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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.24 by root, Sun Jul 31 18:45:48 2005 UTC vs.
Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC

…		…
14	aio_unlink "/tmp/file", sub { };	14	aio_unlink "/tmp/file", sub { };
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
		20	use IO::AIO 2; # version has aio objects
		21
		22	my $req = aio_unlink "/tmp/file", sub { };
		23	$req->cancel; # cancel request if still in queue
		24
		25	# AnyEvent
		26	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
		27	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
19		28
20	# Event	29	# Event
21	Event->io (fd => IO::AIO::poll_fileno,	30	Event->io (fd => IO::AIO::poll_fileno,
22	poll => 'r',	31	poll => 'r',
23	cb => \&IO::AIO::poll_cb);	32	cb => \&IO::AIO::poll_cb);
…		…
57	=cut	66	=cut
58		67
59	package IO::AIO;	68	package IO::AIO;
60		69
61	no warnings;	70	no warnings;
		71	use strict 'vars';
62		72
63	use base 'Exporter';	73	use base 'Exporter';
64		74
65	use Fcntl ();
66
67	BEGIN {	75	BEGIN {
68	$VERSION = 1.1;	76	our $VERSION = '1.99';
69		77
70	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink	78	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
		79	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
71	aio_fsync aio_fdatasync aio_readahead);	80	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
		81	aio_group);
72	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	82	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
		83
		84	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
73		85
74	require XSLoader;	86	require XSLoader;
75	XSLoader::load IO::AIO, $VERSION;	87	XSLoader::load ("IO::AIO", $VERSION);
76	}	88	}
77		89
78	=head1 FUNCTIONS	90	=head1 FUNCTIONS
79		91
80	=head2 AIO FUNCTIONS	92	=head2 AIO FUNCTIONS
…		…
88	syscall has been executed asynchronously.	100	syscall has been executed asynchronously.
89		101
90	All functions expecting a filehandle keep a copy of the filehandle	102	All functions expecting a filehandle keep a copy of the filehandle
91	internally until the request has finished.	103	internally until the request has finished.
92		104
		105	All non-composite requests (requests that are not broken down into
		106	multiple requests) return objects of type L<IO::AIO::REQ> that allow
		107	further manipulation of running requests.
		108
93	The filenames you pass to these routines I<must> be absolute. The reason	109	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	110	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	111	request is being executed, the current working directory could have
96	that you never change the current working directory.	112	changed. Alternatively, you can make sure that you never change the
		113	current working directory.
		114
		115	To encode pathnames to byte form, either make sure you either: a)
		116	always pass in filenames you got from outside (command line, readdir
		117	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
		118	your pathnames to the locale (or other) encoding in effect in the user
		119	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
		120	use something else.
97		121
98	=over 4	122	=over 4
99		123
100	=item aio_open $pathname, $flags, $mode, $callback	124	=item aio_open $pathname, $flags, $mode, $callback->($fh)
101		125
102	Asynchronously open or create a file and call the callback with a newly	126	Asynchronously open or create a file and call the callback with a newly
103	created filehandle for the file.	127	created filehandle for the file.
104		128
105	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	129	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
…		…
122	} else {	146	} else {
123	die "open failed: $!\n";	147	die "open failed: $!\n";
124	}	148	}
125	};	149	};
126		150
127	=item aio_close $fh, $callback	151	=item aio_close $fh, $callback->($status)
128		152
129	Asynchronously close a file and call the callback with the result	153	Asynchronously close a file and call the callback with the result
130	code. I<WARNING:> although accepted, you should not pass in a perl	154	code. I<WARNING:> although accepted, you should not pass in a perl
131	filehandle here, as perl will likely close the file descriptor another	155	filehandle here, as perl will likely close the file descriptor another
132	time when the filehandle is destroyed. Normally, you can safely call perls	156	time when the filehandle is destroyed. Normally, you can safely call perls
133	C<close> or just let filehandles go out of scope.	157	C<close> or just let filehandles go out of scope.
134		158
135	This is supposed to be a bug in the API, so that might change. It's	159	This is supposed to be a bug in the API, so that might change. It's
136	therefore best to avoid this function.	160	therefore best to avoid this function.
137		161
138	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	162	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
139		163
140	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	164	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
141		165
142	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	166	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	167	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	168	callback without the actual number of bytes read (or -1 on error, just
145	like the syscall).	169	like the syscall).
146		170
		171	The C<$data> scalar I<MUST NOT> be modified in any way while the request
		172	is outstanding. Modifying it can result in segfaults or WW3 (if the
		173	necessary/optional hardware is installed).
		174
147	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	175	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
148	offset C<0> within the scalar:	176	offset C<0> within the scalar:
149		177
150	aio_read $fh, 7, 15, $buffer, 0, sub {	178	aio_read $fh, 7, 15, $buffer, 0, sub {
151	$_[0] > 0 or die "read error: $!";	179	$_[0] > 0 or die "read error: $!";
152	print "read $_[0] bytes: <$buffer>\n";	180	print "read $_[0] bytes: <$buffer>\n";
153	};	181	};
154		182
		183	=item aio_move $srcpath, $dstpath, $callback->($status)
		184
		185	Try to move the I<file> (directories not supported as either source or
		186	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		187	the C<0> (error) or C<-1> ok.
		188
		189	This is a composite request that tries to rename(2) the file first. If
		190	rename files with C<EXDEV>, it creates the destination file with mode 0200
		191	and copies the contents of the source file into it using C<aio_sendfile>,
		192	followed by restoring atime, mtime, access mode and uid/gid, in that
		193	order, and unlinking the C<$srcpath>.
		194
		195	If an error occurs, the partial destination file will be unlinked, if
		196	possible, except when setting atime, mtime, access mode and uid/gid, where
		197	errors are being ignored.
		198
		199	=cut
		200
		201	sub aio_move($$$) {
		202	my ($src, $dst, $cb) = @_;
		203
		204	aio_rename $src, $dst, sub {
		205	if ($_[0] && $! == EXDEV) {
		206	aio_open $src, O_RDONLY, 0, sub {
		207	if (my $src_fh = $_[0]) {
		208	my @stat = stat $src_fh;
		209
		210	aio_open $dst, O_WRONLY, 0200, sub {
		211	if (my $dst_fh = $_[0]) {
		212	aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		213	close $src_fh;
		214
		215	if ($_[0] == $stat[7]) {
		216	utime $stat[8], $stat[9], $dst;
		217	chmod $stat[2] & 07777, $dst_fh;
		218	chown $stat[4], $stat[5], $dst_fh;
		219	close $dst_fh;
		220
		221	aio_unlink $src, sub {
		222	$cb->($_[0]);
		223	};
		224	} else {
		225	my $errno = $!;
		226	aio_unlink $dst, sub {
		227	$! = $errno;
		228	$cb->(-1);
		229	};
		230	}
		231	};
		232	} else {
		233	$cb->(-1);
		234	}
		235	},
		236
		237	} else {
		238	$cb->(-1);
		239	}
		240	};
		241	} else {
		242	$cb->($_[0]);
		243	}
		244	};
		245	}
		246
		247	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		248
		249	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
		250	reading at byte offset C<$in_offset>, and starts writing at the current
		251	file offset of C<$out_fh>. Because of that, it is not safe to issue more
		252	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
		253	other.
		254
		255	This call tries to make use of a native C<sendfile> syscall to provide
		256	zero-copy operation. For this to work, C<$out_fh> should refer to a
		257	socket, and C<$in_fh> should refer to mmap'able file.
		258
		259	If the native sendfile call fails or is not implemented, it will be
		260	emulated, so you can call C<aio_sendfile> on any type of filehandle
		261	regardless of the limitations of the operating system.
		262
		263	Please note, however, that C<aio_sendfile> can read more bytes from
		264	C<$in_fh> than are written, and there is no way to find out how many
		265	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
		266	provides the number of bytes written to C<$out_fh>. Only if the result
		267	value equals C<$length> one can assume that C<$length> bytes have been
		268	read.
		269
155	=item aio_readahead $fh,$offset,$length, $callback	270	=item aio_readahead $fh,$offset,$length, $callback->($retval)
156
157	Asynchronously reads the specified byte range into the page cache, using
158	the C<readahead> syscall. If that syscall doesn't exist (likely if your OS
159	isn't Linux) the status will be C<-1> and C<$!> is set to C<ENOSYS>.
160		271
161	C<aio_readahead> populates the page cache with data from a file so that	272	C<aio_readahead> populates the page cache with data from a file so that
162	subsequent reads from that file will not block on disk I/O. The C<$offset>	273	subsequent reads from that file will not block on disk I/O. The C<$offset>
163	argument specifies the starting point from which data is to be read and	274	argument specifies the starting point from which data is to be read and
164	C<$length> specifies the number of bytes to be read. I/O is performed in	275	C<$length> specifies the number of bytes to be read. I/O is performed in
165	whole pages, so that offset is effectively rounded down to a page boundary	276	whole pages, so that offset is effectively rounded down to a page boundary
166	and bytes are read up to the next page boundary greater than or equal to	277	and bytes are read up to the next page boundary greater than or equal to
167	(off-set+length). C<aio_readahead> does not read beyond the end of the	278	(off-set+length). C<aio_readahead> does not read beyond the end of the
168	file. The current file offset of the file is left unchanged.	279	file. The current file offset of the file is left unchanged.
169		280
		281	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
		282	emulated by simply reading the data, which would have a similar effect.
		283
170	=item aio_stat $fh_or_path, $callback	284	=item aio_stat $fh_or_path, $callback->($status)
171		285
172	=item aio_lstat $fh, $callback	286	=item aio_lstat $fh, $callback->($status)
173		287
174	Works like perl's C<stat> or C<lstat> in void context. The callback will	288	Works like perl's C<stat> or C<lstat> in void context. The callback will
175	be called after the stat and the results will be available using C<stat _>	289	be called after the stat and the results will be available using C<stat _>
176	or C<-s _> etc...	290	or C<-s _> etc...
177		291
…		…
187	aio_stat "/etc/passwd", sub {	301	aio_stat "/etc/passwd", sub {
188	$_[0] and die "stat failed: $!";	302	$_[0] and die "stat failed: $!";
189	print "size is ", -s _, "\n";	303	print "size is ", -s _, "\n";
190	};	304	};
191		305
192	=item aio_unlink $pathname, $callback	306	=item aio_unlink $pathname, $callback->($status)
193		307
194	Asynchronously unlink (delete) a file and call the callback with the	308	Asynchronously unlink (delete) a file and call the callback with the
195	result code.	309	result code.
196		310
		311	=item aio_link $srcpath, $dstpath, $callback->($status)
		312
		313	Asynchronously create a new link to the existing object at C<$srcpath> at
		314	the path C<$dstpath> and call the callback with the result code.
		315
		316	=item aio_symlink $srcpath, $dstpath, $callback->($status)
		317
		318	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
		319	the path C<$dstpath> and call the callback with the result code.
		320
		321	=item aio_rename $srcpath, $dstpath, $callback->($status)
		322
		323	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
		324	rename(2) and call the callback with the result code.
		325
		326	=item aio_rmdir $pathname, $callback->($status)
		327
		328	Asynchronously rmdir (delete) a directory and call the callback with the
		329	result code.
		330
		331	=item aio_readdir $pathname, $callback->($entries)
		332
		333	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
		334	directory (i.e. opendir + readdir + closedir). The entries will not be
		335	sorted, and will B<NOT> include the C<.> and C<..> entries.
		336
		337	The callback a single argument which is either C<undef> or an array-ref
		338	with the filenames.
		339
		340	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		341
		342	Scans a directory (similar to C<aio_readdir>) but additionally tries to
		343	separate the entries of directory C<$path> into two sets of names, ones
		344	you can recurse into (directories or links to them), and ones you cannot
		345	recurse into (everything else).
		346
		347	C<aio_scandir> is a composite request that consists of many sub
		348	requests. C<$maxreq> specifies the maximum number of outstanding aio
		349	requests that this function generates. If it is C<< <= 0 >>, then a
		350	suitable default will be chosen (currently 8).
		351
		352	On error, the callback is called without arguments, otherwise it receives
		353	two array-refs with path-relative entry names.
		354
		355	Example:
		356
		357	aio_scandir $dir, 0, sub {
		358	my ($dirs, $nondirs) = @_;
		359	print "real directories: @$dirs\n";
		360	print "everything else: @$nondirs\n";
		361	};
		362
		363	Implementation notes.
		364
		365	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
		366
		367	After reading the directory, the modification time, size etc. of the
		368	directory before and after the readdir is checked, and if they match (and
		369	isn't the current time), the link count will be used to decide how many
		370	entries are directories (if >= 2). Otherwise, no knowledge of the number
		371	of subdirectories will be assumed.
		372
		373	Then entries will be sorted into likely directories (everything without
		374	a non-initial dot currently) and likely non-directories (everything
		375	else). Then every entry plus an appended C</.> will be C<stat>'ed,
		376	likely directories first. If that succeeds, it assumes that the entry
		377	is a directory or a symlink to directory (which will be checked
		378	seperately). This is often faster than stat'ing the entry itself because
		379	filesystems might detect the type of the entry without reading the inode
		380	data (e.g. ext2fs filetype feature).
		381
		382	If the known number of directories (link count - 2) has been reached, the
		383	rest of the entries is assumed to be non-directories.
		384
		385	This only works with certainty on POSIX (= UNIX) filesystems, which
		386	fortunately are the vast majority of filesystems around.
		387
		388	It will also likely work on non-POSIX filesystems with reduced efficiency
		389	as those tend to return 0 or 1 as link counts, which disables the
		390	directory counting heuristic.
		391
		392	=cut
		393
		394	sub aio_scandir($$$) {
		395	my ($path, $maxreq, $cb) = @_;
		396
		397	$maxreq = 8 if $maxreq <= 0;
		398
		399	# stat once
		400	aio_stat $path, sub {
		401	return $cb->() if $_[0];
		402	my $now = time;
		403	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		404
		405	# read the directory entries
		406	aio_readdir $path, sub {
		407	my $entries = shift
		408	or return $cb->();
		409
		410	# stat the dir another time
		411	aio_stat $path, sub {
		412	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		413
		414	my $ndirs;
		415
		416	# take the slow route if anything looks fishy
		417	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		418	$ndirs = -1;
		419	} else {
		420	# if nlink == 2, we are finished
		421	# on non-posix-fs's, we rely on nlink < 2
		422	$ndirs = (stat _)[3] - 2
		423	or return $cb->([], $entries);
		424	}
		425
		426	# sort into likely dirs and likely nondirs
		427	# dirs == files without ".", short entries first
		428	$entries = [map $_->[0],
		429	sort { $b->[1] cmp $a->[1] }
		430	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		431	@$entries];
		432
		433	my (@dirs, @nondirs);
		434
		435	my ($statcb, $schedcb);
		436	my $nreq = 0;
		437
		438	$schedcb = sub {
		439	if (@$entries) {
		440	if ($nreq < $maxreq) {
		441	my $ent = pop @$entries;
		442	$nreq++;
		443	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
		444	}
		445	} elsif (!$nreq) {
		446	# finished
		447	undef $statcb;
		448	undef $schedcb;
		449	$cb->(\@dirs, \@nondirs) if $cb;
		450	undef $cb;
		451	}
		452	};
		453	$statcb = sub {
		454	my ($status, $entry) = @_;
		455
		456	if ($status < 0) {
		457	$nreq--;
		458	push @nondirs, $entry;
		459	&$schedcb;
		460	} else {
		461	# need to check for real directory
		462	aio_lstat "$path/$entry", sub {
		463	$nreq--;
		464
		465	if (-d _) {
		466	push @dirs, $entry;
		467
		468	if (!--$ndirs) {
		469	push @nondirs, @$entries;
		470	$entries = [];
		471	}
		472	} else {
		473	push @nondirs, $entry;
		474	}
		475
		476	&$schedcb;
		477	}
		478	}
		479	};
		480
		481	&$schedcb while @$entries && $nreq < $maxreq;
		482	};
		483	};
		484	};
		485	}
		486
197	=item aio_fsync $fh, $callback	487	=item aio_fsync $fh, $callback->($status)
198		488
199	Asynchronously call fsync on the given filehandle and call the callback	489	Asynchronously call fsync on the given filehandle and call the callback
200	with the fsync result code.	490	with the fsync result code.
201		491
202	=item aio_fdatasync $fh, $callback	492	=item aio_fdatasync $fh, $callback->($status)
203		493
204	Asynchronously call fdatasync on the given filehandle and call the	494	Asynchronously call fdatasync on the given filehandle and call the
205	callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if	495	callback with the fdatasync result code.
206	C<fdatasync> is not available.	496
		497	If this call isn't available because your OS lacks it or it couldn't be
		498	detected, it will be emulated by calling C<fsync> instead.
		499
		500	=item aio_group $callback->()
		501
		502	=item aio_sleep $fractional_seconds, $callback->() NOT EXPORTED
		503
		504	Mainly used for debugging and benchmarking, this aio request puts one of
		505	the request workers to sleep for the given time.
		506
		507	=back
		508
		509	=head2 IO::AIO::REQ CLASS
		510
		511	All non-aggregate C<aio_*> functions return an object of this class when
		512	called in non-void context.
		513
		514	A request always moves through the following five states in its lifetime,
		515	in order: B<ready> (request has been created, but has not been executed
		516	yet), B<execute> (request is currently being executed), B<pending>
		517	(request has been executed but callback has not been called yet),
		518	B<result> (results are being processed synchronously, includes calling the
		519	callback) and B<done> (request has reached the end of its lifetime and
		520	holds no resources anymore).
		521
		522	=over 4
		523
		524	=item $req->cancel
		525
		526	Cancels the request, if possible. Has the effect of skipping execution
		527	when entering the B<execute> state and skipping calling the callback when
		528	entering the the B<result> state, but will leave the request otherwise
		529	untouched. That means that requests that currently execute will not be
		530	stopped and resources held by the request will not be freed prematurely.
207		531
208	=back	532	=back
209		533
210	=head2 SUPPORT FUNCTIONS	534	=head2 SUPPORT FUNCTIONS
211		535
…		…
269	IO::AIO::poll_wait, IO::AIO::poll_cb	593	IO::AIO::poll_wait, IO::AIO::poll_cb
270	if IO::AIO::nreqs;	594	if IO::AIO::nreqs;
271		595
272	=item IO::AIO::min_parallel $nthreads	596	=item IO::AIO::min_parallel $nthreads
273		597
274	Set the minimum number of AIO threads to C<$nthreads>. The default is	598	Set the minimum number of AIO threads to C<$nthreads>. The current default
275	C<1>, which means a single asynchronous operation can be done at one time	599	is C<4>, which means four asynchronous operations can be done at one time
276	(the number of outstanding operations, however, is unlimited).	600	(the number of outstanding operations, however, is unlimited).
		601
		602	IO::AIO starts threads only on demand, when an AIO request is queued and
		603	no free thread exists.
277		604
278	It is recommended to keep the number of threads low, as some Linux	605	It is recommended to keep the number of threads low, as some Linux
279	kernel versions will scale negatively with the number of threads (higher	606	kernel versions will scale negatively with the number of threads (higher
280	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	607	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
281	threads should be fine.	608	threads should be fine.
282		609
283	Under normal circumstances you don't need to call this function, as this	610	Under most circumstances you don't need to call this function, as the
284	module automatically starts some threads (the exact number might change,	611	module selects a default that is suitable for low to moderate load.
285	and is currently 4).
286		612
287	=item IO::AIO::max_parallel $nthreads	613	=item IO::AIO::max_parallel $nthreads
288		614
289	Sets the maximum number of AIO threads to C<$nthreads>. If more than	615	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
290	the specified number of threads are currently running, kill them. This	616	specified number of threads are currently running, this function kills
291	function blocks until the limit is reached.	617	them. This function blocks until the limit is reached.
		618
		619	While C<$nthreads> are zero, aio requests get queued but not executed
		620	until the number of threads has been increased again.
292		621
293	This module automatically runs C<max_parallel 0> at program end, to ensure	622	This module automatically runs C<max_parallel 0> at program end, to ensure
294	that all threads are killed and that there are no outstanding requests.	623	that all threads are killed and that there are no outstanding requests.
295		624
296	Under normal circumstances you don't need to call this function.	625	Under normal circumstances you don't need to call this function.
…		…
300	Sets the maximum number of outstanding requests to C<$nreqs>. If you	629	Sets the maximum number of outstanding requests to C<$nreqs>. If you
301	try to queue up more than this number of requests, the caller will block until	630	try to queue up more than this number of requests, the caller will block until
302	some requests have been handled.	631	some requests have been handled.
303		632
304	The default is very large, so normally there is no practical limit. If you	633	The default is very large, so normally there is no practical limit. If you
305	queue up many requests in a loop it it often improves speed if you set	634	queue up many requests in a loop it often improves speed if you set
306	this to a relatively low number, such as C<100>.	635	this to a relatively low number, such as C<100>.
307		636
308	Under normal circumstances you don't need to call this function.	637	Under normal circumstances you don't need to call this function.
309		638
310	=back	639	=back
…		…
316	return undef if $_[0] < 0;	645	return undef if $_[0] < 0;
317		646
318	# try to generate nice filehandles	647	# try to generate nice filehandles
319	my $sym = "IO::AIO::fd#$_[0]";	648	my $sym = "IO::AIO::fd#$_[0]";
320	local *$sym;	649	local *$sym;
321	open *$sym, "+<&=$_[0]"	650
		651	open *$sym, "+<&=$_[0]" # usually works under any unix
		652	or open *$sym, "<&=$_[0]" # cygwin needs this
		653	or open *$sym, ">&=$_[0]" # or this
322	or return undef;	654	or return undef;
323		655
324	*$sym	656	*$sym
325	}	657	}
326		658
…		…
330	max_parallel 0;	662	max_parallel 0;
331	}	663	}
332		664
333	1;	665	1;
334		666
		667	=head2 FORK BEHAVIOUR
		668
		669	This module should do "the right thing" when the process using it forks:
		670
		671	Before the fork, IO::AIO enters a quiescent state where no requests
		672	can be added in other threads and no results will be processed. After
		673	the fork the parent simply leaves the quiescent state and continues
		674	request/result processing, while the child clears the request/result
		675	queue (so the requests started before the fork will only be handled in
		676	the parent). Threads will be started on demand until the limit ste in the
		677	parent process has been reached again.
		678
		679	In short: the parent will, after a short pause, continue as if fork had
		680	not been called, while the child will act as if IO::AIO has not been used
		681	yet.
		682
335	=head1 SEE ALSO	683	=head1 SEE ALSO
336		684
337	L<Coro>, L<Linux::AIO>.	685	L<Coro>, L<Linux::AIO> (obsolete).
338		686
339	=head1 AUTHOR	687	=head1 AUTHOR
340		688
341	Marc Lehmann <schmorp@schmorp.de>	689	Marc Lehmann <schmorp@schmorp.de>
342	http://home.schmorp.de/	690	http://home.schmorp.de/

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Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC