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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.14 by root, Mon Jul 11 02:53:59 2005 UTC vs.
Revision 1.53 by root, Sat Oct 21 23:20:29 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	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 });
		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);
24		33
25	# Glib/Gtk2	34	# Glib/Gtk2
26	add_watch Glib::IO IO::AIO::poll_fileno,	35	add_watch Glib::IO IO::AIO::poll_fileno,
27	\&IO::AIO::poll_cb;	36	in => sub { IO::AIO::poll_cb; 1 };
28		37
29	# Tk	38	# Tk
30	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",	39	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
31	readable => \&IO::AIO::poll_cb);	40	readable => \&IO::AIO::poll_cb);
32		41
…		…
48	not well-supported (Linux doesn't allow them on normal files currently,	57	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	58	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.	59	remaining functionality would have to be implemented using threads anyway.
51		60
52	Although the module will work with in the presence of other threads, it is	61	Although the module will work with in the presence of other threads, it is
53	currently not reentrant, so use appropriate locking yourself.	62	currently not reentrant, so use appropriate locking yourself, always call
		63	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other
		64	C<aio_> functions) recursively.
54		65
55	=cut	66	=cut
56		67
57	package IO::AIO;	68	package IO::AIO;
58		69
		70	no warnings;
		71	use strict 'vars';
		72
59	use base 'Exporter';	73	use base 'Exporter';
60		74
61	use Fcntl ();
62
63	BEGIN {	75	BEGIN {
64	$VERSION = 0.3;	76	our $VERSION = '1.99';
65		77
66	@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
67	aio_fsync aio_fdatasync aio_readahead);	80	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);	81	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
69		82
70	require XSLoader;	83	require XSLoader;
71	XSLoader::load IO::AIO, $VERSION;	84	XSLoader::load ("IO::AIO", $VERSION);
72	}	85	}
73		86
74	=head1 FUNCTIONS	87	=head1 FUNCTIONS
75		88
76	=head2 AIO FUNCTIONS	89	=head2 AIO FUNCTIONS
…		…
81	which must be a code reference. This code reference will get called with	94	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	95	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	96	perl, which usually delivers "false") as it's sole argument when the given
84	syscall has been executed asynchronously.	97	syscall has been executed asynchronously.
85		98
86	All functions that expect a filehandle will also accept a file descriptor.	99	All functions expecting a filehandle keep a copy of the filehandle
		100	internally until the request has finished.
87		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
88	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
89	is that at the time the request is being executed, the current working	107	encoded in byte form. The reason for the former is that at the time the
90	directory could have changed. Alternatively, you can make sure that you	108	request is being executed, the current working directory could have
		109	changed. Alternatively, you can make sure that you never change the
91	never change the current working directory.	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.
92		118
93	=over 4	119	=over 4
94		120
95	=item aio_open $pathname, $flags, $mode, $callback	121	=item aio_open $pathname, $flags, $mode, $callback->($fh)
96		122
97	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
98	created filehandle for the file.	124	created filehandle for the file.
99		125
100	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,
101	for an explanation.	127	for an explanation.
102		128
103	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a	129	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
104	list. They are the same as used in C<sysopen>.	130	list. They are the same as used by C<sysopen>.
		131
		132	Likewise, C<$mode> specifies the mode of the newly created file, if it
		133	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
		134	except that it is mandatory (i.e. use C<0> if you don't create new files,
		135	and C<0666> or C<0777> if you do).
105		136
106	Example:	137	Example:
107		138
108	aio_open "/etc/passwd", O_RDONLY, 0, sub {	139	aio_open "/etc/passwd", O_RDONLY, 0, sub {
109	if ($_[0]) {	140	if ($_[0]) {
…		…
112	} else {	143	} else {
113	die "open failed: $!\n";	144	die "open failed: $!\n";
114	}	145	}
115	};	146	};
116		147
117	=item aio_close $fh, $callback	148	=item aio_close $fh, $callback->($status)
118		149
119	Asynchronously close a file and call the callback with the result	150	Asynchronously close a file and call the callback with the result
120	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
121	filehandle here, as perl will likely close the file descriptor itself when	152	filehandle here, as perl will likely close the file descriptor another
122	the filehandle is destroyed. Normally, you can safely call perls C<close>	153	time when the filehandle is destroyed. Normally, you can safely call perls
123	or just let filehandles go out of scope.	154	C<close> or just let filehandles go out of scope.
124		155
		156	This is supposed to be a bug in the API, so that might change. It's
		157	therefore best to avoid this function.
		158
125	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	159	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
126		160
127	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	161	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
128		162
129	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>
130	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
131	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
132	like the syscall).	166	like the syscall).
133		167
		168	The C<$data> scalar I<MUST NOT> be modified in any way while the request
		169	is outstanding. Modifying it can result in segfaults or WW3 (if the
		170	necessary/optional hardware is installed).
		171
134	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at	172	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
135	offset C<0> within the scalar:	173	offset C<0> within the scalar:
136		174
137	aio_read $fh, 7, 15, $buffer, 0, sub {	175	aio_read $fh, 7, 15, $buffer, 0, sub {
138	$_[0] > 0 or die "read error: $!";	176	$_[0] > 0 or die "read error: $!";
139	print "read $_[0] bytes: <$buffer>\n";	177	print "read $_[0] bytes: <$buffer>\n";
140	};	178	};
141		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
142	=item aio_readahead $fh,$offset,$length, $callback	267	=item aio_readahead $fh,$offset,$length, $callback->($retval)
143		268
144	Asynchronously reads the specified byte range into the page cache, using
145	the C<readahead> syscall. If that syscall doesn't exist the status will be
146	C<-1> and C<$!> is set to ENOSYS.
147
148	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
149	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>
150	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
151	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
152	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
153	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
154	(off-set+length). 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
155	file. The current file offset of the file is left unchanged.	276	file. The current file offset of the file is left unchanged.
156		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
157	=item aio_stat $fh_or_path, $callback	281	=item aio_stat $fh_or_path, $callback->($status)
158		282
159	=item aio_lstat $fh, $callback	283	=item aio_lstat $fh, $callback->($status)
160		284
161	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
162	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 _>
163	or C<-s _> etc...	287	or C<-s _> etc...
164		288
…		…
174	aio_stat "/etc/passwd", sub {	298	aio_stat "/etc/passwd", sub {
175	$_[0] and die "stat failed: $!";	299	$_[0] and die "stat failed: $!";
176	print "size is ", -s _, "\n";	300	print "size is ", -s _, "\n";
177	};	301	};
178		302
179	=item aio_unlink $pathname, $callback	303	=item aio_unlink $pathname, $callback->($status)
180		304
181	Asynchronously unlink (delete) a file and call the callback with the	305	Asynchronously unlink (delete) a file and call the callback with the
182	result code.	306	result code.
183		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
184	=item aio_fsync $fh, $callback	484	=item aio_fsync $fh, $callback->($status)
185		485
186	Asynchronously call fsync on the given filehandle and call the callback	486	Asynchronously call fsync on the given filehandle and call the callback
187	with the fsync result code.	487	with the fsync result code.
188		488
189	=item aio_fdatasync $fh, $callback	489	=item aio_fdatasync $fh, $callback->($status)
190		490
191	Asynchronously call fdatasync on the given filehandle and call the	491	Asynchronously call fdatasync on the given filehandle and call the
192	callback with the fdatasync result code.	492	callback with the fdatasync result code.
193		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
194	=back	497	=back
195		498
		499	=head2 IO::AIO::REQ 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.
		521
		522	=back
		523
196	=head2 SUPPORT FUNCTIONS	524	=head2 SUPPORT FUNCTIONS
197		525
198	=over 4	526	=over 4
199		527
200	=item $fileno = IO::AIO::poll_fileno	528	=item $fileno = IO::AIO::poll_fileno
201		529
202	Return the I<request result pipe filehandle>. This filehandle must be	530	Return the I<request result pipe file descriptor>. This filehandle must be
203	polled for reading by some mechanism outside this module (e.g. Event	531	polled for reading by some mechanism outside this module (e.g. Event or
204	or select, see below). If the pipe becomes readable you have to call	532	select, see below or the SYNOPSIS). If the pipe becomes readable you have
205	C<poll_cb> to check the results.	533	to call C<poll_cb> to check the results.
206		534
207	See C<poll_cb> for an example.	535	See C<poll_cb> for an example.
208		536
209	=item IO::AIO::poll_cb	537	=item IO::AIO::poll_cb
210		538
211	Process all outstanding events on the result pipe. You have to call this	539	Process all outstanding events on the result pipe. You have to call this
212	regularly. Returns the number of events processed. Returns immediately	540	regularly. Returns the number of events processed. Returns immediately
213	when no events are outstanding.	541	when no events are outstanding.
214		542
215	You can use Event to multiplex, e.g.:	543	Example: Install an Event watcher that automatically calls
		544	IO::AIO::poll_cb with high priority:
216		545
217	Event->io (fd => IO::AIO::poll_fileno,	546	Event->io (fd => IO::AIO::poll_fileno,
218	poll => 'r', async => 1,	547	poll => 'r', async => 1,
219	cb => \&IO::AIO::poll_cb);	548	cb => \&IO::AIO::poll_cb);
220		549
221	=item IO::AIO::poll_wait	550	=item IO::AIO::poll_wait
222		551
223	Wait till the result filehandle becomes ready for reading (simply does a	552	Wait till the result filehandle becomes ready for reading (simply does a
224	select on the filehandle. This is useful if you want to synchronously wait	553	C<select> on the filehandle. This is useful if you want to synchronously wait
225	for some requests to finish).	554	for some requests to finish).
226		555
227	See C<nreqs> for an example.	556	See C<nreqs> for an example.
228		557
229	=item IO::AIO::nreqs	558	=item IO::AIO::nreqs
230		559
231	Returns the number of requests currently outstanding.	560	Returns the number of requests currently outstanding (i.e. for which their
		561	callback has not been invoked yet).
232		562
233	Example: wait till there are no outstanding requests anymore:	563	Example: wait till there are no outstanding requests anymore:
234		564
235	IO::AIO::poll_wait, IO::AIO::poll_cb	565	IO::AIO::poll_wait, IO::AIO::poll_cb
236	while IO::AIO::nreqs;	566	while IO::AIO::nreqs;
…		…
253	IO::AIO::poll_wait, IO::AIO::poll_cb	583	IO::AIO::poll_wait, IO::AIO::poll_cb
254	if IO::AIO::nreqs;	584	if IO::AIO::nreqs;
255		585
256	=item IO::AIO::min_parallel $nthreads	586	=item IO::AIO::min_parallel $nthreads
257		587
258	Set the minimum number of AIO threads to C<$nthreads>. The default is	588	Set the minimum number of AIO threads to C<$nthreads>. The current default
259	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
260	(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.
261		594
262	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
263	kernel versions will scale negatively with the number of threads (higher	596	kernel versions will scale negatively with the number of threads (higher
264	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
265	threads should be fine.	598	threads should be fine.
266		599
267	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
268	module automatically starts some threads (the exact number might change,	601	module selects a default that is suitable for low to moderate load.
269	and is currently 4).
270		602
271	=item IO::AIO::max_parallel $nthreads	603	=item IO::AIO::max_parallel $nthreads
272		604
273	Sets the maximum number of AIO threads to C<$nthreads>. If more than	605	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
274	the specified number of threads are currently running, kill them. This	606	specified number of threads are currently running, this function kills
275	function blocks until the limit is reached.	607	them. This function blocks until the limit is reached.
		608
		609	While C<$nthreads> are zero, aio requests get queued but not executed
		610	until the number of threads has been increased again.
276		611
277	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
278	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.
279		614
280	Under normal circumstances you don't need to call this function.	615	Under normal circumstances you don't need to call this function.
…		…
284	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
285	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
286	some requests have been handled.	621	some requests have been handled.
287		622
288	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
289	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
290	this to a relatively low number, such as C<100>.	625	this to a relatively low number, such as C<100>.
291		626
292	Under normal circumstances you don't need to call this function.	627	Under normal circumstances you don't need to call this function.
293		628
294	=back	629	=back
…		…
297		632
298	# support function to convert a fd into a perl filehandle	633	# support function to convert a fd into a perl filehandle
299	sub _fd2fh {	634	sub _fd2fh {
300	return undef if $_[0] < 0;	635	return undef if $_[0] < 0;
301		636
302	# try to be perl5.6-compatible	637	# try to generate nice filehandles
303	local *AIO_FH;	638	my $sym = "IO::AIO::fd#$_[0]";
304	open AIO_FH, "+<&=$_[0]"	639	local *$sym;
		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
305	or return undef;	644	or return undef;
306		645
307	*AIO_FH	646	*$sym
308	}	647	}
309		648
310	min_parallel 4;	649	min_parallel 4;
311		650
312	END {	651	END {
313	max_parallel 0;	652	max_parallel 0;
314	}	653	}
315		654
316	1;	655	1;
317		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
318	=head1 SEE ALSO	673	=head1 SEE ALSO
319		674
320	L<Coro>, L<Linux::AIO>.	675	L<Coro>, L<Linux::AIO> (obsolete).
321		676
322	=head1 AUTHOR	677	=head1 AUTHOR
323		678
324	Marc Lehmann <schmorp@schmorp.de>	679	Marc Lehmann <schmorp@schmorp.de>
325	http://home.schmorp.de/	680	http://home.schmorp.de/

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Revision 1.53 by root, Sat Oct 21 23:20:29 2006 UTC