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Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.194 by root, Fri May 27 00:44:49 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 = '3.9';
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_sync aio_fsync
		178	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		179	aio_rename aio_link aio_move aio_copy aio_group
		180	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		181	aio_chmod aio_utime aio_truncate
		182	aio_msync aio_mtouch aio_mlock aio_mlockall
85	aio_group aio_nop);	183	aio_statvfs);
		184
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	185	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	186	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	187	min_parallel max_parallel max_idle idle_timeout
		188	nreqs nready npending nthreads
		189	max_poll_time max_poll_reqs
		190	sendfile fadvise madvise
		191	mmap munmap munlock munlockall);
		192
		193	push @AIO_REQ, qw(aio_busy); # not exported
89		194
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	195	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		196
92	require XSLoader;	197	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	198	XSLoader::load ("IO::AIO", $VERSION);
94	}	199	}
95		200
96	=head1 FUNCTIONS	201	=head1 FUNCTIONS
97		202
		203	=head2 QUICK OVERVIEW
		204
		205	This section simply lists the prototypes of the most important functions
		206	for quick reference. See the following sections for function-by-function
		207	documentation.
		208
		209	aio_open $pathname, $flags, $mode, $callback->($fh)
		210	aio_close $fh, $callback->($status)
		211	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		212	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		213	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		214	aio_readahead $fh,$offset,$length, $callback->($retval)
		215	aio_stat $fh_or_path, $callback->($status)
		216	aio_lstat $fh, $callback->($status)
		217	aio_statvfs $fh_or_path, $callback->($statvfs)
		218	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		219	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		220	aio_truncate $fh_or_path, $offset, $callback->($status)
		221	aio_chmod $fh_or_path, $mode, $callback->($status)
		222	aio_unlink $pathname, $callback->($status)
		223	aio_mknod $path, $mode, $dev, $callback->($status)
		224	aio_link $srcpath, $dstpath, $callback->($status)
		225	aio_symlink $srcpath, $dstpath, $callback->($status)
		226	aio_readlink $path, $callback->($link)
		227	aio_rename $srcpath, $dstpath, $callback->($status)
		228	aio_mkdir $pathname, $mode, $callback->($status)
		229	aio_rmdir $pathname, $callback->($status)
		230	aio_readdir $pathname, $callback->($entries)
		231	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		232	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		233	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		234	aio_load $path, $data, $callback->($status)
		235	aio_copy $srcpath, $dstpath, $callback->($status)
		236	aio_move $srcpath, $dstpath, $callback->($status)
		237	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		238	aio_rmtree $path, $callback->($status)
		239	aio_sync $callback->($status)
		240	aio_fsync $fh, $callback->($status)
		241	aio_fdatasync $fh, $callback->($status)
		242	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		243	aio_pathsync $path, $callback->($status)
		244	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		245	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		246	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		247	aio_mlockall $flags, $callback->($status)
		248	aio_group $callback->(...)
		249	aio_nop $callback->()
		250
		251	$prev_pri = aioreq_pri [$pri]
		252	aioreq_nice $pri_adjust
		253
		254	IO::AIO::poll_wait
		255	IO::AIO::poll_cb
		256	IO::AIO::poll
		257	IO::AIO::flush
		258	IO::AIO::max_poll_reqs $nreqs
		259	IO::AIO::max_poll_time $seconds
		260	IO::AIO::min_parallel $nthreads
		261	IO::AIO::max_parallel $nthreads
		262	IO::AIO::max_idle $nthreads
		263	IO::AIO::idle_timeout $seconds
		264	IO::AIO::max_outstanding $maxreqs
		265	IO::AIO::nreqs
		266	IO::AIO::nready
		267	IO::AIO::npending
		268
		269	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		270	IO::AIO::fadvise $fh, $offset, $len, $advice
		271	IO::AIO::madvise $scalar, $offset, $length, $advice
		272	IO::AIO::mprotect $scalar, $offset, $length, $protect
		273	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		274	IO::AIO::munlockall
		275
98	=head2 AIO FUNCTIONS	276	=head2 AIO REQUEST FUNCTIONS
99		277
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	278	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	279	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	280	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	281	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	282	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	283	perl, which usually delivers "false") as its sole argument after the given
106	syscall has been executed asynchronously.	284	syscall has been executed asynchronously.
107		285
108	All functions expecting a filehandle keep a copy of the filehandle	286	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	287	internally until the request has finished.
110		288
111	All requests return objects of type L<IO::AIO::REQ> that allow further	289	All functions return request objects of type L<IO::AIO::REQ> that allow
112	manipulation of those requests while they are in-flight.	290	further manipulation of those requests while they are in-flight.
113		291
114	The pathnames you pass to these routines I<must> be absolute and	292	The pathnames you pass to these routines I<must> be absolute and
115	encoded in byte form. The reason for the former is that at the time the	293	encoded as octets. The reason for the former is that at the time the
116	request is being executed, the current working directory could have	294	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	295	changed. Alternatively, you can make sure that you never change the
118	current working directory.	296	current working directory anywhere in the program and then use relative
		297	paths.
119		298
120	To encode pathnames to byte form, either make sure you either: a)	299	To encode pathnames as octets, either make sure you either: a) always pass
121	always pass in filenames you got from outside (command line, readdir	300	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	301	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	302	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)	303	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	304	use something else to ensure your scalar has the correct contents.
		305
		306	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		307	handles correctly whether it is set or not.
126		308
127	=over 4	309	=over 4
128		310
129	=item aioreq_pri $pri	311	=item $prev_pri = aioreq_pri [$pri]
130		312
131	Sets the priority for the next aio request. The default priority	313	Returns the priority value that would be used for the next request and, if
		314	C<$pri> is given, sets the priority for the next aio request.
		315
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	316	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	317	and C<4>, respectively. Requests with higher priority will be serviced
		318	first.
134		319
135	The priority will be reset to C<0> after each call to one of the C<aio_>	320	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	321	functions.
137		322
138	Example: open a file with low priority, then read something from it with	323	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	324	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	325	open requests (potentially spamming the cache):
…		…
147	aio_read $_[0], ..., sub {	332	aio_read $_[0], ..., sub {
148	...	333	...
149	};	334	};
150	};	335	};
151		336
		337
152	=item aioreq_nice $pri_adjust	338	=item aioreq_nice $pri_adjust
153		339
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	340	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	341	priority, so the effect is cumulative.
		342
156		343
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	344	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		345
159	Asynchronously open or create a file and call the callback with a newly	346	Asynchronously open or create a file and call the callback with a newly
160	created filehandle for the file.	347	created filehandle for the file.
…		…
166	list. They are the same as used by C<sysopen>.	353	list. They are the same as used by C<sysopen>.
167		354
168	Likewise, C<$mode> specifies the mode of the newly created file, if it	355	Likewise, C<$mode> specifies the mode of the newly created file, if it
169	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	356	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
170	except that it is mandatory (i.e. use C<0> if you don't create new files,	357	except that it is mandatory (i.e. use C<0> if you don't create new files,
171	and C<0666> or C<0777> if you do).	358	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		359	by the umask in effect then the request is being executed, so better never
		360	change the umask.
172		361
173	Example:	362	Example:
174		363
175	aio_open "/etc/passwd", O_RDONLY, 0, sub {	364	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
176	if ($_[0]) {	365	if ($_[0]) {
177	print "open successful, fh is $_[0]\n";	366	print "open successful, fh is $_[0]\n";
178	...	367	...
179	} else {	368	} else {
180	die "open failed: $!\n";	369	die "open failed: $!\n";
181	}	370	}
182	};	371	};
183		372
		373	In addition to all the common open modes/flags (C<O_RDONLY>, C<O_WRONLY>,
		374	C<O_RDWR>, C<O_CREAT>, C<O_TRUNC>, C<O_EXCL> and C<O_APPEND>), the
		375	following POSIX and non-POSIX constants are available (missing ones on
		376	your system are, as usual, C<0>):
		377
		378	C<O_ASYNC>, C<O_DIRECT>, C<O_NOATIME>, C<O_CLOEXEC>, C<O_NOCTTY>, C<O_NOFOLLOW>,
		379	C<O_NONBLOCK>, C<O_EXEC>, C<O_SEARCH>, C<O_DIRECTORY>, C<O_DSYNC>,
		380	C<O_RSYNC>, C<O_SYNC> and C<O_TTY_INIT>.
		381
		382
184	=item aio_close $fh, $callback->($status)	383	=item aio_close $fh, $callback->($status)
185		384
186	Asynchronously close a file and call the callback with the result	385	Asynchronously close a file and call the callback with the result
187	code. I<WARNING:> although accepted, you should not pass in a perl	386	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		387
192	This is supposed to be a bug in the API, so that might change. It's	388	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
193	therefore best to avoid this function.	389	closing the file descriptor associated with the filehandle itself.
		390
		391	Therefore, C<aio_close> will not close the filehandle - instead it will
		392	use dup2 to overwrite the file descriptor with the write-end of a pipe
		393	(the pipe fd will be created on demand and will be cached).
		394
		395	Or in other words: the file descriptor will be closed, but it will not be
		396	free for reuse until the perl filehandle is closed.
		397
		398	=cut
194		399
195	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	400	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
196		401
197	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	402	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
198		403
199	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	404	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	405	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
201	callback without the actual number of bytes read (or -1 on error, just	406	and calls the callback without the actual number of bytes read (or -1 on
202	like the syscall).	407	error, just like the syscall).
		408
		409	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		410	offset plus the actual number of bytes read.
		411
		412	If C<$offset> is undefined, then the current file descriptor offset will
		413	be used (and updated), otherwise the file descriptor offset will not be
		414	changed by these calls.
		415
		416	If C<$length> is undefined in C<aio_write>, use the remaining length of
		417	C<$data>.
		418
		419	If C<$dataoffset> is less than zero, it will be counted from the end of
		420	C<$data>.
203		421
204	The C<$data> scalar I<MUST NOT> be modified in any way while the request	422	The C<$data> scalar I<MUST NOT> be modified in any way while the request
205	is outstanding. Modifying it can result in segfaults or WW3 (if the	423	is outstanding. Modifying it can result in segfaults or World War III (if
206	necessary/optional hardware is installed).	424	the necessary/optional hardware is installed).
207		425
208	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	426	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
209	offset C<0> within the scalar:	427	offset C<0> within the scalar:
210		428
211	aio_read $fh, 7, 15, $buffer, 0, sub {	429	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	430	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	431	print "read $_[0] bytes: <$buffer>\n";
214	};	432	};
215		433
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		434
286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	435	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
287		436
288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	437	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	438	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	439	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	440	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
292	other.	441	other.
293		442
		443	Please note that C<aio_sendfile> can read more bytes from C<$in_fh> than
		444	are written, and there is no way to find out how many bytes have been read
		445	from C<aio_sendfile> alone, as C<aio_sendfile> only provides the number of
		446	bytes written to C<$out_fh>. Only if the result value equals C<$length>
		447	one can assume that C<$length> bytes have been read.
		448
		449	Unlike with other C<aio_> functions, it makes a lot of sense to use
		450	C<aio_sendfile> on non-blocking sockets, as long as one end (typically
		451	the C<$in_fh>) is a file - the file I/O will then be asynchronous, while
		452	the socket I/O will be non-blocking. Note, however, that you can run into
		453	a trap where C<aio_sendfile> reads some data with readahead, then fails
		454	to write all data, and when the socket is ready the next time, the data
		455	in the cache is already lost, forcing C<aio_sendfile> to again hit the
		456	disk. Explicit C<aio_read> + C<aio_write> let's you control resource usage
		457	much better.
		458
294	This call tries to make use of a native C<sendfile> syscall to provide	459	This call tries to make use of a native C<sendfile> syscall to provide
295	zero-copy operation. For this to work, C<$out_fh> should refer to a	460	zero-copy operation. For this to work, C<$out_fh> should refer to a
296	socket, and C<$in_fh> should refer to mmap'able file.	461	socket, and C<$in_fh> should refer to an mmap'able file.
297		462
298	If the native sendfile call fails or is not implemented, it will be	463	If a native sendfile cannot be found or it fails with C<ENOSYS>,
		464	C<ENOTSUP>, C<EOPNOTSUPP>, C<EAFNOSUPPORT>, C<EPROTOTYPE> or C<ENOTSOCK>,
299	emulated, so you can call C<aio_sendfile> on any type of filehandle	465	it will be emulated, so you can call C<aio_sendfile> on any type of
300	regardless of the limitations of the operating system.	466	filehandle regardless of the limitations of the operating system.
301		467
302	Please note, however, that C<aio_sendfile> can read more bytes from
303	C<$in_fh> than are written, and there is no way to find out how many
304	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
305	provides the number of bytes written to C<$out_fh>. Only if the result
306	value equals C<$length> one can assume that C<$length> bytes have been
307	read.
308		468
309	=item aio_readahead $fh,$offset,$length, $callback->($retval)	469	=item aio_readahead $fh,$offset,$length, $callback->($retval)
310		470
311	C<aio_readahead> populates the page cache with data from a file so that	471	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>	472	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.	478	file. The current file offset of the file is left unchanged.
319		479
320	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	480	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.	481	emulated by simply reading the data, which would have a similar effect.
322		482
		483
323	=item aio_stat $fh_or_path, $callback->($status)	484	=item aio_stat $fh_or_path, $callback->($status)
324		485
325	=item aio_lstat $fh, $callback->($status)	486	=item aio_lstat $fh, $callback->($status)
326		487
327	Works like perl's C<stat> or C<lstat> in void context. The callback will	488	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
332	for an explanation.	493	for an explanation.
333		494
334	Currently, the stats are always 64-bit-stats, i.e. instead of returning an	495	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	496	error when stat'ing a large file, the results will be silently truncated
336	unless perl itself is compiled with large file support.	497	unless perl itself is compiled with large file support.
		498
		499	To help interpret the mode and dev/rdev stat values, IO::AIO offers the
		500	following constants and functions (if not implemented, the constants will
		501	be C<0> and the functions will either C<croak> or fall back on traditional
		502	behaviour).
		503
		504	C<S_IFMT>, C<S_IFIFO>, C<S_IFCHR>, C<S_IFBLK>, C<S_IFLNK>, C<S_IFREG>,
		505	C<S_IFDIR>, C<S_IFWHT>, C<S_IFSOCK>, C<IO::AIO::major $dev_t>,
		506	C<IO::AIO::minor $dev_t>, C<IO::AIO::makedev $major, $minor>.
337		507
338	Example: Print the length of F</etc/passwd>:	508	Example: Print the length of F</etc/passwd>:
339		509
340	aio_stat "/etc/passwd", sub {	510	aio_stat "/etc/passwd", sub {
341	$_[0] and die "stat failed: $!";	511	$_[0] and die "stat failed: $!";
342	print "size is ", -s _, "\n";	512	print "size is ", -s _, "\n";
343	};	513	};
344		514
		515
		516	=item aio_statvfs $fh_or_path, $callback->($statvfs)
		517
		518	Works like the POSIX C<statvfs> or C<fstatvfs> syscalls, depending on
		519	whether a file handle or path was passed.
		520
		521	On success, the callback is passed a hash reference with the following
		522	members: C<bsize>, C<frsize>, C<blocks>, C<bfree>, C<bavail>, C<files>,
		523	C<ffree>, C<favail>, C<fsid>, C<flag> and C<namemax>. On failure, C<undef>
		524	is passed.
		525
		526	The following POSIX IO::AIO::ST_* constants are defined: C<ST_RDONLY> and
		527	C<ST_NOSUID>.
		528
		529	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		530	their correct value when available, or to C<0> on systems that do
		531	not support them: C<ST_NODEV>, C<ST_NOEXEC>, C<ST_SYNCHRONOUS>,
		532	C<ST_MANDLOCK>, C<ST_WRITE>, C<ST_APPEND>, C<ST_IMMUTABLE>, C<ST_NOATIME>,
		533	C<ST_NODIRATIME> and C<ST_RELATIME>.
		534
		535	Example: stat C</wd> and dump out the data if successful.
		536
		537	aio_statvfs "/wd", sub {
		538	my $f = $_[0]
		539	or die "statvfs: $!";
		540
		541	use Data::Dumper;
		542	say Dumper $f;
		543	};
		544
		545	# result:
		546	{
		547	bsize => 1024,
		548	bfree => 4333064312,
		549	blocks => 10253828096,
		550	files => 2050765568,
		551	flag => 4096,
		552	favail => 2042092649,
		553	bavail => 4333064312,
		554	ffree => 2042092649,
		555	namemax => 255,
		556	frsize => 1024,
		557	fsid => 1810
		558	}
		559
		560
		561	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		562
		563	Works like perl's C<utime> function (including the special case of $atime
		564	and $mtime being undef). Fractional times are supported if the underlying
		565	syscalls support them.
		566
		567	When called with a pathname, uses utimes(2) if available, otherwise
		568	utime(2). If called on a file descriptor, uses futimes(2) if available,
		569	otherwise returns ENOSYS, so this is not portable.
		570
		571	Examples:
		572
		573	# set atime and mtime to current time (basically touch(1)):
		574	aio_utime "path", undef, undef;
		575	# set atime to current time and mtime to beginning of the epoch:
		576	aio_utime "path", time, undef; # undef==0
		577
		578
		579	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		580
		581	Works like perl's C<chown> function, except that C<undef> for either $uid
		582	or $gid is being interpreted as "do not change" (but -1 can also be used).
		583
		584	Examples:
		585
		586	# same as "chown root path" in the shell:
		587	aio_chown "path", 0, -1;
		588	# same as above:
		589	aio_chown "path", 0, undef;
		590
		591
		592	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		593
		594	Works like truncate(2) or ftruncate(2).
		595
		596
		597	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		598
		599	Works like perl's C<chmod> function.
		600
		601
345	=item aio_unlink $pathname, $callback->($status)	602	=item aio_unlink $pathname, $callback->($status)
346		603
347	Asynchronously unlink (delete) a file and call the callback with the	604	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	605	result code.
349		606
		607
		608	=item aio_mknod $path, $mode, $dev, $callback->($status)
		609
		610	[EXPERIMENTAL]
		611
		612	Asynchronously create a device node (or fifo). See mknod(2).
		613
		614	The only (POSIX-) portable way of calling this function is:
		615
		616	aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
		617
		618	See C<aio_stat> for info about some potentially helpful extra constants
		619	and functions.
		620
350	=item aio_link $srcpath, $dstpath, $callback->($status)	621	=item aio_link $srcpath, $dstpath, $callback->($status)
351		622
352	Asynchronously create a new link to the existing object at C<$srcpath> at	623	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.	624	the path C<$dstpath> and call the callback with the result code.
354		625
		626
355	=item aio_symlink $srcpath, $dstpath, $callback->($status)	627	=item aio_symlink $srcpath, $dstpath, $callback->($status)
356		628
357	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	629	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.	630	the path C<$dstpath> and call the callback with the result code.
359		631
		632
		633	=item aio_readlink $path, $callback->($link)
		634
		635	Asynchronously read the symlink specified by C<$path> and pass it to
		636	the callback. If an error occurs, nothing or undef gets passed to the
		637	callback.
		638
		639
360	=item aio_rename $srcpath, $dstpath, $callback->($status)	640	=item aio_rename $srcpath, $dstpath, $callback->($status)
361		641
362	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	642	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
363	rename(2) and call the callback with the result code.	643	rename(2) and call the callback with the result code.
364		644
		645
		646	=item aio_mkdir $pathname, $mode, $callback->($status)
		647
		648	Asynchronously mkdir (create) a directory and call the callback with
		649	the result code. C<$mode> will be modified by the umask at the time the
		650	request is executed, so do not change your umask.
		651
		652
365	=item aio_rmdir $pathname, $callback->($status)	653	=item aio_rmdir $pathname, $callback->($status)
366		654
367	Asynchronously rmdir (delete) a directory and call the callback with the	655	Asynchronously rmdir (delete) a directory and call the callback with the
368	result code.	656	result code.
		657
369		658
370	=item aio_readdir $pathname, $callback->($entries)	659	=item aio_readdir $pathname, $callback->($entries)
371		660
372	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	661	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	662	directory (i.e. opendir + readdir + closedir). The entries will not be
374	sorted, and will B<NOT> include the C<.> and C<..> entries.	663	sorted, and will B<NOT> include the C<.> and C<..> entries.
375		664
376	The callback a single argument which is either C<undef> or an array-ref	665	The callback is passed a single argument which is either C<undef> or an
377	with the filenames.	666	array-ref with the filenames.
		667
		668
		669	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		670
		671	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		672	behaviour and output format. In case of an error, C<$entries> will be
		673	C<undef>.
		674
		675	The flags are a combination of the following constants, ORed together (the
		676	flags will also be passed to the callback, possibly modified):
		677
		678	=over 4
		679
		680	=item IO::AIO::READDIR_DENTS
		681
		682	When this flag is off, then the callback gets an arrayref consisting of
		683	names only (as with C<aio_readdir>), otherwise it gets an arrayref with
		684	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		685	entry in more detail.
		686
		687	C<$name> is the name of the entry.
		688
		689	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		690
		691	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		692	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		693	C<IO::AIO::DT_WHT>.
		694
		695	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		696	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		697	scalars are read-only: you can not modify them.
		698
		699	C<$inode> is the inode number (which might not be exact on systems with 64
		700	bit inode numbers and 32 bit perls). This field has unspecified content on
		701	systems that do not deliver the inode information.
		702
		703	=item IO::AIO::READDIR_DIRS_FIRST
		704
		705	When this flag is set, then the names will be returned in an order where
		706	likely directories come first, in optimal stat order. This is useful when
		707	you need to quickly find directories, or you want to find all directories
		708	while avoiding to stat() each entry.
		709
		710	If the system returns type information in readdir, then this is used
		711	to find directories directly. Otherwise, likely directories are names
		712	beginning with ".", or otherwise names with no dots, of which names with
		713	short names are tried first.
		714
		715	=item IO::AIO::READDIR_STAT_ORDER
		716
		717	When this flag is set, then the names will be returned in an order
		718	suitable for stat()'ing each one. That is, when you plan to stat()
		719	all files in the given directory, then the returned order will likely
		720	be fastest.
		721
		722	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		723	the likely dirs come first, resulting in a less optimal stat order.
		724
		725	=item IO::AIO::READDIR_FOUND_UNKNOWN
		726
		727	This flag should not be set when calling C<aio_readdirx>. Instead, it
		728	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		729	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		730	C<$type>'s are known, which can be used to speed up some algorithms.
		731
		732	=back
		733
		734
		735	=item aio_load $path, $data, $callback->($status)
		736
		737	This is a composite request that tries to fully load the given file into
		738	memory. Status is the same as with aio_read.
		739
		740	=cut
		741
		742	sub aio_load($$;$) {
		743	my ($path, undef, $cb) = @_;
		744	my $data = \$_[1];
		745
		746	my $pri = aioreq_pri;
		747	my $grp = aio_group $cb;
		748
		749	aioreq_pri $pri;
		750	add $grp aio_open $path, O_RDONLY, 0, sub {
		751	my $fh = shift
		752	or return $grp->result (-1);
		753
		754	aioreq_pri $pri;
		755	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		756	$grp->result ($_[0]);
		757	};
		758	};
		759
		760	$grp
		761	}
		762
		763	=item aio_copy $srcpath, $dstpath, $callback->($status)
		764
		765	Try to copy the I<file> (directories not supported as either source or
		766	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		767	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		768
		769	This is a composite request that creates the destination file with
		770	mode 0200 and copies the contents of the source file into it using
		771	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		772	uid/gid, in that order.
		773
		774	If an error occurs, the partial destination file will be unlinked, if
		775	possible, except when setting atime, mtime, access mode and uid/gid, where
		776	errors are being ignored.
		777
		778	=cut
		779
		780	sub aio_copy($$;$) {
		781	my ($src, $dst, $cb) = @_;
		782
		783	my $pri = aioreq_pri;
		784	my $grp = aio_group $cb;
		785
		786	aioreq_pri $pri;
		787	add $grp aio_open $src, O_RDONLY, 0, sub {
		788	if (my $src_fh = $_[0]) {
		789	my @stat = stat $src_fh; # hmm, might block over nfs?
		790
		791	aioreq_pri $pri;
		792	add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
		793	if (my $dst_fh = $_[0]) {
		794	aioreq_pri $pri;
		795	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		796	if ($_[0] == $stat[7]) {
		797	$grp->result (0);
		798	close $src_fh;
		799
		800	my $ch = sub {
		801	aioreq_pri $pri;
		802	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		803	aioreq_pri $pri;
		804	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		805	aioreq_pri $pri;
		806	add $grp aio_close $dst_fh;
		807	}
		808	};
		809	};
		810
		811	aioreq_pri $pri;
		812	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		813	if ($_[0] < 0 && $! == ENOSYS) {
		814	aioreq_pri $pri;
		815	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
		816	} else {
		817	$ch->();
		818	}
		819	};
		820	} else {
		821	$grp->result (-1);
		822	close $src_fh;
		823	close $dst_fh;
		824
		825	aioreq $pri;
		826	add $grp aio_unlink $dst;
		827	}
		828	};
		829	} else {
		830	$grp->result (-1);
		831	}
		832	},
		833
		834	} else {
		835	$grp->result (-1);
		836	}
		837	};
		838
		839	$grp
		840	}
		841
		842	=item aio_move $srcpath, $dstpath, $callback->($status)
		843
		844	Try to move the I<file> (directories not supported as either source or
		845	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		846	a status of C<0> (ok) or C<-1> (error, see C<$!>).
		847
		848	This is a composite request that tries to rename(2) the file first; if
		849	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
		850	that is successful, unlinks the C<$srcpath>.
		851
		852	=cut
		853
		854	sub aio_move($$;$) {
		855	my ($src, $dst, $cb) = @_;
		856
		857	my $pri = aioreq_pri;
		858	my $grp = aio_group $cb;
		859
		860	aioreq_pri $pri;
		861	add $grp aio_rename $src, $dst, sub {
		862	if ($_[0] && $! == EXDEV) {
		863	aioreq_pri $pri;
		864	add $grp aio_copy $src, $dst, sub {
		865	$grp->result ($_[0]);
		866
		867	if (!$_[0]) {
		868	aioreq_pri $pri;
		869	add $grp aio_unlink $src;
		870	}
		871	};
		872	} else {
		873	$grp->result ($_[0]);
		874	}
		875	};
		876
		877	$grp
		878	}
378		879
379	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	880	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
380		881
381	[EXPERIMENTAL due to internal aio_group use]
382
383	Scans a directory (similar to C<aio_readdir>) but additionally tries to	882	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	883	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	884	names, directories you can recurse into (directories), and ones you cannot
386	recurse into (everything else).	885	recurse into (everything else, including symlinks to directories).
387		886
388	C<aio_scandir> is a composite request that creates of many sub requests_	887	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	888	C<$maxreq> specifies the maximum number of outstanding aio requests that
390	this function generates. If it is C<< <= 0 >>, then a suitable default	889	this function generates. If it is C<< <= 0 >>, then a suitable default
391	will be chosen (currently 6).	890	will be chosen (currently 4).
392		891
393	On error, the callback is called without arguments, otherwise it receives	892	On error, the callback is called without arguments, otherwise it receives
394	two array-refs with path-relative entry names.	893	two array-refs with path-relative entry names.
395		894
396	Example:	895	Example:
…		…
403		902
404	Implementation notes.	903	Implementation notes.
405		904
406	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	905	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
407		906
		907	If readdir returns file type information, then this is used directly to
		908	find directories.
		909
408	After reading the directory, the modification time, size etc. of the	910	Otherwise, after reading the directory, the modification time, size etc.
409	directory before and after the readdir is checked, and if they match (and	911	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	912	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	913	how many entries are directories (if >= 2). Otherwise, no knowledge of the
412	of subdirectories will be assumed.	914	number of subdirectories will be assumed.
413		915
414	Then entries will be sorted into likely directories (everything without	916	Then entries will be sorted into likely directories a non-initial dot
415	a non-initial dot currently) and likely non-directories (everything	917	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,	918	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	919	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	920	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	921	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	922	filesystems might detect the type of the entry without reading the inode
421	data (e.g. ext2fs filetype feature).	923	data (e.g. ext2fs filetype feature), even on systems that cannot return
		924	the filetype information on readdir.
422		925
423	If the known number of directories (link count - 2) has been reached, the	926	If the known number of directories (link count - 2) has been reached, the
424	rest of the entries is assumed to be non-directories.	927	rest of the entries is assumed to be non-directories.
425		928
426	This only works with certainty on POSIX (= UNIX) filesystems, which	929	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	933	as those tend to return 0 or 1 as link counts, which disables the
431	directory counting heuristic.	934	directory counting heuristic.
432		935
433	=cut	936	=cut
434		937
435	sub aio_scandir($$$) {	938	sub aio_scandir($$;$) {
436	my ($path, $maxreq, $cb) = @_;	939	my ($path, $maxreq, $cb) = @_;
437		940
		941	my $pri = aioreq_pri;
		942
438	my $grp = aio_group $cb;	943	my $grp = aio_group $cb;
439		944
440	$maxreq = 6 if $maxreq <= 0;	945	$maxreq = 4 if $maxreq <= 0;
441		946
442	# stat once	947	# stat once
		948	aioreq_pri $pri;
443	add $grp aio_stat $path, sub {	949	add $grp aio_stat $path, sub {
444	return $grp->result () if $_[0];	950	return $grp->result () if $_[0];
445	my $now = time;	951	my $now = time;
446	my $hash1 = join ":", (stat _)[0,1,3,7,9];	952	my $hash1 = join ":", (stat _)[0,1,3,7,9];
447		953
448	# read the directory entries	954	# read the directory entries
		955	aioreq_pri $pri;
449	add $grp aio_readdir $path, sub {	956	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
450	my $entries = shift	957	my $entries = shift
451	or return $grp->result ();	958	or return $grp->result ();
452		959
453	# stat the dir another time	960	# stat the dir another time
		961	aioreq_pri $pri;
454	add $grp aio_stat $path, sub {	962	add $grp aio_stat $path, sub {
455	my $hash2 = join ":", (stat _)[0,1,3,7,9];	963	my $hash2 = join ":", (stat _)[0,1,3,7,9];
456		964
457	my $ndirs;	965	my $ndirs;
458		966
459	# take the slow route if anything looks fishy	967	# take the slow route if anything looks fishy
460	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	968	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
461	$ndirs = -1;	969	$ndirs = -1;
462	} else {	970	} else {
463	# if nlink == 2, we are finished	971	# if nlink == 2, we are finished
464	# on non-posix-fs's, we rely on nlink < 2	972	# for non-posix-fs's, we rely on nlink < 2
465	$ndirs = (stat _)[3] - 2	973	$ndirs = (stat _)[3] - 2
466	or return $grp->result ([], $entries);	974	or return $grp->result ([], $entries);
467	}	975	}
468		976
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	@$entries];
475
476	my (@dirs, @nondirs);	977	my (@dirs, @nondirs);
477		978
478	my ($statcb, $schedcb);
479	my $nreq = 0;
480
481	my $statgrp = add $grp aio_group;	979	my $statgrp = add $grp aio_group sub {
		980	$grp->result (\@dirs, \@nondirs);
		981	};
482		982
483	$schedcb = sub {	983	limit $statgrp $maxreq;
484	if (@$entries) {	984	feed $statgrp sub {
485	if ($nreq < $maxreq) {	985	return unless @$entries;
486	my $ent = pop @$entries;	986	my $entry = shift @$entries;
		987
		988	aioreq_pri $pri;
		989	add $statgrp aio_stat "$path/$entry/.", sub {
		990	if ($_[0] < 0) {
		991	push @nondirs, $entry;
		992	} else {
		993	# need to check for real directory
		994	aioreq_pri $pri;
		995	add $statgrp aio_lstat "$path/$entry", sub {
		996	if (-d _) {
		997	push @dirs, $entry;
		998
		999	unless (--$ndirs) {
		1000	push @nondirs, @$entries;
		1001	feed $statgrp;
		1002	}
		1003	} else {
		1004	push @nondirs, $entry;
		1005	}
487	$nreq++;	1006	}
488	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
489	}	1007	}
490	} elsif (!$nreq) {
491	# finished
492	$statgrp->cancel;
493	undef $statcb;
494	undef $schedcb;
495	$grp->result (\@dirs, \@nondirs);
496	}	1008	};
497	};	1009	};
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	};	1010	};
528	};	1011	};
529	};	1012	};
530		1013
531	$grp	1014	$grp
532	}	1015	}
533		1016
		1017	=item aio_rmtree $path, $callback->($status)
		1018
		1019	Delete a directory tree starting (and including) C<$path>, return the
		1020	status of the final C<rmdir> only. This is a composite request that
		1021	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		1022	everything else.
		1023
		1024	=cut
		1025
		1026	sub aio_rmtree;
		1027	sub aio_rmtree($;$) {
		1028	my ($path, $cb) = @_;
		1029
		1030	my $pri = aioreq_pri;
		1031	my $grp = aio_group $cb;
		1032
		1033	aioreq_pri $pri;
		1034	add $grp aio_scandir $path, 0, sub {
		1035	my ($dirs, $nondirs) = @_;
		1036
		1037	my $dirgrp = aio_group sub {
		1038	add $grp aio_rmdir $path, sub {
		1039	$grp->result ($_[0]);
		1040	};
		1041	};
		1042
		1043	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		1044	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		1045
		1046	add $grp $dirgrp;
		1047	};
		1048
		1049	$grp
		1050	}
		1051
		1052	=item aio_sync $callback->($status)
		1053
		1054	Asynchronously call sync and call the callback when finished.
		1055
534	=item aio_fsync $fh, $callback->($status)	1056	=item aio_fsync $fh, $callback->($status)
535		1057
536	Asynchronously call fsync on the given filehandle and call the callback	1058	Asynchronously call fsync on the given filehandle and call the callback
537	with the fsync result code.	1059	with the fsync result code.
538		1060
…		…
542	callback with the fdatasync result code.	1064	callback with the fdatasync result code.
543		1065
544	If this call isn't available because your OS lacks it or it couldn't be	1066	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.	1067	detected, it will be emulated by calling C<fsync> instead.
546		1068
		1069	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		1070
		1071	Sync the data portion of the file specified by C<$offset> and C<$length>
		1072	to disk (but NOT the metadata), by calling the Linux-specific
		1073	sync_file_range call. If sync_file_range is not available or it returns
		1074	ENOSYS, then fdatasync or fsync is being substituted.
		1075
		1076	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		1077	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		1078	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		1079	manpage for details.
		1080
		1081	=item aio_pathsync $path, $callback->($status)
		1082
		1083	This request tries to open, fsync and close the given path. This is a
		1084	composite request intended to sync directories after directory operations
		1085	(E.g. rename). This might not work on all operating systems or have any
		1086	specific effect, but usually it makes sure that directory changes get
		1087	written to disc. It works for anything that can be opened for read-only,
		1088	not just directories.
		1089
		1090	Future versions of this function might fall back to other methods when
		1091	C<fsync> on the directory fails (such as calling C<sync>).
		1092
		1093	Passes C<0> when everything went ok, and C<-1> on error.
		1094
		1095	=cut
		1096
		1097	sub aio_pathsync($;$) {
		1098	my ($path, $cb) = @_;
		1099
		1100	my $pri = aioreq_pri;
		1101	my $grp = aio_group $cb;
		1102
		1103	aioreq_pri $pri;
		1104	add $grp aio_open $path, O_RDONLY, 0, sub {
		1105	my ($fh) = @_;
		1106	if ($fh) {
		1107	aioreq_pri $pri;
		1108	add $grp aio_fsync $fh, sub {
		1109	$grp->result ($_[0]);
		1110
		1111	aioreq_pri $pri;
		1112	add $grp aio_close $fh;
		1113	};
		1114	} else {
		1115	$grp->result (-1);
		1116	}
		1117	};
		1118
		1119	$grp
		1120	}
		1121
		1122	=item aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1123
		1124	This is a rather advanced IO::AIO call, which only works on mmap(2)ed
		1125	scalars (see the C<IO::AIO::mmap> function, although it also works on data
		1126	scalars managed by the L<Sys::Mmap> or L<Mmap> modules, note that the
		1127	scalar must only be modified in-place while an aio operation is pending on
		1128	it).
		1129
		1130	It calls the C<msync> function of your OS, if available, with the memory
		1131	area starting at C<$offset> in the string and ending C<$length> bytes
		1132	later. If C<$length> is negative, counts from the end, and if C<$length>
		1133	is C<undef>, then it goes till the end of the string. The flags can be
		1134	a combination of C<IO::AIO::MS_ASYNC>, C<IO::AIO::MS_INVALIDATE> and
		1135	C<IO::AIO::MS_SYNC>.
		1136
		1137	=item aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		1138
		1139	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1140	scalars.
		1141
		1142	It touches (reads or writes) all memory pages in the specified
		1143	range inside the scalar. All caveats and parameters are the same
		1144	as for C<aio_msync>, above, except for flags, which must be either
		1145	C<0> (which reads all pages and ensures they are instantiated) or
		1146	C<IO::AIO::MT_MODIFY>, which modifies the memory page s(by reading and
		1147	writing an octet from it, which dirties the page).
		1148
		1149	=item aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		1150
		1151	This is a rather advanced IO::AIO call, which works best on mmap(2)ed
		1152	scalars.
		1153
		1154	It reads in all the pages of the underlying storage into memory (if any)
		1155	and locks them, so they are not getting swapped/paged out or removed.
		1156
		1157	If C<$length> is undefined, then the scalar will be locked till the end.
		1158
		1159	On systems that do not implement C<mlock>, this function returns C<-1>
		1160	and sets errno to C<ENOSYS>.
		1161
		1162	Note that the corresponding C<munlock> is synchronous and is
		1163	documented under L<MISCELLANEOUS FUNCTIONS>.
		1164
		1165	Example: open a file, mmap and mlock it - both will be undone when
		1166	C<$data> gets destroyed.
		1167
		1168	open my $fh, "<", $path or die "$path: $!";
		1169	my $data;
		1170	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1171	aio_mlock $data; # mlock in background
		1172
		1173	=item aio_mlockall $flags, $callback->($status)
		1174
		1175	Calls the C<mlockall> function with the given C<$flags> (a combination of
		1176	C<IO::AIO::MCL_CURRENT> and C<IO::AIO::MCL_FUTURE>).
		1177
		1178	On systems that do not implement C<mlockall>, this function returns C<-1>
		1179	and sets errno to C<ENOSYS>.
		1180
		1181	Note that the corresponding C<munlockall> is synchronous and is
		1182	documented under L<MISCELLANEOUS FUNCTIONS>.
		1183
		1184	Example: asynchronously lock all current and future pages into memory.
		1185
		1186	aio_mlockall IO::AIO::MCL_FUTURE;
		1187
547	=item aio_group $callback->(...)	1188	=item aio_group $callback->(...)
548
549	[EXPERIMENTAL]
550		1189
551	This is a very special aio request: Instead of doing something, it is a	1190	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	1191	container for other aio requests, which is useful if you want to bundle
553	many requests into a single, composite, request.	1192	many requests into a single, composite, request with a definite callback
		1193	and the ability to cancel the whole request with its subrequests.
554		1194
555	Returns an object of class L<IO::AIO::GRP>. See its documentation below	1195	Returns an object of class L<IO::AIO::GRP>. See its documentation below
556	for more info.	1196	for more info.
557		1197
558	Example:	1198	Example:
…		…
577	phase and still requires a worker thread. Thus, the callback will not	1217	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	1218	be executed immediately but only after other requests in the queue have
579	entered their execution phase. This can be used to measure request	1219	entered their execution phase. This can be used to measure request
580	latency.	1220	latency.
581		1221
582	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() *NOT EXPORTED*	1222	=item IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED*
583		1223
584	Mainly used for debugging and benchmarking, this aio request puts one of	1224	Mainly used for debugging and benchmarking, this aio request puts one of
585	the request workers to sleep for the given time.	1225	the request workers to sleep for the given time.
586		1226
587	While it is theoretically handy to have simple I/O scheduling requests	1227	While it is theoretically handy to have simple I/O scheduling requests
588	like sleep and file handle readable/writable, the overhead this creates	1228	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	1229	immense (it blocks a thread for a long time) so do not use this function
590	under artificial I/O pressure.	1230	except to put your application under artificial I/O pressure.
591		1231
592	=back	1232	=back
593		1233
594	=head2 IO::AIO::REQ CLASS	1234	=head2 IO::AIO::REQ CLASS
595		1235
596	All non-aggregate C<aio_*> functions return an object of this class when	1236	All non-aggregate C<aio_*> functions return an object of this class when
597	called in non-void context.	1237	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		1238
607	=over 4	1239	=over 4
608		1240
609	=item cancel $req	1241	=item cancel $req
610		1242
611	Cancels the request, if possible. Has the effect of skipping execution	1243	Cancels the request, if possible. Has the effect of skipping execution
612	when entering the B<execute> state and skipping calling the callback when	1244	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	1245	entering the the B<result> state, but will leave the request otherwise
614	untouched. That means that requests that currently execute will not be	1246	untouched (with the exception of readdir). That means that requests that
615	stopped and resources held by the request will not be freed prematurely.	1247	currently execute will not be stopped and resources held by the request
		1248	will not be freed prematurely.
616		1249
617	=item cb $req $callback->(...)	1250	=item cb $req $callback->(...)
618		1251
619	Replace (or simply set) the callback registered to the request.	1252	Replace (or simply set) the callback registered to the request.
620		1253
…		…
664	=item * They can also can also be added to other IO::AIO::GRP objects.	1297	=item * They can also can also be added to other IO::AIO::GRP objects.
665		1298
666	=item * You must not add requests to a group from within the group callback (or	1299	=item * You must not add requests to a group from within the group callback (or
667	any later time).	1300	any later time).
668		1301
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	1302	=back
674		1303
675	Their lifetime, simplified, looks like this: when they are empty, they	1304	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	1305	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	1306	C<done> state, they will also finish. Otherwise they will continue to
678	exist.	1307	exist.
679		1308
680	That means after creating a group you have some time to add requests. And	1309	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	1310	(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	1311	the C<poll_cb>). And in the callbacks of those requests, you can add
683	itself finish.	1312	further requests to the group. And only when all those requests have
		1313	finished will the the group itself finish.
684		1314
685	=over 4	1315	=over 4
686		1316
687	=item add $grp ...	1317	=item add $grp ...
688		1318
…		…
692	be added, including other groups, as long as you do not create circular	1322	be added, including other groups, as long as you do not create circular
693	dependencies.	1323	dependencies.
694		1324
695	Returns all its arguments.	1325	Returns all its arguments.
696		1326
		1327	=item $grp->cancel_subs
		1328
		1329	Cancel all subrequests and clears any feeder, but not the group request
		1330	itself. Useful when you queued a lot of events but got a result early.
		1331
		1332	The group request will finish normally (you cannot add requests to the
		1333	group).
		1334
697	=item $grp->result (...)	1335	=item $grp->result (...)
698		1336
699	Set the result value(s) that will be passed to the group callback when all	1337	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.	1338	subrequests have finished and set the groups errno to the current value
		1339	of errno (just like calling C<errno> without an error number). By default,
		1340	no argument will be passed and errno is zero.
		1341
		1342	=item $grp->errno ([$errno])
		1343
		1344	Sets the group errno value to C<$errno>, or the current value of errno
		1345	when the argument is missing.
		1346
		1347	Every aio request has an associated errno value that is restored when
		1348	the callback is invoked. This method lets you change this value from its
		1349	default (0).
		1350
		1351	Calling C<result> will also set errno, so make sure you either set C<$!>
		1352	before the call to C<result>, or call c<errno> after it.
701		1353
702	=item feed $grp $callback->($grp)	1354	=item feed $grp $callback->($grp)
703
704	[VERY EXPERIMENTAL]
705		1355
706	Sets a feeder/generator on this group: every group can have an attached	1356	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,	1357	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,	1358	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	1359	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>	1360	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
711	requests, delaying any later requests for a long time.	1361	delaying any later requests for a long time.
712		1362
713	To avoid this, and allow incremental generation of requests, you can	1363	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	1364	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>,	1365	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	1366	below) requests active in the group itself and is expected to queue more
…		…
720	not impose any limits).	1370	not impose any limits).
721		1371
722	If the feed does not queue more requests when called, it will be	1372	If the feed does not queue more requests when called, it will be
723	automatically removed from the group.	1373	automatically removed from the group.
724		1374
725	If the feed limit is C<0>, it will be set to C<2> automatically.	1375	If the feed limit is C<0> when this method is called, it will be set to
		1376	C<2> automatically.
726		1377
727	Example:	1378	Example:
728		1379
729	# stat all files in @files, but only ever use four aio requests concurrently:	1380	# stat all files in @files, but only ever use four aio requests concurrently:
730		1381
…		…
742	Sets the feeder limit for the group: The feeder will be called whenever	1393	Sets the feeder limit for the group: The feeder will be called whenever
743	the group contains less than this many requests.	1394	the group contains less than this many requests.
744		1395
745	Setting the limit to C<0> will pause the feeding process.	1396	Setting the limit to C<0> will pause the feeding process.
746		1397
		1398	The default value for the limit is C<0>, but note that setting a feeder
		1399	automatically bumps it up to C<2>.
		1400
747	=back	1401	=back
748		1402
749	=head2 SUPPORT FUNCTIONS	1403	=head2 SUPPORT FUNCTIONS
750		1404
		1405	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1406
751	=over 4	1407	=over 4
752		1408
753	=item $fileno = IO::AIO::poll_fileno	1409	=item $fileno = IO::AIO::poll_fileno
754		1410
755	Return the I<request result pipe file descriptor>. This filehandle must be	1411	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	1412	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	1413	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
758	to call C<poll_cb> to check the results.	1414	you have to call C<poll_cb> to check the results.
759		1415
760	See C<poll_cb> for an example.	1416	See C<poll_cb> for an example.
761		1417
762	=item IO::AIO::poll_cb	1418	=item IO::AIO::poll_cb
763		1419
764	Process all outstanding events on the result pipe. You have to call this	1420	Process some outstanding events on the result pipe. You have to call
765	regularly. Returns the number of events processed. Returns immediately	1421	this regularly. Returns C<0> if all events could be processed (or there
766	when no events are outstanding.	1422	were no events to process), or C<-1> if it returned earlier for whatever
		1423	reason. Returns immediately when no events are outstanding. The amount of
		1424	events processed depends on the settings of C<IO::AIO::max_poll_req> and
		1425	C<IO::AIO::max_poll_time>.
		1426
		1427	If not all requests were processed for whatever reason, the filehandle
		1428	will still be ready when C<poll_cb> returns, so normally you don't have to
		1429	do anything special to have it called later.
		1430
		1431	Apart from calling C<IO::AIO::poll_cb> when the event filehandle becomes
		1432	ready, it can be beneficial to call this function from loops which submit
		1433	a lot of requests, to make sure the results get processed when they become
		1434	available and not just when the loop is finished and the event loop takes
		1435	over again. This function returns very fast when there are no outstanding
		1436	requests.
767		1437
768	Example: Install an Event watcher that automatically calls	1438	Example: Install an Event watcher that automatically calls
769	IO::AIO::poll_cb with high priority:	1439	IO::AIO::poll_cb with high priority (more examples can be found in the
		1440	SYNOPSIS section, at the top of this document):
770		1441
771	Event->io (fd => IO::AIO::poll_fileno,	1442	Event->io (fd => IO::AIO::poll_fileno,
772	poll => 'r', async => 1,	1443	poll => 'r', async => 1,
773	cb => \&IO::AIO::poll_cb);	1444	cb => \&IO::AIO::poll_cb);
774		1445
775	=item IO::AIO::poll_wait	1446	=item IO::AIO::poll_wait
776		1447
		1448	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	1449	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	1450	does a C<select> on the filehandle. This is useful if you want to
779	for some requests to finish).	1451	synchronously wait for some requests to finish).
780		1452
781	See C<nreqs> for an example.	1453	See C<nreqs> for an example.
782		1454
		1455	=item IO::AIO::poll
		1456
		1457	Waits until some requests have been handled.
		1458
		1459	Returns the number of requests processed, but is otherwise strictly
		1460	equivalent to:
		1461
		1462	IO::AIO::poll_wait, IO::AIO::poll_cb
		1463
783	=item IO::AIO::nreqs	1464	=item IO::AIO::flush
784		1465
785	Returns the number of requests currently outstanding (i.e. for which their	1466	Wait till all outstanding AIO requests have been handled.
786	callback has not been invoked yet).
787		1467
788	Example: wait till there are no outstanding requests anymore:	1468	Strictly equivalent to:
789		1469
790	IO::AIO::poll_wait, IO::AIO::poll_cb	1470	IO::AIO::poll_wait, IO::AIO::poll_cb
791	while IO::AIO::nreqs;	1471	while IO::AIO::nreqs;
792		1472
793	=item IO::AIO::flush	1473	=item IO::AIO::max_poll_reqs $nreqs
794		1474
795	Wait till all outstanding AIO requests have been handled.	1475	=item IO::AIO::max_poll_time $seconds
796		1476
797	Strictly equivalent to:	1477	These set the maximum number of requests (default C<0>, meaning infinity)
		1478	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1479	the maximum amount of time (default C<0>, meaning infinity) spent in
		1480	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1481	of time C<poll_cb> is allowed to use).
798		1482
799	IO::AIO::poll_wait, IO::AIO::poll_cb	1483	Setting C<max_poll_time> to a non-zero value creates an overhead of one
800	while IO::AIO::nreqs;	1484	syscall per request processed, which is not normally a problem unless your
		1485	callbacks are really really fast or your OS is really really slow (I am
		1486	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
801		1487
802	=item IO::AIO::poll	1488	Setting these is useful if you want to ensure some level of
		1489	interactiveness when perl is not fast enough to process all requests in
		1490	time.
803		1491
804	Waits until some requests have been handled.	1492	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
805		1493
806	Strictly equivalent to:	1494	Example: Install an Event watcher that automatically calls
		1495	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1496	program get the CPU sometimes even under high AIO load.
807		1497
808	IO::AIO::poll_wait, IO::AIO::poll_cb	1498	# try not to spend much more than 0.1s in poll_cb
809	if IO::AIO::nreqs;	1499	IO::AIO::max_poll_time 0.1;
		1500
		1501	# use a low priority so other tasks have priority
		1502	Event->io (fd => IO::AIO::poll_fileno,
		1503	poll => 'r', nice => 1,
		1504	cb => &IO::AIO::poll_cb);
		1505
		1506	=back
		1507
		1508	=head3 CONTROLLING THE NUMBER OF THREADS
		1509
		1510	=over
810		1511
811	=item IO::AIO::min_parallel $nthreads	1512	=item IO::AIO::min_parallel $nthreads
812		1513
813	Set the minimum number of AIO threads to C<$nthreads>. The current	1514	Set the minimum number of AIO threads to C<$nthreads>. The current
814	default is C<8>, which means eight asynchronous operations can execute	1515	default is C<8>, which means eight asynchronous operations can execute
815	concurrently at any one time (the number of outstanding requests,	1516	concurrently at any one time (the number of outstanding requests,
816	however, is unlimited).	1517	however, is unlimited).
817		1518
818	IO::AIO starts threads only on demand, when an AIO request is queued and	1519	IO::AIO starts threads only on demand, when an AIO request is queued and
819	no free thread exists.	1520	no free thread exists. Please note that queueing up a hundred requests can
		1521	create demand for a hundred threads, even if it turns out that everything
		1522	is in the cache and could have been processed faster by a single thread.
820		1523
821	It is recommended to keep the number of threads relatively low, as some	1524	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	1525	Linux kernel versions will scale negatively with the number of threads
823	(higher parallelity => MUCH higher latency). With current Linux 2.6	1526	(higher parallelity => MUCH higher latency). With current Linux 2.6
824	versions, 4-32 threads should be fine.	1527	versions, 4-32 threads should be fine.
…		…
838	This module automatically runs C<max_parallel 0> at program end, to ensure	1541	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.	1542	that all threads are killed and that there are no outstanding requests.
840		1543
841	Under normal circumstances you don't need to call this function.	1544	Under normal circumstances you don't need to call this function.
842		1545
		1546	=item IO::AIO::max_idle $nthreads
		1547
		1548	Limit the number of threads (default: 4) that are allowed to idle
		1549	(i.e., threads that did not get a request to process within the idle
		1550	timeout (default: 10 seconds). That means if a thread becomes idle while
		1551	C<$nthreads> other threads are also idle, it will free its resources and
		1552	exit.
		1553
		1554	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1555	to allow for extremely high load situations, but want to free resources
		1556	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1557
		1558	The default is probably ok in most situations, especially if thread
		1559	creation is fast. If thread creation is very slow on your system you might
		1560	want to use larger values.
		1561
		1562	=item IO::AIO::idle_timeout $seconds
		1563
		1564	Sets the minimum idle timeout (default 10) after which worker threads are
		1565	allowed to exit. SEe C<IO::AIO::max_idle>.
		1566
843	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1567	=item IO::AIO::max_outstanding $maxreqs
844		1568
845	[DEPRECATED]	1569	This is a very bad function to use in interactive programs because it
		1570	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1571	use an C<aio_group> together with a feed callback.
846		1572
847	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1573	Sets the maximum number of outstanding requests to C<$nreqs>. If you
848	try to queue up more than this number of requests, the caller will block until	1574	do queue up more than this number of requests, the next call to the
849	some requests have been handled.	1575	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1576	function will block until the limit is no longer exceeded.
850		1577
851	The default is very large, so normally there is no practical limit. If you	1578	The default value is very large, so there is no practical limit on the
852	queue up many requests in a loop it often improves speed if you set	1579	number of outstanding requests.
853	this to a relatively low number, such as C<100>.
854		1580
855	This function does not work well together with C<aio_group>'s, and their	1581	You can still queue as many requests as you want. Therefore,
856	feeder interface is better suited to limiting concurrency, so do not use	1582	C<max_outstanding> is mainly useful in simple scripts (with low values) or
857	this function.	1583	as a stop gap to shield against fatal memory overflow (with large values).
858
859	Under normal circumstances you don't need to call this function.
860		1584
861	=back	1585	=back
862		1586
		1587	=head3 STATISTICAL INFORMATION
		1588
		1589	=over
		1590
		1591	=item IO::AIO::nreqs
		1592
		1593	Returns the number of requests currently in the ready, execute or pending
		1594	states (i.e. for which their callback has not been invoked yet).
		1595
		1596	Example: wait till there are no outstanding requests anymore:
		1597
		1598	IO::AIO::poll_wait, IO::AIO::poll_cb
		1599	while IO::AIO::nreqs;
		1600
		1601	=item IO::AIO::nready
		1602
		1603	Returns the number of requests currently in the ready state (not yet
		1604	executed).
		1605
		1606	=item IO::AIO::npending
		1607
		1608	Returns the number of requests currently in the pending state (executed,
		1609	but not yet processed by poll_cb).
		1610
		1611	=back
		1612
		1613	=head3 MISCELLANEOUS FUNCTIONS
		1614
		1615	IO::AIO implements some functions that might be useful, but are not
		1616	asynchronous.
		1617
		1618	=over 4
		1619
		1620	=item IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1621
		1622	Calls the C<eio_sendfile_sync> function, which is like C<aio_sendfile>,
		1623	but is blocking (this makes most sense if you know the input data is
		1624	likely cached already and the output filehandle is set to non-blocking
		1625	operations).
		1626
		1627	Returns the number of bytes copied, or C<-1> on error.
		1628
		1629	=item IO::AIO::fadvise $fh, $offset, $len, $advice
		1630
		1631	Simply calls the C<posix_fadvise> function (see its
		1632	manpage for details). The following advice constants are
		1633	avaiable: C<IO::AIO::FADV_NORMAL>, C<IO::AIO::FADV_SEQUENTIAL>,
		1634	C<IO::AIO::FADV_RANDOM>, C<IO::AIO::FADV_NOREUSE>,
		1635	C<IO::AIO::FADV_WILLNEED>, C<IO::AIO::FADV_DONTNEED>.
		1636
		1637	On systems that do not implement C<posix_fadvise>, this function returns
		1638	ENOSYS, otherwise the return value of C<posix_fadvise>.
		1639
		1640	=item IO::AIO::madvise $scalar, $offset, $len, $advice
		1641
		1642	Simply calls the C<posix_madvise> function (see its
		1643	manpage for details). The following advice constants are
		1644	avaiable: C<IO::AIO::MADV_NORMAL>, C<IO::AIO::MADV_SEQUENTIAL>,
		1645	C<IO::AIO::MADV_RANDOM>, C<IO::AIO::MADV_WILLNEED>, C<IO::AIO::MADV_DONTNEED>.
		1646
		1647	On systems that do not implement C<posix_madvise>, this function returns
		1648	ENOSYS, otherwise the return value of C<posix_madvise>.
		1649
		1650	=item IO::AIO::mprotect $scalar, $offset, $len, $protect
		1651
		1652	Simply calls the C<mprotect> function on the preferably AIO::mmap'ed
		1653	$scalar (see its manpage for details). The following protect
		1654	constants are avaiable: C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_READ>,
		1655	C<IO::AIO::PROT_WRITE>, C<IO::AIO::PROT_EXEC>.
		1656
		1657	On systems that do not implement C<mprotect>, this function returns
		1658	ENOSYS, otherwise the return value of C<mprotect>.
		1659
		1660	=item IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1661
		1662	Memory-maps a file (or anonymous memory range) and attaches it to the
		1663	given C<$scalar>, which will act like a string scalar.
		1664
		1665	The only operations allowed on the scalar are C<substr>/C<vec> that don't
		1666	change the string length, and most read-only operations such as copying it
		1667	or searching it with regexes and so on.
		1668
		1669	Anything else is unsafe and will, at best, result in memory leaks.
		1670
		1671	The memory map associated with the C<$scalar> is automatically removed
		1672	when the C<$scalar> is destroyed, or when the C<IO::AIO::mmap> or
		1673	C<IO::AIO::munmap> functions are called.
		1674
		1675	This calls the C<mmap>(2) function internally. See your system's manual
		1676	page for details on the C<$length>, C<$prot> and C<$flags> parameters.
		1677
		1678	The C<$length> must be larger than zero and smaller than the actual
		1679	filesize.
		1680
		1681	C<$prot> is a combination of C<IO::AIO::PROT_NONE>, C<IO::AIO::PROT_EXEC>,
		1682	C<IO::AIO::PROT_READ> and/or C<IO::AIO::PROT_WRITE>,
		1683
		1684	C<$flags> can be a combination of C<IO::AIO::MAP_SHARED> or
		1685	C<IO::AIO::MAP_PRIVATE>, or a number of system-specific flags (when
		1686	not available, the are defined as 0): C<IO::AIO::MAP_ANONYMOUS>
		1687	(which is set to C<MAP_ANON> if your system only provides this
		1688	constant), C<IO::AIO::MAP_HUGETLB>, C<IO::AIO::MAP_LOCKED>,
		1689	C<IO::AIO::MAP_NORESERVE>, C<IO::AIO::MAP_POPULATE> or
		1690	C<IO::AIO::MAP_NONBLOCK>
		1691
		1692	If C<$fh> is C<undef>, then a file descriptor of C<-1> is passed.
		1693
		1694	C<$offset> is the offset from the start of the file - it generally must be
		1695	a multiple of C<IO::AIO::PAGESIZE> and defaults to C<0>.
		1696
		1697	Example:
		1698
		1699	use Digest::MD5;
		1700	use IO::AIO;
		1701
		1702	open my $fh, "<verybigfile"
		1703	or die "$!";
		1704
		1705	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1706	or die "verybigfile: $!";
		1707
		1708	my $fast_md5 = md5 $data;
		1709
		1710	=item IO::AIO::munmap $scalar
		1711
		1712	Removes a previous mmap and undefines the C<$scalar>.
		1713
		1714	=item IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1715
		1716	Calls the C<munlock> function, undoing the effects of a previous
		1717	C<aio_mlock> call (see its description for details).
		1718
		1719	=item IO::AIO::munlockall
		1720
		1721	Calls the C<munlockall> function.
		1722
		1723	On systems that do not implement C<munlockall>, this function returns
		1724	ENOSYS, otherwise the return value of C<munlockall>.
		1725
		1726	=back
		1727
863	=cut	1728	=cut
864		1729
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;	1730	min_parallel 8;
882		1731
883	END {	1732	END { flush }
884	max_parallel 0;
885	}
886		1733
887	1;	1734	1;
		1735
		1736	=head1 EVENT LOOP INTEGRATION
		1737
		1738	It is recommended to use L<AnyEvent::AIO> to integrate IO::AIO
		1739	automatically into many event loops:
		1740
		1741	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1742	use AnyEvent::AIO;
		1743
		1744	You can also integrate IO::AIO manually into many event loops, here are
		1745	some examples of how to do this:
		1746
		1747	# EV integration
		1748	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1749
		1750	# Event integration
		1751	Event->io (fd => IO::AIO::poll_fileno,
		1752	poll => 'r',
		1753	cb => \&IO::AIO::poll_cb);
		1754
		1755	# Glib/Gtk2 integration
		1756	add_watch Glib::IO IO::AIO::poll_fileno,
		1757	in => sub { IO::AIO::poll_cb; 1 };
		1758
		1759	# Tk integration
		1760	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1761	readable => \&IO::AIO::poll_cb);
		1762
		1763	# Danga::Socket integration
		1764	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1765	\&IO::AIO::poll_cb);
888		1766
889	=head2 FORK BEHAVIOUR	1767	=head2 FORK BEHAVIOUR
890		1768
891	This module should do "the right thing" when the process using it forks:	1769	This module should do "the right thing" when the process using it forks:
892		1770
893	Before the fork, IO::AIO enters a quiescent state where no requests	1771	Before the fork, IO::AIO enters a quiescent state where no requests
894	can be added in other threads and no results will be processed. After	1772	can be added in other threads and no results will be processed. After
895	the fork the parent simply leaves the quiescent state and continues	1773	the fork the parent simply leaves the quiescent state and continues
896	request/result processing, while the child clears the request/result	1774	request/result processing, while the child frees the request/result queue
897	queue (so the requests started before the fork will only be handled in	1775	(so that the requests started before the fork will only be handled in the
898	the parent). Threads will be started on demand until the limit ste in the	1776	parent). Threads will be started on demand until the limit set in the
899	parent process has been reached again.	1777	parent process has been reached again.
900		1778
901	In short: the parent will, after a short pause, continue as if fork had	1779	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	1780	not been called, while the child will act as if IO::AIO has not been used
903	yet.	1781	yet.
904		1782
905	=head2 MEMORY USAGE	1783	=head2 MEMORY USAGE
906		1784
		1785	Per-request usage:
		1786
907	Each aio request uses - depending on your architecture - around 128 bytes	1787	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	1788	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	1789	a few hundred bytes), readdir requires a result buffer and so on. Perl
910	also be locked.	1790	scalars and other data passed into aio requests will also be locked and
		1791	will consume memory till the request has entered the done state.
911		1792
912	This is now awfully much, so queuing lots of requests is not usually a	1793	This is not awfully much, so queuing lots of requests is not usually a
913	problem.	1794	problem.
914		1795
915	Each thread needs a stack area which is usually around 16k, sometimes much	1796	Per-thread usage:
916	larger, depending on the OS.	1797
		1798	In the execution phase, some aio requests require more memory for
		1799	temporary buffers, and each thread requires a stack and other data
		1800	structures (usually around 16k-128k, depending on the OS).
		1801
		1802	=head1 KNOWN BUGS
		1803
		1804	Known bugs will be fixed in the next release.
917		1805
918	=head1 SEE ALSO	1806	=head1 SEE ALSO
919		1807
920	L<Coro::AIO>.	1808	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1809	more natural syntax.
921		1810
922	=head1 AUTHOR	1811	=head1 AUTHOR
923		1812
924	Marc Lehmann <schmorp@schmorp.de>	1813	Marc Lehmann <schmorp@schmorp.de>
925	http://home.schmorp.de/	1814	http://home.schmorp.de/

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