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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC vs.
Revision 1.171 by root, Sat Jan 2 14:24:32 2010 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>).
		59
		60	Asynchronous means that operations that can normally block your program
		61	(e.g. reading from disk) will be done asynchronously: the operation
		62	will still block, but you can do something else in the meantime. This
		63	is extremely useful for programs that need to stay interactive even
		64	when doing heavy I/O (GUI programs, high performance network servers
		65	etc.), but can also be used to easily do operations in parallel that are
		66	normally done sequentially, e.g. stat'ing many files, which is much faster
		67	on a RAID volume or over NFS when you do a number of stat operations
		68	concurrently.
		69
		70	While most of this works on all types of file descriptors (for
		71	example sockets), using these functions on file descriptors that
		72	support nonblocking operation (again, sockets, pipes etc.) is
		73	very inefficient. Use an event loop for that (such as the L<EV>
		74	module): IO::AIO will naturally fit into such an event loop itself.
55		75
56	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
57	requests and signal their completion. You don't need thread support	77	requests and signal their completion. You don't need thread support
58	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
59	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
60	functions available on many operating systems. However, they are often	80	functions available on many operating systems. However, they are often
61	not well-supported or restricted (Linux doesn't allow them on normal	81	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	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
63	aio_write, so the remaining functionality would have to be implemented	83	aio_write, so the remaining functionality would have to be implemented
64	using threads anyway.	84	using threads anyway.
65		85
66	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,
67	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
68	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
69	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;
70		132
71	=head1 REQUEST ANATOMY AND LIFETIME	133	=head1 REQUEST ANATOMY AND LIFETIME
72		134
73	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
74	directly visible to Perl.	136	directly visible to Perl.
…		…
116	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
117	(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
118	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
119	result in a runtime error).	181	result in a runtime error).
120		182
		183	=back
		184
121	=cut	185	=cut
122		186
123	package IO::AIO;	187	package IO::AIO;
124		188
125	no warnings;	189	use Carp ();
126	use strict 'vars';	190
		191	use common::sense;
127		192
128	use base 'Exporter';	193	use base 'Exporter';
129		194
130	BEGIN {	195	BEGIN {
131	our $VERSION = '2.0';	196	our $VERSION = '3.4';
132		197
133	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
134	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
135	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	200	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
136	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	aio_msync aio_mtouch);
		206
137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	207	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	208	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139	min_parallel max_parallel nreqs nready npending);	209	min_parallel max_parallel max_idle
		210	nreqs nready npending nthreads
		211	max_poll_time max_poll_reqs
		212	sendfile fadvise);
		213
		214	push @AIO_REQ, qw(aio_busy); # not exported
140		215
141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142		217
143	require XSLoader;	218	require XSLoader;
144	XSLoader::load ("IO::AIO", $VERSION);	219	XSLoader::load ("IO::AIO", $VERSION);
145	}	220	}
146		221
147	=head1 FUNCTIONS	222	=head1 FUNCTIONS
148		223
149	=head2 AIO FUNCTIONS	224	=head2 AIO REQUEST FUNCTIONS
150		225
151	All the C<aio_*> calls are more or less thin wrappers around the syscall	226	All the C<aio_*> calls are more or less thin wrappers around the syscall
152	with the same name (sans C<aio_>). The arguments are similar or identical,	227	with the same name (sans C<aio_>). The arguments are similar or identical,
153	and they all accept an additional (and optional) C<$callback> argument	228	and they all accept an additional (and optional) C<$callback> argument
154	which must be a code reference. This code reference will get called with	229	which must be a code reference. This code reference will get called with
155	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	230	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
156	perl, which usually delivers "false") as it's sole argument when the given	231	perl, which usually delivers "false") as its sole argument after the given
157	syscall has been executed asynchronously.	232	syscall has been executed asynchronously.
158		233
159	All functions expecting a filehandle keep a copy of the filehandle	234	All functions expecting a filehandle keep a copy of the filehandle
160	internally until the request has finished.	235	internally until the request has finished.
161		236
162	All requests return objects of type L<IO::AIO::REQ> that allow further	237	All functions return request objects of type L<IO::AIO::REQ> that allow
163	manipulation of those requests while they are in-flight.	238	further manipulation of those requests while they are in-flight.
164		239
165	The pathnames you pass to these routines I<must> be absolute and	240	The pathnames you pass to these routines I<must> be absolute and
166	encoded in byte form. The reason for the former is that at the time the	241	encoded as octets. The reason for the former is that at the time the
167	request is being executed, the current working directory could have	242	request is being executed, the current working directory could have
168	changed. Alternatively, you can make sure that you never change the	243	changed. Alternatively, you can make sure that you never change the
169	current working directory.	244	current working directory anywhere in the program and then use relative
		245	paths.
170		246
171	To encode pathnames to byte form, either make sure you either: a)	247	To encode pathnames as octets, either make sure you either: a) always pass
172	always pass in filenames you got from outside (command line, readdir	248	in filenames you got from outside (command line, readdir etc.) without
173	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	249	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
174	your pathnames to the locale (or other) encoding in effect in the user	250	your pathnames to the locale (or other) encoding in effect in the user
175	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	251	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176	use something else.	252	use something else to ensure your scalar has the correct contents.
		253
		254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		255	handles correctly whether it is set or not.
177		256
178	=over 4	257	=over 4
179		258
180	=item $prev_pri = aioreq_pri [$pri]	259	=item $prev_pri = aioreq_pri [$pri]
181		260
…		…
201	aio_read $_[0], ..., sub {	280	aio_read $_[0], ..., sub {
202	...	281	...
203	};	282	};
204	};	283	};
205		284
		285
206	=item aioreq_nice $pri_adjust	286	=item aioreq_nice $pri_adjust
207		287
208	Similar to C<aioreq_pri>, but subtracts the given value from the current	288	Similar to C<aioreq_pri>, but subtracts the given value from the current
209	priority, so effects are cumulative.	289	priority, so the effect is cumulative.
		290
210		291
211	=item aio_open $pathname, $flags, $mode, $callback->($fh)	292	=item aio_open $pathname, $flags, $mode, $callback->($fh)
212		293
213	Asynchronously open or create a file and call the callback with a newly	294	Asynchronously open or create a file and call the callback with a newly
214	created filehandle for the file.	295	created filehandle for the file.
…		…
220	list. They are the same as used by C<sysopen>.	301	list. They are the same as used by C<sysopen>.
221		302
222	Likewise, C<$mode> specifies the mode of the newly created file, if it	303	Likewise, C<$mode> specifies the mode of the newly created file, if it
223	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	304	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
224	except that it is mandatory (i.e. use C<0> if you don't create new files,	305	except that it is mandatory (i.e. use C<0> if you don't create new files,
225	and C<0666> or C<0777> if you do).	306	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		307	by the umask in effect then the request is being executed, so better never
		308	change the umask.
226		309
227	Example:	310	Example:
228		311
229	aio_open "/etc/passwd", O_RDONLY, 0, sub {	312	aio_open "/etc/passwd", O_RDONLY, 0, sub {
230	if ($_[0]) {	313	if ($_[0]) {
…		…
233	} else {	316	} else {
234	die "open failed: $!\n";	317	die "open failed: $!\n";
235	}	318	}
236	};	319	};
237		320
		321
238	=item aio_close $fh, $callback->($status)	322	=item aio_close $fh, $callback->($status)
239		323
240	Asynchronously close a file and call the callback with the result	324	Asynchronously close a file and call the callback with the result
241	code. I<WARNING:> although accepted, you should not pass in a perl	325	code.
242	filehandle here, as perl will likely close the file descriptor another
243	time when the filehandle is destroyed. Normally, you can safely call perls
244	C<close> or just let filehandles go out of scope.
245		326
246	This is supposed to be a bug in the API, so that might change. It's	327	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
247	therefore best to avoid this function.	328	closing the file descriptor associated with the filehandle itself.
		329
		330	Therefore, C<aio_close> will not close the filehandle - instead it will
		331	use dup2 to overwrite the file descriptor with the write-end of a pipe
		332	(the pipe fd will be created on demand and will be cached).
		333
		334	Or in other words: the file descriptor will be closed, but it will not be
		335	free for reuse until the perl filehandle is closed.
		336
		337	=cut
248		338
249	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250		340
251	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252		342
253	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	343	Reads or writes C<$length> bytes from or to the specified C<$fh> and
254	into the scalar given by C<data> and offset C<dataoffset> and calls the	344	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
255	callback without the actual number of bytes read (or -1 on error, just	345	and calls the callback without the actual number of bytes read (or -1 on
256	like the syscall).	346	error, just like the syscall).
		347
		348	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		349	offset plus the actual number of bytes read.
		350
		351	If C<$offset> is undefined, then the current file descriptor offset will
		352	be used (and updated), otherwise the file descriptor offset will not be
		353	changed by these calls.
		354
		355	If C<$length> is undefined in C<aio_write>, use the remaining length of
		356	C<$data>.
		357
		358	If C<$dataoffset> is less than zero, it will be counted from the end of
		359	C<$data>.
257		360
258	The C<$data> scalar I<MUST NOT> be modified in any way while the request	361	The C<$data> scalar I<MUST NOT> be modified in any way while the request
259	is outstanding. Modifying it can result in segfaults or WW3 (if the	362	is outstanding. Modifying it can result in segfaults or World War III (if
260	necessary/optional hardware is installed).	363	the necessary/optional hardware is installed).
261		364
262	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	365	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263	offset C<0> within the scalar:	366	offset C<0> within the scalar:
264		367
265	aio_read $fh, 7, 15, $buffer, 0, sub {	368	aio_read $fh, 7, 15, $buffer, 0, sub {
266	$_[0] > 0 or die "read error: $!";	369	$_[0] > 0 or die "read error: $!";
267	print "read $_[0] bytes: <$buffer>\n";	370	print "read $_[0] bytes: <$buffer>\n";
268	};	371	};
		372
269		373
270	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	374	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
271		375
272	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	376	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
273	reading at byte offset C<$in_offset>, and starts writing at the current	377	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
277		381
278	This call tries to make use of a native C<sendfile> syscall to provide	382	This call tries to make use of a native C<sendfile> syscall to provide
279	zero-copy operation. For this to work, C<$out_fh> should refer to a	383	zero-copy operation. For this to work, C<$out_fh> should refer to a
280	socket, and C<$in_fh> should refer to mmap'able file.	384	socket, and C<$in_fh> should refer to mmap'able file.
281		385
282	If the native sendfile call fails or is not implemented, it will be	386	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		387	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
283	emulated, so you can call C<aio_sendfile> on any type of filehandle	388	it will be emulated, so you can call C<aio_sendfile> on any type of
284	regardless of the limitations of the operating system.	389	filehandle regardless of the limitations of the operating system.
285		390
286	Please note, however, that C<aio_sendfile> can read more bytes from	391	Please note, however, that C<aio_sendfile> can read more bytes from
287	C<$in_fh> than are written, and there is no way to find out how many	392	C<$in_fh> than are written, and there is no way to find out how many
288	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	393	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
289	provides the number of bytes written to C<$out_fh>. Only if the result	394	provides the number of bytes written to C<$out_fh>. Only if the result
290	value equals C<$length> one can assume that C<$length> bytes have been	395	value equals C<$length> one can assume that C<$length> bytes have been
291	read.	396	read.
		397
292		398
293	=item aio_readahead $fh,$offset,$length, $callback->($retval)	399	=item aio_readahead $fh,$offset,$length, $callback->($retval)
294		400
295	C<aio_readahead> populates the page cache with data from a file so that	401	C<aio_readahead> populates the page cache with data from a file so that
296	subsequent reads from that file will not block on disk I/O. The C<$offset>	402	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
302	file. The current file offset of the file is left unchanged.	408	file. The current file offset of the file is left unchanged.
303		409
304	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	410	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
305	emulated by simply reading the data, which would have a similar effect.	411	emulated by simply reading the data, which would have a similar effect.
306		412
		413
307	=item aio_stat $fh_or_path, $callback->($status)	414	=item aio_stat $fh_or_path, $callback->($status)
308		415
309	=item aio_lstat $fh, $callback->($status)	416	=item aio_lstat $fh, $callback->($status)
310		417
311	Works like perl's C<stat> or C<lstat> in void context. The callback will	418	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
324	aio_stat "/etc/passwd", sub {	431	aio_stat "/etc/passwd", sub {
325	$_[0] and die "stat failed: $!";	432	$_[0] and die "stat failed: $!";
326	print "size is ", -s _, "\n";	433	print "size is ", -s _, "\n";
327	};	434	};
328		435
		436
		437	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		438
		439	Works like perl's C<utime> function (including the special case of $atime
		440	and $mtime being undef). Fractional times are supported if the underlying
		441	syscalls support them.
		442
		443	When called with a pathname, uses utimes(2) if available, otherwise
		444	utime(2). If called on a file descriptor, uses futimes(2) if available,
		445	otherwise returns ENOSYS, so this is not portable.
		446
		447	Examples:
		448
		449	# set atime and mtime to current time (basically touch(1)):
		450	aio_utime "path", undef, undef;
		451	# set atime to current time and mtime to beginning of the epoch:
		452	aio_utime "path", time, undef; # undef==0
		453
		454
		455	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		456
		457	Works like perl's C<chown> function, except that C<undef> for either $uid
		458	or $gid is being interpreted as "do not change" (but -1 can also be used).
		459
		460	Examples:
		461
		462	# same as "chown root path" in the shell:
		463	aio_chown "path", 0, -1;
		464	# same as above:
		465	aio_chown "path", 0, undef;
		466
		467
		468	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		469
		470	Works like truncate(2) or ftruncate(2).
		471
		472
		473	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		474
		475	Works like perl's C<chmod> function.
		476
		477
329	=item aio_unlink $pathname, $callback->($status)	478	=item aio_unlink $pathname, $callback->($status)
330		479
331	Asynchronously unlink (delete) a file and call the callback with the	480	Asynchronously unlink (delete) a file and call the callback with the
332	result code.	481	result code.
333		482
		483
334	=item aio_mknod $path, $mode, $dev, $callback->($status)	484	=item aio_mknod $path, $mode, $dev, $callback->($status)
335		485
		486	[EXPERIMENTAL]
		487
336	Asynchronously create a device node (or fifo). See mknod(2): the only	488	Asynchronously create a device node (or fifo). See mknod(2).
337	portable value for C<$mode> is C<S_IFIFO> ored with permissions, and C<0>	489
338	for C<$dev>.	490	The only (POSIX-) portable way of calling this function is:
		491
		492	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		493
339		494
340	=item aio_link $srcpath, $dstpath, $callback->($status)	495	=item aio_link $srcpath, $dstpath, $callback->($status)
341		496
342	Asynchronously create a new link to the existing object at C<$srcpath> at	497	Asynchronously create a new link to the existing object at C<$srcpath> at
343	the path C<$dstpath> and call the callback with the result code.	498	the path C<$dstpath> and call the callback with the result code.
344		499
		500
345	=item aio_symlink $srcpath, $dstpath, $callback->($status)	501	=item aio_symlink $srcpath, $dstpath, $callback->($status)
346		502
347	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	503	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
348	the path C<$dstpath> and call the callback with the result code.	504	the path C<$dstpath> and call the callback with the result code.
349		505
		506
		507	=item aio_readlink $path, $callback->($link)
		508
		509	Asynchronously read the symlink specified by C<$path> and pass it to
		510	the callback. If an error occurs, nothing or undef gets passed to the
		511	callback.
		512
		513
350	=item aio_rename $srcpath, $dstpath, $callback->($status)	514	=item aio_rename $srcpath, $dstpath, $callback->($status)
351		515
352	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	516	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
353	rename(2) and call the callback with the result code.	517	rename(2) and call the callback with the result code.
354		518
		519
		520	=item aio_mkdir $pathname, $mode, $callback->($status)
		521
		522	Asynchronously mkdir (create) a directory and call the callback with
		523	the result code. C<$mode> will be modified by the umask at the time the
		524	request is executed, so do not change your umask.
		525
		526
355	=item aio_rmdir $pathname, $callback->($status)	527	=item aio_rmdir $pathname, $callback->($status)
356		528
357	Asynchronously rmdir (delete) a directory and call the callback with the	529	Asynchronously rmdir (delete) a directory and call the callback with the
358	result code.	530	result code.
		531
359		532
360	=item aio_readdir $pathname, $callback->($entries)	533	=item aio_readdir $pathname, $callback->($entries)
361		534
362	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	535	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
363	directory (i.e. opendir + readdir + closedir). The entries will not be	536	directory (i.e. opendir + readdir + closedir). The entries will not be
364	sorted, and will B<NOT> include the C<.> and C<..> entries.	537	sorted, and will B<NOT> include the C<.> and C<..> entries.
365		538
366	The callback a single argument which is either C<undef> or an array-ref	539	The callback is passed a single argument which is either C<undef> or an
367	with the filenames.	540	array-ref with the filenames.
		541
		542
		543	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		544
		545	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		546	behaviour and output format. In case of an error, C<$entries> will be
		547	C<undef>.
		548
		549	The flags are a combination of the following constants, ORed together (the
		550	flags will also be passed to the callback, possibly modified):
		551
		552	=over 4
		553
		554	=item IO::AIO::READDIR_DENTS
		555
		556	When this flag is off, then the callback gets an arrayref with of names
		557	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		558	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		559	entry in more detail.
		560
		561	C<$name> is the name of the entry.
		562
		563	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		564
		565	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		566	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		567	C<IO::AIO::DT_WHT>.
		568
		569	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		570	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		571	scalars are read-only: you can not modify them.
		572
		573	C<$inode> is the inode number (which might not be exact on systems with 64
		574	bit inode numbers and 32 bit perls). This field has unspecified content on
		575	systems that do not deliver the inode information.
		576
		577	=item IO::AIO::READDIR_DIRS_FIRST
		578
		579	When this flag is set, then the names will be returned in an order where
		580	likely directories come first. This is useful when you need to quickly
		581	find directories, or you want to find all directories while avoiding to
		582	stat() each entry.
		583
		584	If the system returns type information in readdir, then this is used
		585	to find directories directly. Otherwise, likely directories are files
		586	beginning with ".", or otherwise files with no dots, of which files with
		587	short names are tried first.
		588
		589	=item IO::AIO::READDIR_STAT_ORDER
		590
		591	When this flag is set, then the names will be returned in an order
		592	suitable for stat()'ing each one. That is, when you plan to stat()
		593	all files in the given directory, then the returned order will likely
		594	be fastest.
		595
		596	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		597	the likely dirs come first, resulting in a less optimal stat order.
		598
		599	=item IO::AIO::READDIR_FOUND_UNKNOWN
		600
		601	This flag should not be set when calling C<aio_readdirx>. Instead, it
		602	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		603	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		604	C<$type>'s are known, which can be used to speed up some algorithms.
		605
		606	=back
		607
		608
		609	=item aio_load $path, $data, $callback->($status)
		610
		611	This is a composite request that tries to fully load the given file into
		612	memory. Status is the same as with aio_read.
		613
		614	=cut
		615
		616	sub aio_load($$;$) {
		617	my ($path, undef, $cb) = @_;
		618	my $data = \$_[1];
		619
		620	my $pri = aioreq_pri;
		621	my $grp = aio_group $cb;
		622
		623	aioreq_pri $pri;
		624	add $grp aio_open $path, O_RDONLY, 0, sub {
		625	my $fh = shift
		626	or return $grp->result (-1);
		627
		628	aioreq_pri $pri;
		629	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		630	$grp->result ($_[0]);
		631	};
		632	};
		633
		634	$grp
		635	}
368		636
369	=item aio_copy $srcpath, $dstpath, $callback->($status)	637	=item aio_copy $srcpath, $dstpath, $callback->($status)
370		638
371	Try to copy the I<file> (directories not supported as either source or	639	Try to copy the I<file> (directories not supported as either source or
372	destination) from C<$srcpath> to C<$dstpath> and call the callback with	640	destination) from C<$srcpath> to C<$dstpath> and call the callback with
373	the C<0> (error) or C<-1> ok.	641	a status of C<0> (ok) or C<-1> (error, see C<$!>).
374		642
375	This is a composite request that it creates the destination file with	643	This is a composite request that creates the destination file with
376	mode 0200 and copies the contents of the source file into it using	644	mode 0200 and copies the contents of the source file into it using
377	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	645	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
378	uid/gid, in that order.	646	uid/gid, in that order.
379		647
380	If an error occurs, the partial destination file will be unlinked, if	648	If an error occurs, the partial destination file will be unlinked, if
…		…
390	my $grp = aio_group $cb;	658	my $grp = aio_group $cb;
391		659
392	aioreq_pri $pri;	660	aioreq_pri $pri;
393	add $grp aio_open $src, O_RDONLY, 0, sub {	661	add $grp aio_open $src, O_RDONLY, 0, sub {
394	if (my $src_fh = $_[0]) {	662	if (my $src_fh = $_[0]) {
395	my @stat = stat $src_fh;	663	my @stat = stat $src_fh; # hmm, might block over nfs?
396		664
397	aioreq_pri $pri;	665	aioreq_pri $pri;
398	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {	666	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
399	if (my $dst_fh = $_[0]) {	667	if (my $dst_fh = $_[0]) {
400	aioreq_pri $pri;	668	aioreq_pri $pri;
401	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	669	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
402	if ($_[0] == $stat[7]) {	670	if ($_[0] == $stat[7]) {
403	$grp->result (0);	671	$grp->result (0);
404	close $src_fh;	672	close $src_fh;
405		673
406	# those should not normally block. should. should.	674	my $ch = sub {
		675	aioreq_pri $pri;
		676	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		677	aioreq_pri $pri;
		678	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		679	aioreq_pri $pri;
		680	add $grp aio_close $dst_fh;
		681	}
		682	};
		683	};
		684
		685	aioreq_pri $pri;
		686	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		687	if ($_[0] < 0 && $! == ENOSYS) {
		688	aioreq_pri $pri;
407	utime $stat[8], $stat[9], $dst;	689	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
408	chmod $stat[2] & 07777, $dst_fh;	690	} else {
409	chown $stat[4], $stat[5], $dst_fh;	691	$ch->();
		692	}
410	close $dst_fh;	693	};
411	} else {	694	} else {
412	$grp->result (-1);	695	$grp->result (-1);
413	close $src_fh;	696	close $src_fh;
414	close $dst_fh;	697	close $dst_fh;
415		698
…		…
432		715
433	=item aio_move $srcpath, $dstpath, $callback->($status)	716	=item aio_move $srcpath, $dstpath, $callback->($status)
434		717
435	Try to move the I<file> (directories not supported as either source or	718	Try to move the I<file> (directories not supported as either source or
436	destination) from C<$srcpath> to C<$dstpath> and call the callback with	719	destination) from C<$srcpath> to C<$dstpath> and call the callback with
437	the C<0> (error) or C<-1> ok.	720	a status of C<0> (ok) or C<-1> (error, see C<$!>).
438		721
439	This is a composite request that tries to rename(2) the file first. If	722	This is a composite request that tries to rename(2) the file first; if
440	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	723	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
441	that is successful, unlinking the C<$srcpath>.	724	that is successful, unlinks the C<$srcpath>.
442		725
443	=cut	726	=cut
444		727
445	sub aio_move($$;$) {	728	sub aio_move($$;$) {
446	my ($src, $dst, $cb) = @_;	729	my ($src, $dst, $cb) = @_;
…		…
493		776
494	Implementation notes.	777	Implementation notes.
495		778
496	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	779	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
497		780
		781	If readdir returns file type information, then this is used directly to
		782	find directories.
		783
498	After reading the directory, the modification time, size etc. of the	784	Otherwise, after reading the directory, the modification time, size etc.
499	directory before and after the readdir is checked, and if they match (and	785	of the directory before and after the readdir is checked, and if they
500	isn't the current time), the link count will be used to decide how many	786	match (and isn't the current time), the link count will be used to decide
501	entries are directories (if >= 2). Otherwise, no knowledge of the number	787	how many entries are directories (if >= 2). Otherwise, no knowledge of the
502	of subdirectories will be assumed.	788	number of subdirectories will be assumed.
503		789
504	Then entries will be sorted into likely directories (everything without	790	Then entries will be sorted into likely directories a non-initial dot
505	a non-initial dot currently) and likely non-directories (everything	791	currently) and likely non-directories (see C<aio_readdirx>). Then every
506	else). Then every entry plus an appended C</.> will be C<stat>'ed,	792	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
507	likely directories first. If that succeeds, it assumes that the entry	793	in order of their inode numbers. If that succeeds, it assumes that the
508	is a directory or a symlink to directory (which will be checked	794	entry is a directory or a symlink to directory (which will be checked
509	seperately). This is often faster than stat'ing the entry itself because	795	seperately). This is often faster than stat'ing the entry itself because
510	filesystems might detect the type of the entry without reading the inode	796	filesystems might detect the type of the entry without reading the inode
511	data (e.g. ext2fs filetype feature).	797	data (e.g. ext2fs filetype feature), even on systems that cannot return
		798	the filetype information on readdir.
512		799
513	If the known number of directories (link count - 2) has been reached, the	800	If the known number of directories (link count - 2) has been reached, the
514	rest of the entries is assumed to be non-directories.	801	rest of the entries is assumed to be non-directories.
515		802
516	This only works with certainty on POSIX (= UNIX) filesystems, which	803	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
520	as those tend to return 0 or 1 as link counts, which disables the	807	as those tend to return 0 or 1 as link counts, which disables the
521	directory counting heuristic.	808	directory counting heuristic.
522		809
523	=cut	810	=cut
524		811
525	sub aio_scandir($$$) {	812	sub aio_scandir($$;$) {
526	my ($path, $maxreq, $cb) = @_;	813	my ($path, $maxreq, $cb) = @_;
527		814
528	my $pri = aioreq_pri;	815	my $pri = aioreq_pri;
529		816
530	my $grp = aio_group $cb;	817	my $grp = aio_group $cb;
…		…
538	my $now = time;	825	my $now = time;
539	my $hash1 = join ":", (stat _)[0,1,3,7,9];	826	my $hash1 = join ":", (stat _)[0,1,3,7,9];
540		827
541	# read the directory entries	828	# read the directory entries
542	aioreq_pri $pri;	829	aioreq_pri $pri;
543	add $grp aio_readdir $path, sub {	830	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
544	my $entries = shift	831	my $entries = shift
545	or return $grp->result ();	832	or return $grp->result ();
546		833
547	# stat the dir another time	834	# stat the dir another time
548	aioreq_pri $pri;	835	aioreq_pri $pri;
…		…
554	# take the slow route if anything looks fishy	841	# take the slow route if anything looks fishy
555	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	842	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
556	$ndirs = -1;	843	$ndirs = -1;
557	} else {	844	} else {
558	# if nlink == 2, we are finished	845	# if nlink == 2, we are finished
559	# on non-posix-fs's, we rely on nlink < 2	846	# for non-posix-fs's, we rely on nlink < 2
560	$ndirs = (stat _)[3] - 2	847	$ndirs = (stat _)[3] - 2
561	or return $grp->result ([], $entries);	848	or return $grp->result ([], $entries);
562	}	849	}
563		850
564	# sort into likely dirs and likely nondirs
565	# dirs == files without ".", short entries first
566	$entries = [map $_->[0],
567	sort { $b->[1] cmp $a->[1] }
568	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
569	@$entries];
570
571	my (@dirs, @nondirs);	851	my (@dirs, @nondirs);
572		852
573	my $statgrp = add $grp aio_group sub {	853	my $statgrp = add $grp aio_group sub {
574	$grp->result (\@dirs, \@nondirs);	854	$grp->result (\@dirs, \@nondirs);
575	};	855	};
576		856
577	limit $statgrp $maxreq;	857	limit $statgrp $maxreq;
578	feed $statgrp sub {	858	feed $statgrp sub {
579	return unless @$entries;	859	return unless @$entries;
580	my $entry = pop @$entries;	860	my $entry = shift @$entries;
581		861
582	aioreq_pri $pri;	862	aioreq_pri $pri;
583	add $statgrp aio_stat "$path/$entry/.", sub {	863	add $statgrp aio_stat "$path/$entry/.", sub {
584	if ($_[0] < 0) {	864	if ($_[0] < 0) {
585	push @nondirs, $entry;	865	push @nondirs, $entry;
…		…
606	};	886	};
607		887
608	$grp	888	$grp
609	}	889	}
610		890
		891	=item aio_rmtree $path, $callback->($status)
		892
		893	Delete a directory tree starting (and including) C<$path>, return the
		894	status of the final C<rmdir> only. This is a composite request that
		895	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		896	everything else.
		897
		898	=cut
		899
		900	sub aio_rmtree;
		901	sub aio_rmtree($;$) {
		902	my ($path, $cb) = @_;
		903
		904	my $pri = aioreq_pri;
		905	my $grp = aio_group $cb;
		906
		907	aioreq_pri $pri;
		908	add $grp aio_scandir $path, 0, sub {
		909	my ($dirs, $nondirs) = @_;
		910
		911	my $dirgrp = aio_group sub {
		912	add $grp aio_rmdir $path, sub {
		913	$grp->result ($_[0]);
		914	};
		915	};
		916
		917	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		918	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		919
		920	add $grp $dirgrp;
		921	};
		922
		923	$grp
		924	}
		925
		926	=item aio_sync $callback->($status)
		927
		928	Asynchronously call sync and call the callback when finished.
		929
611	=item aio_fsync $fh, $callback->($status)	930	=item aio_fsync $fh, $callback->($status)
612		931
613	Asynchronously call fsync on the given filehandle and call the callback	932	Asynchronously call fsync on the given filehandle and call the callback
614	with the fsync result code.	933	with the fsync result code.
615		934
…		…
618	Asynchronously call fdatasync on the given filehandle and call the	937	Asynchronously call fdatasync on the given filehandle and call the
619	callback with the fdatasync result code.	938	callback with the fdatasync result code.
620		939
621	If this call isn't available because your OS lacks it or it couldn't be	940	If this call isn't available because your OS lacks it or it couldn't be
622	detected, it will be emulated by calling C<fsync> instead.	941	detected, it will be emulated by calling C<fsync> instead.
		942
		943	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		944
		945	Sync the data portion of the file specified by C<$offset> and C<$length>
		946	to disk (but NOT the metadata), by calling the Linux-specific
		947	sync_file_range call. If sync_file_range is not available or it returns
		948	ENOSYS, then fdatasync or fsync is being substituted.
		949
		950	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		951	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		952	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		953	manpage for details.
		954
		955	=item aio_pathsync $path, $callback->($status)
		956
		957	This request tries to open, fsync and close the given path. This is a
		958	composite request intended to sync directories after directory operations
		959	(E.g. rename). This might not work on all operating systems or have any
		960	specific effect, but usually it makes sure that directory changes get
		961	written to disc. It works for anything that can be opened for read-only,
		962	not just directories.
		963
		964	Future versions of this function might fall back to other methods when
		965	C<fsync> on the directory fails (such as calling C<sync>).
		966
		967	Passes C<0> when everything went ok, and C<-1> on error.
		968
		969	=cut
		970
		971	sub aio_pathsync($;$) {
		972	my ($path, $cb) = @_;
		973
		974	my $pri = aioreq_pri;
		975	my $grp = aio_group $cb;
		976
		977	aioreq_pri $pri;
		978	add $grp aio_open $path, O_RDONLY, 0, sub {
		979	my ($fh) = @_;
		980	if ($fh) {
		981	aioreq_pri $pri;
		982	add $grp aio_fsync $fh, sub {
		983	$grp->result ($_[0]);
		984
		985	aioreq_pri $pri;
		986	add $grp aio_close $fh;
		987	};
		988	} else {
		989	$grp->result (-1);
		990	}
		991	};
		992
		993	$grp
		994	}
		995
		996	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		997
		998	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		999	scalars (see the L<Sys::Mmap> or L<Mmap> modules for details on this, note
		1000	that the scalar must only be modified in-place while an aio operation is
		1001	pending on it).
		1002
		1003	It calls the C<msync> function of your OS, if available, with the memory
		1004	area starting at C<$offset> in the string and ending C<$length> bytes
		1005	later. If C<$length> is negative, counts from the end, and if C<$length>
		1006	is C<undef>, then it goes till the end of the string. The flags can be
		1007	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1008	C<IO::AIO::MS_SYNC>.
		1009
		1010	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1011
		1012	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1013	scalars.
		1014
		1015	It touches (reads or writes) all memory pages in the specified
		1016	range inside the scalar. All caveats and parameters are the same
		1017	as for C<aio_msync>, above, except for flags, which must be either
		1018	C<0> (which reads all pages and ensures they are instantiated) or
		1019	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1020	writing an octet from it, which dirties the page).
623		1021
624	=item aio_group $callback->(...)	1022	=item aio_group $callback->(...)
625		1023
626	This is a very special aio request: Instead of doing something, it is a	1024	This is a very special aio request: Instead of doing something, it is a
627	container for other aio requests, which is useful if you want to bundle	1025	container for other aio requests, which is useful if you want to bundle
…		…
677	=item cancel $req	1075	=item cancel $req
678		1076
679	Cancels the request, if possible. Has the effect of skipping execution	1077	Cancels the request, if possible. Has the effect of skipping execution
680	when entering the B<execute> state and skipping calling the callback when	1078	when entering the B<execute> state and skipping calling the callback when
681	entering the the B<result> state, but will leave the request otherwise	1079	entering the the B<result> state, but will leave the request otherwise
682	untouched. That means that requests that currently execute will not be	1080	untouched (with the exception of readdir). That means that requests that
683	stopped and resources held by the request will not be freed prematurely.	1081	currently execute will not be stopped and resources held by the request
		1082	will not be freed prematurely.
684		1083
685	=item cb $req $callback->(...)	1084	=item cb $req $callback->(...)
686		1085
687	Replace (or simply set) the callback registered to the request.	1086	Replace (or simply set) the callback registered to the request.
688		1087
…		…
739	Their lifetime, simplified, looks like this: when they are empty, they	1138	Their lifetime, simplified, looks like this: when they are empty, they
740	will finish very quickly. If they contain only requests that are in the	1139	will finish very quickly. If they contain only requests that are in the
741	C<done> state, they will also finish. Otherwise they will continue to	1140	C<done> state, they will also finish. Otherwise they will continue to
742	exist.	1141	exist.
743		1142
744	That means after creating a group you have some time to add requests. And	1143	That means after creating a group you have some time to add requests
745	in the callbacks of those requests, you can add further requests to the	1144	(precisely before the callback has been invoked, which is only done within
746	group. And only when all those requests have finished will the the group	1145	the C<poll_cb>). And in the callbacks of those requests, you can add
747	itself finish.	1146	further requests to the group. And only when all those requests have
		1147	finished will the the group itself finish.
748		1148
749	=over 4	1149	=over 4
750		1150
751	=item add $grp ...	1151	=item add $grp ...
752		1152
…		…
761	=item $grp->cancel_subs	1161	=item $grp->cancel_subs
762		1162
763	Cancel all subrequests and clears any feeder, but not the group request	1163	Cancel all subrequests and clears any feeder, but not the group request
764	itself. Useful when you queued a lot of events but got a result early.	1164	itself. Useful when you queued a lot of events but got a result early.
765		1165
		1166	The group request will finish normally (you cannot add requests to the
		1167	group).
		1168
766	=item $grp->result (...)	1169	=item $grp->result (...)
767		1170
768	Set the result value(s) that will be passed to the group callback when all	1171	Set the result value(s) that will be passed to the group callback when all
769	subrequests have finished and set thre groups errno to the current value	1172	subrequests have finished and set the groups errno to the current value
770	of errno (just like calling C<errno> without an error number). By default,	1173	of errno (just like calling C<errno> without an error number). By default,
771	no argument will be passed and errno is zero.	1174	no argument will be passed and errno is zero.
772		1175
773	=item $grp->errno ([$errno])	1176	=item $grp->errno ([$errno])
774		1177
…		…
785	=item feed $grp $callback->($grp)	1188	=item feed $grp $callback->($grp)
786		1189
787	Sets a feeder/generator on this group: every group can have an attached	1190	Sets a feeder/generator on this group: every group can have an attached
788	generator that generates requests if idle. The idea behind this is that,	1191	generator that generates requests if idle. The idea behind this is that,
789	although you could just queue as many requests as you want in a group,	1192	although you could just queue as many requests as you want in a group,
790	this might starve other requests for a potentially long time. For	1193	this might starve other requests for a potentially long time. For example,
791	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1194	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
792	requests, delaying any later requests for a long time.	1195	delaying any later requests for a long time.
793		1196
794	To avoid this, and allow incremental generation of requests, you can	1197	To avoid this, and allow incremental generation of requests, you can
795	instead a group and set a feeder on it that generates those requests. The	1198	instead a group and set a feeder on it that generates those requests. The
796	feed callback will be called whenever there are few enough (see C<limit>,	1199	feed callback will be called whenever there are few enough (see C<limit>,
797	below) requests active in the group itself and is expected to queue more	1200	below) requests active in the group itself and is expected to queue more
…		…
801	not impose any limits).	1204	not impose any limits).
802		1205
803	If the feed does not queue more requests when called, it will be	1206	If the feed does not queue more requests when called, it will be
804	automatically removed from the group.	1207	automatically removed from the group.
805		1208
806	If the feed limit is C<0>, it will be set to C<2> automatically.	1209	If the feed limit is C<0> when this method is called, it will be set to
		1210	C<2> automatically.
807		1211
808	Example:	1212	Example:
809		1213
810	# stat all files in @files, but only ever use four aio requests concurrently:	1214	# stat all files in @files, but only ever use four aio requests concurrently:
811		1215
…		…
823	Sets the feeder limit for the group: The feeder will be called whenever	1227	Sets the feeder limit for the group: The feeder will be called whenever
824	the group contains less than this many requests.	1228	the group contains less than this many requests.
825		1229
826	Setting the limit to C<0> will pause the feeding process.	1230	Setting the limit to C<0> will pause the feeding process.
827		1231
		1232	The default value for the limit is C<0>, but note that setting a feeder
		1233	automatically bumps it up to C<2>.
		1234
828	=back	1235	=back
829		1236
830	=head2 SUPPORT FUNCTIONS	1237	=head2 SUPPORT FUNCTIONS
831		1238
		1239	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1240
832	=over 4	1241	=over 4
833		1242
834	=item $fileno = IO::AIO::poll_fileno	1243	=item $fileno = IO::AIO::poll_fileno
835		1244
836	Return the I<request result pipe file descriptor>. This filehandle must be	1245	Return the I<request result pipe file descriptor>. This filehandle must be
837	polled for reading by some mechanism outside this module (e.g. Event or	1246	polled for reading by some mechanism outside this module (e.g. EV, Glib,
838	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1247	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
839	to call C<poll_cb> to check the results.	1248	you have to call C<poll_cb> to check the results.
840		1249
841	See C<poll_cb> for an example.	1250	See C<poll_cb> for an example.
842		1251
843	=item IO::AIO::poll_cb	1252	=item IO::AIO::poll_cb
844		1253
845	Process all outstanding events on the result pipe. You have to call this	1254	Process some outstanding events on the result pipe. You have to call this
846	regularly. Returns the number of events processed. Returns immediately	1255	regularly. Returns C<0> if all events could be processed, or C<-1> if it
847	when no events are outstanding.	1256	returned earlier for whatever reason. Returns immediately when no events
		1257	are outstanding. The amount of events processed depends on the settings of
		1258	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
848		1259
849	If not all requests were processed for whatever reason, the filehandle	1260	If not all requests were processed for whatever reason, the filehandle
850	will still be ready when C<poll_cb> returns.	1261	will still be ready when C<poll_cb> returns, so normally you don't have to
		1262	do anything special to have it called later.
851		1263
852	Example: Install an Event watcher that automatically calls	1264	Example: Install an Event watcher that automatically calls
853	IO::AIO::poll_cb with high priority:	1265	IO::AIO::poll_cb with high priority (more examples can be found in the
		1266	SYNOPSIS section, at the top of this document):
854		1267
855	Event->io (fd => IO::AIO::poll_fileno,	1268	Event->io (fd => IO::AIO::poll_fileno,
856	poll => 'r', async => 1,	1269	poll => 'r', async => 1,
857	cb => \&IO::AIO::poll_cb);	1270	cb => \&IO::AIO::poll_cb);
858		1271
859	=item IO::AIO::poll_some $max_requests	1272	=item IO::AIO::max_poll_reqs $nreqs
860		1273
861	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests	1274	=item IO::AIO::max_poll_time $seconds
862	at a time.
863		1275
864	Useful if you want to ensure some level of interactiveness when perl is	1276	These set the maximum number of requests (default C<0>, meaning infinity)
865	not fast enough to process all requests in time.	1277	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1278	the maximum amount of time (default C<0>, meaning infinity) spent in
		1279	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1280	of time C<poll_cb> is allowed to use).
		1281
		1282	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1283	syscall per request processed, which is not normally a problem unless your
		1284	callbacks are really really fast or your OS is really really slow (I am
		1285	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1286
		1287	Setting these is useful if you want to ensure some level of
		1288	interactiveness when perl is not fast enough to process all requests in
		1289	time.
		1290
		1291	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
866		1292
867	Example: Install an Event watcher that automatically calls	1293	Example: Install an Event watcher that automatically calls
868	IO::AIO::poll_some with low priority, to ensure that other parts of the	1294	IO::AIO::poll_cb with low priority, to ensure that other parts of the
869	program get the CPU sometimes even under high AIO load.	1295	program get the CPU sometimes even under high AIO load.
870		1296
		1297	# try not to spend much more than 0.1s in poll_cb
		1298	IO::AIO::max_poll_time 0.1;
		1299
		1300	# use a low priority so other tasks have priority
871	Event->io (fd => IO::AIO::poll_fileno,	1301	Event->io (fd => IO::AIO::poll_fileno,
872	poll => 'r', nice => 1,	1302	poll => 'r', nice => 1,
873	cb => sub { IO::AIO::poll_some 256 });	1303	cb => &IO::AIO::poll_cb);
874		1304
875	=item IO::AIO::poll_wait	1305	=item IO::AIO::poll_wait
876		1306
		1307	If there are any outstanding requests and none of them in the result
877	Wait till the result filehandle becomes ready for reading (simply does a	1308	phase, wait till the result filehandle becomes ready for reading (simply
878	C<select> on the filehandle. This is useful if you want to synchronously wait	1309	does a C<select> on the filehandle. This is useful if you want to
879	for some requests to finish).	1310	synchronously wait for some requests to finish).
880		1311
881	See C<nreqs> for an example.	1312	See C<nreqs> for an example.
882		1313
		1314	=item IO::AIO::poll
		1315
		1316	Waits until some requests have been handled.
		1317
		1318	Returns the number of requests processed, but is otherwise strictly
		1319	equivalent to:
		1320
		1321	IO::AIO::poll_wait, IO::AIO::poll_cb
		1322
883	=item IO::AIO::nreqs	1323	=item IO::AIO::flush
884		1324
885	Returns the number of requests currently in the ready, execute or pending	1325	Wait till all outstanding AIO requests have been handled.
886	states (i.e. for which their callback has not been invoked yet).
887		1326
888	Example: wait till there are no outstanding requests anymore:	1327	Strictly equivalent to:
889		1328
890	IO::AIO::poll_wait, IO::AIO::poll_cb	1329	IO::AIO::poll_wait, IO::AIO::poll_cb
891	while IO::AIO::nreqs;	1330	while IO::AIO::nreqs;
892		1331
893	=item IO::AIO::nready	1332	=back
894		1333
895	Returns the number of requests currently in the ready state (not yet	1334	=head3 CONTROLLING THE NUMBER OF THREADS
896	executed).
897		1335
898	=item IO::AIO::npending	1336	=over
899
900	Returns the number of requests currently in the pending state (executed,
901	but not yet processed by poll_cb).
902
903	=item IO::AIO::flush
904
905	Wait till all outstanding AIO requests have been handled.
906
907	Strictly equivalent to:
908
909	IO::AIO::poll_wait, IO::AIO::poll_cb
910	while IO::AIO::nreqs;
911
912	=item IO::AIO::poll
913
914	Waits until some requests have been handled.
915
916	Strictly equivalent to:
917
918	IO::AIO::poll_wait, IO::AIO::poll_cb
919	if IO::AIO::nreqs;
920		1337
921	=item IO::AIO::min_parallel $nthreads	1338	=item IO::AIO::min_parallel $nthreads
922		1339
923	Set the minimum number of AIO threads to C<$nthreads>. The current	1340	Set the minimum number of AIO threads to C<$nthreads>. The current
924	default is C<8>, which means eight asynchronous operations can execute	1341	default is C<8>, which means eight asynchronous operations can execute
925	concurrently at any one time (the number of outstanding requests,	1342	concurrently at any one time (the number of outstanding requests,
926	however, is unlimited).	1343	however, is unlimited).
927		1344
928	IO::AIO starts threads only on demand, when an AIO request is queued and	1345	IO::AIO starts threads only on demand, when an AIO request is queued and
929	no free thread exists.	1346	no free thread exists. Please note that queueing up a hundred requests can
		1347	create demand for a hundred threads, even if it turns out that everything
		1348	is in the cache and could have been processed faster by a single thread.
930		1349
931	It is recommended to keep the number of threads relatively low, as some	1350	It is recommended to keep the number of threads relatively low, as some
932	Linux kernel versions will scale negatively with the number of threads	1351	Linux kernel versions will scale negatively with the number of threads
933	(higher parallelity => MUCH higher latency). With current Linux 2.6	1352	(higher parallelity => MUCH higher latency). With current Linux 2.6
934	versions, 4-32 threads should be fine.	1353	versions, 4-32 threads should be fine.
…		…
948	This module automatically runs C<max_parallel 0> at program end, to ensure	1367	This module automatically runs C<max_parallel 0> at program end, to ensure
949	that all threads are killed and that there are no outstanding requests.	1368	that all threads are killed and that there are no outstanding requests.
950		1369
951	Under normal circumstances you don't need to call this function.	1370	Under normal circumstances you don't need to call this function.
952		1371
		1372	=item IO::AIO::max_idle $nthreads
		1373
		1374	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1375	threads that did not get a request to process within 10 seconds). That
		1376	means if a thread becomes idle while C<$nthreads> other threads are also
		1377	idle, it will free its resources and exit.
		1378
		1379	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1380	to allow for extremely high load situations, but want to free resources
		1381	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1382
		1383	The default is probably ok in most situations, especially if thread
		1384	creation is fast. If thread creation is very slow on your system you might
		1385	want to use larger values.
		1386
953	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1387	=item IO::AIO::max_outstanding $maxreqs
954		1388
955	This is a very bad function to use in interactive programs because it	1389	This is a very bad function to use in interactive programs because it
956	blocks, and a bad way to reduce concurrency because it is inexact: Better	1390	blocks, and a bad way to reduce concurrency because it is inexact: Better
957	use an C<aio_group> together with a feed callback.	1391	use an C<aio_group> together with a feed callback.
958		1392
959	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1393	Sets the maximum number of outstanding requests to C<$nreqs>. If you
960	to queue up more than this number of requests, the next call to the	1394	do queue up more than this number of requests, the next call to the
961	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)	1395	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
962	function will block until the limit is no longer exceeded.	1396	function will block until the limit is no longer exceeded.
963		1397
964	The default value is very large, so there is no practical limit on the	1398	The default value is very large, so there is no practical limit on the
965	number of outstanding requests.	1399	number of outstanding requests.
966		1400
967	You can still queue as many requests as you want. Therefore,	1401	You can still queue as many requests as you want. Therefore,
968	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1402	C<max_outstanding> is mainly useful in simple scripts (with low values) or
969	as a stop gap to shield against fatal memory overflow (with large values).	1403	as a stop gap to shield against fatal memory overflow (with large values).
970		1404
971	=back	1405	=back
972		1406
		1407	=head3 STATISTICAL INFORMATION
		1408
		1409	=over
		1410
		1411	=item IO::AIO::nreqs
		1412
		1413	Returns the number of requests currently in the ready, execute or pending
		1414	states (i.e. for which their callback has not been invoked yet).
		1415
		1416	Example: wait till there are no outstanding requests anymore:
		1417
		1418	IO::AIO::poll_wait, IO::AIO::poll_cb
		1419	while IO::AIO::nreqs;
		1420
		1421	=item IO::AIO::nready
		1422
		1423	Returns the number of requests currently in the ready state (not yet
		1424	executed).
		1425
		1426	=item IO::AIO::npending
		1427
		1428	Returns the number of requests currently in the pending state (executed,
		1429	but not yet processed by poll_cb).
		1430
		1431	=back
		1432
		1433	=head3 MISCELLANEOUS FUNCTIONS
		1434
		1435	IO::AIO implements some functions that might be useful, but are not
		1436	asynchronous.
		1437
		1438	=over 4
		1439
		1440	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1441
		1442	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1443	but is blocking (this makes most sense if you know the input data is
		1444	likely cached already and the output filehandle is set to non-blocking
		1445	operations).
		1446
		1447	Returns the number of bytes copied, or C<-1> on error.
		1448
		1449	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1450
		1451	Simply calls the C<posix_fadvise> function (see it's
		1452	manpage for details). The following advice constants are
		1453	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1454	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1455	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1456
		1457	On systems that do not implement C<posix_fadvise>, this function returns
		1458	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1459
		1460	=back
		1461
973	=cut	1462	=cut
974		1463
975	# support function to convert a fd into a perl filehandle
976	sub _fd2fh {
977	return undef if $_[0] < 0;
978
979	# try to generate nice filehandles
980	my $sym = "IO::AIO::fd#$_[0]";
981	local *$sym;
982
983	open *$sym, "+<&=$_[0]" # usually works under any unix
984	or open *$sym, "<&=$_[0]" # cygwin needs this
985	or open *$sym, ">&=$_[0]" # or this
986	or return undef;
987
988	*$sym
989	}
990
991	min_parallel 8;	1464	min_parallel 8;
992		1465
993	END {	1466	END { flush }
994	flush;
995	};
996		1467
997	1;	1468	1;
998		1469
999	=head2 FORK BEHAVIOUR	1470	=head2 FORK BEHAVIOUR
1000		1471
…		…
1020	bytes of memory. In addition, stat requests need a stat buffer (possibly	1491	bytes of memory. In addition, stat requests need a stat buffer (possibly
1021	a few hundred bytes), readdir requires a result buffer and so on. Perl	1492	a few hundred bytes), readdir requires a result buffer and so on. Perl
1022	scalars and other data passed into aio requests will also be locked and	1493	scalars and other data passed into aio requests will also be locked and
1023	will consume memory till the request has entered the done state.	1494	will consume memory till the request has entered the done state.
1024		1495
1025	This is now awfully much, so queuing lots of requests is not usually a	1496	This is not awfully much, so queuing lots of requests is not usually a
1026	problem.	1497	problem.
1027		1498
1028	Per-thread usage:	1499	Per-thread usage:
1029		1500
1030	In the execution phase, some aio requests require more memory for	1501	In the execution phase, some aio requests require more memory for
…		…
1035		1506
1036	Known bugs will be fixed in the next release.	1507	Known bugs will be fixed in the next release.
1037		1508
1038	=head1 SEE ALSO	1509	=head1 SEE ALSO
1039		1510
1040	L<Coro::AIO>.	1511	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1512	more natural syntax.
1041		1513
1042	=head1 AUTHOR	1514	=head1 AUTHOR
1043		1515
1044	Marc Lehmann <schmorp@schmorp.de>	1516	Marc Lehmann <schmorp@schmorp.de>
1045	http://home.schmorp.de/	1517	http://home.schmorp.de/

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Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC vs.
Revision 1.171 by root, Sat Jan 2 14:24:32 2010 UTC