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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.69 by root, Tue Oct 24 03:40:25 2006 UTC vs.
Revision 1.141 by root, Wed Oct 22 16:30:49 2008 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 = '3.16';
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_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));	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);
89		213
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	214	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		215
92	require XSLoader;	216	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	217	XSLoader::load ("IO::AIO", $VERSION);
94	}	218	}
95		219
96	=head1 FUNCTIONS	220	=head1 FUNCTIONS
97		221
98	=head2 AIO FUNCTIONS	222	=head2 AIO REQUEST FUNCTIONS
99		223
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	224	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	225	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	226	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	227	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	228	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	229	perl, which usually delivers "false") as its sole argument after the given
106	syscall has been executed asynchronously.	230	syscall has been executed asynchronously.
107		231
108	All functions expecting a filehandle keep a copy of the filehandle	232	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	233	internally until the request has finished.
110		234
111	All requests return objects of type L<IO::AIO::REQ> that allow further	235	All functions return request objects of type L<IO::AIO::REQ> that allow
112	manipulation of those requests while they are in-flight.	236	further manipulation of those requests while they are in-flight.
113		237
114	The pathnames you pass to these routines I<must> be absolute and	238	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	239	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	240	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	241	changed. Alternatively, you can make sure that you never change the
118	current working directory.	242	current working directory anywhere in the program and then use relative
		243	paths.
119		244
120	To encode pathnames to byte form, either make sure you either: a)	245	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	246	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	247	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	248	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)	249	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	250	use something else to ensure your scalar has the correct contents.
		251
		252	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		253	handles correctly whether it is set or not.
126		254
127	=over 4	255	=over 4
128		256
129	=item aioreq_pri $pri	257	=item $prev_pri = aioreq_pri [$pri]
130		258
131	Sets the priority for the next aio request. The default priority	259	Returns the priority value that would be used for the next request and, if
		260	C<$pri> is given, sets the priority for the next aio request.
		261
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	262	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	263	and C<4>, respectively. Requests with higher priority will be serviced
		264	first.
134		265
135	The priority will be reset to C<0> after each call to one of the C<aio_>	266	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	267	functions.
137		268
138	Example: open a file with low priority, then read something from it with	269	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	270	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	271	open requests (potentially spamming the cache):
…		…
147	aio_read $_[0], ..., sub {	278	aio_read $_[0], ..., sub {
148	...	279	...
149	};	280	};
150	};	281	};
151		282
		283
152	=item aioreq_nice $pri_adjust	284	=item aioreq_nice $pri_adjust
153		285
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	286	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	287	priority, so the effect is cumulative.
		288
156		289
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	290	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		291
159	Asynchronously open or create a file and call the callback with a newly	292	Asynchronously open or create a file and call the callback with a newly
160	created filehandle for the file.	293	created filehandle for the file.
…		…
166	list. They are the same as used by C<sysopen>.	299	list. They are the same as used by C<sysopen>.
167		300
168	Likewise, C<$mode> specifies the mode of the newly created file, if it	301	Likewise, C<$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>,	302	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,	303	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).	304	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		305	by the umask in effect then the request is being executed, so better never
		306	change the umask.
172		307
173	Example:	308	Example:
174		309
175	aio_open "/etc/passwd", O_RDONLY, 0, sub {	310	aio_open "/etc/passwd", O_RDONLY, 0, sub {
176	if ($_[0]) {	311	if ($_[0]) {
…		…
179	} else {	314	} else {
180	die "open failed: $!\n";	315	die "open failed: $!\n";
181	}	316	}
182	};	317	};
183		318
		319
184	=item aio_close $fh, $callback->($status)	320	=item aio_close $fh, $callback->($status)
185		321
186	Asynchronously close a file and call the callback with the result	322	Asynchronously close a file and call the callback with the result
187	code. I<WARNING:> although accepted, you should not pass in a perl	323	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		324
192	This is supposed to be a bug in the API, so that might change. It's	325	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
193	therefore best to avoid this function.	326	closing the file descriptor associated with the filehandle itself.
		327
		328	Therefore, C<aio_close> will not close the filehandle - instead it will
		329	use dup2 to overwrite the file descriptor with the write-end of a pipe
		330	(the pipe fd will be created on demand and will be cached).
		331
		332	Or in other words: the file descriptor will be closed, but it will not be
		333	free for reuse until the perl filehandle is closed.
		334
		335	=cut
194		336
195	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	337	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
196		338
197	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	339	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
198		340
199	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	341	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
200	into the scalar given by C<data> and offset C<dataoffset> and calls the	342	into the scalar given by C<$data> and offset C<$dataoffset> and calls the
201	callback without the actual number of bytes read (or -1 on error, just	343	callback without the actual number of bytes read (or -1 on error, just
202	like the syscall).	344	like the syscall).
203		345
		346	If C<$offset> is undefined, then the current file descriptor offset will
		347	be used (and updated), otherwise the file descriptor offset will not be
		348	changed by these calls.
		349
		350	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
		351
		352	If C<$dataoffset> is less than zero, it will be counted from the end of
		353	C<$data>.
		354
204	The C<$data> scalar I<MUST NOT> be modified in any way while the request	355	The C<$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	356	is outstanding. Modifying it can result in segfaults or World War III (if
206	necessary/optional hardware is installed).	357	the necessary/optional hardware is installed).
207		358
208	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	359	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
209	offset C<0> within the scalar:	360	offset C<0> within the scalar:
210		361
211	aio_read $fh, 7, 15, $buffer, 0, sub {	362	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	363	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	364	print "read $_[0] bytes: <$buffer>\n";
214	};	365	};
215		366
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		367
286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	368	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
287		369
288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	370	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	371	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	385	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	386	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	387	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	388	value equals C<$length> one can assume that C<$length> bytes have been
307	read.	389	read.
		390
308		391
309	=item aio_readahead $fh,$offset,$length, $callback->($retval)	392	=item aio_readahead $fh,$offset,$length, $callback->($retval)
310		393
311	C<aio_readahead> populates the page cache with data from a file so that	394	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>	395	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.	401	file. The current file offset of the file is left unchanged.
319		402
320	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	403	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.	404	emulated by simply reading the data, which would have a similar effect.
322		405
		406
323	=item aio_stat $fh_or_path, $callback->($status)	407	=item aio_stat $fh_or_path, $callback->($status)
324		408
325	=item aio_lstat $fh, $callback->($status)	409	=item aio_lstat $fh, $callback->($status)
326		410
327	Works like perl's C<stat> or C<lstat> in void context. The callback will	411	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
340	aio_stat "/etc/passwd", sub {	424	aio_stat "/etc/passwd", sub {
341	$_[0] and die "stat failed: $!";	425	$_[0] and die "stat failed: $!";
342	print "size is ", -s _, "\n";	426	print "size is ", -s _, "\n";
343	};	427	};
344		428
		429
		430	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		431
		432	Works like perl's C<utime> function (including the special case of $atime
		433	and $mtime being undef). Fractional times are supported if the underlying
		434	syscalls support them.
		435
		436	When called with a pathname, uses utimes(2) if available, otherwise
		437	utime(2). If called on a file descriptor, uses futimes(2) if available,
		438	otherwise returns ENOSYS, so this is not portable.
		439
		440	Examples:
		441
		442	# set atime and mtime to current time (basically touch(1)):
		443	aio_utime "path", undef, undef;
		444	# set atime to current time and mtime to beginning of the epoch:
		445	aio_utime "path", time, undef; # undef==0
		446
		447
		448	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		449
		450	Works like perl's C<chown> function, except that C<undef> for either $uid
		451	or $gid is being interpreted as "do not change" (but -1 can also be used).
		452
		453	Examples:
		454
		455	# same as "chown root path" in the shell:
		456	aio_chown "path", 0, -1;
		457	# same as above:
		458	aio_chown "path", 0, undef;
		459
		460
		461	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		462
		463	Works like truncate(2) or ftruncate(2).
		464
		465
		466	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		467
		468	Works like perl's C<chmod> function.
		469
		470
345	=item aio_unlink $pathname, $callback->($status)	471	=item aio_unlink $pathname, $callback->($status)
346		472
347	Asynchronously unlink (delete) a file and call the callback with the	473	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	474	result code.
349		475
		476
		477	=item aio_mknod $path, $mode, $dev, $callback->($status)
		478
		479	[EXPERIMENTAL]
		480
		481	Asynchronously create a device node (or fifo). See mknod(2).
		482
		483	The only (POSIX-) portable way of calling this function is:
		484
		485	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		486
		487
350	=item aio_link $srcpath, $dstpath, $callback->($status)	488	=item aio_link $srcpath, $dstpath, $callback->($status)
351		489
352	Asynchronously create a new link to the existing object at C<$srcpath> at	490	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.	491	the path C<$dstpath> and call the callback with the result code.
354		492
		493
355	=item aio_symlink $srcpath, $dstpath, $callback->($status)	494	=item aio_symlink $srcpath, $dstpath, $callback->($status)
356		495
357	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	496	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.	497	the path C<$dstpath> and call the callback with the result code.
359		498
		499
		500	=item aio_readlink $path, $callback->($link)
		501
		502	Asynchronously read the symlink specified by C<$path> and pass it to
		503	the callback. If an error occurs, nothing or undef gets passed to the
		504	callback.
		505
		506
360	=item aio_rename $srcpath, $dstpath, $callback->($status)	507	=item aio_rename $srcpath, $dstpath, $callback->($status)
361		508
362	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	509	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
363	rename(2) and call the callback with the result code.	510	rename(2) and call the callback with the result code.
364		511
		512
		513	=item aio_mkdir $pathname, $mode, $callback->($status)
		514
		515	Asynchronously mkdir (create) a directory and call the callback with
		516	the result code. C<$mode> will be modified by the umask at the time the
		517	request is executed, so do not change your umask.
		518
		519
365	=item aio_rmdir $pathname, $callback->($status)	520	=item aio_rmdir $pathname, $callback->($status)
366		521
367	Asynchronously rmdir (delete) a directory and call the callback with the	522	Asynchronously rmdir (delete) a directory and call the callback with the
368	result code.	523	result code.
		524
369		525
370	=item aio_readdir $pathname, $callback->($entries)	526	=item aio_readdir $pathname, $callback->($entries)
371		527
372	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	528	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	529	directory (i.e. opendir + readdir + closedir). The entries will not be
374	sorted, and will B<NOT> include the C<.> and C<..> entries.	530	sorted, and will B<NOT> include the C<.> and C<..> entries.
375		531
376	The callback a single argument which is either C<undef> or an array-ref	532	The callback a single argument which is either C<undef> or an array-ref
377	with the filenames.	533	with the filenames.
378		534
		535
		536	=item aio_load $path, $data, $callback->($status)
		537
		538	This is a composite request that tries to fully load the given file into
		539	memory. Status is the same as with aio_read.
		540
		541	=cut
		542
		543	sub aio_load($$;$) {
		544	my ($path, undef, $cb) = @_;
		545	my $data = \$_[1];
		546
		547	my $pri = aioreq_pri;
		548	my $grp = aio_group $cb;
		549
		550	aioreq_pri $pri;
		551	add $grp aio_open $path, O_RDONLY, 0, sub {
		552	my $fh = shift
		553	or return $grp->result (-1);
		554
		555	aioreq_pri $pri;
		556	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		557	$grp->result ($_[0]);
		558	};
		559	};
		560
		561	$grp
		562	}
		563
		564	=item aio_copy $srcpath, $dstpath, $callback->($status)
		565
		566	Try to copy the I<file> (directories not supported as either source or
		567	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		568	the C<0> (error) or C<-1> ok.
		569
		570	This is a composite request that creates the destination file with
		571	mode 0200 and copies the contents of the source file into it using
		572	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		573	uid/gid, in that order.
		574
		575	If an error occurs, the partial destination file will be unlinked, if
		576	possible, except when setting atime, mtime, access mode and uid/gid, where
		577	errors are being ignored.
		578
		579	=cut
		580
		581	sub aio_copy($$;$) {
		582	my ($src, $dst, $cb) = @_;
		583
		584	my $pri = aioreq_pri;
		585	my $grp = aio_group $cb;
		586
		587	aioreq_pri $pri;
		588	add $grp aio_open $src, O_RDONLY, 0, sub {
		589	if (my $src_fh = $_[0]) {
		590	my @stat = stat $src_fh;
		591
		592	aioreq_pri $pri;
		593	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		594	if (my $dst_fh = $_[0]) {
		595	aioreq_pri $pri;
		596	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		597	if ($_[0] == $stat[7]) {
		598	$grp->result (0);
		599	close $src_fh;
		600
		601	# those should not normally block. should. should.
		602	utime $stat[8], $stat[9], $dst;
		603	chmod $stat[2] & 07777, $dst_fh;
		604	chown $stat[4], $stat[5], $dst_fh;
		605
		606	aioreq_pri $pri;
		607	add $grp aio_close $dst_fh;
		608	} else {
		609	$grp->result (-1);
		610	close $src_fh;
		611	close $dst_fh;
		612
		613	aioreq $pri;
		614	add $grp aio_unlink $dst;
		615	}
		616	};
		617	} else {
		618	$grp->result (-1);
		619	}
		620	},
		621
		622	} else {
		623	$grp->result (-1);
		624	}
		625	};
		626
		627	$grp
		628	}
		629
		630	=item aio_move $srcpath, $dstpath, $callback->($status)
		631
		632	Try to move the I<file> (directories not supported as either source or
		633	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		634	the C<0> (error) or C<-1> ok.
		635
		636	This is a composite request that tries to rename(2) the file first; if
		637	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		638	that is successful, unlinks the C<$srcpath>.
		639
		640	=cut
		641
		642	sub aio_move($$;$) {
		643	my ($src, $dst, $cb) = @_;
		644
		645	my $pri = aioreq_pri;
		646	my $grp = aio_group $cb;
		647
		648	aioreq_pri $pri;
		649	add $grp aio_rename $src, $dst, sub {
		650	if ($_[0] && $! == EXDEV) {
		651	aioreq_pri $pri;
		652	add $grp aio_copy $src, $dst, sub {
		653	$grp->result ($_[0]);
		654
		655	if (!$_[0]) {
		656	aioreq_pri $pri;
		657	add $grp aio_unlink $src;
		658	}
		659	};
		660	} else {
		661	$grp->result ($_[0]);
		662	}
		663	};
		664
		665	$grp
		666	}
		667
379	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	668	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
380		669
381	[EXPERIMENTAL due to internal aio_group use]
382
383	Scans a directory (similar to C<aio_readdir>) but additionally tries to	670	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	671	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	672	names, directories you can recurse into (directories), and ones you cannot
386	recurse into (everything else).	673	recurse into (everything else, including symlinks to directories).
387		674
388	C<aio_scandir> is a composite request that creates of many sub requests_	675	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	676	C<$maxreq> specifies the maximum number of outstanding aio requests that
390	this function generates. If it is C<< <= 0 >>, then a suitable default	677	this function generates. If it is C<< <= 0 >>, then a suitable default
391	will be chosen (currently 6).	678	will be chosen (currently 4).
392		679
393	On error, the callback is called without arguments, otherwise it receives	680	On error, the callback is called without arguments, otherwise it receives
394	two array-refs with path-relative entry names.	681	two array-refs with path-relative entry names.
395		682
396	Example:	683	Example:
…		…
430	as those tend to return 0 or 1 as link counts, which disables the	717	as those tend to return 0 or 1 as link counts, which disables the
431	directory counting heuristic.	718	directory counting heuristic.
432		719
433	=cut	720	=cut
434		721
435	sub aio_scandir($$$) {	722	sub aio_scandir($$;$) {
436	my ($path, $maxreq, $cb) = @_;	723	my ($path, $maxreq, $cb) = @_;
437		724
		725	my $pri = aioreq_pri;
		726
438	my $grp = aio_group $cb;	727	my $grp = aio_group $cb;
439		728
440	$maxreq = 6 if $maxreq <= 0;	729	$maxreq = 4 if $maxreq <= 0;
441		730
442	# stat once	731	# stat once
		732	aioreq_pri $pri;
443	add $grp aio_stat $path, sub {	733	add $grp aio_stat $path, sub {
444	return $grp->result () if $_[0];	734	return $grp->result () if $_[0];
445	my $now = time;	735	my $now = time;
446	my $hash1 = join ":", (stat _)[0,1,3,7,9];	736	my $hash1 = join ":", (stat _)[0,1,3,7,9];
447		737
448	# read the directory entries	738	# read the directory entries
		739	aioreq_pri $pri;
449	add $grp aio_readdir $path, sub {	740	add $grp aio_readdir $path, sub {
450	my $entries = shift	741	my $entries = shift
451	or return $grp->result ();	742	or return $grp->result ();
452		743
453	# stat the dir another time	744	# stat the dir another time
		745	aioreq_pri $pri;
454	add $grp aio_stat $path, sub {	746	add $grp aio_stat $path, sub {
455	my $hash2 = join ":", (stat _)[0,1,3,7,9];	747	my $hash2 = join ":", (stat _)[0,1,3,7,9];
456		748
457	my $ndirs;	749	my $ndirs;
458		750
…		…
473	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	765	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
474	@$entries];	766	@$entries];
475		767
476	my (@dirs, @nondirs);	768	my (@dirs, @nondirs);
477		769
478	my ($statcb, $schedcb);
479	my $nreq = 0;
480
481	my $statgrp = add $grp aio_group;	770	my $statgrp = add $grp aio_group sub {
		771	$grp->result (\@dirs, \@nondirs);
		772	};
482		773
483	$schedcb = sub {	774	limit $statgrp $maxreq;
484	if (@$entries) {	775	feed $statgrp sub {
485	if ($nreq < $maxreq) {	776	return unless @$entries;
486	my $ent = pop @$entries;	777	my $entry = pop @$entries;
		778
		779	aioreq_pri $pri;
		780	add $statgrp aio_stat "$path/$entry/.", sub {
		781	if ($_[0] < 0) {
		782	push @nondirs, $entry;
		783	} else {
		784	# need to check for real directory
		785	aioreq_pri $pri;
		786	add $statgrp aio_lstat "$path/$entry", sub {
		787	if (-d _) {
		788	push @dirs, $entry;
		789
		790	unless (--$ndirs) {
		791	push @nondirs, @$entries;
		792	feed $statgrp;
		793	}
		794	} else {
		795	push @nondirs, $entry;
		796	}
487	$nreq++;	797	}
488	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
489	}	798	}
490	} elsif (!$nreq) {
491	# finished
492	$statgrp->cancel;
493	undef $statcb;
494	undef $schedcb;
495	$grp->result (\@dirs, \@nondirs);
496	}	799	};
497	};	800	};
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	};	801	};
528	};	802	};
529	};	803	};
530		804
531	$grp	805	$grp
532	}	806	}
533		807
		808	=item aio_rmtree $path, $callback->($status)
		809
		810	Delete a directory tree starting (and including) C<$path>, return the
		811	status of the final C<rmdir> only. This is a composite request that
		812	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		813	everything else.
		814
		815	=cut
		816
		817	sub aio_rmtree;
		818	sub aio_rmtree($;$) {
		819	my ($path, $cb) = @_;
		820
		821	my $pri = aioreq_pri;
		822	my $grp = aio_group $cb;
		823
		824	aioreq_pri $pri;
		825	add $grp aio_scandir $path, 0, sub {
		826	my ($dirs, $nondirs) = @_;
		827
		828	my $dirgrp = aio_group sub {
		829	add $grp aio_rmdir $path, sub {
		830	$grp->result ($_[0]);
		831	};
		832	};
		833
		834	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		835	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		836
		837	add $grp $dirgrp;
		838	};
		839
		840	$grp
		841	}
		842
		843	=item aio_sync $callback->($status)
		844
		845	Asynchronously call sync and call the callback when finished.
		846
534	=item aio_fsync $fh, $callback->($status)	847	=item aio_fsync $fh, $callback->($status)
535		848
536	Asynchronously call fsync on the given filehandle and call the callback	849	Asynchronously call fsync on the given filehandle and call the callback
537	with the fsync result code.	850	with the fsync result code.
538		851
…		…
542	callback with the fdatasync result code.	855	callback with the fdatasync result code.
543		856
544	If this call isn't available because your OS lacks it or it couldn't be	857	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.	858	detected, it will be emulated by calling C<fsync> instead.
546		859
		860	=item aio_pathsync $path, $callback->($status)
		861
		862	This request tries to open, fsync and close the given path. This is a
		863	composite request intended to sync directories after directory operations
		864	(E.g. rename). This might not work on all operating systems or have any
		865	specific effect, but usually it makes sure that directory changes get
		866	written to disc. It works for anything that can be opened for read-only,
		867	not just directories.
		868
		869	Passes C<0> when everything went ok, and C<-1> on error.
		870
		871	=cut
		872
		873	sub aio_pathsync($;$) {
		874	my ($path, $cb) = @_;
		875
		876	my $pri = aioreq_pri;
		877	my $grp = aio_group $cb;
		878
		879	aioreq_pri $pri;
		880	add $grp aio_open $path, O_RDONLY, 0, sub {
		881	my ($fh) = @_;
		882	if ($fh) {
		883	aioreq_pri $pri;
		884	add $grp aio_fsync $fh, sub {
		885	$grp->result ($_[0]);
		886
		887	aioreq_pri $pri;
		888	add $grp aio_close $fh;
		889	};
		890	} else {
		891	$grp->result (-1);
		892	}
		893	};
		894
		895	$grp
		896	}
		897
547	=item aio_group $callback->(...)	898	=item aio_group $callback->(...)
548
549	[EXPERIMENTAL]
550		899
551	This is a very special aio request: Instead of doing something, it is a	900	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	901	container for other aio requests, which is useful if you want to bundle
553	many requests into a single, composite, request.	902	many requests into a single, composite, request with a definite callback
		903	and the ability to cancel the whole request with its subrequests.
554		904
555	Returns an object of class L<IO::AIO::GRP>. See its documentation below	905	Returns an object of class L<IO::AIO::GRP>. See its documentation below
556	for more info.	906	for more info.
557		907
558	Example:	908	Example:
…		…
577	phase and still requires a worker thread. Thus, the callback will not	927	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	928	be executed immediately but only after other requests in the queue have
579	entered their execution phase. This can be used to measure request	929	entered their execution phase. This can be used to measure request
580	latency.	930	latency.
581		931
582	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	932	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
583		933
584	Mainly used for debugging and benchmarking, this aio request puts one of	934	Mainly used for debugging and benchmarking, this aio request puts one of
585	the request workers to sleep for the given time.	935	the request workers to sleep for the given time.
586		936
587	While it is theoretically handy to have simple I/O scheduling requests	937	While it is theoretically handy to have simple I/O scheduling requests
588	like sleep and file handle readable/writable, the overhead this creates	938	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	939	immense (it blocks a thread for a long time) so do not use this function
590	under artificial I/O pressure.	940	except to put your application under artificial I/O pressure.
591		941
592	=back	942	=back
593		943
594	=head2 IO::AIO::REQ CLASS	944	=head2 IO::AIO::REQ CLASS
595		945
596	All non-aggregate C<aio_*> functions return an object of this class when	946	All non-aggregate C<aio_*> functions return an object of this class when
597	called in non-void context.	947	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		948
607	=over 4	949	=over 4
608		950
609	=item cancel $req	951	=item cancel $req
610		952
…		…
664	=item * They can also can also be added to other IO::AIO::GRP objects.	1006	=item * They can also can also be added to other IO::AIO::GRP objects.
665		1007
666	=item * You must not add requests to a group from within the group callback (or	1008	=item * You must not add requests to a group from within the group callback (or
667	any later time).	1009	any later time).
668		1010
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	1011	=back
674		1012
675	Their lifetime, simplified, looks like this: when they are empty, they	1013	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	1014	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	1015	C<done> state, they will also finish. Otherwise they will continue to
678	exist.	1016	exist.
679		1017
680	That means after creating a group you have some time to add requests. And	1018	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	1019	(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	1020	the C<poll_cb>). And in the callbacks of those requests, you can add
683	itself finish.	1021	further requests to the group. And only when all those requests have
		1022	finished will the the group itself finish.
684		1023
685	=over 4	1024	=over 4
686		1025
687	=item add $grp ...	1026	=item add $grp ...
688		1027
…		…
692	be added, including other groups, as long as you do not create circular	1031	be added, including other groups, as long as you do not create circular
693	dependencies.	1032	dependencies.
694		1033
695	Returns all its arguments.	1034	Returns all its arguments.
696		1035
		1036	=item $grp->cancel_subs
		1037
		1038	Cancel all subrequests and clears any feeder, but not the group request
		1039	itself. Useful when you queued a lot of events but got a result early.
		1040
697	=item $grp->result (...)	1041	=item $grp->result (...)
698		1042
699	Set the result value(s) that will be passed to the group callback when all	1043	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.	1044	subrequests have finished and set the groups errno to the current value
		1045	of errno (just like calling C<errno> without an error number). By default,
		1046	no argument will be passed and errno is zero.
		1047
		1048	=item $grp->errno ([$errno])
		1049
		1050	Sets the group errno value to C<$errno>, or the current value of errno
		1051	when the argument is missing.
		1052
		1053	Every aio request has an associated errno value that is restored when
		1054	the callback is invoked. This method lets you change this value from its
		1055	default (0).
		1056
		1057	Calling C<result> will also set errno, so make sure you either set C<$!>
		1058	before the call to C<result>, or call c<errno> after it.
701		1059
702	=item feed $grp $callback->($grp)	1060	=item feed $grp $callback->($grp)
703
704	[VERY EXPERIMENTAL]
705		1061
706	Sets a feeder/generator on this group: every group can have an attached	1062	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,	1063	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,	1064	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	1065	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>	1066	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
711	requests, delaying any later requests for a long time.	1067	delaying any later requests for a long time.
712		1068
713	To avoid this, and allow incremental generation of requests, you can	1069	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	1070	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>,	1071	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	1072	below) requests active in the group itself and is expected to queue more
…		…
720	not impose any limits).	1076	not impose any limits).
721		1077
722	If the feed does not queue more requests when called, it will be	1078	If the feed does not queue more requests when called, it will be
723	automatically removed from the group.	1079	automatically removed from the group.
724		1080
725	If the feed limit is C<0>, it will be set to C<2> automatically.	1081	If the feed limit is C<0> when this method is called, it will be set to
		1082	C<2> automatically.
726		1083
727	Example:	1084	Example:
728		1085
729	# stat all files in @files, but only ever use four aio requests concurrently:	1086	# stat all files in @files, but only ever use four aio requests concurrently:
730		1087
…		…
742	Sets the feeder limit for the group: The feeder will be called whenever	1099	Sets the feeder limit for the group: The feeder will be called whenever
743	the group contains less than this many requests.	1100	the group contains less than this many requests.
744		1101
745	Setting the limit to C<0> will pause the feeding process.	1102	Setting the limit to C<0> will pause the feeding process.
746		1103
		1104	The default value for the limit is C<0>, but note that setting a feeder
		1105	automatically bumps it up to C<2>.
		1106
747	=back	1107	=back
748		1108
749	=head2 SUPPORT FUNCTIONS	1109	=head2 SUPPORT FUNCTIONS
		1110
		1111	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
750		1112
751	=over 4	1113	=over 4
752		1114
753	=item $fileno = IO::AIO::poll_fileno	1115	=item $fileno = IO::AIO::poll_fileno
754		1116
…		…
759		1121
760	See C<poll_cb> for an example.	1122	See C<poll_cb> for an example.
761		1123
762	=item IO::AIO::poll_cb	1124	=item IO::AIO::poll_cb
763		1125
764	Process all outstanding events on the result pipe. You have to call this	1126	Process some outstanding events on the result pipe. You have to call this
765	regularly. Returns the number of events processed. Returns immediately	1127	regularly. Returns C<0> if all events could be processed, or C<-1> if it
766	when no events are outstanding.	1128	returned earlier for whatever reason. Returns immediately when no events
		1129	are outstanding. The amount of events processed depends on the settings of
		1130	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1131
		1132	If not all requests were processed for whatever reason, the filehandle
		1133	will still be ready when C<poll_cb> returns, so normally you don't have to
		1134	do anything special to have it called later.
767		1135
768	Example: Install an Event watcher that automatically calls	1136	Example: Install an Event watcher that automatically calls
769	IO::AIO::poll_cb with high priority:	1137	IO::AIO::poll_cb with high priority:
770		1138
771	Event->io (fd => IO::AIO::poll_fileno,	1139	Event->io (fd => IO::AIO::poll_fileno,
772	poll => 'r', async => 1,	1140	poll => 'r', async => 1,
773	cb => \&IO::AIO::poll_cb);	1141	cb => \&IO::AIO::poll_cb);
774		1142
		1143	=item IO::AIO::max_poll_reqs $nreqs
		1144
		1145	=item IO::AIO::max_poll_time $seconds
		1146
		1147	These set the maximum number of requests (default C<0>, meaning infinity)
		1148	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1149	the maximum amount of time (default C<0>, meaning infinity) spent in
		1150	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1151	of time C<poll_cb> is allowed to use).
		1152
		1153	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1154	syscall per request processed, which is not normally a problem unless your
		1155	callbacks are really really fast or your OS is really really slow (I am
		1156	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1157
		1158	Setting these is useful if you want to ensure some level of
		1159	interactiveness when perl is not fast enough to process all requests in
		1160	time.
		1161
		1162	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1163
		1164	Example: Install an Event watcher that automatically calls
		1165	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1166	program get the CPU sometimes even under high AIO load.
		1167
		1168	# try not to spend much more than 0.1s in poll_cb
		1169	IO::AIO::max_poll_time 0.1;
		1170
		1171	# use a low priority so other tasks have priority
		1172	Event->io (fd => IO::AIO::poll_fileno,
		1173	poll => 'r', nice => 1,
		1174	cb => &IO::AIO::poll_cb);
		1175
775	=item IO::AIO::poll_wait	1176	=item IO::AIO::poll_wait
776		1177
		1178	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	1179	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	1180	does a C<select> on the filehandle. This is useful if you want to
779	for some requests to finish).	1181	synchronously wait for some requests to finish).
780		1182
781	See C<nreqs> for an example.	1183	See C<nreqs> for an example.
782		1184
		1185	=item IO::AIO::poll
		1186
		1187	Waits until some requests have been handled.
		1188
		1189	Returns the number of requests processed, but is otherwise strictly
		1190	equivalent to:
		1191
		1192	IO::AIO::poll_wait, IO::AIO::poll_cb
		1193
783	=item IO::AIO::nreqs	1194	=item IO::AIO::flush
784		1195
785	Returns the number of requests currently outstanding (i.e. for which their	1196	Wait till all outstanding AIO requests have been handled.
786	callback has not been invoked yet).
787		1197
788	Example: wait till there are no outstanding requests anymore:	1198	Strictly equivalent to:
789		1199
790	IO::AIO::poll_wait, IO::AIO::poll_cb	1200	IO::AIO::poll_wait, IO::AIO::poll_cb
791	while IO::AIO::nreqs;	1201	while IO::AIO::nreqs;
792		1202
793	=item IO::AIO::flush	1203	=back
794		1204
795	Wait till all outstanding AIO requests have been handled.	1205	=head3 CONTROLLING THE NUMBER OF THREADS
796		1206
797	Strictly equivalent to:	1207	=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		1208
811	=item IO::AIO::min_parallel $nthreads	1209	=item IO::AIO::min_parallel $nthreads
812		1210
813	Set the minimum number of AIO threads to C<$nthreads>. The current	1211	Set the minimum number of AIO threads to C<$nthreads>. The current
814	default is C<8>, which means eight asynchronous operations can execute	1212	default is C<8>, which means eight asynchronous operations can execute
815	concurrently at any one time (the number of outstanding requests,	1213	concurrently at any one time (the number of outstanding requests,
816	however, is unlimited).	1214	however, is unlimited).
817		1215
818	IO::AIO starts threads only on demand, when an AIO request is queued and	1216	IO::AIO starts threads only on demand, when an AIO request is queued and
819	no free thread exists.	1217	no free thread exists. Please note that queueing up a hundred requests can
		1218	create demand for a hundred threads, even if it turns out that everything
		1219	is in the cache and could have been processed faster by a single thread.
820		1220
821	It is recommended to keep the number of threads relatively low, as some	1221	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	1222	Linux kernel versions will scale negatively with the number of threads
823	(higher parallelity => MUCH higher latency). With current Linux 2.6	1223	(higher parallelity => MUCH higher latency). With current Linux 2.6
824	versions, 4-32 threads should be fine.	1224	versions, 4-32 threads should be fine.
…		…
838	This module automatically runs C<max_parallel 0> at program end, to ensure	1238	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.	1239	that all threads are killed and that there are no outstanding requests.
840		1240
841	Under normal circumstances you don't need to call this function.	1241	Under normal circumstances you don't need to call this function.
842		1242
		1243	=item IO::AIO::max_idle $nthreads
		1244
		1245	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1246	threads that did not get a request to process within 10 seconds). That
		1247	means if a thread becomes idle while C<$nthreads> other threads are also
		1248	idle, it will free its resources and exit.
		1249
		1250	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1251	to allow for extremely high load situations, but want to free resources
		1252	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1253
		1254	The default is probably ok in most situations, especially if thread
		1255	creation is fast. If thread creation is very slow on your system you might
		1256	want to use larger values.
		1257
843	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1258	=item IO::AIO::max_outstanding $maxreqs
844		1259
845	[DEPRECATED]	1260	This is a very bad function to use in interactive programs because it
		1261	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1262	use an C<aio_group> together with a feed callback.
846		1263
847	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1264	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	1265	do queue up more than this number of requests, the next call to the
849	some requests have been handled.	1266	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1267	function will block until the limit is no longer exceeded.
850		1268
851	The default is very large, so normally there is no practical limit. If you	1269	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	1270	number of outstanding requests.
853	this to a relatively low number, such as C<100>.
854		1271
855	This function does not work well together with C<aio_group>'s, and their	1272	You can still queue as many requests as you want. Therefore,
856	feeder interface is better suited to limiting concurrency, so do not use	1273	C<max_outstanding> is mainly useful in simple scripts (with low values) or
857	this function.	1274	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		1275
861	=back	1276	=back
862		1277
		1278	=head3 STATISTICAL INFORMATION
		1279
		1280	=over
		1281
		1282	=item IO::AIO::nreqs
		1283
		1284	Returns the number of requests currently in the ready, execute or pending
		1285	states (i.e. for which their callback has not been invoked yet).
		1286
		1287	Example: wait till there are no outstanding requests anymore:
		1288
		1289	IO::AIO::poll_wait, IO::AIO::poll_cb
		1290	while IO::AIO::nreqs;
		1291
		1292	=item IO::AIO::nready
		1293
		1294	Returns the number of requests currently in the ready state (not yet
		1295	executed).
		1296
		1297	=item IO::AIO::npending
		1298
		1299	Returns the number of requests currently in the pending state (executed,
		1300	but not yet processed by poll_cb).
		1301
		1302	=back
		1303
863	=cut	1304	=cut
864		1305
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;	1306	min_parallel 8;
882		1307
883	END {	1308	END { flush }
884	max_parallel 0;
885	}
886		1309
887	1;	1310	1;
888		1311
889	=head2 FORK BEHAVIOUR	1312	=head2 FORK BEHAVIOUR
890		1313
891	This module should do "the right thing" when the process using it forks:	1314	This module should do "the right thing" when the process using it forks:
892		1315
893	Before the fork, IO::AIO enters a quiescent state where no requests	1316	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	1317	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	1318	the fork the parent simply leaves the quiescent state and continues
896	request/result processing, while the child clears the request/result	1319	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	1320	(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	1321	parent). Threads will be started on demand until the limit set in the
899	parent process has been reached again.	1322	parent process has been reached again.
900		1323
901	In short: the parent will, after a short pause, continue as if fork had	1324	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	1325	not been called, while the child will act as if IO::AIO has not been used
903	yet.	1326	yet.
904		1327
905	=head2 MEMORY USAGE	1328	=head2 MEMORY USAGE
906		1329
		1330	Per-request usage:
		1331
907	Each aio request uses - depending on your architecture - around 128 bytes	1332	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	1333	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	1334	a few hundred bytes), readdir requires a result buffer and so on. Perl
910	also be locked.	1335	scalars and other data passed into aio requests will also be locked and
		1336	will consume memory till the request has entered the done state.
911		1337
912	This is now awfully much, so queuing lots of requests is not usually a	1338	This is not awfully much, so queuing lots of requests is not usually a
913	problem.	1339	problem.
914		1340
915	Each thread needs a stack area which is usually around 16k, sometimes much	1341	Per-thread usage:
916	larger, depending on the OS.	1342
		1343	In the execution phase, some aio requests require more memory for
		1344	temporary buffers, and each thread requires a stack and other data
		1345	structures (usually around 16k-128k, depending on the OS).
		1346
		1347	=head1 KNOWN BUGS
		1348
		1349	Known bugs will be fixed in the next release.
917		1350
918	=head1 SEE ALSO	1351	=head1 SEE ALSO
919		1352
920	L<Coro::AIO>.	1353	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1354	more natural syntax.
921		1355
922	=head1 AUTHOR	1356	=head1 AUTHOR
923		1357
924	Marc Lehmann <schmorp@schmorp.de>	1358	Marc Lehmann <schmorp@schmorp.de>
925	http://home.schmorp.de/	1359	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.69 by root, Tue Oct 24 03:40:25 2006 UTC vs. Revision 1.141 by root, Wed Oct 22 16:30:49 2008 UTC

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Revision 1.69 by root, Tue Oct 24 03:40:25 2006 UTC vs.
Revision 1.141 by root, Wed Oct 22 16:30:49 2008 UTC