[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 1.88 by root, Sun Oct 29 01:50:29 2006 UTC

…		…
18	};	18	};
19		19
20	# version 2+ has request and group objects	20	# version 2+ has request and group objects
21	use IO::AIO 2;	21	use IO::AIO 2;
22		22
		23	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	24	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	25	$req->cancel; # cancel request if still in queue
25		26
26	my $grp = aio_group sub { print "all stats done\n" };	27	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	28	add $grp aio_stat "..." for ...;
…		…
50	=head1 DESCRIPTION	51	=head1 DESCRIPTION
51		52
52	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
53	operating system supports.	54	operating system supports.
54		55
		56	Asynchronous means that operations that can normally block your program
		57	(e.g. reading from disk) will be done asynchronously: the operation
		58	will still block, but you can do something else in the meantime. This
		59	is extremely useful for programs that need to stay interactive even
		60	when doing heavy I/O (GUI programs, high performance network servers
		61	etc.), but can also be used to easily do operations in parallel that are
		62	normally done sequentially, e.g. stat'ing many files, which is much faster
		63	on a RAID volume or over NFS when you do a number of stat operations
		64	concurrently.
		65
		66	While this works on all types of file descriptors (for example sockets),
		67	using these functions on file descriptors that support nonblocking
		68	operation (again, sockets, pipes etc.) is very inefficient. Use an event
		69	loop for that (such as the L<Event\|Event> module): IO::AIO will naturally
		70	fit into such an event loop itself.
		71
55	Currently, a number of threads are started that execute your read/writes	72	In this version, a number of threads are started that execute your
56	and signal their completion. You don't need thread support in perl, and	73	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	74	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	75	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	76	functions available on many operating systems. However, they are often
60	(Linux doesn't allow them on normal files currently, for example),	77	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	78	files currently, for example), and they would only support aio_read and
62	functionality would have to be implemented using threads anyway.	79	aio_write, so the remaining functionality would have to be implemented
		80	using threads anyway.
63		81
64	Although the module will work with in the presence of other threads, it is	82	Although the module will work with in the presence of other (Perl-)
65	currently not reentrant, so use appropriate locking yourself, always call	83	threads, it is currently not reentrant in any way, so use appropriate
66	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	84	locking yourself, always call C<poll_cb> from within the same thread, or
67	C<aio_> functions) recursively.	85	never call C<poll_cb> (or other C<aio_> functions) recursively.
		86
		87	=head2 EXAMPLE
		88
		89	This is a simple example that uses the Event module and loads
		90	F</etc/passwd> asynchronously:
		91
		92	use Fcntl;
		93	use Event;
		94	use IO::AIO;
		95
		96	# register the IO::AIO callback with Event
		97	Event->io (fd => IO::AIO::poll_fileno,
		98	poll => 'r',
		99	cb => \&IO::AIO::poll_cb);
		100
		101	# queue the request to open /etc/passwd
		102	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		103	my $fh = $_[0]
		104	or die "error while opening: $!";
		105
		106	# stat'ing filehandles is generally non-blocking
		107	my $size = -s $fh;
		108
		109	# queue a request to read the file
		110	my $contents;
		111	aio_read $fh, 0, $size, $contents, 0, sub {
		112	$_[0] == $size
		113	or die "short read: $!";
		114
		115	close $fh;
		116
		117	# file contents now in $contents
		118	print $contents;
		119
		120	# exit event loop and program
		121	Event::unloop;
		122	};
		123	};
		124
		125	# possibly queue up other requests, or open GUI windows,
		126	# check for sockets etc. etc.
		127
		128	# process events as long as there are some:
		129	Event::loop;
		130
		131	=head1 REQUEST ANATOMY AND LIFETIME
		132
		133	Every C<aio_*> function creates a request. which is a C data structure not
		134	directly visible to Perl.
		135
		136	If called in non-void context, every request function returns a Perl
		137	object representing the request. In void context, nothing is returned,
		138	which saves a bit of memory.
		139
		140	The perl object is a fairly standard ref-to-hash object. The hash contents
		141	are not used by IO::AIO so you are free to store anything you like in it.
		142
		143	During their existance, aio requests travel through the following states,
		144	in order:
		145
		146	=over 4
		147
		148	=item ready
		149
		150	Immediately after a request is created it is put into the ready state,
		151	waiting for a thread to execute it.
		152
		153	=item execute
		154
		155	A thread has accepted the request for processing and is currently
		156	executing it (e.g. blocking in read).
		157
		158	=item pending
		159
		160	The request has been executed and is waiting for result processing.
		161
		162	While request submission and execution is fully asynchronous, result
		163	processing is not and relies on the perl interpreter calling C<poll_cb>
		164	(or another function with the same effect).
		165
		166	=item result
		167
		168	The request results are processed synchronously by C<poll_cb>.
		169
		170	The C<poll_cb> function will process all outstanding aio requests by
		171	calling their callbacks, freeing memory associated with them and managing
		172	any groups they are contained in.
		173
		174	=item done
		175
		176	Request has reached the end of its lifetime and holds no resources anymore
		177	(except possibly for the Perl object, but its connection to the actual
		178	aio request is severed and calling its methods will either do nothing or
		179	result in a runtime error).
		180
		181	=back
68		182
69	=cut	183	=cut
70		184
71	package IO::AIO;	185	package IO::AIO;
72		186
…		…
74	use strict 'vars';	188	use strict 'vars';
75		189
76	use base 'Exporter';	190	use base 'Exporter';
77		191
78	BEGIN {	192	BEGIN {
79	our $VERSION = '2.0';	193	our $VERSION = '2.1';
80		194
81	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	195	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
82	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	196	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
83	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	197	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
84	aio_group aio_nop);	198	aio_copy aio_group aio_nop aio_mknod);
85	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	199	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
86	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	200	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
87	min_parallel max_parallel max_outstanding nreqs);	201	min_parallel max_parallel max_idle
		202	nreqs nready npending nthreads
		203	max_poll_time max_poll_reqs);
88		204
89	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	205	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
90		206
91	require XSLoader;	207	require XSLoader;
92	XSLoader::load ("IO::AIO", $VERSION);	208	XSLoader::load ("IO::AIO", $VERSION);
93	}	209	}
94		210
95	=head1 FUNCTIONS	211	=head1 FUNCTIONS
96		212
97	=head2 AIO FUNCTIONS	213	=head2 AIO REQUEST FUNCTIONS
98		214
99	All the C<aio_*> calls are more or less thin wrappers around the syscall	215	All the C<aio_*> calls are more or less thin wrappers around the syscall
100	with the same name (sans C<aio_>). The arguments are similar or identical,	216	with the same name (sans C<aio_>). The arguments are similar or identical,
101	and they all accept an additional (and optional) C<$callback> argument	217	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	218	which must be a code reference. This code reference will get called with
…		…
105	syscall has been executed asynchronously.	221	syscall has been executed asynchronously.
106		222
107	All functions expecting a filehandle keep a copy of the filehandle	223	All functions expecting a filehandle keep a copy of the filehandle
108	internally until the request has finished.	224	internally until the request has finished.
109		225
110	All requests return objects of type L<IO::AIO::REQ> that allow further	226	All functions return request objects of type L<IO::AIO::REQ> that allow
111	manipulation of those requests while they are in-flight.	227	further manipulation of those requests while they are in-flight.
112		228
113	The pathnames you pass to these routines I<must> be absolute and	229	The pathnames you pass to these routines I<must> be absolute and
114	encoded in byte form. The reason for the former is that at the time the	230	encoded as octets. The reason for the former is that at the time the
115	request is being executed, the current working directory could have	231	request is being executed, the current working directory could have
116	changed. Alternatively, you can make sure that you never change the	232	changed. Alternatively, you can make sure that you never change the
117	current working directory.	233	current working directory anywhere in the program and then use relative
		234	paths.
118		235
119	To encode pathnames to byte form, either make sure you either: a)	236	To encode pathnames as octets, either make sure you either: a) always pass
120	always pass in filenames you got from outside (command line, readdir	237	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	238	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	239	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)	240	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
124	use something else.	241	use something else to ensure your scalar has the correct contents.
		242
		243	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		244	handles correctly wether it is set or not.
125		245
126	=over 4	246	=over 4
		247
		248	=item $prev_pri = aioreq_pri [$pri]
		249
		250	Returns the priority value that would be used for the next request and, if
		251	C<$pri> is given, sets the priority for the next aio request.
		252
		253	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		254	and C<4>, respectively. Requests with higher priority will be serviced
		255	first.
		256
		257	The priority will be reset to C<0> after each call to one of the C<aio_*>
		258	functions.
		259
		260	Example: open a file with low priority, then read something from it with
		261	higher priority so the read request is serviced before other low priority
		262	open requests (potentially spamming the cache):
		263
		264	aioreq_pri -3;
		265	aio_open ..., sub {
		266	return unless $_[0];
		267
		268	aioreq_pri -2;
		269	aio_read $_[0], ..., sub {
		270	...
		271	};
		272	};
		273
		274	=item aioreq_nice $pri_adjust
		275
		276	Similar to C<aioreq_pri>, but subtracts the given value from the current
		277	priority, so the effect is cumulative.
127		278
128	=item aio_open $pathname, $flags, $mode, $callback->($fh)	279	=item aio_open $pathname, $flags, $mode, $callback->($fh)
129		280
130	Asynchronously open or create a file and call the callback with a newly	281	Asynchronously open or create a file and call the callback with a newly
131	created filehandle for the file.	282	created filehandle for the file.
…		…
181		332
182	aio_read $fh, 7, 15, $buffer, 0, sub {	333	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] > 0 or die "read error: $!";	334	$_[0] > 0 or die "read error: $!";
184	print "read $_[0] bytes: <$buffer>\n";	335	print "read $_[0] bytes: <$buffer>\n";
185	};	336	};
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		337
257	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	338	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
258		339
259	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	340	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
260	reading at byte offset C<$in_offset>, and starts writing at the current	341	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
316	=item aio_unlink $pathname, $callback->($status)	397	=item aio_unlink $pathname, $callback->($status)
317		398
318	Asynchronously unlink (delete) a file and call the callback with the	399	Asynchronously unlink (delete) a file and call the callback with the
319	result code.	400	result code.
320		401
		402	=item aio_mknod $path, $mode, $dev, $callback->($status)
		403
		404	[EXPERIMENTAL]
		405
		406	Asynchronously create a device node (or fifo). See mknod(2).
		407
		408	The only (POSIX-) portable way of calling this function is:
		409
		410	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		411
321	=item aio_link $srcpath, $dstpath, $callback->($status)	412	=item aio_link $srcpath, $dstpath, $callback->($status)
322		413
323	Asynchronously create a new link to the existing object at C<$srcpath> at	414	Asynchronously create a new link to the existing object at C<$srcpath> at
324	the path C<$dstpath> and call the callback with the result code.	415	the path C<$dstpath> and call the callback with the result code.
325		416
…		…
345	sorted, and will B<NOT> include the C<.> and C<..> entries.	436	sorted, and will B<NOT> include the C<.> and C<..> entries.
346		437
347	The callback a single argument which is either C<undef> or an array-ref	438	The callback a single argument which is either C<undef> or an array-ref
348	with the filenames.	439	with the filenames.
349		440
		441	=item aio_copy $srcpath, $dstpath, $callback->($status)
		442
		443	Try to copy the I<file> (directories not supported as either source or
		444	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		445	the C<0> (error) or C<-1> ok.
		446
		447	This is a composite request that it creates the destination file with
		448	mode 0200 and copies the contents of the source file into it using
		449	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		450	uid/gid, in that order.
		451
		452	If an error occurs, the partial destination file will be unlinked, if
		453	possible, except when setting atime, mtime, access mode and uid/gid, where
		454	errors are being ignored.
		455
		456	=cut
		457
		458	sub aio_copy($$;$) {
		459	my ($src, $dst, $cb) = @_;
		460
		461	my $pri = aioreq_pri;
		462	my $grp = aio_group $cb;
		463
		464	aioreq_pri $pri;
		465	add $grp aio_open $src, O_RDONLY, 0, sub {
		466	if (my $src_fh = $_[0]) {
		467	my @stat = stat $src_fh;
		468
		469	aioreq_pri $pri;
		470	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		471	if (my $dst_fh = $_[0]) {
		472	aioreq_pri $pri;
		473	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		474	if ($_[0] == $stat[7]) {
		475	$grp->result (0);
		476	close $src_fh;
		477
		478	# those should not normally block. should. should.
		479	utime $stat[8], $stat[9], $dst;
		480	chmod $stat[2] & 07777, $dst_fh;
		481	chown $stat[4], $stat[5], $dst_fh;
		482	close $dst_fh;
		483	} else {
		484	$grp->result (-1);
		485	close $src_fh;
		486	close $dst_fh;
		487
		488	aioreq $pri;
		489	add $grp aio_unlink $dst;
		490	}
		491	};
		492	} else {
		493	$grp->result (-1);
		494	}
		495	},
		496
		497	} else {
		498	$grp->result (-1);
		499	}
		500	};
		501
		502	$grp
		503	}
		504
		505	=item aio_move $srcpath, $dstpath, $callback->($status)
		506
		507	Try to move the I<file> (directories not supported as either source or
		508	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		509	the C<0> (error) or C<-1> ok.
		510
		511	This is a composite request that tries to rename(2) the file first. If
		512	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		513	that is successful, unlinking the C<$srcpath>.
		514
		515	=cut
		516
		517	sub aio_move($$;$) {
		518	my ($src, $dst, $cb) = @_;
		519
		520	my $pri = aioreq_pri;
		521	my $grp = aio_group $cb;
		522
		523	aioreq_pri $pri;
		524	add $grp aio_rename $src, $dst, sub {
		525	if ($_[0] && $! == EXDEV) {
		526	aioreq_pri $pri;
		527	add $grp aio_copy $src, $dst, sub {
		528	$grp->result ($_[0]);
		529
		530	if (!$_[0]) {
		531	aioreq_pri $pri;
		532	add $grp aio_unlink $src;
		533	}
		534	};
		535	} else {
		536	$grp->result ($_[0]);
		537	}
		538	};
		539
		540	$grp
		541	}
		542
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	543	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		544
352	[EXPERIMENTAL due to internal aio_group use]
353
354	Scans a directory (similar to C<aio_readdir>) but additionally tries to	545	Scans a directory (similar to C<aio_readdir>) but additionally tries to
355	separate the entries of directory C<$path> into two sets of names, ones	546	efficiently separate the entries of directory C<$path> into two sets of
356	you can recurse into (directories or links to them), and ones you cannot	547	names, directories you can recurse into (directories), and ones you cannot
357	recurse into (everything else).	548	recurse into (everything else, including symlinks to directories).
358		549
359	C<aio_scandir> is a composite request that creates of many sub requests_	550	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	551	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	this function generates. If it is C<< <= 0 >>, then a suitable default	552	this function generates. If it is C<< <= 0 >>, then a suitable default
362	will be chosen (currently 6).	553	will be chosen (currently 4).
363		554
364	On error, the callback is called without arguments, otherwise it receives	555	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	556	two array-refs with path-relative entry names.
366		557
367	Example:	558	Example:
…		…
404	=cut	595	=cut
405		596
406	sub aio_scandir($$$) {	597	sub aio_scandir($$$) {
407	my ($path, $maxreq, $cb) = @_;	598	my ($path, $maxreq, $cb) = @_;
408		599
		600	my $pri = aioreq_pri;
		601
409	my $grp = aio_group $cb;	602	my $grp = aio_group $cb;
410		603
411	$maxreq = 6 if $maxreq <= 0;	604	$maxreq = 4 if $maxreq <= 0;
412		605
413	# stat once	606	# stat once
		607	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	608	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	609	return $grp->result () if $_[0];
416	my $now = time;	610	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	611	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		612
419	# read the directory entries	613	# read the directory entries
		614	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	615	add $grp aio_readdir $path, sub {
421	my $entries = shift	616	my $entries = shift
422	or return $grp->result ();	617	or return $grp->result ();
423		618
424	# stat the dir another time	619	# stat the dir another time
		620	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	621	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	622	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		623
428	my $ndirs;	624	my $ndirs;
429		625
…		…
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	640	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];	641	@$entries];
446		642
447	my (@dirs, @nondirs);	643	my (@dirs, @nondirs);
448		644
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	645	my $statgrp = add $grp aio_group sub {
		646	$grp->result (\@dirs, \@nondirs);
		647	};
453		648
454	$schedcb = sub {	649	limit $statgrp $maxreq;
455	if (@$entries) {	650	feed $statgrp sub {
456	if ($nreq < $maxreq) {	651	return unless @$entries;
457	my $ent = pop @$entries;	652	my $entry = pop @$entries;
		653
		654	aioreq_pri $pri;
		655	add $statgrp aio_stat "$path/$entry/.", sub {
		656	if ($_[0] < 0) {
		657	push @nondirs, $entry;
		658	} else {
		659	# need to check for real directory
		660	aioreq_pri $pri;
		661	add $statgrp aio_lstat "$path/$entry", sub {
		662	if (-d _) {
		663	push @dirs, $entry;
		664
		665	unless (--$ndirs) {
		666	push @nondirs, @$entries;
		667	feed $statgrp;
		668	}
		669	} else {
		670	push @nondirs, $entry;
		671	}
458	$nreq++;	672	}
459	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
460	}	673	}
461	} elsif (!$nreq) {
462	# finished
463	$statgrp->cancel;
464	undef $statcb;
465	undef $schedcb;
466	$grp->result (\@dirs, \@nondirs);
467	}	674	};
468	};	675	};
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	};	676	};
499	};	677	};
500	};	678	};
501		679
502	$grp	680	$grp
…		…
515	If this call isn't available because your OS lacks it or it couldn't be	693	If this call isn't available because your OS lacks it or it couldn't be
516	detected, it will be emulated by calling C<fsync> instead.	694	detected, it will be emulated by calling C<fsync> instead.
517		695
518	=item aio_group $callback->(...)	696	=item aio_group $callback->(...)
519		697
520	[EXPERIMENTAL]
521
522	This is a very special aio request: Instead of doing something, it is a	698	This is a very special aio request: Instead of doing something, it is a
523	container for other aio requests, which is useful if you want to bundle	699	container for other aio requests, which is useful if you want to bundle
524	many requests into a single, composite, request.	700	many requests into a single, composite, request with a definite callback
		701	and the ability to cancel the whole request with its subrequests.
525		702
526	Returns an object of class L<IO::AIO::GRP>. See its documentation below	703	Returns an object of class L<IO::AIO::GRP>. See its documentation below
527	for more info.	704	for more info.
528		705
529	Example:	706	Example:
…		…
548	phase and still requires a worker thread. Thus, the callback will not	725	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	726	be executed immediately but only after other requests in the queue have
550	entered their execution phase. This can be used to measure request	727	entered their execution phase. This can be used to measure request
551	latency.	728	latency.
552		729
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	730	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
554		731
555	Mainly used for debugging and benchmarking, this aio request puts one of	732	Mainly used for debugging and benchmarking, this aio request puts one of
556	the request workers to sleep for the given time.	733	the request workers to sleep for the given time.
557		734
558	While it is theoretically handy to have simple I/O scheduling requests	735	While it is theoretically handy to have simple I/O scheduling requests
559	like sleep and file handle readable/writable, the overhead this creates	736	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	737	immense (it blocks a thread for a long time) so do not use this function
561	under artificial I/O pressure.	738	except to put your application under artificial I/O pressure.
562		739
563	=back	740	=back
564		741
565	=head2 IO::AIO::REQ CLASS	742	=head2 IO::AIO::REQ CLASS
566		743
567	All non-aggregate C<aio_*> functions return an object of this class when	744	All non-aggregate C<aio_*> functions return an object of this class when
568	called in non-void context.	745	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		746
578	=over 4	747	=over 4
579		748
580	=item cancel $req	749	=item cancel $req
581		750
…		…
635	=item * They can also can also be added to other IO::AIO::GRP objects.	804	=item * They can also can also be added to other IO::AIO::GRP objects.
636		805
637	=item * You must not add requests to a group from within the group callback (or	806	=item * You must not add requests to a group from within the group callback (or
638	any later time).	807	any later time).
639		808
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	809	=back
645		810
646	Their lifetime, simplified, looks like this: when they are empty, they	811	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	812	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	813	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	828	be added, including other groups, as long as you do not create circular
664	dependencies.	829	dependencies.
665		830
666	Returns all its arguments.	831	Returns all its arguments.
667		832
		833	=item $grp->cancel_subs
		834
		835	Cancel all subrequests and clears any feeder, but not the group request
		836	itself. Useful when you queued a lot of events but got a result early.
		837
668	=item $grp->result (...)	838	=item $grp->result (...)
669		839
670	Set the result value(s) that will be passed to the group callback when all	840	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.	841	subrequests have finished and set thre groups errno to the current value
		842	of errno (just like calling C<errno> without an error number). By default,
		843	no argument will be passed and errno is zero.
		844
		845	=item $grp->errno ([$errno])
		846
		847	Sets the group errno value to C<$errno>, or the current value of errno
		848	when the argument is missing.
		849
		850	Every aio request has an associated errno value that is restored when
		851	the callback is invoked. This method lets you change this value from its
		852	default (0).
		853
		854	Calling C<result> will also set errno, so make sure you either set C<$!>
		855	before the call to C<result>, or call c<errno> after it.
672		856
673	=item feed $grp $callback->($grp)	857	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		858
677	Sets a feeder/generator on this group: every group can have an attached	859	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,	860	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,	861	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	862	this might starve other requests for a potentially long time. For
681	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	863	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
682	requests, delaying any later requests for a long time.	864	requests, delaying any later requests for a long time.
683		865
684	To avoid this, and allow incremental generation of requests, you can	866	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	867	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>,	868	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	869	below) requests active in the group itself and is expected to queue more
688	requests.	870	requests.
689		871
690	The feed can queue as many requests as it likes (i.e. C<add> does not	872	The feed callback can queue as many requests as it likes (i.e. C<add> does
691	impose any limits).	873	not impose any limits).
692		874
693	If the feed does not queue more requests when called, it will be	875	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	876	automatically removed from the group.
695		877
696	If the feed limit is C<0>, it will be set to C<2> automatically.	878	If the feed limit is C<0>, it will be set to C<2> automatically.
…		…
698	Example:	880	Example:
699		881
700	# stat all files in @files, but only ever use four aio requests concurrently:	882	# stat all files in @files, but only ever use four aio requests concurrently:
701		883
702	my $grp = aio_group sub { print "finished\n" };	884	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	885	limit $grp 4;
704	feed $grp sub {	886	feed $grp sub {
705	my $file = pop @files	887	my $file = pop @files
706	or return;	888	or return;
707		889
708	add $grp aio_stat $file, sub { ... };	890	add $grp aio_stat $file, sub { ... };
709	};	891	};
710		892
711	=item feed_limit $grp $num	893	=item limit $grp $num
712		894
713	Sets the feeder limit for the group: The feeder will be called whenever	895	Sets the feeder limit for the group: The feeder will be called whenever
714	the group contains less than this many requests.	896	the group contains less than this many requests.
715		897
716	Setting the limit to C<0> will pause the feeding process.	898	Setting the limit to C<0> will pause the feeding process.
717		899
718	=back	900	=back
719		901
720	=head2 SUPPORT FUNCTIONS	902	=head2 SUPPORT FUNCTIONS
		903
		904	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
721		905
722	=over 4	906	=over 4
723		907
724	=item $fileno = IO::AIO::poll_fileno	908	=item $fileno = IO::AIO::poll_fileno
725		909
…		…
730		914
731	See C<poll_cb> for an example.	915	See C<poll_cb> for an example.
732		916
733	=item IO::AIO::poll_cb	917	=item IO::AIO::poll_cb
734		918
735	Process all outstanding events on the result pipe. You have to call this	919	Process some outstanding events on the result pipe. You have to call this
736	regularly. Returns the number of events processed. Returns immediately	920	regularly. Returns the number of events processed. Returns immediately
737	when no events are outstanding.	921	when no events are outstanding. The amount of events processed depends on
		922	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		923
		924	If not all requests were processed for whatever reason, the filehandle
		925	will still be ready when C<poll_cb> returns.
738		926
739	Example: Install an Event watcher that automatically calls	927	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	928	IO::AIO::poll_cb with high priority:
741		929
742	Event->io (fd => IO::AIO::poll_fileno,	930	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	931	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	932	cb => \&IO::AIO::poll_cb);
745		933
		934	=item IO::AIO::max_poll_reqs $nreqs
		935
		936	=item IO::AIO::max_poll_time $seconds
		937
		938	These set the maximum number of requests (default C<0>, meaning infinity)
		939	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		940	the maximum amount of time (default C<0>, meaning infinity) spent in
		941	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		942	of time C<poll_cb> is allowed to use).
		943
		944	Setting these is useful if you want to ensure some level of
		945	interactiveness when perl is not fast enough to process all requests in
		946	time.
		947
		948	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		949
		950	Example: Install an Event watcher that automatically calls
		951	IO::AIO::poll_some with low priority, to ensure that other parts of the
		952	program get the CPU sometimes even under high AIO load.
		953
		954	# try not to spend much more than 0.1s in poll_cb
		955	IO::AIO::max_poll_time 0.1;
		956
		957	# use a low priority so other tasks have priority
		958	Event->io (fd => IO::AIO::poll_fileno,
		959	poll => 'r', nice => 1,
		960	cb => &IO::AIO::poll_cb);
		961
746	=item IO::AIO::poll_wait	962	=item IO::AIO::poll_wait
747		963
748	Wait till the result filehandle becomes ready for reading (simply does a	964	Wait till the result filehandle becomes ready for reading (simply does a
749	C<select> on the filehandle. This is useful if you want to synchronously wait	965	C<select> on the filehandle. This is useful if you want to synchronously
750	for some requests to finish).	966	wait for some requests to finish).
751		967
752	See C<nreqs> for an example.	968	See C<nreqs> for an example.
753		969
		970	=item IO::AIO::poll
		971
		972	Waits until some requests have been handled.
		973
		974	Strictly equivalent to:
		975
		976	IO::AIO::poll_wait, IO::AIO::poll_cb
		977	if IO::AIO::nreqs;
		978
754	=item IO::AIO::nreqs	979	=item IO::AIO::flush
755		980
756	Returns the number of requests currently outstanding (i.e. for which their	981	Wait till all outstanding AIO requests have been handled.
757	callback has not been invoked yet).
758		982
759	Example: wait till there are no outstanding requests anymore:	983	Strictly equivalent to:
760		984
761	IO::AIO::poll_wait, IO::AIO::poll_cb	985	IO::AIO::poll_wait, IO::AIO::poll_cb
762	while IO::AIO::nreqs;	986	while IO::AIO::nreqs;
763		987
764	=item IO::AIO::flush	988	=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		989
782	=item IO::AIO::min_parallel $nthreads	990	=item IO::AIO::min_parallel $nthreads
783		991
784	Set the minimum number of AIO threads to C<$nthreads>. The current	992	Set the minimum number of AIO threads to C<$nthreads>. The current
785	default is C<8>, which means eight asynchronous operations can execute	993	default is C<8>, which means eight asynchronous operations can execute
786	concurrently at any one time (the number of outstanding requests,	994	concurrently at any one time (the number of outstanding requests,
787	however, is unlimited).	995	however, is unlimited).
788		996
789	IO::AIO starts threads only on demand, when an AIO request is queued and	997	IO::AIO starts threads only on demand, when an AIO request is queued and
790	no free thread exists.	998	no free thread exists. Please note that queueing up a hundred requests can
		999	create demand for a hundred threads, even if it turns out that everything
		1000	is in the cache and could have been processed faster by a single thread.
791		1001
792	It is recommended to keep the number of threads relatively low, as some	1002	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	1003	Linux kernel versions will scale negatively with the number of threads
794	(higher parallelity => MUCH higher latency). With current Linux 2.6	1004	(higher parallelity => MUCH higher latency). With current Linux 2.6
795	versions, 4-32 threads should be fine.	1005	versions, 4-32 threads should be fine.
…		…
809	This module automatically runs C<max_parallel 0> at program end, to ensure	1019	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.	1020	that all threads are killed and that there are no outstanding requests.
811		1021
812	Under normal circumstances you don't need to call this function.	1022	Under normal circumstances you don't need to call this function.
813		1023
		1024	=item IO::AIO::max_idle $nthreads
		1025
		1026	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1027	threads that did not get a request to process within 10 seconds). That
		1028	means if a thread becomes idle while C<$nthreads> other threads are also
		1029	idle, it will free its resources and exit.
		1030
		1031	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1032	to allow for extremely high load situations, but want to free resources
		1033	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1034
		1035	The default is probably ok in most situations, especially if thread
		1036	creation is fast. If thread creation is very slow on your system you might
		1037	want to use larger values.
		1038
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1039	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
815		1040
816	[DEPRECATED]	1041	This is a very bad function to use in interactive programs because it
		1042	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1043	use an C<aio_group> together with a feed callback.
817		1044
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1045	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	1046	to queue up more than this number of requests, the next call to the
820	some requests have been handled.	1047	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1048	function will block until the limit is no longer exceeded.
821		1049
822	The default is very large, so normally there is no practical limit. If you	1050	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	1051	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		1052
826	This function does not work well together with C<aio_group>'s, and their	1053	You can still queue as many requests as you want. Therefore,
827	feeder interface is better suited to limiting concurrency, so do not use	1054	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
828	this function.	1055	as a stop gap to shield against fatal memory overflow (with large values).
829		1056
830	Under normal circumstances you don't need to call this function.	1057	=head3 STATISTICAL INFORMATION
		1058
		1059	=item IO::AIO::nreqs
		1060
		1061	Returns the number of requests currently in the ready, execute or pending
		1062	states (i.e. for which their callback has not been invoked yet).
		1063
		1064	Example: wait till there are no outstanding requests anymore:
		1065
		1066	IO::AIO::poll_wait, IO::AIO::poll_cb
		1067	while IO::AIO::nreqs;
		1068
		1069	=item IO::AIO::nready
		1070
		1071	Returns the number of requests currently in the ready state (not yet
		1072	executed).
		1073
		1074	=item IO::AIO::npending
		1075
		1076	Returns the number of requests currently in the pending state (executed,
		1077	but not yet processed by poll_cb).
831		1078
832	=back	1079	=back
833		1080
834	=cut	1081	=cut
835		1082
…		…
850	}	1097	}
851		1098
852	min_parallel 8;	1099	min_parallel 8;
853		1100
854	END {	1101	END {
855	max_parallel 0;	1102	min_parallel 1;
856	}	1103	flush;
		1104	};
857		1105
858	1;	1106	1;
859		1107
860	=head2 FORK BEHAVIOUR	1108	=head2 FORK BEHAVIOUR
861		1109
862	This module should do "the right thing" when the process using it forks:	1110	This module should do "the right thing" when the process using it forks:
863		1111
864	Before the fork, IO::AIO enters a quiescent state where no requests	1112	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	1113	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	1114	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	1115	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	1116	(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	1117	parent). Threads will be started on demand until the limit set in the
870	parent process has been reached again.	1118	parent process has been reached again.
871		1119
872	In short: the parent will, after a short pause, continue as if fork had	1120	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	1121	not been called, while the child will act as if IO::AIO has not been used
874	yet.	1122	yet.
875		1123
876	=head2 MEMORY USAGE	1124	=head2 MEMORY USAGE
877		1125
		1126	Per-request usage:
		1127
878	Each aio request uses - depending on your architecture - around 128 bytes	1128	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	1129	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	1130	a few hundred bytes), readdir requires a result buffer and so on. Perl
881	also be locked.	1131	scalars and other data passed into aio requests will also be locked and
		1132	will consume memory till the request has entered the done state.
882		1133
883	This is now awfully much, so queuing lots of requests is not usually a	1134	This is now awfully much, so queuing lots of requests is not usually a
884	problem.	1135	problem.
885		1136
886	Each thread needs a stack area which is usually around 16k, sometimes much	1137	Per-thread usage:
887	larger, depending on the OS.	1138
		1139	In the execution phase, some aio requests require more memory for
		1140	temporary buffers, and each thread requires a stack and other data
		1141	structures (usually around 16k-128k, depending on the OS).
		1142
		1143	=head1 KNOWN BUGS
		1144
		1145	Known bugs will be fixed in the next release.
888		1146
889	=head1 SEE ALSO	1147	=head1 SEE ALSO
890		1148
891	L<Coro>, L<Linux::AIO> (obsolete).	1149	L<Coro::AIO>.
892		1150
893	=head1 AUTHOR	1151	=head1 AUTHOR
894		1152
895	Marc Lehmann <schmorp@schmorp.de>	1153	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1154	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 1.88 by root, Sun Oct 29 01:50:29 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 1.88 by root, Sun Oct 29 01:50:29 2006 UTC