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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.77 by root, Wed Oct 25 17:57:30 2006 UTC vs.
Revision 1.163 by root, Wed Aug 5 11:53:16 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>).
		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 = '3.3';
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_group aio_nop);	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
137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	206	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	207	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139	min_parallel max_parallel nreqs);	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
140		214
141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142		216
143	require XSLoader;	217	require XSLoader;
144	XSLoader::load ("IO::AIO", $VERSION);	218	XSLoader::load ("IO::AIO", $VERSION);
145	}	219	}
146		220
147	=head1 FUNCTIONS	221	=head1 FUNCTIONS
148		222
149	=head2 AIO FUNCTIONS	223	=head2 AIO REQUEST FUNCTIONS
150		224
151	All the C<aio_*> calls are more or less thin wrappers around the syscall	225	All the C<aio_*> calls are more or less thin wrappers around the syscall
152	with the same name (sans C<aio_>). The arguments are similar or identical,	226	with the same name (sans C<aio_>). The arguments are similar or identical,
153	and they all accept an additional (and optional) C<$callback> argument	227	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	228	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	229	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	230	perl, which usually delivers "false") as its sole argument after the given
157	syscall has been executed asynchronously.	231	syscall has been executed asynchronously.
158		232
159	All functions expecting a filehandle keep a copy of the filehandle	233	All functions expecting a filehandle keep a copy of the filehandle
160	internally until the request has finished.	234	internally until the request has finished.
161		235
162	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
163	manipulation of those requests while they are in-flight.	237	further manipulation of those requests while they are in-flight.
164		238
165	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
166	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
167	request is being executed, the current working directory could have	241	request is being executed, the current working directory could have
168	changed. Alternatively, you can make sure that you never change the	242	changed. Alternatively, you can make sure that you never change the
169	current working directory.	243	current working directory anywhere in the program and then use relative
		244	paths.
170		245
171	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
172	always pass in filenames you got from outside (command line, readdir	247	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	248	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	249	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)	250	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176	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.
177		255
178	=over 4	256	=over 4
179		257
180	=item aioreq_pri $pri	258	=item $prev_pri = aioreq_pri [$pri]
181		259
182	Sets the priority for the next aio request. The default priority	260	Returns the priority value that would be used for the next request and, if
		261	C<$pri> is given, sets the priority for the next aio request.
		262
183	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	263	The default priority is C<0>, the minimum and maximum priorities are C<-4>
184	respectively. Requests with higher priority will be serviced first.	264	and C<4>, respectively. Requests with higher priority will be serviced
		265	first.
185		266
186	The priority will be reset to C<0> after each call to one of the C<aio_>	267	The priority will be reset to C<0> after each call to one of the C<aio_*>
187	functions.	268	functions.
188		269
189	Example: open a file with low priority, then read something from it with	270	Example: open a file with low priority, then read something from it with
190	higher priority so the read request is serviced before other low priority	271	higher priority so the read request is serviced before other low priority
191	open requests (potentially spamming the cache):	272	open requests (potentially spamming the cache):
…		…
198	aio_read $_[0], ..., sub {	279	aio_read $_[0], ..., sub {
199	...	280	...
200	};	281	};
201	};	282	};
202		283
		284
203	=item aioreq_nice $pri_adjust	285	=item aioreq_nice $pri_adjust
204		286
205	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
206	priority, so effects are cumulative.	288	priority, so the effect is cumulative.
		289
207		290
208	=item aio_open $pathname, $flags, $mode, $callback->($fh)	291	=item aio_open $pathname, $flags, $mode, $callback->($fh)
209		292
210	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
211	created filehandle for the file.	294	created filehandle for the file.
…		…
217	list. They are the same as used by C<sysopen>.	300	list. They are the same as used by C<sysopen>.
218		301
219	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
220	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>,
221	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,
222	and C<0666> or C<0777> if you do).	305	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		306	by the umask in effect then the request is being executed, so better never
		307	change the umask.
223		308
224	Example:	309	Example:
225		310
226	aio_open "/etc/passwd", O_RDONLY, 0, sub {	311	aio_open "/etc/passwd", O_RDONLY, 0, sub {
227	if ($_[0]) {	312	if ($_[0]) {
…		…
230	} else {	315	} else {
231	die "open failed: $!\n";	316	die "open failed: $!\n";
232	}	317	}
233	};	318	};
234		319
		320
235	=item aio_close $fh, $callback->($status)	321	=item aio_close $fh, $callback->($status)
236		322
237	Asynchronously close a file and call the callback with the result	323	Asynchronously close a file and call the callback with the result
238	code. I<WARNING:> although accepted, you should not pass in a perl	324	code.
239	filehandle here, as perl will likely close the file descriptor another
240	time when the filehandle is destroyed. Normally, you can safely call perls
241	C<close> or just let filehandles go out of scope.
242		325
243	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
244	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
245		337
246	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	338	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
247		339
248	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	340	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
249		341
250	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
251	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<$dataoffset>
252	callback without the actual number of bytes read (or -1 on error, just	344	and calls the callback without the actual number of bytes read (or -1 on
253	like the syscall).	345	error, just like the syscall).
		346
		347	C<aio_read> will, like C<sysread>, shrink or grow the C<$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<$data>.
254		359
255	The C<$data> scalar I<MUST NOT> be modified in any way while the request	360	The C<$data> scalar I<MUST NOT> be modified in any way while the request
256	is outstanding. Modifying it can result in segfaults or WW3 (if the	361	is outstanding. Modifying it can result in segfaults or World War III (if
257	necessary/optional hardware is installed).	362	the necessary/optional hardware is installed).
258		363
259	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	364	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
260	offset C<0> within the scalar:	365	offset C<0> within the scalar:
261		366
262	aio_read $fh, 7, 15, $buffer, 0, sub {	367	aio_read $fh, 7, 15, $buffer, 0, sub {
263	$_[0] > 0 or die "read error: $!";	368	$_[0] > 0 or die "read error: $!";
264	print "read $_[0] bytes: <$buffer>\n";	369	print "read $_[0] bytes: <$buffer>\n";
265	};	370	};
266		371
267	=item aio_move $srcpath, $dstpath, $callback->($status)
268
269	Try to move the I<file> (directories not supported as either source or
270	destination) from C<$srcpath> to C<$dstpath> and call the callback with
271	the C<0> (error) or C<-1> ok.
272
273	This is a composite request that tries to rename(2) the file first. If
274	rename files with C<EXDEV>, it creates the destination file with mode 0200
275	and copies the contents of the source file into it using C<aio_sendfile>,
276	followed by restoring atime, mtime, access mode and uid/gid, in that
277	order, and unlinking the C<$srcpath>.
278
279	If an error occurs, the partial destination file will be unlinked, if
280	possible, except when setting atime, mtime, access mode and uid/gid, where
281	errors are being ignored.
282
283	=cut
284
285	sub aio_move($$$) {
286	my ($src, $dst, $cb) = @_;
287
288	my $grp = aio_group $cb;
289
290	add $grp aio_rename $src, $dst, sub {
291	if ($_[0] && $! == EXDEV) {
292	add $grp aio_open $src, O_RDONLY, 0, sub {
293	if (my $src_fh = $_[0]) {
294	my @stat = stat $src_fh;
295
296	add $grp aio_open $dst, O_WRONLY, 0200, sub {
297	if (my $dst_fh = $_[0]) {
298	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
299	close $src_fh;
300
301	if ($_[0] == $stat[7]) {
302	utime $stat[8], $stat[9], $dst;
303	chmod $stat[2] & 07777, $dst_fh;
304	chown $stat[4], $stat[5], $dst_fh;
305	close $dst_fh;
306
307	add $grp aio_unlink $src, sub {
308	$grp->result ($_[0]);
309	};
310	} else {
311	my $errno = $!;
312	add $grp aio_unlink $dst, sub {
313	$! = $errno;
314	$grp->result (-1);
315	};
316	}
317	};
318	} else {
319	$grp->result (-1);
320	}
321	},
322
323	} else {
324	$grp->result (-1);
325	}
326	};
327	} else {
328	$grp->result ($_[0]);
329	}
330	};
331
332	$grp
333	}
334		372
335	=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)
336		374
337	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
338	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
…		…
352	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
353	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
354	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
355	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
356	read.	394	read.
		395
357		396
358	=item aio_readahead $fh,$offset,$length, $callback->($retval)	397	=item aio_readahead $fh,$offset,$length, $callback->($retval)
359		398
360	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
361	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>
…		…
367	file. The current file offset of the file is left unchanged.	406	file. The current file offset of the file is left unchanged.
368		407
369	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
370	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.
371		410
		411
372	=item aio_stat $fh_or_path, $callback->($status)	412	=item aio_stat $fh_or_path, $callback->($status)
373		413
374	=item aio_lstat $fh, $callback->($status)	414	=item aio_lstat $fh, $callback->($status)
375		415
376	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
…		…
389	aio_stat "/etc/passwd", sub {	429	aio_stat "/etc/passwd", sub {
390	$_[0] and die "stat failed: $!";	430	$_[0] and die "stat failed: $!";
391	print "size is ", -s _, "\n";	431	print "size is ", -s _, "\n";
392	};	432	};
393		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
394	=item aio_unlink $pathname, $callback->($status)	476	=item aio_unlink $pathname, $callback->($status)
395		477
396	Asynchronously unlink (delete) a file and call the callback with the	478	Asynchronously unlink (delete) a file and call the callback with the
397	result code.	479	result code.
398		480
		481
		482	=item aio_mknod $path, $mode, $dev, $callback->($status)
		483
		484	[EXPERIMENTAL]
		485
		486	Asynchronously create a device node (or fifo). See mknod(2).
		487
		488	The only (POSIX-) portable way of calling this function is:
		489
		490	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		491
		492
399	=item aio_link $srcpath, $dstpath, $callback->($status)	493	=item aio_link $srcpath, $dstpath, $callback->($status)
400		494
401	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
402	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.
403		497
		498
404	=item aio_symlink $srcpath, $dstpath, $callback->($status)	499	=item aio_symlink $srcpath, $dstpath, $callback->($status)
405		500
406	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
407	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.
408		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
409	=item aio_rename $srcpath, $dstpath, $callback->($status)	512	=item aio_rename $srcpath, $dstpath, $callback->($status)
410		513
411	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
412	rename(2) and call the callback with the result code.	515	rename(2) and call the callback with the result code.
413		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
414	=item aio_rmdir $pathname, $callback->($status)	525	=item aio_rmdir $pathname, $callback->($status)
415		526
416	Asynchronously rmdir (delete) a directory and call the callback with the	527	Asynchronously rmdir (delete) a directory and call the callback with the
417	result code.	528	result code.
		529
418		530
419	=item aio_readdir $pathname, $callback->($entries)	531	=item aio_readdir $pathname, $callback->($entries)
420		532
421	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
422	directory (i.e. opendir + readdir + closedir). The entries will not be	534	directory (i.e. opendir + readdir + closedir). The entries will not be
423	sorted, and will B<NOT> include the C<.> and C<..> entries.	535	sorted, and will B<NOT> include the C<.> and C<..> entries.
424		536
425	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
426	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), $$data, 0, sub {
		628	$grp->result ($_[0]);
		629	};
		630	};
		631
		632	$grp
		633	}
		634
		635	=item aio_copy $srcpath, $dstpath, $callback->($status)
		636
		637	Try to copy the I<file> (directories not supported as either source or
		638	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		639	the C<0> (error) or C<-1> ok.
		640
		641	This is a composite request that creates the destination file with
		642	mode 0200 and copies the contents of the source file into it using
		643	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		644	uid/gid, in that order.
		645
		646	If an error occurs, the partial destination file will be unlinked, if
		647	possible, except when setting atime, mtime, access mode and uid/gid, where
		648	errors are being ignored.
		649
		650	=cut
		651
		652	sub aio_copy($$;$) {
		653	my ($src, $dst, $cb) = @_;
		654
		655	my $pri = aioreq_pri;
		656	my $grp = aio_group $cb;
		657
		658	aioreq_pri $pri;
		659	add $grp aio_open $src, O_RDONLY, 0, sub {
		660	if (my $src_fh = $_[0]) {
		661	my @stat = stat $src_fh; # hmm, might bock over nfs?
		662
		663	aioreq_pri $pri;
		664	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		665	if (my $dst_fh = $_[0]) {
		666	aioreq_pri $pri;
		667	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		668	if ($_[0] == $stat[7]) {
		669	$grp->result (0);
		670	close $src_fh;
		671
		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;
		687	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		688	} else {
		689	$ch->();
		690	}
		691	};
		692	} else {
		693	$grp->result (-1);
		694	close $src_fh;
		695	close $dst_fh;
		696
		697	aioreq $pri;
		698	add $grp aio_unlink $dst;
		699	}
		700	};
		701	} else {
		702	$grp->result (-1);
		703	}
		704	},
		705
		706	} else {
		707	$grp->result (-1);
		708	}
		709	};
		710
		711	$grp
		712	}
		713
		714	=item aio_move $srcpath, $dstpath, $callback->($status)
		715
		716	Try to move the I<file> (directories not supported as either source or
		717	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		718	the C<0> (error) or C<-1> ok.
		719
		720	This is a composite request that tries to rename(2) the file first; if
		721	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		722	that is successful, unlinks the C<$srcpath>.
		723
		724	=cut
		725
		726	sub aio_move($$;$) {
		727	my ($src, $dst, $cb) = @_;
		728
		729	my $pri = aioreq_pri;
		730	my $grp = aio_group $cb;
		731
		732	aioreq_pri $pri;
		733	add $grp aio_rename $src, $dst, sub {
		734	if ($_[0] && $! == EXDEV) {
		735	aioreq_pri $pri;
		736	add $grp aio_copy $src, $dst, sub {
		737	$grp->result ($_[0]);
		738
		739	if (!$_[0]) {
		740	aioreq_pri $pri;
		741	add $grp aio_unlink $src;
		742	}
		743	};
		744	} else {
		745	$grp->result ($_[0]);
		746	}
		747	};
		748
		749	$grp
		750	}
427		751
428	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	752	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
429		753
430	Scans a directory (similar to C<aio_readdir>) but additionally tries to	754	Scans a directory (similar to C<aio_readdir>) but additionally tries to
431	efficiently separate the entries of directory C<$path> into two sets of	755	efficiently separate the entries of directory C<$path> into two sets of
…		…
433	recurse into (everything else, including symlinks to directories).	757	recurse into (everything else, including symlinks to directories).
434		758
435	C<aio_scandir> is a composite request that creates of many sub requests_	759	C<aio_scandir> is a composite request that creates of many sub requests_
436	C<$maxreq> specifies the maximum number of outstanding aio requests that	760	C<$maxreq> specifies the maximum number of outstanding aio requests that
437	this function generates. If it is C<< <= 0 >>, then a suitable default	761	this function generates. If it is C<< <= 0 >>, then a suitable default
438	will be chosen (currently 6).	762	will be chosen (currently 4).
439		763
440	On error, the callback is called without arguments, otherwise it receives	764	On error, the callback is called without arguments, otherwise it receives
441	two array-refs with path-relative entry names.	765	two array-refs with path-relative entry names.
442		766
443	Example:	767	Example:
…		…
450		774
451	Implementation notes.	775	Implementation notes.
452		776
453	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.
454		778
		779	If readdir returns file type information, then this is used directly to
		780	find directories.
		781
455	After reading the directory, the modification time, size etc. of the	782	Otherwise, after reading the directory, the modification time, size etc.
456	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
457	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
458	entries are directories (if >= 2). Otherwise, no knowledge of the number	785	how many entries are directories (if >= 2). Otherwise, no knowledge of the
459	of subdirectories will be assumed.	786	number of subdirectories will be assumed.
460		787
461	Then entries will be sorted into likely directories (everything without	788	Then entries will be sorted into likely directories a non-initial dot
462	a non-initial dot currently) and likely non-directories (everything	789	currently) and likely non-directories (see C<aio_readdirx>). Then every
463	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,
464	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
465	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
466	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
467	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
468	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.
469		797
470	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
471	rest of the entries is assumed to be non-directories.	799	rest of the entries is assumed to be non-directories.
472		800
473	This only works with certainty on POSIX (= UNIX) filesystems, which	801	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
477	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
478	directory counting heuristic.	806	directory counting heuristic.
479		807
480	=cut	808	=cut
481		809
482	sub aio_scandir($$$) {	810	sub aio_scandir($$;$) {
483	my ($path, $maxreq, $cb) = @_;	811	my ($path, $maxreq, $cb) = @_;
484		812
		813	my $pri = aioreq_pri;
		814
485	my $grp = aio_group $cb;	815	my $grp = aio_group $cb;
486		816
487	$maxreq = 6 if $maxreq <= 0;	817	$maxreq = 4 if $maxreq <= 0;
488		818
489	# stat once	819	# stat once
		820	aioreq_pri $pri;
490	add $grp aio_stat $path, sub {	821	add $grp aio_stat $path, sub {
491	return $grp->result () if $_[0];	822	return $grp->result () if $_[0];
492	my $now = time;	823	my $now = time;
493	my $hash1 = join ":", (stat _)[0,1,3,7,9];	824	my $hash1 = join ":", (stat _)[0,1,3,7,9];
494		825
495	# read the directory entries	826	# read the directory entries
		827	aioreq_pri $pri;
496	add $grp aio_readdir $path, sub {	828	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
497	my $entries = shift	829	my $entries = shift
498	or return $grp->result ();	830	or return $grp->result ();
499		831
500	# stat the dir another time	832	# stat the dir another time
		833	aioreq_pri $pri;
501	add $grp aio_stat $path, sub {	834	add $grp aio_stat $path, sub {
502	my $hash2 = join ":", (stat _)[0,1,3,7,9];	835	my $hash2 = join ":", (stat _)[0,1,3,7,9];
503		836
504	my $ndirs;	837	my $ndirs;
505		838
506	# take the slow route if anything looks fishy	839	# take the slow route if anything looks fishy
507	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	840	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
508	$ndirs = -1;	841	$ndirs = -1;
509	} else {	842	} else {
510	# if nlink == 2, we are finished	843	# if nlink == 2, we are finished
511	# on non-posix-fs's, we rely on nlink < 2	844	# for non-posix-fs's, we rely on nlink < 2
512	$ndirs = (stat _)[3] - 2	845	$ndirs = (stat _)[3] - 2
513	or return $grp->result ([], $entries);	846	or return $grp->result ([], $entries);
514	}	847	}
515		848
516	# sort into likely dirs and likely nondirs
517	# dirs == files without ".", short entries first
518	$entries = [map $_->[0],
519	sort { $b->[1] cmp $a->[1] }
520	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
521	@$entries];
522
523	my (@dirs, @nondirs);	849	my (@dirs, @nondirs);
524		850
525	my $statgrp = add $grp aio_group sub {	851	my $statgrp = add $grp aio_group sub {
526	$grp->result (\@dirs, \@nondirs);	852	$grp->result (\@dirs, \@nondirs);
527	};	853	};
528		854
529	limit $statgrp $maxreq;	855	limit $statgrp $maxreq;
530	feed $statgrp sub {	856	feed $statgrp sub {
531	return unless @$entries;	857	return unless @$entries;
532	my $entry = pop @$entries;	858	my $entry = shift @$entries;
533		859
		860	aioreq_pri $pri;
534	add $statgrp aio_stat "$path/$entry/.", sub {	861	add $statgrp aio_stat "$path/$entry/.", sub {
535	if ($_[0] < 0) {	862	if ($_[0] < 0) {
536	push @nondirs, $entry;	863	push @nondirs, $entry;
537	} else {	864	} else {
538	# need to check for real directory	865	# need to check for real directory
		866	aioreq_pri $pri;
539	add $statgrp aio_lstat "$path/$entry", sub {	867	add $statgrp aio_lstat "$path/$entry", sub {
540	if (-d _) {	868	if (-d _) {
541	push @dirs, $entry;	869	push @dirs, $entry;
542		870
543	unless (--$ndirs) {	871	unless (--$ndirs) {
…		…
556	};	884	};
557		885
558	$grp	886	$grp
559	}	887	}
560		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
561	=item aio_fsync $fh, $callback->($status)	928	=item aio_fsync $fh, $callback->($status)
562		929
563	Asynchronously call fsync on the given filehandle and call the callback	930	Asynchronously call fsync on the given filehandle and call the callback
564	with the fsync result code.	931	with the fsync result code.
565		932
…		…
568	Asynchronously call fdatasync on the given filehandle and call the	935	Asynchronously call fdatasync on the given filehandle and call the
569	callback with the fdatasync result code.	936	callback with the fdatasync result code.
570		937
571	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
572	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	}
573		993
574	=item aio_group $callback->(...)	994	=item aio_group $callback->(...)
575		995
576	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
577	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
…		…
627	=item cancel $req	1047	=item cancel $req
628		1048
629	Cancels the request, if possible. Has the effect of skipping execution	1049	Cancels the request, if possible. Has the effect of skipping execution
630	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
631	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
632	untouched. That means that requests that currently execute will not be	1052	untouched (with the exception of readdir). That means that requests that
633	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.
634		1055
635	=item cb $req $callback->(...)	1056	=item cb $req $callback->(...)
636		1057
637	Replace (or simply set) the callback registered to the request.	1058	Replace (or simply set) the callback registered to the request.
638		1059
…		…
689	Their lifetime, simplified, looks like this: when they are empty, they	1110	Their lifetime, simplified, looks like this: when they are empty, they
690	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
691	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
692	exist.	1113	exist.
693		1114
694	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
695	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
696	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
697	itself finish.	1118	further requests to the group. And only when all those requests have
		1119	finished will the the group itself finish.
698		1120
699	=over 4	1121	=over 4
700		1122
701	=item add $grp ...	1123	=item add $grp ...
702		1124
…		…
714	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.
715		1137
716	=item $grp->result (...)	1138	=item $grp->result (...)
717		1139
718	Set the result value(s) that will be passed to the group callback when all	1140	Set the result value(s) that will be passed to the group callback when all
719	subrequests have finished. By default, no argument will be passed.	1141	subrequests have finished and set the groups errno to the current value
		1142	of errno (just like calling C<errno> without an error number). By default,
		1143	no argument will be passed and errno is zero.
		1144
		1145	=item $grp->errno ([$errno])
		1146
		1147	Sets the group errno value to C<$errno>, or the current value of errno
		1148	when the argument is missing.
		1149
		1150	Every aio request has an associated errno value that is restored when
		1151	the callback is invoked. This method lets you change this value from its
		1152	default (0).
		1153
		1154	Calling C<result> will also set errno, so make sure you either set C<$!>
		1155	before the call to C<result>, or call c<errno> after it.
720		1156
721	=item feed $grp $callback->($grp)	1157	=item feed $grp $callback->($grp)
722		1158
723	Sets a feeder/generator on this group: every group can have an attached	1159	Sets a feeder/generator on this group: every group can have an attached
724	generator that generates requests if idle. The idea behind this is that,	1160	generator that generates requests if idle. The idea behind this is that,
725	although you could just queue as many requests as you want in a group,	1161	although you could just queue as many requests as you want in a group,
726	this might starve other requests for a potentially long time. For	1162	this might starve other requests for a potentially long time. For example,
727	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1163	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
728	requests, delaying any later requests for a long time.	1164	delaying any later requests for a long time.
729		1165
730	To avoid this, and allow incremental generation of requests, you can	1166	To avoid this, and allow incremental generation of requests, you can
731	instead a group and set a feeder on it that generates those requests. The	1167	instead a group and set a feeder on it that generates those requests. The
732	feed callback will be called whenever there are few enough (see C<limit>,	1168	feed callback will be called whenever there are few enough (see C<limit>,
733	below) requests active in the group itself and is expected to queue more	1169	below) requests active in the group itself and is expected to queue more
…		…
737	not impose any limits).	1173	not impose any limits).
738		1174
739	If the feed does not queue more requests when called, it will be	1175	If the feed does not queue more requests when called, it will be
740	automatically removed from the group.	1176	automatically removed from the group.
741		1177
742	If the feed limit is C<0>, it will be set to C<2> automatically.	1178	If the feed limit is C<0> when this method is called, it will be set to
		1179	C<2> automatically.
743		1180
744	Example:	1181	Example:
745		1182
746	# stat all files in @files, but only ever use four aio requests concurrently:	1183	# stat all files in @files, but only ever use four aio requests concurrently:
747		1184
…		…
759	Sets the feeder limit for the group: The feeder will be called whenever	1196	Sets the feeder limit for the group: The feeder will be called whenever
760	the group contains less than this many requests.	1197	the group contains less than this many requests.
761		1198
762	Setting the limit to C<0> will pause the feeding process.	1199	Setting the limit to C<0> will pause the feeding process.
763		1200
		1201	The default value for the limit is C<0>, but note that setting a feeder
		1202	automatically bumps it up to C<2>.
		1203
764	=back	1204	=back
765		1205
766	=head2 SUPPORT FUNCTIONS	1206	=head2 SUPPORT FUNCTIONS
767		1207
		1208	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1209
768	=over 4	1210	=over 4
769		1211
770	=item $fileno = IO::AIO::poll_fileno	1212	=item $fileno = IO::AIO::poll_fileno
771		1213
772	Return the I<request result pipe file descriptor>. This filehandle must be	1214	Return the I<request result pipe file descriptor>. This filehandle must be
773	polled for reading by some mechanism outside this module (e.g. Event or	1215	polled for reading by some mechanism outside this module (e.g. EV, Glib,
774	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1216	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
775	to call C<poll_cb> to check the results.	1217	you have to call C<poll_cb> to check the results.
776		1218
777	See C<poll_cb> for an example.	1219	See C<poll_cb> for an example.
778		1220
779	=item IO::AIO::poll_cb	1221	=item IO::AIO::poll_cb
780		1222
781	Process all outstanding events on the result pipe. You have to call this	1223	Process some outstanding events on the result pipe. You have to call this
782	regularly. Returns the number of events processed. Returns immediately	1224	regularly. Returns C<0> if all events could be processed, or C<-1> if it
783	when no events are outstanding.	1225	returned earlier for whatever reason. Returns immediately when no events
		1226	are outstanding. The amount of events processed depends on the settings of
		1227	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1228
		1229	If not all requests were processed for whatever reason, the filehandle
		1230	will still be ready when C<poll_cb> returns, so normally you don't have to
		1231	do anything special to have it called later.
784		1232
785	Example: Install an Event watcher that automatically calls	1233	Example: Install an Event watcher that automatically calls
786	IO::AIO::poll_cb with high priority:	1234	IO::AIO::poll_cb with high priority (more examples can be found in the
		1235	SYNOPSIS section, at the top of this document):
787		1236
788	Event->io (fd => IO::AIO::poll_fileno,	1237	Event->io (fd => IO::AIO::poll_fileno,
789	poll => 'r', async => 1,	1238	poll => 'r', async => 1,
790	cb => \&IO::AIO::poll_cb);	1239	cb => \&IO::AIO::poll_cb);
791		1240
		1241	=item IO::AIO::max_poll_reqs $nreqs
		1242
		1243	=item IO::AIO::max_poll_time $seconds
		1244
		1245	These set the maximum number of requests (default C<0>, meaning infinity)
		1246	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1247	the maximum amount of time (default C<0>, meaning infinity) spent in
		1248	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1249	of time C<poll_cb> is allowed to use).
		1250
		1251	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1252	syscall per request processed, which is not normally a problem unless your
		1253	callbacks are really really fast or your OS is really really slow (I am
		1254	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1255
		1256	Setting these is useful if you want to ensure some level of
		1257	interactiveness when perl is not fast enough to process all requests in
		1258	time.
		1259
		1260	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1261
		1262	Example: Install an Event watcher that automatically calls
		1263	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1264	program get the CPU sometimes even under high AIO load.
		1265
		1266	# try not to spend much more than 0.1s in poll_cb
		1267	IO::AIO::max_poll_time 0.1;
		1268
		1269	# use a low priority so other tasks have priority
		1270	Event->io (fd => IO::AIO::poll_fileno,
		1271	poll => 'r', nice => 1,
		1272	cb => &IO::AIO::poll_cb);
		1273
792	=item IO::AIO::poll_wait	1274	=item IO::AIO::poll_wait
793		1275
		1276	If there are any outstanding requests and none of them in the result
794	Wait till the result filehandle becomes ready for reading (simply does a	1277	phase, wait till the result filehandle becomes ready for reading (simply
795	C<select> on the filehandle. This is useful if you want to synchronously wait	1278	does a C<select> on the filehandle. This is useful if you want to
796	for some requests to finish).	1279	synchronously wait for some requests to finish).
797		1280
798	See C<nreqs> for an example.	1281	See C<nreqs> for an example.
799		1282
		1283	=item IO::AIO::poll
		1284
		1285	Waits until some requests have been handled.
		1286
		1287	Returns the number of requests processed, but is otherwise strictly
		1288	equivalent to:
		1289
		1290	IO::AIO::poll_wait, IO::AIO::poll_cb
		1291
800	=item IO::AIO::nreqs	1292	=item IO::AIO::flush
801		1293
802	Returns the number of requests currently outstanding (i.e. for which their	1294	Wait till all outstanding AIO requests have been handled.
803	callback has not been invoked yet).
804		1295
805	Example: wait till there are no outstanding requests anymore:	1296	Strictly equivalent to:
806		1297
807	IO::AIO::poll_wait, IO::AIO::poll_cb	1298	IO::AIO::poll_wait, IO::AIO::poll_cb
808	while IO::AIO::nreqs;	1299	while IO::AIO::nreqs;
809		1300
810	=item IO::AIO::flush	1301	=back
811		1302
812	Wait till all outstanding AIO requests have been handled.	1303	=head3 CONTROLLING THE NUMBER OF THREADS
813		1304
814	Strictly equivalent to:	1305	=over
815
816	IO::AIO::poll_wait, IO::AIO::poll_cb
817	while IO::AIO::nreqs;
818
819	=item IO::AIO::poll
820
821	Waits until some requests have been handled.
822
823	Strictly equivalent to:
824
825	IO::AIO::poll_wait, IO::AIO::poll_cb
826	if IO::AIO::nreqs;
827		1306
828	=item IO::AIO::min_parallel $nthreads	1307	=item IO::AIO::min_parallel $nthreads
829		1308
830	Set the minimum number of AIO threads to C<$nthreads>. The current	1309	Set the minimum number of AIO threads to C<$nthreads>. The current
831	default is C<8>, which means eight asynchronous operations can execute	1310	default is C<8>, which means eight asynchronous operations can execute
832	concurrently at any one time (the number of outstanding requests,	1311	concurrently at any one time (the number of outstanding requests,
833	however, is unlimited).	1312	however, is unlimited).
834		1313
835	IO::AIO starts threads only on demand, when an AIO request is queued and	1314	IO::AIO starts threads only on demand, when an AIO request is queued and
836	no free thread exists.	1315	no free thread exists. Please note that queueing up a hundred requests can
		1316	create demand for a hundred threads, even if it turns out that everything
		1317	is in the cache and could have been processed faster by a single thread.
837		1318
838	It is recommended to keep the number of threads relatively low, as some	1319	It is recommended to keep the number of threads relatively low, as some
839	Linux kernel versions will scale negatively with the number of threads	1320	Linux kernel versions will scale negatively with the number of threads
840	(higher parallelity => MUCH higher latency). With current Linux 2.6	1321	(higher parallelity => MUCH higher latency). With current Linux 2.6
841	versions, 4-32 threads should be fine.	1322	versions, 4-32 threads should be fine.
…		…
855	This module automatically runs C<max_parallel 0> at program end, to ensure	1336	This module automatically runs C<max_parallel 0> at program end, to ensure
856	that all threads are killed and that there are no outstanding requests.	1337	that all threads are killed and that there are no outstanding requests.
857		1338
858	Under normal circumstances you don't need to call this function.	1339	Under normal circumstances you don't need to call this function.
859		1340
		1341	=item IO::AIO::max_idle $nthreads
		1342
		1343	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1344	threads that did not get a request to process within 10 seconds). That
		1345	means if a thread becomes idle while C<$nthreads> other threads are also
		1346	idle, it will free its resources and exit.
		1347
		1348	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1349	to allow for extremely high load situations, but want to free resources
		1350	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1351
		1352	The default is probably ok in most situations, especially if thread
		1353	creation is fast. If thread creation is very slow on your system you might
		1354	want to use larger values.
		1355
860	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1356	=item IO::AIO::max_outstanding $maxreqs
861		1357
862	[REMOVED]	1358	This is a very bad function to use in interactive programs because it
		1359	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1360	use an C<aio_group> together with a feed callback.
863		1361
864	Pre-2.x versions used max_outstanding for a crude request queue length limit.
865
866	In 2.x+ you are advised to use a group and a feeder to limit
867	concurrency. The max_outstanding feature ran very unstable (endless
868	recursions causing segfaults, bad interaction with groups etc.) and was
869	removed.
870
871	I am deeply sorry, but I am still on the hunt for a good limiting interface.
872
873	Original description was as follows:
874
875	Sets the maximum number of outstanding requests to C<$nreqs>. If you try	1362	Sets the maximum number of outstanding requests to C<$nreqs>. If you
876	to queue up more than this number of requests, the caller will block until	1363	do queue up more than this number of requests, the next call to the
877	some requests have been handled.	1364	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1365	function will block until the limit is no longer exceeded.
		1366
		1367	The default value is very large, so there is no practical limit on the
		1368	number of outstanding requests.
		1369
		1370	You can still queue as many requests as you want. Therefore,
		1371	C<max_outstanding> is mainly useful in simple scripts (with low values) or
		1372	as a stop gap to shield against fatal memory overflow (with large values).
878		1373
879	=back	1374	=back
880		1375
		1376	=head3 STATISTICAL INFORMATION
		1377
		1378	=over
		1379
		1380	=item IO::AIO::nreqs
		1381
		1382	Returns the number of requests currently in the ready, execute or pending
		1383	states (i.e. for which their callback has not been invoked yet).
		1384
		1385	Example: wait till there are no outstanding requests anymore:
		1386
		1387	IO::AIO::poll_wait, IO::AIO::poll_cb
		1388	while IO::AIO::nreqs;
		1389
		1390	=item IO::AIO::nready
		1391
		1392	Returns the number of requests currently in the ready state (not yet
		1393	executed).
		1394
		1395	=item IO::AIO::npending
		1396
		1397	Returns the number of requests currently in the pending state (executed,
		1398	but not yet processed by poll_cb).
		1399
		1400	=back
		1401
		1402	=head3 MISCELLANEOUS FUNCTIONS
		1403
		1404	IO::AIO implements some functions that might be useful, but are not
		1405	asynchronous.
		1406
		1407	=over 4
		1408
		1409	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1410
		1411	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1412	but is blocking (this makes most sense if you know the input data is
		1413	likely cached already and the output filehandle is set to non-blocking
		1414	operations).
		1415
		1416	Returns the number of bytes copied, or C<-1> on error.
		1417
		1418	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1419
		1420	Simply calls the C<posix_fadvise> function (see it's
		1421	manpage for details). The following advice constants are
		1422	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1423	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1424	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1425
		1426	On systems that do not implement C<posix_fadvise>, this function returns
		1427	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1428
		1429	=back
		1430
881	=cut	1431	=cut
882		1432
883	# support function to convert a fd into a perl filehandle
884	sub _fd2fh {
885	return undef if $_[0] < 0;
886
887	# try to generate nice filehandles
888	my $sym = "IO::AIO::fd#$_[0]";
889	local *$sym;
890
891	open *$sym, "+<&=$_[0]" # usually works under any unix
892	or open *$sym, "<&=$_[0]" # cygwin needs this
893	or open *$sym, ">&=$_[0]" # or this
894	or return undef;
895
896	*$sym
897	}
898
899	min_parallel 8;	1433	min_parallel 8;
900		1434
901	END {	1435	END { flush }
902	max_parallel 0;
903	}
904		1436
905	1;	1437	1;
906		1438
907	=head2 FORK BEHAVIOUR	1439	=head2 FORK BEHAVIOUR
908		1440
…		…
928	bytes of memory. In addition, stat requests need a stat buffer (possibly	1460	bytes of memory. In addition, stat requests need a stat buffer (possibly
929	a few hundred bytes), readdir requires a result buffer and so on. Perl	1461	a few hundred bytes), readdir requires a result buffer and so on. Perl
930	scalars and other data passed into aio requests will also be locked and	1462	scalars and other data passed into aio requests will also be locked and
931	will consume memory till the request has entered the done state.	1463	will consume memory till the request has entered the done state.
932		1464
933	This is now awfully much, so queuing lots of requests is not usually a	1465	This is not awfully much, so queuing lots of requests is not usually a
934	problem.	1466	problem.
935		1467
936	Per-thread usage:	1468	Per-thread usage:
937		1469
938	In the execution phase, some aio requests require more memory for	1470	In the execution phase, some aio requests require more memory for
…		…
943		1475
944	Known bugs will be fixed in the next release.	1476	Known bugs will be fixed in the next release.
945		1477
946	=head1 SEE ALSO	1478	=head1 SEE ALSO
947		1479
948	L<Coro::AIO>.	1480	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1481	more natural syntax.
949		1482
950	=head1 AUTHOR	1483	=head1 AUTHOR
951		1484
952	Marc Lehmann <schmorp@schmorp.de>	1485	Marc Lehmann <schmorp@schmorp.de>
953	http://home.schmorp.de/	1486	http://home.schmorp.de/

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing IO-AIO/AIO.pm (file contents): Revision 1.77 by root, Wed Oct 25 17:57:30 2006 UTC vs. Revision 1.163 by root, Wed Aug 5 11:53:16 2009 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.77 by root, Wed Oct 25 17:57:30 2006 UTC vs.
Revision 1.163 by root, Wed Aug 5 11:53:16 2009 UTC