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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs.
Revision 1.87 by root, Sun Oct 29 00:52:02 2006 UTC

…		…
51	=head1 DESCRIPTION	51	=head1 DESCRIPTION
52		52
53	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
54	operating system supports.	54	operating system supports.
55		55
		56	Asynchronous means that operations that can normally block your program
		57	(e.g. reading from disk) will be done asynchronously: the operation
		58	will still block, but you can do something else in the meantime. This
		59	is extremely useful for programs that need to stay interactive even
		60	when doing heavy I/O (GUI programs, high performance network servers
		61	etc.), but can also be used to easily do operations in parallel that are
		62	normally done sequentially, e.g. stat'ing many files, which is much faster
		63	on a RAID volume or over NFS when you do a number of stat operations
		64	concurrently.
		65
		66	While this works on all types of file descriptors (for example sockets),
		67	using these functions on file descriptors that support nonblocking
		68	operation (again, sockets, pipes etc.) is very inefficient. Use an event
		69	loop for that (such as the L<Event\|Event> module): IO::AIO will naturally
		70	fit into such an event loop itself.
		71
56	Currently, a number of threads are started that execute your read/writes	72	In this version, a number of threads are started that execute your
57	and signal their completion. You don't need thread support in perl, and	73	requests and signal their completion. You don't need thread support
58	the threads created by this module will not be visible to perl. In the	74	in perl, and the threads created by this module will not be visible
59	future, this module might make use of the native aio functions available	75	to perl. In the future, this module might make use of the native aio
60	on many operating systems. However, they are often not well-supported	76	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	77	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	and they would only support aio_read and aio_write, so the remaining	78	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	79	aio_write, so the remaining functionality would have to be implemented
		80	using threads anyway.
64		81
65	Although the module will work with in the presence of other threads,	82	Although the module will work with in the presence of other (Perl-)
66	it is currently not reentrant in any way, so use appropriate locking	83	threads, it is currently not reentrant in any way, so use appropriate
67	yourself, always call C<poll_cb> from within the same thread, or never	84	locking yourself, always call C<poll_cb> from within the same thread, or
68	call C<poll_cb> (or other C<aio_> functions) recursively.	85	never call C<poll_cb> (or other C<aio_> functions) recursively.
		86
		87	=head2 EXAMPLE
		88
		89	This is a simple example that uses the Event module and loads
		90	F</etc/passwd> asynchronously:
		91
		92	use Fcntl;
		93	use Event;
		94	use IO::AIO;
		95
		96	# register the IO::AIO callback with Event
		97	Event->io (fd => IO::AIO::poll_fileno,
		98	poll => 'r',
		99	cb => \&IO::AIO::poll_cb);
		100
		101	# queue the request to open /etc/passwd
		102	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		103	my $fh = $_[0]
		104	or die "error while opening: $!";
		105
		106	# stat'ing filehandles is generally non-blocking
		107	my $size = -s $fh;
		108
		109	# queue a request to read the file
		110	my $contents;
		111	aio_read $fh, 0, $size, $contents, 0, sub {
		112	$_[0] == $size
		113	or die "short read: $!";
		114
		115	close $fh;
		116
		117	# file contents now in $contents
		118	print $contents;
		119
		120	# exit event loop and program
		121	Event::unloop;
		122	};
		123	};
		124
		125	# possibly queue up other requests, or open GUI windows,
		126	# check for sockets etc. etc.
		127
		128	# process events as long as there are some:
		129	Event::loop;
		130
		131	=head1 REQUEST ANATOMY AND LIFETIME
		132
		133	Every C<aio_*> function creates a request. which is a C data structure not
		134	directly visible to Perl.
		135
		136	If called in non-void context, every request function returns a Perl
		137	object representing the request. In void context, nothing is returned,
		138	which saves a bit of memory.
		139
		140	The perl object is a fairly standard ref-to-hash object. The hash contents
		141	are not used by IO::AIO so you are free to store anything you like in it.
		142
		143	During their existance, aio requests travel through the following states,
		144	in order:
		145
		146	=over 4
		147
		148	=item ready
		149
		150	Immediately after a request is created it is put into the ready state,
		151	waiting for a thread to execute it.
		152
		153	=item execute
		154
		155	A thread has accepted the request for processing and is currently
		156	executing it (e.g. blocking in read).
		157
		158	=item pending
		159
		160	The request has been executed and is waiting for result processing.
		161
		162	While request submission and execution is fully asynchronous, result
		163	processing is not and relies on the perl interpreter calling C<poll_cb>
		164	(or another function with the same effect).
		165
		166	=item result
		167
		168	The request results are processed synchronously by C<poll_cb>.
		169
		170	The C<poll_cb> function will process all outstanding aio requests by
		171	calling their callbacks, freeing memory associated with them and managing
		172	any groups they are contained in.
		173
		174	=item done
		175
		176	Request has reached the end of its lifetime and holds no resources anymore
		177	(except possibly for the Perl object, but its connection to the actual
		178	aio request is severed and calling its methods will either do nothing or
		179	result in a runtime error).
69		180
70	=cut	181	=cut
71		182
72	package IO::AIO;	183	package IO::AIO;
73		184
…		…
75	use strict 'vars';	186	use strict 'vars';
76		187
77	use base 'Exporter';	188	use base 'Exporter';
78		189
79	BEGIN {	190	BEGIN {
80	our $VERSION = '2.0';	191	our $VERSION = '2.1';
81		192
82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	193	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
83	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	194	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	195	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
85	aio_group aio_nop);	196	aio_copy aio_group aio_nop aio_mknod);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	197	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	198	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	199	min_parallel max_parallel max_idle
		200	nreqs nready npending nthreads
		201	max_poll_time max_poll_reqs);
89		202
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	203	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		204
92	require XSLoader;	205	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	206	XSLoader::load ("IO::AIO", $VERSION);
94	}	207	}
95		208
96	=head1 FUNCTIONS	209	=head1 FUNCTIONS
97		210
98	=head2 AIO FUNCTIONS	211	=head2 AIO REQUEST FUNCTIONS
99		212
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	213	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	214	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	215	and they all accept an additional (and optional) C<$callback> argument
103	which must be a code reference. This code reference will get called with	216	which must be a code reference. This code reference will get called with
…		…
106	syscall has been executed asynchronously.	219	syscall has been executed asynchronously.
107		220
108	All functions expecting a filehandle keep a copy of the filehandle	221	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	222	internally until the request has finished.
110		223
111	All requests return objects of type L<IO::AIO::REQ> that allow further	224	All functions return request objects of type L<IO::AIO::REQ> that allow
112	manipulation of those requests while they are in-flight.	225	further manipulation of those requests while they are in-flight.
113		226
114	The pathnames you pass to these routines I<must> be absolute and	227	The pathnames you pass to these routines I<must> be absolute and
115	encoded in byte form. The reason for the former is that at the time the	228	encoded as octets. The reason for the former is that at the time the
116	request is being executed, the current working directory could have	229	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	230	changed. Alternatively, you can make sure that you never change the
118	current working directory.	231	current working directory anywhere in the program and then use relative
		232	paths.
119		233
120	To encode pathnames to byte form, either make sure you either: a)	234	To encode pathnames as octets, either make sure you either: a) always pass
121	always pass in filenames you got from outside (command line, readdir	235	in filenames you got from outside (command line, readdir etc.) without
122	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	236	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
123	your pathnames to the locale (or other) encoding in effect in the user	237	your pathnames to the locale (or other) encoding in effect in the user
124	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	238	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	239	use something else to ensure your scalar has the correct contents.
		240
		241	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		242	handles correctly wether it is set or not.
126		243
127	=over 4	244	=over 4
128		245
129	=item aioreq_pri $pri	246	=item $prev_pri = aioreq_pri [$pri]
130		247
131	Sets the priority for the next aio request. The default priority	248	Returns the priority value that would be used for the next request and, if
		249	C<$pri> is given, sets the priority for the next aio request.
		250
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	251	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	252	and C<4>, respectively. Requests with higher priority will be serviced
		253	first.
134		254
135	The priority will be reset to C<0> after each call to one of the C<aio_>	255	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	256	functions.
137		257
138	Example: open a file with low priority, then read something from it with	258	Example: open a file with low priority, then read something from it with
139	higher priority so the read request is serviced before other low priority	259	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	260	open requests (potentially spamming the cache):
…		…
150	};	270	};
151		271
152	=item aioreq_nice $pri_adjust	272	=item aioreq_nice $pri_adjust
153		273
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	274	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	275	priority, so the effect is cumulative.
156		276
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	277	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		278
159	Asynchronously open or create a file and call the callback with a newly	279	Asynchronously open or create a file and call the callback with a newly
160	created filehandle for the file.	280	created filehandle for the file.
…		…
210		330
211	aio_read $fh, 7, 15, $buffer, 0, sub {	331	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	332	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	333	print "read $_[0] bytes: <$buffer>\n";
214	};	334	};
215
216	=item aio_move $srcpath, $dstpath, $callback->($status)
217
218	Try to move the I<file> (directories not supported as either source or
219	destination) from C<$srcpath> to C<$dstpath> and call the callback with
220	the C<0> (error) or C<-1> ok.
221
222	This is a composite request that tries to rename(2) the file first. If
223	rename files with C<EXDEV>, it creates the destination file with mode 0200
224	and copies the contents of the source file into it using C<aio_sendfile>,
225	followed by restoring atime, mtime, access mode and uid/gid, in that
226	order, and unlinking the C<$srcpath>.
227
228	If an error occurs, the partial destination file will be unlinked, if
229	possible, except when setting atime, mtime, access mode and uid/gid, where
230	errors are being ignored.
231
232	=cut
233
234	sub aio_move($$$) {
235	my ($src, $dst, $cb) = @_;
236
237	my $grp = aio_group $cb;
238
239	add $grp aio_rename $src, $dst, sub {
240	if ($_[0] && $! == EXDEV) {
241	add $grp aio_open $src, O_RDONLY, 0, sub {
242	if (my $src_fh = $_[0]) {
243	my @stat = stat $src_fh;
244
245	add $grp aio_open $dst, O_WRONLY, 0200, sub {
246	if (my $dst_fh = $_[0]) {
247	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
248	close $src_fh;
249
250	if ($_[0] == $stat[7]) {
251	utime $stat[8], $stat[9], $dst;
252	chmod $stat[2] & 07777, $dst_fh;
253	chown $stat[4], $stat[5], $dst_fh;
254	close $dst_fh;
255
256	add $grp aio_unlink $src, sub {
257	$grp->result ($_[0]);
258	};
259	} else {
260	my $errno = $!;
261	add $grp aio_unlink $dst, sub {
262	$! = $errno;
263	$grp->result (-1);
264	};
265	}
266	};
267	} else {
268	$grp->result (-1);
269	}
270	},
271
272	} else {
273	$grp->result (-1);
274	}
275	};
276	} else {
277	$grp->result ($_[0]);
278	}
279	};
280
281	$grp
282	}
283		335
284	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	336	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
285		337
286	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	338	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
287	reading at byte offset C<$in_offset>, and starts writing at the current	339	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
343	=item aio_unlink $pathname, $callback->($status)	395	=item aio_unlink $pathname, $callback->($status)
344		396
345	Asynchronously unlink (delete) a file and call the callback with the	397	Asynchronously unlink (delete) a file and call the callback with the
346	result code.	398	result code.
347		399
		400	=item aio_mknod $path, $mode, $dev, $callback->($status)
		401
		402	[EXPERIMENTAL]
		403
		404	Asynchronously create a device node (or fifo). See mknod(2).
		405
		406	The only (POSIX-) portable way of calling this function is:
		407
		408	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		409
348	=item aio_link $srcpath, $dstpath, $callback->($status)	410	=item aio_link $srcpath, $dstpath, $callback->($status)
349		411
350	Asynchronously create a new link to the existing object at C<$srcpath> at	412	Asynchronously create a new link to the existing object at C<$srcpath> at
351	the path C<$dstpath> and call the callback with the result code.	413	the path C<$dstpath> and call the callback with the result code.
352		414
…		…
372	sorted, and will B<NOT> include the C<.> and C<..> entries.	434	sorted, and will B<NOT> include the C<.> and C<..> entries.
373		435
374	The callback a single argument which is either C<undef> or an array-ref	436	The callback a single argument which is either C<undef> or an array-ref
375	with the filenames.	437	with the filenames.
376		438
		439	=item aio_copy $srcpath, $dstpath, $callback->($status)
		440
		441	Try to copy the I<file> (directories not supported as either source or
		442	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		443	the C<0> (error) or C<-1> ok.
		444
		445	This is a composite request that it creates the destination file with
		446	mode 0200 and copies the contents of the source file into it using
		447	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		448	uid/gid, in that order.
		449
		450	If an error occurs, the partial destination file will be unlinked, if
		451	possible, except when setting atime, mtime, access mode and uid/gid, where
		452	errors are being ignored.
		453
		454	=cut
		455
		456	sub aio_copy($$;$) {
		457	my ($src, $dst, $cb) = @_;
		458
		459	my $pri = aioreq_pri;
		460	my $grp = aio_group $cb;
		461
		462	aioreq_pri $pri;
		463	add $grp aio_open $src, O_RDONLY, 0, sub {
		464	if (my $src_fh = $_[0]) {
		465	my @stat = stat $src_fh;
		466
		467	aioreq_pri $pri;
		468	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		469	if (my $dst_fh = $_[0]) {
		470	aioreq_pri $pri;
		471	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		472	if ($_[0] == $stat[7]) {
		473	$grp->result (0);
		474	close $src_fh;
		475
		476	# those should not normally block. should. should.
		477	utime $stat[8], $stat[9], $dst;
		478	chmod $stat[2] & 07777, $dst_fh;
		479	chown $stat[4], $stat[5], $dst_fh;
		480	close $dst_fh;
		481	} else {
		482	$grp->result (-1);
		483	close $src_fh;
		484	close $dst_fh;
		485
		486	aioreq $pri;
		487	add $grp aio_unlink $dst;
		488	}
		489	};
		490	} else {
		491	$grp->result (-1);
		492	}
		493	},
		494
		495	} else {
		496	$grp->result (-1);
		497	}
		498	};
		499
		500	$grp
		501	}
		502
		503	=item aio_move $srcpath, $dstpath, $callback->($status)
		504
		505	Try to move the I<file> (directories not supported as either source or
		506	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		507	the C<0> (error) or C<-1> ok.
		508
		509	This is a composite request that tries to rename(2) the file first. If
		510	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		511	that is successful, unlinking the C<$srcpath>.
		512
		513	=cut
		514
		515	sub aio_move($$;$) {
		516	my ($src, $dst, $cb) = @_;
		517
		518	my $pri = aioreq_pri;
		519	my $grp = aio_group $cb;
		520
		521	aioreq_pri $pri;
		522	add $grp aio_rename $src, $dst, sub {
		523	if ($_[0] && $! == EXDEV) {
		524	aioreq_pri $pri;
		525	add $grp aio_copy $src, $dst, sub {
		526	$grp->result ($_[0]);
		527
		528	if (!$_[0]) {
		529	aioreq_pri $pri;
		530	add $grp aio_unlink $src;
		531	}
		532	};
		533	} else {
		534	$grp->result ($_[0]);
		535	}
		536	};
		537
		538	$grp
		539	}
		540
377	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	541	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
378		542
379	Scans a directory (similar to C<aio_readdir>) but additionally tries to	543	Scans a directory (similar to C<aio_readdir>) but additionally tries to
380	separate the entries of directory C<$path> into two sets of names, ones	544	efficiently separate the entries of directory C<$path> into two sets of
381	you can recurse into (directories or links to them), and ones you cannot	545	names, directories you can recurse into (directories), and ones you cannot
382	recurse into (everything else).	546	recurse into (everything else, including symlinks to directories).
383		547
384	C<aio_scandir> is a composite request that creates of many sub requests_	548	C<aio_scandir> is a composite request that creates of many sub requests_
385	C<$maxreq> specifies the maximum number of outstanding aio requests that	549	C<$maxreq> specifies the maximum number of outstanding aio requests that
386	this function generates. If it is C<< <= 0 >>, then a suitable default	550	this function generates. If it is C<< <= 0 >>, then a suitable default
387	will be chosen (currently 6).	551	will be chosen (currently 4).
388		552
389	On error, the callback is called without arguments, otherwise it receives	553	On error, the callback is called without arguments, otherwise it receives
390	two array-refs with path-relative entry names.	554	two array-refs with path-relative entry names.
391		555
392	Example:	556	Example:
…		…
429	=cut	593	=cut
430		594
431	sub aio_scandir($$$) {	595	sub aio_scandir($$$) {
432	my ($path, $maxreq, $cb) = @_;	596	my ($path, $maxreq, $cb) = @_;
433		597
		598	my $pri = aioreq_pri;
		599
434	my $grp = aio_group $cb;	600	my $grp = aio_group $cb;
435		601
436	$maxreq = 6 if $maxreq <= 0;	602	$maxreq = 4 if $maxreq <= 0;
437		603
438	# stat once	604	# stat once
		605	aioreq_pri $pri;
439	add $grp aio_stat $path, sub {	606	add $grp aio_stat $path, sub {
440	return $grp->result () if $_[0];	607	return $grp->result () if $_[0];
441	my $now = time;	608	my $now = time;
442	my $hash1 = join ":", (stat _)[0,1,3,7,9];	609	my $hash1 = join ":", (stat _)[0,1,3,7,9];
443		610
444	# read the directory entries	611	# read the directory entries
		612	aioreq_pri $pri;
445	add $grp aio_readdir $path, sub {	613	add $grp aio_readdir $path, sub {
446	my $entries = shift	614	my $entries = shift
447	or return $grp->result ();	615	or return $grp->result ();
448		616
449	# stat the dir another time	617	# stat the dir another time
		618	aioreq_pri $pri;
450	add $grp aio_stat $path, sub {	619	add $grp aio_stat $path, sub {
451	my $hash2 = join ":", (stat _)[0,1,3,7,9];	620	my $hash2 = join ":", (stat _)[0,1,3,7,9];
452		621
453	my $ndirs;	622	my $ndirs;
454		623
…		…
469	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	638	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
470	@$entries];	639	@$entries];
471		640
472	my (@dirs, @nondirs);	641	my (@dirs, @nondirs);
473		642
474	my ($statcb, $schedcb);
475	my $nreq = 0;
476
477	my $statgrp = add $grp aio_group;	643	my $statgrp = add $grp aio_group sub {
		644	$grp->result (\@dirs, \@nondirs);
		645	};
478		646
479	$schedcb = sub {	647	limit $statgrp $maxreq;
480	if (@$entries) {	648	feed $statgrp sub {
481	if ($nreq < $maxreq) {	649	return unless @$entries;
482	my $ent = pop @$entries;	650	my $entry = pop @$entries;
		651
		652	aioreq_pri $pri;
		653	add $statgrp aio_stat "$path/$entry/.", sub {
		654	if ($_[0] < 0) {
		655	push @nondirs, $entry;
		656	} else {
		657	# need to check for real directory
		658	aioreq_pri $pri;
		659	add $statgrp aio_lstat "$path/$entry", sub {
		660	if (-d _) {
		661	push @dirs, $entry;
		662
		663	unless (--$ndirs) {
		664	push @nondirs, @$entries;
		665	feed $statgrp;
		666	}
		667	} else {
		668	push @nondirs, $entry;
		669	}
483	$nreq++;	670	}
484	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
485	}	671	}
486	} elsif (!$nreq) {
487	# finished
488	$statgrp->cancel;
489	undef $statcb;
490	undef $schedcb;
491	$grp->result (\@dirs, \@nondirs);
492	}	672	};
493	};	673	};
494	$statcb = sub {
495	my ($status, $entry) = @_;
496
497	if ($status < 0) {
498	$nreq--;
499	push @nondirs, $entry;
500	&$schedcb;
501	} else {
502	# need to check for real directory
503	add $grp aio_lstat "$path/$entry", sub {
504	$nreq--;
505
506	if (-d _) {
507	push @dirs, $entry;
508
509	if (!--$ndirs) {
510	push @nondirs, @$entries;
511	$entries = [];
512	}
513	} else {
514	push @nondirs, $entry;
515	}
516
517	&$schedcb;
518	}
519	}
520	};
521
522	&$schedcb while @$entries && $nreq < $maxreq;
523	};	674	};
524	};	675	};
525	};	676	};
526		677
527	$grp	678	$grp
…		…
539		690
540	If this call isn't available because your OS lacks it or it couldn't be	691	If this call isn't available because your OS lacks it or it couldn't be
541	detected, it will be emulated by calling C<fsync> instead.	692	detected, it will be emulated by calling C<fsync> instead.
542		693
543	=item aio_group $callback->(...)	694	=item aio_group $callback->(...)
544
545	[EXPERIMENTAL]
546		695
547	This is a very special aio request: Instead of doing something, it is a	696	This is a very special aio request: Instead of doing something, it is a
548	container for other aio requests, which is useful if you want to bundle	697	container for other aio requests, which is useful if you want to bundle
549	many requests into a single, composite, request with a definite callback	698	many requests into a single, composite, request with a definite callback
550	and the ability to cancel the whole request with its subrequests.	699	and the ability to cancel the whole request with its subrequests.
…		…
591	=head2 IO::AIO::REQ CLASS	740	=head2 IO::AIO::REQ CLASS
592		741
593	All non-aggregate C<aio_*> functions return an object of this class when	742	All non-aggregate C<aio_*> functions return an object of this class when
594	called in non-void context.	743	called in non-void context.
595		744
596	A request always moves through the following five states in its lifetime,
597	in order: B<ready> (request has been created, but has not been executed
598	yet), B<execute> (request is currently being executed), B<pending>
599	(request has been executed but callback has not been called yet),
600	B<result> (results are being processed synchronously, includes calling the
601	callback) and B<done> (request has reached the end of its lifetime and
602	holds no resources anymore).
603
604	=over 4	745	=over 4
605		746
606	=item cancel $req	747	=item cancel $req
607		748
608	Cancels the request, if possible. Has the effect of skipping execution	749	Cancels the request, if possible. Has the effect of skipping execution
…		…
661	=item * They can also can also be added to other IO::AIO::GRP objects.	802	=item * They can also can also be added to other IO::AIO::GRP objects.
662		803
663	=item * You must not add requests to a group from within the group callback (or	804	=item * You must not add requests to a group from within the group callback (or
664	any later time).	805	any later time).
665		806
666	=item * This does not harmonise well with C<max_outstanding>, so best do
667	not combine C<aio_group> with it. Groups and feeders are recommended for
668	this kind of concurrency-limiting.
669
670	=back	807	=back
671		808
672	Their lifetime, simplified, looks like this: when they are empty, they	809	Their lifetime, simplified, looks like this: when they are empty, they
673	will finish very quickly. If they contain only requests that are in the	810	will finish very quickly. If they contain only requests that are in the
674	C<done> state, they will also finish. Otherwise they will continue to	811	C<done> state, they will also finish. Otherwise they will continue to
…		…
689	be added, including other groups, as long as you do not create circular	826	be added, including other groups, as long as you do not create circular
690	dependencies.	827	dependencies.
691		828
692	Returns all its arguments.	829	Returns all its arguments.
693		830
		831	=item $grp->cancel_subs
		832
		833	Cancel all subrequests and clears any feeder, but not the group request
		834	itself. Useful when you queued a lot of events but got a result early.
		835
694	=item $grp->result (...)	836	=item $grp->result (...)
695		837
696	Set the result value(s) that will be passed to the group callback when all	838	Set the result value(s) that will be passed to the group callback when all
697	subrequests have finished. By default, no argument will be passed.	839	subrequests have finished and set thre groups errno to the current value
		840	of errno (just like calling C<errno> without an error number). By default,
		841	no argument will be passed and errno is zero.
		842
		843	=item $grp->errno ([$errno])
		844
		845	Sets the group errno value to C<$errno>, or the current value of errno
		846	when the argument is missing.
		847
		848	Every aio request has an associated errno value that is restored when
		849	the callback is invoked. This method lets you change this value from its
		850	default (0).
		851
		852	Calling C<result> will also set errno, so make sure you either set C<$!>
		853	before the call to C<result>, or call c<errno> after it.
698		854
699	=item feed $grp $callback->($grp)	855	=item feed $grp $callback->($grp)
700
701	[VERY EXPERIMENTAL]
702		856
703	Sets a feeder/generator on this group: every group can have an attached	857	Sets a feeder/generator on this group: every group can have an attached
704	generator that generates requests if idle. The idea behind this is that,	858	generator that generates requests if idle. The idea behind this is that,
705	although you could just queue as many requests as you want in a group,	859	although you could just queue as many requests as you want in a group,
706	this might starve other requests for a potentially long time. For	860	this might starve other requests for a potentially long time. For
…		…
743		897
744	=back	898	=back
745		899
746	=head2 SUPPORT FUNCTIONS	900	=head2 SUPPORT FUNCTIONS
747		901
		902	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		903
748	=over 4	904	=over 4
749		905
750	=item $fileno = IO::AIO::poll_fileno	906	=item $fileno = IO::AIO::poll_fileno
751		907
752	Return the I<request result pipe file descriptor>. This filehandle must be	908	Return the I<request result pipe file descriptor>. This filehandle must be
…		…
756		912
757	See C<poll_cb> for an example.	913	See C<poll_cb> for an example.
758		914
759	=item IO::AIO::poll_cb	915	=item IO::AIO::poll_cb
760		916
761	Process all outstanding events on the result pipe. You have to call this	917	Process some outstanding events on the result pipe. You have to call this
762	regularly. Returns the number of events processed. Returns immediately	918	regularly. Returns the number of events processed. Returns immediately
763	when no events are outstanding.	919	when no events are outstanding. The amount of events processed depends on
		920	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		921
		922	If not all requests were processed for whatever reason, the filehandle
		923	will still be ready when C<poll_cb> returns.
764		924
765	Example: Install an Event watcher that automatically calls	925	Example: Install an Event watcher that automatically calls
766	IO::AIO::poll_cb with high priority:	926	IO::AIO::poll_cb with high priority:
767		927
768	Event->io (fd => IO::AIO::poll_fileno,	928	Event->io (fd => IO::AIO::poll_fileno,
769	poll => 'r', async => 1,	929	poll => 'r', async => 1,
770	cb => \&IO::AIO::poll_cb);	930	cb => \&IO::AIO::poll_cb);
771		931
		932	=item IO::AIO::max_poll_reqs $nreqs
		933
		934	=item IO::AIO::max_poll_time $seconds
		935
		936	These set the maximum number of requests (default C<0>, meaning infinity)
		937	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		938	the maximum amount of time (default C<0>, meaning infinity) spent in
		939	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		940	of time C<poll_cb> is allowed to use).
		941
		942	Setting these is useful if you want to ensure some level of
		943	interactiveness when perl is not fast enough to process all requests in
		944	time.
		945
		946	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		947
		948	Example: Install an Event watcher that automatically calls
		949	IO::AIO::poll_some with low priority, to ensure that other parts of the
		950	program get the CPU sometimes even under high AIO load.
		951
		952	# try not to spend much more than 0.1s in poll_cb
		953	IO::AIO::max_poll_time 0.1;
		954
		955	# use a low priority so other tasks have priority
		956	Event->io (fd => IO::AIO::poll_fileno,
		957	poll => 'r', nice => 1,
		958	cb => &IO::AIO::poll_cb);
		959
772	=item IO::AIO::poll_wait	960	=item IO::AIO::poll_wait
773		961
774	Wait till the result filehandle becomes ready for reading (simply does a	962	Wait till the result filehandle becomes ready for reading (simply does a
775	C<select> on the filehandle. This is useful if you want to synchronously wait	963	C<select> on the filehandle. This is useful if you want to synchronously
776	for some requests to finish).	964	wait for some requests to finish).
777		965
778	See C<nreqs> for an example.	966	See C<nreqs> for an example.
779		967
		968	=item IO::AIO::poll
		969
		970	Waits until some requests have been handled.
		971
		972	Strictly equivalent to:
		973
		974	IO::AIO::poll_wait, IO::AIO::poll_cb
		975	if IO::AIO::nreqs;
		976
780	=item IO::AIO::nreqs	977	=item IO::AIO::flush
781		978
782	Returns the number of requests currently outstanding (i.e. for which their	979	Wait till all outstanding AIO requests have been handled.
783	callback has not been invoked yet).
784		980
785	Example: wait till there are no outstanding requests anymore:	981	Strictly equivalent to:
786		982
787	IO::AIO::poll_wait, IO::AIO::poll_cb	983	IO::AIO::poll_wait, IO::AIO::poll_cb
788	while IO::AIO::nreqs;	984	while IO::AIO::nreqs;
789		985
790	=item IO::AIO::flush	986	=head3 CONTROLLING THE NUMBER OF THREADS
791
792	Wait till all outstanding AIO requests have been handled.
793
794	Strictly equivalent to:
795
796	IO::AIO::poll_wait, IO::AIO::poll_cb
797	while IO::AIO::nreqs;
798
799	=item IO::AIO::poll
800
801	Waits until some requests have been handled.
802
803	Strictly equivalent to:
804
805	IO::AIO::poll_wait, IO::AIO::poll_cb
806	if IO::AIO::nreqs;
807		987
808	=item IO::AIO::min_parallel $nthreads	988	=item IO::AIO::min_parallel $nthreads
809		989
810	Set the minimum number of AIO threads to C<$nthreads>. The current	990	Set the minimum number of AIO threads to C<$nthreads>. The current
811	default is C<8>, which means eight asynchronous operations can execute	991	default is C<8>, which means eight asynchronous operations can execute
812	concurrently at any one time (the number of outstanding requests,	992	concurrently at any one time (the number of outstanding requests,
813	however, is unlimited).	993	however, is unlimited).
814		994
815	IO::AIO starts threads only on demand, when an AIO request is queued and	995	IO::AIO starts threads only on demand, when an AIO request is queued and
816	no free thread exists.	996	no free thread exists. Please note that queueing up a hundred requests can
		997	create demand for a hundred threads, even if it turns out that everything
		998	is in the cache and could have been processed faster by a single thread.
817		999
818	It is recommended to keep the number of threads relatively low, as some	1000	It is recommended to keep the number of threads relatively low, as some
819	Linux kernel versions will scale negatively with the number of threads	1001	Linux kernel versions will scale negatively with the number of threads
820	(higher parallelity => MUCH higher latency). With current Linux 2.6	1002	(higher parallelity => MUCH higher latency). With current Linux 2.6
821	versions, 4-32 threads should be fine.	1003	versions, 4-32 threads should be fine.
…		…
835	This module automatically runs C<max_parallel 0> at program end, to ensure	1017	This module automatically runs C<max_parallel 0> at program end, to ensure
836	that all threads are killed and that there are no outstanding requests.	1018	that all threads are killed and that there are no outstanding requests.
837		1019
838	Under normal circumstances you don't need to call this function.	1020	Under normal circumstances you don't need to call this function.
839		1021
		1022	=item IO::AIO::max_idle $nthreads
		1023
		1024	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1025	threads that did not get a request to process within 10 seconds). That
		1026	means if a thread becomes idle while C<$nthreads> other threads are also
		1027	idle, it will free its resources and exit.
		1028
		1029	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1030	to allow for extremely high load situations, but want to free resources
		1031	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1032
		1033	The default is probably ok in most situations, especially if thread
		1034	creation is fast. If thread creation is very slow on your system you might
		1035	want to use larger values.
		1036
840	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1037	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
841		1038
842	[DEPRECATED]	1039	This is a very bad function to use in interactive programs because it
		1040	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1041	use an C<aio_group> together with a feed callback.
843		1042
844	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1043	Sets the maximum number of outstanding requests to C<$nreqs>. If you
845	try to queue up more than this number of requests, the caller will block until	1044	to queue up more than this number of requests, the next call to the
846	some requests have been handled.	1045	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1046	function will block until the limit is no longer exceeded.
847		1047
848	The default is very large, so normally there is no practical limit. If you	1048	The default value is very large, so there is no practical limit on the
849	queue up many requests in a loop it often improves speed if you set	1049	number of outstanding requests.
850	this to a relatively low number, such as C<100>.
851		1050
852	This function does not work well together with C<aio_group>'s, and their	1051	You can still queue as many requests as you want. Therefore,
853	feeder interface is better suited to limiting concurrency, so do not use	1052	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
854	this function.	1053	as a stop gap to shield against fatal memory overflow (with large values).
855		1054
856	Under normal circumstances you don't need to call this function.	1055	=head3 STATISTICAL INFORMATION
		1056
		1057	=item IO::AIO::nreqs
		1058
		1059	Returns the number of requests currently in the ready, execute or pending
		1060	states (i.e. for which their callback has not been invoked yet).
		1061
		1062	Example: wait till there are no outstanding requests anymore:
		1063
		1064	IO::AIO::poll_wait, IO::AIO::poll_cb
		1065	while IO::AIO::nreqs;
		1066
		1067	=item IO::AIO::nready
		1068
		1069	Returns the number of requests currently in the ready state (not yet
		1070	executed).
		1071
		1072	=item IO::AIO::npending
		1073
		1074	Returns the number of requests currently in the pending state (executed,
		1075	but not yet processed by poll_cb).
857		1076
858	=back	1077	=back
859		1078
860	=cut	1079	=cut
861		1080
…		…
876	}	1095	}
877		1096
878	min_parallel 8;	1097	min_parallel 8;
879		1098
880	END {	1099	END {
881	max_parallel 0;	1100	min_parallel 1;
882	}	1101	flush;
		1102	};
883		1103
884	1;	1104	1;
885		1105
886	=head2 FORK BEHAVIOUR	1106	=head2 FORK BEHAVIOUR
887		1107
888	This module should do "the right thing" when the process using it forks:	1108	This module should do "the right thing" when the process using it forks:
889		1109
890	Before the fork, IO::AIO enters a quiescent state where no requests	1110	Before the fork, IO::AIO enters a quiescent state where no requests
891	can be added in other threads and no results will be processed. After	1111	can be added in other threads and no results will be processed. After
892	the fork the parent simply leaves the quiescent state and continues	1112	the fork the parent simply leaves the quiescent state and continues
893	request/result processing, while the child clears the request/result	1113	request/result processing, while the child frees the request/result queue
894	queue (so the requests started before the fork will only be handled in	1114	(so that the requests started before the fork will only be handled in the
895	the parent). Threads will be started on demand until the limit ste in the	1115	parent). Threads will be started on demand until the limit set in the
896	parent process has been reached again.	1116	parent process has been reached again.
897		1117
898	In short: the parent will, after a short pause, continue as if fork had	1118	In short: the parent will, after a short pause, continue as if fork had
899	not been called, while the child will act as if IO::AIO has not been used	1119	not been called, while the child will act as if IO::AIO has not been used
900	yet.	1120	yet.
901		1121
902	=head2 MEMORY USAGE	1122	=head2 MEMORY USAGE
903		1123
		1124	Per-request usage:
		1125
904	Each aio request uses - depending on your architecture - around 128 bytes	1126	Each aio request uses - depending on your architecture - around 100-200
905	of memory. In addition, stat requests need a stat buffer (possibly a few	1127	bytes of memory. In addition, stat requests need a stat buffer (possibly
906	hundred bytes). Perl scalars and other data passed into aio requests will	1128	a few hundred bytes), readdir requires a result buffer and so on. Perl
907	also be locked.	1129	scalars and other data passed into aio requests will also be locked and
		1130	will consume memory till the request has entered the done state.
908		1131
909	This is now awfully much, so queuing lots of requests is not usually a	1132	This is now awfully much, so queuing lots of requests is not usually a
910	problem.	1133	problem.
911		1134
912	Each thread needs a stack area which is usually around 16k, sometimes much	1135	Per-thread usage:
913	larger, depending on the OS.	1136
		1137	In the execution phase, some aio requests require more memory for
		1138	temporary buffers, and each thread requires a stack and other data
		1139	structures (usually around 16k-128k, depending on the OS).
		1140
		1141	=head1 KNOWN BUGS
		1142
		1143	Known bugs will be fixed in the next release.
914		1144
915	=head1 SEE ALSO	1145	=head1 SEE ALSO
916		1146
917	L<Coro::AIO>.	1147	L<Coro::AIO>.
918		1148

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs. Revision 1.87 by root, Sun Oct 29 00:52:02 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs.
Revision 1.87 by root, Sun Oct 29 00:52:02 2006 UTC