[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 1.34 by root, Thu Aug 18 16:32:10 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 = 1.5;
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_rmdir aio_symlink 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 $nthreads	93	The pathnames you pass to these routines I<must> be absolute and
		94	encoded in byte form. The reason for the former is that at the time the
		95	request is being executed, the current working directory could have
		96	changed. Alternatively, you can make sure that you never change the
		97	current working directory.
73		98
74	Sets the maximum number of AIO threads to C<$nthreads>. If more than	99	To encode pathnames to byte form, either make sure you either: a)
75	the specified number of threads are currently running, kill them. This	100	always pass in filenames you got from outside (command line, readdir
76	function blocks until the limit is reached.	101	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
		102	your pathnames to the locale (or other) encoding in effect in the user
		103	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
		104	use something else.
77		105
78	This module automatically runs C<max_parallel 0> at program end, to ensure	106	=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		107
121	=item aio_open $pathname, $flags, $mode, $callback	108	=item aio_open $pathname, $flags, $mode, $callback
122		109
123	Asynchronously open or create a file and call the callback with the	110	Asynchronously open or create a file and call the callback with a newly
124	filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this	111	created filehandle for the file.
125	might change in the future).
126		112
127	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	113	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
128	for an explanation.	114	for an explanation.
129		115
130	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a	116	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
131	list. They are the same as used in C<sysopen>.	117	list. They are the same as used by C<sysopen>.
		118
		119	Likewise, C<$mode> specifies the mode of the newly created file, if it
		120	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
		121	except that it is mandatory (i.e. use C<0> if you don't create new files,
		122	and C<0666> or C<0777> if you do).
132		123
133	Example:	124	Example:
134		125
135	aio_open "/etc/passwd", O_RDONLY, 0, sub {	126	aio_open "/etc/passwd", O_RDONLY, 0, sub {
136	if ($_[0] >= 0) {	127	if ($_[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";	128	print "open successful, fh is $_[0]\n";
140	...	129	...
141	} else {	130	} else {
142	die "open failed: $!\n";	131	die "open failed: $!\n";
143	}	132	}
144	};	133	};
145		134
146	=item aio_close $fh, $callback	135	=item aio_close $fh, $callback
147		136
148	Asynchronously close a file and call the callback with the result code.	137	Asynchronously close a file and call the callback with the result
		138	code. I<WARNING:> although accepted, you should not pass in a perl
		139	filehandle here, as perl will likely close the file descriptor another
		140	time when the filehandle is destroyed. Normally, you can safely call perls
		141	C<close> or just let filehandles go out of scope.
		142
		143	This is supposed to be a bug in the API, so that might change. It's
		144	therefore best to avoid this function.
149		145
150	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	146	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback
151		147
152	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	148	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback
153		149
154	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	150	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
155	into the scalar given by C<data> and offset C<dataoffset> and calls the	151	into the scalar given by C<data> and offset C<dataoffset> and calls the
156	callback without the actual number of bytes read (or -1 on error, just	152	callback without the actual number of bytes read (or -1 on error, just
157	like the syscall).	153	like the syscall).
158		154
		155	The C<$data> scalar I<MUST NOT> be modified in any way while the request
		156	is outstanding. Modifying it can result in segfaults or WW3 (if the
		157	necessary/optional hardware is installed).
		158
159	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at	159	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
160	offset C<0> within the scalar:	160	offset C<0> within the scalar:
161		161
162	aio_read $fh, 7, 15, $buffer, 0, sub {	162	aio_read $fh, 7, 15, $buffer, 0, sub {
163	$_[0] >= 0 or die "read error: $!";	163	$_[0] > 0 or die "read error: $!";
164	print "read <$buffer>\n";	164	print "read $_[0] bytes: <$buffer>\n";
165	};	165	};
166		166
167	=item aio_readahead $fh,$offset,$length, $callback	167	=item aio_readahead $fh,$offset,$length, $callback
168		168
169	Asynchronously reads the specified byte range into the page cache, using
170	the C<readahead> syscall. If that syscall doesn't exist the status will be
171	C<-1> and C<$!> is set to ENOSYS.
172
173	readahead() populates the page cache with data from a file so that	169	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<$offset>	170	subsequent reads from that file will not block on disk I/O. The C<$offset>
175	argument specifies the starting point from which data is to be read and	171	argument specifies the starting point from which data is to be read and
176	C<$length> specifies the number of bytes to be read. I/O is performed in	172	C<$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	173	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	174	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	175	(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.	176	file. The current file offset of the file is left unchanged.
		177
		178	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
		179	emulated by simply reading the data, which would have a similar effect.
181		180
182	=item aio_stat $fh_or_path, $callback	181	=item aio_stat $fh_or_path, $callback
183		182
184	=item aio_lstat $fh, $callback	183	=item aio_lstat $fh, $callback
185		184
…		…
204	=item aio_unlink $pathname, $callback	203	=item aio_unlink $pathname, $callback
205		204
206	Asynchronously unlink (delete) a file and call the callback with the	205	Asynchronously unlink (delete) a file and call the callback with the
207	result code.	206	result code.
208		207
		208	=item aio_rmdir $pathname, $callback
		209
		210	Asynchronously rmdir (delete) a directory and call the callback with the
		211	result code.
		212
209	=item aio_fsync $fh, $callback	213	=item aio_fsync $fh, $callback
210		214
211	Asynchronously call fsync on the given filehandle and call the callback	215	Asynchronously call fsync on the given filehandle and call the callback
212	with the fsync result code.	216	with the fsync result code.
213		217
214	=item aio_fdatasync $fh, $callback	218	=item aio_fdatasync $fh, $callback
215		219
216	Asynchronously call fdatasync on the given filehandle and call the	220	Asynchronously call fdatasync on the given filehandle and call the
217	callback with the fdatasync result code.	221	callback with the fdatasync result code.
218		222
		223	If this call isn't available because your OS lacks it or it couldn't be
		224	detected, it will be emulated by calling C<fsync> instead.
		225
		226	=back
		227
		228	=head2 SUPPORT FUNCTIONS
		229
		230	=over 4
		231
		232	=item $fileno = IO::AIO::poll_fileno
		233
		234	Return the I<request result pipe file descriptor>. This filehandle must be
		235	polled for reading by some mechanism outside this module (e.g. Event or
		236	select, see below or the SYNOPSIS). If the pipe becomes readable you have
		237	to call C<poll_cb> to check the results.
		238
		239	See C<poll_cb> for an example.
		240
		241	=item IO::AIO::poll_cb
		242
		243	Process all outstanding events on the result pipe. You have to call this
		244	regularly. Returns the number of events processed. Returns immediately
		245	when no events are outstanding.
		246
		247	Example: Install an Event watcher that automatically calls
		248	IO::AIO::poll_cb with high priority:
		249
		250	Event->io (fd => IO::AIO::poll_fileno,
		251	poll => 'r', async => 1,
		252	cb => \&IO::AIO::poll_cb);
		253
		254	=item IO::AIO::poll_wait
		255
		256	Wait till the result filehandle becomes ready for reading (simply does a
		257	C<select> on the filehandle. This is useful if you want to synchronously wait
		258	for some requests to finish).
		259
		260	See C<nreqs> for an example.
		261
		262	=item IO::AIO::nreqs
		263
		264	Returns the number of requests currently outstanding (i.e. for which their
		265	callback has not been invoked yet).
		266
		267	Example: wait till there are no outstanding requests anymore:
		268
		269	IO::AIO::poll_wait, IO::AIO::poll_cb
		270	while IO::AIO::nreqs;
		271
		272	=item IO::AIO::flush
		273
		274	Wait till all outstanding AIO requests have been handled.
		275
		276	Strictly equivalent to:
		277
		278	IO::AIO::poll_wait, IO::AIO::poll_cb
		279	while IO::AIO::nreqs;
		280
		281	=item IO::AIO::poll
		282
		283	Waits until some requests have been handled.
		284
		285	Strictly equivalent to:
		286
		287	IO::AIO::poll_wait, IO::AIO::poll_cb
		288	if IO::AIO::nreqs;
		289
		290	=item IO::AIO::min_parallel $nthreads
		291
		292	Set the minimum number of AIO threads to C<$nthreads>. The current default
		293	is C<4>, which means four asynchronous operations can be done at one time
		294	(the number of outstanding operations, however, is unlimited).
		295
		296	IO::AIO starts threads only on demand, when an AIO request is queued and
		297	no free thread exists.
		298
		299	It is recommended to keep the number of threads low, as some Linux
		300	kernel versions will scale negatively with the number of threads (higher
		301	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
		302	threads should be fine.
		303
		304	Under most circumstances you don't need to call this function, as the
		305	module selects a default that is suitable for low to moderate load.
		306
		307	=item IO::AIO::max_parallel $nthreads
		308
		309	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
		310	specified number of threads are currently running, this function kills
		311	them. This function blocks until the limit is reached.
		312
		313	While C<$nthreads> are zero, aio requests get queued but not executed
		314	until the number of threads has been increased again.
		315
		316	This module automatically runs C<max_parallel 0> at program end, to ensure
		317	that all threads are killed and that there are no outstanding requests.
		318
		319	Under normal circumstances you don't need to call this function.
		320
		321	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
		322
		323	Sets the maximum number of outstanding requests to C<$nreqs>. If you
		324	try to queue up more than this number of requests, the caller will block until
		325	some requests have been handled.
		326
		327	The default is very large, so normally there is no practical limit. If you
		328	queue up many requests in a loop it often improves speed if you set
		329	this to a relatively low number, such as C<100>.
		330
		331	Under normal circumstances you don't need to call this function.
		332
		333	=back
		334
219	=cut	335	=cut
		336
		337	# support function to convert a fd into a perl filehandle
		338	sub _fd2fh {
		339	return undef if $_[0] < 0;
		340
		341	# try to generate nice filehandles
		342	my $sym = "IO::AIO::fd#$_[0]";
		343	local *$sym;
		344
		345	open *$sym, "+<&=$_[0]" # usually works under any unix
		346	or open *$sym, "<&=$_[0]" # cygwin needs this
		347	or open *$sym, ">&=$_[0]" # or this
		348	or return undef;
		349
		350	*$sym
		351	}
220		352
221	min_parallel 4;	353	min_parallel 4;
222		354
223	END {	355	END {
224	max_parallel 0;	356	max_parallel 0;
225	}	357	}
226		358
227	1;	359	1;
228		360
229	=back	361	=head2 FORK BEHAVIOUR
230		362
231	=head1 BUGS	363	Before the fork, IO::AIO enters a quiescent state where no requests
232		364	can be added in other threads and no results will be processed. After
233	- aio_open gives a fd, but all other functions expect a perl filehandle.	365	the fork the parent simply leaves the quiescent state and continues
		366	request/result processing, while the child clears the request/result
		367	queue (so the requests started before the fork will only be handled in
		368	the parent). Threats will be started on demand until the limit ste in the
		369	parent process has been reached again.
234		370
235	=head1 SEE ALSO	371	=head1 SEE ALSO
236		372
237	L<Coro>, L<Linux::AIO>.	373	L<Coro>, L<Linux::AIO>.
238		374

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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 1.34 by root, Thu Aug 18 16:32:10 2005 UTC

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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 1.34 by root, Thu Aug 18 16:32:10 2005 UTC