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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs.
Revision 1.145 by root, Sun Apr 19 19:20:10 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
…		…
18	};	19	};
19		20
20	# version 2+ has request and group objects	21	# version 2+ has request and group objects
21	use IO::AIO 2;	22	use IO::AIO 2;
22		23
		24	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
25		27
26	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
28		30
		31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		32	use AnyEvent::AIO;
		33
29	# AnyEvent integration	34	# EV integration
30	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	35	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
31	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
32		36
33	# Event integration	37	# Event integration
34	Event->io (fd => IO::AIO::poll_fileno,	38	Event->io (fd => IO::AIO::poll_fileno,
35	poll => 'r',	39	poll => 'r',
36	cb => \&IO::AIO::poll_cb);	40	cb => \&IO::AIO::poll_cb);
…		…
50	=head1 DESCRIPTION	54	=head1 DESCRIPTION
51		55
52	This module implements asynchronous I/O using whatever means your	56	This module implements asynchronous I/O using whatever means your
53	operating system supports.	57	operating system supports.
54		58
		59	Asynchronous means that operations that can normally block your program
		60	(e.g. reading from disk) will be done asynchronously: the operation
		61	will still block, but you can do something else in the meantime. This
		62	is extremely useful for programs that need to stay interactive even
		63	when doing heavy I/O (GUI programs, high performance network servers
		64	etc.), but can also be used to easily do operations in parallel that are
		65	normally done sequentially, e.g. stat'ing many files, which is much faster
		66	on a RAID volume or over NFS when you do a number of stat operations
		67	concurrently.
		68
		69	While most of this works on all types of file descriptors (for
		70	example sockets), using these functions on file descriptors that
		71	support nonblocking operation (again, sockets, pipes etc.) is very
		72	inefficient. Use an event loop for that (such as the L<Event\|Event>
		73	module): IO::AIO will naturally fit into such an event loop itself.
		74
55	Currently, a number of threads are started that execute your read/writes	75	In this version, a number of threads are started that execute your
56	and signal their completion. You don't need thread support in perl, and	76	requests and signal their completion. You don't need thread support
57	the threads created by this module will not be visible to perl. In the	77	in perl, and the threads created by this module will not be visible
58	future, this module might make use of the native aio functions available	78	to perl. In the future, this module might make use of the native aio
59	on many operating systems. However, they are often not well-supported	79	functions available on many operating systems. However, they are often
60	(Linux doesn't allow them on normal files currently, for example),	80	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	and they would only support aio_read and aio_write, so the remaining	81	files currently, for example), and they would only support aio_read and
62	functionality would have to be implemented using threads anyway.	82	aio_write, so the remaining functionality would have to be implemented
		83	using threads anyway.
63		84
64	Although the module will work with in the presence of other threads, it is	85	Although the module will work in the presence of other (Perl-) threads,
65	currently not reentrant, so use appropriate locking yourself, always call	86	it is currently not reentrant in any way, so use appropriate locking
66	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	87	yourself, always call C<poll_cb> from within the same thread, or never
67	C<aio_> functions) recursively.	88	call C<poll_cb> (or other C<aio_> functions) recursively.
		89
		90	=head2 EXAMPLE
		91
		92	This is a simple example that uses the Event module and loads
		93	F</etc/passwd> asynchronously:
		94
		95	use Fcntl;
		96	use Event;
		97	use IO::AIO;
		98
		99	# register the IO::AIO callback with Event
		100	Event->io (fd => IO::AIO::poll_fileno,
		101	poll => 'r',
		102	cb => \&IO::AIO::poll_cb);
		103
		104	# queue the request to open /etc/passwd
		105	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		106	my $fh = shift
		107	or die "error while opening: $!";
		108
		109	# stat'ing filehandles is generally non-blocking
		110	my $size = -s $fh;
		111
		112	# queue a request to read the file
		113	my $contents;
		114	aio_read $fh, 0, $size, $contents, 0, sub {
		115	$_[0] == $size
		116	or die "short read: $!";
		117
		118	close $fh;
		119
		120	# file contents now in $contents
		121	print $contents;
		122
		123	# exit event loop and program
		124	Event::unloop;
		125	};
		126	};
		127
		128	# possibly queue up other requests, or open GUI windows,
		129	# check for sockets etc. etc.
		130
		131	# process events as long as there are some:
		132	Event::loop;
		133
		134	=head1 REQUEST ANATOMY AND LIFETIME
		135
		136	Every C<aio_*> function creates a request. which is a C data structure not
		137	directly visible to Perl.
		138
		139	If called in non-void context, every request function returns a Perl
		140	object representing the request. In void context, nothing is returned,
		141	which saves a bit of memory.
		142
		143	The perl object is a fairly standard ref-to-hash object. The hash contents
		144	are not used by IO::AIO so you are free to store anything you like in it.
		145
		146	During their existance, aio requests travel through the following states,
		147	in order:
		148
		149	=over 4
		150
		151	=item ready
		152
		153	Immediately after a request is created it is put into the ready state,
		154	waiting for a thread to execute it.
		155
		156	=item execute
		157
		158	A thread has accepted the request for processing and is currently
		159	executing it (e.g. blocking in read).
		160
		161	=item pending
		162
		163	The request has been executed and is waiting for result processing.
		164
		165	While request submission and execution is fully asynchronous, result
		166	processing is not and relies on the perl interpreter calling C<poll_cb>
		167	(or another function with the same effect).
		168
		169	=item result
		170
		171	The request results are processed synchronously by C<poll_cb>.
		172
		173	The C<poll_cb> function will process all outstanding aio requests by
		174	calling their callbacks, freeing memory associated with them and managing
		175	any groups they are contained in.
		176
		177	=item done
		178
		179	Request has reached the end of its lifetime and holds no resources anymore
		180	(except possibly for the Perl object, but its connection to the actual
		181	aio request is severed and calling its methods will either do nothing or
		182	result in a runtime error).
		183
		184	=back
68		185
69	=cut	186	=cut
70		187
71	package IO::AIO;	188	package IO::AIO;
		189
		190	use Carp ();
72		191
73	no warnings;	192	no warnings;
74	use strict 'vars';	193	use strict 'vars';
75		194
76	use base 'Exporter';	195	use base 'Exporter';
77		196
78	BEGIN {	197	BEGIN {
79	our $VERSION = '2.0';	198	our $VERSION = '3.18';
80		199
81	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	200	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
82	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	201	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir
83	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	202	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
84	aio_group aio_nop);	203	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		204	aio_rename aio_link aio_move aio_copy aio_group
		205	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		206	aio_chmod aio_utime aio_truncate);
		207
85	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	208	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
86	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	209	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
87	min_parallel max_parallel max_outstanding nreqs);	210	min_parallel max_parallel max_idle
		211	nreqs nready npending nthreads
		212	max_poll_time max_poll_reqs);
		213
		214	push @AIO_REQ, qw(aio_busy); # not exported
88		215
89	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
90		217
91	require XSLoader;	218	require XSLoader;
92	XSLoader::load ("IO::AIO", $VERSION);	219	XSLoader::load ("IO::AIO", $VERSION);
93	}	220	}
94		221
95	=head1 FUNCTIONS	222	=head1 FUNCTIONS
96		223
97	=head2 AIO FUNCTIONS	224	=head2 AIO REQUEST FUNCTIONS
98		225
99	All the C<aio_*> calls are more or less thin wrappers around the syscall	226	All the C<aio_*> calls are more or less thin wrappers around the syscall
100	with the same name (sans C<aio_>). The arguments are similar or identical,	227	with the same name (sans C<aio_>). The arguments are similar or identical,
101	and they all accept an additional (and optional) C<$callback> argument	228	and they all accept an additional (and optional) C<$callback> argument
102	which must be a code reference. This code reference will get called with	229	which must be a code reference. This code reference will get called with
103	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	230	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
104	perl, which usually delivers "false") as it's sole argument when the given	231	perl, which usually delivers "false") as its sole argument after the given
105	syscall has been executed asynchronously.	232	syscall has been executed asynchronously.
106		233
107	All functions expecting a filehandle keep a copy of the filehandle	234	All functions expecting a filehandle keep a copy of the filehandle
108	internally until the request has finished.	235	internally until the request has finished.
109		236
110	All requests return objects of type L<IO::AIO::REQ> that allow further	237	All functions return request objects of type L<IO::AIO::REQ> that allow
111	manipulation of those requests while they are in-flight.	238	further manipulation of those requests while they are in-flight.
112		239
113	The pathnames you pass to these routines I<must> be absolute and	240	The pathnames you pass to these routines I<must> be absolute and
114	encoded in byte form. The reason for the former is that at the time the	241	encoded as octets. The reason for the former is that at the time the
115	request is being executed, the current working directory could have	242	request is being executed, the current working directory could have
116	changed. Alternatively, you can make sure that you never change the	243	changed. Alternatively, you can make sure that you never change the
117	current working directory.	244	current working directory anywhere in the program and then use relative
		245	paths.
118		246
119	To encode pathnames to byte form, either make sure you either: a)	247	To encode pathnames as octets, either make sure you either: a) always pass
120	always pass in filenames you got from outside (command line, readdir	248	in filenames you got from outside (command line, readdir etc.) without
121	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	249	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
122	your pathnames to the locale (or other) encoding in effect in the user	250	your pathnames to the locale (or other) encoding in effect in the user
123	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	251	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
124	use something else.	252	use something else to ensure your scalar has the correct contents.
		253
		254	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		255	handles correctly whether it is set or not.
125		256
126	=over 4	257	=over 4
		258
		259	=item $prev_pri = aioreq_pri [$pri]
		260
		261	Returns the priority value that would be used for the next request and, if
		262	C<$pri> is given, sets the priority for the next aio request.
		263
		264	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		265	and C<4>, respectively. Requests with higher priority will be serviced
		266	first.
		267
		268	The priority will be reset to C<0> after each call to one of the C<aio_*>
		269	functions.
		270
		271	Example: open a file with low priority, then read something from it with
		272	higher priority so the read request is serviced before other low priority
		273	open requests (potentially spamming the cache):
		274
		275	aioreq_pri -3;
		276	aio_open ..., sub {
		277	return unless $_[0];
		278
		279	aioreq_pri -2;
		280	aio_read $_[0], ..., sub {
		281	...
		282	};
		283	};
		284
		285
		286	=item aioreq_nice $pri_adjust
		287
		288	Similar to C<aioreq_pri>, but subtracts the given value from the current
		289	priority, so the effect is cumulative.
		290
127		291
128	=item aio_open $pathname, $flags, $mode, $callback->($fh)	292	=item aio_open $pathname, $flags, $mode, $callback->($fh)
129		293
130	Asynchronously open or create a file and call the callback with a newly	294	Asynchronously open or create a file and call the callback with a newly
131	created filehandle for the file.	295	created filehandle for the file.
…		…
137	list. They are the same as used by C<sysopen>.	301	list. They are the same as used by C<sysopen>.
138		302
139	Likewise, C<$mode> specifies the mode of the newly created file, if it	303	Likewise, C<$mode> specifies the mode of the newly created file, if it
140	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	304	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
141	except that it is mandatory (i.e. use C<0> if you don't create new files,	305	except that it is mandatory (i.e. use C<0> if you don't create new files,
142	and C<0666> or C<0777> if you do).	306	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		307	by the umask in effect then the request is being executed, so better never
		308	change the umask.
143		309
144	Example:	310	Example:
145		311
146	aio_open "/etc/passwd", O_RDONLY, 0, sub {	312	aio_open "/etc/passwd", O_RDONLY, 0, sub {
147	if ($_[0]) {	313	if ($_[0]) {
…		…
150	} else {	316	} else {
151	die "open failed: $!\n";	317	die "open failed: $!\n";
152	}	318	}
153	};	319	};
154		320
		321
155	=item aio_close $fh, $callback->($status)	322	=item aio_close $fh, $callback->($status)
156		323
157	Asynchronously close a file and call the callback with the result	324	Asynchronously close a file and call the callback with the result
158	code. I<WARNING:> although accepted, you should not pass in a perl	325	code.
159	filehandle here, as perl will likely close the file descriptor another
160	time when the filehandle is destroyed. Normally, you can safely call perls
161	C<close> or just let filehandles go out of scope.
162		326
163	This is supposed to be a bug in the API, so that might change. It's	327	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
164	therefore best to avoid this function.	328	closing the file descriptor associated with the filehandle itself.
		329
		330	Therefore, C<aio_close> will not close the filehandle - instead it will
		331	use dup2 to overwrite the file descriptor with the write-end of a pipe
		332	(the pipe fd will be created on demand and will be cached).
		333
		334	Or in other words: the file descriptor will be closed, but it will not be
		335	free for reuse until the perl filehandle is closed.
		336
		337	=cut
165		338
166	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
167		340
168	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
169		342
170	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	343	Reads or writes C<$length> bytes from or to the specified C<$fh> and
171	into the scalar given by C<data> and offset C<dataoffset> and calls the	344	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
172	callback without the actual number of bytes read (or -1 on error, just	345	and calls the callback without the actual number of bytes read (or -1 on
173	like the syscall).	346	error, just like the syscall).
		347
		348	If C<$offset> is undefined, then the current file descriptor offset will
		349	be used (and updated), otherwise the file descriptor offset will not be
		350	changed by these calls.
		351
		352	If C<$length> is undefined in C<aio_write>, use the remaining length of
		353	C<$data>.
		354
		355	If C<$dataoffset> is less than zero, it will be counted from the end of
		356	C<$data>.
174		357
175	The C<$data> scalar I<MUST NOT> be modified in any way while the request	358	The C<$data> scalar I<MUST NOT> be modified in any way while the request
176	is outstanding. Modifying it can result in segfaults or WW3 (if the	359	is outstanding. Modifying it can result in segfaults or World War III (if
177	necessary/optional hardware is installed).	360	the necessary/optional hardware is installed).
178		361
179	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	362	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
180	offset C<0> within the scalar:	363	offset C<0> within the scalar:
181		364
182	aio_read $fh, 7, 15, $buffer, 0, sub {	365	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] > 0 or die "read error: $!";	366	$_[0] > 0 or die "read error: $!";
184	print "read $_[0] bytes: <$buffer>\n";	367	print "read $_[0] bytes: <$buffer>\n";
185	};	368	};
186		369
187	=item aio_move $srcpath, $dstpath, $callback->($status)
188
189	[EXPERIMENTAL due to internal aio_group use]
190
191	Try to move the I<file> (directories not supported as either source or
192	destination) from C<$srcpath> to C<$dstpath> and call the callback with
193	the C<0> (error) or C<-1> ok.
194
195	This is a composite request that tries to rename(2) the file first. If
196	rename files with C<EXDEV>, it creates the destination file with mode 0200
197	and copies the contents of the source file into it using C<aio_sendfile>,
198	followed by restoring atime, mtime, access mode and uid/gid, in that
199	order, and unlinking the C<$srcpath>.
200
201	If an error occurs, the partial destination file will be unlinked, if
202	possible, except when setting atime, mtime, access mode and uid/gid, where
203	errors are being ignored.
204
205	=cut
206
207	sub aio_move($$$) {
208	my ($src, $dst, $cb) = @_;
209
210	my $grp = aio_group $cb;
211
212	add $grp aio_rename $src, $dst, sub {
213	if ($_[0] && $! == EXDEV) {
214	add $grp aio_open $src, O_RDONLY, 0, sub {
215	if (my $src_fh = $_[0]) {
216	my @stat = stat $src_fh;
217
218	add $grp aio_open $dst, O_WRONLY, 0200, sub {
219	if (my $dst_fh = $_[0]) {
220	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
221	close $src_fh;
222
223	if ($_[0] == $stat[7]) {
224	utime $stat[8], $stat[9], $dst;
225	chmod $stat[2] & 07777, $dst_fh;
226	chown $stat[4], $stat[5], $dst_fh;
227	close $dst_fh;
228
229	add $grp aio_unlink $src, sub {
230	$grp->result ($_[0]);
231	};
232	} else {
233	my $errno = $!;
234	add $grp aio_unlink $dst, sub {
235	$! = $errno;
236	$grp->result (-1);
237	};
238	}
239	};
240	} else {
241	$grp->result (-1);
242	}
243	},
244
245	} else {
246	$grp->result (-1);
247	}
248	};
249	} else {
250	$grp->result ($_[0]);
251	}
252	};
253
254	$grp
255	}
256		370
257	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	371	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
258		372
259	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	373	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
260	reading at byte offset C<$in_offset>, and starts writing at the current	374	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
274	C<$in_fh> than are written, and there is no way to find out how many	388	C<$in_fh> than are written, and there is no way to find out how many
275	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	389	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
276	provides the number of bytes written to C<$out_fh>. Only if the result	390	provides the number of bytes written to C<$out_fh>. Only if the result
277	value equals C<$length> one can assume that C<$length> bytes have been	391	value equals C<$length> one can assume that C<$length> bytes have been
278	read.	392	read.
		393
279		394
280	=item aio_readahead $fh,$offset,$length, $callback->($retval)	395	=item aio_readahead $fh,$offset,$length, $callback->($retval)
281		396
282	C<aio_readahead> populates the page cache with data from a file so that	397	C<aio_readahead> populates the page cache with data from a file so that
283	subsequent reads from that file will not block on disk I/O. The C<$offset>	398	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
289	file. The current file offset of the file is left unchanged.	404	file. The current file offset of the file is left unchanged.
290		405
291	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	406	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
292	emulated by simply reading the data, which would have a similar effect.	407	emulated by simply reading the data, which would have a similar effect.
293		408
		409
294	=item aio_stat $fh_or_path, $callback->($status)	410	=item aio_stat $fh_or_path, $callback->($status)
295		411
296	=item aio_lstat $fh, $callback->($status)	412	=item aio_lstat $fh, $callback->($status)
297		413
298	Works like perl's C<stat> or C<lstat> in void context. The callback will	414	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
311	aio_stat "/etc/passwd", sub {	427	aio_stat "/etc/passwd", sub {
312	$_[0] and die "stat failed: $!";	428	$_[0] and die "stat failed: $!";
313	print "size is ", -s _, "\n";	429	print "size is ", -s _, "\n";
314	};	430	};
315		431
		432
		433	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		434
		435	Works like perl's C<utime> function (including the special case of $atime
		436	and $mtime being undef). Fractional times are supported if the underlying
		437	syscalls support them.
		438
		439	When called with a pathname, uses utimes(2) if available, otherwise
		440	utime(2). If called on a file descriptor, uses futimes(2) if available,
		441	otherwise returns ENOSYS, so this is not portable.
		442
		443	Examples:
		444
		445	# set atime and mtime to current time (basically touch(1)):
		446	aio_utime "path", undef, undef;
		447	# set atime to current time and mtime to beginning of the epoch:
		448	aio_utime "path", time, undef; # undef==0
		449
		450
		451	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		452
		453	Works like perl's C<chown> function, except that C<undef> for either $uid
		454	or $gid is being interpreted as "do not change" (but -1 can also be used).
		455
		456	Examples:
		457
		458	# same as "chown root path" in the shell:
		459	aio_chown "path", 0, -1;
		460	# same as above:
		461	aio_chown "path", 0, undef;
		462
		463
		464	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		465
		466	Works like truncate(2) or ftruncate(2).
		467
		468
		469	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		470
		471	Works like perl's C<chmod> function.
		472
		473
316	=item aio_unlink $pathname, $callback->($status)	474	=item aio_unlink $pathname, $callback->($status)
317		475
318	Asynchronously unlink (delete) a file and call the callback with the	476	Asynchronously unlink (delete) a file and call the callback with the
319	result code.	477	result code.
320		478
		479
		480	=item aio_mknod $path, $mode, $dev, $callback->($status)
		481
		482	[EXPERIMENTAL]
		483
		484	Asynchronously create a device node (or fifo). See mknod(2).
		485
		486	The only (POSIX-) portable way of calling this function is:
		487
		488	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		489
		490
321	=item aio_link $srcpath, $dstpath, $callback->($status)	491	=item aio_link $srcpath, $dstpath, $callback->($status)
322		492
323	Asynchronously create a new link to the existing object at C<$srcpath> at	493	Asynchronously create a new link to the existing object at C<$srcpath> at
324	the path C<$dstpath> and call the callback with the result code.	494	the path C<$dstpath> and call the callback with the result code.
325		495
		496
326	=item aio_symlink $srcpath, $dstpath, $callback->($status)	497	=item aio_symlink $srcpath, $dstpath, $callback->($status)
327		498
328	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	499	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
329	the path C<$dstpath> and call the callback with the result code.	500	the path C<$dstpath> and call the callback with the result code.
330		501
		502
		503	=item aio_readlink $path, $callback->($link)
		504
		505	Asynchronously read the symlink specified by C<$path> and pass it to
		506	the callback. If an error occurs, nothing or undef gets passed to the
		507	callback.
		508
		509
331	=item aio_rename $srcpath, $dstpath, $callback->($status)	510	=item aio_rename $srcpath, $dstpath, $callback->($status)
332		511
333	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	512	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
334	rename(2) and call the callback with the result code.	513	rename(2) and call the callback with the result code.
335		514
		515
		516	=item aio_mkdir $pathname, $mode, $callback->($status)
		517
		518	Asynchronously mkdir (create) a directory and call the callback with
		519	the result code. C<$mode> will be modified by the umask at the time the
		520	request is executed, so do not change your umask.
		521
		522
336	=item aio_rmdir $pathname, $callback->($status)	523	=item aio_rmdir $pathname, $callback->($status)
337		524
338	Asynchronously rmdir (delete) a directory and call the callback with the	525	Asynchronously rmdir (delete) a directory and call the callback with the
339	result code.	526	result code.
		527
340		528
341	=item aio_readdir $pathname, $callback->($entries)	529	=item aio_readdir $pathname, $callback->($entries)
342		530
343	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	531	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
344	directory (i.e. opendir + readdir + closedir). The entries will not be	532	directory (i.e. opendir + readdir + closedir). The entries will not be
345	sorted, and will B<NOT> include the C<.> and C<..> entries.	533	sorted, and will B<NOT> include the C<.> and C<..> entries.
346		534
347	The callback a single argument which is either C<undef> or an array-ref	535	The callback a single argument which is either C<undef> or an array-ref
348	with the filenames.	536	with the filenames.
349		537
		538
		539	=item aio_load $path, $data, $callback->($status)
		540
		541	This is a composite request that tries to fully load the given file into
		542	memory. Status is the same as with aio_read.
		543
		544	=cut
		545
		546	sub aio_load($$;$) {
		547	my ($path, undef, $cb) = @_;
		548	my $data = \$_[1];
		549
		550	my $pri = aioreq_pri;
		551	my $grp = aio_group $cb;
		552
		553	aioreq_pri $pri;
		554	add $grp aio_open $path, O_RDONLY, 0, sub {
		555	my $fh = shift
		556	or return $grp->result (-1);
		557
		558	aioreq_pri $pri;
		559	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		560	$grp->result ($_[0]);
		561	};
		562	};
		563
		564	$grp
		565	}
		566
		567	=item aio_copy $srcpath, $dstpath, $callback->($status)
		568
		569	Try to copy the I<file> (directories not supported as either source or
		570	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		571	the C<0> (error) or C<-1> ok.
		572
		573	This is a composite request that creates the destination file with
		574	mode 0200 and copies the contents of the source file into it using
		575	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		576	uid/gid, in that order.
		577
		578	If an error occurs, the partial destination file will be unlinked, if
		579	possible, except when setting atime, mtime, access mode and uid/gid, where
		580	errors are being ignored.
		581
		582	=cut
		583
		584	sub aio_copy($$;$) {
		585	my ($src, $dst, $cb) = @_;
		586
		587	my $pri = aioreq_pri;
		588	my $grp = aio_group $cb;
		589
		590	aioreq_pri $pri;
		591	add $grp aio_open $src, O_RDONLY, 0, sub {
		592	if (my $src_fh = $_[0]) {
		593	my @stat = stat $src_fh;
		594
		595	aioreq_pri $pri;
		596	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		597	if (my $dst_fh = $_[0]) {
		598	aioreq_pri $pri;
		599	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		600	if ($_[0] == $stat[7]) {
		601	$grp->result (0);
		602	close $src_fh;
		603
		604	# those should not normally block. should. should.
		605	utime $stat[8], $stat[9], $dst;
		606	chmod $stat[2] & 07777, $dst_fh;
		607	chown $stat[4], $stat[5], $dst_fh;
		608
		609	aioreq_pri $pri;
		610	add $grp aio_close $dst_fh;
		611	} else {
		612	$grp->result (-1);
		613	close $src_fh;
		614	close $dst_fh;
		615
		616	aioreq $pri;
		617	add $grp aio_unlink $dst;
		618	}
		619	};
		620	} else {
		621	$grp->result (-1);
		622	}
		623	},
		624
		625	} else {
		626	$grp->result (-1);
		627	}
		628	};
		629
		630	$grp
		631	}
		632
		633	=item aio_move $srcpath, $dstpath, $callback->($status)
		634
		635	Try to move the I<file> (directories not supported as either source or
		636	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		637	the C<0> (error) or C<-1> ok.
		638
		639	This is a composite request that tries to rename(2) the file first; if
		640	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		641	that is successful, unlinks the C<$srcpath>.
		642
		643	=cut
		644
		645	sub aio_move($$;$) {
		646	my ($src, $dst, $cb) = @_;
		647
		648	my $pri = aioreq_pri;
		649	my $grp = aio_group $cb;
		650
		651	aioreq_pri $pri;
		652	add $grp aio_rename $src, $dst, sub {
		653	if ($_[0] && $! == EXDEV) {
		654	aioreq_pri $pri;
		655	add $grp aio_copy $src, $dst, sub {
		656	$grp->result ($_[0]);
		657
		658	if (!$_[0]) {
		659	aioreq_pri $pri;
		660	add $grp aio_unlink $src;
		661	}
		662	};
		663	} else {
		664	$grp->result ($_[0]);
		665	}
		666	};
		667
		668	$grp
		669	}
		670
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	671	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		672
352	[EXPERIMENTAL due to internal aio_group use]
353
354	Scans a directory (similar to C<aio_readdir>) but additionally tries to	673	Scans a directory (similar to C<aio_readdir>) but additionally tries to
355	separate the entries of directory C<$path> into two sets of names, ones	674	efficiently separate the entries of directory C<$path> into two sets of
356	you can recurse into (directories or links to them), and ones you cannot	675	names, directories you can recurse into (directories), and ones you cannot
357	recurse into (everything else).	676	recurse into (everything else, including symlinks to directories).
358		677
359	C<aio_scandir> is a composite request that creates of many sub requests_	678	C<aio_scandir> is a composite request that creates of many sub requests_
360	C<$maxreq> specifies the maximum number of outstanding aio requests that	679	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	this function generates. If it is C<< <= 0 >>, then a suitable default	680	this function generates. If it is C<< <= 0 >>, then a suitable default
362	will be chosen (currently 6).	681	will be chosen (currently 4).
363		682
364	On error, the callback is called without arguments, otherwise it receives	683	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	684	two array-refs with path-relative entry names.
366		685
367	Example:	686	Example:
…		…
401	as those tend to return 0 or 1 as link counts, which disables the	720	as those tend to return 0 or 1 as link counts, which disables the
402	directory counting heuristic.	721	directory counting heuristic.
403		722
404	=cut	723	=cut
405		724
406	sub aio_scandir($$$) {	725	sub aio_scandir($$;$) {
407	my ($path, $maxreq, $cb) = @_;	726	my ($path, $maxreq, $cb) = @_;
408		727
		728	my $pri = aioreq_pri;
		729
409	my $grp = aio_group $cb;	730	my $grp = aio_group $cb;
410		731
411	$maxreq = 6 if $maxreq <= 0;	732	$maxreq = 4 if $maxreq <= 0;
412		733
413	# stat once	734	# stat once
		735	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	736	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	737	return $grp->result () if $_[0];
416	my $now = time;	738	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	739	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		740
419	# read the directory entries	741	# read the directory entries
		742	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	743	add $grp aio_readdir $path, sub {
421	my $entries = shift	744	my $entries = shift
422	or return $grp->result ();	745	or return $grp->result ();
423		746
424	# stat the dir another time	747	# stat the dir another time
		748	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	749	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	750	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		751
428	my $ndirs;	752	my $ndirs;
429		753
…		…
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	768	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];	769	@$entries];
446		770
447	my (@dirs, @nondirs);	771	my (@dirs, @nondirs);
448		772
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	773	my $statgrp = add $grp aio_group sub {
		774	$grp->result (\@dirs, \@nondirs);
		775	};
453		776
454	$schedcb = sub {	777	limit $statgrp $maxreq;
455	if (@$entries) {	778	feed $statgrp sub {
456	if ($nreq < $maxreq) {	779	return unless @$entries;
457	my $ent = pop @$entries;	780	my $entry = pop @$entries;
		781
		782	aioreq_pri $pri;
		783	add $statgrp aio_stat "$path/$entry/.", sub {
		784	if ($_[0] < 0) {
		785	push @nondirs, $entry;
		786	} else {
		787	# need to check for real directory
		788	aioreq_pri $pri;
		789	add $statgrp aio_lstat "$path/$entry", sub {
		790	if (-d _) {
		791	push @dirs, $entry;
		792
		793	unless (--$ndirs) {
		794	push @nondirs, @$entries;
		795	feed $statgrp;
		796	}
		797	} else {
		798	push @nondirs, $entry;
		799	}
458	$nreq++;	800	}
459	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
460	}	801	}
461	} elsif (!$nreq) {
462	# finished
463	$statgrp->cancel;
464	undef $statcb;
465	undef $schedcb;
466	$grp->result (\@dirs, \@nondirs);
467	}	802	};
468	};	803	};
469	$statcb = sub {
470	my ($status, $entry) = @_;
471
472	if ($status < 0) {
473	$nreq--;
474	push @nondirs, $entry;
475	&$schedcb;
476	} else {
477	# need to check for real directory
478	add $grp aio_lstat "$path/$entry", sub {
479	$nreq--;
480
481	if (-d _) {
482	push @dirs, $entry;
483
484	if (!--$ndirs) {
485	push @nondirs, @$entries;
486	$entries = [];
487	}
488	} else {
489	push @nondirs, $entry;
490	}
491
492	&$schedcb;
493	}
494	}
495	};
496
497	&$schedcb while @$entries && $nreq < $maxreq;
498	};	804	};
499	};	805	};
500	};	806	};
501		807
502	$grp	808	$grp
503	}	809	}
504		810
		811	=item aio_rmtree $path, $callback->($status)
		812
		813	Delete a directory tree starting (and including) C<$path>, return the
		814	status of the final C<rmdir> only. This is a composite request that
		815	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		816	everything else.
		817
		818	=cut
		819
		820	sub aio_rmtree;
		821	sub aio_rmtree($;$) {
		822	my ($path, $cb) = @_;
		823
		824	my $pri = aioreq_pri;
		825	my $grp = aio_group $cb;
		826
		827	aioreq_pri $pri;
		828	add $grp aio_scandir $path, 0, sub {
		829	my ($dirs, $nondirs) = @_;
		830
		831	my $dirgrp = aio_group sub {
		832	add $grp aio_rmdir $path, sub {
		833	$grp->result ($_[0]);
		834	};
		835	};
		836
		837	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		838	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		839
		840	add $grp $dirgrp;
		841	};
		842
		843	$grp
		844	}
		845
		846	=item aio_sync $callback->($status)
		847
		848	Asynchronously call sync and call the callback when finished.
		849
505	=item aio_fsync $fh, $callback->($status)	850	=item aio_fsync $fh, $callback->($status)
506		851
507	Asynchronously call fsync on the given filehandle and call the callback	852	Asynchronously call fsync on the given filehandle and call the callback
508	with the fsync result code.	853	with the fsync result code.
509		854
…		…
513	callback with the fdatasync result code.	858	callback with the fdatasync result code.
514		859
515	If this call isn't available because your OS lacks it or it couldn't be	860	If this call isn't available because your OS lacks it or it couldn't be
516	detected, it will be emulated by calling C<fsync> instead.	861	detected, it will be emulated by calling C<fsync> instead.
517		862
		863	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		864
		865	Sync the data portion of the file specified by C<$offset> and C<$length>
		866	to disk (but NOT the metadata), by calling the Linux-specific
		867	sync_file_range call. If sync_file_range is not available or it returns
		868	ENOSYS, then fdatasync or fsync is being substituted.
		869
		870	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		871	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		872	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		873	manpage for details.
		874
		875	=item aio_pathsync $path, $callback->($status)
		876
		877	This request tries to open, fsync and close the given path. This is a
		878	composite request intended to sync directories after directory operations
		879	(E.g. rename). This might not work on all operating systems or have any
		880	specific effect, but usually it makes sure that directory changes get
		881	written to disc. It works for anything that can be opened for read-only,
		882	not just directories.
		883
		884	Passes C<0> when everything went ok, and C<-1> on error.
		885
		886	=cut
		887
		888	sub aio_pathsync($;$) {
		889	my ($path, $cb) = @_;
		890
		891	my $pri = aioreq_pri;
		892	my $grp = aio_group $cb;
		893
		894	aioreq_pri $pri;
		895	add $grp aio_open $path, O_RDONLY, 0, sub {
		896	my ($fh) = @_;
		897	if ($fh) {
		898	aioreq_pri $pri;
		899	add $grp aio_fsync $fh, sub {
		900	$grp->result ($_[0]);
		901
		902	aioreq_pri $pri;
		903	add $grp aio_close $fh;
		904	};
		905	} else {
		906	$grp->result (-1);
		907	}
		908	};
		909
		910	$grp
		911	}
		912
518	=item aio_group $callback->(...)	913	=item aio_group $callback->(...)
519
520	[EXPERIMENTAL]
521		914
522	This is a very special aio request: Instead of doing something, it is a	915	This is a very special aio request: Instead of doing something, it is a
523	container for other aio requests, which is useful if you want to bundle	916	container for other aio requests, which is useful if you want to bundle
524	many requests into a single, composite, request.	917	many requests into a single, composite, request with a definite callback
		918	and the ability to cancel the whole request with its subrequests.
525		919
526	Returns an object of class L<IO::AIO::GRP>. See its documentation below	920	Returns an object of class L<IO::AIO::GRP>. See its documentation below
527	for more info.	921	for more info.
528		922
529	Example:	923	Example:
…		…
548	phase and still requires a worker thread. Thus, the callback will not	942	phase and still requires a worker thread. Thus, the callback will not
549	be executed immediately but only after other requests in the queue have	943	be executed immediately but only after other requests in the queue have
550	entered their execution phase. This can be used to measure request	944	entered their execution phase. This can be used to measure request
551	latency.	945	latency.
552		946
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	947	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
554		948
555	Mainly used for debugging and benchmarking, this aio request puts one of	949	Mainly used for debugging and benchmarking, this aio request puts one of
556	the request workers to sleep for the given time.	950	the request workers to sleep for the given time.
557		951
558	While it is theoretically handy to have simple I/O scheduling requests	952	While it is theoretically handy to have simple I/O scheduling requests
559	like sleep and file handle readable/writable, the overhead this creates	953	like sleep and file handle readable/writable, the overhead this creates is
560	is immense, so do not use this function except to put your application	954	immense (it blocks a thread for a long time) so do not use this function
561	under artificial I/O pressure.	955	except to put your application under artificial I/O pressure.
562		956
563	=back	957	=back
564		958
565	=head2 IO::AIO::REQ CLASS	959	=head2 IO::AIO::REQ CLASS
566		960
567	All non-aggregate C<aio_*> functions return an object of this class when	961	All non-aggregate C<aio_*> functions return an object of this class when
568	called in non-void context.	962	called in non-void context.
569
570	A request always moves through the following five states in its lifetime,
571	in order: B<ready> (request has been created, but has not been executed
572	yet), B<execute> (request is currently being executed), B<pending>
573	(request has been executed but callback has not been called yet),
574	B<result> (results are being processed synchronously, includes calling the
575	callback) and B<done> (request has reached the end of its lifetime and
576	holds no resources anymore).
577		963
578	=over 4	964	=over 4
579		965
580	=item cancel $req	966	=item cancel $req
581		967
…		…
635	=item * They can also can also be added to other IO::AIO::GRP objects.	1021	=item * They can also can also be added to other IO::AIO::GRP objects.
636		1022
637	=item * You must not add requests to a group from within the group callback (or	1023	=item * You must not add requests to a group from within the group callback (or
638	any later time).	1024	any later time).
639		1025
640	=item * This does not harmonise well with C<max_outstanding>, so best do
641	not combine C<aio_group> with it. Groups and feeders are recommended for
642	this kind of concurrency-limiting.
643
644	=back	1026	=back
645		1027
646	Their lifetime, simplified, looks like this: when they are empty, they	1028	Their lifetime, simplified, looks like this: when they are empty, they
647	will finish very quickly. If they contain only requests that are in the	1029	will finish very quickly. If they contain only requests that are in the
648	C<done> state, they will also finish. Otherwise they will continue to	1030	C<done> state, they will also finish. Otherwise they will continue to
649	exist.	1031	exist.
650		1032
651	That means after creating a group you have some time to add requests. And	1033	That means after creating a group you have some time to add requests
652	in the callbacks of those requests, you can add further requests to the	1034	(precisely before the callback has been invoked, which is only done within
653	group. And only when all those requests have finished will the the group	1035	the C<poll_cb>). And in the callbacks of those requests, you can add
654	itself finish.	1036	further requests to the group. And only when all those requests have
		1037	finished will the the group itself finish.
655		1038
656	=over 4	1039	=over 4
657		1040
658	=item add $grp ...	1041	=item add $grp ...
659		1042
…		…
663	be added, including other groups, as long as you do not create circular	1046	be added, including other groups, as long as you do not create circular
664	dependencies.	1047	dependencies.
665		1048
666	Returns all its arguments.	1049	Returns all its arguments.
667		1050
		1051	=item $grp->cancel_subs
		1052
		1053	Cancel all subrequests and clears any feeder, but not the group request
		1054	itself. Useful when you queued a lot of events but got a result early.
		1055
668	=item $grp->result (...)	1056	=item $grp->result (...)
669		1057
670	Set the result value(s) that will be passed to the group callback when all	1058	Set the result value(s) that will be passed to the group callback when all
671	subrequests have finished. By default, no argument will be passed.	1059	subrequests have finished and set the groups errno to the current value
		1060	of errno (just like calling C<errno> without an error number). By default,
		1061	no argument will be passed and errno is zero.
		1062
		1063	=item $grp->errno ([$errno])
		1064
		1065	Sets the group errno value to C<$errno>, or the current value of errno
		1066	when the argument is missing.
		1067
		1068	Every aio request has an associated errno value that is restored when
		1069	the callback is invoked. This method lets you change this value from its
		1070	default (0).
		1071
		1072	Calling C<result> will also set errno, so make sure you either set C<$!>
		1073	before the call to C<result>, or call c<errno> after it.
672		1074
673	=item feed $grp $callback->($grp)	1075	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		1076
677	Sets a feeder/generator on this group: every group can have an attached	1077	Sets a feeder/generator on this group: every group can have an attached
678	generator that generates requests if idle. The idea behind this is that,	1078	generator that generates requests if idle. The idea behind this is that,
679	although you could just queue as many requests as you want in a group,	1079	although you could just queue as many requests as you want in a group,
680	this might starve other requests for a potentially long time. For	1080	this might starve other requests for a potentially long time. For example,
681	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1081	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
682	requests, delaying any later requests for a long time.	1082	delaying any later requests for a long time.
683		1083
684	To avoid this, and allow incremental generation of requests, you can	1084	To avoid this, and allow incremental generation of requests, you can
685	instead a group and set a feeder on it that generates those requests. The	1085	instead a group and set a feeder on it that generates those requests. The
686	feed callback will be called whenever there are few enough (see C<feed_limit>,	1086	feed callback will be called whenever there are few enough (see C<limit>,
687	below) requests active in the group itself and is expected to queue more	1087	below) requests active in the group itself and is expected to queue more
688	requests.	1088	requests.
689		1089
690	The feed can queue as many requests as it likes (i.e. C<add> does not	1090	The feed callback can queue as many requests as it likes (i.e. C<add> does
691	impose any limits).	1091	not impose any limits).
692		1092
693	If the feed does not queue more requests when called, it will be	1093	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	1094	automatically removed from the group.
695		1095
696	If the feed limit is C<0>, it will be set to C<2> automatically.	1096	If the feed limit is C<0> when this method is called, it will be set to
		1097	C<2> automatically.
697		1098
698	Example:	1099	Example:
699		1100
700	# stat all files in @files, but only ever use four aio requests concurrently:	1101	# stat all files in @files, but only ever use four aio requests concurrently:
701		1102
702	my $grp = aio_group sub { print "finished\n" };	1103	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	1104	limit $grp 4;
704	feed $grp sub {	1105	feed $grp sub {
705	my $file = pop @files	1106	my $file = pop @files
706	or return;	1107	or return;
707		1108
708	add $grp aio_stat $file, sub { ... };	1109	add $grp aio_stat $file, sub { ... };
709	};	1110	};
710		1111
711	=item feed_limit $grp $num	1112	=item limit $grp $num
712		1113
713	Sets the feeder limit for the group: The feeder will be called whenever	1114	Sets the feeder limit for the group: The feeder will be called whenever
714	the group contains less than this many requests.	1115	the group contains less than this many requests.
715		1116
716	Setting the limit to C<0> will pause the feeding process.	1117	Setting the limit to C<0> will pause the feeding process.
717		1118
		1119	The default value for the limit is C<0>, but note that setting a feeder
		1120	automatically bumps it up to C<2>.
		1121
718	=back	1122	=back
719		1123
720	=head2 SUPPORT FUNCTIONS	1124	=head2 SUPPORT FUNCTIONS
		1125
		1126	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
721		1127
722	=over 4	1128	=over 4
723		1129
724	=item $fileno = IO::AIO::poll_fileno	1130	=item $fileno = IO::AIO::poll_fileno
725		1131
…		…
730		1136
731	See C<poll_cb> for an example.	1137	See C<poll_cb> for an example.
732		1138
733	=item IO::AIO::poll_cb	1139	=item IO::AIO::poll_cb
734		1140
735	Process all outstanding events on the result pipe. You have to call this	1141	Process some outstanding events on the result pipe. You have to call this
736	regularly. Returns the number of events processed. Returns immediately	1142	regularly. Returns C<0> if all events could be processed, or C<-1> if it
737	when no events are outstanding.	1143	returned earlier for whatever reason. Returns immediately when no events
		1144	are outstanding. The amount of events processed depends on the settings of
		1145	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1146
		1147	If not all requests were processed for whatever reason, the filehandle
		1148	will still be ready when C<poll_cb> returns, so normally you don't have to
		1149	do anything special to have it called later.
738		1150
739	Example: Install an Event watcher that automatically calls	1151	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	1152	IO::AIO::poll_cb with high priority:
741		1153
742	Event->io (fd => IO::AIO::poll_fileno,	1154	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	1155	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	1156	cb => \&IO::AIO::poll_cb);
745		1157
		1158	=item IO::AIO::max_poll_reqs $nreqs
		1159
		1160	=item IO::AIO::max_poll_time $seconds
		1161
		1162	These set the maximum number of requests (default C<0>, meaning infinity)
		1163	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1164	the maximum amount of time (default C<0>, meaning infinity) spent in
		1165	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1166	of time C<poll_cb> is allowed to use).
		1167
		1168	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1169	syscall per request processed, which is not normally a problem unless your
		1170	callbacks are really really fast or your OS is really really slow (I am
		1171	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1172
		1173	Setting these is useful if you want to ensure some level of
		1174	interactiveness when perl is not fast enough to process all requests in
		1175	time.
		1176
		1177	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1178
		1179	Example: Install an Event watcher that automatically calls
		1180	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1181	program get the CPU sometimes even under high AIO load.
		1182
		1183	# try not to spend much more than 0.1s in poll_cb
		1184	IO::AIO::max_poll_time 0.1;
		1185
		1186	# use a low priority so other tasks have priority
		1187	Event->io (fd => IO::AIO::poll_fileno,
		1188	poll => 'r', nice => 1,
		1189	cb => &IO::AIO::poll_cb);
		1190
746	=item IO::AIO::poll_wait	1191	=item IO::AIO::poll_wait
747		1192
		1193	If there are any outstanding requests and none of them in the result
748	Wait till the result filehandle becomes ready for reading (simply does a	1194	phase, wait till the result filehandle becomes ready for reading (simply
749	C<select> on the filehandle. This is useful if you want to synchronously wait	1195	does a C<select> on the filehandle. This is useful if you want to
750	for some requests to finish).	1196	synchronously wait for some requests to finish).
751		1197
752	See C<nreqs> for an example.	1198	See C<nreqs> for an example.
753		1199
		1200	=item IO::AIO::poll
		1201
		1202	Waits until some requests have been handled.
		1203
		1204	Returns the number of requests processed, but is otherwise strictly
		1205	equivalent to:
		1206
		1207	IO::AIO::poll_wait, IO::AIO::poll_cb
		1208
754	=item IO::AIO::nreqs	1209	=item IO::AIO::flush
755		1210
756	Returns the number of requests currently outstanding (i.e. for which their	1211	Wait till all outstanding AIO requests have been handled.
757	callback has not been invoked yet).
758		1212
759	Example: wait till there are no outstanding requests anymore:	1213	Strictly equivalent to:
760		1214
761	IO::AIO::poll_wait, IO::AIO::poll_cb	1215	IO::AIO::poll_wait, IO::AIO::poll_cb
762	while IO::AIO::nreqs;	1216	while IO::AIO::nreqs;
763		1217
764	=item IO::AIO::flush	1218	=back
765		1219
766	Wait till all outstanding AIO requests have been handled.	1220	=head3 CONTROLLING THE NUMBER OF THREADS
767		1221
768	Strictly equivalent to:	1222	=over
769
770	IO::AIO::poll_wait, IO::AIO::poll_cb
771	while IO::AIO::nreqs;
772
773	=item IO::AIO::poll
774
775	Waits until some requests have been handled.
776
777	Strictly equivalent to:
778
779	IO::AIO::poll_wait, IO::AIO::poll_cb
780	if IO::AIO::nreqs;
781		1223
782	=item IO::AIO::min_parallel $nthreads	1224	=item IO::AIO::min_parallel $nthreads
783		1225
784	Set the minimum number of AIO threads to C<$nthreads>. The current	1226	Set the minimum number of AIO threads to C<$nthreads>. The current
785	default is C<8>, which means eight asynchronous operations can execute	1227	default is C<8>, which means eight asynchronous operations can execute
786	concurrently at any one time (the number of outstanding requests,	1228	concurrently at any one time (the number of outstanding requests,
787	however, is unlimited).	1229	however, is unlimited).
788		1230
789	IO::AIO starts threads only on demand, when an AIO request is queued and	1231	IO::AIO starts threads only on demand, when an AIO request is queued and
790	no free thread exists.	1232	no free thread exists. Please note that queueing up a hundred requests can
		1233	create demand for a hundred threads, even if it turns out that everything
		1234	is in the cache and could have been processed faster by a single thread.
791		1235
792	It is recommended to keep the number of threads relatively low, as some	1236	It is recommended to keep the number of threads relatively low, as some
793	Linux kernel versions will scale negatively with the number of threads	1237	Linux kernel versions will scale negatively with the number of threads
794	(higher parallelity => MUCH higher latency). With current Linux 2.6	1238	(higher parallelity => MUCH higher latency). With current Linux 2.6
795	versions, 4-32 threads should be fine.	1239	versions, 4-32 threads should be fine.
…		…
809	This module automatically runs C<max_parallel 0> at program end, to ensure	1253	This module automatically runs C<max_parallel 0> at program end, to ensure
810	that all threads are killed and that there are no outstanding requests.	1254	that all threads are killed and that there are no outstanding requests.
811		1255
812	Under normal circumstances you don't need to call this function.	1256	Under normal circumstances you don't need to call this function.
813		1257
		1258	=item IO::AIO::max_idle $nthreads
		1259
		1260	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1261	threads that did not get a request to process within 10 seconds). That
		1262	means if a thread becomes idle while C<$nthreads> other threads are also
		1263	idle, it will free its resources and exit.
		1264
		1265	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1266	to allow for extremely high load situations, but want to free resources
		1267	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1268
		1269	The default is probably ok in most situations, especially if thread
		1270	creation is fast. If thread creation is very slow on your system you might
		1271	want to use larger values.
		1272
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1273	=item IO::AIO::max_outstanding $maxreqs
815		1274
816	[DEPRECATED]	1275	This is a very bad function to use in interactive programs because it
		1276	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1277	use an C<aio_group> together with a feed callback.
817		1278
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1279	Sets the maximum number of outstanding requests to C<$nreqs>. If you
819	try to queue up more than this number of requests, the caller will block until	1280	do queue up more than this number of requests, the next call to the
820	some requests have been handled.	1281	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1282	function will block until the limit is no longer exceeded.
821		1283
822	The default is very large, so normally there is no practical limit. If you	1284	The default value is very large, so there is no practical limit on the
823	queue up many requests in a loop it often improves speed if you set	1285	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		1286
826	This function does not work well together with C<aio_group>'s, and their	1287	You can still queue as many requests as you want. Therefore,
827	feeder interface is better suited to limiting concurrency, so do not use	1288	C<max_outstanding> is mainly useful in simple scripts (with low values) or
828	this function.	1289	as a stop gap to shield against fatal memory overflow (with large values).
829
830	Under normal circumstances you don't need to call this function.
831		1290
832	=back	1291	=back
833		1292
		1293	=head3 STATISTICAL INFORMATION
		1294
		1295	=over
		1296
		1297	=item IO::AIO::nreqs
		1298
		1299	Returns the number of requests currently in the ready, execute or pending
		1300	states (i.e. for which their callback has not been invoked yet).
		1301
		1302	Example: wait till there are no outstanding requests anymore:
		1303
		1304	IO::AIO::poll_wait, IO::AIO::poll_cb
		1305	while IO::AIO::nreqs;
		1306
		1307	=item IO::AIO::nready
		1308
		1309	Returns the number of requests currently in the ready state (not yet
		1310	executed).
		1311
		1312	=item IO::AIO::npending
		1313
		1314	Returns the number of requests currently in the pending state (executed,
		1315	but not yet processed by poll_cb).
		1316
		1317	=back
		1318
834	=cut	1319	=cut
835		1320
836	# support function to convert a fd into a perl filehandle
837	sub _fd2fh {
838	return undef if $_[0] < 0;
839
840	# try to generate nice filehandles
841	my $sym = "IO::AIO::fd#$_[0]";
842	local *$sym;
843
844	open *$sym, "+<&=$_[0]" # usually works under any unix
845	or open *$sym, "<&=$_[0]" # cygwin needs this
846	or open *$sym, ">&=$_[0]" # or this
847	or return undef;
848
849	*$sym
850	}
851
852	min_parallel 8;	1321	min_parallel 8;
853		1322
854	END {	1323	END { flush }
855	max_parallel 0;
856	}
857		1324
858	1;	1325	1;
859		1326
860	=head2 FORK BEHAVIOUR	1327	=head2 FORK BEHAVIOUR
861		1328
862	This module should do "the right thing" when the process using it forks:	1329	This module should do "the right thing" when the process using it forks:
863		1330
864	Before the fork, IO::AIO enters a quiescent state where no requests	1331	Before the fork, IO::AIO enters a quiescent state where no requests
865	can be added in other threads and no results will be processed. After	1332	can be added in other threads and no results will be processed. After
866	the fork the parent simply leaves the quiescent state and continues	1333	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	1334	request/result processing, while the child frees the request/result queue
868	queue (so the requests started before the fork will only be handled in	1335	(so that the requests started before the fork will only be handled in the
869	the parent). Threads will be started on demand until the limit ste in the	1336	parent). Threads will be started on demand until the limit set in the
870	parent process has been reached again.	1337	parent process has been reached again.
871		1338
872	In short: the parent will, after a short pause, continue as if fork had	1339	In short: the parent will, after a short pause, continue as if fork had
873	not been called, while the child will act as if IO::AIO has not been used	1340	not been called, while the child will act as if IO::AIO has not been used
874	yet.	1341	yet.
875		1342
876	=head2 MEMORY USAGE	1343	=head2 MEMORY USAGE
877		1344
		1345	Per-request usage:
		1346
878	Each aio request uses - depending on your architecture - around 128 bytes	1347	Each aio request uses - depending on your architecture - around 100-200
879	of memory. In addition, stat requests need a stat buffer (possibly a few	1348	bytes of memory. In addition, stat requests need a stat buffer (possibly
880	hundred bytes). Perl scalars and other data passed into aio requests will	1349	a few hundred bytes), readdir requires a result buffer and so on. Perl
881	also be locked.	1350	scalars and other data passed into aio requests will also be locked and
		1351	will consume memory till the request has entered the done state.
882		1352
883	This is now awfully much, so queuing lots of requests is not usually a	1353	This is not awfully much, so queuing lots of requests is not usually a
884	problem.	1354	problem.
885		1355
886	Each thread needs a stack area which is usually around 16k, sometimes much	1356	Per-thread usage:
887	larger, depending on the OS.	1357
		1358	In the execution phase, some aio requests require more memory for
		1359	temporary buffers, and each thread requires a stack and other data
		1360	structures (usually around 16k-128k, depending on the OS).
		1361
		1362	=head1 KNOWN BUGS
		1363
		1364	Known bugs will be fixed in the next release.
888		1365
889	=head1 SEE ALSO	1366	=head1 SEE ALSO
890		1367
891	L<Coro>, L<Linux::AIO> (obsolete).	1368	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1369	more natural syntax.
892		1370
893	=head1 AUTHOR	1371	=head1 AUTHOR
894		1372
895	Marc Lehmann <schmorp@schmorp.de>	1373	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1374	http://home.schmorp.de/

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Revision 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs.
Revision 1.145 by root, Sun Apr 19 19:20:10 2009 UTC