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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC vs.
Revision 1.156 by root, Tue Jun 16 23:41:59 2009 UTC

…		…
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", O_RDONLY, 0, sub {
10	my ($fh) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
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
		31	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		32	use AnyEvent::AIO;
		33
30	# AnyEvent integration	34	# EV integration
31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	35	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
33		36
34	# Event integration	37	# Event integration
35	Event->io (fd => IO::AIO::poll_fileno,	38	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',	39	poll => 'r',
37	cb => \&IO::AIO::poll_cb);	40	cb => \&IO::AIO::poll_cb);
…		…
49	\&IO::AIO::poll_cb);	52	\&IO::AIO::poll_cb);
50		53
51	=head1 DESCRIPTION	54	=head1 DESCRIPTION
52		55
53	This module implements asynchronous I/O using whatever means your	56	This module implements asynchronous I/O using whatever means your
54	operating system supports.	57	operating system supports. It is implemented as an interface to C<libeio>
		58	(L<http://software.schmorp.de/pkg/libeio.html>).
		59
		60	Asynchronous means that operations that can normally block your program
		61	(e.g. reading from disk) will be done asynchronously: the operation
		62	will still block, but you can do something else in the meantime. This
		63	is extremely useful for programs that need to stay interactive even
		64	when doing heavy I/O (GUI programs, high performance network servers
		65	etc.), but can also be used to easily do operations in parallel that are
		66	normally done sequentially, e.g. stat'ing many files, which is much faster
		67	on a RAID volume or over NFS when you do a number of stat operations
		68	concurrently.
		69
		70	While most of this works on all types of file descriptors (for
		71	example sockets), using these functions on file descriptors that
		72	support nonblocking operation (again, sockets, pipes etc.) is
		73	very inefficient. Use an event loop for that (such as the L<EV>
		74	module): IO::AIO will naturally fit into such an event loop itself.
55		75
56	In this version, a number of threads are started that execute your	76	In this version, a number of threads are started that execute your
57	requests and signal their completion. You don't need thread support	77	requests and signal their completion. You don't need thread support
58	in perl, and the threads created by this module will not be visible	78	in perl, and the threads created by this module will not be visible
59	to perl. In the future, this module might make use of the native aio	79	to perl. In the future, this module might make use of the native aio
60	functions available on many operating systems. However, they are often	80	functions available on many operating systems. However, they are often
61	not well-supported or restricted (Linux doesn't allow them on normal	81	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	files currently, for example), and they would only support aio_read and	82	files currently, for example), and they would only support aio_read and
63	aio_write, so the remaining functionality would have to be implemented	83	aio_write, so the remaining functionality would have to be implemented
64	using threads anyway.	84	using threads anyway.
65		85
66	Although the module will work with in the presence of other (Perl-)	86	Although the module will work in the presence of other (Perl-) threads,
67	threads, it is currently not reentrant in any way, so use appropriate	87	it is currently not reentrant in any way, so use appropriate locking
68	locking yourself, always call C<poll_cb> from within the same thread, or	88	yourself, always call C<poll_cb> from within the same thread, or never
69	never call C<poll_cb> (or other C<aio_> functions) recursively.	89	call C<poll_cb> (or other C<aio_> functions) recursively.
		90
		91	=head2 EXAMPLE
		92
		93	This is a simple example that uses the EV module and loads
		94	F</etc/passwd> asynchronously:
		95
		96	use Fcntl;
		97	use EV;
		98	use IO::AIO;
		99
		100	# register the IO::AIO callback with EV
		101	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		102
		103	# queue the request to open /etc/passwd
		104	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		105	my $fh = shift
		106	or die "error while opening: $!";
		107
		108	# stat'ing filehandles is generally non-blocking
		109	my $size = -s $fh;
		110
		111	# queue a request to read the file
		112	my $contents;
		113	aio_read $fh, 0, $size, $contents, 0, sub {
		114	$_[0] == $size
		115	or die "short read: $!";
		116
		117	close $fh;
		118
		119	# file contents now in $contents
		120	print $contents;
		121
		122	# exit event loop and program
		123	EV::unloop;
		124	};
		125	};
		126
		127	# possibly queue up other requests, or open GUI windows,
		128	# check for sockets etc. etc.
		129
		130	# process events as long as there are some:
		131	EV::loop;
70		132
71	=head1 REQUEST ANATOMY AND LIFETIME	133	=head1 REQUEST ANATOMY AND LIFETIME
72		134
73	Every C<aio_*> function creates a request. which is a C data structure not	135	Every C<aio_*> function creates a request. which is a C data structure not
74	directly visible to Perl.	136	directly visible to Perl.
…		…
116	Request has reached the end of its lifetime and holds no resources anymore	178	Request has reached the end of its lifetime and holds no resources anymore
117	(except possibly for the Perl object, but its connection to the actual	179	(except possibly for the Perl object, but its connection to the actual
118	aio request is severed and calling its methods will either do nothing or	180	aio request is severed and calling its methods will either do nothing or
119	result in a runtime error).	181	result in a runtime error).
120		182
		183	=back
		184
121	=cut	185	=cut
122		186
123	package IO::AIO;	187	package IO::AIO;
		188
		189	use Carp ();
124		190
125	no warnings;	191	no warnings;
126	use strict 'vars';	192	use strict 'vars';
127		193
128	use base 'Exporter';	194	use base 'Exporter';
129		195
130	BEGIN {	196	BEGIN {
131	our $VERSION = '2.0';	197	our $VERSION = '3.23';
132		198
133	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	199	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close
134	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	200	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir aio_readdirx
135	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	201	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
136	aio_copy aio_group aio_nop aio_mknod);	202	aio_fdatasync aio_sync_file_range aio_pathsync aio_readahead
		203	aio_rename aio_link aio_move aio_copy aio_group
		204	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		205	aio_chmod aio_utime aio_truncate);
		206
137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	207	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	208	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139	min_parallel max_parallel nreqs nready npending);	209	min_parallel max_parallel max_idle
		210	nreqs nready npending nthreads
		211	max_poll_time max_poll_reqs);
		212
		213	push @AIO_REQ, qw(aio_busy); # not exported
140		214
141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142		216
143	require XSLoader;	217	require XSLoader;
144	XSLoader::load ("IO::AIO", $VERSION);	218	XSLoader::load ("IO::AIO", $VERSION);
145	}	219	}
146		220
147	=head1 FUNCTIONS	221	=head1 FUNCTIONS
148		222
149	=head2 AIO FUNCTIONS	223	=head2 AIO REQUEST FUNCTIONS
150		224
151	All the C<aio_*> calls are more or less thin wrappers around the syscall	225	All the C<aio_*> calls are more or less thin wrappers around the syscall
152	with the same name (sans C<aio_>). The arguments are similar or identical,	226	with the same name (sans C<aio_>). The arguments are similar or identical,
153	and they all accept an additional (and optional) C<$callback> argument	227	and they all accept an additional (and optional) C<$callback> argument
154	which must be a code reference. This code reference will get called with	228	which must be a code reference. This code reference will get called with
155	the syscall return code (e.g. most syscalls return C<-1> on error, unlike	229	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
156	perl, which usually delivers "false") as it's sole argument when the given	230	perl, which usually delivers "false") as its sole argument after the given
157	syscall has been executed asynchronously.	231	syscall has been executed asynchronously.
158		232
159	All functions expecting a filehandle keep a copy of the filehandle	233	All functions expecting a filehandle keep a copy of the filehandle
160	internally until the request has finished.	234	internally until the request has finished.
161		235
162	All requests return objects of type L<IO::AIO::REQ> that allow further	236	All functions return request objects of type L<IO::AIO::REQ> that allow
163	manipulation of those requests while they are in-flight.	237	further manipulation of those requests while they are in-flight.
164		238
165	The pathnames you pass to these routines I<must> be absolute and	239	The pathnames you pass to these routines I<must> be absolute and
166	encoded in byte form. The reason for the former is that at the time the	240	encoded as octets. The reason for the former is that at the time the
167	request is being executed, the current working directory could have	241	request is being executed, the current working directory could have
168	changed. Alternatively, you can make sure that you never change the	242	changed. Alternatively, you can make sure that you never change the
169	current working directory.	243	current working directory anywhere in the program and then use relative
		244	paths.
170		245
171	To encode pathnames to byte form, either make sure you either: a)	246	To encode pathnames as octets, either make sure you either: a) always pass
172	always pass in filenames you got from outside (command line, readdir	247	in filenames you got from outside (command line, readdir etc.) without
173	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	248	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
174	your pathnames to the locale (or other) encoding in effect in the user	249	your pathnames to the locale (or other) encoding in effect in the user
175	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	250	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176	use something else.	251	use something else to ensure your scalar has the correct contents.
		252
		253	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		254	handles correctly whether it is set or not.
177		255
178	=over 4	256	=over 4
179		257
180	=item $prev_pri = aioreq_pri [$pri]	258	=item $prev_pri = aioreq_pri [$pri]
181		259
…		…
201	aio_read $_[0], ..., sub {	279	aio_read $_[0], ..., sub {
202	...	280	...
203	};	281	};
204	};	282	};
205		283
		284
206	=item aioreq_nice $pri_adjust	285	=item aioreq_nice $pri_adjust
207		286
208	Similar to C<aioreq_pri>, but subtracts the given value from the current	287	Similar to C<aioreq_pri>, but subtracts the given value from the current
209	priority, so effects are cumulative.	288	priority, so the effect is cumulative.
		289
210		290
211	=item aio_open $pathname, $flags, $mode, $callback->($fh)	291	=item aio_open $pathname, $flags, $mode, $callback->($fh)
212		292
213	Asynchronously open or create a file and call the callback with a newly	293	Asynchronously open or create a file and call the callback with a newly
214	created filehandle for the file.	294	created filehandle for the file.
…		…
220	list. They are the same as used by C<sysopen>.	300	list. They are the same as used by C<sysopen>.
221		301
222	Likewise, C<$mode> specifies the mode of the newly created file, if it	302	Likewise, C<$mode> specifies the mode of the newly created file, if it
223	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,	303	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
224	except that it is mandatory (i.e. use C<0> if you don't create new files,	304	except that it is mandatory (i.e. use C<0> if you don't create new files,
225	and C<0666> or C<0777> if you do).	305	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		306	by the umask in effect then the request is being executed, so better never
		307	change the umask.
226		308
227	Example:	309	Example:
228		310
229	aio_open "/etc/passwd", O_RDONLY, 0, sub {	311	aio_open "/etc/passwd", O_RDONLY, 0, sub {
230	if ($_[0]) {	312	if ($_[0]) {
…		…
233	} else {	315	} else {
234	die "open failed: $!\n";	316	die "open failed: $!\n";
235	}	317	}
236	};	318	};
237		319
		320
238	=item aio_close $fh, $callback->($status)	321	=item aio_close $fh, $callback->($status)
239		322
240	Asynchronously close a file and call the callback with the result	323	Asynchronously close a file and call the callback with the result
241	code. I<WARNING:> although accepted, you should not pass in a perl	324	code.
242	filehandle here, as perl will likely close the file descriptor another
243	time when the filehandle is destroyed. Normally, you can safely call perls
244	C<close> or just let filehandles go out of scope.
245		325
246	This is supposed to be a bug in the API, so that might change. It's	326	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
247	therefore best to avoid this function.	327	closing the file descriptor associated with the filehandle itself.
		328
		329	Therefore, C<aio_close> will not close the filehandle - instead it will
		330	use dup2 to overwrite the file descriptor with the write-end of a pipe
		331	(the pipe fd will be created on demand and will be cached).
		332
		333	Or in other words: the file descriptor will be closed, but it will not be
		334	free for reuse until the perl filehandle is closed.
		335
		336	=cut
248		337
249	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	338	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
250		339
251	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	340	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
252		341
253	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	342	Reads or writes C<$length> bytes from or to the specified C<$fh> and
254	into the scalar given by C<data> and offset C<dataoffset> and calls the	343	C<$offset> into the scalar given by C<$data> and offset C<$dataoffset>
255	callback without the actual number of bytes read (or -1 on error, just	344	and calls the callback without the actual number of bytes read (or -1 on
256	like the syscall).	345	error, just like the syscall).
		346
		347	C<aio_read> will, like C<sysread>, shrink or grow the C<$data> scalar to
		348	offset plus the actual number of bytes read.
		349
		350	If C<$offset> is undefined, then the current file descriptor offset will
		351	be used (and updated), otherwise the file descriptor offset will not be
		352	changed by these calls.
		353
		354	If C<$length> is undefined in C<aio_write>, use the remaining length of
		355	C<$data>.
		356
		357	If C<$dataoffset> is less than zero, it will be counted from the end of
		358	C<$data>.
257		359
258	The C<$data> scalar I<MUST NOT> be modified in any way while the request	360	The C<$data> scalar I<MUST NOT> be modified in any way while the request
259	is outstanding. Modifying it can result in segfaults or WW3 (if the	361	is outstanding. Modifying it can result in segfaults or World War III (if
260	necessary/optional hardware is installed).	362	the necessary/optional hardware is installed).
261		363
262	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	364	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
263	offset C<0> within the scalar:	365	offset C<0> within the scalar:
264		366
265	aio_read $fh, 7, 15, $buffer, 0, sub {	367	aio_read $fh, 7, 15, $buffer, 0, sub {
266	$_[0] > 0 or die "read error: $!";	368	$_[0] > 0 or die "read error: $!";
267	print "read $_[0] bytes: <$buffer>\n";	369	print "read $_[0] bytes: <$buffer>\n";
268	};	370	};
		371
269		372
270	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	373	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
271		374
272	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	375	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
273	reading at byte offset C<$in_offset>, and starts writing at the current	376	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
287	C<$in_fh> than are written, and there is no way to find out how many	390	C<$in_fh> than are written, and there is no way to find out how many
288	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	391	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
289	provides the number of bytes written to C<$out_fh>. Only if the result	392	provides the number of bytes written to C<$out_fh>. Only if the result
290	value equals C<$length> one can assume that C<$length> bytes have been	393	value equals C<$length> one can assume that C<$length> bytes have been
291	read.	394	read.
		395
292		396
293	=item aio_readahead $fh,$offset,$length, $callback->($retval)	397	=item aio_readahead $fh,$offset,$length, $callback->($retval)
294		398
295	C<aio_readahead> populates the page cache with data from a file so that	399	C<aio_readahead> populates the page cache with data from a file so that
296	subsequent reads from that file will not block on disk I/O. The C<$offset>	400	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
302	file. The current file offset of the file is left unchanged.	406	file. The current file offset of the file is left unchanged.
303		407
304	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	408	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
305	emulated by simply reading the data, which would have a similar effect.	409	emulated by simply reading the data, which would have a similar effect.
306		410
		411
307	=item aio_stat $fh_or_path, $callback->($status)	412	=item aio_stat $fh_or_path, $callback->($status)
308		413
309	=item aio_lstat $fh, $callback->($status)	414	=item aio_lstat $fh, $callback->($status)
310		415
311	Works like perl's C<stat> or C<lstat> in void context. The callback will	416	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
324	aio_stat "/etc/passwd", sub {	429	aio_stat "/etc/passwd", sub {
325	$_[0] and die "stat failed: $!";	430	$_[0] and die "stat failed: $!";
326	print "size is ", -s _, "\n";	431	print "size is ", -s _, "\n";
327	};	432	};
328		433
		434
		435	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		436
		437	Works like perl's C<utime> function (including the special case of $atime
		438	and $mtime being undef). Fractional times are supported if the underlying
		439	syscalls support them.
		440
		441	When called with a pathname, uses utimes(2) if available, otherwise
		442	utime(2). If called on a file descriptor, uses futimes(2) if available,
		443	otherwise returns ENOSYS, so this is not portable.
		444
		445	Examples:
		446
		447	# set atime and mtime to current time (basically touch(1)):
		448	aio_utime "path", undef, undef;
		449	# set atime to current time and mtime to beginning of the epoch:
		450	aio_utime "path", time, undef; # undef==0
		451
		452
		453	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		454
		455	Works like perl's C<chown> function, except that C<undef> for either $uid
		456	or $gid is being interpreted as "do not change" (but -1 can also be used).
		457
		458	Examples:
		459
		460	# same as "chown root path" in the shell:
		461	aio_chown "path", 0, -1;
		462	# same as above:
		463	aio_chown "path", 0, undef;
		464
		465
		466	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		467
		468	Works like truncate(2) or ftruncate(2).
		469
		470
		471	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		472
		473	Works like perl's C<chmod> function.
		474
		475
329	=item aio_unlink $pathname, $callback->($status)	476	=item aio_unlink $pathname, $callback->($status)
330		477
331	Asynchronously unlink (delete) a file and call the callback with the	478	Asynchronously unlink (delete) a file and call the callback with the
332	result code.	479	result code.
333		480
		481
334	=item aio_mknod $path, $mode, $dev, $callback->($status)	482	=item aio_mknod $path, $mode, $dev, $callback->($status)
335		483
		484	[EXPERIMENTAL]
		485
336	Asynchronously create a device node (or fifo). See mknod(2): the only	486	Asynchronously create a device node (or fifo). See mknod(2).
337	portable value for C<$mode> is C<S_IFIFO> ored with permissions, and C<0>	487
338	for C<$dev>.	488	The only (POSIX-) portable way of calling this function is:
		489
		490	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		491
339		492
340	=item aio_link $srcpath, $dstpath, $callback->($status)	493	=item aio_link $srcpath, $dstpath, $callback->($status)
341		494
342	Asynchronously create a new link to the existing object at C<$srcpath> at	495	Asynchronously create a new link to the existing object at C<$srcpath> at
343	the path C<$dstpath> and call the callback with the result code.	496	the path C<$dstpath> and call the callback with the result code.
344		497
		498
345	=item aio_symlink $srcpath, $dstpath, $callback->($status)	499	=item aio_symlink $srcpath, $dstpath, $callback->($status)
346		500
347	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	501	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
348	the path C<$dstpath> and call the callback with the result code.	502	the path C<$dstpath> and call the callback with the result code.
349		503
		504
		505	=item aio_readlink $path, $callback->($link)
		506
		507	Asynchronously read the symlink specified by C<$path> and pass it to
		508	the callback. If an error occurs, nothing or undef gets passed to the
		509	callback.
		510
		511
350	=item aio_rename $srcpath, $dstpath, $callback->($status)	512	=item aio_rename $srcpath, $dstpath, $callback->($status)
351		513
352	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	514	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
353	rename(2) and call the callback with the result code.	515	rename(2) and call the callback with the result code.
354		516
		517
		518	=item aio_mkdir $pathname, $mode, $callback->($status)
		519
		520	Asynchronously mkdir (create) a directory and call the callback with
		521	the result code. C<$mode> will be modified by the umask at the time the
		522	request is executed, so do not change your umask.
		523
		524
355	=item aio_rmdir $pathname, $callback->($status)	525	=item aio_rmdir $pathname, $callback->($status)
356		526
357	Asynchronously rmdir (delete) a directory and call the callback with the	527	Asynchronously rmdir (delete) a directory and call the callback with the
358	result code.	528	result code.
		529
359		530
360	=item aio_readdir $pathname, $callback->($entries)	531	=item aio_readdir $pathname, $callback->($entries)
361		532
362	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	533	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
363	directory (i.e. opendir + readdir + closedir). The entries will not be	534	directory (i.e. opendir + readdir + closedir). The entries will not be
364	sorted, and will B<NOT> include the C<.> and C<..> entries.	535	sorted, and will B<NOT> include the C<.> and C<..> entries.
365		536
366	The callback a single argument which is either C<undef> or an array-ref	537	The callback is passed a single argument which is either C<undef> or an
367	with the filenames.	538	array-ref with the filenames.
		539
		540
		541	=item aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		542
		543	Quite similar to C<aio_readdir>, but the C<$flags> argument allows to tune
		544	behaviour and output format. In case of an error, C<$entries> will be
		545	C<undef>.
		546
		547	The flags are a combination of the following constants, ORed together (the
		548	flags will also be passed to the callback, possibly modified):
		549
		550	=over 4
		551
		552	=item IO::AIO::READDIR_DENTS
		553
		554	When this flag is off, then the callback gets an arrayref with of names
		555	only (as with C<aio_readdir>), otherwise it gets an arrayref with
		556	C<[$name, $type, $inode]> arrayrefs, each describing a single directory
		557	entry in more detail.
		558
		559	C<$name> is the name of the entry.
		560
		561	C<$type> is one of the C<IO::AIO::DT_xxx> constants:
		562
		563	C<IO::AIO::DT_UNKNOWN>, C<IO::AIO::DT_FIFO>, C<IO::AIO::DT_CHR>, C<IO::AIO::DT_DIR>,
		564	C<IO::AIO::DT_BLK>, C<IO::AIO::DT_REG>, C<IO::AIO::DT_LNK>, C<IO::AIO::DT_SOCK>,
		565	C<IO::AIO::DT_WHT>.
		566
		567	C<IO::AIO::DT_UNKNOWN> means just that: readdir does not know. If you need to
		568	know, you have to run stat yourself. Also, for speed reasons, the C<$type>
		569	scalars are read-only: you can not modify them.
		570
		571	C<$inode> is the inode number (which might not be exact on systems with 64
		572	bit inode numbers and 32 bit perls). This field has unspecified content on
		573	systems that do not deliver the inode information.
		574
		575	=item IO::AIO::READDIR_DIRS_FIRST
		576
		577	When this flag is set, then the names will be returned in an order where
		578	likely directories come first. This is useful when you need to quickly
		579	find directories, or you want to find all directories while avoiding to
		580	stat() each entry.
		581
		582	If the system returns type information in readdir, then this is used
		583	to find directories directly. Otherwise, likely directories are files
		584	beginning with ".", or otherwise files with no dots, of which files with
		585	short names are tried first.
		586
		587	=item IO::AIO::READDIR_STAT_ORDER
		588
		589	When this flag is set, then the names will be returned in an order
		590	suitable for stat()'ing each one. That is, when you plan to stat()
		591	all files in the given directory, then the returned order will likely
		592	be fastest.
		593
		594	If both this flag and C<IO::AIO::READDIR_DIRS_FIRST> are specified, then
		595	the likely dirs come first, resulting in a less optimal stat order.
		596
		597	=item IO::AIO::READDIR_FOUND_UNKNOWN
		598
		599	This flag should not be set when calling C<aio_readdirx>. Instead, it
		600	is being set by C<aio_readdirx>, when any of the C<$type>'s found were
		601	C<IO::AIO::DT_UNKNOWN>. The absense of this flag therefore indicates that all
		602	C<$type>'s are known, which can be used to speed up some algorithms.
		603
		604	=back
		605
		606
		607	=item aio_load $path, $data, $callback->($status)
		608
		609	This is a composite request that tries to fully load the given file into
		610	memory. Status is the same as with aio_read.
		611
		612	=cut
		613
		614	sub aio_load($$;$) {
		615	my ($path, undef, $cb) = @_;
		616	my $data = \$_[1];
		617
		618	my $pri = aioreq_pri;
		619	my $grp = aio_group $cb;
		620
		621	aioreq_pri $pri;
		622	add $grp aio_open $path, O_RDONLY, 0, sub {
		623	my $fh = shift
		624	or return $grp->result (-1);
		625
		626	aioreq_pri $pri;
		627	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		628	$grp->result ($_[0]);
		629	};
		630	};
		631
		632	$grp
		633	}
368		634
369	=item aio_copy $srcpath, $dstpath, $callback->($status)	635	=item aio_copy $srcpath, $dstpath, $callback->($status)
370		636
371	Try to copy the I<file> (directories not supported as either source or	637	Try to copy the I<file> (directories not supported as either source or
372	destination) from C<$srcpath> to C<$dstpath> and call the callback with	638	destination) from C<$srcpath> to C<$dstpath> and call the callback with
373	the C<0> (error) or C<-1> ok.	639	the C<0> (error) or C<-1> ok.
374		640
375	This is a composite request that it creates the destination file with	641	This is a composite request that creates the destination file with
376	mode 0200 and copies the contents of the source file into it using	642	mode 0200 and copies the contents of the source file into it using
377	C<aio_sendfile>, followed by restoring atime, mtime, access mode and	643	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
378	uid/gid, in that order.	644	uid/gid, in that order.
379		645
380	If an error occurs, the partial destination file will be unlinked, if	646	If an error occurs, the partial destination file will be unlinked, if
…		…
390	my $grp = aio_group $cb;	656	my $grp = aio_group $cb;
391		657
392	aioreq_pri $pri;	658	aioreq_pri $pri;
393	add $grp aio_open $src, O_RDONLY, 0, sub {	659	add $grp aio_open $src, O_RDONLY, 0, sub {
394	if (my $src_fh = $_[0]) {	660	if (my $src_fh = $_[0]) {
395	my @stat = stat $src_fh;	661	my @stat = stat $src_fh; # hmm, might bock over nfs?
396		662
397	aioreq_pri $pri;	663	aioreq_pri $pri;
398	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {	664	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
399	if (my $dst_fh = $_[0]) {	665	if (my $dst_fh = $_[0]) {
400	aioreq_pri $pri;	666	aioreq_pri $pri;
401	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	667	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
402	if ($_[0] == $stat[7]) {	668	if ($_[0] == $stat[7]) {
403	$grp->result (0);	669	$grp->result (0);
404	close $src_fh;	670	close $src_fh;
405		671
406	# those should not normally block. should. should.	672	my $ch = sub {
		673	aioreq_pri $pri;
		674	add $grp aio_chmod $dst_fh, $stat[2] & 07777, sub {
		675	aioreq_pri $pri;
		676	add $grp aio_chown $dst_fh, $stat[4], $stat[5], sub {
		677	aioreq_pri $pri;
		678	add $grp aio_close $dst_fh;
		679	}
		680	};
		681	};
		682
		683	aioreq_pri $pri;
		684	add $grp aio_utime $dst_fh, $stat[8], $stat[9], sub {
		685	if ($_[0] < 0 && $! == ENOSYS) {
		686	aioreq_pri $pri;
407	utime $stat[8], $stat[9], $dst;	687	add $grp aio_utime $dst, $stat[8], $stat[9], $ch;
408	chmod $stat[2] & 07777, $dst_fh;	688	} else {
409	chown $stat[4], $stat[5], $dst_fh;	689	$ch->();
		690	}
410	close $dst_fh;	691	};
411	} else {	692	} else {
412	$grp->result (-1);	693	$grp->result (-1);
413	close $src_fh;	694	close $src_fh;
414	close $dst_fh;	695	close $dst_fh;
415		696
…		…
434		715
435	Try to move the I<file> (directories not supported as either source or	716	Try to move the I<file> (directories not supported as either source or
436	destination) from C<$srcpath> to C<$dstpath> and call the callback with	717	destination) from C<$srcpath> to C<$dstpath> and call the callback with
437	the C<0> (error) or C<-1> ok.	718	the C<0> (error) or C<-1> ok.
438		719
439	This is a composite request that tries to rename(2) the file first. If	720	This is a composite request that tries to rename(2) the file first; if
440	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if	721	rename fails with C<EXDEV>, it copies the file with C<aio_copy> and, if
441	that is successful, unlinking the C<$srcpath>.	722	that is successful, unlinks the C<$srcpath>.
442		723
443	=cut	724	=cut
444		725
445	sub aio_move($$;$) {	726	sub aio_move($$;$) {
446	my ($src, $dst, $cb) = @_;	727	my ($src, $dst, $cb) = @_;
…		…
493		774
494	Implementation notes.	775	Implementation notes.
495		776
496	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	777	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
497		778
		779	If readdir returns file type information, then this is used directly to
		780	find directories.
		781
498	After reading the directory, the modification time, size etc. of the	782	Otherwise, after reading the directory, the modification time, size etc.
499	directory before and after the readdir is checked, and if they match (and	783	of the directory before and after the readdir is checked, and if they
500	isn't the current time), the link count will be used to decide how many	784	match (and isn't the current time), the link count will be used to decide
501	entries are directories (if >= 2). Otherwise, no knowledge of the number	785	how many entries are directories (if >= 2). Otherwise, no knowledge of the
502	of subdirectories will be assumed.	786	number of subdirectories will be assumed.
503		787
504	Then entries will be sorted into likely directories (everything without	788	Then entries will be sorted into likely directories a non-initial dot
505	a non-initial dot currently) and likely non-directories (everything	789	currently) and likely non-directories (see C<aio_readdirx>). Then every
506	else). Then every entry plus an appended C</.> will be C<stat>'ed,	790	entry plus an appended C</.> will be C<stat>'ed, likely directories first,
507	likely directories first. If that succeeds, it assumes that the entry	791	in order of their inode numbers. If that succeeds, it assumes that the
508	is a directory or a symlink to directory (which will be checked	792	entry is a directory or a symlink to directory (which will be checked
509	seperately). This is often faster than stat'ing the entry itself because	793	seperately). This is often faster than stat'ing the entry itself because
510	filesystems might detect the type of the entry without reading the inode	794	filesystems might detect the type of the entry without reading the inode
511	data (e.g. ext2fs filetype feature).	795	data (e.g. ext2fs filetype feature), even on systems that cannot return
		796	the filetype information on readdir.
512		797
513	If the known number of directories (link count - 2) has been reached, the	798	If the known number of directories (link count - 2) has been reached, the
514	rest of the entries is assumed to be non-directories.	799	rest of the entries is assumed to be non-directories.
515		800
516	This only works with certainty on POSIX (= UNIX) filesystems, which	801	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
520	as those tend to return 0 or 1 as link counts, which disables the	805	as those tend to return 0 or 1 as link counts, which disables the
521	directory counting heuristic.	806	directory counting heuristic.
522		807
523	=cut	808	=cut
524		809
525	sub aio_scandir($$$) {	810	sub aio_scandir($$;$) {
526	my ($path, $maxreq, $cb) = @_;	811	my ($path, $maxreq, $cb) = @_;
527		812
528	my $pri = aioreq_pri;	813	my $pri = aioreq_pri;
529		814
530	my $grp = aio_group $cb;	815	my $grp = aio_group $cb;
…		…
538	my $now = time;	823	my $now = time;
539	my $hash1 = join ":", (stat _)[0,1,3,7,9];	824	my $hash1 = join ":", (stat _)[0,1,3,7,9];
540		825
541	# read the directory entries	826	# read the directory entries
542	aioreq_pri $pri;	827	aioreq_pri $pri;
543	add $grp aio_readdir $path, sub {	828	add $grp aio_readdirx $path, READDIR_DIRS_FIRST, sub {
544	my $entries = shift	829	my $entries = shift
545	or return $grp->result ();	830	or return $grp->result ();
546		831
547	# stat the dir another time	832	# stat the dir another time
548	aioreq_pri $pri;	833	aioreq_pri $pri;
…		…
554	# take the slow route if anything looks fishy	839	# take the slow route if anything looks fishy
555	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	840	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
556	$ndirs = -1;	841	$ndirs = -1;
557	} else {	842	} else {
558	# if nlink == 2, we are finished	843	# if nlink == 2, we are finished
559	# on non-posix-fs's, we rely on nlink < 2	844	# for non-posix-fs's, we rely on nlink < 2
560	$ndirs = (stat _)[3] - 2	845	$ndirs = (stat _)[3] - 2
561	or return $grp->result ([], $entries);	846	or return $grp->result ([], $entries);
562	}	847	}
563		848
564	# sort into likely dirs and likely nondirs
565	# dirs == files without ".", short entries first
566	$entries = [map $_->[0],
567	sort { $b->[1] cmp $a->[1] }
568	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
569	@$entries];
570
571	my (@dirs, @nondirs);	849	my (@dirs, @nondirs);
572		850
573	my $statgrp = add $grp aio_group sub {	851	my $statgrp = add $grp aio_group sub {
574	$grp->result (\@dirs, \@nondirs);	852	$grp->result (\@dirs, \@nondirs);
575	};	853	};
576		854
577	limit $statgrp $maxreq;	855	limit $statgrp $maxreq;
578	feed $statgrp sub {	856	feed $statgrp sub {
579	return unless @$entries;	857	return unless @$entries;
580	my $entry = pop @$entries;	858	my $entry = shift @$entries;
581		859
582	aioreq_pri $pri;	860	aioreq_pri $pri;
583	add $statgrp aio_stat "$path/$entry/.", sub {	861	add $statgrp aio_stat "$path/$entry/.", sub {
584	if ($_[0] < 0) {	862	if ($_[0] < 0) {
585	push @nondirs, $entry;	863	push @nondirs, $entry;
…		…
606	};	884	};
607		885
608	$grp	886	$grp
609	}	887	}
610		888
		889	=item aio_rmtree $path, $callback->($status)
		890
		891	Delete a directory tree starting (and including) C<$path>, return the
		892	status of the final C<rmdir> only. This is a composite request that
		893	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		894	everything else.
		895
		896	=cut
		897
		898	sub aio_rmtree;
		899	sub aio_rmtree($;$) {
		900	my ($path, $cb) = @_;
		901
		902	my $pri = aioreq_pri;
		903	my $grp = aio_group $cb;
		904
		905	aioreq_pri $pri;
		906	add $grp aio_scandir $path, 0, sub {
		907	my ($dirs, $nondirs) = @_;
		908
		909	my $dirgrp = aio_group sub {
		910	add $grp aio_rmdir $path, sub {
		911	$grp->result ($_[0]);
		912	};
		913	};
		914
		915	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		916	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		917
		918	add $grp $dirgrp;
		919	};
		920
		921	$grp
		922	}
		923
		924	=item aio_sync $callback->($status)
		925
		926	Asynchronously call sync and call the callback when finished.
		927
611	=item aio_fsync $fh, $callback->($status)	928	=item aio_fsync $fh, $callback->($status)
612		929
613	Asynchronously call fsync on the given filehandle and call the callback	930	Asynchronously call fsync on the given filehandle and call the callback
614	with the fsync result code.	931	with the fsync result code.
615		932
…		…
618	Asynchronously call fdatasync on the given filehandle and call the	935	Asynchronously call fdatasync on the given filehandle and call the
619	callback with the fdatasync result code.	936	callback with the fdatasync result code.
620		937
621	If this call isn't available because your OS lacks it or it couldn't be	938	If this call isn't available because your OS lacks it or it couldn't be
622	detected, it will be emulated by calling C<fsync> instead.	939	detected, it will be emulated by calling C<fsync> instead.
		940
		941	=item aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		942
		943	Sync the data portion of the file specified by C<$offset> and C<$length>
		944	to disk (but NOT the metadata), by calling the Linux-specific
		945	sync_file_range call. If sync_file_range is not available or it returns
		946	ENOSYS, then fdatasync or fsync is being substituted.
		947
		948	C<$flags> can be a combination of C<IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE>,
		949	C<IO::AIO::SYNC_FILE_RANGE_WRITE> and
		950	C<IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER>: refer to the sync_file_range
		951	manpage for details.
		952
		953	=item aio_pathsync $path, $callback->($status)
		954
		955	This request tries to open, fsync and close the given path. This is a
		956	composite request intended to sync directories after directory operations
		957	(E.g. rename). This might not work on all operating systems or have any
		958	specific effect, but usually it makes sure that directory changes get
		959	written to disc. It works for anything that can be opened for read-only,
		960	not just directories.
		961
		962	Passes C<0> when everything went ok, and C<-1> on error.
		963
		964	=cut
		965
		966	sub aio_pathsync($;$) {
		967	my ($path, $cb) = @_;
		968
		969	my $pri = aioreq_pri;
		970	my $grp = aio_group $cb;
		971
		972	aioreq_pri $pri;
		973	add $grp aio_open $path, O_RDONLY, 0, sub {
		974	my ($fh) = @_;
		975	if ($fh) {
		976	aioreq_pri $pri;
		977	add $grp aio_fsync $fh, sub {
		978	$grp->result ($_[0]);
		979
		980	aioreq_pri $pri;
		981	add $grp aio_close $fh;
		982	};
		983	} else {
		984	$grp->result (-1);
		985	}
		986	};
		987
		988	$grp
		989	}
623		990
624	=item aio_group $callback->(...)	991	=item aio_group $callback->(...)
625		992
626	This is a very special aio request: Instead of doing something, it is a	993	This is a very special aio request: Instead of doing something, it is a
627	container for other aio requests, which is useful if you want to bundle	994	container for other aio requests, which is useful if you want to bundle
…		…
677	=item cancel $req	1044	=item cancel $req
678		1045
679	Cancels the request, if possible. Has the effect of skipping execution	1046	Cancels the request, if possible. Has the effect of skipping execution
680	when entering the B<execute> state and skipping calling the callback when	1047	when entering the B<execute> state and skipping calling the callback when
681	entering the the B<result> state, but will leave the request otherwise	1048	entering the the B<result> state, but will leave the request otherwise
682	untouched. That means that requests that currently execute will not be	1049	untouched (with the exception of readdir). That means that requests that
683	stopped and resources held by the request will not be freed prematurely.	1050	currently execute will not be stopped and resources held by the request
		1051	will not be freed prematurely.
684		1052
685	=item cb $req $callback->(...)	1053	=item cb $req $callback->(...)
686		1054
687	Replace (or simply set) the callback registered to the request.	1055	Replace (or simply set) the callback registered to the request.
688		1056
…		…
739	Their lifetime, simplified, looks like this: when they are empty, they	1107	Their lifetime, simplified, looks like this: when they are empty, they
740	will finish very quickly. If they contain only requests that are in the	1108	will finish very quickly. If they contain only requests that are in the
741	C<done> state, they will also finish. Otherwise they will continue to	1109	C<done> state, they will also finish. Otherwise they will continue to
742	exist.	1110	exist.
743		1111
744	That means after creating a group you have some time to add requests. And	1112	That means after creating a group you have some time to add requests
745	in the callbacks of those requests, you can add further requests to the	1113	(precisely before the callback has been invoked, which is only done within
746	group. And only when all those requests have finished will the the group	1114	the C<poll_cb>). And in the callbacks of those requests, you can add
747	itself finish.	1115	further requests to the group. And only when all those requests have
		1116	finished will the the group itself finish.
748		1117
749	=over 4	1118	=over 4
750		1119
751	=item add $grp ...	1120	=item add $grp ...
752		1121
…		…
764	itself. Useful when you queued a lot of events but got a result early.	1133	itself. Useful when you queued a lot of events but got a result early.
765		1134
766	=item $grp->result (...)	1135	=item $grp->result (...)
767		1136
768	Set the result value(s) that will be passed to the group callback when all	1137	Set the result value(s) that will be passed to the group callback when all
769	subrequests have finished and set thre groups errno to the current value	1138	subrequests have finished and set the groups errno to the current value
770	of errno (just like calling C<errno> without an error number). By default,	1139	of errno (just like calling C<errno> without an error number). By default,
771	no argument will be passed and errno is zero.	1140	no argument will be passed and errno is zero.
772		1141
773	=item $grp->errno ([$errno])	1142	=item $grp->errno ([$errno])
774		1143
…		…
785	=item feed $grp $callback->($grp)	1154	=item feed $grp $callback->($grp)
786		1155
787	Sets a feeder/generator on this group: every group can have an attached	1156	Sets a feeder/generator on this group: every group can have an attached
788	generator that generates requests if idle. The idea behind this is that,	1157	generator that generates requests if idle. The idea behind this is that,
789	although you could just queue as many requests as you want in a group,	1158	although you could just queue as many requests as you want in a group,
790	this might starve other requests for a potentially long time. For	1159	this might starve other requests for a potentially long time. For example,
791	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1160	C<aio_scandir> might generate hundreds of thousands C<aio_stat> requests,
792	requests, delaying any later requests for a long time.	1161	delaying any later requests for a long time.
793		1162
794	To avoid this, and allow incremental generation of requests, you can	1163	To avoid this, and allow incremental generation of requests, you can
795	instead a group and set a feeder on it that generates those requests. The	1164	instead a group and set a feeder on it that generates those requests. The
796	feed callback will be called whenever there are few enough (see C<limit>,	1165	feed callback will be called whenever there are few enough (see C<limit>,
797	below) requests active in the group itself and is expected to queue more	1166	below) requests active in the group itself and is expected to queue more
…		…
801	not impose any limits).	1170	not impose any limits).
802		1171
803	If the feed does not queue more requests when called, it will be	1172	If the feed does not queue more requests when called, it will be
804	automatically removed from the group.	1173	automatically removed from the group.
805		1174
806	If the feed limit is C<0>, it will be set to C<2> automatically.	1175	If the feed limit is C<0> when this method is called, it will be set to
		1176	C<2> automatically.
807		1177
808	Example:	1178	Example:
809		1179
810	# stat all files in @files, but only ever use four aio requests concurrently:	1180	# stat all files in @files, but only ever use four aio requests concurrently:
811		1181
…		…
823	Sets the feeder limit for the group: The feeder will be called whenever	1193	Sets the feeder limit for the group: The feeder will be called whenever
824	the group contains less than this many requests.	1194	the group contains less than this many requests.
825		1195
826	Setting the limit to C<0> will pause the feeding process.	1196	Setting the limit to C<0> will pause the feeding process.
827		1197
		1198	The default value for the limit is C<0>, but note that setting a feeder
		1199	automatically bumps it up to C<2>.
		1200
828	=back	1201	=back
829		1202
830	=head2 SUPPORT FUNCTIONS	1203	=head2 SUPPORT FUNCTIONS
831		1204
		1205	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1206
832	=over 4	1207	=over 4
833		1208
834	=item $fileno = IO::AIO::poll_fileno	1209	=item $fileno = IO::AIO::poll_fileno
835		1210
836	Return the I<request result pipe file descriptor>. This filehandle must be	1211	Return the I<request result pipe file descriptor>. This filehandle must be
837	polled for reading by some mechanism outside this module (e.g. Event or	1212	polled for reading by some mechanism outside this module (e.g. EV, Glib,
838	select, see below or the SYNOPSIS). If the pipe becomes readable you have	1213	select and so on, see below or the SYNOPSIS). If the pipe becomes readable
839	to call C<poll_cb> to check the results.	1214	you have to call C<poll_cb> to check the results.
840		1215
841	See C<poll_cb> for an example.	1216	See C<poll_cb> for an example.
842		1217
843	=item IO::AIO::poll_cb	1218	=item IO::AIO::poll_cb
844		1219
845	Process all outstanding events on the result pipe. You have to call this	1220	Process some outstanding events on the result pipe. You have to call this
846	regularly. Returns the number of events processed. Returns immediately	1221	regularly. Returns C<0> if all events could be processed, or C<-1> if it
847	when no events are outstanding.	1222	returned earlier for whatever reason. Returns immediately when no events
		1223	are outstanding. The amount of events processed depends on the settings of
		1224	C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
848		1225
849	If not all requests were processed for whatever reason, the filehandle	1226	If not all requests were processed for whatever reason, the filehandle
850	will still be ready when C<poll_cb> returns.	1227	will still be ready when C<poll_cb> returns, so normally you don't have to
		1228	do anything special to have it called later.
851		1229
852	Example: Install an Event watcher that automatically calls	1230	Example: Install an Event watcher that automatically calls
853	IO::AIO::poll_cb with high priority:	1231	IO::AIO::poll_cb with high priority (more examples can be found in the
		1232	SYNOPSIS section, at the top of this document):
854		1233
855	Event->io (fd => IO::AIO::poll_fileno,	1234	Event->io (fd => IO::AIO::poll_fileno,
856	poll => 'r', async => 1,	1235	poll => 'r', async => 1,
857	cb => \&IO::AIO::poll_cb);	1236	cb => \&IO::AIO::poll_cb);
858		1237
859	=item IO::AIO::poll_some $max_requests	1238	=item IO::AIO::max_poll_reqs $nreqs
860		1239
861	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests	1240	=item IO::AIO::max_poll_time $seconds
862	at a time.
863		1241
864	Useful if you want to ensure some level of interactiveness when perl is	1242	These set the maximum number of requests (default C<0>, meaning infinity)
865	not fast enough to process all requests in time.	1243	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1244	the maximum amount of time (default C<0>, meaning infinity) spent in
		1245	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1246	of time C<poll_cb> is allowed to use).
		1247
		1248	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1249	syscall per request processed, which is not normally a problem unless your
		1250	callbacks are really really fast or your OS is really really slow (I am
		1251	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1252
		1253	Setting these is useful if you want to ensure some level of
		1254	interactiveness when perl is not fast enough to process all requests in
		1255	time.
		1256
		1257	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
866		1258
867	Example: Install an Event watcher that automatically calls	1259	Example: Install an Event watcher that automatically calls
868	IO::AIO::poll_some with low priority, to ensure that other parts of the	1260	IO::AIO::poll_cb with low priority, to ensure that other parts of the
869	program get the CPU sometimes even under high AIO load.	1261	program get the CPU sometimes even under high AIO load.
870		1262
		1263	# try not to spend much more than 0.1s in poll_cb
		1264	IO::AIO::max_poll_time 0.1;
		1265
		1266	# use a low priority so other tasks have priority
871	Event->io (fd => IO::AIO::poll_fileno,	1267	Event->io (fd => IO::AIO::poll_fileno,
872	poll => 'r', nice => 1,	1268	poll => 'r', nice => 1,
873	cb => sub { IO::AIO::poll_some 256 });	1269	cb => &IO::AIO::poll_cb);
874		1270
875	=item IO::AIO::poll_wait	1271	=item IO::AIO::poll_wait
876		1272
		1273	If there are any outstanding requests and none of them in the result
877	Wait till the result filehandle becomes ready for reading (simply does a	1274	phase, wait till the result filehandle becomes ready for reading (simply
878	C<select> on the filehandle. This is useful if you want to synchronously wait	1275	does a C<select> on the filehandle. This is useful if you want to
879	for some requests to finish).	1276	synchronously wait for some requests to finish).
880		1277
881	See C<nreqs> for an example.	1278	See C<nreqs> for an example.
882		1279
		1280	=item IO::AIO::poll
		1281
		1282	Waits until some requests have been handled.
		1283
		1284	Returns the number of requests processed, but is otherwise strictly
		1285	equivalent to:
		1286
		1287	IO::AIO::poll_wait, IO::AIO::poll_cb
		1288
883	=item IO::AIO::nreqs	1289	=item IO::AIO::flush
884		1290
885	Returns the number of requests currently in the ready, execute or pending	1291	Wait till all outstanding AIO requests have been handled.
886	states (i.e. for which their callback has not been invoked yet).
887		1292
888	Example: wait till there are no outstanding requests anymore:	1293	Strictly equivalent to:
889		1294
890	IO::AIO::poll_wait, IO::AIO::poll_cb	1295	IO::AIO::poll_wait, IO::AIO::poll_cb
891	while IO::AIO::nreqs;	1296	while IO::AIO::nreqs;
892		1297
893	=item IO::AIO::nready	1298	=back
894		1299
895	Returns the number of requests currently in the ready state (not yet	1300	=head3 CONTROLLING THE NUMBER OF THREADS
896	executed).
897		1301
898	=item IO::AIO::npending	1302	=over
899
900	Returns the number of requests currently in the pending state (executed,
901	but not yet processed by poll_cb).
902
903	=item IO::AIO::flush
904
905	Wait till all outstanding AIO requests have been handled.
906
907	Strictly equivalent to:
908
909	IO::AIO::poll_wait, IO::AIO::poll_cb
910	while IO::AIO::nreqs;
911
912	=item IO::AIO::poll
913
914	Waits until some requests have been handled.
915
916	Strictly equivalent to:
917
918	IO::AIO::poll_wait, IO::AIO::poll_cb
919	if IO::AIO::nreqs;
920		1303
921	=item IO::AIO::min_parallel $nthreads	1304	=item IO::AIO::min_parallel $nthreads
922		1305
923	Set the minimum number of AIO threads to C<$nthreads>. The current	1306	Set the minimum number of AIO threads to C<$nthreads>. The current
924	default is C<8>, which means eight asynchronous operations can execute	1307	default is C<8>, which means eight asynchronous operations can execute
925	concurrently at any one time (the number of outstanding requests,	1308	concurrently at any one time (the number of outstanding requests,
926	however, is unlimited).	1309	however, is unlimited).
927		1310
928	IO::AIO starts threads only on demand, when an AIO request is queued and	1311	IO::AIO starts threads only on demand, when an AIO request is queued and
929	no free thread exists.	1312	no free thread exists. Please note that queueing up a hundred requests can
		1313	create demand for a hundred threads, even if it turns out that everything
		1314	is in the cache and could have been processed faster by a single thread.
930		1315
931	It is recommended to keep the number of threads relatively low, as some	1316	It is recommended to keep the number of threads relatively low, as some
932	Linux kernel versions will scale negatively with the number of threads	1317	Linux kernel versions will scale negatively with the number of threads
933	(higher parallelity => MUCH higher latency). With current Linux 2.6	1318	(higher parallelity => MUCH higher latency). With current Linux 2.6
934	versions, 4-32 threads should be fine.	1319	versions, 4-32 threads should be fine.
…		…
948	This module automatically runs C<max_parallel 0> at program end, to ensure	1333	This module automatically runs C<max_parallel 0> at program end, to ensure
949	that all threads are killed and that there are no outstanding requests.	1334	that all threads are killed and that there are no outstanding requests.
950		1335
951	Under normal circumstances you don't need to call this function.	1336	Under normal circumstances you don't need to call this function.
952		1337
		1338	=item IO::AIO::max_idle $nthreads
		1339
		1340	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1341	threads that did not get a request to process within 10 seconds). That
		1342	means if a thread becomes idle while C<$nthreads> other threads are also
		1343	idle, it will free its resources and exit.
		1344
		1345	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1346	to allow for extremely high load situations, but want to free resources
		1347	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1348
		1349	The default is probably ok in most situations, especially if thread
		1350	creation is fast. If thread creation is very slow on your system you might
		1351	want to use larger values.
		1352
953	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1353	=item IO::AIO::max_outstanding $maxreqs
954		1354
955	This is a very bad function to use in interactive programs because it	1355	This is a very bad function to use in interactive programs because it
956	blocks, and a bad way to reduce concurrency because it is inexact: Better	1356	blocks, and a bad way to reduce concurrency because it is inexact: Better
957	use an C<aio_group> together with a feed callback.	1357	use an C<aio_group> together with a feed callback.
958		1358
959	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1359	Sets the maximum number of outstanding requests to C<$nreqs>. If you
960	to queue up more than this number of requests, the next call to the	1360	do queue up more than this number of requests, the next call to the
961	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)	1361	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
962	function will block until the limit is no longer exceeded.	1362	function will block until the limit is no longer exceeded.
963		1363
964	The default value is very large, so there is no practical limit on the	1364	The default value is very large, so there is no practical limit on the
965	number of outstanding requests.	1365	number of outstanding requests.
966		1366
967	You can still queue as many requests as you want. Therefore,	1367	You can still queue as many requests as you want. Therefore,
968	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	1368	C<max_outstanding> is mainly useful in simple scripts (with low values) or
969	as a stop gap to shield against fatal memory overflow (with large values).	1369	as a stop gap to shield against fatal memory overflow (with large values).
970		1370
971	=back	1371	=back
972		1372
		1373	=head3 STATISTICAL INFORMATION
		1374
		1375	=over
		1376
		1377	=item IO::AIO::nreqs
		1378
		1379	Returns the number of requests currently in the ready, execute or pending
		1380	states (i.e. for which their callback has not been invoked yet).
		1381
		1382	Example: wait till there are no outstanding requests anymore:
		1383
		1384	IO::AIO::poll_wait, IO::AIO::poll_cb
		1385	while IO::AIO::nreqs;
		1386
		1387	=item IO::AIO::nready
		1388
		1389	Returns the number of requests currently in the ready state (not yet
		1390	executed).
		1391
		1392	=item IO::AIO::npending
		1393
		1394	Returns the number of requests currently in the pending state (executed,
		1395	but not yet processed by poll_cb).
		1396
		1397	=back
		1398
973	=cut	1399	=cut
974		1400
975	# support function to convert a fd into a perl filehandle
976	sub _fd2fh {
977	return undef if $_[0] < 0;
978
979	# try to generate nice filehandles
980	my $sym = "IO::AIO::fd#$_[0]";
981	local *$sym;
982
983	open *$sym, "+<&=$_[0]" # usually works under any unix
984	or open *$sym, "<&=$_[0]" # cygwin needs this
985	or open *$sym, ">&=$_[0]" # or this
986	or return undef;
987
988	*$sym
989	}
990
991	min_parallel 8;	1401	min_parallel 8;
992		1402
993	END {	1403	END { flush }
994	flush;
995	};
996		1404
997	1;	1405	1;
998		1406
999	=head2 FORK BEHAVIOUR	1407	=head2 FORK BEHAVIOUR
1000		1408
…		…
1020	bytes of memory. In addition, stat requests need a stat buffer (possibly	1428	bytes of memory. In addition, stat requests need a stat buffer (possibly
1021	a few hundred bytes), readdir requires a result buffer and so on. Perl	1429	a few hundred bytes), readdir requires a result buffer and so on. Perl
1022	scalars and other data passed into aio requests will also be locked and	1430	scalars and other data passed into aio requests will also be locked and
1023	will consume memory till the request has entered the done state.	1431	will consume memory till the request has entered the done state.
1024		1432
1025	This is now awfully much, so queuing lots of requests is not usually a	1433	This is not awfully much, so queuing lots of requests is not usually a
1026	problem.	1434	problem.
1027		1435
1028	Per-thread usage:	1436	Per-thread usage:
1029		1437
1030	In the execution phase, some aio requests require more memory for	1438	In the execution phase, some aio requests require more memory for
…		…
1035		1443
1036	Known bugs will be fixed in the next release.	1444	Known bugs will be fixed in the next release.
1037		1445
1038	=head1 SEE ALSO	1446	=head1 SEE ALSO
1039		1447
1040	L<Coro::AIO>.	1448	L<AnyEvent::AIO> for easy integration into event loops, L<Coro::AIO> for a
		1449	more natural syntax.
1041		1450
1042	=head1 AUTHOR	1451	=head1 AUTHOR
1043		1452
1044	Marc Lehmann <schmorp@schmorp.de>	1453	Marc Lehmann <schmorp@schmorp.de>
1045	http://home.schmorp.de/	1454	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC vs. Revision 1.156 by root, Tue Jun 16 23:41:59 2009 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC vs.
Revision 1.156 by root, Tue Jun 16 23:41:59 2009 UTC