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Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs.
Revision 1.183 by root, Sun Sep 12 03:40:05 2010 UTC

…		…
4		4
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", IO::AIO::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
16	aio_read $fh, 30000, 1024, $buffer, 0, sub {	17	aio_read $fh, 30000, 1024, $buffer, 0, sub {
17	$_[0] > 0 or die "read error: $!";	18	$_[0] > 0 or die "read error: $!";
18	};	19	};
19		20
20	use IO::AIO 2; # version has aio objects	21	# version 2+ has request and group objects
		22	use IO::AIO 2;
21		23
		24	aioreq_pri 4; # give next request a very high priority
22	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
23	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
24		27
25	# AnyEvent	28	my $grp = aio_group sub { print "all stats done\n" };
26	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	29	add $grp aio_stat "..." for ...;
27	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
28
29	# Event
30	Event->io (fd => IO::AIO::poll_fileno,
31	poll => 'r',
32	cb => \&IO::AIO::poll_cb);
33
34	# Glib/Gtk2
35	add_watch Glib::IO IO::AIO::poll_fileno,
36	in => sub { IO::AIO::poll_cb; 1 };
37
38	# Tk
39	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
40	readable => \&IO::AIO::poll_cb);
41
42	# Danga::Socket
43	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
44	\&IO::AIO::poll_cb);
45
46		30
47	=head1 DESCRIPTION	31	=head1 DESCRIPTION
48		32
49	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
50	operating system supports.	34	operating system supports. It is implemented as an interface to C<libeio>
		35	(L<http://software.schmorp.de/pkg/libeio.html>).
51		36
		37	Asynchronous means that operations that can normally block your program
		38	(e.g. reading from disk) will be done asynchronously: the operation
		39	will still block, but you can do something else in the meantime. This
		40	is extremely useful for programs that need to stay interactive even
		41	when doing heavy I/O (GUI programs, high performance network servers
		42	etc.), but can also be used to easily do operations in parallel that are
		43	normally done sequentially, e.g. stat'ing many files, which is much faster
		44	on a RAID volume or over NFS when you do a number of stat operations
		45	concurrently.
		46
		47	While most of this works on all types of file descriptors (for
		48	example sockets), using these functions on file descriptors that
		49	support nonblocking operation (again, sockets, pipes etc.) is
		50	very inefficient. Use an event loop for that (such as the L<EV>
		51	module): IO::AIO will naturally fit into such an event loop itself.
		52
52	Currently, a number of threads are started that execute your read/writes	53	In this version, a number of threads are started that execute your
53	and signal their completion. You don't need thread support in your libc or	54	requests and signal their completion. You don't need thread support
54	perl, and the threads created by this module will not be visible to the	55	in perl, and the threads created by this module will not be visible
55	pthreads library. In the future, this module might make use of the native	56	to perl. In the future, this module might make use of the native aio
56	aio functions available on many operating systems. However, they are often	57	functions available on many operating systems. However, they are often
57	not well-supported (Linux doesn't allow them on normal files currently,	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
58	for example), and they would only support aio_read and aio_write, so the	59	files currently, for example), and they would only support aio_read and
59	remaining functionality would have to be implemented using threads anyway.	60	aio_write, so the remaining functionality would have to be implemented
		61	using threads anyway.
60		62
61	Although the module will work with in the presence of other threads, it is	63	Although the module will work in the presence of other (Perl-) threads,
62	currently not reentrant, so use appropriate locking yourself, always call	64	it is currently not reentrant in any way, so use appropriate locking
63	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	65	yourself, always call C<poll_cb> from within the same thread, or never
64	C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
		67
		68	=head2 EXAMPLE
		69
		70	This is a simple example that uses the EV module and loads
		71	F</etc/passwd> asynchronously:
		72
		73	use Fcntl;
		74	use EV;
		75	use IO::AIO;
		76
		77	# register the IO::AIO callback with EV
		78	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		79
		80	# queue the request to open /etc/passwd
		81	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
		82	my $fh = shift
		83	or die "error while opening: $!";
		84
		85	# stat'ing filehandles is generally non-blocking
		86	my $size = -s $fh;
		87
		88	# queue a request to read the file
		89	my $contents;
		90	aio_read $fh, 0, $size, $contents, 0, sub {
		91	$_[0] == $size
		92	or die "short read: $!";
		93
		94	close $fh;
		95
		96	# file contents now in $contents
		97	print $contents;
		98
		99	# exit event loop and program
		100	EV::unloop;
		101	};
		102	};
		103
		104	# possibly queue up other requests, or open GUI windows,
		105	# check for sockets etc. etc.
		106
		107	# process events as long as there are some:
		108	EV::loop;
		109
		110	=head1 REQUEST ANATOMY AND LIFETIME
		111
		112	Every C<aio_*> function creates a request. which is a C data structure not
		113	directly visible to Perl.
		114
		115	If called in non-void context, every request function returns a Perl
		116	object representing the request. In void context, nothing is returned,
		117	which saves a bit of memory.
		118
		119	The perl object is a fairly standard ref-to-hash object. The hash contents
		120	are not used by IO::AIO so you are free to store anything you like in it.
		121
		122	During their existance, aio requests travel through the following states,
		123	in order:
		124
		125	=over 4
		126
		127	=item ready
		128
		129	Immediately after a request is created it is put into the ready state,
		130	waiting for a thread to execute it.
		131
		132	=item execute
		133
		134	A thread has accepted the request for processing and is currently
		135	executing it (e.g. blocking in read).
		136
		137	=item pending
		138
		139	The request has been executed and is waiting for result processing.
		140
		141	While request submission and execution is fully asynchronous, result
		142	processing is not and relies on the perl interpreter calling C<poll_cb>
		143	(or another function with the same effect).
		144
		145	=item result
		146
		147	The request results are processed synchronously by C<poll_cb>.
		148
		149	The C<poll_cb> function will process all outstanding aio requests by
		150	calling their callbacks, freeing memory associated with them and managing
		151	any groups they are contained in.
		152
		153	=item done
		154
		155	Request has reached the end of its lifetime and holds no resources anymore
		156	(except possibly for the Perl object, but its connection to the actual
		157	aio request is severed and calling its methods will either do nothing or
		158	result in a runtime error).
		159
		160	=back
65		161
66	=cut	162	=cut
67		163
68	package IO::AIO;	164	package IO::AIO;
69		165
70	no warnings;	166	use Carp ();
71	use strict 'vars';	167
		168	use common::sense;
72		169
73	use base 'Exporter';	170	use base 'Exporter';
74		171
75	BEGIN {	172	BEGIN {
76	our $VERSION = '2.0';	173	our $VERSION = '3.65';
77		174
78	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	175	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
79	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	176	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
80	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	177	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
		178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		179	aio_rename aio_link aio_move aio_copy aio_group
		180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		181	aio_chmod aio_utime aio_truncate
		182	aio_msync aio_mtouch aio_mlock aio_mlockall
81	aio_group);	183	aio_statvfs);
82	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	184
		185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		187	min_parallel max_parallel max_idle
		188	nreqs nready npending nthreads
		189	max_poll_time max_poll_reqs
		190	sendfile fadvise madvise
		191	mmap munmap munlock munlockall);
		192
		193	push @AIO_REQ, qw(aio_busy); # not exported
83		194
84	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
85		196
86	require XSLoader;	197	require XSLoader;
87	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
88	}	199	}
89		200
90	=head1 FUNCTIONS	201	=head1 FUNCTIONS
91		202
		203	=head2 QUICK OVERVIEW
		204
		205	This section simply lists the prototypes of the most important functions
		206	for quick reference. See the following sections for function-by-function
		207	documentation.
		208
		209	aio_open $pathname, $flags, $mode, $callback->($fh)
		210	aio_close $fh, $callback->($status)
		211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		214	aio_readahead $fh,$offset,$length, $callback->($retval)
		215	aio_stat $fh_or_path, $callback->($status)
		216	aio_lstat $fh, $callback->($status)
		217	aio_statvfs $fh_or_path, $callback->($statvfs)
		218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		220	aio_truncate $fh_or_path, $offset, $callback->($status)
		221	aio_chmod $fh_or_path, $mode, $callback->($status)
		222	aio_unlink $pathname, $callback->($status)
		223	aio_mknod $path, $mode, $dev, $callback->($status)
		224	aio_link $srcpath, $dstpath, $callback->($status)
		225	aio_symlink $srcpath, $dstpath, $callback->($status)
		226	aio_readlink $path, $callback->($link)
		227	aio_rename $srcpath, $dstpath, $callback->($status)
		228	aio_mkdir $pathname, $mode, $callback->($status)
		229	aio_rmdir $pathname, $callback->($status)
		230	aio_readdir $pathname, $callback->($entries)
		231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		233	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		234	aio_load $path, $data, $callback->($status)
		235	aio_copy $srcpath, $dstpath, $callback->($status)
		236	aio_move $srcpath, $dstpath, $callback->($status)
		237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		238	aio_rmtree $path, $callback->($status)
		239	aio_sync $callback->($status)
		240	aio_fsync $fh, $callback->($status)
		241	aio_fdatasync $fh, $callback->($status)
		242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		243	aio_pathsync $path, $callback->($status)
		244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		247	aio_mlockall $flags, $callback->($status)
		248	aio_group $callback->(...)
		249	aio_nop $callback->()
		250
		251	$prev_pri = aioreq_pri [$pri]
		252	aioreq_nice $pri_adjust
		253
		254	IO::AIO::poll_wait
		255	IO::AIO::poll_cb
		256	IO::AIO::poll
		257	IO::AIO::flush
		258	IO::AIO::max_poll_reqs $nreqs
		259	IO::AIO::max_poll_time $seconds
		260	IO::AIO::min_parallel $nthreads
		261	IO::AIO::max_parallel $nthreads
		262	IO::AIO::max_idle $nthreads
		263	IO::AIO::max_outstanding $maxreqs
		264	IO::AIO::nreqs
		265	IO::AIO::nready
		266	IO::AIO::npending
		267
		268	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		269	IO::AIO::fadvise $fh, $offset, $len, $advice
		270	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		271	IO::AIO::munlockall
		272
92	=head2 AIO FUNCTIONS	273	=head2 AIO REQUEST FUNCTIONS
93		274
94	All the C<aio_*> calls are more or less thin wrappers around the syscall	275	All the C<aio_*> calls are more or less thin wrappers around the syscall
95	with the same name (sans C<aio_>). The arguments are similar or identical,	276	with the same name (sans C<aio_>). The arguments are similar or identical,
96	and they all accept an additional (and optional) C<$callback> argument	277	and they all accept an additional (and optional) C<$callback> argument
97	which must be a code reference. This code reference will get called with	278	which must be a code reference. This code reference will get called with
98	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	279	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
99	perl, which usually delivers "false") as it's sole argument when the given	280	perl, which usually delivers "false") as its sole argument after the given
100	syscall has been executed asynchronously.	281	syscall has been executed asynchronously.
101		282
102	All functions expecting a filehandle keep a copy of the filehandle	283	All functions expecting a filehandle keep a copy of the filehandle
103	internally until the request has finished.	284	internally until the request has finished.
104		285
105	All requests return objects of type L<IO::AIO::REQ> that allow further	286	All functions return request objects of type L<IO::AIO::REQ> that allow
106	manipulation of those requests while they are in-flight.	287	further manipulation of those requests while they are in-flight.
107		288
108	The pathnames you pass to these routines I<must> be absolute and	289	The pathnames you pass to these routines I<must> be absolute and
109	encoded in byte form. The reason for the former is that at the time the	290	encoded as octets. The reason for the former is that at the time the
110	request is being executed, the current working directory could have	291	request is being executed, the current working directory could have
111	changed. Alternatively, you can make sure that you never change the	292	changed. Alternatively, you can make sure that you never change the
112	current working directory.	293	current working directory anywhere in the program and then use relative
		294	paths.
113		295
114	To encode pathnames to byte form, either make sure you either: a)	296	To encode pathnames as octets, either make sure you either: a) always pass
115	always pass in filenames you got from outside (command line, readdir	297	in filenames you got from outside (command line, readdir etc.) without
116	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	298	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
117	your pathnames to the locale (or other) encoding in effect in the user	299	your pathnames to the locale (or other) encoding in effect in the user
118	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	300	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
119	use something else.	301	use something else to ensure your scalar has the correct contents.
		302
		303	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		304	handles correctly whether it is set or not.
120		305
121	=over 4	306	=over 4
		307
		308	=item $prev_pri = aioreq_pri [$pri]
		309
		310	Returns the priority value that would be used for the next request and, if
		311	C<$pri> is given, sets the priority for the next aio request.
		312
		313	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		314	and C<4>, respectively. Requests with higher priority will be serviced
		315	first.
		316
		317	The priority will be reset to C<0> after each call to one of the C<aio_*>
		318	functions.
		319
		320	Example: open a file with low priority, then read something from it with
		321	higher priority so the read request is serviced before other low priority
		322	open requests (potentially spamming the cache):
		323
		324	aioreq_pri -3;
		325	aio_open ..., sub {
		326	return unless $_[0];
		327
		328	aioreq_pri -2;
		329	aio_read $_[0], ..., sub {
		330	...
		331	};
		332	};
		333
		334
		335	=item aioreq_nice $pri_adjust
		336
		337	Similar to C<aioreq_pri>, but subtracts the given value from the current
		338	priority, so the effect is cumulative.
		339
122		340
123	=item aio_open $pathname, $flags, $mode, $callback->($fh)	341	=item aio_open $pathname, $flags, $mode, $callback->($fh)
124		342
125	Asynchronously open or create a file and call the callback with a newly	343	Asynchronously open or create a file and call the callback with a newly
126	created filehandle for the file.	344	created filehandle for the file.
…		…
132	list. They are the same as used by C<sysopen>.	350	list. They are the same as used by C<sysopen>.
133		351
134	Likewise, C<$mode> specifies the mode of the newly created file, if it	352	Likewise, C<$mode> specifies the mode of the newly created file, if it
135	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	353	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
136	except that it is mandatory (i.e. use C<0> if you don't create new files,	354	except that it is mandatory (i.e. use C<0> if you don't create new files,
137	and C<0666> or C<0777> if you do).	355	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		356	by the umask in effect then the request is being executed, so better never
		357	change the umask.
138		358
139	Example:	359	Example:
140		360
141	aio_open "/etc/passwd", O_RDONLY, 0, sub {	361	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
142	if ($_[0]) {	362	if ($_[0]) {
143	print "open successful, fh is $_[0]\n";	363	print "open successful, fh is $_[0]\n";
144	...	364	...
145	} else {	365	} else {
146	die "open failed: $!\n";	366	die "open failed: $!\n";
147	}	367	}
148	};	368	};
149		369
		370
150	=item aio_close $fh, $callback->($status)	371	=item aio_close $fh, $callback->($status)
151		372
152	Asynchronously close a file and call the callback with the result	373	Asynchronously close a file and call the callback with the result
153	code. I<WARNING:> although accepted, you should not pass in a perl	374	code.
154	filehandle here, as perl will likely close the file descriptor another
155	time when the filehandle is destroyed. Normally, you can safely call perls
156	C<close> or just let filehandles go out of scope.
157		375
158	This is supposed to be a bug in the API, so that might change. It's	376	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
159	therefore best to avoid this function.	377	closing the file descriptor associated with the filehandle itself.
		378
		379	Therefore, C<aio_close> will not close the filehandle - instead it will
		380	use dup2 to overwrite the file descriptor with the write-end of a pipe
		381	(the pipe fd will be created on demand and will be cached).
		382
		383	Or in other words: the file descriptor will be closed, but it will not be
		384	free for reuse until the perl filehandle is closed.
		385
		386	=cut
160		387
161	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	388	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
162		389
163	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	390	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
164		391
165	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	392	Reads or writes C<$length> bytes from or to the specified C<$fh> and
166	into the scalar given by C<data> and offset C<dataoffset> and calls the	393	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
167	callback without the actual number of bytes read (or -1 on error, just	394	and calls the callback without the actual number of bytes read (or -1 on
168	like the syscall).	395	error, just like the syscall).
		396
		397	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		398	offset plus the actual number of bytes read.
		399
		400	If C<$offset> is undefined, then the current file descriptor offset will
		401	be used (and updated), otherwise the file descriptor offset will not be
		402	changed by these calls.
		403
		404	If C<$length> is undefined in C<aio_write>, use the remaining length of
		405	C<$data>.
		406
		407	If C<$dataoffset> is less than zero, it will be counted from the end of
		408	C<$data>.
169		409
170	The C<$data> scalar I<MUST NOT> be modified in any way while the request	410	The C<$data> scalar I<MUST NOT> be modified in any way while the request
171	is outstanding. Modifying it can result in segfaults or WW3 (if the	411	is outstanding. Modifying it can result in segfaults or World War III (if
172	necessary/optional hardware is installed).	412	the necessary/optional hardware is installed).
173		413
174	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	414	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
175	offset C<0> within the scalar:	415	offset C<0> within the scalar:
176		416
177	aio_read $fh, 7, 15, $buffer, 0, sub {	417	aio_read $fh, 7, 15, $buffer, 0, sub {
178	$_[0] > 0 or die "read error: $!";	418	$_[0] > 0 or die "read error: $!";
179	print "read $_[0] bytes: <$buffer>\n";	419	print "read $_[0] bytes: <$buffer>\n";
180	};	420	};
181		421
182	=item aio_move $srcpath, $dstpath, $callback->($status)
183
184	Try to move the I<file> (directories not supported as either source or
185	destination) from C<$srcpath> to C<$dstpath> and call the callback with
186	the C<0> (error) or C<-1> ok.
187
188	This is a composite request that tries to rename(2) the file first. If
189	rename files with C<EXDEV>, it creates the destination file with mode 0200
190	and copies the contents of the source file into it using C<aio_sendfile>,
191	followed by restoring atime, mtime, access mode and uid/gid, in that
192	order, and unlinking the C<$srcpath>.
193
194	If an error occurs, the partial destination file will be unlinked, if
195	possible, except when setting atime, mtime, access mode and uid/gid, where
196	errors are being ignored.
197
198	=cut
199
200	sub aio_move($$$) {
201	my ($src, $dst, $cb) = @_;
202
203	my $grp = aio_group;
204
205	add $grp aio_rename $src, $dst, sub {
206	if ($_[0] && $! == EXDEV) {
207	add $grp aio_open $src, O_RDONLY, 0, sub {
208	if (my $src_fh = $_[0]) {
209	my @stat = stat $src_fh;
210
211	add $grp aio_open $dst, O_WRONLY, 0200, sub {
212	if (my $dst_fh = $_[0]) {
213	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
214	close $src_fh;
215
216	if ($_[0] == $stat[7]) {
217	utime $stat[8], $stat[9], $dst;
218	chmod $stat[2] & 07777, $dst_fh;
219	chown $stat[4], $stat[5], $dst_fh;
220	close $dst_fh;
221
222	add $grp aio_unlink $src, sub {
223	$cb->($_[0]);
224	};
225	} else {
226	my $errno = $!;
227	add $grp aio_unlink $dst, sub {
228	$! = $errno;
229	$cb->(-1);
230	};
231	}
232	};
233	} else {
234	$cb->(-1);
235	}
236	},
237
238	} else {
239	$cb->(-1);
240	}
241	};
242	} else {
243	$cb->($_[0]);
244	}
245	};
246
247	$grp
248	}
249		422
250	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	423	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
251		424
252	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	425	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
253	reading at byte offset C<$in_offset>, and starts writing at the current	426	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
255	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	428	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
256	other.	429	other.
257		430
258	This call tries to make use of a native C<sendfile> syscall to provide	431	This call tries to make use of a native C<sendfile> syscall to provide
259	zero-copy operation. For this to work, C<$out_fh> should refer to a	432	zero-copy operation. For this to work, C<$out_fh> should refer to a
260	socket, and C<$in_fh> should refer to mmap'able file.	433	socket, and C<$in_fh> should refer to an mmap'able file.
261		434
262	If the native sendfile call fails or is not implemented, it will be	435	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		436	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
263	emulated, so you can call C<aio_sendfile> on any type of filehandle	437	it will be emulated, so you can call C<aio_sendfile> on any type of
264	regardless of the limitations of the operating system.	438	filehandle regardless of the limitations of the operating system.
265		439
266	Please note, however, that C<aio_sendfile> can read more bytes from	440	Please note, however, that C<aio_sendfile> can read more bytes from
267	C<$in_fh> than are written, and there is no way to find out how many	441	C<$in_fh> than are written, and there is no way to find out how many
268	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	442	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
269	provides the number of bytes written to C<$out_fh>. Only if the result	443	provides the number of bytes written to C<$out_fh>. Only if the result
270	value equals C<$length> one can assume that C<$length> bytes have been	444	value equals C<$length> one can assume that C<$length> bytes have been
271	read.	445	read.
		446
272		447
273	=item aio_readahead $fh,$offset,$length, $callback->($retval)	448	=item aio_readahead $fh,$offset,$length, $callback->($retval)
274		449
275	C<aio_readahead> populates the page cache with data from a file so that	450	C<aio_readahead> populates the page cache with data from a file so that
276	subsequent reads from that file will not block on disk I/O. The C<$offset>	451	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
282	file. The current file offset of the file is left unchanged.	457	file. The current file offset of the file is left unchanged.
283		458
284	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	459	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
285	emulated by simply reading the data, which would have a similar effect.	460	emulated by simply reading the data, which would have a similar effect.
286		461
		462
287	=item aio_stat $fh_or_path, $callback->($status)	463	=item aio_stat $fh_or_path, $callback->($status)
288		464
289	=item aio_lstat $fh, $callback->($status)	465	=item aio_lstat $fh, $callback->($status)
290		466
291	Works like perl's C<stat> or C<lstat> in void context. The callback will	467	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
304	aio_stat "/etc/passwd", sub {	480	aio_stat "/etc/passwd", sub {
305	$_[0] and die "stat failed: $!";	481	$_[0] and die "stat failed: $!";
306	print "size is ", -s _, "\n";	482	print "size is ", -s _, "\n";
307	};	483	};
308		484
		485
		486	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		487
		488	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		489	whether a file handle or path was passed.
		490
		491	On success, the callback is passed a hash reference with the following
		492	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		493	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		494	is passed.
		495
		496	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		497	C<ST_NOSUID>.
		498
		499	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		500	their correct value when available, or to C<0> on systems that do
		501	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		502	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		503	C<ST_NODIRATIME> and C<ST_RELATIME>.
		504
		505	Example: stat C</wd> and dump out the data if successful.
		506
		507	aio_statvfs "/wd", sub {
		508	my $f = $_[0]
		509	or die "statvfs: $!";
		510
		511	use Data::Dumper;
		512	say Dumper $f;
		513	};
		514
		515	# result:
		516	{
		517	bsize => 1024,
		518	bfree => 4333064312,
		519	blocks => 10253828096,
		520	files => 2050765568,
		521	flag => 4096,
		522	favail => 2042092649,
		523	bavail => 4333064312,
		524	ffree => 2042092649,
		525	namemax => 255,
		526	frsize => 1024,
		527	fsid => 1810
		528	}
		529
		530
		531	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		532
		533	Works like perl's C<utime> function (including the special case of $atime
		534	and $mtime being undef). Fractional times are supported if the underlying
		535	syscalls support them.
		536
		537	When called with a pathname, uses utimes(2) if available, otherwise
		538	utime(2). If called on a file descriptor, uses futimes(2) if available,
		539	otherwise returns ENOSYS, so this is not portable.
		540
		541	Examples:
		542
		543	# set atime and mtime to current time (basically touch(1)):
		544	aio_utime "path", undef, undef;
		545	# set atime to current time and mtime to beginning of the epoch:
		546	aio_utime "path", time, undef; # undef==0
		547
		548
		549	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		550
		551	Works like perl's C<chown> function, except that C<undef> for either $uid
		552	or $gid is being interpreted as "do not change" (but -1 can also be used).
		553
		554	Examples:
		555
		556	# same as "chown root path" in the shell:
		557	aio_chown "path", 0, -1;
		558	# same as above:
		559	aio_chown "path", 0, undef;
		560
		561
		562	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		563
		564	Works like truncate(2) or ftruncate(2).
		565
		566
		567	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		568
		569	Works like perl's C<chmod> function.
		570
		571
309	=item aio_unlink $pathname, $callback->($status)	572	=item aio_unlink $pathname, $callback->($status)
310		573
311	Asynchronously unlink (delete) a file and call the callback with the	574	Asynchronously unlink (delete) a file and call the callback with the
312	result code.	575	result code.
313		576
		577
		578	=item aio_mknod $path, $mode, $dev, $callback->($status)
		579
		580	[EXPERIMENTAL]
		581
		582	Asynchronously create a device node (or fifo). See mknod(2).
		583
		584	The only (POSIX-) portable way of calling this function is:
		585
		586	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		587
		588
314	=item aio_link $srcpath, $dstpath, $callback->($status)	589	=item aio_link $srcpath, $dstpath, $callback->($status)
315		590
316	Asynchronously create a new link to the existing object at C<$srcpath> at	591	Asynchronously create a new link to the existing object at C<$srcpath> at
317	the path C<$dstpath> and call the callback with the result code.	592	the path C<$dstpath> and call the callback with the result code.
318		593
		594
319	=item aio_symlink $srcpath, $dstpath, $callback->($status)	595	=item aio_symlink $srcpath, $dstpath, $callback->($status)
320		596
321	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	597	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
322	the path C<$dstpath> and call the callback with the result code.	598	the path C<$dstpath> and call the callback with the result code.
323		599
		600
		601	=item aio_readlink $path, $callback->($link)
		602
		603	Asynchronously read the symlink specified by C<$path> and pass it to
		604	the callback. If an error occurs, nothing or undef gets passed to the
		605	callback.
		606
		607
324	=item aio_rename $srcpath, $dstpath, $callback->($status)	608	=item aio_rename $srcpath, $dstpath, $callback->($status)
325		609
326	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	610	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
327	rename(2) and call the callback with the result code.	611	rename(2) and call the callback with the result code.
328		612
		613
		614	=item aio_mkdir $pathname, $mode, $callback->($status)
		615
		616	Asynchronously mkdir (create) a directory and call the callback with
		617	the result code. C<$mode> will be modified by the umask at the time the
		618	request is executed, so do not change your umask.
		619
		620
329	=item aio_rmdir $pathname, $callback->($status)	621	=item aio_rmdir $pathname, $callback->($status)
330		622
331	Asynchronously rmdir (delete) a directory and call the callback with the	623	Asynchronously rmdir (delete) a directory and call the callback with the
332	result code.	624	result code.
		625
333		626
334	=item aio_readdir $pathname, $callback->($entries)	627	=item aio_readdir $pathname, $callback->($entries)
335		628
336	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	629	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
337	directory (i.e. opendir + readdir + closedir). The entries will not be	630	directory (i.e. opendir + readdir + closedir). The entries will not be
338	sorted, and will B<NOT> include the C<.> and C<..> entries.	631	sorted, and will B<NOT> include the C<.> and C<..> entries.
339		632
340	The callback a single argument which is either C<undef> or an array-ref	633	The callback is passed a single argument which is either C<undef> or an
341	with the filenames.	634	array-ref with the filenames.
		635
		636
		637	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		638
		639	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		640	behaviour and output format. In case of an error, C<$entries> will be
		641	C<undef>.
		642
		643	The flags are a combination of the following constants, ORed together (the
		644	flags will also be passed to the callback, possibly modified):
		645
		646	=over 4
		647
		648	=item IO::AIO::READDIR_DENTS
		649
		650	When this flag is off, then the callback gets an arrayref with of names
		651	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		652	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		653	entry in more detail.
		654
		655	C<$name> is the name of the entry.
		656
		657	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		658
		659	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		660	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		661	C<IO::AIO::DT_WHT>.
		662
		663	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		664	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		665	scalars are read-only: you can not modify them.
		666
		667	C<$inode> is the inode number (which might not be exact on systems with 64
		668	bit inode numbers and 32 bit perls). This field has unspecified content on
		669	systems that do not deliver the inode information.
		670
		671	=item IO::AIO::READDIR_DIRS_FIRST
		672
		673	When this flag is set, then the names will be returned in an order where
		674	likely directories come first. This is useful when you need to quickly
		675	find directories, or you want to find all directories while avoiding to
		676	stat() each entry.
		677
		678	If the system returns type information in readdir, then this is used
		679	to find directories directly. Otherwise, likely directories are files
		680	beginning with ".", or otherwise files with no dots, of which files with
		681	short names are tried first.
		682
		683	=item IO::AIO::READDIR_STAT_ORDER
		684
		685	When this flag is set, then the names will be returned in an order
		686	suitable for stat()'ing each one. That is, when you plan to stat()
		687	all files in the given directory, then the returned order will likely
		688	be fastest.
		689
		690	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		691	the likely dirs come first, resulting in a less optimal stat order.
		692
		693	=item IO::AIO::READDIR_FOUND_UNKNOWN
		694
		695	This flag should not be set when calling C<aio_readdirx>. Instead, it
		696	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		697	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		698	C<$type>'s are known, which can be used to speed up some algorithms.
		699
		700	=back
		701
		702
		703	=item aio_load $path, $data, $callback->($status)
		704
		705	This is a composite request that tries to fully load the given file into
		706	memory. Status is the same as with aio_read.
		707
		708	=cut
		709
		710	sub aio_load($$;$) {
		711	my ($path, undef, $cb) = @_;
		712	my $data = \$_[1];
		713
		714	my $pri = aioreq_pri;
		715	my $grp = aio_group $cb;
		716
		717	aioreq_pri $pri;
		718	add $grp aio_open $path, O_RDONLY, 0, sub {
		719	my $fh = shift
		720	or return $grp->result (-1);
		721
		722	aioreq_pri $pri;
		723	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		724	$grp->result ($_[0]);
		725	};
		726	};
		727
		728	$grp
		729	}
		730
		731	=item aio_copy $srcpath, $dstpath, $callback->($status)
		732
		733	Try to copy the I<file> (directories not supported as either source or
		734	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		735	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		736
		737	This is a composite request that creates the destination file with
		738	mode 0200 and copies the contents of the source file into it using
		739	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		740	uid/gid, in that order.
		741
		742	If an error occurs, the partial destination file will be unlinked, if
		743	possible, except when setting atime, mtime, access mode and uid/gid, where
		744	errors are being ignored.
		745
		746	=cut
		747
		748	sub aio_copy($$;$) {
		749	my ($src, $dst, $cb) = @_;
		750
		751	my $pri = aioreq_pri;
		752	my $grp = aio_group $cb;
		753
		754	aioreq_pri $pri;
		755	add $grp aio_open $src, O_RDONLY, 0, sub {
		756	if (my $src_fh = $_[0]) {
		757	my @stat = stat $src_fh; # hmm, might block over nfs?
		758
		759	aioreq_pri $pri;
		760	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		761	if (my $dst_fh = $_[0]) {
		762	aioreq_pri $pri;
		763	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		764	if ($_[0] == $stat[7]) {
		765	$grp->result (0);
		766	close $src_fh;
		767
		768	my $ch = sub {
		769	aioreq_pri $pri;
		770	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		771	aioreq_pri $pri;
		772	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		773	aioreq_pri $pri;
		774	add $grp aio_close $dst_fh;
		775	}
		776	};
		777	};
		778
		779	aioreq_pri $pri;
		780	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		781	if ($_[0] < 0 && $! == ENOSYS) {
		782	aioreq_pri $pri;
		783	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		784	} else {
		785	$ch->();
		786	}
		787	};
		788	} else {
		789	$grp->result (-1);
		790	close $src_fh;
		791	close $dst_fh;
		792
		793	aioreq $pri;
		794	add $grp aio_unlink $dst;
		795	}
		796	};
		797	} else {
		798	$grp->result (-1);
		799	}
		800	},
		801
		802	} else {
		803	$grp->result (-1);
		804	}
		805	};
		806
		807	$grp
		808	}
		809
		810	=item aio_move $srcpath, $dstpath, $callback->($status)
		811
		812	Try to move the I<file> (directories not supported as either source or
		813	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		814	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		815
		816	This is a composite request that tries to rename(2) the file first; if
		817	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		818	that is successful, unlinks the C<$srcpath>.
		819
		820	=cut
		821
		822	sub aio_move($$;$) {
		823	my ($src, $dst, $cb) = @_;
		824
		825	my $pri = aioreq_pri;
		826	my $grp = aio_group $cb;
		827
		828	aioreq_pri $pri;
		829	add $grp aio_rename $src, $dst, sub {
		830	if ($_[0] && $! == EXDEV) {
		831	aioreq_pri $pri;
		832	add $grp aio_copy $src, $dst, sub {
		833	$grp->result ($_[0]);
		834
		835	if (!$_[0]) {
		836	aioreq_pri $pri;
		837	add $grp aio_unlink $src;
		838	}
		839	};
		840	} else {
		841	$grp->result ($_[0]);
		842	}
		843	};
		844
		845	$grp
		846	}
342		847
343	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	848	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
344		849
345	Scans a directory (similar to C<aio_readdir>) but additionally tries to	850	Scans a directory (similar to C<aio_readdir>) but additionally tries to
346	separate the entries of directory C<$path> into two sets of names, ones	851	efficiently separate the entries of directory C<$path> into two sets of
347	you can recurse into (directories or links to them), and ones you cannot	852	names, directories you can recurse into (directories), and ones you cannot
348	recurse into (everything else).	853	recurse into (everything else, including symlinks to directories).
349		854
350	C<aio_scandir> is a composite request that consists of many sub	855	C<aio_scandir> is a composite request that creates of many sub requests_
351	requests. C<$maxreq> specifies the maximum number of outstanding aio	856	C<$maxreq> specifies the maximum number of outstanding aio requests that
352	requests that this function generates. If it is C<< <= 0 >>, then a	857	this function generates. If it is C<< <= 0 >>, then a suitable default
353	suitable default will be chosen (currently 8).	858	will be chosen (currently 4).
354		859
355	On error, the callback is called without arguments, otherwise it receives	860	On error, the callback is called without arguments, otherwise it receives
356	two array-refs with path-relative entry names.	861	two array-refs with path-relative entry names.
357		862
358	Example:	863	Example:
…		…
365		870
366	Implementation notes.	871	Implementation notes.
367		872
368	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	873	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
369		874
		875	If readdir returns file type information, then this is used directly to
		876	find directories.
		877
370	After reading the directory, the modification time, size etc. of the	878	Otherwise, after reading the directory, the modification time, size etc.
371	directory before and after the readdir is checked, and if they match (and	879	of the directory before and after the readdir is checked, and if they
372	isn't the current time), the link count will be used to decide how many	880	match (and isn't the current time), the link count will be used to decide
373	entries are directories (if >= 2). Otherwise, no knowledge of the number	881	how many entries are directories (if >= 2). Otherwise, no knowledge of the
374	of subdirectories will be assumed.	882	number of subdirectories will be assumed.
375		883
376	Then entries will be sorted into likely directories (everything without	884	Then entries will be sorted into likely directories a non-initial dot
377	a non-initial dot currently) and likely non-directories (everything	885	currently) and likely non-directories (see C<aio_readdirx>). Then every
378	else). Then every entry plus an appended C</.> will be C<stat>'ed,	886	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
379	likely directories first. If that succeeds, it assumes that the entry	887	in order of their inode numbers. If that succeeds, it assumes that the
380	is a directory or a symlink to directory (which will be checked	888	entry is a directory or a symlink to directory (which will be checked
381	seperately). This is often faster than stat'ing the entry itself because	889	seperately). This is often faster than stat'ing the entry itself because
382	filesystems might detect the type of the entry without reading the inode	890	filesystems might detect the type of the entry without reading the inode
383	data (e.g. ext2fs filetype feature).	891	data (e.g. ext2fs filetype feature), even on systems that cannot return
		892	the filetype information on readdir.
384		893
385	If the known number of directories (link count - 2) has been reached, the	894	If the known number of directories (link count - 2) has been reached, the
386	rest of the entries is assumed to be non-directories.	895	rest of the entries is assumed to be non-directories.
387		896
388	This only works with certainty on POSIX (= UNIX) filesystems, which	897	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
392	as those tend to return 0 or 1 as link counts, which disables the	901	as those tend to return 0 or 1 as link counts, which disables the
393	directory counting heuristic.	902	directory counting heuristic.
394		903
395	=cut	904	=cut
396		905
397	sub aio_scandir($$$) {	906	sub aio_scandir($$;$) {
398	my ($path, $maxreq, $cb) = @_;	907	my ($path, $maxreq, $cb) = @_;
399		908
		909	my $pri = aioreq_pri;
		910
400	my $grp = aio_group;	911	my $grp = aio_group $cb;
401		912
402	$maxreq = 8 if $maxreq <= 0;	913	$maxreq = 4 if $maxreq <= 0;
403		914
404	# stat once	915	# stat once
		916	aioreq_pri $pri;
405	add $grp aio_stat $path, sub {	917	add $grp aio_stat $path, sub {
406	return $cb->() if $_[0];	918	return $grp->result () if $_[0];
407	my $now = time;	919	my $now = time;
408	my $hash1 = join ":", (stat _)[0,1,3,7,9];	920	my $hash1 = join ":", (stat _)[0,1,3,7,9];
409		921
410	# read the directory entries	922	# read the directory entries
		923	aioreq_pri $pri;
411	add $grp aio_readdir $path, sub {	924	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
412	my $entries = shift	925	my $entries = shift
413	or return $cb->();	926	or return $grp->result ();
414		927
415	# stat the dir another time	928	# stat the dir another time
		929	aioreq_pri $pri;
416	add $grp aio_stat $path, sub {	930	add $grp aio_stat $path, sub {
417	my $hash2 = join ":", (stat _)[0,1,3,7,9];	931	my $hash2 = join ":", (stat _)[0,1,3,7,9];
418		932
419	my $ndirs;	933	my $ndirs;
420		934
421	# take the slow route if anything looks fishy	935	# take the slow route if anything looks fishy
422	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	936	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
423	$ndirs = -1;	937	$ndirs = -1;
424	} else {	938	} else {
425	# if nlink == 2, we are finished	939	# if nlink == 2, we are finished
426	# on non-posix-fs's, we rely on nlink < 2	940	# for non-posix-fs's, we rely on nlink < 2
427	$ndirs = (stat _)[3] - 2	941	$ndirs = (stat _)[3] - 2
428	or return $cb->([], $entries);	942	or return $grp->result ([], $entries);
429	}	943	}
430		944
431	# sort into likely dirs and likely nondirs
432	# dirs == files without ".", short entries first
433	$entries = [map $_->[0],
434	sort { $b->[1] cmp $a->[1] }
435	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
436	@$entries];
437
438	my (@dirs, @nondirs);	945	my (@dirs, @nondirs);
439		946
440	my ($statcb, $schedcb);	947	my $statgrp = add $grp aio_group sub {
441	my $nreq = 0;	948	$grp->result (\@dirs, \@nondirs);
		949	};
442		950
443	$schedcb = sub {	951	limit $statgrp $maxreq;
444	if (@$entries) {	952	feed $statgrp sub {
445	if ($nreq < $maxreq) {	953	return unless @$entries;
446	my $ent = pop @$entries;	954	my $entry = shift @$entries;
		955
		956	aioreq_pri $pri;
		957	add $statgrp aio_stat "$path/$entry/.", sub {
		958	if ($_[0] < 0) {
		959	push @nondirs, $entry;
		960	} else {
		961	# need to check for real directory
		962	aioreq_pri $pri;
		963	add $statgrp aio_lstat "$path/$entry", sub {
		964	if (-d _) {
		965	push @dirs, $entry;
		966
		967	unless (--$ndirs) {
		968	push @nondirs, @$entries;
		969	feed $statgrp;
		970	}
		971	} else {
		972	push @nondirs, $entry;
		973	}
447	$nreq++;	974	}
448	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
449	}	975	}
450	} elsif (!$nreq) {
451	# finished
452	undef $statcb;
453	undef $schedcb;
454	$cb->(\@dirs, \@nondirs) if $cb;
455	undef $cb;
456	}	976	};
457	};	977	};
458	$statcb = sub {
459	my ($status, $entry) = @_;
460
461	if ($status < 0) {
462	$nreq--;
463	push @nondirs, $entry;
464	&$schedcb;
465	} else {
466	# need to check for real directory
467	add $grp aio_lstat "$path/$entry", sub {
468	$nreq--;
469
470	if (-d _) {
471	push @dirs, $entry;
472
473	if (!--$ndirs) {
474	push @nondirs, @$entries;
475	$entries = [];
476	}
477	} else {
478	push @nondirs, $entry;
479	}
480
481	&$schedcb;
482	}
483	}
484	};
485
486	&$schedcb while @$entries && $nreq < $maxreq;
487	};	978	};
488	};	979	};
489	};	980	};
490		981
491	$grp	982	$grp
492	}	983	}
493		984
		985	=item aio_rmtree $path, $callback->($status)
		986
		987	Delete a directory tree starting (and including) C<$path>, return the
		988	status of the final C<rmdir> only. This is a composite request that
		989	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		990	everything else.
		991
		992	=cut
		993
		994	sub aio_rmtree;
		995	sub aio_rmtree($;$) {
		996	my ($path, $cb) = @_;
		997
		998	my $pri = aioreq_pri;
		999	my $grp = aio_group $cb;
		1000
		1001	aioreq_pri $pri;
		1002	add $grp aio_scandir $path, 0, sub {
		1003	my ($dirs, $nondirs) = @_;
		1004
		1005	my $dirgrp = aio_group sub {
		1006	add $grp aio_rmdir $path, sub {
		1007	$grp->result ($_[0]);
		1008	};
		1009	};
		1010
		1011	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1012	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1013
		1014	add $grp $dirgrp;
		1015	};
		1016
		1017	$grp
		1018	}
		1019
		1020	=item aio_sync $callback->($status)
		1021
		1022	Asynchronously call sync and call the callback when finished.
		1023
494	=item aio_fsync $fh, $callback->($status)	1024	=item aio_fsync $fh, $callback->($status)
495		1025
496	Asynchronously call fsync on the given filehandle and call the callback	1026	Asynchronously call fsync on the given filehandle and call the callback
497	with the fsync result code.	1027	with the fsync result code.
498		1028
…		…
502	callback with the fdatasync result code.	1032	callback with the fdatasync result code.
503		1033
504	If this call isn't available because your OS lacks it or it couldn't be	1034	If this call isn't available because your OS lacks it or it couldn't be
505	detected, it will be emulated by calling C<fsync> instead.	1035	detected, it will be emulated by calling C<fsync> instead.
506		1036
		1037	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1038
		1039	Sync the data portion of the file specified by C<$offset> and C<$length>
		1040	to disk (but NOT the metadata), by calling the Linux-specific
		1041	sync_file_range call. If sync_file_range is not available or it returns
		1042	ENOSYS, then fdatasync or fsync is being substituted.
		1043
		1044	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1045	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1046	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1047	manpage for details.
		1048
		1049	=item aio_pathsync $path, $callback->($status)
		1050
		1051	This request tries to open, fsync and close the given path. This is a
		1052	composite request intended to sync directories after directory operations
		1053	(E.g. rename). This might not work on all operating systems or have any
		1054	specific effect, but usually it makes sure that directory changes get
		1055	written to disc. It works for anything that can be opened for read-only,
		1056	not just directories.
		1057
		1058	Future versions of this function might fall back to other methods when
		1059	C<fsync> on the directory fails (such as calling C<sync>).
		1060
		1061	Passes C<0> when everything went ok, and C<-1> on error.
		1062
		1063	=cut
		1064
		1065	sub aio_pathsync($;$) {
		1066	my ($path, $cb) = @_;
		1067
		1068	my $pri = aioreq_pri;
		1069	my $grp = aio_group $cb;
		1070
		1071	aioreq_pri $pri;
		1072	add $grp aio_open $path, O_RDONLY, 0, sub {
		1073	my ($fh) = @_;
		1074	if ($fh) {
		1075	aioreq_pri $pri;
		1076	add $grp aio_fsync $fh, sub {
		1077	$grp->result ($_[0]);
		1078
		1079	aioreq_pri $pri;
		1080	add $grp aio_close $fh;
		1081	};
		1082	} else {
		1083	$grp->result (-1);
		1084	}
		1085	};
		1086
		1087	$grp
		1088	}
		1089
		1090	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1091
		1092	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1093	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1094	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1095	scalar must only be modified in-place while an aio operation is pending on
		1096	it).
		1097
		1098	It calls the C<msync> function of your OS, if available, with the memory
		1099	area starting at C<$offset> in the string and ending C<$length> bytes
		1100	later. If C<$length> is negative, counts from the end, and if C<$length>
		1101	is C<undef>, then it goes till the end of the string. The flags can be
		1102	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1103	C<IO::AIO::MS_SYNC>.
		1104
		1105	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1106
		1107	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1108	scalars.
		1109
		1110	It touches (reads or writes) all memory pages in the specified
		1111	range inside the scalar. All caveats and parameters are the same
		1112	as for C<aio_msync>, above, except for flags, which must be either
		1113	C<0> (which reads all pages and ensures they are instantiated) or
		1114	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1115	writing an octet from it, which dirties the page).
		1116
		1117	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1118
		1119	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1120	scalars.
		1121
		1122	It reads in all the pages of the underlying storage into memory (if any)
		1123	and locks them, so they are not getting swapped/paged out or removed.
		1124
		1125	If C<$length> is undefined, then the scalar will be locked till the end.
		1126
		1127	On systems that do not implement C<mlock>, this function returns C<-1>
		1128	and sets errno to C<ENOSYS>.
		1129
		1130	Note that the corresponding C<munlock> is synchronous and is
		1131	documented under L<MISCELLANEOUS FUNCTIONS>.
		1132
		1133	Example: open a file, mmap and mlock it - both will be undone when
		1134	C<$data> gets destroyed.
		1135
		1136	open my $fh, "<", $path or die "$path: $!";
		1137	my $data;
		1138	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1139	aio_mlock $data; # mlock in background
		1140
		1141	=item aio_mlockall $flags, $callback->($status)
		1142
		1143	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1144	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1145
		1146	On systems that do not implement C<mlockall>, this function returns C<-1>
		1147	and sets errno to C<ENOSYS>.
		1148
		1149	Note that the corresponding C<munlockall> is synchronous and is
		1150	documented under L<MISCELLANEOUS FUNCTIONS>.
		1151
		1152	Example: asynchronously lock all current and future pages into memory.
		1153
		1154	aio_mlockall IO::AIO::MCL_FUTURE;
		1155
507	=item aio_group $callback->()	1156	=item aio_group $callback->(...)
508
509	[EXPERIMENTAL]
510		1157
511	This is a very special aio request: Instead of doing something, it is a	1158	This is a very special aio request: Instead of doing something, it is a
512	container for other aio requests, which is useful if you want to bundle	1159	container for other aio requests, which is useful if you want to bundle
513	many requests into a single, composite, request.	1160	many requests into a single, composite, request with a definite callback
		1161	and the ability to cancel the whole request with its subrequests.
514		1162
515	Returns an object of class L<IO::AIO::GRP>. See its documentation below	1163	Returns an object of class L<IO::AIO::GRP>. See its documentation below
516	for more info.	1164	for more info.
517		1165
518	Example:	1166	Example:
…		…
524	add $grp	1172	add $grp
525	(aio_stat ...),	1173	(aio_stat ...),
526	(aio_stat ...),	1174	(aio_stat ...),
527	...;	1175	...;
528		1176
		1177	=item aio_nop $callback->()
		1178
		1179	This is a special request - it does nothing in itself and is only used for
		1180	side effects, such as when you want to add a dummy request to a group so
		1181	that finishing the requests in the group depends on executing the given
		1182	code.
		1183
		1184	While this request does nothing, it still goes through the execution
		1185	phase and still requires a worker thread. Thus, the callback will not
		1186	be executed immediately but only after other requests in the queue have
		1187	entered their execution phase. This can be used to measure request
		1188	latency.
		1189
529	=item aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED*	1190	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
530		1191
531	Mainly used for debugging and benchmarking, this aio request puts one of	1192	Mainly used for debugging and benchmarking, this aio request puts one of
532	the request workers to sleep for the given time.	1193	the request workers to sleep for the given time.
533		1194
		1195	While it is theoretically handy to have simple I/O scheduling requests
		1196	like sleep and file handle readable/writable, the overhead this creates is
		1197	immense (it blocks a thread for a long time) so do not use this function
		1198	except to put your application under artificial I/O pressure.
		1199
534	=back	1200	=back
535		1201
536	=head2 IO::AIO::REQ CLASS	1202	=head2 IO::AIO::REQ CLASS
537		1203
538	All non-aggregate C<aio_*> functions return an object of this class when	1204	All non-aggregate C<aio_*> functions return an object of this class when
539	called in non-void context.	1205	called in non-void context.
540		1206
541	A request always moves through the following five states in its lifetime,
542	in order: B<ready> (request has been created, but has not been executed
543	yet), B<execute> (request is currently being executed), B<pending>
544	(request has been executed but callback has not been called yet),
545	B<result> (results are being processed synchronously, includes calling the
546	callback) and B<done> (request has reached the end of its lifetime and
547	holds no resources anymore).
548
549	=over 4	1207	=over 4
550		1208
551	=item $req->cancel	1209	=item cancel $req
552		1210
553	Cancels the request, if possible. Has the effect of skipping execution	1211	Cancels the request, if possible. Has the effect of skipping execution
554	when entering the B<execute> state and skipping calling the callback when	1212	when entering the B<execute> state and skipping calling the callback when
555	entering the the B<result> state, but will leave the request otherwise	1213	entering the the B<result> state, but will leave the request otherwise
556	untouched. That means that requests that currently execute will not be	1214	untouched (with the exception of readdir). That means that requests that
557	stopped and resources held by the request will not be freed prematurely.	1215	currently execute will not be stopped and resources held by the request
		1216	will not be freed prematurely.
		1217
		1218	=item cb $req $callback->(...)
		1219
		1220	Replace (or simply set) the callback registered to the request.
558		1221
559	=back	1222	=back
560		1223
561	=head2 IO::AIO::GRP CLASS	1224	=head2 IO::AIO::GRP CLASS
562		1225
…		…
577	You add requests by calling the C<add> method with one or more	1240	You add requests by calling the C<add> method with one or more
578	C<IO::AIO::REQ> objects:	1241	C<IO::AIO::REQ> objects:
579		1242
580	$grp->add (aio_unlink "...");	1243	$grp->add (aio_unlink "...");
581		1244
582	add $grp aio_stat "...", sub { ... };	1245	add $grp aio_stat "...", sub {
		1246	$_[0] or return $grp->result ("error");
		1247
		1248	# add another request dynamically, if first succeeded
		1249	add $grp aio_open "...", sub {
		1250	$grp->result ("ok");
		1251	};
		1252	};
583		1253
584	This makes it very easy to create composite requests (see the source of	1254	This makes it very easy to create composite requests (see the source of
585	C<aio_move> for an application) that work and feel like simple requests.	1255	C<aio_move> for an application) that work and feel like simple requests.
586		1256
		1257	=over 4
		1258
587	The IO::AIO::GRP objects will be cleaned up during calls to	1259	=item * The IO::AIO::GRP objects will be cleaned up during calls to
588	C<IO::AIO::poll_cb>, just like any other request.	1260	C<IO::AIO::poll_cb>, just like any other request.
589		1261
590	They can be canceled like any other request. Canceling will cancel not	1262	=item * They can be canceled like any other request. Canceling will cancel not
591	just the request itself, but also all requests it contains.	1263	only the request itself, but also all requests it contains.
592		1264
593	They can also can also be added to other IO::AIO::GRP objects.	1265	=item * They can also can also be added to other IO::AIO::GRP objects.
		1266
		1267	=item * You must not add requests to a group from within the group callback (or
		1268	any later time).
		1269
		1270	=back
594		1271
595	Their lifetime, simplified, looks like this: when they are empty, they	1272	Their lifetime, simplified, looks like this: when they are empty, they
596	will finish very quickly. If they contain only requests that are in the	1273	will finish very quickly. If they contain only requests that are in the
597	C<done> state, they will also finish. Otherwise they will continue to	1274	C<done> state, they will also finish. Otherwise they will continue to
598	exist.	1275	exist.
599		1276
		1277	That means after creating a group you have some time to add requests
		1278	(precisely before the callback has been invoked, which is only done within
		1279	the C<poll_cb>). And in the callbacks of those requests, you can add
		1280	further requests to the group. And only when all those requests have
		1281	finished will the the group itself finish.
		1282
600	=over 4	1283	=over 4
601		1284
		1285	=item add $grp ...
		1286
602	=item $grp->add (...)	1287	=item $grp->add (...)
603		1288
604	=item add $grp ...	1289	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		1290	be added, including other groups, as long as you do not create circular
		1291	dependencies.
605		1292
606	Add one or more	1293	Returns all its arguments.
607	Cancels the request, if possible. Has the effect of skipping execution	1294
608	when entering the B<execute> state and skipping calling the callback when	1295	=item $grp->cancel_subs
609	entering the the B<result> state, but will leave the request otherwise	1296
610	untouched. That means that requests that currently execute will not be	1297	Cancel all subrequests and clears any feeder, but not the group request
611	stopped and resources held by the request will not be freed prematurely.	1298	itself. Useful when you queued a lot of events but got a result early.
		1299
		1300	The group request will finish normally (you cannot add requests to the
		1301	group).
		1302
		1303	=item $grp->result (...)
		1304
		1305	Set the result value(s) that will be passed to the group callback when all
		1306	subrequests have finished and set the groups errno to the current value
		1307	of errno (just like calling C<errno> without an error number). By default,
		1308	no argument will be passed and errno is zero.
		1309
		1310	=item $grp->errno ([$errno])
		1311
		1312	Sets the group errno value to C<$errno>, or the current value of errno
		1313	when the argument is missing.
		1314
		1315	Every aio request has an associated errno value that is restored when
		1316	the callback is invoked. This method lets you change this value from its
		1317	default (0).
		1318
		1319	Calling C<result> will also set errno, so make sure you either set C<$!>
		1320	before the call to C<result>, or call c<errno> after it.
		1321
		1322	=item feed $grp $callback->($grp)
		1323
		1324	Sets a feeder/generator on this group: every group can have an attached
		1325	generator that generates requests if idle. The idea behind this is that,
		1326	although you could just queue as many requests as you want in a group,
		1327	this might starve other requests for a potentially long time. For example,
		1328	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
		1329	delaying any later requests for a long time.
		1330
		1331	To avoid this, and allow incremental generation of requests, you can
		1332	instead a group and set a feeder on it that generates those requests. The
		1333	feed callback will be called whenever there are few enough (see C<limit>,
		1334	below) requests active in the group itself and is expected to queue more
		1335	requests.
		1336
		1337	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1338	not impose any limits).
		1339
		1340	If the feed does not queue more requests when called, it will be
		1341	automatically removed from the group.
		1342
		1343	If the feed limit is C<0> when this method is called, it will be set to
		1344	C<2> automatically.
		1345
		1346	Example:
		1347
		1348	# stat all files in @files, but only ever use four aio requests concurrently:
		1349
		1350	my $grp = aio_group sub { print "finished\n" };
		1351	limit $grp 4;
		1352	feed $grp sub {
		1353	my $file = pop @files
		1354	or return;
		1355
		1356	add $grp aio_stat $file, sub { ... };
		1357	};
		1358
		1359	=item limit $grp $num
		1360
		1361	Sets the feeder limit for the group: The feeder will be called whenever
		1362	the group contains less than this many requests.
		1363
		1364	Setting the limit to C<0> will pause the feeding process.
		1365
		1366	The default value for the limit is C<0>, but note that setting a feeder
		1367	automatically bumps it up to C<2>.
612		1368
613	=back	1369	=back
614		1370
615	=head2 SUPPORT FUNCTIONS	1371	=head2 SUPPORT FUNCTIONS
616		1372
		1373	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1374
617	=over 4	1375	=over 4
618		1376
619	=item $fileno = IO::AIO::poll_fileno	1377	=item $fileno = IO::AIO::poll_fileno
620		1378
621	Return the I<request result pipe file descriptor>. This filehandle must be	1379	Return the I<request result pipe file descriptor>. This filehandle must be
622	polled for reading by some mechanism outside this module (e.g. Event or	1380	polled for reading by some mechanism outside this module (e.g. EV, Glib,
623	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1381	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
624	to call C<poll_cb> to check the results.	1382	you have to call C<poll_cb> to check the results.
625		1383
626	See C<poll_cb> for an example.	1384	See C<poll_cb> for an example.
627		1385
628	=item IO::AIO::poll_cb	1386	=item IO::AIO::poll_cb
629		1387
630	Process all outstanding events on the result pipe. You have to call this	1388	Process some outstanding events on the result pipe. You have to call this
631	regularly. Returns the number of events processed. Returns immediately	1389	regularly. Returns C<0> if all events could be processed, or C<-1> if it
632	when no events are outstanding.	1390	returned earlier for whatever reason. Returns immediately when no events
		1391	are outstanding. The amount of events processed depends on the settings of
		1392	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1393
		1394	If not all requests were processed for whatever reason, the filehandle
		1395	will still be ready when C<poll_cb> returns, so normally you don't have to
		1396	do anything special to have it called later.
633		1397
634	Example: Install an Event watcher that automatically calls	1398	Example: Install an Event watcher that automatically calls
635	IO::AIO::poll_cb with high priority:	1399	IO::AIO::poll_cb with high priority (more examples can be found in the
		1400	SYNOPSIS section, at the top of this document):
636		1401
637	Event->io (fd => IO::AIO::poll_fileno,	1402	Event->io (fd => IO::AIO::poll_fileno,
638	poll => 'r', async => 1,	1403	poll => 'r', async => 1,
639	cb => \&IO::AIO::poll_cb);	1404	cb => \&IO::AIO::poll_cb);
640		1405
641	=item IO::AIO::poll_wait	1406	=item IO::AIO::poll_wait
642		1407
		1408	If there are any outstanding requests and none of them in the result
643	Wait till the result filehandle becomes ready for reading (simply does a	1409	phase, wait till the result filehandle becomes ready for reading (simply
644	C<select> on the filehandle. This is useful if you want to synchronously wait	1410	does a C<select> on the filehandle. This is useful if you want to
645	for some requests to finish).	1411	synchronously wait for some requests to finish).
646		1412
647	See C<nreqs> for an example.	1413	See C<nreqs> for an example.
648		1414
		1415	=item IO::AIO::poll
		1416
		1417	Waits until some requests have been handled.
		1418
		1419	Returns the number of requests processed, but is otherwise strictly
		1420	equivalent to:
		1421
		1422	IO::AIO::poll_wait, IO::AIO::poll_cb
		1423
649	=item IO::AIO::nreqs	1424	=item IO::AIO::flush
650		1425
651	Returns the number of requests currently outstanding (i.e. for which their	1426	Wait till all outstanding AIO requests have been handled.
652	callback has not been invoked yet).
653		1427
654	Example: wait till there are no outstanding requests anymore:	1428	Strictly equivalent to:
655		1429
656	IO::AIO::poll_wait, IO::AIO::poll_cb	1430	IO::AIO::poll_wait, IO::AIO::poll_cb
657	while IO::AIO::nreqs;	1431	while IO::AIO::nreqs;
658		1432
659	=item IO::AIO::flush	1433	=item IO::AIO::max_poll_reqs $nreqs
660		1434
661	Wait till all outstanding AIO requests have been handled.	1435	=item IO::AIO::max_poll_time $seconds
662		1436
663	Strictly equivalent to:	1437	These set the maximum number of requests (default C<0>, meaning infinity)
		1438	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1439	the maximum amount of time (default C<0>, meaning infinity) spent in
		1440	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1441	of time C<poll_cb> is allowed to use).
664		1442
665	IO::AIO::poll_wait, IO::AIO::poll_cb	1443	Setting C<max_poll_time> to a non-zero value creates an overhead of one
666	while IO::AIO::nreqs;	1444	syscall per request processed, which is not normally a problem unless your
		1445	callbacks are really really fast or your OS is really really slow (I am
		1446	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
667		1447
668	=item IO::AIO::poll	1448	Setting these is useful if you want to ensure some level of
		1449	interactiveness when perl is not fast enough to process all requests in
		1450	time.
669		1451
670	Waits until some requests have been handled.	1452	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
671		1453
672	Strictly equivalent to:	1454	Example: Install an Event watcher that automatically calls
		1455	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1456	program get the CPU sometimes even under high AIO load.
673		1457
674	IO::AIO::poll_wait, IO::AIO::poll_cb	1458	# try not to spend much more than 0.1s in poll_cb
675	if IO::AIO::nreqs;	1459	IO::AIO::max_poll_time 0.1;
		1460
		1461	# use a low priority so other tasks have priority
		1462	Event->io (fd => IO::AIO::poll_fileno,
		1463	poll => 'r', nice => 1,
		1464	cb => &IO::AIO::poll_cb);
		1465
		1466	=back
		1467
		1468	=head3 CONTROLLING THE NUMBER OF THREADS
		1469
		1470	=over
676		1471
677	=item IO::AIO::min_parallel $nthreads	1472	=item IO::AIO::min_parallel $nthreads
678		1473
679	Set the minimum number of AIO threads to C<$nthreads>. The current default	1474	Set the minimum number of AIO threads to C<$nthreads>. The current
680	is C<4>, which means four asynchronous operations can be done at one time	1475	default is C<8>, which means eight asynchronous operations can execute
681	(the number of outstanding operations, however, is unlimited).	1476	concurrently at any one time (the number of outstanding requests,
		1477	however, is unlimited).
682		1478
683	IO::AIO starts threads only on demand, when an AIO request is queued and	1479	IO::AIO starts threads only on demand, when an AIO request is queued and
684	no free thread exists.	1480	no free thread exists. Please note that queueing up a hundred requests can
		1481	create demand for a hundred threads, even if it turns out that everything
		1482	is in the cache and could have been processed faster by a single thread.
685		1483
686	It is recommended to keep the number of threads low, as some Linux	1484	It is recommended to keep the number of threads relatively low, as some
687	kernel versions will scale negatively with the number of threads (higher	1485	Linux kernel versions will scale negatively with the number of threads
688	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1486	(higher parallelity => MUCH higher latency). With current Linux 2.6
689	threads should be fine.	1487	versions, 4-32 threads should be fine.
690		1488
691	Under most circumstances you don't need to call this function, as the	1489	Under most circumstances you don't need to call this function, as the
692	module selects a default that is suitable for low to moderate load.	1490	module selects a default that is suitable for low to moderate load.
693		1491
694	=item IO::AIO::max_parallel $nthreads	1492	=item IO::AIO::max_parallel $nthreads
…		…
703	This module automatically runs C<max_parallel 0> at program end, to ensure	1501	This module automatically runs C<max_parallel 0> at program end, to ensure
704	that all threads are killed and that there are no outstanding requests.	1502	that all threads are killed and that there are no outstanding requests.
705		1503
706	Under normal circumstances you don't need to call this function.	1504	Under normal circumstances you don't need to call this function.
707		1505
		1506	=item IO::AIO::max_idle $nthreads
		1507
		1508	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1509	threads that did not get a request to process within 10 seconds). That
		1510	means if a thread becomes idle while C<$nthreads> other threads are also
		1511	idle, it will free its resources and exit.
		1512
		1513	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1514	to allow for extremely high load situations, but want to free resources
		1515	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1516
		1517	The default is probably ok in most situations, especially if thread
		1518	creation is fast. If thread creation is very slow on your system you might
		1519	want to use larger values.
		1520
708	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1521	=item IO::AIO::max_outstanding $maxreqs
		1522
		1523	This is a very bad function to use in interactive programs because it
		1524	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1525	use an C<aio_group> together with a feed callback.
709		1526
710	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1527	Sets the maximum number of outstanding requests to C<$nreqs>. If you
711	try to queue up more than this number of requests, the caller will block until	1528	do queue up more than this number of requests, the next call to the
712	some requests have been handled.	1529	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1530	function will block until the limit is no longer exceeded.
713		1531
714	The default is very large, so normally there is no practical limit. If you	1532	The default value is very large, so there is no practical limit on the
715	queue up many requests in a loop it often improves speed if you set	1533	number of outstanding requests.
716	this to a relatively low number, such as C<100>.
717		1534
718	Under normal circumstances you don't need to call this function.	1535	You can still queue as many requests as you want. Therefore,
		1536	C<max_outstanding> is mainly useful in simple scripts (with low values) or
		1537	as a stop gap to shield against fatal memory overflow (with large values).
719		1538
720	=back	1539	=back
721		1540
		1541	=head3 STATISTICAL INFORMATION
		1542
		1543	=over
		1544
		1545	=item IO::AIO::nreqs
		1546
		1547	Returns the number of requests currently in the ready, execute or pending
		1548	states (i.e. for which their callback has not been invoked yet).
		1549
		1550	Example: wait till there are no outstanding requests anymore:
		1551
		1552	IO::AIO::poll_wait, IO::AIO::poll_cb
		1553	while IO::AIO::nreqs;
		1554
		1555	=item IO::AIO::nready
		1556
		1557	Returns the number of requests currently in the ready state (not yet
		1558	executed).
		1559
		1560	=item IO::AIO::npending
		1561
		1562	Returns the number of requests currently in the pending state (executed,
		1563	but not yet processed by poll_cb).
		1564
		1565	=back
		1566
		1567	=head3 MISCELLANEOUS FUNCTIONS
		1568
		1569	IO::AIO implements some functions that might be useful, but are not
		1570	asynchronous.
		1571
		1572	=over 4
		1573
		1574	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1575
		1576	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1577	but is blocking (this makes most sense if you know the input data is
		1578	likely cached already and the output filehandle is set to non-blocking
		1579	operations).
		1580
		1581	Returns the number of bytes copied, or C<-1> on error.
		1582
		1583	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1584
		1585	Simply calls the C<posix_fadvise> function (see it's
		1586	manpage for details). The following advice constants are
		1587	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1588	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1589	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1590
		1591	On systems that do not implement C<posix_fadvise>, this function returns
		1592	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1593
		1594	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1595
		1596	Memory-maps a file (or anonymous memory range) and attaches it to the
		1597	given C<$scalar>, which will act like a string scalar.
		1598
		1599	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1600	change the string length, and most read-only operations such as copying it
		1601	or searching it with regexes and so on.
		1602
		1603	Anything else is unsafe and will, at best, result in memory leaks.
		1604
		1605	The memory map associated with the C<$scalar> is automatically removed
		1606	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1607	C<IO::AIO::munmap> functions are called.
		1608
		1609	This calls the C<mmap>(2) function internally. See your system's manual
		1610	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1611
		1612	The C<$length> must be larger than zero and smaller than the actual
		1613	filesize.
		1614
		1615	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1616	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1617
		1618	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1619	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1620	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1621	(which is set to C<MAP_ANON> if your system only provides this
		1622	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1623	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1624	C<IO::AIO::MAP_NONBLOCK>
		1625
		1626	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1627
		1628	C<$offset> is the offset from the start of the file - it generally must be
		1629	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1630
		1631	Example:
		1632
		1633	use Digest::MD5;
		1634	use IO::AIO;
		1635
		1636	open my $fh, "<verybigfile"
		1637	or die "$!";
		1638
		1639	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1640	or die "verybigfile: $!";
		1641
		1642	my $fast_md5 = md5 $data;
		1643
		1644	=item IO::AIO::munmap $scalar
		1645
		1646	Removes a previous mmap and undefines the C<$scalar>.
		1647
		1648	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1649
		1650	Calls the C<munlock> function, undoing the effects of a previous
		1651	C<aio_mlock> call (see its description for details).
		1652
		1653	=item IO::AIO::munlockall
		1654
		1655	Calls the C<munlockall> function.
		1656
		1657	On systems that do not implement C<munlockall>, this function returns
		1658	ENOSYS, otherwise the return value of C<munlockall>.
		1659
		1660	=back
		1661
722	=cut	1662	=cut
723		1663
724	# support function to convert a fd into a perl filehandle
725	sub _fd2fh {
726	return undef if $_[0] < 0;
727
728	# try to generate nice filehandles
729	my $sym = "IO::AIO::fd#$_[0]";
730	local *$sym;
731
732	open *$sym, "+<&=$_[0]" # usually works under any unix
733	or open *$sym, "<&=$_[0]" # cygwin needs this
734	or open *$sym, ">&=$_[0]" # or this
735	or return undef;
736
737	*$sym
738	}
739
740	min_parallel 4;	1664	min_parallel 8;
741		1665
742	END {	1666	END { flush }
743	max_parallel 0;
744	}
745		1667
746	1;	1668	1;
		1669
		1670	=head1 EVENT LOOP INTEGRATION
		1671
		1672	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1673	automatically into many event loops:
		1674
		1675	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1676	use AnyEvent::AIO;
		1677
		1678	You can also integrate IO::AIO manually into many event loops, here are
		1679	some examples of how to do this:
		1680
		1681	# EV integration
		1682	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1683
		1684	# Event integration
		1685	Event->io (fd => IO::AIO::poll_fileno,
		1686	poll => 'r',
		1687	cb => \&IO::AIO::poll_cb);
		1688
		1689	# Glib/Gtk2 integration
		1690	add_watch Glib::IO IO::AIO::poll_fileno,
		1691	in => sub { IO::AIO::poll_cb; 1 };
		1692
		1693	# Tk integration
		1694	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1695	readable => \&IO::AIO::poll_cb);
		1696
		1697	# Danga::Socket integration
		1698	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1699	\&IO::AIO::poll_cb);
747		1700
748	=head2 FORK BEHAVIOUR	1701	=head2 FORK BEHAVIOUR
749		1702
750	This module should do "the right thing" when the process using it forks:	1703	This module should do "the right thing" when the process using it forks:
751		1704
752	Before the fork, IO::AIO enters a quiescent state where no requests	1705	Before the fork, IO::AIO enters a quiescent state where no requests
753	can be added in other threads and no results will be processed. After	1706	can be added in other threads and no results will be processed. After
754	the fork the parent simply leaves the quiescent state and continues	1707	the fork the parent simply leaves the quiescent state and continues
755	request/result processing, while the child clears the request/result	1708	request/result processing, while the child frees the request/result queue
756	queue (so the requests started before the fork will only be handled in	1709	(so that the requests started before the fork will only be handled in the
757	the parent). Threads will be started on demand until the limit ste in the	1710	parent). Threads will be started on demand until the limit set in the
758	parent process has been reached again.	1711	parent process has been reached again.
759		1712
760	In short: the parent will, after a short pause, continue as if fork had	1713	In short: the parent will, after a short pause, continue as if fork had
761	not been called, while the child will act as if IO::AIO has not been used	1714	not been called, while the child will act as if IO::AIO has not been used
762	yet.	1715	yet.
763		1716
		1717	=head2 MEMORY USAGE
		1718
		1719	Per-request usage:
		1720
		1721	Each aio request uses - depending on your architecture - around 100-200
		1722	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1723	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1724	scalars and other data passed into aio requests will also be locked and
		1725	will consume memory till the request has entered the done state.
		1726
		1727	This is not awfully much, so queuing lots of requests is not usually a
		1728	problem.
		1729
		1730	Per-thread usage:
		1731
		1732	In the execution phase, some aio requests require more memory for
		1733	temporary buffers, and each thread requires a stack and other data
		1734	structures (usually around 16k-128k, depending on the OS).
		1735
		1736	=head1 KNOWN BUGS
		1737
		1738	Known bugs will be fixed in the next release.
		1739
764	=head1 SEE ALSO	1740	=head1 SEE ALSO
765		1741
766	L<Coro>, L<Linux::AIO> (obsolete).	1742	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1743	more natural syntax.
767		1744
768	=head1 AUTHOR	1745	=head1 AUTHOR
769		1746
770	Marc Lehmann <schmorp@schmorp.de>	1747	Marc Lehmann <schmorp@schmorp.de>
771	http://home.schmorp.de/	1748	http://home.schmorp.de/

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