[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 1.39 by root, Sun Aug 28 11:05:50 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_sendfile aio_read aio_write aio_open aio_close aio_stat
		71	aio_lstat aio_unlink aio_rmdir aio_readdir aio_symlink
69	aio_fsync aio_fdatasync aio_readahead);	72	aio_fsync aio_fdatasync aio_readahead);
70	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	73	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel
		74	max_outstanding nreqs);
71		75
72	require XSLoader;	76	require XSLoader;
73	XSLoader::load IO::AIO, $VERSION;	77	XSLoader::load IO::AIO, $VERSION;
74	}	78	}
75		79
…		…
83	which must be a code reference. This code reference will get called with	87	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	88	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	89	perl, which usually delivers "false") as it's sole argument when the given
86	syscall has been executed asynchronously.	90	syscall has been executed asynchronously.
87		91
88	All functions that expect a filehandle will also accept a file descriptor.	92	All functions expecting a filehandle keep a copy of the filehandle
		93	internally until the request has finished.
89		94
90	The filenames you pass to these routines I<must> be absolute. The reason	95	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	96	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	97	request is being executed, the current working directory could have
93	that you never change the current working directory.	98	changed. Alternatively, you can make sure that you never change the
		99	current working directory.
		100
		101	To encode pathnames to byte form, either make sure you either: a)
		102	always pass in filenames you got from outside (command line, readdir
		103	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
		104	your pathnames to the locale (or other) encoding in effect in the user
		105	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
		106	use something else.
94		107
95	=over 4	108	=over 4
96		109
97	=item aio_open $pathname, $flags, $mode, $callback	110	=item aio_open $pathname, $flags, $mode, $callback
98		111
…		…
139	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	152	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
140	into the scalar given by C<data> and offset C<dataoffset> and calls the	153	into the scalar given by C<data> and offset C<dataoffset> and calls the
141	callback without the actual number of bytes read (or -1 on error, just	154	callback without the actual number of bytes read (or -1 on error, just
142	like the syscall).	155	like the syscall).
143		156
		157	The C<$data> scalar I<MUST NOT> be modified in any way while the request
		158	is outstanding. Modifying it can result in segfaults or WW3 (if the
		159	necessary/optional hardware is installed).
		160
144	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	161	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
145	offset C<0> within the scalar:	162	offset C<0> within the scalar:
146		163
147	aio_read $fh, 7, 15, $buffer, 0, sub {	164	aio_read $fh, 7, 15, $buffer, 0, sub {
148	$_[0] > 0 or die "read error: $!";	165	$_[0] > 0 or die "read error: $!";
149	print "read $_[0] bytes: <$buffer>\n";	166	print "read $_[0] bytes: <$buffer>\n";
150	};	167	};
151		168
		169	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback
		170
		171	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
		172	reading at byte offset C<$in_offset>, and starts writing at the current
		173	file offset of C<$out_fh>. Because of that, it is not safe to issue more
		174	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
		175	other.
		176
		177	This call tries to make use of a native C<sendfile> syscall to provide
		178	zero-copy operation. For this to work, C<$out_fh> should refer to a
		179	socket, and C<$in_fh> should refer to mmap'able file.
		180
		181	If the native sendfile call fails or is not implemented, it will be
		182	emulated, so you can call C<aio_sendfile> on any type of filehandle
		183	regardless of the limitations of the operating system.
		184
		185	Please note, however, that C<aio_sendfile> can read more bytes from
		186	C<$in_fh> than are written, and there is no way to find out how many
		187	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
		188	provides the number of bytes written to C<$out_fh>. Only if the result
		189	value equals C<$length> one can assume that C<$length> bytes have been
		190	read.
		191
152	=item aio_readahead $fh,$offset,$length, $callback	192	=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		193
158	C<aio_readahead> populates the page cache with data from a file so that	194	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<$offset>	195	subsequent reads from that file will not block on disk I/O. The C<$offset>
160	argument specifies the starting point from which data is to be read and	196	argument specifies the starting point from which data is to be read and
161	C<$length> specifies the number of bytes to be read. I/O is performed in	197	C<$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	198	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	199	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	200	(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.	201	file. The current file offset of the file is left unchanged.
166		202
		203	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
		204	emulated by simply reading the data, which would have a similar effect.
		205
167	=item aio_stat $fh_or_path, $callback	206	=item aio_stat $fh_or_path, $callback
168		207
169	=item aio_lstat $fh, $callback	208	=item aio_lstat $fh, $callback
170		209
171	Works like perl's C<stat> or C<lstat> in void context. The callback will	210	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
189	=item aio_unlink $pathname, $callback	228	=item aio_unlink $pathname, $callback
190		229
191	Asynchronously unlink (delete) a file and call the callback with the	230	Asynchronously unlink (delete) a file and call the callback with the
192	result code.	231	result code.
193		232
		233	=item aio_rmdir $pathname, $callback
		234
		235	Asynchronously rmdir (delete) a directory and call the callback with the
		236	result code.
		237
		238	=item aio_readdir $pathname $callback
		239
		240	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
		241	directory (i.e. opendir + readdir + closedir). The entries will not be
		242	sorted, and will B<NOT> include the C<.> and C<..> entries.
		243
		244	The callback a single argument which is either C<undef> or an array-ref
		245	with the filenames.
		246
194	=item aio_fsync $fh, $callback	247	=item aio_fsync $fh, $callback
195		248
196	Asynchronously call fsync on the given filehandle and call the callback	249	Asynchronously call fsync on the given filehandle and call the callback
197	with the fsync result code.	250	with the fsync result code.
198		251
199	=item aio_fdatasync $fh, $callback	252	=item aio_fdatasync $fh, $callback
200		253
201	Asynchronously call fdatasync on the given filehandle and call the	254	Asynchronously call fdatasync on the given filehandle and call the
202	callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if	255	callback with the fdatasync result code.
203	C<fdatasync> is not available.	256
		257	If this call isn't available because your OS lacks it or it couldn't be
		258	detected, it will be emulated by calling C<fsync> instead.
204		259
205	=back	260	=back
206		261
207	=head2 SUPPORT FUNCTIONS	262	=head2 SUPPORT FUNCTIONS
208		263
…		…
266	IO::AIO::poll_wait, IO::AIO::poll_cb	321	IO::AIO::poll_wait, IO::AIO::poll_cb
267	if IO::AIO::nreqs;	322	if IO::AIO::nreqs;
268		323
269	=item IO::AIO::min_parallel $nthreads	324	=item IO::AIO::min_parallel $nthreads
270		325
271	Set the minimum number of AIO threads to C<$nthreads>. The default is	326	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	327	is C<4>, which means four asynchronous operations can be done at one time
273	(the number of outstanding operations, however, is unlimited).	328	(the number of outstanding operations, however, is unlimited).
		329
		330	IO::AIO starts threads only on demand, when an AIO request is queued and
		331	no free thread exists.
274		332
275	It is recommended to keep the number of threads low, as some Linux	333	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	334	kernel versions will scale negatively with the number of threads (higher
277	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	335	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
278	threads should be fine.	336	threads should be fine.
279		337
280	Under normal circumstances you don't need to call this function, as this	338	Under most circumstances you don't need to call this function, as the
281	module automatically starts some threads (the exact number might change,	339	module selects a default that is suitable for low to moderate load.
282	and is currently 4).
283		340
284	=item IO::AIO::max_parallel $nthreads	341	=item IO::AIO::max_parallel $nthreads
285		342
286	Sets the maximum number of AIO threads to C<$nthreads>. If more than	343	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
287	the specified number of threads are currently running, kill them. This	344	specified number of threads are currently running, this function kills
288	function blocks until the limit is reached.	345	them. This function blocks until the limit is reached.
		346
		347	While C<$nthreads> are zero, aio requests get queued but not executed
		348	until the number of threads has been increased again.
289		349
290	This module automatically runs C<max_parallel 0> at program end, to ensure	350	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.	351	that all threads are killed and that there are no outstanding requests.
292		352
293	Under normal circumstances you don't need to call this function.	353	Under normal circumstances you don't need to call this function.
…		…
297	Sets the maximum number of outstanding requests to C<$nreqs>. If you	357	Sets the maximum number of outstanding requests to C<$nreqs>. If you
298	try to queue up more than this number of requests, the caller will block until	358	try to queue up more than this number of requests, the caller will block until
299	some requests have been handled.	359	some requests have been handled.
300		360
301	The default is very large, so normally there is no practical limit. If you	361	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	362	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>.	363	this to a relatively low number, such as C<100>.
304		364
305	Under normal circumstances you don't need to call this function.	365	Under normal circumstances you don't need to call this function.
306		366
307	=back	367	=back
…		…
310		370
311	# support function to convert a fd into a perl filehandle	371	# support function to convert a fd into a perl filehandle
312	sub _fd2fh {	372	sub _fd2fh {
313	return undef if $_[0] < 0;	373	return undef if $_[0] < 0;
314		374
315	# try to be perl5.6-compatible	375	# try to generate nice filehandles
316	local *AIO_FH;	376	my $sym = "IO::AIO::fd#$_[0]";
317	open AIO_FH, "+<&=$_[0]"	377	local *$sym;
		378
		379	open *$sym, "+<&=$_[0]" # usually works under any unix
		380	or open *$sym, "<&=$_[0]" # cygwin needs this
		381	or open *$sym, ">&=$_[0]" # or this
318	or return undef;	382	or return undef;
319		383
320	*AIO_FH	384	*$sym
321	}	385	}
322		386
323	min_parallel 4;	387	min_parallel 4;
324		388
325	END {	389	END {
326	max_parallel 0;	390	max_parallel 0;
327	}	391	}
328		392
329	1;	393	1;
330		394
		395	=head2 FORK BEHAVIOUR
		396
		397	Before the fork, IO::AIO enters a quiescent state where no requests
		398	can be added in other threads and no results will be processed. After
		399	the fork the parent simply leaves the quiescent state and continues
		400	request/result processing, while the child clears the request/result
		401	queue (so the requests started before the fork will only be handled in
		402	the parent). Threats will be started on demand until the limit ste in the
		403	parent process has been reached again.
		404
331	=head1 SEE ALSO	405	=head1 SEE ALSO
332		406
333	L<Coro>, L<Linux::AIO>.	407	L<Coro>, L<Linux::AIO>.
334		408
335	=head1 AUTHOR	409	=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 1.39 by root, Sun Aug 28 11:05:50 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 1.39 by root, Sun Aug 28 11:05:50 2005 UTC