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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.94 by root, Wed Nov 8 02:01:02 2006 UTC

…		…
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", O_RDONLY, 0, sub {
10	my ($fh) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
51	=head1 DESCRIPTION	52	=head1 DESCRIPTION
52		53
53	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
54	operating system supports.	55	operating system supports.
55		56
		57	Asynchronous means that operations that can normally block your program
		58	(e.g. reading from disk) will be done asynchronously: the operation
		59	will still block, but you can do something else in the meantime. This
		60	is extremely useful for programs that need to stay interactive even
		61	when doing heavy I/O (GUI programs, high performance network servers
		62	etc.), but can also be used to easily do operations in parallel that are
		63	normally done sequentially, e.g. stat'ing many files, which is much faster
		64	on a RAID volume or over NFS when you do a number of stat operations
		65	concurrently.
		66
		67	While most of this works on all types of file descriptors (for example
		68	sockets), using these functions on file descriptors that support
		69	nonblocking operation (again, sockets, pipes etc.) is very inefficient or
		70	might not work (aio_read fails on sockets/pipes/fifos). Use an event loop
		71	for that (such as the L<Event\|Event> module): IO::AIO will naturally fit
		72	into such an event loop itself.
		73
56	Currently, a number of threads are started that execute your read/writes	74	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	75	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	76	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	77	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	78	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	79	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	80	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	81	aio_write, so the remaining functionality would have to be implemented
		82	using threads anyway.
64		83
65	Although the module will work with in the presence of other threads,	84	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	85	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	86	locking yourself, always call C<poll_cb> from within the same thread, or
68	call C<poll_cb> (or other C<aio_> functions) recursively.	87	never call C<poll_cb> (or other C<aio_> functions) recursively.
		88
		89	=head2 EXAMPLE
		90
		91	This is a simple example that uses the Event module and loads
		92	F</etc/passwd> asynchronously:
		93
		94	use Fcntl;
		95	use Event;
		96	use IO::AIO;
		97
		98	# register the IO::AIO callback with Event
		99	Event->io (fd => IO::AIO::poll_fileno,
		100	poll => 'r',
		101	cb => \&IO::AIO::poll_cb);
		102
		103	# queue the request to open /etc/passwd
		104	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		105	my $fh = shift
		106	or die "error while opening: $!";
		107
		108	# stat'ing filehandles is generally non-blocking
		109	my $size = -s $fh;
		110
		111	# queue a request to read the file
		112	my $contents;
		113	aio_read $fh, 0, $size, $contents, 0, sub {
		114	$_[0] == $size
		115	or die "short read: $!";
		116
		117	close $fh;
		118
		119	# file contents now in $contents
		120	print $contents;
		121
		122	# exit event loop and program
		123	Event::unloop;
		124	};
		125	};
		126
		127	# possibly queue up other requests, or open GUI windows,
		128	# check for sockets etc. etc.
		129
		130	# process events as long as there are some:
		131	Event::loop;
		132
		133	=head1 REQUEST ANATOMY AND LIFETIME
		134
		135	Every C<aio_*> function creates a request. which is a C data structure not
		136	directly visible to Perl.
		137
		138	If called in non-void context, every request function returns a Perl
		139	object representing the request. In void context, nothing is returned,
		140	which saves a bit of memory.
		141
		142	The perl object is a fairly standard ref-to-hash object. The hash contents
		143	are not used by IO::AIO so you are free to store anything you like in it.
		144
		145	During their existance, aio requests travel through the following states,
		146	in order:
		147
		148	=over 4
		149
		150	=item ready
		151
		152	Immediately after a request is created it is put into the ready state,
		153	waiting for a thread to execute it.
		154
		155	=item execute
		156
		157	A thread has accepted the request for processing and is currently
		158	executing it (e.g. blocking in read).
		159
		160	=item pending
		161
		162	The request has been executed and is waiting for result processing.
		163
		164	While request submission and execution is fully asynchronous, result
		165	processing is not and relies on the perl interpreter calling C<poll_cb>
		166	(or another function with the same effect).
		167
		168	=item result
		169
		170	The request results are processed synchronously by C<poll_cb>.
		171
		172	The C<poll_cb> function will process all outstanding aio requests by
		173	calling their callbacks, freeing memory associated with them and managing
		174	any groups they are contained in.
		175
		176	=item done
		177
		178	Request has reached the end of its lifetime and holds no resources anymore
		179	(except possibly for the Perl object, but its connection to the actual
		180	aio request is severed and calling its methods will either do nothing or
		181	result in a runtime error).
		182
		183	=back
69		184
70	=cut	185	=cut
71		186
72	package IO::AIO;	187	package IO::AIO;
73		188
…		…
75	use strict 'vars';	190	use strict 'vars';
76		191
77	use base 'Exporter';	192	use base 'Exporter';
78		193
79	BEGIN {	194	BEGIN {
80	our $VERSION = '2.0';	195	our $VERSION = '2.2';
81		196
82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	197	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	198	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	199	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
85	aio_group aio_nop);	200	aio_move aio_copy aio_group aio_nop aio_mknod);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	203	min_parallel max_parallel max_idle
		204	nreqs nready npending nthreads
		205	max_poll_time max_poll_reqs);
89		206
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		208
92	require XSLoader;	209	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
94	}	211	}
95		212
96	=head1 FUNCTIONS	213	=head1 FUNCTIONS
97		214
98	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
99		216
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	219	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	220	which must be a code reference. This code reference will get called with
…		…
106	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
107		224
108	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	226	internally until the request has finished.
110		227
111	All requests return objects of type L<IO::AIO::REQ> that allow further	228	All functions return request objects of type L<IO::AIO::REQ> that allow
112	manipulation of those requests while they are in-flight.	229	further manipulation of those requests while they are in-flight.
113		230
114	The pathnames you pass to these routines I<must> be absolute and	231	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	232	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	233	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
118	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
119		237
120	To encode pathnames to byte form, either make sure you either: a)	238	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	239	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	240	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	241	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)	242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	243	use something else to ensure your scalar has the correct contents.
		244
		245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		246	handles correctly wether it is set or not.
126		247
127	=over 4	248	=over 4
128		249
129	=item aioreq_pri $pri	250	=item $prev_pri = aioreq_pri [$pri]
130		251
131	Sets the priority for the next aio request. The default priority	252	Returns the priority value that would be used for the next request and, if
		253	C<$pri> is given, sets the priority for the next aio request.
		254
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	255	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	256	and C<4>, respectively. Requests with higher priority will be serviced
		257	first.
134		258
135	The priority will be reset to C<0> after each call to one of the C<aio_>	259	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	260	functions.
137		261
138	Example: open a file with low priority, then read something from it with	262	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	263	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	264	open requests (potentially spamming the cache):
…		…
150	};	274	};
151		275
152	=item aioreq_nice $pri_adjust	276	=item aioreq_nice $pri_adjust
153		277
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	278	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	279	priority, so the effect is cumulative.
156		280
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	281	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		282
159	Asynchronously open or create a file and call the callback with a newly	283	Asynchronously open or create a file and call the callback with a newly
160	created filehandle for the file.	284	created filehandle for the file.
…		…
210		334
211	aio_read $fh, 7, 15, $buffer, 0, sub {	335	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	336	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	337	print "read $_[0] bytes: <$buffer>\n";
214	};	338	};
215
216	=item aio_move $srcpath, $dstpath, $callback->($status)
217
218	[EXPERIMENTAL due to internal aio_group use]
219
220	Try to move the I<file> (directories not supported as either source or
221	destination) from C<$srcpath> to C<$dstpath> and call the callback with
222	the C<0> (error) or C<-1> ok.
223
224	This is a composite request that tries to rename(2) the file first. If
225	rename files with C<EXDEV>, it creates the destination file with mode 0200
226	and copies the contents of the source file into it using C<aio_sendfile>,
227	followed by restoring atime, mtime, access mode and uid/gid, in that
228	order, and unlinking the C<$srcpath>.
229
230	If an error occurs, the partial destination file will be unlinked, if
231	possible, except when setting atime, mtime, access mode and uid/gid, where
232	errors are being ignored.
233
234	=cut
235
236	sub aio_move($$$) {
237	my ($src, $dst, $cb) = @_;
238
239	my $grp = aio_group $cb;
240
241	add $grp aio_rename $src, $dst, sub {
242	if ($_[0] && $! == EXDEV) {
243	add $grp aio_open $src, O_RDONLY, 0, sub {
244	if (my $src_fh = $_[0]) {
245	my @stat = stat $src_fh;
246
247	add $grp aio_open $dst, O_WRONLY, 0200, sub {
248	if (my $dst_fh = $_[0]) {
249	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
250	close $src_fh;
251
252	if ($_[0] == $stat[7]) {
253	utime $stat[8], $stat[9], $dst;
254	chmod $stat[2] & 07777, $dst_fh;
255	chown $stat[4], $stat[5], $dst_fh;
256	close $dst_fh;
257
258	add $grp aio_unlink $src, sub {
259	$grp->result ($_[0]);
260	};
261	} else {
262	my $errno = $!;
263	add $grp aio_unlink $dst, sub {
264	$! = $errno;
265	$grp->result (-1);
266	};
267	}
268	};
269	} else {
270	$grp->result (-1);
271	}
272	},
273
274	} else {
275	$grp->result (-1);
276	}
277	};
278	} else {
279	$grp->result ($_[0]);
280	}
281	};
282
283	$grp
284	}
285		339
286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	340	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
287		341
288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	342	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
289	reading at byte offset C<$in_offset>, and starts writing at the current	343	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
345	=item aio_unlink $pathname, $callback->($status)	399	=item aio_unlink $pathname, $callback->($status)
346		400
347	Asynchronously unlink (delete) a file and call the callback with the	401	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	402	result code.
349		403
		404	=item aio_mknod $path, $mode, $dev, $callback->($status)
		405
		406	[EXPERIMENTAL]
		407
		408	Asynchronously create a device node (or fifo). See mknod(2).
		409
		410	The only (POSIX-) portable way of calling this function is:
		411
		412	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		413
350	=item aio_link $srcpath, $dstpath, $callback->($status)	414	=item aio_link $srcpath, $dstpath, $callback->($status)
351		415
352	Asynchronously create a new link to the existing object at C<$srcpath> at	416	Asynchronously create a new link to the existing object at C<$srcpath> at
353	the path C<$dstpath> and call the callback with the result code.	417	the path C<$dstpath> and call the callback with the result code.
354		418
355	=item aio_symlink $srcpath, $dstpath, $callback->($status)	419	=item aio_symlink $srcpath, $dstpath, $callback->($status)
356		420
357	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	421	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
358	the path C<$dstpath> and call the callback with the result code.	422	the path C<$dstpath> and call the callback with the result code.
		423
		424	=item aio_readlink $path, $callback->($link)
		425
		426	Asynchronously read the symlink specified by C<$path> and pass it to
		427	the callback. If an error occurs, nothing or undef gets passed to the
		428	callback.
359		429
360	=item aio_rename $srcpath, $dstpath, $callback->($status)	430	=item aio_rename $srcpath, $dstpath, $callback->($status)
361		431
362	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	432	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
363	rename(2) and call the callback with the result code.	433	rename(2) and call the callback with the result code.
…		…
374	sorted, and will B<NOT> include the C<.> and C<..> entries.	444	sorted, and will B<NOT> include the C<.> and C<..> entries.
375		445
376	The callback a single argument which is either C<undef> or an array-ref	446	The callback a single argument which is either C<undef> or an array-ref
377	with the filenames.	447	with the filenames.
378		448
		449	=item aio_copy $srcpath, $dstpath, $callback->($status)
		450
		451	Try to copy the I<file> (directories not supported as either source or
		452	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		453	the C<0> (error) or C<-1> ok.
		454
		455	This is a composite request that it creates the destination file with
		456	mode 0200 and copies the contents of the source file into it using
		457	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		458	uid/gid, in that order.
		459
		460	If an error occurs, the partial destination file will be unlinked, if
		461	possible, except when setting atime, mtime, access mode and uid/gid, where
		462	errors are being ignored.
		463
		464	=cut
		465
		466	sub aio_copy($$;$) {
		467	my ($src, $dst, $cb) = @_;
		468
		469	my $pri = aioreq_pri;
		470	my $grp = aio_group $cb;
		471
		472	aioreq_pri $pri;
		473	add $grp aio_open $src, O_RDONLY, 0, sub {
		474	if (my $src_fh = $_[0]) {
		475	my @stat = stat $src_fh;
		476
		477	aioreq_pri $pri;
		478	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		479	if (my $dst_fh = $_[0]) {
		480	aioreq_pri $pri;
		481	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		482	if ($_[0] == $stat[7]) {
		483	$grp->result (0);
		484	close $src_fh;
		485
		486	# those should not normally block. should. should.
		487	utime $stat[8], $stat[9], $dst;
		488	chmod $stat[2] & 07777, $dst_fh;
		489	chown $stat[4], $stat[5], $dst_fh;
		490	close $dst_fh;
		491	} else {
		492	$grp->result (-1);
		493	close $src_fh;
		494	close $dst_fh;
		495
		496	aioreq $pri;
		497	add $grp aio_unlink $dst;
		498	}
		499	};
		500	} else {
		501	$grp->result (-1);
		502	}
		503	},
		504
		505	} else {
		506	$grp->result (-1);
		507	}
		508	};
		509
		510	$grp
		511	}
		512
		513	=item aio_move $srcpath, $dstpath, $callback->($status)
		514
		515	Try to move the I<file> (directories not supported as either source or
		516	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		517	the C<0> (error) or C<-1> ok.
		518
		519	This is a composite request that tries to rename(2) the file first. If
		520	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		521	that is successful, unlinking the C<$srcpath>.
		522
		523	=cut
		524
		525	sub aio_move($$;$) {
		526	my ($src, $dst, $cb) = @_;
		527
		528	my $pri = aioreq_pri;
		529	my $grp = aio_group $cb;
		530
		531	aioreq_pri $pri;
		532	add $grp aio_rename $src, $dst, sub {
		533	if ($_[0] && $! == EXDEV) {
		534	aioreq_pri $pri;
		535	add $grp aio_copy $src, $dst, sub {
		536	$grp->result ($_[0]);
		537
		538	if (!$_[0]) {
		539	aioreq_pri $pri;
		540	add $grp aio_unlink $src;
		541	}
		542	};
		543	} else {
		544	$grp->result ($_[0]);
		545	}
		546	};
		547
		548	$grp
		549	}
		550
379	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	551	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
380		552
381	[EXPERIMENTAL due to internal aio_group use]
382
383	Scans a directory (similar to C<aio_readdir>) but additionally tries to	553	Scans a directory (similar to C<aio_readdir>) but additionally tries to
384	separate the entries of directory C<$path> into two sets of names, ones	554	efficiently separate the entries of directory C<$path> into two sets of
385	you can recurse into (directories or links to them), and ones you cannot	555	names, directories you can recurse into (directories), and ones you cannot
386	recurse into (everything else).	556	recurse into (everything else, including symlinks to directories).
387		557
388	C<aio_scandir> is a composite request that creates of many sub requests_	558	C<aio_scandir> is a composite request that creates of many sub requests_
389	C<$maxreq> specifies the maximum number of outstanding aio requests that	559	C<$maxreq> specifies the maximum number of outstanding aio requests that
390	this function generates. If it is C<< <= 0 >>, then a suitable default	560	this function generates. If it is C<< <= 0 >>, then a suitable default
391	will be chosen (currently 6).	561	will be chosen (currently 4).
392		562
393	On error, the callback is called without arguments, otherwise it receives	563	On error, the callback is called without arguments, otherwise it receives
394	two array-refs with path-relative entry names.	564	two array-refs with path-relative entry names.
395		565
396	Example:	566	Example:
…		…
433	=cut	603	=cut
434		604
435	sub aio_scandir($$$) {	605	sub aio_scandir($$$) {
436	my ($path, $maxreq, $cb) = @_;	606	my ($path, $maxreq, $cb) = @_;
437		607
		608	my $pri = aioreq_pri;
		609
438	my $grp = aio_group $cb;	610	my $grp = aio_group $cb;
439		611
440	$maxreq = 6 if $maxreq <= 0;	612	$maxreq = 4 if $maxreq <= 0;
441		613
442	# stat once	614	# stat once
		615	aioreq_pri $pri;
443	add $grp aio_stat $path, sub {	616	add $grp aio_stat $path, sub {
444	return $grp->result () if $_[0];	617	return $grp->result () if $_[0];
445	my $now = time;	618	my $now = time;
446	my $hash1 = join ":", (stat _)[0,1,3,7,9];	619	my $hash1 = join ":", (stat _)[0,1,3,7,9];
447		620
448	# read the directory entries	621	# read the directory entries
		622	aioreq_pri $pri;
449	add $grp aio_readdir $path, sub {	623	add $grp aio_readdir $path, sub {
450	my $entries = shift	624	my $entries = shift
451	or return $grp->result ();	625	or return $grp->result ();
452		626
453	# stat the dir another time	627	# stat the dir another time
		628	aioreq_pri $pri;
454	add $grp aio_stat $path, sub {	629	add $grp aio_stat $path, sub {
455	my $hash2 = join ":", (stat _)[0,1,3,7,9];	630	my $hash2 = join ":", (stat _)[0,1,3,7,9];
456		631
457	my $ndirs;	632	my $ndirs;
458		633
…		…
473	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	648	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
474	@$entries];	649	@$entries];
475		650
476	my (@dirs, @nondirs);	651	my (@dirs, @nondirs);
477		652
478	my ($statcb, $schedcb);
479	my $nreq = 0;
480
481	my $statgrp = add $grp aio_group;	653	my $statgrp = add $grp aio_group sub {
		654	$grp->result (\@dirs, \@nondirs);
		655	};
482		656
483	$schedcb = sub {	657	limit $statgrp $maxreq;
484	if (@$entries) {	658	feed $statgrp sub {
485	if ($nreq < $maxreq) {	659	return unless @$entries;
486	my $ent = pop @$entries;	660	my $entry = pop @$entries;
		661
		662	aioreq_pri $pri;
		663	add $statgrp aio_stat "$path/$entry/.", sub {
		664	if ($_[0] < 0) {
		665	push @nondirs, $entry;
		666	} else {
		667	# need to check for real directory
		668	aioreq_pri $pri;
		669	add $statgrp aio_lstat "$path/$entry", sub {
		670	if (-d _) {
		671	push @dirs, $entry;
		672
		673	unless (--$ndirs) {
		674	push @nondirs, @$entries;
		675	feed $statgrp;
		676	}
		677	} else {
		678	push @nondirs, $entry;
		679	}
487	$nreq++;	680	}
488	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
489	}	681	}
490	} elsif (!$nreq) {
491	# finished
492	$statgrp->cancel;
493	undef $statcb;
494	undef $schedcb;
495	$grp->result (\@dirs, \@nondirs);
496	}	682	};
497	};	683	};
498	$statcb = sub {
499	my ($status, $entry) = @_;
500
501	if ($status < 0) {
502	$nreq--;
503	push @nondirs, $entry;
504	&$schedcb;
505	} else {
506	# need to check for real directory
507	add $grp aio_lstat "$path/$entry", sub {
508	$nreq--;
509
510	if (-d _) {
511	push @dirs, $entry;
512
513	if (!--$ndirs) {
514	push @nondirs, @$entries;
515	$entries = [];
516	}
517	} else {
518	push @nondirs, $entry;
519	}
520
521	&$schedcb;
522	}
523	}
524	};
525
526	&$schedcb while @$entries && $nreq < $maxreq;
527	};	684	};
528	};	685	};
529	};	686	};
530		687
531	$grp	688	$grp
…		…
544	If this call isn't available because your OS lacks it or it couldn't be	701	If this call isn't available because your OS lacks it or it couldn't be
545	detected, it will be emulated by calling C<fsync> instead.	702	detected, it will be emulated by calling C<fsync> instead.
546		703
547	=item aio_group $callback->(...)	704	=item aio_group $callback->(...)
548		705
549	[EXPERIMENTAL]
550
551	This is a very special aio request: Instead of doing something, it is a	706	This is a very special aio request: Instead of doing something, it is a
552	container for other aio requests, which is useful if you want to bundle	707	container for other aio requests, which is useful if you want to bundle
553	many requests into a single, composite, request.	708	many requests into a single, composite, request with a definite callback
		709	and the ability to cancel the whole request with its subrequests.
554		710
555	Returns an object of class L<IO::AIO::GRP>. See its documentation below	711	Returns an object of class L<IO::AIO::GRP>. See its documentation below
556	for more info.	712	for more info.
557		713
558	Example:	714	Example:
…		…
577	phase and still requires a worker thread. Thus, the callback will not	733	phase and still requires a worker thread. Thus, the callback will not
578	be executed immediately but only after other requests in the queue have	734	be executed immediately but only after other requests in the queue have
579	entered their execution phase. This can be used to measure request	735	entered their execution phase. This can be used to measure request
580	latency.	736	latency.
581		737
582	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	738	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
583		739
584	Mainly used for debugging and benchmarking, this aio request puts one of	740	Mainly used for debugging and benchmarking, this aio request puts one of
585	the request workers to sleep for the given time.	741	the request workers to sleep for the given time.
586		742
587	While it is theoretically handy to have simple I/O scheduling requests	743	While it is theoretically handy to have simple I/O scheduling requests
588	like sleep and file handle readable/writable, the overhead this creates	744	like sleep and file handle readable/writable, the overhead this creates is
589	is immense, so do not use this function except to put your application	745	immense (it blocks a thread for a long time) so do not use this function
590	under artificial I/O pressure.	746	except to put your application under artificial I/O pressure.
591		747
592	=back	748	=back
593		749
594	=head2 IO::AIO::REQ CLASS	750	=head2 IO::AIO::REQ CLASS
595		751
596	All non-aggregate C<aio_*> functions return an object of this class when	752	All non-aggregate C<aio_*> functions return an object of this class when
597	called in non-void context.	753	called in non-void context.
598
599	A request always moves through the following five states in its lifetime,
600	in order: B<ready> (request has been created, but has not been executed
601	yet), B<execute> (request is currently being executed), B<pending>
602	(request has been executed but callback has not been called yet),
603	B<result> (results are being processed synchronously, includes calling the
604	callback) and B<done> (request has reached the end of its lifetime and
605	holds no resources anymore).
606		754
607	=over 4	755	=over 4
608		756
609	=item cancel $req	757	=item cancel $req
610		758
…		…
664	=item * They can also can also be added to other IO::AIO::GRP objects.	812	=item * They can also can also be added to other IO::AIO::GRP objects.
665		813
666	=item * You must not add requests to a group from within the group callback (or	814	=item * You must not add requests to a group from within the group callback (or
667	any later time).	815	any later time).
668		816
669	=item * This does not harmonise well with C<max_outstanding>, so best do
670	not combine C<aio_group> with it. Groups and feeders are recommended for
671	this kind of concurrency-limiting.
672
673	=back	817	=back
674		818
675	Their lifetime, simplified, looks like this: when they are empty, they	819	Their lifetime, simplified, looks like this: when they are empty, they
676	will finish very quickly. If they contain only requests that are in the	820	will finish very quickly. If they contain only requests that are in the
677	C<done> state, they will also finish. Otherwise they will continue to	821	C<done> state, they will also finish. Otherwise they will continue to
…		…
692	be added, including other groups, as long as you do not create circular	836	be added, including other groups, as long as you do not create circular
693	dependencies.	837	dependencies.
694		838
695	Returns all its arguments.	839	Returns all its arguments.
696		840
		841	=item $grp->cancel_subs
		842
		843	Cancel all subrequests and clears any feeder, but not the group request
		844	itself. Useful when you queued a lot of events but got a result early.
		845
697	=item $grp->result (...)	846	=item $grp->result (...)
698		847
699	Set the result value(s) that will be passed to the group callback when all	848	Set the result value(s) that will be passed to the group callback when all
700	subrequests have finished. By default, no argument will be passed.	849	subrequests have finished and set thre groups errno to the current value
		850	of errno (just like calling C<errno> without an error number). By default,
		851	no argument will be passed and errno is zero.
		852
		853	=item $grp->errno ([$errno])
		854
		855	Sets the group errno value to C<$errno>, or the current value of errno
		856	when the argument is missing.
		857
		858	Every aio request has an associated errno value that is restored when
		859	the callback is invoked. This method lets you change this value from its
		860	default (0).
		861
		862	Calling C<result> will also set errno, so make sure you either set C<$!>
		863	before the call to C<result>, or call c<errno> after it.
701		864
702	=item feed $grp $callback->($grp)	865	=item feed $grp $callback->($grp)
703
704	[VERY EXPERIMENTAL]
705		866
706	Sets a feeder/generator on this group: every group can have an attached	867	Sets a feeder/generator on this group: every group can have an attached
707	generator that generates requests if idle. The idea behind this is that,	868	generator that generates requests if idle. The idea behind this is that,
708	although you could just queue as many requests as you want in a group,	869	although you could just queue as many requests as you want in a group,
709	this might starve other requests for a potentially long time. For	870	this might starve other requests for a potentially long time. For
…		…
746		907
747	=back	908	=back
748		909
749	=head2 SUPPORT FUNCTIONS	910	=head2 SUPPORT FUNCTIONS
750		911
		912	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		913
751	=over 4	914	=over 4
752		915
753	=item $fileno = IO::AIO::poll_fileno	916	=item $fileno = IO::AIO::poll_fileno
754		917
755	Return the I<request result pipe file descriptor>. This filehandle must be	918	Return the I<request result pipe file descriptor>. This filehandle must be
…		…
759		922
760	See C<poll_cb> for an example.	923	See C<poll_cb> for an example.
761		924
762	=item IO::AIO::poll_cb	925	=item IO::AIO::poll_cb
763		926
764	Process all outstanding events on the result pipe. You have to call this	927	Process some outstanding events on the result pipe. You have to call this
765	regularly. Returns the number of events processed. Returns immediately	928	regularly. Returns the number of events processed. Returns immediately
766	when no events are outstanding.	929	when no events are outstanding. The amount of events processed depends on
		930	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		931
		932	If not all requests were processed for whatever reason, the filehandle
		933	will still be ready when C<poll_cb> returns.
767		934
768	Example: Install an Event watcher that automatically calls	935	Example: Install an Event watcher that automatically calls
769	IO::AIO::poll_cb with high priority:	936	IO::AIO::poll_cb with high priority:
770		937
771	Event->io (fd => IO::AIO::poll_fileno,	938	Event->io (fd => IO::AIO::poll_fileno,
772	poll => 'r', async => 1,	939	poll => 'r', async => 1,
773	cb => \&IO::AIO::poll_cb);	940	cb => \&IO::AIO::poll_cb);
774		941
		942	=item IO::AIO::max_poll_reqs $nreqs
		943
		944	=item IO::AIO::max_poll_time $seconds
		945
		946	These set the maximum number of requests (default C<0>, meaning infinity)
		947	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		948	the maximum amount of time (default C<0>, meaning infinity) spent in
		949	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		950	of time C<poll_cb> is allowed to use).
		951
		952	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		953	syscall per request processed, which is not normally a problem unless your
		954	callbacks are really really fast or your OS is really really slow (I am
		955	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		956
		957	Setting these is useful if you want to ensure some level of
		958	interactiveness when perl is not fast enough to process all requests in
		959	time.
		960
		961	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		962
		963	Example: Install an Event watcher that automatically calls
		964	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		965	program get the CPU sometimes even under high AIO load.
		966
		967	# try not to spend much more than 0.1s in poll_cb
		968	IO::AIO::max_poll_time 0.1;
		969
		970	# use a low priority so other tasks have priority
		971	Event->io (fd => IO::AIO::poll_fileno,
		972	poll => 'r', nice => 1,
		973	cb => &IO::AIO::poll_cb);
		974
775	=item IO::AIO::poll_wait	975	=item IO::AIO::poll_wait
776		976
		977	If there are any outstanding requests and none of them in the result
777	Wait till the result filehandle becomes ready for reading (simply does a	978	phase, wait till the result filehandle becomes ready for reading (simply
778	C<select> on the filehandle. This is useful if you want to synchronously wait	979	does a C<select> on the filehandle. This is useful if you want to
779	for some requests to finish).	980	synchronously wait for some requests to finish).
780		981
781	See C<nreqs> for an example.	982	See C<nreqs> for an example.
782		983
		984	=item IO::AIO::poll
		985
		986	Waits until some requests have been handled.
		987
		988	Returns the number of requests processed, but is otherwise strictly
		989	equivalent to:
		990
		991	IO::AIO::poll_wait, IO::AIO::poll_cb
		992
783	=item IO::AIO::nreqs	993	=item IO::AIO::flush
784		994
785	Returns the number of requests currently outstanding (i.e. for which their	995	Wait till all outstanding AIO requests have been handled.
786	callback has not been invoked yet).
787		996
788	Example: wait till there are no outstanding requests anymore:	997	Strictly equivalent to:
789		998
790	IO::AIO::poll_wait, IO::AIO::poll_cb	999	IO::AIO::poll_wait, IO::AIO::poll_cb
791	while IO::AIO::nreqs;	1000	while IO::AIO::nreqs;
792		1001
793	=item IO::AIO::flush	1002	=head3 CONTROLLING THE NUMBER OF THREADS
794
795	Wait till all outstanding AIO requests have been handled.
796
797	Strictly equivalent to:
798
799	IO::AIO::poll_wait, IO::AIO::poll_cb
800	while IO::AIO::nreqs;
801
802	=item IO::AIO::poll
803
804	Waits until some requests have been handled.
805
806	Strictly equivalent to:
807
808	IO::AIO::poll_wait, IO::AIO::poll_cb
809	if IO::AIO::nreqs;
810		1003
811	=item IO::AIO::min_parallel $nthreads	1004	=item IO::AIO::min_parallel $nthreads
812		1005
813	Set the minimum number of AIO threads to C<$nthreads>. The current	1006	Set the minimum number of AIO threads to C<$nthreads>. The current
814	default is C<8>, which means eight asynchronous operations can execute	1007	default is C<8>, which means eight asynchronous operations can execute
815	concurrently at any one time (the number of outstanding requests,	1008	concurrently at any one time (the number of outstanding requests,
816	however, is unlimited).	1009	however, is unlimited).
817		1010
818	IO::AIO starts threads only on demand, when an AIO request is queued and	1011	IO::AIO starts threads only on demand, when an AIO request is queued and
819	no free thread exists.	1012	no free thread exists. Please note that queueing up a hundred requests can
		1013	create demand for a hundred threads, even if it turns out that everything
		1014	is in the cache and could have been processed faster by a single thread.
820		1015
821	It is recommended to keep the number of threads relatively low, as some	1016	It is recommended to keep the number of threads relatively low, as some
822	Linux kernel versions will scale negatively with the number of threads	1017	Linux kernel versions will scale negatively with the number of threads
823	(higher parallelity => MUCH higher latency). With current Linux 2.6	1018	(higher parallelity => MUCH higher latency). With current Linux 2.6
824	versions, 4-32 threads should be fine.	1019	versions, 4-32 threads should be fine.
…		…
838	This module automatically runs C<max_parallel 0> at program end, to ensure	1033	This module automatically runs C<max_parallel 0> at program end, to ensure
839	that all threads are killed and that there are no outstanding requests.	1034	that all threads are killed and that there are no outstanding requests.
840		1035
841	Under normal circumstances you don't need to call this function.	1036	Under normal circumstances you don't need to call this function.
842		1037
		1038	=item IO::AIO::max_idle $nthreads
		1039
		1040	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1041	threads that did not get a request to process within 10 seconds). That
		1042	means if a thread becomes idle while C<$nthreads> other threads are also
		1043	idle, it will free its resources and exit.
		1044
		1045	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1046	to allow for extremely high load situations, but want to free resources
		1047	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1048
		1049	The default is probably ok in most situations, especially if thread
		1050	creation is fast. If thread creation is very slow on your system you might
		1051	want to use larger values.
		1052
843	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1053	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
844		1054
845	[DEPRECATED]	1055	This is a very bad function to use in interactive programs because it
		1056	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1057	use an C<aio_group> together with a feed callback.
846		1058
847	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1059	Sets the maximum number of outstanding requests to C<$nreqs>. If you
848	try to queue up more than this number of requests, the caller will block until	1060	to queue up more than this number of requests, the next call to the
849	some requests have been handled.	1061	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1062	function will block until the limit is no longer exceeded.
850		1063
851	The default is very large, so normally there is no practical limit. If you	1064	The default value is very large, so there is no practical limit on the
852	queue up many requests in a loop it often improves speed if you set	1065	number of outstanding requests.
853	this to a relatively low number, such as C<100>.
854		1066
855	This function does not work well together with C<aio_group>'s, and their	1067	You can still queue as many requests as you want. Therefore,
856	feeder interface is better suited to limiting concurrency, so do not use	1068	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
857	this function.	1069	as a stop gap to shield against fatal memory overflow (with large values).
858		1070
859	Under normal circumstances you don't need to call this function.	1071	=head3 STATISTICAL INFORMATION
		1072
		1073	=item IO::AIO::nreqs
		1074
		1075	Returns the number of requests currently in the ready, execute or pending
		1076	states (i.e. for which their callback has not been invoked yet).
		1077
		1078	Example: wait till there are no outstanding requests anymore:
		1079
		1080	IO::AIO::poll_wait, IO::AIO::poll_cb
		1081	while IO::AIO::nreqs;
		1082
		1083	=item IO::AIO::nready
		1084
		1085	Returns the number of requests currently in the ready state (not yet
		1086	executed).
		1087
		1088	=item IO::AIO::npending
		1089
		1090	Returns the number of requests currently in the pending state (executed,
		1091	but not yet processed by poll_cb).
860		1092
861	=back	1093	=back
862		1094
863	=cut	1095	=cut
864		1096
…		…
879	}	1111	}
880		1112
881	min_parallel 8;	1113	min_parallel 8;
882		1114
883	END {	1115	END {
884	max_parallel 0;	1116	min_parallel 1;
885	}	1117	flush;
		1118	};
886		1119
887	1;	1120	1;
888		1121
889	=head2 FORK BEHAVIOUR	1122	=head2 FORK BEHAVIOUR
890		1123
891	This module should do "the right thing" when the process using it forks:	1124	This module should do "the right thing" when the process using it forks:
892		1125
893	Before the fork, IO::AIO enters a quiescent state where no requests	1126	Before the fork, IO::AIO enters a quiescent state where no requests
894	can be added in other threads and no results will be processed. After	1127	can be added in other threads and no results will be processed. After
895	the fork the parent simply leaves the quiescent state and continues	1128	the fork the parent simply leaves the quiescent state and continues
896	request/result processing, while the child clears the request/result	1129	request/result processing, while the child frees the request/result queue
897	queue (so the requests started before the fork will only be handled in	1130	(so that the requests started before the fork will only be handled in the
898	the parent). Threads will be started on demand until the limit ste in the	1131	parent). Threads will be started on demand until the limit set in the
899	parent process has been reached again.	1132	parent process has been reached again.
900		1133
901	In short: the parent will, after a short pause, continue as if fork had	1134	In short: the parent will, after a short pause, continue as if fork had
902	not been called, while the child will act as if IO::AIO has not been used	1135	not been called, while the child will act as if IO::AIO has not been used
903	yet.	1136	yet.
904		1137
905	=head2 MEMORY USAGE	1138	=head2 MEMORY USAGE
906		1139
		1140	Per-request usage:
		1141
907	Each aio request uses - depending on your architecture - around 128 bytes	1142	Each aio request uses - depending on your architecture - around 100-200
908	of memory. In addition, stat requests need a stat buffer (possibly a few	1143	bytes of memory. In addition, stat requests need a stat buffer (possibly
909	hundred bytes). Perl scalars and other data passed into aio requests will	1144	a few hundred bytes), readdir requires a result buffer and so on. Perl
910	also be locked.	1145	scalars and other data passed into aio requests will also be locked and
		1146	will consume memory till the request has entered the done state.
911		1147
912	This is now awfully much, so queuing lots of requests is not usually a	1148	This is now awfully much, so queuing lots of requests is not usually a
913	problem.	1149	problem.
914		1150
915	Each thread needs a stack area which is usually around 16k, sometimes much	1151	Per-thread usage:
916	larger, depending on the OS.	1152
		1153	In the execution phase, some aio requests require more memory for
		1154	temporary buffers, and each thread requires a stack and other data
		1155	structures (usually around 16k-128k, depending on the OS).
		1156
		1157	=head1 KNOWN BUGS
		1158
		1159	Known bugs will be fixed in the next release.
917		1160
918	=head1 SEE ALSO	1161	=head1 SEE ALSO
919		1162
920	L<Coro::AIO>.	1163	L<Coro::AIO>.
921		1164

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs. Revision 1.94 by root, Wed Nov 8 02:01:02 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.94 by root, Wed Nov 8 02:01:02 2006 UTC