[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 1.32 by root, Wed Aug 17 05:26:20 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 = 1.3;
		69
50		70
51	@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
52	aio_fsync aio_fdatasync aio_readahead);	72	aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead);
53	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);	73	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
54		74
55	require XSLoader;	75	require XSLoader;
56	XSLoader::load IO::AIO, $VERSION;	76	XSLoader::load IO::AIO, $VERSION;
57	}	77	}
58		78
59	=item IO::AIO::min_parallel $nthreads	79	=head1 FUNCTIONS
60		80
61	Set the minimum number of AIO threads to C<$nthreads>. The default is	81	=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		82
65	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
66	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,
67	parallelity => MUCH higher latency).	85	and they all accept an additional (and optional) C<$callback> argument
		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.
68		90
69	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
70	module automatically starts a single async thread.	92	internally until the request has finished.
71		93
72	=item IO::AIO::max_parallel $nthreads	94	The pathnames you pass to these routines I<must> be absolute and
		95	encoded in byte form. The reason for the former is that at the time the
		96	request is being executed, the current working directory could have
		97	changed. Alternatively, you can make sure that you never change the
		98	current working directory.
73		99
74	Sets the maximum number of AIO threads to C<$nthreads>. If more than	100	To encode pathnames to byte form, either make sure you either: a)
75	the specified number of threads are currently running, kill them. This	101	always pass in filenames you got from outside (command line, readdir
76	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.
77		106
78	This module automatically runs C<max_parallel 0> at program end, to ensure	107	=over 4
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		108
121	=item aio_open $pathname, $flags, $mode, $callback	109	=item aio_open $pathname, $flags, $mode, $callback
122		110
123	Asynchronously open or create a file and call the callback with the	111	Asynchronously open or create a file and call the callback with a newly
124	filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this	112	created filehandle for the file.
125	might change in the future).
126		113
127	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	114	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
128	for an explanation.	115	for an explanation.
129		116
130	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a	117	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
131	list. They are the same as used in C<sysopen>.	118	list. They are the same as used by C<sysopen>.
		119
		120	Likewise, C<$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).
132		124
133	Example:	125	Example:
134		126
135	aio_open "/etc/passwd", O_RDONLY, 0, sub {	127	aio_open "/etc/passwd", O_RDONLY, 0, sub {
136	if ($_[0] >= 0) {	128	if ($_[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";	129	print "open successful, fh is $_[0]\n";
140	...	130	...
141	} else {	131	} else {
142	die "open failed: $!\n";	132	die "open failed: $!\n";
143	}	133	}
144	};	134	};
145		135
146	=item aio_close $fh, $callback	136	=item aio_close $fh, $callback
147		137
148	Asynchronously close a file and call the callback with the result code.	138	Asynchronously close a file and call the callback with the result
		139	code. I<WARNING:> although accepted, you should not pass in a perl
		140	filehandle here, as perl will likely close the file descriptor another
		141	time when the filehandle is destroyed. Normally, you can safely call perls
		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.
149		146
150	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	147	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
151		148
152	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	149	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
153		150
154	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	151	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
155	into the scalar given by C<data> and offset C<dataoffset> and calls the	152	into the scalar given by C<data> and offset C<dataoffset> and calls the
156	callback without the actual number of bytes read (or -1 on error, just	153	callback without the actual number of bytes read (or -1 on error, just
157	like the syscall).	154	like the syscall).
158		155
		156	The C<$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
159	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
160	offset C<0> within the scalar:	161	offset C<0> within the scalar:
161		162
162	aio_read $fh, 7, 15, $buffer, 0, sub {	163	aio_read $fh, 7, 15, $buffer, 0, sub {
163	$_[0] >= 0 or die "read error: $!";	164	$_[0] > 0 or die "read error: $!";
164	print "read <$buffer>\n";	165	print "read $_[0] bytes: <$buffer>\n";
165	};	166	};
166		167
167	=item aio_readahead $fh,$offset,$length, $callback	168	=item aio_readahead $fh,$offset,$length, $callback
168		169
169	Asynchronously reads the specified byte range into the page cache, using
170	the C<readahead> syscall. If that syscall doesn't exist the status will be
171	C<-1> and C<$!> is set to ENOSYS.
172
173	readahead() populates the page cache with data from a file so that	170	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<$offset>	171	subsequent reads from that file will not block on disk I/O. The C<$offset>
175	argument specifies the starting point from which data is to be read and	172	argument specifies the starting point from which data is to be read and
176	C<$length> specifies the number of bytes to be read. I/O is performed in	173	C<$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	174	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	175	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	176	(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.	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.
181		181
182	=item aio_stat $fh_or_path, $callback	182	=item aio_stat $fh_or_path, $callback
183		183
184	=item aio_lstat $fh, $callback	184	=item aio_lstat $fh, $callback
185		185
…		…
204	=item aio_unlink $pathname, $callback	204	=item aio_unlink $pathname, $callback
205		205
206	Asynchronously unlink (delete) a file and call the callback with the	206	Asynchronously unlink (delete) a file and call the callback with the
207	result code.	207	result code.
208		208
		209	=item aio_rmdir $pathname, $callback
		210
		211	Asynchronously rmdir (delete) a directory and call the callback with the
		212	result code.
		213
209	=item aio_fsync $fh, $callback	214	=item aio_fsync $fh, $callback
210		215
211	Asynchronously call fsync on the given filehandle and call the callback	216	Asynchronously call fsync on the given filehandle and call the callback
212	with the fsync result code.	217	with the fsync result code.
213		218
214	=item aio_fdatasync $fh, $callback	219	=item aio_fdatasync $fh, $callback
215		220
216	Asynchronously call fdatasync on the given filehandle and call the	221	Asynchronously call fdatasync on the given filehandle and call the
217	callback with the fdatasync result code.	222	callback with the fdatasync result code.
218		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
		330
219	=cut	331	=cut
		332
		333	# support function to convert a fd into a perl filehandle
		334	sub _fd2fh {
		335	return undef if $_[0] < 0;
		336
		337	# try to generate nice filehandles
		338	my $sym = "IO::AIO::fd#$_[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, ">&=$_[0]" # or this
		344	or return undef;
		345
		346	*$sym
		347	}
220		348
221	min_parallel 4;	349	min_parallel 4;
222		350
223	END {	351	END {
224	max_parallel 0;	352	max_parallel 0;
225	}	353	}
226		354
227	1;	355	1;
228		356
229	=back	357	=head2 FORK BEHAVIOUR
230		358
231	=head1 BUGS	359	Before the fork IO::AIO enters a quiescent state where no requests can be
232		360	added in other threads and no results will be processed. After the fork
233	- aio_open gives a fd, but all other functions expect a perl filehandle.	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.
234		364
235	=head1 SEE ALSO	365	=head1 SEE ALSO
236		366
237	L<Coro>, L<Linux::AIO>.	367	L<Coro>, L<Linux::AIO>.
238		368

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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 1.32 by root, Wed Aug 17 05:26:20 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 1.32 by root, Wed Aug 17 05:26:20 2005 UTC