[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 1.93 by root, Wed Nov 8 01:59:58 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 most of this works on all types of file descriptors (for example
		67	sockets), using these functions on file descriptors that support
		68	nonblocking operation (again, sockets, pipes etc.) is very inefficient or
		69	might not work (aio_read fails on sockets/pipes/fifos). Use an event loop
		70	for that (such as the L<Event\|Event> module): IO::AIO will naturally fit
		71	into such an event loop itself.
		72
56	Currently, a number of threads are started that execute your read/writes	73	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	74	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	75	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	76	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	77	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	78	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	79	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	80	aio_write, so the remaining functionality would have to be implemented
		81	using threads anyway.
64		82
65	Although the module will work with in the presence of other threads,	83	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	84	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	85	locking yourself, always call C<poll_cb> from within the same thread, or
68	call C<poll_cb> (or other C<aio_> functions) recursively.	86	never call C<poll_cb> (or other C<aio_> functions) recursively.
		87
		88	=head2 EXAMPLE
		89
		90	This is a simple example that uses the Event module and loads
		91	F</etc/passwd> asynchronously:
		92
		93	use Fcntl;
		94	use Event;
		95	use IO::AIO;
		96
		97	# register the IO::AIO callback with Event
		98	Event->io (fd => IO::AIO::poll_fileno,
		99	poll => 'r',
		100	cb => \&IO::AIO::poll_cb);
		101
		102	# queue the request to open /etc/passwd
		103	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		104	my $fh = $_[0]
		105	or die "error while opening: $!";
		106
		107	# stat'ing filehandles is generally non-blocking
		108	my $size = -s $fh;
		109
		110	# queue a request to read the file
		111	my $contents;
		112	aio_read $fh, 0, $size, $contents, 0, sub {
		113	$_[0] == $size
		114	or die "short read: $!";
		115
		116	close $fh;
		117
		118	# file contents now in $contents
		119	print $contents;
		120
		121	# exit event loop and program
		122	Event::unloop;
		123	};
		124	};
		125
		126	# possibly queue up other requests, or open GUI windows,
		127	# check for sockets etc. etc.
		128
		129	# process events as long as there are some:
		130	Event::loop;
		131
		132	=head1 REQUEST ANATOMY AND LIFETIME
		133
		134	Every C<aio_*> function creates a request. which is a C data structure not
		135	directly visible to Perl.
		136
		137	If called in non-void context, every request function returns a Perl
		138	object representing the request. In void context, nothing is returned,
		139	which saves a bit of memory.
		140
		141	The perl object is a fairly standard ref-to-hash object. The hash contents
		142	are not used by IO::AIO so you are free to store anything you like in it.
		143
		144	During their existance, aio requests travel through the following states,
		145	in order:
		146
		147	=over 4
		148
		149	=item ready
		150
		151	Immediately after a request is created it is put into the ready state,
		152	waiting for a thread to execute it.
		153
		154	=item execute
		155
		156	A thread has accepted the request for processing and is currently
		157	executing it (e.g. blocking in read).
		158
		159	=item pending
		160
		161	The request has been executed and is waiting for result processing.
		162
		163	While request submission and execution is fully asynchronous, result
		164	processing is not and relies on the perl interpreter calling C<poll_cb>
		165	(or another function with the same effect).
		166
		167	=item result
		168
		169	The request results are processed synchronously by C<poll_cb>.
		170
		171	The C<poll_cb> function will process all outstanding aio requests by
		172	calling their callbacks, freeing memory associated with them and managing
		173	any groups they are contained in.
		174
		175	=item done
		176
		177	Request has reached the end of its lifetime and holds no resources anymore
		178	(except possibly for the Perl object, but its connection to the actual
		179	aio request is severed and calling its methods will either do nothing or
		180	result in a runtime error).
		181
		182	=back
69		183
70	=cut	184	=cut
71		185
72	package IO::AIO;	186	package IO::AIO;
73		187
…		…
75	use strict 'vars';	189	use strict 'vars';
76		190
77	use base 'Exporter';	191	use base 'Exporter';
78		192
79	BEGIN {	193	BEGIN {
80	our $VERSION = '2.0';	194	our $VERSION = '2.2';
81		195
82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	196	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	197	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	198	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
85	aio_group aio_nop);	199	aio_move aio_copy aio_group aio_nop aio_mknod);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	200	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	201	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	202	min_parallel max_parallel max_idle
		203	nreqs nready npending nthreads
		204	max_poll_time max_poll_reqs);
89		205
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	206	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		207
92	require XSLoader;	208	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	209	XSLoader::load ("IO::AIO", $VERSION);
94	}	210	}
95		211
96	=head1 FUNCTIONS	212	=head1 FUNCTIONS
97		213
98	=head2 AIO FUNCTIONS	214	=head2 AIO REQUEST FUNCTIONS
99		215
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	216	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	217	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	218	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	219	which must be a code reference. This code reference will get called with
…		…
106	syscall has been executed asynchronously.	222	syscall has been executed asynchronously.
107		223
108	All functions expecting a filehandle keep a copy of the filehandle	224	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	225	internally until the request has finished.
110		226
111	All requests return objects of type L<IO::AIO::REQ> that allow further	227	All functions return request objects of type L<IO::AIO::REQ> that allow
112	manipulation of those requests while they are in-flight.	228	further manipulation of those requests while they are in-flight.
113		229
114	The pathnames you pass to these routines I<must> be absolute and	230	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	231	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	232	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	233	changed. Alternatively, you can make sure that you never change the
118	current working directory.	234	current working directory anywhere in the program and then use relative
		235	paths.
119		236
120	To encode pathnames to byte form, either make sure you either: a)	237	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	238	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	239	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	240	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)	241	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	242	use something else to ensure your scalar has the correct contents.
		243
		244	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		245	handles correctly wether it is set or not.
126		246
127	=over 4	247	=over 4
128		248
129	=item aioreq_pri $pri	249	=item $prev_pri = aioreq_pri [$pri]
130		250
131	Sets the priority for the next aio request. The default priority	251	Returns the priority value that would be used for the next request and, if
		252	C<$pri> is given, sets the priority for the next aio request.
		253
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	254	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	255	and C<4>, respectively. Requests with higher priority will be serviced
		256	first.
134		257
135	The priority will be reset to C<0> after each call to one of the C<aio_>	258	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	259	functions.
137		260
138	Example: open a file with low priority, then read something from it with	261	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	262	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	263	open requests (potentially spamming the cache):
…		…
150	};	273	};
151		274
152	=item aioreq_nice $pri_adjust	275	=item aioreq_nice $pri_adjust
153		276
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	277	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	278	priority, so the effect is cumulative.
156		279
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	280	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		281
159	Asynchronously open or create a file and call the callback with a newly	282	Asynchronously open or create a file and call the callback with a newly
160	created filehandle for the file.	283	created filehandle for the file.
…		…
210		333
211	aio_read $fh, 7, 15, $buffer, 0, sub {	334	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	335	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	336	print "read $_[0] bytes: <$buffer>\n";
214	};	337	};
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		338
284	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	339	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
285		340
286	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	341	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	342	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
343	=item aio_unlink $pathname, $callback->($status)	398	=item aio_unlink $pathname, $callback->($status)
344		399
345	Asynchronously unlink (delete) a file and call the callback with the	400	Asynchronously unlink (delete) a file and call the callback with the
346	result code.	401	result code.
347		402
		403	=item aio_mknod $path, $mode, $dev, $callback->($status)
		404
		405	[EXPERIMENTAL]
		406
		407	Asynchronously create a device node (or fifo). See mknod(2).
		408
		409	The only (POSIX-) portable way of calling this function is:
		410
		411	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		412
348	=item aio_link $srcpath, $dstpath, $callback->($status)	413	=item aio_link $srcpath, $dstpath, $callback->($status)
349		414
350	Asynchronously create a new link to the existing object at C<$srcpath> at	415	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.	416	the path C<$dstpath> and call the callback with the result code.
352		417
353	=item aio_symlink $srcpath, $dstpath, $callback->($status)	418	=item aio_symlink $srcpath, $dstpath, $callback->($status)
354		419
355	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	420	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
356	the path C<$dstpath> and call the callback with the result code.	421	the path C<$dstpath> and call the callback with the result code.
		422
		423	=item aio_readlink $path, $callback->($link)
		424
		425	Asynchronously read the symlink specified by C<$path> and pass it to
		426	the callback. If an error occurs, nothing or undef gets passed to the
		427	callback.
357		428
358	=item aio_rename $srcpath, $dstpath, $callback->($status)	429	=item aio_rename $srcpath, $dstpath, $callback->($status)
359		430
360	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	431	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
361	rename(2) and call the callback with the result code.	432	rename(2) and call the callback with the result code.
…		…
372	sorted, and will B<NOT> include the C<.> and C<..> entries.	443	sorted, and will B<NOT> include the C<.> and C<..> entries.
373		444
374	The callback a single argument which is either C<undef> or an array-ref	445	The callback a single argument which is either C<undef> or an array-ref
375	with the filenames.	446	with the filenames.
376		447
		448	=item aio_copy $srcpath, $dstpath, $callback->($status)
		449
		450	Try to copy the I<file> (directories not supported as either source or
		451	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		452	the C<0> (error) or C<-1> ok.
		453
		454	This is a composite request that it creates the destination file with
		455	mode 0200 and copies the contents of the source file into it using
		456	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		457	uid/gid, in that order.
		458
		459	If an error occurs, the partial destination file will be unlinked, if
		460	possible, except when setting atime, mtime, access mode and uid/gid, where
		461	errors are being ignored.
		462
		463	=cut
		464
		465	sub aio_copy($$;$) {
		466	my ($src, $dst, $cb) = @_;
		467
		468	my $pri = aioreq_pri;
		469	my $grp = aio_group $cb;
		470
		471	aioreq_pri $pri;
		472	add $grp aio_open $src, O_RDONLY, 0, sub {
		473	if (my $src_fh = $_[0]) {
		474	my @stat = stat $src_fh;
		475
		476	aioreq_pri $pri;
		477	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		478	if (my $dst_fh = $_[0]) {
		479	aioreq_pri $pri;
		480	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		481	if ($_[0] == $stat[7]) {
		482	$grp->result (0);
		483	close $src_fh;
		484
		485	# those should not normally block. should. should.
		486	utime $stat[8], $stat[9], $dst;
		487	chmod $stat[2] & 07777, $dst_fh;
		488	chown $stat[4], $stat[5], $dst_fh;
		489	close $dst_fh;
		490	} else {
		491	$grp->result (-1);
		492	close $src_fh;
		493	close $dst_fh;
		494
		495	aioreq $pri;
		496	add $grp aio_unlink $dst;
		497	}
		498	};
		499	} else {
		500	$grp->result (-1);
		501	}
		502	},
		503
		504	} else {
		505	$grp->result (-1);
		506	}
		507	};
		508
		509	$grp
		510	}
		511
		512	=item aio_move $srcpath, $dstpath, $callback->($status)
		513
		514	Try to move the I<file> (directories not supported as either source or
		515	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		516	the C<0> (error) or C<-1> ok.
		517
		518	This is a composite request that tries to rename(2) the file first. If
		519	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		520	that is successful, unlinking the C<$srcpath>.
		521
		522	=cut
		523
		524	sub aio_move($$;$) {
		525	my ($src, $dst, $cb) = @_;
		526
		527	my $pri = aioreq_pri;
		528	my $grp = aio_group $cb;
		529
		530	aioreq_pri $pri;
		531	add $grp aio_rename $src, $dst, sub {
		532	if ($_[0] && $! == EXDEV) {
		533	aioreq_pri $pri;
		534	add $grp aio_copy $src, $dst, sub {
		535	$grp->result ($_[0]);
		536
		537	if (!$_[0]) {
		538	aioreq_pri $pri;
		539	add $grp aio_unlink $src;
		540	}
		541	};
		542	} else {
		543	$grp->result ($_[0]);
		544	}
		545	};
		546
		547	$grp
		548	}
		549
377	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	550	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
378		551
379	Scans a directory (similar to C<aio_readdir>) but additionally tries to	552	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	553	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	554	names, directories you can recurse into (directories), and ones you cannot
382	recurse into (everything else).	555	recurse into (everything else, including symlinks to directories).
383		556
384	C<aio_scandir> is a composite request that creates of many sub requests_	557	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	558	C<$maxreq> specifies the maximum number of outstanding aio requests that
386	this function generates. If it is C<< <= 0 >>, then a suitable default	559	this function generates. If it is C<< <= 0 >>, then a suitable default
387	will be chosen (currently 6).	560	will be chosen (currently 4).
388		561
389	On error, the callback is called without arguments, otherwise it receives	562	On error, the callback is called without arguments, otherwise it receives
390	two array-refs with path-relative entry names.	563	two array-refs with path-relative entry names.
391		564
392	Example:	565	Example:
…		…
429	=cut	602	=cut
430		603
431	sub aio_scandir($$$) {	604	sub aio_scandir($$$) {
432	my ($path, $maxreq, $cb) = @_;	605	my ($path, $maxreq, $cb) = @_;
433		606
		607	my $pri = aioreq_pri;
		608
434	my $grp = aio_group $cb;	609	my $grp = aio_group $cb;
435		610
436	$maxreq = 6 if $maxreq <= 0;	611	$maxreq = 4 if $maxreq <= 0;
437		612
438	# stat once	613	# stat once
		614	aioreq_pri $pri;
439	add $grp aio_stat $path, sub {	615	add $grp aio_stat $path, sub {
440	return $grp->result () if $_[0];	616	return $grp->result () if $_[0];
441	my $now = time;	617	my $now = time;
442	my $hash1 = join ":", (stat _)[0,1,3,7,9];	618	my $hash1 = join ":", (stat _)[0,1,3,7,9];
443		619
444	# read the directory entries	620	# read the directory entries
		621	aioreq_pri $pri;
445	add $grp aio_readdir $path, sub {	622	add $grp aio_readdir $path, sub {
446	my $entries = shift	623	my $entries = shift
447	or return $grp->result ();	624	or return $grp->result ();
448		625
449	# stat the dir another time	626	# stat the dir another time
		627	aioreq_pri $pri;
450	add $grp aio_stat $path, sub {	628	add $grp aio_stat $path, sub {
451	my $hash2 = join ":", (stat _)[0,1,3,7,9];	629	my $hash2 = join ":", (stat _)[0,1,3,7,9];
452		630
453	my $ndirs;	631	my $ndirs;
454		632
…		…
469	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	647	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
470	@$entries];	648	@$entries];
471		649
472	my (@dirs, @nondirs);	650	my (@dirs, @nondirs);
473		651
474	my ($statcb, $schedcb);
475	my $nreq = 0;
476
477	my $statgrp = add $grp aio_group;	652	my $statgrp = add $grp aio_group sub {
		653	$grp->result (\@dirs, \@nondirs);
		654	};
478		655
479	$schedcb = sub {	656	limit $statgrp $maxreq;
480	if (@$entries) {	657	feed $statgrp sub {
481	if ($nreq < $maxreq) {	658	return unless @$entries;
482	my $ent = pop @$entries;	659	my $entry = pop @$entries;
		660
		661	aioreq_pri $pri;
		662	add $statgrp aio_stat "$path/$entry/.", sub {
		663	if ($_[0] < 0) {
		664	push @nondirs, $entry;
		665	} else {
		666	# need to check for real directory
		667	aioreq_pri $pri;
		668	add $statgrp aio_lstat "$path/$entry", sub {
		669	if (-d _) {
		670	push @dirs, $entry;
		671
		672	unless (--$ndirs) {
		673	push @nondirs, @$entries;
		674	feed $statgrp;
		675	}
		676	} else {
		677	push @nondirs, $entry;
		678	}
483	$nreq++;	679	}
484	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
485	}	680	}
486	} elsif (!$nreq) {
487	# finished
488	$statgrp->cancel;
489	undef $statcb;
490	undef $schedcb;
491	$grp->result (\@dirs, \@nondirs);
492	}	681	};
493	};	682	};
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	};	683	};
524	};	684	};
525	};	685	};
526		686
527	$grp	687	$grp
…		…
539		699
540	If this call isn't available because your OS lacks it or it couldn't be	700	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.	701	detected, it will be emulated by calling C<fsync> instead.
542		702
543	=item aio_group $callback->(...)	703	=item aio_group $callback->(...)
544
545	[EXPERIMENTAL]
546		704
547	This is a very special aio request: Instead of doing something, it is a	705	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	706	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	707	many requests into a single, composite, request with a definite callback
550	and the ability to cancel the whole request with its subrequests.	708	and the ability to cancel the whole request with its subrequests.
…		…
591	=head2 IO::AIO::REQ CLASS	749	=head2 IO::AIO::REQ CLASS
592		750
593	All non-aggregate C<aio_*> functions return an object of this class when	751	All non-aggregate C<aio_*> functions return an object of this class when
594	called in non-void context.	752	called in non-void context.
595		753
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	754	=over 4
605		755
606	=item cancel $req	756	=item cancel $req
607		757
608	Cancels the request, if possible. Has the effect of skipping execution	758	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.	811	=item * They can also can also be added to other IO::AIO::GRP objects.
662		812
663	=item * You must not add requests to a group from within the group callback (or	813	=item * You must not add requests to a group from within the group callback (or
664	any later time).	814	any later time).
665		815
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	816	=back
671		817
672	Their lifetime, simplified, looks like this: when they are empty, they	818	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	819	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	820	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	835	be added, including other groups, as long as you do not create circular
690	dependencies.	836	dependencies.
691		837
692	Returns all its arguments.	838	Returns all its arguments.
693		839
		840	=item $grp->cancel_subs
		841
		842	Cancel all subrequests and clears any feeder, but not the group request
		843	itself. Useful when you queued a lot of events but got a result early.
		844
694	=item $grp->result (...)	845	=item $grp->result (...)
695		846
696	Set the result value(s) that will be passed to the group callback when all	847	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.	848	subrequests have finished and set thre groups errno to the current value
		849	of errno (just like calling C<errno> without an error number). By default,
		850	no argument will be passed and errno is zero.
		851
		852	=item $grp->errno ([$errno])
		853
		854	Sets the group errno value to C<$errno>, or the current value of errno
		855	when the argument is missing.
		856
		857	Every aio request has an associated errno value that is restored when
		858	the callback is invoked. This method lets you change this value from its
		859	default (0).
		860
		861	Calling C<result> will also set errno, so make sure you either set C<$!>
		862	before the call to C<result>, or call c<errno> after it.
698		863
699	=item feed $grp $callback->($grp)	864	=item feed $grp $callback->($grp)
700
701	[VERY EXPERIMENTAL]
702		865
703	Sets a feeder/generator on this group: every group can have an attached	866	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,	867	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,	868	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	869	this might starve other requests for a potentially long time. For
…		…
743		906
744	=back	907	=back
745		908
746	=head2 SUPPORT FUNCTIONS	909	=head2 SUPPORT FUNCTIONS
747		910
		911	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		912
748	=over 4	913	=over 4
749		914
750	=item $fileno = IO::AIO::poll_fileno	915	=item $fileno = IO::AIO::poll_fileno
751		916
752	Return the I<request result pipe file descriptor>. This filehandle must be	917	Return the I<request result pipe file descriptor>. This filehandle must be
…		…
756		921
757	See C<poll_cb> for an example.	922	See C<poll_cb> for an example.
758		923
759	=item IO::AIO::poll_cb	924	=item IO::AIO::poll_cb
760		925
761	Process all outstanding events on the result pipe. You have to call this	926	Process some outstanding events on the result pipe. You have to call this
762	regularly. Returns the number of events processed. Returns immediately	927	regularly. Returns the number of events processed. Returns immediately
763	when no events are outstanding.	928	when no events are outstanding. The amount of events processed depends on
		929	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		930
		931	If not all requests were processed for whatever reason, the filehandle
		932	will still be ready when C<poll_cb> returns.
764		933
765	Example: Install an Event watcher that automatically calls	934	Example: Install an Event watcher that automatically calls
766	IO::AIO::poll_cb with high priority:	935	IO::AIO::poll_cb with high priority:
767		936
768	Event->io (fd => IO::AIO::poll_fileno,	937	Event->io (fd => IO::AIO::poll_fileno,
769	poll => 'r', async => 1,	938	poll => 'r', async => 1,
770	cb => \&IO::AIO::poll_cb);	939	cb => \&IO::AIO::poll_cb);
771		940
		941	=item IO::AIO::max_poll_reqs $nreqs
		942
		943	=item IO::AIO::max_poll_time $seconds
		944
		945	These set the maximum number of requests (default C<0>, meaning infinity)
		946	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		947	the maximum amount of time (default C<0>, meaning infinity) spent in
		948	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		949	of time C<poll_cb> is allowed to use).
		950
		951	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		952	syscall per request processed, which is not normally a problem unless your
		953	callbacks are really really fast or your OS is really really slow (I am
		954	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		955
		956	Setting these is useful if you want to ensure some level of
		957	interactiveness when perl is not fast enough to process all requests in
		958	time.
		959
		960	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		961
		962	Example: Install an Event watcher that automatically calls
		963	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		964	program get the CPU sometimes even under high AIO load.
		965
		966	# try not to spend much more than 0.1s in poll_cb
		967	IO::AIO::max_poll_time 0.1;
		968
		969	# use a low priority so other tasks have priority
		970	Event->io (fd => IO::AIO::poll_fileno,
		971	poll => 'r', nice => 1,
		972	cb => &IO::AIO::poll_cb);
		973
772	=item IO::AIO::poll_wait	974	=item IO::AIO::poll_wait
773		975
		976	If there are any outstanding requests and none of them in the result
774	Wait till the result filehandle becomes ready for reading (simply does a	977	phase, wait till the result filehandle becomes ready for reading (simply
775	C<select> on the filehandle. This is useful if you want to synchronously wait	978	does a C<select> on the filehandle. This is useful if you want to
776	for some requests to finish).	979	synchronously wait for some requests to finish).
777		980
778	See C<nreqs> for an example.	981	See C<nreqs> for an example.
779		982
		983	=item IO::AIO::poll
		984
		985	Waits until some requests have been handled.
		986
		987	Returns the number of requests processed, but is otherwise strictly
		988	equivalent to:
		989
		990	IO::AIO::poll_wait, IO::AIO::poll_cb
		991
780	=item IO::AIO::nreqs	992	=item IO::AIO::flush
781		993
782	Returns the number of requests currently outstanding (i.e. for which their	994	Wait till all outstanding AIO requests have been handled.
783	callback has not been invoked yet).
784		995
785	Example: wait till there are no outstanding requests anymore:	996	Strictly equivalent to:
786		997
787	IO::AIO::poll_wait, IO::AIO::poll_cb	998	IO::AIO::poll_wait, IO::AIO::poll_cb
788	while IO::AIO::nreqs;	999	while IO::AIO::nreqs;
789		1000
790	=item IO::AIO::flush	1001	=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		1002
808	=item IO::AIO::min_parallel $nthreads	1003	=item IO::AIO::min_parallel $nthreads
809		1004
810	Set the minimum number of AIO threads to C<$nthreads>. The current	1005	Set the minimum number of AIO threads to C<$nthreads>. The current
811	default is C<8>, which means eight asynchronous operations can execute	1006	default is C<8>, which means eight asynchronous operations can execute
812	concurrently at any one time (the number of outstanding requests,	1007	concurrently at any one time (the number of outstanding requests,
813	however, is unlimited).	1008	however, is unlimited).
814		1009
815	IO::AIO starts threads only on demand, when an AIO request is queued and	1010	IO::AIO starts threads only on demand, when an AIO request is queued and
816	no free thread exists.	1011	no free thread exists. Please note that queueing up a hundred requests can
		1012	create demand for a hundred threads, even if it turns out that everything
		1013	is in the cache and could have been processed faster by a single thread.
817		1014
818	It is recommended to keep the number of threads relatively low, as some	1015	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	1016	Linux kernel versions will scale negatively with the number of threads
820	(higher parallelity => MUCH higher latency). With current Linux 2.6	1017	(higher parallelity => MUCH higher latency). With current Linux 2.6
821	versions, 4-32 threads should be fine.	1018	versions, 4-32 threads should be fine.
…		…
835	This module automatically runs C<max_parallel 0> at program end, to ensure	1032	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.	1033	that all threads are killed and that there are no outstanding requests.
837		1034
838	Under normal circumstances you don't need to call this function.	1035	Under normal circumstances you don't need to call this function.
839		1036
		1037	=item IO::AIO::max_idle $nthreads
		1038
		1039	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1040	threads that did not get a request to process within 10 seconds). That
		1041	means if a thread becomes idle while C<$nthreads> other threads are also
		1042	idle, it will free its resources and exit.
		1043
		1044	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1045	to allow for extremely high load situations, but want to free resources
		1046	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1047
		1048	The default is probably ok in most situations, especially if thread
		1049	creation is fast. If thread creation is very slow on your system you might
		1050	want to use larger values.
		1051
840	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1052	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
841		1053
842	[DEPRECATED]	1054	This is a very bad function to use in interactive programs because it
		1055	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1056	use an C<aio_group> together with a feed callback.
843		1057
844	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1058	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	1059	to queue up more than this number of requests, the next call to the
846	some requests have been handled.	1060	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1061	function will block until the limit is no longer exceeded.
847		1062
848	The default is very large, so normally there is no practical limit. If you	1063	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	1064	number of outstanding requests.
850	this to a relatively low number, such as C<100>.
851		1065
852	This function does not work well together with C<aio_group>'s, and their	1066	You can still queue as many requests as you want. Therefore,
853	feeder interface is better suited to limiting concurrency, so do not use	1067	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
854	this function.	1068	as a stop gap to shield against fatal memory overflow (with large values).
855		1069
856	Under normal circumstances you don't need to call this function.	1070	=head3 STATISTICAL INFORMATION
		1071
		1072	=item IO::AIO::nreqs
		1073
		1074	Returns the number of requests currently in the ready, execute or pending
		1075	states (i.e. for which their callback has not been invoked yet).
		1076
		1077	Example: wait till there are no outstanding requests anymore:
		1078
		1079	IO::AIO::poll_wait, IO::AIO::poll_cb
		1080	while IO::AIO::nreqs;
		1081
		1082	=item IO::AIO::nready
		1083
		1084	Returns the number of requests currently in the ready state (not yet
		1085	executed).
		1086
		1087	=item IO::AIO::npending
		1088
		1089	Returns the number of requests currently in the pending state (executed,
		1090	but not yet processed by poll_cb).
857		1091
858	=back	1092	=back
859		1093
860	=cut	1094	=cut
861		1095
…		…
876	}	1110	}
877		1111
878	min_parallel 8;	1112	min_parallel 8;
879		1113
880	END {	1114	END {
881	max_parallel 0;	1115	min_parallel 1;
882	}	1116	flush;
		1117	};
883		1118
884	1;	1119	1;
885		1120
886	=head2 FORK BEHAVIOUR	1121	=head2 FORK BEHAVIOUR
887		1122
888	This module should do "the right thing" when the process using it forks:	1123	This module should do "the right thing" when the process using it forks:
889		1124
890	Before the fork, IO::AIO enters a quiescent state where no requests	1125	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	1126	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	1127	the fork the parent simply leaves the quiescent state and continues
893	request/result processing, while the child clears the request/result	1128	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	1129	(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	1130	parent). Threads will be started on demand until the limit set in the
896	parent process has been reached again.	1131	parent process has been reached again.
897		1132
898	In short: the parent will, after a short pause, continue as if fork had	1133	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	1134	not been called, while the child will act as if IO::AIO has not been used
900	yet.	1135	yet.
901		1136
902	=head2 MEMORY USAGE	1137	=head2 MEMORY USAGE
903		1138
		1139	Per-request usage:
		1140
904	Each aio request uses - depending on your architecture - around 128 bytes	1141	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	1142	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	1143	a few hundred bytes), readdir requires a result buffer and so on. Perl
907	also be locked.	1144	scalars and other data passed into aio requests will also be locked and
		1145	will consume memory till the request has entered the done state.
908		1146
909	This is now awfully much, so queuing lots of requests is not usually a	1147	This is now awfully much, so queuing lots of requests is not usually a
910	problem.	1148	problem.
911		1149
912	Each thread needs a stack area which is usually around 16k, sometimes much	1150	Per-thread usage:
913	larger, depending on the OS.	1151
		1152	In the execution phase, some aio requests require more memory for
		1153	temporary buffers, and each thread requires a stack and other data
		1154	structures (usually around 16k-128k, depending on the OS).
		1155
		1156	=head1 KNOWN BUGS
		1157
		1158	Known bugs will be fixed in the next release.
914		1159
915	=head1 SEE ALSO	1160	=head1 SEE ALSO
916		1161
917	L<Coro::AIO>.	1162	L<Coro::AIO>.
918		1163

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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 1.93 by root, Wed Nov 8 01:59:58 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 1.93 by root, Wed Nov 8 01:59:58 2006 UTC