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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC vs.
Revision 1.168 by root, Mon Nov 30 22:22:13 2009 UTC

…		…
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", O_RDONLY, 0, sub {
10	my ($fh) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
25	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
26		27
27	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
28	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
29		30
		31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		32	use AnyEvent::AIO;
		33
30	# AnyEvent integration	34	# EV integration
31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	35	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
33		36
34	# Event integration	37	# Event integration
35	Event->io (fd => IO::AIO::poll_fileno,	38	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',	39	poll => 'r',
37	cb => \&IO::AIO::poll_cb);	40	cb => \&IO::AIO::poll_cb);
…		…
49	\&IO::AIO::poll_cb);	52	\&IO::AIO::poll_cb);
50		53
51	=head1 DESCRIPTION	54	=head1 DESCRIPTION
52		55
53	This module implements asynchronous I/O using whatever means your	56	This module implements asynchronous I/O using whatever means your
54	operating system supports.	57	operating system supports. It is implemented as an interface to C<libeio>
		58	(L<http://software.schmorp.de/pkg/libeio.html>).
55		59
56	Asynchronous means that operations that can normally block your program	60	Asynchronous means that operations that can normally block your program
57	(e.g. reading from disk) will be done asynchronously: the operation	61	(e.g. reading from disk) will be done asynchronously: the operation
58	will still block, but you can do something else in the meantime. This	62	will still block, but you can do something else in the meantime. This
59	is extremely useful for programs that need to stay interactive even	63	is extremely useful for programs that need to stay interactive even
…		…
61	etc.), but can also be used to easily do operations in parallel that are	65	etc.), but can also be used to easily do operations in parallel that are
62	normally done sequentially, e.g. stat'ing many files, which is much faster	66	normally done sequentially, e.g. stat'ing many files, which is much faster
63	on a RAID volume or over NFS when you do a number of stat operations	67	on a RAID volume or over NFS when you do a number of stat operations
64	concurrently.	68	concurrently.
65		69
66	While this works on all types of file descriptors (for example sockets),	70	While most of this works on all types of file descriptors (for
67	using these functions on file descriptors that support nonblocking	71	example sockets), using these functions on file descriptors that
68	operation (again, sockets, pipes etc.) is very inefficient. Use an event	72	support nonblocking operation (again, sockets, pipes etc.) is
69	loop for that (such as the L<Event\|Event> module): IO::AIO will naturally	73	very inefficient. Use an event loop for that (such as the L<EV>
70	fit into such an event loop itself.	74	module): IO::AIO will naturally fit into such an event loop itself.
71		75
72	In this version, a number of threads are started that execute your	76	In this version, a number of threads are started that execute your
73	requests and signal their completion. You don't need thread support	77	requests and signal their completion. You don't need thread support
74	in perl, and the threads created by this module will not be visible	78	in perl, and the threads created by this module will not be visible
75	to perl. In the future, this module might make use of the native aio	79	to perl. In the future, this module might make use of the native aio
…		…
77	not well-supported or restricted (GNU/Linux doesn't allow them on normal	81	not well-supported or restricted (GNU/Linux doesn't allow them on normal
78	files currently, for example), and they would only support aio_read and	82	files currently, for example), and they would only support aio_read and
79	aio_write, so the remaining functionality would have to be implemented	83	aio_write, so the remaining functionality would have to be implemented
80	using threads anyway.	84	using threads anyway.
81		85
82	Although the module will work with in the presence of other (Perl-)	86	Although the module will work in the presence of other (Perl-) threads,
83	threads, it is currently not reentrant in any way, so use appropriate	87	it is currently not reentrant in any way, so use appropriate locking
84	locking yourself, always call C<poll_cb> from within the same thread, or	88	yourself, always call C<poll_cb> from within the same thread, or never
85	never call C<poll_cb> (or other C<aio_> functions) recursively.	89	call C<poll_cb> (or other C<aio_> functions) recursively.
		90
		91	=head2 EXAMPLE
		92
		93	This is a simple example that uses the EV module and loads
		94	F</etc/passwd> asynchronously:
		95
		96	use Fcntl;
		97	use EV;
		98	use IO::AIO;
		99
		100	# register the IO::AIO callback with EV
		101	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		102
		103	# queue the request to open /etc/passwd
		104	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		105	my $fh = shift
		106	or die "error while opening: $!";
		107
		108	# stat'ing filehandles is generally non-blocking
		109	my $size = -s $fh;
		110
		111	# queue a request to read the file
		112	my $contents;
		113	aio_read $fh, 0, $size, $contents, 0, sub {
		114	$_[0] == $size
		115	or die "short read: $!";
		116
		117	close $fh;
		118
		119	# file contents now in $contents
		120	print $contents;
		121
		122	# exit event loop and program
		123	EV::unloop;
		124	};
		125	};
		126
		127	# possibly queue up other requests, or open GUI windows,
		128	# check for sockets etc. etc.
		129
		130	# process events as long as there are some:
		131	EV::loop;
86		132
87	=head1 REQUEST ANATOMY AND LIFETIME	133	=head1 REQUEST ANATOMY AND LIFETIME
88		134
89	Every C<aio_*> function creates a request. which is a C data structure not	135	Every C<aio_*> function creates a request. which is a C data structure not
90	directly visible to Perl.	136	directly visible to Perl.
…		…
132	Request has reached the end of its lifetime and holds no resources anymore	178	Request has reached the end of its lifetime and holds no resources anymore
133	(except possibly for the Perl object, but its connection to the actual	179	(except possibly for the Perl object, but its connection to the actual
134	aio request is severed and calling its methods will either do nothing or	180	aio request is severed and calling its methods will either do nothing or
135	result in a runtime error).	181	result in a runtime error).
136		182
		183	=back
		184
137	=cut	185	=cut
138		186
139	package IO::AIO;	187	package IO::AIO;
140		188
141	no warnings;	189	use Carp ();
142	use strict 'vars';	190
		191	use common::sense;
143		192
144	use base 'Exporter';	193	use base 'Exporter';
145		194
146	BEGIN {	195	BEGIN {
147	our $VERSION = '2.0';	196	our $VERSION = '3.31';
148		197
149	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	198	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
150	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	199	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
151	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	200	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
152	aio_copy aio_group aio_nop aio_mknod);	201	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		202	aio_rename aio_link aio_move aio_copy aio_group
		203	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		204	aio_chmod aio_utime aio_truncate);
		205
153	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	206	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
154	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	207	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
155	min_parallel max_parallel nreqs nready npending);	208	min_parallel max_parallel max_idle
		209	nreqs nready npending nthreads
		210	max_poll_time max_poll_reqs
		211	sendfile fadvise);
		212
		213	push @AIO_REQ, qw(aio_busy); # not exported
156		214
157	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
158		216
159	require XSLoader;	217	require XSLoader;
160	XSLoader::load ("IO::AIO", $VERSION);	218	XSLoader::load ("IO::AIO", $VERSION);
161	}	219	}
162		220
163	=head1 FUNCTIONS	221	=head1 FUNCTIONS
164		222
165	=head2 AIO FUNCTIONS	223	=head2 AIO REQUEST FUNCTIONS
166		224
167	All the C<aio_*> calls are more or less thin wrappers around the syscall	225	All the C<aio_*> calls are more or less thin wrappers around the syscall
168	with the same name (sans C<aio_>). The arguments are similar or identical,	226	with the same name (sans C<aio_>). The arguments are similar or identical,
169	and they all accept an additional (and optional) C<$callback> argument	227	and they all accept an additional (and optional) C<$callback> argument
170	which must be a code reference. This code reference will get called with	228	which must be a code reference. This code reference will get called with
171	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	229	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
172	perl, which usually delivers "false") as it's sole argument when the given	230	perl, which usually delivers "false") as its sole argument after the given
173	syscall has been executed asynchronously.	231	syscall has been executed asynchronously.
174		232
175	All functions expecting a filehandle keep a copy of the filehandle	233	All functions expecting a filehandle keep a copy of the filehandle
176	internally until the request has finished.	234	internally until the request has finished.
177		235
178	All requests return objects of type L<IO::AIO::REQ> that allow further	236	All functions return request objects of type L<IO::AIO::REQ> that allow
179	manipulation of those requests while they are in-flight.	237	further manipulation of those requests while they are in-flight.
180		238
181	The pathnames you pass to these routines I<must> be absolute and	239	The pathnames you pass to these routines I<must> be absolute and
182	encoded in byte form. The reason for the former is that at the time the	240	encoded as octets. The reason for the former is that at the time the
183	request is being executed, the current working directory could have	241	request is being executed, the current working directory could have
184	changed. Alternatively, you can make sure that you never change the	242	changed. Alternatively, you can make sure that you never change the
185	current working directory.	243	current working directory anywhere in the program and then use relative
		244	paths.
186		245
187	To encode pathnames to byte form, either make sure you either: a)	246	To encode pathnames as octets, either make sure you either: a) always pass
188	always pass in filenames you got from outside (command line, readdir	247	in filenames you got from outside (command line, readdir etc.) without
189	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	248	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
190	your pathnames to the locale (or other) encoding in effect in the user	249	your pathnames to the locale (or other) encoding in effect in the user
191	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	250	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
192	use something else.	251	use something else to ensure your scalar has the correct contents.
		252
		253	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		254	handles correctly whether it is set or not.
193		255
194	=over 4	256	=over 4
195		257
196	=item $prev_pri = aioreq_pri [$pri]	258	=item $prev_pri = aioreq_pri [$pri]
197		259
…		…
217	aio_read $_[0], ..., sub {	279	aio_read $_[0], ..., sub {
218	...	280	...
219	};	281	};
220	};	282	};
221		283
		284
222	=item aioreq_nice $pri_adjust	285	=item aioreq_nice $pri_adjust
223		286
224	Similar to C<aioreq_pri>, but subtracts the given value from the current	287	Similar to C<aioreq_pri>, but subtracts the given value from the current
225	priority, so effects are cumulative.	288	priority, so the effect is cumulative.
		289
226		290
227	=item aio_open $pathname, $flags, $mode, $callback->($fh)	291	=item aio_open $pathname, $flags, $mode, $callback->($fh)
228		292
229	Asynchronously open or create a file and call the callback with a newly	293	Asynchronously open or create a file and call the callback with a newly
230	created filehandle for the file.	294	created filehandle for the file.
…		…
236	list. They are the same as used by C<sysopen>.	300	list. They are the same as used by C<sysopen>.
237		301
238	Likewise, C<$mode> specifies the mode of the newly created file, if it	302	Likewise, C<$mode> specifies the mode of the newly created file, if it
239	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	303	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
240	except that it is mandatory (i.e. use C<0> if you don't create new files,	304	except that it is mandatory (i.e. use C<0> if you don't create new files,
241	and C<0666> or C<0777> if you do).	305	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		306	by the umask in effect then the request is being executed, so better never
		307	change the umask.
242		308
243	Example:	309	Example:
244		310
245	aio_open "/etc/passwd", O_RDONLY, 0, sub {	311	aio_open "/etc/passwd", O_RDONLY, 0, sub {
246	if ($_[0]) {	312	if ($_[0]) {
…		…
249	} else {	315	} else {
250	die "open failed: $!\n";	316	die "open failed: $!\n";
251	}	317	}
252	};	318	};
253		319
		320
254	=item aio_close $fh, $callback->($status)	321	=item aio_close $fh, $callback->($status)
255		322
256	Asynchronously close a file and call the callback with the result	323	Asynchronously close a file and call the callback with the result
257	code. I<WARNING:> although accepted, you should not pass in a perl	324	code.
258	filehandle here, as perl will likely close the file descriptor another
259	time when the filehandle is destroyed. Normally, you can safely call perls
260	C<close> or just let filehandles go out of scope.
261		325
262	This is supposed to be a bug in the API, so that might change. It's	326	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
263	therefore best to avoid this function.	327	closing the file descriptor associated with the filehandle itself.
		328
		329	Therefore, C<aio_close> will not close the filehandle - instead it will
		330	use dup2 to overwrite the file descriptor with the write-end of a pipe
		331	(the pipe fd will be created on demand and will be cached).
		332
		333	Or in other words: the file descriptor will be closed, but it will not be
		334	free for reuse until the perl filehandle is closed.
		335
		336	=cut
264		337
265	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	338	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
266		339
267	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	340	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
268		341
269	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	342	Reads or writes C<$length> bytes from or to the specified C<$fh> and
270	into the scalar given by C<data> and offset C<dataoffset> and calls the	343	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
271	callback without the actual number of bytes read (or -1 on error, just	344	and calls the callback without the actual number of bytes read (or -1 on
272	like the syscall).	345	error, just like the syscall).
		346
		347	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		348	offset plus the actual number of bytes read.
		349
		350	If C<$offset> is undefined, then the current file descriptor offset will
		351	be used (and updated), otherwise the file descriptor offset will not be
		352	changed by these calls.
		353
		354	If C<$length> is undefined in C<aio_write>, use the remaining length of
		355	C<$data>.
		356
		357	If C<$dataoffset> is less than zero, it will be counted from the end of
		358	C<$data>.
273		359
274	The C<$data> scalar I<MUST NOT> be modified in any way while the request	360	The C<$data> scalar I<MUST NOT> be modified in any way while the request
275	is outstanding. Modifying it can result in segfaults or WW3 (if the	361	is outstanding. Modifying it can result in segfaults or World War III (if
276	necessary/optional hardware is installed).	362	the necessary/optional hardware is installed).
277		363
278	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	364	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
279	offset C<0> within the scalar:	365	offset C<0> within the scalar:
280		366
281	aio_read $fh, 7, 15, $buffer, 0, sub {	367	aio_read $fh, 7, 15, $buffer, 0, sub {
282	$_[0] > 0 or die "read error: $!";	368	$_[0] > 0 or die "read error: $!";
283	print "read $_[0] bytes: <$buffer>\n";	369	print "read $_[0] bytes: <$buffer>\n";
284	};	370	};
		371
285		372
286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	373	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
287		374
288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	375	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
289	reading at byte offset C<$in_offset>, and starts writing at the current	376	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
303	C<$in_fh> than are written, and there is no way to find out how many	390	C<$in_fh> than are written, and there is no way to find out how many
304	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	391	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
305	provides the number of bytes written to C<$out_fh>. Only if the result	392	provides the number of bytes written to C<$out_fh>. Only if the result
306	value equals C<$length> one can assume that C<$length> bytes have been	393	value equals C<$length> one can assume that C<$length> bytes have been
307	read.	394	read.
		395
308		396
309	=item aio_readahead $fh,$offset,$length, $callback->($retval)	397	=item aio_readahead $fh,$offset,$length, $callback->($retval)
310		398
311	C<aio_readahead> populates the page cache with data from a file so that	399	C<aio_readahead> populates the page cache with data from a file so that
312	subsequent reads from that file will not block on disk I/O. The C<$offset>	400	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
318	file. The current file offset of the file is left unchanged.	406	file. The current file offset of the file is left unchanged.
319		407
320	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	408	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
321	emulated by simply reading the data, which would have a similar effect.	409	emulated by simply reading the data, which would have a similar effect.
322		410
		411
323	=item aio_stat $fh_or_path, $callback->($status)	412	=item aio_stat $fh_or_path, $callback->($status)
324		413
325	=item aio_lstat $fh, $callback->($status)	414	=item aio_lstat $fh, $callback->($status)
326		415
327	Works like perl's C<stat> or C<lstat> in void context. The callback will	416	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
340	aio_stat "/etc/passwd", sub {	429	aio_stat "/etc/passwd", sub {
341	$_[0] and die "stat failed: $!";	430	$_[0] and die "stat failed: $!";
342	print "size is ", -s _, "\n";	431	print "size is ", -s _, "\n";
343	};	432	};
344		433
		434
		435	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		436
		437	Works like perl's C<utime> function (including the special case of $atime
		438	and $mtime being undef). Fractional times are supported if the underlying
		439	syscalls support them.
		440
		441	When called with a pathname, uses utimes(2) if available, otherwise
		442	utime(2). If called on a file descriptor, uses futimes(2) if available,
		443	otherwise returns ENOSYS, so this is not portable.
		444
		445	Examples:
		446
		447	# set atime and mtime to current time (basically touch(1)):
		448	aio_utime "path", undef, undef;
		449	# set atime to current time and mtime to beginning of the epoch:
		450	aio_utime "path", time, undef; # undef==0
		451
		452
		453	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		454
		455	Works like perl's C<chown> function, except that C<undef> for either $uid
		456	or $gid is being interpreted as "do not change" (but -1 can also be used).
		457
		458	Examples:
		459
		460	# same as "chown root path" in the shell:
		461	aio_chown "path", 0, -1;
		462	# same as above:
		463	aio_chown "path", 0, undef;
		464
		465
		466	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		467
		468	Works like truncate(2) or ftruncate(2).
		469
		470
		471	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		472
		473	Works like perl's C<chmod> function.
		474
		475
345	=item aio_unlink $pathname, $callback->($status)	476	=item aio_unlink $pathname, $callback->($status)
346		477
347	Asynchronously unlink (delete) a file and call the callback with the	478	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	479	result code.
349		480
		481
350	=item aio_mknod $path, $mode, $dev, $callback->($status)	482	=item aio_mknod $path, $mode, $dev, $callback->($status)
351		483
		484	[EXPERIMENTAL]
		485
352	Asynchronously create a device node (or fifo). See mknod(2).	486	Asynchronously create a device node (or fifo). See mknod(2).
353		487
354	The only portable (POSIX) way of calling this function is:	488	The only (POSIX-) portable way of calling this function is:
355		489
356	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	490	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		491
357		492
358	=item aio_link $srcpath, $dstpath, $callback->($status)	493	=item aio_link $srcpath, $dstpath, $callback->($status)
359		494
360	Asynchronously create a new link to the existing object at C<$srcpath> at	495	Asynchronously create a new link to the existing object at C<$srcpath> at
361	the path C<$dstpath> and call the callback with the result code.	496	the path C<$dstpath> and call the callback with the result code.
362		497
		498
363	=item aio_symlink $srcpath, $dstpath, $callback->($status)	499	=item aio_symlink $srcpath, $dstpath, $callback->($status)
364		500
365	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	501	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
366	the path C<$dstpath> and call the callback with the result code.	502	the path C<$dstpath> and call the callback with the result code.
367		503
		504
		505	=item aio_readlink $path, $callback->($link)
		506
		507	Asynchronously read the symlink specified by C<$path> and pass it to
		508	the callback. If an error occurs, nothing or undef gets passed to the
		509	callback.
		510
		511
368	=item aio_rename $srcpath, $dstpath, $callback->($status)	512	=item aio_rename $srcpath, $dstpath, $callback->($status)
369		513
370	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	514	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
371	rename(2) and call the callback with the result code.	515	rename(2) and call the callback with the result code.
372		516
		517
		518	=item aio_mkdir $pathname, $mode, $callback->($status)
		519
		520	Asynchronously mkdir (create) a directory and call the callback with
		521	the result code. C<$mode> will be modified by the umask at the time the
		522	request is executed, so do not change your umask.
		523
		524
373	=item aio_rmdir $pathname, $callback->($status)	525	=item aio_rmdir $pathname, $callback->($status)
374		526
375	Asynchronously rmdir (delete) a directory and call the callback with the	527	Asynchronously rmdir (delete) a directory and call the callback with the
376	result code.	528	result code.
		529
377		530
378	=item aio_readdir $pathname, $callback->($entries)	531	=item aio_readdir $pathname, $callback->($entries)
379		532
380	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	533	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
381	directory (i.e. opendir + readdir + closedir). The entries will not be	534	directory (i.e. opendir + readdir + closedir). The entries will not be
382	sorted, and will B<NOT> include the C<.> and C<..> entries.	535	sorted, and will B<NOT> include the C<.> and C<..> entries.
383		536
384	The callback a single argument which is either C<undef> or an array-ref	537	The callback is passed a single argument which is either C<undef> or an
385	with the filenames.	538	array-ref with the filenames.
		539
		540
		541	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		542
		543	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		544	behaviour and output format. In case of an error, C<$entries> will be
		545	C<undef>.
		546
		547	The flags are a combination of the following constants, ORed together (the
		548	flags will also be passed to the callback, possibly modified):
		549
		550	=over 4
		551
		552	=item IO::AIO::READDIR_DENTS
		553
		554	When this flag is off, then the callback gets an arrayref with of names
		555	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		556	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		557	entry in more detail.
		558
		559	C<$name> is the name of the entry.
		560
		561	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		562
		563	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		564	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		565	C<IO::AIO::DT_WHT>.
		566
		567	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		568	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		569	scalars are read-only: you can not modify them.
		570
		571	C<$inode> is the inode number (which might not be exact on systems with 64
		572	bit inode numbers and 32 bit perls). This field has unspecified content on
		573	systems that do not deliver the inode information.
		574
		575	=item IO::AIO::READDIR_DIRS_FIRST
		576
		577	When this flag is set, then the names will be returned in an order where
		578	likely directories come first. This is useful when you need to quickly
		579	find directories, or you want to find all directories while avoiding to
		580	stat() each entry.
		581
		582	If the system returns type information in readdir, then this is used
		583	to find directories directly. Otherwise, likely directories are files
		584	beginning with ".", or otherwise files with no dots, of which files with
		585	short names are tried first.
		586
		587	=item IO::AIO::READDIR_STAT_ORDER
		588
		589	When this flag is set, then the names will be returned in an order
		590	suitable for stat()'ing each one. That is, when you plan to stat()
		591	all files in the given directory, then the returned order will likely
		592	be fastest.
		593
		594	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		595	the likely dirs come first, resulting in a less optimal stat order.
		596
		597	=item IO::AIO::READDIR_FOUND_UNKNOWN
		598
		599	This flag should not be set when calling C<aio_readdirx>. Instead, it
		600	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		601	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		602	C<$type>'s are known, which can be used to speed up some algorithms.
		603
		604	=back
		605
		606
		607	=item aio_load $path, $data, $callback->($status)
		608
		609	This is a composite request that tries to fully load the given file into
		610	memory. Status is the same as with aio_read.
		611
		612	=cut
		613
		614	sub aio_load($$;$) {
		615	my ($path, undef, $cb) = @_;
		616	my $data = \$_[1];
		617
		618	my $pri = aioreq_pri;
		619	my $grp = aio_group $cb;
		620
		621	aioreq_pri $pri;
		622	add $grp aio_open $path, O_RDONLY, 0, sub {
		623	my $fh = shift
		624	or return $grp->result (-1);
		625
		626	aioreq_pri $pri;
		627	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		628	$grp->result ($_[0]);
		629	};
		630	};
		631
		632	$grp
		633	}
386		634
387	=item aio_copy $srcpath, $dstpath, $callback->($status)	635	=item aio_copy $srcpath, $dstpath, $callback->($status)
388		636
389	Try to copy the I<file> (directories not supported as either source or	637	Try to copy the I<file> (directories not supported as either source or
390	destination) from C<$srcpath> to C<$dstpath> and call the callback with	638	destination) from C<$srcpath> to C<$dstpath> and call the callback with
391	the C<0> (error) or C<-1> ok.	639	a status of C<0> (ok) or C<-1> (error, see C<$!>).
392		640
393	This is a composite request that it creates the destination file with	641	This is a composite request that creates the destination file with
394	mode 0200 and copies the contents of the source file into it using	642	mode 0200 and copies the contents of the source file into it using
395	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	643	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
396	uid/gid, in that order.	644	uid/gid, in that order.
397		645
398	If an error occurs, the partial destination file will be unlinked, if	646	If an error occurs, the partial destination file will be unlinked, if
…		…
408	my $grp = aio_group $cb;	656	my $grp = aio_group $cb;
409		657
410	aioreq_pri $pri;	658	aioreq_pri $pri;
411	add $grp aio_open $src, O_RDONLY, 0, sub {	659	add $grp aio_open $src, O_RDONLY, 0, sub {
412	if (my $src_fh = $_[0]) {	660	if (my $src_fh = $_[0]) {
413	my @stat = stat $src_fh;	661	my @stat = stat $src_fh; # hmm, might block over nfs?
414		662
415	aioreq_pri $pri;	663	aioreq_pri $pri;
416	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {	664	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
417	if (my $dst_fh = $_[0]) {	665	if (my $dst_fh = $_[0]) {
418	aioreq_pri $pri;	666	aioreq_pri $pri;
419	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	667	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
420	if ($_[0] == $stat[7]) {	668	if ($_[0] == $stat[7]) {
421	$grp->result (0);	669	$grp->result (0);
422	close $src_fh;	670	close $src_fh;
423		671
424	# those should not normally block. should. should.	672	my $ch = sub {
		673	aioreq_pri $pri;
		674	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		675	aioreq_pri $pri;
		676	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		677	aioreq_pri $pri;
		678	add $grp aio_close $dst_fh;
		679	}
		680	};
		681	};
		682
		683	aioreq_pri $pri;
		684	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		685	if ($_[0] < 0 && $! == ENOSYS) {
		686	aioreq_pri $pri;
425	utime $stat[8], $stat[9], $dst;	687	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
426	chmod $stat[2] & 07777, $dst_fh;	688	} else {
427	chown $stat[4], $stat[5], $dst_fh;	689	$ch->();
		690	}
428	close $dst_fh;	691	};
429	} else {	692	} else {
430	$grp->result (-1);	693	$grp->result (-1);
431	close $src_fh;	694	close $src_fh;
432	close $dst_fh;	695	close $dst_fh;
433		696
…		…
450		713
451	=item aio_move $srcpath, $dstpath, $callback->($status)	714	=item aio_move $srcpath, $dstpath, $callback->($status)
452		715
453	Try to move the I<file> (directories not supported as either source or	716	Try to move the I<file> (directories not supported as either source or
454	destination) from C<$srcpath> to C<$dstpath> and call the callback with	717	destination) from C<$srcpath> to C<$dstpath> and call the callback with
455	the C<0> (error) or C<-1> ok.	718	a status of C<0> (ok) or C<-1> (error, see C<$!>).
456		719
457	This is a composite request that tries to rename(2) the file first. If	720	This is a composite request that tries to rename(2) the file first; if
458	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	721	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
459	that is successful, unlinking the C<$srcpath>.	722	that is successful, unlinks the C<$srcpath>.
460		723
461	=cut	724	=cut
462		725
463	sub aio_move($$;$) {	726	sub aio_move($$;$) {
464	my ($src, $dst, $cb) = @_;	727	my ($src, $dst, $cb) = @_;
…		…
511		774
512	Implementation notes.	775	Implementation notes.
513		776
514	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	777	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
515		778
		779	If readdir returns file type information, then this is used directly to
		780	find directories.
		781
516	After reading the directory, the modification time, size etc. of the	782	Otherwise, after reading the directory, the modification time, size etc.
517	directory before and after the readdir is checked, and if they match (and	783	of the directory before and after the readdir is checked, and if they
518	isn't the current time), the link count will be used to decide how many	784	match (and isn't the current time), the link count will be used to decide
519	entries are directories (if >= 2). Otherwise, no knowledge of the number	785	how many entries are directories (if >= 2). Otherwise, no knowledge of the
520	of subdirectories will be assumed.	786	number of subdirectories will be assumed.
521		787
522	Then entries will be sorted into likely directories (everything without	788	Then entries will be sorted into likely directories a non-initial dot
523	a non-initial dot currently) and likely non-directories (everything	789	currently) and likely non-directories (see C<aio_readdirx>). Then every
524	else). Then every entry plus an appended C</.> will be C<stat>'ed,	790	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
525	likely directories first. If that succeeds, it assumes that the entry	791	in order of their inode numbers. If that succeeds, it assumes that the
526	is a directory or a symlink to directory (which will be checked	792	entry is a directory or a symlink to directory (which will be checked
527	seperately). This is often faster than stat'ing the entry itself because	793	seperately). This is often faster than stat'ing the entry itself because
528	filesystems might detect the type of the entry without reading the inode	794	filesystems might detect the type of the entry without reading the inode
529	data (e.g. ext2fs filetype feature).	795	data (e.g. ext2fs filetype feature), even on systems that cannot return
		796	the filetype information on readdir.
530		797
531	If the known number of directories (link count - 2) has been reached, the	798	If the known number of directories (link count - 2) has been reached, the
532	rest of the entries is assumed to be non-directories.	799	rest of the entries is assumed to be non-directories.
533		800
534	This only works with certainty on POSIX (= UNIX) filesystems, which	801	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
538	as those tend to return 0 or 1 as link counts, which disables the	805	as those tend to return 0 or 1 as link counts, which disables the
539	directory counting heuristic.	806	directory counting heuristic.
540		807
541	=cut	808	=cut
542		809
543	sub aio_scandir($$$) {	810	sub aio_scandir($$;$) {
544	my ($path, $maxreq, $cb) = @_;	811	my ($path, $maxreq, $cb) = @_;
545		812
546	my $pri = aioreq_pri;	813	my $pri = aioreq_pri;
547		814
548	my $grp = aio_group $cb;	815	my $grp = aio_group $cb;
…		…
556	my $now = time;	823	my $now = time;
557	my $hash1 = join ":", (stat _)[0,1,3,7,9];	824	my $hash1 = join ":", (stat _)[0,1,3,7,9];
558		825
559	# read the directory entries	826	# read the directory entries
560	aioreq_pri $pri;	827	aioreq_pri $pri;
561	add $grp aio_readdir $path, sub {	828	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
562	my $entries = shift	829	my $entries = shift
563	or return $grp->result ();	830	or return $grp->result ();
564		831
565	# stat the dir another time	832	# stat the dir another time
566	aioreq_pri $pri;	833	aioreq_pri $pri;
…		…
572	# take the slow route if anything looks fishy	839	# take the slow route if anything looks fishy
573	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	840	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
574	$ndirs = -1;	841	$ndirs = -1;
575	} else {	842	} else {
576	# if nlink == 2, we are finished	843	# if nlink == 2, we are finished
577	# on non-posix-fs's, we rely on nlink < 2	844	# for non-posix-fs's, we rely on nlink < 2
578	$ndirs = (stat _)[3] - 2	845	$ndirs = (stat _)[3] - 2
579	or return $grp->result ([], $entries);	846	or return $grp->result ([], $entries);
580	}	847	}
581		848
582	# sort into likely dirs and likely nondirs
583	# dirs == files without ".", short entries first
584	$entries = [map $_->[0],
585	sort { $b->[1] cmp $a->[1] }
586	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
587	@$entries];
588
589	my (@dirs, @nondirs);	849	my (@dirs, @nondirs);
590		850
591	my $statgrp = add $grp aio_group sub {	851	my $statgrp = add $grp aio_group sub {
592	$grp->result (\@dirs, \@nondirs);	852	$grp->result (\@dirs, \@nondirs);
593	};	853	};
594		854
595	limit $statgrp $maxreq;	855	limit $statgrp $maxreq;
596	feed $statgrp sub {	856	feed $statgrp sub {
597	return unless @$entries;	857	return unless @$entries;
598	my $entry = pop @$entries;	858	my $entry = shift @$entries;
599		859
600	aioreq_pri $pri;	860	aioreq_pri $pri;
601	add $statgrp aio_stat "$path/$entry/.", sub {	861	add $statgrp aio_stat "$path/$entry/.", sub {
602	if ($_[0] < 0) {	862	if ($_[0] < 0) {
603	push @nondirs, $entry;	863	push @nondirs, $entry;
…		…
624	};	884	};
625		885
626	$grp	886	$grp
627	}	887	}
628		888
		889	=item aio_rmtree $path, $callback->($status)
		890
		891	Delete a directory tree starting (and including) C<$path>, return the
		892	status of the final C<rmdir> only. This is a composite request that
		893	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		894	everything else.
		895
		896	=cut
		897
		898	sub aio_rmtree;
		899	sub aio_rmtree($;$) {
		900	my ($path, $cb) = @_;
		901
		902	my $pri = aioreq_pri;
		903	my $grp = aio_group $cb;
		904
		905	aioreq_pri $pri;
		906	add $grp aio_scandir $path, 0, sub {
		907	my ($dirs, $nondirs) = @_;
		908
		909	my $dirgrp = aio_group sub {
		910	add $grp aio_rmdir $path, sub {
		911	$grp->result ($_[0]);
		912	};
		913	};
		914
		915	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		916	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		917
		918	add $grp $dirgrp;
		919	};
		920
		921	$grp
		922	}
		923
		924	=item aio_sync $callback->($status)
		925
		926	Asynchronously call sync and call the callback when finished.
		927
629	=item aio_fsync $fh, $callback->($status)	928	=item aio_fsync $fh, $callback->($status)
630		929
631	Asynchronously call fsync on the given filehandle and call the callback	930	Asynchronously call fsync on the given filehandle and call the callback
632	with the fsync result code.	931	with the fsync result code.
633		932
…		…
636	Asynchronously call fdatasync on the given filehandle and call the	935	Asynchronously call fdatasync on the given filehandle and call the
637	callback with the fdatasync result code.	936	callback with the fdatasync result code.
638		937
639	If this call isn't available because your OS lacks it or it couldn't be	938	If this call isn't available because your OS lacks it or it couldn't be
640	detected, it will be emulated by calling C<fsync> instead.	939	detected, it will be emulated by calling C<fsync> instead.
		940
		941	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		942
		943	Sync the data portion of the file specified by C<$offset> and C<$length>
		944	to disk (but NOT the metadata), by calling the Linux-specific
		945	sync_file_range call. If sync_file_range is not available or it returns
		946	ENOSYS, then fdatasync or fsync is being substituted.
		947
		948	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		949	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		950	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		951	manpage for details.
		952
		953	=item aio_pathsync $path, $callback->($status)
		954
		955	This request tries to open, fsync and close the given path. This is a
		956	composite request intended to sync directories after directory operations
		957	(E.g. rename). This might not work on all operating systems or have any
		958	specific effect, but usually it makes sure that directory changes get
		959	written to disc. It works for anything that can be opened for read-only,
		960	not just directories.
		961
		962	Future versions of this function might fall back to other methods when
		963	C<fsync> on the directory fails (such as calling C<sync>).
		964
		965	Passes C<0> when everything went ok, and C<-1> on error.
		966
		967	=cut
		968
		969	sub aio_pathsync($;$) {
		970	my ($path, $cb) = @_;
		971
		972	my $pri = aioreq_pri;
		973	my $grp = aio_group $cb;
		974
		975	aioreq_pri $pri;
		976	add $grp aio_open $path, O_RDONLY, 0, sub {
		977	my ($fh) = @_;
		978	if ($fh) {
		979	aioreq_pri $pri;
		980	add $grp aio_fsync $fh, sub {
		981	$grp->result ($_[0]);
		982
		983	aioreq_pri $pri;
		984	add $grp aio_close $fh;
		985	};
		986	} else {
		987	$grp->result (-1);
		988	}
		989	};
		990
		991	$grp
		992	}
641		993
642	=item aio_group $callback->(...)	994	=item aio_group $callback->(...)
643		995
644	This is a very special aio request: Instead of doing something, it is a	996	This is a very special aio request: Instead of doing something, it is a
645	container for other aio requests, which is useful if you want to bundle	997	container for other aio requests, which is useful if you want to bundle
…		…
695	=item cancel $req	1047	=item cancel $req
696		1048
697	Cancels the request, if possible. Has the effect of skipping execution	1049	Cancels the request, if possible. Has the effect of skipping execution
698	when entering the B<execute> state and skipping calling the callback when	1050	when entering the B<execute> state and skipping calling the callback when
699	entering the the B<result> state, but will leave the request otherwise	1051	entering the the B<result> state, but will leave the request otherwise
700	untouched. That means that requests that currently execute will not be	1052	untouched (with the exception of readdir). That means that requests that
701	stopped and resources held by the request will not be freed prematurely.	1053	currently execute will not be stopped and resources held by the request
		1054	will not be freed prematurely.
702		1055
703	=item cb $req $callback->(...)	1056	=item cb $req $callback->(...)
704		1057
705	Replace (or simply set) the callback registered to the request.	1058	Replace (or simply set) the callback registered to the request.
706		1059
…		…
757	Their lifetime, simplified, looks like this: when they are empty, they	1110	Their lifetime, simplified, looks like this: when they are empty, they
758	will finish very quickly. If they contain only requests that are in the	1111	will finish very quickly. If they contain only requests that are in the
759	C<done> state, they will also finish. Otherwise they will continue to	1112	C<done> state, they will also finish. Otherwise they will continue to
760	exist.	1113	exist.
761		1114
762	That means after creating a group you have some time to add requests. And	1115	That means after creating a group you have some time to add requests
763	in the callbacks of those requests, you can add further requests to the	1116	(precisely before the callback has been invoked, which is only done within
764	group. And only when all those requests have finished will the the group	1117	the C<poll_cb>). And in the callbacks of those requests, you can add
765	itself finish.	1118	further requests to the group. And only when all those requests have
		1119	finished will the the group itself finish.
766		1120
767	=over 4	1121	=over 4
768		1122
769	=item add $grp ...	1123	=item add $grp ...
770		1124
…		…
779	=item $grp->cancel_subs	1133	=item $grp->cancel_subs
780		1134
781	Cancel all subrequests and clears any feeder, but not the group request	1135	Cancel all subrequests and clears any feeder, but not the group request
782	itself. Useful when you queued a lot of events but got a result early.	1136	itself. Useful when you queued a lot of events but got a result early.
783		1137
		1138	The group request will finish normally (you cannot add requests to the
		1139	group).
		1140
784	=item $grp->result (...)	1141	=item $grp->result (...)
785		1142
786	Set the result value(s) that will be passed to the group callback when all	1143	Set the result value(s) that will be passed to the group callback when all
787	subrequests have finished and set thre groups errno to the current value	1144	subrequests have finished and set the groups errno to the current value
788	of errno (just like calling C<errno> without an error number). By default,	1145	of errno (just like calling C<errno> without an error number). By default,
789	no argument will be passed and errno is zero.	1146	no argument will be passed and errno is zero.
790		1147
791	=item $grp->errno ([$errno])	1148	=item $grp->errno ([$errno])
792		1149
…		…
803	=item feed $grp $callback->($grp)	1160	=item feed $grp $callback->($grp)
804		1161
805	Sets a feeder/generator on this group: every group can have an attached	1162	Sets a feeder/generator on this group: every group can have an attached
806	generator that generates requests if idle. The idea behind this is that,	1163	generator that generates requests if idle. The idea behind this is that,
807	although you could just queue as many requests as you want in a group,	1164	although you could just queue as many requests as you want in a group,
808	this might starve other requests for a potentially long time. For	1165	this might starve other requests for a potentially long time. For example,
809	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1166	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
810	requests, delaying any later requests for a long time.	1167	delaying any later requests for a long time.
811		1168
812	To avoid this, and allow incremental generation of requests, you can	1169	To avoid this, and allow incremental generation of requests, you can
813	instead a group and set a feeder on it that generates those requests. The	1170	instead a group and set a feeder on it that generates those requests. The
814	feed callback will be called whenever there are few enough (see C<limit>,	1171	feed callback will be called whenever there are few enough (see C<limit>,
815	below) requests active in the group itself and is expected to queue more	1172	below) requests active in the group itself and is expected to queue more
…		…
819	not impose any limits).	1176	not impose any limits).
820		1177
821	If the feed does not queue more requests when called, it will be	1178	If the feed does not queue more requests when called, it will be
822	automatically removed from the group.	1179	automatically removed from the group.
823		1180
824	If the feed limit is C<0>, it will be set to C<2> automatically.	1181	If the feed limit is C<0> when this method is called, it will be set to
		1182	C<2> automatically.
825		1183
826	Example:	1184	Example:
827		1185
828	# stat all files in @files, but only ever use four aio requests concurrently:	1186	# stat all files in @files, but only ever use four aio requests concurrently:
829		1187
…		…
841	Sets the feeder limit for the group: The feeder will be called whenever	1199	Sets the feeder limit for the group: The feeder will be called whenever
842	the group contains less than this many requests.	1200	the group contains less than this many requests.
843		1201
844	Setting the limit to C<0> will pause the feeding process.	1202	Setting the limit to C<0> will pause the feeding process.
845		1203
		1204	The default value for the limit is C<0>, but note that setting a feeder
		1205	automatically bumps it up to C<2>.
		1206
846	=back	1207	=back
847		1208
848	=head2 SUPPORT FUNCTIONS	1209	=head2 SUPPORT FUNCTIONS
849		1210
		1211	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1212
850	=over 4	1213	=over 4
851		1214
852	=item $fileno = IO::AIO::poll_fileno	1215	=item $fileno = IO::AIO::poll_fileno
853		1216
854	Return the I<request result pipe file descriptor>. This filehandle must be	1217	Return the I<request result pipe file descriptor>. This filehandle must be
855	polled for reading by some mechanism outside this module (e.g. Event or	1218	polled for reading by some mechanism outside this module (e.g. EV, Glib,
856	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1219	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
857	to call C<poll_cb> to check the results.	1220	you have to call C<poll_cb> to check the results.
858		1221
859	See C<poll_cb> for an example.	1222	See C<poll_cb> for an example.
860		1223
861	=item IO::AIO::poll_cb	1224	=item IO::AIO::poll_cb
862		1225
863	Process all outstanding events on the result pipe. You have to call this	1226	Process some outstanding events on the result pipe. You have to call this
864	regularly. Returns the number of events processed. Returns immediately	1227	regularly. Returns C<0> if all events could be processed, or C<-1> if it
865	when no events are outstanding.	1228	returned earlier for whatever reason. Returns immediately when no events
		1229	are outstanding. The amount of events processed depends on the settings of
		1230	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
866		1231
867	If not all requests were processed for whatever reason, the filehandle	1232	If not all requests were processed for whatever reason, the filehandle
868	will still be ready when C<poll_cb> returns.	1233	will still be ready when C<poll_cb> returns, so normally you don't have to
		1234	do anything special to have it called later.
869		1235
870	Example: Install an Event watcher that automatically calls	1236	Example: Install an Event watcher that automatically calls
871	IO::AIO::poll_cb with high priority:	1237	IO::AIO::poll_cb with high priority (more examples can be found in the
		1238	SYNOPSIS section, at the top of this document):
872		1239
873	Event->io (fd => IO::AIO::poll_fileno,	1240	Event->io (fd => IO::AIO::poll_fileno,
874	poll => 'r', async => 1,	1241	poll => 'r', async => 1,
875	cb => \&IO::AIO::poll_cb);	1242	cb => \&IO::AIO::poll_cb);
876		1243
877	=item IO::AIO::poll_some $max_requests	1244	=item IO::AIO::max_poll_reqs $nreqs
878		1245
879	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests	1246	=item IO::AIO::max_poll_time $seconds
880	at a time.
881		1247
882	Useful if you want to ensure some level of interactiveness when perl is	1248	These set the maximum number of requests (default C<0>, meaning infinity)
883	not fast enough to process all requests in time.	1249	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1250	the maximum amount of time (default C<0>, meaning infinity) spent in
		1251	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1252	of time C<poll_cb> is allowed to use).
		1253
		1254	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1255	syscall per request processed, which is not normally a problem unless your
		1256	callbacks are really really fast or your OS is really really slow (I am
		1257	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1258
		1259	Setting these is useful if you want to ensure some level of
		1260	interactiveness when perl is not fast enough to process all requests in
		1261	time.
		1262
		1263	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
884		1264
885	Example: Install an Event watcher that automatically calls	1265	Example: Install an Event watcher that automatically calls
886	IO::AIO::poll_some with low priority, to ensure that other parts of the	1266	IO::AIO::poll_cb with low priority, to ensure that other parts of the
887	program get the CPU sometimes even under high AIO load.	1267	program get the CPU sometimes even under high AIO load.
888		1268
		1269	# try not to spend much more than 0.1s in poll_cb
		1270	IO::AIO::max_poll_time 0.1;
		1271
		1272	# use a low priority so other tasks have priority
889	Event->io (fd => IO::AIO::poll_fileno,	1273	Event->io (fd => IO::AIO::poll_fileno,
890	poll => 'r', nice => 1,	1274	poll => 'r', nice => 1,
891	cb => sub { IO::AIO::poll_some 256 });	1275	cb => &IO::AIO::poll_cb);
892		1276
893	=item IO::AIO::poll_wait	1277	=item IO::AIO::poll_wait
894		1278
		1279	If there are any outstanding requests and none of them in the result
895	Wait till the result filehandle becomes ready for reading (simply does a	1280	phase, wait till the result filehandle becomes ready for reading (simply
896	C<select> on the filehandle. This is useful if you want to synchronously wait	1281	does a C<select> on the filehandle. This is useful if you want to
897	for some requests to finish).	1282	synchronously wait for some requests to finish).
898		1283
899	See C<nreqs> for an example.	1284	See C<nreqs> for an example.
900		1285
		1286	=item IO::AIO::poll
		1287
		1288	Waits until some requests have been handled.
		1289
		1290	Returns the number of requests processed, but is otherwise strictly
		1291	equivalent to:
		1292
		1293	IO::AIO::poll_wait, IO::AIO::poll_cb
		1294
901	=item IO::AIO::nreqs	1295	=item IO::AIO::flush
902		1296
903	Returns the number of requests currently in the ready, execute or pending	1297	Wait till all outstanding AIO requests have been handled.
904	states (i.e. for which their callback has not been invoked yet).
905		1298
906	Example: wait till there are no outstanding requests anymore:	1299	Strictly equivalent to:
907		1300
908	IO::AIO::poll_wait, IO::AIO::poll_cb	1301	IO::AIO::poll_wait, IO::AIO::poll_cb
909	while IO::AIO::nreqs;	1302	while IO::AIO::nreqs;
910		1303
911	=item IO::AIO::nready	1304	=back
912		1305
913	Returns the number of requests currently in the ready state (not yet	1306	=head3 CONTROLLING THE NUMBER OF THREADS
914	executed).
915		1307
916	=item IO::AIO::npending	1308	=over
917
918	Returns the number of requests currently in the pending state (executed,
919	but not yet processed by poll_cb).
920
921	=item IO::AIO::flush
922
923	Wait till all outstanding AIO requests have been handled.
924
925	Strictly equivalent to:
926
927	IO::AIO::poll_wait, IO::AIO::poll_cb
928	while IO::AIO::nreqs;
929
930	=item IO::AIO::poll
931
932	Waits until some requests have been handled.
933
934	Strictly equivalent to:
935
936	IO::AIO::poll_wait, IO::AIO::poll_cb
937	if IO::AIO::nreqs;
938		1309
939	=item IO::AIO::min_parallel $nthreads	1310	=item IO::AIO::min_parallel $nthreads
940		1311
941	Set the minimum number of AIO threads to C<$nthreads>. The current	1312	Set the minimum number of AIO threads to C<$nthreads>. The current
942	default is C<8>, which means eight asynchronous operations can execute	1313	default is C<8>, which means eight asynchronous operations can execute
943	concurrently at any one time (the number of outstanding requests,	1314	concurrently at any one time (the number of outstanding requests,
944	however, is unlimited).	1315	however, is unlimited).
945		1316
946	IO::AIO starts threads only on demand, when an AIO request is queued and	1317	IO::AIO starts threads only on demand, when an AIO request is queued and
947	no free thread exists.	1318	no free thread exists. Please note that queueing up a hundred requests can
		1319	create demand for a hundred threads, even if it turns out that everything
		1320	is in the cache and could have been processed faster by a single thread.
948		1321
949	It is recommended to keep the number of threads relatively low, as some	1322	It is recommended to keep the number of threads relatively low, as some
950	Linux kernel versions will scale negatively with the number of threads	1323	Linux kernel versions will scale negatively with the number of threads
951	(higher parallelity => MUCH higher latency). With current Linux 2.6	1324	(higher parallelity => MUCH higher latency). With current Linux 2.6
952	versions, 4-32 threads should be fine.	1325	versions, 4-32 threads should be fine.
…		…
966	This module automatically runs C<max_parallel 0> at program end, to ensure	1339	This module automatically runs C<max_parallel 0> at program end, to ensure
967	that all threads are killed and that there are no outstanding requests.	1340	that all threads are killed and that there are no outstanding requests.
968		1341
969	Under normal circumstances you don't need to call this function.	1342	Under normal circumstances you don't need to call this function.
970		1343
		1344	=item IO::AIO::max_idle $nthreads
		1345
		1346	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1347	threads that did not get a request to process within 10 seconds). That
		1348	means if a thread becomes idle while C<$nthreads> other threads are also
		1349	idle, it will free its resources and exit.
		1350
		1351	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1352	to allow for extremely high load situations, but want to free resources
		1353	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1354
		1355	The default is probably ok in most situations, especially if thread
		1356	creation is fast. If thread creation is very slow on your system you might
		1357	want to use larger values.
		1358
971	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1359	=item IO::AIO::max_outstanding $maxreqs
972		1360
973	This is a very bad function to use in interactive programs because it	1361	This is a very bad function to use in interactive programs because it
974	blocks, and a bad way to reduce concurrency because it is inexact: Better	1362	blocks, and a bad way to reduce concurrency because it is inexact: Better
975	use an C<aio_group> together with a feed callback.	1363	use an C<aio_group> together with a feed callback.
976		1364
977	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1365	Sets the maximum number of outstanding requests to C<$nreqs>. If you
978	to queue up more than this number of requests, the next call to the	1366	do queue up more than this number of requests, the next call to the
979	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)	1367	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
980	function will block until the limit is no longer exceeded.	1368	function will block until the limit is no longer exceeded.
981		1369
982	The default value is very large, so there is no practical limit on the	1370	The default value is very large, so there is no practical limit on the
983	number of outstanding requests.	1371	number of outstanding requests.
984		1372
985	You can still queue as many requests as you want. Therefore,	1373	You can still queue as many requests as you want. Therefore,
986	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1374	C<max_outstanding> is mainly useful in simple scripts (with low values) or
987	as a stop gap to shield against fatal memory overflow (with large values).	1375	as a stop gap to shield against fatal memory overflow (with large values).
988		1376
989	=back	1377	=back
990		1378
		1379	=head3 STATISTICAL INFORMATION
		1380
		1381	=over
		1382
		1383	=item IO::AIO::nreqs
		1384
		1385	Returns the number of requests currently in the ready, execute or pending
		1386	states (i.e. for which their callback has not been invoked yet).
		1387
		1388	Example: wait till there are no outstanding requests anymore:
		1389
		1390	IO::AIO::poll_wait, IO::AIO::poll_cb
		1391	while IO::AIO::nreqs;
		1392
		1393	=item IO::AIO::nready
		1394
		1395	Returns the number of requests currently in the ready state (not yet
		1396	executed).
		1397
		1398	=item IO::AIO::npending
		1399
		1400	Returns the number of requests currently in the pending state (executed,
		1401	but not yet processed by poll_cb).
		1402
		1403	=back
		1404
		1405	=head3 MISCELLANEOUS FUNCTIONS
		1406
		1407	IO::AIO implements some functions that might be useful, but are not
		1408	asynchronous.
		1409
		1410	=over 4
		1411
		1412	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1413
		1414	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1415	but is blocking (this makes most sense if you know the input data is
		1416	likely cached already and the output filehandle is set to non-blocking
		1417	operations).
		1418
		1419	Returns the number of bytes copied, or C<-1> on error.
		1420
		1421	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1422
		1423	Simply calls the C<posix_fadvise> function (see it's
		1424	manpage for details). The following advice constants are
		1425	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1426	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1427	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1428
		1429	On systems that do not implement C<posix_fadvise>, this function returns
		1430	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1431
		1432	=back
		1433
991	=cut	1434	=cut
992		1435
993	# support function to convert a fd into a perl filehandle
994	sub _fd2fh {
995	return undef if $_[0] < 0;
996
997	# try to generate nice filehandles
998	my $sym = "IO::AIO::fd#$_[0]";
999	local *$sym;
1000
1001	open *$sym, "+<&=$_[0]" # usually works under any unix
1002	or open *$sym, "<&=$_[0]" # cygwin needs this
1003	or open *$sym, ">&=$_[0]" # or this
1004	or return undef;
1005
1006	*$sym
1007	}
1008
1009	min_parallel 8;	1436	min_parallel 8;
1010		1437
1011	END {	1438	END { flush }
1012	min_parallel 1;
1013	flush;
1014	};
1015		1439
1016	1;	1440	1;
1017		1441
1018	=head2 FORK BEHAVIOUR	1442	=head2 FORK BEHAVIOUR
1019		1443
…		…
1039	bytes of memory. In addition, stat requests need a stat buffer (possibly	1463	bytes of memory. In addition, stat requests need a stat buffer (possibly
1040	a few hundred bytes), readdir requires a result buffer and so on. Perl	1464	a few hundred bytes), readdir requires a result buffer and so on. Perl
1041	scalars and other data passed into aio requests will also be locked and	1465	scalars and other data passed into aio requests will also be locked and
1042	will consume memory till the request has entered the done state.	1466	will consume memory till the request has entered the done state.
1043		1467
1044	This is now awfully much, so queuing lots of requests is not usually a	1468	This is not awfully much, so queuing lots of requests is not usually a
1045	problem.	1469	problem.
1046		1470
1047	Per-thread usage:	1471	Per-thread usage:
1048		1472
1049	In the execution phase, some aio requests require more memory for	1473	In the execution phase, some aio requests require more memory for
…		…
1054		1478
1055	Known bugs will be fixed in the next release.	1479	Known bugs will be fixed in the next release.
1056		1480
1057	=head1 SEE ALSO	1481	=head1 SEE ALSO
1058		1482
1059	L<Coro::AIO>.	1483	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1484	more natural syntax.
1060		1485
1061	=head1 AUTHOR	1486	=head1 AUTHOR
1062		1487
1063	Marc Lehmann <schmorp@schmorp.de>	1488	Marc Lehmann <schmorp@schmorp.de>
1064	http://home.schmorp.de/	1489	http://home.schmorp.de/

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Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC vs.
Revision 1.168 by root, Mon Nov 30 22:22:13 2009 UTC