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Revision 1.69 by root, Tue Oct 24 03:40:25 2006 UTC vs.
Revision 1.203 by root, Thu Jul 7 22:36:18 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
…		…
25	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
26		27
27	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
28	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
29		30
30	# AnyEvent integration
31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
33
34	# Event integration
35	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',
37	cb => \&IO::AIO::poll_cb);
38
39	# Glib/Gtk2 integration
40	add_watch Glib::IO IO::AIO::poll_fileno,
41	in => sub { IO::AIO::poll_cb; 1 };
42
43	# Tk integration
44	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
45	readable => \&IO::AIO::poll_cb);
46
47	# Danga::Socket integration
48	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
49	\&IO::AIO::poll_cb);
50
51	=head1 DESCRIPTION	31	=head1 DESCRIPTION
52		32
53	This module implements asynchronous I/O using whatever means your	33	This module implements asynchronous I/O using whatever means your
54	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>).
55		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
56	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
57	and signal their completion. You don't need thread support in perl, and	54	requests and signal their completion. You don't need thread support
58	the threads created by this module will not be visible to perl. In the	55	in perl, and the threads created by this module will not be visible
59	future, this module might make use of the native aio functions available	56	to perl. In the future, this module might make use of the native aio
60	on many operating systems. However, they are often not well-supported	57	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	58	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	and they would only support aio_read and aio_write, so the remaining	59	files currently, for example), and they would only support aio_read and
63	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.
64		62
65	Although the module will work with in the presence of other threads,	63	Although the module will work in the presence of other (Perl-) threads,
66	it is currently not reentrant in any way, so use appropriate locking	64	it is currently not reentrant in any way, so use appropriate locking
67	yourself, always call C<poll_cb> from within the same thread, or never	65	yourself, always call C<poll_cb> from within the same thread, or never
68	call C<poll_cb> (or other C<aio_> functions) recursively.	66	call C<poll_cb> (or other C<aio_> functions) recursively.
69		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
		161
70	=cut	162	=cut
71		163
72	package IO::AIO;	164	package IO::AIO;
73		165
74	no warnings;	166	use Carp ();
75	use strict 'vars';	167
		168	use common::sense;
76		169
77	use base 'Exporter';	170	use base 'Exporter';
78		171
79	BEGIN {	172	BEGIN {
80	our $VERSION = '2.0';	173	our $VERSION = '3.93';
81		174
82	our @AIO_REQ = 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
83	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
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	177	aio_scandir aio_symlink aio_readlink aio_realpath aio_sync aio_fsync
		178	aio_fdatasync aio_sync_file_range aio_fallocate
		179	aio_pathsync aio_readahead
		180	aio_rename aio_link aio_move aio_copy aio_group
		181	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		182	aio_chmod aio_utime aio_truncate
		183	aio_msync aio_mtouch aio_mlock aio_mlockall
85	aio_group aio_nop);	184	aio_statvfs);
		185
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	186	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	187	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	188	min_parallel max_parallel max_idle idle_timeout
		189	nreqs nready npending nthreads
		190	max_poll_time max_poll_reqs
		191	sendfile fadvise madvise
		192	mmap munmap munlock munlockall);
		193
		194	push @AIO_REQ, qw(aio_busy); # not exported
89		195
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	196	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		197
92	require XSLoader;	198	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	199	XSLoader::load ("IO::AIO", $VERSION);
94	}	200	}
95		201
96	=head1 FUNCTIONS	202	=head1 FUNCTIONS
97		203
		204	=head2 QUICK OVERVIEW
		205
		206	This section simply lists the prototypes of the most important functions
		207	for quick reference. See the following sections for function-by-function
		208	documentation.
		209
		210	aio_open $pathname, $flags, $mode, $callback->($fh)
		211	aio_close $fh, $callback->($status)
		212	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		213	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		214	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		215	aio_readahead $fh,$offset,$length, $callback->($retval)
		216	aio_stat $fh_or_path, $callback->($status)
		217	aio_lstat $fh, $callback->($status)
		218	aio_statvfs $fh_or_path, $callback->($statvfs)
		219	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		220	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		221	aio_truncate $fh_or_path, $offset, $callback->($status)
		222	aio_chmod $fh_or_path, $mode, $callback->($status)
		223	aio_unlink $pathname, $callback->($status)
		224	aio_mknod $path, $mode, $dev, $callback->($status)
		225	aio_link $srcpath, $dstpath, $callback->($status)
		226	aio_symlink $srcpath, $dstpath, $callback->($status)
		227	aio_readlink $path, $callback->($link)
		228	aio_realpath $path, $callback->($link)
		229	aio_rename $srcpath, $dstpath, $callback->($status)
		230	aio_mkdir $pathname, $mode, $callback->($status)
		231	aio_rmdir $pathname, $callback->($status)
		232	aio_readdir $pathname, $callback->($entries)
		233	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		234	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		235	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		236	aio_load $path, $data, $callback->($status)
		237	aio_copy $srcpath, $dstpath, $callback->($status)
		238	aio_move $srcpath, $dstpath, $callback->($status)
		239	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		240	aio_rmtree $path, $callback->($status)
		241	aio_sync $callback->($status)
		242	aio_fsync $fh, $callback->($status)
		243	aio_fdatasync $fh, $callback->($status)
		244	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		245	aio_pathsync $path, $callback->($status)
		246	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		247	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		248	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		249	aio_mlockall $flags, $callback->($status)
		250	aio_group $callback->(...)
		251	aio_nop $callback->()
		252
		253	$prev_pri = aioreq_pri [$pri]
		254	aioreq_nice $pri_adjust
		255
		256	IO::AIO::poll_wait
		257	IO::AIO::poll_cb
		258	IO::AIO::poll
		259	IO::AIO::flush
		260	IO::AIO::max_poll_reqs $nreqs
		261	IO::AIO::max_poll_time $seconds
		262	IO::AIO::min_parallel $nthreads
		263	IO::AIO::max_parallel $nthreads
		264	IO::AIO::max_idle $nthreads
		265	IO::AIO::idle_timeout $seconds
		266	IO::AIO::max_outstanding $maxreqs
		267	IO::AIO::nreqs
		268	IO::AIO::nready
		269	IO::AIO::npending
		270
		271	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		272	IO::AIO::fadvise $fh, $offset, $len, $advice
		273	IO::AIO::madvise $scalar, $offset, $length, $advice
		274	IO::AIO::mprotect $scalar, $offset, $length, $protect
		275	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		276	IO::AIO::munlockall
		277
98	=head2 AIO FUNCTIONS	278	=head2 AIO REQUEST FUNCTIONS
99		279
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	280	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	281	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	282	and they all accept an additional (and optional) C<$callback> argument
103	which must be a code reference. This code reference will get called with	283	which must be a code reference. This code reference will get called with
104	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	284	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
105	perl, which usually delivers "false") as it's sole argument when the given	285	perl, which usually delivers "false") as its sole argument after the given
106	syscall has been executed asynchronously.	286	syscall has been executed asynchronously.
107		287
108	All functions expecting a filehandle keep a copy of the filehandle	288	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	289	internally until the request has finished.
110		290
111	All requests return objects of type L<IO::AIO::REQ> that allow further	291	All functions return request objects of type L<IO::AIO::REQ> that allow
112	manipulation of those requests while they are in-flight.	292	further manipulation of those requests while they are in-flight.
113		293
114	The pathnames you pass to these routines I<must> be absolute and	294	The pathnames you pass to these routines I<must> be absolute and
115	encoded in byte form. The reason for the former is that at the time the	295	encoded as octets. The reason for the former is that at the time the
116	request is being executed, the current working directory could have	296	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	297	changed. Alternatively, you can make sure that you never change the
118	current working directory.	298	current working directory anywhere in the program and then use relative
		299	paths.
119		300
120	To encode pathnames to byte form, either make sure you either: a)	301	To encode pathnames as octets, either make sure you either: a) always pass
121	always pass in filenames you got from outside (command line, readdir	302	in filenames you got from outside (command line, readdir etc.) without
122	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	303	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
123	your pathnames to the locale (or other) encoding in effect in the user	304	your pathnames to the locale (or other) encoding in effect in the user
124	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	305	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	306	use something else to ensure your scalar has the correct contents.
		307
		308	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		309	handles correctly whether it is set or not.
126		310
127	=over 4	311	=over 4
128		312
129	=item aioreq_pri $pri	313	=item $prev_pri = aioreq_pri [$pri]
130		314
131	Sets the priority for the next aio request. The default priority	315	Returns the priority value that would be used for the next request and, if
		316	C<$pri> is given, sets the priority for the next aio request.
		317
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	318	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	319	and C<4>, respectively. Requests with higher priority will be serviced
		320	first.
134		321
135	The priority will be reset to C<0> after each call to one of the C<aio_>	322	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	323	functions.
137		324
138	Example: open a file with low priority, then read something from it with	325	Example: open a file with low priority, then read something from it with
139	higher priority so the read request is serviced before other low priority	326	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	327	open requests (potentially spamming the cache):
…		…
147	aio_read $_[0], ..., sub {	334	aio_read $_[0], ..., sub {
148	...	335	...
149	};	336	};
150	};	337	};
151		338
		339
152	=item aioreq_nice $pri_adjust	340	=item aioreq_nice $pri_adjust
153		341
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	342	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	343	priority, so the effect is cumulative.
		344
156		345
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	346	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		347
159	Asynchronously open or create a file and call the callback with a newly	348	Asynchronously open or create a file and call the callback with a newly
160	created filehandle for the file.	349	created filehandle for the file.
…		…
166	list. They are the same as used by C<sysopen>.	355	list. They are the same as used by C<sysopen>.
167		356
168	Likewise, C<$mode> specifies the mode of the newly created file, if it	357	Likewise, C<$mode> specifies the mode of the newly created file, if it
169	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	358	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
170	except that it is mandatory (i.e. use C<0> if you don't create new files,	359	except that it is mandatory (i.e. use C<0> if you don't create new files,
171	and C<0666> or C<0777> if you do).	360	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		361	by the umask in effect then the request is being executed, so better never
		362	change the umask.
172		363
173	Example:	364	Example:
174		365
175	aio_open "/etc/passwd", O_RDONLY, 0, sub {	366	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
176	if ($_[0]) {	367	if ($_[0]) {
177	print "open successful, fh is $_[0]\n";	368	print "open successful, fh is $_[0]\n";
178	...	369	...
179	} else {	370	} else {
180	die "open failed: $!\n";	371	die "open failed: $!\n";
181	}	372	}
182	};	373	};
183		374
		375	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		376	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		377	following POSIX and non-POSIX constants are available (missing ones on
		378	your system are, as usual, C<0>):
		379
		380	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		381	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		382	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		383
		384
184	=item aio_close $fh, $callback->($status)	385	=item aio_close $fh, $callback->($status)
185		386
186	Asynchronously close a file and call the callback with the result	387	Asynchronously close a file and call the callback with the result
187	code. I<WARNING:> although accepted, you should not pass in a perl	388	code.
188	filehandle here, as perl will likely close the file descriptor another
189	time when the filehandle is destroyed. Normally, you can safely call perls
190	C<close> or just let filehandles go out of scope.
191		389
192	This is supposed to be a bug in the API, so that might change. It's	390	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
193	therefore best to avoid this function.	391	closing the file descriptor associated with the filehandle itself.
		392
		393	Therefore, C<aio_close> will not close the filehandle - instead it will
		394	use dup2 to overwrite the file descriptor with the write-end of a pipe
		395	(the pipe fd will be created on demand and will be cached).
		396
		397	Or in other words: the file descriptor will be closed, but it will not be
		398	free for reuse until the perl filehandle is closed.
		399
		400	=cut
194		401
195	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	402	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
196		403
197	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	404	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
198		405
199	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	406	Reads or writes C<$length> bytes from or to the specified C<$fh> and
200	into the scalar given by C<data> and offset C<dataoffset> and calls the	407	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
201	callback without the actual number of bytes read (or -1 on error, just	408	and calls the callback without the actual number of bytes read (or -1 on
202	like the syscall).	409	error, just like the syscall).
		410
		411	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		412	offset plus the actual number of bytes read.
		413
		414	If C<$offset> is undefined, then the current file descriptor offset will
		415	be used (and updated), otherwise the file descriptor offset will not be
		416	changed by these calls.
		417
		418	If C<$length> is undefined in C<aio_write>, use the remaining length of
		419	C<$data>.
		420
		421	If C<$dataoffset> is less than zero, it will be counted from the end of
		422	C<$data>.
203		423
204	The C<$data> scalar I<MUST NOT> be modified in any way while the request	424	The C<$data> scalar I<MUST NOT> be modified in any way while the request
205	is outstanding. Modifying it can result in segfaults or WW3 (if the	425	is outstanding. Modifying it can result in segfaults or World War III (if
206	necessary/optional hardware is installed).	426	the necessary/optional hardware is installed).
207		427
208	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	428	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
209	offset C<0> within the scalar:	429	offset C<0> within the scalar:
210		430
211	aio_read $fh, 7, 15, $buffer, 0, sub {	431	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	432	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	433	print "read $_[0] bytes: <$buffer>\n";
214	};	434	};
215		435
216	=item aio_move $srcpath, $dstpath, $callback->($status)
217
218	[EXPERIMENTAL due to internal aio_group use]
219
220	Try to move the I<file> (directories not supported as either source or
221	destination) from C<$srcpath> to C<$dstpath> and call the callback with
222	the C<0> (error) or C<-1> ok.
223
224	This is a composite request that tries to rename(2) the file first. If
225	rename files with C<EXDEV>, it creates the destination file with mode 0200
226	and copies the contents of the source file into it using C<aio_sendfile>,
227	followed by restoring atime, mtime, access mode and uid/gid, in that
228	order, and unlinking the C<$srcpath>.
229
230	If an error occurs, the partial destination file will be unlinked, if
231	possible, except when setting atime, mtime, access mode and uid/gid, where
232	errors are being ignored.
233
234	=cut
235
236	sub aio_move($$$) {
237	my ($src, $dst, $cb) = @_;
238
239	my $grp = aio_group $cb;
240
241	add $grp aio_rename $src, $dst, sub {
242	if ($_[0] && $! == EXDEV) {
243	add $grp aio_open $src, O_RDONLY, 0, sub {
244	if (my $src_fh = $_[0]) {
245	my @stat = stat $src_fh;
246
247	add $grp aio_open $dst, O_WRONLY, 0200, sub {
248	if (my $dst_fh = $_[0]) {
249	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
250	close $src_fh;
251
252	if ($_[0] == $stat[7]) {
253	utime $stat[8], $stat[9], $dst;
254	chmod $stat[2] & 07777, $dst_fh;
255	chown $stat[4], $stat[5], $dst_fh;
256	close $dst_fh;
257
258	add $grp aio_unlink $src, sub {
259	$grp->result ($_[0]);
260	};
261	} else {
262	my $errno = $!;
263	add $grp aio_unlink $dst, sub {
264	$! = $errno;
265	$grp->result (-1);
266	};
267	}
268	};
269	} else {
270	$grp->result (-1);
271	}
272	},
273
274	} else {
275	$grp->result (-1);
276	}
277	};
278	} else {
279	$grp->result ($_[0]);
280	}
281	};
282
283	$grp
284	}
285		436
286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	437	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
287		438
288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	439	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
289	reading at byte offset C<$in_offset>, and starts writing at the current	440	reading at byte offset C<$in_offset>, and starts writing at the current
290	file offset of C<$out_fh>. Because of that, it is not safe to issue more	441	file offset of C<$out_fh>. Because of that, it is not safe to issue more
291	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each	442	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
292	other.	443	other. The same C<$in_fh> works fine though, as this function does not
		444	move or use the file offset of C<$in_fh>.
293		445
		446	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		447	are written, and there is no way to find out how many more bytes have been
		448	read from C<aio_sendfile> alone, as C<aio_sendfile> only provides the
		449	number of bytes written to C<$out_fh>. Only if the result value equals
		450	C<$length> one can assume that C<$length> bytes have been read.
		451
		452	Unlike with other C<aio_> functions, it makes a lot of sense to use
		453	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		454	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		455	the socket I/O will be non-blocking. Note, however, that you can run
		456	into a trap where C<aio_sendfile> reads some data with readahead, then
		457	fails to write all data, and when the socket is ready the next time, the
		458	data in the cache is already lost, forcing C<aio_sendfile> to again hit
		459	the disk. Explicit C<aio_read> + C<aio_write> let's you better control
		460	resource usage.
		461
294	This call tries to make use of a native C<sendfile> syscall to provide	462	This call tries to make use of a native C<sendfile>-like syscall to
295	zero-copy operation. For this to work, C<$out_fh> should refer to a	463	provide zero-copy operation. For this to work, C<$out_fh> should refer to
296	socket, and C<$in_fh> should refer to mmap'able file.	464	a socket, and C<$in_fh> should refer to an mmap'able file.
297		465
298	If the native sendfile call fails or is not implemented, it will be	466	If a native sendfile cannot be found or it fails with C<ENOSYS>,
299	emulated, so you can call C<aio_sendfile> on any type of filehandle	467	C<EINVAL>, C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or
		468	C<ENOTSOCK>, it will be emulated, so you can call C<aio_sendfile> on any
300	regardless of the limitations of the operating system.	469	type of filehandle regardless of the limitations of the operating system.
301		470
302	Please note, however, that C<aio_sendfile> can read more bytes from	471	As native sendfile syscalls (as practically any non-POSIX interface hacked
303	C<$in_fh> than are written, and there is no way to find out how many	472	together in a hurry to improve benchmark numbers) tend to be rather buggy
304	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	473	on many systems, this implementation tries to work around some known bugs
305	provides the number of bytes written to C<$out_fh>. Only if the result	474	in Linux and FreeBSD kernels (probably others, too), but that might fail,
306	value equals C<$length> one can assume that C<$length> bytes have been	475	so you really really should check the return value of C<aio_sendfile> -
307	read.	476	fewre bytes than expected might have been transferred.
		477
308		478
309	=item aio_readahead $fh,$offset,$length, $callback->($retval)	479	=item aio_readahead $fh,$offset,$length, $callback->($retval)
310		480
311	C<aio_readahead> populates the page cache with data from a file so that	481	C<aio_readahead> populates the page cache with data from a file so that
312	subsequent reads from that file will not block on disk I/O. The C<$offset>	482	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
318	file. The current file offset of the file is left unchanged.	488	file. The current file offset of the file is left unchanged.
319		489
320	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	490	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
321	emulated by simply reading the data, which would have a similar effect.	491	emulated by simply reading the data, which would have a similar effect.
322		492
		493
323	=item aio_stat $fh_or_path, $callback->($status)	494	=item aio_stat $fh_or_path, $callback->($status)
324		495
325	=item aio_lstat $fh, $callback->($status)	496	=item aio_lstat $fh, $callback->($status)
326		497
327	Works like perl's C<stat> or C<lstat> in void context. The callback will	498	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
332	for an explanation.	503	for an explanation.
333		504
334	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	505	Currently, the stats are always 64-bit-stats, i.e. instead of returning an
335	error when stat'ing a large file, the results will be silently truncated	506	error when stat'ing a large file, the results will be silently truncated
336	unless perl itself is compiled with large file support.	507	unless perl itself is compiled with large file support.
		508
		509	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		510	following constants and functions (if not implemented, the constants will
		511	be C<0> and the functions will either C<croak> or fall back on traditional
		512	behaviour).
		513
		514	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		515	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		516	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
337		517
338	Example: Print the length of F</etc/passwd>:	518	Example: Print the length of F</etc/passwd>:
339		519
340	aio_stat "/etc/passwd", sub {	520	aio_stat "/etc/passwd", sub {
341	$_[0] and die "stat failed: $!";	521	$_[0] and die "stat failed: $!";
342	print "size is ", -s _, "\n";	522	print "size is ", -s _, "\n";
343	};	523	};
344		524
		525
		526	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		527
		528	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		529	whether a file handle or path was passed.
		530
		531	On success, the callback is passed a hash reference with the following
		532	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		533	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		534	is passed.
		535
		536	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		537	C<ST_NOSUID>.
		538
		539	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		540	their correct value when available, or to C<0> on systems that do
		541	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		542	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		543	C<ST_NODIRATIME> and C<ST_RELATIME>.
		544
		545	Example: stat C</wd> and dump out the data if successful.
		546
		547	aio_statvfs "/wd", sub {
		548	my $f = $_[0]
		549	or die "statvfs: $!";
		550
		551	use Data::Dumper;
		552	say Dumper $f;
		553	};
		554
		555	# result:
		556	{
		557	bsize => 1024,
		558	bfree => 4333064312,
		559	blocks => 10253828096,
		560	files => 2050765568,
		561	flag => 4096,
		562	favail => 2042092649,
		563	bavail => 4333064312,
		564	ffree => 2042092649,
		565	namemax => 255,
		566	frsize => 1024,
		567	fsid => 1810
		568	}
		569
		570
		571	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		572
		573	Works like perl's C<utime> function (including the special case of $atime
		574	and $mtime being undef). Fractional times are supported if the underlying
		575	syscalls support them.
		576
		577	When called with a pathname, uses utimes(2) if available, otherwise
		578	utime(2). If called on a file descriptor, uses futimes(2) if available,
		579	otherwise returns ENOSYS, so this is not portable.
		580
		581	Examples:
		582
		583	# set atime and mtime to current time (basically touch(1)):
		584	aio_utime "path", undef, undef;
		585	# set atime to current time and mtime to beginning of the epoch:
		586	aio_utime "path", time, undef; # undef==0
		587
		588
		589	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		590
		591	Works like perl's C<chown> function, except that C<undef> for either $uid
		592	or $gid is being interpreted as "do not change" (but -1 can also be used).
		593
		594	Examples:
		595
		596	# same as "chown root path" in the shell:
		597	aio_chown "path", 0, -1;
		598	# same as above:
		599	aio_chown "path", 0, undef;
		600
		601
		602	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		603
		604	Works like truncate(2) or ftruncate(2).
		605
		606
		607	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		608
		609	Works like perl's C<chmod> function.
		610
		611
345	=item aio_unlink $pathname, $callback->($status)	612	=item aio_unlink $pathname, $callback->($status)
346		613
347	Asynchronously unlink (delete) a file and call the callback with the	614	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	615	result code.
349		616
		617
		618	=item aio_mknod $path, $mode, $dev, $callback->($status)
		619
		620	[EXPERIMENTAL]
		621
		622	Asynchronously create a device node (or fifo). See mknod(2).
		623
		624	The only (POSIX-) portable way of calling this function is:
		625
		626	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		627
		628	See C<aio_stat> for info about some potentially helpful extra constants
		629	and functions.
		630
350	=item aio_link $srcpath, $dstpath, $callback->($status)	631	=item aio_link $srcpath, $dstpath, $callback->($status)
351		632
352	Asynchronously create a new link to the existing object at C<$srcpath> at	633	Asynchronously create a new link to the existing object at C<$srcpath> at
353	the path C<$dstpath> and call the callback with the result code.	634	the path C<$dstpath> and call the callback with the result code.
354		635
		636
355	=item aio_symlink $srcpath, $dstpath, $callback->($status)	637	=item aio_symlink $srcpath, $dstpath, $callback->($status)
356		638
357	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	639	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
358	the path C<$dstpath> and call the callback with the result code.	640	the path C<$dstpath> and call the callback with the result code.
359		641
		642
		643	=item aio_readlink $path, $callback->($link)
		644
		645	Asynchronously read the symlink specified by C<$path> and pass it to
		646	the callback. If an error occurs, nothing or undef gets passed to the
		647	callback.
		648
		649
		650	=item aio_realpath $path, $callback->($path)
		651
		652	Asynchronously make the path absolute and resolve any symlinks in
		653	C<$path>. The resulting path only consists of directories (Same as
		654	L<Cwd::realpath>).
		655
		656	This request can be used to get the absolute path of the current working
		657	directory by passing it a path of F<.> (a single dot).
		658
		659
360	=item aio_rename $srcpath, $dstpath, $callback->($status)	660	=item aio_rename $srcpath, $dstpath, $callback->($status)
361		661
362	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	662	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
363	rename(2) and call the callback with the result code.	663	rename(2) and call the callback with the result code.
364		664
		665
		666	=item aio_mkdir $pathname, $mode, $callback->($status)
		667
		668	Asynchronously mkdir (create) a directory and call the callback with
		669	the result code. C<$mode> will be modified by the umask at the time the
		670	request is executed, so do not change your umask.
		671
		672
365	=item aio_rmdir $pathname, $callback->($status)	673	=item aio_rmdir $pathname, $callback->($status)
366		674
367	Asynchronously rmdir (delete) a directory and call the callback with the	675	Asynchronously rmdir (delete) a directory and call the callback with the
368	result code.	676	result code.
		677
369		678
370	=item aio_readdir $pathname, $callback->($entries)	679	=item aio_readdir $pathname, $callback->($entries)
371		680
372	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	681	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
373	directory (i.e. opendir + readdir + closedir). The entries will not be	682	directory (i.e. opendir + readdir + closedir). The entries will not be
374	sorted, and will B<NOT> include the C<.> and C<..> entries.	683	sorted, and will B<NOT> include the C<.> and C<..> entries.
375		684
376	The callback a single argument which is either C<undef> or an array-ref	685	The callback is passed a single argument which is either C<undef> or an
377	with the filenames.	686	array-ref with the filenames.
		687
		688
		689	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		690
		691	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		692	behaviour and output format. In case of an error, C<$entries> will be
		693	C<undef>.
		694
		695	The flags are a combination of the following constants, ORed together (the
		696	flags will also be passed to the callback, possibly modified):
		697
		698	=over 4
		699
		700	=item IO::AIO::READDIR_DENTS
		701
		702	When this flag is off, then the callback gets an arrayref consisting of
		703	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		704	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		705	entry in more detail.
		706
		707	C<$name> is the name of the entry.
		708
		709	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		710
		711	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		712	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		713	C<IO::AIO::DT_WHT>.
		714
		715	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		716	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		717	scalars are read-only: you can not modify them.
		718
		719	C<$inode> is the inode number (which might not be exact on systems with 64
		720	bit inode numbers and 32 bit perls). This field has unspecified content on
		721	systems that do not deliver the inode information.
		722
		723	=item IO::AIO::READDIR_DIRS_FIRST
		724
		725	When this flag is set, then the names will be returned in an order where
		726	likely directories come first, in optimal stat order. This is useful when
		727	you need to quickly find directories, or you want to find all directories
		728	while avoiding to stat() each entry.
		729
		730	If the system returns type information in readdir, then this is used
		731	to find directories directly. Otherwise, likely directories are names
		732	beginning with ".", or otherwise names with no dots, of which names with
		733	short names are tried first.
		734
		735	=item IO::AIO::READDIR_STAT_ORDER
		736
		737	When this flag is set, then the names will be returned in an order
		738	suitable for stat()'ing each one. That is, when you plan to stat()
		739	all files in the given directory, then the returned order will likely
		740	be fastest.
		741
		742	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		743	the likely dirs come first, resulting in a less optimal stat order.
		744
		745	=item IO::AIO::READDIR_FOUND_UNKNOWN
		746
		747	This flag should not be set when calling C<aio_readdirx>. Instead, it
		748	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		749	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		750	C<$type>'s are known, which can be used to speed up some algorithms.
		751
		752	=back
		753
		754
		755	=item aio_load $path, $data, $callback->($status)
		756
		757	This is a composite request that tries to fully load the given file into
		758	memory. Status is the same as with aio_read.
		759
		760	=cut
		761
		762	sub aio_load($$;$) {
		763	my ($path, undef, $cb) = @_;
		764	my $data = \$_[1];
		765
		766	my $pri = aioreq_pri;
		767	my $grp = aio_group $cb;
		768
		769	aioreq_pri $pri;
		770	add $grp aio_open $path, O_RDONLY, 0, sub {
		771	my $fh = shift
		772	or return $grp->result (-1);
		773
		774	aioreq_pri $pri;
		775	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		776	$grp->result ($_[0]);
		777	};
		778	};
		779
		780	$grp
		781	}
		782
		783	=item aio_copy $srcpath, $dstpath, $callback->($status)
		784
		785	Try to copy the I<file> (directories not supported as either source or
		786	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		787	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		788
		789	This is a composite request that creates the destination file with
		790	mode 0200 and copies the contents of the source file into it using
		791	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		792	uid/gid, in that order.
		793
		794	If an error occurs, the partial destination file will be unlinked, if
		795	possible, except when setting atime, mtime, access mode and uid/gid, where
		796	errors are being ignored.
		797
		798	=cut
		799
		800	sub aio_copy($$;$) {
		801	my ($src, $dst, $cb) = @_;
		802
		803	my $pri = aioreq_pri;
		804	my $grp = aio_group $cb;
		805
		806	aioreq_pri $pri;
		807	add $grp aio_open $src, O_RDONLY, 0, sub {
		808	if (my $src_fh = $_[0]) {
		809	my @stat = stat $src_fh; # hmm, might block over nfs?
		810
		811	aioreq_pri $pri;
		812	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		813	if (my $dst_fh = $_[0]) {
		814	aioreq_pri $pri;
		815	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		816	if ($_[0] == $stat[7]) {
		817	$grp->result (0);
		818	close $src_fh;
		819
		820	my $ch = sub {
		821	aioreq_pri $pri;
		822	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		823	aioreq_pri $pri;
		824	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		825	aioreq_pri $pri;
		826	add $grp aio_close $dst_fh;
		827	}
		828	};
		829	};
		830
		831	aioreq_pri $pri;
		832	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		833	if ($_[0] < 0 && $! == ENOSYS) {
		834	aioreq_pri $pri;
		835	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		836	} else {
		837	$ch->();
		838	}
		839	};
		840	} else {
		841	$grp->result (-1);
		842	close $src_fh;
		843	close $dst_fh;
		844
		845	aioreq $pri;
		846	add $grp aio_unlink $dst;
		847	}
		848	};
		849	} else {
		850	$grp->result (-1);
		851	}
		852	},
		853
		854	} else {
		855	$grp->result (-1);
		856	}
		857	};
		858
		859	$grp
		860	}
		861
		862	=item aio_move $srcpath, $dstpath, $callback->($status)
		863
		864	Try to move the I<file> (directories not supported as either source or
		865	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		866	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		867
		868	This is a composite request that tries to rename(2) the file first; if
		869	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		870	that is successful, unlinks the C<$srcpath>.
		871
		872	=cut
		873
		874	sub aio_move($$;$) {
		875	my ($src, $dst, $cb) = @_;
		876
		877	my $pri = aioreq_pri;
		878	my $grp = aio_group $cb;
		879
		880	aioreq_pri $pri;
		881	add $grp aio_rename $src, $dst, sub {
		882	if ($_[0] && $! == EXDEV) {
		883	aioreq_pri $pri;
		884	add $grp aio_copy $src, $dst, sub {
		885	$grp->result ($_[0]);
		886
		887	unless ($_[0]) {
		888	aioreq_pri $pri;
		889	add $grp aio_unlink $src;
		890	}
		891	};
		892	} else {
		893	$grp->result ($_[0]);
		894	}
		895	};
		896
		897	$grp
		898	}
378		899
379	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	900	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
380		901
381	[EXPERIMENTAL due to internal aio_group use]
382
383	Scans a directory (similar to C<aio_readdir>) but additionally tries to	902	Scans a directory (similar to C<aio_readdir>) but additionally tries to
384	separate the entries of directory C<$path> into two sets of names, ones	903	efficiently separate the entries of directory C<$path> into two sets of
385	you can recurse into (directories or links to them), and ones you cannot	904	names, directories you can recurse into (directories), and ones you cannot
386	recurse into (everything else).	905	recurse into (everything else, including symlinks to directories).
387		906
388	C<aio_scandir> is a composite request that creates of many sub requests_	907	C<aio_scandir> is a composite request that creates of many sub requests_
389	C<$maxreq> specifies the maximum number of outstanding aio requests that	908	C<$maxreq> specifies the maximum number of outstanding aio requests that
390	this function generates. If it is C<< <= 0 >>, then a suitable default	909	this function generates. If it is C<< <= 0 >>, then a suitable default
391	will be chosen (currently 6).	910	will be chosen (currently 4).
392		911
393	On error, the callback is called without arguments, otherwise it receives	912	On error, the callback is called without arguments, otherwise it receives
394	two array-refs with path-relative entry names.	913	two array-refs with path-relative entry names.
395		914
396	Example:	915	Example:
…		…
403		922
404	Implementation notes.	923	Implementation notes.
405		924
406	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	925	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
407		926
		927	If readdir returns file type information, then this is used directly to
		928	find directories.
		929
408	After reading the directory, the modification time, size etc. of the	930	Otherwise, after reading the directory, the modification time, size etc.
409	directory before and after the readdir is checked, and if they match (and	931	of the directory before and after the readdir is checked, and if they
410	isn't the current time), the link count will be used to decide how many	932	match (and isn't the current time), the link count will be used to decide
411	entries are directories (if >= 2). Otherwise, no knowledge of the number	933	how many entries are directories (if >= 2). Otherwise, no knowledge of the
412	of subdirectories will be assumed.	934	number of subdirectories will be assumed.
413		935
414	Then entries will be sorted into likely directories (everything without	936	Then entries will be sorted into likely directories a non-initial dot
415	a non-initial dot currently) and likely non-directories (everything	937	currently) and likely non-directories (see C<aio_readdirx>). Then every
416	else). Then every entry plus an appended C</.> will be C<stat>'ed,	938	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
417	likely directories first. If that succeeds, it assumes that the entry	939	in order of their inode numbers. If that succeeds, it assumes that the
418	is a directory or a symlink to directory (which will be checked	940	entry is a directory or a symlink to directory (which will be checked
419	seperately). This is often faster than stat'ing the entry itself because	941	seperately). This is often faster than stat'ing the entry itself because
420	filesystems might detect the type of the entry without reading the inode	942	filesystems might detect the type of the entry without reading the inode
421	data (e.g. ext2fs filetype feature).	943	data (e.g. ext2fs filetype feature), even on systems that cannot return
		944	the filetype information on readdir.
422		945
423	If the known number of directories (link count - 2) has been reached, the	946	If the known number of directories (link count - 2) has been reached, the
424	rest of the entries is assumed to be non-directories.	947	rest of the entries is assumed to be non-directories.
425		948
426	This only works with certainty on POSIX (= UNIX) filesystems, which	949	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
430	as those tend to return 0 or 1 as link counts, which disables the	953	as those tend to return 0 or 1 as link counts, which disables the
431	directory counting heuristic.	954	directory counting heuristic.
432		955
433	=cut	956	=cut
434		957
435	sub aio_scandir($$$) {	958	sub aio_scandir($$;$) {
436	my ($path, $maxreq, $cb) = @_;	959	my ($path, $maxreq, $cb) = @_;
437		960
		961	my $pri = aioreq_pri;
		962
438	my $grp = aio_group $cb;	963	my $grp = aio_group $cb;
439		964
440	$maxreq = 6 if $maxreq <= 0;	965	$maxreq = 4 if $maxreq <= 0;
441		966
442	# stat once	967	# stat once
		968	aioreq_pri $pri;
443	add $grp aio_stat $path, sub {	969	add $grp aio_stat $path, sub {
444	return $grp->result () if $_[0];	970	return $grp->result () if $_[0];
445	my $now = time;	971	my $now = time;
446	my $hash1 = join ":", (stat _)[0,1,3,7,9];	972	my $hash1 = join ":", (stat _)[0,1,3,7,9];
447		973
448	# read the directory entries	974	# read the directory entries
		975	aioreq_pri $pri;
449	add $grp aio_readdir $path, sub {	976	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
450	my $entries = shift	977	my $entries = shift
451	or return $grp->result ();	978	or return $grp->result ();
452		979
453	# stat the dir another time	980	# stat the dir another time
		981	aioreq_pri $pri;
454	add $grp aio_stat $path, sub {	982	add $grp aio_stat $path, sub {
455	my $hash2 = join ":", (stat _)[0,1,3,7,9];	983	my $hash2 = join ":", (stat _)[0,1,3,7,9];
456		984
457	my $ndirs;	985	my $ndirs;
458		986
459	# take the slow route if anything looks fishy	987	# take the slow route if anything looks fishy
460	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	988	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
461	$ndirs = -1;	989	$ndirs = -1;
462	} else {	990	} else {
463	# if nlink == 2, we are finished	991	# if nlink == 2, we are finished
464	# on non-posix-fs's, we rely on nlink < 2	992	# for non-posix-fs's, we rely on nlink < 2
465	$ndirs = (stat _)[3] - 2	993	$ndirs = (stat _)[3] - 2
466	or return $grp->result ([], $entries);	994	or return $grp->result ([], $entries);
467	}	995	}
468		996
469	# sort into likely dirs and likely nondirs
470	# dirs == files without ".", short entries first
471	$entries = [map $_->[0],
472	sort { $b->[1] cmp $a->[1] }
473	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
474	@$entries];
475
476	my (@dirs, @nondirs);	997	my (@dirs, @nondirs);
477		998
478	my ($statcb, $schedcb);
479	my $nreq = 0;
480
481	my $statgrp = add $grp aio_group;	999	my $statgrp = add $grp aio_group sub {
		1000	$grp->result (\@dirs, \@nondirs);
		1001	};
482		1002
483	$schedcb = sub {	1003	limit $statgrp $maxreq;
484	if (@$entries) {	1004	feed $statgrp sub {
485	if ($nreq < $maxreq) {	1005	return unless @$entries;
486	my $ent = pop @$entries;	1006	my $entry = shift @$entries;
		1007
		1008	aioreq_pri $pri;
		1009	add $statgrp aio_stat "$path/$entry/.", sub {
		1010	if ($_[0] < 0) {
		1011	push @nondirs, $entry;
		1012	} else {
		1013	# need to check for real directory
		1014	aioreq_pri $pri;
		1015	add $statgrp aio_lstat "$path/$entry", sub {
		1016	if (-d _) {
		1017	push @dirs, $entry;
		1018
		1019	unless (--$ndirs) {
		1020	push @nondirs, @$entries;
		1021	feed $statgrp;
		1022	}
		1023	} else {
		1024	push @nondirs, $entry;
		1025	}
487	$nreq++;	1026	}
488	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
489	}	1027	}
490	} elsif (!$nreq) {
491	# finished
492	$statgrp->cancel;
493	undef $statcb;
494	undef $schedcb;
495	$grp->result (\@dirs, \@nondirs);
496	}	1028	};
497	};	1029	};
498	$statcb = sub {
499	my ($status, $entry) = @_;
500
501	if ($status < 0) {
502	$nreq--;
503	push @nondirs, $entry;
504	&$schedcb;
505	} else {
506	# need to check for real directory
507	add $grp aio_lstat "$path/$entry", sub {
508	$nreq--;
509
510	if (-d _) {
511	push @dirs, $entry;
512
513	if (!--$ndirs) {
514	push @nondirs, @$entries;
515	$entries = [];
516	}
517	} else {
518	push @nondirs, $entry;
519	}
520
521	&$schedcb;
522	}
523	}
524	};
525
526	&$schedcb while @$entries && $nreq < $maxreq;
527	};	1030	};
528	};	1031	};
529	};	1032	};
530		1033
531	$grp	1034	$grp
532	}	1035	}
533		1036
		1037	=item aio_rmtree $path, $callback->($status)
		1038
		1039	Delete a directory tree starting (and including) C<$path>, return the
		1040	status of the final C<rmdir> only. This is a composite request that
		1041	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		1042	everything else.
		1043
		1044	=cut
		1045
		1046	sub aio_rmtree;
		1047	sub aio_rmtree($;$) {
		1048	my ($path, $cb) = @_;
		1049
		1050	my $pri = aioreq_pri;
		1051	my $grp = aio_group $cb;
		1052
		1053	aioreq_pri $pri;
		1054	add $grp aio_scandir $path, 0, sub {
		1055	my ($dirs, $nondirs) = @_;
		1056
		1057	my $dirgrp = aio_group sub {
		1058	add $grp aio_rmdir $path, sub {
		1059	$grp->result ($_[0]);
		1060	};
		1061	};
		1062
		1063	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1064	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1065
		1066	add $grp $dirgrp;
		1067	};
		1068
		1069	$grp
		1070	}
		1071
		1072	=item aio_sync $callback->($status)
		1073
		1074	Asynchronously call sync and call the callback when finished.
		1075
534	=item aio_fsync $fh, $callback->($status)	1076	=item aio_fsync $fh, $callback->($status)
535		1077
536	Asynchronously call fsync on the given filehandle and call the callback	1078	Asynchronously call fsync on the given filehandle and call the callback
537	with the fsync result code.	1079	with the fsync result code.
538		1080
…		…
542	callback with the fdatasync result code.	1084	callback with the fdatasync result code.
543		1085
544	If this call isn't available because your OS lacks it or it couldn't be	1086	If this call isn't available because your OS lacks it or it couldn't be
545	detected, it will be emulated by calling C<fsync> instead.	1087	detected, it will be emulated by calling C<fsync> instead.
546		1088
		1089	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1090
		1091	Sync the data portion of the file specified by C<$offset> and C<$length>
		1092	to disk (but NOT the metadata), by calling the Linux-specific
		1093	sync_file_range call. If sync_file_range is not available or it returns
		1094	ENOSYS, then fdatasync or fsync is being substituted.
		1095
		1096	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1097	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1098	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1099	manpage for details.
		1100
		1101	=item aio_pathsync $path, $callback->($status)
		1102
		1103	This request tries to open, fsync and close the given path. This is a
		1104	composite request intended to sync directories after directory operations
		1105	(E.g. rename). This might not work on all operating systems or have any
		1106	specific effect, but usually it makes sure that directory changes get
		1107	written to disc. It works for anything that can be opened for read-only,
		1108	not just directories.
		1109
		1110	Future versions of this function might fall back to other methods when
		1111	C<fsync> on the directory fails (such as calling C<sync>).
		1112
		1113	Passes C<0> when everything went ok, and C<-1> on error.
		1114
		1115	=cut
		1116
		1117	sub aio_pathsync($;$) {
		1118	my ($path, $cb) = @_;
		1119
		1120	my $pri = aioreq_pri;
		1121	my $grp = aio_group $cb;
		1122
		1123	aioreq_pri $pri;
		1124	add $grp aio_open $path, O_RDONLY, 0, sub {
		1125	my ($fh) = @_;
		1126	if ($fh) {
		1127	aioreq_pri $pri;
		1128	add $grp aio_fsync $fh, sub {
		1129	$grp->result ($_[0]);
		1130
		1131	aioreq_pri $pri;
		1132	add $grp aio_close $fh;
		1133	};
		1134	} else {
		1135	$grp->result (-1);
		1136	}
		1137	};
		1138
		1139	$grp
		1140	}
		1141
		1142	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1143
		1144	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1145	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1146	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1147	scalar must only be modified in-place while an aio operation is pending on
		1148	it).
		1149
		1150	It calls the C<msync> function of your OS, if available, with the memory
		1151	area starting at C<$offset> in the string and ending C<$length> bytes
		1152	later. If C<$length> is negative, counts from the end, and if C<$length>
		1153	is C<undef>, then it goes till the end of the string. The flags can be
		1154	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1155	C<IO::AIO::MS_SYNC>.
		1156
		1157	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1158
		1159	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1160	scalars.
		1161
		1162	It touches (reads or writes) all memory pages in the specified
		1163	range inside the scalar. All caveats and parameters are the same
		1164	as for C<aio_msync>, above, except for flags, which must be either
		1165	C<0> (which reads all pages and ensures they are instantiated) or
		1166	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1167	writing an octet from it, which dirties the page).
		1168
		1169	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1170
		1171	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1172	scalars.
		1173
		1174	It reads in all the pages of the underlying storage into memory (if any)
		1175	and locks them, so they are not getting swapped/paged out or removed.
		1176
		1177	If C<$length> is undefined, then the scalar will be locked till the end.
		1178
		1179	On systems that do not implement C<mlock>, this function returns C<-1>
		1180	and sets errno to C<ENOSYS>.
		1181
		1182	Note that the corresponding C<munlock> is synchronous and is
		1183	documented under L<MISCELLANEOUS FUNCTIONS>.
		1184
		1185	Example: open a file, mmap and mlock it - both will be undone when
		1186	C<$data> gets destroyed.
		1187
		1188	open my $fh, "<", $path or die "$path: $!";
		1189	my $data;
		1190	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1191	aio_mlock $data; # mlock in background
		1192
		1193	=item aio_mlockall $flags, $callback->($status)
		1194
		1195	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1196	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1197
		1198	On systems that do not implement C<mlockall>, this function returns C<-1>
		1199	and sets errno to C<ENOSYS>.
		1200
		1201	Note that the corresponding C<munlockall> is synchronous and is
		1202	documented under L<MISCELLANEOUS FUNCTIONS>.
		1203
		1204	Example: asynchronously lock all current and future pages into memory.
		1205
		1206	aio_mlockall IO::AIO::MCL_FUTURE;
		1207
547	=item aio_group $callback->(...)	1208	=item aio_group $callback->(...)
548
549	[EXPERIMENTAL]
550		1209
551	This is a very special aio request: Instead of doing something, it is a	1210	This is a very special aio request: Instead of doing something, it is a
552	container for other aio requests, which is useful if you want to bundle	1211	container for other aio requests, which is useful if you want to bundle
553	many requests into a single, composite, request.	1212	many requests into a single, composite, request with a definite callback
		1213	and the ability to cancel the whole request with its subrequests.
554		1214
555	Returns an object of class L<IO::AIO::GRP>. See its documentation below	1215	Returns an object of class L<IO::AIO::GRP>. See its documentation below
556	for more info.	1216	for more info.
557		1217
558	Example:	1218	Example:
…		…
577	phase and still requires a worker thread. Thus, the callback will not	1237	phase and still requires a worker thread. Thus, the callback will not
578	be executed immediately but only after other requests in the queue have	1238	be executed immediately but only after other requests in the queue have
579	entered their execution phase. This can be used to measure request	1239	entered their execution phase. This can be used to measure request
580	latency.	1240	latency.
581		1241
582	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED*	1242	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
583		1243
584	Mainly used for debugging and benchmarking, this aio request puts one of	1244	Mainly used for debugging and benchmarking, this aio request puts one of
585	the request workers to sleep for the given time.	1245	the request workers to sleep for the given time.
586		1246
587	While it is theoretically handy to have simple I/O scheduling requests	1247	While it is theoretically handy to have simple I/O scheduling requests
588	like sleep and file handle readable/writable, the overhead this creates	1248	like sleep and file handle readable/writable, the overhead this creates is
589	is immense, so do not use this function except to put your application	1249	immense (it blocks a thread for a long time) so do not use this function
590	under artificial I/O pressure.	1250	except to put your application under artificial I/O pressure.
591		1251
592	=back	1252	=back
593		1253
594	=head2 IO::AIO::REQ CLASS	1254	=head2 IO::AIO::REQ CLASS
595		1255
596	All non-aggregate C<aio_*> functions return an object of this class when	1256	All non-aggregate C<aio_*> functions return an object of this class when
597	called in non-void context.	1257	called in non-void context.
598
599	A request always moves through the following five states in its lifetime,
600	in order: B<ready> (request has been created, but has not been executed
601	yet), B<execute> (request is currently being executed), B<pending>
602	(request has been executed but callback has not been called yet),
603	B<result> (results are being processed synchronously, includes calling the
604	callback) and B<done> (request has reached the end of its lifetime and
605	holds no resources anymore).
606		1258
607	=over 4	1259	=over 4
608		1260
609	=item cancel $req	1261	=item cancel $req
610		1262
611	Cancels the request, if possible. Has the effect of skipping execution	1263	Cancels the request, if possible. Has the effect of skipping execution
612	when entering the B<execute> state and skipping calling the callback when	1264	when entering the B<execute> state and skipping calling the callback when
613	entering the the B<result> state, but will leave the request otherwise	1265	entering the the B<result> state, but will leave the request otherwise
614	untouched. That means that requests that currently execute will not be	1266	untouched (with the exception of readdir). That means that requests that
615	stopped and resources held by the request will not be freed prematurely.	1267	currently execute will not be stopped and resources held by the request
		1268	will not be freed prematurely.
616		1269
617	=item cb $req $callback->(...)	1270	=item cb $req $callback->(...)
618		1271
619	Replace (or simply set) the callback registered to the request.	1272	Replace (or simply set) the callback registered to the request.
620		1273
…		…
664	=item * They can also can also be added to other IO::AIO::GRP objects.	1317	=item * They can also can also be added to other IO::AIO::GRP objects.
665		1318
666	=item * You must not add requests to a group from within the group callback (or	1319	=item * You must not add requests to a group from within the group callback (or
667	any later time).	1320	any later time).
668		1321
669	=item * This does not harmonise well with C<max_outstanding>, so best do
670	not combine C<aio_group> with it. Groups and feeders are recommended for
671	this kind of concurrency-limiting.
672
673	=back	1322	=back
674		1323
675	Their lifetime, simplified, looks like this: when they are empty, they	1324	Their lifetime, simplified, looks like this: when they are empty, they
676	will finish very quickly. If they contain only requests that are in the	1325	will finish very quickly. If they contain only requests that are in the
677	C<done> state, they will also finish. Otherwise they will continue to	1326	C<done> state, they will also finish. Otherwise they will continue to
678	exist.	1327	exist.
679		1328
680	That means after creating a group you have some time to add requests. And	1329	That means after creating a group you have some time to add requests
681	in the callbacks of those requests, you can add further requests to the	1330	(precisely before the callback has been invoked, which is only done within
682	group. And only when all those requests have finished will the the group	1331	the C<poll_cb>). And in the callbacks of those requests, you can add
683	itself finish.	1332	further requests to the group. And only when all those requests have
		1333	finished will the the group itself finish.
684		1334
685	=over 4	1335	=over 4
686		1336
687	=item add $grp ...	1337	=item add $grp ...
688		1338
…		…
692	be added, including other groups, as long as you do not create circular	1342	be added, including other groups, as long as you do not create circular
693	dependencies.	1343	dependencies.
694		1344
695	Returns all its arguments.	1345	Returns all its arguments.
696		1346
		1347	=item $grp->cancel_subs
		1348
		1349	Cancel all subrequests and clears any feeder, but not the group request
		1350	itself. Useful when you queued a lot of events but got a result early.
		1351
		1352	The group request will finish normally (you cannot add requests to the
		1353	group).
		1354
697	=item $grp->result (...)	1355	=item $grp->result (...)
698		1356
699	Set the result value(s) that will be passed to the group callback when all	1357	Set the result value(s) that will be passed to the group callback when all
700	subrequests have finished. By default, no argument will be passed.	1358	subrequests have finished and set the groups errno to the current value
		1359	of errno (just like calling C<errno> without an error number). By default,
		1360	no argument will be passed and errno is zero.
		1361
		1362	=item $grp->errno ([$errno])
		1363
		1364	Sets the group errno value to C<$errno>, or the current value of errno
		1365	when the argument is missing.
		1366
		1367	Every aio request has an associated errno value that is restored when
		1368	the callback is invoked. This method lets you change this value from its
		1369	default (0).
		1370
		1371	Calling C<result> will also set errno, so make sure you either set C<$!>
		1372	before the call to C<result>, or call c<errno> after it.
701		1373
702	=item feed $grp $callback->($grp)	1374	=item feed $grp $callback->($grp)
703
704	[VERY EXPERIMENTAL]
705		1375
706	Sets a feeder/generator on this group: every group can have an attached	1376	Sets a feeder/generator on this group: every group can have an attached
707	generator that generates requests if idle. The idea behind this is that,	1377	generator that generates requests if idle. The idea behind this is that,
708	although you could just queue as many requests as you want in a group,	1378	although you could just queue as many requests as you want in a group,
709	this might starve other requests for a potentially long time. For	1379	this might starve other requests for a potentially long time. For example,
710	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1380	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
711	requests, delaying any later requests for a long time.	1381	delaying any later requests for a long time.
712		1382
713	To avoid this, and allow incremental generation of requests, you can	1383	To avoid this, and allow incremental generation of requests, you can
714	instead a group and set a feeder on it that generates those requests. The	1384	instead a group and set a feeder on it that generates those requests. The
715	feed callback will be called whenever there are few enough (see C<limit>,	1385	feed callback will be called whenever there are few enough (see C<limit>,
716	below) requests active in the group itself and is expected to queue more	1386	below) requests active in the group itself and is expected to queue more
…		…
720	not impose any limits).	1390	not impose any limits).
721		1391
722	If the feed does not queue more requests when called, it will be	1392	If the feed does not queue more requests when called, it will be
723	automatically removed from the group.	1393	automatically removed from the group.
724		1394
725	If the feed limit is C<0>, it will be set to C<2> automatically.	1395	If the feed limit is C<0> when this method is called, it will be set to
		1396	C<2> automatically.
726		1397
727	Example:	1398	Example:
728		1399
729	# stat all files in @files, but only ever use four aio requests concurrently:	1400	# stat all files in @files, but only ever use four aio requests concurrently:
730		1401
…		…
742	Sets the feeder limit for the group: The feeder will be called whenever	1413	Sets the feeder limit for the group: The feeder will be called whenever
743	the group contains less than this many requests.	1414	the group contains less than this many requests.
744		1415
745	Setting the limit to C<0> will pause the feeding process.	1416	Setting the limit to C<0> will pause the feeding process.
746		1417
		1418	The default value for the limit is C<0>, but note that setting a feeder
		1419	automatically bumps it up to C<2>.
		1420
747	=back	1421	=back
748		1422
749	=head2 SUPPORT FUNCTIONS	1423	=head2 SUPPORT FUNCTIONS
750		1424
		1425	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1426
751	=over 4	1427	=over 4
752		1428
753	=item $fileno = IO::AIO::poll_fileno	1429	=item $fileno = IO::AIO::poll_fileno
754		1430
755	Return the I<request result pipe file descriptor>. This filehandle must be	1431	Return the I<request result pipe file descriptor>. This filehandle must be
756	polled for reading by some mechanism outside this module (e.g. Event or	1432	polled for reading by some mechanism outside this module (e.g. EV, Glib,
757	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1433	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
758	to call C<poll_cb> to check the results.	1434	you have to call C<poll_cb> to check the results.
759		1435
760	See C<poll_cb> for an example.	1436	See C<poll_cb> for an example.
761		1437
762	=item IO::AIO::poll_cb	1438	=item IO::AIO::poll_cb
763		1439
764	Process all outstanding events on the result pipe. You have to call this	1440	Process some outstanding events on the result pipe. You have to call
765	regularly. Returns the number of events processed. Returns immediately	1441	this regularly. Returns C<0> if all events could be processed (or there
766	when no events are outstanding.	1442	were no events to process), or C<-1> if it returned earlier for whatever
		1443	reason. Returns immediately when no events are outstanding. The amount of
		1444	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1445	C<IO::AIO::max_poll_time>.
		1446
		1447	If not all requests were processed for whatever reason, the filehandle
		1448	will still be ready when C<poll_cb> returns, so normally you don't have to
		1449	do anything special to have it called later.
		1450
		1451	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1452	ready, it can be beneficial to call this function from loops which submit
		1453	a lot of requests, to make sure the results get processed when they become
		1454	available and not just when the loop is finished and the event loop takes
		1455	over again. This function returns very fast when there are no outstanding
		1456	requests.
767		1457
768	Example: Install an Event watcher that automatically calls	1458	Example: Install an Event watcher that automatically calls
769	IO::AIO::poll_cb with high priority:	1459	IO::AIO::poll_cb with high priority (more examples can be found in the
		1460	SYNOPSIS section, at the top of this document):
770		1461
771	Event->io (fd => IO::AIO::poll_fileno,	1462	Event->io (fd => IO::AIO::poll_fileno,
772	poll => 'r', async => 1,	1463	poll => 'r', async => 1,
773	cb => \&IO::AIO::poll_cb);	1464	cb => \&IO::AIO::poll_cb);
774		1465
775	=item IO::AIO::poll_wait	1466	=item IO::AIO::poll_wait
776		1467
		1468	If there are any outstanding requests and none of them in the result
777	Wait till the result filehandle becomes ready for reading (simply does a	1469	phase, wait till the result filehandle becomes ready for reading (simply
778	C<select> on the filehandle. This is useful if you want to synchronously wait	1470	does a C<select> on the filehandle. This is useful if you want to
779	for some requests to finish).	1471	synchronously wait for some requests to finish).
780		1472
781	See C<nreqs> for an example.	1473	See C<nreqs> for an example.
782		1474
		1475	=item IO::AIO::poll
		1476
		1477	Waits until some requests have been handled.
		1478
		1479	Returns the number of requests processed, but is otherwise strictly
		1480	equivalent to:
		1481
		1482	IO::AIO::poll_wait, IO::AIO::poll_cb
		1483
783	=item IO::AIO::nreqs	1484	=item IO::AIO::flush
784		1485
785	Returns the number of requests currently outstanding (i.e. for which their	1486	Wait till all outstanding AIO requests have been handled.
786	callback has not been invoked yet).
787		1487
788	Example: wait till there are no outstanding requests anymore:	1488	Strictly equivalent to:
789		1489
790	IO::AIO::poll_wait, IO::AIO::poll_cb	1490	IO::AIO::poll_wait, IO::AIO::poll_cb
791	while IO::AIO::nreqs;	1491	while IO::AIO::nreqs;
792		1492
793	=item IO::AIO::flush	1493	=item IO::AIO::max_poll_reqs $nreqs
794		1494
795	Wait till all outstanding AIO requests have been handled.	1495	=item IO::AIO::max_poll_time $seconds
796		1496
797	Strictly equivalent to:	1497	These set the maximum number of requests (default C<0>, meaning infinity)
		1498	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1499	the maximum amount of time (default C<0>, meaning infinity) spent in
		1500	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1501	of time C<poll_cb> is allowed to use).
798		1502
799	IO::AIO::poll_wait, IO::AIO::poll_cb	1503	Setting C<max_poll_time> to a non-zero value creates an overhead of one
800	while IO::AIO::nreqs;	1504	syscall per request processed, which is not normally a problem unless your
		1505	callbacks are really really fast or your OS is really really slow (I am
		1506	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
801		1507
802	=item IO::AIO::poll	1508	Setting these is useful if you want to ensure some level of
		1509	interactiveness when perl is not fast enough to process all requests in
		1510	time.
803		1511
804	Waits until some requests have been handled.	1512	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
805		1513
806	Strictly equivalent to:	1514	Example: Install an Event watcher that automatically calls
		1515	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1516	program get the CPU sometimes even under high AIO load.
807		1517
808	IO::AIO::poll_wait, IO::AIO::poll_cb	1518	# try not to spend much more than 0.1s in poll_cb
809	if IO::AIO::nreqs;	1519	IO::AIO::max_poll_time 0.1;
		1520
		1521	# use a low priority so other tasks have priority
		1522	Event->io (fd => IO::AIO::poll_fileno,
		1523	poll => 'r', nice => 1,
		1524	cb => &IO::AIO::poll_cb);
		1525
		1526	=back
		1527
		1528	=head3 CONTROLLING THE NUMBER OF THREADS
		1529
		1530	=over
810		1531
811	=item IO::AIO::min_parallel $nthreads	1532	=item IO::AIO::min_parallel $nthreads
812		1533
813	Set the minimum number of AIO threads to C<$nthreads>. The current	1534	Set the minimum number of AIO threads to C<$nthreads>. The current
814	default is C<8>, which means eight asynchronous operations can execute	1535	default is C<8>, which means eight asynchronous operations can execute
815	concurrently at any one time (the number of outstanding requests,	1536	concurrently at any one time (the number of outstanding requests,
816	however, is unlimited).	1537	however, is unlimited).
817		1538
818	IO::AIO starts threads only on demand, when an AIO request is queued and	1539	IO::AIO starts threads only on demand, when an AIO request is queued and
819	no free thread exists.	1540	no free thread exists. Please note that queueing up a hundred requests can
		1541	create demand for a hundred threads, even if it turns out that everything
		1542	is in the cache and could have been processed faster by a single thread.
820		1543
821	It is recommended to keep the number of threads relatively low, as some	1544	It is recommended to keep the number of threads relatively low, as some
822	Linux kernel versions will scale negatively with the number of threads	1545	Linux kernel versions will scale negatively with the number of threads
823	(higher parallelity => MUCH higher latency). With current Linux 2.6	1546	(higher parallelity => MUCH higher latency). With current Linux 2.6
824	versions, 4-32 threads should be fine.	1547	versions, 4-32 threads should be fine.
…		…
838	This module automatically runs C<max_parallel 0> at program end, to ensure	1561	This module automatically runs C<max_parallel 0> at program end, to ensure
839	that all threads are killed and that there are no outstanding requests.	1562	that all threads are killed and that there are no outstanding requests.
840		1563
841	Under normal circumstances you don't need to call this function.	1564	Under normal circumstances you don't need to call this function.
842		1565
		1566	=item IO::AIO::max_idle $nthreads
		1567
		1568	Limit the number of threads (default: 4) that are allowed to idle
		1569	(i.e., threads that did not get a request to process within the idle
		1570	timeout (default: 10 seconds). That means if a thread becomes idle while
		1571	C<$nthreads> other threads are also idle, it will free its resources and
		1572	exit.
		1573
		1574	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1575	to allow for extremely high load situations, but want to free resources
		1576	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1577
		1578	The default is probably ok in most situations, especially if thread
		1579	creation is fast. If thread creation is very slow on your system you might
		1580	want to use larger values.
		1581
		1582	=item IO::AIO::idle_timeout $seconds
		1583
		1584	Sets the minimum idle timeout (default 10) after which worker threads are
		1585	allowed to exit. SEe C<IO::AIO::max_idle>.
		1586
843	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1587	=item IO::AIO::max_outstanding $maxreqs
844		1588
845	[DEPRECATED]
846
847	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1589	Sets the maximum number of outstanding requests to C<$nreqs>. If
848	try to queue up more than this number of requests, the caller will block until	1590	you do queue up more than this number of requests, the next call to
849	some requests have been handled.	1591	C<IO::AIO::poll_cb> (and other functions calling C<poll_cb>, such as
		1592	C<IO::AIO::flush> or C<IO::AIO::poll>) will block until the limit is no
		1593	longer exceeded.
850		1594
851	The default is very large, so normally there is no practical limit. If you	1595	In other words, this setting does not enforce a queue limit, but can be
852	queue up many requests in a loop it often improves speed if you set	1596	used to make poll functions block if the limit is exceeded.
853	this to a relatively low number, such as C<100>.
854		1597
855	This function does not work well together with C<aio_group>'s, and their	1598	This is a very bad function to use in interactive programs because it
856	feeder interface is better suited to limiting concurrency, so do not use	1599	blocks, and a bad way to reduce concurrency because it is inexact: Better
857	this function.	1600	use an C<aio_group> together with a feed callback.
858		1601
859	Under normal circumstances you don't need to call this function.	1602	It's main use is in scripts without an event loop - when you want to stat
		1603	a lot of files, you can write somehting like this:
		1604
		1605	IO::AIO::max_outstanding 32;
		1606
		1607	for my $path (...) {
		1608	aio_stat $path , ...;
		1609	IO::AIO::poll_cb;
		1610	}
		1611
		1612	IO::AIO::flush;
		1613
		1614	The call to C<poll_cb> inside the loop will normally return instantly, but
		1615	as soon as more thna C<32> reqeusts are in-flight, it will block until
		1616	some requests have been handled. This keeps the loop from pushing a large
		1617	number of C<aio_stat> requests onto the queue.
		1618
		1619	The default value for C<max_outstanding> is very large, so there is no
		1620	practical limit on the number of outstanding requests.
860		1621
861	=back	1622	=back
862		1623
		1624	=head3 STATISTICAL INFORMATION
		1625
		1626	=over
		1627
		1628	=item IO::AIO::nreqs
		1629
		1630	Returns the number of requests currently in the ready, execute or pending
		1631	states (i.e. for which their callback has not been invoked yet).
		1632
		1633	Example: wait till there are no outstanding requests anymore:
		1634
		1635	IO::AIO::poll_wait, IO::AIO::poll_cb
		1636	while IO::AIO::nreqs;
		1637
		1638	=item IO::AIO::nready
		1639
		1640	Returns the number of requests currently in the ready state (not yet
		1641	executed).
		1642
		1643	=item IO::AIO::npending
		1644
		1645	Returns the number of requests currently in the pending state (executed,
		1646	but not yet processed by poll_cb).
		1647
		1648	=back
		1649
		1650	=head3 MISCELLANEOUS FUNCTIONS
		1651
		1652	IO::AIO implements some functions that might be useful, but are not
		1653	asynchronous.
		1654
		1655	=over 4
		1656
		1657	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1658
		1659	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1660	but is blocking (this makes most sense if you know the input data is
		1661	likely cached already and the output filehandle is set to non-blocking
		1662	operations).
		1663
		1664	Returns the number of bytes copied, or C<-1> on error.
		1665
		1666	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1667
		1668	Simply calls the C<posix_fadvise> function (see its
		1669	manpage for details). The following advice constants are
		1670	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1671	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1672	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1673
		1674	On systems that do not implement C<posix_fadvise>, this function returns
		1675	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1676
		1677	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1678
		1679	Simply calls the C<posix_madvise> function (see its
		1680	manpage for details). The following advice constants are
		1681	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1682	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1683
		1684	On systems that do not implement C<posix_madvise>, this function returns
		1685	ENOSYS, otherwise the return value of C<posix_madvise>.
		1686
		1687	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1688
		1689	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1690	$scalar (see its manpage for details). The following protect
		1691	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1692	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1693
		1694	On systems that do not implement C<mprotect>, this function returns
		1695	ENOSYS, otherwise the return value of C<mprotect>.
		1696
		1697	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1698
		1699	Memory-maps a file (or anonymous memory range) and attaches it to the
		1700	given C<$scalar>, which will act like a string scalar.
		1701
		1702	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1703	change the string length, and most read-only operations such as copying it
		1704	or searching it with regexes and so on.
		1705
		1706	Anything else is unsafe and will, at best, result in memory leaks.
		1707
		1708	The memory map associated with the C<$scalar> is automatically removed
		1709	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1710	C<IO::AIO::munmap> functions are called.
		1711
		1712	This calls the C<mmap>(2) function internally. See your system's manual
		1713	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1714
		1715	The C<$length> must be larger than zero and smaller than the actual
		1716	filesize.
		1717
		1718	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1719	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1720
		1721	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1722	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1723	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1724	(which is set to C<MAP_ANON> if your system only provides this
		1725	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1726	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1727	C<IO::AIO::MAP_NONBLOCK>
		1728
		1729	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1730
		1731	C<$offset> is the offset from the start of the file - it generally must be
		1732	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1733
		1734	Example:
		1735
		1736	use Digest::MD5;
		1737	use IO::AIO;
		1738
		1739	open my $fh, "<verybigfile"
		1740	or die "$!";
		1741
		1742	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1743	or die "verybigfile: $!";
		1744
		1745	my $fast_md5 = md5 $data;
		1746
		1747	=item IO::AIO::munmap $scalar
		1748
		1749	Removes a previous mmap and undefines the C<$scalar>.
		1750
		1751	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1752
		1753	Calls the C<munlock> function, undoing the effects of a previous
		1754	C<aio_mlock> call (see its description for details).
		1755
		1756	=item IO::AIO::munlockall
		1757
		1758	Calls the C<munlockall> function.
		1759
		1760	On systems that do not implement C<munlockall>, this function returns
		1761	ENOSYS, otherwise the return value of C<munlockall>.
		1762
		1763	=back
		1764
863	=cut	1765	=cut
864		1766
865	# support function to convert a fd into a perl filehandle
866	sub _fd2fh {
867	return undef if $_[0] < 0;
868
869	# try to generate nice filehandles
870	my $sym = "IO::AIO::fd#$_[0]";
871	local *$sym;
872
873	open *$sym, "+<&=$_[0]" # usually works under any unix
874	or open *$sym, "<&=$_[0]" # cygwin needs this
875	or open *$sym, ">&=$_[0]" # or this
876	or return undef;
877
878	*$sym
879	}
880
881	min_parallel 8;	1767	min_parallel 8;
882		1768
883	END {	1769	END { flush }
884	max_parallel 0;
885	}
886		1770
887	1;	1771	1;
888		1772
		1773	=head1 EVENT LOOP INTEGRATION
		1774
		1775	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1776	automatically into many event loops:
		1777
		1778	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1779	use AnyEvent::AIO;
		1780
		1781	You can also integrate IO::AIO manually into many event loops, here are
		1782	some examples of how to do this:
		1783
		1784	# EV integration
		1785	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1786
		1787	# Event integration
		1788	Event->io (fd => IO::AIO::poll_fileno,
		1789	poll => 'r',
		1790	cb => \&IO::AIO::poll_cb);
		1791
		1792	# Glib/Gtk2 integration
		1793	add_watch Glib::IO IO::AIO::poll_fileno,
		1794	in => sub { IO::AIO::poll_cb; 1 };
		1795
		1796	# Tk integration
		1797	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1798	readable => \&IO::AIO::poll_cb);
		1799
		1800	# Danga::Socket integration
		1801	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1802	\&IO::AIO::poll_cb);
		1803
889	=head2 FORK BEHAVIOUR	1804	=head2 FORK BEHAVIOUR
890		1805
891	This module should do "the right thing" when the process using it forks:	1806	Usage of pthreads in a program changes the semantics of fork
		1807	considerably. Specifically, only async-safe functions can be called after
		1808	fork. Perl doesn't know about this, so in general, you cannot call fork
		1809	with defined behaviour in perl. IO::AIO uses pthreads, so this applies,
		1810	but many other extensions and (for inexplicable reasons) perl itself often
		1811	is linked against pthreads, so this limitation applies.
892		1812
893	Before the fork, IO::AIO enters a quiescent state where no requests	1813	Some operating systems have extensions that allow safe use of fork, and
894	can be added in other threads and no results will be processed. After	1814	this module should do "the right thing" on those, and tries on others. At
895	the fork the parent simply leaves the quiescent state and continues	1815	the time of this writing (2011) only GNU/Linux supports these extensions
896	request/result processing, while the child clears the request/result	1816	to POSIX.
897	queue (so the requests started before the fork will only be handled in
898	the parent). Threads will be started on demand until the limit ste in the
899	parent process has been reached again.
900
901	In short: the parent will, after a short pause, continue as if fork had
902	not been called, while the child will act as if IO::AIO has not been used
903	yet.
904		1817
905	=head2 MEMORY USAGE	1818	=head2 MEMORY USAGE
906		1819
		1820	Per-request usage:
		1821
907	Each aio request uses - depending on your architecture - around 128 bytes	1822	Each aio request uses - depending on your architecture - around 100-200
908	of memory. In addition, stat requests need a stat buffer (possibly a few	1823	bytes of memory. In addition, stat requests need a stat buffer (possibly
909	hundred bytes). Perl scalars and other data passed into aio requests will	1824	a few hundred bytes), readdir requires a result buffer and so on. Perl
910	also be locked.	1825	scalars and other data passed into aio requests will also be locked and
		1826	will consume memory till the request has entered the done state.
911		1827
912	This is now awfully much, so queuing lots of requests is not usually a	1828	This is not awfully much, so queuing lots of requests is not usually a
913	problem.	1829	problem.
914		1830
915	Each thread needs a stack area which is usually around 16k, sometimes much	1831	Per-thread usage:
916	larger, depending on the OS.	1832
		1833	In the execution phase, some aio requests require more memory for
		1834	temporary buffers, and each thread requires a stack and other data
		1835	structures (usually around 16k-128k, depending on the OS).
		1836
		1837	=head1 KNOWN BUGS
		1838
		1839	Known bugs will be fixed in the next release.
917		1840
918	=head1 SEE ALSO	1841	=head1 SEE ALSO
919		1842
920	L<Coro::AIO>.	1843	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1844	more natural syntax.
921		1845
922	=head1 AUTHOR	1846	=head1 AUTHOR
923		1847
924	Marc Lehmann <schmorp@schmorp.de>	1848	Marc Lehmann <schmorp@schmorp.de>
925	http://home.schmorp.de/	1849	http://home.schmorp.de/

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