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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs.
Revision 1.90 by root, Mon Oct 30 23:30:00 2006 UTC

…		…
51	=head1 DESCRIPTION	51	=head1 DESCRIPTION
52		52
53	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
54	operating system supports.	54	operating system supports.
55		55
		56	Asynchronous means that operations that can normally block your program
		57	(e.g. reading from disk) will be done asynchronously: the operation
		58	will still block, but you can do something else in the meantime. This
		59	is extremely useful for programs that need to stay interactive even
		60	when doing heavy I/O (GUI programs, high performance network servers
		61	etc.), but can also be used to easily do operations in parallel that are
		62	normally done sequentially, e.g. stat'ing many files, which is much faster
		63	on a RAID volume or over NFS when you do a number of stat operations
		64	concurrently.
		65
		66	While most of this works on all types of file descriptors (for example
		67	sockets), using these functions on file descriptors that support
		68	nonblocking operation (again, sockets, pipes etc.) is very inefficient or
		69	might not work (aio_read fails on sockets/pipes/fifos). Use an event loop
		70	for that (such as the L<Event\|Event> module): IO::AIO will naturally fit
		71	into such an event loop itself.
		72
56	Currently, a number of threads are started that execute your read/writes	73	In this version, a number of threads are started that execute your
57	and signal their completion. You don't need thread support in perl, and	74	requests and signal their completion. You don't need thread support
58	the threads created by this module will not be visible to perl. In the	75	in perl, and the threads created by this module will not be visible
59	future, this module might make use of the native aio functions available	76	to perl. In the future, this module might make use of the native aio
60	on many operating systems. However, they are often not well-supported	77	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	78	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	and they would only support aio_read and aio_write, so the remaining	79	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	80	aio_write, so the remaining functionality would have to be implemented
		81	using threads anyway.
64		82
65	Although the module will work with in the presence of other threads,	83	Although the module will work with in the presence of other (Perl-)
66	it is currently not reentrant in any way, so use appropriate locking	84	threads, it is currently not reentrant in any way, so use appropriate
67	yourself, always call C<poll_cb> from within the same thread, or never	85	locking yourself, always call C<poll_cb> from within the same thread, or
68	call C<poll_cb> (or other C<aio_> functions) recursively.	86	never call C<poll_cb> (or other C<aio_> functions) recursively.
		87
		88	=head2 EXAMPLE
		89
		90	This is a simple example that uses the Event module and loads
		91	F</etc/passwd> asynchronously:
		92
		93	use Fcntl;
		94	use Event;
		95	use IO::AIO;
		96
		97	# register the IO::AIO callback with Event
		98	Event->io (fd => IO::AIO::poll_fileno,
		99	poll => 'r',
		100	cb => \&IO::AIO::poll_cb);
		101
		102	# queue the request to open /etc/passwd
		103	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		104	my $fh = $_[0]
		105	or die "error while opening: $!";
		106
		107	# stat'ing filehandles is generally non-blocking
		108	my $size = -s $fh;
		109
		110	# queue a request to read the file
		111	my $contents;
		112	aio_read $fh, 0, $size, $contents, 0, sub {
		113	$_[0] == $size
		114	or die "short read: $!";
		115
		116	close $fh;
		117
		118	# file contents now in $contents
		119	print $contents;
		120
		121	# exit event loop and program
		122	Event::unloop;
		123	};
		124	};
		125
		126	# possibly queue up other requests, or open GUI windows,
		127	# check for sockets etc. etc.
		128
		129	# process events as long as there are some:
		130	Event::loop;
		131
		132	=head1 REQUEST ANATOMY AND LIFETIME
		133
		134	Every C<aio_*> function creates a request. which is a C data structure not
		135	directly visible to Perl.
		136
		137	If called in non-void context, every request function returns a Perl
		138	object representing the request. In void context, nothing is returned,
		139	which saves a bit of memory.
		140
		141	The perl object is a fairly standard ref-to-hash object. The hash contents
		142	are not used by IO::AIO so you are free to store anything you like in it.
		143
		144	During their existance, aio requests travel through the following states,
		145	in order:
		146
		147	=over 4
		148
		149	=item ready
		150
		151	Immediately after a request is created it is put into the ready state,
		152	waiting for a thread to execute it.
		153
		154	=item execute
		155
		156	A thread has accepted the request for processing and is currently
		157	executing it (e.g. blocking in read).
		158
		159	=item pending
		160
		161	The request has been executed and is waiting for result processing.
		162
		163	While request submission and execution is fully asynchronous, result
		164	processing is not and relies on the perl interpreter calling C<poll_cb>
		165	(or another function with the same effect).
		166
		167	=item result
		168
		169	The request results are processed synchronously by C<poll_cb>.
		170
		171	The C<poll_cb> function will process all outstanding aio requests by
		172	calling their callbacks, freeing memory associated with them and managing
		173	any groups they are contained in.
		174
		175	=item done
		176
		177	Request has reached the end of its lifetime and holds no resources anymore
		178	(except possibly for the Perl object, but its connection to the actual
		179	aio request is severed and calling its methods will either do nothing or
		180	result in a runtime error).
		181
		182	=back
69		183
70	=cut	184	=cut
71		185
72	package IO::AIO;	186	package IO::AIO;
73		187
…		…
75	use strict 'vars';	189	use strict 'vars';
76		190
77	use base 'Exporter';	191	use base 'Exporter';
78		192
79	BEGIN {	193	BEGIN {
80	our $VERSION = '2.0';	194	our $VERSION = '2.1';
81		195
82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	196	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
83	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	197	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	198	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
85	aio_group aio_nop);	199	aio_move aio_copy aio_group aio_nop aio_mknod);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	200	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	201	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	202	min_parallel max_parallel max_idle
		203	nreqs nready npending nthreads
		204	max_poll_time max_poll_reqs);
89		205
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	206	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		207
92	require XSLoader;	208	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	209	XSLoader::load ("IO::AIO", $VERSION);
94	}	210	}
95		211
96	=head1 FUNCTIONS	212	=head1 FUNCTIONS
97		213
98	=head2 AIO FUNCTIONS	214	=head2 AIO REQUEST FUNCTIONS
99		215
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	216	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	217	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	218	and they all accept an additional (and optional) C<$callback> argument
103	which must be a code reference. This code reference will get called with	219	which must be a code reference. This code reference will get called with
…		…
106	syscall has been executed asynchronously.	222	syscall has been executed asynchronously.
107		223
108	All functions expecting a filehandle keep a copy of the filehandle	224	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	225	internally until the request has finished.
110		226
111	All requests return objects of type L<IO::AIO::REQ> that allow further	227	All functions return request objects of type L<IO::AIO::REQ> that allow
112	manipulation of those requests while they are in-flight.	228	further manipulation of those requests while they are in-flight.
113		229
114	The pathnames you pass to these routines I<must> be absolute and	230	The pathnames you pass to these routines I<must> be absolute and
115	encoded in byte form. The reason for the former is that at the time the	231	encoded as octets. The reason for the former is that at the time the
116	request is being executed, the current working directory could have	232	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	233	changed. Alternatively, you can make sure that you never change the
118	current working directory.	234	current working directory anywhere in the program and then use relative
		235	paths.
119		236
120	To encode pathnames to byte form, either make sure you either: a)	237	To encode pathnames as octets, either make sure you either: a) always pass
121	always pass in filenames you got from outside (command line, readdir	238	in filenames you got from outside (command line, readdir etc.) without
122	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	239	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
123	your pathnames to the locale (or other) encoding in effect in the user	240	your pathnames to the locale (or other) encoding in effect in the user
124	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	241	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	242	use something else to ensure your scalar has the correct contents.
		243
		244	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		245	handles correctly wether it is set or not.
126		246
127	=over 4	247	=over 4
128		248
129	=item aioreq_pri $pri	249	=item $prev_pri = aioreq_pri [$pri]
130		250
131	Sets the priority for the next aio request. The default priority	251	Returns the priority value that would be used for the next request and, if
		252	C<$pri> is given, sets the priority for the next aio request.
		253
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	254	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	255	and C<4>, respectively. Requests with higher priority will be serviced
		256	first.
134		257
135	The priority will be reset to C<0> after each call to one of the C<aio_>	258	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	259	functions.
		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.
137		279
138	=item aio_open $pathname, $flags, $mode, $callback->($fh)	280	=item aio_open $pathname, $flags, $mode, $callback->($fh)
139		281
140	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
141	created filehandle for the file.	283	created filehandle for the file.
…		…
191		333
192	aio_read $fh, 7, 15, $buffer, 0, sub {	334	aio_read $fh, 7, 15, $buffer, 0, sub {
193	$_[0] > 0 or die "read error: $!";	335	$_[0] > 0 or die "read error: $!";
194	print "read $_[0] bytes: <$buffer>\n";	336	print "read $_[0] bytes: <$buffer>\n";
195	};	337	};
196
197	=item aio_move $srcpath, $dstpath, $callback->($status)
198
199	[EXPERIMENTAL due to internal aio_group use]
200
201	Try to move the I<file> (directories not supported as either source or
202	destination) from C<$srcpath> to C<$dstpath> and call the callback with
203	the C<0> (error) or C<-1> ok.
204
205	This is a composite request that tries to rename(2) the file first. If
206	rename files with C<EXDEV>, it creates the destination file with mode 0200
207	and copies the contents of the source file into it using C<aio_sendfile>,
208	followed by restoring atime, mtime, access mode and uid/gid, in that
209	order, and unlinking the C<$srcpath>.
210
211	If an error occurs, the partial destination file will be unlinked, if
212	possible, except when setting atime, mtime, access mode and uid/gid, where
213	errors are being ignored.
214
215	=cut
216
217	sub aio_move($$$) {
218	my ($src, $dst, $cb) = @_;
219
220	my $grp = aio_group $cb;
221
222	add $grp aio_rename $src, $dst, sub {
223	if ($_[0] && $! == EXDEV) {
224	add $grp aio_open $src, O_RDONLY, 0, sub {
225	if (my $src_fh = $_[0]) {
226	my @stat = stat $src_fh;
227
228	add $grp aio_open $dst, O_WRONLY, 0200, sub {
229	if (my $dst_fh = $_[0]) {
230	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
231	close $src_fh;
232
233	if ($_[0] == $stat[7]) {
234	utime $stat[8], $stat[9], $dst;
235	chmod $stat[2] & 07777, $dst_fh;
236	chown $stat[4], $stat[5], $dst_fh;
237	close $dst_fh;
238
239	add $grp aio_unlink $src, sub {
240	$grp->result ($_[0]);
241	};
242	} else {
243	my $errno = $!;
244	add $grp aio_unlink $dst, sub {
245	$! = $errno;
246	$grp->result (-1);
247	};
248	}
249	};
250	} else {
251	$grp->result (-1);
252	}
253	},
254
255	} else {
256	$grp->result (-1);
257	}
258	};
259	} else {
260	$grp->result ($_[0]);
261	}
262	};
263
264	$grp
265	}
266		338
267	=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)
268		340
269	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
270	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
…		…
326	=item aio_unlink $pathname, $callback->($status)	398	=item aio_unlink $pathname, $callback->($status)
327		399
328	Asynchronously unlink (delete) a file and call the callback with the	400	Asynchronously unlink (delete) a file and call the callback with the
329	result code.	401	result code.
330		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
331	=item aio_link $srcpath, $dstpath, $callback->($status)	413	=item aio_link $srcpath, $dstpath, $callback->($status)
332		414
333	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
334	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.
335		417
336	=item aio_symlink $srcpath, $dstpath, $callback->($status)	418	=item aio_symlink $srcpath, $dstpath, $callback->($status)
337		419
338	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
339	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.
340		428
341	=item aio_rename $srcpath, $dstpath, $callback->($status)	429	=item aio_rename $srcpath, $dstpath, $callback->($status)
342		430
343	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
344	rename(2) and call the callback with the result code.	432	rename(2) and call the callback with the result code.
…		…
355	sorted, and will B<NOT> include the C<.> and C<..> entries.	443	sorted, and will B<NOT> include the C<.> and C<..> entries.
356		444
357	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
358	with the filenames.	446	with the filenames.
359		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
360	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	550	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
361		551
362	[EXPERIMENTAL due to internal aio_group use]
363
364	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
365	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
366	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
367	recurse into (everything else).	555	recurse into (everything else, including symlinks to directories).
368		556
369	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_
370	C<$maxreq> specifies the maximum number of outstanding aio requests that	558	C<$maxreq> specifies the maximum number of outstanding aio requests that
371	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
372	will be chosen (currently 6).	560	will be chosen (currently 4).
373		561
374	On error, the callback is called without arguments, otherwise it receives	562	On error, the callback is called without arguments, otherwise it receives
375	two array-refs with path-relative entry names.	563	two array-refs with path-relative entry names.
376		564
377	Example:	565	Example:
…		…
414	=cut	602	=cut
415		603
416	sub aio_scandir($$$) {	604	sub aio_scandir($$$) {
417	my ($path, $maxreq, $cb) = @_;	605	my ($path, $maxreq, $cb) = @_;
418		606
		607	my $pri = aioreq_pri;
		608
419	my $grp = aio_group $cb;	609	my $grp = aio_group $cb;
420		610
421	$maxreq = 6 if $maxreq <= 0;	611	$maxreq = 4 if $maxreq <= 0;
422		612
423	# stat once	613	# stat once
		614	aioreq_pri $pri;
424	add $grp aio_stat $path, sub {	615	add $grp aio_stat $path, sub {
425	return $grp->result () if $_[0];	616	return $grp->result () if $_[0];
426	my $now = time;	617	my $now = time;
427	my $hash1 = join ":", (stat _)[0,1,3,7,9];	618	my $hash1 = join ":", (stat _)[0,1,3,7,9];
428		619
429	# read the directory entries	620	# read the directory entries
		621	aioreq_pri $pri;
430	add $grp aio_readdir $path, sub {	622	add $grp aio_readdir $path, sub {
431	my $entries = shift	623	my $entries = shift
432	or return $grp->result ();	624	or return $grp->result ();
433		625
434	# stat the dir another time	626	# stat the dir another time
		627	aioreq_pri $pri;
435	add $grp aio_stat $path, sub {	628	add $grp aio_stat $path, sub {
436	my $hash2 = join ":", (stat _)[0,1,3,7,9];	629	my $hash2 = join ":", (stat _)[0,1,3,7,9];
437		630
438	my $ndirs;	631	my $ndirs;
439		632
…		…
454	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	647	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
455	@$entries];	648	@$entries];
456		649
457	my (@dirs, @nondirs);	650	my (@dirs, @nondirs);
458		651
459	my ($statcb, $schedcb);
460	my $nreq = 0;
461
462	my $statgrp = add $grp aio_group;	652	my $statgrp = add $grp aio_group sub {
		653	$grp->result (\@dirs, \@nondirs);
		654	};
463		655
464	$schedcb = sub {	656	limit $statgrp $maxreq;
465	if (@$entries) {	657	feed $statgrp sub {
466	if ($nreq < $maxreq) {	658	return unless @$entries;
467	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	}
468	$nreq++;	679	}
469	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
470	}	680	}
471	} elsif (!$nreq) {
472	# finished
473	$statgrp->cancel;
474	undef $statcb;
475	undef $schedcb;
476	$grp->result (\@dirs, \@nondirs);
477	}	681	};
478	};	682	};
479	$statcb = sub {
480	my ($status, $entry) = @_;
481
482	if ($status < 0) {
483	$nreq--;
484	push @nondirs, $entry;
485	&$schedcb;
486	} else {
487	# need to check for real directory
488	add $grp aio_lstat "$path/$entry", sub {
489	$nreq--;
490
491	if (-d _) {
492	push @dirs, $entry;
493
494	if (!--$ndirs) {
495	push @nondirs, @$entries;
496	$entries = [];
497	}
498	} else {
499	push @nondirs, $entry;
500	}
501
502	&$schedcb;
503	}
504	}
505	};
506
507	&$schedcb while @$entries && $nreq < $maxreq;
508	};	683	};
509	};	684	};
510	};	685	};
511		686
512	$grp	687	$grp
…		…
525	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
526	detected, it will be emulated by calling C<fsync> instead.	701	detected, it will be emulated by calling C<fsync> instead.
527		702
528	=item aio_group $callback->(...)	703	=item aio_group $callback->(...)
529		704
530	[EXPERIMENTAL]
531
532	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
533	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
534	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.
535		709
536	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
537	for more info.	711	for more info.
538		712
539	Example:	713	Example:
…		…
558	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
559	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
560	entered their execution phase. This can be used to measure request	734	entered their execution phase. This can be used to measure request
561	latency.	735	latency.
562		736
563	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	737	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
564		738
565	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
566	the request workers to sleep for the given time.	740	the request workers to sleep for the given time.
567		741
568	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
569	like sleep and file handle readable/writable, the overhead this creates	743	like sleep and file handle readable/writable, the overhead this creates is
570	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
571	under artificial I/O pressure.	745	except to put your application under artificial I/O pressure.
572		746
573	=back	747	=back
574		748
575	=head2 IO::AIO::REQ CLASS	749	=head2 IO::AIO::REQ CLASS
576		750
577	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
578	called in non-void context.	752	called in non-void context.
579
580	A request always moves through the following five states in its lifetime,
581	in order: B<ready> (request has been created, but has not been executed
582	yet), B<execute> (request is currently being executed), B<pending>
583	(request has been executed but callback has not been called yet),
584	B<result> (results are being processed synchronously, includes calling the
585	callback) and B<done> (request has reached the end of its lifetime and
586	holds no resources anymore).
587		753
588	=over 4	754	=over 4
589		755
590	=item cancel $req	756	=item cancel $req
591		757
…		…
645	=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.
646		812
647	=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
648	any later time).	814	any later time).
649		815
650	=item * This does not harmonise well with C<max_outstanding>, so best do
651	not combine C<aio_group> with it. Groups and feeders are recommended for
652	this kind of concurrency-limiting.
653
654	=back	816	=back
655		817
656	Their lifetime, simplified, looks like this: when they are empty, they	818	Their lifetime, simplified, looks like this: when they are empty, they
657	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
658	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
…		…
673	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
674	dependencies.	836	dependencies.
675		837
676	Returns all its arguments.	838	Returns all its arguments.
677		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
678	=item $grp->result (...)	845	=item $grp->result (...)
679		846
680	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
681	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.
682		863
683	=item feed $grp $callback->($grp)	864	=item feed $grp $callback->($grp)
684
685	[VERY EXPERIMENTAL]
686		865
687	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
688	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,
689	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,
690	this might starve other requests for a potentially long time. For	869	this might starve other requests for a potentially long time. For
…		…
727		906
728	=back	907	=back
729		908
730	=head2 SUPPORT FUNCTIONS	909	=head2 SUPPORT FUNCTIONS
731		910
		911	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		912
732	=over 4	913	=over 4
733		914
734	=item $fileno = IO::AIO::poll_fileno	915	=item $fileno = IO::AIO::poll_fileno
735		916
736	Return the I<request result pipe file descriptor>. This filehandle must be	917	Return the I<request result pipe file descriptor>. This filehandle must be
…		…
740		921
741	See C<poll_cb> for an example.	922	See C<poll_cb> for an example.
742		923
743	=item IO::AIO::poll_cb	924	=item IO::AIO::poll_cb
744		925
745	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
746	regularly. Returns the number of events processed. Returns immediately	927	regularly. Returns the number of events processed. Returns immediately
747	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.
748		933
749	Example: Install an Event watcher that automatically calls	934	Example: Install an Event watcher that automatically calls
750	IO::AIO::poll_cb with high priority:	935	IO::AIO::poll_cb with high priority:
751		936
752	Event->io (fd => IO::AIO::poll_fileno,	937	Event->io (fd => IO::AIO::poll_fileno,
753	poll => 'r', async => 1,	938	poll => 'r', async => 1,
754	cb => \&IO::AIO::poll_cb);	939	cb => \&IO::AIO::poll_cb);
755		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
756	=item IO::AIO::poll_wait	974	=item IO::AIO::poll_wait
757		975
758	Wait till the result filehandle becomes ready for reading (simply does a	976	Wait till the result filehandle becomes ready for reading (simply does a
759	C<select> on the filehandle. This is useful if you want to synchronously wait	977	C<select> on the filehandle. This is useful if you want to synchronously
760	for some requests to finish).	978	wait for some requests to finish).
761		979
762	See C<nreqs> for an example.	980	See C<nreqs> for an example.
763		981
		982	=item IO::AIO::poll
		983
		984	Waits until some requests have been handled.
		985
		986	Strictly equivalent to:
		987
		988	IO::AIO::poll_wait, IO::AIO::poll_cb
		989	if IO::AIO::nreqs;
		990
764	=item IO::AIO::nreqs	991	=item IO::AIO::flush
765		992
766	Returns the number of requests currently outstanding (i.e. for which their	993	Wait till all outstanding AIO requests have been handled.
767	callback has not been invoked yet).
768		994
769	Example: wait till there are no outstanding requests anymore:	995	Strictly equivalent to:
770		996
771	IO::AIO::poll_wait, IO::AIO::poll_cb	997	IO::AIO::poll_wait, IO::AIO::poll_cb
772	while IO::AIO::nreqs;	998	while IO::AIO::nreqs;
773		999
774	=item IO::AIO::flush	1000	=head3 CONTROLLING THE NUMBER OF THREADS
775
776	Wait till all outstanding AIO requests have been handled.
777
778	Strictly equivalent to:
779
780	IO::AIO::poll_wait, IO::AIO::poll_cb
781	while IO::AIO::nreqs;
782
783	=item IO::AIO::poll
784
785	Waits until some requests have been handled.
786
787	Strictly equivalent to:
788
789	IO::AIO::poll_wait, IO::AIO::poll_cb
790	if IO::AIO::nreqs;
791		1001
792	=item IO::AIO::min_parallel $nthreads	1002	=item IO::AIO::min_parallel $nthreads
793		1003
794	Set the minimum number of AIO threads to C<$nthreads>. The current	1004	Set the minimum number of AIO threads to C<$nthreads>. The current
795	default is C<8>, which means eight asynchronous operations can execute	1005	default is C<8>, which means eight asynchronous operations can execute
796	concurrently at any one time (the number of outstanding requests,	1006	concurrently at any one time (the number of outstanding requests,
797	however, is unlimited).	1007	however, is unlimited).
798		1008
799	IO::AIO starts threads only on demand, when an AIO request is queued and	1009	IO::AIO starts threads only on demand, when an AIO request is queued and
800	no free thread exists.	1010	no free thread exists. Please note that queueing up a hundred requests can
		1011	create demand for a hundred threads, even if it turns out that everything
		1012	is in the cache and could have been processed faster by a single thread.
801		1013
802	It is recommended to keep the number of threads relatively low, as some	1014	It is recommended to keep the number of threads relatively low, as some
803	Linux kernel versions will scale negatively with the number of threads	1015	Linux kernel versions will scale negatively with the number of threads
804	(higher parallelity => MUCH higher latency). With current Linux 2.6	1016	(higher parallelity => MUCH higher latency). With current Linux 2.6
805	versions, 4-32 threads should be fine.	1017	versions, 4-32 threads should be fine.
…		…
819	This module automatically runs C<max_parallel 0> at program end, to ensure	1031	This module automatically runs C<max_parallel 0> at program end, to ensure
820	that all threads are killed and that there are no outstanding requests.	1032	that all threads are killed and that there are no outstanding requests.
821		1033
822	Under normal circumstances you don't need to call this function.	1034	Under normal circumstances you don't need to call this function.
823		1035
		1036	=item IO::AIO::max_idle $nthreads
		1037
		1038	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1039	threads that did not get a request to process within 10 seconds). That
		1040	means if a thread becomes idle while C<$nthreads> other threads are also
		1041	idle, it will free its resources and exit.
		1042
		1043	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1044	to allow for extremely high load situations, but want to free resources
		1045	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1046
		1047	The default is probably ok in most situations, especially if thread
		1048	creation is fast. If thread creation is very slow on your system you might
		1049	want to use larger values.
		1050
824	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1051	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
825		1052
826	[DEPRECATED]	1053	This is a very bad function to use in interactive programs because it
		1054	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1055	use an C<aio_group> together with a feed callback.
827		1056
828	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1057	Sets the maximum number of outstanding requests to C<$nreqs>. If you
829	try to queue up more than this number of requests, the caller will block until	1058	to queue up more than this number of requests, the next call to the
830	some requests have been handled.	1059	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1060	function will block until the limit is no longer exceeded.
831		1061
832	The default is very large, so normally there is no practical limit. If you	1062	The default value is very large, so there is no practical limit on the
833	queue up many requests in a loop it often improves speed if you set	1063	number of outstanding requests.
834	this to a relatively low number, such as C<100>.
835		1064
836	This function does not work well together with C<aio_group>'s, and their	1065	You can still queue as many requests as you want. Therefore,
837	feeder interface is better suited to limiting concurrency, so do not use	1066	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
838	this function.	1067	as a stop gap to shield against fatal memory overflow (with large values).
839		1068
840	Under normal circumstances you don't need to call this function.	1069	=head3 STATISTICAL INFORMATION
		1070
		1071	=item IO::AIO::nreqs
		1072
		1073	Returns the number of requests currently in the ready, execute or pending
		1074	states (i.e. for which their callback has not been invoked yet).
		1075
		1076	Example: wait till there are no outstanding requests anymore:
		1077
		1078	IO::AIO::poll_wait, IO::AIO::poll_cb
		1079	while IO::AIO::nreqs;
		1080
		1081	=item IO::AIO::nready
		1082
		1083	Returns the number of requests currently in the ready state (not yet
		1084	executed).
		1085
		1086	=item IO::AIO::npending
		1087
		1088	Returns the number of requests currently in the pending state (executed,
		1089	but not yet processed by poll_cb).
841		1090
842	=back	1091	=back
843		1092
844	=cut	1093	=cut
845		1094
…		…
860	}	1109	}
861		1110
862	min_parallel 8;	1111	min_parallel 8;
863		1112
864	END {	1113	END {
865	max_parallel 0;	1114	min_parallel 1;
866	}	1115	flush;
		1116	};
867		1117
868	1;	1118	1;
869		1119
870	=head2 FORK BEHAVIOUR	1120	=head2 FORK BEHAVIOUR
871		1121
872	This module should do "the right thing" when the process using it forks:	1122	This module should do "the right thing" when the process using it forks:
873		1123
874	Before the fork, IO::AIO enters a quiescent state where no requests	1124	Before the fork, IO::AIO enters a quiescent state where no requests
875	can be added in other threads and no results will be processed. After	1125	can be added in other threads and no results will be processed. After
876	the fork the parent simply leaves the quiescent state and continues	1126	the fork the parent simply leaves the quiescent state and continues
877	request/result processing, while the child clears the request/result	1127	request/result processing, while the child frees the request/result queue
878	queue (so the requests started before the fork will only be handled in	1128	(so that the requests started before the fork will only be handled in the
879	the parent). Threads will be started on demand until the limit ste in the	1129	parent). Threads will be started on demand until the limit set in the
880	parent process has been reached again.	1130	parent process has been reached again.
881		1131
882	In short: the parent will, after a short pause, continue as if fork had	1132	In short: the parent will, after a short pause, continue as if fork had
883	not been called, while the child will act as if IO::AIO has not been used	1133	not been called, while the child will act as if IO::AIO has not been used
884	yet.	1134	yet.
885		1135
886	=head2 MEMORY USAGE	1136	=head2 MEMORY USAGE
887		1137
		1138	Per-request usage:
		1139
888	Each aio request uses - depending on your architecture - around 128 bytes	1140	Each aio request uses - depending on your architecture - around 100-200
889	of memory. In addition, stat requests need a stat buffer (possibly a few	1141	bytes of memory. In addition, stat requests need a stat buffer (possibly
890	hundred bytes). Perl scalars and other data passed into aio requests will	1142	a few hundred bytes), readdir requires a result buffer and so on. Perl
891	also be locked.	1143	scalars and other data passed into aio requests will also be locked and
		1144	will consume memory till the request has entered the done state.
892		1145
893	This is now awfully much, so queuing lots of requests is not usually a	1146	This is now awfully much, so queuing lots of requests is not usually a
894	problem.	1147	problem.
895		1148
896	Each thread needs a stack area which is usually around 16k, sometimes much	1149	Per-thread usage:
897	larger, depending on the OS.	1150
		1151	In the execution phase, some aio requests require more memory for
		1152	temporary buffers, and each thread requires a stack and other data
		1153	structures (usually around 16k-128k, depending on the OS).
		1154
		1155	=head1 KNOWN BUGS
		1156
		1157	Known bugs will be fixed in the next release.
898		1158
899	=head1 SEE ALSO	1159	=head1 SEE ALSO
900		1160
901	L<Coro::AIO>.	1161	L<Coro::AIO>.
902		1162

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing IO-AIO/AIO.pm (file contents): Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs. Revision 1.90 by root, Mon Oct 30 23:30:00 2006 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs.
Revision 1.90 by root, Mon Oct 30 23:30:00 2006 UTC