[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 1.108 by root, Fri Jun 1 13:25:50 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
…		…
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 ...;
…		…
50	=head1 DESCRIPTION	52	=head1 DESCRIPTION
51		53
52	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
53	operating system supports.	55	operating system supports.
54		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
55	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
56	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
57	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
58	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
59	on many operating systems. However, they are often not well-supported	77	functions available on many operating systems. However, they are often
60	(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
61	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
62	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.
63		82
64	Although the module will work with in the presence of other threads, it is	83	Although the module will work in the presence of other (Perl-) threads,
65	currently not reentrant, so use appropriate locking yourself, always call	84	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	85	yourself, always call C<poll_cb> from within the same thread, or never
67	C<aio_> functions) recursively.	86	call C<poll_cb> (or other C<aio_> functions) recursively.
		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
68		183
69	=cut	184	=cut
70		185
71	package IO::AIO;	186	package IO::AIO;
72		187
…		…
74	use strict 'vars';	189	use strict 'vars';
75		190
76	use base 'Exporter';	191	use base 'Exporter';
77		192
78	BEGIN {	193	BEGIN {
79	our $VERSION = '2.0';	194	our $VERSION = '2.4';
80		195
81	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	196	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
82	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	197	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
83	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	198	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
84	aio_group aio_nop);	199	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
		200	aio_chown aio_chmod aio_utime);
85	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
86	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
87	min_parallel max_parallel max_outstanding nreqs);	203	min_parallel max_parallel max_idle
		204	nreqs nready npending nthreads
		205	max_poll_time max_poll_reqs);
88		206
89	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
90		208
91	require XSLoader;	209	require XSLoader;
92	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
93	}	211	}
94		212
95	=head1 FUNCTIONS	213	=head1 FUNCTIONS
96		214
97	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
98		216
99	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
100	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
101	and they all accept an additional (and optional) C<$callback> argument	219	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	220	which must be a code reference. This code reference will get called with
…		…
105	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
106		224
107	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
108	internally until the request has finished.	226	internally until the request has finished.
109		227
110	All requests return objects of type L<IO::AIO::REQ> that allow further	228	All functions return request objects of type L<IO::AIO::REQ> that allow
111	manipulation of those requests while they are in-flight.	229	further manipulation of those requests while they are in-flight.
112		230
113	The pathnames you pass to these routines I<must> be absolute and	231	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	232	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	233	request is being executed, the current working directory could have
116	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
117	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
118		237
119	To encode pathnames to byte form, either make sure you either: a)	238	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	239	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	240	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	241	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)	242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
124	use something else.	243	use something else to ensure your scalar has the correct contents.
		244
		245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		246	handles correctly wether it is set or not.
125		247
126	=over 4	248	=over 4
		249
		250	=item $prev_pri = aioreq_pri [$pri]
		251
		252	Returns the priority value that would be used for the next request and, if
		253	C<$pri> is given, sets the priority for the next aio request.
		254
		255	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		256	and C<4>, respectively. Requests with higher priority will be serviced
		257	first.
		258
		259	The priority will be reset to C<0> after each call to one of the C<aio_*>
		260	functions.
		261
		262	Example: open a file with low priority, then read something from it with
		263	higher priority so the read request is serviced before other low priority
		264	open requests (potentially spamming the cache):
		265
		266	aioreq_pri -3;
		267	aio_open ..., sub {
		268	return unless $_[0];
		269
		270	aioreq_pri -2;
		271	aio_read $_[0], ..., sub {
		272	...
		273	};
		274	};
		275
		276
		277	=item aioreq_nice $pri_adjust
		278
		279	Similar to C<aioreq_pri>, but subtracts the given value from the current
		280	priority, so the effect is cumulative.
		281
127		282
128	=item aio_open $pathname, $flags, $mode, $callback->($fh)	283	=item aio_open $pathname, $flags, $mode, $callback->($fh)
129		284
130	Asynchronously open or create a file and call the callback with a newly	285	Asynchronously open or create a file and call the callback with a newly
131	created filehandle for the file.	286	created filehandle for the file.
…		…
137	list. They are the same as used by C<sysopen>.	292	list. They are the same as used by C<sysopen>.
138		293
139	Likewise, C<$mode> specifies the mode of the newly created file, if it	294	Likewise, C<$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>,	295	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,	296	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).	297	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		298	by the umask in effect then the request is being executed, so better never
		299	change the umask.
143		300
144	Example:	301	Example:
145		302
146	aio_open "/etc/passwd", O_RDONLY, 0, sub {	303	aio_open "/etc/passwd", O_RDONLY, 0, sub {
147	if ($_[0]) {	304	if ($_[0]) {
…		…
150	} else {	307	} else {
151	die "open failed: $!\n";	308	die "open failed: $!\n";
152	}	309	}
153	};	310	};
154		311
		312
155	=item aio_close $fh, $callback->($status)	313	=item aio_close $fh, $callback->($status)
156		314
157	Asynchronously close a file and call the callback with the result	315	Asynchronously close a file and call the callback with the result
158	code. I<WARNING:> although accepted, you should not pass in a perl	316	code. I<WARNING:> although accepted, you should not pass in a perl
159	filehandle here, as perl will likely close the file descriptor another	317	filehandle here, as perl will likely close the file descriptor another
…		…
161	C<close> or just let filehandles go out of scope.	319	C<close> or just let filehandles go out of scope.
162		320
163	This is supposed to be a bug in the API, so that might change. It's	321	This is supposed to be a bug in the API, so that might change. It's
164	therefore best to avoid this function.	322	therefore best to avoid this function.
165		323
		324
166	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	325	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
167		326
168	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	327	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
169		328
170	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	329	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	330	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	331	callback without the actual number of bytes read (or -1 on error, just
173	like the syscall).	332	like the syscall). If C<offset> is undefined, then the current file offset
		333	will be used (and updated), otherwise the file offset will not be changed
		334	by these calls.
174		335
175	The C<$data> scalar I<MUST NOT> be modified in any way while the request	336	The C<$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	337	is outstanding. Modifying it can result in segfaults or World War III (if
177	necessary/optional hardware is installed).	338	the necessary/optional hardware is installed).
178		339
179	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	340	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
180	offset C<0> within the scalar:	341	offset C<0> within the scalar:
181		342
182	aio_read $fh, 7, 15, $buffer, 0, sub {	343	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] > 0 or die "read error: $!";	344	$_[0] > 0 or die "read error: $!";
184	print "read $_[0] bytes: <$buffer>\n";	345	print "read $_[0] bytes: <$buffer>\n";
185	};	346	};
186		347
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		348
257	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	349	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
258		350
259	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	351	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	352	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	366	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	367	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	368	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	369	value equals C<$length> one can assume that C<$length> bytes have been
278	read.	370	read.
		371
279		372
280	=item aio_readahead $fh,$offset,$length, $callback->($retval)	373	=item aio_readahead $fh,$offset,$length, $callback->($retval)
281		374
282	C<aio_readahead> populates the page cache with data from a file so that	375	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>	376	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.	382	file. The current file offset of the file is left unchanged.
290		383
291	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	384	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.	385	emulated by simply reading the data, which would have a similar effect.
293		386
		387
294	=item aio_stat $fh_or_path, $callback->($status)	388	=item aio_stat $fh_or_path, $callback->($status)
295		389
296	=item aio_lstat $fh, $callback->($status)	390	=item aio_lstat $fh, $callback->($status)
297		391
298	Works like perl's C<stat> or C<lstat> in void context. The callback will	392	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
311	aio_stat "/etc/passwd", sub {	405	aio_stat "/etc/passwd", sub {
312	$_[0] and die "stat failed: $!";	406	$_[0] and die "stat failed: $!";
313	print "size is ", -s _, "\n";	407	print "size is ", -s _, "\n";
314	};	408	};
315		409
		410
		411	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		412
		413	Works like perl's C<utime> function (including the special case of $atime
		414	and $mtime being undef). Fractional times are supported if the underlying
		415	syscalls support them.
		416
		417	When called with a pathname, uses utimes(2) if available, otherwise
		418	utime(2). If called on a file descriptor, uses futimes(2) if available,
		419	otherwise returns ENOSYS, so this is not portable.
		420
		421	Examples:
		422
		423	# set atime and mtime to current time (basically touch(1)):
		424	aio_utime "path", undef, undef;
		425	# set atime to current time and mtime to beginning of the epoch:
		426	aio_utime "path", time, undef; # undef==0
		427
		428
		429	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		430
		431	Works like perl's C<chown> function, except that C<undef> for either $uid
		432	or $gid is being interpreted as "do not change" (but -1 can also be used).
		433
		434	Examples:
		435
		436	# same as "chown root path" in the shell:
		437	aio_chown "path", 0, -1;
		438	# same as above:
		439	aio_chown "path", 0, undef;
		440
		441
		442	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		443
		444	Works like perl's C<chmod> function.
		445
		446
316	=item aio_unlink $pathname, $callback->($status)	447	=item aio_unlink $pathname, $callback->($status)
317		448
318	Asynchronously unlink (delete) a file and call the callback with the	449	Asynchronously unlink (delete) a file and call the callback with the
319	result code.	450	result code.
320		451
		452
		453	=item aio_mknod $path, $mode, $dev, $callback->($status)
		454
		455	[EXPERIMENTAL]
		456
		457	Asynchronously create a device node (or fifo). See mknod(2).
		458
		459	The only (POSIX-) portable way of calling this function is:
		460
		461	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		462
		463
321	=item aio_link $srcpath, $dstpath, $callback->($status)	464	=item aio_link $srcpath, $dstpath, $callback->($status)
322		465
323	Asynchronously create a new link to the existing object at C<$srcpath> at	466	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.	467	the path C<$dstpath> and call the callback with the result code.
325		468
		469
326	=item aio_symlink $srcpath, $dstpath, $callback->($status)	470	=item aio_symlink $srcpath, $dstpath, $callback->($status)
327		471
328	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	472	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.	473	the path C<$dstpath> and call the callback with the result code.
330		474
		475
		476	=item aio_readlink $path, $callback->($link)
		477
		478	Asynchronously read the symlink specified by C<$path> and pass it to
		479	the callback. If an error occurs, nothing or undef gets passed to the
		480	callback.
		481
		482
331	=item aio_rename $srcpath, $dstpath, $callback->($status)	483	=item aio_rename $srcpath, $dstpath, $callback->($status)
332		484
333	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	485	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
334	rename(2) and call the callback with the result code.	486	rename(2) and call the callback with the result code.
335		487
		488
		489	=item aio_mkdir $pathname, $mode, $callback->($status)
		490
		491	Asynchronously mkdir (create) a directory and call the callback with
		492	the result code. C<$mode> will be modified by the umask at the time the
		493	request is executed, so do not change your umask.
		494
		495
336	=item aio_rmdir $pathname, $callback->($status)	496	=item aio_rmdir $pathname, $callback->($status)
337		497
338	Asynchronously rmdir (delete) a directory and call the callback with the	498	Asynchronously rmdir (delete) a directory and call the callback with the
339	result code.	499	result code.
		500
340		501
341	=item aio_readdir $pathname, $callback->($entries)	502	=item aio_readdir $pathname, $callback->($entries)
342		503
343	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	504	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	505	directory (i.e. opendir + readdir + closedir). The entries will not be
345	sorted, and will B<NOT> include the C<.> and C<..> entries.	506	sorted, and will B<NOT> include the C<.> and C<..> entries.
346		507
347	The callback a single argument which is either C<undef> or an array-ref	508	The callback a single argument which is either C<undef> or an array-ref
348	with the filenames.	509	with the filenames.
349		510
		511
		512	=item aio_load $path, $data, $callback->($status)
		513
		514	This is a composite request that tries to fully load the given file into
		515	memory. Status is the same as with aio_read.
		516
		517	=cut
		518
		519	sub aio_load($$;$) {
		520	aio_block {
		521	my ($path, undef, $cb) = @_;
		522	my $data = \$_[1];
		523
		524	my $pri = aioreq_pri;
		525	my $grp = aio_group $cb;
		526
		527	aioreq_pri $pri;
		528	add $grp aio_open $path, O_RDONLY, 0, sub {
		529	my $fh = shift
		530	or return $grp->result (-1);
		531
		532	aioreq_pri $pri;
		533	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		534	$grp->result ($_[0]);
		535	};
		536	};
		537
		538	$grp
		539	}
		540	}
		541
		542	=item aio_copy $srcpath, $dstpath, $callback->($status)
		543
		544	Try to copy the I<file> (directories not supported as either source or
		545	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		546	the C<0> (error) or C<-1> ok.
		547
		548	This is a composite request that it creates the destination file with
		549	mode 0200 and copies the contents of the source file into it using
		550	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		551	uid/gid, in that order.
		552
		553	If an error occurs, the partial destination file will be unlinked, if
		554	possible, except when setting atime, mtime, access mode and uid/gid, where
		555	errors are being ignored.
		556
		557	=cut
		558
		559	sub aio_copy($$;$) {
		560	aio_block {
		561	my ($src, $dst, $cb) = @_;
		562
		563	my $pri = aioreq_pri;
		564	my $grp = aio_group $cb;
		565
		566	aioreq_pri $pri;
		567	add $grp aio_open $src, O_RDONLY, 0, sub {
		568	if (my $src_fh = $_[0]) {
		569	my @stat = stat $src_fh;
		570
		571	aioreq_pri $pri;
		572	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		573	if (my $dst_fh = $_[0]) {
		574	aioreq_pri $pri;
		575	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		576	if ($_[0] == $stat[7]) {
		577	$grp->result (0);
		578	close $src_fh;
		579
		580	# those should not normally block. should. should.
		581	utime $stat[8], $stat[9], $dst;
		582	chmod $stat[2] & 07777, $dst_fh;
		583	chown $stat[4], $stat[5], $dst_fh;
		584	close $dst_fh;
		585	} else {
		586	$grp->result (-1);
		587	close $src_fh;
		588	close $dst_fh;
		589
		590	aioreq $pri;
		591	add $grp aio_unlink $dst;
		592	}
		593	};
		594	} else {
		595	$grp->result (-1);
		596	}
		597	},
		598
		599	} else {
		600	$grp->result (-1);
		601	}
		602	};
		603
		604	$grp
		605	}
		606	}
		607
		608	=item aio_move $srcpath, $dstpath, $callback->($status)
		609
		610	Try to move the I<file> (directories not supported as either source or
		611	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		612	the C<0> (error) or C<-1> ok.
		613
		614	This is a composite request that tries to rename(2) the file first. If
		615	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		616	that is successful, unlinking the C<$srcpath>.
		617
		618	=cut
		619
		620	sub aio_move($$;$) {
		621	aio_block {
		622	my ($src, $dst, $cb) = @_;
		623
		624	my $pri = aioreq_pri;
		625	my $grp = aio_group $cb;
		626
		627	aioreq_pri $pri;
		628	add $grp aio_rename $src, $dst, sub {
		629	if ($_[0] && $! == EXDEV) {
		630	aioreq_pri $pri;
		631	add $grp aio_copy $src, $dst, sub {
		632	$grp->result ($_[0]);
		633
		634	if (!$_[0]) {
		635	aioreq_pri $pri;
		636	add $grp aio_unlink $src;
		637	}
		638	};
		639	} else {
		640	$grp->result ($_[0]);
		641	}
		642	};
		643
		644	$grp
		645	}
		646	}
		647
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	648	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		649
352	[EXPERIMENTAL due to internal aio_group use]
353
354	Scans a directory (similar to C<aio_readdir>) but additionally tries to	650	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	651	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	652	names, directories you can recurse into (directories), and ones you cannot
357	recurse into (everything else).	653	recurse into (everything else, including symlinks to directories).
358		654
359	C<aio_scandir> is a composite request that creates of many sub requests_	655	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	656	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	this function generates. If it is C<< <= 0 >>, then a suitable default	657	this function generates. If it is C<< <= 0 >>, then a suitable default
362	will be chosen (currently 6).	658	will be chosen (currently 4).
363		659
364	On error, the callback is called without arguments, otherwise it receives	660	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	661	two array-refs with path-relative entry names.
366		662
367	Example:	663	Example:
…		…
401	as those tend to return 0 or 1 as link counts, which disables the	697	as those tend to return 0 or 1 as link counts, which disables the
402	directory counting heuristic.	698	directory counting heuristic.
403		699
404	=cut	700	=cut
405		701
406	sub aio_scandir($$$) {	702	sub aio_scandir($$;$) {
		703	aio_block {
407	my ($path, $maxreq, $cb) = @_;	704	my ($path, $maxreq, $cb) = @_;
408		705
		706	my $pri = aioreq_pri;
		707
409	my $grp = aio_group $cb;	708	my $grp = aio_group $cb;
410		709
411	$maxreq = 6 if $maxreq <= 0;	710	$maxreq = 4 if $maxreq <= 0;
412		711
413	# stat once	712	# stat once
		713	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	714	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	715	return $grp->result () if $_[0];
416	my $now = time;	716	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	717	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		718
419	# read the directory entries	719	# read the directory entries
		720	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	721	add $grp aio_readdir $path, sub {
421	my $entries = shift	722	my $entries = shift
422	or return $grp->result ();	723	or return $grp->result ();
423		724
424	# stat the dir another time	725	# stat the dir another time
		726	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	727	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	728	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		729
428	my $ndirs;	730	my $ndirs;
429		731
430	# take the slow route if anything looks fishy	732	# take the slow route if anything looks fishy
431	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	733	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
432	$ndirs = -1;	734	$ndirs = -1;
433	} else {	735	} else {
434	# if nlink == 2, we are finished	736	# if nlink == 2, we are finished
435	# on non-posix-fs's, we rely on nlink < 2	737	# on non-posix-fs's, we rely on nlink < 2
436	$ndirs = (stat _)[3] - 2	738	$ndirs = (stat _)[3] - 2
437	or return $grp->result ([], $entries);	739	or return $grp->result ([], $entries);
438	}	740	}
439		741
440	# sort into likely dirs and likely nondirs	742	# sort into likely dirs and likely nondirs
441	# dirs == files without ".", short entries first	743	# dirs == files without ".", short entries first
442	$entries = [map $_->[0],	744	$entries = [map $_->[0],
443	sort { $b->[1] cmp $a->[1] }	745	sort { $b->[1] cmp $a->[1] }
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	746	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];	747	@$entries];
446		748
447	my (@dirs, @nondirs);	749	my (@dirs, @nondirs);
448		750
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	751	my $statgrp = add $grp aio_group sub {
453
454	$schedcb = sub {
455	if (@$entries) {
456	if ($nreq < $maxreq) {
457	my $ent = pop @$entries;
458	$nreq++;
459	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
460	}
461	} elsif (!$nreq) {
462	# finished
463	$statgrp->cancel;
464	undef $statcb;
465	undef $schedcb;
466	$grp->result (\@dirs, \@nondirs);	752	$grp->result (\@dirs, \@nondirs);
467	}	753	};
		754
		755	limit $statgrp $maxreq;
		756	feed $statgrp sub {
		757	return unless @$entries;
		758	my $entry = pop @$entries;
		759
		760	aioreq_pri $pri;
		761	add $statgrp aio_stat "$path/$entry/.", sub {
		762	if ($_[0] < 0) {
		763	push @nondirs, $entry;
		764	} else {
		765	# need to check for real directory
		766	aioreq_pri $pri;
		767	add $statgrp aio_lstat "$path/$entry", sub {
		768	if (-d _) {
		769	push @dirs, $entry;
		770
		771	unless (--$ndirs) {
		772	push @nondirs, @$entries;
		773	feed $statgrp;
		774	}
		775	} else {
		776	push @nondirs, $entry;
		777	}
		778	}
		779	}
		780	};
		781	};
468	};	782	};
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	};	783	};
499	};	784	};
		785
		786	$grp
500	};	787	}
		788	}
501		789
		790	=item aio_rmtree $path, $callback->($status)
		791
		792	Delete a directory tree starting (and including) C<$path>, return the
		793	status of the final C<rmdir> only. This is a composite request that
		794	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		795	everything else.
		796
		797	=cut
		798
		799	sub aio_rmtree;
		800	sub aio_rmtree($;$) {
		801	aio_block {
		802	my ($path, $cb) = @_;
		803
		804	my $pri = aioreq_pri;
		805	my $grp = aio_group $cb;
		806
		807	aioreq_pri $pri;
		808	add $grp aio_scandir $path, 0, sub {
		809	my ($dirs, $nondirs) = @_;
		810
		811	my $dirgrp = aio_group sub {
		812	add $grp aio_rmdir $path, sub {
		813	$grp->result ($_[0]);
		814	};
		815	};
		816
		817	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		818	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		819
		820	add $grp $dirgrp;
		821	};
		822
502	$grp	823	$grp
		824	}
503	}	825	}
504		826
505	=item aio_fsync $fh, $callback->($status)	827	=item aio_fsync $fh, $callback->($status)
506		828
507	Asynchronously call fsync on the given filehandle and call the callback	829	Asynchronously call fsync on the given filehandle and call the callback
…		…
515	If this call isn't available because your OS lacks it or it couldn't be	837	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.	838	detected, it will be emulated by calling C<fsync> instead.
517		839
518	=item aio_group $callback->(...)	840	=item aio_group $callback->(...)
519		841
520	[EXPERIMENTAL]
521
522	This is a very special aio request: Instead of doing something, it is a	842	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	843	container for other aio requests, which is useful if you want to bundle
524	many requests into a single, composite, request.	844	many requests into a single, composite, request with a definite callback
		845	and the ability to cancel the whole request with its subrequests.
525		846
526	Returns an object of class L<IO::AIO::GRP>. See its documentation below	847	Returns an object of class L<IO::AIO::GRP>. See its documentation below
527	for more info.	848	for more info.
528		849
529	Example:	850	Example:
…		…
548	phase and still requires a worker thread. Thus, the callback will not	869	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	870	be executed immediately but only after other requests in the queue have
550	entered their execution phase. This can be used to measure request	871	entered their execution phase. This can be used to measure request
551	latency.	872	latency.
552		873
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	874	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
554		875
555	Mainly used for debugging and benchmarking, this aio request puts one of	876	Mainly used for debugging and benchmarking, this aio request puts one of
556	the request workers to sleep for the given time.	877	the request workers to sleep for the given time.
557		878
558	While it is theoretically handy to have simple I/O scheduling requests	879	While it is theoretically handy to have simple I/O scheduling requests
559	like sleep and file handle readable/writable, the overhead this creates	880	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	881	immense (it blocks a thread for a long time) so do not use this function
561	under artificial I/O pressure.	882	except to put your application under artificial I/O pressure.
562		883
563	=back	884	=back
564		885
565	=head2 IO::AIO::REQ CLASS	886	=head2 IO::AIO::REQ CLASS
566		887
567	All non-aggregate C<aio_*> functions return an object of this class when	888	All non-aggregate C<aio_*> functions return an object of this class when
568	called in non-void context.	889	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		890
578	=over 4	891	=over 4
579		892
580	=item cancel $req	893	=item cancel $req
581		894
…		…
635	=item * They can also can also be added to other IO::AIO::GRP objects.	948	=item * They can also can also be added to other IO::AIO::GRP objects.
636		949
637	=item * You must not add requests to a group from within the group callback (or	950	=item * You must not add requests to a group from within the group callback (or
638	any later time).	951	any later time).
639		952
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	953	=back
645		954
646	Their lifetime, simplified, looks like this: when they are empty, they	955	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	956	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	957	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	972	be added, including other groups, as long as you do not create circular
664	dependencies.	973	dependencies.
665		974
666	Returns all its arguments.	975	Returns all its arguments.
667		976
		977	=item $grp->cancel_subs
		978
		979	Cancel all subrequests and clears any feeder, but not the group request
		980	itself. Useful when you queued a lot of events but got a result early.
		981
668	=item $grp->result (...)	982	=item $grp->result (...)
669		983
670	Set the result value(s) that will be passed to the group callback when all	984	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.	985	subrequests have finished and set thre groups errno to the current value
		986	of errno (just like calling C<errno> without an error number). By default,
		987	no argument will be passed and errno is zero.
		988
		989	=item $grp->errno ([$errno])
		990
		991	Sets the group errno value to C<$errno>, or the current value of errno
		992	when the argument is missing.
		993
		994	Every aio request has an associated errno value that is restored when
		995	the callback is invoked. This method lets you change this value from its
		996	default (0).
		997
		998	Calling C<result> will also set errno, so make sure you either set C<$!>
		999	before the call to C<result>, or call c<errno> after it.
672		1000
673	=item feed $grp $callback->($grp)	1001	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		1002
677	Sets a feeder/generator on this group: every group can have an attached	1003	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,	1004	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,	1005	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	1006	this might starve other requests for a potentially long time. For
681	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	1007	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
682	requests, delaying any later requests for a long time.	1008	requests, delaying any later requests for a long time.
683		1009
684	To avoid this, and allow incremental generation of requests, you can	1010	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	1011	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>,	1012	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	1013	below) requests active in the group itself and is expected to queue more
688	requests.	1014	requests.
689		1015
690	The feed can queue as many requests as it likes (i.e. C<add> does not	1016	The feed callback can queue as many requests as it likes (i.e. C<add> does
691	impose any limits).	1017	not impose any limits).
692		1018
693	If the feed does not queue more requests when called, it will be	1019	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	1020	automatically removed from the group.
695		1021
696	If the feed limit is C<0>, it will be set to C<2> automatically.	1022	If the feed limit is C<0>, it will be set to C<2> automatically.
…		…
698	Example:	1024	Example:
699		1025
700	# stat all files in @files, but only ever use four aio requests concurrently:	1026	# stat all files in @files, but only ever use four aio requests concurrently:
701		1027
702	my $grp = aio_group sub { print "finished\n" };	1028	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	1029	limit $grp 4;
704	feed $grp sub {	1030	feed $grp sub {
705	my $file = pop @files	1031	my $file = pop @files
706	or return;	1032	or return;
707		1033
708	add $grp aio_stat $file, sub { ... };	1034	add $grp aio_stat $file, sub { ... };
709	};	1035	};
710		1036
711	=item feed_limit $grp $num	1037	=item limit $grp $num
712		1038
713	Sets the feeder limit for the group: The feeder will be called whenever	1039	Sets the feeder limit for the group: The feeder will be called whenever
714	the group contains less than this many requests.	1040	the group contains less than this many requests.
715		1041
716	Setting the limit to C<0> will pause the feeding process.	1042	Setting the limit to C<0> will pause the feeding process.
717		1043
718	=back	1044	=back
719		1045
720	=head2 SUPPORT FUNCTIONS	1046	=head2 SUPPORT FUNCTIONS
		1047
		1048	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
721		1049
722	=over 4	1050	=over 4
723		1051
724	=item $fileno = IO::AIO::poll_fileno	1052	=item $fileno = IO::AIO::poll_fileno
725		1053
…		…
730		1058
731	See C<poll_cb> for an example.	1059	See C<poll_cb> for an example.
732		1060
733	=item IO::AIO::poll_cb	1061	=item IO::AIO::poll_cb
734		1062
735	Process all outstanding events on the result pipe. You have to call this	1063	Process some outstanding events on the result pipe. You have to call this
736	regularly. Returns the number of events processed. Returns immediately	1064	regularly. Returns the number of events processed. Returns immediately
737	when no events are outstanding.	1065	when no events are outstanding. The amount of events processed depends on
		1066	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1067
		1068	If not all requests were processed for whatever reason, the filehandle
		1069	will still be ready when C<poll_cb> returns.
738		1070
739	Example: Install an Event watcher that automatically calls	1071	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	1072	IO::AIO::poll_cb with high priority:
741		1073
742	Event->io (fd => IO::AIO::poll_fileno,	1074	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	1075	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	1076	cb => \&IO::AIO::poll_cb);
745		1077
		1078	=item IO::AIO::max_poll_reqs $nreqs
		1079
		1080	=item IO::AIO::max_poll_time $seconds
		1081
		1082	These set the maximum number of requests (default C<0>, meaning infinity)
		1083	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1084	the maximum amount of time (default C<0>, meaning infinity) spent in
		1085	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1086	of time C<poll_cb> is allowed to use).
		1087
		1088	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1089	syscall per request processed, which is not normally a problem unless your
		1090	callbacks are really really fast or your OS is really really slow (I am
		1091	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1092
		1093	Setting these is useful if you want to ensure some level of
		1094	interactiveness when perl is not fast enough to process all requests in
		1095	time.
		1096
		1097	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1098
		1099	Example: Install an Event watcher that automatically calls
		1100	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1101	program get the CPU sometimes even under high AIO load.
		1102
		1103	# try not to spend much more than 0.1s in poll_cb
		1104	IO::AIO::max_poll_time 0.1;
		1105
		1106	# use a low priority so other tasks have priority
		1107	Event->io (fd => IO::AIO::poll_fileno,
		1108	poll => 'r', nice => 1,
		1109	cb => &IO::AIO::poll_cb);
		1110
746	=item IO::AIO::poll_wait	1111	=item IO::AIO::poll_wait
747		1112
		1113	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	1114	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	1115	does a C<select> on the filehandle. This is useful if you want to
750	for some requests to finish).	1116	synchronously wait for some requests to finish).
751		1117
752	See C<nreqs> for an example.	1118	See C<nreqs> for an example.
753		1119
		1120	=item IO::AIO::poll
		1121
		1122	Waits until some requests have been handled.
		1123
		1124	Returns the number of requests processed, but is otherwise strictly
		1125	equivalent to:
		1126
		1127	IO::AIO::poll_wait, IO::AIO::poll_cb
		1128
754	=item IO::AIO::nreqs	1129	=item IO::AIO::flush
755		1130
756	Returns the number of requests currently outstanding (i.e. for which their	1131	Wait till all outstanding AIO requests have been handled.
757	callback has not been invoked yet).
758		1132
759	Example: wait till there are no outstanding requests anymore:	1133	Strictly equivalent to:
760		1134
761	IO::AIO::poll_wait, IO::AIO::poll_cb	1135	IO::AIO::poll_wait, IO::AIO::poll_cb
762	while IO::AIO::nreqs;	1136	while IO::AIO::nreqs;
763		1137
764	=item IO::AIO::flush	1138	=back
765		1139
766	Wait till all outstanding AIO requests have been handled.	1140	=head3 CONTROLLING THE NUMBER OF THREADS
767		1141
768	Strictly equivalent to:	1142	=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		1143
782	=item IO::AIO::min_parallel $nthreads	1144	=item IO::AIO::min_parallel $nthreads
783		1145
784	Set the minimum number of AIO threads to C<$nthreads>. The current	1146	Set the minimum number of AIO threads to C<$nthreads>. The current
785	default is C<8>, which means eight asynchronous operations can execute	1147	default is C<8>, which means eight asynchronous operations can execute
786	concurrently at any one time (the number of outstanding requests,	1148	concurrently at any one time (the number of outstanding requests,
787	however, is unlimited).	1149	however, is unlimited).
788		1150
789	IO::AIO starts threads only on demand, when an AIO request is queued and	1151	IO::AIO starts threads only on demand, when an AIO request is queued and
790	no free thread exists.	1152	no free thread exists. Please note that queueing up a hundred requests can
		1153	create demand for a hundred threads, even if it turns out that everything
		1154	is in the cache and could have been processed faster by a single thread.
791		1155
792	It is recommended to keep the number of threads relatively low, as some	1156	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	1157	Linux kernel versions will scale negatively with the number of threads
794	(higher parallelity => MUCH higher latency). With current Linux 2.6	1158	(higher parallelity => MUCH higher latency). With current Linux 2.6
795	versions, 4-32 threads should be fine.	1159	versions, 4-32 threads should be fine.
…		…
809	This module automatically runs C<max_parallel 0> at program end, to ensure	1173	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.	1174	that all threads are killed and that there are no outstanding requests.
811		1175
812	Under normal circumstances you don't need to call this function.	1176	Under normal circumstances you don't need to call this function.
813		1177
		1178	=item IO::AIO::max_idle $nthreads
		1179
		1180	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1181	threads that did not get a request to process within 10 seconds). That
		1182	means if a thread becomes idle while C<$nthreads> other threads are also
		1183	idle, it will free its resources and exit.
		1184
		1185	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1186	to allow for extremely high load situations, but want to free resources
		1187	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1188
		1189	The default is probably ok in most situations, especially if thread
		1190	creation is fast. If thread creation is very slow on your system you might
		1191	want to use larger values.
		1192
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1193	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
815		1194
816	[DEPRECATED]	1195	This is a very bad function to use in interactive programs because it
		1196	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1197	use an C<aio_group> together with a feed callback.
817		1198
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1199	Sets the maximum number of outstanding requests to C<$nreqs>. If you
819	try to queue up more than this number of requests, the caller will block until	1200	to queue up more than this number of requests, the next call to the
820	some requests have been handled.	1201	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1202	function will block until the limit is no longer exceeded.
821		1203
822	The default is very large, so normally there is no practical limit. If you	1204	The default value is very large, so there is no practical limit on the
823	queue up many requests in a loop it often improves speed if you set	1205	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		1206
826	This function does not work well together with C<aio_group>'s, and their	1207	You can still queue as many requests as you want. Therefore,
827	feeder interface is better suited to limiting concurrency, so do not use	1208	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
828	this function.	1209	as a stop gap to shield against fatal memory overflow (with large values).
829		1210
830	Under normal circumstances you don't need to call this function.	1211	=back
		1212
		1213	=head3 STATISTICAL INFORMATION
		1214
		1215	=over
		1216
		1217	=item IO::AIO::nreqs
		1218
		1219	Returns the number of requests currently in the ready, execute or pending
		1220	states (i.e. for which their callback has not been invoked yet).
		1221
		1222	Example: wait till there are no outstanding requests anymore:
		1223
		1224	IO::AIO::poll_wait, IO::AIO::poll_cb
		1225	while IO::AIO::nreqs;
		1226
		1227	=item IO::AIO::nready
		1228
		1229	Returns the number of requests currently in the ready state (not yet
		1230	executed).
		1231
		1232	=item IO::AIO::npending
		1233
		1234	Returns the number of requests currently in the pending state (executed,
		1235	but not yet processed by poll_cb).
831		1236
832	=back	1237	=back
833		1238
834	=cut	1239	=cut
835		1240
…		…
849	*$sym	1254	*$sym
850	}	1255	}
851		1256
852	min_parallel 8;	1257	min_parallel 8;
853		1258
854	END {	1259	END { flush }
855	max_parallel 0;
856	}
857		1260
858	1;	1261	1;
859		1262
860	=head2 FORK BEHAVIOUR	1263	=head2 FORK BEHAVIOUR
861		1264
862	This module should do "the right thing" when the process using it forks:	1265	This module should do "the right thing" when the process using it forks:
863		1266
864	Before the fork, IO::AIO enters a quiescent state where no requests	1267	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	1268	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	1269	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	1270	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	1271	(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	1272	parent). Threads will be started on demand until the limit set in the
870	parent process has been reached again.	1273	parent process has been reached again.
871		1274
872	In short: the parent will, after a short pause, continue as if fork had	1275	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	1276	not been called, while the child will act as if IO::AIO has not been used
874	yet.	1277	yet.
875		1278
876	=head2 MEMORY USAGE	1279	=head2 MEMORY USAGE
877		1280
		1281	Per-request usage:
		1282
878	Each aio request uses - depending on your architecture - around 128 bytes	1283	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	1284	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	1285	a few hundred bytes), readdir requires a result buffer and so on. Perl
881	also be locked.	1286	scalars and other data passed into aio requests will also be locked and
		1287	will consume memory till the request has entered the done state.
882		1288
883	This is now awfully much, so queuing lots of requests is not usually a	1289	This is now awfully much, so queuing lots of requests is not usually a
884	problem.	1290	problem.
885		1291
886	Each thread needs a stack area which is usually around 16k, sometimes much	1292	Per-thread usage:
887	larger, depending on the OS.	1293
		1294	In the execution phase, some aio requests require more memory for
		1295	temporary buffers, and each thread requires a stack and other data
		1296	structures (usually around 16k-128k, depending on the OS).
		1297
		1298	=head1 KNOWN BUGS
		1299
		1300	Known bugs will be fixed in the next release.
888		1301
889	=head1 SEE ALSO	1302	=head1 SEE ALSO
890		1303
891	L<Coro>, L<Linux::AIO> (obsolete).	1304	L<Coro::AIO>.
892		1305
893	=head1 AUTHOR	1306	=head1 AUTHOR
894		1307
895	Marc Lehmann <schmorp@schmorp.de>	1308	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1309	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 1.108 by root, Fri Jun 1 13:25:50 2007 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 1.108 by root, Fri Jun 1 13:25:50 2007 UTC