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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.21 by root, Wed Jul 13 00:13:09 2005 UTC vs.
Revision 1.50 by root, Sat Jun 24 16:27:02 2006 UTC

…		…
15		15
16	aio_read $fh, 30000, 1024, $buffer, 0, sub {	16	aio_read $fh, 30000, 1024, $buffer, 0, sub {
17	$_[0] > 0 or die "read error: $!";	17	$_[0] > 0 or die "read error: $!";
18	};	18	};
19		19
		20	# AnyEvent
		21	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
		22	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
		23
20	# Event	24	# Event
21	Event->io (fd => IO::AIO::poll_fileno,	25	Event->io (fd => IO::AIO::poll_fileno,
22	poll => 'r',	26	poll => 'r',
23	cb => \&IO::AIO::poll_cb);	27	cb => \&IO::AIO::poll_cb);
24		28
25	# Glib/Gtk2	29	# Glib/Gtk2
26	add_watch Glib::IO IO::AIO::poll_fileno,	30	add_watch Glib::IO IO::AIO::poll_fileno,
27	in => sub { IO::AIO::poll_cb, 1 };	31	in => sub { IO::AIO::poll_cb; 1 };
28		32
29	# Tk	33	# Tk
30	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",	34	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
31	readable => \&IO::AIO::poll_cb);	35	readable => \&IO::AIO::poll_cb);
32		36
…		…
48	not well-supported (Linux doesn't allow them on normal files currently,	52	not well-supported (Linux doesn't allow them on normal files currently,
49	for example), and they would only support aio_read and aio_write, so the	53	for example), and they would only support aio_read and aio_write, so the
50	remaining functionality would have to be implemented using threads anyway.	54	remaining functionality would have to be implemented using threads anyway.
51		55
52	Although the module will work with in the presence of other threads, it is	56	Although the module will work with in the presence of other threads, it is
53	currently not reentrant, so use appropriate locking yourself.	57	currently not reentrant, so use appropriate locking yourself, always call
		58	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other
		59	C<aio_> functions) recursively.
54		60
55	=cut	61	=cut
56		62
57	package IO::AIO;	63	package IO::AIO;
58		64
		65	no warnings;
		66
59	use base 'Exporter';	67	use base 'Exporter';
60		68
61	use Fcntl ();	69	use Fcntl ();
62		70
63	BEGIN {	71	BEGIN {
64	$VERSION = 0.9;	72	$VERSION = '1.8';
65		73
66	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink	74	@EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
		75	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
67	aio_fsync aio_fdatasync aio_readahead);	76	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move);
68	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	77	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel
		78	max_outstanding nreqs);
69		79
70	require XSLoader;	80	require XSLoader;
71	XSLoader::load IO::AIO, $VERSION;	81	XSLoader::load IO::AIO, $VERSION;
72	}	82	}
73		83
…		…
81	which must be a code reference. This code reference will get called with	91	which must be a code reference. This code reference will get called with
82	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	92	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
83	perl, which usually delivers "false") as it's sole argument when the given	93	perl, which usually delivers "false") as it's sole argument when the given
84	syscall has been executed asynchronously.	94	syscall has been executed asynchronously.
85		95
86	All functions that expect a filehandle will also accept a file descriptor.	96	All functions expecting a filehandle keep a copy of the filehandle
		97	internally until the request has finished.
87		98
88	The filenames you pass to these routines I<must> be absolute. The reason	99	The pathnames you pass to these routines I<must> be absolute and
89	for this is that at the time the request is being executed, the current	100	encoded in byte form. The reason for the former is that at the time the
90	working directory could have changed. Alternatively, you can make sure	101	request is being executed, the current working directory could have
91	that you never change the current working directory.	102	changed. Alternatively, you can make sure that you never change the
		103	current working directory.
		104
		105	To encode pathnames to byte form, either make sure you either: a)
		106	always pass in filenames you got from outside (command line, readdir
		107	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
		108	your pathnames to the locale (or other) encoding in effect in the user
		109	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
		110	use something else.
92		111
93	=over 4	112	=over 4
94		113
95	=item aio_open $pathname, $flags, $mode, $callback	114	=item aio_open $pathname, $flags, $mode, $callback->($fh)
96		115
97	Asynchronously open or create a file and call the callback with a newly	116	Asynchronously open or create a file and call the callback with a newly
98	created filehandle for the file.	117	created filehandle for the file.
99		118
100	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	119	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
…		…
117	} else {	136	} else {
118	die "open failed: $!\n";	137	die "open failed: $!\n";
119	}	138	}
120	};	139	};
121		140
122	=item aio_close $fh, $callback	141	=item aio_close $fh, $callback->($status)
123		142
124	Asynchronously close a file and call the callback with the result	143	Asynchronously close a file and call the callback with the result
125	code. I<WARNING:> although accepted, you should not pass in a perl	144	code. I<WARNING:> although accepted, you should not pass in a perl
126	filehandle here, as perl will likely close the file descriptor another	145	filehandle here, as perl will likely close the file descriptor another
127	time when the filehandle is destroyed. Normally, you can safely call perls	146	time when the filehandle is destroyed. Normally, you can safely call perls
128	C<close> or just let filehandles go out of scope.	147	C<close> or just let filehandles go out of scope.
129		148
130	This is supposed to be a bug in the API, so that might change. It's	149	This is supposed to be a bug in the API, so that might change. It's
131	therefore best to avoid this function.	150	therefore best to avoid this function.
132		151
133	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	152	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
134		153
135	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	154	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
136		155
137	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	156	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
138	into the scalar given by C<data> and offset C<dataoffset> and calls the	157	into the scalar given by C<data> and offset C<dataoffset> and calls the
139	callback without the actual number of bytes read (or -1 on error, just	158	callback without the actual number of bytes read (or -1 on error, just
140	like the syscall).	159	like the syscall).
141		160
		161	The C<$data> scalar I<MUST NOT> be modified in any way while the request
		162	is outstanding. Modifying it can result in segfaults or WW3 (if the
		163	necessary/optional hardware is installed).
		164
142	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	165	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
143	offset C<0> within the scalar:	166	offset C<0> within the scalar:
144		167
145	aio_read $fh, 7, 15, $buffer, 0, sub {	168	aio_read $fh, 7, 15, $buffer, 0, sub {
146	$_[0] > 0 or die "read error: $!";	169	$_[0] > 0 or die "read error: $!";
147	print "read $_[0] bytes: <$buffer>\n";	170	print "read $_[0] bytes: <$buffer>\n";
148	};	171	};
149		172
		173	=item aio_move $srcpath, $dstpath, $callback->($status)
		174
		175	[EXPERIMENTAL]
		176
		177	Try to move the I<file> (directories not supported as either source or destination)
		178	from C<$srcpath> to C<$dstpath> and call the callback with the C<0> (error) or C<-1> ok.
		179
		180	This is a composite request that tries to rename(2) the file first. If
		181	rename files with C<EXDEV>, it creates the destination file with mode 0200
		182	and copies the contents of the source file into it using C<aio_sendfile>,
		183	followed by restoring atime, mtime, access mode and uid/gid, in that
		184	order, and unlinking the C<$srcpath>.
		185
		186	If an error occurs, the partial destination file will be unlinked, if
		187	possible, except when setting atime, mtime, access mode and uid/gid, where
		188	errors are being ignored.
		189
		190	=cut
		191
		192	sub aio_move($$$) {
		193	my ($src, $dst, $cb) = @_;
		194
		195	aio_rename $src, $dst, sub {
		196	if ($_[0] && $! == Errno::EXDEV) {
		197	aio_open $src, O_RDONLY, 0, sub {
		198	if (my $src_fh = $_[0]) {
		199	my @stat = stat $src_fh;
		200
		201	aio_open $dst, O_WRONLY, 0200, sub {
		202	if (my $dst_fh = $_[0]) {
		203	aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		204	close $src_fh;
		205
		206	if ($_[0] == $stat[7]) {
		207	utime $stat[8], $stat[9], $dst;
		208	chmod $stat[2] & 07777, $dst_fh;
		209	chown $stat[4], $stat[5], $dst_fh;
		210	close $dst_fh;
		211
		212	aio_unlink $src, sub {
		213	$cb->($_[0]);
		214	};
		215	} else {
		216	my $errno = $!;
		217	aio_unlink $dst, sub {
		218	$! = $errno;
		219	$cb->(-1);
		220	};
		221	}
		222	};
		223	} else {
		224	$cb->(-1);
		225	}
		226	},
		227
		228	} else {
		229	$cb->(-1);
		230	}
		231	};
		232	} else {
		233	$cb->($_[0]);
		234	}
		235	};
		236	}
		237
		238	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		239
		240	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
		241	reading at byte offset C<$in_offset>, and starts writing at the current
		242	file offset of C<$out_fh>. Because of that, it is not safe to issue more
		243	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
		244	other.
		245
		246	This call tries to make use of a native C<sendfile> syscall to provide
		247	zero-copy operation. For this to work, C<$out_fh> should refer to a
		248	socket, and C<$in_fh> should refer to mmap'able file.
		249
		250	If the native sendfile call fails or is not implemented, it will be
		251	emulated, so you can call C<aio_sendfile> on any type of filehandle
		252	regardless of the limitations of the operating system.
		253
		254	Please note, however, that C<aio_sendfile> can read more bytes from
		255	C<$in_fh> than are written, and there is no way to find out how many
		256	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
		257	provides the number of bytes written to C<$out_fh>. Only if the result
		258	value equals C<$length> one can assume that C<$length> bytes have been
		259	read.
		260
150	=item aio_readahead $fh,$offset,$length, $callback	261	=item aio_readahead $fh,$offset,$length, $callback->($retval)
151
152	Asynchronously reads the specified byte range into the page cache, using
153	the C<readahead> syscall. If that syscall doesn't exist (likely if your OS
154	isn't Linux) the status will be C<-1> and C<$!> is set to C<ENOSYS>.
155		262
156	C<aio_readahead> populates the page cache with data from a file so that	263	C<aio_readahead> populates the page cache with data from a file so that
157	subsequent reads from that file will not block on disk I/O. The C<$offset>	264	subsequent reads from that file will not block on disk I/O. The C<$offset>
158	argument specifies the starting point from which data is to be read and	265	argument specifies the starting point from which data is to be read and
159	C<$length> specifies the number of bytes to be read. I/O is performed in	266	C<$length> specifies the number of bytes to be read. I/O is performed in
160	whole pages, so that offset is effectively rounded down to a page boundary	267	whole pages, so that offset is effectively rounded down to a page boundary
161	and bytes are read up to the next page boundary greater than or equal to	268	and bytes are read up to the next page boundary greater than or equal to
162	(off-set+length). C<aio_readahead> does not read beyond the end of the	269	(off-set+length). C<aio_readahead> does not read beyond the end of the
163	file. The current file offset of the file is left unchanged.	270	file. The current file offset of the file is left unchanged.
164		271
		272	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
		273	emulated by simply reading the data, which would have a similar effect.
		274
165	=item aio_stat $fh_or_path, $callback	275	=item aio_stat $fh_or_path, $callback->($status)
166		276
167	=item aio_lstat $fh, $callback	277	=item aio_lstat $fh, $callback->($status)
168		278
169	Works like perl's C<stat> or C<lstat> in void context. The callback will	279	Works like perl's C<stat> or C<lstat> in void context. The callback will
170	be called after the stat and the results will be available using C<stat _>	280	be called after the stat and the results will be available using C<stat _>
171	or C<-s _> etc...	281	or C<-s _> etc...
172		282
…		…
182	aio_stat "/etc/passwd", sub {	292	aio_stat "/etc/passwd", sub {
183	$_[0] and die "stat failed: $!";	293	$_[0] and die "stat failed: $!";
184	print "size is ", -s _, "\n";	294	print "size is ", -s _, "\n";
185	};	295	};
186		296
187	=item aio_unlink $pathname, $callback	297	=item aio_unlink $pathname, $callback->($status)
188		298
189	Asynchronously unlink (delete) a file and call the callback with the	299	Asynchronously unlink (delete) a file and call the callback with the
190	result code.	300	result code.
191		301
		302	=item aio_link $srcpath, $dstpath, $callback->($status)
		303
		304	Asynchronously create a new link to the existing object at C<$srcpath> at
		305	the path C<$dstpath> and call the callback with the result code.
		306
		307	=item aio_symlink $srcpath, $dstpath, $callback->($status)
		308
		309	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
		310	the path C<$dstpath> and call the callback with the result code.
		311
		312	=item aio_rename $srcpath, $dstpath, $callback->($status)
		313
		314	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
		315	rename(2) and call the callback with the result code.
		316
		317	=item aio_rmdir $pathname, $callback->($status)
		318
		319	Asynchronously rmdir (delete) a directory and call the callback with the
		320	result code.
		321
		322	=item aio_readdir $pathname, $callback->($entries)
		323
		324	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
		325	directory (i.e. opendir + readdir + closedir). The entries will not be
		326	sorted, and will B<NOT> include the C<.> and C<..> entries.
		327
		328	The callback a single argument which is either C<undef> or an array-ref
		329	with the filenames.
		330
		331	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		332
		333	Scans a directory (similar to C<aio_readdir>) and tries to separate the
		334	entries of directory C<$path> into two sets of names, ones you can recurse
		335	into (directories), and ones you cannot recurse into (everything else).
		336
		337	C<aio_scandir> is a composite request that consists of many
		338	aio-primitives. C<$maxreq> specifies the maximum number of outstanding
		339	aio requests that this function generates. If it is C<< <= 0 >>, then a
		340	suitable default will be chosen (currently 8).
		341
		342	On error, the callback is called without arguments, otherwise it receives
		343	two array-refs with path-relative entry names.
		344
		345	Example:
		346
		347	aio_scandir $dir, 0, sub {
		348	my ($dirs, $nondirs) = @_;
		349	print "real directories: @$dirs\n";
		350	print "everything else: @$nondirs\n";
		351	};
		352
		353	Implementation notes.
		354
		355	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
		356
		357	After reading the directory, the modification time, size etc. of the
		358	directory before and after the readdir is checked, and if they match, the
		359	link count will be used to decide how many entries are directories (if
		360	>= 2). Otherwise, no knowledge of the number of subdirectories will be
		361	assumed.
		362
		363	Then entires will be sorted into likely directories (everything without a
		364	non-initial dot) and likely non-directories (everything else). Then every
		365	entry + C</.> will be C<stat>'ed, likely directories first. This is often
		366	faster because filesystems might detect the type of the entry without
		367	reading the inode data (e.g. ext2fs filetype feature). If that succeeds,
		368	it assumes that the entry is a directory or a symlink to directory (which
		369	will be checked seperately).
		370
		371	If the known number of directories has been reached, the rest of the
		372	entries is assumed to be non-directories.
		373
		374	=cut
		375
		376	sub aio_scandir($$$) {
		377	my ($path, $maxreq, $cb) = @_;
		378
		379	$maxreq = 8 if $maxreq <= 0;
		380
		381	# stat once
		382	aio_stat $path, sub {
		383	return $cb->() if $_[0];
		384	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		385
		386	# read the directory entries
		387	aio_readdir $path, sub {
		388	my $entries = shift
		389	or return $cb->();
		390
		391	# stat the dir another time
		392	aio_stat $path, sub {
		393	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		394
		395	my $ndirs;
		396
		397	# take the slow route if anything looks fishy
		398	if ($hash1 ne $hash2) {
		399	$ndirs = -1;
		400	} else {
		401	# if nlink == 2, we are finished
		402	# on non-posix-fs's, we rely on nlink < 2
		403	$ndirs = (stat _)[3] - 2
		404	or return $cb->([], $entries);
		405	}
		406
		407	# sort into likely dirs and likely nondirs
		408	# dirs == files without ".", short entries first
		409	$entries = [map $_->[0],
		410	sort { $b->[1] cmp $a->[1] }
		411	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		412	@$entries];
		413
		414	my (@dirs, @nondirs);
		415
		416	my ($statcb, $schedcb);
		417	my $nreq = 0;
		418
		419	$schedcb = sub {
		420	if (@$entries) {
		421	if ($nreq < $maxreq) {
		422	my $ent = pop @$entries;
		423	$nreq++;
		424	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
		425	}
		426	} elsif (!$nreq) {
		427	# finished
		428	undef $statcb;
		429	undef $schedcb;
		430	$cb->(\@dirs, \@nondirs) if $cb;
		431	undef $cb;
		432	}
		433	};
		434	$statcb = sub {
		435	my ($status, $entry) = @_;
		436
		437	if ($status < 0) {
		438	$nreq--;
		439	push @nondirs, $entry;
		440	&$schedcb;
		441	} else {
		442	# need to check for real directory
		443	aio_lstat "$path/$entry", sub {
		444	$nreq--;
		445
		446	if (-d _) {
		447	push @dirs, $entry;
		448
		449	if (!--$ndirs) {
		450	push @nondirs, @$entries;
		451	$entries = [];
		452	}
		453	} else {
		454	push @nondirs, $entry;
		455	}
		456
		457	&$schedcb;
		458	}
		459	}
		460	};
		461
		462	&$schedcb while @$entries && $nreq < $maxreq;
		463	};
		464	};
		465	};
		466	}
		467
192	=item aio_fsync $fh, $callback	468	=item aio_fsync $fh, $callback->($status)
193		469
194	Asynchronously call fsync on the given filehandle and call the callback	470	Asynchronously call fsync on the given filehandle and call the callback
195	with the fsync result code.	471	with the fsync result code.
196		472
197	=item aio_fdatasync $fh, $callback	473	=item aio_fdatasync $fh, $callback->($status)
198		474
199	Asynchronously call fdatasync on the given filehandle and call the	475	Asynchronously call fdatasync on the given filehandle and call the
200	callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if	476	callback with the fdatasync result code.
201	C<fdatasync> is not available.	477
		478	If this call isn't available because your OS lacks it or it couldn't be
		479	detected, it will be emulated by calling C<fsync> instead.
202		480
203	=back	481	=back
204		482
205	=head2 SUPPORT FUNCTIONS	483	=head2 SUPPORT FUNCTIONS
206		484
…		…
264	IO::AIO::poll_wait, IO::AIO::poll_cb	542	IO::AIO::poll_wait, IO::AIO::poll_cb
265	if IO::AIO::nreqs;	543	if IO::AIO::nreqs;
266		544
267	=item IO::AIO::min_parallel $nthreads	545	=item IO::AIO::min_parallel $nthreads
268		546
269	Set the minimum number of AIO threads to C<$nthreads>. The default is	547	Set the minimum number of AIO threads to C<$nthreads>. The current default
270	C<1>, which means a single asynchronous operation can be done at one time	548	is C<4>, which means four asynchronous operations can be done at one time
271	(the number of outstanding operations, however, is unlimited).	549	(the number of outstanding operations, however, is unlimited).
		550
		551	IO::AIO starts threads only on demand, when an AIO request is queued and
		552	no free thread exists.
272		553
273	It is recommended to keep the number of threads low, as some Linux	554	It is recommended to keep the number of threads low, as some Linux
274	kernel versions will scale negatively with the number of threads (higher	555	kernel versions will scale negatively with the number of threads (higher
275	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	556	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
276	threads should be fine.	557	threads should be fine.
277		558
278	Under normal circumstances you don't need to call this function, as this	559	Under most circumstances you don't need to call this function, as the
279	module automatically starts some threads (the exact number might change,	560	module selects a default that is suitable for low to moderate load.
280	and is currently 4).
281		561
282	=item IO::AIO::max_parallel $nthreads	562	=item IO::AIO::max_parallel $nthreads
283		563
284	Sets the maximum number of AIO threads to C<$nthreads>. If more than	564	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
285	the specified number of threads are currently running, kill them. This	565	specified number of threads are currently running, this function kills
286	function blocks until the limit is reached.	566	them. This function blocks until the limit is reached.
		567
		568	While C<$nthreads> are zero, aio requests get queued but not executed
		569	until the number of threads has been increased again.
287		570
288	This module automatically runs C<max_parallel 0> at program end, to ensure	571	This module automatically runs C<max_parallel 0> at program end, to ensure
289	that all threads are killed and that there are no outstanding requests.	572	that all threads are killed and that there are no outstanding requests.
290		573
291	Under normal circumstances you don't need to call this function.	574	Under normal circumstances you don't need to call this function.
…		…
295	Sets the maximum number of outstanding requests to C<$nreqs>. If you	578	Sets the maximum number of outstanding requests to C<$nreqs>. If you
296	try to queue up more than this number of requests, the caller will block until	579	try to queue up more than this number of requests, the caller will block until
297	some requests have been handled.	580	some requests have been handled.
298		581
299	The default is very large, so normally there is no practical limit. If you	582	The default is very large, so normally there is no practical limit. If you
300	queue up many requests in a loop it it often improves speed if you set	583	queue up many requests in a loop it often improves speed if you set
301	this to a relatively low number, such as C<100>.	584	this to a relatively low number, such as C<100>.
302		585
303	Under normal circumstances you don't need to call this function.	586	Under normal circumstances you don't need to call this function.
304		587
305	=back	588	=back
…		…
308		591
309	# support function to convert a fd into a perl filehandle	592	# support function to convert a fd into a perl filehandle
310	sub _fd2fh {	593	sub _fd2fh {
311	return undef if $_[0] < 0;	594	return undef if $_[0] < 0;
312		595
313	# try to be perl5.6-compatible	596	# try to generate nice filehandles
314	local *AIO_FH;	597	my $sym = "IO::AIO::fd#$_[0]";
315	open AIO_FH, "+<&=$_[0]"	598	local *$sym;
		599
		600	open *$sym, "+<&=$_[0]" # usually works under any unix
		601	or open *$sym, "<&=$_[0]" # cygwin needs this
		602	or open *$sym, ">&=$_[0]" # or this
316	or return undef;	603	or return undef;
317		604
318	*AIO_FH	605	*$sym
319	}	606	}
320		607
321	min_parallel 4;	608	min_parallel 4;
322		609
323	END {	610	END {
324	max_parallel 0;	611	max_parallel 0;
325	}	612	}
326		613
327	1;	614	1;
328		615
		616	=head2 FORK BEHAVIOUR
		617
		618	Before the fork, IO::AIO enters a quiescent state where no requests
		619	can be added in other threads and no results will be processed. After
		620	the fork the parent simply leaves the quiescent state and continues
		621	request/result processing, while the child clears the request/result
		622	queue (so the requests started before the fork will only be handled in
		623	the parent). Threats will be started on demand until the limit ste in the
		624	parent process has been reached again.
		625
329	=head1 SEE ALSO	626	=head1 SEE ALSO
330		627
331	L<Coro>, L<Linux::AIO>.	628	L<Coro>, L<Linux::AIO>.
332		629
333	=head1 AUTHOR	630	=head1 AUTHOR

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Revision 1.21 by root, Wed Jul 13 00:13:09 2005 UTC vs.
Revision 1.50 by root, Sat Jun 24 16:27:02 2006 UTC