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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.22 by root, Wed Jul 20 21:55:27 2005 UTC vs.
Revision 1.34 by root, Thu Aug 18 16:32:10 2005 UTC

…		…
56		56
57	=cut	57	=cut
58		58
59	package IO::AIO;	59	package IO::AIO;
60		60
		61	no warnings;
		62
61	use base 'Exporter';	63	use base 'Exporter';
62		64
63	use Fcntl ();	65	use Fcntl ();
64		66
65	BEGIN {	67	BEGIN {
66	$VERSION = 0.9;	68	$VERSION = 1.5;
67		69
68	@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
69	aio_fsync aio_fdatasync aio_readahead);	71	aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead);
70	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	72	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
71		73
72	require XSLoader;	74	require XSLoader;
73	XSLoader::load IO::AIO, $VERSION;	75	XSLoader::load IO::AIO, $VERSION;
74	}	76	}
…		…
83	which must be a code reference. This code reference will get called with	85	which must be a code reference. This code reference will get called with
84	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	86	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
85	perl, which usually delivers "false") as it's sole argument when the given	87	perl, which usually delivers "false") as it's sole argument when the given
86	syscall has been executed asynchronously.	88	syscall has been executed asynchronously.
87		89
88	All functions that expect a filehandle will also accept a file descriptor.	90	All functions expecting a filehandle keep a copy of the filehandle
		91	internally until the request has finished.
89		92
90	The filenames you pass to these routines I<must> be absolute. The reason	93	The pathnames you pass to these routines I<must> be absolute and
91	for this is that at the time the request is being executed, the current	94	encoded in byte form. The reason for the former is that at the time the
92	working directory could have changed. Alternatively, you can make sure	95	request is being executed, the current working directory could have
93	that you never change the current working directory.	96	changed. Alternatively, you can make sure that you never change the
		97	current working directory.
		98
		99	To encode pathnames to byte form, either make sure you either: a)
		100	always pass in filenames you got from outside (command line, readdir
		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.
94		105
95	=over 4	106	=over 4
96		107
97	=item aio_open $pathname, $flags, $mode, $callback	108	=item aio_open $pathname, $flags, $mode, $callback
98		109
…		…
139	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	150	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
140	into the scalar given by C<data> and offset C<dataoffset> and calls the	151	into the scalar given by C<data> and offset C<dataoffset> and calls the
141	callback without the actual number of bytes read (or -1 on error, just	152	callback without the actual number of bytes read (or -1 on error, just
142	like the syscall).	153	like the syscall).
143		154
		155	The C<$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
144	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	159	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
145	offset C<0> within the scalar:	160	offset C<0> within the scalar:
146		161
147	aio_read $fh, 7, 15, $buffer, 0, sub {	162	aio_read $fh, 7, 15, $buffer, 0, sub {
148	$_[0] > 0 or die "read error: $!";	163	$_[0] > 0 or die "read error: $!";
149	print "read $_[0] bytes: <$buffer>\n";	164	print "read $_[0] bytes: <$buffer>\n";
150	};	165	};
151		166
152	=item aio_readahead $fh,$offset,$length, $callback	167	=item aio_readahead $fh,$offset,$length, $callback
153
154	Asynchronously reads the specified byte range into the page cache, using
155	the C<readahead> syscall. If that syscall doesn't exist (likely if your OS
156	isn't Linux) the status will be C<-1> and C<$!> is set to C<ENOSYS>.
157		168
158	C<aio_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
159	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>
160	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
161	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
162	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
163	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
164	(off-set+length). C<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
165	file. The current file offset of the file is left unchanged.	176	file. The current file offset of the file is left unchanged.
166		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.
		180
167	=item aio_stat $fh_or_path, $callback	181	=item aio_stat $fh_or_path, $callback
168		182
169	=item aio_lstat $fh, $callback	183	=item aio_lstat $fh, $callback
170		184
171	Works like perl's C<stat> or C<lstat> in void context. The callback will	185	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
189	=item aio_unlink $pathname, $callback	203	=item aio_unlink $pathname, $callback
190		204
191	Asynchronously unlink (delete) a file and call the callback with the	205	Asynchronously unlink (delete) a file and call the callback with the
192	result code.	206	result code.
193		207
		208	=item aio_rmdir $pathname, $callback
		209
		210	Asynchronously rmdir (delete) a directory and call the callback with the
		211	result code.
		212
194	=item aio_fsync $fh, $callback	213	=item aio_fsync $fh, $callback
195		214
196	Asynchronously call fsync on the given filehandle and call the callback	215	Asynchronously call fsync on the given filehandle and call the callback
197	with the fsync result code.	216	with the fsync result code.
198		217
199	=item aio_fdatasync $fh, $callback	218	=item aio_fdatasync $fh, $callback
200		219
201	Asynchronously call fdatasync on the given filehandle and call the	220	Asynchronously call fdatasync on the given filehandle and call the
202	callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if	221	callback with the fdatasync result code.
203	C<fdatasync> is not available.	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.
204		225
205	=back	226	=back
206		227
207	=head2 SUPPORT FUNCTIONS	228	=head2 SUPPORT FUNCTIONS
208		229
…		…
266	IO::AIO::poll_wait, IO::AIO::poll_cb	287	IO::AIO::poll_wait, IO::AIO::poll_cb
267	if IO::AIO::nreqs;	288	if IO::AIO::nreqs;
268		289
269	=item IO::AIO::min_parallel $nthreads	290	=item IO::AIO::min_parallel $nthreads
270		291
271	Set the minimum number of AIO threads to C<$nthreads>. The default is	292	Set the minimum number of AIO threads to C<$nthreads>. The current default
272	C<1>, which means a single asynchronous operation can be done at one time	293	is C<4>, which means four asynchronous operations can be done at one time
273	(the number of outstanding operations, however, is unlimited).	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.
274		298
275	It is recommended to keep the number of threads low, as some Linux	299	It is recommended to keep the number of threads low, as some Linux
276	kernel versions will scale negatively with the number of threads (higher	300	kernel versions will scale negatively with the number of threads (higher
277	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	301	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
278	threads should be fine.	302	threads should be fine.
279		303
280	Under normal circumstances you don't need to call this function, as this	304	Under most circumstances you don't need to call this function, as the
281	module automatically starts some threads (the exact number might change,	305	module selects a default that is suitable for low to moderate load.
282	and is currently 4).
283		306
284	=item IO::AIO::max_parallel $nthreads	307	=item IO::AIO::max_parallel $nthreads
285		308
286	Sets the maximum number of AIO threads to C<$nthreads>. If more than	309	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
287	the specified number of threads are currently running, kill them. This	310	specified number of threads are currently running, this function kills
288	function blocks until the limit is reached.	311	them. This function blocks until the limit is reached.
		312
		313	While C<$nthreads> are zero, aio requests get queued but not executed
		314	until the number of threads has been increased again.
289		315
290	This module automatically runs C<max_parallel 0> at program end, to ensure	316	This module automatically runs C<max_parallel 0> at program end, to ensure
291	that all threads are killed and that there are no outstanding requests.	317	that all threads are killed and that there are no outstanding requests.
292		318
293	Under normal circumstances you don't need to call this function.	319	Under normal circumstances you don't need to call this function.
…		…
297	Sets the maximum number of outstanding requests to C<$nreqs>. If you	323	Sets the maximum number of outstanding requests to C<$nreqs>. If you
298	try to queue up more than this number of requests, the caller will block until	324	try to queue up more than this number of requests, the caller will block until
299	some requests have been handled.	325	some requests have been handled.
300		326
301	The default is very large, so normally there is no practical limit. If you	327	The default is very large, so normally there is no practical limit. If you
302	queue up many requests in a loop it it often improves speed if you set	328	queue up many requests in a loop it often improves speed if you set
303	this to a relatively low number, such as C<100>.	329	this to a relatively low number, such as C<100>.
304		330
305	Under normal circumstances you don't need to call this function.	331	Under normal circumstances you don't need to call this function.
306		332
307	=back	333	=back
…		…
310		336
311	# support function to convert a fd into a perl filehandle	337	# support function to convert a fd into a perl filehandle
312	sub _fd2fh {	338	sub _fd2fh {
313	return undef if $_[0] < 0;	339	return undef if $_[0] < 0;
314		340
315	# try to be perl5.6-compatible	341	# try to generate nice filehandles
316	local *AIO_FH;	342	my $sym = "IO::AIO::fd#$_[0]";
317	open AIO_FH, "+<&=$_[0]"	343	local *$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
318	or return undef;	348	or return undef;
319		349
320	*AIO_FH	350	*$sym
321	}	351	}
322		352
323	min_parallel 4;	353	min_parallel 4;
324		354
325	END {	355	END {
326	max_parallel 0;	356	max_parallel 0;
327	}	357	}
328		358
329	1;	359	1;
330		360
		361	=head2 FORK BEHAVIOUR
		362
		363	Before the fork, IO::AIO enters a quiescent state where no requests
		364	can be added in other threads and no results will be processed. After
		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.
		370
331	=head1 SEE ALSO	371	=head1 SEE ALSO
332		372
333	L<Coro>, L<Linux::AIO>.	373	L<Coro>, L<Linux::AIO>.
334		374
335	=head1 AUTHOR	375	=head1 AUTHOR

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.22 by root, Wed Jul 20 21:55:27 2005 UTC vs. Revision 1.34 by root, Thu Aug 18 16:32:10 2005 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.22 by root, Wed Jul 20 21:55:27 2005 UTC vs.
Revision 1.34 by root, Thu Aug 18 16:32:10 2005 UTC