[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 1.37 by root, Tue Aug 23 12:37:19 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 = 1.6;
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_readdir 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
		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.
		189
152	=item aio_readahead $fh,$offset,$length, $callback	190	=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		191
158	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
159	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>
160	argument specifies the starting point from which data is to be read and	194	argument specifies the starting point from which data is to be read and
161	C<$length> specifies the number of bytes to be read. I/O is performed in	195	C<$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	196	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	197	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	198	(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.	199	file. The current file offset of the file is left unchanged.
166		200
		201	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
		202	emulated by simply reading the data, which would have a similar effect.
		203
167	=item aio_stat $fh_or_path, $callback	204	=item aio_stat $fh_or_path, $callback
168		205
169	=item aio_lstat $fh, $callback	206	=item aio_lstat $fh, $callback
170		207
171	Works like perl's C<stat> or C<lstat> in void context. The callback will	208	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
189	=item aio_unlink $pathname, $callback	226	=item aio_unlink $pathname, $callback
190		227
191	Asynchronously unlink (delete) a file and call the callback with the	228	Asynchronously unlink (delete) a file and call the callback with the
192	result code.	229	result code.
193		230
		231	=item aio_rmdir $pathname, $callback
		232
		233	Asynchronously rmdir (delete) a directory and call the callback with the
		234	result code.
		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
194	=item aio_fsync $fh, $callback	245	=item aio_fsync $fh, $callback
195		246
196	Asynchronously call fsync on the given filehandle and call the callback	247	Asynchronously call fsync on the given filehandle and call the callback
197	with the fsync result code.	248	with the fsync result code.
198		249
199	=item aio_fdatasync $fh, $callback	250	=item aio_fdatasync $fh, $callback
200		251
201	Asynchronously call fdatasync on the given filehandle and call the	252	Asynchronously call fdatasync on the given filehandle and call the
202	callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if	253	callback with the fdatasync result code.
203	C<fdatasync> is not available.	254
		255	If this call isn't available because your OS lacks it or it couldn't be
		256	detected, it will be emulated by calling C<fsync> instead.
204		257
205	=back	258	=back
206		259
207	=head2 SUPPORT FUNCTIONS	260	=head2 SUPPORT FUNCTIONS
208		261
…		…
266	IO::AIO::poll_wait, IO::AIO::poll_cb	319	IO::AIO::poll_wait, IO::AIO::poll_cb
267	if IO::AIO::nreqs;	320	if IO::AIO::nreqs;
268		321
269	=item IO::AIO::min_parallel $nthreads	322	=item IO::AIO::min_parallel $nthreads
270		323
271	Set the minimum number of AIO threads to C<$nthreads>. The default is	324	Set the minimum number of AIO threads to C<$nthreads>. The current default
272	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
273	(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.
274		330
275	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
276	kernel versions will scale negatively with the number of threads (higher	332	kernel versions will scale negatively with the number of threads (higher
277	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
278	threads should be fine.	334	threads should be fine.
279		335
280	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
281	module automatically starts some threads (the exact number might change,	337	module selects a default that is suitable for low to moderate load.
282	and is currently 4).
283		338
284	=item IO::AIO::max_parallel $nthreads	339	=item IO::AIO::max_parallel $nthreads
285		340
286	Sets the maximum number of AIO threads to C<$nthreads>. If more than	341	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
287	the specified number of threads are currently running, kill them. This	342	specified number of threads are currently running, this function kills
288	function blocks until the limit is reached.	343	them. This function blocks until the limit is reached.
		344
		345	While C<$nthreads> are zero, aio requests get queued but not executed
		346	until the number of threads has been increased again.
289		347
290	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
291	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.
292		350
293	Under normal circumstances you don't need to call this function.	351	Under normal circumstances you don't need to call this function.
…		…
297	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
298	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
299	some requests have been handled.	357	some requests have been handled.
300		358
301	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
302	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
303	this to a relatively low number, such as C<100>.	361	this to a relatively low number, such as C<100>.
304		362
305	Under normal circumstances you don't need to call this function.	363	Under normal circumstances you don't need to call this function.
306		364
307	=back	365	=back
…		…
310		368
311	# support function to convert a fd into a perl filehandle	369	# support function to convert a fd into a perl filehandle
312	sub _fd2fh {	370	sub _fd2fh {
313	return undef if $_[0] < 0;	371	return undef if $_[0] < 0;
314		372
315	# try to be perl5.6-compatible	373	# try to generate nice filehandles
316	local *AIO_FH;	374	my $sym = "IO::AIO::fd#$_[0]";
317	open AIO_FH, "+<&=$_[0]"	375	local *$sym;
		376
		377	open *$sym, "+<&=$_[0]" # usually works under any unix
		378	or open *$sym, "<&=$_[0]" # cygwin needs this
		379	or open *$sym, ">&=$_[0]" # or this
318	or return undef;	380	or return undef;
319		381
320	*AIO_FH	382	*$sym
321	}	383	}
322		384
323	min_parallel 4;	385	min_parallel 4;
324		386
325	END {	387	END {
326	max_parallel 0;	388	max_parallel 0;
327	}	389	}
328		390
329	1;	391	1;
330		392
		393	=head2 FORK BEHAVIOUR
		394
		395	Before the fork, IO::AIO enters a quiescent state where no requests
		396	can be added in other threads and no results will be processed. After
		397	the fork the parent simply leaves the quiescent state and continues
		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.
		402
331	=head1 SEE ALSO	403	=head1 SEE ALSO
332		404
333	L<Coro>, L<Linux::AIO>.	405	L<Coro>, L<Linux::AIO>.
334		406
335	=head1 AUTHOR	407	=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 1.37 by root, Tue Aug 23 12:37:19 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 1.37 by root, Tue Aug 23 12:37:19 2005 UTC