[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 1.89 by root, Sun Oct 29 11:03:18 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 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
56	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
57	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
58	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
59	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
60	on many operating systems. However, they are often not well-supported	76	functions available on many operating systems. However, they are often
61	(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
62	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
63	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.
64		81
65	Although the module will work with in the presence of other threads,	82	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	83	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	84	locking yourself, always call C<poll_cb> from within the same thread, or
68	call C<poll_cb> (or other 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
69		182
70	=cut	183	=cut
71		184
72	package IO::AIO;	185	package IO::AIO;
73		186
…		…
75	use strict 'vars';	188	use strict 'vars';
76		189
77	use base 'Exporter';	190	use base 'Exporter';
78		191
79	BEGIN {	192	BEGIN {
80	our $VERSION = '2.0';	193	our $VERSION = '2.1';
81		194
82	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
83	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
84	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
85	aio_group aio_nop);	198	aio_copy aio_group aio_nop aio_mknod);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	199	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	200	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	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);
89		204
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	205	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		206
92	require XSLoader;	207	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	208	XSLoader::load ("IO::AIO", $VERSION);
94	}	209	}
95		210
96	=head1 FUNCTIONS	211	=head1 FUNCTIONS
97		212
98	=head2 AIO FUNCTIONS	213	=head2 AIO REQUEST FUNCTIONS
99		214
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	215	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	216	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	217	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	218	which must be a code reference. This code reference will get called with
…		…
106	syscall has been executed asynchronously.	221	syscall has been executed asynchronously.
107		222
108	All functions expecting a filehandle keep a copy of the filehandle	223	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	224	internally until the request has finished.
110		225
111	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
112	manipulation of those requests while they are in-flight.	227	further manipulation of those requests while they are in-flight.
113		228
114	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
115	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
116	request is being executed, the current working directory could have	231	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	232	changed. Alternatively, you can make sure that you never change the
118	current working directory.	233	current working directory anywhere in the program and then use relative
		234	paths.
119		235
120	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
121	always pass in filenames you got from outside (command line, readdir	237	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	238	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	239	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)	240	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	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.
126		245
127	=over 4	246	=over 4
128		247
129	=item aioreq_pri $pri	248	=item $prev_pri = aioreq_pri [$pri]
130		249
131	Sets the priority for the next aio request. The default priority	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
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	253	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	254	and C<4>, respectively. Requests with higher priority will be serviced
		255	first.
134		256
135	The priority will be reset to C<0> after each call to one of the C<aio_>	257	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	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.
137		278
138	=item aio_open $pathname, $flags, $mode, $callback->($fh)	279	=item aio_open $pathname, $flags, $mode, $callback->($fh)
139		280
140	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
141	created filehandle for the file.	282	created filehandle for the file.
…		…
191		332
192	aio_read $fh, 7, 15, $buffer, 0, sub {	333	aio_read $fh, 7, 15, $buffer, 0, sub {
193	$_[0] > 0 or die "read error: $!";	334	$_[0] > 0 or die "read error: $!";
194	print "read $_[0] bytes: <$buffer>\n";	335	print "read $_[0] bytes: <$buffer>\n";
195	};	336	};
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		337
267	=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)
268		339
269	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
270	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
…		…
326	=item aio_unlink $pathname, $callback->($status)	397	=item aio_unlink $pathname, $callback->($status)
327		398
328	Asynchronously unlink (delete) a file and call the callback with the	399	Asynchronously unlink (delete) a file and call the callback with the
329	result code.	400	result code.
330		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
331	=item aio_link $srcpath, $dstpath, $callback->($status)	412	=item aio_link $srcpath, $dstpath, $callback->($status)
332		413
333	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
334	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.
335		416
…		…
355	sorted, and will B<NOT> include the C<.> and C<..> entries.	436	sorted, and will B<NOT> include the C<.> and C<..> entries.
356		437
357	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
358	with the filenames.	439	with the filenames.
359		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
360	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	543	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
361		544
362	[EXPERIMENTAL due to internal aio_group use]
363
364	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
365	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
366	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
367	recurse into (everything else).	548	recurse into (everything else, including symlinks to directories).
368		549
369	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_
370	C<$maxreq> specifies the maximum number of outstanding aio requests that	551	C<$maxreq> specifies the maximum number of outstanding aio requests that
371	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
372	will be chosen (currently 6).	553	will be chosen (currently 4).
373		554
374	On error, the callback is called without arguments, otherwise it receives	555	On error, the callback is called without arguments, otherwise it receives
375	two array-refs with path-relative entry names.	556	two array-refs with path-relative entry names.
376		557
377	Example:	558	Example:
…		…
414	=cut	595	=cut
415		596
416	sub aio_scandir($$$) {	597	sub aio_scandir($$$) {
417	my ($path, $maxreq, $cb) = @_;	598	my ($path, $maxreq, $cb) = @_;
418		599
		600	my $pri = aioreq_pri;
		601
419	my $grp = aio_group $cb;	602	my $grp = aio_group $cb;
420		603
421	$maxreq = 6 if $maxreq <= 0;	604	$maxreq = 4 if $maxreq <= 0;
422		605
423	# stat once	606	# stat once
		607	aioreq_pri $pri;
424	add $grp aio_stat $path, sub {	608	add $grp aio_stat $path, sub {
425	return $grp->result () if $_[0];	609	return $grp->result () if $_[0];
426	my $now = time;	610	my $now = time;
427	my $hash1 = join ":", (stat _)[0,1,3,7,9];	611	my $hash1 = join ":", (stat _)[0,1,3,7,9];
428		612
429	# read the directory entries	613	# read the directory entries
		614	aioreq_pri $pri;
430	add $grp aio_readdir $path, sub {	615	add $grp aio_readdir $path, sub {
431	my $entries = shift	616	my $entries = shift
432	or return $grp->result ();	617	or return $grp->result ();
433		618
434	# stat the dir another time	619	# stat the dir another time
		620	aioreq_pri $pri;
435	add $grp aio_stat $path, sub {	621	add $grp aio_stat $path, sub {
436	my $hash2 = join ":", (stat _)[0,1,3,7,9];	622	my $hash2 = join ":", (stat _)[0,1,3,7,9];
437		623
438	my $ndirs;	624	my $ndirs;
439		625
…		…
454	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	640	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
455	@$entries];	641	@$entries];
456		642
457	my (@dirs, @nondirs);	643	my (@dirs, @nondirs);
458		644
459	my ($statcb, $schedcb);
460	my $nreq = 0;
461
462	my $statgrp = add $grp aio_group;	645	my $statgrp = add $grp aio_group sub {
		646	$grp->result (\@dirs, \@nondirs);
		647	};
463		648
464	$schedcb = sub {	649	limit $statgrp $maxreq;
465	if (@$entries) {	650	feed $statgrp sub {
466	if ($nreq < $maxreq) {	651	return unless @$entries;
467	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	}
468	$nreq++;	672	}
469	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
470	}	673	}
471	} elsif (!$nreq) {
472	# finished
473	$statgrp->cancel;
474	undef $statcb;
475	undef $schedcb;
476	$grp->result (\@dirs, \@nondirs);
477	}	674	};
478	};	675	};
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	};	676	};
509	};	677	};
510	};	678	};
511		679
512	$grp	680	$grp
…		…
525	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
526	detected, it will be emulated by calling C<fsync> instead.	694	detected, it will be emulated by calling C<fsync> instead.
527		695
528	=item aio_group $callback->(...)	696	=item aio_group $callback->(...)
529		697
530	[EXPERIMENTAL]
531
532	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
533	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
534	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.
535		702
536	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
537	for more info.	704	for more info.
538		705
539	Example:	706	Example:
…		…
558	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
559	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
560	entered their execution phase. This can be used to measure request	727	entered their execution phase. This can be used to measure request
561	latency.	728	latency.
562		729
563	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	730	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
564		731
565	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
566	the request workers to sleep for the given time.	733	the request workers to sleep for the given time.
567		734
568	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
569	like sleep and file handle readable/writable, the overhead this creates	736	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	737	immense (it blocks a thread for a long time) so do not use this function
571	under artificial I/O pressure.	738	except to put your application under artificial I/O pressure.
572		739
573	=back	740	=back
574		741
575	=head2 IO::AIO::REQ CLASS	742	=head2 IO::AIO::REQ CLASS
576		743
577	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
578	called in non-void context.	745	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		746
588	=over 4	747	=over 4
589		748
590	=item cancel $req	749	=item cancel $req
591		750
…		…
645	=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.
646		805
647	=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
648	any later time).	807	any later time).
649		808
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	809	=back
655		810
656	Their lifetime, simplified, looks like this: when they are empty, they	811	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	812	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	813	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	828	be added, including other groups, as long as you do not create circular
674	dependencies.	829	dependencies.
675		830
676	Returns all its arguments.	831	Returns all its arguments.
677		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
678	=item $grp->result (...)	838	=item $grp->result (...)
679		839
680	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
681	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.
682		856
683	=item feed $grp $callback->($grp)	857	=item feed $grp $callback->($grp)
684
685	[VERY EXPERIMENTAL]
686		858
687	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
688	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,
689	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,
690	this might starve other requests for a potentially long time. For	862	this might starve other requests for a potentially long time. For
…		…
727		899
728	=back	900	=back
729		901
730	=head2 SUPPORT FUNCTIONS	902	=head2 SUPPORT FUNCTIONS
731		903
		904	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		905
732	=over 4	906	=over 4
733		907
734	=item $fileno = IO::AIO::poll_fileno	908	=item $fileno = IO::AIO::poll_fileno
735		909
736	Return the I<request result pipe file descriptor>. This filehandle must be	910	Return the I<request result pipe file descriptor>. This filehandle must be
…		…
740		914
741	See C<poll_cb> for an example.	915	See C<poll_cb> for an example.
742		916
743	=item IO::AIO::poll_cb	917	=item IO::AIO::poll_cb
744		918
745	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
746	regularly. Returns the number of events processed. Returns immediately	920	regularly. Returns the number of events processed. Returns immediately
747	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.
748		926
749	Example: Install an Event watcher that automatically calls	927	Example: Install an Event watcher that automatically calls
750	IO::AIO::poll_cb with high priority:	928	IO::AIO::poll_cb with high priority:
751		929
752	Event->io (fd => IO::AIO::poll_fileno,	930	Event->io (fd => IO::AIO::poll_fileno,
753	poll => 'r', async => 1,	931	poll => 'r', async => 1,
754	cb => \&IO::AIO::poll_cb);	932	cb => \&IO::AIO::poll_cb);
755		933
		934	=item IO::AIO::max_poll_reqs $nreqs
		935
		936	=item IO::AIO::max_poll_time $seconds
		937
		938	These set the maximum number of requests (default C<0>, meaning infinity)
		939	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		940	the maximum amount of time (default C<0>, meaning infinity) spent in
		941	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		942	of time C<poll_cb> is allowed to use).
		943
		944	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		945	syscall per request processed, which is not normally a problem unless your
		946	callbacks are really really fast or your OS is really really slow (I am
		947	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		948
		949	Setting these is useful if you want to ensure some level of
		950	interactiveness when perl is not fast enough to process all requests in
		951	time.
		952
		953	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		954
		955	Example: Install an Event watcher that automatically calls
		956	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		957	program get the CPU sometimes even under high AIO load.
		958
		959	# try not to spend much more than 0.1s in poll_cb
		960	IO::AIO::max_poll_time 0.1;
		961
		962	# use a low priority so other tasks have priority
		963	Event->io (fd => IO::AIO::poll_fileno,
		964	poll => 'r', nice => 1,
		965	cb => &IO::AIO::poll_cb);
		966
756	=item IO::AIO::poll_wait	967	=item IO::AIO::poll_wait
757		968
758	Wait till the result filehandle becomes ready for reading (simply does a	969	Wait till the result filehandle becomes ready for reading (simply does a
759	C<select> on the filehandle. This is useful if you want to synchronously wait	970	C<select> on the filehandle. This is useful if you want to synchronously
760	for some requests to finish).	971	wait for some requests to finish).
761		972
762	See C<nreqs> for an example.	973	See C<nreqs> for an example.
763		974
		975	=item IO::AIO::poll
		976
		977	Waits until some requests have been handled.
		978
		979	Strictly equivalent to:
		980
		981	IO::AIO::poll_wait, IO::AIO::poll_cb
		982	if IO::AIO::nreqs;
		983
764	=item IO::AIO::nreqs	984	=item IO::AIO::flush
765		985
766	Returns the number of requests currently outstanding (i.e. for which their	986	Wait till all outstanding AIO requests have been handled.
767	callback has not been invoked yet).
768		987
769	Example: wait till there are no outstanding requests anymore:	988	Strictly equivalent to:
770		989
771	IO::AIO::poll_wait, IO::AIO::poll_cb	990	IO::AIO::poll_wait, IO::AIO::poll_cb
772	while IO::AIO::nreqs;	991	while IO::AIO::nreqs;
773		992
774	=item IO::AIO::flush	993	=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		994
792	=item IO::AIO::min_parallel $nthreads	995	=item IO::AIO::min_parallel $nthreads
793		996
794	Set the minimum number of AIO threads to C<$nthreads>. The current	997	Set the minimum number of AIO threads to C<$nthreads>. The current
795	default is C<8>, which means eight asynchronous operations can execute	998	default is C<8>, which means eight asynchronous operations can execute
796	concurrently at any one time (the number of outstanding requests,	999	concurrently at any one time (the number of outstanding requests,
797	however, is unlimited).	1000	however, is unlimited).
798		1001
799	IO::AIO starts threads only on demand, when an AIO request is queued and	1002	IO::AIO starts threads only on demand, when an AIO request is queued and
800	no free thread exists.	1003	no free thread exists. Please note that queueing up a hundred requests can
		1004	create demand for a hundred threads, even if it turns out that everything
		1005	is in the cache and could have been processed faster by a single thread.
801		1006
802	It is recommended to keep the number of threads relatively low, as some	1007	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	1008	Linux kernel versions will scale negatively with the number of threads
804	(higher parallelity => MUCH higher latency). With current Linux 2.6	1009	(higher parallelity => MUCH higher latency). With current Linux 2.6
805	versions, 4-32 threads should be fine.	1010	versions, 4-32 threads should be fine.
…		…
819	This module automatically runs C<max_parallel 0> at program end, to ensure	1024	This module automatically runs C<max_parallel 0> at program end, to ensure
820	that all threads are killed and that there are no outstanding requests.	1025	that all threads are killed and that there are no outstanding requests.
821		1026
822	Under normal circumstances you don't need to call this function.	1027	Under normal circumstances you don't need to call this function.
823		1028
		1029	=item IO::AIO::max_idle $nthreads
		1030
		1031	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1032	threads that did not get a request to process within 10 seconds). That
		1033	means if a thread becomes idle while C<$nthreads> other threads are also
		1034	idle, it will free its resources and exit.
		1035
		1036	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1037	to allow for extremely high load situations, but want to free resources
		1038	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1039
		1040	The default is probably ok in most situations, especially if thread
		1041	creation is fast. If thread creation is very slow on your system you might
		1042	want to use larger values.
		1043
824	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1044	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
825		1045
826	[DEPRECATED]	1046	This is a very bad function to use in interactive programs because it
		1047	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1048	use an C<aio_group> together with a feed callback.
827		1049
828	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1050	Sets the maximum number of outstanding requests to C<$nreqs>. If you
829	try to queue up more than this number of requests, the caller will block until	1051	to queue up more than this number of requests, the next call to the
830	some requests have been handled.	1052	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1053	function will block until the limit is no longer exceeded.
831		1054
832	The default is very large, so normally there is no practical limit. If you	1055	The default value is very large, so there is no practical limit on the
833	queue up many requests in a loop it often improves speed if you set	1056	number of outstanding requests.
834	this to a relatively low number, such as C<100>.
835		1057
836	This function does not work well together with C<aio_group>'s, and their	1058	You can still queue as many requests as you want. Therefore,
837	feeder interface is better suited to limiting concurrency, so do not use	1059	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
838	this function.	1060	as a stop gap to shield against fatal memory overflow (with large values).
839		1061
840	Under normal circumstances you don't need to call this function.	1062	=head3 STATISTICAL INFORMATION
		1063
		1064	=item IO::AIO::nreqs
		1065
		1066	Returns the number of requests currently in the ready, execute or pending
		1067	states (i.e. for which their callback has not been invoked yet).
		1068
		1069	Example: wait till there are no outstanding requests anymore:
		1070
		1071	IO::AIO::poll_wait, IO::AIO::poll_cb
		1072	while IO::AIO::nreqs;
		1073
		1074	=item IO::AIO::nready
		1075
		1076	Returns the number of requests currently in the ready state (not yet
		1077	executed).
		1078
		1079	=item IO::AIO::npending
		1080
		1081	Returns the number of requests currently in the pending state (executed,
		1082	but not yet processed by poll_cb).
841		1083
842	=back	1084	=back
843		1085
844	=cut	1086	=cut
845		1087
…		…
860	}	1102	}
861		1103
862	min_parallel 8;	1104	min_parallel 8;
863		1105
864	END {	1106	END {
865	max_parallel 0;	1107	min_parallel 1;
866	}	1108	flush;
		1109	};
867		1110
868	1;	1111	1;
869		1112
870	=head2 FORK BEHAVIOUR	1113	=head2 FORK BEHAVIOUR
871		1114
872	This module should do "the right thing" when the process using it forks:	1115	This module should do "the right thing" when the process using it forks:
873		1116
874	Before the fork, IO::AIO enters a quiescent state where no requests	1117	Before the fork, IO::AIO enters a quiescent state where no requests
875	can be added in other threads and no results will be processed. After	1118	can be added in other threads and no results will be processed. After
876	the fork the parent simply leaves the quiescent state and continues	1119	the fork the parent simply leaves the quiescent state and continues
877	request/result processing, while the child clears the request/result	1120	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	1121	(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	1122	parent). Threads will be started on demand until the limit set in the
880	parent process has been reached again.	1123	parent process has been reached again.
881		1124
882	In short: the parent will, after a short pause, continue as if fork had	1125	In short: the parent will, after a short pause, continue as if fork had
883	not been called, while the child will act as if IO::AIO has not been used	1126	not been called, while the child will act as if IO::AIO has not been used
884	yet.	1127	yet.
885		1128
886	=head2 MEMORY USAGE	1129	=head2 MEMORY USAGE
887		1130
		1131	Per-request usage:
		1132
888	Each aio request uses - depending on your architecture - around 128 bytes	1133	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	1134	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	1135	a few hundred bytes), readdir requires a result buffer and so on. Perl
891	also be locked.	1136	scalars and other data passed into aio requests will also be locked and
		1137	will consume memory till the request has entered the done state.
892		1138
893	This is now awfully much, so queuing lots of requests is not usually a	1139	This is now awfully much, so queuing lots of requests is not usually a
894	problem.	1140	problem.
895		1141
896	Each thread needs a stack area which is usually around 16k, sometimes much	1142	Per-thread usage:
897	larger, depending on the OS.	1143
		1144	In the execution phase, some aio requests require more memory for
		1145	temporary buffers, and each thread requires a stack and other data
		1146	structures (usually around 16k-128k, depending on the OS).
		1147
		1148	=head1 KNOWN BUGS
		1149
		1150	Known bugs will be fixed in the next release.
898		1151
899	=head1 SEE ALSO	1152	=head1 SEE ALSO
900		1153
901	L<Coro::AIO>.	1154	L<Coro::AIO>.
902		1155

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs. Revision 1.89 by root, Sun Oct 29 11:03:18 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs.
Revision 1.89 by root, Sun Oct 29 11:03:18 2006 UTC