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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC vs.
Revision 1.103 by root, Tue Jan 23 22:57:34 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 example
		68	sockets), using these functions on file descriptors that support
		69	nonblocking operation (again, sockets, pipes etc.) is very inefficient or
		70	might not work (aio_read fails on sockets/pipes/fifos). Use an event loop
		71	for that (such as the L<Event\|Event> module): IO::AIO will naturally fit
		72	into such an event loop itself.
		73
52	Currently, a number of threads are started that execute your read/writes	74	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	75	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	76	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	77	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	78	functions available on many operating systems. However, they are often
57	not well-supported (Linux doesn't allow them on normal files currently,	79	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	80	files currently, for example), and they would only support aio_read and
59	remaining functionality would have to be implemented using threads anyway.	81	aio_write, so the remaining functionality would have to be implemented
		82	using threads anyway.
60		83
61	Although the module will work with in the presence of other threads, it is	84	Although the module will work with in the presence of other (Perl-)
62	currently not reentrant, so use appropriate locking yourself, always call	85	threads, it is currently not reentrant in any way, so use appropriate
63	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	86	locking yourself, always call C<poll_cb> from within the same thread, or
64	C<aio_> functions) recursively.	87	never call C<poll_cb> (or other C<aio_> functions) recursively.
		88
		89	=head2 EXAMPLE
		90
		91	This is a simple example that uses the Event module and loads
		92	F</etc/passwd> asynchronously:
		93
		94	use Fcntl;
		95	use Event;
		96	use IO::AIO;
		97
		98	# register the IO::AIO callback with Event
		99	Event->io (fd => IO::AIO::poll_fileno,
		100	poll => 'r',
		101	cb => \&IO::AIO::poll_cb);
		102
		103	# queue the request to open /etc/passwd
		104	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		105	my $fh = shift
		106	or die "error while opening: $!";
		107
		108	# stat'ing filehandles is generally non-blocking
		109	my $size = -s $fh;
		110
		111	# queue a request to read the file
		112	my $contents;
		113	aio_read $fh, 0, $size, $contents, 0, sub {
		114	$_[0] == $size
		115	or die "short read: $!";
		116
		117	close $fh;
		118
		119	# file contents now in $contents
		120	print $contents;
		121
		122	# exit event loop and program
		123	Event::unloop;
		124	};
		125	};
		126
		127	# possibly queue up other requests, or open GUI windows,
		128	# check for sockets etc. etc.
		129
		130	# process events as long as there are some:
		131	Event::loop;
		132
		133	=head1 REQUEST ANATOMY AND LIFETIME
		134
		135	Every C<aio_*> function creates a request. which is a C data structure not
		136	directly visible to Perl.
		137
		138	If called in non-void context, every request function returns a Perl
		139	object representing the request. In void context, nothing is returned,
		140	which saves a bit of memory.
		141
		142	The perl object is a fairly standard ref-to-hash object. The hash contents
		143	are not used by IO::AIO so you are free to store anything you like in it.
		144
		145	During their existance, aio requests travel through the following states,
		146	in order:
		147
		148	=over 4
		149
		150	=item ready
		151
		152	Immediately after a request is created it is put into the ready state,
		153	waiting for a thread to execute it.
		154
		155	=item execute
		156
		157	A thread has accepted the request for processing and is currently
		158	executing it (e.g. blocking in read).
		159
		160	=item pending
		161
		162	The request has been executed and is waiting for result processing.
		163
		164	While request submission and execution is fully asynchronous, result
		165	processing is not and relies on the perl interpreter calling C<poll_cb>
		166	(or another function with the same effect).
		167
		168	=item result
		169
		170	The request results are processed synchronously by C<poll_cb>.
		171
		172	The C<poll_cb> function will process all outstanding aio requests by
		173	calling their callbacks, freeing memory associated with them and managing
		174	any groups they are contained in.
		175
		176	=item done
		177
		178	Request has reached the end of its lifetime and holds no resources anymore
		179	(except possibly for the Perl object, but its connection to the actual
		180	aio request is severed and calling its methods will either do nothing or
		181	result in a runtime error).
		182
		183	=back
65		184
66	=cut	185	=cut
67		186
68	package IO::AIO;	187	package IO::AIO;
69		188
…		…
71	use strict 'vars';	190	use strict 'vars';
72		191
73	use base 'Exporter';	192	use base 'Exporter';
74		193
75	BEGIN {	194	BEGIN {
76	our $VERSION = '1.99';	195	our $VERSION = '2.33';
77		196
78	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	197	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	198	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	199	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
81	aio_group);	200	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);	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 non-composite requests (requests that are not broken down into
106	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
107	further manipulation of running requests.	229	further manipulation of those requests while they are in-flight.
108		230
109	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
110	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
111	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
112	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
113	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
114		237
115	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
116	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
117	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
118	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
119	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)
120	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.
121		247
122	=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	=item aioreq_nice $pri_adjust
		277
		278	Similar to C<aioreq_pri>, but subtracts the given value from the current
		279	priority, so the effect is cumulative.
123		280
124	=item aio_open $pathname, $flags, $mode, $callback->($fh)	281	=item aio_open $pathname, $flags, $mode, $callback->($fh)
125		282
126	Asynchronously open or create a file and call the callback with a newly	283	Asynchronously open or create a file and call the callback with a newly
127	created filehandle for the file.	284	created filehandle for the file.
…		…
133	list. They are the same as used by C<sysopen>.	290	list. They are the same as used by C<sysopen>.
134		291
135	Likewise, C<$mode> specifies the mode of the newly created file, if it	292	Likewise, C<$mode> specifies the mode of the newly created file, if it
136	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	293	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
137	except that it is mandatory (i.e. use C<0> if you don't create new files,	294	except that it is mandatory (i.e. use C<0> if you don't create new files,
138	and C<0666> or C<0777> if you do).	295	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		296	by the umask in effect then the request is being executed, so better never
		297	change the umask.
139		298
140	Example:	299	Example:
141		300
142	aio_open "/etc/passwd", O_RDONLY, 0, sub {	301	aio_open "/etc/passwd", O_RDONLY, 0, sub {
143	if ($_[0]) {	302	if ($_[0]) {
…		…
178	aio_read $fh, 7, 15, $buffer, 0, sub {	337	aio_read $fh, 7, 15, $buffer, 0, sub {
179	$_[0] > 0 or die "read error: $!";	338	$_[0] > 0 or die "read error: $!";
180	print "read $_[0] bytes: <$buffer>\n";	339	print "read $_[0] bytes: <$buffer>\n";
181	};	340	};
182		341
183	=item aio_move $srcpath, $dstpath, $callback->($status)
184
185	Try to move the I<file> (directories not supported as either source or
186	destination) from C<$srcpath> to C<$dstpath> and call the callback with
187	the C<0> (error) or C<-1> ok.
188
189	This is a composite request that tries to rename(2) the file first. If
190	rename files with C<EXDEV>, it creates the destination file with mode 0200
191	and copies the contents of the source file into it using C<aio_sendfile>,
192	followed by restoring atime, mtime, access mode and uid/gid, in that
193	order, and unlinking the C<$srcpath>.
194
195	If an error occurs, the partial destination file will be unlinked, if
196	possible, except when setting atime, mtime, access mode and uid/gid, where
197	errors are being ignored.
198
199	=cut
200
201	sub aio_move($$$) {
202	my ($src, $dst, $cb) = @_;
203
204	aio_rename $src, $dst, sub {
205	if ($_[0] && $! == EXDEV) {
206	aio_open $src, O_RDONLY, 0, sub {
207	if (my $src_fh = $_[0]) {
208	my @stat = stat $src_fh;
209
210	aio_open $dst, O_WRONLY, 0200, sub {
211	if (my $dst_fh = $_[0]) {
212	aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
213	close $src_fh;
214
215	if ($_[0] == $stat[7]) {
216	utime $stat[8], $stat[9], $dst;
217	chmod $stat[2] & 07777, $dst_fh;
218	chown $stat[4], $stat[5], $dst_fh;
219	close $dst_fh;
220
221	aio_unlink $src, sub {
222	$cb->($_[0]);
223	};
224	} else {
225	my $errno = $!;
226	aio_unlink $dst, sub {
227	$! = $errno;
228	$cb->(-1);
229	};
230	}
231	};
232	} else {
233	$cb->(-1);
234	}
235	},
236
237	} else {
238	$cb->(-1);
239	}
240	};
241	} else {
242	$cb->($_[0]);
243	}
244	};
245	}
246
247	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	342	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
248		343
249	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	344	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
250	reading at byte offset C<$in_offset>, and starts writing at the current	345	reading at byte offset C<$in_offset>, and starts writing at the current
251	file offset of C<$out_fh>. Because of that, it is not safe to issue more	346	file offset of C<$out_fh>. Because of that, it is not safe to issue more
…		…
306	=item aio_unlink $pathname, $callback->($status)	401	=item aio_unlink $pathname, $callback->($status)
307		402
308	Asynchronously unlink (delete) a file and call the callback with the	403	Asynchronously unlink (delete) a file and call the callback with the
309	result code.	404	result code.
310		405
		406	=item aio_mknod $path, $mode, $dev, $callback->($status)
		407
		408	[EXPERIMENTAL]
		409
		410	Asynchronously create a device node (or fifo). See mknod(2).
		411
		412	The only (POSIX-) portable way of calling this function is:
		413
		414	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		415
311	=item aio_link $srcpath, $dstpath, $callback->($status)	416	=item aio_link $srcpath, $dstpath, $callback->($status)
312		417
313	Asynchronously create a new link to the existing object at C<$srcpath> at	418	Asynchronously create a new link to the existing object at C<$srcpath> at
314	the path C<$dstpath> and call the callback with the result code.	419	the path C<$dstpath> and call the callback with the result code.
315		420
316	=item aio_symlink $srcpath, $dstpath, $callback->($status)	421	=item aio_symlink $srcpath, $dstpath, $callback->($status)
317		422
318	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	423	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
319	the path C<$dstpath> and call the callback with the result code.	424	the path C<$dstpath> and call the callback with the result code.
320		425
		426	=item aio_readlink $path, $callback->($link)
		427
		428	Asynchronously read the symlink specified by C<$path> and pass it to
		429	the callback. If an error occurs, nothing or undef gets passed to the
		430	callback.
		431
321	=item aio_rename $srcpath, $dstpath, $callback->($status)	432	=item aio_rename $srcpath, $dstpath, $callback->($status)
322		433
323	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	434	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
324	rename(2) and call the callback with the result code.	435	rename(2) and call the callback with the result code.
		436
		437	=item aio_mkdir $pathname, $mode, $callback->($status)
		438
		439	Asynchronously mkdir (create) a directory and call the callback with
		440	the result code. C<$mode> will be modified by the umask at the time the
		441	request is executed, so do not change your umask.
325		442
326	=item aio_rmdir $pathname, $callback->($status)	443	=item aio_rmdir $pathname, $callback->($status)
327		444
328	Asynchronously rmdir (delete) a directory and call the callback with the	445	Asynchronously rmdir (delete) a directory and call the callback with the
329	result code.	446	result code.
…		…
335	sorted, and will B<NOT> include the C<.> and C<..> entries.	452	sorted, and will B<NOT> include the C<.> and C<..> entries.
336		453
337	The callback a single argument which is either C<undef> or an array-ref	454	The callback a single argument which is either C<undef> or an array-ref
338	with the filenames.	455	with the filenames.
339		456
		457	=item aio_load $path, $data, $callback->($status)
		458
		459	This is a composite request that tries to fully load the given file into
		460	memory. Status is the same as with aio_read.
		461
		462	=cut
		463
		464	sub aio_load($$;$) {
		465	aio_block {
		466	my ($path, undef, $cb) = @_;
		467	my $data = \$_[1];
		468
		469	my $pri = aioreq_pri;
		470	my $grp = aio_group $cb;
		471
		472	aioreq_pri $pri;
		473	add $grp aio_open $path, O_RDONLY, 0, sub {
		474	my $fh = shift
		475	or return $grp->result (-1);
		476
		477	aioreq_pri $pri;
		478	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		479	$grp->result ($_[0]);
		480	};
		481	};
		482
		483	$grp
		484	}
		485	}
		486
		487	=item aio_copy $srcpath, $dstpath, $callback->($status)
		488
		489	Try to copy the I<file> (directories not supported as either source or
		490	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		491	the C<0> (error) or C<-1> ok.
		492
		493	This is a composite request that it creates the destination file with
		494	mode 0200 and copies the contents of the source file into it using
		495	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		496	uid/gid, in that order.
		497
		498	If an error occurs, the partial destination file will be unlinked, if
		499	possible, except when setting atime, mtime, access mode and uid/gid, where
		500	errors are being ignored.
		501
		502	=cut
		503
		504	sub aio_copy($$;$) {
		505	aio_block {
		506	my ($src, $dst, $cb) = @_;
		507
		508	my $pri = aioreq_pri;
		509	my $grp = aio_group $cb;
		510
		511	aioreq_pri $pri;
		512	add $grp aio_open $src, O_RDONLY, 0, sub {
		513	if (my $src_fh = $_[0]) {
		514	my @stat = stat $src_fh;
		515
		516	aioreq_pri $pri;
		517	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		518	if (my $dst_fh = $_[0]) {
		519	aioreq_pri $pri;
		520	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		521	if ($_[0] == $stat[7]) {
		522	$grp->result (0);
		523	close $src_fh;
		524
		525	# those should not normally block. should. should.
		526	utime $stat[8], $stat[9], $dst;
		527	chmod $stat[2] & 07777, $dst_fh;
		528	chown $stat[4], $stat[5], $dst_fh;
		529	close $dst_fh;
		530	} else {
		531	$grp->result (-1);
		532	close $src_fh;
		533	close $dst_fh;
		534
		535	aioreq $pri;
		536	add $grp aio_unlink $dst;
		537	}
		538	};
		539	} else {
		540	$grp->result (-1);
		541	}
		542	},
		543
		544	} else {
		545	$grp->result (-1);
		546	}
		547	};
		548
		549	$grp
		550	}
		551	}
		552
		553	=item aio_move $srcpath, $dstpath, $callback->($status)
		554
		555	Try to move the I<file> (directories not supported as either source or
		556	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		557	the C<0> (error) or C<-1> ok.
		558
		559	This is a composite request that tries to rename(2) the file first. If
		560	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		561	that is successful, unlinking the C<$srcpath>.
		562
		563	=cut
		564
		565	sub aio_move($$;$) {
		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_rename $src, $dst, sub {
		574	if ($_[0] && $! == EXDEV) {
		575	aioreq_pri $pri;
		576	add $grp aio_copy $src, $dst, sub {
		577	$grp->result ($_[0]);
		578
		579	if (!$_[0]) {
		580	aioreq_pri $pri;
		581	add $grp aio_unlink $src;
		582	}
		583	};
		584	} else {
		585	$grp->result ($_[0]);
		586	}
		587	};
		588
		589	$grp
		590	}
		591	}
		592
340	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	593	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
341		594
342	Scans a directory (similar to C<aio_readdir>) but additionally tries to	595	Scans a directory (similar to C<aio_readdir>) but additionally tries to
343	separate the entries of directory C<$path> into two sets of names, ones	596	efficiently separate the entries of directory C<$path> into two sets of
344	you can recurse into (directories or links to them), and ones you cannot	597	names, directories you can recurse into (directories), and ones you cannot
345	recurse into (everything else).	598	recurse into (everything else, including symlinks to directories).
346		599
347	C<aio_scandir> is a composite request that consists of many sub	600	C<aio_scandir> is a composite request that creates of many sub requests_
348	requests. C<$maxreq> specifies the maximum number of outstanding aio	601	C<$maxreq> specifies the maximum number of outstanding aio requests that
349	requests that this function generates. If it is C<< <= 0 >>, then a	602	this function generates. If it is C<< <= 0 >>, then a suitable default
350	suitable default will be chosen (currently 8).	603	will be chosen (currently 4).
351		604
352	On error, the callback is called without arguments, otherwise it receives	605	On error, the callback is called without arguments, otherwise it receives
353	two array-refs with path-relative entry names.	606	two array-refs with path-relative entry names.
354		607
355	Example:	608	Example:
…		…
389	as those tend to return 0 or 1 as link counts, which disables the	642	as those tend to return 0 or 1 as link counts, which disables the
390	directory counting heuristic.	643	directory counting heuristic.
391		644
392	=cut	645	=cut
393		646
394	sub aio_scandir($$$) {	647	sub aio_scandir($$;$) {
		648	aio_block {
395	my ($path, $maxreq, $cb) = @_;	649	my ($path, $maxreq, $cb) = @_;
396		650
		651	my $pri = aioreq_pri;
		652
		653	my $grp = aio_group $cb;
		654
397	$maxreq = 8 if $maxreq <= 0;	655	$maxreq = 4 if $maxreq <= 0;
398		656
399	# stat once	657	# stat once
		658	aioreq_pri $pri;
400	aio_stat $path, sub {	659	add $grp aio_stat $path, sub {
401	return $cb->() if $_[0];	660	return $grp->result () if $_[0];
402	my $now = time;	661	my $now = time;
403	my $hash1 = join ":", (stat _)[0,1,3,7,9];	662	my $hash1 = join ":", (stat _)[0,1,3,7,9];
404		663
405	# read the directory entries	664	# read the directory entries
		665	aioreq_pri $pri;
406	aio_readdir $path, sub {	666	add $grp aio_readdir $path, sub {
407	my $entries = shift	667	my $entries = shift
408	or return $cb->();	668	or return $grp->result ();
409		669
410	# stat the dir another time	670	# stat the dir another time
		671	aioreq_pri $pri;
411	aio_stat $path, sub {	672	add $grp aio_stat $path, sub {
412	my $hash2 = join ":", (stat _)[0,1,3,7,9];	673	my $hash2 = join ":", (stat _)[0,1,3,7,9];
413		674
414	my $ndirs;	675	my $ndirs;
415		676
416	# take the slow route if anything looks fishy	677	# take the slow route if anything looks fishy
417	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	678	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
418	$ndirs = -1;	679	$ndirs = -1;
419	} else {	680	} else {
420	# if nlink == 2, we are finished	681	# if nlink == 2, we are finished
421	# on non-posix-fs's, we rely on nlink < 2	682	# on non-posix-fs's, we rely on nlink < 2
422	$ndirs = (stat _)[3] - 2	683	$ndirs = (stat _)[3] - 2
423	or return $cb->([], $entries);	684	or return $grp->result ([], $entries);
424	}
425
426	# sort into likely dirs and likely nondirs
427	# dirs == files without ".", short entries first
428	$entries = [map $_->[0],
429	sort { $b->[1] cmp $a->[1] }
430	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
431	@$entries];
432
433	my (@dirs, @nondirs);
434
435	my ($statcb, $schedcb);
436	my $nreq = 0;
437
438	$schedcb = sub {
439	if (@$entries) {
440	if ($nreq < $maxreq) {
441	my $ent = pop @$entries;
442	$nreq++;
443	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
444	}
445	} elsif (!$nreq) {
446	# finished
447	undef $statcb;
448	undef $schedcb;
449	$cb->(\@dirs, \@nondirs) if $cb;
450	undef $cb;
451	}	685	}
		686
		687	# sort into likely dirs and likely nondirs
		688	# dirs == files without ".", short entries first
		689	$entries = [map $_->[0],
		690	sort { $b->[1] cmp $a->[1] }
		691	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		692	@$entries];
		693
		694	my (@dirs, @nondirs);
		695
		696	my $statgrp = add $grp aio_group sub {
		697	$grp->result (\@dirs, \@nondirs);
		698	};
		699
		700	limit $statgrp $maxreq;
		701	feed $statgrp sub {
		702	return unless @$entries;
		703	my $entry = pop @$entries;
		704
		705	aioreq_pri $pri;
		706	add $statgrp aio_stat "$path/$entry/.", sub {
		707	if ($_[0] < 0) {
		708	push @nondirs, $entry;
		709	} else {
		710	# need to check for real directory
		711	aioreq_pri $pri;
		712	add $statgrp aio_lstat "$path/$entry", sub {
		713	if (-d _) {
		714	push @dirs, $entry;
		715
		716	unless (--$ndirs) {
		717	push @nondirs, @$entries;
		718	feed $statgrp;
		719	}
		720	} else {
		721	push @nondirs, $entry;
		722	}
		723	}
		724	}
		725	};
		726	};
452	};	727	};
453	$statcb = sub {
454	my ($status, $entry) = @_;
455
456	if ($status < 0) {
457	$nreq--;
458	push @nondirs, $entry;
459	&$schedcb;
460	} else {
461	# need to check for real directory
462	aio_lstat "$path/$entry", sub {
463	$nreq--;
464
465	if (-d _) {
466	push @dirs, $entry;
467
468	if (!--$ndirs) {
469	push @nondirs, @$entries;
470	$entries = [];
471	}
472	} else {
473	push @nondirs, $entry;
474	}
475
476	&$schedcb;
477	}
478	}
479	};
480
481	&$schedcb while @$entries && $nreq < $maxreq;
482	};	728	};
483	};	729	};
		730
		731	$grp
484	};	732	}
		733	}
		734
		735	=item aio_rmtree $path, $callback->($status)
		736
		737	Delete a directory tree starting (and including) C<$path>, return the
		738	status of the final C<rmdir> only. This is a composite request that
		739	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		740	everything else.
		741
		742	=cut
		743
		744	sub aio_rmtree;
		745	sub aio_rmtree($;$) {
		746	aio_block {
		747	my ($path, $cb) = @_;
		748
		749	my $pri = aioreq_pri;
		750	my $grp = aio_group $cb;
		751
		752	aioreq_pri $pri;
		753	add $grp aio_scandir $path, 0, sub {
		754	my ($dirs, $nondirs) = @_;
		755
		756	my $dirgrp = aio_group sub {
		757	add $grp aio_rmdir $path, sub {
		758	$grp->result ($_[0]);
		759	};
		760	};
		761
		762	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		763	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		764
		765	add $grp $dirgrp;
		766	};
		767
		768	$grp
		769	}
485	}	770	}
486		771
487	=item aio_fsync $fh, $callback->($status)	772	=item aio_fsync $fh, $callback->($status)
488		773
489	Asynchronously call fsync on the given filehandle and call the callback	774	Asynchronously call fsync on the given filehandle and call the callback
…		…
495	callback with the fdatasync result code.	780	callback with the fdatasync result code.
496		781
497	If this call isn't available because your OS lacks it or it couldn't be	782	If this call isn't available because your OS lacks it or it couldn't be
498	detected, it will be emulated by calling C<fsync> instead.	783	detected, it will be emulated by calling C<fsync> instead.
499		784
500	=item aio_group $callback->()	785	=item aio_group $callback->(...)
501		786
		787	This is a very special aio request: Instead of doing something, it is a
		788	container for other aio requests, which is useful if you want to bundle
		789	many requests into a single, composite, request with a definite callback
		790	and the ability to cancel the whole request with its subrequests.
		791
		792	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		793	for more info.
		794
		795	Example:
		796
		797	my $grp = aio_group sub {
		798	print "all stats done\n";
		799	};
		800
		801	add $grp
		802	(aio_stat ...),
		803	(aio_stat ...),
		804	...;
		805
		806	=item aio_nop $callback->()
		807
		808	This is a special request - it does nothing in itself and is only used for
		809	side effects, such as when you want to add a dummy request to a group so
		810	that finishing the requests in the group depends on executing the given
		811	code.
		812
		813	While this request does nothing, it still goes through the execution
		814	phase and still requires a worker thread. Thus, the callback will not
		815	be executed immediately but only after other requests in the queue have
		816	entered their execution phase. This can be used to measure request
		817	latency.
		818
502	=item aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	819	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
503		820
504	Mainly used for debugging and benchmarking, this aio request puts one of	821	Mainly used for debugging and benchmarking, this aio request puts one of
505	the request workers to sleep for the given time.	822	the request workers to sleep for the given time.
506		823
		824	While it is theoretically handy to have simple I/O scheduling requests
		825	like sleep and file handle readable/writable, the overhead this creates is
		826	immense (it blocks a thread for a long time) so do not use this function
		827	except to put your application under artificial I/O pressure.
		828
507	=back	829	=back
508		830
509	=head2 IO::AIO::REQ CLASS	831	=head2 IO::AIO::REQ CLASS
510		832
511	All non-aggregate C<aio_*> functions return an object of this class when	833	All non-aggregate C<aio_*> functions return an object of this class when
512	called in non-void context.	834	called in non-void context.
513		835
514	A request always moves through the following five states in its lifetime,
515	in order: B<ready> (request has been created, but has not been executed
516	yet), B<execute> (request is currently being executed), B<pending>
517	(request has been executed but callback has not been called yet),
518	B<result> (results are being processed synchronously, includes calling the
519	callback) and B<done> (request has reached the end of its lifetime and
520	holds no resources anymore).
521
522	=over 4	836	=over 4
523		837
524	=item $req->cancel	838	=item cancel $req
525		839
526	Cancels the request, if possible. Has the effect of skipping execution	840	Cancels the request, if possible. Has the effect of skipping execution
527	when entering the B<execute> state and skipping calling the callback when	841	when entering the B<execute> state and skipping calling the callback when
528	entering the the B<result> state, but will leave the request otherwise	842	entering the the B<result> state, but will leave the request otherwise
529	untouched. That means that requests that currently execute will not be	843	untouched. That means that requests that currently execute will not be
530	stopped and resources held by the request will not be freed prematurely.	844	stopped and resources held by the request will not be freed prematurely.
531		845
		846	=item cb $req $callback->(...)
		847
		848	Replace (or simply set) the callback registered to the request.
		849
532	=back	850	=back
533		851
		852	=head2 IO::AIO::GRP CLASS
		853
		854	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		855	objects of this class, too.
		856
		857	A IO::AIO::GRP object is a special request that can contain multiple other
		858	aio requests.
		859
		860	You create one by calling the C<aio_group> constructing function with a
		861	callback that will be called when all contained requests have entered the
		862	C<done> state:
		863
		864	my $grp = aio_group sub {
		865	print "all requests are done\n";
		866	};
		867
		868	You add requests by calling the C<add> method with one or more
		869	C<IO::AIO::REQ> objects:
		870
		871	$grp->add (aio_unlink "...");
		872
		873	add $grp aio_stat "...", sub {
		874	$_[0] or return $grp->result ("error");
		875
		876	# add another request dynamically, if first succeeded
		877	add $grp aio_open "...", sub {
		878	$grp->result ("ok");
		879	};
		880	};
		881
		882	This makes it very easy to create composite requests (see the source of
		883	C<aio_move> for an application) that work and feel like simple requests.
		884
		885	=over 4
		886
		887	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		888	C<IO::AIO::poll_cb>, just like any other request.
		889
		890	=item * They can be canceled like any other request. Canceling will cancel not
		891	only the request itself, but also all requests it contains.
		892
		893	=item * They can also can also be added to other IO::AIO::GRP objects.
		894
		895	=item * You must not add requests to a group from within the group callback (or
		896	any later time).
		897
		898	=back
		899
		900	Their lifetime, simplified, looks like this: when they are empty, they
		901	will finish very quickly. If they contain only requests that are in the
		902	C<done> state, they will also finish. Otherwise they will continue to
		903	exist.
		904
		905	That means after creating a group you have some time to add requests. And
		906	in the callbacks of those requests, you can add further requests to the
		907	group. And only when all those requests have finished will the the group
		908	itself finish.
		909
		910	=over 4
		911
		912	=item add $grp ...
		913
		914	=item $grp->add (...)
		915
		916	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		917	be added, including other groups, as long as you do not create circular
		918	dependencies.
		919
		920	Returns all its arguments.
		921
		922	=item $grp->cancel_subs
		923
		924	Cancel all subrequests and clears any feeder, but not the group request
		925	itself. Useful when you queued a lot of events but got a result early.
		926
		927	=item $grp->result (...)
		928
		929	Set the result value(s) that will be passed to the group callback when all
		930	subrequests have finished and set thre groups errno to the current value
		931	of errno (just like calling C<errno> without an error number). By default,
		932	no argument will be passed and errno is zero.
		933
		934	=item $grp->errno ([$errno])
		935
		936	Sets the group errno value to C<$errno>, or the current value of errno
		937	when the argument is missing.
		938
		939	Every aio request has an associated errno value that is restored when
		940	the callback is invoked. This method lets you change this value from its
		941	default (0).
		942
		943	Calling C<result> will also set errno, so make sure you either set C<$!>
		944	before the call to C<result>, or call c<errno> after it.
		945
		946	=item feed $grp $callback->($grp)
		947
		948	Sets a feeder/generator on this group: every group can have an attached
		949	generator that generates requests if idle. The idea behind this is that,
		950	although you could just queue as many requests as you want in a group,
		951	this might starve other requests for a potentially long time. For
		952	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		953	requests, delaying any later requests for a long time.
		954
		955	To avoid this, and allow incremental generation of requests, you can
		956	instead a group and set a feeder on it that generates those requests. The
		957	feed callback will be called whenever there are few enough (see C<limit>,
		958	below) requests active in the group itself and is expected to queue more
		959	requests.
		960
		961	The feed callback can queue as many requests as it likes (i.e. C<add> does
		962	not impose any limits).
		963
		964	If the feed does not queue more requests when called, it will be
		965	automatically removed from the group.
		966
		967	If the feed limit is C<0>, it will be set to C<2> automatically.
		968
		969	Example:
		970
		971	# stat all files in @files, but only ever use four aio requests concurrently:
		972
		973	my $grp = aio_group sub { print "finished\n" };
		974	limit $grp 4;
		975	feed $grp sub {
		976	my $file = pop @files
		977	or return;
		978
		979	add $grp aio_stat $file, sub { ... };
		980	};
		981
		982	=item limit $grp $num
		983
		984	Sets the feeder limit for the group: The feeder will be called whenever
		985	the group contains less than this many requests.
		986
		987	Setting the limit to C<0> will pause the feeding process.
		988
		989	=back
		990
534	=head2 SUPPORT FUNCTIONS	991	=head2 SUPPORT FUNCTIONS
		992
		993	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
535		994
536	=over 4	995	=over 4
537		996
538	=item $fileno = IO::AIO::poll_fileno	997	=item $fileno = IO::AIO::poll_fileno
539		998
…		…
544		1003
545	See C<poll_cb> for an example.	1004	See C<poll_cb> for an example.
546		1005
547	=item IO::AIO::poll_cb	1006	=item IO::AIO::poll_cb
548		1007
549	Process all outstanding events on the result pipe. You have to call this	1008	Process some outstanding events on the result pipe. You have to call this
550	regularly. Returns the number of events processed. Returns immediately	1009	regularly. Returns the number of events processed. Returns immediately
551	when no events are outstanding.	1010	when no events are outstanding. The amount of events processed depends on
		1011	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1012
		1013	If not all requests were processed for whatever reason, the filehandle
		1014	will still be ready when C<poll_cb> returns.
552		1015
553	Example: Install an Event watcher that automatically calls	1016	Example: Install an Event watcher that automatically calls
554	IO::AIO::poll_cb with high priority:	1017	IO::AIO::poll_cb with high priority:
555		1018
556	Event->io (fd => IO::AIO::poll_fileno,	1019	Event->io (fd => IO::AIO::poll_fileno,
557	poll => 'r', async => 1,	1020	poll => 'r', async => 1,
558	cb => \&IO::AIO::poll_cb);	1021	cb => \&IO::AIO::poll_cb);
559		1022
		1023	=item IO::AIO::max_poll_reqs $nreqs
		1024
		1025	=item IO::AIO::max_poll_time $seconds
		1026
		1027	These set the maximum number of requests (default C<0>, meaning infinity)
		1028	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1029	the maximum amount of time (default C<0>, meaning infinity) spent in
		1030	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1031	of time C<poll_cb> is allowed to use).
		1032
		1033	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1034	syscall per request processed, which is not normally a problem unless your
		1035	callbacks are really really fast or your OS is really really slow (I am
		1036	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1037
		1038	Setting these is useful if you want to ensure some level of
		1039	interactiveness when perl is not fast enough to process all requests in
		1040	time.
		1041
		1042	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1043
		1044	Example: Install an Event watcher that automatically calls
		1045	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1046	program get the CPU sometimes even under high AIO load.
		1047
		1048	# try not to spend much more than 0.1s in poll_cb
		1049	IO::AIO::max_poll_time 0.1;
		1050
		1051	# use a low priority so other tasks have priority
		1052	Event->io (fd => IO::AIO::poll_fileno,
		1053	poll => 'r', nice => 1,
		1054	cb => &IO::AIO::poll_cb);
		1055
560	=item IO::AIO::poll_wait	1056	=item IO::AIO::poll_wait
561		1057
		1058	If there are any outstanding requests and none of them in the result
562	Wait till the result filehandle becomes ready for reading (simply does a	1059	phase, wait till the result filehandle becomes ready for reading (simply
563	C<select> on the filehandle. This is useful if you want to synchronously wait	1060	does a C<select> on the filehandle. This is useful if you want to
564	for some requests to finish).	1061	synchronously wait for some requests to finish).
565		1062
566	See C<nreqs> for an example.	1063	See C<nreqs> for an example.
567		1064
		1065	=item IO::AIO::poll
		1066
		1067	Waits until some requests have been handled.
		1068
		1069	Returns the number of requests processed, but is otherwise strictly
		1070	equivalent to:
		1071
		1072	IO::AIO::poll_wait, IO::AIO::poll_cb
		1073
568	=item IO::AIO::nreqs	1074	=item IO::AIO::flush
569		1075
570	Returns the number of requests currently outstanding (i.e. for which their	1076	Wait till all outstanding AIO requests have been handled.
571	callback has not been invoked yet).
572		1077
573	Example: wait till there are no outstanding requests anymore:	1078	Strictly equivalent to:
574		1079
575	IO::AIO::poll_wait, IO::AIO::poll_cb	1080	IO::AIO::poll_wait, IO::AIO::poll_cb
576	while IO::AIO::nreqs;	1081	while IO::AIO::nreqs;
577		1082
578	=item IO::AIO::flush	1083	=head3 CONTROLLING THE NUMBER OF THREADS
579
580	Wait till all outstanding AIO requests have been handled.
581
582	Strictly equivalent to:
583
584	IO::AIO::poll_wait, IO::AIO::poll_cb
585	while IO::AIO::nreqs;
586
587	=item IO::AIO::poll
588
589	Waits until some requests have been handled.
590
591	Strictly equivalent to:
592
593	IO::AIO::poll_wait, IO::AIO::poll_cb
594	if IO::AIO::nreqs;
595		1084
596	=item IO::AIO::min_parallel $nthreads	1085	=item IO::AIO::min_parallel $nthreads
597		1086
598	Set the minimum number of AIO threads to C<$nthreads>. The current default	1087	Set the minimum number of AIO threads to C<$nthreads>. The current
599	is C<4>, which means four asynchronous operations can be done at one time	1088	default is C<8>, which means eight asynchronous operations can execute
600	(the number of outstanding operations, however, is unlimited).	1089	concurrently at any one time (the number of outstanding requests,
		1090	however, is unlimited).
601		1091
602	IO::AIO starts threads only on demand, when an AIO request is queued and	1092	IO::AIO starts threads only on demand, when an AIO request is queued and
603	no free thread exists.	1093	no free thread exists. Please note that queueing up a hundred requests can
		1094	create demand for a hundred threads, even if it turns out that everything
		1095	is in the cache and could have been processed faster by a single thread.
604		1096
605	It is recommended to keep the number of threads low, as some Linux	1097	It is recommended to keep the number of threads relatively low, as some
606	kernel versions will scale negatively with the number of threads (higher	1098	Linux kernel versions will scale negatively with the number of threads
607	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1099	(higher parallelity => MUCH higher latency). With current Linux 2.6
608	threads should be fine.	1100	versions, 4-32 threads should be fine.
609		1101
610	Under most circumstances you don't need to call this function, as the	1102	Under most circumstances you don't need to call this function, as the
611	module selects a default that is suitable for low to moderate load.	1103	module selects a default that is suitable for low to moderate load.
612		1104
613	=item IO::AIO::max_parallel $nthreads	1105	=item IO::AIO::max_parallel $nthreads
…		…
622	This module automatically runs C<max_parallel 0> at program end, to ensure	1114	This module automatically runs C<max_parallel 0> at program end, to ensure
623	that all threads are killed and that there are no outstanding requests.	1115	that all threads are killed and that there are no outstanding requests.
624		1116
625	Under normal circumstances you don't need to call this function.	1117	Under normal circumstances you don't need to call this function.
626		1118
		1119	=item IO::AIO::max_idle $nthreads
		1120
		1121	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1122	threads that did not get a request to process within 10 seconds). That
		1123	means if a thread becomes idle while C<$nthreads> other threads are also
		1124	idle, it will free its resources and exit.
		1125
		1126	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1127	to allow for extremely high load situations, but want to free resources
		1128	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1129
		1130	The default is probably ok in most situations, especially if thread
		1131	creation is fast. If thread creation is very slow on your system you might
		1132	want to use larger values.
		1133
627	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1134	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1135
		1136	This is a very bad function to use in interactive programs because it
		1137	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1138	use an C<aio_group> together with a feed callback.
628		1139
629	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1140	Sets the maximum number of outstanding requests to C<$nreqs>. If you
630	try to queue up more than this number of requests, the caller will block until	1141	to queue up more than this number of requests, the next call to the
631	some requests have been handled.	1142	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1143	function will block until the limit is no longer exceeded.
632		1144
633	The default is very large, so normally there is no practical limit. If you	1145	The default value is very large, so there is no practical limit on the
634	queue up many requests in a loop it often improves speed if you set	1146	number of outstanding requests.
635	this to a relatively low number, such as C<100>.
636		1147
637	Under normal circumstances you don't need to call this function.	1148	You can still queue as many requests as you want. Therefore,
		1149	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1150	as a stop gap to shield against fatal memory overflow (with large values).
		1151
		1152	=head3 STATISTICAL INFORMATION
		1153
		1154	=item IO::AIO::nreqs
		1155
		1156	Returns the number of requests currently in the ready, execute or pending
		1157	states (i.e. for which their callback has not been invoked yet).
		1158
		1159	Example: wait till there are no outstanding requests anymore:
		1160
		1161	IO::AIO::poll_wait, IO::AIO::poll_cb
		1162	while IO::AIO::nreqs;
		1163
		1164	=item IO::AIO::nready
		1165
		1166	Returns the number of requests currently in the ready state (not yet
		1167	executed).
		1168
		1169	=item IO::AIO::npending
		1170
		1171	Returns the number of requests currently in the pending state (executed,
		1172	but not yet processed by poll_cb).
638		1173
639	=back	1174	=back
640		1175
641	=cut	1176	=cut
642		1177
…		…
654	or return undef;	1189	or return undef;
655		1190
656	*$sym	1191	*$sym
657	}	1192	}
658		1193
659	min_parallel 4;	1194	min_parallel 8;
660		1195
661	END {	1196	END { flush }
662	max_parallel 0;
663	}
664		1197
665	1;	1198	1;
666		1199
667	=head2 FORK BEHAVIOUR	1200	=head2 FORK BEHAVIOUR
668		1201
669	This module should do "the right thing" when the process using it forks:	1202	This module should do "the right thing" when the process using it forks:
670		1203
671	Before the fork, IO::AIO enters a quiescent state where no requests	1204	Before the fork, IO::AIO enters a quiescent state where no requests
672	can be added in other threads and no results will be processed. After	1205	can be added in other threads and no results will be processed. After
673	the fork the parent simply leaves the quiescent state and continues	1206	the fork the parent simply leaves the quiescent state and continues
674	request/result processing, while the child clears the request/result	1207	request/result processing, while the child frees the request/result queue
675	queue (so the requests started before the fork will only be handled in	1208	(so that the requests started before the fork will only be handled in the
676	the parent). Threads will be started on demand until the limit ste in the	1209	parent). Threads will be started on demand until the limit set in the
677	parent process has been reached again.	1210	parent process has been reached again.
678		1211
679	In short: the parent will, after a short pause, continue as if fork had	1212	In short: the parent will, after a short pause, continue as if fork had
680	not been called, while the child will act as if IO::AIO has not been used	1213	not been called, while the child will act as if IO::AIO has not been used
681	yet.	1214	yet.
682		1215
		1216	=head2 MEMORY USAGE
		1217
		1218	Per-request usage:
		1219
		1220	Each aio request uses - depending on your architecture - around 100-200
		1221	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1222	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1223	scalars and other data passed into aio requests will also be locked and
		1224	will consume memory till the request has entered the done state.
		1225
		1226	This is now awfully much, so queuing lots of requests is not usually a
		1227	problem.
		1228
		1229	Per-thread usage:
		1230
		1231	In the execution phase, some aio requests require more memory for
		1232	temporary buffers, and each thread requires a stack and other data
		1233	structures (usually around 16k-128k, depending on the OS).
		1234
		1235	=head1 KNOWN BUGS
		1236
		1237	Known bugs will be fixed in the next release.
		1238
683	=head1 SEE ALSO	1239	=head1 SEE ALSO
684		1240
685	L<Coro>, L<Linux::AIO> (obsolete).	1241	L<Coro::AIO>.
686		1242
687	=head1 AUTHOR	1243	=head1 AUTHOR
688		1244
689	Marc Lehmann <schmorp@schmorp.de>	1245	Marc Lehmann <schmorp@schmorp.de>
690	http://home.schmorp.de/	1246	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC vs. Revision 1.103 by root, Tue Jan 23 22:57:34 2007 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC vs.
Revision 1.103 by root, Tue Jan 23 22:57:34 2007 UTC