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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.146 by root, Tue Apr 21 20:06:05 2009 UTC

…		…
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", O_RDONLY, 0, sub {
10	my ($fh) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
25	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
26		27
27	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
28	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
29		30
		31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		32	use AnyEvent::AIO;
		33
30	# AnyEvent integration	34	# EV integration
31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	35	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
33		36
34	# Event integration	37	# Event integration
35	Event->io (fd => IO::AIO::poll_fileno,	38	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',	39	poll => 'r',
37	cb => \&IO::AIO::poll_cb);	40	cb => \&IO::AIO::poll_cb);
…		…
51	=head1 DESCRIPTION	54	=head1 DESCRIPTION
52		55
53	This module implements asynchronous I/O using whatever means your	56	This module implements asynchronous I/O using whatever means your
54	operating system supports.	57	operating system supports.
55		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
56	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
57	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
58	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
59	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
60	on many operating systems. However, they are often not well-supported	79	functions available on many operating systems. However, they are often
61	(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
62	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
63	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.
64		84
65	Although the module will work with in the presence of other threads,	85	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	86	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	87	yourself, always call C<poll_cb> from within the same thread, or never
68	call C<poll_cb> (or other C<aio_> functions) recursively.	88	call C<poll_cb> (or other C<aio_> functions) recursively.
69		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
		185
70	=cut	186	=cut
71		187
72	package IO::AIO;	188	package IO::AIO;
		189
		190	use Carp ();
73		191
74	no warnings;	192	no warnings;
75	use strict 'vars';	193	use strict 'vars';
76		194
77	use base 'Exporter';	195	use base 'Exporter';
78		196
79	BEGIN {	197	BEGIN {
80	our $VERSION = '2.0';	198	our $VERSION = '3.19';
81		199
82	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
83	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	201	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	202	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
85	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
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	208	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	209	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	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
89		215
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	216	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		217
92	require XSLoader;	218	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	219	XSLoader::load ("IO::AIO", $VERSION);
94	}	220	}
95		221
96	=head1 FUNCTIONS	222	=head1 FUNCTIONS
97		223
98	=head2 AIO FUNCTIONS	224	=head2 AIO REQUEST FUNCTIONS
99		225
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	226	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	227	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	228	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	229	which must be a code reference. This code reference will get called with
104	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
105	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
106	syscall has been executed asynchronously.	232	syscall has been executed asynchronously.
107		233
108	All functions expecting a filehandle keep a copy of the filehandle	234	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	235	internally until the request has finished.
110		236
111	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
112	manipulation of those requests while they are in-flight.	238	further manipulation of those requests while they are in-flight.
113		239
114	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
115	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
116	request is being executed, the current working directory could have	242	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	243	changed. Alternatively, you can make sure that you never change the
118	current working directory.	244	current working directory anywhere in the program and then use relative
		245	paths.
119		246
120	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
121	always pass in filenames you got from outside (command line, readdir	248	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	249	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	250	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)	251	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	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.
126		256
127	=over 4	257	=over 4
128		258
129	=item aioreq_pri $pri	259	=item $prev_pri = aioreq_pri [$pri]
130		260
131	Sets the priority for the next aio request. The default priority	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
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	264	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	265	and C<4>, respectively. Requests with higher priority will be serviced
		266	first.
134		267
135	The priority will be reset to C<0> after each call to one of the C<aio_>	268	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	269	functions.
137		270
138	Example: open a file with low priority, then read something from it with	271	Example: open a file with low priority, then read something from it with
139	higher priority so the read request is serviced before other low priority	272	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	273	open requests (potentially spamming the cache):
…		…
147	aio_read $_[0], ..., sub {	280	aio_read $_[0], ..., sub {
148	...	281	...
149	};	282	};
150	};	283	};
151		284
		285
152	=item aioreq_nice $pri_adjust	286	=item aioreq_nice $pri_adjust
153		287
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	288	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	289	priority, so the effect is cumulative.
		290
156		291
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	292	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		293
159	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
160	created filehandle for the file.	295	created filehandle for the file.
…		…
166	list. They are the same as used by C<sysopen>.	301	list. They are the same as used by C<sysopen>.
167		302
168	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
169	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>,
170	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,
171	and C<0666> or C<0777> if you do).	306	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		307	by the umask in effect then the request is being executed, so better never
		308	change the umask.
172		309
173	Example:	310	Example:
174		311
175	aio_open "/etc/passwd", O_RDONLY, 0, sub {	312	aio_open "/etc/passwd", O_RDONLY, 0, sub {
176	if ($_[0]) {	313	if ($_[0]) {
…		…
179	} else {	316	} else {
180	die "open failed: $!\n";	317	die "open failed: $!\n";
181	}	318	}
182	};	319	};
183		320
		321
184	=item aio_close $fh, $callback->($status)	322	=item aio_close $fh, $callback->($status)
185		323
186	Asynchronously close a file and call the callback with the result	324	Asynchronously close a file and call the callback with the result
187	code. I<WARNING:> although accepted, you should not pass in a perl	325	code.
188	filehandle here, as perl will likely close the file descriptor another
189	time when the filehandle is destroyed. Normally, you can safely call perls
190	C<close> or just let filehandles go out of scope.
191		326
192	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
193	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
194		338
195	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	339	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
196		340
197	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	341	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
198		342
199	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
200	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<$dataoffset>
201	callback without the actual number of bytes read (or -1 on error, just	345	and calls the callback without the actual number of bytes read (or -1 on
202	like the syscall).	346	error, just like the syscall).
		347
		348	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		349	offset plus the actual number of bytes read.
		350
		351	If C<$offset> is undefined, then the current file descriptor offset will
		352	be used (and updated), otherwise the file descriptor offset will not be
		353	changed by these calls.
		354
		355	If C<$length> is undefined in C<aio_write>, use the remaining length of
		356	C<$data>.
		357
		358	If C<$dataoffset> is less than zero, it will be counted from the end of
		359	C<$data>.
203		360
204	The C<$data> scalar I<MUST NOT> be modified in any way while the request	361	The C<$data> scalar I<MUST NOT> be modified in any way while the request
205	is outstanding. Modifying it can result in segfaults or WW3 (if the	362	is outstanding. Modifying it can result in segfaults or World War III (if
206	necessary/optional hardware is installed).	363	the necessary/optional hardware is installed).
207		364
208	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	365	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
209	offset C<0> within the scalar:	366	offset C<0> within the scalar:
210		367
211	aio_read $fh, 7, 15, $buffer, 0, sub {	368	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	369	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	370	print "read $_[0] bytes: <$buffer>\n";
214	};	371	};
215		372
216	=item aio_move $srcpath, $dstpath, $callback->($status)
217
218	[EXPERIMENTAL due to internal aio_group use]
219
220	Try to move the I<file> (directories not supported as either source or
221	destination) from C<$srcpath> to C<$dstpath> and call the callback with
222	the C<0> (error) or C<-1> ok.
223
224	This is a composite request that tries to rename(2) the file first. If
225	rename files with C<EXDEV>, it creates the destination file with mode 0200
226	and copies the contents of the source file into it using C<aio_sendfile>,
227	followed by restoring atime, mtime, access mode and uid/gid, in that
228	order, and unlinking the C<$srcpath>.
229
230	If an error occurs, the partial destination file will be unlinked, if
231	possible, except when setting atime, mtime, access mode and uid/gid, where
232	errors are being ignored.
233
234	=cut
235
236	sub aio_move($$$) {
237	my ($src, $dst, $cb) = @_;
238
239	my $grp = aio_group $cb;
240
241	add $grp aio_rename $src, $dst, sub {
242	if ($_[0] && $! == EXDEV) {
243	add $grp aio_open $src, O_RDONLY, 0, sub {
244	if (my $src_fh = $_[0]) {
245	my @stat = stat $src_fh;
246
247	add $grp aio_open $dst, O_WRONLY, 0200, sub {
248	if (my $dst_fh = $_[0]) {
249	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
250	close $src_fh;
251
252	if ($_[0] == $stat[7]) {
253	utime $stat[8], $stat[9], $dst;
254	chmod $stat[2] & 07777, $dst_fh;
255	chown $stat[4], $stat[5], $dst_fh;
256	close $dst_fh;
257
258	add $grp aio_unlink $src, sub {
259	$grp->result ($_[0]);
260	};
261	} else {
262	my $errno = $!;
263	add $grp aio_unlink $dst, sub {
264	$! = $errno;
265	$grp->result (-1);
266	};
267	}
268	};
269	} else {
270	$grp->result (-1);
271	}
272	},
273
274	} else {
275	$grp->result (-1);
276	}
277	};
278	} else {
279	$grp->result ($_[0]);
280	}
281	};
282
283	$grp
284	}
285		373
286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	374	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
287		375
288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	376	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
289	reading at byte offset C<$in_offset>, and starts writing at the current	377	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
303	C<$in_fh> than are written, and there is no way to find out how many	391	C<$in_fh> than are written, and there is no way to find out how many
304	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	392	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
305	provides the number of bytes written to C<$out_fh>. Only if the result	393	provides the number of bytes written to C<$out_fh>. Only if the result
306	value equals C<$length> one can assume that C<$length> bytes have been	394	value equals C<$length> one can assume that C<$length> bytes have been
307	read.	395	read.
		396
308		397
309	=item aio_readahead $fh,$offset,$length, $callback->($retval)	398	=item aio_readahead $fh,$offset,$length, $callback->($retval)
310		399
311	C<aio_readahead> populates the page cache with data from a file so that	400	C<aio_readahead> populates the page cache with data from a file so that
312	subsequent reads from that file will not block on disk I/O. The C<$offset>	401	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
318	file. The current file offset of the file is left unchanged.	407	file. The current file offset of the file is left unchanged.
319		408
320	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	409	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
321	emulated by simply reading the data, which would have a similar effect.	410	emulated by simply reading the data, which would have a similar effect.
322		411
		412
323	=item aio_stat $fh_or_path, $callback->($status)	413	=item aio_stat $fh_or_path, $callback->($status)
324		414
325	=item aio_lstat $fh, $callback->($status)	415	=item aio_lstat $fh, $callback->($status)
326		416
327	Works like perl's C<stat> or C<lstat> in void context. The callback will	417	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
340	aio_stat "/etc/passwd", sub {	430	aio_stat "/etc/passwd", sub {
341	$_[0] and die "stat failed: $!";	431	$_[0] and die "stat failed: $!";
342	print "size is ", -s _, "\n";	432	print "size is ", -s _, "\n";
343	};	433	};
344		434
		435
		436	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		437
		438	Works like perl's C<utime> function (including the special case of $atime
		439	and $mtime being undef). Fractional times are supported if the underlying
		440	syscalls support them.
		441
		442	When called with a pathname, uses utimes(2) if available, otherwise
		443	utime(2). If called on a file descriptor, uses futimes(2) if available,
		444	otherwise returns ENOSYS, so this is not portable.
		445
		446	Examples:
		447
		448	# set atime and mtime to current time (basically touch(1)):
		449	aio_utime "path", undef, undef;
		450	# set atime to current time and mtime to beginning of the epoch:
		451	aio_utime "path", time, undef; # undef==0
		452
		453
		454	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		455
		456	Works like perl's C<chown> function, except that C<undef> for either $uid
		457	or $gid is being interpreted as "do not change" (but -1 can also be used).
		458
		459	Examples:
		460
		461	# same as "chown root path" in the shell:
		462	aio_chown "path", 0, -1;
		463	# same as above:
		464	aio_chown "path", 0, undef;
		465
		466
		467	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		468
		469	Works like truncate(2) or ftruncate(2).
		470
		471
		472	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		473
		474	Works like perl's C<chmod> function.
		475
		476
345	=item aio_unlink $pathname, $callback->($status)	477	=item aio_unlink $pathname, $callback->($status)
346		478
347	Asynchronously unlink (delete) a file and call the callback with the	479	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	480	result code.
349		481
		482
		483	=item aio_mknod $path, $mode, $dev, $callback->($status)
		484
		485	[EXPERIMENTAL]
		486
		487	Asynchronously create a device node (or fifo). See mknod(2).
		488
		489	The only (POSIX-) portable way of calling this function is:
		490
		491	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		492
		493
350	=item aio_link $srcpath, $dstpath, $callback->($status)	494	=item aio_link $srcpath, $dstpath, $callback->($status)
351		495
352	Asynchronously create a new link to the existing object at C<$srcpath> at	496	Asynchronously create a new link to the existing object at C<$srcpath> at
353	the path C<$dstpath> and call the callback with the result code.	497	the path C<$dstpath> and call the callback with the result code.
354		498
		499
355	=item aio_symlink $srcpath, $dstpath, $callback->($status)	500	=item aio_symlink $srcpath, $dstpath, $callback->($status)
356		501
357	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	502	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
358	the path C<$dstpath> and call the callback with the result code.	503	the path C<$dstpath> and call the callback with the result code.
359		504
		505
		506	=item aio_readlink $path, $callback->($link)
		507
		508	Asynchronously read the symlink specified by C<$path> and pass it to
		509	the callback. If an error occurs, nothing or undef gets passed to the
		510	callback.
		511
		512
360	=item aio_rename $srcpath, $dstpath, $callback->($status)	513	=item aio_rename $srcpath, $dstpath, $callback->($status)
361		514
362	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	515	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
363	rename(2) and call the callback with the result code.	516	rename(2) and call the callback with the result code.
364		517
		518
		519	=item aio_mkdir $pathname, $mode, $callback->($status)
		520
		521	Asynchronously mkdir (create) a directory and call the callback with
		522	the result code. C<$mode> will be modified by the umask at the time the
		523	request is executed, so do not change your umask.
		524
		525
365	=item aio_rmdir $pathname, $callback->($status)	526	=item aio_rmdir $pathname, $callback->($status)
366		527
367	Asynchronously rmdir (delete) a directory and call the callback with the	528	Asynchronously rmdir (delete) a directory and call the callback with the
368	result code.	529	result code.
		530
369		531
370	=item aio_readdir $pathname, $callback->($entries)	532	=item aio_readdir $pathname, $callback->($entries)
371		533
372	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	534	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
373	directory (i.e. opendir + readdir + closedir). The entries will not be	535	directory (i.e. opendir + readdir + closedir). The entries will not be
374	sorted, and will B<NOT> include the C<.> and C<..> entries.	536	sorted, and will B<NOT> include the C<.> and C<..> entries.
375		537
376	The callback a single argument which is either C<undef> or an array-ref	538	The callback a single argument which is either C<undef> or an array-ref
377	with the filenames.	539	with the filenames.
378		540
		541
		542	=item aio_load $path, $data, $callback->($status)
		543
		544	This is a composite request that tries to fully load the given file into
		545	memory. Status is the same as with aio_read.
		546
		547	=cut
		548
		549	sub aio_load($$;$) {
		550	my ($path, undef, $cb) = @_;
		551	my $data = \$_[1];
		552
		553	my $pri = aioreq_pri;
		554	my $grp = aio_group $cb;
		555
		556	aioreq_pri $pri;
		557	add $grp aio_open $path, O_RDONLY, 0, sub {
		558	my $fh = shift
		559	or return $grp->result (-1);
		560
		561	aioreq_pri $pri;
		562	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		563	$grp->result ($_[0]);
		564	};
		565	};
		566
		567	$grp
		568	}
		569
		570	=item aio_copy $srcpath, $dstpath, $callback->($status)
		571
		572	Try to copy the I<file> (directories not supported as either source or
		573	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		574	the C<0> (error) or C<-1> ok.
		575
		576	This is a composite request that creates the destination file with
		577	mode 0200 and copies the contents of the source file into it using
		578	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		579	uid/gid, in that order.
		580
		581	If an error occurs, the partial destination file will be unlinked, if
		582	possible, except when setting atime, mtime, access mode and uid/gid, where
		583	errors are being ignored.
		584
		585	=cut
		586
		587	sub aio_copy($$;$) {
		588	my ($src, $dst, $cb) = @_;
		589
		590	my $pri = aioreq_pri;
		591	my $grp = aio_group $cb;
		592
		593	aioreq_pri $pri;
		594	add $grp aio_open $src, O_RDONLY, 0, sub {
		595	if (my $src_fh = $_[0]) {
		596	my @stat = stat $src_fh;
		597
		598	aioreq_pri $pri;
		599	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		600	if (my $dst_fh = $_[0]) {
		601	aioreq_pri $pri;
		602	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		603	if ($_[0] == $stat[7]) {
		604	$grp->result (0);
		605	close $src_fh;
		606
		607	# those should not normally block. should. should.
		608	utime $stat[8], $stat[9], $dst;
		609	chmod $stat[2] & 07777, $dst_fh;
		610	chown $stat[4], $stat[5], $dst_fh;
		611
		612	aioreq_pri $pri;
		613	add $grp aio_close $dst_fh;
		614	} else {
		615	$grp->result (-1);
		616	close $src_fh;
		617	close $dst_fh;
		618
		619	aioreq $pri;
		620	add $grp aio_unlink $dst;
		621	}
		622	};
		623	} else {
		624	$grp->result (-1);
		625	}
		626	},
		627
		628	} else {
		629	$grp->result (-1);
		630	}
		631	};
		632
		633	$grp
		634	}
		635
		636	=item aio_move $srcpath, $dstpath, $callback->($status)
		637
		638	Try to move the I<file> (directories not supported as either source or
		639	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		640	the C<0> (error) or C<-1> ok.
		641
		642	This is a composite request that tries to rename(2) the file first; if
		643	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		644	that is successful, unlinks the C<$srcpath>.
		645
		646	=cut
		647
		648	sub aio_move($$;$) {
		649	my ($src, $dst, $cb) = @_;
		650
		651	my $pri = aioreq_pri;
		652	my $grp = aio_group $cb;
		653
		654	aioreq_pri $pri;
		655	add $grp aio_rename $src, $dst, sub {
		656	if ($_[0] && $! == EXDEV) {
		657	aioreq_pri $pri;
		658	add $grp aio_copy $src, $dst, sub {
		659	$grp->result ($_[0]);
		660
		661	if (!$_[0]) {
		662	aioreq_pri $pri;
		663	add $grp aio_unlink $src;
		664	}
		665	};
		666	} else {
		667	$grp->result ($_[0]);
		668	}
		669	};
		670
		671	$grp
		672	}
		673
379	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	674	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
380		675
381	[EXPERIMENTAL due to internal aio_group use]
382
383	Scans a directory (similar to C<aio_readdir>) but additionally tries to	676	Scans a directory (similar to C<aio_readdir>) but additionally tries to
384	separate the entries of directory C<$path> into two sets of names, ones	677	efficiently separate the entries of directory C<$path> into two sets of
385	you can recurse into (directories or links to them), and ones you cannot	678	names, directories you can recurse into (directories), and ones you cannot
386	recurse into (everything else).	679	recurse into (everything else, including symlinks to directories).
387		680
388	C<aio_scandir> is a composite request that creates of many sub requests_	681	C<aio_scandir> is a composite request that creates of many sub requests_
389	C<$maxreq> specifies the maximum number of outstanding aio requests that	682	C<$maxreq> specifies the maximum number of outstanding aio requests that
390	this function generates. If it is C<< <= 0 >>, then a suitable default	683	this function generates. If it is C<< <= 0 >>, then a suitable default
391	will be chosen (currently 6).	684	will be chosen (currently 4).
392		685
393	On error, the callback is called without arguments, otherwise it receives	686	On error, the callback is called without arguments, otherwise it receives
394	two array-refs with path-relative entry names.	687	two array-refs with path-relative entry names.
395		688
396	Example:	689	Example:
…		…
430	as those tend to return 0 or 1 as link counts, which disables the	723	as those tend to return 0 or 1 as link counts, which disables the
431	directory counting heuristic.	724	directory counting heuristic.
432		725
433	=cut	726	=cut
434		727
435	sub aio_scandir($$$) {	728	sub aio_scandir($$;$) {
436	my ($path, $maxreq, $cb) = @_;	729	my ($path, $maxreq, $cb) = @_;
437		730
		731	my $pri = aioreq_pri;
		732
438	my $grp = aio_group $cb;	733	my $grp = aio_group $cb;
439		734
440	$maxreq = 6 if $maxreq <= 0;	735	$maxreq = 4 if $maxreq <= 0;
441		736
442	# stat once	737	# stat once
		738	aioreq_pri $pri;
443	add $grp aio_stat $path, sub {	739	add $grp aio_stat $path, sub {
444	return $grp->result () if $_[0];	740	return $grp->result () if $_[0];
445	my $now = time;	741	my $now = time;
446	my $hash1 = join ":", (stat _)[0,1,3,7,9];	742	my $hash1 = join ":", (stat _)[0,1,3,7,9];
447		743
448	# read the directory entries	744	# read the directory entries
		745	aioreq_pri $pri;
449	add $grp aio_readdir $path, sub {	746	add $grp aio_readdir $path, sub {
450	my $entries = shift	747	my $entries = shift
451	or return $grp->result ();	748	or return $grp->result ();
452		749
453	# stat the dir another time	750	# stat the dir another time
		751	aioreq_pri $pri;
454	add $grp aio_stat $path, sub {	752	add $grp aio_stat $path, sub {
455	my $hash2 = join ":", (stat _)[0,1,3,7,9];	753	my $hash2 = join ":", (stat _)[0,1,3,7,9];
456		754
457	my $ndirs;	755	my $ndirs;
458		756
…		…
473	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	771	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
474	@$entries];	772	@$entries];
475		773
476	my (@dirs, @nondirs);	774	my (@dirs, @nondirs);
477		775
478	my ($statcb, $schedcb);
479	my $nreq = 0;
480
481	my $statgrp = add $grp aio_group;	776	my $statgrp = add $grp aio_group sub {
		777	$grp->result (\@dirs, \@nondirs);
		778	};
482		779
483	$schedcb = sub {	780	limit $statgrp $maxreq;
484	if (@$entries) {	781	feed $statgrp sub {
485	if ($nreq < $maxreq) {	782	return unless @$entries;
486	my $ent = pop @$entries;	783	my $entry = pop @$entries;
		784
		785	aioreq_pri $pri;
		786	add $statgrp aio_stat "$path/$entry/.", sub {
		787	if ($_[0] < 0) {
		788	push @nondirs, $entry;
		789	} else {
		790	# need to check for real directory
		791	aioreq_pri $pri;
		792	add $statgrp aio_lstat "$path/$entry", sub {
		793	if (-d _) {
		794	push @dirs, $entry;
		795
		796	unless (--$ndirs) {
		797	push @nondirs, @$entries;
		798	feed $statgrp;
		799	}
		800	} else {
		801	push @nondirs, $entry;
		802	}
487	$nreq++;	803	}
488	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
489	}	804	}
490	} elsif (!$nreq) {
491	# finished
492	$statgrp->cancel;
493	undef $statcb;
494	undef $schedcb;
495	$grp->result (\@dirs, \@nondirs);
496	}	805	};
497	};	806	};
498	$statcb = sub {
499	my ($status, $entry) = @_;
500
501	if ($status < 0) {
502	$nreq--;
503	push @nondirs, $entry;
504	&$schedcb;
505	} else {
506	# need to check for real directory
507	add $grp aio_lstat "$path/$entry", sub {
508	$nreq--;
509
510	if (-d _) {
511	push @dirs, $entry;
512
513	if (!--$ndirs) {
514	push @nondirs, @$entries;
515	$entries = [];
516	}
517	} else {
518	push @nondirs, $entry;
519	}
520
521	&$schedcb;
522	}
523	}
524	};
525
526	&$schedcb while @$entries && $nreq < $maxreq;
527	};	807	};
528	};	808	};
529	};	809	};
530		810
531	$grp	811	$grp
532	}	812	}
533		813
		814	=item aio_rmtree $path, $callback->($status)
		815
		816	Delete a directory tree starting (and including) C<$path>, return the
		817	status of the final C<rmdir> only. This is a composite request that
		818	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		819	everything else.
		820
		821	=cut
		822
		823	sub aio_rmtree;
		824	sub aio_rmtree($;$) {
		825	my ($path, $cb) = @_;
		826
		827	my $pri = aioreq_pri;
		828	my $grp = aio_group $cb;
		829
		830	aioreq_pri $pri;
		831	add $grp aio_scandir $path, 0, sub {
		832	my ($dirs, $nondirs) = @_;
		833
		834	my $dirgrp = aio_group sub {
		835	add $grp aio_rmdir $path, sub {
		836	$grp->result ($_[0]);
		837	};
		838	};
		839
		840	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		841	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		842
		843	add $grp $dirgrp;
		844	};
		845
		846	$grp
		847	}
		848
		849	=item aio_sync $callback->($status)
		850
		851	Asynchronously call sync and call the callback when finished.
		852
534	=item aio_fsync $fh, $callback->($status)	853	=item aio_fsync $fh, $callback->($status)
535		854
536	Asynchronously call fsync on the given filehandle and call the callback	855	Asynchronously call fsync on the given filehandle and call the callback
537	with the fsync result code.	856	with the fsync result code.
538		857
…		…
542	callback with the fdatasync result code.	861	callback with the fdatasync result code.
543		862
544	If this call isn't available because your OS lacks it or it couldn't be	863	If this call isn't available because your OS lacks it or it couldn't be
545	detected, it will be emulated by calling C<fsync> instead.	864	detected, it will be emulated by calling C<fsync> instead.
546		865
		866	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		867
		868	Sync the data portion of the file specified by C<$offset> and C<$length>
		869	to disk (but NOT the metadata), by calling the Linux-specific
		870	sync_file_range call. If sync_file_range is not available or it returns
		871	ENOSYS, then fdatasync or fsync is being substituted.
		872
		873	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		874	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		875	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		876	manpage for details.
		877
		878	=item aio_pathsync $path, $callback->($status)
		879
		880	This request tries to open, fsync and close the given path. This is a
		881	composite request intended to sync directories after directory operations
		882	(E.g. rename). This might not work on all operating systems or have any
		883	specific effect, but usually it makes sure that directory changes get
		884	written to disc. It works for anything that can be opened for read-only,
		885	not just directories.
		886
		887	Passes C<0> when everything went ok, and C<-1> on error.
		888
		889	=cut
		890
		891	sub aio_pathsync($;$) {
		892	my ($path, $cb) = @_;
		893
		894	my $pri = aioreq_pri;
		895	my $grp = aio_group $cb;
		896
		897	aioreq_pri $pri;
		898	add $grp aio_open $path, O_RDONLY, 0, sub {
		899	my ($fh) = @_;
		900	if ($fh) {
		901	aioreq_pri $pri;
		902	add $grp aio_fsync $fh, sub {
		903	$grp->result ($_[0]);
		904
		905	aioreq_pri $pri;
		906	add $grp aio_close $fh;
		907	};
		908	} else {
		909	$grp->result (-1);
		910	}
		911	};
		912
		913	$grp
		914	}
		915
547	=item aio_group $callback->(...)	916	=item aio_group $callback->(...)
548
549	[EXPERIMENTAL]
550		917
551	This is a very special aio request: Instead of doing something, it is a	918	This is a very special aio request: Instead of doing something, it is a
552	container for other aio requests, which is useful if you want to bundle	919	container for other aio requests, which is useful if you want to bundle
553	many requests into a single, composite, request.	920	many requests into a single, composite, request with a definite callback
		921	and the ability to cancel the whole request with its subrequests.
554		922
555	Returns an object of class L<IO::AIO::GRP>. See its documentation below	923	Returns an object of class L<IO::AIO::GRP>. See its documentation below
556	for more info.	924	for more info.
557		925
558	Example:	926	Example:
…		…
577	phase and still requires a worker thread. Thus, the callback will not	945	phase and still requires a worker thread. Thus, the callback will not
578	be executed immediately but only after other requests in the queue have	946	be executed immediately but only after other requests in the queue have
579	entered their execution phase. This can be used to measure request	947	entered their execution phase. This can be used to measure request
580	latency.	948	latency.
581		949
582	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	950	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
583		951
584	Mainly used for debugging and benchmarking, this aio request puts one of	952	Mainly used for debugging and benchmarking, this aio request puts one of
585	the request workers to sleep for the given time.	953	the request workers to sleep for the given time.
586		954
587	While it is theoretically handy to have simple I/O scheduling requests	955	While it is theoretically handy to have simple I/O scheduling requests
588	like sleep and file handle readable/writable, the overhead this creates	956	like sleep and file handle readable/writable, the overhead this creates is
589	is immense, so do not use this function except to put your application	957	immense (it blocks a thread for a long time) so do not use this function
590	under artificial I/O pressure.	958	except to put your application under artificial I/O pressure.
591		959
592	=back	960	=back
593		961
594	=head2 IO::AIO::REQ CLASS	962	=head2 IO::AIO::REQ CLASS
595		963
596	All non-aggregate C<aio_*> functions return an object of this class when	964	All non-aggregate C<aio_*> functions return an object of this class when
597	called in non-void context.	965	called in non-void context.
598
599	A request always moves through the following five states in its lifetime,
600	in order: B<ready> (request has been created, but has not been executed
601	yet), B<execute> (request is currently being executed), B<pending>
602	(request has been executed but callback has not been called yet),
603	B<result> (results are being processed synchronously, includes calling the
604	callback) and B<done> (request has reached the end of its lifetime and
605	holds no resources anymore).
606		966
607	=over 4	967	=over 4
608		968
609	=item cancel $req	969	=item cancel $req
610		970
…		…
664	=item * They can also can also be added to other IO::AIO::GRP objects.	1024	=item * They can also can also be added to other IO::AIO::GRP objects.
665		1025
666	=item * You must not add requests to a group from within the group callback (or	1026	=item * You must not add requests to a group from within the group callback (or
667	any later time).	1027	any later time).
668		1028
669	=item * This does not harmonise well with C<max_outstanding>, so best do
670	not combine C<aio_group> with it. Groups and feeders are recommended for
671	this kind of concurrency-limiting.
672
673	=back	1029	=back
674		1030
675	Their lifetime, simplified, looks like this: when they are empty, they	1031	Their lifetime, simplified, looks like this: when they are empty, they
676	will finish very quickly. If they contain only requests that are in the	1032	will finish very quickly. If they contain only requests that are in the
677	C<done> state, they will also finish. Otherwise they will continue to	1033	C<done> state, they will also finish. Otherwise they will continue to
678	exist.	1034	exist.
679		1035
680	That means after creating a group you have some time to add requests. And	1036	That means after creating a group you have some time to add requests
681	in the callbacks of those requests, you can add further requests to the	1037	(precisely before the callback has been invoked, which is only done within
682	group. And only when all those requests have finished will the the group	1038	the C<poll_cb>). And in the callbacks of those requests, you can add
683	itself finish.	1039	further requests to the group. And only when all those requests have
		1040	finished will the the group itself finish.
684		1041
685	=over 4	1042	=over 4
686		1043
687	=item add $grp ...	1044	=item add $grp ...
688		1045
…		…
692	be added, including other groups, as long as you do not create circular	1049	be added, including other groups, as long as you do not create circular
693	dependencies.	1050	dependencies.
694		1051
695	Returns all its arguments.	1052	Returns all its arguments.
696		1053
		1054	=item $grp->cancel_subs
		1055
		1056	Cancel all subrequests and clears any feeder, but not the group request
		1057	itself. Useful when you queued a lot of events but got a result early.
		1058
697	=item $grp->result (...)	1059	=item $grp->result (...)
698		1060
699	Set the result value(s) that will be passed to the group callback when all	1061	Set the result value(s) that will be passed to the group callback when all
700	subrequests have finished. By default, no argument will be passed.	1062	subrequests have finished and set the groups errno to the current value
		1063	of errno (just like calling C<errno> without an error number). By default,
		1064	no argument will be passed and errno is zero.
		1065
		1066	=item $grp->errno ([$errno])
		1067
		1068	Sets the group errno value to C<$errno>, or the current value of errno
		1069	when the argument is missing.
		1070
		1071	Every aio request has an associated errno value that is restored when
		1072	the callback is invoked. This method lets you change this value from its
		1073	default (0).
		1074
		1075	Calling C<result> will also set errno, so make sure you either set C<$!>
		1076	before the call to C<result>, or call c<errno> after it.
701		1077
702	=item feed $grp $callback->($grp)	1078	=item feed $grp $callback->($grp)
703
704	[VERY EXPERIMENTAL]
705		1079
706	Sets a feeder/generator on this group: every group can have an attached	1080	Sets a feeder/generator on this group: every group can have an attached
707	generator that generates requests if idle. The idea behind this is that,	1081	generator that generates requests if idle. The idea behind this is that,
708	although you could just queue as many requests as you want in a group,	1082	although you could just queue as many requests as you want in a group,
709	this might starve other requests for a potentially long time. For	1083	this might starve other requests for a potentially long time. For example,
710	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1084	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
711	requests, delaying any later requests for a long time.	1085	delaying any later requests for a long time.
712		1086
713	To avoid this, and allow incremental generation of requests, you can	1087	To avoid this, and allow incremental generation of requests, you can
714	instead a group and set a feeder on it that generates those requests. The	1088	instead a group and set a feeder on it that generates those requests. The
715	feed callback will be called whenever there are few enough (see C<limit>,	1089	feed callback will be called whenever there are few enough (see C<limit>,
716	below) requests active in the group itself and is expected to queue more	1090	below) requests active in the group itself and is expected to queue more
…		…
720	not impose any limits).	1094	not impose any limits).
721		1095
722	If the feed does not queue more requests when called, it will be	1096	If the feed does not queue more requests when called, it will be
723	automatically removed from the group.	1097	automatically removed from the group.
724		1098
725	If the feed limit is C<0>, it will be set to C<2> automatically.	1099	If the feed limit is C<0> when this method is called, it will be set to
		1100	C<2> automatically.
726		1101
727	Example:	1102	Example:
728		1103
729	# stat all files in @files, but only ever use four aio requests concurrently:	1104	# stat all files in @files, but only ever use four aio requests concurrently:
730		1105
…		…
742	Sets the feeder limit for the group: The feeder will be called whenever	1117	Sets the feeder limit for the group: The feeder will be called whenever
743	the group contains less than this many requests.	1118	the group contains less than this many requests.
744		1119
745	Setting the limit to C<0> will pause the feeding process.	1120	Setting the limit to C<0> will pause the feeding process.
746		1121
		1122	The default value for the limit is C<0>, but note that setting a feeder
		1123	automatically bumps it up to C<2>.
		1124
747	=back	1125	=back
748		1126
749	=head2 SUPPORT FUNCTIONS	1127	=head2 SUPPORT FUNCTIONS
		1128
		1129	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
750		1130
751	=over 4	1131	=over 4
752		1132
753	=item $fileno = IO::AIO::poll_fileno	1133	=item $fileno = IO::AIO::poll_fileno
754		1134
…		…
759		1139
760	See C<poll_cb> for an example.	1140	See C<poll_cb> for an example.
761		1141
762	=item IO::AIO::poll_cb	1142	=item IO::AIO::poll_cb
763		1143
764	Process all outstanding events on the result pipe. You have to call this	1144	Process some outstanding events on the result pipe. You have to call this
765	regularly. Returns the number of events processed. Returns immediately	1145	regularly. Returns C<0> if all events could be processed, or C<-1> if it
766	when no events are outstanding.	1146	returned earlier for whatever reason. Returns immediately when no events
		1147	are outstanding. The amount of events processed depends on the settings of
		1148	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1149
		1150	If not all requests were processed for whatever reason, the filehandle
		1151	will still be ready when C<poll_cb> returns, so normally you don't have to
		1152	do anything special to have it called later.
767		1153
768	Example: Install an Event watcher that automatically calls	1154	Example: Install an Event watcher that automatically calls
769	IO::AIO::poll_cb with high priority:	1155	IO::AIO::poll_cb with high priority:
770		1156
771	Event->io (fd => IO::AIO::poll_fileno,	1157	Event->io (fd => IO::AIO::poll_fileno,
772	poll => 'r', async => 1,	1158	poll => 'r', async => 1,
773	cb => \&IO::AIO::poll_cb);	1159	cb => \&IO::AIO::poll_cb);
774		1160
		1161	=item IO::AIO::max_poll_reqs $nreqs
		1162
		1163	=item IO::AIO::max_poll_time $seconds
		1164
		1165	These set the maximum number of requests (default C<0>, meaning infinity)
		1166	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1167	the maximum amount of time (default C<0>, meaning infinity) spent in
		1168	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1169	of time C<poll_cb> is allowed to use).
		1170
		1171	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1172	syscall per request processed, which is not normally a problem unless your
		1173	callbacks are really really fast or your OS is really really slow (I am
		1174	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1175
		1176	Setting these is useful if you want to ensure some level of
		1177	interactiveness when perl is not fast enough to process all requests in
		1178	time.
		1179
		1180	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1181
		1182	Example: Install an Event watcher that automatically calls
		1183	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1184	program get the CPU sometimes even under high AIO load.
		1185
		1186	# try not to spend much more than 0.1s in poll_cb
		1187	IO::AIO::max_poll_time 0.1;
		1188
		1189	# use a low priority so other tasks have priority
		1190	Event->io (fd => IO::AIO::poll_fileno,
		1191	poll => 'r', nice => 1,
		1192	cb => &IO::AIO::poll_cb);
		1193
775	=item IO::AIO::poll_wait	1194	=item IO::AIO::poll_wait
776		1195
		1196	If there are any outstanding requests and none of them in the result
777	Wait till the result filehandle becomes ready for reading (simply does a	1197	phase, wait till the result filehandle becomes ready for reading (simply
778	C<select> on the filehandle. This is useful if you want to synchronously wait	1198	does a C<select> on the filehandle. This is useful if you want to
779	for some requests to finish).	1199	synchronously wait for some requests to finish).
780		1200
781	See C<nreqs> for an example.	1201	See C<nreqs> for an example.
782		1202
		1203	=item IO::AIO::poll
		1204
		1205	Waits until some requests have been handled.
		1206
		1207	Returns the number of requests processed, but is otherwise strictly
		1208	equivalent to:
		1209
		1210	IO::AIO::poll_wait, IO::AIO::poll_cb
		1211
783	=item IO::AIO::nreqs	1212	=item IO::AIO::flush
784		1213
785	Returns the number of requests currently outstanding (i.e. for which their	1214	Wait till all outstanding AIO requests have been handled.
786	callback has not been invoked yet).
787		1215
788	Example: wait till there are no outstanding requests anymore:	1216	Strictly equivalent to:
789		1217
790	IO::AIO::poll_wait, IO::AIO::poll_cb	1218	IO::AIO::poll_wait, IO::AIO::poll_cb
791	while IO::AIO::nreqs;	1219	while IO::AIO::nreqs;
792		1220
793	=item IO::AIO::flush	1221	=back
794		1222
795	Wait till all outstanding AIO requests have been handled.	1223	=head3 CONTROLLING THE NUMBER OF THREADS
796		1224
797	Strictly equivalent to:	1225	=over
798
799	IO::AIO::poll_wait, IO::AIO::poll_cb
800	while IO::AIO::nreqs;
801
802	=item IO::AIO::poll
803
804	Waits until some requests have been handled.
805
806	Strictly equivalent to:
807
808	IO::AIO::poll_wait, IO::AIO::poll_cb
809	if IO::AIO::nreqs;
810		1226
811	=item IO::AIO::min_parallel $nthreads	1227	=item IO::AIO::min_parallel $nthreads
812		1228
813	Set the minimum number of AIO threads to C<$nthreads>. The current	1229	Set the minimum number of AIO threads to C<$nthreads>. The current
814	default is C<8>, which means eight asynchronous operations can execute	1230	default is C<8>, which means eight asynchronous operations can execute
815	concurrently at any one time (the number of outstanding requests,	1231	concurrently at any one time (the number of outstanding requests,
816	however, is unlimited).	1232	however, is unlimited).
817		1233
818	IO::AIO starts threads only on demand, when an AIO request is queued and	1234	IO::AIO starts threads only on demand, when an AIO request is queued and
819	no free thread exists.	1235	no free thread exists. Please note that queueing up a hundred requests can
		1236	create demand for a hundred threads, even if it turns out that everything
		1237	is in the cache and could have been processed faster by a single thread.
820		1238
821	It is recommended to keep the number of threads relatively low, as some	1239	It is recommended to keep the number of threads relatively low, as some
822	Linux kernel versions will scale negatively with the number of threads	1240	Linux kernel versions will scale negatively with the number of threads
823	(higher parallelity => MUCH higher latency). With current Linux 2.6	1241	(higher parallelity => MUCH higher latency). With current Linux 2.6
824	versions, 4-32 threads should be fine.	1242	versions, 4-32 threads should be fine.
…		…
838	This module automatically runs C<max_parallel 0> at program end, to ensure	1256	This module automatically runs C<max_parallel 0> at program end, to ensure
839	that all threads are killed and that there are no outstanding requests.	1257	that all threads are killed and that there are no outstanding requests.
840		1258
841	Under normal circumstances you don't need to call this function.	1259	Under normal circumstances you don't need to call this function.
842		1260
		1261	=item IO::AIO::max_idle $nthreads
		1262
		1263	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1264	threads that did not get a request to process within 10 seconds). That
		1265	means if a thread becomes idle while C<$nthreads> other threads are also
		1266	idle, it will free its resources and exit.
		1267
		1268	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1269	to allow for extremely high load situations, but want to free resources
		1270	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1271
		1272	The default is probably ok in most situations, especially if thread
		1273	creation is fast. If thread creation is very slow on your system you might
		1274	want to use larger values.
		1275
843	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1276	=item IO::AIO::max_outstanding $maxreqs
844		1277
845	[DEPRECATED]	1278	This is a very bad function to use in interactive programs because it
		1279	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1280	use an C<aio_group> together with a feed callback.
846		1281
847	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1282	Sets the maximum number of outstanding requests to C<$nreqs>. If you
848	try to queue up more than this number of requests, the caller will block until	1283	do queue up more than this number of requests, the next call to the
849	some requests have been handled.	1284	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1285	function will block until the limit is no longer exceeded.
850		1286
851	The default is very large, so normally there is no practical limit. If you	1287	The default value is very large, so there is no practical limit on the
852	queue up many requests in a loop it often improves speed if you set	1288	number of outstanding requests.
853	this to a relatively low number, such as C<100>.
854		1289
855	This function does not work well together with C<aio_group>'s, and their	1290	You can still queue as many requests as you want. Therefore,
856	feeder interface is better suited to limiting concurrency, so do not use	1291	C<max_outstanding> is mainly useful in simple scripts (with low values) or
857	this function.	1292	as a stop gap to shield against fatal memory overflow (with large values).
858
859	Under normal circumstances you don't need to call this function.
860		1293
861	=back	1294	=back
862		1295
		1296	=head3 STATISTICAL INFORMATION
		1297
		1298	=over
		1299
		1300	=item IO::AIO::nreqs
		1301
		1302	Returns the number of requests currently in the ready, execute or pending
		1303	states (i.e. for which their callback has not been invoked yet).
		1304
		1305	Example: wait till there are no outstanding requests anymore:
		1306
		1307	IO::AIO::poll_wait, IO::AIO::poll_cb
		1308	while IO::AIO::nreqs;
		1309
		1310	=item IO::AIO::nready
		1311
		1312	Returns the number of requests currently in the ready state (not yet
		1313	executed).
		1314
		1315	=item IO::AIO::npending
		1316
		1317	Returns the number of requests currently in the pending state (executed,
		1318	but not yet processed by poll_cb).
		1319
		1320	=back
		1321
863	=cut	1322	=cut
864		1323
865	# support function to convert a fd into a perl filehandle
866	sub _fd2fh {
867	return undef if $_[0] < 0;
868
869	# try to generate nice filehandles
870	my $sym = "IO::AIO::fd#$_[0]";
871	local *$sym;
872
873	open *$sym, "+<&=$_[0]" # usually works under any unix
874	or open *$sym, "<&=$_[0]" # cygwin needs this
875	or open *$sym, ">&=$_[0]" # or this
876	or return undef;
877
878	*$sym
879	}
880
881	min_parallel 8;	1324	min_parallel 8;
882		1325
883	END {	1326	END { flush }
884	max_parallel 0;
885	}
886		1327
887	1;	1328	1;
888		1329
889	=head2 FORK BEHAVIOUR	1330	=head2 FORK BEHAVIOUR
890		1331
891	This module should do "the right thing" when the process using it forks:	1332	This module should do "the right thing" when the process using it forks:
892		1333
893	Before the fork, IO::AIO enters a quiescent state where no requests	1334	Before the fork, IO::AIO enters a quiescent state where no requests
894	can be added in other threads and no results will be processed. After	1335	can be added in other threads and no results will be processed. After
895	the fork the parent simply leaves the quiescent state and continues	1336	the fork the parent simply leaves the quiescent state and continues
896	request/result processing, while the child clears the request/result	1337	request/result processing, while the child frees the request/result queue
897	queue (so the requests started before the fork will only be handled in	1338	(so that the requests started before the fork will only be handled in the
898	the parent). Threads will be started on demand until the limit ste in the	1339	parent). Threads will be started on demand until the limit set in the
899	parent process has been reached again.	1340	parent process has been reached again.
900		1341
901	In short: the parent will, after a short pause, continue as if fork had	1342	In short: the parent will, after a short pause, continue as if fork had
902	not been called, while the child will act as if IO::AIO has not been used	1343	not been called, while the child will act as if IO::AIO has not been used
903	yet.	1344	yet.
904		1345
905	=head2 MEMORY USAGE	1346	=head2 MEMORY USAGE
906		1347
		1348	Per-request usage:
		1349
907	Each aio request uses - depending on your architecture - around 128 bytes	1350	Each aio request uses - depending on your architecture - around 100-200
908	of memory. In addition, stat requests need a stat buffer (possibly a few	1351	bytes of memory. In addition, stat requests need a stat buffer (possibly
909	hundred bytes). Perl scalars and other data passed into aio requests will	1352	a few hundred bytes), readdir requires a result buffer and so on. Perl
910	also be locked.	1353	scalars and other data passed into aio requests will also be locked and
		1354	will consume memory till the request has entered the done state.
911		1355
912	This is now awfully much, so queuing lots of requests is not usually a	1356	This is not awfully much, so queuing lots of requests is not usually a
913	problem.	1357	problem.
914		1358
915	Each thread needs a stack area which is usually around 16k, sometimes much	1359	Per-thread usage:
916	larger, depending on the OS.	1360
		1361	In the execution phase, some aio requests require more memory for
		1362	temporary buffers, and each thread requires a stack and other data
		1363	structures (usually around 16k-128k, depending on the OS).
		1364
		1365	=head1 KNOWN BUGS
		1366
		1367	Known bugs will be fixed in the next release.
917		1368
918	=head1 SEE ALSO	1369	=head1 SEE ALSO
919		1370
920	L<Coro::AIO>.	1371	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1372	more natural syntax.
921		1373
922	=head1 AUTHOR	1374	=head1 AUTHOR
923		1375
924	Marc Lehmann <schmorp@schmorp.de>	1376	Marc Lehmann <schmorp@schmorp.de>
925	http://home.schmorp.de/	1377	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs. Revision 1.146 by root, Tue Apr 21 20:06:05 2009 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.146 by root, Tue Apr 21 20:06:05 2009 UTC