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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.56 by root, Sun Oct 22 00:53:47 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 your libc or	74	requests and signal their completion. You don't need thread support
57	perl, and the threads created by this module will not be visible to the	75	in perl, and the threads created by this module will not be visible
58	pthreads library. In the future, this module might make use of the native	76	to perl. In the future, this module might make use of the native aio
59	aio functions available on many operating systems. However, they are often	77	functions available on many operating systems. However, they are often
60	not well-supported (Linux doesn't allow them on normal files currently,	78	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	for example), and they would only support aio_read and aio_write, so the	79	files currently, for example), and they would only support aio_read and
62	remaining 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 @EXPORT = 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);	199	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	200	aio_chown aio_chmod aio_utime);
		201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
		202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		203	min_parallel max_parallel max_idle
		204	nreqs nready npending nthreads
		205	max_poll_time max_poll_reqs);
86		206
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		208
89	require XSLoader;	209	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
91	}	211	}
92		212
93	=head1 FUNCTIONS	213	=head1 FUNCTIONS
94		214
95	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
96		216
97	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
98	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
99	and they all accept an additional (and optional) C<$callback> argument	219	and they all accept an additional (and optional) C<$callback> argument
100	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
…		…
103	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
104		224
105	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
106	internally until the request has finished.	226	internally until the request has finished.
107		227
108	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
109	manipulation of those requests while they are in-flight.	229	further manipulation of those requests while they are in-flight.
110		230
111	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
112	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
113	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
114	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
115	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
116		237
117	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
118	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
119	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
120	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
121	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)
122	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.
123		247
124	=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
125		282
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	283	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		284
128	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
129	created filehandle for the file.	286	created filehandle for the file.
…		…
135	list. They are the same as used by C<sysopen>.	292	list. They are the same as used by C<sysopen>.
136		293
137	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
138	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>,
139	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,
140	and C<0666> or C<0777> if you do).	297	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		298	by the umask in effect then the request is being executed, so better never
		299	change the umask.
141		300
142	Example:	301	Example:
143		302
144	aio_open "/etc/passwd", O_RDONLY, 0, sub {	303	aio_open "/etc/passwd", O_RDONLY, 0, sub {
145	if ($_[0]) {	304	if ($_[0]) {
…		…
148	} else {	307	} else {
149	die "open failed: $!\n";	308	die "open failed: $!\n";
150	}	309	}
151	};	310	};
152		311
		312
153	=item aio_close $fh, $callback->($status)	313	=item aio_close $fh, $callback->($status)
154		314
155	Asynchronously close a file and call the callback with the result	315	Asynchronously close a file and call the callback with the result
156	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
157	filehandle here, as perl will likely close the file descriptor another	317	filehandle here, as perl will likely close the file descriptor another
…		…
159	C<close> or just let filehandles go out of scope.	319	C<close> or just let filehandles go out of scope.
160		320
161	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
162	therefore best to avoid this function.	322	therefore best to avoid this function.
163		323
		324
164	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	325	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
165		326
166	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	327	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
167		328
168	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>
169	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
170	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
171	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.
172		335
173	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
174	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
175	necessary/optional hardware is installed).	338	the necessary/optional hardware is installed).
176		339
177	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
178	offset C<0> within the scalar:	341	offset C<0> within the scalar:
179		342
180	aio_read $fh, 7, 15, $buffer, 0, sub {	343	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	344	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	345	print "read $_[0] bytes: <$buffer>\n";
183	};	346	};
184		347
185	=item aio_move $srcpath, $dstpath, $callback->($status)
186
187	Try to move the I<file> (directories not supported as either source or
188	destination) from C<$srcpath> to C<$dstpath> and call the callback with
189	the C<0> (error) or C<-1> ok.
190
191	This is a composite request that tries to rename(2) the file first. If
192	rename files with C<EXDEV>, it creates the destination file with mode 0200
193	and copies the contents of the source file into it using C<aio_sendfile>,
194	followed by restoring atime, mtime, access mode and uid/gid, in that
195	order, and unlinking the C<$srcpath>.
196
197	If an error occurs, the partial destination file will be unlinked, if
198	possible, except when setting atime, mtime, access mode and uid/gid, where
199	errors are being ignored.
200
201	=cut
202
203	sub aio_move($$$) {
204	my ($src, $dst, $cb) = @_;
205
206	my $grp = aio_group;
207
208	add $grp aio_rename $src, $dst, sub {
209	if ($_[0] && $! == EXDEV) {
210	add $grp aio_open $src, O_RDONLY, 0, sub {
211	if (my $src_fh = $_[0]) {
212	my @stat = stat $src_fh;
213
214	add $grp aio_open $dst, O_WRONLY, 0200, sub {
215	if (my $dst_fh = $_[0]) {
216	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
217	close $src_fh;
218
219	if ($_[0] == $stat[7]) {
220	utime $stat[8], $stat[9], $dst;
221	chmod $stat[2] & 07777, $dst_fh;
222	chown $stat[4], $stat[5], $dst_fh;
223	close $dst_fh;
224
225	add $grp aio_unlink $src, sub {
226	$cb->($_[0]);
227	};
228	} else {
229	my $errno = $!;
230	add $grp aio_unlink $dst, sub {
231	$! = $errno;
232	$cb->(-1);
233	};
234	}
235	};
236	} else {
237	$cb->(-1);
238	}
239	},
240
241	} else {
242	$cb->(-1);
243	}
244	};
245	} else {
246	$cb->($_[0]);
247	}
248	};
249
250	$grp
251	}
252		348
253	=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)
254		350
255	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
256	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
…		…
270	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
271	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
272	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
273	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
274	read.	370	read.
		371
275		372
276	=item aio_readahead $fh,$offset,$length, $callback->($retval)	373	=item aio_readahead $fh,$offset,$length, $callback->($retval)
277		374
278	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
279	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>
…		…
285	file. The current file offset of the file is left unchanged.	382	file. The current file offset of the file is left unchanged.
286		383
287	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
288	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.
289		386
		387
290	=item aio_stat $fh_or_path, $callback->($status)	388	=item aio_stat $fh_or_path, $callback->($status)
291		389
292	=item aio_lstat $fh, $callback->($status)	390	=item aio_lstat $fh, $callback->($status)
293		391
294	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
…		…
307	aio_stat "/etc/passwd", sub {	405	aio_stat "/etc/passwd", sub {
308	$_[0] and die "stat failed: $!";	406	$_[0] and die "stat failed: $!";
309	print "size is ", -s _, "\n";	407	print "size is ", -s _, "\n";
310	};	408	};
311		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
312	=item aio_unlink $pathname, $callback->($status)	447	=item aio_unlink $pathname, $callback->($status)
313		448
314	Asynchronously unlink (delete) a file and call the callback with the	449	Asynchronously unlink (delete) a file and call the callback with the
315	result code.	450	result code.
316		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
317	=item aio_link $srcpath, $dstpath, $callback->($status)	464	=item aio_link $srcpath, $dstpath, $callback->($status)
318		465
319	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
320	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.
321		468
		469
322	=item aio_symlink $srcpath, $dstpath, $callback->($status)	470	=item aio_symlink $srcpath, $dstpath, $callback->($status)
323		471
324	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
325	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.
326		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
327	=item aio_rename $srcpath, $dstpath, $callback->($status)	483	=item aio_rename $srcpath, $dstpath, $callback->($status)
328		484
329	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
330	rename(2) and call the callback with the result code.	486	rename(2) and call the callback with the result code.
331		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
332	=item aio_rmdir $pathname, $callback->($status)	496	=item aio_rmdir $pathname, $callback->($status)
333		497
334	Asynchronously rmdir (delete) a directory and call the callback with the	498	Asynchronously rmdir (delete) a directory and call the callback with the
335	result code.	499	result code.
		500
336		501
337	=item aio_readdir $pathname, $callback->($entries)	502	=item aio_readdir $pathname, $callback->($entries)
338		503
339	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
340	directory (i.e. opendir + readdir + closedir). The entries will not be	505	directory (i.e. opendir + readdir + closedir). The entries will not be
341	sorted, and will B<NOT> include the C<.> and C<..> entries.	506	sorted, and will B<NOT> include the C<.> and C<..> entries.
342		507
343	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
344	with the filenames.	509	with the filenames.
345		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
346	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	648	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
347		649
348	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
349	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
350	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
351	recurse into (everything else).	653	recurse into (everything else, including symlinks to directories).
352		654
353	C<aio_scandir> is a composite request that consists of many sub	655	C<aio_scandir> is a composite request that creates of many sub requests_
354	requests. C<$maxreq> specifies the maximum number of outstanding aio	656	C<$maxreq> specifies the maximum number of outstanding aio requests that
355	requests that this function generates. If it is C<< <= 0 >>, then a	657	this function generates. If it is C<< <= 0 >>, then a suitable default
356	suitable default will be chosen (currently 8).	658	will be chosen (currently 4).
357		659
358	On error, the callback is called without arguments, otherwise it receives	660	On error, the callback is called without arguments, otherwise it receives
359	two array-refs with path-relative entry names.	661	two array-refs with path-relative entry names.
360		662
361	Example:	663	Example:
…		…
395	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
396	directory counting heuristic.	698	directory counting heuristic.
397		699
398	=cut	700	=cut
399		701
400	sub aio_scandir($$$) {	702	sub aio_scandir($$;$) {
		703	aio_block {
401	my ($path, $maxreq, $cb) = @_;	704	my ($path, $maxreq, $cb) = @_;
402		705
		706	my $pri = aioreq_pri;
		707
403	my $grp = aio_group;	708	my $grp = aio_group $cb;
404		709
405	$maxreq = 8 if $maxreq <= 0;	710	$maxreq = 4 if $maxreq <= 0;
406		711
407	# stat once	712	# stat once
		713	aioreq_pri $pri;
408	add $grp aio_stat $path, sub {	714	add $grp aio_stat $path, sub {
409	return $cb->() if $_[0];	715	return $grp->result () if $_[0];
410	my $now = time;	716	my $now = time;
411	my $hash1 = join ":", (stat _)[0,1,3,7,9];	717	my $hash1 = join ":", (stat _)[0,1,3,7,9];
412		718
413	# read the directory entries	719	# read the directory entries
		720	aioreq_pri $pri;
414	add $grp aio_readdir $path, sub {	721	add $grp aio_readdir $path, sub {
415	my $entries = shift	722	my $entries = shift
416	or return $cb->();	723	or return $grp->result ();
417		724
418	# stat the dir another time	725	# stat the dir another time
		726	aioreq_pri $pri;
419	add $grp aio_stat $path, sub {	727	add $grp aio_stat $path, sub {
420	my $hash2 = join ":", (stat _)[0,1,3,7,9];	728	my $hash2 = join ":", (stat _)[0,1,3,7,9];
421		729
422	my $ndirs;	730	my $ndirs;
423		731
424	# take the slow route if anything looks fishy	732	# take the slow route if anything looks fishy
425	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	733	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
426	$ndirs = -1;	734	$ndirs = -1;
427	} else {	735	} else {
428	# if nlink == 2, we are finished	736	# if nlink == 2, we are finished
429	# on non-posix-fs's, we rely on nlink < 2	737	# on non-posix-fs's, we rely on nlink < 2
430	$ndirs = (stat _)[3] - 2	738	$ndirs = (stat _)[3] - 2
431	or return $cb->([], $entries);	739	or return $grp->result ([], $entries);
432	}
433
434	# sort into likely dirs and likely nondirs
435	# dirs == files without ".", short entries first
436	$entries = [map $_->[0],
437	sort { $b->[1] cmp $a->[1] }
438	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
439	@$entries];
440
441	my (@dirs, @nondirs);
442
443	my ($statcb, $schedcb);
444	my $nreq = 0;
445
446	$schedcb = sub {
447	if (@$entries) {
448	if ($nreq < $maxreq) {
449	my $ent = pop @$entries;
450	$nreq++;
451	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
452	}
453	} elsif (!$nreq) {
454	# finished
455	undef $statcb;
456	undef $schedcb;
457	$cb->(\@dirs, \@nondirs) if $cb;
458	undef $cb;
459	}	740	}
		741
		742	# sort into likely dirs and likely nondirs
		743	# dirs == files without ".", short entries first
		744	$entries = [map $_->[0],
		745	sort { $b->[1] cmp $a->[1] }
		746	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		747	@$entries];
		748
		749	my (@dirs, @nondirs);
		750
		751	my $statgrp = add $grp aio_group sub {
		752	$grp->result (\@dirs, \@nondirs);
		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	};
460	};	782	};
461	$statcb = sub {
462	my ($status, $entry) = @_;
463
464	if ($status < 0) {
465	$nreq--;
466	push @nondirs, $entry;
467	&$schedcb;
468	} else {
469	# need to check for real directory
470	add $grp aio_lstat "$path/$entry", sub {
471	$nreq--;
472
473	if (-d _) {
474	push @dirs, $entry;
475
476	if (!--$ndirs) {
477	push @nondirs, @$entries;
478	$entries = [];
479	}
480	} else {
481	push @nondirs, $entry;
482	}
483
484	&$schedcb;
485	}
486	}
487	};
488
489	&$schedcb while @$entries && $nreq < $maxreq;
490	};	783	};
491	};	784	};
		785
		786	$grp
492	};	787	}
		788	}
493		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
494	$grp	823	$grp
		824	}
495	}	825	}
496		826
497	=item aio_fsync $fh, $callback->($status)	827	=item aio_fsync $fh, $callback->($status)
498		828
499	Asynchronously call fsync on the given filehandle and call the callback	829	Asynchronously call fsync on the given filehandle and call the callback
…		…
505	callback with the fdatasync result code.	835	callback with the fdatasync result code.
506		836
507	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
508	detected, it will be emulated by calling C<fsync> instead.	838	detected, it will be emulated by calling C<fsync> instead.
509		839
510	=item aio_group $callback->()	840	=item aio_group $callback->(...)
511
512	[EXPERIMENTAL]
513		841
514	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
515	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
516	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.
517		846
518	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
519	for more info.	848	for more info.
520		849
521	Example:	850	Example:
…		…
527	add $grp	856	add $grp
528	(aio_stat ...),	857	(aio_stat ...),
529	(aio_stat ...),	858	(aio_stat ...),
530	...;	859	...;
531		860
		861	=item aio_nop $callback->()
		862
		863	This is a special request - it does nothing in itself and is only used for
		864	side effects, such as when you want to add a dummy request to a group so
		865	that finishing the requests in the group depends on executing the given
		866	code.
		867
		868	While this request does nothing, it still goes through the execution
		869	phase and still requires a worker thread. Thus, the callback will not
		870	be executed immediately but only after other requests in the queue have
		871	entered their execution phase. This can be used to measure request
		872	latency.
		873
532	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	874	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
533		875
534	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
535	the request workers to sleep for the given time.	877	the request workers to sleep for the given time.
536		878
537	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
538	like sleep and file handle readable/writable, the overhead this creates	880	like sleep and file handle readable/writable, the overhead this creates is
539	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
540	under artificial I/O pressure.	882	except to put your application under artificial I/O pressure.
541		883
542	=back	884	=back
543		885
544	=head2 IO::AIO::REQ CLASS	886	=head2 IO::AIO::REQ CLASS
545		887
546	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
547	called in non-void context.	889	called in non-void context.
548		890
549	A request always moves through the following five states in its lifetime,
550	in order: B<ready> (request has been created, but has not been executed
551	yet), B<execute> (request is currently being executed), B<pending>
552	(request has been executed but callback has not been called yet),
553	B<result> (results are being processed synchronously, includes calling the
554	callback) and B<done> (request has reached the end of its lifetime and
555	holds no resources anymore).
556
557	=over 4	891	=over 4
558		892
559	=item $req->cancel	893	=item cancel $req
560		894
561	Cancels the request, if possible. Has the effect of skipping execution	895	Cancels the request, if possible. Has the effect of skipping execution
562	when entering the B<execute> state and skipping calling the callback when	896	when entering the B<execute> state and skipping calling the callback when
563	entering the the B<result> state, but will leave the request otherwise	897	entering the the B<result> state, but will leave the request otherwise
564	untouched. That means that requests that currently execute will not be	898	untouched. That means that requests that currently execute will not be
565	stopped and resources held by the request will not be freed prematurely.	899	stopped and resources held by the request will not be freed prematurely.
566		900
		901	=item cb $req $callback->(...)
		902
		903	Replace (or simply set) the callback registered to the request.
		904
567	=back	905	=back
568		906
569	=head2 IO::AIO::GRP CLASS	907	=head2 IO::AIO::GRP CLASS
570		908
571	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	909	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
585	You add requests by calling the C<add> method with one or more	923	You add requests by calling the C<add> method with one or more
586	C<IO::AIO::REQ> objects:	924	C<IO::AIO::REQ> objects:
587		925
588	$grp->add (aio_unlink "...");	926	$grp->add (aio_unlink "...");
589		927
590	add $grp aio_stat "...", sub { ... };	928	add $grp aio_stat "...", sub {
		929	$_[0] or return $grp->result ("error");
		930
		931	# add another request dynamically, if first succeeded
		932	add $grp aio_open "...", sub {
		933	$grp->result ("ok");
		934	};
		935	};
591		936
592	This makes it very easy to create composite requests (see the source of	937	This makes it very easy to create composite requests (see the source of
593	C<aio_move> for an application) that work and feel like simple requests.	938	C<aio_move> for an application) that work and feel like simple requests.
594		939
		940	=over 4
		941
595	The IO::AIO::GRP objects will be cleaned up during calls to	942	=item * The IO::AIO::GRP objects will be cleaned up during calls to
596	C<IO::AIO::poll_cb>, just like any other request.	943	C<IO::AIO::poll_cb>, just like any other request.
597		944
598	They can be canceled like any other request. Canceling will cancel not	945	=item * They can be canceled like any other request. Canceling will cancel not
599	just the request itself, but also all requests it contains.	946	only the request itself, but also all requests it contains.
600		947
601	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.
		949
		950	=item * You must not add requests to a group from within the group callback (or
		951	any later time).
		952
		953	=back
602		954
603	Their lifetime, simplified, looks like this: when they are empty, they	955	Their lifetime, simplified, looks like this: when they are empty, they
604	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
605	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
606	exist.	958	exist.
607		959
		960	That means after creating a group you have some time to add requests. And
		961	in the callbacks of those requests, you can add further requests to the
		962	group. And only when all those requests have finished will the the group
		963	itself finish.
		964
608	=over 4	965	=over 4
609		966
		967	=item add $grp ...
		968
610	=item $grp->add (...)	969	=item $grp->add (...)
611		970
612	=item add $grp ...	971	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		972	be added, including other groups, as long as you do not create circular
		973	dependencies.
613		974
614	Add one or more	975	Returns all its arguments.
615	Cancels the request, if possible. Has the effect of skipping execution	976
616	when entering the B<execute> state and skipping calling the callback when	977	=item $grp->cancel_subs
617	entering the the B<result> state, but will leave the request otherwise	978
618	untouched. That means that requests that currently execute will not be	979	Cancel all subrequests and clears any feeder, but not the group request
619	stopped and resources held by the request will not be freed prematurely.	980	itself. Useful when you queued a lot of events but got a result early.
		981
		982	=item $grp->result (...)
		983
		984	Set the result value(s) that will be passed to the group callback when all
		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.
		1000
		1001	=item feed $grp $callback->($grp)
		1002
		1003	Sets a feeder/generator on this group: every group can have an attached
		1004	generator that generates requests if idle. The idea behind this is that,
		1005	although you could just queue as many requests as you want in a group,
		1006	this might starve other requests for a potentially long time. For
		1007	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		1008	requests, delaying any later requests for a long time.
		1009
		1010	To avoid this, and allow incremental generation of requests, you can
		1011	instead a group and set a feeder on it that generates those requests. The
		1012	feed callback will be called whenever there are few enough (see C<limit>,
		1013	below) requests active in the group itself and is expected to queue more
		1014	requests.
		1015
		1016	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1017	not impose any limits).
		1018
		1019	If the feed does not queue more requests when called, it will be
		1020	automatically removed from the group.
		1021
		1022	If the feed limit is C<0>, it will be set to C<2> automatically.
		1023
		1024	Example:
		1025
		1026	# stat all files in @files, but only ever use four aio requests concurrently:
		1027
		1028	my $grp = aio_group sub { print "finished\n" };
		1029	limit $grp 4;
		1030	feed $grp sub {
		1031	my $file = pop @files
		1032	or return;
		1033
		1034	add $grp aio_stat $file, sub { ... };
		1035	};
		1036
		1037	=item limit $grp $num
		1038
		1039	Sets the feeder limit for the group: The feeder will be called whenever
		1040	the group contains less than this many requests.
		1041
		1042	Setting the limit to C<0> will pause the feeding process.
620		1043
621	=back	1044	=back
622		1045
623	=head2 SUPPORT FUNCTIONS	1046	=head2 SUPPORT FUNCTIONS
		1047
		1048	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
624		1049
625	=over 4	1050	=over 4
626		1051
627	=item $fileno = IO::AIO::poll_fileno	1052	=item $fileno = IO::AIO::poll_fileno
628		1053
…		…
633		1058
634	See C<poll_cb> for an example.	1059	See C<poll_cb> for an example.
635		1060
636	=item IO::AIO::poll_cb	1061	=item IO::AIO::poll_cb
637		1062
638	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
639	regularly. Returns the number of events processed. Returns immediately	1064	regularly. Returns the number of events processed. Returns immediately
640	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.
641		1070
642	Example: Install an Event watcher that automatically calls	1071	Example: Install an Event watcher that automatically calls
643	IO::AIO::poll_cb with high priority:	1072	IO::AIO::poll_cb with high priority:
644		1073
645	Event->io (fd => IO::AIO::poll_fileno,	1074	Event->io (fd => IO::AIO::poll_fileno,
646	poll => 'r', async => 1,	1075	poll => 'r', async => 1,
647	cb => \&IO::AIO::poll_cb);	1076	cb => \&IO::AIO::poll_cb);
648		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
649	=item IO::AIO::poll_wait	1111	=item IO::AIO::poll_wait
650		1112
		1113	If there are any outstanding requests and none of them in the result
651	Wait till the result filehandle becomes ready for reading (simply does a	1114	phase, wait till the result filehandle becomes ready for reading (simply
652	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
653	for some requests to finish).	1116	synchronously wait for some requests to finish).
654		1117
655	See C<nreqs> for an example.	1118	See C<nreqs> for an example.
656		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
657	=item IO::AIO::nreqs	1129	=item IO::AIO::flush
658		1130
659	Returns the number of requests currently outstanding (i.e. for which their	1131	Wait till all outstanding AIO requests have been handled.
660	callback has not been invoked yet).
661		1132
662	Example: wait till there are no outstanding requests anymore:	1133	Strictly equivalent to:
663		1134
664	IO::AIO::poll_wait, IO::AIO::poll_cb	1135	IO::AIO::poll_wait, IO::AIO::poll_cb
665	while IO::AIO::nreqs;	1136	while IO::AIO::nreqs;
666		1137
667	=item IO::AIO::flush	1138	=back
668		1139
669	Wait till all outstanding AIO requests have been handled.	1140	=head3 CONTROLLING THE NUMBER OF THREADS
670		1141
671	Strictly equivalent to:	1142	=over
672
673	IO::AIO::poll_wait, IO::AIO::poll_cb
674	while IO::AIO::nreqs;
675
676	=item IO::AIO::poll
677
678	Waits until some requests have been handled.
679
680	Strictly equivalent to:
681
682	IO::AIO::poll_wait, IO::AIO::poll_cb
683	if IO::AIO::nreqs;
684		1143
685	=item IO::AIO::min_parallel $nthreads	1144	=item IO::AIO::min_parallel $nthreads
686		1145
687	Set the minimum number of AIO threads to C<$nthreads>. The current default	1146	Set the minimum number of AIO threads to C<$nthreads>. The current
688	is C<4>, which means four asynchronous operations can be done at one time	1147	default is C<8>, which means eight asynchronous operations can execute
689	(the number of outstanding operations, however, is unlimited).	1148	concurrently at any one time (the number of outstanding requests,
		1149	however, is unlimited).
690		1150
691	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
692	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.
693		1155
694	It is recommended to keep the number of threads low, as some Linux	1156	It is recommended to keep the number of threads relatively low, as some
695	kernel versions will scale negatively with the number of threads (higher	1157	Linux kernel versions will scale negatively with the number of threads
696	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1158	(higher parallelity => MUCH higher latency). With current Linux 2.6
697	threads should be fine.	1159	versions, 4-32 threads should be fine.
698		1160
699	Under most circumstances you don't need to call this function, as the	1161	Under most circumstances you don't need to call this function, as the
700	module selects a default that is suitable for low to moderate load.	1162	module selects a default that is suitable for low to moderate load.
701		1163
702	=item IO::AIO::max_parallel $nthreads	1164	=item IO::AIO::max_parallel $nthreads
…		…
711	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
712	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.
713		1175
714	Under normal circumstances you don't need to call this function.	1176	Under normal circumstances you don't need to call this function.
715		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
716	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1193	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1194
		1195	This is a very bad function to use in interactive programs because it
		1196	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1197	use an C<aio_group> together with a feed callback.
717		1198
718	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1199	Sets the maximum number of outstanding requests to C<$nreqs>. If you
719	try to queue up more than this number of requests, the caller will block until	1200	to queue up more than this number of requests, the next call to the
720	some requests have been handled.	1201	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1202	function will block until the limit is no longer exceeded.
721		1203
722	The default is very large, so normally there is no practical limit. If you	1204	The default value is very large, so there is no practical limit on the
723	queue up many requests in a loop it often improves speed if you set	1205	number of outstanding requests.
724	this to a relatively low number, such as C<100>.
725		1206
726	Under normal circumstances you don't need to call this function.	1207	You can still queue as many requests as you want. Therefore,
		1208	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1209	as a stop gap to shield against fatal memory overflow (with large values).
		1210
		1211	=back
		1212
		1213	=head3 STATISTICAL INFORMATION
		1214
		1215	=over
		1216
		1217	=item IO::AIO::nreqs
		1218
		1219	Returns the number of requests currently in the ready, execute or pending
		1220	states (i.e. for which their callback has not been invoked yet).
		1221
		1222	Example: wait till there are no outstanding requests anymore:
		1223
		1224	IO::AIO::poll_wait, IO::AIO::poll_cb
		1225	while IO::AIO::nreqs;
		1226
		1227	=item IO::AIO::nready
		1228
		1229	Returns the number of requests currently in the ready state (not yet
		1230	executed).
		1231
		1232	=item IO::AIO::npending
		1233
		1234	Returns the number of requests currently in the pending state (executed,
		1235	but not yet processed by poll_cb).
727		1236
728	=back	1237	=back
729		1238
730	=cut	1239	=cut
731		1240
…		…
743	or return undef;	1252	or return undef;
744		1253
745	*$sym	1254	*$sym
746	}	1255	}
747		1256
748	min_parallel 4;	1257	min_parallel 8;
749		1258
750	END {	1259	END { flush }
751	max_parallel 0;
752	}
753		1260
754	1;	1261	1;
755		1262
756	=head2 FORK BEHAVIOUR	1263	=head2 FORK BEHAVIOUR
757		1264
758	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:
759		1266
760	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
761	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
762	the fork the parent simply leaves the quiescent state and continues	1269	the fork the parent simply leaves the quiescent state and continues
763	request/result processing, while the child clears the request/result	1270	request/result processing, while the child frees the request/result queue
764	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
765	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
766	parent process has been reached again.	1273	parent process has been reached again.
767		1274
768	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
769	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
770	yet.	1277	yet.
771		1278
		1279	=head2 MEMORY USAGE
		1280
		1281	Per-request usage:
		1282
		1283	Each aio request uses - depending on your architecture - around 100-200
		1284	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1285	a few hundred bytes), readdir requires a result buffer and so on. Perl
		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.
		1288
		1289	This is now awfully much, so queuing lots of requests is not usually a
		1290	problem.
		1291
		1292	Per-thread usage:
		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.
		1301
772	=head1 SEE ALSO	1302	=head1 SEE ALSO
773		1303
774	L<Coro>, L<Linux::AIO> (obsolete).	1304	L<Coro::AIO>.
775		1305
776	=head1 AUTHOR	1306	=head1 AUTHOR
777		1307
778	Marc Lehmann <schmorp@schmorp.de>	1308	Marc Lehmann <schmorp@schmorp.de>
779	http://home.schmorp.de/	1309	http://home.schmorp.de/

Diff Legend

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

Comparing IO-AIO/AIO.pm (file contents): Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs. Revision 1.108 by root, Fri Jun 1 13:25:50 2007 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs.
Revision 1.108 by root, Fri Jun 1 13:25:50 2007 UTC