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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.32 by root, Wed Aug 17 05:26:20 2005 UTC vs.
Revision 1.57 by root, Sun Oct 22 01:28:31 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	# Event	20	# version 2+ has request and group objects
		21	use IO::AIO 2;
		22
		23	my $req = aio_unlink "/tmp/file", sub { };
		24	$req->cancel; # cancel request if still in queue
		25
		26	my $grp = aio_group sub { print "all stats done\n" };
		27	add $grp aio_stat "..." for ...;
		28
		29	# AnyEvent integration
		30	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
		31	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
		32
		33	# Event integration
21	Event->io (fd => IO::AIO::poll_fileno,	34	Event->io (fd => IO::AIO::poll_fileno,
22	poll => 'r',	35	poll => 'r',
23	cb => \&IO::AIO::poll_cb);	36	cb => \&IO::AIO::poll_cb);
24		37
25	# Glib/Gtk2	38	# Glib/Gtk2 integration
26	add_watch Glib::IO IO::AIO::poll_fileno,	39	add_watch Glib::IO IO::AIO::poll_fileno,
27	in => sub { IO::AIO::poll_cb; 1 };	40	in => sub { IO::AIO::poll_cb; 1 };
28		41
29	# Tk	42	# Tk integration
30	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",	43	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
31	readable => \&IO::AIO::poll_cb);	44	readable => \&IO::AIO::poll_cb);
32		45
33	# Danga::Socket	46	# Danga::Socket integration
34	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	47	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
35	\&IO::AIO::poll_cb);	48	\&IO::AIO::poll_cb);
36
37		49
38	=head1 DESCRIPTION	50	=head1 DESCRIPTION
39		51
40	This module implements asynchronous I/O using whatever means your	52	This module implements asynchronous I/O using whatever means your
41	operating system supports.	53	operating system supports.
…		…
57	=cut	69	=cut
58		70
59	package IO::AIO;	71	package IO::AIO;
60		72
61	no warnings;	73	no warnings;
		74	use strict 'vars';
62		75
63	use base 'Exporter';	76	use base 'Exporter';
64		77
65	use Fcntl ();
66
67	BEGIN {	78	BEGIN {
68	$VERSION = 1.3;	79	our $VERSION = '2.0';
69		80
70
71	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink	81	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
72	aio_rmdir aio_symlink aio_fsync aio_fdatasync aio_readahead);	82	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
		83	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
		84	aio_group);
73	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);
		86
		87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
74		88
75	require XSLoader;	89	require XSLoader;
76	XSLoader::load IO::AIO, $VERSION;	90	XSLoader::load ("IO::AIO", $VERSION);
77	}	91	}
78		92
79	=head1 FUNCTIONS	93	=head1 FUNCTIONS
80		94
81	=head2 AIO FUNCTIONS	95	=head2 AIO FUNCTIONS
…		…
89	syscall has been executed asynchronously.	103	syscall has been executed asynchronously.
90		104
91	All functions expecting a filehandle keep a copy of the filehandle	105	All functions expecting a filehandle keep a copy of the filehandle
92	internally until the request has finished.	106	internally until the request has finished.
93		107
		108	All requests return objects of type L<IO::AIO::REQ> that allow further
		109	manipulation of those requests while they are in-flight.
		110
94	The pathnames you pass to these routines I<must> be absolute and	111	The pathnames you pass to these routines I<must> be absolute and
95	encoded in byte form. The reason for the former is that at the time the	112	encoded in byte form. The reason for the former is that at the time the
96	request is being executed, the current working directory could have	113	request is being executed, the current working directory could have
97	changed. Alternatively, you can make sure that you never change the	114	changed. Alternatively, you can make sure that you never change the
98	current working directory.	115	current working directory.
…		…
104	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	121	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
105	use something else.	122	use something else.
106		123
107	=over 4	124	=over 4
108		125
109	=item aio_open $pathname, $flags, $mode, $callback	126	=item aio_open $pathname, $flags, $mode, $callback->($fh)
110		127
111	Asynchronously open or create a file and call the callback with a newly	128	Asynchronously open or create a file and call the callback with a newly
112	created filehandle for the file.	129	created filehandle for the file.
113		130
114	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	131	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
…		…
131	} else {	148	} else {
132	die "open failed: $!\n";	149	die "open failed: $!\n";
133	}	150	}
134	};	151	};
135		152
136	=item aio_close $fh, $callback	153	=item aio_close $fh, $callback->($status)
137		154
138	Asynchronously close a file and call the callback with the result	155	Asynchronously close a file and call the callback with the result
139	code. I<WARNING:> although accepted, you should not pass in a perl	156	code. I<WARNING:> although accepted, you should not pass in a perl
140	filehandle here, as perl will likely close the file descriptor another	157	filehandle here, as perl will likely close the file descriptor another
141	time when the filehandle is destroyed. Normally, you can safely call perls	158	time when the filehandle is destroyed. Normally, you can safely call perls
142	C<close> or just let filehandles go out of scope.	159	C<close> or just let filehandles go out of scope.
143		160
144	This is supposed to be a bug in the API, so that might change. It's	161	This is supposed to be a bug in the API, so that might change. It's
145	therefore best to avoid this function.	162	therefore best to avoid this function.
146		163
147	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	164	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
148		165
149	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	166	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
150		167
151	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	168	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
152	into the scalar given by C<data> and offset C<dataoffset> and calls the	169	into the scalar given by C<data> and offset C<dataoffset> and calls the
153	callback without the actual number of bytes read (or -1 on error, just	170	callback without the actual number of bytes read (or -1 on error, just
154	like the syscall).	171	like the syscall).
…		…
163	aio_read $fh, 7, 15, $buffer, 0, sub {	180	aio_read $fh, 7, 15, $buffer, 0, sub {
164	$_[0] > 0 or die "read error: $!";	181	$_[0] > 0 or die "read error: $!";
165	print "read $_[0] bytes: <$buffer>\n";	182	print "read $_[0] bytes: <$buffer>\n";
166	};	183	};
167		184
		185	=item aio_move $srcpath, $dstpath, $callback->($status)
		186
		187	Try to move the I<file> (directories not supported as either source or
		188	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		189	the C<0> (error) or C<-1> ok.
		190
		191	This is a composite request that tries to rename(2) the file first. If
		192	rename files with C<EXDEV>, it creates the destination file with mode 0200
		193	and copies the contents of the source file into it using C<aio_sendfile>,
		194	followed by restoring atime, mtime, access mode and uid/gid, in that
		195	order, and unlinking the C<$srcpath>.
		196
		197	If an error occurs, the partial destination file will be unlinked, if
		198	possible, except when setting atime, mtime, access mode and uid/gid, where
		199	errors are being ignored.
		200
		201	=cut
		202
		203	sub aio_move($$$) {
		204	my ($src, $dst, $cb) = @_;
		205
		206	my $grp = aio_group;
		207
		208	add $grp aio_rename $src, $dst, sub {
		209	if ($_[0] && $! == EXDEV) {
		210	add $grp aio_open $src, O_RDONLY, 0, sub {
		211	if (my $src_fh = $_[0]) {
		212	my @stat = stat $src_fh;
		213
		214	add $grp aio_open $dst, O_WRONLY, 0200, sub {
		215	if (my $dst_fh = $_[0]) {
		216	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		217	close $src_fh;
		218
		219	if ($_[0] == $stat[7]) {
		220	utime $stat[8], $stat[9], $dst;
		221	chmod $stat[2] & 07777, $dst_fh;
		222	chown $stat[4], $stat[5], $dst_fh;
		223	close $dst_fh;
		224
		225	add $grp aio_unlink $src, sub {
		226	$cb->($_[0]);
		227	};
		228	} else {
		229	my $errno = $!;
		230	add $grp aio_unlink $dst, sub {
		231	$! = $errno;
		232	$cb->(-1);
		233	};
		234	}
		235	};
		236	} else {
		237	$cb->(-1);
		238	}
		239	},
		240
		241	} else {
		242	$cb->(-1);
		243	}
		244	};
		245	} else {
		246	$cb->($_[0]);
		247	}
		248	};
		249
		250	$grp
		251	}
		252
		253	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		254
		255	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
		256	reading at byte offset C<$in_offset>, and starts writing at the current
		257	file offset of C<$out_fh>. Because of that, it is not safe to issue more
		258	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
		259	other.
		260
		261	This call tries to make use of a native C<sendfile> syscall to provide
		262	zero-copy operation. For this to work, C<$out_fh> should refer to a
		263	socket, and C<$in_fh> should refer to mmap'able file.
		264
		265	If the native sendfile call fails or is not implemented, it will be
		266	emulated, so you can call C<aio_sendfile> on any type of filehandle
		267	regardless of the limitations of the operating system.
		268
		269	Please note, however, that C<aio_sendfile> can read more bytes from
		270	C<$in_fh> than are written, and there is no way to find out how many
		271	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
		272	provides the number of bytes written to C<$out_fh>. Only if the result
		273	value equals C<$length> one can assume that C<$length> bytes have been
		274	read.
		275
168	=item aio_readahead $fh,$offset,$length, $callback	276	=item aio_readahead $fh,$offset,$length, $callback->($retval)
169		277
170	C<aio_readahead> populates the page cache with data from a file so that	278	C<aio_readahead> populates the page cache with data from a file so that
171	subsequent reads from that file will not block on disk I/O. The C<$offset>	279	subsequent reads from that file will not block on disk I/O. The C<$offset>
172	argument specifies the starting point from which data is to be read and	280	argument specifies the starting point from which data is to be read and
173	C<$length> specifies the number of bytes to be read. I/O is performed in	281	C<$length> specifies the number of bytes to be read. I/O is performed in
…		…
177	file. The current file offset of the file is left unchanged.	285	file. The current file offset of the file is left unchanged.
178		286
179	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	287	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
180	emulated by simply reading the data, which would have a similar effect.	288	emulated by simply reading the data, which would have a similar effect.
181		289
182	=item aio_stat $fh_or_path, $callback	290	=item aio_stat $fh_or_path, $callback->($status)
183		291
184	=item aio_lstat $fh, $callback	292	=item aio_lstat $fh, $callback->($status)
185		293
186	Works like perl's C<stat> or C<lstat> in void context. The callback will	294	Works like perl's C<stat> or C<lstat> in void context. The callback will
187	be called after the stat and the results will be available using C<stat _>	295	be called after the stat and the results will be available using C<stat _>
188	or C<-s _> etc...	296	or C<-s _> etc...
189		297
…		…
199	aio_stat "/etc/passwd", sub {	307	aio_stat "/etc/passwd", sub {
200	$_[0] and die "stat failed: $!";	308	$_[0] and die "stat failed: $!";
201	print "size is ", -s _, "\n";	309	print "size is ", -s _, "\n";
202	};	310	};
203		311
204	=item aio_unlink $pathname, $callback	312	=item aio_unlink $pathname, $callback->($status)
205		313
206	Asynchronously unlink (delete) a file and call the callback with the	314	Asynchronously unlink (delete) a file and call the callback with the
207	result code.	315	result code.
208		316
		317	=item aio_link $srcpath, $dstpath, $callback->($status)
		318
		319	Asynchronously create a new link to the existing object at C<$srcpath> at
		320	the path C<$dstpath> and call the callback with the result code.
		321
		322	=item aio_symlink $srcpath, $dstpath, $callback->($status)
		323
		324	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
		325	the path C<$dstpath> and call the callback with the result code.
		326
		327	=item aio_rename $srcpath, $dstpath, $callback->($status)
		328
		329	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
		330	rename(2) and call the callback with the result code.
		331
209	=item aio_rmdir $pathname, $callback	332	=item aio_rmdir $pathname, $callback->($status)
210		333
211	Asynchronously rmdir (delete) a directory and call the callback with the	334	Asynchronously rmdir (delete) a directory and call the callback with the
212	result code.	335	result code.
213		336
		337	=item aio_readdir $pathname, $callback->($entries)
		338
		339	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
		340	directory (i.e. opendir + readdir + closedir). The entries will not be
		341	sorted, and will B<NOT> include the C<.> and C<..> entries.
		342
		343	The callback a single argument which is either C<undef> or an array-ref
		344	with the filenames.
		345
		346	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		347
		348	Scans a directory (similar to C<aio_readdir>) but additionally tries to
		349	separate the entries of directory C<$path> into two sets of names, ones
		350	you can recurse into (directories or links to them), and ones you cannot
		351	recurse into (everything else).
		352
		353	C<aio_scandir> is a composite request that consists of many sub
		354	requests. C<$maxreq> specifies the maximum number of outstanding aio
		355	requests that this function generates. If it is C<< <= 0 >>, then a
		356	suitable default will be chosen (currently 8).
		357
		358	On error, the callback is called without arguments, otherwise it receives
		359	two array-refs with path-relative entry names.
		360
		361	Example:
		362
		363	aio_scandir $dir, 0, sub {
		364	my ($dirs, $nondirs) = @_;
		365	print "real directories: @$dirs\n";
		366	print "everything else: @$nondirs\n";
		367	};
		368
		369	Implementation notes.
		370
		371	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
		372
		373	After reading the directory, the modification time, size etc. of the
		374	directory before and after the readdir is checked, and if they match (and
		375	isn't the current time), the link count will be used to decide how many
		376	entries are directories (if >= 2). Otherwise, no knowledge of the number
		377	of subdirectories will be assumed.
		378
		379	Then entries will be sorted into likely directories (everything without
		380	a non-initial dot currently) and likely non-directories (everything
		381	else). Then every entry plus an appended C</.> will be C<stat>'ed,
		382	likely directories first. If that succeeds, it assumes that the entry
		383	is a directory or a symlink to directory (which will be checked
		384	seperately). This is often faster than stat'ing the entry itself because
		385	filesystems might detect the type of the entry without reading the inode
		386	data (e.g. ext2fs filetype feature).
		387
		388	If the known number of directories (link count - 2) has been reached, the
		389	rest of the entries is assumed to be non-directories.
		390
		391	This only works with certainty on POSIX (= UNIX) filesystems, which
		392	fortunately are the vast majority of filesystems around.
		393
		394	It will also likely work on non-POSIX filesystems with reduced efficiency
		395	as those tend to return 0 or 1 as link counts, which disables the
		396	directory counting heuristic.
		397
		398	=cut
		399
		400	sub aio_scandir($$$) {
		401	my ($path, $maxreq, $cb) = @_;
		402
		403	my $grp = aio_group;
		404
		405	$maxreq = 8 if $maxreq <= 0;
		406
		407	# stat once
		408	add $grp aio_stat $path, sub {
		409	return $cb->() if $_[0];
		410	my $now = time;
		411	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		412
		413	# read the directory entries
		414	add $grp aio_readdir $path, sub {
		415	my $entries = shift
		416	or return $cb->();
		417
		418	# stat the dir another time
		419	add $grp aio_stat $path, sub {
		420	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		421
		422	my $ndirs;
		423
		424	# take the slow route if anything looks fishy
		425	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		426	$ndirs = -1;
		427	} else {
		428	# if nlink == 2, we are finished
		429	# on non-posix-fs's, we rely on nlink < 2
		430	$ndirs = (stat _)[3] - 2
		431	or return $cb->([], $entries);
		432	}
		433
		434	# sort into likely dirs and likely nondirs
		435	# dirs == files without ".", short entries first
		436	$entries = [map $_->[0],
		437	sort { $b->[1] cmp $a->[1] }
		438	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		439	@$entries];
		440
		441	my (@dirs, @nondirs);
		442
		443	my ($statcb, $schedcb);
		444	my $nreq = 0;
		445
		446	$schedcb = sub {
		447	if (@$entries) {
		448	if ($nreq < $maxreq) {
		449	my $ent = pop @$entries;
		450	$nreq++;
		451	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
		452	}
		453	} elsif (!$nreq) {
		454	# finished
		455	undef $statcb;
		456	undef $schedcb;
		457	$cb->(\@dirs, \@nondirs) if $cb;
		458	undef $cb;
		459	}
		460	};
		461	$statcb = sub {
		462	my ($status, $entry) = @_;
		463
		464	if ($status < 0) {
		465	$nreq--;
		466	push @nondirs, $entry;
		467	&$schedcb;
		468	} else {
		469	# need to check for real directory
		470	add $grp aio_lstat "$path/$entry", sub {
		471	$nreq--;
		472
		473	if (-d _) {
		474	push @dirs, $entry;
		475
		476	if (!--$ndirs) {
		477	push @nondirs, @$entries;
		478	$entries = [];
		479	}
		480	} else {
		481	push @nondirs, $entry;
		482	}
		483
		484	&$schedcb;
		485	}
		486	}
		487	};
		488
		489	&$schedcb while @$entries && $nreq < $maxreq;
		490	};
		491	};
		492	};
		493
		494	$grp
		495	}
		496
214	=item aio_fsync $fh, $callback	497	=item aio_fsync $fh, $callback->($status)
215		498
216	Asynchronously call fsync on the given filehandle and call the callback	499	Asynchronously call fsync on the given filehandle and call the callback
217	with the fsync result code.	500	with the fsync result code.
218		501
219	=item aio_fdatasync $fh, $callback	502	=item aio_fdatasync $fh, $callback->($status)
220		503
221	Asynchronously call fdatasync on the given filehandle and call the	504	Asynchronously call fdatasync on the given filehandle and call the
222	callback with the fdatasync result code.	505	callback with the fdatasync result code.
223		506
224	If this call isn't available because your OS lacks it or it couldn't be	507	If this call isn't available because your OS lacks it or it couldn't be
225	detected, it will be emulated by calling C<fsync> instead.	508	detected, it will be emulated by calling C<fsync> instead.
		509
		510	=item aio_group $callback->()
		511
		512	[EXPERIMENTAL]
		513
		514	This is a very special aio request: Instead of doing something, it is a
		515	container for other aio requests, which is useful if you want to bundle
		516	many requests into a single, composite, request.
		517
		518	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		519	for more info.
		520
		521	Example:
		522
		523	my $grp = aio_group sub {
		524	print "all stats done\n";
		525	};
		526
		527	add $grp
		528	(aio_stat ...),
		529	(aio_stat ...),
		530	...;
		531
		532	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED
		533
		534	Mainly used for debugging and benchmarking, this aio request puts one of
		535	the request workers to sleep for the given time.
		536
		537	While it is theoretically handy to have simple I/O scheduling requests
		538	like sleep and file handle readable/writable, the overhead this creates
		539	is immense, so do not use this function except to put your application
		540	under artificial I/O pressure.
		541
		542	=back
		543
		544	=head2 IO::AIO::REQ CLASS
		545
		546	All non-aggregate C<aio_*> functions return an object of this class when
		547	called in non-void context.
		548
		549	A request always moves through the following five states in its lifetime,
		550	in order: B<ready> (request has been created, but has not been executed
		551	yet), B<execute> (request is currently being executed), B<pending>
		552	(request has been executed but callback has not been called yet),
		553	B<result> (results are being processed synchronously, includes calling the
		554	callback) and B<done> (request has reached the end of its lifetime and
		555	holds no resources anymore).
		556
		557	=over 4
		558
		559	=item $req->cancel
		560
		561	Cancels the request, if possible. Has the effect of skipping execution
		562	when entering the B<execute> state and skipping calling the callback when
		563	entering the the B<result> state, but will leave the request otherwise
		564	untouched. That means that requests that currently execute will not be
		565	stopped and resources held by the request will not be freed prematurely.
		566
		567	=back
		568
		569	=head2 IO::AIO::GRP CLASS
		570
		571	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		572	objects of this class, too.
		573
		574	A IO::AIO::GRP object is a special request that can contain multiple other
		575	aio requests.
		576
		577	You create one by calling the C<aio_group> constructing function with a
		578	callback that will be called when all contained requests have entered the
		579	C<done> state:
		580
		581	my $grp = aio_group sub {
		582	print "all requests are done\n";
		583	};
		584
		585	You add requests by calling the C<add> method with one or more
		586	C<IO::AIO::REQ> objects:
		587
		588	$grp->add (aio_unlink "...");
		589
		590	add $grp aio_stat "...", sub { ... };
		591
		592	This makes it very easy to create composite requests (see the source of
		593	C<aio_move> for an application) that work and feel like simple requests.
		594
		595	The IO::AIO::GRP objects will be cleaned up during calls to
		596	C<IO::AIO::poll_cb>, just like any other request.
		597
		598	They can be canceled like any other request. Canceling will cancel not
		599	just the request itself, but also all requests it contains.
		600
		601	They can also can also be added to other IO::AIO::GRP objects.
		602
		603	Their lifetime, simplified, looks like this: when they are empty, they
		604	will finish very quickly. If they contain only requests that are in the
		605	C<done> state, they will also finish. Otherwise they will continue to
		606	exist.
		607
		608	That means after creating a group you have some time to add requests. And
		609	in the callbacks of those requests, you can add further requests to the
		610	group. And only when all those requests have finished will the the group
		611	itself finish.
		612
		613	=over 4
		614
		615	=item $grp->add (...)
		616
		617	=item add $grp ...
		618
		619	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		620	be added, including other groups, as long as you do not create circular
		621	dependencies.
		622
		623	Returns all its arguments.
226		624
227	=back	625	=back
228		626
229	=head2 SUPPORT FUNCTIONS	627	=head2 SUPPORT FUNCTIONS
230		628
…		…
288	IO::AIO::poll_wait, IO::AIO::poll_cb	686	IO::AIO::poll_wait, IO::AIO::poll_cb
289	if IO::AIO::nreqs;	687	if IO::AIO::nreqs;
290		688
291	=item IO::AIO::min_parallel $nthreads	689	=item IO::AIO::min_parallel $nthreads
292		690
293	Set the minimum number of AIO threads to C<$nthreads>. The default is	691	Set the minimum number of AIO threads to C<$nthreads>. The current default
294	C<1>, which means a single asynchronous operation can be done at one time	692	is C<4>, which means four asynchronous operations can be done at one time
295	(the number of outstanding operations, however, is unlimited).	693	(the number of outstanding operations, however, is unlimited).
		694
		695	IO::AIO starts threads only on demand, when an AIO request is queued and
		696	no free thread exists.
296		697
297	It is recommended to keep the number of threads low, as some Linux	698	It is recommended to keep the number of threads low, as some Linux
298	kernel versions will scale negatively with the number of threads (higher	699	kernel versions will scale negatively with the number of threads (higher
299	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	700	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32
300	threads should be fine.	701	threads should be fine.
301		702
302	Under normal circumstances you don't need to call this function, as this	703	Under most circumstances you don't need to call this function, as the
303	module automatically starts some threads (the exact number might change,	704	module selects a default that is suitable for low to moderate load.
304	and is currently 4).
305		705
306	=item IO::AIO::max_parallel $nthreads	706	=item IO::AIO::max_parallel $nthreads
307		707
308	Sets the maximum number of AIO threads to C<$nthreads>. If more than	708	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
309	the specified number of threads are currently running, kill them. This	709	specified number of threads are currently running, this function kills
310	function blocks until the limit is reached.	710	them. This function blocks until the limit is reached.
		711
		712	While C<$nthreads> are zero, aio requests get queued but not executed
		713	until the number of threads has been increased again.
311		714
312	This module automatically runs C<max_parallel 0> at program end, to ensure	715	This module automatically runs C<max_parallel 0> at program end, to ensure
313	that all threads are killed and that there are no outstanding requests.	716	that all threads are killed and that there are no outstanding requests.
314		717
315	Under normal circumstances you don't need to call this function.	718	Under normal circumstances you don't need to call this function.
…		…
319	Sets the maximum number of outstanding requests to C<$nreqs>. If you	722	Sets the maximum number of outstanding requests to C<$nreqs>. If you
320	try to queue up more than this number of requests, the caller will block until	723	try to queue up more than this number of requests, the caller will block until
321	some requests have been handled.	724	some requests have been handled.
322		725
323	The default is very large, so normally there is no practical limit. If you	726	The default is very large, so normally there is no practical limit. If you
324	queue up many requests in a loop it it often improves speed if you set	727	queue up many requests in a loop it often improves speed if you set
325	this to a relatively low number, such as C<100>.	728	this to a relatively low number, such as C<100>.
326		729
327	Under normal circumstances you don't need to call this function.	730	Under normal circumstances you don't need to call this function.
328		731
329	=back	732	=back
…		…
354		757
355	1;	758	1;
356		759
357	=head2 FORK BEHAVIOUR	760	=head2 FORK BEHAVIOUR
358		761
		762	This module should do "the right thing" when the process using it forks:
		763
359	Before the fork IO::AIO enters a quiescent state where no requests can be	764	Before the fork, IO::AIO enters a quiescent state where no requests
360	added in other threads and no results will be processed. After the fork	765	can be added in other threads and no results will be processed. After
361	the parent simply leaves the quiescent state and continues request/result	766	the fork the parent simply leaves the quiescent state and continues
362	processing, while the child clears the request/result queue and starts the	767	request/result processing, while the child clears the request/result
363	same number of threads as were in use by the parent.	768	queue (so the requests started before the fork will only be handled in
		769	the parent). Threads will be started on demand until the limit ste in the
		770	parent process has been reached again.
		771
		772	In short: the parent will, after a short pause, continue as if fork had
		773	not been called, while the child will act as if IO::AIO has not been used
		774	yet.
364		775
365	=head1 SEE ALSO	776	=head1 SEE ALSO
366		777
367	L<Coro>, L<Linux::AIO>.	778	L<Coro>, L<Linux::AIO> (obsolete).
368		779
369	=head1 AUTHOR	780	=head1 AUTHOR
370		781
371	Marc Lehmann <schmorp@schmorp.de>	782	Marc Lehmann <schmorp@schmorp.de>
372	http://home.schmorp.de/	783	http://home.schmorp.de/

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Revision 1.57 by root, Sun Oct 22 01:28:31 2006 UTC