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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs.
Revision 1.89 by root, Sun Oct 29 11:03:18 2006 UTC

…		…
18	};	18	};
19		19
20	# version 2+ has request and group objects	20	# version 2+ has request and group objects
21	use IO::AIO 2;	21	use IO::AIO 2;
22		22
		23	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	24	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	25	$req->cancel; # cancel request if still in queue
25		26
26	my $grp = aio_group sub { print "all stats done\n" };	27	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	28	add $grp aio_stat "..." for ...;
…		…
50	=head1 DESCRIPTION	51	=head1 DESCRIPTION
51		52
52	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
53	operating system supports.	54	operating system supports.
54		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
55	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
56	and signal their completion. You don't need thread support in your libc or	73	requests and signal their completion. You don't need thread support
57	perl, and the threads created by this module will not be visible to the	74	in perl, and the threads created by this module will not be visible
58	pthreads library. In the future, this module might make use of the native	75	to perl. In the future, this module might make use of the native aio
59	aio functions available on many operating systems. However, they are often	76	functions available on many operating systems. However, they are often
60	not well-supported (Linux doesn't allow them on normal files currently,	77	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	for example), and they would only support aio_read and aio_write, so the	78	files currently, for example), and they would only support aio_read and
62	remaining 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.
63		81
64	Although the module will work with in the presence of other threads, it is	82	Although the module will work with in the presence of other (Perl-)
65	currently not reentrant, so use appropriate locking yourself, always call	83	threads, it is currently not reentrant in any way, so use appropriate
66	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	84	locking yourself, always call C<poll_cb> from within the same thread, or
67	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).
		180
		181	=back
68		182
69	=cut	183	=cut
70		184
71	package IO::AIO;	185	package IO::AIO;
72		186
…		…
74	use strict 'vars';	188	use strict 'vars';
75		189
76	use base 'Exporter';	190	use base 'Exporter';
77		191
78	BEGIN {	192	BEGIN {
79	our $VERSION = '2.0';	193	our $VERSION = '2.1';
80		194
81	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	195	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
82	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	196	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
83	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	197	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
84	aio_group);	198	aio_copy aio_group aio_nop aio_mknod);
85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	199	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		200	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		201	min_parallel max_parallel max_idle
		202	nreqs nready npending nthreads
		203	max_poll_time max_poll_reqs);
86		204
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	205	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		206
89	require XSLoader;	207	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	208	XSLoader::load ("IO::AIO", $VERSION);
91	}	209	}
92		210
93	=head1 FUNCTIONS	211	=head1 FUNCTIONS
94		212
95	=head2 AIO FUNCTIONS	213	=head2 AIO REQUEST FUNCTIONS
96		214
97	All the C<aio_*> calls are more or less thin wrappers around the syscall	215	All the C<aio_*> calls are more or less thin wrappers around the syscall
98	with the same name (sans C<aio_>). The arguments are similar or identical,	216	with the same name (sans C<aio_>). The arguments are similar or identical,
99	and they all accept an additional (and optional) C<$callback> argument	217	and they all accept an additional (and optional) C<$callback> argument
100	which must be a code reference. This code reference will get called with	218	which must be a code reference. This code reference will get called with
…		…
103	syscall has been executed asynchronously.	221	syscall has been executed asynchronously.
104		222
105	All functions expecting a filehandle keep a copy of the filehandle	223	All functions expecting a filehandle keep a copy of the filehandle
106	internally until the request has finished.	224	internally until the request has finished.
107		225
108	All requests return objects of type L<IO::AIO::REQ> that allow further	226	All functions return request objects of type L<IO::AIO::REQ> that allow
109	manipulation of those requests while they are in-flight.	227	further manipulation of those requests while they are in-flight.
110		228
111	The pathnames you pass to these routines I<must> be absolute and	229	The pathnames you pass to these routines I<must> be absolute and
112	encoded in byte form. The reason for the former is that at the time the	230	encoded as octets. The reason for the former is that at the time the
113	request is being executed, the current working directory could have	231	request is being executed, the current working directory could have
114	changed. Alternatively, you can make sure that you never change the	232	changed. Alternatively, you can make sure that you never change the
115	current working directory.	233	current working directory anywhere in the program and then use relative
		234	paths.
116		235
117	To encode pathnames to byte form, either make sure you either: a)	236	To encode pathnames as octets, either make sure you either: a) always pass
118	always pass in filenames you got from outside (command line, readdir	237	in filenames you got from outside (command line, readdir etc.) without
119	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	238	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
120	your pathnames to the locale (or other) encoding in effect in the user	239	your pathnames to the locale (or other) encoding in effect in the user
121	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	240	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
122	use something else.	241	use something else to ensure your scalar has the correct contents.
		242
		243	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		244	handles correctly wether it is set or not.
123		245
124	=over 4	246	=over 4
		247
		248	=item $prev_pri = aioreq_pri [$pri]
		249
		250	Returns the priority value that would be used for the next request and, if
		251	C<$pri> is given, sets the priority for the next aio request.
		252
		253	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		254	and C<4>, respectively. Requests with higher priority will be serviced
		255	first.
		256
		257	The priority will be reset to C<0> after each call to one of the C<aio_*>
		258	functions.
		259
		260	Example: open a file with low priority, then read something from it with
		261	higher priority so the read request is serviced before other low priority
		262	open requests (potentially spamming the cache):
		263
		264	aioreq_pri -3;
		265	aio_open ..., sub {
		266	return unless $_[0];
		267
		268	aioreq_pri -2;
		269	aio_read $_[0], ..., sub {
		270	...
		271	};
		272	};
		273
		274	=item aioreq_nice $pri_adjust
		275
		276	Similar to C<aioreq_pri>, but subtracts the given value from the current
		277	priority, so the effect is cumulative.
125		278
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	279	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		280
128	Asynchronously open or create a file and call the callback with a newly	281	Asynchronously open or create a file and call the callback with a newly
129	created filehandle for the file.	282	created filehandle for the file.
…		…
179		332
180	aio_read $fh, 7, 15, $buffer, 0, sub {	333	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	334	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	335	print "read $_[0] bytes: <$buffer>\n";
183	};	336	};
184
185	=item aio_move $srcpath, $dstpath, $callback->($status)
186
187	Try to move the I<file> (directories not supported as either source or
188	destination) from C<$srcpath> to C<$dstpath> and call the callback with
189	the C<0> (error) or C<-1> ok.
190
191	This is a composite request that tries to rename(2) the file first. If
192	rename files with C<EXDEV>, it creates the destination file with mode 0200
193	and copies the contents of the source file into it using C<aio_sendfile>,
194	followed by restoring atime, mtime, access mode and uid/gid, in that
195	order, and unlinking the C<$srcpath>.
196
197	If an error occurs, the partial destination file will be unlinked, if
198	possible, except when setting atime, mtime, access mode and uid/gid, where
199	errors are being ignored.
200
201	=cut
202
203	sub aio_move($$$) {
204	my ($src, $dst, $cb) = @_;
205
206	my $grp = aio_group;
207
208	add $grp aio_rename $src, $dst, sub {
209	if ($_[0] && $! == EXDEV) {
210	add $grp aio_open $src, O_RDONLY, 0, sub {
211	if (my $src_fh = $_[0]) {
212	my @stat = stat $src_fh;
213
214	add $grp aio_open $dst, O_WRONLY, 0200, sub {
215	if (my $dst_fh = $_[0]) {
216	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
217	close $src_fh;
218
219	if ($_[0] == $stat[7]) {
220	utime $stat[8], $stat[9], $dst;
221	chmod $stat[2] & 07777, $dst_fh;
222	chown $stat[4], $stat[5], $dst_fh;
223	close $dst_fh;
224
225	add $grp aio_unlink $src, sub {
226	$cb->($_[0]);
227	};
228	} else {
229	my $errno = $!;
230	add $grp aio_unlink $dst, sub {
231	$! = $errno;
232	$cb->(-1);
233	};
234	}
235	};
236	} else {
237	$cb->(-1);
238	}
239	},
240
241	} else {
242	$cb->(-1);
243	}
244	};
245	} else {
246	$cb->($_[0]);
247	}
248	};
249
250	$grp
251	}
252		337
253	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	338	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
254		339
255	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	340	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
256	reading at byte offset C<$in_offset>, and starts writing at the current	341	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
312	=item aio_unlink $pathname, $callback->($status)	397	=item aio_unlink $pathname, $callback->($status)
313		398
314	Asynchronously unlink (delete) a file and call the callback with the	399	Asynchronously unlink (delete) a file and call the callback with the
315	result code.	400	result code.
316		401
		402	=item aio_mknod $path, $mode, $dev, $callback->($status)
		403
		404	[EXPERIMENTAL]
		405
		406	Asynchronously create a device node (or fifo). See mknod(2).
		407
		408	The only (POSIX-) portable way of calling this function is:
		409
		410	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		411
317	=item aio_link $srcpath, $dstpath, $callback->($status)	412	=item aio_link $srcpath, $dstpath, $callback->($status)
318		413
319	Asynchronously create a new link to the existing object at C<$srcpath> at	414	Asynchronously create a new link to the existing object at C<$srcpath> at
320	the path C<$dstpath> and call the callback with the result code.	415	the path C<$dstpath> and call the callback with the result code.
321		416
…		…
341	sorted, and will B<NOT> include the C<.> and C<..> entries.	436	sorted, and will B<NOT> include the C<.> and C<..> entries.
342		437
343	The callback a single argument which is either C<undef> or an array-ref	438	The callback a single argument which is either C<undef> or an array-ref
344	with the filenames.	439	with the filenames.
345		440
		441	=item aio_copy $srcpath, $dstpath, $callback->($status)
		442
		443	Try to copy the I<file> (directories not supported as either source or
		444	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		445	the C<0> (error) or C<-1> ok.
		446
		447	This is a composite request that it creates the destination file with
		448	mode 0200 and copies the contents of the source file into it using
		449	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		450	uid/gid, in that order.
		451
		452	If an error occurs, the partial destination file will be unlinked, if
		453	possible, except when setting atime, mtime, access mode and uid/gid, where
		454	errors are being ignored.
		455
		456	=cut
		457
		458	sub aio_copy($$;$) {
		459	my ($src, $dst, $cb) = @_;
		460
		461	my $pri = aioreq_pri;
		462	my $grp = aio_group $cb;
		463
		464	aioreq_pri $pri;
		465	add $grp aio_open $src, O_RDONLY, 0, sub {
		466	if (my $src_fh = $_[0]) {
		467	my @stat = stat $src_fh;
		468
		469	aioreq_pri $pri;
		470	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		471	if (my $dst_fh = $_[0]) {
		472	aioreq_pri $pri;
		473	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		474	if ($_[0] == $stat[7]) {
		475	$grp->result (0);
		476	close $src_fh;
		477
		478	# those should not normally block. should. should.
		479	utime $stat[8], $stat[9], $dst;
		480	chmod $stat[2] & 07777, $dst_fh;
		481	chown $stat[4], $stat[5], $dst_fh;
		482	close $dst_fh;
		483	} else {
		484	$grp->result (-1);
		485	close $src_fh;
		486	close $dst_fh;
		487
		488	aioreq $pri;
		489	add $grp aio_unlink $dst;
		490	}
		491	};
		492	} else {
		493	$grp->result (-1);
		494	}
		495	},
		496
		497	} else {
		498	$grp->result (-1);
		499	}
		500	};
		501
		502	$grp
		503	}
		504
		505	=item aio_move $srcpath, $dstpath, $callback->($status)
		506
		507	Try to move the I<file> (directories not supported as either source or
		508	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		509	the C<0> (error) or C<-1> ok.
		510
		511	This is a composite request that tries to rename(2) the file first. If
		512	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		513	that is successful, unlinking the C<$srcpath>.
		514
		515	=cut
		516
		517	sub aio_move($$;$) {
		518	my ($src, $dst, $cb) = @_;
		519
		520	my $pri = aioreq_pri;
		521	my $grp = aio_group $cb;
		522
		523	aioreq_pri $pri;
		524	add $grp aio_rename $src, $dst, sub {
		525	if ($_[0] && $! == EXDEV) {
		526	aioreq_pri $pri;
		527	add $grp aio_copy $src, $dst, sub {
		528	$grp->result ($_[0]);
		529
		530	if (!$_[0]) {
		531	aioreq_pri $pri;
		532	add $grp aio_unlink $src;
		533	}
		534	};
		535	} else {
		536	$grp->result ($_[0]);
		537	}
		538	};
		539
		540	$grp
		541	}
		542
346	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	543	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
347		544
348	Scans a directory (similar to C<aio_readdir>) but additionally tries to	545	Scans a directory (similar to C<aio_readdir>) but additionally tries to
349	separate the entries of directory C<$path> into two sets of names, ones	546	efficiently separate the entries of directory C<$path> into two sets of
350	you can recurse into (directories or links to them), and ones you cannot	547	names, directories you can recurse into (directories), and ones you cannot
351	recurse into (everything else).	548	recurse into (everything else, including symlinks to directories).
352		549
353	C<aio_scandir> is a composite request that consists of many sub	550	C<aio_scandir> is a composite request that creates of many sub requests_
354	requests. C<$maxreq> specifies the maximum number of outstanding aio	551	C<$maxreq> specifies the maximum number of outstanding aio requests that
355	requests that this function generates. If it is C<< <= 0 >>, then a	552	this function generates. If it is C<< <= 0 >>, then a suitable default
356	suitable default will be chosen (currently 8).	553	will be chosen (currently 4).
357		554
358	On error, the callback is called without arguments, otherwise it receives	555	On error, the callback is called without arguments, otherwise it receives
359	two array-refs with path-relative entry names.	556	two array-refs with path-relative entry names.
360		557
361	Example:	558	Example:
…		…
398	=cut	595	=cut
399		596
400	sub aio_scandir($$$) {	597	sub aio_scandir($$$) {
401	my ($path, $maxreq, $cb) = @_;	598	my ($path, $maxreq, $cb) = @_;
402		599
		600	my $pri = aioreq_pri;
		601
403	my $grp = aio_group;	602	my $grp = aio_group $cb;
404		603
405	$maxreq = 8 if $maxreq <= 0;	604	$maxreq = 4 if $maxreq <= 0;
406		605
407	# stat once	606	# stat once
		607	aioreq_pri $pri;
408	add $grp aio_stat $path, sub {	608	add $grp aio_stat $path, sub {
409	return $cb->() if $_[0];	609	return $grp->result () if $_[0];
410	my $now = time;	610	my $now = time;
411	my $hash1 = join ":", (stat _)[0,1,3,7,9];	611	my $hash1 = join ":", (stat _)[0,1,3,7,9];
412		612
413	# read the directory entries	613	# read the directory entries
		614	aioreq_pri $pri;
414	add $grp aio_readdir $path, sub {	615	add $grp aio_readdir $path, sub {
415	my $entries = shift	616	my $entries = shift
416	or return $cb->();	617	or return $grp->result ();
417		618
418	# stat the dir another time	619	# stat the dir another time
		620	aioreq_pri $pri;
419	add $grp aio_stat $path, sub {	621	add $grp aio_stat $path, sub {
420	my $hash2 = join ":", (stat _)[0,1,3,7,9];	622	my $hash2 = join ":", (stat _)[0,1,3,7,9];
421		623
422	my $ndirs;	624	my $ndirs;
423		625
…		…
426	$ndirs = -1;	628	$ndirs = -1;
427	} else {	629	} else {
428	# if nlink == 2, we are finished	630	# if nlink == 2, we are finished
429	# on non-posix-fs's, we rely on nlink < 2	631	# on non-posix-fs's, we rely on nlink < 2
430	$ndirs = (stat _)[3] - 2	632	$ndirs = (stat _)[3] - 2
431	or return $cb->([], $entries);	633	or return $grp->result ([], $entries);
432	}	634	}
433		635
434	# sort into likely dirs and likely nondirs	636	# sort into likely dirs and likely nondirs
435	# dirs == files without ".", short entries first	637	# dirs == files without ".", short entries first
436	$entries = [map $_->[0],	638	$entries = [map $_->[0],
…		…
438	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	640	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
439	@$entries];	641	@$entries];
440		642
441	my (@dirs, @nondirs);	643	my (@dirs, @nondirs);
442		644
443	my ($statcb, $schedcb);	645	my $statgrp = add $grp aio_group sub {
444	my $nreq = 0;	646	$grp->result (\@dirs, \@nondirs);
		647	};
445		648
446	$schedcb = sub {	649	limit $statgrp $maxreq;
447	if (@$entries) {	650	feed $statgrp sub {
448	if ($nreq < $maxreq) {	651	return unless @$entries;
449	my $ent = pop @$entries;	652	my $entry = pop @$entries;
		653
		654	aioreq_pri $pri;
		655	add $statgrp aio_stat "$path/$entry/.", sub {
		656	if ($_[0] < 0) {
		657	push @nondirs, $entry;
		658	} else {
		659	# need to check for real directory
		660	aioreq_pri $pri;
		661	add $statgrp aio_lstat "$path/$entry", sub {
		662	if (-d _) {
		663	push @dirs, $entry;
		664
		665	unless (--$ndirs) {
		666	push @nondirs, @$entries;
		667	feed $statgrp;
		668	}
		669	} else {
		670	push @nondirs, $entry;
		671	}
450	$nreq++;	672	}
451	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
452	}	673	}
453	} elsif (!$nreq) {
454	# finished
455	undef $statcb;
456	undef $schedcb;
457	$cb->(\@dirs, \@nondirs) if $cb;
458	undef $cb;
459	}	674	};
460	};	675	};
461	$statcb = sub {
462	my ($status, $entry) = @_;
463
464	if ($status < 0) {
465	$nreq--;
466	push @nondirs, $entry;
467	&$schedcb;
468	} else {
469	# need to check for real directory
470	add $grp aio_lstat "$path/$entry", sub {
471	$nreq--;
472
473	if (-d _) {
474	push @dirs, $entry;
475
476	if (!--$ndirs) {
477	push @nondirs, @$entries;
478	$entries = [];
479	}
480	} else {
481	push @nondirs, $entry;
482	}
483
484	&$schedcb;
485	}
486	}
487	};
488
489	&$schedcb while @$entries && $nreq < $maxreq;
490	};	676	};
491	};	677	};
492	};	678	};
493		679
494	$grp	680	$grp
…		…
505	callback with the fdatasync result code.	691	callback with the fdatasync result code.
506		692
507	If this call isn't available because your OS lacks it or it couldn't be	693	If this call isn't available because your OS lacks it or it couldn't be
508	detected, it will be emulated by calling C<fsync> instead.	694	detected, it will be emulated by calling C<fsync> instead.
509		695
510	=item aio_group $callback->()	696	=item aio_group $callback->(...)
511
512	[EXPERIMENTAL]
513		697
514	This is a very special aio request: Instead of doing something, it is a	698	This is a very special aio request: Instead of doing something, it is a
515	container for other aio requests, which is useful if you want to bundle	699	container for other aio requests, which is useful if you want to bundle
516	many requests into a single, composite, request.	700	many requests into a single, composite, request with a definite callback
		701	and the ability to cancel the whole request with its subrequests.
517		702
518	Returns an object of class L<IO::AIO::GRP>. See its documentation below	703	Returns an object of class L<IO::AIO::GRP>. See its documentation below
519	for more info.	704	for more info.
520		705
521	Example:	706	Example:
…		…
527	add $grp	712	add $grp
528	(aio_stat ...),	713	(aio_stat ...),
529	(aio_stat ...),	714	(aio_stat ...),
530	...;	715	...;
531		716
		717	=item aio_nop $callback->()
		718
		719	This is a special request - it does nothing in itself and is only used for
		720	side effects, such as when you want to add a dummy request to a group so
		721	that finishing the requests in the group depends on executing the given
		722	code.
		723
		724	While this request does nothing, it still goes through the execution
		725	phase and still requires a worker thread. Thus, the callback will not
		726	be executed immediately but only after other requests in the queue have
		727	entered their execution phase. This can be used to measure request
		728	latency.
		729
532	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	730	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
533		731
534	Mainly used for debugging and benchmarking, this aio request puts one of	732	Mainly used for debugging and benchmarking, this aio request puts one of
535	the request workers to sleep for the given time.	733	the request workers to sleep for the given time.
536		734
537	While it is theoretically handy to have simple I/O scheduling requests	735	While it is theoretically handy to have simple I/O scheduling requests
538	like sleep and file handle readable/writable, the overhead this creates	736	like sleep and file handle readable/writable, the overhead this creates is
539	is immense, so do not use this function except to put your application	737	immense (it blocks a thread for a long time) so do not use this function
540	under artificial I/O pressure.	738	except to put your application under artificial I/O pressure.
541		739
542	=back	740	=back
543		741
544	=head2 IO::AIO::REQ CLASS	742	=head2 IO::AIO::REQ CLASS
545		743
546	All non-aggregate C<aio_*> functions return an object of this class when	744	All non-aggregate C<aio_*> functions return an object of this class when
547	called in non-void context.	745	called in non-void context.
548		746
549	A request always moves through the following five states in its lifetime,
550	in order: B<ready> (request has been created, but has not been executed
551	yet), B<execute> (request is currently being executed), B<pending>
552	(request has been executed but callback has not been called yet),
553	B<result> (results are being processed synchronously, includes calling the
554	callback) and B<done> (request has reached the end of its lifetime and
555	holds no resources anymore).
556
557	=over 4	747	=over 4
558		748
559	=item $req->cancel	749	=item cancel $req
560		750
561	Cancels the request, if possible. Has the effect of skipping execution	751	Cancels the request, if possible. Has the effect of skipping execution
562	when entering the B<execute> state and skipping calling the callback when	752	when entering the B<execute> state and skipping calling the callback when
563	entering the the B<result> state, but will leave the request otherwise	753	entering the the B<result> state, but will leave the request otherwise
564	untouched. That means that requests that currently execute will not be	754	untouched. That means that requests that currently execute will not be
565	stopped and resources held by the request will not be freed prematurely.	755	stopped and resources held by the request will not be freed prematurely.
566		756
		757	=item cb $req $callback->(...)
		758
		759	Replace (or simply set) the callback registered to the request.
		760
567	=back	761	=back
568		762
569	=head2 IO::AIO::GRP CLASS	763	=head2 IO::AIO::GRP CLASS
570		764
571	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	765	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
585	You add requests by calling the C<add> method with one or more	779	You add requests by calling the C<add> method with one or more
586	C<IO::AIO::REQ> objects:	780	C<IO::AIO::REQ> objects:
587		781
588	$grp->add (aio_unlink "...");	782	$grp->add (aio_unlink "...");
589		783
590	add $grp aio_stat "...", sub { ... };	784	add $grp aio_stat "...", sub {
		785	$_[0] or return $grp->result ("error");
		786
		787	# add another request dynamically, if first succeeded
		788	add $grp aio_open "...", sub {
		789	$grp->result ("ok");
		790	};
		791	};
591		792
592	This makes it very easy to create composite requests (see the source of	793	This makes it very easy to create composite requests (see the source of
593	C<aio_move> for an application) that work and feel like simple requests.	794	C<aio_move> for an application) that work and feel like simple requests.
594		795
		796	=over 4
		797
595	The IO::AIO::GRP objects will be cleaned up during calls to	798	=item * The IO::AIO::GRP objects will be cleaned up during calls to
596	C<IO::AIO::poll_cb>, just like any other request.	799	C<IO::AIO::poll_cb>, just like any other request.
597		800
598	They can be canceled like any other request. Canceling will cancel not	801	=item * They can be canceled like any other request. Canceling will cancel not
599	just the request itself, but also all requests it contains.	802	only the request itself, but also all requests it contains.
600		803
601	They can also can also be added to other IO::AIO::GRP objects.	804	=item * They can also can also be added to other IO::AIO::GRP objects.
		805
		806	=item * You must not add requests to a group from within the group callback (or
		807	any later time).
		808
		809	=back
602		810
603	Their lifetime, simplified, looks like this: when they are empty, they	811	Their lifetime, simplified, looks like this: when they are empty, they
604	will finish very quickly. If they contain only requests that are in the	812	will finish very quickly. If they contain only requests that are in the
605	C<done> state, they will also finish. Otherwise they will continue to	813	C<done> state, they will also finish. Otherwise they will continue to
606	exist.	814	exist.
607		815
		816	That means after creating a group you have some time to add requests. And
		817	in the callbacks of those requests, you can add further requests to the
		818	group. And only when all those requests have finished will the the group
		819	itself finish.
		820
608	=over 4	821	=over 4
609		822
		823	=item add $grp ...
		824
610	=item $grp->add (...)	825	=item $grp->add (...)
611		826
612	=item add $grp ...	827	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		828	be added, including other groups, as long as you do not create circular
		829	dependencies.
613		830
614	Add one or more	831	Returns all its arguments.
615	Cancels the request, if possible. Has the effect of skipping execution	832
616	when entering the B<execute> state and skipping calling the callback when	833	=item $grp->cancel_subs
617	entering the the B<result> state, but will leave the request otherwise	834
618	untouched. That means that requests that currently execute will not be	835	Cancel all subrequests and clears any feeder, but not the group request
619	stopped and resources held by the request will not be freed prematurely.	836	itself. Useful when you queued a lot of events but got a result early.
		837
		838	=item $grp->result (...)
		839
		840	Set the result value(s) that will be passed to the group callback when all
		841	subrequests have finished and set thre groups errno to the current value
		842	of errno (just like calling C<errno> without an error number). By default,
		843	no argument will be passed and errno is zero.
		844
		845	=item $grp->errno ([$errno])
		846
		847	Sets the group errno value to C<$errno>, or the current value of errno
		848	when the argument is missing.
		849
		850	Every aio request has an associated errno value that is restored when
		851	the callback is invoked. This method lets you change this value from its
		852	default (0).
		853
		854	Calling C<result> will also set errno, so make sure you either set C<$!>
		855	before the call to C<result>, or call c<errno> after it.
		856
		857	=item feed $grp $callback->($grp)
		858
		859	Sets a feeder/generator on this group: every group can have an attached
		860	generator that generates requests if idle. The idea behind this is that,
		861	although you could just queue as many requests as you want in a group,
		862	this might starve other requests for a potentially long time. For
		863	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		864	requests, delaying any later requests for a long time.
		865
		866	To avoid this, and allow incremental generation of requests, you can
		867	instead a group and set a feeder on it that generates those requests. The
		868	feed callback will be called whenever there are few enough (see C<limit>,
		869	below) requests active in the group itself and is expected to queue more
		870	requests.
		871
		872	The feed callback can queue as many requests as it likes (i.e. C<add> does
		873	not impose any limits).
		874
		875	If the feed does not queue more requests when called, it will be
		876	automatically removed from the group.
		877
		878	If the feed limit is C<0>, it will be set to C<2> automatically.
		879
		880	Example:
		881
		882	# stat all files in @files, but only ever use four aio requests concurrently:
		883
		884	my $grp = aio_group sub { print "finished\n" };
		885	limit $grp 4;
		886	feed $grp sub {
		887	my $file = pop @files
		888	or return;
		889
		890	add $grp aio_stat $file, sub { ... };
		891	};
		892
		893	=item limit $grp $num
		894
		895	Sets the feeder limit for the group: The feeder will be called whenever
		896	the group contains less than this many requests.
		897
		898	Setting the limit to C<0> will pause the feeding process.
620		899
621	=back	900	=back
622		901
623	=head2 SUPPORT FUNCTIONS	902	=head2 SUPPORT FUNCTIONS
		903
		904	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
624		905
625	=over 4	906	=over 4
626		907
627	=item $fileno = IO::AIO::poll_fileno	908	=item $fileno = IO::AIO::poll_fileno
628		909
…		…
633		914
634	See C<poll_cb> for an example.	915	See C<poll_cb> for an example.
635		916
636	=item IO::AIO::poll_cb	917	=item IO::AIO::poll_cb
637		918
638	Process all outstanding events on the result pipe. You have to call this	919	Process some outstanding events on the result pipe. You have to call this
639	regularly. Returns the number of events processed. Returns immediately	920	regularly. Returns the number of events processed. Returns immediately
640	when no events are outstanding.	921	when no events are outstanding. The amount of events processed depends on
		922	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		923
		924	If not all requests were processed for whatever reason, the filehandle
		925	will still be ready when C<poll_cb> returns.
641		926
642	Example: Install an Event watcher that automatically calls	927	Example: Install an Event watcher that automatically calls
643	IO::AIO::poll_cb with high priority:	928	IO::AIO::poll_cb with high priority:
644		929
645	Event->io (fd => IO::AIO::poll_fileno,	930	Event->io (fd => IO::AIO::poll_fileno,
646	poll => 'r', async => 1,	931	poll => 'r', async => 1,
647	cb => \&IO::AIO::poll_cb);	932	cb => \&IO::AIO::poll_cb);
648		933
		934	=item IO::AIO::max_poll_reqs $nreqs
		935
		936	=item IO::AIO::max_poll_time $seconds
		937
		938	These set the maximum number of requests (default C<0>, meaning infinity)
		939	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		940	the maximum amount of time (default C<0>, meaning infinity) spent in
		941	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		942	of time C<poll_cb> is allowed to use).
		943
		944	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		945	syscall per request processed, which is not normally a problem unless your
		946	callbacks are really really fast or your OS is really really slow (I am
		947	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		948
		949	Setting these is useful if you want to ensure some level of
		950	interactiveness when perl is not fast enough to process all requests in
		951	time.
		952
		953	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		954
		955	Example: Install an Event watcher that automatically calls
		956	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		957	program get the CPU sometimes even under high AIO load.
		958
		959	# try not to spend much more than 0.1s in poll_cb
		960	IO::AIO::max_poll_time 0.1;
		961
		962	# use a low priority so other tasks have priority
		963	Event->io (fd => IO::AIO::poll_fileno,
		964	poll => 'r', nice => 1,
		965	cb => &IO::AIO::poll_cb);
		966
649	=item IO::AIO::poll_wait	967	=item IO::AIO::poll_wait
650		968
651	Wait till the result filehandle becomes ready for reading (simply does a	969	Wait till the result filehandle becomes ready for reading (simply does a
652	C<select> on the filehandle. This is useful if you want to synchronously wait	970	C<select> on the filehandle. This is useful if you want to synchronously
653	for some requests to finish).	971	wait for some requests to finish).
654		972
655	See C<nreqs> for an example.	973	See C<nreqs> for an example.
656		974
		975	=item IO::AIO::poll
		976
		977	Waits until some requests have been handled.
		978
		979	Strictly equivalent to:
		980
		981	IO::AIO::poll_wait, IO::AIO::poll_cb
		982	if IO::AIO::nreqs;
		983
657	=item IO::AIO::nreqs	984	=item IO::AIO::flush
658		985
659	Returns the number of requests currently outstanding (i.e. for which their	986	Wait till all outstanding AIO requests have been handled.
660	callback has not been invoked yet).
661		987
662	Example: wait till there are no outstanding requests anymore:	988	Strictly equivalent to:
663		989
664	IO::AIO::poll_wait, IO::AIO::poll_cb	990	IO::AIO::poll_wait, IO::AIO::poll_cb
665	while IO::AIO::nreqs;	991	while IO::AIO::nreqs;
666		992
667	=item IO::AIO::flush	993	=head3 CONTROLLING THE NUMBER OF THREADS
668
669	Wait till all outstanding AIO requests have been handled.
670
671	Strictly equivalent to:
672
673	IO::AIO::poll_wait, IO::AIO::poll_cb
674	while IO::AIO::nreqs;
675
676	=item IO::AIO::poll
677
678	Waits until some requests have been handled.
679
680	Strictly equivalent to:
681
682	IO::AIO::poll_wait, IO::AIO::poll_cb
683	if IO::AIO::nreqs;
684		994
685	=item IO::AIO::min_parallel $nthreads	995	=item IO::AIO::min_parallel $nthreads
686		996
687	Set the minimum number of AIO threads to C<$nthreads>. The current default	997	Set the minimum number of AIO threads to C<$nthreads>. The current
688	is C<4>, which means four asynchronous operations can be done at one time	998	default is C<8>, which means eight asynchronous operations can execute
689	(the number of outstanding operations, however, is unlimited).	999	concurrently at any one time (the number of outstanding requests,
		1000	however, is unlimited).
690		1001
691	IO::AIO starts threads only on demand, when an AIO request is queued and	1002	IO::AIO starts threads only on demand, when an AIO request is queued and
692	no free thread exists.	1003	no free thread exists. Please note that queueing up a hundred requests can
		1004	create demand for a hundred threads, even if it turns out that everything
		1005	is in the cache and could have been processed faster by a single thread.
693		1006
694	It is recommended to keep the number of threads low, as some Linux	1007	It is recommended to keep the number of threads relatively low, as some
695	kernel versions will scale negatively with the number of threads (higher	1008	Linux kernel versions will scale negatively with the number of threads
696	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1009	(higher parallelity => MUCH higher latency). With current Linux 2.6
697	threads should be fine.	1010	versions, 4-32 threads should be fine.
698		1011
699	Under most circumstances you don't need to call this function, as the	1012	Under most circumstances you don't need to call this function, as the
700	module selects a default that is suitable for low to moderate load.	1013	module selects a default that is suitable for low to moderate load.
701		1014
702	=item IO::AIO::max_parallel $nthreads	1015	=item IO::AIO::max_parallel $nthreads
…		…
711	This module automatically runs C<max_parallel 0> at program end, to ensure	1024	This module automatically runs C<max_parallel 0> at program end, to ensure
712	that all threads are killed and that there are no outstanding requests.	1025	that all threads are killed and that there are no outstanding requests.
713		1026
714	Under normal circumstances you don't need to call this function.	1027	Under normal circumstances you don't need to call this function.
715		1028
		1029	=item IO::AIO::max_idle $nthreads
		1030
		1031	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1032	threads that did not get a request to process within 10 seconds). That
		1033	means if a thread becomes idle while C<$nthreads> other threads are also
		1034	idle, it will free its resources and exit.
		1035
		1036	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1037	to allow for extremely high load situations, but want to free resources
		1038	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1039
		1040	The default is probably ok in most situations, especially if thread
		1041	creation is fast. If thread creation is very slow on your system you might
		1042	want to use larger values.
		1043
716	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1044	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1045
		1046	This is a very bad function to use in interactive programs because it
		1047	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1048	use an C<aio_group> together with a feed callback.
717		1049
718	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1050	Sets the maximum number of outstanding requests to C<$nreqs>. If you
719	try to queue up more than this number of requests, the caller will block until	1051	to queue up more than this number of requests, the next call to the
720	some requests have been handled.	1052	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1053	function will block until the limit is no longer exceeded.
721		1054
722	The default is very large, so normally there is no practical limit. If you	1055	The default value is very large, so there is no practical limit on the
723	queue up many requests in a loop it often improves speed if you set	1056	number of outstanding requests.
724	this to a relatively low number, such as C<100>.
725		1057
726	Under normal circumstances you don't need to call this function.	1058	You can still queue as many requests as you want. Therefore,
		1059	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1060	as a stop gap to shield against fatal memory overflow (with large values).
		1061
		1062	=head3 STATISTICAL INFORMATION
		1063
		1064	=item IO::AIO::nreqs
		1065
		1066	Returns the number of requests currently in the ready, execute or pending
		1067	states (i.e. for which their callback has not been invoked yet).
		1068
		1069	Example: wait till there are no outstanding requests anymore:
		1070
		1071	IO::AIO::poll_wait, IO::AIO::poll_cb
		1072	while IO::AIO::nreqs;
		1073
		1074	=item IO::AIO::nready
		1075
		1076	Returns the number of requests currently in the ready state (not yet
		1077	executed).
		1078
		1079	=item IO::AIO::npending
		1080
		1081	Returns the number of requests currently in the pending state (executed,
		1082	but not yet processed by poll_cb).
727		1083
728	=back	1084	=back
729		1085
730	=cut	1086	=cut
731		1087
…		…
743	or return undef;	1099	or return undef;
744		1100
745	*$sym	1101	*$sym
746	}	1102	}
747		1103
748	min_parallel 4;	1104	min_parallel 8;
749		1105
750	END {	1106	END {
751	max_parallel 0;	1107	min_parallel 1;
752	}	1108	flush;
		1109	};
753		1110
754	1;	1111	1;
755		1112
756	=head2 FORK BEHAVIOUR	1113	=head2 FORK BEHAVIOUR
757		1114
758	This module should do "the right thing" when the process using it forks:	1115	This module should do "the right thing" when the process using it forks:
759		1116
760	Before the fork, IO::AIO enters a quiescent state where no requests	1117	Before the fork, IO::AIO enters a quiescent state where no requests
761	can be added in other threads and no results will be processed. After	1118	can be added in other threads and no results will be processed. After
762	the fork the parent simply leaves the quiescent state and continues	1119	the fork the parent simply leaves the quiescent state and continues
763	request/result processing, while the child clears the request/result	1120	request/result processing, while the child frees the request/result queue
764	queue (so the requests started before the fork will only be handled in	1121	(so that the requests started before the fork will only be handled in the
765	the parent). Threads will be started on demand until the limit ste in the	1122	parent). Threads will be started on demand until the limit set in the
766	parent process has been reached again.	1123	parent process has been reached again.
767		1124
768	In short: the parent will, after a short pause, continue as if fork had	1125	In short: the parent will, after a short pause, continue as if fork had
769	not been called, while the child will act as if IO::AIO has not been used	1126	not been called, while the child will act as if IO::AIO has not been used
770	yet.	1127	yet.
771		1128
		1129	=head2 MEMORY USAGE
		1130
		1131	Per-request usage:
		1132
		1133	Each aio request uses - depending on your architecture - around 100-200
		1134	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1135	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1136	scalars and other data passed into aio requests will also be locked and
		1137	will consume memory till the request has entered the done state.
		1138
		1139	This is now awfully much, so queuing lots of requests is not usually a
		1140	problem.
		1141
		1142	Per-thread usage:
		1143
		1144	In the execution phase, some aio requests require more memory for
		1145	temporary buffers, and each thread requires a stack and other data
		1146	structures (usually around 16k-128k, depending on the OS).
		1147
		1148	=head1 KNOWN BUGS
		1149
		1150	Known bugs will be fixed in the next release.
		1151
772	=head1 SEE ALSO	1152	=head1 SEE ALSO
773		1153
774	L<Coro>, L<Linux::AIO> (obsolete).	1154	L<Coro::AIO>.
775		1155
776	=head1 AUTHOR	1156	=head1 AUTHOR
777		1157
778	Marc Lehmann <schmorp@schmorp.de>	1158	Marc Lehmann <schmorp@schmorp.de>
779	http://home.schmorp.de/	1159	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs. Revision 1.89 by root, Sun Oct 29 11:03:18 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs.
Revision 1.89 by root, Sun Oct 29 11:03:18 2006 UTC