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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.23 by root, Fri Jul 22 08:25:22 2005 UTC vs.
Revision 1.52 by root, Sat Oct 21 23:06:04 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 = '1.0';	76	our $VERSION = '1.8';
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);
72	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	81	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
73		82
74	require XSLoader;	83	require XSLoader;
75	XSLoader::load IO::AIO, $VERSION;	84	XSLoader::load ("IO::AIO", $VERSION);
76	}	85	}
77		86
78	=head1 FUNCTIONS	87	=head1 FUNCTIONS
79		88
80	=head2 AIO FUNCTIONS	89	=head2 AIO FUNCTIONS
…		…
88	syscall has been executed asynchronously.	97	syscall has been executed asynchronously.
89		98
90	All functions expecting a filehandle keep a copy of the filehandle	99	All functions expecting a filehandle keep a copy of the filehandle
91	internally until the request has finished.	100	internally until the request has finished.
92		101
		102	All non-composite requests (requests that are not broken down into
		103	multiple requests) return objects of type L<IO::AIO::REQ> that allow
		104	further manipulation of running requests.
		105
93	The filenames you pass to these routines I<must> be absolute. The reason	106	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	107	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	108	request is being executed, the current working directory could have
96	that you never change the current working directory.	109	changed. Alternatively, you can make sure that you never change the
		110	current working directory.
		111
		112	To encode pathnames to byte form, either make sure you either: a)
		113	always pass in filenames you got from outside (command line, readdir
		114	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
		115	your pathnames to the locale (or other) encoding in effect in the user
		116	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
		117	use something else.
97		118
98	=over 4	119	=over 4
99		120
100	=item aio_open $pathname, $flags, $mode, $callback	121	=item aio_open $pathname, $flags, $mode, $callback->($fh)
101		122
102	Asynchronously open or create a file and call the callback with a newly	123	Asynchronously open or create a file and call the callback with a newly
103	created filehandle for the file.	124	created filehandle for the file.
104		125
105	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	126	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
…		…
122	} else {	143	} else {
123	die "open failed: $!\n";	144	die "open failed: $!\n";
124	}	145	}
125	};	146	};
126		147
127	=item aio_close $fh, $callback	148	=item aio_close $fh, $callback->($status)
128		149
129	Asynchronously close a file and call the callback with the result	150	Asynchronously close a file and call the callback with the result
130	code. I<WARNING:> although accepted, you should not pass in a perl	151	code. I<WARNING:> although accepted, you should not pass in a perl
131	filehandle here, as perl will likely close the file descriptor another	152	filehandle here, as perl will likely close the file descriptor another
132	time when the filehandle is destroyed. Normally, you can safely call perls	153	time when the filehandle is destroyed. Normally, you can safely call perls
133	C<close> or just let filehandles go out of scope.	154	C<close> or just let filehandles go out of scope.
134		155
135	This is supposed to be a bug in the API, so that might change. It's	156	This is supposed to be a bug in the API, so that might change. It's
136	therefore best to avoid this function.	157	therefore best to avoid this function.
137		158
138	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	159	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
139		160
140	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	161	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
141		162
142	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	163	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	164	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	165	callback without the actual number of bytes read (or -1 on error, just
145	like the syscall).	166	like the syscall).
146		167
		168	The C<$data> scalar I<MUST NOT> be modified in any way while the request
		169	is outstanding. Modifying it can result in segfaults or WW3 (if the
		170	necessary/optional hardware is installed).
		171
147	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	172	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
148	offset C<0> within the scalar:	173	offset C<0> within the scalar:
149		174
150	aio_read $fh, 7, 15, $buffer, 0, sub {	175	aio_read $fh, 7, 15, $buffer, 0, sub {
151	$_[0] > 0 or die "read error: $!";	176	$_[0] > 0 or die "read error: $!";
152	print "read $_[0] bytes: <$buffer>\n";	177	print "read $_[0] bytes: <$buffer>\n";
153	};	178	};
154		179
		180	=item aio_move $srcpath, $dstpath, $callback->($status)
		181
		182	Try to move the I<file> (directories not supported as either source or
		183	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		184	the C<0> (error) or C<-1> ok.
		185
		186	This is a composite request that tries to rename(2) the file first. If
		187	rename files with C<EXDEV>, it creates the destination file with mode 0200
		188	and copies the contents of the source file into it using C<aio_sendfile>,
		189	followed by restoring atime, mtime, access mode and uid/gid, in that
		190	order, and unlinking the C<$srcpath>.
		191
		192	If an error occurs, the partial destination file will be unlinked, if
		193	possible, except when setting atime, mtime, access mode and uid/gid, where
		194	errors are being ignored.
		195
		196	=cut
		197
		198	sub aio_move($$$) {
		199	my ($src, $dst, $cb) = @_;
		200
		201	aio_rename $src, $dst, sub {
		202	if ($_[0] && $! == EXDEV) {
		203	aio_open $src, O_RDONLY, 0, sub {
		204	if (my $src_fh = $_[0]) {
		205	my @stat = stat $src_fh;
		206
		207	aio_open $dst, O_WRONLY, 0200, sub {
		208	if (my $dst_fh = $_[0]) {
		209	aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		210	close $src_fh;
		211
		212	if ($_[0] == $stat[7]) {
		213	utime $stat[8], $stat[9], $dst;
		214	chmod $stat[2] & 07777, $dst_fh;
		215	chown $stat[4], $stat[5], $dst_fh;
		216	close $dst_fh;
		217
		218	aio_unlink $src, sub {
		219	$cb->($_[0]);
		220	};
		221	} else {
		222	my $errno = $!;
		223	aio_unlink $dst, sub {
		224	$! = $errno;
		225	$cb->(-1);
		226	};
		227	}
		228	};
		229	} else {
		230	$cb->(-1);
		231	}
		232	},
		233
		234	} else {
		235	$cb->(-1);
		236	}
		237	};
		238	} else {
		239	$cb->($_[0]);
		240	}
		241	};
		242	}
		243
		244	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		245
		246	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
		247	reading at byte offset C<$in_offset>, and starts writing at the current
		248	file offset of C<$out_fh>. Because of that, it is not safe to issue more
		249	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
		250	other.
		251
		252	This call tries to make use of a native C<sendfile> syscall to provide
		253	zero-copy operation. For this to work, C<$out_fh> should refer to a
		254	socket, and C<$in_fh> should refer to mmap'able file.
		255
		256	If the native sendfile call fails or is not implemented, it will be
		257	emulated, so you can call C<aio_sendfile> on any type of filehandle
		258	regardless of the limitations of the operating system.
		259
		260	Please note, however, that C<aio_sendfile> can read more bytes from
		261	C<$in_fh> than are written, and there is no way to find out how many
		262	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
		263	provides the number of bytes written to C<$out_fh>. Only if the result
		264	value equals C<$length> one can assume that C<$length> bytes have been
		265	read.
		266
155	=item aio_readahead $fh,$offset,$length, $callback	267	=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		268
161	C<aio_readahead> populates the page cache with data from a file so that	269	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>	270	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	271	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	272	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	273	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	274	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	275	(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.	276	file. The current file offset of the file is left unchanged.
169		277
		278	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
		279	emulated by simply reading the data, which would have a similar effect.
		280
170	=item aio_stat $fh_or_path, $callback	281	=item aio_stat $fh_or_path, $callback->($status)
171		282
172	=item aio_lstat $fh, $callback	283	=item aio_lstat $fh, $callback->($status)
173		284
174	Works like perl's C<stat> or C<lstat> in void context. The callback will	285	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 _>	286	be called after the stat and the results will be available using C<stat _>
176	or C<-s _> etc...	287	or C<-s _> etc...
177		288
…		…
187	aio_stat "/etc/passwd", sub {	298	aio_stat "/etc/passwd", sub {
188	$_[0] and die "stat failed: $!";	299	$_[0] and die "stat failed: $!";
189	print "size is ", -s _, "\n";	300	print "size is ", -s _, "\n";
190	};	301	};
191		302
192	=item aio_unlink $pathname, $callback	303	=item aio_unlink $pathname, $callback->($status)
193		304
194	Asynchronously unlink (delete) a file and call the callback with the	305	Asynchronously unlink (delete) a file and call the callback with the
195	result code.	306	result code.
196		307
		308	=item aio_link $srcpath, $dstpath, $callback->($status)
		309
		310	Asynchronously create a new link to the existing object at C<$srcpath> at
		311	the path C<$dstpath> and call the callback with the result code.
		312
		313	=item aio_symlink $srcpath, $dstpath, $callback->($status)
		314
		315	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
		316	the path C<$dstpath> and call the callback with the result code.
		317
		318	=item aio_rename $srcpath, $dstpath, $callback->($status)
		319
		320	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
		321	rename(2) and call the callback with the result code.
		322
		323	=item aio_rmdir $pathname, $callback->($status)
		324
		325	Asynchronously rmdir (delete) a directory and call the callback with the
		326	result code.
		327
		328	=item aio_readdir $pathname, $callback->($entries)
		329
		330	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
		331	directory (i.e. opendir + readdir + closedir). The entries will not be
		332	sorted, and will B<NOT> include the C<.> and C<..> entries.
		333
		334	The callback a single argument which is either C<undef> or an array-ref
		335	with the filenames.
		336
		337	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		338
		339	Scans a directory (similar to C<aio_readdir>) but additionally tries to
		340	separate the entries of directory C<$path> into two sets of names, ones
		341	you can recurse into (directories or links to them), and ones you cannot
		342	recurse into (everything else).
		343
		344	C<aio_scandir> is a composite request that consists of many sub
		345	requests. C<$maxreq> specifies the maximum number of outstanding aio
		346	requests that this function generates. If it is C<< <= 0 >>, then a
		347	suitable default will be chosen (currently 8).
		348
		349	On error, the callback is called without arguments, otherwise it receives
		350	two array-refs with path-relative entry names.
		351
		352	Example:
		353
		354	aio_scandir $dir, 0, sub {
		355	my ($dirs, $nondirs) = @_;
		356	print "real directories: @$dirs\n";
		357	print "everything else: @$nondirs\n";
		358	};
		359
		360	Implementation notes.
		361
		362	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
		363
		364	After reading the directory, the modification time, size etc. of the
		365	directory before and after the readdir is checked, and if they match (and
		366	isn't the current time), the link count will be used to decide how many
		367	entries are directories (if >= 2). Otherwise, no knowledge of the number
		368	of subdirectories will be assumed.
		369
		370	Then entries will be sorted into likely directories (everything without
		371	a non-initial dot currently) and likely non-directories (everything
		372	else). Then every entry plus an appended C</.> will be C<stat>'ed,
		373	likely directories first. If that succeeds, it assumes that the entry
		374	is a directory or a symlink to directory (which will be checked
		375	seperately). This is often faster than stat'ing the entry itself because
		376	filesystems might detect the type of the entry without reading the inode
		377	data (e.g. ext2fs filetype feature).
		378
		379	If the known number of directories (link count - 2) has been reached, the
		380	rest of the entries is assumed to be non-directories.
		381
		382	This only works with certainty on POSIX (= UNIX) filesystems, which
		383	fortunately are the vast majority of filesystems around.
		384
		385	It will also likely work on non-POSIX filesystems with reduced efficiency
		386	as those tend to return 0 or 1 as link counts, which disables the
		387	directory counting heuristic.
		388
		389	=cut
		390
		391	sub aio_scandir($$$) {
		392	my ($path, $maxreq, $cb) = @_;
		393
		394	$maxreq = 8 if $maxreq <= 0;
		395
		396	# stat once
		397	aio_stat $path, sub {
		398	return $cb->() if $_[0];
		399	my $now = time;
		400	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		401
		402	# read the directory entries
		403	aio_readdir $path, sub {
		404	my $entries = shift
		405	or return $cb->();
		406
		407	# stat the dir another time
		408	aio_stat $path, sub {
		409	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		410
		411	my $ndirs;
		412
		413	# take the slow route if anything looks fishy
		414	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		415	$ndirs = -1;
		416	} else {
		417	# if nlink == 2, we are finished
		418	# on non-posix-fs's, we rely on nlink < 2
		419	$ndirs = (stat _)[3] - 2
		420	or return $cb->([], $entries);
		421	}
		422
		423	# sort into likely dirs and likely nondirs
		424	# dirs == files without ".", short entries first
		425	$entries = [map $_->[0],
		426	sort { $b->[1] cmp $a->[1] }
		427	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		428	@$entries];
		429
		430	my (@dirs, @nondirs);
		431
		432	my ($statcb, $schedcb);
		433	my $nreq = 0;
		434
		435	$schedcb = sub {
		436	if (@$entries) {
		437	if ($nreq < $maxreq) {
		438	my $ent = pop @$entries;
		439	$nreq++;
		440	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
		441	}
		442	} elsif (!$nreq) {
		443	# finished
		444	undef $statcb;
		445	undef $schedcb;
		446	$cb->(\@dirs, \@nondirs) if $cb;
		447	undef $cb;
		448	}
		449	};
		450	$statcb = sub {
		451	my ($status, $entry) = @_;
		452
		453	if ($status < 0) {
		454	$nreq--;
		455	push @nondirs, $entry;
		456	&$schedcb;
		457	} else {
		458	# need to check for real directory
		459	aio_lstat "$path/$entry", sub {
		460	$nreq--;
		461
		462	if (-d _) {
		463	push @dirs, $entry;
		464
		465	if (!--$ndirs) {
		466	push @nondirs, @$entries;
		467	$entries = [];
		468	}
		469	} else {
		470	push @nondirs, $entry;
		471	}
		472
		473	&$schedcb;
		474	}
		475	}
		476	};
		477
		478	&$schedcb while @$entries && $nreq < $maxreq;
		479	};
		480	};
		481	};
		482	}
		483
197	=item aio_fsync $fh, $callback	484	=item aio_fsync $fh, $callback->($status)
198		485
199	Asynchronously call fsync on the given filehandle and call the callback	486	Asynchronously call fsync on the given filehandle and call the callback
200	with the fsync result code.	487	with the fsync result code.
201		488
202	=item aio_fdatasync $fh, $callback	489	=item aio_fdatasync $fh, $callback->($status)
203		490
204	Asynchronously call fdatasync on the given filehandle and call the	491	Asynchronously call fdatasync on the given filehandle and call the
205	callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if	492	callback with the fdatasync result code.
206	C<fdatasync> is not available.	493
		494	If this call isn't available because your OS lacks it or it couldn't be
		495	detected, it will be emulated by calling C<fsync> instead.
		496
		497	=back
		498
		499	=head2 IO::AIO::CB CLASS
		500
		501	All non-aggregate C<aio_*> functions return an object of this class when
		502	called in non-void context.
		503
		504	A request always moves through the following five states in its lifetime,
		505	in order: B<ready> (request has been created, but has not been executed
		506	yet), B<execute> (request is currently being executed), B<pending>
		507	(request has been executed but callback has not been called yet),
		508	B<result> (results are being processed synchronously, includes calling the
		509	callback) and B<done> (request has reached the end of its lifetime and
		510	holds no resources anymore).
		511
		512	=over 4
		513
		514	=item $req->cancel
		515
		516	Cancels the request, if possible. Has the effect of skipping execution
		517	when entering the B<execute> state and skipping calling the callback when
		518	entering the the B<result> state, but will leave the request otherwise
		519	untouched. That means that requests that currently execute will not be
		520	stopped and resources held by the request will not be freed prematurely.
207		521
208	=back	522	=back
209		523
210	=head2 SUPPORT FUNCTIONS	524	=head2 SUPPORT FUNCTIONS
211		525
…		…
269	IO::AIO::poll_wait, IO::AIO::poll_cb	583	IO::AIO::poll_wait, IO::AIO::poll_cb
270	if IO::AIO::nreqs;	584	if IO::AIO::nreqs;
271		585
272	=item IO::AIO::min_parallel $nthreads	586	=item IO::AIO::min_parallel $nthreads
273		587
274	Set the minimum number of AIO threads to C<$nthreads>. The default is	588	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	589	is C<4>, which means four asynchronous operations can be done at one time
276	(the number of outstanding operations, however, is unlimited).	590	(the number of outstanding operations, however, is unlimited).
		591
		592	IO::AIO starts threads only on demand, when an AIO request is queued and
		593	no free thread exists.
277		594
278	It is recommended to keep the number of threads low, as some Linux	595	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	596	kernel versions will scale negatively with the number of threads (higher
280	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	597	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
281	threads should be fine.	598	threads should be fine.
282		599
283	Under normal circumstances you don't need to call this function, as this	600	Under most circumstances you don't need to call this function, as the
284	module automatically starts some threads (the exact number might change,	601	module selects a default that is suitable for low to moderate load.
285	and is currently 4).
286		602
287	=item IO::AIO::max_parallel $nthreads	603	=item IO::AIO::max_parallel $nthreads
288		604
289	Sets the maximum number of AIO threads to C<$nthreads>. If more than	605	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
290	the specified number of threads are currently running, kill them. This	606	specified number of threads are currently running, this function kills
291	function blocks until the limit is reached.	607	them. This function blocks until the limit is reached.
		608
		609	While C<$nthreads> are zero, aio requests get queued but not executed
		610	until the number of threads has been increased again.
292		611
293	This module automatically runs C<max_parallel 0> at program end, to ensure	612	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.	613	that all threads are killed and that there are no outstanding requests.
295		614
296	Under normal circumstances you don't need to call this function.	615	Under normal circumstances you don't need to call this function.
…		…
300	Sets the maximum number of outstanding requests to C<$nreqs>. If you	619	Sets the maximum number of outstanding requests to C<$nreqs>. If you
301	try to queue up more than this number of requests, the caller will block until	620	try to queue up more than this number of requests, the caller will block until
302	some requests have been handled.	621	some requests have been handled.
303		622
304	The default is very large, so normally there is no practical limit. If you	623	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	624	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>.	625	this to a relatively low number, such as C<100>.
307		626
308	Under normal circumstances you don't need to call this function.	627	Under normal circumstances you don't need to call this function.
309		628
310	=back	629	=back
…		…
316	return undef if $_[0] < 0;	635	return undef if $_[0] < 0;
317		636
318	# try to generate nice filehandles	637	# try to generate nice filehandles
319	my $sym = "IO::AIO::fd#$_[0]";	638	my $sym = "IO::AIO::fd#$_[0]";
320	local *$sym;	639	local *$sym;
321	open *$sym, "+<&=$_[0]"	640
		641	open *$sym, "+<&=$_[0]" # usually works under any unix
		642	or open *$sym, "<&=$_[0]" # cygwin needs this
		643	or open *$sym, ">&=$_[0]" # or this
322	or return undef;	644	or return undef;
323		645
324	*$sym	646	*$sym
325	}	647	}
326		648
…		…
330	max_parallel 0;	652	max_parallel 0;
331	}	653	}
332		654
333	1;	655	1;
334		656
		657	=head2 FORK BEHAVIOUR
		658
		659	This module should do "the right thing" when the process using it forks:
		660
		661	Before the fork, IO::AIO enters a quiescent state where no requests
		662	can be added in other threads and no results will be processed. After
		663	the fork the parent simply leaves the quiescent state and continues
		664	request/result processing, while the child clears the request/result
		665	queue (so the requests started before the fork will only be handled in
		666	the parent). Threads will be started on demand until the limit ste in the
		667	parent process has been reached again.
		668
		669	In short: the parent will, after a short pause, continue as if fork had
		670	not been called, while the child will act as if IO::AIO has not been used
		671	yet.
		672
335	=head1 SEE ALSO	673	=head1 SEE ALSO
336		674
337	L<Coro>, L<Linux::AIO>.	675	L<Coro>, L<Linux::AIO> (obsolete).
338		676
339	=head1 AUTHOR	677	=head1 AUTHOR
340		678
341	Marc Lehmann <schmorp@schmorp.de>	679	Marc Lehmann <schmorp@schmorp.de>
342	http://home.schmorp.de/	680	http://home.schmorp.de/

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Revision 1.52 by root, Sat Oct 21 23:06:04 2006 UTC