[ViewVC] Diff of: cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC vs.
Revision 1.173 by root, Thu Jan 7 20:25:57 2010 UTC

…		…
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", 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
		31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		32	use AnyEvent::AIO;
		33
30	# AnyEvent integration	34	# EV integration
31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	35	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
33		36
34	# Event integration	37	# Event integration
35	Event->io (fd => IO::AIO::poll_fileno,	38	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',	39	poll => 'r',
37	cb => \&IO::AIO::poll_cb);	40	cb => \&IO::AIO::poll_cb);
…		…
49	\&IO::AIO::poll_cb);	52	\&IO::AIO::poll_cb);
50		53
51	=head1 DESCRIPTION	54	=head1 DESCRIPTION
52		55
53	This module implements asynchronous I/O using whatever means your	56	This module implements asynchronous I/O using whatever means your
54	operating system supports.	57	operating system supports. It is implemented as an interface to C<libeio>
		58	(L<http://software.schmorp.de/pkg/libeio.html>).
		59
		60	Asynchronous means that operations that can normally block your program
		61	(e.g. reading from disk) will be done asynchronously: the operation
		62	will still block, but you can do something else in the meantime. This
		63	is extremely useful for programs that need to stay interactive even
		64	when doing heavy I/O (GUI programs, high performance network servers
		65	etc.), but can also be used to easily do operations in parallel that are
		66	normally done sequentially, e.g. stat'ing many files, which is much faster
		67	on a RAID volume or over NFS when you do a number of stat operations
		68	concurrently.
		69
		70	While most of this works on all types of file descriptors (for
		71	example sockets), using these functions on file descriptors that
		72	support nonblocking operation (again, sockets, pipes etc.) is
		73	very inefficient. Use an event loop for that (such as the L<EV>
		74	module): IO::AIO will naturally fit into such an event loop itself.
55		75
56	In this version, a number of threads are started that execute your	76	In this version, a number of threads are started that execute your
57	requests and signal their completion. You don't need thread support	77	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	78	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	79	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	80	functions available on many operating systems. However, they are often
61	not well-supported or restricted (Linux doesn't allow them on normal	81	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	82	files currently, for example), and they would only support aio_read and
63	aio_write, so the remaining functionality would have to be implemented	83	aio_write, so the remaining functionality would have to be implemented
64	using threads anyway.	84	using threads anyway.
65		85
66	Although the module will work with in the presence of other (Perl-)	86	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	87	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	88	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.	89	call C<poll_cb> (or other C<aio_> functions) recursively.
		90
		91	=head2 EXAMPLE
		92
		93	This is a simple example that uses the EV module and loads
		94	F</etc/passwd> asynchronously:
		95
		96	use Fcntl;
		97	use EV;
		98	use IO::AIO;
		99
		100	# register the IO::AIO callback with EV
		101	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		102
		103	# queue the request to open /etc/passwd
		104	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		105	my $fh = shift
		106	or die "error while opening: $!";
		107
		108	# stat'ing filehandles is generally non-blocking
		109	my $size = -s $fh;
		110
		111	# queue a request to read the file
		112	my $contents;
		113	aio_read $fh, 0, $size, $contents, 0, sub {
		114	$_[0] == $size
		115	or die "short read: $!";
		116
		117	close $fh;
		118
		119	# file contents now in $contents
		120	print $contents;
		121
		122	# exit event loop and program
		123	EV::unloop;
		124	};
		125	};
		126
		127	# possibly queue up other requests, or open GUI windows,
		128	# check for sockets etc. etc.
		129
		130	# process events as long as there are some:
		131	EV::loop;
70		132
71	=head1 REQUEST ANATOMY AND LIFETIME	133	=head1 REQUEST ANATOMY AND LIFETIME
72		134
73	Every C<aio_*> function creates a request. which is a C data structure not	135	Every C<aio_*> function creates a request. which is a C data structure not
74	directly visible to Perl.	136	directly visible to Perl.
…		…
116	Request has reached the end of its lifetime and holds no resources anymore	178	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	179	(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	180	aio request is severed and calling its methods will either do nothing or
119	result in a runtime error).	181	result in a runtime error).
120		182
		183	=back
		184
121	=cut	185	=cut
122		186
123	package IO::AIO;	187	package IO::AIO;
124		188
125	no warnings;	189	use Carp ();
126	use strict 'vars';	190
		191	use common::sense;
127		192
128	use base 'Exporter';	193	use base 'Exporter';
129		194
130	BEGIN {	195	BEGIN {
131	our $VERSION = '2.0';	196	our $VERSION = '3.5';
132		197
133	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	198	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	199	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	200	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
136	aio_group aio_nop);	201	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		202	aio_rename aio_link aio_move aio_copy aio_group
		203	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		204	aio_chmod aio_utime aio_truncate
		205	aio_msync aio_mtouch aio_statvfs);
		206
137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	207	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	208	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139	min_parallel max_parallel nreqs nready npending);	209	min_parallel max_parallel max_idle
		210	nreqs nready npending nthreads
		211	max_poll_time max_poll_reqs
		212	sendfile fadvise);
		213
		214	push @AIO_REQ, qw(aio_busy); # not exported
140		215
141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142		217
143	require XSLoader;	218	require XSLoader;
144	XSLoader::load ("IO::AIO", $VERSION);	219	XSLoader::load ("IO::AIO", $VERSION);
145	}	220	}
146		221
147	=head1 FUNCTIONS	222	=head1 FUNCTIONS
148		223
149	=head2 AIO FUNCTIONS	224	=head2 AIO REQUEST FUNCTIONS
150		225
151	All the C<aio_*> calls are more or less thin wrappers around the syscall	226	All the C<aio_*> calls are more or less thin wrappers around the syscall
152	with the same name (sans C<aio_>). The arguments are similar or identical,	227	with the same name (sans C<aio_>). The arguments are similar or identical,
153	and they all accept an additional (and optional) C<$callback> argument	228	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	229	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	230	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	231	perl, which usually delivers "false") as its sole argument after the given
157	syscall has been executed asynchronously.	232	syscall has been executed asynchronously.
158		233
159	All functions expecting a filehandle keep a copy of the filehandle	234	All functions expecting a filehandle keep a copy of the filehandle
160	internally until the request has finished.	235	internally until the request has finished.
161		236
162	All requests return objects of type L<IO::AIO::REQ> that allow further	237	All functions return request objects of type L<IO::AIO::REQ> that allow
163	manipulation of those requests while they are in-flight.	238	further manipulation of those requests while they are in-flight.
164		239
165	The pathnames you pass to these routines I<must> be absolute and	240	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	241	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	242	request is being executed, the current working directory could have
168	changed. Alternatively, you can make sure that you never change the	243	changed. Alternatively, you can make sure that you never change the
169	current working directory.	244	current working directory anywhere in the program and then use relative
		245	paths.
170		246
171	To encode pathnames to byte form, either make sure you either: a)	247	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	248	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	249	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	250	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)	251	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176	use something else.	252	use something else to ensure your scalar has the correct contents.
		253
		254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		255	handles correctly whether it is set or not.
177		256
178	=over 4	257	=over 4
179		258
180	=item $prev_pri = aioreq_pri [$pri]	259	=item $prev_pri = aioreq_pri [$pri]
181		260
…		…
201	aio_read $_[0], ..., sub {	280	aio_read $_[0], ..., sub {
202	...	281	...
203	};	282	};
204	};	283	};
205		284
		285
206	=item aioreq_nice $pri_adjust	286	=item aioreq_nice $pri_adjust
207		287
208	Similar to C<aioreq_pri>, but subtracts the given value from the current	288	Similar to C<aioreq_pri>, but subtracts the given value from the current
209	priority, so effects are cumulative.	289	priority, so the effect is cumulative.
		290
210		291
211	=item aio_open $pathname, $flags, $mode, $callback->($fh)	292	=item aio_open $pathname, $flags, $mode, $callback->($fh)
212		293
213	Asynchronously open or create a file and call the callback with a newly	294	Asynchronously open or create a file and call the callback with a newly
214	created filehandle for the file.	295	created filehandle for the file.
…		…
220	list. They are the same as used by C<sysopen>.	301	list. They are the same as used by C<sysopen>.
221		302
222	Likewise, C<$mode> specifies the mode of the newly created file, if it	303	Likewise, C<$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>,	304	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,	305	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).	306	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		307	by the umask in effect then the request is being executed, so better never
		308	change the umask.
226		309
227	Example:	310	Example:
228		311
229	aio_open "/etc/passwd", O_RDONLY, 0, sub {	312	aio_open "/etc/passwd", O_RDONLY, 0, sub {
230	if ($_[0]) {	313	if ($_[0]) {
…		…
233	} else {	316	} else {
234	die "open failed: $!\n";	317	die "open failed: $!\n";
235	}	318	}
236	};	319	};
237		320
		321
238	=item aio_close $fh, $callback->($status)	322	=item aio_close $fh, $callback->($status)
239		323
240	Asynchronously close a file and call the callback with the result	324	Asynchronously close a file and call the callback with the result
241	code. I<WARNING:> although accepted, you should not pass in a perl	325	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		326
246	This is supposed to be a bug in the API, so that might change. It's	327	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
247	therefore best to avoid this function.	328	closing the file descriptor associated with the filehandle itself.
		329
		330	Therefore, C<aio_close> will not close the filehandle - instead it will
		331	use dup2 to overwrite the file descriptor with the write-end of a pipe
		332	(the pipe fd will be created on demand and will be cached).
		333
		334	Or in other words: the file descriptor will be closed, but it will not be
		335	free for reuse until the perl filehandle is closed.
		336
		337	=cut
248		338
249	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250		340
251	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252		342
253	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	343	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	344	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
255	callback without the actual number of bytes read (or -1 on error, just	345	and calls the callback without the actual number of bytes read (or -1 on
256	like the syscall).	346	error, just like the syscall).
		347
		348	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		349	offset plus the actual number of bytes read.
		350
		351	If C<$offset> is undefined, then the current file descriptor offset will
		352	be used (and updated), otherwise the file descriptor offset will not be
		353	changed by these calls.
		354
		355	If C<$length> is undefined in C<aio_write>, use the remaining length of
		356	C<$data>.
		357
		358	If C<$dataoffset> is less than zero, it will be counted from the end of
		359	C<$data>.
257		360
258	The C<$data> scalar I<MUST NOT> be modified in any way while the request	361	The C<$data> scalar I<MUST NOT> be modified in any way while the request
259	is outstanding. Modifying it can result in segfaults or WW3 (if the	362	is outstanding. Modifying it can result in segfaults or World War III (if
260	necessary/optional hardware is installed).	363	the necessary/optional hardware is installed).
261		364
262	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	365	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263	offset C<0> within the scalar:	366	offset C<0> within the scalar:
264		367
265	aio_read $fh, 7, 15, $buffer, 0, sub {	368	aio_read $fh, 7, 15, $buffer, 0, sub {
266	$_[0] > 0 or die "read error: $!";	369	$_[0] > 0 or die "read error: $!";
267	print "read $_[0] bytes: <$buffer>\n";	370	print "read $_[0] bytes: <$buffer>\n";
268	};	371	};
269		372
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		373
345	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	374	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
346		375
347	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	376	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	377	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
352		381
353	This call tries to make use of a native C<sendfile> syscall to provide	382	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	383	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.	384	socket, and C<$in_fh> should refer to mmap'able file.
356		385
357	If the native sendfile call fails or is not implemented, it will be	386	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		387	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	388	it will be emulated, so you can call C<aio_sendfile> on any type of
359	regardless of the limitations of the operating system.	389	filehandle regardless of the limitations of the operating system.
360		390
361	Please note, however, that C<aio_sendfile> can read more bytes from	391	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	392	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	393	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	394	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	395	value equals C<$length> one can assume that C<$length> bytes have been
366	read.	396	read.
		397
367		398
368	=item aio_readahead $fh,$offset,$length, $callback->($retval)	399	=item aio_readahead $fh,$offset,$length, $callback->($retval)
369		400
370	C<aio_readahead> populates the page cache with data from a file so that	401	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>	402	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.	408	file. The current file offset of the file is left unchanged.
378		409
379	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	410	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.	411	emulated by simply reading the data, which would have a similar effect.
381		412
		413
382	=item aio_stat $fh_or_path, $callback->($status)	414	=item aio_stat $fh_or_path, $callback->($status)
383		415
384	=item aio_lstat $fh, $callback->($status)	416	=item aio_lstat $fh, $callback->($status)
385		417
386	Works like perl's C<stat> or C<lstat> in void context. The callback will	418	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
399	aio_stat "/etc/passwd", sub {	431	aio_stat "/etc/passwd", sub {
400	$_[0] and die "stat failed: $!";	432	$_[0] and die "stat failed: $!";
401	print "size is ", -s _, "\n";	433	print "size is ", -s _, "\n";
402	};	434	};
403		435
		436
		437	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		438
		439	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		440	whether a file handle or path was passed.
		441
		442	On success, the callback is passed a hash reference with the following
		443	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		444	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		445	is passed.
		446
		447	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		448	C<ST_NOSUID>.
		449
		450	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		451	their correct value when available, or to C<0> on systems that do
		452	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		453	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		454	C<ST_NODIRATIME> and C<ST_RELATIME>.
		455
		456	Example: stat C</wd> and dump out the data if successful.
		457
		458	aio_statvfs "/wd", sub {
		459	my $f = $_[0]
		460	or die "statvfs: $!";
		461
		462	use Data::Dumper;
		463	say Dumper $f;
		464	};
		465
		466	# result:
		467	{
		468	bsize => 1024,
		469	bfree => 4333064312,
		470	blocks => 10253828096,
		471	files => 2050765568,
		472	flag => 4096,
		473	favail => 2042092649,
		474	bavail => 4333064312,
		475	ffree => 2042092649,
		476	namemax => 255,
		477	frsize => 1024,
		478	fsid => 1810
		479	}
		480
		481
		482	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		483
		484	Works like perl's C<utime> function (including the special case of $atime
		485	and $mtime being undef). Fractional times are supported if the underlying
		486	syscalls support them.
		487
		488	When called with a pathname, uses utimes(2) if available, otherwise
		489	utime(2). If called on a file descriptor, uses futimes(2) if available,
		490	otherwise returns ENOSYS, so this is not portable.
		491
		492	Examples:
		493
		494	# set atime and mtime to current time (basically touch(1)):
		495	aio_utime "path", undef, undef;
		496	# set atime to current time and mtime to beginning of the epoch:
		497	aio_utime "path", time, undef; # undef==0
		498
		499
		500	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		501
		502	Works like perl's C<chown> function, except that C<undef> for either $uid
		503	or $gid is being interpreted as "do not change" (but -1 can also be used).
		504
		505	Examples:
		506
		507	# same as "chown root path" in the shell:
		508	aio_chown "path", 0, -1;
		509	# same as above:
		510	aio_chown "path", 0, undef;
		511
		512
		513	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		514
		515	Works like truncate(2) or ftruncate(2).
		516
		517
		518	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		519
		520	Works like perl's C<chmod> function.
		521
		522
404	=item aio_unlink $pathname, $callback->($status)	523	=item aio_unlink $pathname, $callback->($status)
405		524
406	Asynchronously unlink (delete) a file and call the callback with the	525	Asynchronously unlink (delete) a file and call the callback with the
407	result code.	526	result code.
408		527
		528
		529	=item aio_mknod $path, $mode, $dev, $callback->($status)
		530
		531	[EXPERIMENTAL]
		532
		533	Asynchronously create a device node (or fifo). See mknod(2).
		534
		535	The only (POSIX-) portable way of calling this function is:
		536
		537	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		538
		539
409	=item aio_link $srcpath, $dstpath, $callback->($status)	540	=item aio_link $srcpath, $dstpath, $callback->($status)
410		541
411	Asynchronously create a new link to the existing object at C<$srcpath> at	542	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.	543	the path C<$dstpath> and call the callback with the result code.
413		544
		545
414	=item aio_symlink $srcpath, $dstpath, $callback->($status)	546	=item aio_symlink $srcpath, $dstpath, $callback->($status)
415		547
416	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	548	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.	549	the path C<$dstpath> and call the callback with the result code.
418		550
		551
		552	=item aio_readlink $path, $callback->($link)
		553
		554	Asynchronously read the symlink specified by C<$path> and pass it to
		555	the callback. If an error occurs, nothing or undef gets passed to the
		556	callback.
		557
		558
419	=item aio_rename $srcpath, $dstpath, $callback->($status)	559	=item aio_rename $srcpath, $dstpath, $callback->($status)
420		560
421	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	561	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
422	rename(2) and call the callback with the result code.	562	rename(2) and call the callback with the result code.
423		563
		564
		565	=item aio_mkdir $pathname, $mode, $callback->($status)
		566
		567	Asynchronously mkdir (create) a directory and call the callback with
		568	the result code. C<$mode> will be modified by the umask at the time the
		569	request is executed, so do not change your umask.
		570
		571
424	=item aio_rmdir $pathname, $callback->($status)	572	=item aio_rmdir $pathname, $callback->($status)
425		573
426	Asynchronously rmdir (delete) a directory and call the callback with the	574	Asynchronously rmdir (delete) a directory and call the callback with the
427	result code.	575	result code.
		576
428		577
429	=item aio_readdir $pathname, $callback->($entries)	578	=item aio_readdir $pathname, $callback->($entries)
430		579
431	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	580	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	581	directory (i.e. opendir + readdir + closedir). The entries will not be
433	sorted, and will B<NOT> include the C<.> and C<..> entries.	582	sorted, and will B<NOT> include the C<.> and C<..> entries.
434		583
435	The callback a single argument which is either C<undef> or an array-ref	584	The callback is passed a single argument which is either C<undef> or an
436	with the filenames.	585	array-ref with the filenames.
		586
		587
		588	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		589
		590	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		591	behaviour and output format. In case of an error, C<$entries> will be
		592	C<undef>.
		593
		594	The flags are a combination of the following constants, ORed together (the
		595	flags will also be passed to the callback, possibly modified):
		596
		597	=over 4
		598
		599	=item IO::AIO::READDIR_DENTS
		600
		601	When this flag is off, then the callback gets an arrayref with of names
		602	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		603	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		604	entry in more detail.
		605
		606	C<$name> is the name of the entry.
		607
		608	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		609
		610	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		611	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		612	C<IO::AIO::DT_WHT>.
		613
		614	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		615	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		616	scalars are read-only: you can not modify them.
		617
		618	C<$inode> is the inode number (which might not be exact on systems with 64
		619	bit inode numbers and 32 bit perls). This field has unspecified content on
		620	systems that do not deliver the inode information.
		621
		622	=item IO::AIO::READDIR_DIRS_FIRST
		623
		624	When this flag is set, then the names will be returned in an order where
		625	likely directories come first. This is useful when you need to quickly
		626	find directories, or you want to find all directories while avoiding to
		627	stat() each entry.
		628
		629	If the system returns type information in readdir, then this is used
		630	to find directories directly. Otherwise, likely directories are files
		631	beginning with ".", or otherwise files with no dots, of which files with
		632	short names are tried first.
		633
		634	=item IO::AIO::READDIR_STAT_ORDER
		635
		636	When this flag is set, then the names will be returned in an order
		637	suitable for stat()'ing each one. That is, when you plan to stat()
		638	all files in the given directory, then the returned order will likely
		639	be fastest.
		640
		641	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		642	the likely dirs come first, resulting in a less optimal stat order.
		643
		644	=item IO::AIO::READDIR_FOUND_UNKNOWN
		645
		646	This flag should not be set when calling C<aio_readdirx>. Instead, it
		647	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		648	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		649	C<$type>'s are known, which can be used to speed up some algorithms.
		650
		651	=back
		652
		653
		654	=item aio_load $path, $data, $callback->($status)
		655
		656	This is a composite request that tries to fully load the given file into
		657	memory. Status is the same as with aio_read.
		658
		659	=cut
		660
		661	sub aio_load($$;$) {
		662	my ($path, undef, $cb) = @_;
		663	my $data = \$_[1];
		664
		665	my $pri = aioreq_pri;
		666	my $grp = aio_group $cb;
		667
		668	aioreq_pri $pri;
		669	add $grp aio_open $path, O_RDONLY, 0, sub {
		670	my $fh = shift
		671	or return $grp->result (-1);
		672
		673	aioreq_pri $pri;
		674	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		675	$grp->result ($_[0]);
		676	};
		677	};
		678
		679	$grp
		680	}
		681
		682	=item aio_copy $srcpath, $dstpath, $callback->($status)
		683
		684	Try to copy the I<file> (directories not supported as either source or
		685	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		686	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		687
		688	This is a composite request that creates the destination file with
		689	mode 0200 and copies the contents of the source file into it using
		690	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		691	uid/gid, in that order.
		692
		693	If an error occurs, the partial destination file will be unlinked, if
		694	possible, except when setting atime, mtime, access mode and uid/gid, where
		695	errors are being ignored.
		696
		697	=cut
		698
		699	sub aio_copy($$;$) {
		700	my ($src, $dst, $cb) = @_;
		701
		702	my $pri = aioreq_pri;
		703	my $grp = aio_group $cb;
		704
		705	aioreq_pri $pri;
		706	add $grp aio_open $src, O_RDONLY, 0, sub {
		707	if (my $src_fh = $_[0]) {
		708	my @stat = stat $src_fh; # hmm, might block over nfs?
		709
		710	aioreq_pri $pri;
		711	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		712	if (my $dst_fh = $_[0]) {
		713	aioreq_pri $pri;
		714	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		715	if ($_[0] == $stat[7]) {
		716	$grp->result (0);
		717	close $src_fh;
		718
		719	my $ch = sub {
		720	aioreq_pri $pri;
		721	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		722	aioreq_pri $pri;
		723	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		724	aioreq_pri $pri;
		725	add $grp aio_close $dst_fh;
		726	}
		727	};
		728	};
		729
		730	aioreq_pri $pri;
		731	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		732	if ($_[0] < 0 && $! == ENOSYS) {
		733	aioreq_pri $pri;
		734	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		735	} else {
		736	$ch->();
		737	}
		738	};
		739	} else {
		740	$grp->result (-1);
		741	close $src_fh;
		742	close $dst_fh;
		743
		744	aioreq $pri;
		745	add $grp aio_unlink $dst;
		746	}
		747	};
		748	} else {
		749	$grp->result (-1);
		750	}
		751	},
		752
		753	} else {
		754	$grp->result (-1);
		755	}
		756	};
		757
		758	$grp
		759	}
		760
		761	=item aio_move $srcpath, $dstpath, $callback->($status)
		762
		763	Try to move the I<file> (directories not supported as either source or
		764	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		765	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		766
		767	This is a composite request that tries to rename(2) the file first; if
		768	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		769	that is successful, unlinks the C<$srcpath>.
		770
		771	=cut
		772
		773	sub aio_move($$;$) {
		774	my ($src, $dst, $cb) = @_;
		775
		776	my $pri = aioreq_pri;
		777	my $grp = aio_group $cb;
		778
		779	aioreq_pri $pri;
		780	add $grp aio_rename $src, $dst, sub {
		781	if ($_[0] && $! == EXDEV) {
		782	aioreq_pri $pri;
		783	add $grp aio_copy $src, $dst, sub {
		784	$grp->result ($_[0]);
		785
		786	if (!$_[0]) {
		787	aioreq_pri $pri;
		788	add $grp aio_unlink $src;
		789	}
		790	};
		791	} else {
		792	$grp->result ($_[0]);
		793	}
		794	};
		795
		796	$grp
		797	}
437		798
438	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	799	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
439		800
440	Scans a directory (similar to C<aio_readdir>) but additionally tries to	801	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	802	efficiently separate the entries of directory C<$path> into two sets of
…		…
460		821
461	Implementation notes.	822	Implementation notes.
462		823
463	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	824	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
464		825
		826	If readdir returns file type information, then this is used directly to
		827	find directories.
		828
465	After reading the directory, the modification time, size etc. of the	829	Otherwise, after reading the directory, the modification time, size etc.
466	directory before and after the readdir is checked, and if they match (and	830	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	831	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	832	how many entries are directories (if >= 2). Otherwise, no knowledge of the
469	of subdirectories will be assumed.	833	number of subdirectories will be assumed.
470		834
471	Then entries will be sorted into likely directories (everything without	835	Then entries will be sorted into likely directories a non-initial dot
472	a non-initial dot currently) and likely non-directories (everything	836	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,	837	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	838	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	839	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	840	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	841	filesystems might detect the type of the entry without reading the inode
478	data (e.g. ext2fs filetype feature).	842	data (e.g. ext2fs filetype feature), even on systems that cannot return
		843	the filetype information on readdir.
479		844
480	If the known number of directories (link count - 2) has been reached, the	845	If the known number of directories (link count - 2) has been reached, the
481	rest of the entries is assumed to be non-directories.	846	rest of the entries is assumed to be non-directories.
482		847
483	This only works with certainty on POSIX (= UNIX) filesystems, which	848	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	852	as those tend to return 0 or 1 as link counts, which disables the
488	directory counting heuristic.	853	directory counting heuristic.
489		854
490	=cut	855	=cut
491		856
492	sub aio_scandir($$$) {	857	sub aio_scandir($$;$) {
493	my ($path, $maxreq, $cb) = @_;	858	my ($path, $maxreq, $cb) = @_;
494		859
495	my $pri = aioreq_pri;	860	my $pri = aioreq_pri;
496		861
497	my $grp = aio_group $cb;	862	my $grp = aio_group $cb;
…		…
505	my $now = time;	870	my $now = time;
506	my $hash1 = join ":", (stat _)[0,1,3,7,9];	871	my $hash1 = join ":", (stat _)[0,1,3,7,9];
507		872
508	# read the directory entries	873	# read the directory entries
509	aioreq_pri $pri;	874	aioreq_pri $pri;
510	add $grp aio_readdir $path, sub {	875	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
511	my $entries = shift	876	my $entries = shift
512	or return $grp->result ();	877	or return $grp->result ();
513		878
514	# stat the dir another time	879	# stat the dir another time
515	aioreq_pri $pri;	880	aioreq_pri $pri;
…		…
521	# take the slow route if anything looks fishy	886	# take the slow route if anything looks fishy
522	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	887	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
523	$ndirs = -1;	888	$ndirs = -1;
524	} else {	889	} else {
525	# if nlink == 2, we are finished	890	# if nlink == 2, we are finished
526	# on non-posix-fs's, we rely on nlink < 2	891	# for non-posix-fs's, we rely on nlink < 2
527	$ndirs = (stat _)[3] - 2	892	$ndirs = (stat _)[3] - 2
528	or return $grp->result ([], $entries);	893	or return $grp->result ([], $entries);
529	}	894	}
530		895
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);	896	my (@dirs, @nondirs);
539		897
540	my $statgrp = add $grp aio_group sub {	898	my $statgrp = add $grp aio_group sub {
541	$grp->result (\@dirs, \@nondirs);	899	$grp->result (\@dirs, \@nondirs);
542	};	900	};
543		901
544	limit $statgrp $maxreq;	902	limit $statgrp $maxreq;
545	feed $statgrp sub {	903	feed $statgrp sub {
546	return unless @$entries;	904	return unless @$entries;
547	my $entry = pop @$entries;	905	my $entry = shift @$entries;
548		906
549	aioreq_pri $pri;	907	aioreq_pri $pri;
550	add $statgrp aio_stat "$path/$entry/.", sub {	908	add $statgrp aio_stat "$path/$entry/.", sub {
551	if ($_[0] < 0) {	909	if ($_[0] < 0) {
552	push @nondirs, $entry;	910	push @nondirs, $entry;
…		…
573	};	931	};
574		932
575	$grp	933	$grp
576	}	934	}
577		935
		936	=item aio_rmtree $path, $callback->($status)
		937
		938	Delete a directory tree starting (and including) C<$path>, return the
		939	status of the final C<rmdir> only. This is a composite request that
		940	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		941	everything else.
		942
		943	=cut
		944
		945	sub aio_rmtree;
		946	sub aio_rmtree($;$) {
		947	my ($path, $cb) = @_;
		948
		949	my $pri = aioreq_pri;
		950	my $grp = aio_group $cb;
		951
		952	aioreq_pri $pri;
		953	add $grp aio_scandir $path, 0, sub {
		954	my ($dirs, $nondirs) = @_;
		955
		956	my $dirgrp = aio_group sub {
		957	add $grp aio_rmdir $path, sub {
		958	$grp->result ($_[0]);
		959	};
		960	};
		961
		962	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		963	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		964
		965	add $grp $dirgrp;
		966	};
		967
		968	$grp
		969	}
		970
		971	=item aio_sync $callback->($status)
		972
		973	Asynchronously call sync and call the callback when finished.
		974
578	=item aio_fsync $fh, $callback->($status)	975	=item aio_fsync $fh, $callback->($status)
579		976
580	Asynchronously call fsync on the given filehandle and call the callback	977	Asynchronously call fsync on the given filehandle and call the callback
581	with the fsync result code.	978	with the fsync result code.
582		979
…		…
585	Asynchronously call fdatasync on the given filehandle and call the	982	Asynchronously call fdatasync on the given filehandle and call the
586	callback with the fdatasync result code.	983	callback with the fdatasync result code.
587		984
588	If this call isn't available because your OS lacks it or it couldn't be	985	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.	986	detected, it will be emulated by calling C<fsync> instead.
		987
		988	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		989
		990	Sync the data portion of the file specified by C<$offset> and C<$length>
		991	to disk (but NOT the metadata), by calling the Linux-specific
		992	sync_file_range call. If sync_file_range is not available or it returns
		993	ENOSYS, then fdatasync or fsync is being substituted.
		994
		995	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		996	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		997	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		998	manpage for details.
		999
		1000	=item aio_pathsync $path, $callback->($status)
		1001
		1002	This request tries to open, fsync and close the given path. This is a
		1003	composite request intended to sync directories after directory operations
		1004	(E.g. rename). This might not work on all operating systems or have any
		1005	specific effect, but usually it makes sure that directory changes get
		1006	written to disc. It works for anything that can be opened for read-only,
		1007	not just directories.
		1008
		1009	Future versions of this function might fall back to other methods when
		1010	C<fsync> on the directory fails (such as calling C<sync>).
		1011
		1012	Passes C<0> when everything went ok, and C<-1> on error.
		1013
		1014	=cut
		1015
		1016	sub aio_pathsync($;$) {
		1017	my ($path, $cb) = @_;
		1018
		1019	my $pri = aioreq_pri;
		1020	my $grp = aio_group $cb;
		1021
		1022	aioreq_pri $pri;
		1023	add $grp aio_open $path, O_RDONLY, 0, sub {
		1024	my ($fh) = @_;
		1025	if ($fh) {
		1026	aioreq_pri $pri;
		1027	add $grp aio_fsync $fh, sub {
		1028	$grp->result ($_[0]);
		1029
		1030	aioreq_pri $pri;
		1031	add $grp aio_close $fh;
		1032	};
		1033	} else {
		1034	$grp->result (-1);
		1035	}
		1036	};
		1037
		1038	$grp
		1039	}
		1040
		1041	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1042
		1043	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1044	scalars (see the L<Sys::Mmap> or L<Mmap> modules for details on this, note
		1045	that the scalar must only be modified in-place while an aio operation is
		1046	pending on it).
		1047
		1048	It calls the C<msync> function of your OS, if available, with the memory
		1049	area starting at C<$offset> in the string and ending C<$length> bytes
		1050	later. If C<$length> is negative, counts from the end, and if C<$length>
		1051	is C<undef>, then it goes till the end of the string. The flags can be
		1052	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1053	C<IO::AIO::MS_SYNC>.
		1054
		1055	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1056
		1057	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1058	scalars.
		1059
		1060	It touches (reads or writes) all memory pages in the specified
		1061	range inside the scalar. All caveats and parameters are the same
		1062	as for C<aio_msync>, above, except for flags, which must be either
		1063	C<0> (which reads all pages and ensures they are instantiated) or
		1064	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1065	writing an octet from it, which dirties the page).
590		1066
591	=item aio_group $callback->(...)	1067	=item aio_group $callback->(...)
592		1068
593	This is a very special aio request: Instead of doing something, it is a	1069	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	1070	container for other aio requests, which is useful if you want to bundle
…		…
644	=item cancel $req	1120	=item cancel $req
645		1121
646	Cancels the request, if possible. Has the effect of skipping execution	1122	Cancels the request, if possible. Has the effect of skipping execution
647	when entering the B<execute> state and skipping calling the callback when	1123	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	1124	entering the the B<result> state, but will leave the request otherwise
649	untouched. That means that requests that currently execute will not be	1125	untouched (with the exception of readdir). That means that requests that
650	stopped and resources held by the request will not be freed prematurely.	1126	currently execute will not be stopped and resources held by the request
		1127	will not be freed prematurely.
651		1128
652	=item cb $req $callback->(...)	1129	=item cb $req $callback->(...)
653		1130
654	Replace (or simply set) the callback registered to the request.	1131	Replace (or simply set) the callback registered to the request.
655		1132
…		…
706	Their lifetime, simplified, looks like this: when they are empty, they	1183	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	1184	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	1185	C<done> state, they will also finish. Otherwise they will continue to
709	exist.	1186	exist.
710		1187
711	That means after creating a group you have some time to add requests. And	1188	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	1189	(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	1190	the C<poll_cb>). And in the callbacks of those requests, you can add
714	itself finish.	1191	further requests to the group. And only when all those requests have
		1192	finished will the the group itself finish.
715		1193
716	=over 4	1194	=over 4
717		1195
718	=item add $grp ...	1196	=item add $grp ...
719		1197
…		…
728	=item $grp->cancel_subs	1206	=item $grp->cancel_subs
729		1207
730	Cancel all subrequests and clears any feeder, but not the group request	1208	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.	1209	itself. Useful when you queued a lot of events but got a result early.
732		1210
		1211	The group request will finish normally (you cannot add requests to the
		1212	group).
		1213
733	=item $grp->result (...)	1214	=item $grp->result (...)
734		1215
735	Set the result value(s) that will be passed to the group callback when all	1216	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	1217	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,	1218	of errno (just like calling C<errno> without an error number). By default,
738	no argument will be passed and errno is zero.	1219	no argument will be passed and errno is zero.
739		1220
740	=item $grp->errno ([$errno])	1221	=item $grp->errno ([$errno])
741		1222
…		…
752	=item feed $grp $callback->($grp)	1233	=item feed $grp $callback->($grp)
753		1234
754	Sets a feeder/generator on this group: every group can have an attached	1235	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,	1236	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,	1237	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	1238	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>	1239	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
759	requests, delaying any later requests for a long time.	1240	delaying any later requests for a long time.
760		1241
761	To avoid this, and allow incremental generation of requests, you can	1242	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	1243	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>,	1244	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	1245	below) requests active in the group itself and is expected to queue more
…		…
768	not impose any limits).	1249	not impose any limits).
769		1250
770	If the feed does not queue more requests when called, it will be	1251	If the feed does not queue more requests when called, it will be
771	automatically removed from the group.	1252	automatically removed from the group.
772		1253
773	If the feed limit is C<0>, it will be set to C<2> automatically.	1254	If the feed limit is C<0> when this method is called, it will be set to
		1255	C<2> automatically.
774		1256
775	Example:	1257	Example:
776		1258
777	# stat all files in @files, but only ever use four aio requests concurrently:	1259	# stat all files in @files, but only ever use four aio requests concurrently:
778		1260
…		…
790	Sets the feeder limit for the group: The feeder will be called whenever	1272	Sets the feeder limit for the group: The feeder will be called whenever
791	the group contains less than this many requests.	1273	the group contains less than this many requests.
792		1274
793	Setting the limit to C<0> will pause the feeding process.	1275	Setting the limit to C<0> will pause the feeding process.
794		1276
		1277	The default value for the limit is C<0>, but note that setting a feeder
		1278	automatically bumps it up to C<2>.
		1279
795	=back	1280	=back
796		1281
797	=head2 SUPPORT FUNCTIONS	1282	=head2 SUPPORT FUNCTIONS
798		1283
		1284	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1285
799	=over 4	1286	=over 4
800		1287
801	=item $fileno = IO::AIO::poll_fileno	1288	=item $fileno = IO::AIO::poll_fileno
802		1289
803	Return the I<request result pipe file descriptor>. This filehandle must be	1290	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	1291	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	1292	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
806	to call C<poll_cb> to check the results.	1293	you have to call C<poll_cb> to check the results.
807		1294
808	See C<poll_cb> for an example.	1295	See C<poll_cb> for an example.
809		1296
810	=item IO::AIO::poll_cb	1297	=item IO::AIO::poll_cb
811		1298
812	Process all outstanding events on the result pipe. You have to call this	1299	Process some outstanding events on the result pipe. You have to call this
813	regularly. Returns the number of events processed. Returns immediately	1300	regularly. Returns C<0> if all events could be processed, or C<-1> if it
814	when no events are outstanding.	1301	returned earlier for whatever reason. Returns immediately when no events
		1302	are outstanding. The amount of events processed depends on the settings of
		1303	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
815		1304
816	If not all requests were processed for whatever reason, the filehandle	1305	If not all requests were processed for whatever reason, the filehandle
817	will still be ready when C<poll_cb> returns.	1306	will still be ready when C<poll_cb> returns, so normally you don't have to
		1307	do anything special to have it called later.
818		1308
819	Example: Install an Event watcher that automatically calls	1309	Example: Install an Event watcher that automatically calls
820	IO::AIO::poll_cb with high priority:	1310	IO::AIO::poll_cb with high priority (more examples can be found in the
		1311	SYNOPSIS section, at the top of this document):
821		1312
822	Event->io (fd => IO::AIO::poll_fileno,	1313	Event->io (fd => IO::AIO::poll_fileno,
823	poll => 'r', async => 1,	1314	poll => 'r', async => 1,
824	cb => \&IO::AIO::poll_cb);	1315	cb => \&IO::AIO::poll_cb);
825		1316
826	=item IO::AIO::poll_some $max_requests	1317	=item IO::AIO::max_poll_reqs $nreqs
827		1318
828	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests	1319	=item IO::AIO::max_poll_time $seconds
829	at a time.
830		1320
831	Useful if you want to ensure some level of interactiveness when perl is	1321	These set the maximum number of requests (default C<0>, meaning infinity)
832	not fast enough to process all requests in time.	1322	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1323	the maximum amount of time (default C<0>, meaning infinity) spent in
		1324	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1325	of time C<poll_cb> is allowed to use).
		1326
		1327	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1328	syscall per request processed, which is not normally a problem unless your
		1329	callbacks are really really fast or your OS is really really slow (I am
		1330	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1331
		1332	Setting these is useful if you want to ensure some level of
		1333	interactiveness when perl is not fast enough to process all requests in
		1334	time.
		1335
		1336	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
833		1337
834	Example: Install an Event watcher that automatically calls	1338	Example: Install an Event watcher that automatically calls
835	IO::AIO::poll_some with low priority, to ensure that other parts of the	1339	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.	1340	program get the CPU sometimes even under high AIO load.
837		1341
		1342	# try not to spend much more than 0.1s in poll_cb
		1343	IO::AIO::max_poll_time 0.1;
		1344
		1345	# use a low priority so other tasks have priority
838	Event->io (fd => IO::AIO::poll_fileno,	1346	Event->io (fd => IO::AIO::poll_fileno,
839	poll => 'r', nice => 1,	1347	poll => 'r', nice => 1,
840	cb => sub { IO::AIO::poll_some 256 });	1348	cb => &IO::AIO::poll_cb);
841		1349
842	=item IO::AIO::poll_wait	1350	=item IO::AIO::poll_wait
843		1351
		1352	If there are any outstanding requests and none of them in the result
844	Wait till the result filehandle becomes ready for reading (simply does a	1353	phase, wait till the result filehandle becomes ready for reading (simply
845	C<select> on the filehandle. This is useful if you want to synchronously wait	1354	does a C<select> on the filehandle. This is useful if you want to
846	for some requests to finish).	1355	synchronously wait for some requests to finish).
847		1356
848	See C<nreqs> for an example.	1357	See C<nreqs> for an example.
849		1358
		1359	=item IO::AIO::poll
		1360
		1361	Waits until some requests have been handled.
		1362
		1363	Returns the number of requests processed, but is otherwise strictly
		1364	equivalent to:
		1365
		1366	IO::AIO::poll_wait, IO::AIO::poll_cb
		1367
850	=item IO::AIO::nreqs	1368	=item IO::AIO::flush
851		1369
852	Returns the number of requests currently in the ready, execute or pending	1370	Wait till all outstanding AIO requests have been handled.
853	states (i.e. for which their callback has not been invoked yet).
854		1371
855	Example: wait till there are no outstanding requests anymore:	1372	Strictly equivalent to:
856		1373
857	IO::AIO::poll_wait, IO::AIO::poll_cb	1374	IO::AIO::poll_wait, IO::AIO::poll_cb
858	while IO::AIO::nreqs;	1375	while IO::AIO::nreqs;
859		1376
860	=item IO::AIO::nready	1377	=back
861		1378
862	Returns the number of requests currently in the ready state (not yet	1379	=head3 CONTROLLING THE NUMBER OF THREADS
863	executed).
864		1380
865	=item IO::AIO::npending	1381	=over
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		1382
888	=item IO::AIO::min_parallel $nthreads	1383	=item IO::AIO::min_parallel $nthreads
889		1384
890	Set the minimum number of AIO threads to C<$nthreads>. The current	1385	Set the minimum number of AIO threads to C<$nthreads>. The current
891	default is C<8>, which means eight asynchronous operations can execute	1386	default is C<8>, which means eight asynchronous operations can execute
892	concurrently at any one time (the number of outstanding requests,	1387	concurrently at any one time (the number of outstanding requests,
893	however, is unlimited).	1388	however, is unlimited).
894		1389
895	IO::AIO starts threads only on demand, when an AIO request is queued and	1390	IO::AIO starts threads only on demand, when an AIO request is queued and
896	no free thread exists.	1391	no free thread exists. Please note that queueing up a hundred requests can
		1392	create demand for a hundred threads, even if it turns out that everything
		1393	is in the cache and could have been processed faster by a single thread.
897		1394
898	It is recommended to keep the number of threads relatively low, as some	1395	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	1396	Linux kernel versions will scale negatively with the number of threads
900	(higher parallelity => MUCH higher latency). With current Linux 2.6	1397	(higher parallelity => MUCH higher latency). With current Linux 2.6
901	versions, 4-32 threads should be fine.	1398	versions, 4-32 threads should be fine.
…		…
915	This module automatically runs C<max_parallel 0> at program end, to ensure	1412	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.	1413	that all threads are killed and that there are no outstanding requests.
917		1414
918	Under normal circumstances you don't need to call this function.	1415	Under normal circumstances you don't need to call this function.
919		1416
		1417	=item IO::AIO::max_idle $nthreads
		1418
		1419	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1420	threads that did not get a request to process within 10 seconds). That
		1421	means if a thread becomes idle while C<$nthreads> other threads are also
		1422	idle, it will free its resources and exit.
		1423
		1424	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1425	to allow for extremely high load situations, but want to free resources
		1426	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1427
		1428	The default is probably ok in most situations, especially if thread
		1429	creation is fast. If thread creation is very slow on your system you might
		1430	want to use larger values.
		1431
920	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1432	=item IO::AIO::max_outstanding $maxreqs
921		1433
922	This is a very bad function to use in interactive programs because it	1434	This is a very bad function to use in interactive programs because it
923	blocks, and a bad way to reduce concurrency because it is inexact: Better	1435	blocks, and a bad way to reduce concurrency because it is inexact: Better
924	use an C<aio_group> together with a feed callback.	1436	use an C<aio_group> together with a feed callback.
925		1437
926	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1438	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	1439	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>)	1440	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.	1441	function will block until the limit is no longer exceeded.
930		1442
931	The default value is very large, so there is no practical limit on the	1443	The default value is very large, so there is no practical limit on the
932	number of outstanding requests.	1444	number of outstanding requests.
933		1445
934	You can still queue as many requests as you want. Therefore,	1446	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	1447	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).	1448	as a stop gap to shield against fatal memory overflow (with large values).
937		1449
938	=back	1450	=back
939		1451
		1452	=head3 STATISTICAL INFORMATION
		1453
		1454	=over
		1455
		1456	=item IO::AIO::nreqs
		1457
		1458	Returns the number of requests currently in the ready, execute or pending
		1459	states (i.e. for which their callback has not been invoked yet).
		1460
		1461	Example: wait till there are no outstanding requests anymore:
		1462
		1463	IO::AIO::poll_wait, IO::AIO::poll_cb
		1464	while IO::AIO::nreqs;
		1465
		1466	=item IO::AIO::nready
		1467
		1468	Returns the number of requests currently in the ready state (not yet
		1469	executed).
		1470
		1471	=item IO::AIO::npending
		1472
		1473	Returns the number of requests currently in the pending state (executed,
		1474	but not yet processed by poll_cb).
		1475
		1476	=back
		1477
		1478	=head3 MISCELLANEOUS FUNCTIONS
		1479
		1480	IO::AIO implements some functions that might be useful, but are not
		1481	asynchronous.
		1482
		1483	=over 4
		1484
		1485	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1486
		1487	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1488	but is blocking (this makes most sense if you know the input data is
		1489	likely cached already and the output filehandle is set to non-blocking
		1490	operations).
		1491
		1492	Returns the number of bytes copied, or C<-1> on error.
		1493
		1494	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1495
		1496	Simply calls the C<posix_fadvise> function (see it's
		1497	manpage for details). The following advice constants are
		1498	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1499	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1500	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1501
		1502	On systems that do not implement C<posix_fadvise>, this function returns
		1503	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1504
		1505	=back
		1506
940	=cut	1507	=cut
941		1508
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;	1509	min_parallel 8;
		1510
		1511	END { flush }
959		1512
960	1;	1513	1;
961		1514
962	=head2 FORK BEHAVIOUR	1515	=head2 FORK BEHAVIOUR
963		1516
…		…
983	bytes of memory. In addition, stat requests need a stat buffer (possibly	1536	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	1537	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	1538	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.	1539	will consume memory till the request has entered the done state.
987		1540
988	This is now awfully much, so queuing lots of requests is not usually a	1541	This is not awfully much, so queuing lots of requests is not usually a
989	problem.	1542	problem.
990		1543
991	Per-thread usage:	1544	Per-thread usage:
992		1545
993	In the execution phase, some aio requests require more memory for	1546	In the execution phase, some aio requests require more memory for
…		…
998		1551
999	Known bugs will be fixed in the next release.	1552	Known bugs will be fixed in the next release.
1000		1553
1001	=head1 SEE ALSO	1554	=head1 SEE ALSO
1002		1555
1003	L<Coro::AIO>.	1556	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1557	more natural syntax.
1004		1558
1005	=head1 AUTHOR	1559	=head1 AUTHOR
1006		1560
1007	Marc Lehmann <schmorp@schmorp.de>	1561	Marc Lehmann <schmorp@schmorp.de>
1008	http://home.schmorp.de/	1562	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC vs. Revision 1.173 by root, Thu Jan 7 20:25:57 2010 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC vs.
Revision 1.173 by root, Thu Jan 7 20:25:57 2010 UTC