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Revision 1.77 by root, Wed Oct 25 17:57:30 2006 UTC vs.
Revision 1.200 by root, Wed Jun 29 21:45:09 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_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);	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_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::idle_timeout $seconds
		264	IO::AIO::max_outstanding $maxreqs
		265	IO::AIO::nreqs
		266	IO::AIO::nready
		267	IO::AIO::npending
		268
		269	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		270	IO::AIO::fadvise $fh, $offset, $len, $advice
		271	IO::AIO::madvise $scalar, $offset, $length, $advice
		272	IO::AIO::mprotect $scalar, $offset, $length, $protect
		273	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		274	IO::AIO::munlockall
		275
149	=head2 AIO FUNCTIONS	276	=head2 AIO REQUEST FUNCTIONS
150		277
151	All the C<aio_*> calls are more or less thin wrappers around the syscall	278	All the C<aio_*> calls are more or less thin wrappers around the syscall
152	with the same name (sans C<aio_>). The arguments are similar or identical,	279	with the same name (sans C<aio_>). The arguments are similar or identical,
153	and they all accept an additional (and optional) C<$callback> argument	280	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	281	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	282	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	283	perl, which usually delivers "false") as its sole argument after the given
157	syscall has been executed asynchronously.	284	syscall has been executed asynchronously.
158		285
159	All functions expecting a filehandle keep a copy of the filehandle	286	All functions expecting a filehandle keep a copy of the filehandle
160	internally until the request has finished.	287	internally until the request has finished.
161		288
162	All requests return objects of type L<IO::AIO::REQ> that allow further	289	All functions return request objects of type L<IO::AIO::REQ> that allow
163	manipulation of those requests while they are in-flight.	290	further manipulation of those requests while they are in-flight.
164		291
165	The pathnames you pass to these routines I<must> be absolute and	292	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	293	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	294	request is being executed, the current working directory could have
168	changed. Alternatively, you can make sure that you never change the	295	changed. Alternatively, you can make sure that you never change the
169	current working directory.	296	current working directory anywhere in the program and then use relative
		297	paths.
170		298
171	To encode pathnames to byte form, either make sure you either: a)	299	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	300	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	301	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	302	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)	303	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176	use something else.	304	use something else to ensure your scalar has the correct contents.
		305
		306	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		307	handles correctly whether it is set or not.
177		308
178	=over 4	309	=over 4
179		310
180	=item aioreq_pri $pri	311	=item $prev_pri = aioreq_pri [$pri]
181		312
182	Sets the priority for the next aio request. The default priority	313	Returns the priority value that would be used for the next request and, if
		314	C<$pri> is given, sets the priority for the next aio request.
		315
183	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	316	The default priority is C<0>, the minimum and maximum priorities are C<-4>
184	respectively. Requests with higher priority will be serviced first.	317	and C<4>, respectively. Requests with higher priority will be serviced
		318	first.
185		319
186	The priority will be reset to C<0> after each call to one of the C<aio_>	320	The priority will be reset to C<0> after each call to one of the C<aio_*>
187	functions.	321	functions.
188		322
189	Example: open a file with low priority, then read something from it with	323	Example: open a file with low priority, then read something from it with
190	higher priority so the read request is serviced before other low priority	324	higher priority so the read request is serviced before other low priority
191	open requests (potentially spamming the cache):	325	open requests (potentially spamming the cache):
…		…
198	aio_read $_[0], ..., sub {	332	aio_read $_[0], ..., sub {
199	...	333	...
200	};	334	};
201	};	335	};
202		336
		337
203	=item aioreq_nice $pri_adjust	338	=item aioreq_nice $pri_adjust
204		339
205	Similar to C<aioreq_pri>, but subtracts the given value from the current	340	Similar to C<aioreq_pri>, but subtracts the given value from the current
206	priority, so effects are cumulative.	341	priority, so the effect is cumulative.
		342
207		343
208	=item aio_open $pathname, $flags, $mode, $callback->($fh)	344	=item aio_open $pathname, $flags, $mode, $callback->($fh)
209		345
210	Asynchronously open or create a file and call the callback with a newly	346	Asynchronously open or create a file and call the callback with a newly
211	created filehandle for the file.	347	created filehandle for the file.
…		…
217	list. They are the same as used by C<sysopen>.	353	list. They are the same as used by C<sysopen>.
218		354
219	Likewise, C<$mode> specifies the mode of the newly created file, if it	355	Likewise, C<$mode> specifies the mode of the newly created file, if it
220	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	356	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
221	except that it is mandatory (i.e. use C<0> if you don't create new files,	357	except that it is mandatory (i.e. use C<0> if you don't create new files,
222	and C<0666> or C<0777> if you do).	358	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		359	by the umask in effect then the request is being executed, so better never
		360	change the umask.
223		361
224	Example:	362	Example:
225		363
226	aio_open "/etc/passwd", O_RDONLY, 0, sub {	364	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
227	if ($_[0]) {	365	if ($_[0]) {
228	print "open successful, fh is $_[0]\n";	366	print "open successful, fh is $_[0]\n";
229	...	367	...
230	} else {	368	} else {
231	die "open failed: $!\n";	369	die "open failed: $!\n";
232	}	370	}
233	};	371	};
234		372
		373	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		374	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		375	following POSIX and non-POSIX constants are available (missing ones on
		376	your system are, as usual, C<0>):
		377
		378	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		379	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		380	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		381
		382
235	=item aio_close $fh, $callback->($status)	383	=item aio_close $fh, $callback->($status)
236		384
237	Asynchronously close a file and call the callback with the result	385	Asynchronously close a file and call the callback with the result
238	code. I<WARNING:> although accepted, you should not pass in a perl	386	code.
239	filehandle here, as perl will likely close the file descriptor another
240	time when the filehandle is destroyed. Normally, you can safely call perls
241	C<close> or just let filehandles go out of scope.
242		387
243	This is supposed to be a bug in the API, so that might change. It's	388	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
244	therefore best to avoid this function.	389	closing the file descriptor associated with the filehandle itself.
		390
		391	Therefore, C<aio_close> will not close the filehandle - instead it will
		392	use dup2 to overwrite the file descriptor with the write-end of a pipe
		393	(the pipe fd will be created on demand and will be cached).
		394
		395	Or in other words: the file descriptor will be closed, but it will not be
		396	free for reuse until the perl filehandle is closed.
		397
		398	=cut
245		399
246	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	400	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
247		401
248	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	402	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
249		403
250	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	404	Reads or writes C<$length> bytes from or to the specified C<$fh> and
251	into the scalar given by C<data> and offset C<dataoffset> and calls the	405	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
252	callback without the actual number of bytes read (or -1 on error, just	406	and calls the callback without the actual number of bytes read (or -1 on
253	like the syscall).	407	error, just like the syscall).
		408
		409	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		410	offset plus the actual number of bytes read.
		411
		412	If C<$offset> is undefined, then the current file descriptor offset will
		413	be used (and updated), otherwise the file descriptor offset will not be
		414	changed by these calls.
		415
		416	If C<$length> is undefined in C<aio_write>, use the remaining length of
		417	C<$data>.
		418
		419	If C<$dataoffset> is less than zero, it will be counted from the end of
		420	C<$data>.
254		421
255	The C<$data> scalar I<MUST NOT> be modified in any way while the request	422	The C<$data> scalar I<MUST NOT> be modified in any way while the request
256	is outstanding. Modifying it can result in segfaults or WW3 (if the	423	is outstanding. Modifying it can result in segfaults or World War III (if
257	necessary/optional hardware is installed).	424	the necessary/optional hardware is installed).
258		425
259	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	426	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
260	offset C<0> within the scalar:	427	offset C<0> within the scalar:
261		428
262	aio_read $fh, 7, 15, $buffer, 0, sub {	429	aio_read $fh, 7, 15, $buffer, 0, sub {
263	$_[0] > 0 or die "read error: $!";	430	$_[0] > 0 or die "read error: $!";
264	print "read $_[0] bytes: <$buffer>\n";	431	print "read $_[0] bytes: <$buffer>\n";
265	};	432	};
266		433
267	=item aio_move $srcpath, $dstpath, $callback->($status)
268
269	Try to move the I<file> (directories not supported as either source or
270	destination) from C<$srcpath> to C<$dstpath> and call the callback with
271	the C<0> (error) or C<-1> ok.
272
273	This is a composite request that tries to rename(2) the file first. If
274	rename files with C<EXDEV>, it creates the destination file with mode 0200
275	and copies the contents of the source file into it using C<aio_sendfile>,
276	followed by restoring atime, mtime, access mode and uid/gid, in that
277	order, and unlinking the C<$srcpath>.
278
279	If an error occurs, the partial destination file will be unlinked, if
280	possible, except when setting atime, mtime, access mode and uid/gid, where
281	errors are being ignored.
282
283	=cut
284
285	sub aio_move($$$) {
286	my ($src, $dst, $cb) = @_;
287
288	my $grp = aio_group $cb;
289
290	add $grp aio_rename $src, $dst, sub {
291	if ($_[0] && $! == EXDEV) {
292	add $grp aio_open $src, O_RDONLY, 0, sub {
293	if (my $src_fh = $_[0]) {
294	my @stat = stat $src_fh;
295
296	add $grp aio_open $dst, O_WRONLY, 0200, sub {
297	if (my $dst_fh = $_[0]) {
298	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
299	close $src_fh;
300
301	if ($_[0] == $stat[7]) {
302	utime $stat[8], $stat[9], $dst;
303	chmod $stat[2] & 07777, $dst_fh;
304	chown $stat[4], $stat[5], $dst_fh;
305	close $dst_fh;
306
307	add $grp aio_unlink $src, sub {
308	$grp->result ($_[0]);
309	};
310	} else {
311	my $errno = $!;
312	add $grp aio_unlink $dst, sub {
313	$! = $errno;
314	$grp->result (-1);
315	};
316	}
317	};
318	} else {
319	$grp->result (-1);
320	}
321	},
322
323	} else {
324	$grp->result (-1);
325	}
326	};
327	} else {
328	$grp->result ($_[0]);
329	}
330	};
331
332	$grp
333	}
334		434
335	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	435	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
336		436
337	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	437	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
338	reading at byte offset C<$in_offset>, and starts writing at the current	438	reading at byte offset C<$in_offset>, and starts writing at the current
339	file offset of C<$out_fh>. Because of that, it is not safe to issue more	439	file offset of C<$out_fh>. Because of that, it is not safe to issue more
340	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	440	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
341	other.	441	other. The same C<$in_fh> works fine though, as this function does not
		442	move or use the file offset of C<$in_fh>.
342		443
		444	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		445	are written, and there is no way to find out how many more bytes have been
		446	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		447	number of bytes written to C<$out_fh>. Only if the result value equals
		448	C<$length> one can assume that C<$length> bytes have been read.
		449
		450	Unlike with other C<aio_> functions, it makes a lot of sense to use
		451	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		452	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		453	the socket I/O will be non-blocking. Note, however, that you can run
		454	into a trap where C<aio_sendfile> reads some data with readahead, then
		455	fails to write all data, and when the socket is ready the next time, the
		456	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		457	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		458	resource usage.
		459
343	This call tries to make use of a native C<sendfile> syscall to provide	460	This call tries to make use of a native C<sendfile>-like syscall to
344	zero-copy operation. For this to work, C<$out_fh> should refer to a	461	provide zero-copy operation. For this to work, C<$out_fh> should refer to
345	socket, and C<$in_fh> should refer to mmap'able file.	462	a socket, and C<$in_fh> should refer to an mmap'able file.
346		463
347	If the native sendfile call fails or is not implemented, it will be	464	If a native sendfile cannot be found or it fails with C<ENOSYS>,
348	emulated, so you can call C<aio_sendfile> on any type of filehandle	465	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		466	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
349	regardless of the limitations of the operating system.	467	type of filehandle regardless of the limitations of the operating system.
350		468
351	Please note, however, that C<aio_sendfile> can read more bytes from	469	As native sendfile syscalls (as practically any non-POSIX interface hacked
352	C<$in_fh> than are written, and there is no way to find out how many	470	together in a hurry to improve benchmark numbers) tend to be rather buggy
353	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	471	on many systems, this implementation tries to work around some known bugs
354	provides the number of bytes written to C<$out_fh>. Only if the result	472	in Linux and FreeBSD kernels (probably others, too), but that might fail,
355	value equals C<$length> one can assume that C<$length> bytes have been	473	so you really really should check the return value of C<aio_sendfile> -
356	read.	474	fewre bytes than expected might have been transferred.
		475
357		476
358	=item aio_readahead $fh,$offset,$length, $callback->($retval)	477	=item aio_readahead $fh,$offset,$length, $callback->($retval)
359		478
360	C<aio_readahead> populates the page cache with data from a file so that	479	C<aio_readahead> populates the page cache with data from a file so that
361	subsequent reads from that file will not block on disk I/O. The C<$offset>	480	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
367	file. The current file offset of the file is left unchanged.	486	file. The current file offset of the file is left unchanged.
368		487
369	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	488	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
370	emulated by simply reading the data, which would have a similar effect.	489	emulated by simply reading the data, which would have a similar effect.
371		490
		491
372	=item aio_stat $fh_or_path, $callback->($status)	492	=item aio_stat $fh_or_path, $callback->($status)
373		493
374	=item aio_lstat $fh, $callback->($status)	494	=item aio_lstat $fh, $callback->($status)
375		495
376	Works like perl's C<stat> or C<lstat> in void context. The callback will	496	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
381	for an explanation.	501	for an explanation.
382		502
383	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	503	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
384	error when stat'ing a large file, the results will be silently truncated	504	error when stat'ing a large file, the results will be silently truncated
385	unless perl itself is compiled with large file support.	505	unless perl itself is compiled with large file support.
		506
		507	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		508	following constants and functions (if not implemented, the constants will
		509	be C<0> and the functions will either C<croak> or fall back on traditional
		510	behaviour).
		511
		512	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		513	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		514	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
386		515
387	Example: Print the length of F</etc/passwd>:	516	Example: Print the length of F</etc/passwd>:
388		517
389	aio_stat "/etc/passwd", sub {	518	aio_stat "/etc/passwd", sub {
390	$_[0] and die "stat failed: $!";	519	$_[0] and die "stat failed: $!";
391	print "size is ", -s _, "\n";	520	print "size is ", -s _, "\n";
392	};	521	};
393		522
		523
		524	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		525
		526	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		527	whether a file handle or path was passed.
		528
		529	On success, the callback is passed a hash reference with the following
		530	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		531	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		532	is passed.
		533
		534	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		535	C<ST_NOSUID>.
		536
		537	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		538	their correct value when available, or to C<0> on systems that do
		539	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		540	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		541	C<ST_NODIRATIME> and C<ST_RELATIME>.
		542
		543	Example: stat C</wd> and dump out the data if successful.
		544
		545	aio_statvfs "/wd", sub {
		546	my $f = $_[0]
		547	or die "statvfs: $!";
		548
		549	use Data::Dumper;
		550	say Dumper $f;
		551	};
		552
		553	# result:
		554	{
		555	bsize => 1024,
		556	bfree => 4333064312,
		557	blocks => 10253828096,
		558	files => 2050765568,
		559	flag => 4096,
		560	favail => 2042092649,
		561	bavail => 4333064312,
		562	ffree => 2042092649,
		563	namemax => 255,
		564	frsize => 1024,
		565	fsid => 1810
		566	}
		567
		568
		569	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		570
		571	Works like perl's C<utime> function (including the special case of $atime
		572	and $mtime being undef). Fractional times are supported if the underlying
		573	syscalls support them.
		574
		575	When called with a pathname, uses utimes(2) if available, otherwise
		576	utime(2). If called on a file descriptor, uses futimes(2) if available,
		577	otherwise returns ENOSYS, so this is not portable.
		578
		579	Examples:
		580
		581	# set atime and mtime to current time (basically touch(1)):
		582	aio_utime "path", undef, undef;
		583	# set atime to current time and mtime to beginning of the epoch:
		584	aio_utime "path", time, undef; # undef==0
		585
		586
		587	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		588
		589	Works like perl's C<chown> function, except that C<undef> for either $uid
		590	or $gid is being interpreted as "do not change" (but -1 can also be used).
		591
		592	Examples:
		593
		594	# same as "chown root path" in the shell:
		595	aio_chown "path", 0, -1;
		596	# same as above:
		597	aio_chown "path", 0, undef;
		598
		599
		600	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		601
		602	Works like truncate(2) or ftruncate(2).
		603
		604
		605	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		606
		607	Works like perl's C<chmod> function.
		608
		609
394	=item aio_unlink $pathname, $callback->($status)	610	=item aio_unlink $pathname, $callback->($status)
395		611
396	Asynchronously unlink (delete) a file and call the callback with the	612	Asynchronously unlink (delete) a file and call the callback with the
397	result code.	613	result code.
398		614
		615
		616	=item aio_mknod $path, $mode, $dev, $callback->($status)
		617
		618	[EXPERIMENTAL]
		619
		620	Asynchronously create a device node (or fifo). See mknod(2).
		621
		622	The only (POSIX-) portable way of calling this function is:
		623
		624	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		625
		626	See C<aio_stat> for info about some potentially helpful extra constants
		627	and functions.
		628
399	=item aio_link $srcpath, $dstpath, $callback->($status)	629	=item aio_link $srcpath, $dstpath, $callback->($status)
400		630
401	Asynchronously create a new link to the existing object at C<$srcpath> at	631	Asynchronously create a new link to the existing object at C<$srcpath> at
402	the path C<$dstpath> and call the callback with the result code.	632	the path C<$dstpath> and call the callback with the result code.
403		633
		634
404	=item aio_symlink $srcpath, $dstpath, $callback->($status)	635	=item aio_symlink $srcpath, $dstpath, $callback->($status)
405		636
406	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	637	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
407	the path C<$dstpath> and call the callback with the result code.	638	the path C<$dstpath> and call the callback with the result code.
408		639
		640
		641	=item aio_readlink $path, $callback->($link)
		642
		643	Asynchronously read the symlink specified by C<$path> and pass it to
		644	the callback. If an error occurs, nothing or undef gets passed to the
		645	callback.
		646
		647
409	=item aio_rename $srcpath, $dstpath, $callback->($status)	648	=item aio_rename $srcpath, $dstpath, $callback->($status)
410		649
411	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	650	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
412	rename(2) and call the callback with the result code.	651	rename(2) and call the callback with the result code.
413		652
		653
		654	=item aio_mkdir $pathname, $mode, $callback->($status)
		655
		656	Asynchronously mkdir (create) a directory and call the callback with
		657	the result code. C<$mode> will be modified by the umask at the time the
		658	request is executed, so do not change your umask.
		659
		660
414	=item aio_rmdir $pathname, $callback->($status)	661	=item aio_rmdir $pathname, $callback->($status)
415		662
416	Asynchronously rmdir (delete) a directory and call the callback with the	663	Asynchronously rmdir (delete) a directory and call the callback with the
417	result code.	664	result code.
		665
418		666
419	=item aio_readdir $pathname, $callback->($entries)	667	=item aio_readdir $pathname, $callback->($entries)
420		668
421	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	669	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
422	directory (i.e. opendir + readdir + closedir). The entries will not be	670	directory (i.e. opendir + readdir + closedir). The entries will not be
423	sorted, and will B<NOT> include the C<.> and C<..> entries.	671	sorted, and will B<NOT> include the C<.> and C<..> entries.
424		672
425	The callback a single argument which is either C<undef> or an array-ref	673	The callback is passed a single argument which is either C<undef> or an
426	with the filenames.	674	array-ref with the filenames.
		675
		676
		677	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		678
		679	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		680	behaviour and output format. In case of an error, C<$entries> will be
		681	C<undef>.
		682
		683	The flags are a combination of the following constants, ORed together (the
		684	flags will also be passed to the callback, possibly modified):
		685
		686	=over 4
		687
		688	=item IO::AIO::READDIR_DENTS
		689
		690	When this flag is off, then the callback gets an arrayref consisting of
		691	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		692	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		693	entry in more detail.
		694
		695	C<$name> is the name of the entry.
		696
		697	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		698
		699	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		700	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		701	C<IO::AIO::DT_WHT>.
		702
		703	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		704	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		705	scalars are read-only: you can not modify them.
		706
		707	C<$inode> is the inode number (which might not be exact on systems with 64
		708	bit inode numbers and 32 bit perls). This field has unspecified content on
		709	systems that do not deliver the inode information.
		710
		711	=item IO::AIO::READDIR_DIRS_FIRST
		712
		713	When this flag is set, then the names will be returned in an order where
		714	likely directories come first, in optimal stat order. This is useful when
		715	you need to quickly find directories, or you want to find all directories
		716	while avoiding to stat() each entry.
		717
		718	If the system returns type information in readdir, then this is used
		719	to find directories directly. Otherwise, likely directories are names
		720	beginning with ".", or otherwise names with no dots, of which names with
		721	short names are tried first.
		722
		723	=item IO::AIO::READDIR_STAT_ORDER
		724
		725	When this flag is set, then the names will be returned in an order
		726	suitable for stat()'ing each one. That is, when you plan to stat()
		727	all files in the given directory, then the returned order will likely
		728	be fastest.
		729
		730	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		731	the likely dirs come first, resulting in a less optimal stat order.
		732
		733	=item IO::AIO::READDIR_FOUND_UNKNOWN
		734
		735	This flag should not be set when calling C<aio_readdirx>. Instead, it
		736	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		737	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		738	C<$type>'s are known, which can be used to speed up some algorithms.
		739
		740	=back
		741
		742
		743	=item aio_load $path, $data, $callback->($status)
		744
		745	This is a composite request that tries to fully load the given file into
		746	memory. Status is the same as with aio_read.
		747
		748	=cut
		749
		750	sub aio_load($$;$) {
		751	my ($path, undef, $cb) = @_;
		752	my $data = \$_[1];
		753
		754	my $pri = aioreq_pri;
		755	my $grp = aio_group $cb;
		756
		757	aioreq_pri $pri;
		758	add $grp aio_open $path, O_RDONLY, 0, sub {
		759	my $fh = shift
		760	or return $grp->result (-1);
		761
		762	aioreq_pri $pri;
		763	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		764	$grp->result ($_[0]);
		765	};
		766	};
		767
		768	$grp
		769	}
		770
		771	=item aio_copy $srcpath, $dstpath, $callback->($status)
		772
		773	Try to copy the I<file> (directories not supported as either source or
		774	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		775	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		776
		777	This is a composite request that creates the destination file with
		778	mode 0200 and copies the contents of the source file into it using
		779	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		780	uid/gid, in that order.
		781
		782	If an error occurs, the partial destination file will be unlinked, if
		783	possible, except when setting atime, mtime, access mode and uid/gid, where
		784	errors are being ignored.
		785
		786	=cut
		787
		788	sub aio_copy($$;$) {
		789	my ($src, $dst, $cb) = @_;
		790
		791	my $pri = aioreq_pri;
		792	my $grp = aio_group $cb;
		793
		794	aioreq_pri $pri;
		795	add $grp aio_open $src, O_RDONLY, 0, sub {
		796	if (my $src_fh = $_[0]) {
		797	my @stat = stat $src_fh; # hmm, might block over nfs?
		798
		799	aioreq_pri $pri;
		800	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		801	if (my $dst_fh = $_[0]) {
		802	aioreq_pri $pri;
		803	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		804	if ($_[0] == $stat[7]) {
		805	$grp->result (0);
		806	close $src_fh;
		807
		808	my $ch = sub {
		809	aioreq_pri $pri;
		810	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		811	aioreq_pri $pri;
		812	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		813	aioreq_pri $pri;
		814	add $grp aio_close $dst_fh;
		815	}
		816	};
		817	};
		818
		819	aioreq_pri $pri;
		820	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		821	if ($_[0] < 0 && $! == ENOSYS) {
		822	aioreq_pri $pri;
		823	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		824	} else {
		825	$ch->();
		826	}
		827	};
		828	} else {
		829	$grp->result (-1);
		830	close $src_fh;
		831	close $dst_fh;
		832
		833	aioreq $pri;
		834	add $grp aio_unlink $dst;
		835	}
		836	};
		837	} else {
		838	$grp->result (-1);
		839	}
		840	},
		841
		842	} else {
		843	$grp->result (-1);
		844	}
		845	};
		846
		847	$grp
		848	}
		849
		850	=item aio_move $srcpath, $dstpath, $callback->($status)
		851
		852	Try to move the I<file> (directories not supported as either source or
		853	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		854	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		855
		856	This is a composite request that tries to rename(2) the file first; if
		857	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		858	that is successful, unlinks the C<$srcpath>.
		859
		860	=cut
		861
		862	sub aio_move($$;$) {
		863	my ($src, $dst, $cb) = @_;
		864
		865	my $pri = aioreq_pri;
		866	my $grp = aio_group $cb;
		867
		868	aioreq_pri $pri;
		869	add $grp aio_rename $src, $dst, sub {
		870	if ($_[0] && $! == EXDEV) {
		871	aioreq_pri $pri;
		872	add $grp aio_copy $src, $dst, sub {
		873	$grp->result ($_[0]);
		874
		875	unless ($_[0]) {
		876	aioreq_pri $pri;
		877	add $grp aio_unlink $src;
		878	}
		879	};
		880	} else {
		881	$grp->result ($_[0]);
		882	}
		883	};
		884
		885	$grp
		886	}
427		887
428	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	888	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
429		889
430	Scans a directory (similar to C<aio_readdir>) but additionally tries to	890	Scans a directory (similar to C<aio_readdir>) but additionally tries to
431	efficiently separate the entries of directory C<$path> into two sets of	891	efficiently separate the entries of directory C<$path> into two sets of
…		…
433	recurse into (everything else, including symlinks to directories).	893	recurse into (everything else, including symlinks to directories).
434		894
435	C<aio_scandir> is a composite request that creates of many sub requests_	895	C<aio_scandir> is a composite request that creates of many sub requests_
436	C<$maxreq> specifies the maximum number of outstanding aio requests that	896	C<$maxreq> specifies the maximum number of outstanding aio requests that
437	this function generates. If it is C<< <= 0 >>, then a suitable default	897	this function generates. If it is C<< <= 0 >>, then a suitable default
438	will be chosen (currently 6).	898	will be chosen (currently 4).
439		899
440	On error, the callback is called without arguments, otherwise it receives	900	On error, the callback is called without arguments, otherwise it receives
441	two array-refs with path-relative entry names.	901	two array-refs with path-relative entry names.
442		902
443	Example:	903	Example:
…		…
450		910
451	Implementation notes.	911	Implementation notes.
452		912
453	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	913	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
454		914
		915	If readdir returns file type information, then this is used directly to
		916	find directories.
		917
455	After reading the directory, the modification time, size etc. of the	918	Otherwise, after reading the directory, the modification time, size etc.
456	directory before and after the readdir is checked, and if they match (and	919	of the directory before and after the readdir is checked, and if they
457	isn't the current time), the link count will be used to decide how many	920	match (and isn't the current time), the link count will be used to decide
458	entries are directories (if >= 2). Otherwise, no knowledge of the number	921	how many entries are directories (if >= 2). Otherwise, no knowledge of the
459	of subdirectories will be assumed.	922	number of subdirectories will be assumed.
460		923
461	Then entries will be sorted into likely directories (everything without	924	Then entries will be sorted into likely directories a non-initial dot
462	a non-initial dot currently) and likely non-directories (everything	925	currently) and likely non-directories (see C<aio_readdirx>). Then every
463	else). Then every entry plus an appended C</.> will be C<stat>'ed,	926	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
464	likely directories first. If that succeeds, it assumes that the entry	927	in order of their inode numbers. If that succeeds, it assumes that the
465	is a directory or a symlink to directory (which will be checked	928	entry is a directory or a symlink to directory (which will be checked
466	seperately). This is often faster than stat'ing the entry itself because	929	seperately). This is often faster than stat'ing the entry itself because
467	filesystems might detect the type of the entry without reading the inode	930	filesystems might detect the type of the entry without reading the inode
468	data (e.g. ext2fs filetype feature).	931	data (e.g. ext2fs filetype feature), even on systems that cannot return
		932	the filetype information on readdir.
469		933
470	If the known number of directories (link count - 2) has been reached, the	934	If the known number of directories (link count - 2) has been reached, the
471	rest of the entries is assumed to be non-directories.	935	rest of the entries is assumed to be non-directories.
472		936
473	This only works with certainty on POSIX (= UNIX) filesystems, which	937	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
477	as those tend to return 0 or 1 as link counts, which disables the	941	as those tend to return 0 or 1 as link counts, which disables the
478	directory counting heuristic.	942	directory counting heuristic.
479		943
480	=cut	944	=cut
481		945
482	sub aio_scandir($$$) {	946	sub aio_scandir($$;$) {
483	my ($path, $maxreq, $cb) = @_;	947	my ($path, $maxreq, $cb) = @_;
484		948
		949	my $pri = aioreq_pri;
		950
485	my $grp = aio_group $cb;	951	my $grp = aio_group $cb;
486		952
487	$maxreq = 6 if $maxreq <= 0;	953	$maxreq = 4 if $maxreq <= 0;
488		954
489	# stat once	955	# stat once
		956	aioreq_pri $pri;
490	add $grp aio_stat $path, sub {	957	add $grp aio_stat $path, sub {
491	return $grp->result () if $_[0];	958	return $grp->result () if $_[0];
492	my $now = time;	959	my $now = time;
493	my $hash1 = join ":", (stat _)[0,1,3,7,9];	960	my $hash1 = join ":", (stat _)[0,1,3,7,9];
494		961
495	# read the directory entries	962	# read the directory entries
		963	aioreq_pri $pri;
496	add $grp aio_readdir $path, sub {	964	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
497	my $entries = shift	965	my $entries = shift
498	or return $grp->result ();	966	or return $grp->result ();
499		967
500	# stat the dir another time	968	# stat the dir another time
		969	aioreq_pri $pri;
501	add $grp aio_stat $path, sub {	970	add $grp aio_stat $path, sub {
502	my $hash2 = join ":", (stat _)[0,1,3,7,9];	971	my $hash2 = join ":", (stat _)[0,1,3,7,9];
503		972
504	my $ndirs;	973	my $ndirs;
505		974
506	# take the slow route if anything looks fishy	975	# take the slow route if anything looks fishy
507	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	976	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
508	$ndirs = -1;	977	$ndirs = -1;
509	} else {	978	} else {
510	# if nlink == 2, we are finished	979	# if nlink == 2, we are finished
511	# on non-posix-fs's, we rely on nlink < 2	980	# for non-posix-fs's, we rely on nlink < 2
512	$ndirs = (stat _)[3] - 2	981	$ndirs = (stat _)[3] - 2
513	or return $grp->result ([], $entries);	982	or return $grp->result ([], $entries);
514	}	983	}
515		984
516	# sort into likely dirs and likely nondirs
517	# dirs == files without ".", short entries first
518	$entries = [map $_->[0],
519	sort { $b->[1] cmp $a->[1] }
520	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
521	@$entries];
522
523	my (@dirs, @nondirs);	985	my (@dirs, @nondirs);
524		986
525	my $statgrp = add $grp aio_group sub {	987	my $statgrp = add $grp aio_group sub {
526	$grp->result (\@dirs, \@nondirs);	988	$grp->result (\@dirs, \@nondirs);
527	};	989	};
528		990
529	limit $statgrp $maxreq;	991	limit $statgrp $maxreq;
530	feed $statgrp sub {	992	feed $statgrp sub {
531	return unless @$entries;	993	return unless @$entries;
532	my $entry = pop @$entries;	994	my $entry = shift @$entries;
533		995
		996	aioreq_pri $pri;
534	add $statgrp aio_stat "$path/$entry/.", sub {	997	add $statgrp aio_stat "$path/$entry/.", sub {
535	if ($_[0] < 0) {	998	if ($_[0] < 0) {
536	push @nondirs, $entry;	999	push @nondirs, $entry;
537	} else {	1000	} else {
538	# need to check for real directory	1001	# need to check for real directory
		1002	aioreq_pri $pri;
539	add $statgrp aio_lstat "$path/$entry", sub {	1003	add $statgrp aio_lstat "$path/$entry", sub {
540	if (-d _) {	1004	if (-d _) {
541	push @dirs, $entry;	1005	push @dirs, $entry;
542		1006
543	unless (--$ndirs) {	1007	unless (--$ndirs) {
…		…
556	};	1020	};
557		1021
558	$grp	1022	$grp
559	}	1023	}
560		1024
		1025	=item aio_rmtree $path, $callback->($status)
		1026
		1027	Delete a directory tree starting (and including) C<$path>, return the
		1028	status of the final C<rmdir> only. This is a composite request that
		1029	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		1030	everything else.
		1031
		1032	=cut
		1033
		1034	sub aio_rmtree;
		1035	sub aio_rmtree($;$) {
		1036	my ($path, $cb) = @_;
		1037
		1038	my $pri = aioreq_pri;
		1039	my $grp = aio_group $cb;
		1040
		1041	aioreq_pri $pri;
		1042	add $grp aio_scandir $path, 0, sub {
		1043	my ($dirs, $nondirs) = @_;
		1044
		1045	my $dirgrp = aio_group sub {
		1046	add $grp aio_rmdir $path, sub {
		1047	$grp->result ($_[0]);
		1048	};
		1049	};
		1050
		1051	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1052	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1053
		1054	add $grp $dirgrp;
		1055	};
		1056
		1057	$grp
		1058	}
		1059
		1060	=item aio_sync $callback->($status)
		1061
		1062	Asynchronously call sync and call the callback when finished.
		1063
561	=item aio_fsync $fh, $callback->($status)	1064	=item aio_fsync $fh, $callback->($status)
562		1065
563	Asynchronously call fsync on the given filehandle and call the callback	1066	Asynchronously call fsync on the given filehandle and call the callback
564	with the fsync result code.	1067	with the fsync result code.
565		1068
…		…
568	Asynchronously call fdatasync on the given filehandle and call the	1071	Asynchronously call fdatasync on the given filehandle and call the
569	callback with the fdatasync result code.	1072	callback with the fdatasync result code.
570		1073
571	If this call isn't available because your OS lacks it or it couldn't be	1074	If this call isn't available because your OS lacks it or it couldn't be
572	detected, it will be emulated by calling C<fsync> instead.	1075	detected, it will be emulated by calling C<fsync> instead.
		1076
		1077	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1078
		1079	Sync the data portion of the file specified by C<$offset> and C<$length>
		1080	to disk (but NOT the metadata), by calling the Linux-specific
		1081	sync_file_range call. If sync_file_range is not available or it returns
		1082	ENOSYS, then fdatasync or fsync is being substituted.
		1083
		1084	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1085	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1086	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1087	manpage for details.
		1088
		1089	=item aio_pathsync $path, $callback->($status)
		1090
		1091	This request tries to open, fsync and close the given path. This is a
		1092	composite request intended to sync directories after directory operations
		1093	(E.g. rename). This might not work on all operating systems or have any
		1094	specific effect, but usually it makes sure that directory changes get
		1095	written to disc. It works for anything that can be opened for read-only,
		1096	not just directories.
		1097
		1098	Future versions of this function might fall back to other methods when
		1099	C<fsync> on the directory fails (such as calling C<sync>).
		1100
		1101	Passes C<0> when everything went ok, and C<-1> on error.
		1102
		1103	=cut
		1104
		1105	sub aio_pathsync($;$) {
		1106	my ($path, $cb) = @_;
		1107
		1108	my $pri = aioreq_pri;
		1109	my $grp = aio_group $cb;
		1110
		1111	aioreq_pri $pri;
		1112	add $grp aio_open $path, O_RDONLY, 0, sub {
		1113	my ($fh) = @_;
		1114	if ($fh) {
		1115	aioreq_pri $pri;
		1116	add $grp aio_fsync $fh, sub {
		1117	$grp->result ($_[0]);
		1118
		1119	aioreq_pri $pri;
		1120	add $grp aio_close $fh;
		1121	};
		1122	} else {
		1123	$grp->result (-1);
		1124	}
		1125	};
		1126
		1127	$grp
		1128	}
		1129
		1130	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1131
		1132	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1133	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1134	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1135	scalar must only be modified in-place while an aio operation is pending on
		1136	it).
		1137
		1138	It calls the C<msync> function of your OS, if available, with the memory
		1139	area starting at C<$offset> in the string and ending C<$length> bytes
		1140	later. If C<$length> is negative, counts from the end, and if C<$length>
		1141	is C<undef>, then it goes till the end of the string. The flags can be
		1142	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1143	C<IO::AIO::MS_SYNC>.
		1144
		1145	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1146
		1147	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1148	scalars.
		1149
		1150	It touches (reads or writes) all memory pages in the specified
		1151	range inside the scalar. All caveats and parameters are the same
		1152	as for C<aio_msync>, above, except for flags, which must be either
		1153	C<0> (which reads all pages and ensures they are instantiated) or
		1154	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1155	writing an octet from it, which dirties the page).
		1156
		1157	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1158
		1159	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1160	scalars.
		1161
		1162	It reads in all the pages of the underlying storage into memory (if any)
		1163	and locks them, so they are not getting swapped/paged out or removed.
		1164
		1165	If C<$length> is undefined, then the scalar will be locked till the end.
		1166
		1167	On systems that do not implement C<mlock>, this function returns C<-1>
		1168	and sets errno to C<ENOSYS>.
		1169
		1170	Note that the corresponding C<munlock> is synchronous and is
		1171	documented under L<MISCELLANEOUS FUNCTIONS>.
		1172
		1173	Example: open a file, mmap and mlock it - both will be undone when
		1174	C<$data> gets destroyed.
		1175
		1176	open my $fh, "<", $path or die "$path: $!";
		1177	my $data;
		1178	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1179	aio_mlock $data; # mlock in background
		1180
		1181	=item aio_mlockall $flags, $callback->($status)
		1182
		1183	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1184	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1185
		1186	On systems that do not implement C<mlockall>, this function returns C<-1>
		1187	and sets errno to C<ENOSYS>.
		1188
		1189	Note that the corresponding C<munlockall> is synchronous and is
		1190	documented under L<MISCELLANEOUS FUNCTIONS>.
		1191
		1192	Example: asynchronously lock all current and future pages into memory.
		1193
		1194	aio_mlockall IO::AIO::MCL_FUTURE;
573		1195
574	=item aio_group $callback->(...)	1196	=item aio_group $callback->(...)
575		1197
576	This is a very special aio request: Instead of doing something, it is a	1198	This is a very special aio request: Instead of doing something, it is a
577	container for other aio requests, which is useful if you want to bundle	1199	container for other aio requests, which is useful if you want to bundle
…		…
627	=item cancel $req	1249	=item cancel $req
628		1250
629	Cancels the request, if possible. Has the effect of skipping execution	1251	Cancels the request, if possible. Has the effect of skipping execution
630	when entering the B<execute> state and skipping calling the callback when	1252	when entering the B<execute> state and skipping calling the callback when
631	entering the the B<result> state, but will leave the request otherwise	1253	entering the the B<result> state, but will leave the request otherwise
632	untouched. That means that requests that currently execute will not be	1254	untouched (with the exception of readdir). That means that requests that
633	stopped and resources held by the request will not be freed prematurely.	1255	currently execute will not be stopped and resources held by the request
		1256	will not be freed prematurely.
634		1257
635	=item cb $req $callback->(...)	1258	=item cb $req $callback->(...)
636		1259
637	Replace (or simply set) the callback registered to the request.	1260	Replace (or simply set) the callback registered to the request.
638		1261
…		…
689	Their lifetime, simplified, looks like this: when they are empty, they	1312	Their lifetime, simplified, looks like this: when they are empty, they
690	will finish very quickly. If they contain only requests that are in the	1313	will finish very quickly. If they contain only requests that are in the
691	C<done> state, they will also finish. Otherwise they will continue to	1314	C<done> state, they will also finish. Otherwise they will continue to
692	exist.	1315	exist.
693		1316
694	That means after creating a group you have some time to add requests. And	1317	That means after creating a group you have some time to add requests
695	in the callbacks of those requests, you can add further requests to the	1318	(precisely before the callback has been invoked, which is only done within
696	group. And only when all those requests have finished will the the group	1319	the C<poll_cb>). And in the callbacks of those requests, you can add
697	itself finish.	1320	further requests to the group. And only when all those requests have
		1321	finished will the the group itself finish.
698		1322
699	=over 4	1323	=over 4
700		1324
701	=item add $grp ...	1325	=item add $grp ...
702		1326
…		…
711	=item $grp->cancel_subs	1335	=item $grp->cancel_subs
712		1336
713	Cancel all subrequests and clears any feeder, but not the group request	1337	Cancel all subrequests and clears any feeder, but not the group request
714	itself. Useful when you queued a lot of events but got a result early.	1338	itself. Useful when you queued a lot of events but got a result early.
715		1339
		1340	The group request will finish normally (you cannot add requests to the
		1341	group).
		1342
716	=item $grp->result (...)	1343	=item $grp->result (...)
717		1344
718	Set the result value(s) that will be passed to the group callback when all	1345	Set the result value(s) that will be passed to the group callback when all
719	subrequests have finished. By default, no argument will be passed.	1346	subrequests have finished and set the groups errno to the current value
		1347	of errno (just like calling C<errno> without an error number). By default,
		1348	no argument will be passed and errno is zero.
		1349
		1350	=item $grp->errno ([$errno])
		1351
		1352	Sets the group errno value to C<$errno>, or the current value of errno
		1353	when the argument is missing.
		1354
		1355	Every aio request has an associated errno value that is restored when
		1356	the callback is invoked. This method lets you change this value from its
		1357	default (0).
		1358
		1359	Calling C<result> will also set errno, so make sure you either set C<$!>
		1360	before the call to C<result>, or call c<errno> after it.
720		1361
721	=item feed $grp $callback->($grp)	1362	=item feed $grp $callback->($grp)
722		1363
723	Sets a feeder/generator on this group: every group can have an attached	1364	Sets a feeder/generator on this group: every group can have an attached
724	generator that generates requests if idle. The idea behind this is that,	1365	generator that generates requests if idle. The idea behind this is that,
725	although you could just queue as many requests as you want in a group,	1366	although you could just queue as many requests as you want in a group,
726	this might starve other requests for a potentially long time. For	1367	this might starve other requests for a potentially long time. For example,
727	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1368	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
728	requests, delaying any later requests for a long time.	1369	delaying any later requests for a long time.
729		1370
730	To avoid this, and allow incremental generation of requests, you can	1371	To avoid this, and allow incremental generation of requests, you can
731	instead a group and set a feeder on it that generates those requests. The	1372	instead a group and set a feeder on it that generates those requests. The
732	feed callback will be called whenever there are few enough (see C<limit>,	1373	feed callback will be called whenever there are few enough (see C<limit>,
733	below) requests active in the group itself and is expected to queue more	1374	below) requests active in the group itself and is expected to queue more
…		…
737	not impose any limits).	1378	not impose any limits).
738		1379
739	If the feed does not queue more requests when called, it will be	1380	If the feed does not queue more requests when called, it will be
740	automatically removed from the group.	1381	automatically removed from the group.
741		1382
742	If the feed limit is C<0>, it will be set to C<2> automatically.	1383	If the feed limit is C<0> when this method is called, it will be set to
		1384	C<2> automatically.
743		1385
744	Example:	1386	Example:
745		1387
746	# stat all files in @files, but only ever use four aio requests concurrently:	1388	# stat all files in @files, but only ever use four aio requests concurrently:
747		1389
…		…
759	Sets the feeder limit for the group: The feeder will be called whenever	1401	Sets the feeder limit for the group: The feeder will be called whenever
760	the group contains less than this many requests.	1402	the group contains less than this many requests.
761		1403
762	Setting the limit to C<0> will pause the feeding process.	1404	Setting the limit to C<0> will pause the feeding process.
763		1405
		1406	The default value for the limit is C<0>, but note that setting a feeder
		1407	automatically bumps it up to C<2>.
		1408
764	=back	1409	=back
765		1410
766	=head2 SUPPORT FUNCTIONS	1411	=head2 SUPPORT FUNCTIONS
767		1412
		1413	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1414
768	=over 4	1415	=over 4
769		1416
770	=item $fileno = IO::AIO::poll_fileno	1417	=item $fileno = IO::AIO::poll_fileno
771		1418
772	Return the I<request result pipe file descriptor>. This filehandle must be	1419	Return the I<request result pipe file descriptor>. This filehandle must be
773	polled for reading by some mechanism outside this module (e.g. Event or	1420	polled for reading by some mechanism outside this module (e.g. EV, Glib,
774	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1421	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
775	to call C<poll_cb> to check the results.	1422	you have to call C<poll_cb> to check the results.
776		1423
777	See C<poll_cb> for an example.	1424	See C<poll_cb> for an example.
778		1425
779	=item IO::AIO::poll_cb	1426	=item IO::AIO::poll_cb
780		1427
781	Process all outstanding events on the result pipe. You have to call this	1428	Process some outstanding events on the result pipe. You have to call
782	regularly. Returns the number of events processed. Returns immediately	1429	this regularly. Returns C<0> if all events could be processed (or there
783	when no events are outstanding.	1430	were no events to process), or C<-1> if it returned earlier for whatever
		1431	reason. Returns immediately when no events are outstanding. The amount of
		1432	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1433	C<IO::AIO::max_poll_time>.
		1434
		1435	If not all requests were processed for whatever reason, the filehandle
		1436	will still be ready when C<poll_cb> returns, so normally you don't have to
		1437	do anything special to have it called later.
		1438
		1439	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1440	ready, it can be beneficial to call this function from loops which submit
		1441	a lot of requests, to make sure the results get processed when they become
		1442	available and not just when the loop is finished and the event loop takes
		1443	over again. This function returns very fast when there are no outstanding
		1444	requests.
784		1445
785	Example: Install an Event watcher that automatically calls	1446	Example: Install an Event watcher that automatically calls
786	IO::AIO::poll_cb with high priority:	1447	IO::AIO::poll_cb with high priority (more examples can be found in the
		1448	SYNOPSIS section, at the top of this document):
787		1449
788	Event->io (fd => IO::AIO::poll_fileno,	1450	Event->io (fd => IO::AIO::poll_fileno,
789	poll => 'r', async => 1,	1451	poll => 'r', async => 1,
790	cb => \&IO::AIO::poll_cb);	1452	cb => \&IO::AIO::poll_cb);
791		1453
792	=item IO::AIO::poll_wait	1454	=item IO::AIO::poll_wait
793		1455
		1456	If there are any outstanding requests and none of them in the result
794	Wait till the result filehandle becomes ready for reading (simply does a	1457	phase, wait till the result filehandle becomes ready for reading (simply
795	C<select> on the filehandle. This is useful if you want to synchronously wait	1458	does a C<select> on the filehandle. This is useful if you want to
796	for some requests to finish).	1459	synchronously wait for some requests to finish).
797		1460
798	See C<nreqs> for an example.	1461	See C<nreqs> for an example.
799		1462
		1463	=item IO::AIO::poll
		1464
		1465	Waits until some requests have been handled.
		1466
		1467	Returns the number of requests processed, but is otherwise strictly
		1468	equivalent to:
		1469
		1470	IO::AIO::poll_wait, IO::AIO::poll_cb
		1471
800	=item IO::AIO::nreqs	1472	=item IO::AIO::flush
801		1473
802	Returns the number of requests currently outstanding (i.e. for which their	1474	Wait till all outstanding AIO requests have been handled.
803	callback has not been invoked yet).
804		1475
805	Example: wait till there are no outstanding requests anymore:	1476	Strictly equivalent to:
806		1477
807	IO::AIO::poll_wait, IO::AIO::poll_cb	1478	IO::AIO::poll_wait, IO::AIO::poll_cb
808	while IO::AIO::nreqs;	1479	while IO::AIO::nreqs;
809		1480
810	=item IO::AIO::flush	1481	=item IO::AIO::max_poll_reqs $nreqs
811		1482
812	Wait till all outstanding AIO requests have been handled.	1483	=item IO::AIO::max_poll_time $seconds
813		1484
814	Strictly equivalent to:	1485	These set the maximum number of requests (default C<0>, meaning infinity)
		1486	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1487	the maximum amount of time (default C<0>, meaning infinity) spent in
		1488	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1489	of time C<poll_cb> is allowed to use).
815		1490
816	IO::AIO::poll_wait, IO::AIO::poll_cb	1491	Setting C<max_poll_time> to a non-zero value creates an overhead of one
817	while IO::AIO::nreqs;	1492	syscall per request processed, which is not normally a problem unless your
		1493	callbacks are really really fast or your OS is really really slow (I am
		1494	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
818		1495
819	=item IO::AIO::poll	1496	Setting these is useful if you want to ensure some level of
		1497	interactiveness when perl is not fast enough to process all requests in
		1498	time.
820		1499
821	Waits until some requests have been handled.	1500	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
822		1501
823	Strictly equivalent to:	1502	Example: Install an Event watcher that automatically calls
		1503	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1504	program get the CPU sometimes even under high AIO load.
824		1505
825	IO::AIO::poll_wait, IO::AIO::poll_cb	1506	# try not to spend much more than 0.1s in poll_cb
826	if IO::AIO::nreqs;	1507	IO::AIO::max_poll_time 0.1;
		1508
		1509	# use a low priority so other tasks have priority
		1510	Event->io (fd => IO::AIO::poll_fileno,
		1511	poll => 'r', nice => 1,
		1512	cb => &IO::AIO::poll_cb);
		1513
		1514	=back
		1515
		1516	=head3 CONTROLLING THE NUMBER OF THREADS
		1517
		1518	=over
827		1519
828	=item IO::AIO::min_parallel $nthreads	1520	=item IO::AIO::min_parallel $nthreads
829		1521
830	Set the minimum number of AIO threads to C<$nthreads>. The current	1522	Set the minimum number of AIO threads to C<$nthreads>. The current
831	default is C<8>, which means eight asynchronous operations can execute	1523	default is C<8>, which means eight asynchronous operations can execute
832	concurrently at any one time (the number of outstanding requests,	1524	concurrently at any one time (the number of outstanding requests,
833	however, is unlimited).	1525	however, is unlimited).
834		1526
835	IO::AIO starts threads only on demand, when an AIO request is queued and	1527	IO::AIO starts threads only on demand, when an AIO request is queued and
836	no free thread exists.	1528	no free thread exists. Please note that queueing up a hundred requests can
		1529	create demand for a hundred threads, even if it turns out that everything
		1530	is in the cache and could have been processed faster by a single thread.
837		1531
838	It is recommended to keep the number of threads relatively low, as some	1532	It is recommended to keep the number of threads relatively low, as some
839	Linux kernel versions will scale negatively with the number of threads	1533	Linux kernel versions will scale negatively with the number of threads
840	(higher parallelity => MUCH higher latency). With current Linux 2.6	1534	(higher parallelity => MUCH higher latency). With current Linux 2.6
841	versions, 4-32 threads should be fine.	1535	versions, 4-32 threads should be fine.
…		…
855	This module automatically runs C<max_parallel 0> at program end, to ensure	1549	This module automatically runs C<max_parallel 0> at program end, to ensure
856	that all threads are killed and that there are no outstanding requests.	1550	that all threads are killed and that there are no outstanding requests.
857		1551
858	Under normal circumstances you don't need to call this function.	1552	Under normal circumstances you don't need to call this function.
859		1553
		1554	=item IO::AIO::max_idle $nthreads
		1555
		1556	Limit the number of threads (default: 4) that are allowed to idle
		1557	(i.e., threads that did not get a request to process within the idle
		1558	timeout (default: 10 seconds). That means if a thread becomes idle while
		1559	C<$nthreads> other threads are also idle, it will free its resources and
		1560	exit.
		1561
		1562	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1563	to allow for extremely high load situations, but want to free resources
		1564	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1565
		1566	The default is probably ok in most situations, especially if thread
		1567	creation is fast. If thread creation is very slow on your system you might
		1568	want to use larger values.
		1569
		1570	=item IO::AIO::idle_timeout $seconds
		1571
		1572	Sets the minimum idle timeout (default 10) after which worker threads are
		1573	allowed to exit. SEe C<IO::AIO::max_idle>.
		1574
860	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1575	=item IO::AIO::max_outstanding $maxreqs
861		1576
862	[REMOVED]
863
864	Pre-2.x versions used max_outstanding for a crude request queue length limit.
865
866	In 2.x+ you are advised to use a group and a feeder to limit
867	concurrency. The max_outstanding feature ran very unstable (endless
868	recursions causing segfaults, bad interaction with groups etc.) and was
869	removed.
870
871	I am deeply sorry, but I am still on the hunt for a good limiting interface.
872
873	Original description was as follows:
874
875	Sets the maximum number of outstanding requests to C<$nreqs>. If you try	1577	Sets the maximum number of outstanding requests to C<$nreqs>. If
876	to queue up more than this number of requests, the caller will block until	1578	you do queue up more than this number of requests, the next call to
877	some requests have been handled.	1579	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1580	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1581	longer exceeded.
		1582
		1583	In other words, this setting does not enforce a queue limit, but can be
		1584	used to make poll functions block if the limit is exceeded.
		1585
		1586	This is a very bad function to use in interactive programs because it
		1587	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1588	use an C<aio_group> together with a feed callback.
		1589
		1590	It's main use is in scripts without an event loop - when you want to stat
		1591	a lot of files, you can write somehting like this:
		1592
		1593	IO::AIO::max_outstanding 32;
		1594
		1595	for my $path (...) {
		1596	aio_stat $path , ...;
		1597	IO::AIO::poll_cb;
		1598	}
		1599
		1600	IO::AIO::flush;
		1601
		1602	The call to C<poll_cb> inside the loop will normally return instantly, but
		1603	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1604	some requests have been handled. This keeps the loop from pushing a large
		1605	number of C<aio_stat> requests onto the queue.
		1606
		1607	The default value for C<max_outstanding> is very large, so there is no
		1608	practical limit on the number of outstanding requests.
878		1609
879	=back	1610	=back
880		1611
		1612	=head3 STATISTICAL INFORMATION
		1613
		1614	=over
		1615
		1616	=item IO::AIO::nreqs
		1617
		1618	Returns the number of requests currently in the ready, execute or pending
		1619	states (i.e. for which their callback has not been invoked yet).
		1620
		1621	Example: wait till there are no outstanding requests anymore:
		1622
		1623	IO::AIO::poll_wait, IO::AIO::poll_cb
		1624	while IO::AIO::nreqs;
		1625
		1626	=item IO::AIO::nready
		1627
		1628	Returns the number of requests currently in the ready state (not yet
		1629	executed).
		1630
		1631	=item IO::AIO::npending
		1632
		1633	Returns the number of requests currently in the pending state (executed,
		1634	but not yet processed by poll_cb).
		1635
		1636	=back
		1637
		1638	=head3 MISCELLANEOUS FUNCTIONS
		1639
		1640	IO::AIO implements some functions that might be useful, but are not
		1641	asynchronous.
		1642
		1643	=over 4
		1644
		1645	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1646
		1647	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1648	but is blocking (this makes most sense if you know the input data is
		1649	likely cached already and the output filehandle is set to non-blocking
		1650	operations).
		1651
		1652	Returns the number of bytes copied, or C<-1> on error.
		1653
		1654	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1655
		1656	Simply calls the C<posix_fadvise> function (see its
		1657	manpage for details). The following advice constants are
		1658	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1659	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1660	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1661
		1662	On systems that do not implement C<posix_fadvise>, this function returns
		1663	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1664
		1665	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1666
		1667	Simply calls the C<posix_madvise> function (see its
		1668	manpage for details). The following advice constants are
		1669	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1670	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1671
		1672	On systems that do not implement C<posix_madvise>, this function returns
		1673	ENOSYS, otherwise the return value of C<posix_madvise>.
		1674
		1675	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1676
		1677	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1678	$scalar (see its manpage for details). The following protect
		1679	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1680	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1681
		1682	On systems that do not implement C<mprotect>, this function returns
		1683	ENOSYS, otherwise the return value of C<mprotect>.
		1684
		1685	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1686
		1687	Memory-maps a file (or anonymous memory range) and attaches it to the
		1688	given C<$scalar>, which will act like a string scalar.
		1689
		1690	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1691	change the string length, and most read-only operations such as copying it
		1692	or searching it with regexes and so on.
		1693
		1694	Anything else is unsafe and will, at best, result in memory leaks.
		1695
		1696	The memory map associated with the C<$scalar> is automatically removed
		1697	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1698	C<IO::AIO::munmap> functions are called.
		1699
		1700	This calls the C<mmap>(2) function internally. See your system's manual
		1701	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1702
		1703	The C<$length> must be larger than zero and smaller than the actual
		1704	filesize.
		1705
		1706	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1707	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1708
		1709	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1710	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1711	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1712	(which is set to C<MAP_ANON> if your system only provides this
		1713	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1714	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1715	C<IO::AIO::MAP_NONBLOCK>
		1716
		1717	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1718
		1719	C<$offset> is the offset from the start of the file - it generally must be
		1720	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1721
		1722	Example:
		1723
		1724	use Digest::MD5;
		1725	use IO::AIO;
		1726
		1727	open my $fh, "<verybigfile"
		1728	or die "$!";
		1729
		1730	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1731	or die "verybigfile: $!";
		1732
		1733	my $fast_md5 = md5 $data;
		1734
		1735	=item IO::AIO::munmap $scalar
		1736
		1737	Removes a previous mmap and undefines the C<$scalar>.
		1738
		1739	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1740
		1741	Calls the C<munlock> function, undoing the effects of a previous
		1742	C<aio_mlock> call (see its description for details).
		1743
		1744	=item IO::AIO::munlockall
		1745
		1746	Calls the C<munlockall> function.
		1747
		1748	On systems that do not implement C<munlockall>, this function returns
		1749	ENOSYS, otherwise the return value of C<munlockall>.
		1750
		1751	=back
		1752
881	=cut	1753	=cut
882		1754
883	# support function to convert a fd into a perl filehandle
884	sub _fd2fh {
885	return undef if $_[0] < 0;
886
887	# try to generate nice filehandles
888	my $sym = "IO::AIO::fd#$_[0]";
889	local *$sym;
890
891	open *$sym, "+<&=$_[0]" # usually works under any unix
892	or open *$sym, "<&=$_[0]" # cygwin needs this
893	or open *$sym, ">&=$_[0]" # or this
894	or return undef;
895
896	*$sym
897	}
898
899	min_parallel 8;	1755	min_parallel 8;
900		1756
901	END {	1757	END { flush }
902	max_parallel 0;
903	}
904		1758
905	1;	1759	1;
906		1760
		1761	=head1 EVENT LOOP INTEGRATION
		1762
		1763	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1764	automatically into many event loops:
		1765
		1766	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1767	use AnyEvent::AIO;
		1768
		1769	You can also integrate IO::AIO manually into many event loops, here are
		1770	some examples of how to do this:
		1771
		1772	# EV integration
		1773	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1774
		1775	# Event integration
		1776	Event->io (fd => IO::AIO::poll_fileno,
		1777	poll => 'r',
		1778	cb => \&IO::AIO::poll_cb);
		1779
		1780	# Glib/Gtk2 integration
		1781	add_watch Glib::IO IO::AIO::poll_fileno,
		1782	in => sub { IO::AIO::poll_cb; 1 };
		1783
		1784	# Tk integration
		1785	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1786	readable => \&IO::AIO::poll_cb);
		1787
		1788	# Danga::Socket integration
		1789	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1790	\&IO::AIO::poll_cb);
		1791
907	=head2 FORK BEHAVIOUR	1792	=head2 FORK BEHAVIOUR
908		1793
909	This module should do "the right thing" when the process using it forks:	1794	Usage of pthreads in a program changes the semantics of fork
		1795	considerably. Specifically, only async-safe functions can be called after
		1796	fork. Perl doesn't know about this, so in general, you cannot call fork
		1797	with defined behaviour in perl. IO::AIO uses pthreads, so this applies,
		1798	but many other extensions and (for inexplicable reasons) perl itself often
		1799	is linked against pthreads, so this limitation applies.
910		1800
911	Before the fork, IO::AIO enters a quiescent state where no requests	1801	Some operating systems have extensions that allow safe use of fork, and
912	can be added in other threads and no results will be processed. After	1802	this module should do "the right thing" on those, and tries on others. At
913	the fork the parent simply leaves the quiescent state and continues	1803	the time of this writing (2011) only GNU/Linux supports these extensions
914	request/result processing, while the child frees the request/result queue	1804	to POSIX.
915	(so that the requests started before the fork will only be handled in the
916	parent). Threads will be started on demand until the limit set in the
917	parent process has been reached again.
918
919	In short: the parent will, after a short pause, continue as if fork had
920	not been called, while the child will act as if IO::AIO has not been used
921	yet.
922		1805
923	=head2 MEMORY USAGE	1806	=head2 MEMORY USAGE
924		1807
925	Per-request usage:	1808	Per-request usage:
926		1809
…		…
928	bytes of memory. In addition, stat requests need a stat buffer (possibly	1811	bytes of memory. In addition, stat requests need a stat buffer (possibly
929	a few hundred bytes), readdir requires a result buffer and so on. Perl	1812	a few hundred bytes), readdir requires a result buffer and so on. Perl
930	scalars and other data passed into aio requests will also be locked and	1813	scalars and other data passed into aio requests will also be locked and
931	will consume memory till the request has entered the done state.	1814	will consume memory till the request has entered the done state.
932		1815
933	This is now awfully much, so queuing lots of requests is not usually a	1816	This is not awfully much, so queuing lots of requests is not usually a
934	problem.	1817	problem.
935		1818
936	Per-thread usage:	1819	Per-thread usage:
937		1820
938	In the execution phase, some aio requests require more memory for	1821	In the execution phase, some aio requests require more memory for
…		…
943		1826
944	Known bugs will be fixed in the next release.	1827	Known bugs will be fixed in the next release.
945		1828
946	=head1 SEE ALSO	1829	=head1 SEE ALSO
947		1830
948	L<Coro::AIO>.	1831	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1832	more natural syntax.
949		1833
950	=head1 AUTHOR	1834	=head1 AUTHOR
951		1835
952	Marc Lehmann <schmorp@schmorp.de>	1836	Marc Lehmann <schmorp@schmorp.de>
953	http://home.schmorp.de/	1837	http://home.schmorp.de/

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