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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.52 by root, Sat Oct 21 23:06:04 2006 UTC vs.
Revision 1.108 by root, Fri Jun 1 13:25:50 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 = '1.8';	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	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	199	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
		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);
		206
		207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
82		208
83	require XSLoader;	209	require XSLoader;
84	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
85	}	211	}
86		212
87	=head1 FUNCTIONS	213	=head1 FUNCTIONS
88		214
89	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
90		216
91	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
92	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
93	and they all accept an additional (and optional) C<$callback> argument	219	and they all accept an additional (and optional) C<$callback> argument
94	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
…		…
97	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
98		224
99	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
100	internally until the request has finished.	226	internally until the request has finished.
101		227
102	All non-composite requests (requests that are not broken down into
103	multiple requests) return objects of type L<IO::AIO::REQ> that allow	228	All functions return request objects of type L<IO::AIO::REQ> that allow
104	further manipulation of running requests.	229	further manipulation of those requests while they are in-flight.
105		230
106	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
107	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
108	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
109	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
110	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
111		237
112	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
113	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
114	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
115	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
116	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)
117	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.
118		247
119	=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
120		282
121	=item aio_open $pathname, $flags, $mode, $callback->($fh)	283	=item aio_open $pathname, $flags, $mode, $callback->($fh)
122		284
123	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
124	created filehandle for the file.	286	created filehandle for the file.
…		…
130	list. They are the same as used by C<sysopen>.	292	list. They are the same as used by C<sysopen>.
131		293
132	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
133	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>,
134	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,
135	and C<0666> or C<0777> if you do).	297	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		298	by the umask in effect then the request is being executed, so better never
		299	change the umask.
136		300
137	Example:	301	Example:
138		302
139	aio_open "/etc/passwd", O_RDONLY, 0, sub {	303	aio_open "/etc/passwd", O_RDONLY, 0, sub {
140	if ($_[0]) {	304	if ($_[0]) {
…		…
143	} else {	307	} else {
144	die "open failed: $!\n";	308	die "open failed: $!\n";
145	}	309	}
146	};	310	};
147		311
		312
148	=item aio_close $fh, $callback->($status)	313	=item aio_close $fh, $callback->($status)
149		314
150	Asynchronously close a file and call the callback with the result	315	Asynchronously close a file and call the callback with the result
151	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
152	filehandle here, as perl will likely close the file descriptor another	317	filehandle here, as perl will likely close the file descriptor another
…		…
154	C<close> or just let filehandles go out of scope.	319	C<close> or just let filehandles go out of scope.
155		320
156	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
157	therefore best to avoid this function.	322	therefore best to avoid this function.
158		323
		324
159	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	325	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
160		326
161	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	327	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
162		328
163	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>
164	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
165	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
166	like the syscall).	332	like the syscall). If C<offset> is undefined, then the current file offset
		333	will be used (and updated), otherwise the file offset will not be changed
		334	by these calls.
167		335
168	The C<$data> scalar I<MUST NOT> be modified in any way while the request	336	The C<$data> scalar I<MUST NOT> be modified in any way while the request
169	is outstanding. Modifying it can result in segfaults or WW3 (if the	337	is outstanding. Modifying it can result in segfaults or World War III (if
170	necessary/optional hardware is installed).	338	the necessary/optional hardware is installed).
171		339
172	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	340	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
173	offset C<0> within the scalar:	341	offset C<0> within the scalar:
174		342
175	aio_read $fh, 7, 15, $buffer, 0, sub {	343	aio_read $fh, 7, 15, $buffer, 0, sub {
176	$_[0] > 0 or die "read error: $!";	344	$_[0] > 0 or die "read error: $!";
177	print "read $_[0] bytes: <$buffer>\n";	345	print "read $_[0] bytes: <$buffer>\n";
178	};	346	};
179		347
180	=item aio_move $srcpath, $dstpath, $callback->($status)
181
182	Try to move the I<file> (directories not supported as either source or
183	destination) from C<$srcpath> to C<$dstpath> and call the callback with
184	the C<0> (error) or C<-1> ok.
185
186	This is a composite request that tries to rename(2) the file first. If
187	rename files with C<EXDEV>, it creates the destination file with mode 0200
188	and copies the contents of the source file into it using C<aio_sendfile>,
189	followed by restoring atime, mtime, access mode and uid/gid, in that
190	order, and unlinking the C<$srcpath>.
191
192	If an error occurs, the partial destination file will be unlinked, if
193	possible, except when setting atime, mtime, access mode and uid/gid, where
194	errors are being ignored.
195
196	=cut
197
198	sub aio_move($$$) {
199	my ($src, $dst, $cb) = @_;
200
201	aio_rename $src, $dst, sub {
202	if ($_[0] && $! == EXDEV) {
203	aio_open $src, O_RDONLY, 0, sub {
204	if (my $src_fh = $_[0]) {
205	my @stat = stat $src_fh;
206
207	aio_open $dst, O_WRONLY, 0200, sub {
208	if (my $dst_fh = $_[0]) {
209	aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
210	close $src_fh;
211
212	if ($_[0] == $stat[7]) {
213	utime $stat[8], $stat[9], $dst;
214	chmod $stat[2] & 07777, $dst_fh;
215	chown $stat[4], $stat[5], $dst_fh;
216	close $dst_fh;
217
218	aio_unlink $src, sub {
219	$cb->($_[0]);
220	};
221	} else {
222	my $errno = $!;
223	aio_unlink $dst, sub {
224	$! = $errno;
225	$cb->(-1);
226	};
227	}
228	};
229	} else {
230	$cb->(-1);
231	}
232	},
233
234	} else {
235	$cb->(-1);
236	}
237	};
238	} else {
239	$cb->($_[0]);
240	}
241	};
242	}
243		348
244	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	349	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
245		350
246	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	351	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
247	reading at byte offset C<$in_offset>, and starts writing at the current	352	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
261	C<$in_fh> than are written, and there is no way to find out how many	366	C<$in_fh> than are written, and there is no way to find out how many
262	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	367	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
263	provides the number of bytes written to C<$out_fh>. Only if the result	368	provides the number of bytes written to C<$out_fh>. Only if the result
264	value equals C<$length> one can assume that C<$length> bytes have been	369	value equals C<$length> one can assume that C<$length> bytes have been
265	read.	370	read.
		371
266		372
267	=item aio_readahead $fh,$offset,$length, $callback->($retval)	373	=item aio_readahead $fh,$offset,$length, $callback->($retval)
268		374
269	C<aio_readahead> populates the page cache with data from a file so that	375	C<aio_readahead> populates the page cache with data from a file so that
270	subsequent reads from that file will not block on disk I/O. The C<$offset>	376	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
276	file. The current file offset of the file is left unchanged.	382	file. The current file offset of the file is left unchanged.
277		383
278	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	384	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
279	emulated by simply reading the data, which would have a similar effect.	385	emulated by simply reading the data, which would have a similar effect.
280		386
		387
281	=item aio_stat $fh_or_path, $callback->($status)	388	=item aio_stat $fh_or_path, $callback->($status)
282		389
283	=item aio_lstat $fh, $callback->($status)	390	=item aio_lstat $fh, $callback->($status)
284		391
285	Works like perl's C<stat> or C<lstat> in void context. The callback will	392	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
298	aio_stat "/etc/passwd", sub {	405	aio_stat "/etc/passwd", sub {
299	$_[0] and die "stat failed: $!";	406	$_[0] and die "stat failed: $!";
300	print "size is ", -s _, "\n";	407	print "size is ", -s _, "\n";
301	};	408	};
302		409
		410
		411	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		412
		413	Works like perl's C<utime> function (including the special case of $atime
		414	and $mtime being undef). Fractional times are supported if the underlying
		415	syscalls support them.
		416
		417	When called with a pathname, uses utimes(2) if available, otherwise
		418	utime(2). If called on a file descriptor, uses futimes(2) if available,
		419	otherwise returns ENOSYS, so this is not portable.
		420
		421	Examples:
		422
		423	# set atime and mtime to current time (basically touch(1)):
		424	aio_utime "path", undef, undef;
		425	# set atime to current time and mtime to beginning of the epoch:
		426	aio_utime "path", time, undef; # undef==0
		427
		428
		429	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		430
		431	Works like perl's C<chown> function, except that C<undef> for either $uid
		432	or $gid is being interpreted as "do not change" (but -1 can also be used).
		433
		434	Examples:
		435
		436	# same as "chown root path" in the shell:
		437	aio_chown "path", 0, -1;
		438	# same as above:
		439	aio_chown "path", 0, undef;
		440
		441
		442	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		443
		444	Works like perl's C<chmod> function.
		445
		446
303	=item aio_unlink $pathname, $callback->($status)	447	=item aio_unlink $pathname, $callback->($status)
304		448
305	Asynchronously unlink (delete) a file and call the callback with the	449	Asynchronously unlink (delete) a file and call the callback with the
306	result code.	450	result code.
307		451
		452
		453	=item aio_mknod $path, $mode, $dev, $callback->($status)
		454
		455	[EXPERIMENTAL]
		456
		457	Asynchronously create a device node (or fifo). See mknod(2).
		458
		459	The only (POSIX-) portable way of calling this function is:
		460
		461	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		462
		463
308	=item aio_link $srcpath, $dstpath, $callback->($status)	464	=item aio_link $srcpath, $dstpath, $callback->($status)
309		465
310	Asynchronously create a new link to the existing object at C<$srcpath> at	466	Asynchronously create a new link to the existing object at C<$srcpath> at
311	the path C<$dstpath> and call the callback with the result code.	467	the path C<$dstpath> and call the callback with the result code.
312		468
		469
313	=item aio_symlink $srcpath, $dstpath, $callback->($status)	470	=item aio_symlink $srcpath, $dstpath, $callback->($status)
314		471
315	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	472	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
316	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.
317		474
		475
		476	=item aio_readlink $path, $callback->($link)
		477
		478	Asynchronously read the symlink specified by C<$path> and pass it to
		479	the callback. If an error occurs, nothing or undef gets passed to the
		480	callback.
		481
		482
318	=item aio_rename $srcpath, $dstpath, $callback->($status)	483	=item aio_rename $srcpath, $dstpath, $callback->($status)
319		484
320	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	485	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
321	rename(2) and call the callback with the result code.	486	rename(2) and call the callback with the result code.
322		487
		488
		489	=item aio_mkdir $pathname, $mode, $callback->($status)
		490
		491	Asynchronously mkdir (create) a directory and call the callback with
		492	the result code. C<$mode> will be modified by the umask at the time the
		493	request is executed, so do not change your umask.
		494
		495
323	=item aio_rmdir $pathname, $callback->($status)	496	=item aio_rmdir $pathname, $callback->($status)
324		497
325	Asynchronously rmdir (delete) a directory and call the callback with the	498	Asynchronously rmdir (delete) a directory and call the callback with the
326	result code.	499	result code.
		500
327		501
328	=item aio_readdir $pathname, $callback->($entries)	502	=item aio_readdir $pathname, $callback->($entries)
329		503
330	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	504	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
331	directory (i.e. opendir + readdir + closedir). The entries will not be	505	directory (i.e. opendir + readdir + closedir). The entries will not be
332	sorted, and will B<NOT> include the C<.> and C<..> entries.	506	sorted, and will B<NOT> include the C<.> and C<..> entries.
333		507
334	The callback a single argument which is either C<undef> or an array-ref	508	The callback a single argument which is either C<undef> or an array-ref
335	with the filenames.	509	with the filenames.
336		510
		511
		512	=item aio_load $path, $data, $callback->($status)
		513
		514	This is a composite request that tries to fully load the given file into
		515	memory. Status is the same as with aio_read.
		516
		517	=cut
		518
		519	sub aio_load($$;$) {
		520	aio_block {
		521	my ($path, undef, $cb) = @_;
		522	my $data = \$_[1];
		523
		524	my $pri = aioreq_pri;
		525	my $grp = aio_group $cb;
		526
		527	aioreq_pri $pri;
		528	add $grp aio_open $path, O_RDONLY, 0, sub {
		529	my $fh = shift
		530	or return $grp->result (-1);
		531
		532	aioreq_pri $pri;
		533	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		534	$grp->result ($_[0]);
		535	};
		536	};
		537
		538	$grp
		539	}
		540	}
		541
		542	=item aio_copy $srcpath, $dstpath, $callback->($status)
		543
		544	Try to copy the I<file> (directories not supported as either source or
		545	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		546	the C<0> (error) or C<-1> ok.
		547
		548	This is a composite request that it creates the destination file with
		549	mode 0200 and copies the contents of the source file into it using
		550	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		551	uid/gid, in that order.
		552
		553	If an error occurs, the partial destination file will be unlinked, if
		554	possible, except when setting atime, mtime, access mode and uid/gid, where
		555	errors are being ignored.
		556
		557	=cut
		558
		559	sub aio_copy($$;$) {
		560	aio_block {
		561	my ($src, $dst, $cb) = @_;
		562
		563	my $pri = aioreq_pri;
		564	my $grp = aio_group $cb;
		565
		566	aioreq_pri $pri;
		567	add $grp aio_open $src, O_RDONLY, 0, sub {
		568	if (my $src_fh = $_[0]) {
		569	my @stat = stat $src_fh;
		570
		571	aioreq_pri $pri;
		572	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		573	if (my $dst_fh = $_[0]) {
		574	aioreq_pri $pri;
		575	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		576	if ($_[0] == $stat[7]) {
		577	$grp->result (0);
		578	close $src_fh;
		579
		580	# those should not normally block. should. should.
		581	utime $stat[8], $stat[9], $dst;
		582	chmod $stat[2] & 07777, $dst_fh;
		583	chown $stat[4], $stat[5], $dst_fh;
		584	close $dst_fh;
		585	} else {
		586	$grp->result (-1);
		587	close $src_fh;
		588	close $dst_fh;
		589
		590	aioreq $pri;
		591	add $grp aio_unlink $dst;
		592	}
		593	};
		594	} else {
		595	$grp->result (-1);
		596	}
		597	},
		598
		599	} else {
		600	$grp->result (-1);
		601	}
		602	};
		603
		604	$grp
		605	}
		606	}
		607
		608	=item aio_move $srcpath, $dstpath, $callback->($status)
		609
		610	Try to move the I<file> (directories not supported as either source or
		611	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		612	the C<0> (error) or C<-1> ok.
		613
		614	This is a composite request that tries to rename(2) the file first. If
		615	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		616	that is successful, unlinking the C<$srcpath>.
		617
		618	=cut
		619
		620	sub aio_move($$;$) {
		621	aio_block {
		622	my ($src, $dst, $cb) = @_;
		623
		624	my $pri = aioreq_pri;
		625	my $grp = aio_group $cb;
		626
		627	aioreq_pri $pri;
		628	add $grp aio_rename $src, $dst, sub {
		629	if ($_[0] && $! == EXDEV) {
		630	aioreq_pri $pri;
		631	add $grp aio_copy $src, $dst, sub {
		632	$grp->result ($_[0]);
		633
		634	if (!$_[0]) {
		635	aioreq_pri $pri;
		636	add $grp aio_unlink $src;
		637	}
		638	};
		639	} else {
		640	$grp->result ($_[0]);
		641	}
		642	};
		643
		644	$grp
		645	}
		646	}
		647
337	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	648	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
338		649
339	Scans a directory (similar to C<aio_readdir>) but additionally tries to	650	Scans a directory (similar to C<aio_readdir>) but additionally tries to
340	separate the entries of directory C<$path> into two sets of names, ones	651	efficiently separate the entries of directory C<$path> into two sets of
341	you can recurse into (directories or links to them), and ones you cannot	652	names, directories you can recurse into (directories), and ones you cannot
342	recurse into (everything else).	653	recurse into (everything else, including symlinks to directories).
343		654
344	C<aio_scandir> is a composite request that consists of many sub	655	C<aio_scandir> is a composite request that creates of many sub requests_
345	requests. C<$maxreq> specifies the maximum number of outstanding aio	656	C<$maxreq> specifies the maximum number of outstanding aio requests that
346	requests that this function generates. If it is C<< <= 0 >>, then a	657	this function generates. If it is C<< <= 0 >>, then a suitable default
347	suitable default will be chosen (currently 8).	658	will be chosen (currently 4).
348		659
349	On error, the callback is called without arguments, otherwise it receives	660	On error, the callback is called without arguments, otherwise it receives
350	two array-refs with path-relative entry names.	661	two array-refs with path-relative entry names.
351		662
352	Example:	663	Example:
…		…
386	as those tend to return 0 or 1 as link counts, which disables the	697	as those tend to return 0 or 1 as link counts, which disables the
387	directory counting heuristic.	698	directory counting heuristic.
388		699
389	=cut	700	=cut
390		701
391	sub aio_scandir($$$) {	702	sub aio_scandir($$;$) {
		703	aio_block {
392	my ($path, $maxreq, $cb) = @_;	704	my ($path, $maxreq, $cb) = @_;
393		705
		706	my $pri = aioreq_pri;
		707
		708	my $grp = aio_group $cb;
		709
394	$maxreq = 8 if $maxreq <= 0;	710	$maxreq = 4 if $maxreq <= 0;
395		711
396	# stat once	712	# stat once
		713	aioreq_pri $pri;
397	aio_stat $path, sub {	714	add $grp aio_stat $path, sub {
398	return $cb->() if $_[0];	715	return $grp->result () if $_[0];
399	my $now = time;	716	my $now = time;
400	my $hash1 = join ":", (stat _)[0,1,3,7,9];	717	my $hash1 = join ":", (stat _)[0,1,3,7,9];
401		718
402	# read the directory entries	719	# read the directory entries
		720	aioreq_pri $pri;
403	aio_readdir $path, sub {	721	add $grp aio_readdir $path, sub {
404	my $entries = shift	722	my $entries = shift
405	or return $cb->();	723	or return $grp->result ();
406		724
407	# stat the dir another time	725	# stat the dir another time
		726	aioreq_pri $pri;
408	aio_stat $path, sub {	727	add $grp aio_stat $path, sub {
409	my $hash2 = join ":", (stat _)[0,1,3,7,9];	728	my $hash2 = join ":", (stat _)[0,1,3,7,9];
410		729
411	my $ndirs;	730	my $ndirs;
412		731
413	# take the slow route if anything looks fishy	732	# take the slow route if anything looks fishy
414	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	733	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
415	$ndirs = -1;	734	$ndirs = -1;
416	} else {	735	} else {
417	# if nlink == 2, we are finished	736	# if nlink == 2, we are finished
418	# on non-posix-fs's, we rely on nlink < 2	737	# on non-posix-fs's, we rely on nlink < 2
419	$ndirs = (stat _)[3] - 2	738	$ndirs = (stat _)[3] - 2
420	or return $cb->([], $entries);	739	or return $grp->result ([], $entries);
421	}
422
423	# sort into likely dirs and likely nondirs
424	# dirs == files without ".", short entries first
425	$entries = [map $_->[0],
426	sort { $b->[1] cmp $a->[1] }
427	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
428	@$entries];
429
430	my (@dirs, @nondirs);
431
432	my ($statcb, $schedcb);
433	my $nreq = 0;
434
435	$schedcb = sub {
436	if (@$entries) {
437	if ($nreq < $maxreq) {
438	my $ent = pop @$entries;
439	$nreq++;
440	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
441	}
442	} elsif (!$nreq) {
443	# finished
444	undef $statcb;
445	undef $schedcb;
446	$cb->(\@dirs, \@nondirs) if $cb;
447	undef $cb;
448	}	740	}
		741
		742	# sort into likely dirs and likely nondirs
		743	# dirs == files without ".", short entries first
		744	$entries = [map $_->[0],
		745	sort { $b->[1] cmp $a->[1] }
		746	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		747	@$entries];
		748
		749	my (@dirs, @nondirs);
		750
		751	my $statgrp = add $grp aio_group sub {
		752	$grp->result (\@dirs, \@nondirs);
		753	};
		754
		755	limit $statgrp $maxreq;
		756	feed $statgrp sub {
		757	return unless @$entries;
		758	my $entry = pop @$entries;
		759
		760	aioreq_pri $pri;
		761	add $statgrp aio_stat "$path/$entry/.", sub {
		762	if ($_[0] < 0) {
		763	push @nondirs, $entry;
		764	} else {
		765	# need to check for real directory
		766	aioreq_pri $pri;
		767	add $statgrp aio_lstat "$path/$entry", sub {
		768	if (-d _) {
		769	push @dirs, $entry;
		770
		771	unless (--$ndirs) {
		772	push @nondirs, @$entries;
		773	feed $statgrp;
		774	}
		775	} else {
		776	push @nondirs, $entry;
		777	}
		778	}
		779	}
		780	};
		781	};
449	};	782	};
450	$statcb = sub {
451	my ($status, $entry) = @_;
452
453	if ($status < 0) {
454	$nreq--;
455	push @nondirs, $entry;
456	&$schedcb;
457	} else {
458	# need to check for real directory
459	aio_lstat "$path/$entry", sub {
460	$nreq--;
461
462	if (-d _) {
463	push @dirs, $entry;
464
465	if (!--$ndirs) {
466	push @nondirs, @$entries;
467	$entries = [];
468	}
469	} else {
470	push @nondirs, $entry;
471	}
472
473	&$schedcb;
474	}
475	}
476	};
477
478	&$schedcb while @$entries && $nreq < $maxreq;
479	};	783	};
480	};	784	};
		785
		786	$grp
481	};	787	}
		788	}
		789
		790	=item aio_rmtree $path, $callback->($status)
		791
		792	Delete a directory tree starting (and including) C<$path>, return the
		793	status of the final C<rmdir> only. This is a composite request that
		794	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		795	everything else.
		796
		797	=cut
		798
		799	sub aio_rmtree;
		800	sub aio_rmtree($;$) {
		801	aio_block {
		802	my ($path, $cb) = @_;
		803
		804	my $pri = aioreq_pri;
		805	my $grp = aio_group $cb;
		806
		807	aioreq_pri $pri;
		808	add $grp aio_scandir $path, 0, sub {
		809	my ($dirs, $nondirs) = @_;
		810
		811	my $dirgrp = aio_group sub {
		812	add $grp aio_rmdir $path, sub {
		813	$grp->result ($_[0]);
		814	};
		815	};
		816
		817	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		818	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		819
		820	add $grp $dirgrp;
		821	};
		822
		823	$grp
		824	}
482	}	825	}
483		826
484	=item aio_fsync $fh, $callback->($status)	827	=item aio_fsync $fh, $callback->($status)
485		828
486	Asynchronously call fsync on the given filehandle and call the callback	829	Asynchronously call fsync on the given filehandle and call the callback
…		…
492	callback with the fdatasync result code.	835	callback with the fdatasync result code.
493		836
494	If this call isn't available because your OS lacks it or it couldn't be	837	If this call isn't available because your OS lacks it or it couldn't be
495	detected, it will be emulated by calling C<fsync> instead.	838	detected, it will be emulated by calling C<fsync> instead.
496		839
		840	=item aio_group $callback->(...)
		841
		842	This is a very special aio request: Instead of doing something, it is a
		843	container for other aio requests, which is useful if you want to bundle
		844	many requests into a single, composite, request with a definite callback
		845	and the ability to cancel the whole request with its subrequests.
		846
		847	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		848	for more info.
		849
		850	Example:
		851
		852	my $grp = aio_group sub {
		853	print "all stats done\n";
		854	};
		855
		856	add $grp
		857	(aio_stat ...),
		858	(aio_stat ...),
		859	...;
		860
		861	=item aio_nop $callback->()
		862
		863	This is a special request - it does nothing in itself and is only used for
		864	side effects, such as when you want to add a dummy request to a group so
		865	that finishing the requests in the group depends on executing the given
		866	code.
		867
		868	While this request does nothing, it still goes through the execution
		869	phase and still requires a worker thread. Thus, the callback will not
		870	be executed immediately but only after other requests in the queue have
		871	entered their execution phase. This can be used to measure request
		872	latency.
		873
		874	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
		875
		876	Mainly used for debugging and benchmarking, this aio request puts one of
		877	the request workers to sleep for the given time.
		878
		879	While it is theoretically handy to have simple I/O scheduling requests
		880	like sleep and file handle readable/writable, the overhead this creates is
		881	immense (it blocks a thread for a long time) so do not use this function
		882	except to put your application under artificial I/O pressure.
		883
497	=back	884	=back
498		885
499	=head2 IO::AIO::CB CLASS	886	=head2 IO::AIO::REQ CLASS
500		887
501	All non-aggregate C<aio_*> functions return an object of this class when	888	All non-aggregate C<aio_*> functions return an object of this class when
502	called in non-void context.	889	called in non-void context.
503		890
504	A request always moves through the following five states in its lifetime,
505	in order: B<ready> (request has been created, but has not been executed
506	yet), B<execute> (request is currently being executed), B<pending>
507	(request has been executed but callback has not been called yet),
508	B<result> (results are being processed synchronously, includes calling the
509	callback) and B<done> (request has reached the end of its lifetime and
510	holds no resources anymore).
511
512	=over 4	891	=over 4
513		892
514	=item $req->cancel	893	=item cancel $req
515		894
516	Cancels the request, if possible. Has the effect of skipping execution	895	Cancels the request, if possible. Has the effect of skipping execution
517	when entering the B<execute> state and skipping calling the callback when	896	when entering the B<execute> state and skipping calling the callback when
518	entering the the B<result> state, but will leave the request otherwise	897	entering the the B<result> state, but will leave the request otherwise
519	untouched. That means that requests that currently execute will not be	898	untouched. That means that requests that currently execute will not be
520	stopped and resources held by the request will not be freed prematurely.	899	stopped and resources held by the request will not be freed prematurely.
521		900
		901	=item cb $req $callback->(...)
		902
		903	Replace (or simply set) the callback registered to the request.
		904
522	=back	905	=back
523		906
		907	=head2 IO::AIO::GRP CLASS
		908
		909	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		910	objects of this class, too.
		911
		912	A IO::AIO::GRP object is a special request that can contain multiple other
		913	aio requests.
		914
		915	You create one by calling the C<aio_group> constructing function with a
		916	callback that will be called when all contained requests have entered the
		917	C<done> state:
		918
		919	my $grp = aio_group sub {
		920	print "all requests are done\n";
		921	};
		922
		923	You add requests by calling the C<add> method with one or more
		924	C<IO::AIO::REQ> objects:
		925
		926	$grp->add (aio_unlink "...");
		927
		928	add $grp aio_stat "...", sub {
		929	$_[0] or return $grp->result ("error");
		930
		931	# add another request dynamically, if first succeeded
		932	add $grp aio_open "...", sub {
		933	$grp->result ("ok");
		934	};
		935	};
		936
		937	This makes it very easy to create composite requests (see the source of
		938	C<aio_move> for an application) that work and feel like simple requests.
		939
		940	=over 4
		941
		942	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		943	C<IO::AIO::poll_cb>, just like any other request.
		944
		945	=item * They can be canceled like any other request. Canceling will cancel not
		946	only the request itself, but also all requests it contains.
		947
		948	=item * They can also can also be added to other IO::AIO::GRP objects.
		949
		950	=item * You must not add requests to a group from within the group callback (or
		951	any later time).
		952
		953	=back
		954
		955	Their lifetime, simplified, looks like this: when they are empty, they
		956	will finish very quickly. If they contain only requests that are in the
		957	C<done> state, they will also finish. Otherwise they will continue to
		958	exist.
		959
		960	That means after creating a group you have some time to add requests. And
		961	in the callbacks of those requests, you can add further requests to the
		962	group. And only when all those requests have finished will the the group
		963	itself finish.
		964
		965	=over 4
		966
		967	=item add $grp ...
		968
		969	=item $grp->add (...)
		970
		971	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		972	be added, including other groups, as long as you do not create circular
		973	dependencies.
		974
		975	Returns all its arguments.
		976
		977	=item $grp->cancel_subs
		978
		979	Cancel all subrequests and clears any feeder, but not the group request
		980	itself. Useful when you queued a lot of events but got a result early.
		981
		982	=item $grp->result (...)
		983
		984	Set the result value(s) that will be passed to the group callback when all
		985	subrequests have finished and set thre groups errno to the current value
		986	of errno (just like calling C<errno> without an error number). By default,
		987	no argument will be passed and errno is zero.
		988
		989	=item $grp->errno ([$errno])
		990
		991	Sets the group errno value to C<$errno>, or the current value of errno
		992	when the argument is missing.
		993
		994	Every aio request has an associated errno value that is restored when
		995	the callback is invoked. This method lets you change this value from its
		996	default (0).
		997
		998	Calling C<result> will also set errno, so make sure you either set C<$!>
		999	before the call to C<result>, or call c<errno> after it.
		1000
		1001	=item feed $grp $callback->($grp)
		1002
		1003	Sets a feeder/generator on this group: every group can have an attached
		1004	generator that generates requests if idle. The idea behind this is that,
		1005	although you could just queue as many requests as you want in a group,
		1006	this might starve other requests for a potentially long time. For
		1007	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		1008	requests, delaying any later requests for a long time.
		1009
		1010	To avoid this, and allow incremental generation of requests, you can
		1011	instead a group and set a feeder on it that generates those requests. The
		1012	feed callback will be called whenever there are few enough (see C<limit>,
		1013	below) requests active in the group itself and is expected to queue more
		1014	requests.
		1015
		1016	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1017	not impose any limits).
		1018
		1019	If the feed does not queue more requests when called, it will be
		1020	automatically removed from the group.
		1021
		1022	If the feed limit is C<0>, it will be set to C<2> automatically.
		1023
		1024	Example:
		1025
		1026	# stat all files in @files, but only ever use four aio requests concurrently:
		1027
		1028	my $grp = aio_group sub { print "finished\n" };
		1029	limit $grp 4;
		1030	feed $grp sub {
		1031	my $file = pop @files
		1032	or return;
		1033
		1034	add $grp aio_stat $file, sub { ... };
		1035	};
		1036
		1037	=item limit $grp $num
		1038
		1039	Sets the feeder limit for the group: The feeder will be called whenever
		1040	the group contains less than this many requests.
		1041
		1042	Setting the limit to C<0> will pause the feeding process.
		1043
		1044	=back
		1045
524	=head2 SUPPORT FUNCTIONS	1046	=head2 SUPPORT FUNCTIONS
		1047
		1048	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
525		1049
526	=over 4	1050	=over 4
527		1051
528	=item $fileno = IO::AIO::poll_fileno	1052	=item $fileno = IO::AIO::poll_fileno
529		1053
…		…
534		1058
535	See C<poll_cb> for an example.	1059	See C<poll_cb> for an example.
536		1060
537	=item IO::AIO::poll_cb	1061	=item IO::AIO::poll_cb
538		1062
539	Process all outstanding events on the result pipe. You have to call this	1063	Process some outstanding events on the result pipe. You have to call this
540	regularly. Returns the number of events processed. Returns immediately	1064	regularly. Returns the number of events processed. Returns immediately
541	when no events are outstanding.	1065	when no events are outstanding. The amount of events processed depends on
		1066	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1067
		1068	If not all requests were processed for whatever reason, the filehandle
		1069	will still be ready when C<poll_cb> returns.
542		1070
543	Example: Install an Event watcher that automatically calls	1071	Example: Install an Event watcher that automatically calls
544	IO::AIO::poll_cb with high priority:	1072	IO::AIO::poll_cb with high priority:
545		1073
546	Event->io (fd => IO::AIO::poll_fileno,	1074	Event->io (fd => IO::AIO::poll_fileno,
547	poll => 'r', async => 1,	1075	poll => 'r', async => 1,
548	cb => \&IO::AIO::poll_cb);	1076	cb => \&IO::AIO::poll_cb);
549		1077
		1078	=item IO::AIO::max_poll_reqs $nreqs
		1079
		1080	=item IO::AIO::max_poll_time $seconds
		1081
		1082	These set the maximum number of requests (default C<0>, meaning infinity)
		1083	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1084	the maximum amount of time (default C<0>, meaning infinity) spent in
		1085	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1086	of time C<poll_cb> is allowed to use).
		1087
		1088	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1089	syscall per request processed, which is not normally a problem unless your
		1090	callbacks are really really fast or your OS is really really slow (I am
		1091	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1092
		1093	Setting these is useful if you want to ensure some level of
		1094	interactiveness when perl is not fast enough to process all requests in
		1095	time.
		1096
		1097	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1098
		1099	Example: Install an Event watcher that automatically calls
		1100	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1101	program get the CPU sometimes even under high AIO load.
		1102
		1103	# try not to spend much more than 0.1s in poll_cb
		1104	IO::AIO::max_poll_time 0.1;
		1105
		1106	# use a low priority so other tasks have priority
		1107	Event->io (fd => IO::AIO::poll_fileno,
		1108	poll => 'r', nice => 1,
		1109	cb => &IO::AIO::poll_cb);
		1110
550	=item IO::AIO::poll_wait	1111	=item IO::AIO::poll_wait
551		1112
		1113	If there are any outstanding requests and none of them in the result
552	Wait till the result filehandle becomes ready for reading (simply does a	1114	phase, wait till the result filehandle becomes ready for reading (simply
553	C<select> on the filehandle. This is useful if you want to synchronously wait	1115	does a C<select> on the filehandle. This is useful if you want to
554	for some requests to finish).	1116	synchronously wait for some requests to finish).
555		1117
556	See C<nreqs> for an example.	1118	See C<nreqs> for an example.
557		1119
		1120	=item IO::AIO::poll
		1121
		1122	Waits until some requests have been handled.
		1123
		1124	Returns the number of requests processed, but is otherwise strictly
		1125	equivalent to:
		1126
		1127	IO::AIO::poll_wait, IO::AIO::poll_cb
		1128
558	=item IO::AIO::nreqs	1129	=item IO::AIO::flush
559		1130
560	Returns the number of requests currently outstanding (i.e. for which their	1131	Wait till all outstanding AIO requests have been handled.
561	callback has not been invoked yet).
562		1132
563	Example: wait till there are no outstanding requests anymore:	1133	Strictly equivalent to:
564		1134
565	IO::AIO::poll_wait, IO::AIO::poll_cb	1135	IO::AIO::poll_wait, IO::AIO::poll_cb
566	while IO::AIO::nreqs;	1136	while IO::AIO::nreqs;
567		1137
568	=item IO::AIO::flush	1138	=back
569		1139
570	Wait till all outstanding AIO requests have been handled.	1140	=head3 CONTROLLING THE NUMBER OF THREADS
571		1141
572	Strictly equivalent to:	1142	=over
573
574	IO::AIO::poll_wait, IO::AIO::poll_cb
575	while IO::AIO::nreqs;
576
577	=item IO::AIO::poll
578
579	Waits until some requests have been handled.
580
581	Strictly equivalent to:
582
583	IO::AIO::poll_wait, IO::AIO::poll_cb
584	if IO::AIO::nreqs;
585		1143
586	=item IO::AIO::min_parallel $nthreads	1144	=item IO::AIO::min_parallel $nthreads
587		1145
588	Set the minimum number of AIO threads to C<$nthreads>. The current default	1146	Set the minimum number of AIO threads to C<$nthreads>. The current
589	is C<4>, which means four asynchronous operations can be done at one time	1147	default is C<8>, which means eight asynchronous operations can execute
590	(the number of outstanding operations, however, is unlimited).	1148	concurrently at any one time (the number of outstanding requests,
		1149	however, is unlimited).
591		1150
592	IO::AIO starts threads only on demand, when an AIO request is queued and	1151	IO::AIO starts threads only on demand, when an AIO request is queued and
593	no free thread exists.	1152	no free thread exists. Please note that queueing up a hundred requests can
		1153	create demand for a hundred threads, even if it turns out that everything
		1154	is in the cache and could have been processed faster by a single thread.
594		1155
595	It is recommended to keep the number of threads low, as some Linux	1156	It is recommended to keep the number of threads relatively low, as some
596	kernel versions will scale negatively with the number of threads (higher	1157	Linux kernel versions will scale negatively with the number of threads
597	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1158	(higher parallelity => MUCH higher latency). With current Linux 2.6
598	threads should be fine.	1159	versions, 4-32 threads should be fine.
599		1160
600	Under most circumstances you don't need to call this function, as the	1161	Under most circumstances you don't need to call this function, as the
601	module selects a default that is suitable for low to moderate load.	1162	module selects a default that is suitable for low to moderate load.
602		1163
603	=item IO::AIO::max_parallel $nthreads	1164	=item IO::AIO::max_parallel $nthreads
…		…
612	This module automatically runs C<max_parallel 0> at program end, to ensure	1173	This module automatically runs C<max_parallel 0> at program end, to ensure
613	that all threads are killed and that there are no outstanding requests.	1174	that all threads are killed and that there are no outstanding requests.
614		1175
615	Under normal circumstances you don't need to call this function.	1176	Under normal circumstances you don't need to call this function.
616		1177
		1178	=item IO::AIO::max_idle $nthreads
		1179
		1180	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1181	threads that did not get a request to process within 10 seconds). That
		1182	means if a thread becomes idle while C<$nthreads> other threads are also
		1183	idle, it will free its resources and exit.
		1184
		1185	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1186	to allow for extremely high load situations, but want to free resources
		1187	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1188
		1189	The default is probably ok in most situations, especially if thread
		1190	creation is fast. If thread creation is very slow on your system you might
		1191	want to use larger values.
		1192
617	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1193	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1194
		1195	This is a very bad function to use in interactive programs because it
		1196	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1197	use an C<aio_group> together with a feed callback.
618		1198
619	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1199	Sets the maximum number of outstanding requests to C<$nreqs>. If you
620	try to queue up more than this number of requests, the caller will block until	1200	to queue up more than this number of requests, the next call to the
621	some requests have been handled.	1201	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1202	function will block until the limit is no longer exceeded.
622		1203
623	The default is very large, so normally there is no practical limit. If you	1204	The default value is very large, so there is no practical limit on the
624	queue up many requests in a loop it often improves speed if you set	1205	number of outstanding requests.
625	this to a relatively low number, such as C<100>.
626		1206
627	Under normal circumstances you don't need to call this function.	1207	You can still queue as many requests as you want. Therefore,
		1208	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1209	as a stop gap to shield against fatal memory overflow (with large values).
		1210
		1211	=back
		1212
		1213	=head3 STATISTICAL INFORMATION
		1214
		1215	=over
		1216
		1217	=item IO::AIO::nreqs
		1218
		1219	Returns the number of requests currently in the ready, execute or pending
		1220	states (i.e. for which their callback has not been invoked yet).
		1221
		1222	Example: wait till there are no outstanding requests anymore:
		1223
		1224	IO::AIO::poll_wait, IO::AIO::poll_cb
		1225	while IO::AIO::nreqs;
		1226
		1227	=item IO::AIO::nready
		1228
		1229	Returns the number of requests currently in the ready state (not yet
		1230	executed).
		1231
		1232	=item IO::AIO::npending
		1233
		1234	Returns the number of requests currently in the pending state (executed,
		1235	but not yet processed by poll_cb).
628		1236
629	=back	1237	=back
630		1238
631	=cut	1239	=cut
632		1240
…		…
644	or return undef;	1252	or return undef;
645		1253
646	*$sym	1254	*$sym
647	}	1255	}
648		1256
649	min_parallel 4;	1257	min_parallel 8;
650		1258
651	END {	1259	END { flush }
652	max_parallel 0;
653	}
654		1260
655	1;	1261	1;
656		1262
657	=head2 FORK BEHAVIOUR	1263	=head2 FORK BEHAVIOUR
658		1264
659	This module should do "the right thing" when the process using it forks:	1265	This module should do "the right thing" when the process using it forks:
660		1266
661	Before the fork, IO::AIO enters a quiescent state where no requests	1267	Before the fork, IO::AIO enters a quiescent state where no requests
662	can be added in other threads and no results will be processed. After	1268	can be added in other threads and no results will be processed. After
663	the fork the parent simply leaves the quiescent state and continues	1269	the fork the parent simply leaves the quiescent state and continues
664	request/result processing, while the child clears the request/result	1270	request/result processing, while the child frees the request/result queue
665	queue (so the requests started before the fork will only be handled in	1271	(so that the requests started before the fork will only be handled in the
666	the parent). Threads will be started on demand until the limit ste in the	1272	parent). Threads will be started on demand until the limit set in the
667	parent process has been reached again.	1273	parent process has been reached again.
668		1274
669	In short: the parent will, after a short pause, continue as if fork had	1275	In short: the parent will, after a short pause, continue as if fork had
670	not been called, while the child will act as if IO::AIO has not been used	1276	not been called, while the child will act as if IO::AIO has not been used
671	yet.	1277	yet.
672		1278
		1279	=head2 MEMORY USAGE
		1280
		1281	Per-request usage:
		1282
		1283	Each aio request uses - depending on your architecture - around 100-200
		1284	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1285	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1286	scalars and other data passed into aio requests will also be locked and
		1287	will consume memory till the request has entered the done state.
		1288
		1289	This is now awfully much, so queuing lots of requests is not usually a
		1290	problem.
		1291
		1292	Per-thread usage:
		1293
		1294	In the execution phase, some aio requests require more memory for
		1295	temporary buffers, and each thread requires a stack and other data
		1296	structures (usually around 16k-128k, depending on the OS).
		1297
		1298	=head1 KNOWN BUGS
		1299
		1300	Known bugs will be fixed in the next release.
		1301
673	=head1 SEE ALSO	1302	=head1 SEE ALSO
674		1303
675	L<Coro>, L<Linux::AIO> (obsolete).	1304	L<Coro::AIO>.
676		1305
677	=head1 AUTHOR	1306	=head1 AUTHOR
678		1307
679	Marc Lehmann <schmorp@schmorp.de>	1308	Marc Lehmann <schmorp@schmorp.de>
680	http://home.schmorp.de/	1309	http://home.schmorp.de/

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