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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.4 by root, Sun Jul 10 20:57:00 2005 UTC vs.
Revision 1.32 by root, Wed Aug 17 05:26:20 2005 UTC

…		…
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
		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: $!";
		18	};
		19
		20	# Event
		21	Event->io (fd => IO::AIO::poll_fileno,
		22	poll => 'r',
		23	cb => \&IO::AIO::poll_cb);
		24
		25	# Glib/Gtk2
		26	add_watch Glib::IO IO::AIO::poll_fileno,
		27	in => sub { IO::AIO::poll_cb; 1 };
		28
		29	# Tk
		30	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		31	readable => \&IO::AIO::poll_cb);
		32
		33	# Danga::Socket
		34	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		35	\&IO::AIO::poll_cb);
		36
8		37
9	=head1 DESCRIPTION	38	=head1 DESCRIPTION
10		39
11	This module implements asynchronous I/O using whatever means your	40	This module implements asynchronous I/O using whatever means your
12	operating system supports.	41	operating system supports.
…		…
19	not well-supported (Linux doesn't allow them on normal files currently,	48	not well-supported (Linux doesn't allow them on normal files currently,
20	for example), and they would only support aio_read and aio_write, so the	49	for example), and they would only support aio_read and aio_write, so the
21	remaining functionality would have to be implemented using threads anyway.	50	remaining functionality would have to be implemented using threads anyway.
22		51
23	Although the module will work with in the presence of other threads, it is	52	Although the module will work with in the presence of other threads, it is
24	currently not reentrant, so use appropriate locking yourself.	53	currently not reentrant, so use appropriate locking yourself, always call
25		54	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other
26	=head2 API NOTES	55	C<aio_> functions) recursively.
27
28	All the C<aio_*> calls are more or less thin wrappers around the syscall
29	with the same name (sans C<aio_>). The arguments are similar or identical,
30	and they all accept an additional C<$callback> argument which must be
31	a code reference. This code reference will get called with the syscall
32	return code (e.g. most syscalls return C<-1> on error, unlike perl, which
33	usually delivers "false") as it's sole argument when the given syscall has
34	been executed asynchronously.
35
36	All functions that expect a filehandle will also accept a file descriptor.
37
38	The filenames you pass to these routines I<must> be absolute. The reason
39	is that at the time the request is being executed, the current working
40	directory could have changed. Alternatively, you can make sure that you
41	never change the current working directory.
42
43	=over 4
44		56
45	=cut	57	=cut
46		58
47	package IO::AIO;	59	package IO::AIO;
48		60
		61	no warnings;
		62
49	use base 'Exporter';	63	use base 'Exporter';
50		64
51	use Fcntl ();	65	use Fcntl ();
52		66
53	BEGIN {	67	BEGIN {
54	$VERSION = 0.2;	68	$VERSION = 1.3;
		69
55		70
56	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink	71	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink
57	aio_fsync aio_fdatasync aio_readahead);	72	aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead);
58	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	73	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
59		74
60	require XSLoader;	75	require XSLoader;
61	XSLoader::load IO::AIO, $VERSION;	76	XSLoader::load IO::AIO, $VERSION;
62	}	77	}
63		78
64	=item IO::AIO::min_parallel $nthreads	79	=head1 FUNCTIONS
65		80
66	Set the minimum number of AIO threads to C<$nthreads>. The default is	81	=head2 AIO FUNCTIONS
67	C<1>, which means a single asynchronous operation can be done at one time
68	(the number of outstanding operations, however, is unlimited).
69		82
70	It is recommended to keep the number of threads low, as some Linux	83	All the C<aio_*> calls are more or less thin wrappers around the syscall
71	kernel versions will scale negatively with the number of threads (higher	84	with the same name (sans C<aio_>). The arguments are similar or identical,
72	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	85	and they all accept an additional (and optional) C<$callback> argument
73	threads should be fine.	86	which must be a code reference. This code reference will get called with
		87	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
		88	perl, which usually delivers "false") as it's sole argument when the given
		89	syscall has been executed asynchronously.
74		90
75	Under normal circumstances you don't need to call this function, as this	91	All functions expecting a filehandle keep a copy of the filehandle
76	module automatically starts some threads (the exact number might change,	92	internally until the request has finished.
77	and is currently 4).
78		93
79	=item IO::AIO::max_parallel $nthreads	94	The pathnames you pass to these routines I<must> be absolute and
		95	encoded in byte form. The reason for the former is that at the time the
		96	request is being executed, the current working directory could have
		97	changed. Alternatively, you can make sure that you never change the
		98	current working directory.
80		99
81	Sets the maximum number of AIO threads to C<$nthreads>. If more than	100	To encode pathnames to byte form, either make sure you either: a)
82	the specified number of threads are currently running, kill them. This	101	always pass in filenames you got from outside (command line, readdir
83	function blocks until the limit is reached.	102	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
		103	your pathnames to the locale (or other) encoding in effect in the user
		104	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
		105	use something else.
84		106
85	This module automatically runs C<max_parallel 0> at program end, to ensure	107	=over 4
86	that all threads are killed and that there are no outstanding requests.
87
88	Under normal circumstances you don't need to call this function.
89
90	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
91
92	Sets the maximum number of outstanding requests to C<$nreqs>. If you
93	try to queue up more than this number of requests, the caller will block until
94	some requests have been handled.
95
96	The default is very large, so normally there is no practical limit. If you
97	queue up many requests in a loop it it often improves speed if you set
98	this to a relatively low number, such as C<100>.
99
100	Under normal circumstances you don't need to call this function.
101
102	=item $fileno = IO::AIO::poll_fileno
103
104	Return the I<request result pipe filehandle>. This filehandle must be
105	polled for reading by some mechanism outside this module (e.g. Event
106	or select, see below). If the pipe becomes readable you have to call
107	C<poll_cb> to check the results.
108
109	See C<poll_cb> for an example.
110
111	=item IO::AIO::poll_cb
112
113	Process all outstanding events on the result pipe. You have to call this
114	regularly. Returns the number of events processed. Returns immediately
115	when no events are outstanding.
116
117	You can use Event to multiplex, e.g.:
118
119	Event->io (fd => IO::AIO::poll_fileno,
120	poll => 'r', async => 1,
121	cb => \&IO::AIO::poll_cb);
122
123	=item IO::AIO::poll_wait
124
125	Wait till the result filehandle becomes ready for reading (simply does a
126	select on the filehandle. This is useful if you want to synchronously wait
127	for some requests to finish).
128
129	See C<nreqs> for an example.
130
131	=item IO::AIO::nreqs
132
133	Returns the number of requests currently outstanding.
134
135	Example: wait till there are no outstanding requests anymore:
136
137	IO::AIO::poll_wait, IO::AIO::poll_cb
138	while IO::AIO::nreqs;
139		108
140	=item aio_open $pathname, $flags, $mode, $callback	109	=item aio_open $pathname, $flags, $mode, $callback
141		110
142	Asynchronously open or create a file and call the callback with a newly	111	Asynchronously open or create a file and call the callback with a newly
143	created filehandle for the file.	112	created filehandle for the file.
144		113
145	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	114	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
146	for an explanation.	115	for an explanation.
147		116
148	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a	117	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
149	list. They are the same as used in C<sysopen>.	118	list. They are the same as used by C<sysopen>.
		119
		120	Likewise, C<$mode> specifies the mode of the newly created file, if it
		121	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
		122	except that it is mandatory (i.e. use C<0> if you don't create new files,
		123	and C<0666> or C<0777> if you do).
150		124
151	Example:	125	Example:
152		126
153	aio_open "/etc/passwd", O_RDONLY, 0, sub {	127	aio_open "/etc/passwd", O_RDONLY, 0, sub {
154	if ($_[0]) {	128	if ($_[0]) {
…		…
161		135
162	=item aio_close $fh, $callback	136	=item aio_close $fh, $callback
163		137
164	Asynchronously close a file and call the callback with the result	138	Asynchronously close a file and call the callback with the result
165	code. I<WARNING:> although accepted, you should not pass in a perl	139	code. I<WARNING:> although accepted, you should not pass in a perl
166	filehandle here, as perl will likely close the file descriptor itself when	140	filehandle here, as perl will likely close the file descriptor another
167	the filehandle is destroyed. Normally, you can safely call perls C<close>	141	time when the filehandle is destroyed. Normally, you can safely call perls
168	or just let filehandles go out of scope.	142	C<close> or just let filehandles go out of scope.
		143
		144	This is supposed to be a bug in the API, so that might change. It's
		145	therefore best to avoid this function.
169		146
170	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	147	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
171		148
172	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	149	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
173		150
174	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	151	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
175	into the scalar given by C<data> and offset C<dataoffset> and calls the	152	into the scalar given by C<data> and offset C<dataoffset> and calls the
176	callback without the actual number of bytes read (or -1 on error, just	153	callback without the actual number of bytes read (or -1 on error, just
177	like the syscall).	154	like the syscall).
178		155
		156	The C<$data> scalar I<MUST NOT> be modified in any way while the request
		157	is outstanding. Modifying it can result in segfaults or WW3 (if the
		158	necessary/optional hardware is installed).
		159
179	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at	160	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
180	offset C<0> within the scalar:	161	offset C<0> within the scalar:
181		162
182	aio_read $fh, 7, 15, $buffer, 0, sub {	163	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] >= 0 or die "read error: $!";	164	$_[0] > 0 or die "read error: $!";
184	print "read <$buffer>\n";	165	print "read $_[0] bytes: <$buffer>\n";
185	};	166	};
186		167
187	=item aio_readahead $fh,$offset,$length, $callback	168	=item aio_readahead $fh,$offset,$length, $callback
188		169
189	Asynchronously reads the specified byte range into the page cache, using
190	the C<readahead> syscall. If that syscall doesn't exist the status will be
191	C<-1> and C<$!> is set to ENOSYS.
192
193	readahead() populates the page cache with data from a file so that	170	C<aio_readahead> populates the page cache with data from a file so that
194	subsequent reads from that file will not block on disk I/O. The C<$offset>	171	subsequent reads from that file will not block on disk I/O. The C<$offset>
195	argument specifies the starting point from which data is to be read and	172	argument specifies the starting point from which data is to be read and
196	C<$length> specifies the number of bytes to be read. I/O is performed in	173	C<$length> specifies the number of bytes to be read. I/O is performed in
197	whole pages, so that offset is effectively rounded down to a page boundary	174	whole pages, so that offset is effectively rounded down to a page boundary
198	and bytes are read up to the next page boundary greater than or equal to	175	and bytes are read up to the next page boundary greater than or equal to
199	(off-set+length). aio_readahead() does not read beyond the end of the	176	(off-set+length). C<aio_readahead> does not read beyond the end of the
200	file. The current file offset of the file is left unchanged.	177	file. The current file offset of the file is left unchanged.
		178
		179	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
		180	emulated by simply reading the data, which would have a similar effect.
201		181
202	=item aio_stat $fh_or_path, $callback	182	=item aio_stat $fh_or_path, $callback
203		183
204	=item aio_lstat $fh, $callback	184	=item aio_lstat $fh, $callback
205		185
…		…
224	=item aio_unlink $pathname, $callback	204	=item aio_unlink $pathname, $callback
225		205
226	Asynchronously unlink (delete) a file and call the callback with the	206	Asynchronously unlink (delete) a file and call the callback with the
227	result code.	207	result code.
228		208
		209	=item aio_rmdir $pathname, $callback
		210
		211	Asynchronously rmdir (delete) a directory and call the callback with the
		212	result code.
		213
229	=item aio_fsync $fh, $callback	214	=item aio_fsync $fh, $callback
230		215
231	Asynchronously call fsync on the given filehandle and call the callback	216	Asynchronously call fsync on the given filehandle and call the callback
232	with the fsync result code.	217	with the fsync result code.
233		218
234	=item aio_fdatasync $fh, $callback	219	=item aio_fdatasync $fh, $callback
235		220
236	Asynchronously call fdatasync on the given filehandle and call the	221	Asynchronously call fdatasync on the given filehandle and call the
237	callback with the fdatasync result code.	222	callback with the fdatasync result code.
		223
		224	If this call isn't available because your OS lacks it or it couldn't be
		225	detected, it will be emulated by calling C<fsync> instead.
		226
		227	=back
		228
		229	=head2 SUPPORT FUNCTIONS
		230
		231	=over 4
		232
		233	=item $fileno = IO::AIO::poll_fileno
		234
		235	Return the I<request result pipe file descriptor>. This filehandle must be
		236	polled for reading by some mechanism outside this module (e.g. Event or
		237	select, see below or the SYNOPSIS). If the pipe becomes readable you have
		238	to call C<poll_cb> to check the results.
		239
		240	See C<poll_cb> for an example.
		241
		242	=item IO::AIO::poll_cb
		243
		244	Process all outstanding events on the result pipe. You have to call this
		245	regularly. Returns the number of events processed. Returns immediately
		246	when no events are outstanding.
		247
		248	Example: Install an Event watcher that automatically calls
		249	IO::AIO::poll_cb with high priority:
		250
		251	Event->io (fd => IO::AIO::poll_fileno,
		252	poll => 'r', async => 1,
		253	cb => \&IO::AIO::poll_cb);
		254
		255	=item IO::AIO::poll_wait
		256
		257	Wait till the result filehandle becomes ready for reading (simply does a
		258	C<select> on the filehandle. This is useful if you want to synchronously wait
		259	for some requests to finish).
		260
		261	See C<nreqs> for an example.
		262
		263	=item IO::AIO::nreqs
		264
		265	Returns the number of requests currently outstanding (i.e. for which their
		266	callback has not been invoked yet).
		267
		268	Example: wait till there are no outstanding requests anymore:
		269
		270	IO::AIO::poll_wait, IO::AIO::poll_cb
		271	while IO::AIO::nreqs;
		272
		273	=item IO::AIO::flush
		274
		275	Wait till all outstanding AIO requests have been handled.
		276
		277	Strictly equivalent to:
		278
		279	IO::AIO::poll_wait, IO::AIO::poll_cb
		280	while IO::AIO::nreqs;
		281
		282	=item IO::AIO::poll
		283
		284	Waits until some requests have been handled.
		285
		286	Strictly equivalent to:
		287
		288	IO::AIO::poll_wait, IO::AIO::poll_cb
		289	if IO::AIO::nreqs;
		290
		291	=item IO::AIO::min_parallel $nthreads
		292
		293	Set the minimum number of AIO threads to C<$nthreads>. The default is
		294	C<1>, which means a single asynchronous operation can be done at one time
		295	(the number of outstanding operations, however, is unlimited).
		296
		297	It is recommended to keep the number of threads low, as some Linux
		298	kernel versions will scale negatively with the number of threads (higher
		299	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
		300	threads should be fine.
		301
		302	Under normal circumstances you don't need to call this function, as this
		303	module automatically starts some threads (the exact number might change,
		304	and is currently 4).
		305
		306	=item IO::AIO::max_parallel $nthreads
		307
		308	Sets the maximum number of AIO threads to C<$nthreads>. If more than
		309	the specified number of threads are currently running, kill them. This
		310	function blocks until the limit is reached.
		311
		312	This module automatically runs C<max_parallel 0> at program end, to ensure
		313	that all threads are killed and that there are no outstanding requests.
		314
		315	Under normal circumstances you don't need to call this function.
		316
		317	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
		318
		319	Sets the maximum number of outstanding requests to C<$nreqs>. If you
		320	try to queue up more than this number of requests, the caller will block until
		321	some requests have been handled.
		322
		323	The default is very large, so normally there is no practical limit. If you
		324	queue up many requests in a loop it it often improves speed if you set
		325	this to a relatively low number, such as C<100>.
		326
		327	Under normal circumstances you don't need to call this function.
		328
		329	=back
238		330
239	=cut	331	=cut
240		332
241	# support function to convert a fd into a perl filehandle	333	# support function to convert a fd into a perl filehandle
242	sub _fd2fh {	334	sub _fd2fh {
243	return undef if $_[0] < 0;	335	return undef if $_[0] < 0;
244		336
245	# try to be perl5.6-compatible	337	# try to generate nice filehandles
246	local *AIO_FH;	338	my $sym = "IO::AIO::fd#$_[0]";
247	open AIO_FH, "+<&=$_[0]"	339	local *$sym;
		340
		341	open *$sym, "+<&=$_[0]" # usually works under any unix
		342	or open *$sym, "<&=$_[0]" # cygwin needs this
		343	or open *$sym, ">&=$_[0]" # or this
248	or return undef;	344	or return undef;
249		345
250	*AIO_FH	346	*$sym
251	}	347	}
252		348
253	min_parallel 4;	349	min_parallel 4;
254		350
255	END {	351	END {
256	max_parallel 0;	352	max_parallel 0;
257	}	353	}
258		354
259	1;	355	1;
260		356
261	=back	357	=head2 FORK BEHAVIOUR
262		358
263	=head1 BUGS	359	Before the fork IO::AIO enters a quiescent state where no requests can be
264		360	added in other threads and no results will be processed. After the fork
265	- could be optimized to use more semaphores instead of filehandles.	361	the parent simply leaves the quiescent state and continues request/result
		362	processing, while the child clears the request/result queue and starts the
		363	same number of threads as were in use by the parent.
266		364
267	=head1 SEE ALSO	365	=head1 SEE ALSO
268		366
269	L<Coro>, L<Linux::AIO>.	367	L<Coro>, L<Linux::AIO>.
270		368

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.4 by root, Sun Jul 10 20:57:00 2005 UTC vs. Revision 1.32 by root, Wed Aug 17 05:26:20 2005 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.4 by root, Sun Jul 10 20:57:00 2005 UTC vs.
Revision 1.32 by root, Wed Aug 17 05:26:20 2005 UTC