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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs.
Revision 1.92 by root, Wed Nov 8 01:57:42 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 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
55	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
56	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
57	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
58	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
59	on many operating systems. However, they are often not well-supported	77	functions available on many operating systems. However, they are often
60	(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
61	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
62	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.
63		82
64	Although the module will work with in the presence of other threads, it is	83	Although the module will work with in the presence of other (Perl-)
65	currently not reentrant, so use appropriate locking yourself, always call	84	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	85	locking yourself, always call C<poll_cb> from within the same thread, or
67	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
68		183
69	=cut	184	=cut
70		185
71	package IO::AIO;	186	package IO::AIO;
72		187
…		…
74	use strict 'vars';	189	use strict 'vars';
75		190
76	use base 'Exporter';	191	use base 'Exporter';
77		192
78	BEGIN {	193	BEGIN {
79	our $VERSION = '2.0';	194	our $VERSION = '2.2';
80		195
81	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
82	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
83	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
84	aio_group aio_nop);	199	aio_move aio_copy aio_group aio_nop aio_mknod);
85	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	200	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
86	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	201	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
87	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);
88		205
89	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	206	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
90		207
91	require XSLoader;	208	require XSLoader;
92	XSLoader::load ("IO::AIO", $VERSION);	209	XSLoader::load ("IO::AIO", $VERSION);
93	}	210	}
94		211
95	=head1 FUNCTIONS	212	=head1 FUNCTIONS
96		213
97	=head2 AIO FUNCTIONS	214	=head2 AIO REQUEST FUNCTIONS
98		215
99	All the C<aio_*> calls are more or less thin wrappers around the syscall	216	All the C<aio_*> calls are more or less thin wrappers around the syscall
100	with the same name (sans C<aio_>). The arguments are similar or identical,	217	with the same name (sans C<aio_>). The arguments are similar or identical,
101	and they all accept an additional (and optional) C<$callback> argument	218	and they all accept an additional (and optional) C<$callback> argument
102	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
…		…
105	syscall has been executed asynchronously.	222	syscall has been executed asynchronously.
106		223
107	All functions expecting a filehandle keep a copy of the filehandle	224	All functions expecting a filehandle keep a copy of the filehandle
108	internally until the request has finished.	225	internally until the request has finished.
109		226
110	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
111	manipulation of those requests while they are in-flight.	228	further manipulation of those requests while they are in-flight.
112		229
113	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
114	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
115	request is being executed, the current working directory could have	232	request is being executed, the current working directory could have
116	changed. Alternatively, you can make sure that you never change the	233	changed. Alternatively, you can make sure that you never change the
117	current working directory.	234	current working directory anywhere in the program and then use relative
		235	paths.
118		236
119	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
120	always pass in filenames you got from outside (command line, readdir	238	in filenames you got from outside (command line, readdir etc.) without
121	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
122	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
123	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)
124	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.
125		246
126	=over 4	247	=over 4
		248
		249	=item $prev_pri = aioreq_pri [$pri]
		250
		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
		254	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		255	and C<4>, respectively. Requests with higher priority will be serviced
		256	first.
		257
		258	The priority will be reset to C<0> after each call to one of the C<aio_*>
		259	functions.
		260
		261	Example: open a file with low priority, then read something from it with
		262	higher priority so the read request is serviced before other low priority
		263	open requests (potentially spamming the cache):
		264
		265	aioreq_pri -3;
		266	aio_open ..., sub {
		267	return unless $_[0];
		268
		269	aioreq_pri -2;
		270	aio_read $_[0], ..., sub {
		271	...
		272	};
		273	};
		274
		275	=item aioreq_nice $pri_adjust
		276
		277	Similar to C<aioreq_pri>, but subtracts the given value from the current
		278	priority, so the effect is cumulative.
127		279
128	=item aio_open $pathname, $flags, $mode, $callback->($fh)	280	=item aio_open $pathname, $flags, $mode, $callback->($fh)
129		281
130	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
131	created filehandle for the file.	283	created filehandle for the file.
…		…
181		333
182	aio_read $fh, 7, 15, $buffer, 0, sub {	334	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] > 0 or die "read error: $!";	335	$_[0] > 0 or die "read error: $!";
184	print "read $_[0] bytes: <$buffer>\n";	336	print "read $_[0] bytes: <$buffer>\n";
185	};	337	};
186
187	=item aio_move $srcpath, $dstpath, $callback->($status)
188
189	[EXPERIMENTAL due to internal aio_group use]
190
191	Try to move the I<file> (directories not supported as either source or
192	destination) from C<$srcpath> to C<$dstpath> and call the callback with
193	the C<0> (error) or C<-1> ok.
194
195	This is a composite request that tries to rename(2) the file first. If
196	rename files with C<EXDEV>, it creates the destination file with mode 0200
197	and copies the contents of the source file into it using C<aio_sendfile>,
198	followed by restoring atime, mtime, access mode and uid/gid, in that
199	order, and unlinking the C<$srcpath>.
200
201	If an error occurs, the partial destination file will be unlinked, if
202	possible, except when setting atime, mtime, access mode and uid/gid, where
203	errors are being ignored.
204
205	=cut
206
207	sub aio_move($$$) {
208	my ($src, $dst, $cb) = @_;
209
210	my $grp = aio_group $cb;
211
212	add $grp aio_rename $src, $dst, sub {
213	if ($_[0] && $! == EXDEV) {
214	add $grp aio_open $src, O_RDONLY, 0, sub {
215	if (my $src_fh = $_[0]) {
216	my @stat = stat $src_fh;
217
218	add $grp aio_open $dst, O_WRONLY, 0200, sub {
219	if (my $dst_fh = $_[0]) {
220	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
221	close $src_fh;
222
223	if ($_[0] == $stat[7]) {
224	utime $stat[8], $stat[9], $dst;
225	chmod $stat[2] & 07777, $dst_fh;
226	chown $stat[4], $stat[5], $dst_fh;
227	close $dst_fh;
228
229	add $grp aio_unlink $src, sub {
230	$grp->result ($_[0]);
231	};
232	} else {
233	my $errno = $!;
234	add $grp aio_unlink $dst, sub {
235	$! = $errno;
236	$grp->result (-1);
237	};
238	}
239	};
240	} else {
241	$grp->result (-1);
242	}
243	},
244
245	} else {
246	$grp->result (-1);
247	}
248	};
249	} else {
250	$grp->result ($_[0]);
251	}
252	};
253
254	$grp
255	}
256		338
257	=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)
258		340
259	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
260	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
…		…
316	=item aio_unlink $pathname, $callback->($status)	398	=item aio_unlink $pathname, $callback->($status)
317		399
318	Asynchronously unlink (delete) a file and call the callback with the	400	Asynchronously unlink (delete) a file and call the callback with the
319	result code.	401	result code.
320		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
321	=item aio_link $srcpath, $dstpath, $callback->($status)	413	=item aio_link $srcpath, $dstpath, $callback->($status)
322		414
323	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
324	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.
325		417
326	=item aio_symlink $srcpath, $dstpath, $callback->($status)	418	=item aio_symlink $srcpath, $dstpath, $callback->($status)
327		419
328	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
329	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.
330		428
331	=item aio_rename $srcpath, $dstpath, $callback->($status)	429	=item aio_rename $srcpath, $dstpath, $callback->($status)
332		430
333	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
334	rename(2) and call the callback with the result code.	432	rename(2) and call the callback with the result code.
…		…
345	sorted, and will B<NOT> include the C<.> and C<..> entries.	443	sorted, and will B<NOT> include the C<.> and C<..> entries.
346		444
347	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
348	with the filenames.	446	with the filenames.
349		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
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	550	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		551
352	[EXPERIMENTAL due to internal aio_group use]
353
354	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
355	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
356	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
357	recurse into (everything else).	555	recurse into (everything else, including symlinks to directories).
358		556
359	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_
360	C<$maxreq> specifies the maximum number of outstanding aio requests that	558	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	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
362	will be chosen (currently 6).	560	will be chosen (currently 4).
363		561
364	On error, the callback is called without arguments, otherwise it receives	562	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	563	two array-refs with path-relative entry names.
366		564
367	Example:	565	Example:
…		…
404	=cut	602	=cut
405		603
406	sub aio_scandir($$$) {	604	sub aio_scandir($$$) {
407	my ($path, $maxreq, $cb) = @_;	605	my ($path, $maxreq, $cb) = @_;
408		606
		607	my $pri = aioreq_pri;
		608
409	my $grp = aio_group $cb;	609	my $grp = aio_group $cb;
410		610
411	$maxreq = 6 if $maxreq <= 0;	611	$maxreq = 4 if $maxreq <= 0;
412		612
413	# stat once	613	# stat once
		614	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	615	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	616	return $grp->result () if $_[0];
416	my $now = time;	617	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	618	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		619
419	# read the directory entries	620	# read the directory entries
		621	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	622	add $grp aio_readdir $path, sub {
421	my $entries = shift	623	my $entries = shift
422	or return $grp->result ();	624	or return $grp->result ();
423		625
424	# stat the dir another time	626	# stat the dir another time
		627	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	628	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	629	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		630
428	my $ndirs;	631	my $ndirs;
429		632
…		…
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	647	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];	648	@$entries];
446		649
447	my (@dirs, @nondirs);	650	my (@dirs, @nondirs);
448		651
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	652	my $statgrp = add $grp aio_group sub {
		653	$grp->result (\@dirs, \@nondirs);
		654	};
453		655
454	$schedcb = sub {	656	limit $statgrp $maxreq;
455	if (@$entries) {	657	feed $statgrp sub {
456	if ($nreq < $maxreq) {	658	return unless @$entries;
457	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	}
458	$nreq++;	679	}
459	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
460	}	680	}
461	} elsif (!$nreq) {
462	# finished
463	$statgrp->cancel;
464	undef $statcb;
465	undef $schedcb;
466	$grp->result (\@dirs, \@nondirs);
467	}	681	};
468	};	682	};
469	$statcb = sub {
470	my ($status, $entry) = @_;
471
472	if ($status < 0) {
473	$nreq--;
474	push @nondirs, $entry;
475	&$schedcb;
476	} else {
477	# need to check for real directory
478	add $grp aio_lstat "$path/$entry", sub {
479	$nreq--;
480
481	if (-d _) {
482	push @dirs, $entry;
483
484	if (!--$ndirs) {
485	push @nondirs, @$entries;
486	$entries = [];
487	}
488	} else {
489	push @nondirs, $entry;
490	}
491
492	&$schedcb;
493	}
494	}
495	};
496
497	&$schedcb while @$entries && $nreq < $maxreq;
498	};	683	};
499	};	684	};
500	};	685	};
501		686
502	$grp	687	$grp
…		…
515	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
516	detected, it will be emulated by calling C<fsync> instead.	701	detected, it will be emulated by calling C<fsync> instead.
517		702
518	=item aio_group $callback->(...)	703	=item aio_group $callback->(...)
519		704
520	[EXPERIMENTAL]
521
522	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
523	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
524	many requests into a single, composite, request.	707	many requests into a single, composite, request with a definite callback
		708	and the ability to cancel the whole request with its subrequests.
525		709
526	Returns an object of class L<IO::AIO::GRP>. See its documentation below	710	Returns an object of class L<IO::AIO::GRP>. See its documentation below
527	for more info.	711	for more info.
528		712
529	Example:	713	Example:
…		…
548	phase and still requires a worker thread. Thus, the callback will not	732	phase and still requires a worker thread. Thus, the callback will not
549	be executed immediately but only after other requests in the queue have	733	be executed immediately but only after other requests in the queue have
550	entered their execution phase. This can be used to measure request	734	entered their execution phase. This can be used to measure request
551	latency.	735	latency.
552		736
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	737	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
554		738
555	Mainly used for debugging and benchmarking, this aio request puts one of	739	Mainly used for debugging and benchmarking, this aio request puts one of
556	the request workers to sleep for the given time.	740	the request workers to sleep for the given time.
557		741
558	While it is theoretically handy to have simple I/O scheduling requests	742	While it is theoretically handy to have simple I/O scheduling requests
559	like sleep and file handle readable/writable, the overhead this creates	743	like sleep and file handle readable/writable, the overhead this creates is
560	is immense, so do not use this function except to put your application	744	immense (it blocks a thread for a long time) so do not use this function
561	under artificial I/O pressure.	745	except to put your application under artificial I/O pressure.
562		746
563	=back	747	=back
564		748
565	=head2 IO::AIO::REQ CLASS	749	=head2 IO::AIO::REQ CLASS
566		750
567	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
568	called in non-void context.	752	called in non-void context.
569
570	A request always moves through the following five states in its lifetime,
571	in order: B<ready> (request has been created, but has not been executed
572	yet), B<execute> (request is currently being executed), B<pending>
573	(request has been executed but callback has not been called yet),
574	B<result> (results are being processed synchronously, includes calling the
575	callback) and B<done> (request has reached the end of its lifetime and
576	holds no resources anymore).
577		753
578	=over 4	754	=over 4
579		755
580	=item cancel $req	756	=item cancel $req
581		757
…		…
635	=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.
636		812
637	=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
638	any later time).	814	any later time).
639		815
640	=item * This does not harmonise well with C<max_outstanding>, so best do
641	not combine C<aio_group> with it. Groups and feeders are recommended for
642	this kind of concurrency-limiting.
643
644	=back	816	=back
645		817
646	Their lifetime, simplified, looks like this: when they are empty, they	818	Their lifetime, simplified, looks like this: when they are empty, they
647	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
648	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
…		…
663	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
664	dependencies.	836	dependencies.
665		837
666	Returns all its arguments.	838	Returns all its arguments.
667		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
668	=item $grp->result (...)	845	=item $grp->result (...)
669		846
670	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
671	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.
672		863
673	=item feed $grp $callback->($grp)	864	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		865
677	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
678	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,
679	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,
680	this might starve other requests for a potentially long time. For	869	this might starve other requests for a potentially long time. For
681	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	870	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
682	requests, delaying any later requests for a long time.	871	requests, delaying any later requests for a long time.
683		872
684	To avoid this, and allow incremental generation of requests, you can	873	To avoid this, and allow incremental generation of requests, you can
685	instead a group and set a feeder on it that generates those requests. The	874	instead a group and set a feeder on it that generates those requests. The
686	feed callback will be called whenever there are few enough (see C<feed_limit>,	875	feed callback will be called whenever there are few enough (see C<limit>,
687	below) requests active in the group itself and is expected to queue more	876	below) requests active in the group itself and is expected to queue more
688	requests.	877	requests.
689		878
690	The feed can queue as many requests as it likes (i.e. C<add> does not	879	The feed callback can queue as many requests as it likes (i.e. C<add> does
691	impose any limits).	880	not impose any limits).
692		881
693	If the feed does not queue more requests when called, it will be	882	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	883	automatically removed from the group.
695		884
696	If the feed limit is C<0>, it will be set to C<2> automatically.	885	If the feed limit is C<0>, it will be set to C<2> automatically.
…		…
698	Example:	887	Example:
699		888
700	# stat all files in @files, but only ever use four aio requests concurrently:	889	# stat all files in @files, but only ever use four aio requests concurrently:
701		890
702	my $grp = aio_group sub { print "finished\n" };	891	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	892	limit $grp 4;
704	feed $grp sub {	893	feed $grp sub {
705	my $file = pop @files	894	my $file = pop @files
706	or return;	895	or return;
707		896
708	add $grp aio_stat $file, sub { ... };	897	add $grp aio_stat $file, sub { ... };
709	};	898	};
710		899
711	=item feed_limit $grp $num	900	=item limit $grp $num
712		901
713	Sets the feeder limit for the group: The feeder will be called whenever	902	Sets the feeder limit for the group: The feeder will be called whenever
714	the group contains less than this many requests.	903	the group contains less than this many requests.
715		904
716	Setting the limit to C<0> will pause the feeding process.	905	Setting the limit to C<0> will pause the feeding process.
717		906
718	=back	907	=back
719		908
720	=head2 SUPPORT FUNCTIONS	909	=head2 SUPPORT FUNCTIONS
		910
		911	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
721		912
722	=over 4	913	=over 4
723		914
724	=item $fileno = IO::AIO::poll_fileno	915	=item $fileno = IO::AIO::poll_fileno
725		916
…		…
730		921
731	See C<poll_cb> for an example.	922	See C<poll_cb> for an example.
732		923
733	=item IO::AIO::poll_cb	924	=item IO::AIO::poll_cb
734		925
735	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
736	regularly. Returns the number of events processed. Returns immediately	927	regularly. Returns the number of events processed. Returns immediately
737	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.
738		933
739	Example: Install an Event watcher that automatically calls	934	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	935	IO::AIO::poll_cb with high priority:
741		936
742	Event->io (fd => IO::AIO::poll_fileno,	937	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	938	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	939	cb => \&IO::AIO::poll_cb);
745		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
746	=item IO::AIO::poll_wait	974	=item IO::AIO::poll_wait
747		975
748	Wait till the result filehandle becomes ready for reading (simply does a	976	If there are any outstanding requests, wait till the result filehandle
749	C<select> on the filehandle. This is useful if you want to synchronously wait	977	becomes ready for reading (simply does a C<select> on the filehandle. This
750	for some requests to finish).	978	is useful if you want to synchronously wait for some requests to finish).
751		979
752	See C<nreqs> for an example.	980	See C<nreqs> for an example.
753		981
		982	=item IO::AIO::poll
		983
		984	Waits until some requests have been handled.
		985
		986	Returns the number of requests processed, but is otherwise strictly
		987	equivalent to:
		988
		989	IO::AIO::poll_wait, IO::AIO::poll_cb
		990	if IO::AIO::nreqs;
		991
754	=item IO::AIO::nreqs	992	=item IO::AIO::flush
755		993
756	Returns the number of requests currently outstanding (i.e. for which their	994	Wait till all outstanding AIO requests have been handled.
757	callback has not been invoked yet).
758		995
759	Example: wait till there are no outstanding requests anymore:	996	Strictly equivalent to:
760		997
761	IO::AIO::poll_wait, IO::AIO::poll_cb	998	IO::AIO::poll_wait, IO::AIO::poll_cb
762	while IO::AIO::nreqs;	999	while IO::AIO::nreqs;
763		1000
764	=item IO::AIO::flush	1001	=head3 CONTROLLING THE NUMBER OF THREADS
765
766	Wait till all outstanding AIO requests have been handled.
767
768	Strictly equivalent to:
769
770	IO::AIO::poll_wait, IO::AIO::poll_cb
771	while IO::AIO::nreqs;
772
773	=item IO::AIO::poll
774
775	Waits until some requests have been handled.
776
777	Strictly equivalent to:
778
779	IO::AIO::poll_wait, IO::AIO::poll_cb
780	if IO::AIO::nreqs;
781		1002
782	=item IO::AIO::min_parallel $nthreads	1003	=item IO::AIO::min_parallel $nthreads
783		1004
784	Set the minimum number of AIO threads to C<$nthreads>. The current	1005	Set the minimum number of AIO threads to C<$nthreads>. The current
785	default is C<8>, which means eight asynchronous operations can execute	1006	default is C<8>, which means eight asynchronous operations can execute
786	concurrently at any one time (the number of outstanding requests,	1007	concurrently at any one time (the number of outstanding requests,
787	however, is unlimited).	1008	however, is unlimited).
788		1009
789	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
790	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.
791		1014
792	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
793	Linux kernel versions will scale negatively with the number of threads	1016	Linux kernel versions will scale negatively with the number of threads
794	(higher parallelity => MUCH higher latency). With current Linux 2.6	1017	(higher parallelity => MUCH higher latency). With current Linux 2.6
795	versions, 4-32 threads should be fine.	1018	versions, 4-32 threads should be fine.
…		…
809	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
810	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.
811		1034
812	Under normal circumstances you don't need to call this function.	1035	Under normal circumstances you don't need to call this function.
813		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
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1052	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
815		1053
816	[DEPRECATED]	1054	This is a very bad function to use in interactive programs because it
		1055	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1056	use an C<aio_group> together with a feed callback.
817		1057
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1058	Sets the maximum number of outstanding requests to C<$nreqs>. If you
819	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
820	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.
821		1062
822	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
823	queue up many requests in a loop it often improves speed if you set	1064	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		1065
826	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,
827	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
828	this function.	1068	as a stop gap to shield against fatal memory overflow (with large values).
829		1069
830	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).
831		1091
832	=back	1092	=back
833		1093
834	=cut	1094	=cut
835		1095
…		…
850	}	1110	}
851		1111
852	min_parallel 8;	1112	min_parallel 8;
853		1113
854	END {	1114	END {
855	max_parallel 0;	1115	min_parallel 1;
856	}	1116	flush;
		1117	};
857		1118
858	1;	1119	1;
859		1120
860	=head2 FORK BEHAVIOUR	1121	=head2 FORK BEHAVIOUR
861		1122
862	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:
863		1124
864	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
865	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
866	the fork the parent simply leaves the quiescent state and continues	1127	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	1128	request/result processing, while the child frees the request/result queue
868	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
869	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
870	parent process has been reached again.	1131	parent process has been reached again.
871		1132
872	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
873	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
874	yet.	1135	yet.
875		1136
876	=head2 MEMORY USAGE	1137	=head2 MEMORY USAGE
877		1138
		1139	Per-request usage:
		1140
878	Each aio request uses - depending on your architecture - around 128 bytes	1141	Each aio request uses - depending on your architecture - around 100-200
879	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
880	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
881	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.
882		1146
883	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
884	problem.	1148	problem.
885		1149
886	Each thread needs a stack area which is usually around 16k, sometimes much	1150	Per-thread usage:
887	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.
888		1159
889	=head1 SEE ALSO	1160	=head1 SEE ALSO
890		1161
891	L<Coro>, L<Linux::AIO> (obsolete).	1162	L<Coro::AIO>.
892		1163
893	=head1 AUTHOR	1164	=head1 AUTHOR
894		1165
895	Marc Lehmann <schmorp@schmorp.de>	1166	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1167	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs. Revision 1.92 by root, Wed Nov 8 01:57:42 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs.
Revision 1.92 by root, Wed Nov 8 01:57:42 2006 UTC