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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.58 by root, Sun Oct 22 10:33:19 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	[EXPERIMENTAL due to internal aio_group use]
188
189	Try to move the I<file> (directories not supported as either source or
190	destination) from C<$srcpath> to C<$dstpath> and call the callback with
191	the C<0> (error) or C<-1> ok.
192
193	This is a composite request that tries to rename(2) the file first. If
194	rename files with C<EXDEV>, it creates the destination file with mode 0200
195	and copies the contents of the source file into it using C<aio_sendfile>,
196	followed by restoring atime, mtime, access mode and uid/gid, in that
197	order, and unlinking the C<$srcpath>.
198
199	If an error occurs, the partial destination file will be unlinked, if
200	possible, except when setting atime, mtime, access mode and uid/gid, where
201	errors are being ignored.
202
203	=cut
204
205	sub aio_move($$$) {
206	my ($src, $dst, $cb) = @_;
207
208	my $grp = aio_group $cb;
209
210	add $grp aio_rename $src, $dst, sub {
211	if ($_[0] && $! == EXDEV) {
212	add $grp aio_open $src, O_RDONLY, 0, sub {
213	if (my $src_fh = $_[0]) {
214	my @stat = stat $src_fh;
215
216	add $grp aio_open $dst, O_WRONLY, 0200, sub {
217	if (my $dst_fh = $_[0]) {
218	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
219	close $src_fh;
220
221	if ($_[0] == $stat[7]) {
222	utime $stat[8], $stat[9], $dst;
223	chmod $stat[2] & 07777, $dst_fh;
224	chown $stat[4], $stat[5], $dst_fh;
225	close $dst_fh;
226
227	add $grp aio_unlink $src, sub {
228	$grp->result ($_[0]);
229	};
230	} else {
231	my $errno = $!;
232	add $grp aio_unlink $dst, sub {
233	$! = $errno;
234	$grp->result (-1);
235	};
236	}
237	};
238	} else {
239	$grp->result (-1);
240	}
241	},
242
243	} else {
244	$grp->result (-1);
245	}
246	};
247	} else {
248	$grp->result ($_[0]);
249	}
250	};
251
252	$grp
253	}
254
255	=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)
256		341
257	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
258	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
259	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
…		…
314	=item aio_unlink $pathname, $callback->($status)	399	=item aio_unlink $pathname, $callback->($status)
315		400
316	Asynchronously unlink (delete) a file and call the callback with the	401	Asynchronously unlink (delete) a file and call the callback with the
317	result code.	402	result code.
318		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
319	=item aio_link $srcpath, $dstpath, $callback->($status)	414	=item aio_link $srcpath, $dstpath, $callback->($status)
320		415
321	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
322	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.
323		418
324	=item aio_symlink $srcpath, $dstpath, $callback->($status)	419	=item aio_symlink $srcpath, $dstpath, $callback->($status)
325		420
326	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
327	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.
328		429
329	=item aio_rename $srcpath, $dstpath, $callback->($status)	430	=item aio_rename $srcpath, $dstpath, $callback->($status)
330		431
331	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
332	rename(2) and call the callback with the result code.	433	rename(2) and call the callback with the result code.
…		…
343	sorted, and will B<NOT> include the C<.> and C<..> entries.	444	sorted, and will B<NOT> include the C<.> and C<..> entries.
344		445
345	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
346	with the filenames.	447	with the filenames.
347		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
348	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	585	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
349		586
350	[EXPERIMENTAL due to internal aio_group use]
351
352	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
353	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
354	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
355	recurse into (everything else).	590	recurse into (everything else, including symlinks to directories).
356		591
357	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_
358	requests. C<$maxreq> specifies the maximum number of outstanding aio	593	C<$maxreq> specifies the maximum number of outstanding aio requests that
359	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
360	suitable default will be chosen (currently 8).	595	will be chosen (currently 4).
361		596
362	On error, the callback is called without arguments, otherwise it receives	597	On error, the callback is called without arguments, otherwise it receives
363	two array-refs with path-relative entry names.	598	two array-refs with path-relative entry names.
364		599
365	Example:	600	Example:
…		…
400	directory counting heuristic.	635	directory counting heuristic.
401		636
402	=cut	637	=cut
403		638
404	sub aio_scandir($$$) {	639	sub aio_scandir($$$) {
		640	aio_block {
405	my ($path, $maxreq, $cb) = @_;	641	my ($path, $maxreq, $cb) = @_;
406		642
		643	my $pri = aioreq_pri;
		644
407	my $grp = aio_group $cb;	645	my $grp = aio_group $cb;
408		646
409	$maxreq = 8 if $maxreq <= 0;	647	$maxreq = 4 if $maxreq <= 0;
410		648
411	# stat once	649	# stat once
		650	aioreq_pri $pri;
412	add $grp aio_stat $path, sub {	651	add $grp aio_stat $path, sub {
413	return $grp->result () if $_[0];	652	return $grp->result () if $_[0];
414	my $now = time;	653	my $now = time;
415	my $hash1 = join ":", (stat _)[0,1,3,7,9];	654	my $hash1 = join ":", (stat _)[0,1,3,7,9];
416		655
417	# read the directory entries	656	# read the directory entries
		657	aioreq_pri $pri;
418	add $grp aio_readdir $path, sub {	658	add $grp aio_readdir $path, sub {
419	my $entries = shift	659	my $entries = shift
420	or return $grp->result ();	660	or return $grp->result ();
421		661
422	# stat the dir another time	662	# stat the dir another time
		663	aioreq_pri $pri;
423	add $grp aio_stat $path, sub {	664	add $grp aio_stat $path, sub {
424	my $hash2 = join ":", (stat _)[0,1,3,7,9];	665	my $hash2 = join ":", (stat _)[0,1,3,7,9];
425		666
426	my $ndirs;	667	my $ndirs;
427		668
428	# take the slow route if anything looks fishy	669	# take the slow route if anything looks fishy
429	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	670	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
430	$ndirs = -1;	671	$ndirs = -1;
431	} else {	672	} else {
432	# if nlink == 2, we are finished	673	# if nlink == 2, we are finished
433	# on non-posix-fs's, we rely on nlink < 2	674	# on non-posix-fs's, we rely on nlink < 2
434	$ndirs = (stat _)[3] - 2	675	$ndirs = (stat _)[3] - 2
435	or return $grp->result ([], $entries);	676	or return $grp->result ([], $entries);
436	}
437
438	# sort into likely dirs and likely nondirs
439	# dirs == files without ".", short entries first
440	$entries = [map $_->[0],
441	sort { $b->[1] cmp $a->[1] }
442	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
443	@$entries];
444
445	my (@dirs, @nondirs);
446
447	my ($statcb, $schedcb);
448	my $nreq = 0;
449
450	$schedcb = sub {
451	if (@$entries) {
452	if ($nreq < $maxreq) {
453	my $ent = pop @$entries;
454	$nreq++;
455	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
456	}
457	} elsif (!$nreq) {
458	# finished
459	undef $statcb;
460	undef $schedcb;
461	$grp->result (\@dirs, \@nondirs) if $cb;
462	undef $cb;
463	}	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	};
464	};	719	};
465	$statcb = sub {
466	my ($status, $entry) = @_;
467
468	if ($status < 0) {
469	$nreq--;
470	push @nondirs, $entry;
471	&$schedcb;
472	} else {
473	# need to check for real directory
474	add $grp aio_lstat "$path/$entry", sub {
475	$nreq--;
476
477	if (-d _) {
478	push @dirs, $entry;
479
480	if (!--$ndirs) {
481	push @nondirs, @$entries;
482	$entries = [];
483	}
484	} else {
485	push @nondirs, $entry;
486	}
487
488	&$schedcb;
489	}
490	}
491	};
492
493	&$schedcb while @$entries && $nreq < $maxreq;
494	};	720	};
495	};	721	};
		722
		723	$grp
496	};	724	}
497
498	$grp
499	}	725	}
500		726
501	=item aio_fsync $fh, $callback->($status)	727	=item aio_fsync $fh, $callback->($status)
502		728
503	Asynchronously call fsync on the given filehandle and call the callback	729	Asynchronously call fsync on the given filehandle and call the callback
…		…
511	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
512	detected, it will be emulated by calling C<fsync> instead.	738	detected, it will be emulated by calling C<fsync> instead.
513		739
514	=item aio_group $callback->(...)	740	=item aio_group $callback->(...)
515		741
516	[EXPERIMENTAL]
517
518	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
519	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
520	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.
521		746
522	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
523	for more info.	748	for more info.
524		749
525	Example:	750	Example:
…		…
531	add $grp	756	add $grp
532	(aio_stat ...),	757	(aio_stat ...),
533	(aio_stat ...),	758	(aio_stat ...),
534	...;	759	...;
535		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
536	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	774	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
537		775
538	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
539	the request workers to sleep for the given time.	777	the request workers to sleep for the given time.
540		778
541	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
542	like sleep and file handle readable/writable, the overhead this creates	780	like sleep and file handle readable/writable, the overhead this creates is
543	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
544	under artificial I/O pressure.	782	except to put your application under artificial I/O pressure.
545		783
546	=back	784	=back
547		785
548	=head2 IO::AIO::REQ CLASS	786	=head2 IO::AIO::REQ CLASS
549		787
550	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
551	called in non-void context.	789	called in non-void context.
552		790
553	A request always moves through the following five states in its lifetime,
554	in order: B<ready> (request has been created, but has not been executed
555	yet), B<execute> (request is currently being executed), B<pending>
556	(request has been executed but callback has not been called yet),
557	B<result> (results are being processed synchronously, includes calling the
558	callback) and B<done> (request has reached the end of its lifetime and
559	holds no resources anymore).
560
561	=over 4	791	=over 4
562		792
563	=item $req->cancel	793	=item cancel $req
564		794
565	Cancels the request, if possible. Has the effect of skipping execution	795	Cancels the request, if possible. Has the effect of skipping execution
566	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
567	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
568	untouched. That means that requests that currently execute will not be	798	untouched. That means that requests that currently execute will not be
569	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.
570		800
		801	=item cb $req $callback->(...)
		802
		803	Replace (or simply set) the callback registered to the request.
		804
571	=back	805	=back
572		806
573	=head2 IO::AIO::GRP CLASS	807	=head2 IO::AIO::GRP CLASS
574		808
575	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
…		…
601	};	835	};
602		836
603	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
604	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.
605		839
		840	=over 4
		841
606	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
607	C<IO::AIO::poll_cb>, just like any other request.	843	C<IO::AIO::poll_cb>, just like any other request.
608		844
609	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
610	just the request itself, but also all requests it contains.	846	only the request itself, but also all requests it contains.
611		847
612	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
613		854
614	Their lifetime, simplified, looks like this: when they are empty, they	855	Their lifetime, simplified, looks like this: when they are empty, they
615	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
616	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
617	exist.	858	exist.
…		…
621	group. And only when all those requests have finished will the the group	862	group. And only when all those requests have finished will the the group
622	itself finish.	863	itself finish.
623		864
624	=over 4	865	=over 4
625		866
		867	=item add $grp ...
		868
626	=item $grp->add (...)	869	=item $grp->add (...)
627
628	=item add $grp ...
629		870
630	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	871	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
631	be added, including other groups, as long as you do not create circular	872	be added, including other groups, as long as you do not create circular
632	dependencies.	873	dependencies.
633		874
634	Returns all its arguments.	875	Returns all its arguments.
635		876
		877	=item $grp->cancel_subs
		878
		879	Cancel all subrequests and clears any feeder, but not the group request
		880	itself. Useful when you queued a lot of events but got a result early.
		881
636	=item $grp->result (...)	882	=item $grp->result (...)
637		883
638	Set the result value(s) that will be passed to the group callback when all	884	Set the result value(s) that will be passed to the group callback when all
639	subrequests have finished. By default, no argument will be passed.	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.
640		943
641	=back	944	=back
642		945
643	=head2 SUPPORT FUNCTIONS	946	=head2 SUPPORT FUNCTIONS
		947
		948	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
644		949
645	=over 4	950	=over 4
646		951
647	=item $fileno = IO::AIO::poll_fileno	952	=item $fileno = IO::AIO::poll_fileno
648		953
…		…
653		958
654	See C<poll_cb> for an example.	959	See C<poll_cb> for an example.
655		960
656	=item IO::AIO::poll_cb	961	=item IO::AIO::poll_cb
657		962
658	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
659	regularly. Returns the number of events processed. Returns immediately	964	regularly. Returns the number of events processed. Returns immediately
660	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.
661		970
662	Example: Install an Event watcher that automatically calls	971	Example: Install an Event watcher that automatically calls
663	IO::AIO::poll_cb with high priority:	972	IO::AIO::poll_cb with high priority:
664		973
665	Event->io (fd => IO::AIO::poll_fileno,	974	Event->io (fd => IO::AIO::poll_fileno,
666	poll => 'r', async => 1,	975	poll => 'r', async => 1,
667	cb => \&IO::AIO::poll_cb);	976	cb => \&IO::AIO::poll_cb);
668		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
669	=item IO::AIO::poll_wait	1011	=item IO::AIO::poll_wait
670		1012
		1013	If there are any outstanding requests and none of them in the result
671	Wait till the result filehandle becomes ready for reading (simply does a	1014	phase, wait till the result filehandle becomes ready for reading (simply
672	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
673	for some requests to finish).	1016	synchronously wait for some requests to finish).
674		1017
675	See C<nreqs> for an example.	1018	See C<nreqs> for an example.
676		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
677	=item IO::AIO::nreqs	1029	=item IO::AIO::flush
678		1030
679	Returns the number of requests currently outstanding (i.e. for which their	1031	Wait till all outstanding AIO requests have been handled.
680	callback has not been invoked yet).
681		1032
682	Example: wait till there are no outstanding requests anymore:	1033	Strictly equivalent to:
683		1034
684	IO::AIO::poll_wait, IO::AIO::poll_cb	1035	IO::AIO::poll_wait, IO::AIO::poll_cb
685	while IO::AIO::nreqs;	1036	while IO::AIO::nreqs;
686		1037
687	=item IO::AIO::flush	1038	=head3 CONTROLLING THE NUMBER OF THREADS
688
689	Wait till all outstanding AIO requests have been handled.
690
691	Strictly equivalent to:
692
693	IO::AIO::poll_wait, IO::AIO::poll_cb
694	while IO::AIO::nreqs;
695
696	=item IO::AIO::poll
697
698	Waits until some requests have been handled.
699
700	Strictly equivalent to:
701
702	IO::AIO::poll_wait, IO::AIO::poll_cb
703	if IO::AIO::nreqs;
704		1039
705	=item IO::AIO::min_parallel $nthreads	1040	=item IO::AIO::min_parallel $nthreads
706		1041
707	Set the minimum number of AIO threads to C<$nthreads>. The current default	1042	Set the minimum number of AIO threads to C<$nthreads>. The current
708	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
709	(the number of outstanding operations, however, is unlimited).	1044	concurrently at any one time (the number of outstanding requests,
		1045	however, is unlimited).
710		1046
711	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
712	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.
713		1051
714	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
715	kernel versions will scale negatively with the number of threads (higher	1053	Linux kernel versions will scale negatively with the number of threads
716	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1054	(higher parallelity => MUCH higher latency). With current Linux 2.6
717	threads should be fine.	1055	versions, 4-32 threads should be fine.
718		1056
719	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
720	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.
721		1059
722	=item IO::AIO::max_parallel $nthreads	1060	=item IO::AIO::max_parallel $nthreads
…		…
731	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
732	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.
733		1071
734	Under normal circumstances you don't need to call this function.	1072	Under normal circumstances you don't need to call this function.
735		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
736	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1089	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1090
		1091	This is a very bad function to use in interactive programs because it
		1092	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1093	use an C<aio_group> together with a feed callback.
737		1094
738	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1095	Sets the maximum number of outstanding requests to C<$nreqs>. If you
739	try to queue up more than this number of requests, the caller will block until	1096	to queue up more than this number of requests, the next call to the
740	some requests have been handled.	1097	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1098	function will block until the limit is no longer exceeded.
741		1099
742	The default is very large, so normally there is no practical limit. If you	1100	The default value is very large, so there is no practical limit on the
743	queue up many requests in a loop it often improves speed if you set	1101	number of outstanding requests.
744	this to a relatively low number, such as C<100>.
745		1102
746	Under normal circumstances you don't need to call this function.	1103	You can still queue as many requests as you want. Therefore,
		1104	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1105	as a stop gap to shield against fatal memory overflow (with large values).
		1106
		1107	=head3 STATISTICAL INFORMATION
		1108
		1109	=item IO::AIO::nreqs
		1110
		1111	Returns the number of requests currently in the ready, execute or pending
		1112	states (i.e. for which their callback has not been invoked yet).
		1113
		1114	Example: wait till there are no outstanding requests anymore:
		1115
		1116	IO::AIO::poll_wait, IO::AIO::poll_cb
		1117	while IO::AIO::nreqs;
		1118
		1119	=item IO::AIO::nready
		1120
		1121	Returns the number of requests currently in the ready state (not yet
		1122	executed).
		1123
		1124	=item IO::AIO::npending
		1125
		1126	Returns the number of requests currently in the pending state (executed,
		1127	but not yet processed by poll_cb).
747		1128
748	=back	1129	=back
749		1130
750	=cut	1131	=cut
751		1132
…		…
763	or return undef;	1144	or return undef;
764		1145
765	*$sym	1146	*$sym
766	}	1147	}
767		1148
768	min_parallel 4;	1149	min_parallel 8;
769		1150
770	END {	1151	END { flush }
771	max_parallel 0;
772	}
773		1152
774	1;	1153	1;
775		1154
776	=head2 FORK BEHAVIOUR	1155	=head2 FORK BEHAVIOUR
777		1156
778	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:
779		1158
780	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
781	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
782	the fork the parent simply leaves the quiescent state and continues	1161	the fork the parent simply leaves the quiescent state and continues
783	request/result processing, while the child clears the request/result	1162	request/result processing, while the child frees the request/result queue
784	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
785	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
786	parent process has been reached again.	1165	parent process has been reached again.
787		1166
788	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
789	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
790	yet.	1169	yet.
791		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
792	=head1 SEE ALSO	1194	=head1 SEE ALSO
793		1195
794	L<Coro>, L<Linux::AIO> (obsolete).	1196	L<Coro::AIO>.
795		1197
796	=head1 AUTHOR	1198	=head1 AUTHOR
797		1199
798	Marc Lehmann <schmorp@schmorp.de>	1200	Marc Lehmann <schmorp@schmorp.de>
799	http://home.schmorp.de/	1201	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.58 by root, Sun Oct 22 10:33:19 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 1.58 by root, Sun Oct 22 10:33:19 2006 UTC vs.
Revision 1.98 by root, Sun Dec 31 17:07:32 2006 UTC