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Revision 1.57 by root, Sun Oct 22 01:28:31 2006 UTC vs.
Revision 1.188 by root, Tue Feb 15 03:21:41 2011 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
…		…
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 ...;
28		30
29	# AnyEvent integration
30	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
31	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
32
33	# Event integration
34	Event->io (fd => IO::AIO::poll_fileno,
35	poll => 'r',
36	cb => \&IO::AIO::poll_cb);
37
38	# Glib/Gtk2 integration
39	add_watch Glib::IO IO::AIO::poll_fileno,
40	in => sub { IO::AIO::poll_cb; 1 };
41
42	# Tk integration
43	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
44	readable => \&IO::AIO::poll_cb);
45
46	# Danga::Socket integration
47	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
48	\&IO::AIO::poll_cb);
49
50	=head1 DESCRIPTION	31	=head1 DESCRIPTION
51		32
52	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
53	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>).
54		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
55	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
56	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
57	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
58	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
59	aio functions available on many operating systems. However, they are often	57	functions available on many operating systems. However, they are often
60	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
61	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
62	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.
63		62
64	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,
65	currently not reentrant, so use appropriate locking yourself, always call	64	it is currently not reentrant in any way, so use appropriate locking
66	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
67	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
68		161
69	=cut	162	=cut
70		163
71	package IO::AIO;	164	package IO::AIO;
72		165
73	no warnings;	166	use Carp ();
74	use strict 'vars';	167
		168	use common::sense;
75		169
76	use base 'Exporter';	170	use base 'Exporter';
77		171
78	BEGIN {	172	BEGIN {
79	our $VERSION = '2.0';	173	our $VERSION = '3.72';
80		174
81	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
82	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
83	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
84	aio_group);	183	aio_statvfs);
85	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 idle_timeout
		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
86		194
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		196
89	require XSLoader;	197	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
91	}	199	}
92		200
93	=head1 FUNCTIONS	201	=head1 FUNCTIONS
94		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::idle_timeout $seconds
		264	IO::AIO::max_outstanding $maxreqs
		265	IO::AIO::nreqs
		266	IO::AIO::nready
		267	IO::AIO::npending
		268
		269	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		270	IO::AIO::fadvise $fh, $offset, $len, $advice
		271	IO::AIO::madvise $scalar, $offset, $length, $advice
		272	IO::AIO::mprotect $scalar, $offset, $length, $protect
		273	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		274	IO::AIO::munlockall
		275
95	=head2 AIO FUNCTIONS	276	=head2 AIO REQUEST FUNCTIONS
96		277
97	All the C<aio_*> calls are more or less thin wrappers around the syscall	278	All the C<aio_*> calls are more or less thin wrappers around the syscall
98	with the same name (sans C<aio_>). The arguments are similar or identical,	279	with the same name (sans C<aio_>). The arguments are similar or identical,
99	and they all accept an additional (and optional) C<$callback> argument	280	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	281	which must be a code reference. This code reference will get called with
101	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	282	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
102	perl, which usually delivers "false") as it's sole argument when the given	283	perl, which usually delivers "false") as its sole argument after the given
103	syscall has been executed asynchronously.	284	syscall has been executed asynchronously.
104		285
105	All functions expecting a filehandle keep a copy of the filehandle	286	All functions expecting a filehandle keep a copy of the filehandle
106	internally until the request has finished.	287	internally until the request has finished.
107		288
108	All requests return objects of type L<IO::AIO::REQ> that allow further	289	All functions return request objects of type L<IO::AIO::REQ> that allow
109	manipulation of those requests while they are in-flight.	290	further manipulation of those requests while they are in-flight.
110		291
111	The pathnames you pass to these routines I<must> be absolute and	292	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	293	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	294	request is being executed, the current working directory could have
114	changed. Alternatively, you can make sure that you never change the	295	changed. Alternatively, you can make sure that you never change the
115	current working directory.	296	current working directory anywhere in the program and then use relative
		297	paths.
116		298
117	To encode pathnames to byte form, either make sure you either: a)	299	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	300	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	301	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	302	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)	303	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
122	use something else.	304	use something else to ensure your scalar has the correct contents.
		305
		306	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		307	handles correctly whether it is set or not.
123		308
124	=over 4	309	=over 4
		310
		311	=item $prev_pri = aioreq_pri [$pri]
		312
		313	Returns the priority value that would be used for the next request and, if
		314	C<$pri> is given, sets the priority for the next aio request.
		315
		316	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		317	and C<4>, respectively. Requests with higher priority will be serviced
		318	first.
		319
		320	The priority will be reset to C<0> after each call to one of the C<aio_*>
		321	functions.
		322
		323	Example: open a file with low priority, then read something from it with
		324	higher priority so the read request is serviced before other low priority
		325	open requests (potentially spamming the cache):
		326
		327	aioreq_pri -3;
		328	aio_open ..., sub {
		329	return unless $_[0];
		330
		331	aioreq_pri -2;
		332	aio_read $_[0], ..., sub {
		333	...
		334	};
		335	};
		336
		337
		338	=item aioreq_nice $pri_adjust
		339
		340	Similar to C<aioreq_pri>, but subtracts the given value from the current
		341	priority, so the effect is cumulative.
		342
125		343
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	344	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		345
128	Asynchronously open or create a file and call the callback with a newly	346	Asynchronously open or create a file and call the callback with a newly
129	created filehandle for the file.	347	created filehandle for the file.
…		…
135	list. They are the same as used by C<sysopen>.	353	list. They are the same as used by C<sysopen>.
136		354
137	Likewise, C<$mode> specifies the mode of the newly created file, if it	355	Likewise, C<$mode> specifies the mode of the newly created file, if it
138	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	356	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
139	except that it is mandatory (i.e. use C<0> if you don't create new files,	357	except that it is mandatory (i.e. use C<0> if you don't create new files,
140	and C<0666> or C<0777> if you do).	358	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		359	by the umask in effect then the request is being executed, so better never
		360	change the umask.
141		361
142	Example:	362	Example:
143		363
144	aio_open "/etc/passwd", O_RDONLY, 0, sub {	364	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
145	if ($_[0]) {	365	if ($_[0]) {
146	print "open successful, fh is $_[0]\n";	366	print "open successful, fh is $_[0]\n";
147	...	367	...
148	} else {	368	} else {
149	die "open failed: $!\n";	369	die "open failed: $!\n";
150	}	370	}
151	};	371	};
152		372
		373
153	=item aio_close $fh, $callback->($status)	374	=item aio_close $fh, $callback->($status)
154		375
155	Asynchronously close a file and call the callback with the result	376	Asynchronously close a file and call the callback with the result
156	code. I<WARNING:> although accepted, you should not pass in a perl	377	code.
157	filehandle here, as perl will likely close the file descriptor another
158	time when the filehandle is destroyed. Normally, you can safely call perls
159	C<close> or just let filehandles go out of scope.
160		378
161	This is supposed to be a bug in the API, so that might change. It's	379	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
162	therefore best to avoid this function.	380	closing the file descriptor associated with the filehandle itself.
		381
		382	Therefore, C<aio_close> will not close the filehandle - instead it will
		383	use dup2 to overwrite the file descriptor with the write-end of a pipe
		384	(the pipe fd will be created on demand and will be cached).
		385
		386	Or in other words: the file descriptor will be closed, but it will not be
		387	free for reuse until the perl filehandle is closed.
		388
		389	=cut
163		390
164	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	391	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
165		392
166	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	393	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
167		394
168	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	395	Reads or writes C<$length> bytes from or to the specified C<$fh> and
169	into the scalar given by C<data> and offset C<dataoffset> and calls the	396	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
170	callback without the actual number of bytes read (or -1 on error, just	397	and calls the callback without the actual number of bytes read (or -1 on
171	like the syscall).	398	error, just like the syscall).
		399
		400	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		401	offset plus the actual number of bytes read.
		402
		403	If C<$offset> is undefined, then the current file descriptor offset will
		404	be used (and updated), otherwise the file descriptor offset will not be
		405	changed by these calls.
		406
		407	If C<$length> is undefined in C<aio_write>, use the remaining length of
		408	C<$data>.
		409
		410	If C<$dataoffset> is less than zero, it will be counted from the end of
		411	C<$data>.
172		412
173	The C<$data> scalar I<MUST NOT> be modified in any way while the request	413	The C<$data> scalar I<MUST NOT> be modified in any way while the request
174	is outstanding. Modifying it can result in segfaults or WW3 (if the	414	is outstanding. Modifying it can result in segfaults or World War III (if
175	necessary/optional hardware is installed).	415	the necessary/optional hardware is installed).
176		416
177	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	417	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
178	offset C<0> within the scalar:	418	offset C<0> within the scalar:
179		419
180	aio_read $fh, 7, 15, $buffer, 0, sub {	420	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	421	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	422	print "read $_[0] bytes: <$buffer>\n";
183	};	423	};
184		424
185	=item aio_move $srcpath, $dstpath, $callback->($status)
186
187	Try to move the I<file> (directories not supported as either source or
188	destination) from C<$srcpath> to C<$dstpath> and call the callback with
189	the C<0> (error) or C<-1> ok.
190
191	This is a composite request that tries to rename(2) the file first. If
192	rename files with C<EXDEV>, it creates the destination file with mode 0200
193	and copies the contents of the source file into it using C<aio_sendfile>,
194	followed by restoring atime, mtime, access mode and uid/gid, in that
195	order, and unlinking the C<$srcpath>.
196
197	If an error occurs, the partial destination file will be unlinked, if
198	possible, except when setting atime, mtime, access mode and uid/gid, where
199	errors are being ignored.
200
201	=cut
202
203	sub aio_move($$$) {
204	my ($src, $dst, $cb) = @_;
205
206	my $grp = aio_group;
207
208	add $grp aio_rename $src, $dst, sub {
209	if ($_[0] && $! == EXDEV) {
210	add $grp aio_open $src, O_RDONLY, 0, sub {
211	if (my $src_fh = $_[0]) {
212	my @stat = stat $src_fh;
213
214	add $grp aio_open $dst, O_WRONLY, 0200, sub {
215	if (my $dst_fh = $_[0]) {
216	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
217	close $src_fh;
218
219	if ($_[0] == $stat[7]) {
220	utime $stat[8], $stat[9], $dst;
221	chmod $stat[2] & 07777, $dst_fh;
222	chown $stat[4], $stat[5], $dst_fh;
223	close $dst_fh;
224
225	add $grp aio_unlink $src, sub {
226	$cb->($_[0]);
227	};
228	} else {
229	my $errno = $!;
230	add $grp aio_unlink $dst, sub {
231	$! = $errno;
232	$cb->(-1);
233	};
234	}
235	};
236	} else {
237	$cb->(-1);
238	}
239	},
240
241	} else {
242	$cb->(-1);
243	}
244	};
245	} else {
246	$cb->($_[0]);
247	}
248	};
249
250	$grp
251	}
252		425
253	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	426	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
254		427
255	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	428	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
256	reading at byte offset C<$in_offset>, and starts writing at the current	429	reading at byte offset C<$in_offset>, and starts writing at the current
257	file offset of C<$out_fh>. Because of that, it is not safe to issue more	430	file offset of C<$out_fh>. Because of that, it is not safe to issue more
258	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	431	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
259	other.	432	other.
260		433
		434	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		435	are written, and there is no way to find out how many bytes have been read
		436	from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of
		437	bytes written to C<$out_fh>. Only if the result value equals C<$length>
		438	one can assume that C<$length> bytes have been read.
		439
		440	Unlike with other C<aio_> functions, it makes a lot of sense to use
		441	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		442	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		443	the socket I/O will be non-blocking. Note, however, that you can run into
		444	a trap where C<aio_sendfile> reads some data with readahead, then fails
		445	to write all data, and when the socket is ready the next time, the data
		446	in the cache is already lost, forcing C<aio_sendfile> to again hit the
		447	disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage
		448	much better.
		449
261	This call tries to make use of a native C<sendfile> syscall to provide	450	This call tries to make use of a native C<sendfile> syscall to provide
262	zero-copy operation. For this to work, C<$out_fh> should refer to a	451	zero-copy operation. For this to work, C<$out_fh> should refer to a
263	socket, and C<$in_fh> should refer to mmap'able file.	452	socket, and C<$in_fh> should refer to an mmap'able file.
264		453
265	If the native sendfile call fails or is not implemented, it will be	454	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		455	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
266	emulated, so you can call C<aio_sendfile> on any type of filehandle	456	it will be emulated, so you can call C<aio_sendfile> on any type of
267	regardless of the limitations of the operating system.	457	filehandle regardless of the limitations of the operating system.
268		458
269	Please note, however, that C<aio_sendfile> can read more bytes from
270	C<$in_fh> than are written, and there is no way to find out how many
271	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
272	provides the number of bytes written to C<$out_fh>. Only if the result
273	value equals C<$length> one can assume that C<$length> bytes have been
274	read.
275		459
276	=item aio_readahead $fh,$offset,$length, $callback->($retval)	460	=item aio_readahead $fh,$offset,$length, $callback->($retval)
277		461
278	C<aio_readahead> populates the page cache with data from a file so that	462	C<aio_readahead> populates the page cache with data from a file so that
279	subsequent reads from that file will not block on disk I/O. The C<$offset>	463	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
285	file. The current file offset of the file is left unchanged.	469	file. The current file offset of the file is left unchanged.
286		470
287	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	471	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
288	emulated by simply reading the data, which would have a similar effect.	472	emulated by simply reading the data, which would have a similar effect.
289		473
		474
290	=item aio_stat $fh_or_path, $callback->($status)	475	=item aio_stat $fh_or_path, $callback->($status)
291		476
292	=item aio_lstat $fh, $callback->($status)	477	=item aio_lstat $fh, $callback->($status)
293		478
294	Works like perl's C<stat> or C<lstat> in void context. The callback will	479	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
299	for an explanation.	484	for an explanation.
300		485
301	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	486	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
302	error when stat'ing a large file, the results will be silently truncated	487	error when stat'ing a large file, the results will be silently truncated
303	unless perl itself is compiled with large file support.	488	unless perl itself is compiled with large file support.
		489
		490	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		491	following constants and functions (if not implemented, the constants will
		492	be C<0> and the functions will either C<croak> or fall back on traditional
		493	behaviour).
		494
		495	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		496	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		497	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
304		498
305	Example: Print the length of F</etc/passwd>:	499	Example: Print the length of F</etc/passwd>:
306		500
307	aio_stat "/etc/passwd", sub {	501	aio_stat "/etc/passwd", sub {
308	$_[0] and die "stat failed: $!";	502	$_[0] and die "stat failed: $!";
309	print "size is ", -s _, "\n";	503	print "size is ", -s _, "\n";
310	};	504	};
311		505
		506
		507	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		508
		509	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		510	whether a file handle or path was passed.
		511
		512	On success, the callback is passed a hash reference with the following
		513	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		514	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		515	is passed.
		516
		517	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		518	C<ST_NOSUID>.
		519
		520	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		521	their correct value when available, or to C<0> on systems that do
		522	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		523	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		524	C<ST_NODIRATIME> and C<ST_RELATIME>.
		525
		526	Example: stat C</wd> and dump out the data if successful.
		527
		528	aio_statvfs "/wd", sub {
		529	my $f = $_[0]
		530	or die "statvfs: $!";
		531
		532	use Data::Dumper;
		533	say Dumper $f;
		534	};
		535
		536	# result:
		537	{
		538	bsize => 1024,
		539	bfree => 4333064312,
		540	blocks => 10253828096,
		541	files => 2050765568,
		542	flag => 4096,
		543	favail => 2042092649,
		544	bavail => 4333064312,
		545	ffree => 2042092649,
		546	namemax => 255,
		547	frsize => 1024,
		548	fsid => 1810
		549	}
		550
		551
		552	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		553
		554	Works like perl's C<utime> function (including the special case of $atime
		555	and $mtime being undef). Fractional times are supported if the underlying
		556	syscalls support them.
		557
		558	When called with a pathname, uses utimes(2) if available, otherwise
		559	utime(2). If called on a file descriptor, uses futimes(2) if available,
		560	otherwise returns ENOSYS, so this is not portable.
		561
		562	Examples:
		563
		564	# set atime and mtime to current time (basically touch(1)):
		565	aio_utime "path", undef, undef;
		566	# set atime to current time and mtime to beginning of the epoch:
		567	aio_utime "path", time, undef; # undef==0
		568
		569
		570	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		571
		572	Works like perl's C<chown> function, except that C<undef> for either $uid
		573	or $gid is being interpreted as "do not change" (but -1 can also be used).
		574
		575	Examples:
		576
		577	# same as "chown root path" in the shell:
		578	aio_chown "path", 0, -1;
		579	# same as above:
		580	aio_chown "path", 0, undef;
		581
		582
		583	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		584
		585	Works like truncate(2) or ftruncate(2).
		586
		587
		588	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		589
		590	Works like perl's C<chmod> function.
		591
		592
312	=item aio_unlink $pathname, $callback->($status)	593	=item aio_unlink $pathname, $callback->($status)
313		594
314	Asynchronously unlink (delete) a file and call the callback with the	595	Asynchronously unlink (delete) a file and call the callback with the
315	result code.	596	result code.
316		597
		598
		599	=item aio_mknod $path, $mode, $dev, $callback->($status)
		600
		601	[EXPERIMENTAL]
		602
		603	Asynchronously create a device node (or fifo). See mknod(2).
		604
		605	The only (POSIX-) portable way of calling this function is:
		606
		607	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		608
		609	See C<aio_stat> for info about some potentially helpful extra constants
		610	and functions.
		611
317	=item aio_link $srcpath, $dstpath, $callback->($status)	612	=item aio_link $srcpath, $dstpath, $callback->($status)
318		613
319	Asynchronously create a new link to the existing object at C<$srcpath> at	614	Asynchronously create a new link to the existing object at C<$srcpath> at
320	the path C<$dstpath> and call the callback with the result code.	615	the path C<$dstpath> and call the callback with the result code.
321		616
		617
322	=item aio_symlink $srcpath, $dstpath, $callback->($status)	618	=item aio_symlink $srcpath, $dstpath, $callback->($status)
323		619
324	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	620	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
325	the path C<$dstpath> and call the callback with the result code.	621	the path C<$dstpath> and call the callback with the result code.
326		622
		623
		624	=item aio_readlink $path, $callback->($link)
		625
		626	Asynchronously read the symlink specified by C<$path> and pass it to
		627	the callback. If an error occurs, nothing or undef gets passed to the
		628	callback.
		629
		630
327	=item aio_rename $srcpath, $dstpath, $callback->($status)	631	=item aio_rename $srcpath, $dstpath, $callback->($status)
328		632
329	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	633	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
330	rename(2) and call the callback with the result code.	634	rename(2) and call the callback with the result code.
331		635
		636
		637	=item aio_mkdir $pathname, $mode, $callback->($status)
		638
		639	Asynchronously mkdir (create) a directory and call the callback with
		640	the result code. C<$mode> will be modified by the umask at the time the
		641	request is executed, so do not change your umask.
		642
		643
332	=item aio_rmdir $pathname, $callback->($status)	644	=item aio_rmdir $pathname, $callback->($status)
333		645
334	Asynchronously rmdir (delete) a directory and call the callback with the	646	Asynchronously rmdir (delete) a directory and call the callback with the
335	result code.	647	result code.
		648
336		649
337	=item aio_readdir $pathname, $callback->($entries)	650	=item aio_readdir $pathname, $callback->($entries)
338		651
339	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	652	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
340	directory (i.e. opendir + readdir + closedir). The entries will not be	653	directory (i.e. opendir + readdir + closedir). The entries will not be
341	sorted, and will B<NOT> include the C<.> and C<..> entries.	654	sorted, and will B<NOT> include the C<.> and C<..> entries.
342		655
343	The callback a single argument which is either C<undef> or an array-ref	656	The callback is passed a single argument which is either C<undef> or an
344	with the filenames.	657	array-ref with the filenames.
		658
		659
		660	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		661
		662	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		663	behaviour and output format. In case of an error, C<$entries> will be
		664	C<undef>.
		665
		666	The flags are a combination of the following constants, ORed together (the
		667	flags will also be passed to the callback, possibly modified):
		668
		669	=over 4
		670
		671	=item IO::AIO::READDIR_DENTS
		672
		673	When this flag is off, then the callback gets an arrayref with of names
		674	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		675	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		676	entry in more detail.
		677
		678	C<$name> is the name of the entry.
		679
		680	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		681
		682	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		683	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		684	C<IO::AIO::DT_WHT>.
		685
		686	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		687	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		688	scalars are read-only: you can not modify them.
		689
		690	C<$inode> is the inode number (which might not be exact on systems with 64
		691	bit inode numbers and 32 bit perls). This field has unspecified content on
		692	systems that do not deliver the inode information.
		693
		694	=item IO::AIO::READDIR_DIRS_FIRST
		695
		696	When this flag is set, then the names will be returned in an order where
		697	likely directories come first. This is useful when you need to quickly
		698	find directories, or you want to find all directories while avoiding to
		699	stat() each entry.
		700
		701	If the system returns type information in readdir, then this is used
		702	to find directories directly. Otherwise, likely directories are files
		703	beginning with ".", or otherwise files with no dots, of which files with
		704	short names are tried first.
		705
		706	=item IO::AIO::READDIR_STAT_ORDER
		707
		708	When this flag is set, then the names will be returned in an order
		709	suitable for stat()'ing each one. That is, when you plan to stat()
		710	all files in the given directory, then the returned order will likely
		711	be fastest.
		712
		713	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		714	the likely dirs come first, resulting in a less optimal stat order.
		715
		716	=item IO::AIO::READDIR_FOUND_UNKNOWN
		717
		718	This flag should not be set when calling C<aio_readdirx>. Instead, it
		719	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		720	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		721	C<$type>'s are known, which can be used to speed up some algorithms.
		722
		723	=back
		724
		725
		726	=item aio_load $path, $data, $callback->($status)
		727
		728	This is a composite request that tries to fully load the given file into
		729	memory. Status is the same as with aio_read.
		730
		731	=cut
		732
		733	sub aio_load($$;$) {
		734	my ($path, undef, $cb) = @_;
		735	my $data = \$_[1];
		736
		737	my $pri = aioreq_pri;
		738	my $grp = aio_group $cb;
		739
		740	aioreq_pri $pri;
		741	add $grp aio_open $path, O_RDONLY, 0, sub {
		742	my $fh = shift
		743	or return $grp->result (-1);
		744
		745	aioreq_pri $pri;
		746	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		747	$grp->result ($_[0]);
		748	};
		749	};
		750
		751	$grp
		752	}
		753
		754	=item aio_copy $srcpath, $dstpath, $callback->($status)
		755
		756	Try to copy the I<file> (directories not supported as either source or
		757	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		758	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		759
		760	This is a composite request that creates the destination file with
		761	mode 0200 and copies the contents of the source file into it using
		762	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		763	uid/gid, in that order.
		764
		765	If an error occurs, the partial destination file will be unlinked, if
		766	possible, except when setting atime, mtime, access mode and uid/gid, where
		767	errors are being ignored.
		768
		769	=cut
		770
		771	sub aio_copy($$;$) {
		772	my ($src, $dst, $cb) = @_;
		773
		774	my $pri = aioreq_pri;
		775	my $grp = aio_group $cb;
		776
		777	aioreq_pri $pri;
		778	add $grp aio_open $src, O_RDONLY, 0, sub {
		779	if (my $src_fh = $_[0]) {
		780	my @stat = stat $src_fh; # hmm, might block over nfs?
		781
		782	aioreq_pri $pri;
		783	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		784	if (my $dst_fh = $_[0]) {
		785	aioreq_pri $pri;
		786	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		787	if ($_[0] == $stat[7]) {
		788	$grp->result (0);
		789	close $src_fh;
		790
		791	my $ch = sub {
		792	aioreq_pri $pri;
		793	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		794	aioreq_pri $pri;
		795	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		796	aioreq_pri $pri;
		797	add $grp aio_close $dst_fh;
		798	}
		799	};
		800	};
		801
		802	aioreq_pri $pri;
		803	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		804	if ($_[0] < 0 && $! == ENOSYS) {
		805	aioreq_pri $pri;
		806	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		807	} else {
		808	$ch->();
		809	}
		810	};
		811	} else {
		812	$grp->result (-1);
		813	close $src_fh;
		814	close $dst_fh;
		815
		816	aioreq $pri;
		817	add $grp aio_unlink $dst;
		818	}
		819	};
		820	} else {
		821	$grp->result (-1);
		822	}
		823	},
		824
		825	} else {
		826	$grp->result (-1);
		827	}
		828	};
		829
		830	$grp
		831	}
		832
		833	=item aio_move $srcpath, $dstpath, $callback->($status)
		834
		835	Try to move the I<file> (directories not supported as either source or
		836	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		837	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		838
		839	This is a composite request that tries to rename(2) the file first; if
		840	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		841	that is successful, unlinks the C<$srcpath>.
		842
		843	=cut
		844
		845	sub aio_move($$;$) {
		846	my ($src, $dst, $cb) = @_;
		847
		848	my $pri = aioreq_pri;
		849	my $grp = aio_group $cb;
		850
		851	aioreq_pri $pri;
		852	add $grp aio_rename $src, $dst, sub {
		853	if ($_[0] && $! == EXDEV) {
		854	aioreq_pri $pri;
		855	add $grp aio_copy $src, $dst, sub {
		856	$grp->result ($_[0]);
		857
		858	if (!$_[0]) {
		859	aioreq_pri $pri;
		860	add $grp aio_unlink $src;
		861	}
		862	};
		863	} else {
		864	$grp->result ($_[0]);
		865	}
		866	};
		867
		868	$grp
		869	}
345		870
346	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	871	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
347		872
348	Scans a directory (similar to C<aio_readdir>) but additionally tries to	873	Scans a directory (similar to C<aio_readdir>) but additionally tries to
349	separate the entries of directory C<$path> into two sets of names, ones	874	efficiently separate the entries of directory C<$path> into two sets of
350	you can recurse into (directories or links to them), and ones you cannot	875	names, directories you can recurse into (directories), and ones you cannot
351	recurse into (everything else).	876	recurse into (everything else, including symlinks to directories).
352		877
353	C<aio_scandir> is a composite request that consists of many sub	878	C<aio_scandir> is a composite request that creates of many sub requests_
354	requests. C<$maxreq> specifies the maximum number of outstanding aio	879	C<$maxreq> specifies the maximum number of outstanding aio requests that
355	requests that this function generates. If it is C<< <= 0 >>, then a	880	this function generates. If it is C<< <= 0 >>, then a suitable default
356	suitable default will be chosen (currently 8).	881	will be chosen (currently 4).
357		882
358	On error, the callback is called without arguments, otherwise it receives	883	On error, the callback is called without arguments, otherwise it receives
359	two array-refs with path-relative entry names.	884	two array-refs with path-relative entry names.
360		885
361	Example:	886	Example:
…		…
368		893
369	Implementation notes.	894	Implementation notes.
370		895
371	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	896	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
372		897
		898	If readdir returns file type information, then this is used directly to
		899	find directories.
		900
373	After reading the directory, the modification time, size etc. of the	901	Otherwise, after reading the directory, the modification time, size etc.
374	directory before and after the readdir is checked, and if they match (and	902	of the directory before and after the readdir is checked, and if they
375	isn't the current time), the link count will be used to decide how many	903	match (and isn't the current time), the link count will be used to decide
376	entries are directories (if >= 2). Otherwise, no knowledge of the number	904	how many entries are directories (if >= 2). Otherwise, no knowledge of the
377	of subdirectories will be assumed.	905	number of subdirectories will be assumed.
378		906
379	Then entries will be sorted into likely directories (everything without	907	Then entries will be sorted into likely directories a non-initial dot
380	a non-initial dot currently) and likely non-directories (everything	908	currently) and likely non-directories (see C<aio_readdirx>). Then every
381	else). Then every entry plus an appended C</.> will be C<stat>'ed,	909	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
382	likely directories first. If that succeeds, it assumes that the entry	910	in order of their inode numbers. If that succeeds, it assumes that the
383	is a directory or a symlink to directory (which will be checked	911	entry is a directory or a symlink to directory (which will be checked
384	seperately). This is often faster than stat'ing the entry itself because	912	seperately). This is often faster than stat'ing the entry itself because
385	filesystems might detect the type of the entry without reading the inode	913	filesystems might detect the type of the entry without reading the inode
386	data (e.g. ext2fs filetype feature).	914	data (e.g. ext2fs filetype feature), even on systems that cannot return
		915	the filetype information on readdir.
387		916
388	If the known number of directories (link count - 2) has been reached, the	917	If the known number of directories (link count - 2) has been reached, the
389	rest of the entries is assumed to be non-directories.	918	rest of the entries is assumed to be non-directories.
390		919
391	This only works with certainty on POSIX (= UNIX) filesystems, which	920	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
395	as those tend to return 0 or 1 as link counts, which disables the	924	as those tend to return 0 or 1 as link counts, which disables the
396	directory counting heuristic.	925	directory counting heuristic.
397		926
398	=cut	927	=cut
399		928
400	sub aio_scandir($$$) {	929	sub aio_scandir($$;$) {
401	my ($path, $maxreq, $cb) = @_;	930	my ($path, $maxreq, $cb) = @_;
402		931
		932	my $pri = aioreq_pri;
		933
403	my $grp = aio_group;	934	my $grp = aio_group $cb;
404		935
405	$maxreq = 8 if $maxreq <= 0;	936	$maxreq = 4 if $maxreq <= 0;
406		937
407	# stat once	938	# stat once
		939	aioreq_pri $pri;
408	add $grp aio_stat $path, sub {	940	add $grp aio_stat $path, sub {
409	return $cb->() if $_[0];	941	return $grp->result () if $_[0];
410	my $now = time;	942	my $now = time;
411	my $hash1 = join ":", (stat _)[0,1,3,7,9];	943	my $hash1 = join ":", (stat _)[0,1,3,7,9];
412		944
413	# read the directory entries	945	# read the directory entries
		946	aioreq_pri $pri;
414	add $grp aio_readdir $path, sub {	947	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
415	my $entries = shift	948	my $entries = shift
416	or return $cb->();	949	or return $grp->result ();
417		950
418	# stat the dir another time	951	# stat the dir another time
		952	aioreq_pri $pri;
419	add $grp aio_stat $path, sub {	953	add $grp aio_stat $path, sub {
420	my $hash2 = join ":", (stat _)[0,1,3,7,9];	954	my $hash2 = join ":", (stat _)[0,1,3,7,9];
421		955
422	my $ndirs;	956	my $ndirs;
423		957
424	# take the slow route if anything looks fishy	958	# take the slow route if anything looks fishy
425	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	959	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
426	$ndirs = -1;	960	$ndirs = -1;
427	} else {	961	} else {
428	# if nlink == 2, we are finished	962	# if nlink == 2, we are finished
429	# on non-posix-fs's, we rely on nlink < 2	963	# for non-posix-fs's, we rely on nlink < 2
430	$ndirs = (stat _)[3] - 2	964	$ndirs = (stat _)[3] - 2
431	or return $cb->([], $entries);	965	or return $grp->result ([], $entries);
432	}	966	}
433		967
434	# sort into likely dirs and likely nondirs
435	# dirs == files without ".", short entries first
436	$entries = [map $_->[0],
437	sort { $b->[1] cmp $a->[1] }
438	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
439	@$entries];
440
441	my (@dirs, @nondirs);	968	my (@dirs, @nondirs);
442		969
443	my ($statcb, $schedcb);	970	my $statgrp = add $grp aio_group sub {
444	my $nreq = 0;	971	$grp->result (\@dirs, \@nondirs);
		972	};
445		973
446	$schedcb = sub {	974	limit $statgrp $maxreq;
447	if (@$entries) {	975	feed $statgrp sub {
448	if ($nreq < $maxreq) {	976	return unless @$entries;
449	my $ent = pop @$entries;	977	my $entry = shift @$entries;
		978
		979	aioreq_pri $pri;
		980	add $statgrp aio_stat "$path/$entry/.", sub {
		981	if ($_[0] < 0) {
		982	push @nondirs, $entry;
		983	} else {
		984	# need to check for real directory
		985	aioreq_pri $pri;
		986	add $statgrp aio_lstat "$path/$entry", sub {
		987	if (-d _) {
		988	push @dirs, $entry;
		989
		990	unless (--$ndirs) {
		991	push @nondirs, @$entries;
		992	feed $statgrp;
		993	}
		994	} else {
		995	push @nondirs, $entry;
		996	}
450	$nreq++;	997	}
451	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
452	}	998	}
453	} elsif (!$nreq) {
454	# finished
455	undef $statcb;
456	undef $schedcb;
457	$cb->(\@dirs, \@nondirs) if $cb;
458	undef $cb;
459	}	999	};
460	};	1000	};
461	$statcb = sub {
462	my ($status, $entry) = @_;
463
464	if ($status < 0) {
465	$nreq--;
466	push @nondirs, $entry;
467	&$schedcb;
468	} else {
469	# need to check for real directory
470	add $grp aio_lstat "$path/$entry", sub {
471	$nreq--;
472
473	if (-d _) {
474	push @dirs, $entry;
475
476	if (!--$ndirs) {
477	push @nondirs, @$entries;
478	$entries = [];
479	}
480	} else {
481	push @nondirs, $entry;
482	}
483
484	&$schedcb;
485	}
486	}
487	};
488
489	&$schedcb while @$entries && $nreq < $maxreq;
490	};	1001	};
491	};	1002	};
492	};	1003	};
493		1004
494	$grp	1005	$grp
495	}	1006	}
496		1007
		1008	=item aio_rmtree $path, $callback->($status)
		1009
		1010	Delete a directory tree starting (and including) C<$path>, return the
		1011	status of the final C<rmdir> only. This is a composite request that
		1012	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		1013	everything else.
		1014
		1015	=cut
		1016
		1017	sub aio_rmtree;
		1018	sub aio_rmtree($;$) {
		1019	my ($path, $cb) = @_;
		1020
		1021	my $pri = aioreq_pri;
		1022	my $grp = aio_group $cb;
		1023
		1024	aioreq_pri $pri;
		1025	add $grp aio_scandir $path, 0, sub {
		1026	my ($dirs, $nondirs) = @_;
		1027
		1028	my $dirgrp = aio_group sub {
		1029	add $grp aio_rmdir $path, sub {
		1030	$grp->result ($_[0]);
		1031	};
		1032	};
		1033
		1034	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1035	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1036
		1037	add $grp $dirgrp;
		1038	};
		1039
		1040	$grp
		1041	}
		1042
		1043	=item aio_sync $callback->($status)
		1044
		1045	Asynchronously call sync and call the callback when finished.
		1046
497	=item aio_fsync $fh, $callback->($status)	1047	=item aio_fsync $fh, $callback->($status)
498		1048
499	Asynchronously call fsync on the given filehandle and call the callback	1049	Asynchronously call fsync on the given filehandle and call the callback
500	with the fsync result code.	1050	with the fsync result code.
501		1051
…		…
505	callback with the fdatasync result code.	1055	callback with the fdatasync result code.
506		1056
507	If this call isn't available because your OS lacks it or it couldn't be	1057	If this call isn't available because your OS lacks it or it couldn't be
508	detected, it will be emulated by calling C<fsync> instead.	1058	detected, it will be emulated by calling C<fsync> instead.
509		1059
		1060	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1061
		1062	Sync the data portion of the file specified by C<$offset> and C<$length>
		1063	to disk (but NOT the metadata), by calling the Linux-specific
		1064	sync_file_range call. If sync_file_range is not available or it returns
		1065	ENOSYS, then fdatasync or fsync is being substituted.
		1066
		1067	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1068	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1069	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1070	manpage for details.
		1071
		1072	=item aio_pathsync $path, $callback->($status)
		1073
		1074	This request tries to open, fsync and close the given path. This is a
		1075	composite request intended to sync directories after directory operations
		1076	(E.g. rename). This might not work on all operating systems or have any
		1077	specific effect, but usually it makes sure that directory changes get
		1078	written to disc. It works for anything that can be opened for read-only,
		1079	not just directories.
		1080
		1081	Future versions of this function might fall back to other methods when
		1082	C<fsync> on the directory fails (such as calling C<sync>).
		1083
		1084	Passes C<0> when everything went ok, and C<-1> on error.
		1085
		1086	=cut
		1087
		1088	sub aio_pathsync($;$) {
		1089	my ($path, $cb) = @_;
		1090
		1091	my $pri = aioreq_pri;
		1092	my $grp = aio_group $cb;
		1093
		1094	aioreq_pri $pri;
		1095	add $grp aio_open $path, O_RDONLY, 0, sub {
		1096	my ($fh) = @_;
		1097	if ($fh) {
		1098	aioreq_pri $pri;
		1099	add $grp aio_fsync $fh, sub {
		1100	$grp->result ($_[0]);
		1101
		1102	aioreq_pri $pri;
		1103	add $grp aio_close $fh;
		1104	};
		1105	} else {
		1106	$grp->result (-1);
		1107	}
		1108	};
		1109
		1110	$grp
		1111	}
		1112
		1113	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1114
		1115	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1116	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1117	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1118	scalar must only be modified in-place while an aio operation is pending on
		1119	it).
		1120
		1121	It calls the C<msync> function of your OS, if available, with the memory
		1122	area starting at C<$offset> in the string and ending C<$length> bytes
		1123	later. If C<$length> is negative, counts from the end, and if C<$length>
		1124	is C<undef>, then it goes till the end of the string. The flags can be
		1125	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1126	C<IO::AIO::MS_SYNC>.
		1127
		1128	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1129
		1130	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1131	scalars.
		1132
		1133	It touches (reads or writes) all memory pages in the specified
		1134	range inside the scalar. All caveats and parameters are the same
		1135	as for C<aio_msync>, above, except for flags, which must be either
		1136	C<0> (which reads all pages and ensures they are instantiated) or
		1137	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1138	writing an octet from it, which dirties the page).
		1139
		1140	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1141
		1142	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1143	scalars.
		1144
		1145	It reads in all the pages of the underlying storage into memory (if any)
		1146	and locks them, so they are not getting swapped/paged out or removed.
		1147
		1148	If C<$length> is undefined, then the scalar will be locked till the end.
		1149
		1150	On systems that do not implement C<mlock>, this function returns C<-1>
		1151	and sets errno to C<ENOSYS>.
		1152
		1153	Note that the corresponding C<munlock> is synchronous and is
		1154	documented under L<MISCELLANEOUS FUNCTIONS>.
		1155
		1156	Example: open a file, mmap and mlock it - both will be undone when
		1157	C<$data> gets destroyed.
		1158
		1159	open my $fh, "<", $path or die "$path: $!";
		1160	my $data;
		1161	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1162	aio_mlock $data; # mlock in background
		1163
		1164	=item aio_mlockall $flags, $callback->($status)
		1165
		1166	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1167	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1168
		1169	On systems that do not implement C<mlockall>, this function returns C<-1>
		1170	and sets errno to C<ENOSYS>.
		1171
		1172	Note that the corresponding C<munlockall> is synchronous and is
		1173	documented under L<MISCELLANEOUS FUNCTIONS>.
		1174
		1175	Example: asynchronously lock all current and future pages into memory.
		1176
		1177	aio_mlockall IO::AIO::MCL_FUTURE;
		1178
510	=item aio_group $callback->()	1179	=item aio_group $callback->(...)
511
512	[EXPERIMENTAL]
513		1180
514	This is a very special aio request: Instead of doing something, it is a	1181	This is a very special aio request: Instead of doing something, it is a
515	container for other aio requests, which is useful if you want to bundle	1182	container for other aio requests, which is useful if you want to bundle
516	many requests into a single, composite, request.	1183	many requests into a single, composite, request with a definite callback
		1184	and the ability to cancel the whole request with its subrequests.
517		1185
518	Returns an object of class L<IO::AIO::GRP>. See its documentation below	1186	Returns an object of class L<IO::AIO::GRP>. See its documentation below
519	for more info.	1187	for more info.
520		1188
521	Example:	1189	Example:
…		…
527	add $grp	1195	add $grp
528	(aio_stat ...),	1196	(aio_stat ...),
529	(aio_stat ...),	1197	(aio_stat ...),
530	...;	1198	...;
531		1199
		1200	=item aio_nop $callback->()
		1201
		1202	This is a special request - it does nothing in itself and is only used for
		1203	side effects, such as when you want to add a dummy request to a group so
		1204	that finishing the requests in the group depends on executing the given
		1205	code.
		1206
		1207	While this request does nothing, it still goes through the execution
		1208	phase and still requires a worker thread. Thus, the callback will not
		1209	be executed immediately but only after other requests in the queue have
		1210	entered their execution phase. This can be used to measure request
		1211	latency.
		1212
532	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED*	1213	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
533		1214
534	Mainly used for debugging and benchmarking, this aio request puts one of	1215	Mainly used for debugging and benchmarking, this aio request puts one of
535	the request workers to sleep for the given time.	1216	the request workers to sleep for the given time.
536		1217
537	While it is theoretically handy to have simple I/O scheduling requests	1218	While it is theoretically handy to have simple I/O scheduling requests
538	like sleep and file handle readable/writable, the overhead this creates	1219	like sleep and file handle readable/writable, the overhead this creates is
539	is immense, so do not use this function except to put your application	1220	immense (it blocks a thread for a long time) so do not use this function
540	under artificial I/O pressure.	1221	except to put your application under artificial I/O pressure.
541		1222
542	=back	1223	=back
543		1224
544	=head2 IO::AIO::REQ CLASS	1225	=head2 IO::AIO::REQ CLASS
545		1226
546	All non-aggregate C<aio_*> functions return an object of this class when	1227	All non-aggregate C<aio_*> functions return an object of this class when
547	called in non-void context.	1228	called in non-void context.
548		1229
549	A request always moves through the following five states in its lifetime,
550	in order: B<ready> (request has been created, but has not been executed
551	yet), B<execute> (request is currently being executed), B<pending>
552	(request has been executed but callback has not been called yet),
553	B<result> (results are being processed synchronously, includes calling the
554	callback) and B<done> (request has reached the end of its lifetime and
555	holds no resources anymore).
556
557	=over 4	1230	=over 4
558		1231
559	=item $req->cancel	1232	=item cancel $req
560		1233
561	Cancels the request, if possible. Has the effect of skipping execution	1234	Cancels the request, if possible. Has the effect of skipping execution
562	when entering the B<execute> state and skipping calling the callback when	1235	when entering the B<execute> state and skipping calling the callback when
563	entering the the B<result> state, but will leave the request otherwise	1236	entering the the B<result> state, but will leave the request otherwise
564	untouched. That means that requests that currently execute will not be	1237	untouched (with the exception of readdir). That means that requests that
565	stopped and resources held by the request will not be freed prematurely.	1238	currently execute will not be stopped and resources held by the request
		1239	will not be freed prematurely.
		1240
		1241	=item cb $req $callback->(...)
		1242
		1243	Replace (or simply set) the callback registered to the request.
566		1244
567	=back	1245	=back
568		1246
569	=head2 IO::AIO::GRP CLASS	1247	=head2 IO::AIO::GRP CLASS
570		1248
…		…
585	You add requests by calling the C<add> method with one or more	1263	You add requests by calling the C<add> method with one or more
586	C<IO::AIO::REQ> objects:	1264	C<IO::AIO::REQ> objects:
587		1265
588	$grp->add (aio_unlink "...");	1266	$grp->add (aio_unlink "...");
589		1267
590	add $grp aio_stat "...", sub { ... };	1268	add $grp aio_stat "...", sub {
		1269	$_[0] or return $grp->result ("error");
		1270
		1271	# add another request dynamically, if first succeeded
		1272	add $grp aio_open "...", sub {
		1273	$grp->result ("ok");
		1274	};
		1275	};
591		1276
592	This makes it very easy to create composite requests (see the source of	1277	This makes it very easy to create composite requests (see the source of
593	C<aio_move> for an application) that work and feel like simple requests.	1278	C<aio_move> for an application) that work and feel like simple requests.
594		1279
		1280	=over 4
		1281
595	The IO::AIO::GRP objects will be cleaned up during calls to	1282	=item * The IO::AIO::GRP objects will be cleaned up during calls to
596	C<IO::AIO::poll_cb>, just like any other request.	1283	C<IO::AIO::poll_cb>, just like any other request.
597		1284
598	They can be canceled like any other request. Canceling will cancel not	1285	=item * They can be canceled like any other request. Canceling will cancel not
599	just the request itself, but also all requests it contains.	1286	only the request itself, but also all requests it contains.
600		1287
601	They can also can also be added to other IO::AIO::GRP objects.	1288	=item * They can also can also be added to other IO::AIO::GRP objects.
		1289
		1290	=item * You must not add requests to a group from within the group callback (or
		1291	any later time).
		1292
		1293	=back
602		1294
603	Their lifetime, simplified, looks like this: when they are empty, they	1295	Their lifetime, simplified, looks like this: when they are empty, they
604	will finish very quickly. If they contain only requests that are in the	1296	will finish very quickly. If they contain only requests that are in the
605	C<done> state, they will also finish. Otherwise they will continue to	1297	C<done> state, they will also finish. Otherwise they will continue to
606	exist.	1298	exist.
607		1299
608	That means after creating a group you have some time to add requests. And	1300	That means after creating a group you have some time to add requests
609	in the callbacks of those requests, you can add further requests to the	1301	(precisely before the callback has been invoked, which is only done within
610	group. And only when all those requests have finished will the the group	1302	the C<poll_cb>). And in the callbacks of those requests, you can add
611	itself finish.	1303	further requests to the group. And only when all those requests have
		1304	finished will the the group itself finish.
612		1305
613	=over 4	1306	=over 4
614		1307
		1308	=item add $grp ...
		1309
615	=item $grp->add (...)	1310	=item $grp->add (...)
616
617	=item add $grp ...
618		1311
619	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	1312	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
620	be added, including other groups, as long as you do not create circular	1313	be added, including other groups, as long as you do not create circular
621	dependencies.	1314	dependencies.
622		1315
623	Returns all its arguments.	1316	Returns all its arguments.
624		1317
		1318	=item $grp->cancel_subs
		1319
		1320	Cancel all subrequests and clears any feeder, but not the group request
		1321	itself. Useful when you queued a lot of events but got a result early.
		1322
		1323	The group request will finish normally (you cannot add requests to the
		1324	group).
		1325
		1326	=item $grp->result (...)
		1327
		1328	Set the result value(s) that will be passed to the group callback when all
		1329	subrequests have finished and set the groups errno to the current value
		1330	of errno (just like calling C<errno> without an error number). By default,
		1331	no argument will be passed and errno is zero.
		1332
		1333	=item $grp->errno ([$errno])
		1334
		1335	Sets the group errno value to C<$errno>, or the current value of errno
		1336	when the argument is missing.
		1337
		1338	Every aio request has an associated errno value that is restored when
		1339	the callback is invoked. This method lets you change this value from its
		1340	default (0).
		1341
		1342	Calling C<result> will also set errno, so make sure you either set C<$!>
		1343	before the call to C<result>, or call c<errno> after it.
		1344
		1345	=item feed $grp $callback->($grp)
		1346
		1347	Sets a feeder/generator on this group: every group can have an attached
		1348	generator that generates requests if idle. The idea behind this is that,
		1349	although you could just queue as many requests as you want in a group,
		1350	this might starve other requests for a potentially long time. For example,
		1351	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
		1352	delaying any later requests for a long time.
		1353
		1354	To avoid this, and allow incremental generation of requests, you can
		1355	instead a group and set a feeder on it that generates those requests. The
		1356	feed callback will be called whenever there are few enough (see C<limit>,
		1357	below) requests active in the group itself and is expected to queue more
		1358	requests.
		1359
		1360	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1361	not impose any limits).
		1362
		1363	If the feed does not queue more requests when called, it will be
		1364	automatically removed from the group.
		1365
		1366	If the feed limit is C<0> when this method is called, it will be set to
		1367	C<2> automatically.
		1368
		1369	Example:
		1370
		1371	# stat all files in @files, but only ever use four aio requests concurrently:
		1372
		1373	my $grp = aio_group sub { print "finished\n" };
		1374	limit $grp 4;
		1375	feed $grp sub {
		1376	my $file = pop @files
		1377	or return;
		1378
		1379	add $grp aio_stat $file, sub { ... };
		1380	};
		1381
		1382	=item limit $grp $num
		1383
		1384	Sets the feeder limit for the group: The feeder will be called whenever
		1385	the group contains less than this many requests.
		1386
		1387	Setting the limit to C<0> will pause the feeding process.
		1388
		1389	The default value for the limit is C<0>, but note that setting a feeder
		1390	automatically bumps it up to C<2>.
		1391
625	=back	1392	=back
626		1393
627	=head2 SUPPORT FUNCTIONS	1394	=head2 SUPPORT FUNCTIONS
628		1395
		1396	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1397
629	=over 4	1398	=over 4
630		1399
631	=item $fileno = IO::AIO::poll_fileno	1400	=item $fileno = IO::AIO::poll_fileno
632		1401
633	Return the I<request result pipe file descriptor>. This filehandle must be	1402	Return the I<request result pipe file descriptor>. This filehandle must be
634	polled for reading by some mechanism outside this module (e.g. Event or	1403	polled for reading by some mechanism outside this module (e.g. EV, Glib,
635	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1404	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
636	to call C<poll_cb> to check the results.	1405	you have to call C<poll_cb> to check the results.
637		1406
638	See C<poll_cb> for an example.	1407	See C<poll_cb> for an example.
639		1408
640	=item IO::AIO::poll_cb	1409	=item IO::AIO::poll_cb
641		1410
642	Process all outstanding events on the result pipe. You have to call this	1411	Process some outstanding events on the result pipe. You have to call this
643	regularly. Returns the number of events processed. Returns immediately	1412	regularly. Returns C<0> if all events could be processed, or C<-1> if it
644	when no events are outstanding.	1413	returned earlier for whatever reason. Returns immediately when no events
		1414	are outstanding. The amount of events processed depends on the settings of
		1415	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1416
		1417	If not all requests were processed for whatever reason, the filehandle
		1418	will still be ready when C<poll_cb> returns, so normally you don't have to
		1419	do anything special to have it called later.
645		1420
646	Example: Install an Event watcher that automatically calls	1421	Example: Install an Event watcher that automatically calls
647	IO::AIO::poll_cb with high priority:	1422	IO::AIO::poll_cb with high priority (more examples can be found in the
		1423	SYNOPSIS section, at the top of this document):
648		1424
649	Event->io (fd => IO::AIO::poll_fileno,	1425	Event->io (fd => IO::AIO::poll_fileno,
650	poll => 'r', async => 1,	1426	poll => 'r', async => 1,
651	cb => \&IO::AIO::poll_cb);	1427	cb => \&IO::AIO::poll_cb);
652		1428
653	=item IO::AIO::poll_wait	1429	=item IO::AIO::poll_wait
654		1430
		1431	If there are any outstanding requests and none of them in the result
655	Wait till the result filehandle becomes ready for reading (simply does a	1432	phase, wait till the result filehandle becomes ready for reading (simply
656	C<select> on the filehandle. This is useful if you want to synchronously wait	1433	does a C<select> on the filehandle. This is useful if you want to
657	for some requests to finish).	1434	synchronously wait for some requests to finish).
658		1435
659	See C<nreqs> for an example.	1436	See C<nreqs> for an example.
660		1437
		1438	=item IO::AIO::poll
		1439
		1440	Waits until some requests have been handled.
		1441
		1442	Returns the number of requests processed, but is otherwise strictly
		1443	equivalent to:
		1444
		1445	IO::AIO::poll_wait, IO::AIO::poll_cb
		1446
661	=item IO::AIO::nreqs	1447	=item IO::AIO::flush
662		1448
663	Returns the number of requests currently outstanding (i.e. for which their	1449	Wait till all outstanding AIO requests have been handled.
664	callback has not been invoked yet).
665		1450
666	Example: wait till there are no outstanding requests anymore:	1451	Strictly equivalent to:
667		1452
668	IO::AIO::poll_wait, IO::AIO::poll_cb	1453	IO::AIO::poll_wait, IO::AIO::poll_cb
669	while IO::AIO::nreqs;	1454	while IO::AIO::nreqs;
670		1455
671	=item IO::AIO::flush	1456	=item IO::AIO::max_poll_reqs $nreqs
672		1457
673	Wait till all outstanding AIO requests have been handled.	1458	=item IO::AIO::max_poll_time $seconds
674		1459
675	Strictly equivalent to:	1460	These set the maximum number of requests (default C<0>, meaning infinity)
		1461	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1462	the maximum amount of time (default C<0>, meaning infinity) spent in
		1463	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1464	of time C<poll_cb> is allowed to use).
676		1465
677	IO::AIO::poll_wait, IO::AIO::poll_cb	1466	Setting C<max_poll_time> to a non-zero value creates an overhead of one
678	while IO::AIO::nreqs;	1467	syscall per request processed, which is not normally a problem unless your
		1468	callbacks are really really fast or your OS is really really slow (I am
		1469	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
679		1470
680	=item IO::AIO::poll	1471	Setting these is useful if you want to ensure some level of
		1472	interactiveness when perl is not fast enough to process all requests in
		1473	time.
681		1474
682	Waits until some requests have been handled.	1475	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
683		1476
684	Strictly equivalent to:	1477	Example: Install an Event watcher that automatically calls
		1478	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1479	program get the CPU sometimes even under high AIO load.
685		1480
686	IO::AIO::poll_wait, IO::AIO::poll_cb	1481	# try not to spend much more than 0.1s in poll_cb
687	if IO::AIO::nreqs;	1482	IO::AIO::max_poll_time 0.1;
		1483
		1484	# use a low priority so other tasks have priority
		1485	Event->io (fd => IO::AIO::poll_fileno,
		1486	poll => 'r', nice => 1,
		1487	cb => &IO::AIO::poll_cb);
		1488
		1489	=back
		1490
		1491	=head3 CONTROLLING THE NUMBER OF THREADS
		1492
		1493	=over
688		1494
689	=item IO::AIO::min_parallel $nthreads	1495	=item IO::AIO::min_parallel $nthreads
690		1496
691	Set the minimum number of AIO threads to C<$nthreads>. The current default	1497	Set the minimum number of AIO threads to C<$nthreads>. The current
692	is C<4>, which means four asynchronous operations can be done at one time	1498	default is C<8>, which means eight asynchronous operations can execute
693	(the number of outstanding operations, however, is unlimited).	1499	concurrently at any one time (the number of outstanding requests,
		1500	however, is unlimited).
694		1501
695	IO::AIO starts threads only on demand, when an AIO request is queued and	1502	IO::AIO starts threads only on demand, when an AIO request is queued and
696	no free thread exists.	1503	no free thread exists. Please note that queueing up a hundred requests can
		1504	create demand for a hundred threads, even if it turns out that everything
		1505	is in the cache and could have been processed faster by a single thread.
697		1506
698	It is recommended to keep the number of threads low, as some Linux	1507	It is recommended to keep the number of threads relatively low, as some
699	kernel versions will scale negatively with the number of threads (higher	1508	Linux kernel versions will scale negatively with the number of threads
700	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1509	(higher parallelity => MUCH higher latency). With current Linux 2.6
701	threads should be fine.	1510	versions, 4-32 threads should be fine.
702		1511
703	Under most circumstances you don't need to call this function, as the	1512	Under most circumstances you don't need to call this function, as the
704	module selects a default that is suitable for low to moderate load.	1513	module selects a default that is suitable for low to moderate load.
705		1514
706	=item IO::AIO::max_parallel $nthreads	1515	=item IO::AIO::max_parallel $nthreads
…		…
715	This module automatically runs C<max_parallel 0> at program end, to ensure	1524	This module automatically runs C<max_parallel 0> at program end, to ensure
716	that all threads are killed and that there are no outstanding requests.	1525	that all threads are killed and that there are no outstanding requests.
717		1526
718	Under normal circumstances you don't need to call this function.	1527	Under normal circumstances you don't need to call this function.
719		1528
		1529	=item IO::AIO::max_idle $nthreads
		1530
		1531	Limit the number of threads (default: 4) that are allowed to idle
		1532	(i.e., threads that did not get a request to process within the idle
		1533	timeout (default: 10 seconds). That means if a thread becomes idle while
		1534	C<$nthreads> other threads are also idle, it will free its resources and
		1535	exit.
		1536
		1537	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1538	to allow for extremely high load situations, but want to free resources
		1539	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1540
		1541	The default is probably ok in most situations, especially if thread
		1542	creation is fast. If thread creation is very slow on your system you might
		1543	want to use larger values.
		1544
		1545	=item IO::AIO::idle_timeout $seconds
		1546
		1547	Sets the minimum idle timeout (default 10) after which worker threads are
		1548	allowed to exit. SEe C<IO::AIO::max_idle>.
		1549
720	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1550	=item IO::AIO::max_outstanding $maxreqs
		1551
		1552	This is a very bad function to use in interactive programs because it
		1553	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1554	use an C<aio_group> together with a feed callback.
721		1555
722	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1556	Sets the maximum number of outstanding requests to C<$nreqs>. If you
723	try to queue up more than this number of requests, the caller will block until	1557	do queue up more than this number of requests, the next call to the
724	some requests have been handled.	1558	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1559	function will block until the limit is no longer exceeded.
725		1560
726	The default is very large, so normally there is no practical limit. If you	1561	The default value is very large, so there is no practical limit on the
727	queue up many requests in a loop it often improves speed if you set	1562	number of outstanding requests.
728	this to a relatively low number, such as C<100>.
729		1563
730	Under normal circumstances you don't need to call this function.	1564	You can still queue as many requests as you want. Therefore,
		1565	C<max_outstanding> is mainly useful in simple scripts (with low values) or
		1566	as a stop gap to shield against fatal memory overflow (with large values).
731		1567
732	=back	1568	=back
733		1569
		1570	=head3 STATISTICAL INFORMATION
		1571
		1572	=over
		1573
		1574	=item IO::AIO::nreqs
		1575
		1576	Returns the number of requests currently in the ready, execute or pending
		1577	states (i.e. for which their callback has not been invoked yet).
		1578
		1579	Example: wait till there are no outstanding requests anymore:
		1580
		1581	IO::AIO::poll_wait, IO::AIO::poll_cb
		1582	while IO::AIO::nreqs;
		1583
		1584	=item IO::AIO::nready
		1585
		1586	Returns the number of requests currently in the ready state (not yet
		1587	executed).
		1588
		1589	=item IO::AIO::npending
		1590
		1591	Returns the number of requests currently in the pending state (executed,
		1592	but not yet processed by poll_cb).
		1593
		1594	=back
		1595
		1596	=head3 MISCELLANEOUS FUNCTIONS
		1597
		1598	IO::AIO implements some functions that might be useful, but are not
		1599	asynchronous.
		1600
		1601	=over 4
		1602
		1603	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1604
		1605	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1606	but is blocking (this makes most sense if you know the input data is
		1607	likely cached already and the output filehandle is set to non-blocking
		1608	operations).
		1609
		1610	Returns the number of bytes copied, or C<-1> on error.
		1611
		1612	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1613
		1614	Simply calls the C<posix_fadvise> function (see its
		1615	manpage for details). The following advice constants are
		1616	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1617	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1618	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1619
		1620	On systems that do not implement C<posix_fadvise>, this function returns
		1621	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1622
		1623	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1624
		1625	Simply calls the C<posix_madvise> function (see its
		1626	manpage for details). The following advice constants are
		1627	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1628	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1629
		1630	On systems that do not implement C<posix_madvise>, this function returns
		1631	ENOSYS, otherwise the return value of C<posix_madvise>.
		1632
		1633	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1634
		1635	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1636	$scalar (see its manpage for details). The following protect
		1637	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1638	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1639
		1640	On systems that do not implement C<mprotect>, this function returns
		1641	ENOSYS, otherwise the return value of C<mprotect>.
		1642
		1643	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1644
		1645	Memory-maps a file (or anonymous memory range) and attaches it to the
		1646	given C<$scalar>, which will act like a string scalar.
		1647
		1648	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1649	change the string length, and most read-only operations such as copying it
		1650	or searching it with regexes and so on.
		1651
		1652	Anything else is unsafe and will, at best, result in memory leaks.
		1653
		1654	The memory map associated with the C<$scalar> is automatically removed
		1655	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1656	C<IO::AIO::munmap> functions are called.
		1657
		1658	This calls the C<mmap>(2) function internally. See your system's manual
		1659	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1660
		1661	The C<$length> must be larger than zero and smaller than the actual
		1662	filesize.
		1663
		1664	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1665	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1666
		1667	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1668	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1669	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1670	(which is set to C<MAP_ANON> if your system only provides this
		1671	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1672	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1673	C<IO::AIO::MAP_NONBLOCK>
		1674
		1675	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1676
		1677	C<$offset> is the offset from the start of the file - it generally must be
		1678	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1679
		1680	Example:
		1681
		1682	use Digest::MD5;
		1683	use IO::AIO;
		1684
		1685	open my $fh, "<verybigfile"
		1686	or die "$!";
		1687
		1688	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1689	or die "verybigfile: $!";
		1690
		1691	my $fast_md5 = md5 $data;
		1692
		1693	=item IO::AIO::munmap $scalar
		1694
		1695	Removes a previous mmap and undefines the C<$scalar>.
		1696
		1697	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1698
		1699	Calls the C<munlock> function, undoing the effects of a previous
		1700	C<aio_mlock> call (see its description for details).
		1701
		1702	=item IO::AIO::munlockall
		1703
		1704	Calls the C<munlockall> function.
		1705
		1706	On systems that do not implement C<munlockall>, this function returns
		1707	ENOSYS, otherwise the return value of C<munlockall>.
		1708
		1709	=back
		1710
734	=cut	1711	=cut
735		1712
736	# support function to convert a fd into a perl filehandle
737	sub _fd2fh {
738	return undef if $_[0] < 0;
739
740	# try to generate nice filehandles
741	my $sym = "IO::AIO::fd#$_[0]";
742	local *$sym;
743
744	open *$sym, "+<&=$_[0]" # usually works under any unix
745	or open *$sym, "<&=$_[0]" # cygwin needs this
746	or open *$sym, ">&=$_[0]" # or this
747	or return undef;
748
749	*$sym
750	}
751
752	min_parallel 4;	1713	min_parallel 8;
753		1714
754	END {	1715	END { flush }
755	max_parallel 0;
756	}
757		1716
758	1;	1717	1;
		1718
		1719	=head1 EVENT LOOP INTEGRATION
		1720
		1721	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1722	automatically into many event loops:
		1723
		1724	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1725	use AnyEvent::AIO;
		1726
		1727	You can also integrate IO::AIO manually into many event loops, here are
		1728	some examples of how to do this:
		1729
		1730	# EV integration
		1731	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1732
		1733	# Event integration
		1734	Event->io (fd => IO::AIO::poll_fileno,
		1735	poll => 'r',
		1736	cb => \&IO::AIO::poll_cb);
		1737
		1738	# Glib/Gtk2 integration
		1739	add_watch Glib::IO IO::AIO::poll_fileno,
		1740	in => sub { IO::AIO::poll_cb; 1 };
		1741
		1742	# Tk integration
		1743	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1744	readable => \&IO::AIO::poll_cb);
		1745
		1746	# Danga::Socket integration
		1747	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1748	\&IO::AIO::poll_cb);
759		1749
760	=head2 FORK BEHAVIOUR	1750	=head2 FORK BEHAVIOUR
761		1751
762	This module should do "the right thing" when the process using it forks:	1752	This module should do "the right thing" when the process using it forks:
763		1753
764	Before the fork, IO::AIO enters a quiescent state where no requests	1754	Before the fork, IO::AIO enters a quiescent state where no requests
765	can be added in other threads and no results will be processed. After	1755	can be added in other threads and no results will be processed. After
766	the fork the parent simply leaves the quiescent state and continues	1756	the fork the parent simply leaves the quiescent state and continues
767	request/result processing, while the child clears the request/result	1757	request/result processing, while the child frees the request/result queue
768	queue (so the requests started before the fork will only be handled in	1758	(so that the requests started before the fork will only be handled in the
769	the parent). Threads will be started on demand until the limit ste in the	1759	parent). Threads will be started on demand until the limit set in the
770	parent process has been reached again.	1760	parent process has been reached again.
771		1761
772	In short: the parent will, after a short pause, continue as if fork had	1762	In short: the parent will, after a short pause, continue as if fork had
773	not been called, while the child will act as if IO::AIO has not been used	1763	not been called, while the child will act as if IO::AIO has not been used
774	yet.	1764	yet.
775		1765
		1766	=head2 MEMORY USAGE
		1767
		1768	Per-request usage:
		1769
		1770	Each aio request uses - depending on your architecture - around 100-200
		1771	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1772	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1773	scalars and other data passed into aio requests will also be locked and
		1774	will consume memory till the request has entered the done state.
		1775
		1776	This is not awfully much, so queuing lots of requests is not usually a
		1777	problem.
		1778
		1779	Per-thread usage:
		1780
		1781	In the execution phase, some aio requests require more memory for
		1782	temporary buffers, and each thread requires a stack and other data
		1783	structures (usually around 16k-128k, depending on the OS).
		1784
		1785	=head1 KNOWN BUGS
		1786
		1787	Known bugs will be fixed in the next release.
		1788
776	=head1 SEE ALSO	1789	=head1 SEE ALSO
777		1790
778	L<Coro>, L<Linux::AIO> (obsolete).	1791	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1792	more natural syntax.
779		1793
780	=head1 AUTHOR	1794	=head1 AUTHOR
781		1795
782	Marc Lehmann <schmorp@schmorp.de>	1796	Marc Lehmann <schmorp@schmorp.de>
783	http://home.schmorp.de/	1797	http://home.schmorp.de/

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