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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs.
Revision 1.98 by root, Sun Dec 31 17:07:32 2006 UTC

…		…
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", O_RDONLY, 0, sub {
10	my ($fh) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
18	};	19	};
19		20
20	# version 2+ has request and group objects	21	# version 2+ has request and group objects
21	use IO::AIO 2;	22	use IO::AIO 2;
22		23
		24	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
25		27
26	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
…		…
50	=head1 DESCRIPTION	52	=head1 DESCRIPTION
51		53
52	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
53	operating system supports.	55	operating system supports.
54		56
		57	Asynchronous means that operations that can normally block your program
		58	(e.g. reading from disk) will be done asynchronously: the operation
		59	will still block, but you can do something else in the meantime. This
		60	is extremely useful for programs that need to stay interactive even
		61	when doing heavy I/O (GUI programs, high performance network servers
		62	etc.), but can also be used to easily do operations in parallel that are
		63	normally done sequentially, e.g. stat'ing many files, which is much faster
		64	on a RAID volume or over NFS when you do a number of stat operations
		65	concurrently.
		66
		67	While most of this works on all types of file descriptors (for example
		68	sockets), using these functions on file descriptors that support
		69	nonblocking operation (again, sockets, pipes etc.) is very inefficient or
		70	might not work (aio_read fails on sockets/pipes/fifos). Use an event loop
		71	for that (such as the L<Event\|Event> module): IO::AIO will naturally fit
		72	into such an event loop itself.
		73
55	Currently, a number of threads are started that execute your read/writes	74	In this version, a number of threads are started that execute your
56	and signal their completion. You don't need thread support in your libc or	75	requests and signal their completion. You don't need thread support
57	perl, and the threads created by this module will not be visible to the	76	in perl, and the threads created by this module will not be visible
58	pthreads library. In the future, this module might make use of the native	77	to perl. In the future, this module might make use of the native aio
59	aio functions available on many operating systems. However, they are often	78	functions available on many operating systems. However, they are often
60	not well-supported (Linux doesn't allow them on normal files currently,	79	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	for example), and they would only support aio_read and aio_write, so the	80	files currently, for example), and they would only support aio_read and
62	remaining functionality would have to be implemented using threads anyway.	81	aio_write, so the remaining functionality would have to be implemented
		82	using threads anyway.
63		83
64	Although the module will work with in the presence of other threads, it is	84	Although the module will work with in the presence of other (Perl-)
65	currently not reentrant, so use appropriate locking yourself, always call	85	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	86	locking yourself, always call C<poll_cb> from within the same thread, or
67	C<aio_> functions) recursively.	87	never call C<poll_cb> (or other C<aio_> functions) recursively.
		88
		89	=head2 EXAMPLE
		90
		91	This is a simple example that uses the Event module and loads
		92	F</etc/passwd> asynchronously:
		93
		94	use Fcntl;
		95	use Event;
		96	use IO::AIO;
		97
		98	# register the IO::AIO callback with Event
		99	Event->io (fd => IO::AIO::poll_fileno,
		100	poll => 'r',
		101	cb => \&IO::AIO::poll_cb);
		102
		103	# queue the request to open /etc/passwd
		104	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		105	my $fh = shift
		106	or die "error while opening: $!";
		107
		108	# stat'ing filehandles is generally non-blocking
		109	my $size = -s $fh;
		110
		111	# queue a request to read the file
		112	my $contents;
		113	aio_read $fh, 0, $size, $contents, 0, sub {
		114	$_[0] == $size
		115	or die "short read: $!";
		116
		117	close $fh;
		118
		119	# file contents now in $contents
		120	print $contents;
		121
		122	# exit event loop and program
		123	Event::unloop;
		124	};
		125	};
		126
		127	# possibly queue up other requests, or open GUI windows,
		128	# check for sockets etc. etc.
		129
		130	# process events as long as there are some:
		131	Event::loop;
		132
		133	=head1 REQUEST ANATOMY AND LIFETIME
		134
		135	Every C<aio_*> function creates a request. which is a C data structure not
		136	directly visible to Perl.
		137
		138	If called in non-void context, every request function returns a Perl
		139	object representing the request. In void context, nothing is returned,
		140	which saves a bit of memory.
		141
		142	The perl object is a fairly standard ref-to-hash object. The hash contents
		143	are not used by IO::AIO so you are free to store anything you like in it.
		144
		145	During their existance, aio requests travel through the following states,
		146	in order:
		147
		148	=over 4
		149
		150	=item ready
		151
		152	Immediately after a request is created it is put into the ready state,
		153	waiting for a thread to execute it.
		154
		155	=item execute
		156
		157	A thread has accepted the request for processing and is currently
		158	executing it (e.g. blocking in read).
		159
		160	=item pending
		161
		162	The request has been executed and is waiting for result processing.
		163
		164	While request submission and execution is fully asynchronous, result
		165	processing is not and relies on the perl interpreter calling C<poll_cb>
		166	(or another function with the same effect).
		167
		168	=item result
		169
		170	The request results are processed synchronously by C<poll_cb>.
		171
		172	The C<poll_cb> function will process all outstanding aio requests by
		173	calling their callbacks, freeing memory associated with them and managing
		174	any groups they are contained in.
		175
		176	=item done
		177
		178	Request has reached the end of its lifetime and holds no resources anymore
		179	(except possibly for the Perl object, but its connection to the actual
		180	aio request is severed and calling its methods will either do nothing or
		181	result in a runtime error).
		182
		183	=back
68		184
69	=cut	185	=cut
70		186
71	package IO::AIO;	187	package IO::AIO;
72		188
…		…
74	use strict 'vars';	190	use strict 'vars';
75		191
76	use base 'Exporter';	192	use base 'Exporter';
77		193
78	BEGIN {	194	BEGIN {
79	our $VERSION = '2.0';	195	our $VERSION = '2.31';
80		196
81	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	197	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	198	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	199	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
84	aio_group);	200	aio_move aio_copy aio_group aio_nop aio_mknod aio_load);
85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
		202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		203	min_parallel max_parallel max_idle
		204	nreqs nready npending nthreads
		205	max_poll_time max_poll_reqs);
86		206
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		208
89	require XSLoader;	209	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
91	}	211	}
92		212
93	=head1 FUNCTIONS	213	=head1 FUNCTIONS
94		214
95	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
96		216
97	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
98	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
99	and they all accept an additional (and optional) C<$callback> argument	219	and they all accept an additional (and optional) C<$callback> argument
100	which must be a code reference. This code reference will get called with	220	which must be a code reference. This code reference will get called with
…		…
103	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
104		224
105	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
106	internally until the request has finished.	226	internally until the request has finished.
107		227
108	All requests return objects of type L<IO::AIO::REQ> that allow further	228	All functions return request objects of type L<IO::AIO::REQ> that allow
109	manipulation of those requests while they are in-flight.	229	further manipulation of those requests while they are in-flight.
110		230
111	The pathnames you pass to these routines I<must> be absolute and	231	The pathnames you pass to these routines I<must> be absolute and
112	encoded in byte form. The reason for the former is that at the time the	232	encoded as octets. The reason for the former is that at the time the
113	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
114	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
115	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
116		237
117	To encode pathnames to byte form, either make sure you either: a)	238	To encode pathnames as octets, either make sure you either: a) always pass
118	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
119	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	240	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
120	your pathnames to the locale (or other) encoding in effect in the user	241	your pathnames to the locale (or other) encoding in effect in the user
121	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
122	use something else.	243	use something else to ensure your scalar has the correct contents.
		244
		245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		246	handles correctly wether it is set or not.
123		247
124	=over 4	248	=over 4
		249
		250	=item $prev_pri = aioreq_pri [$pri]
		251
		252	Returns the priority value that would be used for the next request and, if
		253	C<$pri> is given, sets the priority for the next aio request.
		254
		255	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		256	and C<4>, respectively. Requests with higher priority will be serviced
		257	first.
		258
		259	The priority will be reset to C<0> after each call to one of the C<aio_*>
		260	functions.
		261
		262	Example: open a file with low priority, then read something from it with
		263	higher priority so the read request is serviced before other low priority
		264	open requests (potentially spamming the cache):
		265
		266	aioreq_pri -3;
		267	aio_open ..., sub {
		268	return unless $_[0];
		269
		270	aioreq_pri -2;
		271	aio_read $_[0], ..., sub {
		272	...
		273	};
		274	};
		275
		276	=item aioreq_nice $pri_adjust
		277
		278	Similar to C<aioreq_pri>, but subtracts the given value from the current
		279	priority, so the effect is cumulative.
125		280
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	281	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		282
128	Asynchronously open or create a file and call the callback with a newly	283	Asynchronously open or create a file and call the callback with a newly
129	created filehandle for the file.	284	created filehandle for the file.
…		…
180	aio_read $fh, 7, 15, $buffer, 0, sub {	335	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	336	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	337	print "read $_[0] bytes: <$buffer>\n";
183	};	338	};
184		339
185	=item aio_move $srcpath, $dstpath, $callback->($status)
186
187	Try to move the I<file> (directories not supported as either source or
188	destination) from C<$srcpath> to C<$dstpath> and call the callback with
189	the C<0> (error) or C<-1> ok.
190
191	This is a composite request that tries to rename(2) the file first. If
192	rename files with C<EXDEV>, it creates the destination file with mode 0200
193	and copies the contents of the source file into it using C<aio_sendfile>,
194	followed by restoring atime, mtime, access mode and uid/gid, in that
195	order, and unlinking the C<$srcpath>.
196
197	If an error occurs, the partial destination file will be unlinked, if
198	possible, except when setting atime, mtime, access mode and uid/gid, where
199	errors are being ignored.
200
201	=cut
202
203	sub aio_move($$$) {
204	my ($src, $dst, $cb) = @_;
205
206	my $grp = aio_group;
207
208	add $grp aio_rename $src, $dst, sub {
209	if ($_[0] && $! == EXDEV) {
210	add $grp aio_open $src, O_RDONLY, 0, sub {
211	if (my $src_fh = $_[0]) {
212	my @stat = stat $src_fh;
213
214	add $grp aio_open $dst, O_WRONLY, 0200, sub {
215	if (my $dst_fh = $_[0]) {
216	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
217	close $src_fh;
218
219	if ($_[0] == $stat[7]) {
220	utime $stat[8], $stat[9], $dst;
221	chmod $stat[2] & 07777, $dst_fh;
222	chown $stat[4], $stat[5], $dst_fh;
223	close $dst_fh;
224
225	add $grp aio_unlink $src, sub {
226	$cb->($_[0]);
227	};
228	} else {
229	my $errno = $!;
230	add $grp aio_unlink $dst, sub {
231	$! = $errno;
232	$cb->(-1);
233	};
234	}
235	};
236	} else {
237	$cb->(-1);
238	}
239	},
240
241	} else {
242	$cb->(-1);
243	}
244	};
245	} else {
246	$cb->($_[0]);
247	}
248	};
249
250	$grp
251	}
252
253	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	340	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
254		341
255	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	342	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
256	reading at byte offset C<$in_offset>, and starts writing at the current	343	reading at byte offset C<$in_offset>, and starts writing at the current
257	file offset of C<$out_fh>. Because of that, it is not safe to issue more	344	file offset of C<$out_fh>. Because of that, it is not safe to issue more
…		…
312	=item aio_unlink $pathname, $callback->($status)	399	=item aio_unlink $pathname, $callback->($status)
313		400
314	Asynchronously unlink (delete) a file and call the callback with the	401	Asynchronously unlink (delete) a file and call the callback with the
315	result code.	402	result code.
316		403
		404	=item aio_mknod $path, $mode, $dev, $callback->($status)
		405
		406	[EXPERIMENTAL]
		407
		408	Asynchronously create a device node (or fifo). See mknod(2).
		409
		410	The only (POSIX-) portable way of calling this function is:
		411
		412	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		413
317	=item aio_link $srcpath, $dstpath, $callback->($status)	414	=item aio_link $srcpath, $dstpath, $callback->($status)
318		415
319	Asynchronously create a new link to the existing object at C<$srcpath> at	416	Asynchronously create a new link to the existing object at C<$srcpath> at
320	the path C<$dstpath> and call the callback with the result code.	417	the path C<$dstpath> and call the callback with the result code.
321		418
322	=item aio_symlink $srcpath, $dstpath, $callback->($status)	419	=item aio_symlink $srcpath, $dstpath, $callback->($status)
323		420
324	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	421	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
325	the path C<$dstpath> and call the callback with the result code.	422	the path C<$dstpath> and call the callback with the result code.
		423
		424	=item aio_readlink $path, $callback->($link)
		425
		426	Asynchronously read the symlink specified by C<$path> and pass it to
		427	the callback. If an error occurs, nothing or undef gets passed to the
		428	callback.
326		429
327	=item aio_rename $srcpath, $dstpath, $callback->($status)	430	=item aio_rename $srcpath, $dstpath, $callback->($status)
328		431
329	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	432	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
330	rename(2) and call the callback with the result code.	433	rename(2) and call the callback with the result code.
…		…
341	sorted, and will B<NOT> include the C<.> and C<..> entries.	444	sorted, and will B<NOT> include the C<.> and C<..> entries.
342		445
343	The callback a single argument which is either C<undef> or an array-ref	446	The callback a single argument which is either C<undef> or an array-ref
344	with the filenames.	447	with the filenames.
345		448
		449	=item aio_load $path, $data, $callback->($status)
		450
		451	This is a composite request that tries to fully load the given file into
		452	memory. Status is the same as with aio_read.
		453
		454	=cut
		455
		456	sub aio_load($$;$) {
		457	aio_block {
		458	my ($path, undef, $cb) = @_;
		459	my $data = \$_[1];
		460
		461	my $pri = aioreq_pri;
		462	my $grp = aio_group $cb;
		463
		464	aioreq_pri $pri;
		465	add $grp aio_open $path, O_RDONLY, 0, sub {
		466	my ($fh) = @_
		467	or return $grp->result (-1);
		468
		469	aioreq_pri $pri;
		470	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		471	$grp->result ($_[0]);
		472	};
		473	};
		474
		475	$grp
		476	}
		477	}
		478
		479	=item aio_copy $srcpath, $dstpath, $callback->($status)
		480
		481	Try to copy the I<file> (directories not supported as either source or
		482	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		483	the C<0> (error) or C<-1> ok.
		484
		485	This is a composite request that it creates the destination file with
		486	mode 0200 and copies the contents of the source file into it using
		487	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		488	uid/gid, in that order.
		489
		490	If an error occurs, the partial destination file will be unlinked, if
		491	possible, except when setting atime, mtime, access mode and uid/gid, where
		492	errors are being ignored.
		493
		494	=cut
		495
		496	sub aio_copy($$;$) {
		497	aio_block {
		498	my ($src, $dst, $cb) = @_;
		499
		500	my $pri = aioreq_pri;
		501	my $grp = aio_group $cb;
		502
		503	aioreq_pri $pri;
		504	add $grp aio_open $src, O_RDONLY, 0, sub {
		505	if (my $src_fh = $_[0]) {
		506	my @stat = stat $src_fh;
		507
		508	aioreq_pri $pri;
		509	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		510	if (my $dst_fh = $_[0]) {
		511	aioreq_pri $pri;
		512	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		513	if ($_[0] == $stat[7]) {
		514	$grp->result (0);
		515	close $src_fh;
		516
		517	# those should not normally block. should. should.
		518	utime $stat[8], $stat[9], $dst;
		519	chmod $stat[2] & 07777, $dst_fh;
		520	chown $stat[4], $stat[5], $dst_fh;
		521	close $dst_fh;
		522	} else {
		523	$grp->result (-1);
		524	close $src_fh;
		525	close $dst_fh;
		526
		527	aioreq $pri;
		528	add $grp aio_unlink $dst;
		529	}
		530	};
		531	} else {
		532	$grp->result (-1);
		533	}
		534	},
		535
		536	} else {
		537	$grp->result (-1);
		538	}
		539	};
		540
		541	$grp
		542	}
		543	}
		544
		545	=item aio_move $srcpath, $dstpath, $callback->($status)
		546
		547	Try to move the I<file> (directories not supported as either source or
		548	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		549	the C<0> (error) or C<-1> ok.
		550
		551	This is a composite request that tries to rename(2) the file first. If
		552	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		553	that is successful, unlinking the C<$srcpath>.
		554
		555	=cut
		556
		557	sub aio_move($$;$) {
		558	aio_block {
		559	my ($src, $dst, $cb) = @_;
		560
		561	my $pri = aioreq_pri;
		562	my $grp = aio_group $cb;
		563
		564	aioreq_pri $pri;
		565	add $grp aio_rename $src, $dst, sub {
		566	if ($_[0] && $! == EXDEV) {
		567	aioreq_pri $pri;
		568	add $grp aio_copy $src, $dst, sub {
		569	$grp->result ($_[0]);
		570
		571	if (!$_[0]) {
		572	aioreq_pri $pri;
		573	add $grp aio_unlink $src;
		574	}
		575	};
		576	} else {
		577	$grp->result ($_[0]);
		578	}
		579	};
		580
		581	$grp
		582	}
		583	}
		584
346	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	585	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
347		586
348	Scans a directory (similar to C<aio_readdir>) but additionally tries to	587	Scans a directory (similar to C<aio_readdir>) but additionally tries to
349	separate the entries of directory C<$path> into two sets of names, ones	588	efficiently separate the entries of directory C<$path> into two sets of
350	you can recurse into (directories or links to them), and ones you cannot	589	names, directories you can recurse into (directories), and ones you cannot
351	recurse into (everything else).	590	recurse into (everything else, including symlinks to directories).
352		591
353	C<aio_scandir> is a composite request that consists of many sub	592	C<aio_scandir> is a composite request that creates of many sub requests_
354	requests. C<$maxreq> specifies the maximum number of outstanding aio	593	C<$maxreq> specifies the maximum number of outstanding aio requests that
355	requests that this function generates. If it is C<< <= 0 >>, then a	594	this function generates. If it is C<< <= 0 >>, then a suitable default
356	suitable default will be chosen (currently 8).	595	will be chosen (currently 4).
357		596
358	On error, the callback is called without arguments, otherwise it receives	597	On error, the callback is called without arguments, otherwise it receives
359	two array-refs with path-relative entry names.	598	two array-refs with path-relative entry names.
360		599
361	Example:	600	Example:
…		…
396	directory counting heuristic.	635	directory counting heuristic.
397		636
398	=cut	637	=cut
399		638
400	sub aio_scandir($$$) {	639	sub aio_scandir($$$) {
		640	aio_block {
401	my ($path, $maxreq, $cb) = @_;	641	my ($path, $maxreq, $cb) = @_;
402		642
		643	my $pri = aioreq_pri;
		644
403	my $grp = aio_group;	645	my $grp = aio_group $cb;
404		646
405	$maxreq = 8 if $maxreq <= 0;	647	$maxreq = 4 if $maxreq <= 0;
406		648
407	# stat once	649	# stat once
		650	aioreq_pri $pri;
408	add $grp aio_stat $path, sub {	651	add $grp aio_stat $path, sub {
409	return $cb->() if $_[0];	652	return $grp->result () if $_[0];
410	my $now = time;	653	my $now = time;
411	my $hash1 = join ":", (stat _)[0,1,3,7,9];	654	my $hash1 = join ":", (stat _)[0,1,3,7,9];
412		655
413	# read the directory entries	656	# read the directory entries
		657	aioreq_pri $pri;
414	add $grp aio_readdir $path, sub {	658	add $grp aio_readdir $path, sub {
415	my $entries = shift	659	my $entries = shift
416	or return $cb->();	660	or return $grp->result ();
417		661
418	# stat the dir another time	662	# stat the dir another time
		663	aioreq_pri $pri;
419	add $grp aio_stat $path, sub {	664	add $grp aio_stat $path, sub {
420	my $hash2 = join ":", (stat _)[0,1,3,7,9];	665	my $hash2 = join ":", (stat _)[0,1,3,7,9];
421		666
422	my $ndirs;	667	my $ndirs;
423		668
424	# take the slow route if anything looks fishy	669	# take the slow route if anything looks fishy
425	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	670	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
426	$ndirs = -1;	671	$ndirs = -1;
427	} else {	672	} else {
428	# if nlink == 2, we are finished	673	# if nlink == 2, we are finished
429	# on non-posix-fs's, we rely on nlink < 2	674	# on non-posix-fs's, we rely on nlink < 2
430	$ndirs = (stat _)[3] - 2	675	$ndirs = (stat _)[3] - 2
431	or return $cb->([], $entries);	676	or return $grp->result ([], $entries);
432	}
433
434	# sort into likely dirs and likely nondirs
435	# dirs == files without ".", short entries first
436	$entries = [map $_->[0],
437	sort { $b->[1] cmp $a->[1] }
438	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
439	@$entries];
440
441	my (@dirs, @nondirs);
442
443	my ($statcb, $schedcb);
444	my $nreq = 0;
445
446	$schedcb = sub {
447	if (@$entries) {
448	if ($nreq < $maxreq) {
449	my $ent = pop @$entries;
450	$nreq++;
451	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
452	}
453	} elsif (!$nreq) {
454	# finished
455	undef $statcb;
456	undef $schedcb;
457	$cb->(\@dirs, \@nondirs) if $cb;
458	undef $cb;
459	}	677	}
		678
		679	# sort into likely dirs and likely nondirs
		680	# dirs == files without ".", short entries first
		681	$entries = [map $_->[0],
		682	sort { $b->[1] cmp $a->[1] }
		683	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		684	@$entries];
		685
		686	my (@dirs, @nondirs);
		687
		688	my $statgrp = add $grp aio_group sub {
		689	$grp->result (\@dirs, \@nondirs);
		690	};
		691
		692	limit $statgrp $maxreq;
		693	feed $statgrp sub {
		694	return unless @$entries;
		695	my $entry = pop @$entries;
		696
		697	aioreq_pri $pri;
		698	add $statgrp aio_stat "$path/$entry/.", sub {
		699	if ($_[0] < 0) {
		700	push @nondirs, $entry;
		701	} else {
		702	# need to check for real directory
		703	aioreq_pri $pri;
		704	add $statgrp aio_lstat "$path/$entry", sub {
		705	if (-d _) {
		706	push @dirs, $entry;
		707
		708	unless (--$ndirs) {
		709	push @nondirs, @$entries;
		710	feed $statgrp;
		711	}
		712	} else {
		713	push @nondirs, $entry;
		714	}
		715	}
		716	}
		717	};
		718	};
460	};	719	};
461	$statcb = sub {
462	my ($status, $entry) = @_;
463
464	if ($status < 0) {
465	$nreq--;
466	push @nondirs, $entry;
467	&$schedcb;
468	} else {
469	# need to check for real directory
470	add $grp aio_lstat "$path/$entry", sub {
471	$nreq--;
472
473	if (-d _) {
474	push @dirs, $entry;
475
476	if (!--$ndirs) {
477	push @nondirs, @$entries;
478	$entries = [];
479	}
480	} else {
481	push @nondirs, $entry;
482	}
483
484	&$schedcb;
485	}
486	}
487	};
488
489	&$schedcb while @$entries && $nreq < $maxreq;
490	};	720	};
491	};	721	};
		722
		723	$grp
492	};	724	}
493
494	$grp
495	}	725	}
496		726
497	=item aio_fsync $fh, $callback->($status)	727	=item aio_fsync $fh, $callback->($status)
498		728
499	Asynchronously call fsync on the given filehandle and call the callback	729	Asynchronously call fsync on the given filehandle and call the callback
…		…
505	callback with the fdatasync result code.	735	callback with the fdatasync result code.
506		736
507	If this call isn't available because your OS lacks it or it couldn't be	737	If this call isn't available because your OS lacks it or it couldn't be
508	detected, it will be emulated by calling C<fsync> instead.	738	detected, it will be emulated by calling C<fsync> instead.
509		739
510	=item aio_group $callback->()	740	=item aio_group $callback->(...)
511
512	[EXPERIMENTAL]
513		741
514	This is a very special aio request: Instead of doing something, it is a	742	This is a very special aio request: Instead of doing something, it is a
515	container for other aio requests, which is useful if you want to bundle	743	container for other aio requests, which is useful if you want to bundle
516	many requests into a single, composite, request.	744	many requests into a single, composite, request with a definite callback
		745	and the ability to cancel the whole request with its subrequests.
517		746
518	Returns an object of class L<IO::AIO::GRP>. See its documentation below	747	Returns an object of class L<IO::AIO::GRP>. See its documentation below
519	for more info.	748	for more info.
520		749
521	Example:	750	Example:
…		…
527	add $grp	756	add $grp
528	(aio_stat ...),	757	(aio_stat ...),
529	(aio_stat ...),	758	(aio_stat ...),
530	...;	759	...;
531		760
		761	=item aio_nop $callback->()
		762
		763	This is a special request - it does nothing in itself and is only used for
		764	side effects, such as when you want to add a dummy request to a group so
		765	that finishing the requests in the group depends on executing the given
		766	code.
		767
		768	While this request does nothing, it still goes through the execution
		769	phase and still requires a worker thread. Thus, the callback will not
		770	be executed immediately but only after other requests in the queue have
		771	entered their execution phase. This can be used to measure request
		772	latency.
		773
532	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	774	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
533		775
534	Mainly used for debugging and benchmarking, this aio request puts one of	776	Mainly used for debugging and benchmarking, this aio request puts one of
535	the request workers to sleep for the given time.	777	the request workers to sleep for the given time.
536		778
537	While it is theoretically handy to have simple I/O scheduling requests	779	While it is theoretically handy to have simple I/O scheduling requests
538	like sleep and file handle readable/writable, the overhead this creates	780	like sleep and file handle readable/writable, the overhead this creates is
539	is immense, so do not use this function except to put your application	781	immense (it blocks a thread for a long time) so do not use this function
540	under artificial I/O pressure.	782	except to put your application under artificial I/O pressure.
541		783
542	=back	784	=back
543		785
544	=head2 IO::AIO::REQ CLASS	786	=head2 IO::AIO::REQ CLASS
545		787
546	All non-aggregate C<aio_*> functions return an object of this class when	788	All non-aggregate C<aio_*> functions return an object of this class when
547	called in non-void context.	789	called in non-void context.
548		790
549	A request always moves through the following five states in its lifetime,
550	in order: B<ready> (request has been created, but has not been executed
551	yet), B<execute> (request is currently being executed), B<pending>
552	(request has been executed but callback has not been called yet),
553	B<result> (results are being processed synchronously, includes calling the
554	callback) and B<done> (request has reached the end of its lifetime and
555	holds no resources anymore).
556
557	=over 4	791	=over 4
558		792
559	=item $req->cancel	793	=item cancel $req
560		794
561	Cancels the request, if possible. Has the effect of skipping execution	795	Cancels the request, if possible. Has the effect of skipping execution
562	when entering the B<execute> state and skipping calling the callback when	796	when entering the B<execute> state and skipping calling the callback when
563	entering the the B<result> state, but will leave the request otherwise	797	entering the the B<result> state, but will leave the request otherwise
564	untouched. That means that requests that currently execute will not be	798	untouched. That means that requests that currently execute will not be
565	stopped and resources held by the request will not be freed prematurely.	799	stopped and resources held by the request will not be freed prematurely.
566		800
		801	=item cb $req $callback->(...)
		802
		803	Replace (or simply set) the callback registered to the request.
		804
567	=back	805	=back
568		806
569	=head2 IO::AIO::GRP CLASS	807	=head2 IO::AIO::GRP CLASS
570		808
571	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	809	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
585	You add requests by calling the C<add> method with one or more	823	You add requests by calling the C<add> method with one or more
586	C<IO::AIO::REQ> objects:	824	C<IO::AIO::REQ> objects:
587		825
588	$grp->add (aio_unlink "...");	826	$grp->add (aio_unlink "...");
589		827
590	add $grp aio_stat "...", sub { ... };	828	add $grp aio_stat "...", sub {
		829	$_[0] or return $grp->result ("error");
		830
		831	# add another request dynamically, if first succeeded
		832	add $grp aio_open "...", sub {
		833	$grp->result ("ok");
		834	};
		835	};
591		836
592	This makes it very easy to create composite requests (see the source of	837	This makes it very easy to create composite requests (see the source of
593	C<aio_move> for an application) that work and feel like simple requests.	838	C<aio_move> for an application) that work and feel like simple requests.
594		839
		840	=over 4
		841
595	The IO::AIO::GRP objects will be cleaned up during calls to	842	=item * The IO::AIO::GRP objects will be cleaned up during calls to
596	C<IO::AIO::poll_cb>, just like any other request.	843	C<IO::AIO::poll_cb>, just like any other request.
597		844
598	They can be canceled like any other request. Canceling will cancel not	845	=item * They can be canceled like any other request. Canceling will cancel not
599	just the request itself, but also all requests it contains.	846	only the request itself, but also all requests it contains.
600		847
601	They can also can also be added to other IO::AIO::GRP objects.	848	=item * They can also can also be added to other IO::AIO::GRP objects.
		849
		850	=item * You must not add requests to a group from within the group callback (or
		851	any later time).
		852
		853	=back
602		854
603	Their lifetime, simplified, looks like this: when they are empty, they	855	Their lifetime, simplified, looks like this: when they are empty, they
604	will finish very quickly. If they contain only requests that are in the	856	will finish very quickly. If they contain only requests that are in the
605	C<done> state, they will also finish. Otherwise they will continue to	857	C<done> state, they will also finish. Otherwise they will continue to
606	exist.	858	exist.
607		859
		860	That means after creating a group you have some time to add requests. And
		861	in the callbacks of those requests, you can add further requests to the
		862	group. And only when all those requests have finished will the the group
		863	itself finish.
		864
608	=over 4	865	=over 4
609		866
		867	=item add $grp ...
		868
610	=item $grp->add (...)	869	=item $grp->add (...)
611		870
612	=item add $grp ...	871	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		872	be added, including other groups, as long as you do not create circular
		873	dependencies.
613		874
614	Add one or more	875	Returns all its arguments.
615	Cancels the request, if possible. Has the effect of skipping execution	876
616	when entering the B<execute> state and skipping calling the callback when	877	=item $grp->cancel_subs
617	entering the the B<result> state, but will leave the request otherwise	878
618	untouched. That means that requests that currently execute will not be	879	Cancel all subrequests and clears any feeder, but not the group request
619	stopped and resources held by the request will not be freed prematurely.	880	itself. Useful when you queued a lot of events but got a result early.
		881
		882	=item $grp->result (...)
		883
		884	Set the result value(s) that will be passed to the group callback when all
		885	subrequests have finished and set thre groups errno to the current value
		886	of errno (just like calling C<errno> without an error number). By default,
		887	no argument will be passed and errno is zero.
		888
		889	=item $grp->errno ([$errno])
		890
		891	Sets the group errno value to C<$errno>, or the current value of errno
		892	when the argument is missing.
		893
		894	Every aio request has an associated errno value that is restored when
		895	the callback is invoked. This method lets you change this value from its
		896	default (0).
		897
		898	Calling C<result> will also set errno, so make sure you either set C<$!>
		899	before the call to C<result>, or call c<errno> after it.
		900
		901	=item feed $grp $callback->($grp)
		902
		903	Sets a feeder/generator on this group: every group can have an attached
		904	generator that generates requests if idle. The idea behind this is that,
		905	although you could just queue as many requests as you want in a group,
		906	this might starve other requests for a potentially long time. For
		907	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		908	requests, delaying any later requests for a long time.
		909
		910	To avoid this, and allow incremental generation of requests, you can
		911	instead a group and set a feeder on it that generates those requests. The
		912	feed callback will be called whenever there are few enough (see C<limit>,
		913	below) requests active in the group itself and is expected to queue more
		914	requests.
		915
		916	The feed callback can queue as many requests as it likes (i.e. C<add> does
		917	not impose any limits).
		918
		919	If the feed does not queue more requests when called, it will be
		920	automatically removed from the group.
		921
		922	If the feed limit is C<0>, it will be set to C<2> automatically.
		923
		924	Example:
		925
		926	# stat all files in @files, but only ever use four aio requests concurrently:
		927
		928	my $grp = aio_group sub { print "finished\n" };
		929	limit $grp 4;
		930	feed $grp sub {
		931	my $file = pop @files
		932	or return;
		933
		934	add $grp aio_stat $file, sub { ... };
		935	};
		936
		937	=item limit $grp $num
		938
		939	Sets the feeder limit for the group: The feeder will be called whenever
		940	the group contains less than this many requests.
		941
		942	Setting the limit to C<0> will pause the feeding process.
620		943
621	=back	944	=back
622		945
623	=head2 SUPPORT FUNCTIONS	946	=head2 SUPPORT FUNCTIONS
		947
		948	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
624		949
625	=over 4	950	=over 4
626		951
627	=item $fileno = IO::AIO::poll_fileno	952	=item $fileno = IO::AIO::poll_fileno
628		953
…		…
633		958
634	See C<poll_cb> for an example.	959	See C<poll_cb> for an example.
635		960
636	=item IO::AIO::poll_cb	961	=item IO::AIO::poll_cb
637		962
638	Process all outstanding events on the result pipe. You have to call this	963	Process some outstanding events on the result pipe. You have to call this
639	regularly. Returns the number of events processed. Returns immediately	964	regularly. Returns the number of events processed. Returns immediately
640	when no events are outstanding.	965	when no events are outstanding. The amount of events processed depends on
		966	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		967
		968	If not all requests were processed for whatever reason, the filehandle
		969	will still be ready when C<poll_cb> returns.
641		970
642	Example: Install an Event watcher that automatically calls	971	Example: Install an Event watcher that automatically calls
643	IO::AIO::poll_cb with high priority:	972	IO::AIO::poll_cb with high priority:
644		973
645	Event->io (fd => IO::AIO::poll_fileno,	974	Event->io (fd => IO::AIO::poll_fileno,
646	poll => 'r', async => 1,	975	poll => 'r', async => 1,
647	cb => \&IO::AIO::poll_cb);	976	cb => \&IO::AIO::poll_cb);
648		977
		978	=item IO::AIO::max_poll_reqs $nreqs
		979
		980	=item IO::AIO::max_poll_time $seconds
		981
		982	These set the maximum number of requests (default C<0>, meaning infinity)
		983	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		984	the maximum amount of time (default C<0>, meaning infinity) spent in
		985	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		986	of time C<poll_cb> is allowed to use).
		987
		988	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		989	syscall per request processed, which is not normally a problem unless your
		990	callbacks are really really fast or your OS is really really slow (I am
		991	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		992
		993	Setting these is useful if you want to ensure some level of
		994	interactiveness when perl is not fast enough to process all requests in
		995	time.
		996
		997	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		998
		999	Example: Install an Event watcher that automatically calls
		1000	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1001	program get the CPU sometimes even under high AIO load.
		1002
		1003	# try not to spend much more than 0.1s in poll_cb
		1004	IO::AIO::max_poll_time 0.1;
		1005
		1006	# use a low priority so other tasks have priority
		1007	Event->io (fd => IO::AIO::poll_fileno,
		1008	poll => 'r', nice => 1,
		1009	cb => &IO::AIO::poll_cb);
		1010
649	=item IO::AIO::poll_wait	1011	=item IO::AIO::poll_wait
650		1012
		1013	If there are any outstanding requests and none of them in the result
651	Wait till the result filehandle becomes ready for reading (simply does a	1014	phase, wait till the result filehandle becomes ready for reading (simply
652	C<select> on the filehandle. This is useful if you want to synchronously wait	1015	does a C<select> on the filehandle. This is useful if you want to
653	for some requests to finish).	1016	synchronously wait for some requests to finish).
654		1017
655	See C<nreqs> for an example.	1018	See C<nreqs> for an example.
656		1019
		1020	=item IO::AIO::poll
		1021
		1022	Waits until some requests have been handled.
		1023
		1024	Returns the number of requests processed, but is otherwise strictly
		1025	equivalent to:
		1026
		1027	IO::AIO::poll_wait, IO::AIO::poll_cb
		1028
657	=item IO::AIO::nreqs	1029	=item IO::AIO::flush
658		1030
659	Returns the number of requests currently outstanding (i.e. for which their	1031	Wait till all outstanding AIO requests have been handled.
660	callback has not been invoked yet).
661		1032
662	Example: wait till there are no outstanding requests anymore:	1033	Strictly equivalent to:
663		1034
664	IO::AIO::poll_wait, IO::AIO::poll_cb	1035	IO::AIO::poll_wait, IO::AIO::poll_cb
665	while IO::AIO::nreqs;	1036	while IO::AIO::nreqs;
666		1037
667	=item IO::AIO::flush	1038	=head3 CONTROLLING THE NUMBER OF THREADS
668
669	Wait till all outstanding AIO requests have been handled.
670
671	Strictly equivalent to:
672
673	IO::AIO::poll_wait, IO::AIO::poll_cb
674	while IO::AIO::nreqs;
675
676	=item IO::AIO::poll
677
678	Waits until some requests have been handled.
679
680	Strictly equivalent to:
681
682	IO::AIO::poll_wait, IO::AIO::poll_cb
683	if IO::AIO::nreqs;
684		1039
685	=item IO::AIO::min_parallel $nthreads	1040	=item IO::AIO::min_parallel $nthreads
686		1041
687	Set the minimum number of AIO threads to C<$nthreads>. The current default	1042	Set the minimum number of AIO threads to C<$nthreads>. The current
688	is C<4>, which means four asynchronous operations can be done at one time	1043	default is C<8>, which means eight asynchronous operations can execute
689	(the number of outstanding operations, however, is unlimited).	1044	concurrently at any one time (the number of outstanding requests,
		1045	however, is unlimited).
690		1046
691	IO::AIO starts threads only on demand, when an AIO request is queued and	1047	IO::AIO starts threads only on demand, when an AIO request is queued and
692	no free thread exists.	1048	no free thread exists. Please note that queueing up a hundred requests can
		1049	create demand for a hundred threads, even if it turns out that everything
		1050	is in the cache and could have been processed faster by a single thread.
693		1051
694	It is recommended to keep the number of threads low, as some Linux	1052	It is recommended to keep the number of threads relatively low, as some
695	kernel versions will scale negatively with the number of threads (higher	1053	Linux kernel versions will scale negatively with the number of threads
696	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1054	(higher parallelity => MUCH higher latency). With current Linux 2.6
697	threads should be fine.	1055	versions, 4-32 threads should be fine.
698		1056
699	Under most circumstances you don't need to call this function, as the	1057	Under most circumstances you don't need to call this function, as the
700	module selects a default that is suitable for low to moderate load.	1058	module selects a default that is suitable for low to moderate load.
701		1059
702	=item IO::AIO::max_parallel $nthreads	1060	=item IO::AIO::max_parallel $nthreads
…		…
711	This module automatically runs C<max_parallel 0> at program end, to ensure	1069	This module automatically runs C<max_parallel 0> at program end, to ensure
712	that all threads are killed and that there are no outstanding requests.	1070	that all threads are killed and that there are no outstanding requests.
713		1071
714	Under normal circumstances you don't need to call this function.	1072	Under normal circumstances you don't need to call this function.
715		1073
		1074	=item IO::AIO::max_idle $nthreads
		1075
		1076	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1077	threads that did not get a request to process within 10 seconds). That
		1078	means if a thread becomes idle while C<$nthreads> other threads are also
		1079	idle, it will free its resources and exit.
		1080
		1081	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1082	to allow for extremely high load situations, but want to free resources
		1083	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1084
		1085	The default is probably ok in most situations, especially if thread
		1086	creation is fast. If thread creation is very slow on your system you might
		1087	want to use larger values.
		1088
716	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1089	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1090
		1091	This is a very bad function to use in interactive programs because it
		1092	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1093	use an C<aio_group> together with a feed callback.
717		1094
718	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1095	Sets the maximum number of outstanding requests to C<$nreqs>. If you
719	try to queue up more than this number of requests, the caller will block until	1096	to queue up more than this number of requests, the next call to the
720	some requests have been handled.	1097	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1098	function will block until the limit is no longer exceeded.
721		1099
722	The default is very large, so normally there is no practical limit. If you	1100	The default value is very large, so there is no practical limit on the
723	queue up many requests in a loop it often improves speed if you set	1101	number of outstanding requests.
724	this to a relatively low number, such as C<100>.
725		1102
726	Under normal circumstances you don't need to call this function.	1103	You can still queue as many requests as you want. Therefore,
		1104	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1105	as a stop gap to shield against fatal memory overflow (with large values).
		1106
		1107	=head3 STATISTICAL INFORMATION
		1108
		1109	=item IO::AIO::nreqs
		1110
		1111	Returns the number of requests currently in the ready, execute or pending
		1112	states (i.e. for which their callback has not been invoked yet).
		1113
		1114	Example: wait till there are no outstanding requests anymore:
		1115
		1116	IO::AIO::poll_wait, IO::AIO::poll_cb
		1117	while IO::AIO::nreqs;
		1118
		1119	=item IO::AIO::nready
		1120
		1121	Returns the number of requests currently in the ready state (not yet
		1122	executed).
		1123
		1124	=item IO::AIO::npending
		1125
		1126	Returns the number of requests currently in the pending state (executed,
		1127	but not yet processed by poll_cb).
727		1128
728	=back	1129	=back
729		1130
730	=cut	1131	=cut
731		1132
…		…
743	or return undef;	1144	or return undef;
744		1145
745	*$sym	1146	*$sym
746	}	1147	}
747		1148
748	min_parallel 4;	1149	min_parallel 8;
749		1150
750	END {	1151	END { flush }
751	max_parallel 0;
752	}
753		1152
754	1;	1153	1;
755		1154
756	=head2 FORK BEHAVIOUR	1155	=head2 FORK BEHAVIOUR
757		1156
758	This module should do "the right thing" when the process using it forks:	1157	This module should do "the right thing" when the process using it forks:
759		1158
760	Before the fork, IO::AIO enters a quiescent state where no requests	1159	Before the fork, IO::AIO enters a quiescent state where no requests
761	can be added in other threads and no results will be processed. After	1160	can be added in other threads and no results will be processed. After
762	the fork the parent simply leaves the quiescent state and continues	1161	the fork the parent simply leaves the quiescent state and continues
763	request/result processing, while the child clears the request/result	1162	request/result processing, while the child frees the request/result queue
764	queue (so the requests started before the fork will only be handled in	1163	(so that the requests started before the fork will only be handled in the
765	the parent). Threads will be started on demand until the limit ste in the	1164	parent). Threads will be started on demand until the limit set in the
766	parent process has been reached again.	1165	parent process has been reached again.
767		1166
768	In short: the parent will, after a short pause, continue as if fork had	1167	In short: the parent will, after a short pause, continue as if fork had
769	not been called, while the child will act as if IO::AIO has not been used	1168	not been called, while the child will act as if IO::AIO has not been used
770	yet.	1169	yet.
771		1170
		1171	=head2 MEMORY USAGE
		1172
		1173	Per-request usage:
		1174
		1175	Each aio request uses - depending on your architecture - around 100-200
		1176	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1177	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1178	scalars and other data passed into aio requests will also be locked and
		1179	will consume memory till the request has entered the done state.
		1180
		1181	This is now awfully much, so queuing lots of requests is not usually a
		1182	problem.
		1183
		1184	Per-thread usage:
		1185
		1186	In the execution phase, some aio requests require more memory for
		1187	temporary buffers, and each thread requires a stack and other data
		1188	structures (usually around 16k-128k, depending on the OS).
		1189
		1190	=head1 KNOWN BUGS
		1191
		1192	Known bugs will be fixed in the next release.
		1193
772	=head1 SEE ALSO	1194	=head1 SEE ALSO
773		1195
774	L<Coro>, L<Linux::AIO> (obsolete).	1196	L<Coro::AIO>.
775		1197
776	=head1 AUTHOR	1198	=head1 AUTHOR
777		1199
778	Marc Lehmann <schmorp@schmorp.de>	1200	Marc Lehmann <schmorp@schmorp.de>
779	http://home.schmorp.de/	1201	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs. Revision 1.98 by root, Sun Dec 31 17:07:32 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs.
Revision 1.98 by root, Sun Dec 31 17:07:32 2006 UTC