ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs.
Revision 1.165 by root, Tue Aug 18 04:05:00 2009 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>).
55		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.
		75
56	Currently, a number of threads are started that execute your read/writes	76	In this version, a number of threads are started that execute your
57	and signal their completion. You don't need thread support in perl, and	77	requests and signal their completion. You don't need thread support
58	the threads created by this module will not be visible to perl. In the	78	in perl, and the threads created by this module will not be visible
59	future, this module might make use of the native aio functions available	79	to perl. In the future, this module might make use of the native aio
60	on many operating systems. However, they are often not well-supported	80	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	81	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	and they would only support aio_read and aio_write, so the remaining	82	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	83	aio_write, so the remaining functionality would have to be implemented
		84	using threads anyway.
64		85
65	Although the module will work with in the presence of other threads,	86	Although the module will work in the presence of other (Perl-) threads,
66	it is currently not reentrant in any way, so use appropriate locking	87	it is currently not reentrant in any way, so use appropriate locking
67	yourself, always call C<poll_cb> from within the same thread, or never	88	yourself, always call C<poll_cb> from within the same thread, or never
68	call C<poll_cb> (or other C<aio_> functions) recursively.	89	call C<poll_cb> (or other C<aio_> functions) recursively.
69		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;
		132
		133	=head1 REQUEST ANATOMY AND LIFETIME
		134
		135	Every C<aio_*> function creates a request. which is a C data structure not
		136	directly visible to Perl.
		137
		138	If called in non-void context, every request function returns a Perl
		139	object representing the request. In void context, nothing is returned,
		140	which saves a bit of memory.
		141
		142	The perl object is a fairly standard ref-to-hash object. The hash contents
		143	are not used by IO::AIO so you are free to store anything you like in it.
		144
		145	During their existance, aio requests travel through the following states,
		146	in order:
		147
		148	=over 4
		149
		150	=item ready
		151
		152	Immediately after a request is created it is put into the ready state,
		153	waiting for a thread to execute it.
		154
		155	=item execute
		156
		157	A thread has accepted the request for processing and is currently
		158	executing it (e.g. blocking in read).
		159
		160	=item pending
		161
		162	The request has been executed and is waiting for result processing.
		163
		164	While request submission and execution is fully asynchronous, result
		165	processing is not and relies on the perl interpreter calling C<poll_cb>
		166	(or another function with the same effect).
		167
		168	=item result
		169
		170	The request results are processed synchronously by C<poll_cb>.
		171
		172	The C<poll_cb> function will process all outstanding aio requests by
		173	calling their callbacks, freeing memory associated with them and managing
		174	any groups they are contained in.
		175
		176	=item done
		177
		178	Request has reached the end of its lifetime and holds no resources anymore
		179	(except possibly for the Perl object, but its connection to the actual
		180	aio request is severed and calling its methods will either do nothing or
		181	result in a runtime error).
		182
		183	=back
		184
70	=cut	185	=cut
71		186
72	package IO::AIO;	187	package IO::AIO;
73		188
74	no warnings;	189	use Carp ();
75	use strict 'vars';	190
		191	use common::sense;
76		192
77	use base 'Exporter';	193	use base 'Exporter';
78		194
79	BEGIN {	195	BEGIN {
80	our $VERSION = '2.0';	196	our $VERSION = '3.3';
81		197
82	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
83	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
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	200	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
85	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
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	206	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	207	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	208	min_parallel max_parallel max_idle
		209	nreqs nready npending nthreads
		210	max_poll_time max_poll_reqs
		211	sendfile fadvise);
		212
		213	push @AIO_REQ, qw(aio_busy); # not exported
89		214
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		216
92	require XSLoader;	217	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	218	XSLoader::load ("IO::AIO", $VERSION);
94	}	219	}
95		220
96	=head1 FUNCTIONS	221	=head1 FUNCTIONS
97		222
98	=head2 AIO FUNCTIONS	223	=head2 AIO REQUEST FUNCTIONS
99		224
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	225	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	226	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	227	and they all accept an additional (and optional) C<$callback> argument
103	which must be a code reference. This code reference will get called with	228	which must be a code reference. This code reference will get called with
104	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	229	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
105	perl, which usually delivers "false") as it's sole argument when the given	230	perl, which usually delivers "false") as its sole argument after the given
106	syscall has been executed asynchronously.	231	syscall has been executed asynchronously.
107		232
108	All functions expecting a filehandle keep a copy of the filehandle	233	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	234	internally until the request has finished.
110		235
111	All requests return objects of type L<IO::AIO::REQ> that allow further	236	All functions return request objects of type L<IO::AIO::REQ> that allow
112	manipulation of those requests while they are in-flight.	237	further manipulation of those requests while they are in-flight.
113		238
114	The pathnames you pass to these routines I<must> be absolute and	239	The pathnames you pass to these routines I<must> be absolute and
115	encoded in byte form. The reason for the former is that at the time the	240	encoded as octets. The reason for the former is that at the time the
116	request is being executed, the current working directory could have	241	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	242	changed. Alternatively, you can make sure that you never change the
118	current working directory.	243	current working directory anywhere in the program and then use relative
		244	paths.
119		245
120	To encode pathnames to byte form, either make sure you either: a)	246	To encode pathnames as octets, either make sure you either: a) always pass
121	always pass in filenames you got from outside (command line, readdir	247	in filenames you got from outside (command line, readdir etc.) without
122	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	248	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
123	your pathnames to the locale (or other) encoding in effect in the user	249	your pathnames to the locale (or other) encoding in effect in the user
124	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	250	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	251	use something else to ensure your scalar has the correct contents.
		252
		253	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		254	handles correctly whether it is set or not.
126		255
127	=over 4	256	=over 4
128		257
129	=item aioreq_pri $pri	258	=item $prev_pri = aioreq_pri [$pri]
130		259
131	Sets the priority for the next aio request. The default priority	260	Returns the priority value that would be used for the next request and, if
		261	C<$pri> is given, sets the priority for the next aio request.
		262
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	263	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	264	and C<4>, respectively. Requests with higher priority will be serviced
		265	first.
134		266
135	The priority will be reset to C<0> after each call to one of the C<aio_>	267	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	268	functions.
137		269
138	Example: open a file with low priority, then read something from it with	270	Example: open a file with low priority, then read something from it with
139	higher priority so the read request is serviced before other low priority	271	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	272	open requests (potentially spamming the cache):
…		…
147	aio_read $_[0], ..., sub {	279	aio_read $_[0], ..., sub {
148	...	280	...
149	};	281	};
150	};	282	};
151		283
		284
152	=item aioreq_nice $pri_adjust	285	=item aioreq_nice $pri_adjust
153		286
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	287	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	288	priority, so the effect is cumulative.
		289
156		290
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	291	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		292
159	Asynchronously open or create a file and call the callback with a newly	293	Asynchronously open or create a file and call the callback with a newly
160	created filehandle for the file.	294	created filehandle for the file.
…		…
166	list. They are the same as used by C<sysopen>.	300	list. They are the same as used by C<sysopen>.
167		301
168	Likewise, C<$mode> specifies the mode of the newly created file, if it	302	Likewise, C<$mode> specifies the mode of the newly created file, if it
169	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	303	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
170	except that it is mandatory (i.e. use C<0> if you don't create new files,	304	except that it is mandatory (i.e. use C<0> if you don't create new files,
171	and C<0666> or C<0777> if you do).	305	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		306	by the umask in effect then the request is being executed, so better never
		307	change the umask.
172		308
173	Example:	309	Example:
174		310
175	aio_open "/etc/passwd", O_RDONLY, 0, sub {	311	aio_open "/etc/passwd", O_RDONLY, 0, sub {
176	if ($_[0]) {	312	if ($_[0]) {
…		…
179	} else {	315	} else {
180	die "open failed: $!\n";	316	die "open failed: $!\n";
181	}	317	}
182	};	318	};
183		319
		320
184	=item aio_close $fh, $callback->($status)	321	=item aio_close $fh, $callback->($status)
185		322
186	Asynchronously close a file and call the callback with the result	323	Asynchronously close a file and call the callback with the result
187	code. I<WARNING:> although accepted, you should not pass in a perl	324	code.
188	filehandle here, as perl will likely close the file descriptor another
189	time when the filehandle is destroyed. Normally, you can safely call perls
190	C<close> or just let filehandles go out of scope.
191		325
192	This is supposed to be a bug in the API, so that might change. It's	326	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
193	therefore best to avoid this function.	327	closing the file descriptor associated with the filehandle itself.
		328
		329	Therefore, C<aio_close> will not close the filehandle - instead it will
		330	use dup2 to overwrite the file descriptor with the write-end of a pipe
		331	(the pipe fd will be created on demand and will be cached).
		332
		333	Or in other words: the file descriptor will be closed, but it will not be
		334	free for reuse until the perl filehandle is closed.
		335
		336	=cut
194		337
195	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	338	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
196		339
197	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	340	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
198		341
199	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	342	Reads or writes C<$length> bytes from or to the specified C<$fh> and
200	into the scalar given by C<data> and offset C<dataoffset> and calls the	343	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
201	callback without the actual number of bytes read (or -1 on error, just	344	and calls the callback without the actual number of bytes read (or -1 on
202	like the syscall).	345	error, just like the syscall).
		346
		347	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		348	offset plus the actual number of bytes read.
		349
		350	If C<$offset> is undefined, then the current file descriptor offset will
		351	be used (and updated), otherwise the file descriptor offset will not be
		352	changed by these calls.
		353
		354	If C<$length> is undefined in C<aio_write>, use the remaining length of
		355	C<$data>.
		356
		357	If C<$dataoffset> is less than zero, it will be counted from the end of
		358	C<$data>.
203		359
204	The C<$data> scalar I<MUST NOT> be modified in any way while the request	360	The C<$data> scalar I<MUST NOT> be modified in any way while the request
205	is outstanding. Modifying it can result in segfaults or WW3 (if the	361	is outstanding. Modifying it can result in segfaults or World War III (if
206	necessary/optional hardware is installed).	362	the necessary/optional hardware is installed).
207		363
208	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	364	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
209	offset C<0> within the scalar:	365	offset C<0> within the scalar:
210		366
211	aio_read $fh, 7, 15, $buffer, 0, sub {	367	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	368	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	369	print "read $_[0] bytes: <$buffer>\n";
214	};	370	};
215		371
216	=item aio_move $srcpath, $dstpath, $callback->($status)
217
218	Try to move the I<file> (directories not supported as either source or
219	destination) from C<$srcpath> to C<$dstpath> and call the callback with
220	the C<0> (error) or C<-1> ok.
221
222	This is a composite request that tries to rename(2) the file first. If
223	rename files with C<EXDEV>, it creates the destination file with mode 0200
224	and copies the contents of the source file into it using C<aio_sendfile>,
225	followed by restoring atime, mtime, access mode and uid/gid, in that
226	order, and unlinking the C<$srcpath>.
227
228	If an error occurs, the partial destination file will be unlinked, if
229	possible, except when setting atime, mtime, access mode and uid/gid, where
230	errors are being ignored.
231
232	=cut
233
234	sub aio_move($$$) {
235	my ($src, $dst, $cb) = @_;
236
237	my $grp = aio_group $cb;
238
239	add $grp aio_rename $src, $dst, sub {
240	if ($_[0] && $! == EXDEV) {
241	add $grp aio_open $src, O_RDONLY, 0, sub {
242	if (my $src_fh = $_[0]) {
243	my @stat = stat $src_fh;
244
245	add $grp aio_open $dst, O_WRONLY, 0200, sub {
246	if (my $dst_fh = $_[0]) {
247	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
248	close $src_fh;
249
250	if ($_[0] == $stat[7]) {
251	utime $stat[8], $stat[9], $dst;
252	chmod $stat[2] & 07777, $dst_fh;
253	chown $stat[4], $stat[5], $dst_fh;
254	close $dst_fh;
255
256	add $grp aio_unlink $src, sub {
257	$grp->result ($_[0]);
258	};
259	} else {
260	my $errno = $!;
261	add $grp aio_unlink $dst, sub {
262	$! = $errno;
263	$grp->result (-1);
264	};
265	}
266	};
267	} else {
268	$grp->result (-1);
269	}
270	},
271
272	} else {
273	$grp->result (-1);
274	}
275	};
276	} else {
277	$grp->result ($_[0]);
278	}
279	};
280
281	$grp
282	}
283		372
284	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	373	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
285		374
286	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	375	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
287	reading at byte offset C<$in_offset>, and starts writing at the current	376	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
301	C<$in_fh> than are written, and there is no way to find out how many	390	C<$in_fh> than are written, and there is no way to find out how many
302	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	391	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
303	provides the number of bytes written to C<$out_fh>. Only if the result	392	provides the number of bytes written to C<$out_fh>. Only if the result
304	value equals C<$length> one can assume that C<$length> bytes have been	393	value equals C<$length> one can assume that C<$length> bytes have been
305	read.	394	read.
		395
306		396
307	=item aio_readahead $fh,$offset,$length, $callback->($retval)	397	=item aio_readahead $fh,$offset,$length, $callback->($retval)
308		398
309	C<aio_readahead> populates the page cache with data from a file so that	399	C<aio_readahead> populates the page cache with data from a file so that
310	subsequent reads from that file will not block on disk I/O. The C<$offset>	400	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
316	file. The current file offset of the file is left unchanged.	406	file. The current file offset of the file is left unchanged.
317		407
318	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	408	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
319	emulated by simply reading the data, which would have a similar effect.	409	emulated by simply reading the data, which would have a similar effect.
320		410
		411
321	=item aio_stat $fh_or_path, $callback->($status)	412	=item aio_stat $fh_or_path, $callback->($status)
322		413
323	=item aio_lstat $fh, $callback->($status)	414	=item aio_lstat $fh, $callback->($status)
324		415
325	Works like perl's C<stat> or C<lstat> in void context. The callback will	416	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
338	aio_stat "/etc/passwd", sub {	429	aio_stat "/etc/passwd", sub {
339	$_[0] and die "stat failed: $!";	430	$_[0] and die "stat failed: $!";
340	print "size is ", -s _, "\n";	431	print "size is ", -s _, "\n";
341	};	432	};
342		433
		434
		435	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		436
		437	Works like perl's C<utime> function (including the special case of $atime
		438	and $mtime being undef). Fractional times are supported if the underlying
		439	syscalls support them.
		440
		441	When called with a pathname, uses utimes(2) if available, otherwise
		442	utime(2). If called on a file descriptor, uses futimes(2) if available,
		443	otherwise returns ENOSYS, so this is not portable.
		444
		445	Examples:
		446
		447	# set atime and mtime to current time (basically touch(1)):
		448	aio_utime "path", undef, undef;
		449	# set atime to current time and mtime to beginning of the epoch:
		450	aio_utime "path", time, undef; # undef==0
		451
		452
		453	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		454
		455	Works like perl's C<chown> function, except that C<undef> for either $uid
		456	or $gid is being interpreted as "do not change" (but -1 can also be used).
		457
		458	Examples:
		459
		460	# same as "chown root path" in the shell:
		461	aio_chown "path", 0, -1;
		462	# same as above:
		463	aio_chown "path", 0, undef;
		464
		465
		466	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		467
		468	Works like truncate(2) or ftruncate(2).
		469
		470
		471	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		472
		473	Works like perl's C<chmod> function.
		474
		475
343	=item aio_unlink $pathname, $callback->($status)	476	=item aio_unlink $pathname, $callback->($status)
344		477
345	Asynchronously unlink (delete) a file and call the callback with the	478	Asynchronously unlink (delete) a file and call the callback with the
346	result code.	479	result code.
347		480
		481
		482	=item aio_mknod $path, $mode, $dev, $callback->($status)
		483
		484	[EXPERIMENTAL]
		485
		486	Asynchronously create a device node (or fifo). See mknod(2).
		487
		488	The only (POSIX-) portable way of calling this function is:
		489
		490	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		491
		492
348	=item aio_link $srcpath, $dstpath, $callback->($status)	493	=item aio_link $srcpath, $dstpath, $callback->($status)
349		494
350	Asynchronously create a new link to the existing object at C<$srcpath> at	495	Asynchronously create a new link to the existing object at C<$srcpath> at
351	the path C<$dstpath> and call the callback with the result code.	496	the path C<$dstpath> and call the callback with the result code.
352		497
		498
353	=item aio_symlink $srcpath, $dstpath, $callback->($status)	499	=item aio_symlink $srcpath, $dstpath, $callback->($status)
354		500
355	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	501	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
356	the path C<$dstpath> and call the callback with the result code.	502	the path C<$dstpath> and call the callback with the result code.
357		503
		504
		505	=item aio_readlink $path, $callback->($link)
		506
		507	Asynchronously read the symlink specified by C<$path> and pass it to
		508	the callback. If an error occurs, nothing or undef gets passed to the
		509	callback.
		510
		511
358	=item aio_rename $srcpath, $dstpath, $callback->($status)	512	=item aio_rename $srcpath, $dstpath, $callback->($status)
359		513
360	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	514	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
361	rename(2) and call the callback with the result code.	515	rename(2) and call the callback with the result code.
362		516
		517
		518	=item aio_mkdir $pathname, $mode, $callback->($status)
		519
		520	Asynchronously mkdir (create) a directory and call the callback with
		521	the result code. C<$mode> will be modified by the umask at the time the
		522	request is executed, so do not change your umask.
		523
		524
363	=item aio_rmdir $pathname, $callback->($status)	525	=item aio_rmdir $pathname, $callback->($status)
364		526
365	Asynchronously rmdir (delete) a directory and call the callback with the	527	Asynchronously rmdir (delete) a directory and call the callback with the
366	result code.	528	result code.
		529
367		530
368	=item aio_readdir $pathname, $callback->($entries)	531	=item aio_readdir $pathname, $callback->($entries)
369		532
370	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	533	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
371	directory (i.e. opendir + readdir + closedir). The entries will not be	534	directory (i.e. opendir + readdir + closedir). The entries will not be
372	sorted, and will B<NOT> include the C<.> and C<..> entries.	535	sorted, and will B<NOT> include the C<.> and C<..> entries.
373		536
374	The callback a single argument which is either C<undef> or an array-ref	537	The callback is passed a single argument which is either C<undef> or an
375	with the filenames.	538	array-ref with the filenames.
		539
		540
		541	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		542
		543	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		544	behaviour and output format. In case of an error, C<$entries> will be
		545	C<undef>.
		546
		547	The flags are a combination of the following constants, ORed together (the
		548	flags will also be passed to the callback, possibly modified):
		549
		550	=over 4
		551
		552	=item IO::AIO::READDIR_DENTS
		553
		554	When this flag is off, then the callback gets an arrayref with of names
		555	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		556	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		557	entry in more detail.
		558
		559	C<$name> is the name of the entry.
		560
		561	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		562
		563	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		564	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		565	C<IO::AIO::DT_WHT>.
		566
		567	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		568	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		569	scalars are read-only: you can not modify them.
		570
		571	C<$inode> is the inode number (which might not be exact on systems with 64
		572	bit inode numbers and 32 bit perls). This field has unspecified content on
		573	systems that do not deliver the inode information.
		574
		575	=item IO::AIO::READDIR_DIRS_FIRST
		576
		577	When this flag is set, then the names will be returned in an order where
		578	likely directories come first. This is useful when you need to quickly
		579	find directories, or you want to find all directories while avoiding to
		580	stat() each entry.
		581
		582	If the system returns type information in readdir, then this is used
		583	to find directories directly. Otherwise, likely directories are files
		584	beginning with ".", or otherwise files with no dots, of which files with
		585	short names are tried first.
		586
		587	=item IO::AIO::READDIR_STAT_ORDER
		588
		589	When this flag is set, then the names will be returned in an order
		590	suitable for stat()'ing each one. That is, when you plan to stat()
		591	all files in the given directory, then the returned order will likely
		592	be fastest.
		593
		594	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		595	the likely dirs come first, resulting in a less optimal stat order.
		596
		597	=item IO::AIO::READDIR_FOUND_UNKNOWN
		598
		599	This flag should not be set when calling C<aio_readdirx>. Instead, it
		600	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		601	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		602	C<$type>'s are known, which can be used to speed up some algorithms.
		603
		604	=back
		605
		606
		607	=item aio_load $path, $data, $callback->($status)
		608
		609	This is a composite request that tries to fully load the given file into
		610	memory. Status is the same as with aio_read.
		611
		612	=cut
		613
		614	sub aio_load($$;$) {
		615	my ($path, undef, $cb) = @_;
		616	my $data = \$_[1];
		617
		618	my $pri = aioreq_pri;
		619	my $grp = aio_group $cb;
		620
		621	aioreq_pri $pri;
		622	add $grp aio_open $path, O_RDONLY, 0, sub {
		623	my $fh = shift
		624	or return $grp->result (-1);
		625
		626	aioreq_pri $pri;
		627	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		628	$grp->result ($_[0]);
		629	};
		630	};
		631
		632	$grp
		633	}
		634
		635	=item aio_copy $srcpath, $dstpath, $callback->($status)
		636
		637	Try to copy the I<file> (directories not supported as either source or
		638	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		639	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		640
		641	This is a composite request that creates the destination file with
		642	mode 0200 and copies the contents of the source file into it using
		643	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		644	uid/gid, in that order.
		645
		646	If an error occurs, the partial destination file will be unlinked, if
		647	possible, except when setting atime, mtime, access mode and uid/gid, where
		648	errors are being ignored.
		649
		650	=cut
		651
		652	sub aio_copy($$;$) {
		653	my ($src, $dst, $cb) = @_;
		654
		655	my $pri = aioreq_pri;
		656	my $grp = aio_group $cb;
		657
		658	aioreq_pri $pri;
		659	add $grp aio_open $src, O_RDONLY, 0, sub {
		660	if (my $src_fh = $_[0]) {
		661	my @stat = stat $src_fh; # hmm, might bock over nfs?
		662
		663	aioreq_pri $pri;
		664	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		665	if (my $dst_fh = $_[0]) {
		666	aioreq_pri $pri;
		667	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		668	if ($_[0] == $stat[7]) {
		669	$grp->result (0);
		670	close $src_fh;
		671
		672	my $ch = sub {
		673	aioreq_pri $pri;
		674	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		675	aioreq_pri $pri;
		676	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		677	aioreq_pri $pri;
		678	add $grp aio_close $dst_fh;
		679	}
		680	};
		681	};
		682
		683	aioreq_pri $pri;
		684	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		685	if ($_[0] < 0 && $! == ENOSYS) {
		686	aioreq_pri $pri;
		687	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		688	} else {
		689	$ch->();
		690	}
		691	};
		692	} else {
		693	$grp->result (-1);
		694	close $src_fh;
		695	close $dst_fh;
		696
		697	aioreq $pri;
		698	add $grp aio_unlink $dst;
		699	}
		700	};
		701	} else {
		702	$grp->result (-1);
		703	}
		704	},
		705
		706	} else {
		707	$grp->result (-1);
		708	}
		709	};
		710
		711	$grp
		712	}
		713
		714	=item aio_move $srcpath, $dstpath, $callback->($status)
		715
		716	Try to move the I<file> (directories not supported as either source or
		717	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		718	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		719
		720	This is a composite request that tries to rename(2) the file first; if
		721	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		722	that is successful, unlinks the C<$srcpath>.
		723
		724	=cut
		725
		726	sub aio_move($$;$) {
		727	my ($src, $dst, $cb) = @_;
		728
		729	my $pri = aioreq_pri;
		730	my $grp = aio_group $cb;
		731
		732	aioreq_pri $pri;
		733	add $grp aio_rename $src, $dst, sub {
		734	if ($_[0] && $! == EXDEV) {
		735	aioreq_pri $pri;
		736	add $grp aio_copy $src, $dst, sub {
		737	$grp->result ($_[0]);
		738
		739	if (!$_[0]) {
		740	aioreq_pri $pri;
		741	add $grp aio_unlink $src;
		742	}
		743	};
		744	} else {
		745	$grp->result ($_[0]);
		746	}
		747	};
		748
		749	$grp
		750	}
376		751
377	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	752	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
378		753
379	Scans a directory (similar to C<aio_readdir>) but additionally tries to	754	Scans a directory (similar to C<aio_readdir>) but additionally tries to
380	separate the entries of directory C<$path> into two sets of names, ones	755	efficiently separate the entries of directory C<$path> into two sets of
381	you can recurse into (directories or links to them), and ones you cannot	756	names, directories you can recurse into (directories), and ones you cannot
382	recurse into (everything else).	757	recurse into (everything else, including symlinks to directories).
383		758
384	C<aio_scandir> is a composite request that creates of many sub requests_	759	C<aio_scandir> is a composite request that creates of many sub requests_
385	C<$maxreq> specifies the maximum number of outstanding aio requests that	760	C<$maxreq> specifies the maximum number of outstanding aio requests that
386	this function generates. If it is C<< <= 0 >>, then a suitable default	761	this function generates. If it is C<< <= 0 >>, then a suitable default
387	will be chosen (currently 6).	762	will be chosen (currently 4).
388		763
389	On error, the callback is called without arguments, otherwise it receives	764	On error, the callback is called without arguments, otherwise it receives
390	two array-refs with path-relative entry names.	765	two array-refs with path-relative entry names.
391		766
392	Example:	767	Example:
…		…
399		774
400	Implementation notes.	775	Implementation notes.
401		776
402	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	777	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
403		778
		779	If readdir returns file type information, then this is used directly to
		780	find directories.
		781
404	After reading the directory, the modification time, size etc. of the	782	Otherwise, after reading the directory, the modification time, size etc.
405	directory before and after the readdir is checked, and if they match (and	783	of the directory before and after the readdir is checked, and if they
406	isn't the current time), the link count will be used to decide how many	784	match (and isn't the current time), the link count will be used to decide
407	entries are directories (if >= 2). Otherwise, no knowledge of the number	785	how many entries are directories (if >= 2). Otherwise, no knowledge of the
408	of subdirectories will be assumed.	786	number of subdirectories will be assumed.
409		787
410	Then entries will be sorted into likely directories (everything without	788	Then entries will be sorted into likely directories a non-initial dot
411	a non-initial dot currently) and likely non-directories (everything	789	currently) and likely non-directories (see C<aio_readdirx>). Then every
412	else). Then every entry plus an appended C</.> will be C<stat>'ed,	790	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
413	likely directories first. If that succeeds, it assumes that the entry	791	in order of their inode numbers. If that succeeds, it assumes that the
414	is a directory or a symlink to directory (which will be checked	792	entry is a directory or a symlink to directory (which will be checked
415	seperately). This is often faster than stat'ing the entry itself because	793	seperately). This is often faster than stat'ing the entry itself because
416	filesystems might detect the type of the entry without reading the inode	794	filesystems might detect the type of the entry without reading the inode
417	data (e.g. ext2fs filetype feature).	795	data (e.g. ext2fs filetype feature), even on systems that cannot return
		796	the filetype information on readdir.
418		797
419	If the known number of directories (link count - 2) has been reached, the	798	If the known number of directories (link count - 2) has been reached, the
420	rest of the entries is assumed to be non-directories.	799	rest of the entries is assumed to be non-directories.
421		800
422	This only works with certainty on POSIX (= UNIX) filesystems, which	801	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
426	as those tend to return 0 or 1 as link counts, which disables the	805	as those tend to return 0 or 1 as link counts, which disables the
427	directory counting heuristic.	806	directory counting heuristic.
428		807
429	=cut	808	=cut
430		809
431	sub aio_scandir($$$) {	810	sub aio_scandir($$;$) {
432	my ($path, $maxreq, $cb) = @_;	811	my ($path, $maxreq, $cb) = @_;
433		812
		813	my $pri = aioreq_pri;
		814
434	my $grp = aio_group $cb;	815	my $grp = aio_group $cb;
435		816
436	$maxreq = 6 if $maxreq <= 0;	817	$maxreq = 4 if $maxreq <= 0;
437		818
438	# stat once	819	# stat once
		820	aioreq_pri $pri;
439	add $grp aio_stat $path, sub {	821	add $grp aio_stat $path, sub {
440	return $grp->result () if $_[0];	822	return $grp->result () if $_[0];
441	my $now = time;	823	my $now = time;
442	my $hash1 = join ":", (stat _)[0,1,3,7,9];	824	my $hash1 = join ":", (stat _)[0,1,3,7,9];
443		825
444	# read the directory entries	826	# read the directory entries
		827	aioreq_pri $pri;
445	add $grp aio_readdir $path, sub {	828	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
446	my $entries = shift	829	my $entries = shift
447	or return $grp->result ();	830	or return $grp->result ();
448		831
449	# stat the dir another time	832	# stat the dir another time
		833	aioreq_pri $pri;
450	add $grp aio_stat $path, sub {	834	add $grp aio_stat $path, sub {
451	my $hash2 = join ":", (stat _)[0,1,3,7,9];	835	my $hash2 = join ":", (stat _)[0,1,3,7,9];
452		836
453	my $ndirs;	837	my $ndirs;
454		838
455	# take the slow route if anything looks fishy	839	# take the slow route if anything looks fishy
456	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	840	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
457	$ndirs = -1;	841	$ndirs = -1;
458	} else {	842	} else {
459	# if nlink == 2, we are finished	843	# if nlink == 2, we are finished
460	# on non-posix-fs's, we rely on nlink < 2	844	# for non-posix-fs's, we rely on nlink < 2
461	$ndirs = (stat _)[3] - 2	845	$ndirs = (stat _)[3] - 2
462	or return $grp->result ([], $entries);	846	or return $grp->result ([], $entries);
463	}	847	}
464		848
465	# sort into likely dirs and likely nondirs
466	# dirs == files without ".", short entries first
467	$entries = [map $_->[0],
468	sort { $b->[1] cmp $a->[1] }
469	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
470	@$entries];
471
472	my (@dirs, @nondirs);	849	my (@dirs, @nondirs);
473		850
474	my ($statcb, $schedcb);
475	my $nreq = 0;
476
477	my $statgrp = add $grp aio_group;	851	my $statgrp = add $grp aio_group sub {
		852	$grp->result (\@dirs, \@nondirs);
		853	};
478		854
479	$schedcb = sub {	855	limit $statgrp $maxreq;
480	if (@$entries) {	856	feed $statgrp sub {
481	if ($nreq < $maxreq) {	857	return unless @$entries;
482	my $ent = pop @$entries;	858	my $entry = shift @$entries;
		859
		860	aioreq_pri $pri;
		861	add $statgrp aio_stat "$path/$entry/.", sub {
		862	if ($_[0] < 0) {
		863	push @nondirs, $entry;
		864	} else {
		865	# need to check for real directory
		866	aioreq_pri $pri;
		867	add $statgrp aio_lstat "$path/$entry", sub {
		868	if (-d _) {
		869	push @dirs, $entry;
		870
		871	unless (--$ndirs) {
		872	push @nondirs, @$entries;
		873	feed $statgrp;
		874	}
		875	} else {
		876	push @nondirs, $entry;
		877	}
483	$nreq++;	878	}
484	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
485	}	879	}
486	} elsif (!$nreq) {
487	# finished
488	$statgrp->cancel;
489	undef $statcb;
490	undef $schedcb;
491	$grp->result (\@dirs, \@nondirs);
492	}	880	};
493	};	881	};
494	$statcb = sub {
495	my ($status, $entry) = @_;
496
497	if ($status < 0) {
498	$nreq--;
499	push @nondirs, $entry;
500	&$schedcb;
501	} else {
502	# need to check for real directory
503	add $grp aio_lstat "$path/$entry", sub {
504	$nreq--;
505
506	if (-d _) {
507	push @dirs, $entry;
508
509	if (!--$ndirs) {
510	push @nondirs, @$entries;
511	$entries = [];
512	}
513	} else {
514	push @nondirs, $entry;
515	}
516
517	&$schedcb;
518	}
519	}
520	};
521
522	&$schedcb while @$entries && $nreq < $maxreq;
523	};	882	};
524	};	883	};
525	};	884	};
526		885
527	$grp	886	$grp
528	}	887	}
529		888
		889	=item aio_rmtree $path, $callback->($status)
		890
		891	Delete a directory tree starting (and including) C<$path>, return the
		892	status of the final C<rmdir> only. This is a composite request that
		893	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		894	everything else.
		895
		896	=cut
		897
		898	sub aio_rmtree;
		899	sub aio_rmtree($;$) {
		900	my ($path, $cb) = @_;
		901
		902	my $pri = aioreq_pri;
		903	my $grp = aio_group $cb;
		904
		905	aioreq_pri $pri;
		906	add $grp aio_scandir $path, 0, sub {
		907	my ($dirs, $nondirs) = @_;
		908
		909	my $dirgrp = aio_group sub {
		910	add $grp aio_rmdir $path, sub {
		911	$grp->result ($_[0]);
		912	};
		913	};
		914
		915	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		916	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		917
		918	add $grp $dirgrp;
		919	};
		920
		921	$grp
		922	}
		923
		924	=item aio_sync $callback->($status)
		925
		926	Asynchronously call sync and call the callback when finished.
		927
530	=item aio_fsync $fh, $callback->($status)	928	=item aio_fsync $fh, $callback->($status)
531		929
532	Asynchronously call fsync on the given filehandle and call the callback	930	Asynchronously call fsync on the given filehandle and call the callback
533	with the fsync result code.	931	with the fsync result code.
534		932
…		…
538	callback with the fdatasync result code.	936	callback with the fdatasync result code.
539		937
540	If this call isn't available because your OS lacks it or it couldn't be	938	If this call isn't available because your OS lacks it or it couldn't be
541	detected, it will be emulated by calling C<fsync> instead.	939	detected, it will be emulated by calling C<fsync> instead.
542		940
		941	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		942
		943	Sync the data portion of the file specified by C<$offset> and C<$length>
		944	to disk (but NOT the metadata), by calling the Linux-specific
		945	sync_file_range call. If sync_file_range is not available or it returns
		946	ENOSYS, then fdatasync or fsync is being substituted.
		947
		948	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		949	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		950	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		951	manpage for details.
		952
		953	=item aio_pathsync $path, $callback->($status)
		954
		955	This request tries to open, fsync and close the given path. This is a
		956	composite request intended to sync directories after directory operations
		957	(E.g. rename). This might not work on all operating systems or have any
		958	specific effect, but usually it makes sure that directory changes get
		959	written to disc. It works for anything that can be opened for read-only,
		960	not just directories.
		961
		962	Future versions of this function might fall back to other methods when
		963	C<fsync> on the directory fails (such as calling C<sync>).
		964
		965	Passes C<0> when everything went ok, and C<-1> on error.
		966
		967	=cut
		968
		969	sub aio_pathsync($;$) {
		970	my ($path, $cb) = @_;
		971
		972	my $pri = aioreq_pri;
		973	my $grp = aio_group $cb;
		974
		975	aioreq_pri $pri;
		976	add $grp aio_open $path, O_RDONLY, 0, sub {
		977	my ($fh) = @_;
		978	if ($fh) {
		979	aioreq_pri $pri;
		980	add $grp aio_fsync $fh, sub {
		981	$grp->result ($_[0]);
		982
		983	aioreq_pri $pri;
		984	add $grp aio_close $fh;
		985	};
		986	} else {
		987	$grp->result (-1);
		988	}
		989	};
		990
		991	$grp
		992	}
		993
543	=item aio_group $callback->(...)	994	=item aio_group $callback->(...)
544
545	[EXPERIMENTAL]
546		995
547	This is a very special aio request: Instead of doing something, it is a	996	This is a very special aio request: Instead of doing something, it is a
548	container for other aio requests, which is useful if you want to bundle	997	container for other aio requests, which is useful if you want to bundle
549	many requests into a single, composite, request with a definite callback	998	many requests into a single, composite, request with a definite callback
550	and the ability to cancel the whole request with its subrequests.	999	and the ability to cancel the whole request with its subrequests.
…		…
591	=head2 IO::AIO::REQ CLASS	1040	=head2 IO::AIO::REQ CLASS
592		1041
593	All non-aggregate C<aio_*> functions return an object of this class when	1042	All non-aggregate C<aio_*> functions return an object of this class when
594	called in non-void context.	1043	called in non-void context.
595		1044
596	A request always moves through the following five states in its lifetime,
597	in order: B<ready> (request has been created, but has not been executed
598	yet), B<execute> (request is currently being executed), B<pending>
599	(request has been executed but callback has not been called yet),
600	B<result> (results are being processed synchronously, includes calling the
601	callback) and B<done> (request has reached the end of its lifetime and
602	holds no resources anymore).
603
604	=over 4	1045	=over 4
605		1046
606	=item cancel $req	1047	=item cancel $req
607		1048
608	Cancels the request, if possible. Has the effect of skipping execution	1049	Cancels the request, if possible. Has the effect of skipping execution
609	when entering the B<execute> state and skipping calling the callback when	1050	when entering the B<execute> state and skipping calling the callback when
610	entering the the B<result> state, but will leave the request otherwise	1051	entering the the B<result> state, but will leave the request otherwise
611	untouched. That means that requests that currently execute will not be	1052	untouched (with the exception of readdir). That means that requests that
612	stopped and resources held by the request will not be freed prematurely.	1053	currently execute will not be stopped and resources held by the request
		1054	will not be freed prematurely.
613		1055
614	=item cb $req $callback->(...)	1056	=item cb $req $callback->(...)
615		1057
616	Replace (or simply set) the callback registered to the request.	1058	Replace (or simply set) the callback registered to the request.
617		1059
…		…
661	=item * They can also can also be added to other IO::AIO::GRP objects.	1103	=item * They can also can also be added to other IO::AIO::GRP objects.
662		1104
663	=item * You must not add requests to a group from within the group callback (or	1105	=item * You must not add requests to a group from within the group callback (or
664	any later time).	1106	any later time).
665		1107
666	=item * This does not harmonise well with C<max_outstanding>, so best do
667	not combine C<aio_group> with it. Groups and feeders are recommended for
668	this kind of concurrency-limiting.
669
670	=back	1108	=back
671		1109
672	Their lifetime, simplified, looks like this: when they are empty, they	1110	Their lifetime, simplified, looks like this: when they are empty, they
673	will finish very quickly. If they contain only requests that are in the	1111	will finish very quickly. If they contain only requests that are in the
674	C<done> state, they will also finish. Otherwise they will continue to	1112	C<done> state, they will also finish. Otherwise they will continue to
675	exist.	1113	exist.
676		1114
677	That means after creating a group you have some time to add requests. And	1115	That means after creating a group you have some time to add requests
678	in the callbacks of those requests, you can add further requests to the	1116	(precisely before the callback has been invoked, which is only done within
679	group. And only when all those requests have finished will the the group	1117	the C<poll_cb>). And in the callbacks of those requests, you can add
680	itself finish.	1118	further requests to the group. And only when all those requests have
		1119	finished will the the group itself finish.
681		1120
682	=over 4	1121	=over 4
683		1122
684	=item add $grp ...	1123	=item add $grp ...
685		1124
…		…
689	be added, including other groups, as long as you do not create circular	1128	be added, including other groups, as long as you do not create circular
690	dependencies.	1129	dependencies.
691		1130
692	Returns all its arguments.	1131	Returns all its arguments.
693		1132
		1133	=item $grp->cancel_subs
		1134
		1135	Cancel all subrequests and clears any feeder, but not the group request
		1136	itself. Useful when you queued a lot of events but got a result early.
		1137
694	=item $grp->result (...)	1138	=item $grp->result (...)
695		1139
696	Set the result value(s) that will be passed to the group callback when all	1140	Set the result value(s) that will be passed to the group callback when all
697	subrequests have finished. By default, no argument will be passed.	1141	subrequests have finished and set the groups errno to the current value
		1142	of errno (just like calling C<errno> without an error number). By default,
		1143	no argument will be passed and errno is zero.
		1144
		1145	=item $grp->errno ([$errno])
		1146
		1147	Sets the group errno value to C<$errno>, or the current value of errno
		1148	when the argument is missing.
		1149
		1150	Every aio request has an associated errno value that is restored when
		1151	the callback is invoked. This method lets you change this value from its
		1152	default (0).
		1153
		1154	Calling C<result> will also set errno, so make sure you either set C<$!>
		1155	before the call to C<result>, or call c<errno> after it.
698		1156
699	=item feed $grp $callback->($grp)	1157	=item feed $grp $callback->($grp)
700
701	[VERY EXPERIMENTAL]
702		1158
703	Sets a feeder/generator on this group: every group can have an attached	1159	Sets a feeder/generator on this group: every group can have an attached
704	generator that generates requests if idle. The idea behind this is that,	1160	generator that generates requests if idle. The idea behind this is that,
705	although you could just queue as many requests as you want in a group,	1161	although you could just queue as many requests as you want in a group,
706	this might starve other requests for a potentially long time. For	1162	this might starve other requests for a potentially long time. For example,
707	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1163	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
708	requests, delaying any later requests for a long time.	1164	delaying any later requests for a long time.
709		1165
710	To avoid this, and allow incremental generation of requests, you can	1166	To avoid this, and allow incremental generation of requests, you can
711	instead a group and set a feeder on it that generates those requests. The	1167	instead a group and set a feeder on it that generates those requests. The
712	feed callback will be called whenever there are few enough (see C<limit>,	1168	feed callback will be called whenever there are few enough (see C<limit>,
713	below) requests active in the group itself and is expected to queue more	1169	below) requests active in the group itself and is expected to queue more
…		…
717	not impose any limits).	1173	not impose any limits).
718		1174
719	If the feed does not queue more requests when called, it will be	1175	If the feed does not queue more requests when called, it will be
720	automatically removed from the group.	1176	automatically removed from the group.
721		1177
722	If the feed limit is C<0>, it will be set to C<2> automatically.	1178	If the feed limit is C<0> when this method is called, it will be set to
		1179	C<2> automatically.
723		1180
724	Example:	1181	Example:
725		1182
726	# stat all files in @files, but only ever use four aio requests concurrently:	1183	# stat all files in @files, but only ever use four aio requests concurrently:
727		1184
…		…
739	Sets the feeder limit for the group: The feeder will be called whenever	1196	Sets the feeder limit for the group: The feeder will be called whenever
740	the group contains less than this many requests.	1197	the group contains less than this many requests.
741		1198
742	Setting the limit to C<0> will pause the feeding process.	1199	Setting the limit to C<0> will pause the feeding process.
743		1200
		1201	The default value for the limit is C<0>, but note that setting a feeder
		1202	automatically bumps it up to C<2>.
		1203
744	=back	1204	=back
745		1205
746	=head2 SUPPORT FUNCTIONS	1206	=head2 SUPPORT FUNCTIONS
747		1207
		1208	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1209
748	=over 4	1210	=over 4
749		1211
750	=item $fileno = IO::AIO::poll_fileno	1212	=item $fileno = IO::AIO::poll_fileno
751		1213
752	Return the I<request result pipe file descriptor>. This filehandle must be	1214	Return the I<request result pipe file descriptor>. This filehandle must be
753	polled for reading by some mechanism outside this module (e.g. Event or	1215	polled for reading by some mechanism outside this module (e.g. EV, Glib,
754	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1216	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
755	to call C<poll_cb> to check the results.	1217	you have to call C<poll_cb> to check the results.
756		1218
757	See C<poll_cb> for an example.	1219	See C<poll_cb> for an example.
758		1220
759	=item IO::AIO::poll_cb	1221	=item IO::AIO::poll_cb
760		1222
761	Process all outstanding events on the result pipe. You have to call this	1223	Process some outstanding events on the result pipe. You have to call this
762	regularly. Returns the number of events processed. Returns immediately	1224	regularly. Returns C<0> if all events could be processed, or C<-1> if it
763	when no events are outstanding.	1225	returned earlier for whatever reason. Returns immediately when no events
		1226	are outstanding. The amount of events processed depends on the settings of
		1227	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1228
		1229	If not all requests were processed for whatever reason, the filehandle
		1230	will still be ready when C<poll_cb> returns, so normally you don't have to
		1231	do anything special to have it called later.
764		1232
765	Example: Install an Event watcher that automatically calls	1233	Example: Install an Event watcher that automatically calls
766	IO::AIO::poll_cb with high priority:	1234	IO::AIO::poll_cb with high priority (more examples can be found in the
		1235	SYNOPSIS section, at the top of this document):
767		1236
768	Event->io (fd => IO::AIO::poll_fileno,	1237	Event->io (fd => IO::AIO::poll_fileno,
769	poll => 'r', async => 1,	1238	poll => 'r', async => 1,
770	cb => \&IO::AIO::poll_cb);	1239	cb => \&IO::AIO::poll_cb);
771		1240
		1241	=item IO::AIO::max_poll_reqs $nreqs
		1242
		1243	=item IO::AIO::max_poll_time $seconds
		1244
		1245	These set the maximum number of requests (default C<0>, meaning infinity)
		1246	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1247	the maximum amount of time (default C<0>, meaning infinity) spent in
		1248	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1249	of time C<poll_cb> is allowed to use).
		1250
		1251	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1252	syscall per request processed, which is not normally a problem unless your
		1253	callbacks are really really fast or your OS is really really slow (I am
		1254	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1255
		1256	Setting these is useful if you want to ensure some level of
		1257	interactiveness when perl is not fast enough to process all requests in
		1258	time.
		1259
		1260	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1261
		1262	Example: Install an Event watcher that automatically calls
		1263	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1264	program get the CPU sometimes even under high AIO load.
		1265
		1266	# try not to spend much more than 0.1s in poll_cb
		1267	IO::AIO::max_poll_time 0.1;
		1268
		1269	# use a low priority so other tasks have priority
		1270	Event->io (fd => IO::AIO::poll_fileno,
		1271	poll => 'r', nice => 1,
		1272	cb => &IO::AIO::poll_cb);
		1273
772	=item IO::AIO::poll_wait	1274	=item IO::AIO::poll_wait
773		1275
		1276	If there are any outstanding requests and none of them in the result
774	Wait till the result filehandle becomes ready for reading (simply does a	1277	phase, wait till the result filehandle becomes ready for reading (simply
775	C<select> on the filehandle. This is useful if you want to synchronously wait	1278	does a C<select> on the filehandle. This is useful if you want to
776	for some requests to finish).	1279	synchronously wait for some requests to finish).
777		1280
778	See C<nreqs> for an example.	1281	See C<nreqs> for an example.
779		1282
		1283	=item IO::AIO::poll
		1284
		1285	Waits until some requests have been handled.
		1286
		1287	Returns the number of requests processed, but is otherwise strictly
		1288	equivalent to:
		1289
		1290	IO::AIO::poll_wait, IO::AIO::poll_cb
		1291
780	=item IO::AIO::nreqs	1292	=item IO::AIO::flush
781		1293
782	Returns the number of requests currently outstanding (i.e. for which their	1294	Wait till all outstanding AIO requests have been handled.
783	callback has not been invoked yet).
784		1295
785	Example: wait till there are no outstanding requests anymore:	1296	Strictly equivalent to:
786		1297
787	IO::AIO::poll_wait, IO::AIO::poll_cb	1298	IO::AIO::poll_wait, IO::AIO::poll_cb
788	while IO::AIO::nreqs;	1299	while IO::AIO::nreqs;
789		1300
790	=item IO::AIO::flush	1301	=back
791		1302
792	Wait till all outstanding AIO requests have been handled.	1303	=head3 CONTROLLING THE NUMBER OF THREADS
793		1304
794	Strictly equivalent to:	1305	=over
795
796	IO::AIO::poll_wait, IO::AIO::poll_cb
797	while IO::AIO::nreqs;
798
799	=item IO::AIO::poll
800
801	Waits until some requests have been handled.
802
803	Strictly equivalent to:
804
805	IO::AIO::poll_wait, IO::AIO::poll_cb
806	if IO::AIO::nreqs;
807		1306
808	=item IO::AIO::min_parallel $nthreads	1307	=item IO::AIO::min_parallel $nthreads
809		1308
810	Set the minimum number of AIO threads to C<$nthreads>. The current	1309	Set the minimum number of AIO threads to C<$nthreads>. The current
811	default is C<8>, which means eight asynchronous operations can execute	1310	default is C<8>, which means eight asynchronous operations can execute
812	concurrently at any one time (the number of outstanding requests,	1311	concurrently at any one time (the number of outstanding requests,
813	however, is unlimited).	1312	however, is unlimited).
814		1313
815	IO::AIO starts threads only on demand, when an AIO request is queued and	1314	IO::AIO starts threads only on demand, when an AIO request is queued and
816	no free thread exists.	1315	no free thread exists. Please note that queueing up a hundred requests can
		1316	create demand for a hundred threads, even if it turns out that everything
		1317	is in the cache and could have been processed faster by a single thread.
817		1318
818	It is recommended to keep the number of threads relatively low, as some	1319	It is recommended to keep the number of threads relatively low, as some
819	Linux kernel versions will scale negatively with the number of threads	1320	Linux kernel versions will scale negatively with the number of threads
820	(higher parallelity => MUCH higher latency). With current Linux 2.6	1321	(higher parallelity => MUCH higher latency). With current Linux 2.6
821	versions, 4-32 threads should be fine.	1322	versions, 4-32 threads should be fine.
…		…
835	This module automatically runs C<max_parallel 0> at program end, to ensure	1336	This module automatically runs C<max_parallel 0> at program end, to ensure
836	that all threads are killed and that there are no outstanding requests.	1337	that all threads are killed and that there are no outstanding requests.
837		1338
838	Under normal circumstances you don't need to call this function.	1339	Under normal circumstances you don't need to call this function.
839		1340
		1341	=item IO::AIO::max_idle $nthreads
		1342
		1343	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1344	threads that did not get a request to process within 10 seconds). That
		1345	means if a thread becomes idle while C<$nthreads> other threads are also
		1346	idle, it will free its resources and exit.
		1347
		1348	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1349	to allow for extremely high load situations, but want to free resources
		1350	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1351
		1352	The default is probably ok in most situations, especially if thread
		1353	creation is fast. If thread creation is very slow on your system you might
		1354	want to use larger values.
		1355
840	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1356	=item IO::AIO::max_outstanding $maxreqs
841		1357
842	[DEPRECATED]	1358	This is a very bad function to use in interactive programs because it
		1359	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1360	use an C<aio_group> together with a feed callback.
843		1361
844	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1362	Sets the maximum number of outstanding requests to C<$nreqs>. If you
845	try to queue up more than this number of requests, the caller will block until	1363	do queue up more than this number of requests, the next call to the
846	some requests have been handled.	1364	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1365	function will block until the limit is no longer exceeded.
847		1366
848	The default is very large, so normally there is no practical limit. If you	1367	The default value is very large, so there is no practical limit on the
849	queue up many requests in a loop it often improves speed if you set	1368	number of outstanding requests.
850	this to a relatively low number, such as C<100>.
851		1369
852	This function does not work well together with C<aio_group>'s, and their	1370	You can still queue as many requests as you want. Therefore,
853	feeder interface is better suited to limiting concurrency, so do not use	1371	C<max_outstanding> is mainly useful in simple scripts (with low values) or
854	this function.	1372	as a stop gap to shield against fatal memory overflow (with large values).
855
856	Under normal circumstances you don't need to call this function.
857		1373
858	=back	1374	=back
859		1375
		1376	=head3 STATISTICAL INFORMATION
		1377
		1378	=over
		1379
		1380	=item IO::AIO::nreqs
		1381
		1382	Returns the number of requests currently in the ready, execute or pending
		1383	states (i.e. for which their callback has not been invoked yet).
		1384
		1385	Example: wait till there are no outstanding requests anymore:
		1386
		1387	IO::AIO::poll_wait, IO::AIO::poll_cb
		1388	while IO::AIO::nreqs;
		1389
		1390	=item IO::AIO::nready
		1391
		1392	Returns the number of requests currently in the ready state (not yet
		1393	executed).
		1394
		1395	=item IO::AIO::npending
		1396
		1397	Returns the number of requests currently in the pending state (executed,
		1398	but not yet processed by poll_cb).
		1399
		1400	=back
		1401
		1402	=head3 MISCELLANEOUS FUNCTIONS
		1403
		1404	IO::AIO implements some functions that might be useful, but are not
		1405	asynchronous.
		1406
		1407	=over 4
		1408
		1409	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1410
		1411	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1412	but is blocking (this makes most sense if you know the input data is
		1413	likely cached already and the output filehandle is set to non-blocking
		1414	operations).
		1415
		1416	Returns the number of bytes copied, or C<-1> on error.
		1417
		1418	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1419
		1420	Simply calls the C<posix_fadvise> function (see it's
		1421	manpage for details). The following advice constants are
		1422	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1423	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1424	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1425
		1426	On systems that do not implement C<posix_fadvise>, this function returns
		1427	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1428
		1429	=back
		1430
860	=cut	1431	=cut
861		1432
862	# support function to convert a fd into a perl filehandle
863	sub _fd2fh {
864	return undef if $_[0] < 0;
865
866	# try to generate nice filehandles
867	my $sym = "IO::AIO::fd#$_[0]";
868	local *$sym;
869
870	open *$sym, "+<&=$_[0]" # usually works under any unix
871	or open *$sym, "<&=$_[0]" # cygwin needs this
872	or open *$sym, ">&=$_[0]" # or this
873	or return undef;
874
875	*$sym
876	}
877
878	min_parallel 8;	1433	min_parallel 8;
879		1434
880	END {	1435	END { flush }
881	max_parallel 0;
882	}
883		1436
884	1;	1437	1;
885		1438
886	=head2 FORK BEHAVIOUR	1439	=head2 FORK BEHAVIOUR
887		1440
888	This module should do "the right thing" when the process using it forks:	1441	This module should do "the right thing" when the process using it forks:
889		1442
890	Before the fork, IO::AIO enters a quiescent state where no requests	1443	Before the fork, IO::AIO enters a quiescent state where no requests
891	can be added in other threads and no results will be processed. After	1444	can be added in other threads and no results will be processed. After
892	the fork the parent simply leaves the quiescent state and continues	1445	the fork the parent simply leaves the quiescent state and continues
893	request/result processing, while the child clears the request/result	1446	request/result processing, while the child frees the request/result queue
894	queue (so the requests started before the fork will only be handled in	1447	(so that the requests started before the fork will only be handled in the
895	the parent). Threads will be started on demand until the limit ste in the	1448	parent). Threads will be started on demand until the limit set in the
896	parent process has been reached again.	1449	parent process has been reached again.
897		1450
898	In short: the parent will, after a short pause, continue as if fork had	1451	In short: the parent will, after a short pause, continue as if fork had
899	not been called, while the child will act as if IO::AIO has not been used	1452	not been called, while the child will act as if IO::AIO has not been used
900	yet.	1453	yet.
901		1454
902	=head2 MEMORY USAGE	1455	=head2 MEMORY USAGE
903		1456
		1457	Per-request usage:
		1458
904	Each aio request uses - depending on your architecture - around 128 bytes	1459	Each aio request uses - depending on your architecture - around 100-200
905	of memory. In addition, stat requests need a stat buffer (possibly a few	1460	bytes of memory. In addition, stat requests need a stat buffer (possibly
906	hundred bytes). Perl scalars and other data passed into aio requests will	1461	a few hundred bytes), readdir requires a result buffer and so on. Perl
907	also be locked.	1462	scalars and other data passed into aio requests will also be locked and
		1463	will consume memory till the request has entered the done state.
908		1464
909	This is now awfully much, so queuing lots of requests is not usually a	1465	This is not awfully much, so queuing lots of requests is not usually a
910	problem.	1466	problem.
911		1467
912	Each thread needs a stack area which is usually around 16k, sometimes much	1468	Per-thread usage:
913	larger, depending on the OS.	1469
		1470	In the execution phase, some aio requests require more memory for
		1471	temporary buffers, and each thread requires a stack and other data
		1472	structures (usually around 16k-128k, depending on the OS).
		1473
		1474	=head1 KNOWN BUGS
		1475
		1476	Known bugs will be fixed in the next release.
914		1477
915	=head1 SEE ALSO	1478	=head1 SEE ALSO
916		1479
917	L<Coro::AIO>.	1480	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1481	more natural syntax.
918		1482
919	=head1 AUTHOR	1483	=head1 AUTHOR
920		1484
921	Marc Lehmann <schmorp@schmorp.de>	1485	Marc Lehmann <schmorp@schmorp.de>
922	http://home.schmorp.de/	1486	http://home.schmorp.de/

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines