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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.67 by root, Tue Oct 24 02:25:16 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
…		…
18	};	19	};
19		20
20	# version 2+ has request and group objects	21	# version 2+ has request and group objects
21	use IO::AIO 2;	22	use IO::AIO 2;
22		23
		24	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	25	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	26	$req->cancel; # cancel request if still in queue
25		27
26	my $grp = aio_group sub { print "all stats done\n" };	28	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	29	add $grp aio_stat "..." for ...;
28		30
29	# AnyEvent integration	31	# AnyEvent integration (EV, Event, Glib, Tk, urxvt, pureperl...)
30	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	32	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
31	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;
32		37
33	# Event integration	38	# Event integration
34	Event->io (fd => IO::AIO::poll_fileno,	39	Event->io (fd => IO::AIO::poll_fileno,
35	poll => 'r',	40	poll => 'r',
36	cb => \&IO::AIO::poll_cb);	41	cb => \&IO::AIO::poll_cb);
…		…
50	=head1 DESCRIPTION	55	=head1 DESCRIPTION
51		56
52	This module implements asynchronous I/O using whatever means your	57	This module implements asynchronous I/O using whatever means your
53	operating system supports.	58	operating system supports.
54		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
55	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
56	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
57	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
58	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
59	on many operating systems. However, they are often not well-supported	80	functions available on many operating systems. However, they are often
60	(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
61	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
62	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.
63		85
64	Although the module will work with in the presence of other threads, it is	86	Although the module will work in the presence of other (Perl-) threads,
65	currently not reentrant, so use appropriate locking yourself, always call	87	it is currently not reentrant in any way, so use appropriate locking
66	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	88	yourself, always call C<poll_cb> from within the same thread, or never
67	C<aio_> functions) recursively.	89	call C<poll_cb> (or other C<aio_> functions) recursively.
		90
		91	=head2 EXAMPLE
		92
		93	This is a simple example that uses the 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
68		186
69	=cut	187	=cut
70		188
71	package IO::AIO;	189	package IO::AIO;
		190
		191	use Carp ();
72		192
73	no warnings;	193	no warnings;
74	use strict 'vars';	194	use strict 'vars';
75		195
76	use base 'Exporter';	196	use base 'Exporter';
77		197
78	BEGIN {	198	BEGIN {
79	our $VERSION = '2.0';	199	our $VERSION = '3.0';
80		200
81	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
82	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	202	aio_stat aio_lstat aio_unlink aio_rmdir aio_readdir
83	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	203	aio_scandir aio_symlink aio_readlink aio_sync aio_fsync
84	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
85	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	209	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
86	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	210	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
87	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);
88		214
89	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	215	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
90		216
91	require XSLoader;	217	require XSLoader;
92	XSLoader::load ("IO::AIO", $VERSION);	218	XSLoader::load ("IO::AIO", $VERSION);
93	}	219	}
94		220
95	=head1 FUNCTIONS	221	=head1 FUNCTIONS
96		222
97	=head2 AIO FUNCTIONS	223	=head2 AIO REQUEST FUNCTIONS
98		224
99	All the C<aio_*> calls are more or less thin wrappers around the syscall	225	All the C<aio_*> calls are more or less thin wrappers around the syscall
100	with the same name (sans C<aio_>). The arguments are similar or identical,	226	with the same name (sans C<aio_>). The arguments are similar or identical,
101	and they all accept an additional (and optional) C<$callback> argument	227	and they all accept an additional (and optional) C<$callback> argument
102	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
…		…
105	syscall has been executed asynchronously.	231	syscall has been executed asynchronously.
106		232
107	All functions expecting a filehandle keep a copy of the filehandle	233	All functions expecting a filehandle keep a copy of the filehandle
108	internally until the request has finished.	234	internally until the request has finished.
109		235
110	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
111	manipulation of those requests while they are in-flight.	237	further manipulation of those requests while they are in-flight.
112		238
113	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
114	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
115	request is being executed, the current working directory could have	241	request is being executed, the current working directory could have
116	changed. Alternatively, you can make sure that you never change the	242	changed. Alternatively, you can make sure that you never change the
117	current working directory.	243	current working directory anywhere in the program and then use relative
		244	paths.
118		245
119	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
120	always pass in filenames you got from outside (command line, readdir	247	in filenames you got from outside (command line, readdir etc.) without
121	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
122	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
123	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)
124	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.
125		255
126	=over 4	256	=over 4
		257
		258	=item $prev_pri = aioreq_pri [$pri]
		259
		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
		263	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		264	and C<4>, respectively. Requests with higher priority will be serviced
		265	first.
		266
		267	The priority will be reset to C<0> after each call to one of the C<aio_*>
		268	functions.
		269
		270	Example: open a file with low priority, then read something from it with
		271	higher priority so the read request is serviced before other low priority
		272	open requests (potentially spamming the cache):
		273
		274	aioreq_pri -3;
		275	aio_open ..., sub {
		276	return unless $_[0];
		277
		278	aioreq_pri -2;
		279	aio_read $_[0], ..., sub {
		280	...
		281	};
		282	};
		283
		284
		285	=item aioreq_nice $pri_adjust
		286
		287	Similar to C<aioreq_pri>, but subtracts the given value from the current
		288	priority, so the effect is cumulative.
		289
127		290
128	=item aio_open $pathname, $flags, $mode, $callback->($fh)	291	=item aio_open $pathname, $flags, $mode, $callback->($fh)
129		292
130	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
131	created filehandle for the file.	294	created filehandle for the file.
…		…
137	list. They are the same as used by C<sysopen>.	300	list. They are the same as used by C<sysopen>.
138		301
139	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
140	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>,
141	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,
142	and C<0666> or C<0777> if you do).	305	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		306	by the umask in effect then the request is being executed, so better never
		307	change the umask.
143		308
144	Example:	309	Example:
145		310
146	aio_open "/etc/passwd", O_RDONLY, 0, sub {	311	aio_open "/etc/passwd", O_RDONLY, 0, sub {
147	if ($_[0]) {	312	if ($_[0]) {
…		…
150	} else {	315	} else {
151	die "open failed: $!\n";	316	die "open failed: $!\n";
152	}	317	}
153	};	318	};
154		319
		320
155	=item aio_close $fh, $callback->($status)	321	=item aio_close $fh, $callback->($status)
156		322
157	Asynchronously close a file and call the callback with the result	323	Asynchronously close a file and call the callback with the result
158	code. I<WARNING:> although accepted, you should not pass in a perl	324	code.
159	filehandle here, as perl will likely close the file descriptor another
160	time when the filehandle is destroyed. Normally, you can safely call perls
161	C<close> or just let filehandles go out of scope.
162		325
163	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
164	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
165		337
166	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	338	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
167		339
168	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	340	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
169		341
170	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<$offset>
171	into the scalar given by C<data> and offset C<dataoffset> and calls the	343	into the scalar given by C<$data> and offset C<$dataoffset> and calls the
172	callback without the actual number of bytes read (or -1 on error, just	344	callback without the actual number of bytes read (or -1 on error, just
173	like the syscall).	345	like the syscall).
174		346
		347	If C<$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
175	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
176	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
177	necessary/optional hardware is installed).	358	the necessary/optional hardware is installed).
178		359
179	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
180	offset C<0> within the scalar:	361	offset C<0> within the scalar:
181		362
182	aio_read $fh, 7, 15, $buffer, 0, sub {	363	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] > 0 or die "read error: $!";	364	$_[0] > 0 or die "read error: $!";
184	print "read $_[0] bytes: <$buffer>\n";	365	print "read $_[0] bytes: <$buffer>\n";
185	};	366	};
186		367
187	=item aio_move $srcpath, $dstpath, $callback->($status)
188
189	[EXPERIMENTAL due to internal aio_group use]
190
191	Try to move the I<file> (directories not supported as either source or
192	destination) from C<$srcpath> to C<$dstpath> and call the callback with
193	the C<0> (error) or C<-1> ok.
194
195	This is a composite request that tries to rename(2) the file first. If
196	rename files with C<EXDEV>, it creates the destination file with mode 0200
197	and copies the contents of the source file into it using C<aio_sendfile>,
198	followed by restoring atime, mtime, access mode and uid/gid, in that
199	order, and unlinking the C<$srcpath>.
200
201	If an error occurs, the partial destination file will be unlinked, if
202	possible, except when setting atime, mtime, access mode and uid/gid, where
203	errors are being ignored.
204
205	=cut
206
207	sub aio_move($$$) {
208	my ($src, $dst, $cb) = @_;
209
210	my $grp = aio_group $cb;
211
212	add $grp aio_rename $src, $dst, sub {
213	if ($_[0] && $! == EXDEV) {
214	add $grp aio_open $src, O_RDONLY, 0, sub {
215	if (my $src_fh = $_[0]) {
216	my @stat = stat $src_fh;
217
218	add $grp aio_open $dst, O_WRONLY, 0200, sub {
219	if (my $dst_fh = $_[0]) {
220	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
221	close $src_fh;
222
223	if ($_[0] == $stat[7]) {
224	utime $stat[8], $stat[9], $dst;
225	chmod $stat[2] & 07777, $dst_fh;
226	chown $stat[4], $stat[5], $dst_fh;
227	close $dst_fh;
228
229	add $grp aio_unlink $src, sub {
230	$grp->result ($_[0]);
231	};
232	} else {
233	my $errno = $!;
234	add $grp aio_unlink $dst, sub {
235	$! = $errno;
236	$grp->result (-1);
237	};
238	}
239	};
240	} else {
241	$grp->result (-1);
242	}
243	},
244
245	} else {
246	$grp->result (-1);
247	}
248	};
249	} else {
250	$grp->result ($_[0]);
251	}
252	};
253
254	$grp
255	}
256		368
257	=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)
258		370
259	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
260	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
…		…
274	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
275	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
276	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
277	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
278	read.	390	read.
		391
279		392
280	=item aio_readahead $fh,$offset,$length, $callback->($retval)	393	=item aio_readahead $fh,$offset,$length, $callback->($retval)
281		394
282	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
283	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>
…		…
289	file. The current file offset of the file is left unchanged.	402	file. The current file offset of the file is left unchanged.
290		403
291	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
292	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.
293		406
		407
294	=item aio_stat $fh_or_path, $callback->($status)	408	=item aio_stat $fh_or_path, $callback->($status)
295		409
296	=item aio_lstat $fh, $callback->($status)	410	=item aio_lstat $fh, $callback->($status)
297		411
298	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
…		…
311	aio_stat "/etc/passwd", sub {	425	aio_stat "/etc/passwd", sub {
312	$_[0] and die "stat failed: $!";	426	$_[0] and die "stat failed: $!";
313	print "size is ", -s _, "\n";	427	print "size is ", -s _, "\n";
314	};	428	};
315		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
316	=item aio_unlink $pathname, $callback->($status)	472	=item aio_unlink $pathname, $callback->($status)
317		473
318	Asynchronously unlink (delete) a file and call the callback with the	474	Asynchronously unlink (delete) a file and call the callback with the
319	result code.	475	result code.
320		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
321	=item aio_link $srcpath, $dstpath, $callback->($status)	489	=item aio_link $srcpath, $dstpath, $callback->($status)
322		490
323	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
324	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.
325		493
		494
326	=item aio_symlink $srcpath, $dstpath, $callback->($status)	495	=item aio_symlink $srcpath, $dstpath, $callback->($status)
327		496
328	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
329	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.
330		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
331	=item aio_rename $srcpath, $dstpath, $callback->($status)	508	=item aio_rename $srcpath, $dstpath, $callback->($status)
332		509
333	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
334	rename(2) and call the callback with the result code.	511	rename(2) and call the callback with the result code.
335		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
336	=item aio_rmdir $pathname, $callback->($status)	521	=item aio_rmdir $pathname, $callback->($status)
337		522
338	Asynchronously rmdir (delete) a directory and call the callback with the	523	Asynchronously rmdir (delete) a directory and call the callback with the
339	result code.	524	result code.
		525
340		526
341	=item aio_readdir $pathname, $callback->($entries)	527	=item aio_readdir $pathname, $callback->($entries)
342		528
343	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
344	directory (i.e. opendir + readdir + closedir). The entries will not be	530	directory (i.e. opendir + readdir + closedir). The entries will not be
345	sorted, and will B<NOT> include the C<.> and C<..> entries.	531	sorted, and will B<NOT> include the C<.> and C<..> entries.
346		532
347	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
348	with the filenames.	534	with the filenames.
349		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
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	669	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		670
352	[EXPERIMENTAL due to internal aio_group use]
353
354	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
355	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
356	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
357	recurse into (everything else).	674	recurse into (everything else, including symlinks to directories).
358		675
359	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_
360	C<$maxreq> specifies the maximum number of outstanding aio requests that	677	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	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
362	will be chosen (currently 6).	679	will be chosen (currently 4).
363		680
364	On error, the callback is called without arguments, otherwise it receives	681	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	682	two array-refs with path-relative entry names.
366		683
367	Example:	684	Example:
…		…
401	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
402	directory counting heuristic.	719	directory counting heuristic.
403		720
404	=cut	721	=cut
405		722
406	sub aio_scandir($$$) {	723	sub aio_scandir($$;$) {
407	my ($path, $maxreq, $cb) = @_;	724	my ($path, $maxreq, $cb) = @_;
408		725
		726	my $pri = aioreq_pri;
		727
409	my $grp = aio_group $cb;	728	my $grp = aio_group $cb;
410		729
411	$maxreq = 6 if $maxreq <= 0;	730	$maxreq = 4 if $maxreq <= 0;
412		731
413	# stat once	732	# stat once
		733	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	734	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	735	return $grp->result () if $_[0];
416	my $now = time;	736	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	737	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		738
419	# read the directory entries	739	# read the directory entries
		740	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	741	add $grp aio_readdir $path, sub {
421	my $entries = shift	742	my $entries = shift
422	or return $grp->result ();	743	or return $grp->result ();
423		744
424	# stat the dir another time	745	# stat the dir another time
		746	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	747	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	748	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		749
428	my $ndirs;	750	my $ndirs;
429		751
…		…
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	766	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];	767	@$entries];
446		768
447	my (@dirs, @nondirs);	769	my (@dirs, @nondirs);
448		770
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	771	my $statgrp = add $grp aio_group sub {
		772	$grp->result (\@dirs, \@nondirs);
		773	};
453		774
454	$schedcb = sub {	775	limit $statgrp $maxreq;
455	if (@$entries) {	776	feed $statgrp sub {
456	if ($nreq < $maxreq) {	777	return unless @$entries;
457	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	}
458	$nreq++;	798	}
459	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
460	}	799	}
461	} elsif (!$nreq) {
462	# finished
463	$statgrp->cancel;
464	undef $statcb;
465	undef $schedcb;
466	$grp->result (\@dirs, \@nondirs);
467	}	800	};
468	};	801	};
469	$statcb = sub {
470	my ($status, $entry) = @_;
471
472	if ($status < 0) {
473	$nreq--;
474	push @nondirs, $entry;
475	&$schedcb;
476	} else {
477	# need to check for real directory
478	add $grp aio_lstat "$path/$entry", sub {
479	$nreq--;
480
481	if (-d _) {
482	push @dirs, $entry;
483
484	if (!--$ndirs) {
485	push @nondirs, @$entries;
486	$entries = [];
487	}
488	} else {
489	push @nondirs, $entry;
490	}
491
492	&$schedcb;
493	}
494	}
495	};
496
497	&$schedcb while @$entries && $nreq < $maxreq;
498	};	802	};
499	};	803	};
500	};	804	};
501		805
502	$grp	806	$grp
503	}	807	}
504		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
505	=item aio_fsync $fh, $callback->($status)	848	=item aio_fsync $fh, $callback->($status)
506		849
507	Asynchronously call fsync on the given filehandle and call the callback	850	Asynchronously call fsync on the given filehandle and call the callback
508	with the fsync result code.	851	with the fsync result code.
509		852
…		…
513	callback with the fdatasync result code.	856	callback with the fdatasync result code.
514		857
515	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
516	detected, it will be emulated by calling C<fsync> instead.	859	detected, it will be emulated by calling C<fsync> instead.
517		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
518	=item aio_group $callback->(...)	899	=item aio_group $callback->(...)
519
520	[EXPERIMENTAL]
521		900
522	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
523	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
524	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.
525		905
526	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
527	for more info.	907	for more info.
528		908
529	Example:	909	Example:
…		…
548	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
549	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
550	entered their execution phase. This can be used to measure request	930	entered their execution phase. This can be used to measure request
551	latency.	931	latency.
552		932
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	933	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
554		934
555	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
556	the request workers to sleep for the given time.	936	the request workers to sleep for the given time.
557		937
558	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
559	like sleep and file handle readable/writable, the overhead this creates	939	like sleep and file handle readable/writable, the overhead this creates is
560	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
561	under artificial I/O pressure.	941	except to put your application under artificial I/O pressure.
562		942
563	=back	943	=back
564		944
565	=head2 IO::AIO::REQ CLASS	945	=head2 IO::AIO::REQ CLASS
566		946
567	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
568	called in non-void context.	948	called in non-void context.
569
570	A request always moves through the following five states in its lifetime,
571	in order: B<ready> (request has been created, but has not been executed
572	yet), B<execute> (request is currently being executed), B<pending>
573	(request has been executed but callback has not been called yet),
574	B<result> (results are being processed synchronously, includes calling the
575	callback) and B<done> (request has reached the end of its lifetime and
576	holds no resources anymore).
577		949
578	=over 4	950	=over 4
579		951
580	=item cancel $req	952	=item cancel $req
581		953
…		…
635	=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.
636		1008
637	=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
638	any later time).	1010	any later time).
639		1011
640	=item * This does not harmonise well with C<max_outstanding>, so best do
641	not combine C<aio_group> with it. Groups and feeders are recommended for
642	this kind of concurrency-limiting.
643
644	=back	1012	=back
645		1013
646	Their lifetime, simplified, looks like this: when they are empty, they	1014	Their lifetime, simplified, looks like this: when they are empty, they
647	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
648	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
…		…
663	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
664	dependencies.	1032	dependencies.
665		1033
666	Returns all its arguments.	1034	Returns all its arguments.
667		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
668	=item $grp->result (...)	1041	=item $grp->result (...)
669		1042
670	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
671	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.
672		1059
673	=item feed $grp $callback->($grp)	1060	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		1061
677	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
678	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,
679	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,
680	this might starve other requests for a potentially long time. For	1065	this might starve other requests for a potentially long time. For
681	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1066	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
682	requests, delaying any later requests for a long time.	1067	requests, delaying any later requests for a long time.
683		1068
684	To avoid this, and allow incremental generation of requests, you can	1069	To avoid this, and allow incremental generation of requests, you can
685	instead a group and set a feeder on it that generates those requests. The	1070	instead a group and set a feeder on it that generates those requests. The
686	feed callback will be called whenever there are few enough (see C<feed_limit>,	1071	feed callback will be called whenever there are few enough (see C<limit>,
687	below) requests active in the group itself and is expected to queue more	1072	below) requests active in the group itself and is expected to queue more
688	requests.	1073	requests.
689		1074
690	The feed can queue as many requests as it likes (i.e. C<add> does not	1075	The feed callback can queue as many requests as it likes (i.e. C<add> does
691	impose any limits).	1076	not impose any limits).
692		1077
693	If the feed does not queue more requests when called, it will be	1078	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	1079	automatically removed from the group.
695		1080
696	If the feed limit is C<0>, it will be set to C<2> automatically.	1081	If the feed limit is C<0>, it will be set to C<2> automatically.
…		…
698	Example:	1083	Example:
699		1084
700	# stat all files in @files, but only ever use four aio requests concurrently:	1085	# stat all files in @files, but only ever use four aio requests concurrently:
701		1086
702	my $grp = aio_group sub { print "finished\n" };	1087	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	1088	limit $grp 4;
704	feed $grp sub {	1089	feed $grp sub {
705	my $file = pop @files	1090	my $file = pop @files
706	or return;	1091	or return;
707		1092
708	add $grp aio_stat $file, sub { ... };	1093	add $grp aio_stat $file, sub { ... };
709	};	1094	};
710		1095
711	=item feed_limit $grp $num	1096	=item limit $grp $num
712		1097
713	Sets the feeder limit for the group: The feeder will be called whenever	1098	Sets the feeder limit for the group: The feeder will be called whenever
714	the group contains less than this many requests.	1099	the group contains less than this many requests.
715		1100
716	Setting the limit to C<0> will pause the feeding process.	1101	Setting the limit to C<0> will pause the feeding process.
717		1102
718	=back	1103	=back
719		1104
720	=head2 SUPPORT FUNCTIONS	1105	=head2 SUPPORT FUNCTIONS
		1106
		1107	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
721		1108
722	=over 4	1109	=over 4
723		1110
724	=item $fileno = IO::AIO::poll_fileno	1111	=item $fileno = IO::AIO::poll_fileno
725		1112
…		…
730		1117
731	See C<poll_cb> for an example.	1118	See C<poll_cb> for an example.
732		1119
733	=item IO::AIO::poll_cb	1120	=item IO::AIO::poll_cb
734		1121
735	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
736	regularly. Returns the number of events processed. Returns immediately	1123	regularly. Returns the number of events processed. Returns immediately
737	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.
738		1129
739	Example: Install an Event watcher that automatically calls	1130	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	1131	IO::AIO::poll_cb with high priority:
741		1132
742	Event->io (fd => IO::AIO::poll_fileno,	1133	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	1134	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	1135	cb => \&IO::AIO::poll_cb);
745		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
746	=item IO::AIO::poll_wait	1170	=item IO::AIO::poll_wait
747		1171
		1172	If there are any outstanding requests and none of them in the result
748	Wait till the result filehandle becomes ready for reading (simply does a	1173	phase, wait till the result filehandle becomes ready for reading (simply
749	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
750	for some requests to finish).	1175	synchronously wait for some requests to finish).
751		1176
752	See C<nreqs> for an example.	1177	See C<nreqs> for an example.
753		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
754	=item IO::AIO::nreqs	1188	=item IO::AIO::flush
755		1189
756	Returns the number of requests currently outstanding (i.e. for which their	1190	Wait till all outstanding AIO requests have been handled.
757	callback has not been invoked yet).
758		1191
759	Example: wait till there are no outstanding requests anymore:	1192	Strictly equivalent to:
760		1193
761	IO::AIO::poll_wait, IO::AIO::poll_cb	1194	IO::AIO::poll_wait, IO::AIO::poll_cb
762	while IO::AIO::nreqs;	1195	while IO::AIO::nreqs;
763		1196
764	=item IO::AIO::flush	1197	=back
765		1198
766	Wait till all outstanding AIO requests have been handled.	1199	=head3 CONTROLLING THE NUMBER OF THREADS
767		1200
768	Strictly equivalent to:	1201	=over
769
770	IO::AIO::poll_wait, IO::AIO::poll_cb
771	while IO::AIO::nreqs;
772
773	=item IO::AIO::poll
774
775	Waits until some requests have been handled.
776
777	Strictly equivalent to:
778
779	IO::AIO::poll_wait, IO::AIO::poll_cb
780	if IO::AIO::nreqs;
781		1202
782	=item IO::AIO::min_parallel $nthreads	1203	=item IO::AIO::min_parallel $nthreads
783		1204
784	Set the minimum number of AIO threads to C<$nthreads>. The current	1205	Set the minimum number of AIO threads to C<$nthreads>. The current
785	default is C<8>, which means eight asynchronous operations can execute	1206	default is C<8>, which means eight asynchronous operations can execute
786	concurrently at any one time (the number of outstanding requests,	1207	concurrently at any one time (the number of outstanding requests,
787	however, is unlimited).	1208	however, is unlimited).
788		1209
789	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
790	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.
791		1214
792	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
793	Linux kernel versions will scale negatively with the number of threads	1216	Linux kernel versions will scale negatively with the number of threads
794	(higher parallelity => MUCH higher latency). With current Linux 2.6	1217	(higher parallelity => MUCH higher latency). With current Linux 2.6
795	versions, 4-32 threads should be fine.	1218	versions, 4-32 threads should be fine.
…		…
809	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
810	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.
811		1234
812	Under normal circumstances you don't need to call this function.	1235	Under normal circumstances you don't need to call this function.
813		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
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1252	=item IO::AIO::max_outstanding $maxreqs
815		1253
816	[DEPRECATED]	1254	This is a very bad function to use in interactive programs because it
		1255	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1256	use an C<aio_group> together with a feed callback.
817		1257
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1258	Sets the maximum number of outstanding requests to C<$nreqs>. If you
819	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
820	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.
821		1262
822	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
823	queue up many requests in a loop it often improves speed if you set	1264	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		1265
826	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,
827	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
828	this function.	1268	as a stop gap to shield against fatal memory overflow (with large values).
829
830	Under normal circumstances you don't need to call this function.
831		1269
832	=back	1270	=back
833		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
834	=cut	1298	=cut
835		1299
836	# support function to convert a fd into a perl filehandle
837	sub _fd2fh {
838	return undef if $_[0] < 0;
839
840	# try to generate nice filehandles
841	my $sym = "IO::AIO::fd#$_[0]";
842	local *$sym;
843
844	open *$sym, "+<&=$_[0]" # usually works under any unix
845	or open *$sym, "<&=$_[0]" # cygwin needs this
846	or open *$sym, ">&=$_[0]" # or this
847	or return undef;
848
849	*$sym
850	}
851
852	min_parallel 8;	1300	min_parallel 8;
853		1301
854	END {	1302	END { flush }
855	max_parallel 0;
856	}
857		1303
858	1;	1304	1;
859		1305
860	=head2 FORK BEHAVIOUR	1306	=head2 FORK BEHAVIOUR
861		1307
862	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:
863		1309
864	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
865	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
866	the fork the parent simply leaves the quiescent state and continues	1312	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	1313	request/result processing, while the child frees the request/result queue
868	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
869	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
870	parent process has been reached again.	1316	parent process has been reached again.
871		1317
872	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
873	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
874	yet.	1320	yet.
875		1321
876	=head2 MEMORY USAGE	1322	=head2 MEMORY USAGE
877		1323
		1324	Per-request usage:
		1325
878	Each aio request uses - depending on your architecture - around 128 bytes	1326	Each aio request uses - depending on your architecture - around 100-200
879	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
880	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
881	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.
882		1331
883	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
884	problem.	1333	problem.
885		1334
886	Each thread needs a stack area which is usually around 16k, sometimes much	1335	Per-thread usage:
887	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.
888		1344
889	=head1 SEE ALSO	1345	=head1 SEE ALSO
890		1346
891	L<Coro>, L<Linux::AIO> (obsolete).	1347	L<Coro::AIO>.
892		1348
893	=head1 AUTHOR	1349	=head1 AUTHOR
894		1350
895	Marc Lehmann <schmorp@schmorp.de>	1351	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1352	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.67 by root, Tue Oct 24 02:25:16 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 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs.
Revision 1.124 by root, Sat May 10 19:25:33 2008 UTC