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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs.
Revision 1.109 by root, Sun Jun 3 09:44:17 2007 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
16	aio_read $fh, 30000, 1024, $buffer, 0, sub {	17	aio_read $fh, 30000, 1024, $buffer, 0, sub {
17	$_[0] > 0 or die "read error: $!";	18	$_[0] > 0 or die "read error: $!";
18	};	19	};
19		20
20	use IO::AIO 2; # version has aio objects	21	# version 2+ has request and group objects
		22	use IO::AIO 2;
21		23
		24	aioreq_pri 4; # give next request a very high priority
22	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
23	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
24		27
25	# AnyEvent	28	my $grp = aio_group sub { print "all stats done\n" };
		29	add $grp aio_stat "..." for ...;
		30
		31	# AnyEvent integration
26	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	32	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
27	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });	33	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
28		34
29	# Event	35	# Event integration
30	Event->io (fd => IO::AIO::poll_fileno,	36	Event->io (fd => IO::AIO::poll_fileno,
31	poll => 'r',	37	poll => 'r',
32	cb => \&IO::AIO::poll_cb);	38	cb => \&IO::AIO::poll_cb);
33		39
34	# Glib/Gtk2	40	# Glib/Gtk2 integration
35	add_watch Glib::IO IO::AIO::poll_fileno,	41	add_watch Glib::IO IO::AIO::poll_fileno,
36	in => sub { IO::AIO::poll_cb; 1 };	42	in => sub { IO::AIO::poll_cb; 1 };
37		43
38	# Tk	44	# Tk integration
39	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",	45	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
40	readable => \&IO::AIO::poll_cb);	46	readable => \&IO::AIO::poll_cb);
41		47
42	# Danga::Socket	48	# Danga::Socket integration
43	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	49	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
44	\&IO::AIO::poll_cb);	50	\&IO::AIO::poll_cb);
45		51
46
47	=head1 DESCRIPTION	52	=head1 DESCRIPTION
48		53
49	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
50	operating system supports.	55	operating system supports.
51		56
		57	Asynchronous means that operations that can normally block your program
		58	(e.g. reading from disk) will be done asynchronously: the operation
		59	will still block, but you can do something else in the meantime. This
		60	is extremely useful for programs that need to stay interactive even
		61	when doing heavy I/O (GUI programs, high performance network servers
		62	etc.), but can also be used to easily do operations in parallel that are
		63	normally done sequentially, e.g. stat'ing many files, which is much faster
		64	on a RAID volume or over NFS when you do a number of stat operations
		65	concurrently.
		66
		67	While most of this works on all types of file descriptors (for
		68	example sockets), using these functions on file descriptors that
		69	support nonblocking operation (again, sockets, pipes etc.) is very
		70	inefficient. Use an event loop for that (such as the L<Event\|Event>
		71	module): IO::AIO will naturally fit into such an event loop itself.
		72
52	Currently, a number of threads are started that execute your read/writes	73	In this version, a number of threads are started that execute your
53	and signal their completion. You don't need thread support in your libc or	74	requests and signal their completion. You don't need thread support
54	perl, and the threads created by this module will not be visible to the	75	in perl, and the threads created by this module will not be visible
55	pthreads library. In the future, this module might make use of the native	76	to perl. In the future, this module might make use of the native aio
56	aio functions available on many operating systems. However, they are often	77	functions available on many operating systems. However, they are often
57	not well-supported (Linux doesn't allow them on normal files currently,	78	not well-supported or restricted (GNU/Linux doesn't allow them on normal
58	for example), and they would only support aio_read and aio_write, so the	79	files currently, for example), and they would only support aio_read and
59	remaining functionality would have to be implemented using threads anyway.	80	aio_write, so the remaining functionality would have to be implemented
		81	using threads anyway.
60		82
61	Although the module will work with in the presence of other threads, it is	83	Although the module will work in the presence of other (Perl-) threads,
62	currently not reentrant, so use appropriate locking yourself, always call	84	it is currently not reentrant in any way, so use appropriate locking
63	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	85	yourself, always call C<poll_cb> from within the same thread, or never
64	C<aio_> functions) recursively.	86	call C<poll_cb> (or other C<aio_> functions) recursively.
		87
		88	=head2 EXAMPLE
		89
		90	This is a simple example that uses the Event module and loads
		91	F</etc/passwd> asynchronously:
		92
		93	use Fcntl;
		94	use Event;
		95	use IO::AIO;
		96
		97	# register the IO::AIO callback with Event
		98	Event->io (fd => IO::AIO::poll_fileno,
		99	poll => 'r',
		100	cb => \&IO::AIO::poll_cb);
		101
		102	# queue the request to open /etc/passwd
		103	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		104	my $fh = shift
		105	or die "error while opening: $!";
		106
		107	# stat'ing filehandles is generally non-blocking
		108	my $size = -s $fh;
		109
		110	# queue a request to read the file
		111	my $contents;
		112	aio_read $fh, 0, $size, $contents, 0, sub {
		113	$_[0] == $size
		114	or die "short read: $!";
		115
		116	close $fh;
		117
		118	# file contents now in $contents
		119	print $contents;
		120
		121	# exit event loop and program
		122	Event::unloop;
		123	};
		124	};
		125
		126	# possibly queue up other requests, or open GUI windows,
		127	# check for sockets etc. etc.
		128
		129	# process events as long as there are some:
		130	Event::loop;
		131
		132	=head1 REQUEST ANATOMY AND LIFETIME
		133
		134	Every C<aio_*> function creates a request. which is a C data structure not
		135	directly visible to Perl.
		136
		137	If called in non-void context, every request function returns a Perl
		138	object representing the request. In void context, nothing is returned,
		139	which saves a bit of memory.
		140
		141	The perl object is a fairly standard ref-to-hash object. The hash contents
		142	are not used by IO::AIO so you are free to store anything you like in it.
		143
		144	During their existance, aio requests travel through the following states,
		145	in order:
		146
		147	=over 4
		148
		149	=item ready
		150
		151	Immediately after a request is created it is put into the ready state,
		152	waiting for a thread to execute it.
		153
		154	=item execute
		155
		156	A thread has accepted the request for processing and is currently
		157	executing it (e.g. blocking in read).
		158
		159	=item pending
		160
		161	The request has been executed and is waiting for result processing.
		162
		163	While request submission and execution is fully asynchronous, result
		164	processing is not and relies on the perl interpreter calling C<poll_cb>
		165	(or another function with the same effect).
		166
		167	=item result
		168
		169	The request results are processed synchronously by C<poll_cb>.
		170
		171	The C<poll_cb> function will process all outstanding aio requests by
		172	calling their callbacks, freeing memory associated with them and managing
		173	any groups they are contained in.
		174
		175	=item done
		176
		177	Request has reached the end of its lifetime and holds no resources anymore
		178	(except possibly for the Perl object, but its connection to the actual
		179	aio request is severed and calling its methods will either do nothing or
		180	result in a runtime error).
		181
		182	=back
65		183
66	=cut	184	=cut
67		185
68	package IO::AIO;	186	package IO::AIO;
69		187
…		…
71	use strict 'vars';	189	use strict 'vars';
72		190
73	use base 'Exporter';	191	use base 'Exporter';
74		192
75	BEGIN {	193	BEGIN {
76	our $VERSION = '2.0';	194	our $VERSION = '2.4';
77		195
78	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	196	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
79	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	197	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
80	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	198	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
81	aio_group);	199	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
82	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	200	aio_chown aio_chmod aio_utime);
		201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
		202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		203	min_parallel max_parallel max_idle
		204	nreqs nready npending nthreads
		205	max_poll_time max_poll_reqs);
83		206
84	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
85		208
86	require XSLoader;	209	require XSLoader;
87	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
88	}	211	}
89		212
90	=head1 FUNCTIONS	213	=head1 FUNCTIONS
91		214
92	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
93		216
94	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
95	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
96	and they all accept an additional (and optional) C<$callback> argument	219	and they all accept an additional (and optional) C<$callback> argument
97	which must be a code reference. This code reference will get called with	220	which must be a code reference. This code reference will get called with
…		…
100	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
101		224
102	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
103	internally until the request has finished.	226	internally until the request has finished.
104		227
105	All requests return objects of type L<IO::AIO::REQ> that allow further	228	All functions return request objects of type L<IO::AIO::REQ> that allow
106	manipulation of those requests while they are in-flight.	229	further manipulation of those requests while they are in-flight.
107		230
108	The pathnames you pass to these routines I<must> be absolute and	231	The pathnames you pass to these routines I<must> be absolute and
109	encoded in byte form. The reason for the former is that at the time the	232	encoded as octets. The reason for the former is that at the time the
110	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
111	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
112	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
113		237
114	To encode pathnames to byte form, either make sure you either: a)	238	To encode pathnames as octets, either make sure you either: a) always pass
115	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
116	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	240	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
117	your pathnames to the locale (or other) encoding in effect in the user	241	your pathnames to the locale (or other) encoding in effect in the user
118	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
119	use something else.	243	use something else to ensure your scalar has the correct contents.
		244
		245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		246	handles correctly wether it is set or not.
120		247
121	=over 4	248	=over 4
		249
		250	=item $prev_pri = aioreq_pri [$pri]
		251
		252	Returns the priority value that would be used for the next request and, if
		253	C<$pri> is given, sets the priority for the next aio request.
		254
		255	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		256	and C<4>, respectively. Requests with higher priority will be serviced
		257	first.
		258
		259	The priority will be reset to C<0> after each call to one of the C<aio_*>
		260	functions.
		261
		262	Example: open a file with low priority, then read something from it with
		263	higher priority so the read request is serviced before other low priority
		264	open requests (potentially spamming the cache):
		265
		266	aioreq_pri -3;
		267	aio_open ..., sub {
		268	return unless $_[0];
		269
		270	aioreq_pri -2;
		271	aio_read $_[0], ..., sub {
		272	...
		273	};
		274	};
		275
		276
		277	=item aioreq_nice $pri_adjust
		278
		279	Similar to C<aioreq_pri>, but subtracts the given value from the current
		280	priority, so the effect is cumulative.
		281
122		282
123	=item aio_open $pathname, $flags, $mode, $callback->($fh)	283	=item aio_open $pathname, $flags, $mode, $callback->($fh)
124		284
125	Asynchronously open or create a file and call the callback with a newly	285	Asynchronously open or create a file and call the callback with a newly
126	created filehandle for the file.	286	created filehandle for the file.
…		…
132	list. They are the same as used by C<sysopen>.	292	list. They are the same as used by C<sysopen>.
133		293
134	Likewise, C<$mode> specifies the mode of the newly created file, if it	294	Likewise, C<$mode> specifies the mode of the newly created file, if it
135	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	295	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
136	except that it is mandatory (i.e. use C<0> if you don't create new files,	296	except that it is mandatory (i.e. use C<0> if you don't create new files,
137	and C<0666> or C<0777> if you do).	297	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		298	by the umask in effect then the request is being executed, so better never
		299	change the umask.
138		300
139	Example:	301	Example:
140		302
141	aio_open "/etc/passwd", O_RDONLY, 0, sub {	303	aio_open "/etc/passwd", O_RDONLY, 0, sub {
142	if ($_[0]) {	304	if ($_[0]) {
…		…
145	} else {	307	} else {
146	die "open failed: $!\n";	308	die "open failed: $!\n";
147	}	309	}
148	};	310	};
149		311
		312
150	=item aio_close $fh, $callback->($status)	313	=item aio_close $fh, $callback->($status)
151		314
152	Asynchronously close a file and call the callback with the result	315	Asynchronously close a file and call the callback with the result
153	code. I<WARNING:> although accepted, you should not pass in a perl	316	code. I<WARNING:> although accepted, you should not pass in a perl
154	filehandle here, as perl will likely close the file descriptor another	317	filehandle here, as perl will likely close the file descriptor another
…		…
156	C<close> or just let filehandles go out of scope.	319	C<close> or just let filehandles go out of scope.
157		320
158	This is supposed to be a bug in the API, so that might change. It's	321	This is supposed to be a bug in the API, so that might change. It's
159	therefore best to avoid this function.	322	therefore best to avoid this function.
160		323
		324
161	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	325	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
162		326
163	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	327	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
164		328
165	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	329	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
166	into the scalar given by C<data> and offset C<dataoffset> and calls the	330	into the scalar given by C<$data> and offset C<$dataoffset> and calls the
167	callback without the actual number of bytes read (or -1 on error, just	331	callback without the actual number of bytes read (or -1 on error, just
168	like the syscall).	332	like the syscall).
169		333
		334	If C<$offset> is undefined, then the current file offset will be used (and
		335	updated), otherwise the file offset will not be changed by these calls.
		336
		337	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
		338
		339	If C<$dataoffset> is less than zero, it will be counted from the end of
		340	C<$data>.
		341
170	The C<$data> scalar I<MUST NOT> be modified in any way while the request	342	The C<$data> scalar I<MUST NOT> be modified in any way while the request
171	is outstanding. Modifying it can result in segfaults or WW3 (if the	343	is outstanding. Modifying it can result in segfaults or World War III (if
172	necessary/optional hardware is installed).	344	the necessary/optional hardware is installed).
173		345
174	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	346	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
175	offset C<0> within the scalar:	347	offset C<0> within the scalar:
176		348
177	aio_read $fh, 7, 15, $buffer, 0, sub {	349	aio_read $fh, 7, 15, $buffer, 0, sub {
178	$_[0] > 0 or die "read error: $!";	350	$_[0] > 0 or die "read error: $!";
179	print "read $_[0] bytes: <$buffer>\n";	351	print "read $_[0] bytes: <$buffer>\n";
180	};	352	};
181		353
182	=item aio_move $srcpath, $dstpath, $callback->($status)
183
184	Try to move the I<file> (directories not supported as either source or
185	destination) from C<$srcpath> to C<$dstpath> and call the callback with
186	the C<0> (error) or C<-1> ok.
187
188	This is a composite request that tries to rename(2) the file first. If
189	rename files with C<EXDEV>, it creates the destination file with mode 0200
190	and copies the contents of the source file into it using C<aio_sendfile>,
191	followed by restoring atime, mtime, access mode and uid/gid, in that
192	order, and unlinking the C<$srcpath>.
193
194	If an error occurs, the partial destination file will be unlinked, if
195	possible, except when setting atime, mtime, access mode and uid/gid, where
196	errors are being ignored.
197
198	=cut
199
200	sub aio_move($$$) {
201	my ($src, $dst, $cb) = @_;
202
203	my $grp = aio_group;
204
205	add $grp aio_rename $src, $dst, sub {
206	if ($_[0] && $! == EXDEV) {
207	add $grp aio_open $src, O_RDONLY, 0, sub {
208	if (my $src_fh = $_[0]) {
209	my @stat = stat $src_fh;
210
211	add $grp aio_open $dst, O_WRONLY, 0200, sub {
212	if (my $dst_fh = $_[0]) {
213	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
214	close $src_fh;
215
216	if ($_[0] == $stat[7]) {
217	utime $stat[8], $stat[9], $dst;
218	chmod $stat[2] & 07777, $dst_fh;
219	chown $stat[4], $stat[5], $dst_fh;
220	close $dst_fh;
221
222	add $grp aio_unlink $src, sub {
223	$cb->($_[0]);
224	};
225	} else {
226	my $errno = $!;
227	add $grp aio_unlink $dst, sub {
228	$! = $errno;
229	$cb->(-1);
230	};
231	}
232	};
233	} else {
234	$cb->(-1);
235	}
236	},
237
238	} else {
239	$cb->(-1);
240	}
241	};
242	} else {
243	$cb->($_[0]);
244	}
245	};
246
247	$grp
248	}
249		354
250	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	355	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
251		356
252	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	357	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
253	reading at byte offset C<$in_offset>, and starts writing at the current	358	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
267	C<$in_fh> than are written, and there is no way to find out how many	372	C<$in_fh> than are written, and there is no way to find out how many
268	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	373	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
269	provides the number of bytes written to C<$out_fh>. Only if the result	374	provides the number of bytes written to C<$out_fh>. Only if the result
270	value equals C<$length> one can assume that C<$length> bytes have been	375	value equals C<$length> one can assume that C<$length> bytes have been
271	read.	376	read.
		377
272		378
273	=item aio_readahead $fh,$offset,$length, $callback->($retval)	379	=item aio_readahead $fh,$offset,$length, $callback->($retval)
274		380
275	C<aio_readahead> populates the page cache with data from a file so that	381	C<aio_readahead> populates the page cache with data from a file so that
276	subsequent reads from that file will not block on disk I/O. The C<$offset>	382	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
282	file. The current file offset of the file is left unchanged.	388	file. The current file offset of the file is left unchanged.
283		389
284	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	390	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
285	emulated by simply reading the data, which would have a similar effect.	391	emulated by simply reading the data, which would have a similar effect.
286		392
		393
287	=item aio_stat $fh_or_path, $callback->($status)	394	=item aio_stat $fh_or_path, $callback->($status)
288		395
289	=item aio_lstat $fh, $callback->($status)	396	=item aio_lstat $fh, $callback->($status)
290		397
291	Works like perl's C<stat> or C<lstat> in void context. The callback will	398	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
304	aio_stat "/etc/passwd", sub {	411	aio_stat "/etc/passwd", sub {
305	$_[0] and die "stat failed: $!";	412	$_[0] and die "stat failed: $!";
306	print "size is ", -s _, "\n";	413	print "size is ", -s _, "\n";
307	};	414	};
308		415
		416
		417	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		418
		419	Works like perl's C<utime> function (including the special case of $atime
		420	and $mtime being undef). Fractional times are supported if the underlying
		421	syscalls support them.
		422
		423	When called with a pathname, uses utimes(2) if available, otherwise
		424	utime(2). If called on a file descriptor, uses futimes(2) if available,
		425	otherwise returns ENOSYS, so this is not portable.
		426
		427	Examples:
		428
		429	# set atime and mtime to current time (basically touch(1)):
		430	aio_utime "path", undef, undef;
		431	# set atime to current time and mtime to beginning of the epoch:
		432	aio_utime "path", time, undef; # undef==0
		433
		434
		435	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		436
		437	Works like perl's C<chown> function, except that C<undef> for either $uid
		438	or $gid is being interpreted as "do not change" (but -1 can also be used).
		439
		440	Examples:
		441
		442	# same as "chown root path" in the shell:
		443	aio_chown "path", 0, -1;
		444	# same as above:
		445	aio_chown "path", 0, undef;
		446
		447
		448	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		449
		450	Works like perl's C<chmod> function.
		451
		452
309	=item aio_unlink $pathname, $callback->($status)	453	=item aio_unlink $pathname, $callback->($status)
310		454
311	Asynchronously unlink (delete) a file and call the callback with the	455	Asynchronously unlink (delete) a file and call the callback with the
312	result code.	456	result code.
313		457
		458
		459	=item aio_mknod $path, $mode, $dev, $callback->($status)
		460
		461	[EXPERIMENTAL]
		462
		463	Asynchronously create a device node (or fifo). See mknod(2).
		464
		465	The only (POSIX-) portable way of calling this function is:
		466
		467	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		468
		469
314	=item aio_link $srcpath, $dstpath, $callback->($status)	470	=item aio_link $srcpath, $dstpath, $callback->($status)
315		471
316	Asynchronously create a new link to the existing object at C<$srcpath> at	472	Asynchronously create a new link to the existing object at C<$srcpath> at
317	the path C<$dstpath> and call the callback with the result code.	473	the path C<$dstpath> and call the callback with the result code.
318		474
		475
319	=item aio_symlink $srcpath, $dstpath, $callback->($status)	476	=item aio_symlink $srcpath, $dstpath, $callback->($status)
320		477
321	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	478	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
322	the path C<$dstpath> and call the callback with the result code.	479	the path C<$dstpath> and call the callback with the result code.
323		480
		481
		482	=item aio_readlink $path, $callback->($link)
		483
		484	Asynchronously read the symlink specified by C<$path> and pass it to
		485	the callback. If an error occurs, nothing or undef gets passed to the
		486	callback.
		487
		488
324	=item aio_rename $srcpath, $dstpath, $callback->($status)	489	=item aio_rename $srcpath, $dstpath, $callback->($status)
325		490
326	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	491	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
327	rename(2) and call the callback with the result code.	492	rename(2) and call the callback with the result code.
328		493
		494
		495	=item aio_mkdir $pathname, $mode, $callback->($status)
		496
		497	Asynchronously mkdir (create) a directory and call the callback with
		498	the result code. C<$mode> will be modified by the umask at the time the
		499	request is executed, so do not change your umask.
		500
		501
329	=item aio_rmdir $pathname, $callback->($status)	502	=item aio_rmdir $pathname, $callback->($status)
330		503
331	Asynchronously rmdir (delete) a directory and call the callback with the	504	Asynchronously rmdir (delete) a directory and call the callback with the
332	result code.	505	result code.
		506
333		507
334	=item aio_readdir $pathname, $callback->($entries)	508	=item aio_readdir $pathname, $callback->($entries)
335		509
336	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	510	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
337	directory (i.e. opendir + readdir + closedir). The entries will not be	511	directory (i.e. opendir + readdir + closedir). The entries will not be
338	sorted, and will B<NOT> include the C<.> and C<..> entries.	512	sorted, and will B<NOT> include the C<.> and C<..> entries.
339		513
340	The callback a single argument which is either C<undef> or an array-ref	514	The callback a single argument which is either C<undef> or an array-ref
341	with the filenames.	515	with the filenames.
342		516
		517
		518	=item aio_load $path, $data, $callback->($status)
		519
		520	This is a composite request that tries to fully load the given file into
		521	memory. Status is the same as with aio_read.
		522
		523	=cut
		524
		525	sub aio_load($$;$) {
		526	aio_block {
		527	my ($path, undef, $cb) = @_;
		528	my $data = \$_[1];
		529
		530	my $pri = aioreq_pri;
		531	my $grp = aio_group $cb;
		532
		533	aioreq_pri $pri;
		534	add $grp aio_open $path, O_RDONLY, 0, sub {
		535	my $fh = shift
		536	or return $grp->result (-1);
		537
		538	aioreq_pri $pri;
		539	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		540	$grp->result ($_[0]);
		541	};
		542	};
		543
		544	$grp
		545	}
		546	}
		547
		548	=item aio_copy $srcpath, $dstpath, $callback->($status)
		549
		550	Try to copy the I<file> (directories not supported as either source or
		551	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		552	the C<0> (error) or C<-1> ok.
		553
		554	This is a composite request that it creates the destination file with
		555	mode 0200 and copies the contents of the source file into it using
		556	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		557	uid/gid, in that order.
		558
		559	If an error occurs, the partial destination file will be unlinked, if
		560	possible, except when setting atime, mtime, access mode and uid/gid, where
		561	errors are being ignored.
		562
		563	=cut
		564
		565	sub aio_copy($$;$) {
		566	aio_block {
		567	my ($src, $dst, $cb) = @_;
		568
		569	my $pri = aioreq_pri;
		570	my $grp = aio_group $cb;
		571
		572	aioreq_pri $pri;
		573	add $grp aio_open $src, O_RDONLY, 0, sub {
		574	if (my $src_fh = $_[0]) {
		575	my @stat = stat $src_fh;
		576
		577	aioreq_pri $pri;
		578	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		579	if (my $dst_fh = $_[0]) {
		580	aioreq_pri $pri;
		581	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		582	if ($_[0] == $stat[7]) {
		583	$grp->result (0);
		584	close $src_fh;
		585
		586	# those should not normally block. should. should.
		587	utime $stat[8], $stat[9], $dst;
		588	chmod $stat[2] & 07777, $dst_fh;
		589	chown $stat[4], $stat[5], $dst_fh;
		590	close $dst_fh;
		591	} else {
		592	$grp->result (-1);
		593	close $src_fh;
		594	close $dst_fh;
		595
		596	aioreq $pri;
		597	add $grp aio_unlink $dst;
		598	}
		599	};
		600	} else {
		601	$grp->result (-1);
		602	}
		603	},
		604
		605	} else {
		606	$grp->result (-1);
		607	}
		608	};
		609
		610	$grp
		611	}
		612	}
		613
		614	=item aio_move $srcpath, $dstpath, $callback->($status)
		615
		616	Try to move the I<file> (directories not supported as either source or
		617	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		618	the C<0> (error) or C<-1> ok.
		619
		620	This is a composite request that tries to rename(2) the file first. If
		621	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		622	that is successful, unlinking the C<$srcpath>.
		623
		624	=cut
		625
		626	sub aio_move($$;$) {
		627	aio_block {
		628	my ($src, $dst, $cb) = @_;
		629
		630	my $pri = aioreq_pri;
		631	my $grp = aio_group $cb;
		632
		633	aioreq_pri $pri;
		634	add $grp aio_rename $src, $dst, sub {
		635	if ($_[0] && $! == EXDEV) {
		636	aioreq_pri $pri;
		637	add $grp aio_copy $src, $dst, sub {
		638	$grp->result ($_[0]);
		639
		640	if (!$_[0]) {
		641	aioreq_pri $pri;
		642	add $grp aio_unlink $src;
		643	}
		644	};
		645	} else {
		646	$grp->result ($_[0]);
		647	}
		648	};
		649
		650	$grp
		651	}
		652	}
		653
343	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	654	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
344		655
345	Scans a directory (similar to C<aio_readdir>) but additionally tries to	656	Scans a directory (similar to C<aio_readdir>) but additionally tries to
346	separate the entries of directory C<$path> into two sets of names, ones	657	efficiently separate the entries of directory C<$path> into two sets of
347	you can recurse into (directories or links to them), and ones you cannot	658	names, directories you can recurse into (directories), and ones you cannot
348	recurse into (everything else).	659	recurse into (everything else, including symlinks to directories).
349		660
350	C<aio_scandir> is a composite request that consists of many sub	661	C<aio_scandir> is a composite request that creates of many sub requests_
351	requests. C<$maxreq> specifies the maximum number of outstanding aio	662	C<$maxreq> specifies the maximum number of outstanding aio requests that
352	requests that this function generates. If it is C<< <= 0 >>, then a	663	this function generates. If it is C<< <= 0 >>, then a suitable default
353	suitable default will be chosen (currently 8).	664	will be chosen (currently 4).
354		665
355	On error, the callback is called without arguments, otherwise it receives	666	On error, the callback is called without arguments, otherwise it receives
356	two array-refs with path-relative entry names.	667	two array-refs with path-relative entry names.
357		668
358	Example:	669	Example:
…		…
392	as those tend to return 0 or 1 as link counts, which disables the	703	as those tend to return 0 or 1 as link counts, which disables the
393	directory counting heuristic.	704	directory counting heuristic.
394		705
395	=cut	706	=cut
396		707
397	sub aio_scandir($$$) {	708	sub aio_scandir($$;$) {
		709	aio_block {
398	my ($path, $maxreq, $cb) = @_;	710	my ($path, $maxreq, $cb) = @_;
399		711
		712	my $pri = aioreq_pri;
		713
400	my $grp = aio_group;	714	my $grp = aio_group $cb;
401		715
402	$maxreq = 8 if $maxreq <= 0;	716	$maxreq = 4 if $maxreq <= 0;
403		717
404	# stat once	718	# stat once
		719	aioreq_pri $pri;
405	add $grp aio_stat $path, sub {	720	add $grp aio_stat $path, sub {
406	return $cb->() if $_[0];	721	return $grp->result () if $_[0];
407	my $now = time;	722	my $now = time;
408	my $hash1 = join ":", (stat _)[0,1,3,7,9];	723	my $hash1 = join ":", (stat _)[0,1,3,7,9];
409		724
410	# read the directory entries	725	# read the directory entries
		726	aioreq_pri $pri;
411	add $grp aio_readdir $path, sub {	727	add $grp aio_readdir $path, sub {
412	my $entries = shift	728	my $entries = shift
413	or return $cb->();	729	or return $grp->result ();
414		730
415	# stat the dir another time	731	# stat the dir another time
		732	aioreq_pri $pri;
416	add $grp aio_stat $path, sub {	733	add $grp aio_stat $path, sub {
417	my $hash2 = join ":", (stat _)[0,1,3,7,9];	734	my $hash2 = join ":", (stat _)[0,1,3,7,9];
418		735
419	my $ndirs;	736	my $ndirs;
420		737
421	# take the slow route if anything looks fishy	738	# take the slow route if anything looks fishy
422	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	739	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
423	$ndirs = -1;	740	$ndirs = -1;
424	} else {	741	} else {
425	# if nlink == 2, we are finished	742	# if nlink == 2, we are finished
426	# on non-posix-fs's, we rely on nlink < 2	743	# on non-posix-fs's, we rely on nlink < 2
427	$ndirs = (stat _)[3] - 2	744	$ndirs = (stat _)[3] - 2
428	or return $cb->([], $entries);	745	or return $grp->result ([], $entries);
429	}
430
431	# sort into likely dirs and likely nondirs
432	# dirs == files without ".", short entries first
433	$entries = [map $_->[0],
434	sort { $b->[1] cmp $a->[1] }
435	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
436	@$entries];
437
438	my (@dirs, @nondirs);
439
440	my ($statcb, $schedcb);
441	my $nreq = 0;
442
443	$schedcb = sub {
444	if (@$entries) {
445	if ($nreq < $maxreq) {
446	my $ent = pop @$entries;
447	$nreq++;
448	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
449	}
450	} elsif (!$nreq) {
451	# finished
452	undef $statcb;
453	undef $schedcb;
454	$cb->(\@dirs, \@nondirs) if $cb;
455	undef $cb;
456	}	746	}
		747
		748	# sort into likely dirs and likely nondirs
		749	# dirs == files without ".", short entries first
		750	$entries = [map $_->[0],
		751	sort { $b->[1] cmp $a->[1] }
		752	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		753	@$entries];
		754
		755	my (@dirs, @nondirs);
		756
		757	my $statgrp = add $grp aio_group sub {
		758	$grp->result (\@dirs, \@nondirs);
		759	};
		760
		761	limit $statgrp $maxreq;
		762	feed $statgrp sub {
		763	return unless @$entries;
		764	my $entry = pop @$entries;
		765
		766	aioreq_pri $pri;
		767	add $statgrp aio_stat "$path/$entry/.", sub {
		768	if ($_[0] < 0) {
		769	push @nondirs, $entry;
		770	} else {
		771	# need to check for real directory
		772	aioreq_pri $pri;
		773	add $statgrp aio_lstat "$path/$entry", sub {
		774	if (-d _) {
		775	push @dirs, $entry;
		776
		777	unless (--$ndirs) {
		778	push @nondirs, @$entries;
		779	feed $statgrp;
		780	}
		781	} else {
		782	push @nondirs, $entry;
		783	}
		784	}
		785	}
		786	};
		787	};
457	};	788	};
458	$statcb = sub {
459	my ($status, $entry) = @_;
460
461	if ($status < 0) {
462	$nreq--;
463	push @nondirs, $entry;
464	&$schedcb;
465	} else {
466	# need to check for real directory
467	add $grp aio_lstat "$path/$entry", sub {
468	$nreq--;
469
470	if (-d _) {
471	push @dirs, $entry;
472
473	if (!--$ndirs) {
474	push @nondirs, @$entries;
475	$entries = [];
476	}
477	} else {
478	push @nondirs, $entry;
479	}
480
481	&$schedcb;
482	}
483	}
484	};
485
486	&$schedcb while @$entries && $nreq < $maxreq;
487	};	789	};
488	};	790	};
		791
		792	$grp
489	};	793	}
		794	}
490		795
		796	=item aio_rmtree $path, $callback->($status)
		797
		798	Delete a directory tree starting (and including) C<$path>, return the
		799	status of the final C<rmdir> only. This is a composite request that
		800	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		801	everything else.
		802
		803	=cut
		804
		805	sub aio_rmtree;
		806	sub aio_rmtree($;$) {
		807	aio_block {
		808	my ($path, $cb) = @_;
		809
		810	my $pri = aioreq_pri;
		811	my $grp = aio_group $cb;
		812
		813	aioreq_pri $pri;
		814	add $grp aio_scandir $path, 0, sub {
		815	my ($dirs, $nondirs) = @_;
		816
		817	my $dirgrp = aio_group sub {
		818	add $grp aio_rmdir $path, sub {
		819	$grp->result ($_[0]);
		820	};
		821	};
		822
		823	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		824	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		825
		826	add $grp $dirgrp;
		827	};
		828
491	$grp	829	$grp
		830	}
492	}	831	}
493		832
494	=item aio_fsync $fh, $callback->($status)	833	=item aio_fsync $fh, $callback->($status)
495		834
496	Asynchronously call fsync on the given filehandle and call the callback	835	Asynchronously call fsync on the given filehandle and call the callback
…		…
502	callback with the fdatasync result code.	841	callback with the fdatasync result code.
503		842
504	If this call isn't available because your OS lacks it or it couldn't be	843	If this call isn't available because your OS lacks it or it couldn't be
505	detected, it will be emulated by calling C<fsync> instead.	844	detected, it will be emulated by calling C<fsync> instead.
506		845
507	=item aio_group $callback->()	846	=item aio_group $callback->(...)
508
509	[EXPERIMENTAL]
510		847
511	This is a very special aio request: Instead of doing something, it is a	848	This is a very special aio request: Instead of doing something, it is a
512	container for other aio requests, which is useful if you want to bundle	849	container for other aio requests, which is useful if you want to bundle
513	many requests into a single, composite, request.	850	many requests into a single, composite, request with a definite callback
		851	and the ability to cancel the whole request with its subrequests.
514		852
515	Returns an object of class L<IO::AIO::GRP>. See its documentation below	853	Returns an object of class L<IO::AIO::GRP>. See its documentation below
516	for more info.	854	for more info.
517		855
518	Example:	856	Example:
…		…
524	add $grp	862	add $grp
525	(aio_stat ...),	863	(aio_stat ...),
526	(aio_stat ...),	864	(aio_stat ...),
527	...;	865	...;
528		866
		867	=item aio_nop $callback->()
		868
		869	This is a special request - it does nothing in itself and is only used for
		870	side effects, such as when you want to add a dummy request to a group so
		871	that finishing the requests in the group depends on executing the given
		872	code.
		873
		874	While this request does nothing, it still goes through the execution
		875	phase and still requires a worker thread. Thus, the callback will not
		876	be executed immediately but only after other requests in the queue have
		877	entered their execution phase. This can be used to measure request
		878	latency.
		879
529	=item aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	880	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
530		881
531	Mainly used for debugging and benchmarking, this aio request puts one of	882	Mainly used for debugging and benchmarking, this aio request puts one of
532	the request workers to sleep for the given time.	883	the request workers to sleep for the given time.
533		884
		885	While it is theoretically handy to have simple I/O scheduling requests
		886	like sleep and file handle readable/writable, the overhead this creates is
		887	immense (it blocks a thread for a long time) so do not use this function
		888	except to put your application under artificial I/O pressure.
		889
534	=back	890	=back
535		891
536	=head2 IO::AIO::REQ CLASS	892	=head2 IO::AIO::REQ CLASS
537		893
538	All non-aggregate C<aio_*> functions return an object of this class when	894	All non-aggregate C<aio_*> functions return an object of this class when
539	called in non-void context.	895	called in non-void context.
540		896
541	A request always moves through the following five states in its lifetime,
542	in order: B<ready> (request has been created, but has not been executed
543	yet), B<execute> (request is currently being executed), B<pending>
544	(request has been executed but callback has not been called yet),
545	B<result> (results are being processed synchronously, includes calling the
546	callback) and B<done> (request has reached the end of its lifetime and
547	holds no resources anymore).
548
549	=over 4	897	=over 4
550		898
551	=item $req->cancel	899	=item cancel $req
552		900
553	Cancels the request, if possible. Has the effect of skipping execution	901	Cancels the request, if possible. Has the effect of skipping execution
554	when entering the B<execute> state and skipping calling the callback when	902	when entering the B<execute> state and skipping calling the callback when
555	entering the the B<result> state, but will leave the request otherwise	903	entering the the B<result> state, but will leave the request otherwise
556	untouched. That means that requests that currently execute will not be	904	untouched. That means that requests that currently execute will not be
557	stopped and resources held by the request will not be freed prematurely.	905	stopped and resources held by the request will not be freed prematurely.
558		906
		907	=item cb $req $callback->(...)
		908
		909	Replace (or simply set) the callback registered to the request.
		910
559	=back	911	=back
560		912
561	=head2 IO::AIO::GRP CLASS	913	=head2 IO::AIO::GRP CLASS
562		914
563	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	915	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
577	You add requests by calling the C<add> method with one or more	929	You add requests by calling the C<add> method with one or more
578	C<IO::AIO::REQ> objects:	930	C<IO::AIO::REQ> objects:
579		931
580	$grp->add (aio_unlink "...");	932	$grp->add (aio_unlink "...");
581		933
582	add $grp aio_stat "...", sub { ... };	934	add $grp aio_stat "...", sub {
		935	$_[0] or return $grp->result ("error");
		936
		937	# add another request dynamically, if first succeeded
		938	add $grp aio_open "...", sub {
		939	$grp->result ("ok");
		940	};
		941	};
583		942
584	This makes it very easy to create composite requests (see the source of	943	This makes it very easy to create composite requests (see the source of
585	C<aio_move> for an application) that work and feel like simple requests.	944	C<aio_move> for an application) that work and feel like simple requests.
586		945
		946	=over 4
		947
587	The IO::AIO::GRP objects will be cleaned up during calls to	948	=item * The IO::AIO::GRP objects will be cleaned up during calls to
588	C<IO::AIO::poll_cb>, just like any other request.	949	C<IO::AIO::poll_cb>, just like any other request.
589		950
590	They can be canceled like any other request. Canceling will cancel not	951	=item * They can be canceled like any other request. Canceling will cancel not
591	just the request itself, but also all requests it contains.	952	only the request itself, but also all requests it contains.
592		953
593	They can also can also be added to other IO::AIO::GRP objects.	954	=item * They can also can also be added to other IO::AIO::GRP objects.
		955
		956	=item * You must not add requests to a group from within the group callback (or
		957	any later time).
		958
		959	=back
594		960
595	Their lifetime, simplified, looks like this: when they are empty, they	961	Their lifetime, simplified, looks like this: when they are empty, they
596	will finish very quickly. If they contain only requests that are in the	962	will finish very quickly. If they contain only requests that are in the
597	C<done> state, they will also finish. Otherwise they will continue to	963	C<done> state, they will also finish. Otherwise they will continue to
598	exist.	964	exist.
599		965
		966	That means after creating a group you have some time to add requests. And
		967	in the callbacks of those requests, you can add further requests to the
		968	group. And only when all those requests have finished will the the group
		969	itself finish.
		970
600	=over 4	971	=over 4
601		972
		973	=item add $grp ...
		974
602	=item $grp->add (...)	975	=item $grp->add (...)
603		976
604	=item add $grp ...	977	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		978	be added, including other groups, as long as you do not create circular
		979	dependencies.
605		980
606	Add one or more	981	Returns all its arguments.
607	Cancels the request, if possible. Has the effect of skipping execution	982
608	when entering the B<execute> state and skipping calling the callback when	983	=item $grp->cancel_subs
609	entering the the B<result> state, but will leave the request otherwise	984
610	untouched. That means that requests that currently execute will not be	985	Cancel all subrequests and clears any feeder, but not the group request
611	stopped and resources held by the request will not be freed prematurely.	986	itself. Useful when you queued a lot of events but got a result early.
		987
		988	=item $grp->result (...)
		989
		990	Set the result value(s) that will be passed to the group callback when all
		991	subrequests have finished and set thre groups errno to the current value
		992	of errno (just like calling C<errno> without an error number). By default,
		993	no argument will be passed and errno is zero.
		994
		995	=item $grp->errno ([$errno])
		996
		997	Sets the group errno value to C<$errno>, or the current value of errno
		998	when the argument is missing.
		999
		1000	Every aio request has an associated errno value that is restored when
		1001	the callback is invoked. This method lets you change this value from its
		1002	default (0).
		1003
		1004	Calling C<result> will also set errno, so make sure you either set C<$!>
		1005	before the call to C<result>, or call c<errno> after it.
		1006
		1007	=item feed $grp $callback->($grp)
		1008
		1009	Sets a feeder/generator on this group: every group can have an attached
		1010	generator that generates requests if idle. The idea behind this is that,
		1011	although you could just queue as many requests as you want in a group,
		1012	this might starve other requests for a potentially long time. For
		1013	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		1014	requests, delaying any later requests for a long time.
		1015
		1016	To avoid this, and allow incremental generation of requests, you can
		1017	instead a group and set a feeder on it that generates those requests. The
		1018	feed callback will be called whenever there are few enough (see C<limit>,
		1019	below) requests active in the group itself and is expected to queue more
		1020	requests.
		1021
		1022	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1023	not impose any limits).
		1024
		1025	If the feed does not queue more requests when called, it will be
		1026	automatically removed from the group.
		1027
		1028	If the feed limit is C<0>, it will be set to C<2> automatically.
		1029
		1030	Example:
		1031
		1032	# stat all files in @files, but only ever use four aio requests concurrently:
		1033
		1034	my $grp = aio_group sub { print "finished\n" };
		1035	limit $grp 4;
		1036	feed $grp sub {
		1037	my $file = pop @files
		1038	or return;
		1039
		1040	add $grp aio_stat $file, sub { ... };
		1041	};
		1042
		1043	=item limit $grp $num
		1044
		1045	Sets the feeder limit for the group: The feeder will be called whenever
		1046	the group contains less than this many requests.
		1047
		1048	Setting the limit to C<0> will pause the feeding process.
612		1049
613	=back	1050	=back
614		1051
615	=head2 SUPPORT FUNCTIONS	1052	=head2 SUPPORT FUNCTIONS
		1053
		1054	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
616		1055
617	=over 4	1056	=over 4
618		1057
619	=item $fileno = IO::AIO::poll_fileno	1058	=item $fileno = IO::AIO::poll_fileno
620		1059
…		…
625		1064
626	See C<poll_cb> for an example.	1065	See C<poll_cb> for an example.
627		1066
628	=item IO::AIO::poll_cb	1067	=item IO::AIO::poll_cb
629		1068
630	Process all outstanding events on the result pipe. You have to call this	1069	Process some outstanding events on the result pipe. You have to call this
631	regularly. Returns the number of events processed. Returns immediately	1070	regularly. Returns the number of events processed. Returns immediately
632	when no events are outstanding.	1071	when no events are outstanding. The amount of events processed depends on
		1072	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1073
		1074	If not all requests were processed for whatever reason, the filehandle
		1075	will still be ready when C<poll_cb> returns.
633		1076
634	Example: Install an Event watcher that automatically calls	1077	Example: Install an Event watcher that automatically calls
635	IO::AIO::poll_cb with high priority:	1078	IO::AIO::poll_cb with high priority:
636		1079
637	Event->io (fd => IO::AIO::poll_fileno,	1080	Event->io (fd => IO::AIO::poll_fileno,
638	poll => 'r', async => 1,	1081	poll => 'r', async => 1,
639	cb => \&IO::AIO::poll_cb);	1082	cb => \&IO::AIO::poll_cb);
640		1083
		1084	=item IO::AIO::max_poll_reqs $nreqs
		1085
		1086	=item IO::AIO::max_poll_time $seconds
		1087
		1088	These set the maximum number of requests (default C<0>, meaning infinity)
		1089	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1090	the maximum amount of time (default C<0>, meaning infinity) spent in
		1091	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1092	of time C<poll_cb> is allowed to use).
		1093
		1094	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1095	syscall per request processed, which is not normally a problem unless your
		1096	callbacks are really really fast or your OS is really really slow (I am
		1097	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1098
		1099	Setting these is useful if you want to ensure some level of
		1100	interactiveness when perl is not fast enough to process all requests in
		1101	time.
		1102
		1103	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1104
		1105	Example: Install an Event watcher that automatically calls
		1106	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1107	program get the CPU sometimes even under high AIO load.
		1108
		1109	# try not to spend much more than 0.1s in poll_cb
		1110	IO::AIO::max_poll_time 0.1;
		1111
		1112	# use a low priority so other tasks have priority
		1113	Event->io (fd => IO::AIO::poll_fileno,
		1114	poll => 'r', nice => 1,
		1115	cb => &IO::AIO::poll_cb);
		1116
641	=item IO::AIO::poll_wait	1117	=item IO::AIO::poll_wait
642		1118
		1119	If there are any outstanding requests and none of them in the result
643	Wait till the result filehandle becomes ready for reading (simply does a	1120	phase, wait till the result filehandle becomes ready for reading (simply
644	C<select> on the filehandle. This is useful if you want to synchronously wait	1121	does a C<select> on the filehandle. This is useful if you want to
645	for some requests to finish).	1122	synchronously wait for some requests to finish).
646		1123
647	See C<nreqs> for an example.	1124	See C<nreqs> for an example.
648		1125
		1126	=item IO::AIO::poll
		1127
		1128	Waits until some requests have been handled.
		1129
		1130	Returns the number of requests processed, but is otherwise strictly
		1131	equivalent to:
		1132
		1133	IO::AIO::poll_wait, IO::AIO::poll_cb
		1134
649	=item IO::AIO::nreqs	1135	=item IO::AIO::flush
650		1136
651	Returns the number of requests currently outstanding (i.e. for which their	1137	Wait till all outstanding AIO requests have been handled.
652	callback has not been invoked yet).
653		1138
654	Example: wait till there are no outstanding requests anymore:	1139	Strictly equivalent to:
655		1140
656	IO::AIO::poll_wait, IO::AIO::poll_cb	1141	IO::AIO::poll_wait, IO::AIO::poll_cb
657	while IO::AIO::nreqs;	1142	while IO::AIO::nreqs;
658		1143
659	=item IO::AIO::flush	1144	=back
660		1145
661	Wait till all outstanding AIO requests have been handled.	1146	=head3 CONTROLLING THE NUMBER OF THREADS
662		1147
663	Strictly equivalent to:	1148	=over
664
665	IO::AIO::poll_wait, IO::AIO::poll_cb
666	while IO::AIO::nreqs;
667
668	=item IO::AIO::poll
669
670	Waits until some requests have been handled.
671
672	Strictly equivalent to:
673
674	IO::AIO::poll_wait, IO::AIO::poll_cb
675	if IO::AIO::nreqs;
676		1149
677	=item IO::AIO::min_parallel $nthreads	1150	=item IO::AIO::min_parallel $nthreads
678		1151
679	Set the minimum number of AIO threads to C<$nthreads>. The current default	1152	Set the minimum number of AIO threads to C<$nthreads>. The current
680	is C<4>, which means four asynchronous operations can be done at one time	1153	default is C<8>, which means eight asynchronous operations can execute
681	(the number of outstanding operations, however, is unlimited).	1154	concurrently at any one time (the number of outstanding requests,
		1155	however, is unlimited).
682		1156
683	IO::AIO starts threads only on demand, when an AIO request is queued and	1157	IO::AIO starts threads only on demand, when an AIO request is queued and
684	no free thread exists.	1158	no free thread exists. Please note that queueing up a hundred requests can
		1159	create demand for a hundred threads, even if it turns out that everything
		1160	is in the cache and could have been processed faster by a single thread.
685		1161
686	It is recommended to keep the number of threads low, as some Linux	1162	It is recommended to keep the number of threads relatively low, as some
687	kernel versions will scale negatively with the number of threads (higher	1163	Linux kernel versions will scale negatively with the number of threads
688	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1164	(higher parallelity => MUCH higher latency). With current Linux 2.6
689	threads should be fine.	1165	versions, 4-32 threads should be fine.
690		1166
691	Under most circumstances you don't need to call this function, as the	1167	Under most circumstances you don't need to call this function, as the
692	module selects a default that is suitable for low to moderate load.	1168	module selects a default that is suitable for low to moderate load.
693		1169
694	=item IO::AIO::max_parallel $nthreads	1170	=item IO::AIO::max_parallel $nthreads
…		…
703	This module automatically runs C<max_parallel 0> at program end, to ensure	1179	This module automatically runs C<max_parallel 0> at program end, to ensure
704	that all threads are killed and that there are no outstanding requests.	1180	that all threads are killed and that there are no outstanding requests.
705		1181
706	Under normal circumstances you don't need to call this function.	1182	Under normal circumstances you don't need to call this function.
707		1183
		1184	=item IO::AIO::max_idle $nthreads
		1185
		1186	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1187	threads that did not get a request to process within 10 seconds). That
		1188	means if a thread becomes idle while C<$nthreads> other threads are also
		1189	idle, it will free its resources and exit.
		1190
		1191	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1192	to allow for extremely high load situations, but want to free resources
		1193	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1194
		1195	The default is probably ok in most situations, especially if thread
		1196	creation is fast. If thread creation is very slow on your system you might
		1197	want to use larger values.
		1198
708	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1199	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1200
		1201	This is a very bad function to use in interactive programs because it
		1202	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1203	use an C<aio_group> together with a feed callback.
709		1204
710	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1205	Sets the maximum number of outstanding requests to C<$nreqs>. If you
711	try to queue up more than this number of requests, the caller will block until	1206	to queue up more than this number of requests, the next call to the
712	some requests have been handled.	1207	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1208	function will block until the limit is no longer exceeded.
713		1209
714	The default is very large, so normally there is no practical limit. If you	1210	The default value is very large, so there is no practical limit on the
715	queue up many requests in a loop it often improves speed if you set	1211	number of outstanding requests.
716	this to a relatively low number, such as C<100>.
717		1212
718	Under normal circumstances you don't need to call this function.	1213	You can still queue as many requests as you want. Therefore,
		1214	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1215	as a stop gap to shield against fatal memory overflow (with large values).
		1216
		1217	=back
		1218
		1219	=head3 STATISTICAL INFORMATION
		1220
		1221	=over
		1222
		1223	=item IO::AIO::nreqs
		1224
		1225	Returns the number of requests currently in the ready, execute or pending
		1226	states (i.e. for which their callback has not been invoked yet).
		1227
		1228	Example: wait till there are no outstanding requests anymore:
		1229
		1230	IO::AIO::poll_wait, IO::AIO::poll_cb
		1231	while IO::AIO::nreqs;
		1232
		1233	=item IO::AIO::nready
		1234
		1235	Returns the number of requests currently in the ready state (not yet
		1236	executed).
		1237
		1238	=item IO::AIO::npending
		1239
		1240	Returns the number of requests currently in the pending state (executed,
		1241	but not yet processed by poll_cb).
719		1242
720	=back	1243	=back
721		1244
722	=cut	1245	=cut
723		1246
…		…
735	or return undef;	1258	or return undef;
736		1259
737	*$sym	1260	*$sym
738	}	1261	}
739		1262
740	min_parallel 4;	1263	min_parallel 8;
741		1264
742	END {	1265	END { flush }
743	max_parallel 0;
744	}
745		1266
746	1;	1267	1;
747		1268
748	=head2 FORK BEHAVIOUR	1269	=head2 FORK BEHAVIOUR
749		1270
750	This module should do "the right thing" when the process using it forks:	1271	This module should do "the right thing" when the process using it forks:
751		1272
752	Before the fork, IO::AIO enters a quiescent state where no requests	1273	Before the fork, IO::AIO enters a quiescent state where no requests
753	can be added in other threads and no results will be processed. After	1274	can be added in other threads and no results will be processed. After
754	the fork the parent simply leaves the quiescent state and continues	1275	the fork the parent simply leaves the quiescent state and continues
755	request/result processing, while the child clears the request/result	1276	request/result processing, while the child frees the request/result queue
756	queue (so the requests started before the fork will only be handled in	1277	(so that the requests started before the fork will only be handled in the
757	the parent). Threads will be started on demand until the limit ste in the	1278	parent). Threads will be started on demand until the limit set in the
758	parent process has been reached again.	1279	parent process has been reached again.
759		1280
760	In short: the parent will, after a short pause, continue as if fork had	1281	In short: the parent will, after a short pause, continue as if fork had
761	not been called, while the child will act as if IO::AIO has not been used	1282	not been called, while the child will act as if IO::AIO has not been used
762	yet.	1283	yet.
763		1284
		1285	=head2 MEMORY USAGE
		1286
		1287	Per-request usage:
		1288
		1289	Each aio request uses - depending on your architecture - around 100-200
		1290	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1291	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1292	scalars and other data passed into aio requests will also be locked and
		1293	will consume memory till the request has entered the done state.
		1294
		1295	This is now awfully much, so queuing lots of requests is not usually a
		1296	problem.
		1297
		1298	Per-thread usage:
		1299
		1300	In the execution phase, some aio requests require more memory for
		1301	temporary buffers, and each thread requires a stack and other data
		1302	structures (usually around 16k-128k, depending on the OS).
		1303
		1304	=head1 KNOWN BUGS
		1305
		1306	Known bugs will be fixed in the next release.
		1307
764	=head1 SEE ALSO	1308	=head1 SEE ALSO
765		1309
766	L<Coro>, L<Linux::AIO> (obsolete).	1310	L<Coro::AIO>.
767		1311
768	=head1 AUTHOR	1312	=head1 AUTHOR
769		1313
770	Marc Lehmann <schmorp@schmorp.de>	1314	Marc Lehmann <schmorp@schmorp.de>
771	http://home.schmorp.de/	1315	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs. Revision 1.109 by root, Sun Jun 3 09:44:17 2007 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs.
Revision 1.109 by root, Sun Jun 3 09:44:17 2007 UTC