[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 1.36 by root, Tue Aug 23 00:03:14 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_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
194	=item aio_fsync $fh, $callback	236	=item aio_fsync $fh, $callback
195		237
196	Asynchronously call fsync on the given filehandle and call the callback	238	Asynchronously call fsync on the given filehandle and call the callback
197	with the fsync result code.	239	with the fsync result code.
198		240
199	=item aio_fdatasync $fh, $callback	241	=item aio_fdatasync $fh, $callback
200		242
201	Asynchronously call fdatasync on the given filehandle and call the	243	Asynchronously call fdatasync on the given filehandle and call the
202	callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if	244	callback with the fdatasync result code.
203	C<fdatasync> is not available.	245
		246	If this call isn't available because your OS lacks it or it couldn't be
		247	detected, it will be emulated by calling C<fsync> instead.
204		248
205	=back	249	=back
206		250
207	=head2 SUPPORT FUNCTIONS	251	=head2 SUPPORT FUNCTIONS
208		252
…		…
266	IO::AIO::poll_wait, IO::AIO::poll_cb	310	IO::AIO::poll_wait, IO::AIO::poll_cb
267	if IO::AIO::nreqs;	311	if IO::AIO::nreqs;
268		312
269	=item IO::AIO::min_parallel $nthreads	313	=item IO::AIO::min_parallel $nthreads
270		314
271	Set the minimum number of AIO threads to C<$nthreads>. The default is	315	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	316	is C<4>, which means four asynchronous operations can be done at one time
273	(the number of outstanding operations, however, is unlimited).	317	(the number of outstanding operations, however, is unlimited).
		318
		319	IO::AIO starts threads only on demand, when an AIO request is queued and
		320	no free thread exists.
274		321
275	It is recommended to keep the number of threads low, as some Linux	322	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	323	kernel versions will scale negatively with the number of threads (higher
277	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	324	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
278	threads should be fine.	325	threads should be fine.
279		326
280	Under normal circumstances you don't need to call this function, as this	327	Under most circumstances you don't need to call this function, as the
281	module automatically starts some threads (the exact number might change,	328	module selects a default that is suitable for low to moderate load.
282	and is currently 4).
283		329
284	=item IO::AIO::max_parallel $nthreads	330	=item IO::AIO::max_parallel $nthreads
285		331
286	Sets the maximum number of AIO threads to C<$nthreads>. If more than	332	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
287	the specified number of threads are currently running, kill them. This	333	specified number of threads are currently running, this function kills
288	function blocks until the limit is reached.	334	them. This function blocks until the limit is reached.
		335
		336	While C<$nthreads> are zero, aio requests get queued but not executed
		337	until the number of threads has been increased again.
289		338
290	This module automatically runs C<max_parallel 0> at program end, to ensure	339	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.	340	that all threads are killed and that there are no outstanding requests.
292		341
293	Under normal circumstances you don't need to call this function.	342	Under normal circumstances you don't need to call this function.
…		…
297	Sets the maximum number of outstanding requests to C<$nreqs>. If you	346	Sets the maximum number of outstanding requests to C<$nreqs>. If you
298	try to queue up more than this number of requests, the caller will block until	347	try to queue up more than this number of requests, the caller will block until
299	some requests have been handled.	348	some requests have been handled.
300		349
301	The default is very large, so normally there is no practical limit. If you	350	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	351	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>.	352	this to a relatively low number, such as C<100>.
304		353
305	Under normal circumstances you don't need to call this function.	354	Under normal circumstances you don't need to call this function.
306		355
307	=back	356	=back
…		…
310		359
311	# support function to convert a fd into a perl filehandle	360	# support function to convert a fd into a perl filehandle
312	sub _fd2fh {	361	sub _fd2fh {
313	return undef if $_[0] < 0;	362	return undef if $_[0] < 0;
314		363
315	# try to be perl5.6-compatible	364	# try to generate nice filehandles
316	local *AIO_FH;	365	my $sym = "IO::AIO::fd#$_[0]";
317	open AIO_FH, "+<&=$_[0]"	366	local *$sym;
		367
		368	open *$sym, "+<&=$_[0]" # usually works under any unix
		369	or open *$sym, "<&=$_[0]" # cygwin needs this
		370	or open *$sym, ">&=$_[0]" # or this
318	or return undef;	371	or return undef;
319		372
320	*AIO_FH	373	*$sym
321	}	374	}
322		375
323	min_parallel 4;	376	min_parallel 4;
324		377
325	END {	378	END {
326	max_parallel 0;	379	max_parallel 0;
327	}	380	}
328		381
329	1;	382	1;
330		383
		384	=head2 FORK BEHAVIOUR
		385
		386	Before the fork, IO::AIO enters a quiescent state where no requests
		387	can be added in other threads and no results will be processed. After
		388	the fork the parent simply leaves the quiescent state and continues
		389	request/result processing, while the child clears the request/result
		390	queue (so the requests started before the fork will only be handled in
		391	the parent). Threats will be started on demand until the limit ste in the
		392	parent process has been reached again.
		393
331	=head1 SEE ALSO	394	=head1 SEE ALSO
332		395
333	L<Coro>, L<Linux::AIO>.	396	L<Coro>, L<Linux::AIO>.
334		397
335	=head1 AUTHOR	398	=head1 AUTHOR

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing IO-AIO/AIO.pm (file contents): Revision 1.22 by root, Wed Jul 20 21:55:27 2005 UTC vs. Revision 1.36 by root, Tue Aug 23 00:03:14 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 1.36 by root, Tue Aug 23 00:03:14 2005 UTC