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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.124 by root, Sat May 10 19:25:33 2008 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
30	# AnyEvent integration	31	# AnyEvent integration (EV, Event, Glib, Tk, urxvt, pureperl...)
31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	32	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	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
		34
		35	# EV integration
		36	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
33		37
34	# Event integration	38	# Event integration
35	Event->io (fd => IO::AIO::poll_fileno,	39	Event->io (fd => IO::AIO::poll_fileno,
36	poll => 'r',	40	poll => 'r',
37	cb => \&IO::AIO::poll_cb);	41	cb => \&IO::AIO::poll_cb);
…		…
51	=head1 DESCRIPTION	55	=head1 DESCRIPTION
52		56
53	This module implements asynchronous I/O using whatever means your	57	This module implements asynchronous I/O using whatever means your
54	operating system supports.	58	operating system supports.
55		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 very
		73	inefficient. Use an event loop for that (such as the L<Event\|Event>
		74	module): IO::AIO will naturally fit into such an event loop itself.
		75
56	Currently, a number of threads are started that execute your read/writes	76	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	77	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	78	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	79	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	80	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	81	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	82	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	83	aio_write, so the remaining functionality would have to be implemented
		84	using threads anyway.
64		85
65	Although the module will work with in the presence of other threads,	86	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	87	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	88	yourself, always call C<poll_cb> from within the same thread, or never
68	call C<poll_cb> (or other C<aio_> functions) recursively.	89	call C<poll_cb> (or other C<aio_> functions) recursively.
69		90
		91	=head2 EXAMPLE
		92
		93	This is a simple example that uses the Event module and loads
		94	F</etc/passwd> asynchronously:
		95
		96	use Fcntl;
		97	use Event;
		98	use IO::AIO;
		99
		100	# register the IO::AIO callback with Event
		101	Event->io (fd => IO::AIO::poll_fileno,
		102	poll => 'r',
		103	cb => \&IO::AIO::poll_cb);
		104
		105	# queue the request to open /etc/passwd
		106	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		107	my $fh = shift
		108	or die "error while opening: $!";
		109
		110	# stat'ing filehandles is generally non-blocking
		111	my $size = -s $fh;
		112
		113	# queue a request to read the file
		114	my $contents;
		115	aio_read $fh, 0, $size, $contents, 0, sub {
		116	$_[0] == $size
		117	or die "short read: $!";
		118
		119	close $fh;
		120
		121	# file contents now in $contents
		122	print $contents;
		123
		124	# exit event loop and program
		125	Event::unloop;
		126	};
		127	};
		128
		129	# possibly queue up other requests, or open GUI windows,
		130	# check for sockets etc. etc.
		131
		132	# process events as long as there are some:
		133	Event::loop;
		134
		135	=head1 REQUEST ANATOMY AND LIFETIME
		136
		137	Every C<aio_*> function creates a request. which is a C data structure not
		138	directly visible to Perl.
		139
		140	If called in non-void context, every request function returns a Perl
		141	object representing the request. In void context, nothing is returned,
		142	which saves a bit of memory.
		143
		144	The perl object is a fairly standard ref-to-hash object. The hash contents
		145	are not used by IO::AIO so you are free to store anything you like in it.
		146
		147	During their existance, aio requests travel through the following states,
		148	in order:
		149
		150	=over 4
		151
		152	=item ready
		153
		154	Immediately after a request is created it is put into the ready state,
		155	waiting for a thread to execute it.
		156
		157	=item execute
		158
		159	A thread has accepted the request for processing and is currently
		160	executing it (e.g. blocking in read).
		161
		162	=item pending
		163
		164	The request has been executed and is waiting for result processing.
		165
		166	While request submission and execution is fully asynchronous, result
		167	processing is not and relies on the perl interpreter calling C<poll_cb>
		168	(or another function with the same effect).
		169
		170	=item result
		171
		172	The request results are processed synchronously by C<poll_cb>.
		173
		174	The C<poll_cb> function will process all outstanding aio requests by
		175	calling their callbacks, freeing memory associated with them and managing
		176	any groups they are contained in.
		177
		178	=item done
		179
		180	Request has reached the end of its lifetime and holds no resources anymore
		181	(except possibly for the Perl object, but its connection to the actual
		182	aio request is severed and calling its methods will either do nothing or
		183	result in a runtime error).
		184
		185	=back
		186
70	=cut	187	=cut
71		188
72	package IO::AIO;	189	package IO::AIO;
		190
		191	use Carp ();
73		192
74	no warnings;	193	no warnings;
75	use strict 'vars';	194	use strict 'vars';
76		195
77	use base 'Exporter';	196	use base 'Exporter';
78		197
79	BEGIN {	198	BEGIN {
80	our $VERSION = '2.0';	199	our $VERSION = '3.0';
81		200
82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	201	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	202	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	203	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
85	aio_group aio_nop);	204	aio_fdatasync aio_pathsync aio_readahead
		205	aio_rename aio_link aio_move aio_copy aio_group
		206	aio_nop aio_mknod aio_load aio_rmtree aio_mkdir aio_chown
		207	aio_chmod aio_utime aio_truncate);
		208
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	209	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	210	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	211	min_parallel max_parallel max_idle
		212	nreqs nready npending nthreads
		213	max_poll_time max_poll_reqs);
89		214
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		216
92	require XSLoader;	217	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	218	XSLoader::load ("IO::AIO", $VERSION);
94	}	219	}
95		220
96	=head1 FUNCTIONS	221	=head1 FUNCTIONS
97		222
98	=head2 AIO FUNCTIONS	223	=head2 AIO REQUEST FUNCTIONS
99		224
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	225	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	226	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	227	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	228	which must be a code reference. This code reference will get called with
…		…
106	syscall has been executed asynchronously.	231	syscall has been executed asynchronously.
107		232
108	All functions expecting a filehandle keep a copy of the filehandle	233	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	234	internally until the request has finished.
110		235
111	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
112	manipulation of those requests while they are in-flight.	237	further manipulation of those requests while they are in-flight.
113		238
114	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
115	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
116	request is being executed, the current working directory could have	241	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	242	changed. Alternatively, you can make sure that you never change the
118	current working directory.	243	current working directory anywhere in the program and then use relative
		244	paths.
119		245
120	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
121	always pass in filenames you got from outside (command line, readdir	247	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	248	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	249	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)	250	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	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 wether it is set or not.
126		255
127	=over 4	256	=over 4
128		257
129	=item aioreq_pri $pri	258	=item $prev_pri = aioreq_pri [$pri]
130		259
131	Sets the priority for the next aio request. The default priority	260	Returns the priority value that would be used for the next request and, if
		261	C<$pri> is given, sets the priority for the next aio request.
		262
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	263	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	264	and C<4>, respectively. Requests with higher priority will be serviced
		265	first.
134		266
135	The priority will be reset to C<0> after each call to one of the C<aio_>	267	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	268	functions.
137		269
138	Example: open a file with low priority, then read something from it with	270	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	271	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	272	open requests (potentially spamming the cache):
…		…
147	aio_read $_[0], ..., sub {	279	aio_read $_[0], ..., sub {
148	...	280	...
149	};	281	};
150	};	282	};
151		283
		284
152	=item aioreq_nice $pri_adjust	285	=item aioreq_nice $pri_adjust
153		286
154	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
155	priority, so effects are cumulative.	288	priority, so the effect is cumulative.
		289
156		290
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	291	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		292
159	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
160	created filehandle for the file.	294	created filehandle for the file.
…		…
166	list. They are the same as used by C<sysopen>.	300	list. They are the same as used by C<sysopen>.
167		301
168	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
169	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>,
170	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,
171	and C<0666> or C<0777> if you do).	305	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		306	by the umask in effect then the request is being executed, so better never
		307	change the umask.
172		308
173	Example:	309	Example:
174		310
175	aio_open "/etc/passwd", O_RDONLY, 0, sub {	311	aio_open "/etc/passwd", O_RDONLY, 0, sub {
176	if ($_[0]) {	312	if ($_[0]) {
…		…
179	} else {	315	} else {
180	die "open failed: $!\n";	316	die "open failed: $!\n";
181	}	317	}
182	};	318	};
183		319
		320
184	=item aio_close $fh, $callback->($status)	321	=item aio_close $fh, $callback->($status)
185		322
186	Asynchronously close a file and call the callback with the result	323	Asynchronously close a file and call the callback with the result
187	code. I<WARNING:> although accepted, you should not pass in a perl	324	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		325
192	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
193	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
194		337
195	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	338	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
196		339
197	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	340	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
198		341
199	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	342	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
200	into the scalar given by C<data> and offset C<dataoffset> and calls the	343	into the scalar given by C<$data> and offset C<$dataoffset> and calls the
201	callback without the actual number of bytes read (or -1 on error, just	344	callback without the actual number of bytes read (or -1 on error, just
202	like the syscall).	345	like the syscall).
203		346
		347	If C<$offset> is undefined, then the current file descriptor offset will
		348	be used (and updated), otherwise the file descriptor offset will not be
		349	changed by these calls.
		350
		351	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
		352
		353	If C<$dataoffset> is less than zero, it will be counted from the end of
		354	C<$data>.
		355
204	The C<$data> scalar I<MUST NOT> be modified in any way while the request	356	The C<$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	357	is outstanding. Modifying it can result in segfaults or World War III (if
206	necessary/optional hardware is installed).	358	the necessary/optional hardware is installed).
207		359
208	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	360	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
209	offset C<0> within the scalar:	361	offset C<0> within the scalar:
210		362
211	aio_read $fh, 7, 15, $buffer, 0, sub {	363	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	364	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	365	print "read $_[0] bytes: <$buffer>\n";
214	};	366	};
215		367
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		368
286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	369	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
287		370
288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	371	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	372	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
303	C<$in_fh> than are written, and there is no way to find out how many	386	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	387	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	388	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	389	value equals C<$length> one can assume that C<$length> bytes have been
307	read.	390	read.
		391
308		392
309	=item aio_readahead $fh,$offset,$length, $callback->($retval)	393	=item aio_readahead $fh,$offset,$length, $callback->($retval)
310		394
311	C<aio_readahead> populates the page cache with data from a file so that	395	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>	396	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.	402	file. The current file offset of the file is left unchanged.
319		403
320	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	404	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.	405	emulated by simply reading the data, which would have a similar effect.
322		406
		407
323	=item aio_stat $fh_or_path, $callback->($status)	408	=item aio_stat $fh_or_path, $callback->($status)
324		409
325	=item aio_lstat $fh, $callback->($status)	410	=item aio_lstat $fh, $callback->($status)
326		411
327	Works like perl's C<stat> or C<lstat> in void context. The callback will	412	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
340	aio_stat "/etc/passwd", sub {	425	aio_stat "/etc/passwd", sub {
341	$_[0] and die "stat failed: $!";	426	$_[0] and die "stat failed: $!";
342	print "size is ", -s _, "\n";	427	print "size is ", -s _, "\n";
343	};	428	};
344		429
		430
		431	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		432
		433	Works like perl's C<utime> function (including the special case of $atime
		434	and $mtime being undef). Fractional times are supported if the underlying
		435	syscalls support them.
		436
		437	When called with a pathname, uses utimes(2) if available, otherwise
		438	utime(2). If called on a file descriptor, uses futimes(2) if available,
		439	otherwise returns ENOSYS, so this is not portable.
		440
		441	Examples:
		442
		443	# set atime and mtime to current time (basically touch(1)):
		444	aio_utime "path", undef, undef;
		445	# set atime to current time and mtime to beginning of the epoch:
		446	aio_utime "path", time, undef; # undef==0
		447
		448
		449	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		450
		451	Works like perl's C<chown> function, except that C<undef> for either $uid
		452	or $gid is being interpreted as "do not change" (but -1 can also be used).
		453
		454	Examples:
		455
		456	# same as "chown root path" in the shell:
		457	aio_chown "path", 0, -1;
		458	# same as above:
		459	aio_chown "path", 0, undef;
		460
		461
		462	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		463
		464	Works like truncate(2) or ftruncate(2).
		465
		466
		467	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		468
		469	Works like perl's C<chmod> function.
		470
		471
345	=item aio_unlink $pathname, $callback->($status)	472	=item aio_unlink $pathname, $callback->($status)
346		473
347	Asynchronously unlink (delete) a file and call the callback with the	474	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	475	result code.
349		476
		477
		478	=item aio_mknod $path, $mode, $dev, $callback->($status)
		479
		480	[EXPERIMENTAL]
		481
		482	Asynchronously create a device node (or fifo). See mknod(2).
		483
		484	The only (POSIX-) portable way of calling this function is:
		485
		486	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		487
		488
350	=item aio_link $srcpath, $dstpath, $callback->($status)	489	=item aio_link $srcpath, $dstpath, $callback->($status)
351		490
352	Asynchronously create a new link to the existing object at C<$srcpath> at	491	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.	492	the path C<$dstpath> and call the callback with the result code.
354		493
		494
355	=item aio_symlink $srcpath, $dstpath, $callback->($status)	495	=item aio_symlink $srcpath, $dstpath, $callback->($status)
356		496
357	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	497	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.	498	the path C<$dstpath> and call the callback with the result code.
359		499
		500
		501	=item aio_readlink $path, $callback->($link)
		502
		503	Asynchronously read the symlink specified by C<$path> and pass it to
		504	the callback. If an error occurs, nothing or undef gets passed to the
		505	callback.
		506
		507
360	=item aio_rename $srcpath, $dstpath, $callback->($status)	508	=item aio_rename $srcpath, $dstpath, $callback->($status)
361		509
362	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	510	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
363	rename(2) and call the callback with the result code.	511	rename(2) and call the callback with the result code.
364		512
		513
		514	=item aio_mkdir $pathname, $mode, $callback->($status)
		515
		516	Asynchronously mkdir (create) a directory and call the callback with
		517	the result code. C<$mode> will be modified by the umask at the time the
		518	request is executed, so do not change your umask.
		519
		520
365	=item aio_rmdir $pathname, $callback->($status)	521	=item aio_rmdir $pathname, $callback->($status)
366		522
367	Asynchronously rmdir (delete) a directory and call the callback with the	523	Asynchronously rmdir (delete) a directory and call the callback with the
368	result code.	524	result code.
		525
369		526
370	=item aio_readdir $pathname, $callback->($entries)	527	=item aio_readdir $pathname, $callback->($entries)
371		528
372	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	529	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	530	directory (i.e. opendir + readdir + closedir). The entries will not be
374	sorted, and will B<NOT> include the C<.> and C<..> entries.	531	sorted, and will B<NOT> include the C<.> and C<..> entries.
375		532
376	The callback a single argument which is either C<undef> or an array-ref	533	The callback a single argument which is either C<undef> or an array-ref
377	with the filenames.	534	with the filenames.
378		535
		536
		537	=item aio_load $path, $data, $callback->($status)
		538
		539	This is a composite request that tries to fully load the given file into
		540	memory. Status is the same as with aio_read.
		541
		542	=cut
		543
		544	sub aio_load($$;$) {
		545	my ($path, undef, $cb) = @_;
		546	my $data = \$_[1];
		547
		548	my $pri = aioreq_pri;
		549	my $grp = aio_group $cb;
		550
		551	aioreq_pri $pri;
		552	add $grp aio_open $path, O_RDONLY, 0, sub {
		553	my $fh = shift
		554	or return $grp->result (-1);
		555
		556	aioreq_pri $pri;
		557	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		558	$grp->result ($_[0]);
		559	};
		560	};
		561
		562	$grp
		563	}
		564
		565	=item aio_copy $srcpath, $dstpath, $callback->($status)
		566
		567	Try to copy the I<file> (directories not supported as either source or
		568	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		569	the C<0> (error) or C<-1> ok.
		570
		571	This is a composite request that it creates the destination file with
		572	mode 0200 and copies the contents of the source file into it using
		573	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		574	uid/gid, in that order.
		575
		576	If an error occurs, the partial destination file will be unlinked, if
		577	possible, except when setting atime, mtime, access mode and uid/gid, where
		578	errors are being ignored.
		579
		580	=cut
		581
		582	sub aio_copy($$;$) {
		583	my ($src, $dst, $cb) = @_;
		584
		585	my $pri = aioreq_pri;
		586	my $grp = aio_group $cb;
		587
		588	aioreq_pri $pri;
		589	add $grp aio_open $src, O_RDONLY, 0, sub {
		590	if (my $src_fh = $_[0]) {
		591	my @stat = stat $src_fh;
		592
		593	aioreq_pri $pri;
		594	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		595	if (my $dst_fh = $_[0]) {
		596	aioreq_pri $pri;
		597	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		598	if ($_[0] == $stat[7]) {
		599	$grp->result (0);
		600	close $src_fh;
		601
		602	# those should not normally block. should. should.
		603	utime $stat[8], $stat[9], $dst;
		604	chmod $stat[2] & 07777, $dst_fh;
		605	chown $stat[4], $stat[5], $dst_fh;
		606
		607	aioreq_pri $pri;
		608	add $grp aio_close $dst_fh;
		609	} else {
		610	$grp->result (-1);
		611	close $src_fh;
		612	close $dst_fh;
		613
		614	aioreq $pri;
		615	add $grp aio_unlink $dst;
		616	}
		617	};
		618	} else {
		619	$grp->result (-1);
		620	}
		621	},
		622
		623	} else {
		624	$grp->result (-1);
		625	}
		626	};
		627
		628	$grp
		629	}
		630
		631	=item aio_move $srcpath, $dstpath, $callback->($status)
		632
		633	Try to move the I<file> (directories not supported as either source or
		634	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		635	the C<0> (error) or C<-1> ok.
		636
		637	This is a composite request that tries to rename(2) the file first. If
		638	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		639	that is successful, unlinking the C<$srcpath>.
		640
		641	=cut
		642
		643	sub aio_move($$;$) {
		644	my ($src, $dst, $cb) = @_;
		645
		646	my $pri = aioreq_pri;
		647	my $grp = aio_group $cb;
		648
		649	aioreq_pri $pri;
		650	add $grp aio_rename $src, $dst, sub {
		651	if ($_[0] && $! == EXDEV) {
		652	aioreq_pri $pri;
		653	add $grp aio_copy $src, $dst, sub {
		654	$grp->result ($_[0]);
		655
		656	if (!$_[0]) {
		657	aioreq_pri $pri;
		658	add $grp aio_unlink $src;
		659	}
		660	};
		661	} else {
		662	$grp->result ($_[0]);
		663	}
		664	};
		665
		666	$grp
		667	}
		668
379	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	669	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
380		670
381	[EXPERIMENTAL due to internal aio_group use]
382
383	Scans a directory (similar to C<aio_readdir>) but additionally tries to	671	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	672	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	673	names, directories you can recurse into (directories), and ones you cannot
386	recurse into (everything else).	674	recurse into (everything else, including symlinks to directories).
387		675
388	C<aio_scandir> is a composite request that creates of many sub requests_	676	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	677	C<$maxreq> specifies the maximum number of outstanding aio requests that
390	this function generates. If it is C<< <= 0 >>, then a suitable default	678	this function generates. If it is C<< <= 0 >>, then a suitable default
391	will be chosen (currently 6).	679	will be chosen (currently 4).
392		680
393	On error, the callback is called without arguments, otherwise it receives	681	On error, the callback is called without arguments, otherwise it receives
394	two array-refs with path-relative entry names.	682	two array-refs with path-relative entry names.
395		683
396	Example:	684	Example:
…		…
430	as those tend to return 0 or 1 as link counts, which disables the	718	as those tend to return 0 or 1 as link counts, which disables the
431	directory counting heuristic.	719	directory counting heuristic.
432		720
433	=cut	721	=cut
434		722
435	sub aio_scandir($$$) {	723	sub aio_scandir($$;$) {
436	my ($path, $maxreq, $cb) = @_;	724	my ($path, $maxreq, $cb) = @_;
437		725
		726	my $pri = aioreq_pri;
		727
438	my $grp = aio_group $cb;	728	my $grp = aio_group $cb;
439		729
440	$maxreq = 6 if $maxreq <= 0;	730	$maxreq = 4 if $maxreq <= 0;
441		731
442	# stat once	732	# stat once
		733	aioreq_pri $pri;
443	add $grp aio_stat $path, sub {	734	add $grp aio_stat $path, sub {
444	return $grp->result () if $_[0];	735	return $grp->result () if $_[0];
445	my $now = time;	736	my $now = time;
446	my $hash1 = join ":", (stat _)[0,1,3,7,9];	737	my $hash1 = join ":", (stat _)[0,1,3,7,9];
447		738
448	# read the directory entries	739	# read the directory entries
		740	aioreq_pri $pri;
449	add $grp aio_readdir $path, sub {	741	add $grp aio_readdir $path, sub {
450	my $entries = shift	742	my $entries = shift
451	or return $grp->result ();	743	or return $grp->result ();
452		744
453	# stat the dir another time	745	# stat the dir another time
		746	aioreq_pri $pri;
454	add $grp aio_stat $path, sub {	747	add $grp aio_stat $path, sub {
455	my $hash2 = join ":", (stat _)[0,1,3,7,9];	748	my $hash2 = join ":", (stat _)[0,1,3,7,9];
456		749
457	my $ndirs;	750	my $ndirs;
458		751
…		…
473	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	766	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
474	@$entries];	767	@$entries];
475		768
476	my (@dirs, @nondirs);	769	my (@dirs, @nondirs);
477		770
478	my ($statcb, $schedcb);
479	my $nreq = 0;
480
481	my $statgrp = add $grp aio_group;	771	my $statgrp = add $grp aio_group sub {
		772	$grp->result (\@dirs, \@nondirs);
		773	};
482		774
483	$schedcb = sub {	775	limit $statgrp $maxreq;
484	if (@$entries) {	776	feed $statgrp sub {
485	if ($nreq < $maxreq) {	777	return unless @$entries;
486	my $ent = pop @$entries;	778	my $entry = pop @$entries;
		779
		780	aioreq_pri $pri;
		781	add $statgrp aio_stat "$path/$entry/.", sub {
		782	if ($_[0] < 0) {
		783	push @nondirs, $entry;
		784	} else {
		785	# need to check for real directory
		786	aioreq_pri $pri;
		787	add $statgrp aio_lstat "$path/$entry", sub {
		788	if (-d _) {
		789	push @dirs, $entry;
		790
		791	unless (--$ndirs) {
		792	push @nondirs, @$entries;
		793	feed $statgrp;
		794	}
		795	} else {
		796	push @nondirs, $entry;
		797	}
487	$nreq++;	798	}
488	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
489	}	799	}
490	} elsif (!$nreq) {
491	# finished
492	$statgrp->cancel;
493	undef $statcb;
494	undef $schedcb;
495	$grp->result (\@dirs, \@nondirs);
496	}	800	};
497	};	801	};
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	};	802	};
528	};	803	};
529	};	804	};
530		805
531	$grp	806	$grp
532	}	807	}
533		808
		809	=item aio_rmtree $path, $callback->($status)
		810
		811	Delete a directory tree starting (and including) C<$path>, return the
		812	status of the final C<rmdir> only. This is a composite request that
		813	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		814	everything else.
		815
		816	=cut
		817
		818	sub aio_rmtree;
		819	sub aio_rmtree($;$) {
		820	my ($path, $cb) = @_;
		821
		822	my $pri = aioreq_pri;
		823	my $grp = aio_group $cb;
		824
		825	aioreq_pri $pri;
		826	add $grp aio_scandir $path, 0, sub {
		827	my ($dirs, $nondirs) = @_;
		828
		829	my $dirgrp = aio_group sub {
		830	add $grp aio_rmdir $path, sub {
		831	$grp->result ($_[0]);
		832	};
		833	};
		834
		835	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		836	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		837
		838	add $grp $dirgrp;
		839	};
		840
		841	$grp
		842	}
		843
		844	=item aio_sync $callback->($status)
		845
		846	Asynchronously call sync and call the callback when finished.
		847
534	=item aio_fsync $fh, $callback->($status)	848	=item aio_fsync $fh, $callback->($status)
535		849
536	Asynchronously call fsync on the given filehandle and call the callback	850	Asynchronously call fsync on the given filehandle and call the callback
537	with the fsync result code.	851	with the fsync result code.
538		852
…		…
542	callback with the fdatasync result code.	856	callback with the fdatasync result code.
543		857
544	If this call isn't available because your OS lacks it or it couldn't be	858	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.	859	detected, it will be emulated by calling C<fsync> instead.
546		860
		861	=item aio_pathsync $path, $callback->($status)
		862
		863	This request tries to open, fsync and close the given path. This is a
		864	composite request intended tosync directories after directory operations
		865	(E.g. rename). This might not work on all operating systems or have any
		866	specific effect, but usually it makes sure that directory changes get
		867	written to disc. It works for anything that can be opened for read-only,
		868	not just directories.
		869
		870	Passes C<0> when everything went ok, and C<-1> on error.
		871
		872	=cut
		873
		874	sub aio_pathsync($;$) {
		875	my ($path, $cb) = @_;
		876
		877	my $pri = aioreq_pri;
		878	my $grp = aio_group $cb;
		879
		880	aioreq_pri $pri;
		881	add $grp aio_open $path, O_RDONLY, 0, sub {
		882	my ($fh) = @_;
		883	if ($fh) {
		884	aioreq_pri $pri;
		885	add $grp aio_fsync $fh, sub {
		886	$grp->result ($_[0]);
		887
		888	aioreq_pri $pri;
		889	add $grp aio_close $fh;
		890	};
		891	} else {
		892	$grp->result (-1);
		893	}
		894	};
		895
		896	$grp
		897	}
		898
547	=item aio_group $callback->(...)	899	=item aio_group $callback->(...)
548
549	[EXPERIMENTAL]
550		900
551	This is a very special aio request: Instead of doing something, it is a	901	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	902	container for other aio requests, which is useful if you want to bundle
553	many requests into a single, composite, request.	903	many requests into a single, composite, request with a definite callback
		904	and the ability to cancel the whole request with its subrequests.
554		905
555	Returns an object of class L<IO::AIO::GRP>. See its documentation below	906	Returns an object of class L<IO::AIO::GRP>. See its documentation below
556	for more info.	907	for more info.
557		908
558	Example:	909	Example:
…		…
577	phase and still requires a worker thread. Thus, the callback will not	928	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	929	be executed immediately but only after other requests in the queue have
579	entered their execution phase. This can be used to measure request	930	entered their execution phase. This can be used to measure request
580	latency.	931	latency.
581		932
582	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	933	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
583		934
584	Mainly used for debugging and benchmarking, this aio request puts one of	935	Mainly used for debugging and benchmarking, this aio request puts one of
585	the request workers to sleep for the given time.	936	the request workers to sleep for the given time.
586		937
587	While it is theoretically handy to have simple I/O scheduling requests	938	While it is theoretically handy to have simple I/O scheduling requests
588	like sleep and file handle readable/writable, the overhead this creates	939	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	940	immense (it blocks a thread for a long time) so do not use this function
590	under artificial I/O pressure.	941	except to put your application under artificial I/O pressure.
591		942
592	=back	943	=back
593		944
594	=head2 IO::AIO::REQ CLASS	945	=head2 IO::AIO::REQ CLASS
595		946
596	All non-aggregate C<aio_*> functions return an object of this class when	947	All non-aggregate C<aio_*> functions return an object of this class when
597	called in non-void context.	948	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		949
607	=over 4	950	=over 4
608		951
609	=item cancel $req	952	=item cancel $req
610		953
…		…
664	=item * They can also can also be added to other IO::AIO::GRP objects.	1007	=item * They can also can also be added to other IO::AIO::GRP objects.
665		1008
666	=item * You must not add requests to a group from within the group callback (or	1009	=item * You must not add requests to a group from within the group callback (or
667	any later time).	1010	any later time).
668		1011
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	1012	=back
674		1013
675	Their lifetime, simplified, looks like this: when they are empty, they	1014	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	1015	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	1016	C<done> state, they will also finish. Otherwise they will continue to
…		…
692	be added, including other groups, as long as you do not create circular	1031	be added, including other groups, as long as you do not create circular
693	dependencies.	1032	dependencies.
694		1033
695	Returns all its arguments.	1034	Returns all its arguments.
696		1035
		1036	=item $grp->cancel_subs
		1037
		1038	Cancel all subrequests and clears any feeder, but not the group request
		1039	itself. Useful when you queued a lot of events but got a result early.
		1040
697	=item $grp->result (...)	1041	=item $grp->result (...)
698		1042
699	Set the result value(s) that will be passed to the group callback when all	1043	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.	1044	subrequests have finished and set the groups errno to the current value
		1045	of errno (just like calling C<errno> without an error number). By default,
		1046	no argument will be passed and errno is zero.
		1047
		1048	=item $grp->errno ([$errno])
		1049
		1050	Sets the group errno value to C<$errno>, or the current value of errno
		1051	when the argument is missing.
		1052
		1053	Every aio request has an associated errno value that is restored when
		1054	the callback is invoked. This method lets you change this value from its
		1055	default (0).
		1056
		1057	Calling C<result> will also set errno, so make sure you either set C<$!>
		1058	before the call to C<result>, or call c<errno> after it.
701		1059
702	=item feed $grp $callback->($grp)	1060	=item feed $grp $callback->($grp)
703
704	[VERY EXPERIMENTAL]
705		1061
706	Sets a feeder/generator on this group: every group can have an attached	1062	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,	1063	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,	1064	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	1065	this might starve other requests for a potentially long time. For
…		…
746		1102
747	=back	1103	=back
748		1104
749	=head2 SUPPORT FUNCTIONS	1105	=head2 SUPPORT FUNCTIONS
750		1106
		1107	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1108
751	=over 4	1109	=over 4
752		1110
753	=item $fileno = IO::AIO::poll_fileno	1111	=item $fileno = IO::AIO::poll_fileno
754		1112
755	Return the I<request result pipe file descriptor>. This filehandle must be	1113	Return the I<request result pipe file descriptor>. This filehandle must be
…		…
759		1117
760	See C<poll_cb> for an example.	1118	See C<poll_cb> for an example.
761		1119
762	=item IO::AIO::poll_cb	1120	=item IO::AIO::poll_cb
763		1121
764	Process all outstanding events on the result pipe. You have to call this	1122	Process some outstanding events on the result pipe. You have to call this
765	regularly. Returns the number of events processed. Returns immediately	1123	regularly. Returns the number of events processed. Returns immediately
766	when no events are outstanding.	1124	when no events are outstanding. The amount of events processed depends on
		1125	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1126
		1127	If not all requests were processed for whatever reason, the filehandle
		1128	will still be ready when C<poll_cb> returns.
767		1129
768	Example: Install an Event watcher that automatically calls	1130	Example: Install an Event watcher that automatically calls
769	IO::AIO::poll_cb with high priority:	1131	IO::AIO::poll_cb with high priority:
770		1132
771	Event->io (fd => IO::AIO::poll_fileno,	1133	Event->io (fd => IO::AIO::poll_fileno,
772	poll => 'r', async => 1,	1134	poll => 'r', async => 1,
773	cb => \&IO::AIO::poll_cb);	1135	cb => \&IO::AIO::poll_cb);
774		1136
		1137	=item IO::AIO::max_poll_reqs $nreqs
		1138
		1139	=item IO::AIO::max_poll_time $seconds
		1140
		1141	These set the maximum number of requests (default C<0>, meaning infinity)
		1142	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1143	the maximum amount of time (default C<0>, meaning infinity) spent in
		1144	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1145	of time C<poll_cb> is allowed to use).
		1146
		1147	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1148	syscall per request processed, which is not normally a problem unless your
		1149	callbacks are really really fast or your OS is really really slow (I am
		1150	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1151
		1152	Setting these is useful if you want to ensure some level of
		1153	interactiveness when perl is not fast enough to process all requests in
		1154	time.
		1155
		1156	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1157
		1158	Example: Install an Event watcher that automatically calls
		1159	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1160	program get the CPU sometimes even under high AIO load.
		1161
		1162	# try not to spend much more than 0.1s in poll_cb
		1163	IO::AIO::max_poll_time 0.1;
		1164
		1165	# use a low priority so other tasks have priority
		1166	Event->io (fd => IO::AIO::poll_fileno,
		1167	poll => 'r', nice => 1,
		1168	cb => &IO::AIO::poll_cb);
		1169
775	=item IO::AIO::poll_wait	1170	=item IO::AIO::poll_wait
776		1171
		1172	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	1173	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	1174	does a C<select> on the filehandle. This is useful if you want to
779	for some requests to finish).	1175	synchronously wait for some requests to finish).
780		1176
781	See C<nreqs> for an example.	1177	See C<nreqs> for an example.
782		1178
		1179	=item IO::AIO::poll
		1180
		1181	Waits until some requests have been handled.
		1182
		1183	Returns the number of requests processed, but is otherwise strictly
		1184	equivalent to:
		1185
		1186	IO::AIO::poll_wait, IO::AIO::poll_cb
		1187
783	=item IO::AIO::nreqs	1188	=item IO::AIO::flush
784		1189
785	Returns the number of requests currently outstanding (i.e. for which their	1190	Wait till all outstanding AIO requests have been handled.
786	callback has not been invoked yet).
787		1191
788	Example: wait till there are no outstanding requests anymore:	1192	Strictly equivalent to:
789		1193
790	IO::AIO::poll_wait, IO::AIO::poll_cb	1194	IO::AIO::poll_wait, IO::AIO::poll_cb
791	while IO::AIO::nreqs;	1195	while IO::AIO::nreqs;
792		1196
793	=item IO::AIO::flush	1197	=back
794		1198
795	Wait till all outstanding AIO requests have been handled.	1199	=head3 CONTROLLING THE NUMBER OF THREADS
796		1200
797	Strictly equivalent to:	1201	=over
798
799	IO::AIO::poll_wait, IO::AIO::poll_cb
800	while IO::AIO::nreqs;
801
802	=item IO::AIO::poll
803
804	Waits until some requests have been handled.
805
806	Strictly equivalent to:
807
808	IO::AIO::poll_wait, IO::AIO::poll_cb
809	if IO::AIO::nreqs;
810		1202
811	=item IO::AIO::min_parallel $nthreads	1203	=item IO::AIO::min_parallel $nthreads
812		1204
813	Set the minimum number of AIO threads to C<$nthreads>. The current	1205	Set the minimum number of AIO threads to C<$nthreads>. The current
814	default is C<8>, which means eight asynchronous operations can execute	1206	default is C<8>, which means eight asynchronous operations can execute
815	concurrently at any one time (the number of outstanding requests,	1207	concurrently at any one time (the number of outstanding requests,
816	however, is unlimited).	1208	however, is unlimited).
817		1209
818	IO::AIO starts threads only on demand, when an AIO request is queued and	1210	IO::AIO starts threads only on demand, when an AIO request is queued and
819	no free thread exists.	1211	no free thread exists. Please note that queueing up a hundred requests can
		1212	create demand for a hundred threads, even if it turns out that everything
		1213	is in the cache and could have been processed faster by a single thread.
820		1214
821	It is recommended to keep the number of threads relatively low, as some	1215	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	1216	Linux kernel versions will scale negatively with the number of threads
823	(higher parallelity => MUCH higher latency). With current Linux 2.6	1217	(higher parallelity => MUCH higher latency). With current Linux 2.6
824	versions, 4-32 threads should be fine.	1218	versions, 4-32 threads should be fine.
…		…
838	This module automatically runs C<max_parallel 0> at program end, to ensure	1232	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.	1233	that all threads are killed and that there are no outstanding requests.
840		1234
841	Under normal circumstances you don't need to call this function.	1235	Under normal circumstances you don't need to call this function.
842		1236
		1237	=item IO::AIO::max_idle $nthreads
		1238
		1239	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1240	threads that did not get a request to process within 10 seconds). That
		1241	means if a thread becomes idle while C<$nthreads> other threads are also
		1242	idle, it will free its resources and exit.
		1243
		1244	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1245	to allow for extremely high load situations, but want to free resources
		1246	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1247
		1248	The default is probably ok in most situations, especially if thread
		1249	creation is fast. If thread creation is very slow on your system you might
		1250	want to use larger values.
		1251
843	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1252	=item IO::AIO::max_outstanding $maxreqs
844		1253
845	[DEPRECATED]	1254	This is a very bad function to use in interactive programs because it
		1255	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1256	use an C<aio_group> together with a feed callback.
846		1257
847	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1258	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	1259	do queue up more than this number of requests, the next call to the
849	some requests have been handled.	1260	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1261	function will block until the limit is no longer exceeded.
850		1262
851	The default is very large, so normally there is no practical limit. If you	1263	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	1264	number of outstanding requests.
853	this to a relatively low number, such as C<100>.
854		1265
855	This function does not work well together with C<aio_group>'s, and their	1266	You can still queue as many requests as you want. Therefore,
856	feeder interface is better suited to limiting concurrency, so do not use	1267	C<max_outstanding> is mainly useful in simple scripts (with low values) or
857	this function.	1268	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		1269
861	=back	1270	=back
862		1271
		1272	=head3 STATISTICAL INFORMATION
		1273
		1274	=over
		1275
		1276	=item IO::AIO::nreqs
		1277
		1278	Returns the number of requests currently in the ready, execute or pending
		1279	states (i.e. for which their callback has not been invoked yet).
		1280
		1281	Example: wait till there are no outstanding requests anymore:
		1282
		1283	IO::AIO::poll_wait, IO::AIO::poll_cb
		1284	while IO::AIO::nreqs;
		1285
		1286	=item IO::AIO::nready
		1287
		1288	Returns the number of requests currently in the ready state (not yet
		1289	executed).
		1290
		1291	=item IO::AIO::npending
		1292
		1293	Returns the number of requests currently in the pending state (executed,
		1294	but not yet processed by poll_cb).
		1295
		1296	=back
		1297
863	=cut	1298	=cut
864		1299
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;	1300	min_parallel 8;
882		1301
883	END {	1302	END { flush }
884	max_parallel 0;
885	}
886		1303
887	1;	1304	1;
888		1305
889	=head2 FORK BEHAVIOUR	1306	=head2 FORK BEHAVIOUR
890		1307
891	This module should do "the right thing" when the process using it forks:	1308	This module should do "the right thing" when the process using it forks:
892		1309
893	Before the fork, IO::AIO enters a quiescent state where no requests	1310	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	1311	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	1312	the fork the parent simply leaves the quiescent state and continues
896	request/result processing, while the child clears the request/result	1313	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	1314	(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	1315	parent). Threads will be started on demand until the limit set in the
899	parent process has been reached again.	1316	parent process has been reached again.
900		1317
901	In short: the parent will, after a short pause, continue as if fork had	1318	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	1319	not been called, while the child will act as if IO::AIO has not been used
903	yet.	1320	yet.
904		1321
905	=head2 MEMORY USAGE	1322	=head2 MEMORY USAGE
906		1323
		1324	Per-request usage:
		1325
907	Each aio request uses - depending on your architecture - around 128 bytes	1326	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	1327	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	1328	a few hundred bytes), readdir requires a result buffer and so on. Perl
910	also be locked.	1329	scalars and other data passed into aio requests will also be locked and
		1330	will consume memory till the request has entered the done state.
911		1331
912	This is now awfully much, so queuing lots of requests is not usually a	1332	This is not awfully much, so queuing lots of requests is not usually a
913	problem.	1333	problem.
914		1334
915	Each thread needs a stack area which is usually around 16k, sometimes much	1335	Per-thread usage:
916	larger, depending on the OS.	1336
		1337	In the execution phase, some aio requests require more memory for
		1338	temporary buffers, and each thread requires a stack and other data
		1339	structures (usually around 16k-128k, depending on the OS).
		1340
		1341	=head1 KNOWN BUGS
		1342
		1343	Known bugs will be fixed in the next release.
917		1344
918	=head1 SEE ALSO	1345	=head1 SEE ALSO
919		1346
920	L<Coro::AIO>.	1347	L<Coro::AIO>.
921		1348

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs. Revision 1.124 by root, Sat May 10 19:25:33 2008 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.124 by root, Sat May 10 19:25:33 2008 UTC