		743	possible, except when setting atime, mtime, access mode and uid/gid, where
		744	errors are being ignored.
		745
		746	=cut
		747
		748	sub aio_copy($$;$) {
		749	my ($src, $dst, $cb) = @_;
		750
		751	my $pri = aioreq_pri;
		752	my $grp = aio_group $cb;
		753
		754	aioreq_pri $pri;
		755	add $grp aio_open $src, O_RDONLY, 0, sub {
		756	if (my $src_fh = $_[0]) {
		757	my @stat = stat $src_fh; # hmm, might block over nfs?
		758
		759	aioreq_pri $pri;
		760	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		761	if (my $dst_fh = $_[0]) {
		762	aioreq_pri $pri;
		763	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		764	if ($_[0] == $stat[7]) {
		765	$grp->result (0);
		766	close $src_fh;
		767
		768	my $ch = sub {
		769	aioreq_pri $pri;
		770	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		771	aioreq_pri $pri;
		772	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		773	aioreq_pri $pri;
		774	add $grp aio_close $dst_fh;
		775	}
		776	};
		777	};
		778
		779	aioreq_pri $pri;
		780	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		781	if ($_[0] < 0 && $! == ENOSYS) {
		782	aioreq_pri $pri;
		783	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		784	} else {
		785	$ch->();
		786	}
		787	};
		788	} else {
		789	$grp->result (-1);
		790	close $src_fh;
		791	close $dst_fh;
		792
		793	aioreq $pri;
		794	add $grp aio_unlink $dst;
		795	}
		796	};
		797	} else {
		798	$grp->result (-1);
		799	}
		800	},
		801
		802	} else {
		803	$grp->result (-1);
		804	}
		805	};
		806
		807	$grp
		808	}
		809
		810	=item aio_move $srcpath, $dstpath, $callback->($status)
		811
		812	Try to move the I<file> (directories not supported as either source or
		813	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		814	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		815
		816	This is a composite request that tries to rename(2) the file first; if
		817	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		818	that is successful, unlinks the C<$srcpath>.
		819
		820	=cut
		821
		822	sub aio_move($$;$) {
		823	my ($src, $dst, $cb) = @_;
		824
		825	my $pri = aioreq_pri;
		826	my $grp = aio_group $cb;
		827
		828	aioreq_pri $pri;
		829	add $grp aio_rename $src, $dst, sub {
		830	if ($_[0] && $! == EXDEV) {
		831	aioreq_pri $pri;
		832	add $grp aio_copy $src, $dst, sub {
		833	$grp->result ($_[0]);
		834
		835	if (!$_[0]) {
		836	aioreq_pri $pri;
		837	add $grp aio_unlink $src;
		838	}
		839	};
		840	} else {
		841	$grp->result ($_[0]);
		842	}
		843	};
		844
		845	$grp
		846	}
437		847
438	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	848	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
439		849
440	Scans a directory (similar to C<aio_readdir>) but additionally tries to	850	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	851	efficiently separate the entries of directory C<$path> into two sets of
…		…
460		870
461	Implementation notes.	871	Implementation notes.
462		872
463	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	873	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
464		874
		875	If readdir returns file type information, then this is used directly to
		876	find directories.
		877
465	After reading the directory, the modification time, size etc. of the	878	Otherwise, after reading the directory, the modification time, size etc.
466	directory before and after the readdir is checked, and if they match (and	879	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	880	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	881	how many entries are directories (if >= 2). Otherwise, no knowledge of the
469	of subdirectories will be assumed.	882	number of subdirectories will be assumed.
470		883
471	Then entries will be sorted into likely directories (everything without	884	Then entries will be sorted into likely directories a non-initial dot
472	a non-initial dot currently) and likely non-directories (everything	885	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,	886	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	887	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	888	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	889	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	890	filesystems might detect the type of the entry without reading the inode
478	data (e.g. ext2fs filetype feature).	891	data (e.g. ext2fs filetype feature), even on systems that cannot return
		892	the filetype information on readdir.
479		893
480	If the known number of directories (link count - 2) has been reached, the	894	If the known number of directories (link count - 2) has been reached, the
481	rest of the entries is assumed to be non-directories.	895	rest of the entries is assumed to be non-directories.
482		896
483	This only works with certainty on POSIX (= UNIX) filesystems, which	897	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	901	as those tend to return 0 or 1 as link counts, which disables the
488	directory counting heuristic.	902	directory counting heuristic.
489		903
490	=cut	904	=cut
491		905
492	sub aio_scandir($$$) {	906	sub aio_scandir($$;$) {
493	my ($path, $maxreq, $cb) = @_;	907	my ($path, $maxreq, $cb) = @_;
494		908
495	my $pri = aioreq_pri;	909	my $pri = aioreq_pri;
496		910
497	my $grp = aio_group $cb;	911	my $grp = aio_group $cb;
…		…
505	my $now = time;	919	my $now = time;
506	my $hash1 = join ":", (stat _)[0,1,3,7,9];	920	my $hash1 = join ":", (stat _)[0,1,3,7,9];
507		921
508	# read the directory entries	922	# read the directory entries
509	aioreq_pri $pri;	923	aioreq_pri $pri;
510	add $grp aio_readdir $path, sub {	924	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
511	my $entries = shift	925	my $entries = shift
512	or return $grp->result ();	926	or return $grp->result ();
513		927
514	# stat the dir another time	928	# stat the dir another time
515	aioreq_pri $pri;	929	aioreq_pri $pri;
…		…
521	# take the slow route if anything looks fishy	935	# take the slow route if anything looks fishy
522	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	936	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
523	$ndirs = -1;	937	$ndirs = -1;
524	} else {	938	} else {
525	# if nlink == 2, we are finished	939	# if nlink == 2, we are finished
526	# on non-posix-fs's, we rely on nlink < 2	940	# for non-posix-fs's, we rely on nlink < 2
527	$ndirs = (stat _)[3] - 2	941	$ndirs = (stat _)[3] - 2
528	or return $grp->result ([], $entries);	942	or return $grp->result ([], $entries);
529	}	943	}
530		944
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);	945	my (@dirs, @nondirs);
539		946
540	my $statgrp = add $grp aio_group sub {	947	my $statgrp = add $grp aio_group sub {
541	$grp->result (\@dirs, \@nondirs);	948	$grp->result (\@dirs, \@nondirs);
542	};	949	};
543		950
544	limit $statgrp $maxreq;	951	limit $statgrp $maxreq;
545	feed $statgrp sub {	952	feed $statgrp sub {
546	return unless @$entries;	953	return unless @$entries;
547	my $entry = pop @$entries;	954	my $entry = shift @$entries;
548		955
549	aioreq_pri $pri;	956	aioreq_pri $pri;
550	add $statgrp aio_stat "$path/$entry/.", sub {	957	add $statgrp aio_stat "$path/$entry/.", sub {
551	if ($_[0] < 0) {	958	if ($_[0] < 0) {
552	push @nondirs, $entry;	959	push @nondirs, $entry;
…		…
573	};	980	};
574		981
575	$grp	982	$grp
576	}	983	}
577		984
		985	=item aio_rmtree $path, $callback->($status)
		986
		987	Delete a directory tree starting (and including) C<$path>, return the
		988	status of the final C<rmdir> only. This is a composite request that
		989	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		990	everything else.
		991
		992	=cut
		993
		994	sub aio_rmtree;
		995	sub aio_rmtree($;$) {
		996	my ($path, $cb) = @_;
		997
		998	my $pri = aioreq_pri;
		999	my $grp = aio_group $cb;
		1000
		1001	aioreq_pri $pri;
		1002	add $grp aio_scandir $path, 0, sub {
		1003	my ($dirs, $nondirs) = @_;
		1004
		1005	my $dirgrp = aio_group sub {
		1006	add $grp aio_rmdir $path, sub {
		1007	$grp->result ($_[0]);
		1008	};
		1009	};
		1010
		1011	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1012	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1013
		1014	add $grp $dirgrp;
		1015	};
		1016
		1017	$grp
		1018	}
		1019
		1020	=item aio_sync $callback->($status)
		1021
		1022	Asynchronously call sync and call the callback when finished.
		1023
578	=item aio_fsync $fh, $callback->($status)	1024	=item aio_fsync $fh, $callback->($status)
579		1025
580	Asynchronously call fsync on the given filehandle and call the callback	1026	Asynchronously call fsync on the given filehandle and call the callback
581	with the fsync result code.	1027	with the fsync result code.
582		1028
…		…
585	Asynchronously call fdatasync on the given filehandle and call the	1031	Asynchronously call fdatasync on the given filehandle and call the
586	callback with the fdatasync result code.	1032	callback with the fdatasync result code.
587		1033
588	If this call isn't available because your OS lacks it or it couldn't be	1034	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.	1035	detected, it will be emulated by calling C<fsync> instead.
		1036
		1037	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1038
		1039	Sync the data portion of the file specified by C<$offset> and C<$length>
		1040	to disk (but NOT the metadata), by calling the Linux-specific
		1041	sync_file_range call. If sync_file_range is not available or it returns
		1042	ENOSYS, then fdatasync or fsync is being substituted.
		1043
		1044	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1045	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1046	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1047	manpage for details.
		1048
		1049	=item aio_pathsync $path, $callback->($status)
		1050
		1051	This request tries to open, fsync and close the given path. This is a
		1052	composite request intended to sync directories after directory operations
		1053	(E.g. rename). This might not work on all operating systems or have any
		1054	specific effect, but usually it makes sure that directory changes get
		1055	written to disc. It works for anything that can be opened for read-only,
		1056	not just directories.
		1057
		1058	Future versions of this function might fall back to other methods when
		1059	C<fsync> on the directory fails (such as calling C<sync>).
		1060
		1061	Passes C<0> when everything went ok, and C<-1> on error.
		1062
		1063	=cut
		1064
		1065	sub aio_pathsync($;$) {
		1066	my ($path, $cb) = @_;
		1067
		1068	my $pri = aioreq_pri;
		1069	my $grp = aio_group $cb;
		1070
		1071	aioreq_pri $pri;
		1072	add $grp aio_open $path, O_RDONLY, 0, sub {
		1073	my ($fh) = @_;
		1074	if ($fh) {
		1075	aioreq_pri $pri;
		1076	add $grp aio_fsync $fh, sub {
		1077	$grp->result ($_[0]);
		1078
		1079	aioreq_pri $pri;
		1080	add $grp aio_close $fh;
		1081	};
		1082	} else {
		1083	$grp->result (-1);
		1084	}
		1085	};
		1086
		1087	$grp
		1088	}
		1089
		1090	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1091
		1092	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1093	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1094	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1095	scalar must only be modified in-place while an aio operation is pending on
		1096	it).
		1097
		1098	It calls the C<msync> function of your OS, if available, with the memory
		1099	area starting at C<$offset> in the string and ending C<$length> bytes
		1100	later. If C<$length> is negative, counts from the end, and if C<$length>
		1101	is C<undef>, then it goes till the end of the string. The flags can be
		1102	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1103	C<IO::AIO::MS_SYNC>.
		1104
		1105	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1106
		1107	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1108	scalars.
		1109
		1110	It touches (reads or writes) all memory pages in the specified
		1111	range inside the scalar. All caveats and parameters are the same
		1112	as for C<aio_msync>, above, except for flags, which must be either
		1113	C<0> (which reads all pages and ensures they are instantiated) or
		1114	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1115	writing an octet from it, which dirties the page).
		1116
		1117	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1118
		1119	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1120	scalars.
		1121
		1122	It reads in all the pages of the underlying storage into memory (if any)
		1123	and locks them, so they are not getting swapped/paged out or removed.
		1124
		1125	If C<$length> is undefined, then the scalar will be locked till the end.
		1126
		1127	On systems that do not implement C<mlock>, this function returns C<-1>
		1128	and sets errno to C<ENOSYS>.
		1129
		1130	Note that the corresponding C<munlock> is synchronous and is
		1131	documented under L<MISCELLANEOUS FUNCTIONS>.
		1132
		1133	=item aio_mlockall $flags, $callback->($status)
		1134
		1135	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1136	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1137
		1138	On systems that do not implement C<mlockall>, this function returns C<-1>
		1139	and sets errno to C<ENOSYS>.
		1140
		1141	Note that the corresponding C<munlockall> is synchronous and is
		1142	documented under L<MISCELLANEOUS FUNCTIONS>.
590		1143
591	=item aio_group $callback->(...)	1144	=item aio_group $callback->(...)
592		1145
593	This is a very special aio request: Instead of doing something, it is a	1146	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	1147	container for other aio requests, which is useful if you want to bundle
…		…
644	=item cancel $req	1197	=item cancel $req
645		1198
646	Cancels the request, if possible. Has the effect of skipping execution	1199	Cancels the request, if possible. Has the effect of skipping execution
647	when entering the B<execute> state and skipping calling the callback when	1200	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	1201	entering the the B<result> state, but will leave the request otherwise
649	untouched. That means that requests that currently execute will not be	1202	untouched (with the exception of readdir). That means that requests that
650	stopped and resources held by the request will not be freed prematurely.	1203	currently execute will not be stopped and resources held by the request
		1204	will not be freed prematurely.
651		1205
652	=item cb $req $callback->(...)	1206	=item cb $req $callback->(...)
653		1207
654	Replace (or simply set) the callback registered to the request.	1208	Replace (or simply set) the callback registered to the request.
655		1209
…		…
706	Their lifetime, simplified, looks like this: when they are empty, they	1260	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	1261	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	1262	C<done> state, they will also finish. Otherwise they will continue to
709	exist.	1263	exist.
710		1264
711	That means after creating a group you have some time to add requests. And	1265	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	1266	(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	1267	the C<poll_cb>). And in the callbacks of those requests, you can add
714	itself finish.	1268	further requests to the group. And only when all those requests have
		1269	finished will the the group itself finish.
715		1270
716	=over 4	1271	=over 4
717		1272
718	=item add $grp ...	1273	=item add $grp ...
719		1274
…		…
728	=item $grp->cancel_subs	1283	=item $grp->cancel_subs
729		1284
730	Cancel all subrequests and clears any feeder, but not the group request	1285	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.	1286	itself. Useful when you queued a lot of events but got a result early.
732		1287
		1288	The group request will finish normally (you cannot add requests to the
		1289	group).
		1290
733	=item $grp->result (...)	1291	=item $grp->result (...)
734		1292
735	Set the result value(s) that will be passed to the group callback when all	1293	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	1294	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,	1295	of errno (just like calling C<errno> without an error number). By default,
738	no argument will be passed and errno is zero.	1296	no argument will be passed and errno is zero.
739		1297
740	=item $grp->errno ([$errno])	1298	=item $grp->errno ([$errno])
741		1299
…		…
752	=item feed $grp $callback->($grp)	1310	=item feed $grp $callback->($grp)
753		1311
754	Sets a feeder/generator on this group: every group can have an attached	1312	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,	1313	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,	1314	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	1315	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>	1316	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
759	requests, delaying any later requests for a long time.	1317	delaying any later requests for a long time.
760		1318
761	To avoid this, and allow incremental generation of requests, you can	1319	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	1320	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>,	1321	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	1322	below) requests active in the group itself and is expected to queue more
…		…
768	not impose any limits).	1326	not impose any limits).
769		1327
770	If the feed does not queue more requests when called, it will be	1328	If the feed does not queue more requests when called, it will be
771	automatically removed from the group.	1329	automatically removed from the group.
772		1330
773	If the feed limit is C<0>, it will be set to C<2> automatically.	1331	If the feed limit is C<0> when this method is called, it will be set to
		1332	C<2> automatically.
774		1333
775	Example:	1334	Example:
776		1335
777	# stat all files in @files, but only ever use four aio requests concurrently:	1336	# stat all files in @files, but only ever use four aio requests concurrently:
778		1337
…		…
790	Sets the feeder limit for the group: The feeder will be called whenever	1349	Sets the feeder limit for the group: The feeder will be called whenever
791	the group contains less than this many requests.	1350	the group contains less than this many requests.
792		1351
793	Setting the limit to C<0> will pause the feeding process.	1352	Setting the limit to C<0> will pause the feeding process.
794		1353
		1354	The default value for the limit is C<0>, but note that setting a feeder
		1355	automatically bumps it up to C<2>.
		1356
795	=back	1357	=back
796		1358
797	=head2 SUPPORT FUNCTIONS	1359	=head2 SUPPORT FUNCTIONS
798		1360
		1361	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1362
799	=over 4	1363	=over 4
800		1364
801	=item $fileno = IO::AIO::poll_fileno	1365	=item $fileno = IO::AIO::poll_fileno
802		1366
803	Return the I<request result pipe file descriptor>. This filehandle must be	1367	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	1368	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	1369	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
806	to call C<poll_cb> to check the results.	1370	you have to call C<poll_cb> to check the results.
807		1371
808	See C<poll_cb> for an example.	1372	See C<poll_cb> for an example.
809		1373
810	=item IO::AIO::poll_cb	1374	=item IO::AIO::poll_cb
811		1375
812	Process all outstanding events on the result pipe. You have to call this	1376	Process some outstanding events on the result pipe. You have to call this
813	regularly. Returns the number of events processed. Returns immediately	1377	regularly. Returns C<0> if all events could be processed, or C<-1> if it
814	when no events are outstanding.	1378	returned earlier for whatever reason. Returns immediately when no events
		1379	are outstanding. The amount of events processed depends on the settings of
		1380	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
815		1381
816	If not all requests were processed for whatever reason, the filehandle	1382	If not all requests were processed for whatever reason, the filehandle
817	will still be ready when C<poll_cb> returns.	1383	will still be ready when C<poll_cb> returns, so normally you don't have to
		1384	do anything special to have it called later.
818		1385
819	Example: Install an Event watcher that automatically calls	1386	Example: Install an Event watcher that automatically calls
820	IO::AIO::poll_cb with high priority:	1387	IO::AIO::poll_cb with high priority (more examples can be found in the
		1388	SYNOPSIS section, at the top of this document):
821		1389
822	Event->io (fd => IO::AIO::poll_fileno,	1390	Event->io (fd => IO::AIO::poll_fileno,
823	poll => 'r', async => 1,	1391	poll => 'r', async => 1,
824	cb => \&IO::AIO::poll_cb);	1392	cb => \&IO::AIO::poll_cb);
825		1393
826	=item IO::AIO::poll_some $max_requests	1394	=item IO::AIO::poll_wait
827		1395
828	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests	1396	If there are any outstanding requests and none of them in the result
829	at a time.	1397	phase, wait till the result filehandle becomes ready for reading (simply
		1398	does a C<select> on the filehandle. This is useful if you want to
		1399	synchronously wait for some requests to finish).
830		1400
831	Useful if you want to ensure some level of interactiveness when perl is	1401	See C<nreqs> for an example.
832	not fast enough to process all requests in time.	1402
		1403	=item IO::AIO::poll
		1404
		1405	Waits until some requests have been handled.
		1406
		1407	Returns the number of requests processed, but is otherwise strictly
		1408	equivalent to:
		1409
		1410	IO::AIO::poll_wait, IO::AIO::poll_cb
		1411
		1412	=item IO::AIO::flush
		1413
		1414	Wait till all outstanding AIO requests have been handled.
		1415
		1416	Strictly equivalent to:
		1417
		1418	IO::AIO::poll_wait, IO::AIO::poll_cb
		1419	while IO::AIO::nreqs;
		1420
		1421	=item IO::AIO::max_poll_reqs $nreqs
		1422
		1423	=item IO::AIO::max_poll_time $seconds
		1424
		1425	These set the maximum number of requests (default C<0>, meaning infinity)
		1426	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1427	the maximum amount of time (default C<0>, meaning infinity) spent in
		1428	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1429	of time C<poll_cb> is allowed to use).
		1430
		1431	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1432	syscall per request processed, which is not normally a problem unless your
		1433	callbacks are really really fast or your OS is really really slow (I am
		1434	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1435
		1436	Setting these is useful if you want to ensure some level of
		1437	interactiveness when perl is not fast enough to process all requests in
		1438	time.
		1439
		1440	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
833		1441
834	Example: Install an Event watcher that automatically calls	1442	Example: Install an Event watcher that automatically calls
835	IO::AIO::poll_some with low priority, to ensure that other parts of the	1443	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.	1444	program get the CPU sometimes even under high AIO load.
837		1445
		1446	# try not to spend much more than 0.1s in poll_cb
		1447	IO::AIO::max_poll_time 0.1;
		1448
		1449	# use a low priority so other tasks have priority
838	Event->io (fd => IO::AIO::poll_fileno,	1450	Event->io (fd => IO::AIO::poll_fileno,
839	poll => 'r', nice => 1,	1451	poll => 'r', nice => 1,
840	cb => sub { IO::AIO::poll_some 256 });	1452	cb => &IO::AIO::poll_cb);
841		1453
842	=item IO::AIO::poll_wait	1454	=back
843		1455
844	Wait till the result filehandle becomes ready for reading (simply does a	1456	=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		1457
848	See C<nreqs> for an example.	1458	=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		1459
888	=item IO::AIO::min_parallel $nthreads	1460	=item IO::AIO::min_parallel $nthreads
889		1461
890	Set the minimum number of AIO threads to C<$nthreads>. The current	1462	Set the minimum number of AIO threads to C<$nthreads>. The current
891	default is C<8>, which means eight asynchronous operations can execute	1463	default is C<8>, which means eight asynchronous operations can execute
892	concurrently at any one time (the number of outstanding requests,	1464	concurrently at any one time (the number of outstanding requests,
893	however, is unlimited).	1465	however, is unlimited).
894		1466
895	IO::AIO starts threads only on demand, when an AIO request is queued and	1467	IO::AIO starts threads only on demand, when an AIO request is queued and
896	no free thread exists.	1468	no free thread exists. Please note that queueing up a hundred requests can
		1469	create demand for a hundred threads, even if it turns out that everything
		1470	is in the cache and could have been processed faster by a single thread.
897		1471
898	It is recommended to keep the number of threads relatively low, as some	1472	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	1473	Linux kernel versions will scale negatively with the number of threads
900	(higher parallelity => MUCH higher latency). With current Linux 2.6	1474	(higher parallelity => MUCH higher latency). With current Linux 2.6
901	versions, 4-32 threads should be fine.	1475	versions, 4-32 threads should be fine.
…		…
915	This module automatically runs C<max_parallel 0> at program end, to ensure	1489	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.	1490	that all threads are killed and that there are no outstanding requests.
917		1491
918	Under normal circumstances you don't need to call this function.	1492	Under normal circumstances you don't need to call this function.
919		1493
		1494	=item IO::AIO::max_idle $nthreads
		1495
		1496	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1497	threads that did not get a request to process within 10 seconds). That
		1498	means if a thread becomes idle while C<$nthreads> other threads are also
		1499	idle, it will free its resources and exit.
		1500
		1501	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1502	to allow for extremely high load situations, but want to free resources
		1503	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1504
		1505	The default is probably ok in most situations, especially if thread
		1506	creation is fast. If thread creation is very slow on your system you might
		1507	want to use larger values.
		1508
920	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1509	=item IO::AIO::max_outstanding $maxreqs
921		1510
922	This is a very bad function to use in interactive programs because it	1511	This is a very bad function to use in interactive programs because it
923	blocks, and a bad way to reduce concurrency because it is inexact: Better	1512	blocks, and a bad way to reduce concurrency because it is inexact: Better
924	use an C<aio_group> together with a feed callback.	1513	use an C<aio_group> together with a feed callback.
925		1514
926	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1515	Sets the maximum number of outstanding requests to C<$nreqs>. If you
927	to queue up more than this number of requests, the next call to the	1516	do queue up more than this number of requests, the next call to the
928	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)	1517	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.	1518	function will block until the limit is no longer exceeded.
930		1519
931	The default value is very large, so there is no practical limit on the	1520	The default value is very large, so there is no practical limit on the
932	number of outstanding requests.	1521	number of outstanding requests.
933		1522
934	You can still queue as many requests as you want. Therefore,	1523	You can still queue as many requests as you want. Therefore,
935	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1524	C<max_outstanding> is mainly useful in simple scripts (with low values) or
936	as a stop gap to shield against fatal memory overflow (with large values).	1525	as a stop gap to shield against fatal memory overflow (with large values).
937		1526
938	=back	1527	=back
939		1528
		1529	=head3 STATISTICAL INFORMATION
		1530
		1531	=over
		1532
		1533	=item IO::AIO::nreqs
		1534
		1535	Returns the number of requests currently in the ready, execute or pending
		1536	states (i.e. for which their callback has not been invoked yet).
		1537
		1538	Example: wait till there are no outstanding requests anymore:
		1539
		1540	IO::AIO::poll_wait, IO::AIO::poll_cb
		1541	while IO::AIO::nreqs;
		1542
		1543	=item IO::AIO::nready
		1544
		1545	Returns the number of requests currently in the ready state (not yet
		1546	executed).
		1547
		1548	=item IO::AIO::npending
		1549
		1550	Returns the number of requests currently in the pending state (executed,
		1551	but not yet processed by poll_cb).
		1552
		1553	=back
		1554
		1555	=head3 MISCELLANEOUS FUNCTIONS
		1556
		1557	IO::AIO implements some functions that might be useful, but are not
		1558	asynchronous.
		1559
		1560	=over 4
		1561
		1562	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1563
		1564	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1565	but is blocking (this makes most sense if you know the input data is
		1566	likely cached already and the output filehandle is set to non-blocking
		1567	operations).
		1568
		1569	Returns the number of bytes copied, or C<-1> on error.
		1570
		1571	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1572
		1573	Simply calls the C<posix_fadvise> function (see it's
		1574	manpage for details). The following advice constants are
		1575	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1576	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1577	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1578
		1579	On systems that do not implement C<posix_fadvise>, this function returns
		1580	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1581
		1582	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1583
		1584	Memory-maps a file (or anonymous memory range) and attaches it to the
		1585	given C<$scalar>, which will act like a string scalar.
		1586
		1587	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1588	change the string length, and most read-only operations such as copying it
		1589	or searching it with regexes and so on.
		1590
		1591	Anything else is unsafe and will, at best, result in memory leaks.
		1592
		1593	The memory map associated with the C<$scalar> is automatically removed
		1594	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1595	C<IO::AIO::munmap> functions are called.
		1596
		1597	This calls the C<mmap>(2) function internally. See your system's manual
		1598	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1599
		1600	The C<$length> must be larger than zero and smaller than the actual
		1601	filesize.
		1602
		1603	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1604	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1605
		1606	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1607	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1608	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1609	(which is set to C<MAP_ANON> if your system only provides this
		1610	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1611	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1612	C<IO::AIO::MAP_NONBLOCK>
		1613
		1614	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1615
		1616	C<$offset> is the offset from the start of the file - it generally must be
		1617	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1618
		1619	Example:
		1620
		1621	use Digest::MD5;
		1622	use IO::AIO;
		1623
		1624	open my $fh, "<verybigfile"
		1625	or die "$!";
		1626
		1627	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1628	or die "verybigfile: $!";
		1629
		1630	my $fast_md5 = md5 $data;
		1631
		1632	=item IO::AIO::munmap $scalar
		1633
		1634	Removes a previous mmap and undefines the C<$scalar>.
		1635
		1636	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1637
		1638	Calls the C<munlock> function, undoing the effects of a previous
		1639	C<aio_mlock> call (see its description for details).
		1640
		1641	=item IO::AIO::munlockall
		1642
		1643	Calls the C<munlockall> function.
		1644
		1645	On systems that do not implement C<munlockall>, this function returns
		1646	ENOSYS, otherwise the return value of C<munlockall>.
		1647
		1648	=back
		1649
940	=cut	1650	=cut
941		1651
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;	1652	min_parallel 8;
959		1653
		1654	END { flush }
		1655
960	1;	1656	1;
		1657
		1658	=head1 EVENT LOOP INTEGRATION
		1659
		1660	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1661	automatically into many event loops:
		1662
		1663	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1664	use AnyEvent::AIO;
		1665
		1666	You can also integrate IO::AIO manually into many event loops, here are
		1667	some examples of how to do this:
		1668
		1669	# EV integration
		1670	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1671
		1672	# Event integration
		1673	Event->io (fd => IO::AIO::poll_fileno,
		1674	poll => 'r',
		1675	cb => \&IO::AIO::poll_cb);
		1676
		1677	# Glib/Gtk2 integration
		1678	add_watch Glib::IO IO::AIO::poll_fileno,
		1679	in => sub { IO::AIO::poll_cb; 1 };
		1680
		1681	# Tk integration
		1682	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1683	readable => \&IO::AIO::poll_cb);
		1684
		1685	# Danga::Socket integration
		1686	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1687	\&IO::AIO::poll_cb);
961		1688
962	=head2 FORK BEHAVIOUR	1689	=head2 FORK BEHAVIOUR
963		1690
964	This module should do "the right thing" when the process using it forks:	1691	This module should do "the right thing" when the process using it forks:
965		1692
…		…
983	bytes of memory. In addition, stat requests need a stat buffer (possibly	1710	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	1711	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	1712	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.	1713	will consume memory till the request has entered the done state.
987		1714
988	This is now awfully much, so queuing lots of requests is not usually a	1715	This is not awfully much, so queuing lots of requests is not usually a
989	problem.	1716	problem.
990		1717
991	Per-thread usage:	1718	Per-thread usage:
992		1719
993	In the execution phase, some aio requests require more memory for	1720	In the execution phase, some aio requests require more memory for
…		…
998		1725
999	Known bugs will be fixed in the next release.	1726	Known bugs will be fixed in the next release.
1000		1727
1001	=head1 SEE ALSO	1728	=head1 SEE ALSO
1002		1729
1003	L<Coro::AIO>.	1730	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1731	more natural syntax.
1004		1732
1005	=head1 AUTHOR	1733	=head1 AUTHOR
1006		1734
1007	Marc Lehmann <schmorp@schmorp.de>	1735	Marc Lehmann <schmorp@schmorp.de>
1008	http://home.schmorp.de/	1736	http://home.schmorp.de/

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