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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.1 by root, Sun Jul 10 17:07:44 2005 UTC vs.
Revision 1.26 by root, Sun Aug 7 03:34:07 2005 UTC

…		…
4		4
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 {
		10	my ($fh) = @_;
		11	...
		12	};
		13
		14	aio_unlink "/tmp/file", sub { };
		15
		16	aio_read $fh, 30000, 1024, $buffer, 0, sub {
		17	$_[0] > 0 or die "read error: $!";
		18	};
		19
		20	# Event
		21	Event->io (fd => IO::AIO::poll_fileno,
		22	poll => 'r',
		23	cb => \&IO::AIO::poll_cb);
		24
		25	# Glib/Gtk2
		26	add_watch Glib::IO IO::AIO::poll_fileno,
		27	in => sub { IO::AIO::poll_cb; 1 };
		28
		29	# Tk
		30	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		31	readable => \&IO::AIO::poll_cb);
		32
		33	# Danga::Socket
		34	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		35	\&IO::AIO::poll_cb);
		36
		37
9	=head1 DESCRIPTION	38	=head1 DESCRIPTION
10		39
11	This module implements asynchronous I/O using whatever means your	40	This module implements asynchronous I/O using whatever means your
12	operating system supports. Currently, it falls back to Linux::AIO if that	41	operating system supports.
13	module is available, or uses pthreads to emulato aio functionality.
14		42
15	Currently, in this module a number of threads are started that execute	43	Currently, a number of threads are started that execute your read/writes
16	your read/writes and signal their completion. You don't need thread	44	and signal their completion. You don't need thread support in your libc or
17	support in your libc or perl, and the threads created by this module will	45	perl, and the threads created by this module will not be visible to the
18	not be visible to the pthreads library.	46	pthreads library. In the future, this module might make use of the native
		47	aio functions available on many operating systems. However, they are often
		48	not well-supported (Linux doesn't allow them on normal files currently,
		49	for example), and they would only support aio_read and aio_write, so the
		50	remaining functionality would have to be implemented using threads anyway.
19		51
20	Although the module will work with in the presence of other threads, it is	52	Although the module will work with in the presence of other threads, it is
21	not reentrant, so use appropriate locking yourself.	53	currently not reentrant, so use appropriate locking yourself, always call
22		54	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other
23	=head2 API NOTES	55	C<aio_> functions) recursively.
24
25	All the C<aio_*> calls are more or less thin wrappers around the syscall
26	with the same name (sans C<aio_>). The arguments are similar or identical,
27	and they all accept an additional C<$callback> argument which must be
28	a code reference. This code reference will get called with the syscall
29	return code (e.g. most syscalls return C<-1> on error, unlike perl, which
30	usually delivers "false") as it's sole argument when the given syscall has
31	been executed asynchronously.
32
33	All functions that expect a filehandle will also accept a file descriptor.
34
35	The filenames you pass to these routines I<must> be absolute. The reason
36	is that at the time the request is being executed, the current working
37	directory could have changed. Alternatively, you can make sure that you
38	never change the current working directory.
39
40	=over 4
41		56
42	=cut	57	=cut
43		58
44	package IO::AIO;	59	package IO::AIO;
45		60
		61	no warnings;
		62
46	use base 'Exporter';	63	use base 'Exporter';
47		64
		65	use Fcntl ();
		66
48	BEGIN {	67	BEGIN {
49	$VERSION = 0.1;	68	$VERSION = 1.1;
50		69
51	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink	70	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
52	aio_fsync aio_fdatasync aio_readahead);	71	aio_fsync aio_fdatasync aio_readahead);
53	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);	72	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
54		73
55	require XSLoader;	74	require XSLoader;
56	XSLoader::load IO::AIO, $VERSION;	75	XSLoader::load IO::AIO, $VERSION;
57	}	76	}
58		77
59	=item IO::AIO::min_parallel $nthreads	78	=head1 FUNCTIONS
60		79
61	Set the minimum number of AIO threads to C<$nthreads>. The default is	80	=head2 AIO FUNCTIONS
62	C<1>, which means a single asynchronous operation can be done at one time
63	(the number of outstanding operations, however, is unlimited).
64		81
65	It is recommended to keep the number of threads low, as some linux	82	All the C<aio_*> calls are more or less thin wrappers around the syscall
66	kernel versions will scale negatively with the number of threads (higher	83	with the same name (sans C<aio_>). The arguments are similar or identical,
67	parallelity => MUCH higher latency).	84	and they all accept an additional (and optional) C<$callback> argument
		85	which must be a code reference. This code reference will get called with
		86	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
		87	perl, which usually delivers "false") as it's sole argument when the given
		88	syscall has been executed asynchronously.
68		89
69	Under normal circumstances you don't need to call this function, as this	90	All functions expecting a filehandle keep a copy of the filehandle
70	module automatically starts a single async thread.	91	internally until the request has finished.
71		92
72	=item IO::AIO::max_parallel $nthreads	93	The filenames you pass to these routines I<must> be absolute. The reason
		94	for this is that at the time the request is being executed, the current
		95	working directory could have changed. Alternatively, you can make sure
		96	that you never change the current working directory.
73		97
74	Sets the maximum number of AIO threads to C<$nthreads>. If more than	98	=over 4
75	the specified number of threads are currently running, kill them. This
76	function blocks until the limit is reached.
77
78	This module automatically runs C<max_parallel 0> at program end, to ensure
79	that all threads are killed and that there are no outstanding requests.
80
81	Under normal circumstances you don't need to call this function.
82
83	=item $fileno = IO::AIO::poll_fileno
84
85	Return the I<request result pipe filehandle>. This filehandle must be
86	polled for reading by some mechanism outside this module (e.g. Event
87	or select, see below). If the pipe becomes readable you have to call
88	C<poll_cb> to check the results.
89
90	See C<poll_cb> for an example.
91
92	=item IO::AIO::poll_cb
93
94	Process all outstanding events on the result pipe. You have to call this
95	regularly. Returns the number of events processed. Returns immediately
96	when no events are outstanding.
97
98	You can use Event to multiplex, e.g.:
99
100	Event->io (fd => IO::AIO::poll_fileno,
101	poll => 'r', async => 1,
102	cb => \&IO::AIO::poll_cb);
103
104	=item IO::AIO::poll_wait
105
106	Wait till the result filehandle becomes ready for reading (simply does a
107	select on the filehandle. This is useful if you want to synchronously wait
108	for some requests to finish).
109
110	See C<nreqs> for an example.
111
112	=item IO::AIO::nreqs
113
114	Returns the number of requests currently outstanding.
115
116	Example: wait till there are no outstanding requests anymore:
117
118	IO::AIO::poll_wait, IO::AIO::poll_cb
119	while IO::AIO::nreqs;
120		99
121	=item aio_open $pathname, $flags, $mode, $callback	100	=item aio_open $pathname, $flags, $mode, $callback
122		101
123	Asynchronously open or create a file and call the callback with the	102	Asynchronously open or create a file and call the callback with a newly
124	filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this	103	created filehandle for the file.
125	might change in the future).
126		104
127	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	105	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
128	for an explanation.	106	for an explanation.
129		107
130	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a	108	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
131	list. They are the same as used in C<sysopen>.	109	list. They are the same as used by C<sysopen>.
		110
		111	Likewise, C<$mode> specifies the mode of the newly created file, if it
		112	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
		113	except that it is mandatory (i.e. use C<0> if you don't create new files,
		114	and C<0666> or C<0777> if you do).
132		115
133	Example:	116	Example:
134		117
135	aio_open "/etc/passwd", O_RDONLY, 0, sub {	118	aio_open "/etc/passwd", O_RDONLY, 0, sub {
136	if ($_[0] >= 0) {	119	if ($_[0]) {
137	open my $fh, "<&$_[0]"; # create a copy for perl
138	aio_close $_[0], sub { }; # close the aio handle
139	print "open successful, fh is $fh\n";	120	print "open successful, fh is $_[0]\n";
140	...	121	...
141	} else {	122	} else {
142	die "open failed: $!\n";	123	die "open failed: $!\n";
143	}	124	}
144	};	125	};
145		126
146	=item aio_close $fh, $callback	127	=item aio_close $fh, $callback
147		128
148	Asynchronously close a file and call the callback with the result code.	129	Asynchronously close a file and call the callback with the result
		130	code. I<WARNING:> although accepted, you should not pass in a perl
		131	filehandle here, as perl will likely close the file descriptor another
		132	time when the filehandle is destroyed. Normally, you can safely call perls
		133	C<close> or just let filehandles go out of scope.
		134
		135	This is supposed to be a bug in the API, so that might change. It's
		136	therefore best to avoid this function.
149		137
150	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	138	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
151		139
152	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	140	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
153		141
154	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	142	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
155	into the scalar given by C<data> and offset C<dataoffset> and calls the	143	into the scalar given by C<data> and offset C<dataoffset> and calls the
156	callback without the actual number of bytes read (or -1 on error, just	144	callback without the actual number of bytes read (or -1 on error, just
157	like the syscall).	145	like the syscall).
158		146
159	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at	147	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
160	offset C<0> within the scalar:	148	offset C<0> within the scalar:
161		149
162	aio_read $fh, 7, 15, $buffer, 0, sub {	150	aio_read $fh, 7, 15, $buffer, 0, sub {
163	$_[0] >= 0 or die "read error: $!";	151	$_[0] > 0 or die "read error: $!";
164	print "read <$buffer>\n";	152	print "read $_[0] bytes: <$buffer>\n";
165	};	153	};
166		154
167	=item aio_readahead $fh,$offset,$length, $callback	155	=item aio_readahead $fh,$offset,$length, $callback
168		156
169	Asynchronously reads the specified byte range into the page cache, using
170	the C<readahead> syscall. If that syscall doesn't exist the status will be
171	C<-1> and C<$!> is set to ENOSYS.
172
173	readahead() populates the page cache with data from a file so that	157	C<aio_readahead> populates the page cache with data from a file so that
174	subsequent reads from that file will not block on disk I/O. The C<$offset>	158	subsequent reads from that file will not block on disk I/O. The C<$offset>
175	argument specifies the starting point from which data is to be read and	159	argument specifies the starting point from which data is to be read and
176	C<$length> specifies the number of bytes to be read. I/O is performed in	160	C<$length> specifies the number of bytes to be read. I/O is performed in
177	whole pages, so that offset is effectively rounded down to a page boundary	161	whole pages, so that offset is effectively rounded down to a page boundary
178	and bytes are read up to the next page boundary greater than or equal to	162	and bytes are read up to the next page boundary greater than or equal to
179	(off-set+length). aio_readahead() does not read beyond the end of the	163	(off-set+length). C<aio_readahead> does not read beyond the end of the
180	file. The current file offset of the file is left unchanged.	164	file. The current file offset of the file is left unchanged.
		165
		166	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
		167	emulated by simply reading the data, which would have a similar effect.
181		168
182	=item aio_stat $fh_or_path, $callback	169	=item aio_stat $fh_or_path, $callback
183		170
184	=item aio_lstat $fh, $callback	171	=item aio_lstat $fh, $callback
185		172
…		…
214	=item aio_fdatasync $fh, $callback	201	=item aio_fdatasync $fh, $callback
215		202
216	Asynchronously call fdatasync on the given filehandle and call the	203	Asynchronously call fdatasync on the given filehandle and call the
217	callback with the fdatasync result code.	204	callback with the fdatasync result code.
218		205
		206	If this call isn't available because your OS lacks it or it couldn't be
		207	detected, it will be emulated by calling C<fsync> instead.
		208
		209	=back
		210
		211	=head2 SUPPORT FUNCTIONS
		212
		213	=over 4
		214
		215	=item $fileno = IO::AIO::poll_fileno
		216
		217	Return the I<request result pipe file descriptor>. This filehandle must be
		218	polled for reading by some mechanism outside this module (e.g. Event or
		219	select, see below or the SYNOPSIS). If the pipe becomes readable you have
		220	to call C<poll_cb> to check the results.
		221
		222	See C<poll_cb> for an example.
		223
		224	=item IO::AIO::poll_cb
		225
		226	Process all outstanding events on the result pipe. You have to call this
		227	regularly. Returns the number of events processed. Returns immediately
		228	when no events are outstanding.
		229
		230	Example: Install an Event watcher that automatically calls
		231	IO::AIO::poll_cb with high priority:
		232
		233	Event->io (fd => IO::AIO::poll_fileno,
		234	poll => 'r', async => 1,
		235	cb => \&IO::AIO::poll_cb);
		236
		237	=item IO::AIO::poll_wait
		238
		239	Wait till the result filehandle becomes ready for reading (simply does a
		240	C<select> on the filehandle. This is useful if you want to synchronously wait
		241	for some requests to finish).
		242
		243	See C<nreqs> for an example.
		244
		245	=item IO::AIO::nreqs
		246
		247	Returns the number of requests currently outstanding (i.e. for which their
		248	callback has not been invoked yet).
		249
		250	Example: wait till there are no outstanding requests anymore:
		251
		252	IO::AIO::poll_wait, IO::AIO::poll_cb
		253	while IO::AIO::nreqs;
		254
		255	=item IO::AIO::flush
		256
		257	Wait till all outstanding AIO requests have been handled.
		258
		259	Strictly equivalent to:
		260
		261	IO::AIO::poll_wait, IO::AIO::poll_cb
		262	while IO::AIO::nreqs;
		263
		264	=item IO::AIO::poll
		265
		266	Waits until some requests have been handled.
		267
		268	Strictly equivalent to:
		269
		270	IO::AIO::poll_wait, IO::AIO::poll_cb
		271	if IO::AIO::nreqs;
		272
		273	=item IO::AIO::min_parallel $nthreads
		274
		275	Set the minimum number of AIO threads to C<$nthreads>. The default is
		276	C<1>, which means a single asynchronous operation can be done at one time
		277	(the number of outstanding operations, however, is unlimited).
		278
		279	It is recommended to keep the number of threads low, as some Linux
		280	kernel versions will scale negatively with the number of threads (higher
		281	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
		282	threads should be fine.
		283
		284	Under normal circumstances you don't need to call this function, as this
		285	module automatically starts some threads (the exact number might change,
		286	and is currently 4).
		287
		288	=item IO::AIO::max_parallel $nthreads
		289
		290	Sets the maximum number of AIO threads to C<$nthreads>. If more than
		291	the specified number of threads are currently running, kill them. This
		292	function blocks until the limit is reached.
		293
		294	This module automatically runs C<max_parallel 0> at program end, to ensure
		295	that all threads are killed and that there are no outstanding requests.
		296
		297	Under normal circumstances you don't need to call this function.
		298
		299	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
		300
		301	Sets the maximum number of outstanding requests to C<$nreqs>. If you
		302	try to queue up more than this number of requests, the caller will block until
		303	some requests have been handled.
		304
		305	The default is very large, so normally there is no practical limit. If you
		306	queue up many requests in a loop it it often improves speed if you set
		307	this to a relatively low number, such as C<100>.
		308
		309	Under normal circumstances you don't need to call this function.
		310
		311	=back
		312
219	=cut	313	=cut
		314
		315	# support function to convert a fd into a perl filehandle
		316	sub _fd2fh {
		317	return undef if $_[0] < 0;
		318
		319	# try to generate nice filehandles
		320	my $sym = "IO::AIO::fd#$_[0]";
		321	local *$sym;
		322
		323	open *$sym, "+<&$_[0]" # usually under any unix
		324	or open *$sym, "<&$_[0]" # cygwin needs this
		325	or open *$sym, ">&$_[0]" # cygwin needs this
		326	or return undef;
		327
		328	*$sym
		329	}
220		330
221	min_parallel 4;	331	min_parallel 4;
222		332
223	END {	333	END {
224	max_parallel 0;	334	max_parallel 0;
225	}	335	}
226		336
227	1;	337	1;
228		338
229	=back
230
231	=head1 BUGS
232
233	- aio_open gives a fd, but all other functions expect a perl filehandle.
234
235	=head1 SEE ALSO	339	=head1 SEE ALSO
236		340
237	L<Coro>, L<Linux::AIO>.	341	L<Coro>, L<Linux::AIO>.
238		342
239	=head1 AUTHOR	343	=head1 AUTHOR

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.1 by root, Sun Jul 10 17:07:44 2005 UTC vs. Revision 1.26 by root, Sun Aug 7 03:34:07 2005 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.1 by root, Sun Jul 10 17:07:44 2005 UTC vs.
Revision 1.26 by root, Sun Aug 7 03:34:07 2005 UTC