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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs.
Revision 1.117 by root, Sat Oct 6 14:05:19 2007 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
…		…
51	=head1 DESCRIPTION	52	=head1 DESCRIPTION
52		53
53	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
54	operating system supports.	55	operating system supports.
55		56
		57	Asynchronous means that operations that can normally block your program
		58	(e.g. reading from disk) will be done asynchronously: the operation
		59	will still block, but you can do something else in the meantime. This
		60	is extremely useful for programs that need to stay interactive even
		61	when doing heavy I/O (GUI programs, high performance network servers
		62	etc.), but can also be used to easily do operations in parallel that are
		63	normally done sequentially, e.g. stat'ing many files, which is much faster
		64	on a RAID volume or over NFS when you do a number of stat operations
		65	concurrently.
		66
		67	While most of this works on all types of file descriptors (for
		68	example sockets), using these functions on file descriptors that
		69	support nonblocking operation (again, sockets, pipes etc.) is very
		70	inefficient. Use an event loop for that (such as the L<Event\|Event>
		71	module): IO::AIO will naturally fit into such an event loop itself.
		72
56	Currently, a number of threads are started that execute your read/writes	73	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	74	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	75	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	76	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	77	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	78	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	79	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	80	aio_write, so the remaining functionality would have to be implemented
		81	using threads anyway.
64		82
65	Although the module will work with in the presence of other threads,	83	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	84	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	85	yourself, always call C<poll_cb> from within the same thread, or never
68	call C<poll_cb> (or other C<aio_> functions) recursively.	86	call C<poll_cb> (or other C<aio_> functions) recursively.
69		87
		88	=head2 EXAMPLE
		89
		90	This is a simple example that uses the Event module and loads
		91	F</etc/passwd> asynchronously:
		92
		93	use Fcntl;
		94	use Event;
		95	use IO::AIO;
		96
		97	# register the IO::AIO callback with Event
		98	Event->io (fd => IO::AIO::poll_fileno,
		99	poll => 'r',
		100	cb => \&IO::AIO::poll_cb);
		101
		102	# queue the request to open /etc/passwd
		103	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		104	my $fh = shift
		105	or die "error while opening: $!";
		106
		107	# stat'ing filehandles is generally non-blocking
		108	my $size = -s $fh;
		109
		110	# queue a request to read the file
		111	my $contents;
		112	aio_read $fh, 0, $size, $contents, 0, sub {
		113	$_[0] == $size
		114	or die "short read: $!";
		115
		116	close $fh;
		117
		118	# file contents now in $contents
		119	print $contents;
		120
		121	# exit event loop and program
		122	Event::unloop;
		123	};
		124	};
		125
		126	# possibly queue up other requests, or open GUI windows,
		127	# check for sockets etc. etc.
		128
		129	# process events as long as there are some:
		130	Event::loop;
		131
		132	=head1 REQUEST ANATOMY AND LIFETIME
		133
		134	Every C<aio_*> function creates a request. which is a C data structure not
		135	directly visible to Perl.
		136
		137	If called in non-void context, every request function returns a Perl
		138	object representing the request. In void context, nothing is returned,
		139	which saves a bit of memory.
		140
		141	The perl object is a fairly standard ref-to-hash object. The hash contents
		142	are not used by IO::AIO so you are free to store anything you like in it.
		143
		144	During their existance, aio requests travel through the following states,
		145	in order:
		146
		147	=over 4
		148
		149	=item ready
		150
		151	Immediately after a request is created it is put into the ready state,
		152	waiting for a thread to execute it.
		153
		154	=item execute
		155
		156	A thread has accepted the request for processing and is currently
		157	executing it (e.g. blocking in read).
		158
		159	=item pending
		160
		161	The request has been executed and is waiting for result processing.
		162
		163	While request submission and execution is fully asynchronous, result
		164	processing is not and relies on the perl interpreter calling C<poll_cb>
		165	(or another function with the same effect).
		166
		167	=item result
		168
		169	The request results are processed synchronously by C<poll_cb>.
		170
		171	The C<poll_cb> function will process all outstanding aio requests by
		172	calling their callbacks, freeing memory associated with them and managing
		173	any groups they are contained in.
		174
		175	=item done
		176
		177	Request has reached the end of its lifetime and holds no resources anymore
		178	(except possibly for the Perl object, but its connection to the actual
		179	aio request is severed and calling its methods will either do nothing or
		180	result in a runtime error).
		181
		182	=back
		183
70	=cut	184	=cut
71		185
72	package IO::AIO;	186	package IO::AIO;
		187
		188	use Carp ();
73		189
74	no warnings;	190	no warnings;
75	use strict 'vars';	191	use strict 'vars';
76		192
77	use base 'Exporter';	193	use base 'Exporter';
78		194
79	BEGIN {	195	BEGIN {
80	our $VERSION = '2.0';	196	our $VERSION = '2.51';
81		197
82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	198	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
83	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	199	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	200	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
85	aio_group aio_nop);	201	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
		202	aio_chown aio_chmod aio_utime aio_truncate);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	203	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	204	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	205	min_parallel max_parallel max_idle
		206	nreqs nready npending nthreads
		207	max_poll_time max_poll_reqs);
89		208
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	209	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		210
92	require XSLoader;	211	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	212	XSLoader::load ("IO::AIO", $VERSION);
94	}	213	}
95		214
96	=head1 FUNCTIONS	215	=head1 FUNCTIONS
97		216
98	=head2 AIO FUNCTIONS	217	=head2 AIO REQUEST FUNCTIONS
99		218
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	219	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	220	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	221	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	222	which must be a code reference. This code reference will get called with
…		…
106	syscall has been executed asynchronously.	225	syscall has been executed asynchronously.
107		226
108	All functions expecting a filehandle keep a copy of the filehandle	227	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	228	internally until the request has finished.
110		229
111	All requests return objects of type L<IO::AIO::REQ> that allow further	230	All functions return request objects of type L<IO::AIO::REQ> that allow
112	manipulation of those requests while they are in-flight.	231	further manipulation of those requests while they are in-flight.
113		232
114	The pathnames you pass to these routines I<must> be absolute and	233	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	234	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	235	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	236	changed. Alternatively, you can make sure that you never change the
118	current working directory.	237	current working directory anywhere in the program and then use relative
		238	paths.
119		239
120	To encode pathnames to byte form, either make sure you either: a)	240	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	241	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	242	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	243	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)	244	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	245	use something else to ensure your scalar has the correct contents.
		246
		247	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		248	handles correctly wether it is set or not.
126		249
127	=over 4	250	=over 4
128		251
129	=item aioreq_pri $pri	252	=item $prev_pri = aioreq_pri [$pri]
130		253
131	Sets the priority for the next aio request. The default priority	254	Returns the priority value that would be used for the next request and, if
		255	C<$pri> is given, sets the priority for the next aio request.
		256
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	257	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	258	and C<4>, respectively. Requests with higher priority will be serviced
		259	first.
134		260
135	The priority will be reset to C<0> after each call to one of the C<aio_>	261	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	262	functions.
137		263
138	Example: open a file with low priority, then read something from it with	264	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	265	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	266	open requests (potentially spamming the cache):
…		…
147	aio_read $_[0], ..., sub {	273	aio_read $_[0], ..., sub {
148	...	274	...
149	};	275	};
150	};	276	};
151		277
		278
152	=item aioreq_nice $pri_adjust	279	=item aioreq_nice $pri_adjust
153		280
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	281	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	282	priority, so the effect is cumulative.
		283
156		284
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	285	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		286
159	Asynchronously open or create a file and call the callback with a newly	287	Asynchronously open or create a file and call the callback with a newly
160	created filehandle for the file.	288	created filehandle for the file.
…		…
166	list. They are the same as used by C<sysopen>.	294	list. They are the same as used by C<sysopen>.
167		295
168	Likewise, C<$mode> specifies the mode of the newly created file, if it	296	Likewise, C<$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>,	297	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,	298	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).	299	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		300	by the umask in effect then the request is being executed, so better never
		301	change the umask.
172		302
173	Example:	303	Example:
174		304
175	aio_open "/etc/passwd", O_RDONLY, 0, sub {	305	aio_open "/etc/passwd", O_RDONLY, 0, sub {
176	if ($_[0]) {	306	if ($_[0]) {
…		…
179	} else {	309	} else {
180	die "open failed: $!\n";	310	die "open failed: $!\n";
181	}	311	}
182	};	312	};
183		313
		314
184	=item aio_close $fh, $callback->($status)	315	=item aio_close $fh, $callback->($status)
185		316
186	Asynchronously close a file and call the callback with the result	317	Asynchronously close a file and call the callback with the result
187	code. I<WARNING:> although accepted, you should not pass in a perl	318	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		319
192	This is supposed to be a bug in the API, so that might change. It's	320	Unfortunately, you can't do this to perl. Perl I<insists> very strongly on
193	therefore best to avoid this function.	321	closing the file descriptor associated with the filehandle itself. Here is
		322	what aio_close will try:
		323
		324	1. dup()licate the fd
		325	2. asynchronously close() the duplicated fd
		326	3. dup()licate the fd once more
		327	4. let perl close() the filehandle
		328	5. asynchronously close the duplicated fd
		329
		330	The idea is that the first close() flushes stuff to disk that closing an
		331	fd will flush, so when perl closes the fd, nothing much will need to be
		332	flushed. The second async. close() will then flush stuff to disk that
		333	closing the last fd to the file will flush.
		334
		335	Just FYI, SuSv3 has this to say on close:
		336
		337	All outstanding record locks owned by the process on the file
		338	associated with the file descriptor shall be removed.
		339
		340	If fildes refers to a socket, close() shall cause the socket to be
		341	destroyed. ... close() shall block for up to the current linger
		342	interval until all data is transmitted.
		343	[this actually sounds like a specification bug, but who knows]
		344
		345	And at least Linux additionally actually flushes stuff on every close,
		346	even when the file itself is still open.
		347
		348	Sounds enourmously inefficient and complicated? Yes... please show me how
		349	to nuke perl's fd out of existence...
		350
		351	=cut
		352
		353	sub aio_close($;$) {
		354	aio_block {
		355	my ($fh, $cb) = @_;
		356
		357	my $pri = aioreq_pri;
		358	my $grp = aio_group $cb;
		359
		360	my $fd = fileno $fh;
		361
		362	defined $fd or Carp::croak "aio_close called with fd-less filehandle";
		363
		364	# if the dups fail we will simply get EBADF
		365	my $fd2 = _dup $fd;
		366	aioreq_pri $pri;
		367	add $grp _aio_close $fd2, sub {
		368	my $fd2 = _dup $fd;
		369	close $fh;
		370	aioreq_pri $pri;
		371	add $grp _aio_close $fd2, sub {
		372	$grp->result ($_[0]);
		373	};
		374	};
		375
		376	$grp
		377	}
		378	}
		379
194		380
195	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	381	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
196		382
197	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	383	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
198		384
199	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	385	Reads or writes C<$length> bytes from the specified C<$fh> and C<$offset>
200	into the scalar given by C<data> and offset C<dataoffset> and calls the	386	into the scalar given by C<$data> and offset C<$dataoffset> and calls the
201	callback without the actual number of bytes read (or -1 on error, just	387	callback without the actual number of bytes read (or -1 on error, just
202	like the syscall).	388	like the syscall).
203		389
		390	If C<$offset> is undefined, then the current file descriptor offset will
		391	be used (and updated), otherwise the file descriptor offset will not be
		392	changed by these calls.
		393
		394	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
		395
		396	If C<$dataoffset> is less than zero, it will be counted from the end of
		397	C<$data>.
		398
204	The C<$data> scalar I<MUST NOT> be modified in any way while the request	399	The C<$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	400	is outstanding. Modifying it can result in segfaults or World War III (if
206	necessary/optional hardware is installed).	401	the necessary/optional hardware is installed).
207		402
208	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	403	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
209	offset C<0> within the scalar:	404	offset C<0> within the scalar:
210		405
211	aio_read $fh, 7, 15, $buffer, 0, sub {	406	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	407	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	408	print "read $_[0] bytes: <$buffer>\n";
214	};	409	};
215		410
216	=item aio_move $srcpath, $dstpath, $callback->($status)
217
218	Try to move the I<file> (directories not supported as either source or
219	destination) from C<$srcpath> to C<$dstpath> and call the callback with
220	the C<0> (error) or C<-1> ok.
221
222	This is a composite request that tries to rename(2) the file first. If
223	rename files with C<EXDEV>, it creates the destination file with mode 0200
224	and copies the contents of the source file into it using C<aio_sendfile>,
225	followed by restoring atime, mtime, access mode and uid/gid, in that
226	order, and unlinking the C<$srcpath>.
227
228	If an error occurs, the partial destination file will be unlinked, if
229	possible, except when setting atime, mtime, access mode and uid/gid, where
230	errors are being ignored.
231
232	=cut
233
234	sub aio_move($$$) {
235	my ($src, $dst, $cb) = @_;
236
237	my $grp = aio_group $cb;
238
239	add $grp aio_rename $src, $dst, sub {
240	if ($_[0] && $! == EXDEV) {
241	add $grp aio_open $src, O_RDONLY, 0, sub {
242	if (my $src_fh = $_[0]) {
243	my @stat = stat $src_fh;
244
245	add $grp aio_open $dst, O_WRONLY, 0200, sub {
246	if (my $dst_fh = $_[0]) {
247	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
248	close $src_fh;
249
250	if ($_[0] == $stat[7]) {
251	utime $stat[8], $stat[9], $dst;
252	chmod $stat[2] & 07777, $dst_fh;
253	chown $stat[4], $stat[5], $dst_fh;
254	close $dst_fh;
255
256	add $grp aio_unlink $src, sub {
257	$grp->result ($_[0]);
258	};
259	} else {
260	my $errno = $!;
261	add $grp aio_unlink $dst, sub {
262	$! = $errno;
263	$grp->result (-1);
264	};
265	}
266	};
267	} else {
268	$grp->result (-1);
269	}
270	},
271
272	} else {
273	$grp->result (-1);
274	}
275	};
276	} else {
277	$grp->result ($_[0]);
278	}
279	};
280
281	$grp
282	}
283		411
284	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	412	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
285		413
286	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	414	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
287	reading at byte offset C<$in_offset>, and starts writing at the current	415	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
301	C<$in_fh> than are written, and there is no way to find out how many	429	C<$in_fh> than are written, and there is no way to find out how many
302	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only	430	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
303	provides the number of bytes written to C<$out_fh>. Only if the result	431	provides the number of bytes written to C<$out_fh>. Only if the result
304	value equals C<$length> one can assume that C<$length> bytes have been	432	value equals C<$length> one can assume that C<$length> bytes have been
305	read.	433	read.
		434
306		435
307	=item aio_readahead $fh,$offset,$length, $callback->($retval)	436	=item aio_readahead $fh,$offset,$length, $callback->($retval)
308		437
309	C<aio_readahead> populates the page cache with data from a file so that	438	C<aio_readahead> populates the page cache with data from a file so that
310	subsequent reads from that file will not block on disk I/O. The C<$offset>	439	subsequent reads from that file will not block on disk I/O. The C<$offset>
…		…
316	file. The current file offset of the file is left unchanged.	445	file. The current file offset of the file is left unchanged.
317		446
318	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	447	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
319	emulated by simply reading the data, which would have a similar effect.	448	emulated by simply reading the data, which would have a similar effect.
320		449
		450
321	=item aio_stat $fh_or_path, $callback->($status)	451	=item aio_stat $fh_or_path, $callback->($status)
322		452
323	=item aio_lstat $fh, $callback->($status)	453	=item aio_lstat $fh, $callback->($status)
324		454
325	Works like perl's C<stat> or C<lstat> in void context. The callback will	455	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
338	aio_stat "/etc/passwd", sub {	468	aio_stat "/etc/passwd", sub {
339	$_[0] and die "stat failed: $!";	469	$_[0] and die "stat failed: $!";
340	print "size is ", -s _, "\n";	470	print "size is ", -s _, "\n";
341	};	471	};
342		472
		473
		474	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		475
		476	Works like perl's C<utime> function (including the special case of $atime
		477	and $mtime being undef). Fractional times are supported if the underlying
		478	syscalls support them.
		479
		480	When called with a pathname, uses utimes(2) if available, otherwise
		481	utime(2). If called on a file descriptor, uses futimes(2) if available,
		482	otherwise returns ENOSYS, so this is not portable.
		483
		484	Examples:
		485
		486	# set atime and mtime to current time (basically touch(1)):
		487	aio_utime "path", undef, undef;
		488	# set atime to current time and mtime to beginning of the epoch:
		489	aio_utime "path", time, undef; # undef==0
		490
		491
		492	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		493
		494	Works like perl's C<chown> function, except that C<undef> for either $uid
		495	or $gid is being interpreted as "do not change" (but -1 can also be used).
		496
		497	Examples:
		498
		499	# same as "chown root path" in the shell:
		500	aio_chown "path", 0, -1;
		501	# same as above:
		502	aio_chown "path", 0, undef;
		503
		504
		505	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		506
		507	Works like truncate(2) or ftruncate(2).
		508
		509
		510	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		511
		512	Works like perl's C<chmod> function.
		513
		514
343	=item aio_unlink $pathname, $callback->($status)	515	=item aio_unlink $pathname, $callback->($status)
344		516
345	Asynchronously unlink (delete) a file and call the callback with the	517	Asynchronously unlink (delete) a file and call the callback with the
346	result code.	518	result code.
347		519
		520
		521	=item aio_mknod $path, $mode, $dev, $callback->($status)
		522
		523	[EXPERIMENTAL]
		524
		525	Asynchronously create a device node (or fifo). See mknod(2).
		526
		527	The only (POSIX-) portable way of calling this function is:
		528
		529	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		530
		531
348	=item aio_link $srcpath, $dstpath, $callback->($status)	532	=item aio_link $srcpath, $dstpath, $callback->($status)
349		533
350	Asynchronously create a new link to the existing object at C<$srcpath> at	534	Asynchronously create a new link to the existing object at C<$srcpath> at
351	the path C<$dstpath> and call the callback with the result code.	535	the path C<$dstpath> and call the callback with the result code.
352		536
		537
353	=item aio_symlink $srcpath, $dstpath, $callback->($status)	538	=item aio_symlink $srcpath, $dstpath, $callback->($status)
354		539
355	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	540	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
356	the path C<$dstpath> and call the callback with the result code.	541	the path C<$dstpath> and call the callback with the result code.
357		542
		543
		544	=item aio_readlink $path, $callback->($link)
		545
		546	Asynchronously read the symlink specified by C<$path> and pass it to
		547	the callback. If an error occurs, nothing or undef gets passed to the
		548	callback.
		549
		550
358	=item aio_rename $srcpath, $dstpath, $callback->($status)	551	=item aio_rename $srcpath, $dstpath, $callback->($status)
359		552
360	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	553	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
361	rename(2) and call the callback with the result code.	554	rename(2) and call the callback with the result code.
362		555
		556
		557	=item aio_mkdir $pathname, $mode, $callback->($status)
		558
		559	Asynchronously mkdir (create) a directory and call the callback with
		560	the result code. C<$mode> will be modified by the umask at the time the
		561	request is executed, so do not change your umask.
		562
		563
363	=item aio_rmdir $pathname, $callback->($status)	564	=item aio_rmdir $pathname, $callback->($status)
364		565
365	Asynchronously rmdir (delete) a directory and call the callback with the	566	Asynchronously rmdir (delete) a directory and call the callback with the
366	result code.	567	result code.
		568
367		569
368	=item aio_readdir $pathname, $callback->($entries)	570	=item aio_readdir $pathname, $callback->($entries)
369		571
370	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	572	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
371	directory (i.e. opendir + readdir + closedir). The entries will not be	573	directory (i.e. opendir + readdir + closedir). The entries will not be
372	sorted, and will B<NOT> include the C<.> and C<..> entries.	574	sorted, and will B<NOT> include the C<.> and C<..> entries.
373		575
374	The callback a single argument which is either C<undef> or an array-ref	576	The callback a single argument which is either C<undef> or an array-ref
375	with the filenames.	577	with the filenames.
376		578
		579
		580	=item aio_load $path, $data, $callback->($status)
		581
		582	This is a composite request that tries to fully load the given file into
		583	memory. Status is the same as with aio_read.
		584
		585	=cut
		586
		587	sub aio_load($$;$) {
		588	aio_block {
		589	my ($path, undef, $cb) = @_;
		590	my $data = \$_[1];
		591
		592	my $pri = aioreq_pri;
		593	my $grp = aio_group $cb;
		594
		595	aioreq_pri $pri;
		596	add $grp aio_open $path, O_RDONLY, 0, sub {
		597	my $fh = shift
		598	or return $grp->result (-1);
		599
		600	aioreq_pri $pri;
		601	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		602	$grp->result ($_[0]);
		603	};
		604	};
		605
		606	$grp
		607	}
		608	}
		609
		610	=item aio_copy $srcpath, $dstpath, $callback->($status)
		611
		612	Try to copy the I<file> (directories not supported as either source or
		613	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		614	the C<0> (error) or C<-1> ok.
		615
		616	This is a composite request that it creates the destination file with
		617	mode 0200 and copies the contents of the source file into it using
		618	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		619	uid/gid, in that order.
		620
		621	If an error occurs, the partial destination file will be unlinked, if
		622	possible, except when setting atime, mtime, access mode and uid/gid, where
		623	errors are being ignored.
		624
		625	=cut
		626
		627	sub aio_copy($$;$) {
		628	aio_block {
		629	my ($src, $dst, $cb) = @_;
		630
		631	my $pri = aioreq_pri;
		632	my $grp = aio_group $cb;
		633
		634	aioreq_pri $pri;
		635	add $grp aio_open $src, O_RDONLY, 0, sub {
		636	if (my $src_fh = $_[0]) {
		637	my @stat = stat $src_fh;
		638
		639	aioreq_pri $pri;
		640	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		641	if (my $dst_fh = $_[0]) {
		642	aioreq_pri $pri;
		643	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		644	if ($_[0] == $stat[7]) {
		645	$grp->result (0);
		646	close $src_fh;
		647
		648	# those should not normally block. should. should.
		649	utime $stat[8], $stat[9], $dst;
		650	chmod $stat[2] & 07777, $dst_fh;
		651	chown $stat[4], $stat[5], $dst_fh;
		652	close $dst_fh;
		653	} else {
		654	$grp->result (-1);
		655	close $src_fh;
		656	close $dst_fh;
		657
		658	aioreq $pri;
		659	add $grp aio_unlink $dst;
		660	}
		661	};
		662	} else {
		663	$grp->result (-1);
		664	}
		665	},
		666
		667	} else {
		668	$grp->result (-1);
		669	}
		670	};
		671
		672	$grp
		673	}
		674	}
		675
		676	=item aio_move $srcpath, $dstpath, $callback->($status)
		677
		678	Try to move the I<file> (directories not supported as either source or
		679	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		680	the C<0> (error) or C<-1> ok.
		681
		682	This is a composite request that tries to rename(2) the file first. If
		683	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		684	that is successful, unlinking the C<$srcpath>.
		685
		686	=cut
		687
		688	sub aio_move($$;$) {
		689	aio_block {
		690	my ($src, $dst, $cb) = @_;
		691
		692	my $pri = aioreq_pri;
		693	my $grp = aio_group $cb;
		694
		695	aioreq_pri $pri;
		696	add $grp aio_rename $src, $dst, sub {
		697	if ($_[0] && $! == EXDEV) {
		698	aioreq_pri $pri;
		699	add $grp aio_copy $src, $dst, sub {
		700	$grp->result ($_[0]);
		701
		702	if (!$_[0]) {
		703	aioreq_pri $pri;
		704	add $grp aio_unlink $src;
		705	}
		706	};
		707	} else {
		708	$grp->result ($_[0]);
		709	}
		710	};
		711
		712	$grp
		713	}
		714	}
		715
377	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	716	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
378		717
379	Scans a directory (similar to C<aio_readdir>) but additionally tries to	718	Scans a directory (similar to C<aio_readdir>) but additionally tries to
380	separate the entries of directory C<$path> into two sets of names, ones	719	efficiently separate the entries of directory C<$path> into two sets of
381	you can recurse into (directories or links to them), and ones you cannot	720	names, directories you can recurse into (directories), and ones you cannot
382	recurse into (everything else).	721	recurse into (everything else, including symlinks to directories).
383		722
384	C<aio_scandir> is a composite request that creates of many sub requests_	723	C<aio_scandir> is a composite request that creates of many sub requests_
385	C<$maxreq> specifies the maximum number of outstanding aio requests that	724	C<$maxreq> specifies the maximum number of outstanding aio requests that
386	this function generates. If it is C<< <= 0 >>, then a suitable default	725	this function generates. If it is C<< <= 0 >>, then a suitable default
387	will be chosen (currently 6).	726	will be chosen (currently 4).
388		727
389	On error, the callback is called without arguments, otherwise it receives	728	On error, the callback is called without arguments, otherwise it receives
390	two array-refs with path-relative entry names.	729	two array-refs with path-relative entry names.
391		730
392	Example:	731	Example:
…		…
426	as those tend to return 0 or 1 as link counts, which disables the	765	as those tend to return 0 or 1 as link counts, which disables the
427	directory counting heuristic.	766	directory counting heuristic.
428		767
429	=cut	768	=cut
430		769
431	sub aio_scandir($$$) {	770	sub aio_scandir($$;$) {
		771	aio_block {
432	my ($path, $maxreq, $cb) = @_;	772	my ($path, $maxreq, $cb) = @_;
433		773
		774	my $pri = aioreq_pri;
		775
434	my $grp = aio_group $cb;	776	my $grp = aio_group $cb;
435		777
436	$maxreq = 6 if $maxreq <= 0;	778	$maxreq = 4 if $maxreq <= 0;
437		779
438	# stat once	780	# stat once
		781	aioreq_pri $pri;
439	add $grp aio_stat $path, sub {	782	add $grp aio_stat $path, sub {
440	return $grp->result () if $_[0];	783	return $grp->result () if $_[0];
441	my $now = time;	784	my $now = time;
442	my $hash1 = join ":", (stat _)[0,1,3,7,9];	785	my $hash1 = join ":", (stat _)[0,1,3,7,9];
443		786
444	# read the directory entries	787	# read the directory entries
		788	aioreq_pri $pri;
445	add $grp aio_readdir $path, sub {	789	add $grp aio_readdir $path, sub {
446	my $entries = shift	790	my $entries = shift
447	or return $grp->result ();	791	or return $grp->result ();
448		792
449	# stat the dir another time	793	# stat the dir another time
		794	aioreq_pri $pri;
450	add $grp aio_stat $path, sub {	795	add $grp aio_stat $path, sub {
451	my $hash2 = join ":", (stat _)[0,1,3,7,9];	796	my $hash2 = join ":", (stat _)[0,1,3,7,9];
452		797
453	my $ndirs;	798	my $ndirs;
454		799
455	# take the slow route if anything looks fishy	800	# take the slow route if anything looks fishy
456	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	801	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
457	$ndirs = -1;	802	$ndirs = -1;
458	} else {	803	} else {
459	# if nlink == 2, we are finished	804	# if nlink == 2, we are finished
460	# on non-posix-fs's, we rely on nlink < 2	805	# on non-posix-fs's, we rely on nlink < 2
461	$ndirs = (stat _)[3] - 2	806	$ndirs = (stat _)[3] - 2
462	or return $grp->result ([], $entries);	807	or return $grp->result ([], $entries);
463	}	808	}
464		809
465	# sort into likely dirs and likely nondirs	810	# sort into likely dirs and likely nondirs
466	# dirs == files without ".", short entries first	811	# dirs == files without ".", short entries first
467	$entries = [map $_->[0],	812	$entries = [map $_->[0],
468	sort { $b->[1] cmp $a->[1] }	813	sort { $b->[1] cmp $a->[1] }
469	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	814	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
470	@$entries];	815	@$entries];
471		816
472	my (@dirs, @nondirs);	817	my (@dirs, @nondirs);
473		818
474	my ($statcb, $schedcb);
475	my $nreq = 0;
476
477	my $statgrp = add $grp aio_group;	819	my $statgrp = add $grp aio_group sub {
478
479	$schedcb = sub {
480	if (@$entries) {
481	if ($nreq < $maxreq) {
482	my $ent = pop @$entries;
483	$nreq++;
484	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
485	}
486	} elsif (!$nreq) {
487	# finished
488	$statgrp->cancel;
489	undef $statcb;
490	undef $schedcb;
491	$grp->result (\@dirs, \@nondirs);	820	$grp->result (\@dirs, \@nondirs);
492	}	821	};
		822
		823	limit $statgrp $maxreq;
		824	feed $statgrp sub {
		825	return unless @$entries;
		826	my $entry = pop @$entries;
		827
		828	aioreq_pri $pri;
		829	add $statgrp aio_stat "$path/$entry/.", sub {
		830	if ($_[0] < 0) {
		831	push @nondirs, $entry;
		832	} else {
		833	# need to check for real directory
		834	aioreq_pri $pri;
		835	add $statgrp aio_lstat "$path/$entry", sub {
		836	if (-d _) {
		837	push @dirs, $entry;
		838
		839	unless (--$ndirs) {
		840	push @nondirs, @$entries;
		841	feed $statgrp;
		842	}
		843	} else {
		844	push @nondirs, $entry;
		845	}
		846	}
		847	}
		848	};
		849	};
493	};	850	};
494	$statcb = sub {
495	my ($status, $entry) = @_;
496
497	if ($status < 0) {
498	$nreq--;
499	push @nondirs, $entry;
500	&$schedcb;
501	} else {
502	# need to check for real directory
503	add $grp aio_lstat "$path/$entry", sub {
504	$nreq--;
505
506	if (-d _) {
507	push @dirs, $entry;
508
509	if (!--$ndirs) {
510	push @nondirs, @$entries;
511	$entries = [];
512	}
513	} else {
514	push @nondirs, $entry;
515	}
516
517	&$schedcb;
518	}
519	}
520	};
521
522	&$schedcb while @$entries && $nreq < $maxreq;
523	};	851	};
524	};	852	};
		853
		854	$grp
525	};	855	}
		856	}
526		857
		858	=item aio_rmtree $path, $callback->($status)
		859
		860	Delete a directory tree starting (and including) C<$path>, return the
		861	status of the final C<rmdir> only. This is a composite request that
		862	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		863	everything else.
		864
		865	=cut
		866
		867	sub aio_rmtree;
		868	sub aio_rmtree($;$) {
		869	aio_block {
		870	my ($path, $cb) = @_;
		871
		872	my $pri = aioreq_pri;
		873	my $grp = aio_group $cb;
		874
		875	aioreq_pri $pri;
		876	add $grp aio_scandir $path, 0, sub {
		877	my ($dirs, $nondirs) = @_;
		878
		879	my $dirgrp = aio_group sub {
		880	add $grp aio_rmdir $path, sub {
		881	$grp->result ($_[0]);
		882	};
		883	};
		884
		885	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		886	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		887
		888	add $grp $dirgrp;
		889	};
		890
527	$grp	891	$grp
		892	}
528	}	893	}
529		894
530	=item aio_fsync $fh, $callback->($status)	895	=item aio_fsync $fh, $callback->($status)
531		896
532	Asynchronously call fsync on the given filehandle and call the callback	897	Asynchronously call fsync on the given filehandle and call the callback
…		…
539		904
540	If this call isn't available because your OS lacks it or it couldn't be	905	If this call isn't available because your OS lacks it or it couldn't be
541	detected, it will be emulated by calling C<fsync> instead.	906	detected, it will be emulated by calling C<fsync> instead.
542		907
543	=item aio_group $callback->(...)	908	=item aio_group $callback->(...)
544
545	[EXPERIMENTAL]
546		909
547	This is a very special aio request: Instead of doing something, it is a	910	This is a very special aio request: Instead of doing something, it is a
548	container for other aio requests, which is useful if you want to bundle	911	container for other aio requests, which is useful if you want to bundle
549	many requests into a single, composite, request with a definite callback	912	many requests into a single, composite, request with a definite callback
550	and the ability to cancel the whole request with its subrequests.	913	and the ability to cancel the whole request with its subrequests.
…		…
591	=head2 IO::AIO::REQ CLASS	954	=head2 IO::AIO::REQ CLASS
592		955
593	All non-aggregate C<aio_*> functions return an object of this class when	956	All non-aggregate C<aio_*> functions return an object of this class when
594	called in non-void context.	957	called in non-void context.
595		958
596	A request always moves through the following five states in its lifetime,
597	in order: B<ready> (request has been created, but has not been executed
598	yet), B<execute> (request is currently being executed), B<pending>
599	(request has been executed but callback has not been called yet),
600	B<result> (results are being processed synchronously, includes calling the
601	callback) and B<done> (request has reached the end of its lifetime and
602	holds no resources anymore).
603
604	=over 4	959	=over 4
605		960
606	=item cancel $req	961	=item cancel $req
607		962
608	Cancels the request, if possible. Has the effect of skipping execution	963	Cancels the request, if possible. Has the effect of skipping execution
…		…
661	=item * They can also can also be added to other IO::AIO::GRP objects.	1016	=item * They can also can also be added to other IO::AIO::GRP objects.
662		1017
663	=item * You must not add requests to a group from within the group callback (or	1018	=item * You must not add requests to a group from within the group callback (or
664	any later time).	1019	any later time).
665		1020
666	=item * This does not harmonise well with C<max_outstanding>, so best do
667	not combine C<aio_group> with it. Groups and feeders are recommended for
668	this kind of concurrency-limiting.
669
670	=back	1021	=back
671		1022
672	Their lifetime, simplified, looks like this: when they are empty, they	1023	Their lifetime, simplified, looks like this: when they are empty, they
673	will finish very quickly. If they contain only requests that are in the	1024	will finish very quickly. If they contain only requests that are in the
674	C<done> state, they will also finish. Otherwise they will continue to	1025	C<done> state, they will also finish. Otherwise they will continue to
…		…
689	be added, including other groups, as long as you do not create circular	1040	be added, including other groups, as long as you do not create circular
690	dependencies.	1041	dependencies.
691		1042
692	Returns all its arguments.	1043	Returns all its arguments.
693		1044
		1045	=item $grp->cancel_subs
		1046
		1047	Cancel all subrequests and clears any feeder, but not the group request
		1048	itself. Useful when you queued a lot of events but got a result early.
		1049
694	=item $grp->result (...)	1050	=item $grp->result (...)
695		1051
696	Set the result value(s) that will be passed to the group callback when all	1052	Set the result value(s) that will be passed to the group callback when all
697	subrequests have finished. By default, no argument will be passed.	1053	subrequests have finished and set thre groups errno to the current value
		1054	of errno (just like calling C<errno> without an error number). By default,
		1055	no argument will be passed and errno is zero.
		1056
		1057	=item $grp->errno ([$errno])
		1058
		1059	Sets the group errno value to C<$errno>, or the current value of errno
		1060	when the argument is missing.
		1061
		1062	Every aio request has an associated errno value that is restored when
		1063	the callback is invoked. This method lets you change this value from its
		1064	default (0).
		1065
		1066	Calling C<result> will also set errno, so make sure you either set C<$!>
		1067	before the call to C<result>, or call c<errno> after it.
698		1068
699	=item feed $grp $callback->($grp)	1069	=item feed $grp $callback->($grp)
700
701	[VERY EXPERIMENTAL]
702		1070
703	Sets a feeder/generator on this group: every group can have an attached	1071	Sets a feeder/generator on this group: every group can have an attached
704	generator that generates requests if idle. The idea behind this is that,	1072	generator that generates requests if idle. The idea behind this is that,
705	although you could just queue as many requests as you want in a group,	1073	although you could just queue as many requests as you want in a group,
706	this might starve other requests for a potentially long time. For	1074	this might starve other requests for a potentially long time. For
…		…
743		1111
744	=back	1112	=back
745		1113
746	=head2 SUPPORT FUNCTIONS	1114	=head2 SUPPORT FUNCTIONS
747		1115
		1116	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1117
748	=over 4	1118	=over 4
749		1119
750	=item $fileno = IO::AIO::poll_fileno	1120	=item $fileno = IO::AIO::poll_fileno
751		1121
752	Return the I<request result pipe file descriptor>. This filehandle must be	1122	Return the I<request result pipe file descriptor>. This filehandle must be
…		…
756		1126
757	See C<poll_cb> for an example.	1127	See C<poll_cb> for an example.
758		1128
759	=item IO::AIO::poll_cb	1129	=item IO::AIO::poll_cb
760		1130
761	Process all outstanding events on the result pipe. You have to call this	1131	Process some outstanding events on the result pipe. You have to call this
762	regularly. Returns the number of events processed. Returns immediately	1132	regularly. Returns the number of events processed. Returns immediately
763	when no events are outstanding.	1133	when no events are outstanding. The amount of events processed depends on
		1134	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1135
		1136	If not all requests were processed for whatever reason, the filehandle
		1137	will still be ready when C<poll_cb> returns.
764		1138
765	Example: Install an Event watcher that automatically calls	1139	Example: Install an Event watcher that automatically calls
766	IO::AIO::poll_cb with high priority:	1140	IO::AIO::poll_cb with high priority:
767		1141
768	Event->io (fd => IO::AIO::poll_fileno,	1142	Event->io (fd => IO::AIO::poll_fileno,
769	poll => 'r', async => 1,	1143	poll => 'r', async => 1,
770	cb => \&IO::AIO::poll_cb);	1144	cb => \&IO::AIO::poll_cb);
771		1145
		1146	=item IO::AIO::max_poll_reqs $nreqs
		1147
		1148	=item IO::AIO::max_poll_time $seconds
		1149
		1150	These set the maximum number of requests (default C<0>, meaning infinity)
		1151	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1152	the maximum amount of time (default C<0>, meaning infinity) spent in
		1153	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1154	of time C<poll_cb> is allowed to use).
		1155
		1156	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1157	syscall per request processed, which is not normally a problem unless your
		1158	callbacks are really really fast or your OS is really really slow (I am
		1159	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1160
		1161	Setting these is useful if you want to ensure some level of
		1162	interactiveness when perl is not fast enough to process all requests in
		1163	time.
		1164
		1165	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1166
		1167	Example: Install an Event watcher that automatically calls
		1168	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1169	program get the CPU sometimes even under high AIO load.
		1170
		1171	# try not to spend much more than 0.1s in poll_cb
		1172	IO::AIO::max_poll_time 0.1;
		1173
		1174	# use a low priority so other tasks have priority
		1175	Event->io (fd => IO::AIO::poll_fileno,
		1176	poll => 'r', nice => 1,
		1177	cb => &IO::AIO::poll_cb);
		1178
772	=item IO::AIO::poll_wait	1179	=item IO::AIO::poll_wait
773		1180
		1181	If there are any outstanding requests and none of them in the result
774	Wait till the result filehandle becomes ready for reading (simply does a	1182	phase, wait till the result filehandle becomes ready for reading (simply
775	C<select> on the filehandle. This is useful if you want to synchronously wait	1183	does a C<select> on the filehandle. This is useful if you want to
776	for some requests to finish).	1184	synchronously wait for some requests to finish).
777		1185
778	See C<nreqs> for an example.	1186	See C<nreqs> for an example.
779		1187
		1188	=item IO::AIO::poll
		1189
		1190	Waits until some requests have been handled.
		1191
		1192	Returns the number of requests processed, but is otherwise strictly
		1193	equivalent to:
		1194
		1195	IO::AIO::poll_wait, IO::AIO::poll_cb
		1196
780	=item IO::AIO::nreqs	1197	=item IO::AIO::flush
781		1198
782	Returns the number of requests currently outstanding (i.e. for which their	1199	Wait till all outstanding AIO requests have been handled.
783	callback has not been invoked yet).
784		1200
785	Example: wait till there are no outstanding requests anymore:	1201	Strictly equivalent to:
786		1202
787	IO::AIO::poll_wait, IO::AIO::poll_cb	1203	IO::AIO::poll_wait, IO::AIO::poll_cb
788	while IO::AIO::nreqs;	1204	while IO::AIO::nreqs;
789		1205
790	=item IO::AIO::flush	1206	=back
791		1207
792	Wait till all outstanding AIO requests have been handled.	1208	=head3 CONTROLLING THE NUMBER OF THREADS
793		1209
794	Strictly equivalent to:	1210	=over
795
796	IO::AIO::poll_wait, IO::AIO::poll_cb
797	while IO::AIO::nreqs;
798
799	=item IO::AIO::poll
800
801	Waits until some requests have been handled.
802
803	Strictly equivalent to:
804
805	IO::AIO::poll_wait, IO::AIO::poll_cb
806	if IO::AIO::nreqs;
807		1211
808	=item IO::AIO::min_parallel $nthreads	1212	=item IO::AIO::min_parallel $nthreads
809		1213
810	Set the minimum number of AIO threads to C<$nthreads>. The current	1214	Set the minimum number of AIO threads to C<$nthreads>. The current
811	default is C<8>, which means eight asynchronous operations can execute	1215	default is C<8>, which means eight asynchronous operations can execute
812	concurrently at any one time (the number of outstanding requests,	1216	concurrently at any one time (the number of outstanding requests,
813	however, is unlimited).	1217	however, is unlimited).
814		1218
815	IO::AIO starts threads only on demand, when an AIO request is queued and	1219	IO::AIO starts threads only on demand, when an AIO request is queued and
816	no free thread exists.	1220	no free thread exists. Please note that queueing up a hundred requests can
		1221	create demand for a hundred threads, even if it turns out that everything
		1222	is in the cache and could have been processed faster by a single thread.
817		1223
818	It is recommended to keep the number of threads relatively low, as some	1224	It is recommended to keep the number of threads relatively low, as some
819	Linux kernel versions will scale negatively with the number of threads	1225	Linux kernel versions will scale negatively with the number of threads
820	(higher parallelity => MUCH higher latency). With current Linux 2.6	1226	(higher parallelity => MUCH higher latency). With current Linux 2.6
821	versions, 4-32 threads should be fine.	1227	versions, 4-32 threads should be fine.
…		…
835	This module automatically runs C<max_parallel 0> at program end, to ensure	1241	This module automatically runs C<max_parallel 0> at program end, to ensure
836	that all threads are killed and that there are no outstanding requests.	1242	that all threads are killed and that there are no outstanding requests.
837		1243
838	Under normal circumstances you don't need to call this function.	1244	Under normal circumstances you don't need to call this function.
839		1245
		1246	=item IO::AIO::max_idle $nthreads
		1247
		1248	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1249	threads that did not get a request to process within 10 seconds). That
		1250	means if a thread becomes idle while C<$nthreads> other threads are also
		1251	idle, it will free its resources and exit.
		1252
		1253	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1254	to allow for extremely high load situations, but want to free resources
		1255	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1256
		1257	The default is probably ok in most situations, especially if thread
		1258	creation is fast. If thread creation is very slow on your system you might
		1259	want to use larger values.
		1260
840	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1261	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
841		1262
842	[DEPRECATED]	1263	This is a very bad function to use in interactive programs because it
		1264	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1265	use an C<aio_group> together with a feed callback.
843		1266
844	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1267	Sets the maximum number of outstanding requests to C<$nreqs>. If you
845	try to queue up more than this number of requests, the caller will block until	1268	do queue up more than this number of requests, the next call to the
846	some requests have been handled.	1269	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1270	function will block until the limit is no longer exceeded.
847		1271
848	The default is very large, so normally there is no practical limit. If you	1272	The default value is very large, so there is no practical limit on the
849	queue up many requests in a loop it often improves speed if you set	1273	number of outstanding requests.
850	this to a relatively low number, such as C<100>.
851		1274
852	This function does not work well together with C<aio_group>'s, and their	1275	You can still queue as many requests as you want. Therefore,
853	feeder interface is better suited to limiting concurrency, so do not use	1276	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
854	this function.	1277	as a stop gap to shield against fatal memory overflow (with large values).
855
856	Under normal circumstances you don't need to call this function.
857		1278
858	=back	1279	=back
859		1280
		1281	=head3 STATISTICAL INFORMATION
		1282
		1283	=over
		1284
		1285	=item IO::AIO::nreqs
		1286
		1287	Returns the number of requests currently in the ready, execute or pending
		1288	states (i.e. for which their callback has not been invoked yet).
		1289
		1290	Example: wait till there are no outstanding requests anymore:
		1291
		1292	IO::AIO::poll_wait, IO::AIO::poll_cb
		1293	while IO::AIO::nreqs;
		1294
		1295	=item IO::AIO::nready
		1296
		1297	Returns the number of requests currently in the ready state (not yet
		1298	executed).
		1299
		1300	=item IO::AIO::npending
		1301
		1302	Returns the number of requests currently in the pending state (executed,
		1303	but not yet processed by poll_cb).
		1304
		1305	=back
		1306
860	=cut	1307	=cut
861		1308
862	# support function to convert a fd into a perl filehandle
863	sub _fd2fh {
864	return undef if $_[0] < 0;
865
866	# try to generate nice filehandles
867	my $sym = "IO::AIO::fd#$_[0]";
868	local *$sym;
869
870	open *$sym, "+<&=$_[0]" # usually works under any unix
871	or open *$sym, "<&=$_[0]" # cygwin needs this
872	or open *$sym, ">&=$_[0]" # or this
873	or return undef;
874
875	*$sym
876	}
877
878	min_parallel 8;	1309	min_parallel 8;
879		1310
880	END {	1311	END { flush }
881	max_parallel 0;
882	}
883		1312
884	1;	1313	1;
885		1314
886	=head2 FORK BEHAVIOUR	1315	=head2 FORK BEHAVIOUR
887		1316
888	This module should do "the right thing" when the process using it forks:	1317	This module should do "the right thing" when the process using it forks:
889		1318
890	Before the fork, IO::AIO enters a quiescent state where no requests	1319	Before the fork, IO::AIO enters a quiescent state where no requests
891	can be added in other threads and no results will be processed. After	1320	can be added in other threads and no results will be processed. After
892	the fork the parent simply leaves the quiescent state and continues	1321	the fork the parent simply leaves the quiescent state and continues
893	request/result processing, while the child clears the request/result	1322	request/result processing, while the child frees the request/result queue
894	queue (so the requests started before the fork will only be handled in	1323	(so that the requests started before the fork will only be handled in the
895	the parent). Threads will be started on demand until the limit ste in the	1324	parent). Threads will be started on demand until the limit set in the
896	parent process has been reached again.	1325	parent process has been reached again.
897		1326
898	In short: the parent will, after a short pause, continue as if fork had	1327	In short: the parent will, after a short pause, continue as if fork had
899	not been called, while the child will act as if IO::AIO has not been used	1328	not been called, while the child will act as if IO::AIO has not been used
900	yet.	1329	yet.
901		1330
902	=head2 MEMORY USAGE	1331	=head2 MEMORY USAGE
903		1332
		1333	Per-request usage:
		1334
904	Each aio request uses - depending on your architecture - around 128 bytes	1335	Each aio request uses - depending on your architecture - around 100-200
905	of memory. In addition, stat requests need a stat buffer (possibly a few	1336	bytes of memory. In addition, stat requests need a stat buffer (possibly
906	hundred bytes). Perl scalars and other data passed into aio requests will	1337	a few hundred bytes), readdir requires a result buffer and so on. Perl
907	also be locked.	1338	scalars and other data passed into aio requests will also be locked and
		1339	will consume memory till the request has entered the done state.
908		1340
909	This is now awfully much, so queuing lots of requests is not usually a	1341	This is not awfully much, so queuing lots of requests is not usually a
910	problem.	1342	problem.
911		1343
912	Each thread needs a stack area which is usually around 16k, sometimes much	1344	Per-thread usage:
913	larger, depending on the OS.	1345
		1346	In the execution phase, some aio requests require more memory for
		1347	temporary buffers, and each thread requires a stack and other data
		1348	structures (usually around 16k-128k, depending on the OS).
		1349
		1350	=head1 KNOWN BUGS
		1351
		1352	Known bugs will be fixed in the next release.
914		1353
915	=head1 SEE ALSO	1354	=head1 SEE ALSO
916		1355
917	L<Coro::AIO>.	1356	L<Coro::AIO>.
918		1357

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing IO-AIO/AIO.pm (file contents): Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs. Revision 1.117 by root, Sat Oct 6 14:05:19 2007 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs.
Revision 1.117 by root, Sat Oct 6 14:05:19 2007 UTC