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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.27 by root, Tue Aug 16 22:22:18 2005 UTC vs.
Revision 1.37 by root, Tue Aug 23 12:37:19 2005 UTC

…		…
63	use base 'Exporter';	63	use base 'Exporter';
64		64
65	use Fcntl ();	65	use Fcntl ();
66		66
67	BEGIN {	67	BEGIN {
68	$VERSION = 1.1;	68	$VERSION = 1.6;
69		69
70	@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
71	aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead);	71	aio_rmdir aio_readdir aio_symlink aio_fsync aio_fdatasync aio_readahead);
72	@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);
73		73
74	require XSLoader;	74	require XSLoader;
75	XSLoader::load IO::AIO, $VERSION;	75	XSLoader::load IO::AIO, $VERSION;
76	}	76	}
…		…
88	syscall has been executed asynchronously.	88	syscall has been executed asynchronously.
89		89
90	All functions expecting a filehandle keep a copy of the filehandle	90	All functions expecting a filehandle keep a copy of the filehandle
91	internally until the request has finished.	91	internally until the request has finished.
92		92
93	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
94	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
95	working directory could have changed. Alternatively, you can make sure	95	request is being executed, the current working directory could have
96	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.
97		105
98	=over 4	106	=over 4
99		107
100	=item aio_open $pathname, $flags, $mode, $callback	108	=item aio_open $pathname, $flags, $mode, $callback
101		109
…		…
142	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	150	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
143	into the scalar given by C<data> and offset C<dataoffset> and calls the	151	into the scalar given by C<data> and offset C<dataoffset> and calls the
144	callback without the actual number of bytes read (or -1 on error, just	152	callback without the actual number of bytes read (or -1 on error, just
145	like the syscall).	153	like the syscall).
146		154
		155	The C<$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
147	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
148	offset C<0> within the scalar:	160	offset C<0> within the scalar:
149		161
150	aio_read $fh, 7, 15, $buffer, 0, sub {	162	aio_read $fh, 7, 15, $buffer, 0, sub {
151	$_[0] > 0 or die "read error: $!";	163	$_[0] > 0 or die "read error: $!";
152	print "read $_[0] bytes: <$buffer>\n";	164	print "read $_[0] bytes: <$buffer>\n";
153	};	165	};
		166
		167	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback
		168
		169	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
		170	reading at byte offset C<$in_offset>, and starts writing at the current
		171	file offset of C<$out_fh>. Because of that, it is not safe to issue more
		172	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
		173	other.
		174
		175	This call tries to make use of a native C<sendfile> syscall to provide
		176	zero-copy operation. For this to work, C<$out_fh> should refer to a
		177	socket, and C<$in_fh> should refer to mmap'able file.
		178
		179	If the native sendfile call fails or is not implemented, it will be
		180	emulated, so you can call C<aio_sendfile> on any type of filehandle
		181	regardless of the limitations of the operating system.
		182
		183	Please note, however, that C<aio_sendfile> can read more bytes from
		184	C<$in_fh> than are written, and there is no way to find out how many
		185	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
		186	provides the number of bytes written to C<$out_fh>. Only if the result
		187	value equals C<$length> one can assume that C<$length> bytes have been
		188	read.
154		189
155	=item aio_readahead $fh,$offset,$length, $callback	190	=item aio_readahead $fh,$offset,$length, $callback
156		191
157	C<aio_readahead> populates the page cache with data from a file so that	192	C<aio_readahead> populates the page cache with data from a file so that
158	subsequent reads from that file will not block on disk I/O. The C<$offset>	193	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
196	=item aio_rmdir $pathname, $callback	231	=item aio_rmdir $pathname, $callback
197		232
198	Asynchronously rmdir (delete) a directory and call the callback with the	233	Asynchronously rmdir (delete) a directory and call the callback with the
199	result code.	234	result code.
200		235
		236	=item aio_readdir $pathname $callback
		237
		238	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
		239	directory (i.e. opendir + readdir + closedir). The entries will not be
		240	sorted, and will B<NOT> include the C<.> and C<..> entries.
		241
		242	The callback a single argument which is either C<undef> or an array-ref
		243	with the filenames.
		244
201	=item aio_fsync $fh, $callback	245	=item aio_fsync $fh, $callback
202		246
203	Asynchronously call fsync on the given filehandle and call the callback	247	Asynchronously call fsync on the given filehandle and call the callback
204	with the fsync result code.	248	with the fsync result code.
205		249
…		…
275	IO::AIO::poll_wait, IO::AIO::poll_cb	319	IO::AIO::poll_wait, IO::AIO::poll_cb
276	if IO::AIO::nreqs;	320	if IO::AIO::nreqs;
277		321
278	=item IO::AIO::min_parallel $nthreads	322	=item IO::AIO::min_parallel $nthreads
279		323
280	Set the minimum number of AIO threads to C<$nthreads>. The default is	324	Set the minimum number of AIO threads to C<$nthreads>. The current default
281	C<1>, which means a single asynchronous operation can be done at one time	325	is C<4>, which means four asynchronous operations can be done at one time
282	(the number of outstanding operations, however, is unlimited).	326	(the number of outstanding operations, however, is unlimited).
		327
		328	IO::AIO starts threads only on demand, when an AIO request is queued and
		329	no free thread exists.
283		330
284	It is recommended to keep the number of threads low, as some Linux	331	It is recommended to keep the number of threads low, as some Linux
285	kernel versions will scale negatively with the number of threads (higher	332	kernel versions will scale negatively with the number of threads (higher
286	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	333	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
287	threads should be fine.	334	threads should be fine.
288		335
289	Under normal circumstances you don't need to call this function, as this	336	Under most circumstances you don't need to call this function, as the
290	module automatically starts some threads (the exact number might change,	337	module selects a default that is suitable for low to moderate load.
291	and is currently 4).
292		338
293	=item IO::AIO::max_parallel $nthreads	339	=item IO::AIO::max_parallel $nthreads
294		340
295	Sets the maximum number of AIO threads to C<$nthreads>. If more than	341	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
296	the specified number of threads are currently running, kill them. This	342	specified number of threads are currently running, this function kills
297	function blocks until the limit is reached.	343	them. This function blocks until the limit is reached.
		344
		345	While C<$nthreads> are zero, aio requests get queued but not executed
		346	until the number of threads has been increased again.
298		347
299	This module automatically runs C<max_parallel 0> at program end, to ensure	348	This module automatically runs C<max_parallel 0> at program end, to ensure
300	that all threads are killed and that there are no outstanding requests.	349	that all threads are killed and that there are no outstanding requests.
301		350
302	Under normal circumstances you don't need to call this function.	351	Under normal circumstances you don't need to call this function.
…		…
306	Sets the maximum number of outstanding requests to C<$nreqs>. If you	355	Sets the maximum number of outstanding requests to C<$nreqs>. If you
307	try to queue up more than this number of requests, the caller will block until	356	try to queue up more than this number of requests, the caller will block until
308	some requests have been handled.	357	some requests have been handled.
309		358
310	The default is very large, so normally there is no practical limit. If you	359	The default is very large, so normally there is no practical limit. If you
311	queue up many requests in a loop it it often improves speed if you set	360	queue up many requests in a loop it often improves speed if you set
312	this to a relatively low number, such as C<100>.	361	this to a relatively low number, such as C<100>.
313		362
314	Under normal circumstances you don't need to call this function.	363	Under normal circumstances you don't need to call this function.
315		364
316	=back	365	=back
…		…
341		390
342	1;	391	1;
343		392
344	=head2 FORK BEHAVIOUR	393	=head2 FORK BEHAVIOUR
345		394
346	IO::AIO handles all outstanding AIO requests before the fork, destroys all	395	Before the fork, IO::AIO enters a quiescent state where no requests
347	AIO threads, and recreates them in both the parent and the child after the	396	can be added in other threads and no results will be processed. After
348	fork.	397	the fork the parent simply leaves the quiescent state and continues
349		398	request/result processing, while the child clears the request/result
		399	queue (so the requests started before the fork will only be handled in
		400	the parent). Threats will be started on demand until the limit ste in the
		401	parent process has been reached again.
350		402
351	=head1 SEE ALSO	403	=head1 SEE ALSO
352		404
353	L<Coro>, L<Linux::AIO>.	405	L<Coro>, L<Linux::AIO>.
354		406

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.27 by root, Tue Aug 16 22:22:18 2005 UTC vs. Revision 1.37 by root, Tue Aug 23 12:37:19 2005 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.27 by root, Tue Aug 16 22:22:18 2005 UTC vs.
Revision 1.37 by root, Tue Aug 23 12:37:19 2005 UTC