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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs.
Revision 1.119 by root, Sun Dec 2 20:54:33 2007 UTC

…		…
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", O_RDONLY, 0, sub {
10	my ($fh) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
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
30	# AnyEvent integration	31	# AnyEvent integration (EV, Event, Glib, Tk, urxvt, pureperl...)
31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	32	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });	33	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
		34
		35	# EV integration
		36	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
33		37
34	# Event integration	38	# Event integration
35	Event->io (fd => IO::AIO::poll_fileno,	39	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',	40	poll => 'r',
37	cb => \&IO::AIO::poll_cb);	41	cb => \&IO::AIO::poll_cb);
…		…
51	=head1 DESCRIPTION	55	=head1 DESCRIPTION
52		56
53	This module implements asynchronous I/O using whatever means your	57	This module implements asynchronous I/O using whatever means your
54	operating system supports.	58	operating system supports.
55		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 very
		73	inefficient. Use an event loop for that (such as the L<Event\|Event>
		74	module): IO::AIO will naturally fit into such an event loop itself.
		75
56	Currently, a number of threads are started that execute your read/writes	76	In this version, a number of threads are started that execute your
57	and signal their completion. You don't need thread support in perl, and	77	requests and signal their completion. You don't need thread support
58	the threads created by this module will not be visible to perl. In the	78	in perl, and the threads created by this module will not be visible
59	future, this module might make use of the native aio functions available	79	to perl. In the future, this module might make use of the native aio
60	on many operating systems. However, they are often not well-supported	80	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	81	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	and they would only support aio_read and aio_write, so the remaining	82	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	83	aio_write, so the remaining functionality would have to be implemented
		84	using threads anyway.
64		85
65	Although the module will work with in the presence of other threads,	86	Although the module will work in the presence of other (Perl-) threads,
66	it is currently not reentrant in any way, so use appropriate locking	87	it is currently not reentrant in any way, so use appropriate locking
67	yourself, always call C<poll_cb> from within the same thread, or never	88	yourself, always call C<poll_cb> from within the same thread, or never
68	call C<poll_cb> (or other C<aio_> functions) recursively.	89	call C<poll_cb> (or other C<aio_> functions) recursively.
69		90
		91	=head2 EXAMPLE
		92
		93	This is a simple example that uses the Event module and loads
		94	F</etc/passwd> asynchronously:
		95
		96	use Fcntl;
		97	use Event;
		98	use IO::AIO;
		99
		100	# register the IO::AIO callback with Event
		101	Event->io (fd => IO::AIO::poll_fileno,
		102	poll => 'r',
		103	cb => \&IO::AIO::poll_cb);
		104
		105	# queue the request to open /etc/passwd
		106	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		107	my $fh = shift
		108	or die "error while opening: $!";
		109
		110	# stat'ing filehandles is generally non-blocking
		111	my $size = -s $fh;
		112
		113	# queue a request to read the file
		114	my $contents;
		115	aio_read $fh, 0, $size, $contents, 0, sub {
		116	$_[0] == $size
		117	or die "short read: $!";
		118
		119	close $fh;
		120
		121	# file contents now in $contents
		122	print $contents;
		123
		124	# exit event loop and program
		125	Event::unloop;
		126	};
		127	};
		128
		129	# possibly queue up other requests, or open GUI windows,
		130	# check for sockets etc. etc.
		131
		132	# process events as long as there are some:
		133	Event::loop;
		134
		135	=head1 REQUEST ANATOMY AND LIFETIME
		136
		137	Every C<aio_*> function creates a request. which is a C data structure not
		138	directly visible to Perl.
		139
		140	If called in non-void context, every request function returns a Perl
		141	object representing the request. In void context, nothing is returned,
		142	which saves a bit of memory.
		143
		144	The perl object is a fairly standard ref-to-hash object. The hash contents
		145	are not used by IO::AIO so you are free to store anything you like in it.
		146
		147	During their existance, aio requests travel through the following states,
		148	in order:
		149
		150	=over 4
		151
		152	=item ready
		153
		154	Immediately after a request is created it is put into the ready state,
		155	waiting for a thread to execute it.
		156
		157	=item execute
		158
		159	A thread has accepted the request for processing and is currently
		160	executing it (e.g. blocking in read).
		161
		162	=item pending
		163
		164	The request has been executed and is waiting for result processing.
		165
		166	While request submission and execution is fully asynchronous, result
		167	processing is not and relies on the perl interpreter calling C<poll_cb>
		168	(or another function with the same effect).
		169
		170	=item result
		171
		172	The request results are processed synchronously by C<poll_cb>.
		173
		174	The C<poll_cb> function will process all outstanding aio requests by
		175	calling their callbacks, freeing memory associated with them and managing
		176	any groups they are contained in.
		177
		178	=item done
		179
		180	Request has reached the end of its lifetime and holds no resources anymore
		181	(except possibly for the Perl object, but its connection to the actual
		182	aio request is severed and calling its methods will either do nothing or
		183	result in a runtime error).
		184
		185	=back
		186
70	=cut	187	=cut
71		188
72	package IO::AIO;	189	package IO::AIO;
		190
		191	use Carp ();
73		192
74	no warnings;	193	no warnings;
75	use strict 'vars';	194	use strict 'vars';
76		195
77	use base 'Exporter';	196	use base 'Exporter';
78		197
79	BEGIN {	198	BEGIN {
80	our $VERSION = '2.0';	199	our $VERSION = '2.6';
81		200
82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	201	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
83	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	202	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	203	aio_readlink aio_sync aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
85	aio_group aio_nop);	204	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
		205	aio_chown aio_chmod aio_utime aio_truncate);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	206	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	207	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	208	min_parallel max_parallel max_idle
		209	nreqs nready npending nthreads
		210	max_poll_time max_poll_reqs);
89		211
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	212	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		213
92	require XSLoader;	214	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	215	XSLoader::load ("IO::AIO", $VERSION);
94	}	216	}
95		217
96	=head1 FUNCTIONS	218	=head1 FUNCTIONS
97		219
98	=head2 AIO FUNCTIONS	220	=head2 AIO REQUEST FUNCTIONS
99		221
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	222	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	223	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	224	and they all accept an additional (and optional) C<$callback> argument
103	which must be a code reference. This code reference will get called with	225	which must be a code reference. This code reference will get called with
…		…
106	syscall has been executed asynchronously.	228	syscall has been executed asynchronously.
107		229
108	All functions expecting a filehandle keep a copy of the filehandle	230	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	231	internally until the request has finished.
110		232
111	All requests return objects of type L<IO::AIO::REQ> that allow further	233	All functions return request objects of type L<IO::AIO::REQ> that allow
112	manipulation of those requests while they are in-flight.	234	further manipulation of those requests while they are in-flight.
113		235
114	The pathnames you pass to these routines I<must> be absolute and	236	The pathnames you pass to these routines I<must> be absolute and
115	encoded in byte form. The reason for the former is that at the time the	237	encoded as octets. The reason for the former is that at the time the
116	request is being executed, the current working directory could have	238	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	239	changed. Alternatively, you can make sure that you never change the
118	current working directory.	240	current working directory anywhere in the program and then use relative
		241	paths.
119		242
120	To encode pathnames to byte form, either make sure you either: a)	243	To encode pathnames as octets, either make sure you either: a) always pass
121	always pass in filenames you got from outside (command line, readdir	244	in filenames you got from outside (command line, readdir etc.) without
122	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	245	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
123	your pathnames to the locale (or other) encoding in effect in the user	246	your pathnames to the locale (or other) encoding in effect in the user
124	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	247	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	248	use something else to ensure your scalar has the correct contents.
		249
		250	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		251	handles correctly wether it is set or not.
126		252
127	=over 4	253	=over 4
128		254
129	=item aioreq_pri $pri	255	=item $prev_pri = aioreq_pri [$pri]
130		256
131	Sets the priority for the next aio request. The default priority	257	Returns the priority value that would be used for the next request and, if
		258	C<$pri> is given, sets the priority for the next aio request.
		259
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	260	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	261	and C<4>, respectively. Requests with higher priority will be serviced
		262	first.
134		263
135	The priority will be reset to C<0> after each call to one of the C<aio_>	264	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	265	functions.
		266
		267	Example: open a file with low priority, then read something from it with
		268	higher priority so the read request is serviced before other low priority
		269	open requests (potentially spamming the cache):
		270
		271	aioreq_pri -3;
		272	aio_open ..., sub {
		273	return unless $_[0];
		274
		275	aioreq_pri -2;
		276	aio_read $_[0], ..., sub {
		277	...
		278	};
		279	};
		280
		281
		282	=item aioreq_nice $pri_adjust
		283
		284	Similar to C<aioreq_pri>, but subtracts the given value from the current
		285	priority, so the effect is cumulative.
		286
137		287
138	=item aio_open $pathname, $flags, $mode, $callback->($fh)	288	=item aio_open $pathname, $flags, $mode, $callback->($fh)
139		289
140	Asynchronously open or create a file and call the callback with a newly	290	Asynchronously open or create a file and call the callback with a newly
141	created filehandle for the file.	291	created filehandle for the file.
…		…
147	list. They are the same as used by C<sysopen>.	297	list. They are the same as used by C<sysopen>.
148		298
149	Likewise, C<$mode> specifies the mode of the newly created file, if it	299	Likewise, C<$mode> specifies the mode of the newly created file, if it
150	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	300	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
151	except that it is mandatory (i.e. use C<0> if you don't create new files,	301	except that it is mandatory (i.e. use C<0> if you don't create new files,
152	and C<0666> or C<0777> if you do).	302	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		303	by the umask in effect then the request is being executed, so better never
		304	change the umask.
153		305
154	Example:	306	Example:
155		307
156	aio_open "/etc/passwd", O_RDONLY, 0, sub {	308	aio_open "/etc/passwd", O_RDONLY, 0, sub {
157	if ($_[0]) {	309	if ($_[0]) {
…		…
160	} else {	312	} else {
161	die "open failed: $!\n";	313	die "open failed: $!\n";
162	}	314	}
163	};	315	};
164		316
		317
165	=item aio_close $fh, $callback->($status)	318	=item aio_close $fh, $callback->($status)
166		319
167	Asynchronously close a file and call the callback with the result	320	Asynchronously close a file and call the callback with the result
168	code. I<WARNING:> although accepted, you should not pass in a perl	321	code.
169	filehandle here, as perl will likely close the file descriptor another
170	time when the filehandle is destroyed. Normally, you can safely call perls
171	C<close> or just let filehandles go out of scope.
172		322
173	This is supposed to be a bug in the API, so that might change. It's	323	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
174	therefore best to avoid this function.	324	closing the file descriptor associated with the filehandle itself. Here is
		325	what aio_close will try:
		326
		327	1. dup()licate the fd
		328	2. asynchronously close() the duplicated fd
		329	3. dup()licate the fd once more
		330	4. let perl close() the filehandle
		331	5. asynchronously close the duplicated fd
		332
		333	The idea is that the first close() flushes stuff to disk that closing an
		334	fd will flush, so when perl closes the fd, nothing much will need to be
		335	flushed. The second async. close() will then flush stuff to disk that
		336	closing the last fd to the file will flush.
		337
		338	Just FYI, SuSv3 has this to say on close:
		339
		340	All outstanding record locks owned by the process on the file
		341	associated with the file descriptor shall be removed.
		342
		343	If fildes refers to a socket, close() shall cause the socket to be
		344	destroyed. ... close() shall block for up to the current linger
		345	interval until all data is transmitted.
		346	[this actually sounds like a specification bug, but who knows]
		347
		348	And at least Linux additionally actually flushes stuff on every close,
		349	even when the file itself is still open.
		350
		351	Sounds enourmously inefficient and complicated? Yes... please show me how
		352	to nuke perl's fd out of existence...
		353
		354	=cut
		355
		356	sub aio_close($;$) {
		357	aio_block {
		358	my ($fh, $cb) = @_;
		359
		360	my $pri = aioreq_pri;
		361	my $grp = aio_group $cb;
		362
		363	my $fd = fileno $fh;
		364
		365	defined $fd or Carp::croak "aio_close called with fd-less filehandle";
		366
		367	# if the dups fail we will simply get EBADF
		368	my $fd2 = _dup $fd;
		369	aioreq_pri $pri;
		370	add $grp _aio_close $fd2, sub {
		371	my $fd2 = _dup $fd;
		372	close $fh;
		373	aioreq_pri $pri;
		374	add $grp _aio_close $fd2, sub {
		375	$grp->result ($_[0]);
		376	};
		377	};
		378
		379	$grp
		380	}
		381	}
		382
175		383
176	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	384	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
177		385
178	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	386	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
179		387
180	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	388	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
181	into the scalar given by C<data> and offset C<dataoffset> and calls the	389	into the scalar given by C<$data> and offset C<$dataoffset> and calls the
182	callback without the actual number of bytes read (or -1 on error, just	390	callback without the actual number of bytes read (or -1 on error, just
183	like the syscall).	391	like the syscall).
184		392
		393	If C<$offset> is undefined, then the current file descriptor offset will
		394	be used (and updated), otherwise the file descriptor offset will not be
		395	changed by these calls.
		396
		397	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
		398
		399	If C<$dataoffset> is less than zero, it will be counted from the end of
		400	C<$data>.
		401
185	The C<$data> scalar I<MUST NOT> be modified in any way while the request	402	The C<$data> scalar I<MUST NOT> be modified in any way while the request
186	is outstanding. Modifying it can result in segfaults or WW3 (if the	403	is outstanding. Modifying it can result in segfaults or World War III (if
187	necessary/optional hardware is installed).	404	the necessary/optional hardware is installed).
188		405
189	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	406	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
190	offset C<0> within the scalar:	407	offset C<0> within the scalar:
191		408
192	aio_read $fh, 7, 15, $buffer, 0, sub {	409	aio_read $fh, 7, 15, $buffer, 0, sub {
193	$_[0] > 0 or die "read error: $!";	410	$_[0] > 0 or die "read error: $!";
194	print "read $_[0] bytes: <$buffer>\n";	411	print "read $_[0] bytes: <$buffer>\n";
195	};	412	};
196		413
197	=item aio_move $srcpath, $dstpath, $callback->($status)
198
199	[EXPERIMENTAL due to internal aio_group use]
200
201	Try to move the I<file> (directories not supported as either source or
202	destination) from C<$srcpath> to C<$dstpath> and call the callback with
203	the C<0> (error) or C<-1> ok.
204
205	This is a composite request that tries to rename(2) the file first. If
206	rename files with C<EXDEV>, it creates the destination file with mode 0200
207	and copies the contents of the source file into it using C<aio_sendfile>,
208	followed by restoring atime, mtime, access mode and uid/gid, in that
209	order, and unlinking the C<$srcpath>.
210
211	If an error occurs, the partial destination file will be unlinked, if
212	possible, except when setting atime, mtime, access mode and uid/gid, where
213	errors are being ignored.
214
215	=cut
216
217	sub aio_move($$$) {
218	my ($src, $dst, $cb) = @_;
219
220	my $grp = aio_group $cb;
221
222	add $grp aio_rename $src, $dst, sub {
223	if ($_[0] && $! == EXDEV) {
224	add $grp aio_open $src, O_RDONLY, 0, sub {
225	if (my $src_fh = $_[0]) {
226	my @stat = stat $src_fh;
227
228	add $grp aio_open $dst, O_WRONLY, 0200, sub {
229	if (my $dst_fh = $_[0]) {
230	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
231	close $src_fh;
232
233	if ($_[0] == $stat[7]) {
234	utime $stat[8], $stat[9], $dst;
235	chmod $stat[2] & 07777, $dst_fh;
236	chown $stat[4], $stat[5], $dst_fh;
237	close $dst_fh;
238
239	add $grp aio_unlink $src, sub {
240	$grp->result ($_[0]);
241	};
242	} else {
243	my $errno = $!;
244	add $grp aio_unlink $dst, sub {
245	$! = $errno;
246	$grp->result (-1);
247	};
248	}
249	};
250	} else {
251	$grp->result (-1);
252	}
253	},
254
255	} else {
256	$grp->result (-1);
257	}
258	};
259	} else {
260	$grp->result ($_[0]);
261	}
262	};
263
264	$grp
265	}
266		414
267	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	415	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
268		416
269	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	417	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
270	reading at byte offset C<$in_offset>, and starts writing at the current	418	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
284	C<$in_fh> than are written, and there is no way to find out how many	432	C<$in_fh> than are written, and there is no way to find out how many
285	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	433	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
286	provides the number of bytes written to C<$out_fh>. Only if the result	434	provides the number of bytes written to C<$out_fh>. Only if the result
287	value equals C<$length> one can assume that C<$length> bytes have been	435	value equals C<$length> one can assume that C<$length> bytes have been
288	read.	436	read.
		437
289		438
290	=item aio_readahead $fh,$offset,$length, $callback->($retval)	439	=item aio_readahead $fh,$offset,$length, $callback->($retval)
291		440
292	C<aio_readahead> populates the page cache with data from a file so that	441	C<aio_readahead> populates the page cache with data from a file so that
293	subsequent reads from that file will not block on disk I/O. The C<$offset>	442	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
299	file. The current file offset of the file is left unchanged.	448	file. The current file offset of the file is left unchanged.
300		449
301	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	450	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
302	emulated by simply reading the data, which would have a similar effect.	451	emulated by simply reading the data, which would have a similar effect.
303		452
		453
304	=item aio_stat $fh_or_path, $callback->($status)	454	=item aio_stat $fh_or_path, $callback->($status)
305		455
306	=item aio_lstat $fh, $callback->($status)	456	=item aio_lstat $fh, $callback->($status)
307		457
308	Works like perl's C<stat> or C<lstat> in void context. The callback will	458	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
321	aio_stat "/etc/passwd", sub {	471	aio_stat "/etc/passwd", sub {
322	$_[0] and die "stat failed: $!";	472	$_[0] and die "stat failed: $!";
323	print "size is ", -s _, "\n";	473	print "size is ", -s _, "\n";
324	};	474	};
325		475
		476
		477	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		478
		479	Works like perl's C<utime> function (including the special case of $atime
		480	and $mtime being undef). Fractional times are supported if the underlying
		481	syscalls support them.
		482
		483	When called with a pathname, uses utimes(2) if available, otherwise
		484	utime(2). If called on a file descriptor, uses futimes(2) if available,
		485	otherwise returns ENOSYS, so this is not portable.
		486
		487	Examples:
		488
		489	# set atime and mtime to current time (basically touch(1)):
		490	aio_utime "path", undef, undef;
		491	# set atime to current time and mtime to beginning of the epoch:
		492	aio_utime "path", time, undef; # undef==0
		493
		494
		495	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		496
		497	Works like perl's C<chown> function, except that C<undef> for either $uid
		498	or $gid is being interpreted as "do not change" (but -1 can also be used).
		499
		500	Examples:
		501
		502	# same as "chown root path" in the shell:
		503	aio_chown "path", 0, -1;
		504	# same as above:
		505	aio_chown "path", 0, undef;
		506
		507
		508	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		509
		510	Works like truncate(2) or ftruncate(2).
		511
		512
		513	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		514
		515	Works like perl's C<chmod> function.
		516
		517
326	=item aio_unlink $pathname, $callback->($status)	518	=item aio_unlink $pathname, $callback->($status)
327		519
328	Asynchronously unlink (delete) a file and call the callback with the	520	Asynchronously unlink (delete) a file and call the callback with the
329	result code.	521	result code.
330		522
		523
		524	=item aio_mknod $path, $mode, $dev, $callback->($status)
		525
		526	[EXPERIMENTAL]
		527
		528	Asynchronously create a device node (or fifo). See mknod(2).
		529
		530	The only (POSIX-) portable way of calling this function is:
		531
		532	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		533
		534
331	=item aio_link $srcpath, $dstpath, $callback->($status)	535	=item aio_link $srcpath, $dstpath, $callback->($status)
332		536
333	Asynchronously create a new link to the existing object at C<$srcpath> at	537	Asynchronously create a new link to the existing object at C<$srcpath> at
334	the path C<$dstpath> and call the callback with the result code.	538	the path C<$dstpath> and call the callback with the result code.
335		539
		540
336	=item aio_symlink $srcpath, $dstpath, $callback->($status)	541	=item aio_symlink $srcpath, $dstpath, $callback->($status)
337		542
338	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	543	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
339	the path C<$dstpath> and call the callback with the result code.	544	the path C<$dstpath> and call the callback with the result code.
340		545
		546
		547	=item aio_readlink $path, $callback->($link)
		548
		549	Asynchronously read the symlink specified by C<$path> and pass it to
		550	the callback. If an error occurs, nothing or undef gets passed to the
		551	callback.
		552
		553
341	=item aio_rename $srcpath, $dstpath, $callback->($status)	554	=item aio_rename $srcpath, $dstpath, $callback->($status)
342		555
343	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	556	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
344	rename(2) and call the callback with the result code.	557	rename(2) and call the callback with the result code.
345		558
		559
		560	=item aio_mkdir $pathname, $mode, $callback->($status)
		561
		562	Asynchronously mkdir (create) a directory and call the callback with
		563	the result code. C<$mode> will be modified by the umask at the time the
		564	request is executed, so do not change your umask.
		565
		566
346	=item aio_rmdir $pathname, $callback->($status)	567	=item aio_rmdir $pathname, $callback->($status)
347		568
348	Asynchronously rmdir (delete) a directory and call the callback with the	569	Asynchronously rmdir (delete) a directory and call the callback with the
349	result code.	570	result code.
		571
350		572
351	=item aio_readdir $pathname, $callback->($entries)	573	=item aio_readdir $pathname, $callback->($entries)
352		574
353	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	575	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
354	directory (i.e. opendir + readdir + closedir). The entries will not be	576	directory (i.e. opendir + readdir + closedir). The entries will not be
355	sorted, and will B<NOT> include the C<.> and C<..> entries.	577	sorted, and will B<NOT> include the C<.> and C<..> entries.
356		578
357	The callback a single argument which is either C<undef> or an array-ref	579	The callback a single argument which is either C<undef> or an array-ref
358	with the filenames.	580	with the filenames.
359		581
		582
		583	=item aio_load $path, $data, $callback->($status)
		584
		585	This is a composite request that tries to fully load the given file into
		586	memory. Status is the same as with aio_read.
		587
		588	=cut
		589
		590	sub aio_load($$;$) {
		591	aio_block {
		592	my ($path, undef, $cb) = @_;
		593	my $data = \$_[1];
		594
		595	my $pri = aioreq_pri;
		596	my $grp = aio_group $cb;
		597
		598	aioreq_pri $pri;
		599	add $grp aio_open $path, O_RDONLY, 0, sub {
		600	my $fh = shift
		601	or return $grp->result (-1);
		602
		603	aioreq_pri $pri;
		604	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		605	$grp->result ($_[0]);
		606	};
		607	};
		608
		609	$grp
		610	}
		611	}
		612
		613	=item aio_copy $srcpath, $dstpath, $callback->($status)
		614
		615	Try to copy the I<file> (directories not supported as either source or
		616	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		617	the C<0> (error) or C<-1> ok.
		618
		619	This is a composite request that it creates the destination file with
		620	mode 0200 and copies the contents of the source file into it using
		621	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		622	uid/gid, in that order.
		623
		624	If an error occurs, the partial destination file will be unlinked, if
		625	possible, except when setting atime, mtime, access mode and uid/gid, where
		626	errors are being ignored.
		627
		628	=cut
		629
		630	sub aio_copy($$;$) {
		631	aio_block {
		632	my ($src, $dst, $cb) = @_;
		633
		634	my $pri = aioreq_pri;
		635	my $grp = aio_group $cb;
		636
		637	aioreq_pri $pri;
		638	add $grp aio_open $src, O_RDONLY, 0, sub {
		639	if (my $src_fh = $_[0]) {
		640	my @stat = stat $src_fh;
		641
		642	aioreq_pri $pri;
		643	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		644	if (my $dst_fh = $_[0]) {
		645	aioreq_pri $pri;
		646	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		647	if ($_[0] == $stat[7]) {
		648	$grp->result (0);
		649	close $src_fh;
		650
		651	# those should not normally block. should. should.
		652	utime $stat[8], $stat[9], $dst;
		653	chmod $stat[2] & 07777, $dst_fh;
		654	chown $stat[4], $stat[5], $dst_fh;
		655	close $dst_fh;
		656	} else {
		657	$grp->result (-1);
		658	close $src_fh;
		659	close $dst_fh;
		660
		661	aioreq $pri;
		662	add $grp aio_unlink $dst;
		663	}
		664	};
		665	} else {
		666	$grp->result (-1);
		667	}
		668	},
		669
		670	} else {
		671	$grp->result (-1);
		672	}
		673	};
		674
		675	$grp
		676	}
		677	}
		678
		679	=item aio_move $srcpath, $dstpath, $callback->($status)
		680
		681	Try to move the I<file> (directories not supported as either source or
		682	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		683	the C<0> (error) or C<-1> ok.
		684
		685	This is a composite request that tries to rename(2) the file first. If
		686	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		687	that is successful, unlinking the C<$srcpath>.
		688
		689	=cut
		690
		691	sub aio_move($$;$) {
		692	aio_block {
		693	my ($src, $dst, $cb) = @_;
		694
		695	my $pri = aioreq_pri;
		696	my $grp = aio_group $cb;
		697
		698	aioreq_pri $pri;
		699	add $grp aio_rename $src, $dst, sub {
		700	if ($_[0] && $! == EXDEV) {
		701	aioreq_pri $pri;
		702	add $grp aio_copy $src, $dst, sub {
		703	$grp->result ($_[0]);
		704
		705	if (!$_[0]) {
		706	aioreq_pri $pri;
		707	add $grp aio_unlink $src;
		708	}
		709	};
		710	} else {
		711	$grp->result ($_[0]);
		712	}
		713	};
		714
		715	$grp
		716	}
		717	}
		718
360	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	719	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
361		720
362	[EXPERIMENTAL due to internal aio_group use]
363
364	Scans a directory (similar to C<aio_readdir>) but additionally tries to	721	Scans a directory (similar to C<aio_readdir>) but additionally tries to
365	separate the entries of directory C<$path> into two sets of names, ones	722	efficiently separate the entries of directory C<$path> into two sets of
366	you can recurse into (directories or links to them), and ones you cannot	723	names, directories you can recurse into (directories), and ones you cannot
367	recurse into (everything else).	724	recurse into (everything else, including symlinks to directories).
368		725
369	C<aio_scandir> is a composite request that creates of many sub requests_	726	C<aio_scandir> is a composite request that creates of many sub requests_
370	C<$maxreq> specifies the maximum number of outstanding aio requests that	727	C<$maxreq> specifies the maximum number of outstanding aio requests that
371	this function generates. If it is C<< <= 0 >>, then a suitable default	728	this function generates. If it is C<< <= 0 >>, then a suitable default
372	will be chosen (currently 6).	729	will be chosen (currently 4).
373		730
374	On error, the callback is called without arguments, otherwise it receives	731	On error, the callback is called without arguments, otherwise it receives
375	two array-refs with path-relative entry names.	732	two array-refs with path-relative entry names.
376		733
377	Example:	734	Example:
…		…
411	as those tend to return 0 or 1 as link counts, which disables the	768	as those tend to return 0 or 1 as link counts, which disables the
412	directory counting heuristic.	769	directory counting heuristic.
413		770
414	=cut	771	=cut
415		772
416	sub aio_scandir($$$) {	773	sub aio_scandir($$;$) {
		774	aio_block {
417	my ($path, $maxreq, $cb) = @_;	775	my ($path, $maxreq, $cb) = @_;
418		776
		777	my $pri = aioreq_pri;
		778
419	my $grp = aio_group $cb;	779	my $grp = aio_group $cb;
420		780
421	$maxreq = 6 if $maxreq <= 0;	781	$maxreq = 4 if $maxreq <= 0;
422		782
423	# stat once	783	# stat once
		784	aioreq_pri $pri;
424	add $grp aio_stat $path, sub {	785	add $grp aio_stat $path, sub {
425	return $grp->result () if $_[0];	786	return $grp->result () if $_[0];
426	my $now = time;	787	my $now = time;
427	my $hash1 = join ":", (stat _)[0,1,3,7,9];	788	my $hash1 = join ":", (stat _)[0,1,3,7,9];
428		789
429	# read the directory entries	790	# read the directory entries
		791	aioreq_pri $pri;
430	add $grp aio_readdir $path, sub {	792	add $grp aio_readdir $path, sub {
431	my $entries = shift	793	my $entries = shift
432	or return $grp->result ();	794	or return $grp->result ();
433		795
434	# stat the dir another time	796	# stat the dir another time
		797	aioreq_pri $pri;
435	add $grp aio_stat $path, sub {	798	add $grp aio_stat $path, sub {
436	my $hash2 = join ":", (stat _)[0,1,3,7,9];	799	my $hash2 = join ":", (stat _)[0,1,3,7,9];
437		800
438	my $ndirs;	801	my $ndirs;
439		802
440	# take the slow route if anything looks fishy	803	# take the slow route if anything looks fishy
441	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	804	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
442	$ndirs = -1;	805	$ndirs = -1;
443	} else {	806	} else {
444	# if nlink == 2, we are finished	807	# if nlink == 2, we are finished
445	# on non-posix-fs's, we rely on nlink < 2	808	# on non-posix-fs's, we rely on nlink < 2
446	$ndirs = (stat _)[3] - 2	809	$ndirs = (stat _)[3] - 2
447	or return $grp->result ([], $entries);	810	or return $grp->result ([], $entries);
448	}	811	}
449		812
450	# sort into likely dirs and likely nondirs	813	# sort into likely dirs and likely nondirs
451	# dirs == files without ".", short entries first	814	# dirs == files without ".", short entries first
452	$entries = [map $_->[0],	815	$entries = [map $_->[0],
453	sort { $b->[1] cmp $a->[1] }	816	sort { $b->[1] cmp $a->[1] }
454	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	817	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
455	@$entries];	818	@$entries];
456		819
457	my (@dirs, @nondirs);	820	my (@dirs, @nondirs);
458		821
459	my ($statcb, $schedcb);
460	my $nreq = 0;
461
462	my $statgrp = add $grp aio_group;	822	my $statgrp = add $grp aio_group sub {
463
464	$schedcb = sub {
465	if (@$entries) {
466	if ($nreq < $maxreq) {
467	my $ent = pop @$entries;
468	$nreq++;
469	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
470	}
471	} elsif (!$nreq) {
472	# finished
473	$statgrp->cancel;
474	undef $statcb;
475	undef $schedcb;
476	$grp->result (\@dirs, \@nondirs);	823	$grp->result (\@dirs, \@nondirs);
477	}	824	};
		825
		826	limit $statgrp $maxreq;
		827	feed $statgrp sub {
		828	return unless @$entries;
		829	my $entry = pop @$entries;
		830
		831	aioreq_pri $pri;
		832	add $statgrp aio_stat "$path/$entry/.", sub {
		833	if ($_[0] < 0) {
		834	push @nondirs, $entry;
		835	} else {
		836	# need to check for real directory
		837	aioreq_pri $pri;
		838	add $statgrp aio_lstat "$path/$entry", sub {
		839	if (-d _) {
		840	push @dirs, $entry;
		841
		842	unless (--$ndirs) {
		843	push @nondirs, @$entries;
		844	feed $statgrp;
		845	}
		846	} else {
		847	push @nondirs, $entry;
		848	}
		849	}
		850	}
		851	};
		852	};
478	};	853	};
479	$statcb = sub {
480	my ($status, $entry) = @_;
481
482	if ($status < 0) {
483	$nreq--;
484	push @nondirs, $entry;
485	&$schedcb;
486	} else {
487	# need to check for real directory
488	add $grp aio_lstat "$path/$entry", sub {
489	$nreq--;
490
491	if (-d _) {
492	push @dirs, $entry;
493
494	if (!--$ndirs) {
495	push @nondirs, @$entries;
496	$entries = [];
497	}
498	} else {
499	push @nondirs, $entry;
500	}
501
502	&$schedcb;
503	}
504	}
505	};
506
507	&$schedcb while @$entries && $nreq < $maxreq;
508	};	854	};
509	};	855	};
		856
		857	$grp
510	};	858	}
511
512	$grp
513	}	859	}
		860
		861	=item aio_rmtree $path, $callback->($status)
		862
		863	Delete a directory tree starting (and including) C<$path>, return the
		864	status of the final C<rmdir> only. This is a composite request that
		865	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		866	everything else.
		867
		868	=cut
		869
		870	sub aio_rmtree;
		871	sub aio_rmtree($;$) {
		872	aio_block {
		873	my ($path, $cb) = @_;
		874
		875	my $pri = aioreq_pri;
		876	my $grp = aio_group $cb;
		877
		878	aioreq_pri $pri;
		879	add $grp aio_scandir $path, 0, sub {
		880	my ($dirs, $nondirs) = @_;
		881
		882	my $dirgrp = aio_group sub {
		883	add $grp aio_rmdir $path, sub {
		884	$grp->result ($_[0]);
		885	};
		886	};
		887
		888	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		889	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		890
		891	add $grp $dirgrp;
		892	};
		893
		894	$grp
		895	}
		896	}
		897
		898	=item aio_sync $callback->($status)
		899
		900	Asynchronously call sync and call the callback when finished.
514		901
515	=item aio_fsync $fh, $callback->($status)	902	=item aio_fsync $fh, $callback->($status)
516		903
517	Asynchronously call fsync on the given filehandle and call the callback	904	Asynchronously call fsync on the given filehandle and call the callback
518	with the fsync result code.	905	with the fsync result code.
…		…
525	If this call isn't available because your OS lacks it or it couldn't be	912	If this call isn't available because your OS lacks it or it couldn't be
526	detected, it will be emulated by calling C<fsync> instead.	913	detected, it will be emulated by calling C<fsync> instead.
527		914
528	=item aio_group $callback->(...)	915	=item aio_group $callback->(...)
529		916
530	[EXPERIMENTAL]
531
532	This is a very special aio request: Instead of doing something, it is a	917	This is a very special aio request: Instead of doing something, it is a
533	container for other aio requests, which is useful if you want to bundle	918	container for other aio requests, which is useful if you want to bundle
534	many requests into a single, composite, request.	919	many requests into a single, composite, request with a definite callback
		920	and the ability to cancel the whole request with its subrequests.
535		921
536	Returns an object of class L<IO::AIO::GRP>. See its documentation below	922	Returns an object of class L<IO::AIO::GRP>. See its documentation below
537	for more info.	923	for more info.
538		924
539	Example:	925	Example:
…		…
558	phase and still requires a worker thread. Thus, the callback will not	944	phase and still requires a worker thread. Thus, the callback will not
559	be executed immediately but only after other requests in the queue have	945	be executed immediately but only after other requests in the queue have
560	entered their execution phase. This can be used to measure request	946	entered their execution phase. This can be used to measure request
561	latency.	947	latency.
562		948
563	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	949	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
564		950
565	Mainly used for debugging and benchmarking, this aio request puts one of	951	Mainly used for debugging and benchmarking, this aio request puts one of
566	the request workers to sleep for the given time.	952	the request workers to sleep for the given time.
567		953
568	While it is theoretically handy to have simple I/O scheduling requests	954	While it is theoretically handy to have simple I/O scheduling requests
569	like sleep and file handle readable/writable, the overhead this creates	955	like sleep and file handle readable/writable, the overhead this creates is
570	is immense, so do not use this function except to put your application	956	immense (it blocks a thread for a long time) so do not use this function
571	under artificial I/O pressure.	957	except to put your application under artificial I/O pressure.
572		958
573	=back	959	=back
574		960
575	=head2 IO::AIO::REQ CLASS	961	=head2 IO::AIO::REQ CLASS
576		962
577	All non-aggregate C<aio_*> functions return an object of this class when	963	All non-aggregate C<aio_*> functions return an object of this class when
578	called in non-void context.	964	called in non-void context.
579
580	A request always moves through the following five states in its lifetime,
581	in order: B<ready> (request has been created, but has not been executed
582	yet), B<execute> (request is currently being executed), B<pending>
583	(request has been executed but callback has not been called yet),
584	B<result> (results are being processed synchronously, includes calling the
585	callback) and B<done> (request has reached the end of its lifetime and
586	holds no resources anymore).
587		965
588	=over 4	966	=over 4
589		967
590	=item cancel $req	968	=item cancel $req
591		969
…		…
645	=item * They can also can also be added to other IO::AIO::GRP objects.	1023	=item * They can also can also be added to other IO::AIO::GRP objects.
646		1024
647	=item * You must not add requests to a group from within the group callback (or	1025	=item * You must not add requests to a group from within the group callback (or
648	any later time).	1026	any later time).
649		1027
650	=item * This does not harmonise well with C<max_outstanding>, so best do
651	not combine C<aio_group> with it. Groups and feeders are recommended for
652	this kind of concurrency-limiting.
653
654	=back	1028	=back
655		1029
656	Their lifetime, simplified, looks like this: when they are empty, they	1030	Their lifetime, simplified, looks like this: when they are empty, they
657	will finish very quickly. If they contain only requests that are in the	1031	will finish very quickly. If they contain only requests that are in the
658	C<done> state, they will also finish. Otherwise they will continue to	1032	C<done> state, they will also finish. Otherwise they will continue to
…		…
673	be added, including other groups, as long as you do not create circular	1047	be added, including other groups, as long as you do not create circular
674	dependencies.	1048	dependencies.
675		1049
676	Returns all its arguments.	1050	Returns all its arguments.
677		1051
		1052	=item $grp->cancel_subs
		1053
		1054	Cancel all subrequests and clears any feeder, but not the group request
		1055	itself. Useful when you queued a lot of events but got a result early.
		1056
678	=item $grp->result (...)	1057	=item $grp->result (...)
679		1058
680	Set the result value(s) that will be passed to the group callback when all	1059	Set the result value(s) that will be passed to the group callback when all
681	subrequests have finished. By default, no argument will be passed.	1060	subrequests have finished and set thre groups errno to the current value
		1061	of errno (just like calling C<errno> without an error number). By default,
		1062	no argument will be passed and errno is zero.
		1063
		1064	=item $grp->errno ([$errno])
		1065
		1066	Sets the group errno value to C<$errno>, or the current value of errno
		1067	when the argument is missing.
		1068
		1069	Every aio request has an associated errno value that is restored when
		1070	the callback is invoked. This method lets you change this value from its
		1071	default (0).
		1072
		1073	Calling C<result> will also set errno, so make sure you either set C<$!>
		1074	before the call to C<result>, or call c<errno> after it.
682		1075
683	=item feed $grp $callback->($grp)	1076	=item feed $grp $callback->($grp)
684
685	[VERY EXPERIMENTAL]
686		1077
687	Sets a feeder/generator on this group: every group can have an attached	1078	Sets a feeder/generator on this group: every group can have an attached
688	generator that generates requests if idle. The idea behind this is that,	1079	generator that generates requests if idle. The idea behind this is that,
689	although you could just queue as many requests as you want in a group,	1080	although you could just queue as many requests as you want in a group,
690	this might starve other requests for a potentially long time. For	1081	this might starve other requests for a potentially long time. For
…		…
727		1118
728	=back	1119	=back
729		1120
730	=head2 SUPPORT FUNCTIONS	1121	=head2 SUPPORT FUNCTIONS
731		1122
		1123	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1124
732	=over 4	1125	=over 4
733		1126
734	=item $fileno = IO::AIO::poll_fileno	1127	=item $fileno = IO::AIO::poll_fileno
735		1128
736	Return the I<request result pipe file descriptor>. This filehandle must be	1129	Return the I<request result pipe file descriptor>. This filehandle must be
…		…
740		1133
741	See C<poll_cb> for an example.	1134	See C<poll_cb> for an example.
742		1135
743	=item IO::AIO::poll_cb	1136	=item IO::AIO::poll_cb
744		1137
745	Process all outstanding events on the result pipe. You have to call this	1138	Process some outstanding events on the result pipe. You have to call this
746	regularly. Returns the number of events processed. Returns immediately	1139	regularly. Returns the number of events processed. Returns immediately
747	when no events are outstanding.	1140	when no events are outstanding. The amount of events processed depends on
		1141	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1142
		1143	If not all requests were processed for whatever reason, the filehandle
		1144	will still be ready when C<poll_cb> returns.
748		1145
749	Example: Install an Event watcher that automatically calls	1146	Example: Install an Event watcher that automatically calls
750	IO::AIO::poll_cb with high priority:	1147	IO::AIO::poll_cb with high priority:
751		1148
752	Event->io (fd => IO::AIO::poll_fileno,	1149	Event->io (fd => IO::AIO::poll_fileno,
753	poll => 'r', async => 1,	1150	poll => 'r', async => 1,
754	cb => \&IO::AIO::poll_cb);	1151	cb => \&IO::AIO::poll_cb);
755		1152
		1153	=item IO::AIO::max_poll_reqs $nreqs
		1154
		1155	=item IO::AIO::max_poll_time $seconds
		1156
		1157	These set the maximum number of requests (default C<0>, meaning infinity)
		1158	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1159	the maximum amount of time (default C<0>, meaning infinity) spent in
		1160	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1161	of time C<poll_cb> is allowed to use).
		1162
		1163	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1164	syscall per request processed, which is not normally a problem unless your
		1165	callbacks are really really fast or your OS is really really slow (I am
		1166	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1167
		1168	Setting these is useful if you want to ensure some level of
		1169	interactiveness when perl is not fast enough to process all requests in
		1170	time.
		1171
		1172	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1173
		1174	Example: Install an Event watcher that automatically calls
		1175	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1176	program get the CPU sometimes even under high AIO load.
		1177
		1178	# try not to spend much more than 0.1s in poll_cb
		1179	IO::AIO::max_poll_time 0.1;
		1180
		1181	# use a low priority so other tasks have priority
		1182	Event->io (fd => IO::AIO::poll_fileno,
		1183	poll => 'r', nice => 1,
		1184	cb => &IO::AIO::poll_cb);
		1185
756	=item IO::AIO::poll_wait	1186	=item IO::AIO::poll_wait
757		1187
		1188	If there are any outstanding requests and none of them in the result
758	Wait till the result filehandle becomes ready for reading (simply does a	1189	phase, wait till the result filehandle becomes ready for reading (simply
759	C<select> on the filehandle. This is useful if you want to synchronously wait	1190	does a C<select> on the filehandle. This is useful if you want to
760	for some requests to finish).	1191	synchronously wait for some requests to finish).
761		1192
762	See C<nreqs> for an example.	1193	See C<nreqs> for an example.
763		1194
		1195	=item IO::AIO::poll
		1196
		1197	Waits until some requests have been handled.
		1198
		1199	Returns the number of requests processed, but is otherwise strictly
		1200	equivalent to:
		1201
		1202	IO::AIO::poll_wait, IO::AIO::poll_cb
		1203
764	=item IO::AIO::nreqs	1204	=item IO::AIO::flush
765		1205
766	Returns the number of requests currently outstanding (i.e. for which their	1206	Wait till all outstanding AIO requests have been handled.
767	callback has not been invoked yet).
768		1207
769	Example: wait till there are no outstanding requests anymore:	1208	Strictly equivalent to:
770		1209
771	IO::AIO::poll_wait, IO::AIO::poll_cb	1210	IO::AIO::poll_wait, IO::AIO::poll_cb
772	while IO::AIO::nreqs;	1211	while IO::AIO::nreqs;
773		1212
774	=item IO::AIO::flush	1213	=back
775		1214
776	Wait till all outstanding AIO requests have been handled.	1215	=head3 CONTROLLING THE NUMBER OF THREADS
777		1216
778	Strictly equivalent to:	1217	=over
779
780	IO::AIO::poll_wait, IO::AIO::poll_cb
781	while IO::AIO::nreqs;
782
783	=item IO::AIO::poll
784
785	Waits until some requests have been handled.
786
787	Strictly equivalent to:
788
789	IO::AIO::poll_wait, IO::AIO::poll_cb
790	if IO::AIO::nreqs;
791		1218
792	=item IO::AIO::min_parallel $nthreads	1219	=item IO::AIO::min_parallel $nthreads
793		1220
794	Set the minimum number of AIO threads to C<$nthreads>. The current	1221	Set the minimum number of AIO threads to C<$nthreads>. The current
795	default is C<8>, which means eight asynchronous operations can execute	1222	default is C<8>, which means eight asynchronous operations can execute
796	concurrently at any one time (the number of outstanding requests,	1223	concurrently at any one time (the number of outstanding requests,
797	however, is unlimited).	1224	however, is unlimited).
798		1225
799	IO::AIO starts threads only on demand, when an AIO request is queued and	1226	IO::AIO starts threads only on demand, when an AIO request is queued and
800	no free thread exists.	1227	no free thread exists. Please note that queueing up a hundred requests can
		1228	create demand for a hundred threads, even if it turns out that everything
		1229	is in the cache and could have been processed faster by a single thread.
801		1230
802	It is recommended to keep the number of threads relatively low, as some	1231	It is recommended to keep the number of threads relatively low, as some
803	Linux kernel versions will scale negatively with the number of threads	1232	Linux kernel versions will scale negatively with the number of threads
804	(higher parallelity => MUCH higher latency). With current Linux 2.6	1233	(higher parallelity => MUCH higher latency). With current Linux 2.6
805	versions, 4-32 threads should be fine.	1234	versions, 4-32 threads should be fine.
…		…
819	This module automatically runs C<max_parallel 0> at program end, to ensure	1248	This module automatically runs C<max_parallel 0> at program end, to ensure
820	that all threads are killed and that there are no outstanding requests.	1249	that all threads are killed and that there are no outstanding requests.
821		1250
822	Under normal circumstances you don't need to call this function.	1251	Under normal circumstances you don't need to call this function.
823		1252
		1253	=item IO::AIO::max_idle $nthreads
		1254
		1255	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1256	threads that did not get a request to process within 10 seconds). That
		1257	means if a thread becomes idle while C<$nthreads> other threads are also
		1258	idle, it will free its resources and exit.
		1259
		1260	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1261	to allow for extremely high load situations, but want to free resources
		1262	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1263
		1264	The default is probably ok in most situations, especially if thread
		1265	creation is fast. If thread creation is very slow on your system you might
		1266	want to use larger values.
		1267
824	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1268	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
825		1269
826	[DEPRECATED]	1270	This is a very bad function to use in interactive programs because it
		1271	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1272	use an C<aio_group> together with a feed callback.
827		1273
828	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1274	Sets the maximum number of outstanding requests to C<$nreqs>. If you
829	try to queue up more than this number of requests, the caller will block until	1275	do queue up more than this number of requests, the next call to the
830	some requests have been handled.	1276	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1277	function will block until the limit is no longer exceeded.
831		1278
832	The default is very large, so normally there is no practical limit. If you	1279	The default value is very large, so there is no practical limit on the
833	queue up many requests in a loop it often improves speed if you set	1280	number of outstanding requests.
834	this to a relatively low number, such as C<100>.
835		1281
836	This function does not work well together with C<aio_group>'s, and their	1282	You can still queue as many requests as you want. Therefore,
837	feeder interface is better suited to limiting concurrency, so do not use	1283	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
838	this function.	1284	as a stop gap to shield against fatal memory overflow (with large values).
839
840	Under normal circumstances you don't need to call this function.
841		1285
842	=back	1286	=back
843		1287
		1288	=head3 STATISTICAL INFORMATION
		1289
		1290	=over
		1291
		1292	=item IO::AIO::nreqs
		1293
		1294	Returns the number of requests currently in the ready, execute or pending
		1295	states (i.e. for which their callback has not been invoked yet).
		1296
		1297	Example: wait till there are no outstanding requests anymore:
		1298
		1299	IO::AIO::poll_wait, IO::AIO::poll_cb
		1300	while IO::AIO::nreqs;
		1301
		1302	=item IO::AIO::nready
		1303
		1304	Returns the number of requests currently in the ready state (not yet
		1305	executed).
		1306
		1307	=item IO::AIO::npending
		1308
		1309	Returns the number of requests currently in the pending state (executed,
		1310	but not yet processed by poll_cb).
		1311
		1312	=back
		1313
844	=cut	1314	=cut
845		1315
846	# support function to convert a fd into a perl filehandle
847	sub _fd2fh {
848	return undef if $_[0] < 0;
849
850	# try to generate nice filehandles
851	my $sym = "IO::AIO::fd#$_[0]";
852	local *$sym;
853
854	open *$sym, "+<&=$_[0]" # usually works under any unix
855	or open *$sym, "<&=$_[0]" # cygwin needs this
856	or open *$sym, ">&=$_[0]" # or this
857	or return undef;
858
859	*$sym
860	}
861
862	min_parallel 8;	1316	min_parallel 8;
863		1317
864	END {	1318	END { flush }
865	max_parallel 0;
866	}
867		1319
868	1;	1320	1;
869		1321
870	=head2 FORK BEHAVIOUR	1322	=head2 FORK BEHAVIOUR
871		1323
872	This module should do "the right thing" when the process using it forks:	1324	This module should do "the right thing" when the process using it forks:
873		1325
874	Before the fork, IO::AIO enters a quiescent state where no requests	1326	Before the fork, IO::AIO enters a quiescent state where no requests
875	can be added in other threads and no results will be processed. After	1327	can be added in other threads and no results will be processed. After
876	the fork the parent simply leaves the quiescent state and continues	1328	the fork the parent simply leaves the quiescent state and continues
877	request/result processing, while the child clears the request/result	1329	request/result processing, while the child frees the request/result queue
878	queue (so the requests started before the fork will only be handled in	1330	(so that the requests started before the fork will only be handled in the
879	the parent). Threads will be started on demand until the limit ste in the	1331	parent). Threads will be started on demand until the limit set in the
880	parent process has been reached again.	1332	parent process has been reached again.
881		1333
882	In short: the parent will, after a short pause, continue as if fork had	1334	In short: the parent will, after a short pause, continue as if fork had
883	not been called, while the child will act as if IO::AIO has not been used	1335	not been called, while the child will act as if IO::AIO has not been used
884	yet.	1336	yet.
885		1337
886	=head2 MEMORY USAGE	1338	=head2 MEMORY USAGE
887		1339
		1340	Per-request usage:
		1341
888	Each aio request uses - depending on your architecture - around 128 bytes	1342	Each aio request uses - depending on your architecture - around 100-200
889	of memory. In addition, stat requests need a stat buffer (possibly a few	1343	bytes of memory. In addition, stat requests need a stat buffer (possibly
890	hundred bytes). Perl scalars and other data passed into aio requests will	1344	a few hundred bytes), readdir requires a result buffer and so on. Perl
891	also be locked.	1345	scalars and other data passed into aio requests will also be locked and
		1346	will consume memory till the request has entered the done state.
892		1347
893	This is now awfully much, so queuing lots of requests is not usually a	1348	This is not awfully much, so queuing lots of requests is not usually a
894	problem.	1349	problem.
895		1350
896	Each thread needs a stack area which is usually around 16k, sometimes much	1351	Per-thread usage:
897	larger, depending on the OS.	1352
		1353	In the execution phase, some aio requests require more memory for
		1354	temporary buffers, and each thread requires a stack and other data
		1355	structures (usually around 16k-128k, depending on the OS).
		1356
		1357	=head1 KNOWN BUGS
		1358
		1359	Known bugs will be fixed in the next release.
898		1360
899	=head1 SEE ALSO	1361	=head1 SEE ALSO
900		1362
901	L<Coro::AIO>.	1363	L<Coro::AIO>.
902		1364

Diff Legend

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

Comparing IO-AIO/AIO.pm (file contents): Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs. Revision 1.119 by root, Sun Dec 2 20:54:33 2007 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs.
Revision 1.119 by root, Sun Dec 2 20:54:33 2007 UTC