[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 1.110 by root, Sun Jul 8 09:09:34 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 aio_truncate);
		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<$dataoffset> and calls the
170	callback without the actual number of bytes read (or -1 on error, just	331	callback without the actual number of bytes read (or -1 on error, just
171	like the syscall).	332	like the syscall).
172		333
		334	If C<$offset> is undefined, then the current file offset will be used (and
		335	updated), otherwise the file offset will not be changed by these calls.
		336
		337	If C<$length> is undefined in C<aio_write>, use the remaining length of C<$data>.
		338
		339	If C<$dataoffset> is less than zero, it will be counted from the end of
		340	C<$data>.
		341
173	The C<$data> scalar I<MUST NOT> be modified in any way while the request	342	The C<$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	343	is outstanding. Modifying it can result in segfaults or World War III (if
175	necessary/optional hardware is installed).	344	the necessary/optional hardware is installed).
176		345
177	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at	346	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
178	offset C<0> within the scalar:	347	offset C<0> within the scalar:
179		348
180	aio_read $fh, 7, 15, $buffer, 0, sub {	349	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	350	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	351	print "read $_[0] bytes: <$buffer>\n";
183	};	352	};
184		353
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		354
253	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	355	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
254		356
255	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	357	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	358	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	372	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	373	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	374	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	375	value equals C<$length> one can assume that C<$length> bytes have been
274	read.	376	read.
		377
275		378
276	=item aio_readahead $fh,$offset,$length, $callback->($retval)	379	=item aio_readahead $fh,$offset,$length, $callback->($retval)
277		380
278	C<aio_readahead> populates the page cache with data from a file so that	381	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>	382	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.	388	file. The current file offset of the file is left unchanged.
286		389
287	If that syscall doesn't exist (likely if your OS isn't Linux) it will be	390	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.	391	emulated by simply reading the data, which would have a similar effect.
289		392
		393
290	=item aio_stat $fh_or_path, $callback->($status)	394	=item aio_stat $fh_or_path, $callback->($status)
291		395
292	=item aio_lstat $fh, $callback->($status)	396	=item aio_lstat $fh, $callback->($status)
293		397
294	Works like perl's C<stat> or C<lstat> in void context. The callback will	398	Works like perl's C<stat> or C<lstat> in void context. The callback will
…		…
307	aio_stat "/etc/passwd", sub {	411	aio_stat "/etc/passwd", sub {
308	$_[0] and die "stat failed: $!";	412	$_[0] and die "stat failed: $!";
309	print "size is ", -s _, "\n";	413	print "size is ", -s _, "\n";
310	};	414	};
311		415
		416
		417	=item aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		418
		419	Works like perl's C<utime> function (including the special case of $atime
		420	and $mtime being undef). Fractional times are supported if the underlying
		421	syscalls support them.
		422
		423	When called with a pathname, uses utimes(2) if available, otherwise
		424	utime(2). If called on a file descriptor, uses futimes(2) if available,
		425	otherwise returns ENOSYS, so this is not portable.
		426
		427	Examples:
		428
		429	# set atime and mtime to current time (basically touch(1)):
		430	aio_utime "path", undef, undef;
		431	# set atime to current time and mtime to beginning of the epoch:
		432	aio_utime "path", time, undef; # undef==0
		433
		434
		435	=item aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		436
		437	Works like perl's C<chown> function, except that C<undef> for either $uid
		438	or $gid is being interpreted as "do not change" (but -1 can also be used).
		439
		440	Examples:
		441
		442	# same as "chown root path" in the shell:
		443	aio_chown "path", 0, -1;
		444	# same as above:
		445	aio_chown "path", 0, undef;
		446
		447
		448	=item aio_truncate $fh_or_path, $offset, $callback->($status)
		449
		450	Works like truncate(2) or ftruncate(2).
		451
		452
		453	=item aio_chmod $fh_or_path, $mode, $callback->($status)
		454
		455	Works like perl's C<chmod> function.
		456
		457
312	=item aio_unlink $pathname, $callback->($status)	458	=item aio_unlink $pathname, $callback->($status)
313		459
314	Asynchronously unlink (delete) a file and call the callback with the	460	Asynchronously unlink (delete) a file and call the callback with the
315	result code.	461	result code.
316		462
		463
		464	=item aio_mknod $path, $mode, $dev, $callback->($status)
		465
		466	[EXPERIMENTAL]
		467
		468	Asynchronously create a device node (or fifo). See mknod(2).
		469
		470	The only (POSIX-) portable way of calling this function is:
		471
		472	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		473
		474
317	=item aio_link $srcpath, $dstpath, $callback->($status)	475	=item aio_link $srcpath, $dstpath, $callback->($status)
318		476
319	Asynchronously create a new link to the existing object at C<$srcpath> at	477	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.	478	the path C<$dstpath> and call the callback with the result code.
321		479
		480
322	=item aio_symlink $srcpath, $dstpath, $callback->($status)	481	=item aio_symlink $srcpath, $dstpath, $callback->($status)
323		482
324	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	483	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.	484	the path C<$dstpath> and call the callback with the result code.
326		485
		486
		487	=item aio_readlink $path, $callback->($link)
		488
		489	Asynchronously read the symlink specified by C<$path> and pass it to
		490	the callback. If an error occurs, nothing or undef gets passed to the
		491	callback.
		492
		493
327	=item aio_rename $srcpath, $dstpath, $callback->($status)	494	=item aio_rename $srcpath, $dstpath, $callback->($status)
328		495
329	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	496	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
330	rename(2) and call the callback with the result code.	497	rename(2) and call the callback with the result code.
331		498
		499
		500	=item aio_mkdir $pathname, $mode, $callback->($status)
		501
		502	Asynchronously mkdir (create) a directory and call the callback with
		503	the result code. C<$mode> will be modified by the umask at the time the
		504	request is executed, so do not change your umask.
		505
		506
332	=item aio_rmdir $pathname, $callback->($status)	507	=item aio_rmdir $pathname, $callback->($status)
333		508
334	Asynchronously rmdir (delete) a directory and call the callback with the	509	Asynchronously rmdir (delete) a directory and call the callback with the
335	result code.	510	result code.
		511
336		512
337	=item aio_readdir $pathname, $callback->($entries)	513	=item aio_readdir $pathname, $callback->($entries)
338		514
339	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	515	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	516	directory (i.e. opendir + readdir + closedir). The entries will not be
341	sorted, and will B<NOT> include the C<.> and C<..> entries.	517	sorted, and will B<NOT> include the C<.> and C<..> entries.
342		518
343	The callback a single argument which is either C<undef> or an array-ref	519	The callback a single argument which is either C<undef> or an array-ref
344	with the filenames.	520	with the filenames.
345		521
		522
		523	=item aio_load $path, $data, $callback->($status)
		524
		525	This is a composite request that tries to fully load the given file into
		526	memory. Status is the same as with aio_read.
		527
		528	=cut
		529
		530	sub aio_load($$;$) {
		531	aio_block {
		532	my ($path, undef, $cb) = @_;
		533	my $data = \$_[1];
		534
		535	my $pri = aioreq_pri;
		536	my $grp = aio_group $cb;
		537
		538	aioreq_pri $pri;
		539	add $grp aio_open $path, O_RDONLY, 0, sub {
		540	my $fh = shift
		541	or return $grp->result (-1);
		542
		543	aioreq_pri $pri;
		544	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		545	$grp->result ($_[0]);
		546	};
		547	};
		548
		549	$grp
		550	}
		551	}
		552
		553	=item aio_copy $srcpath, $dstpath, $callback->($status)
		554
		555	Try to copy the I<file> (directories not supported as either source or
		556	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		557	the C<0> (error) or C<-1> ok.
		558
		559	This is a composite request that it creates the destination file with
		560	mode 0200 and copies the contents of the source file into it using
		561	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		562	uid/gid, in that order.
		563
		564	If an error occurs, the partial destination file will be unlinked, if
		565	possible, except when setting atime, mtime, access mode and uid/gid, where
		566	errors are being ignored.
		567
		568	=cut
		569
		570	sub aio_copy($$;$) {
		571	aio_block {
		572	my ($src, $dst, $cb) = @_;
		573
		574	my $pri = aioreq_pri;
		575	my $grp = aio_group $cb;
		576
		577	aioreq_pri $pri;
		578	add $grp aio_open $src, O_RDONLY, 0, sub {
		579	if (my $src_fh = $_[0]) {
		580	my @stat = stat $src_fh;
		581
		582	aioreq_pri $pri;
		583	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		584	if (my $dst_fh = $_[0]) {
		585	aioreq_pri $pri;
		586	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		587	if ($_[0] == $stat[7]) {
		588	$grp->result (0);
		589	close $src_fh;
		590
		591	# those should not normally block. should. should.
		592	utime $stat[8], $stat[9], $dst;
		593	chmod $stat[2] & 07777, $dst_fh;
		594	chown $stat[4], $stat[5], $dst_fh;
		595	close $dst_fh;
		596	} else {
		597	$grp->result (-1);
		598	close $src_fh;
		599	close $dst_fh;
		600
		601	aioreq $pri;
		602	add $grp aio_unlink $dst;
		603	}
		604	};
		605	} else {
		606	$grp->result (-1);
		607	}
		608	},
		609
		610	} else {
		611	$grp->result (-1);
		612	}
		613	};
		614
		615	$grp
		616	}
		617	}
		618
		619	=item aio_move $srcpath, $dstpath, $callback->($status)
		620
		621	Try to move the I<file> (directories not supported as either source or
		622	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		623	the C<0> (error) or C<-1> ok.
		624
		625	This is a composite request that tries to rename(2) the file first. If
		626	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		627	that is successful, unlinking the C<$srcpath>.
		628
		629	=cut
		630
		631	sub aio_move($$;$) {
		632	aio_block {
		633	my ($src, $dst, $cb) = @_;
		634
		635	my $pri = aioreq_pri;
		636	my $grp = aio_group $cb;
		637
		638	aioreq_pri $pri;
		639	add $grp aio_rename $src, $dst, sub {
		640	if ($_[0] && $! == EXDEV) {
		641	aioreq_pri $pri;
		642	add $grp aio_copy $src, $dst, sub {
		643	$grp->result ($_[0]);
		644
		645	if (!$_[0]) {
		646	aioreq_pri $pri;
		647	add $grp aio_unlink $src;
		648	}
		649	};
		650	} else {
		651	$grp->result ($_[0]);
		652	}
		653	};
		654
		655	$grp
		656	}
		657	}
		658
346	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	659	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
347		660
348	Scans a directory (similar to C<aio_readdir>) but additionally tries to	661	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	662	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	663	names, directories you can recurse into (directories), and ones you cannot
351	recurse into (everything else).	664	recurse into (everything else, including symlinks to directories).
352		665
353	C<aio_scandir> is a composite request that consists of many sub	666	C<aio_scandir> is a composite request that creates of many sub requests_
354	requests. C<$maxreq> specifies the maximum number of outstanding aio	667	C<$maxreq> specifies the maximum number of outstanding aio requests that
355	requests that this function generates. If it is C<< <= 0 >>, then a	668	this function generates. If it is C<< <= 0 >>, then a suitable default
356	suitable default will be chosen (currently 8).	669	will be chosen (currently 4).
357		670
358	On error, the callback is called without arguments, otherwise it receives	671	On error, the callback is called without arguments, otherwise it receives
359	two array-refs with path-relative entry names.	672	two array-refs with path-relative entry names.
360		673
361	Example:	674	Example:
…		…
395	as those tend to return 0 or 1 as link counts, which disables the	708	as those tend to return 0 or 1 as link counts, which disables the
396	directory counting heuristic.	709	directory counting heuristic.
397		710
398	=cut	711	=cut
399		712
400	sub aio_scandir($$$) {	713	sub aio_scandir($$;$) {
		714	aio_block {
401	my ($path, $maxreq, $cb) = @_;	715	my ($path, $maxreq, $cb) = @_;
402		716
		717	my $pri = aioreq_pri;
		718
403	my $grp = aio_group;	719	my $grp = aio_group $cb;
404		720
405	$maxreq = 8 if $maxreq <= 0;	721	$maxreq = 4 if $maxreq <= 0;
406		722
407	# stat once	723	# stat once
		724	aioreq_pri $pri;
408	add $grp aio_stat $path, sub {	725	add $grp aio_stat $path, sub {
409	return $cb->() if $_[0];	726	return $grp->result () if $_[0];
410	my $now = time;	727	my $now = time;
411	my $hash1 = join ":", (stat _)[0,1,3,7,9];	728	my $hash1 = join ":", (stat _)[0,1,3,7,9];
412		729
413	# read the directory entries	730	# read the directory entries
		731	aioreq_pri $pri;
414	add $grp aio_readdir $path, sub {	732	add $grp aio_readdir $path, sub {
415	my $entries = shift	733	my $entries = shift
416	or return $cb->();	734	or return $grp->result ();
417		735
418	# stat the dir another time	736	# stat the dir another time
		737	aioreq_pri $pri;
419	add $grp aio_stat $path, sub {	738	add $grp aio_stat $path, sub {
420	my $hash2 = join ":", (stat _)[0,1,3,7,9];	739	my $hash2 = join ":", (stat _)[0,1,3,7,9];
421		740
422	my $ndirs;	741	my $ndirs;
423		742
424	# take the slow route if anything looks fishy	743	# take the slow route if anything looks fishy
425	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	744	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
426	$ndirs = -1;	745	$ndirs = -1;
427	} else {	746	} else {
428	# if nlink == 2, we are finished	747	# if nlink == 2, we are finished
429	# on non-posix-fs's, we rely on nlink < 2	748	# on non-posix-fs's, we rely on nlink < 2
430	$ndirs = (stat _)[3] - 2	749	$ndirs = (stat _)[3] - 2
431	or return $cb->([], $entries);	750	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	}	751	}
		752
		753	# sort into likely dirs and likely nondirs
		754	# dirs == files without ".", short entries first
		755	$entries = [map $_->[0],
		756	sort { $b->[1] cmp $a->[1] }
		757	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		758	@$entries];
		759
		760	my (@dirs, @nondirs);
		761
		762	my $statgrp = add $grp aio_group sub {
		763	$grp->result (\@dirs, \@nondirs);
		764	};
		765
		766	limit $statgrp $maxreq;
		767	feed $statgrp sub {
		768	return unless @$entries;
		769	my $entry = pop @$entries;
		770
		771	aioreq_pri $pri;
		772	add $statgrp aio_stat "$path/$entry/.", sub {
		773	if ($_[0] < 0) {
		774	push @nondirs, $entry;
		775	} else {
		776	# need to check for real directory
		777	aioreq_pri $pri;
		778	add $statgrp aio_lstat "$path/$entry", sub {
		779	if (-d _) {
		780	push @dirs, $entry;
		781
		782	unless (--$ndirs) {
		783	push @nondirs, @$entries;
		784	feed $statgrp;
		785	}
		786	} else {
		787	push @nondirs, $entry;
		788	}
		789	}
		790	}
		791	};
		792	};
460	};	793	};
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	};	794	};
491	};	795	};
		796
		797	$grp
492	};	798	}
		799	}
493		800
		801	=item aio_rmtree $path, $callback->($status)
		802
		803	Delete a directory tree starting (and including) C<$path>, return the
		804	status of the final C<rmdir> only. This is a composite request that
		805	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		806	everything else.
		807
		808	=cut
		809
		810	sub aio_rmtree;
		811	sub aio_rmtree($;$) {
		812	aio_block {
		813	my ($path, $cb) = @_;
		814
		815	my $pri = aioreq_pri;
		816	my $grp = aio_group $cb;
		817
		818	aioreq_pri $pri;
		819	add $grp aio_scandir $path, 0, sub {
		820	my ($dirs, $nondirs) = @_;
		821
		822	my $dirgrp = aio_group sub {
		823	add $grp aio_rmdir $path, sub {
		824	$grp->result ($_[0]);
		825	};
		826	};
		827
		828	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		829	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		830
		831	add $grp $dirgrp;
		832	};
		833
494	$grp	834	$grp
		835	}
495	}	836	}
496		837
497	=item aio_fsync $fh, $callback->($status)	838	=item aio_fsync $fh, $callback->($status)
498		839
499	Asynchronously call fsync on the given filehandle and call the callback	840	Asynchronously call fsync on the given filehandle and call the callback
…		…
505	callback with the fdatasync result code.	846	callback with the fdatasync result code.
506		847
507	If this call isn't available because your OS lacks it or it couldn't be	848	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.	849	detected, it will be emulated by calling C<fsync> instead.
509		850
510	=item aio_group $callback->()	851	=item aio_group $callback->(...)
511
512	[EXPERIMENTAL]
513		852
514	This is a very special aio request: Instead of doing something, it is a	853	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	854	container for other aio requests, which is useful if you want to bundle
516	many requests into a single, composite, request.	855	many requests into a single, composite, request with a definite callback
		856	and the ability to cancel the whole request with its subrequests.
517		857
518	Returns an object of class L<IO::AIO::GRP>. See its documentation below	858	Returns an object of class L<IO::AIO::GRP>. See its documentation below
519	for more info.	859	for more info.
520		860
521	Example:	861	Example:
…		…
527	add $grp	867	add $grp
528	(aio_stat ...),	868	(aio_stat ...),
529	(aio_stat ...),	869	(aio_stat ...),
530	...;	870	...;
531		871
		872	=item aio_nop $callback->()
		873
		874	This is a special request - it does nothing in itself and is only used for
		875	side effects, such as when you want to add a dummy request to a group so
		876	that finishing the requests in the group depends on executing the given
		877	code.
		878
		879	While this request does nothing, it still goes through the execution
		880	phase and still requires a worker thread. Thus, the callback will not
		881	be executed immediately but only after other requests in the queue have
		882	entered their execution phase. This can be used to measure request
		883	latency.
		884
532	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	885	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
533		886
534	Mainly used for debugging and benchmarking, this aio request puts one of	887	Mainly used for debugging and benchmarking, this aio request puts one of
535	the request workers to sleep for the given time.	888	the request workers to sleep for the given time.
536		889
537	While it is theoretically handy to have simple I/O scheduling requests	890	While it is theoretically handy to have simple I/O scheduling requests
538	like sleep and file handle readable/writable, the overhead this creates	891	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	892	immense (it blocks a thread for a long time) so do not use this function
540	under artificial I/O pressure.	893	except to put your application under artificial I/O pressure.
541		894
542	=back	895	=back
543		896
544	=head2 IO::AIO::REQ CLASS	897	=head2 IO::AIO::REQ CLASS
545		898
546	All non-aggregate C<aio_*> functions return an object of this class when	899	All non-aggregate C<aio_*> functions return an object of this class when
547	called in non-void context.	900	called in non-void context.
548		901
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	902	=over 4
558		903
559	=item $req->cancel	904	=item cancel $req
560		905
561	Cancels the request, if possible. Has the effect of skipping execution	906	Cancels the request, if possible. Has the effect of skipping execution
562	when entering the B<execute> state and skipping calling the callback when	907	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	908	entering the the B<result> state, but will leave the request otherwise
564	untouched. That means that requests that currently execute will not be	909	untouched. That means that requests that currently execute will not be
565	stopped and resources held by the request will not be freed prematurely.	910	stopped and resources held by the request will not be freed prematurely.
566		911
		912	=item cb $req $callback->(...)
		913
		914	Replace (or simply set) the callback registered to the request.
		915
567	=back	916	=back
568		917
569	=head2 IO::AIO::GRP CLASS	918	=head2 IO::AIO::GRP CLASS
570		919
571	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	920	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	934	You add requests by calling the C<add> method with one or more
586	C<IO::AIO::REQ> objects:	935	C<IO::AIO::REQ> objects:
587		936
588	$grp->add (aio_unlink "...");	937	$grp->add (aio_unlink "...");
589		938
590	add $grp aio_stat "...", sub { ... };	939	add $grp aio_stat "...", sub {
		940	$_[0] or return $grp->result ("error");
		941
		942	# add another request dynamically, if first succeeded
		943	add $grp aio_open "...", sub {
		944	$grp->result ("ok");
		945	};
		946	};
591		947
592	This makes it very easy to create composite requests (see the source of	948	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.	949	C<aio_move> for an application) that work and feel like simple requests.
594		950
		951	=over 4
		952
595	The IO::AIO::GRP objects will be cleaned up during calls to	953	=item * The IO::AIO::GRP objects will be cleaned up during calls to
596	C<IO::AIO::poll_cb>, just like any other request.	954	C<IO::AIO::poll_cb>, just like any other request.
597		955
598	They can be canceled like any other request. Canceling will cancel not	956	=item * They can be canceled like any other request. Canceling will cancel not
599	just the request itself, but also all requests it contains.	957	only the request itself, but also all requests it contains.
600		958
601	They can also can also be added to other IO::AIO::GRP objects.	959	=item * They can also can also be added to other IO::AIO::GRP objects.
		960
		961	=item * You must not add requests to a group from within the group callback (or
		962	any later time).
		963
		964	=back
602		965
603	Their lifetime, simplified, looks like this: when they are empty, they	966	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	967	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	968	C<done> state, they will also finish. Otherwise they will continue to
606	exist.	969	exist.
607		970
		971	That means after creating a group you have some time to add requests. And
		972	in the callbacks of those requests, you can add further requests to the
		973	group. And only when all those requests have finished will the the group
		974	itself finish.
		975
608	=over 4	976	=over 4
609		977
		978	=item add $grp ...
		979
610	=item $grp->add (...)	980	=item $grp->add (...)
611		981
612	=item add $grp ...	982	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		983	be added, including other groups, as long as you do not create circular
		984	dependencies.
613		985
614	Add one or more	986	Returns all its arguments.
615	Cancels the request, if possible. Has the effect of skipping execution	987
616	when entering the B<execute> state and skipping calling the callback when	988	=item $grp->cancel_subs
617	entering the the B<result> state, but will leave the request otherwise	989
618	untouched. That means that requests that currently execute will not be	990	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.	991	itself. Useful when you queued a lot of events but got a result early.
		992
		993	=item $grp->result (...)
		994
		995	Set the result value(s) that will be passed to the group callback when all
		996	subrequests have finished and set thre groups errno to the current value
		997	of errno (just like calling C<errno> without an error number). By default,
		998	no argument will be passed and errno is zero.
		999
		1000	=item $grp->errno ([$errno])
		1001
		1002	Sets the group errno value to C<$errno>, or the current value of errno
		1003	when the argument is missing.
		1004
		1005	Every aio request has an associated errno value that is restored when
		1006	the callback is invoked. This method lets you change this value from its
		1007	default (0).
		1008
		1009	Calling C<result> will also set errno, so make sure you either set C<$!>
		1010	before the call to C<result>, or call c<errno> after it.
		1011
		1012	=item feed $grp $callback->($grp)
		1013
		1014	Sets a feeder/generator on this group: every group can have an attached
		1015	generator that generates requests if idle. The idea behind this is that,
		1016	although you could just queue as many requests as you want in a group,
		1017	this might starve other requests for a potentially long time. For
		1018	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		1019	requests, delaying any later requests for a long time.
		1020
		1021	To avoid this, and allow incremental generation of requests, you can
		1022	instead a group and set a feeder on it that generates those requests. The
		1023	feed callback will be called whenever there are few enough (see C<limit>,
		1024	below) requests active in the group itself and is expected to queue more
		1025	requests.
		1026
		1027	The feed callback can queue as many requests as it likes (i.e. C<add> does
		1028	not impose any limits).
		1029
		1030	If the feed does not queue more requests when called, it will be
		1031	automatically removed from the group.
		1032
		1033	If the feed limit is C<0>, it will be set to C<2> automatically.
		1034
		1035	Example:
		1036
		1037	# stat all files in @files, but only ever use four aio requests concurrently:
		1038
		1039	my $grp = aio_group sub { print "finished\n" };
		1040	limit $grp 4;
		1041	feed $grp sub {
		1042	my $file = pop @files
		1043	or return;
		1044
		1045	add $grp aio_stat $file, sub { ... };
		1046	};
		1047
		1048	=item limit $grp $num
		1049
		1050	Sets the feeder limit for the group: The feeder will be called whenever
		1051	the group contains less than this many requests.
		1052
		1053	Setting the limit to C<0> will pause the feeding process.
620		1054
621	=back	1055	=back
622		1056
623	=head2 SUPPORT FUNCTIONS	1057	=head2 SUPPORT FUNCTIONS
		1058
		1059	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
624		1060
625	=over 4	1061	=over 4
626		1062
627	=item $fileno = IO::AIO::poll_fileno	1063	=item $fileno = IO::AIO::poll_fileno
628		1064
…		…
633		1069
634	See C<poll_cb> for an example.	1070	See C<poll_cb> for an example.
635		1071
636	=item IO::AIO::poll_cb	1072	=item IO::AIO::poll_cb
637		1073
638	Process all outstanding events on the result pipe. You have to call this	1074	Process some outstanding events on the result pipe. You have to call this
639	regularly. Returns the number of events processed. Returns immediately	1075	regularly. Returns the number of events processed. Returns immediately
640	when no events are outstanding.	1076	when no events are outstanding. The amount of events processed depends on
		1077	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1078
		1079	If not all requests were processed for whatever reason, the filehandle
		1080	will still be ready when C<poll_cb> returns.
641		1081
642	Example: Install an Event watcher that automatically calls	1082	Example: Install an Event watcher that automatically calls
643	IO::AIO::poll_cb with high priority:	1083	IO::AIO::poll_cb with high priority:
644		1084
645	Event->io (fd => IO::AIO::poll_fileno,	1085	Event->io (fd => IO::AIO::poll_fileno,
646	poll => 'r', async => 1,	1086	poll => 'r', async => 1,
647	cb => \&IO::AIO::poll_cb);	1087	cb => \&IO::AIO::poll_cb);
648		1088
		1089	=item IO::AIO::max_poll_reqs $nreqs
		1090
		1091	=item IO::AIO::max_poll_time $seconds
		1092
		1093	These set the maximum number of requests (default C<0>, meaning infinity)
		1094	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1095	the maximum amount of time (default C<0>, meaning infinity) spent in
		1096	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1097	of time C<poll_cb> is allowed to use).
		1098
		1099	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1100	syscall per request processed, which is not normally a problem unless your
		1101	callbacks are really really fast or your OS is really really slow (I am
		1102	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1103
		1104	Setting these is useful if you want to ensure some level of
		1105	interactiveness when perl is not fast enough to process all requests in
		1106	time.
		1107
		1108	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1109
		1110	Example: Install an Event watcher that automatically calls
		1111	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1112	program get the CPU sometimes even under high AIO load.
		1113
		1114	# try not to spend much more than 0.1s in poll_cb
		1115	IO::AIO::max_poll_time 0.1;
		1116
		1117	# use a low priority so other tasks have priority
		1118	Event->io (fd => IO::AIO::poll_fileno,
		1119	poll => 'r', nice => 1,
		1120	cb => &IO::AIO::poll_cb);
		1121
649	=item IO::AIO::poll_wait	1122	=item IO::AIO::poll_wait
650		1123
		1124	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	1125	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	1126	does a C<select> on the filehandle. This is useful if you want to
653	for some requests to finish).	1127	synchronously wait for some requests to finish).
654		1128
655	See C<nreqs> for an example.	1129	See C<nreqs> for an example.
656		1130
		1131	=item IO::AIO::poll
		1132
		1133	Waits until some requests have been handled.
		1134
		1135	Returns the number of requests processed, but is otherwise strictly
		1136	equivalent to:
		1137
		1138	IO::AIO::poll_wait, IO::AIO::poll_cb
		1139
657	=item IO::AIO::nreqs	1140	=item IO::AIO::flush
658		1141
659	Returns the number of requests currently outstanding (i.e. for which their	1142	Wait till all outstanding AIO requests have been handled.
660	callback has not been invoked yet).
661		1143
662	Example: wait till there are no outstanding requests anymore:	1144	Strictly equivalent to:
663		1145
664	IO::AIO::poll_wait, IO::AIO::poll_cb	1146	IO::AIO::poll_wait, IO::AIO::poll_cb
665	while IO::AIO::nreqs;	1147	while IO::AIO::nreqs;
666		1148
667	=item IO::AIO::flush	1149	=back
668		1150
669	Wait till all outstanding AIO requests have been handled.	1151	=head3 CONTROLLING THE NUMBER OF THREADS
670		1152
671	Strictly equivalent to:	1153	=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		1154
685	=item IO::AIO::min_parallel $nthreads	1155	=item IO::AIO::min_parallel $nthreads
686		1156
687	Set the minimum number of AIO threads to C<$nthreads>. The current default	1157	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	1158	default is C<8>, which means eight asynchronous operations can execute
689	(the number of outstanding operations, however, is unlimited).	1159	concurrently at any one time (the number of outstanding requests,
		1160	however, is unlimited).
690		1161
691	IO::AIO starts threads only on demand, when an AIO request is queued and	1162	IO::AIO starts threads only on demand, when an AIO request is queued and
692	no free thread exists.	1163	no free thread exists. Please note that queueing up a hundred requests can
		1164	create demand for a hundred threads, even if it turns out that everything
		1165	is in the cache and could have been processed faster by a single thread.
693		1166
694	It is recommended to keep the number of threads low, as some Linux	1167	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	1168	Linux kernel versions will scale negatively with the number of threads
696	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1169	(higher parallelity => MUCH higher latency). With current Linux 2.6
697	threads should be fine.	1170	versions, 4-32 threads should be fine.
698		1171
699	Under most circumstances you don't need to call this function, as the	1172	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.	1173	module selects a default that is suitable for low to moderate load.
701		1174
702	=item IO::AIO::max_parallel $nthreads	1175	=item IO::AIO::max_parallel $nthreads
…		…
711	This module automatically runs C<max_parallel 0> at program end, to ensure	1184	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.	1185	that all threads are killed and that there are no outstanding requests.
713		1186
714	Under normal circumstances you don't need to call this function.	1187	Under normal circumstances you don't need to call this function.
715		1188
		1189	=item IO::AIO::max_idle $nthreads
		1190
		1191	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1192	threads that did not get a request to process within 10 seconds). That
		1193	means if a thread becomes idle while C<$nthreads> other threads are also
		1194	idle, it will free its resources and exit.
		1195
		1196	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1197	to allow for extremely high load situations, but want to free resources
		1198	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1199
		1200	The default is probably ok in most situations, especially if thread
		1201	creation is fast. If thread creation is very slow on your system you might
		1202	want to use larger values.
		1203
716	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1204	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1205
		1206	This is a very bad function to use in interactive programs because it
		1207	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1208	use an C<aio_group> together with a feed callback.
717		1209
718	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1210	Sets the maximum number of outstanding requests to C<$nreqs>. If you
719	try to queue up more than this number of requests, the caller will block until	1211	to queue up more than this number of requests, the next call to the
720	some requests have been handled.	1212	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1213	function will block until the limit is no longer exceeded.
721		1214
722	The default is very large, so normally there is no practical limit. If you	1215	The default value is very large, so there is no practical limit on the
723	queue up many requests in a loop it often improves speed if you set	1216	number of outstanding requests.
724	this to a relatively low number, such as C<100>.
725		1217
726	Under normal circumstances you don't need to call this function.	1218	You can still queue as many requests as you want. Therefore,
		1219	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1220	as a stop gap to shield against fatal memory overflow (with large values).
		1221
		1222	=back
		1223
		1224	=head3 STATISTICAL INFORMATION
		1225
		1226	=over
		1227
		1228	=item IO::AIO::nreqs
		1229
		1230	Returns the number of requests currently in the ready, execute or pending
		1231	states (i.e. for which their callback has not been invoked yet).
		1232
		1233	Example: wait till there are no outstanding requests anymore:
		1234
		1235	IO::AIO::poll_wait, IO::AIO::poll_cb
		1236	while IO::AIO::nreqs;
		1237
		1238	=item IO::AIO::nready
		1239
		1240	Returns the number of requests currently in the ready state (not yet
		1241	executed).
		1242
		1243	=item IO::AIO::npending
		1244
		1245	Returns the number of requests currently in the pending state (executed,
		1246	but not yet processed by poll_cb).
727		1247
728	=back	1248	=back
729		1249
730	=cut	1250	=cut
731		1251
…		…
743	or return undef;	1263	or return undef;
744		1264
745	*$sym	1265	*$sym
746	}	1266	}
747		1267
748	min_parallel 4;	1268	min_parallel 8;
749		1269
750	END {	1270	END { flush }
751	max_parallel 0;
752	}
753		1271
754	1;	1272	1;
755		1273
756	=head2 FORK BEHAVIOUR	1274	=head2 FORK BEHAVIOUR
757		1275
758	This module should do "the right thing" when the process using it forks:	1276	This module should do "the right thing" when the process using it forks:
759		1277
760	Before the fork, IO::AIO enters a quiescent state where no requests	1278	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	1279	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	1280	the fork the parent simply leaves the quiescent state and continues
763	request/result processing, while the child clears the request/result	1281	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	1282	(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	1283	parent). Threads will be started on demand until the limit set in the
766	parent process has been reached again.	1284	parent process has been reached again.
767		1285
768	In short: the parent will, after a short pause, continue as if fork had	1286	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	1287	not been called, while the child will act as if IO::AIO has not been used
770	yet.	1288	yet.
771		1289
		1290	=head2 MEMORY USAGE
		1291
		1292	Per-request usage:
		1293
		1294	Each aio request uses - depending on your architecture - around 100-200
		1295	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1296	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1297	scalars and other data passed into aio requests will also be locked and
		1298	will consume memory till the request has entered the done state.
		1299
		1300	This is now awfully much, so queuing lots of requests is not usually a
		1301	problem.
		1302
		1303	Per-thread usage:
		1304
		1305	In the execution phase, some aio requests require more memory for
		1306	temporary buffers, and each thread requires a stack and other data
		1307	structures (usually around 16k-128k, depending on the OS).
		1308
		1309	=head1 KNOWN BUGS
		1310
		1311	Known bugs will be fixed in the next release.
		1312
772	=head1 SEE ALSO	1313	=head1 SEE ALSO
773		1314
774	L<Coro>, L<Linux::AIO> (obsolete).	1315	L<Coro::AIO>.
775		1316
776	=head1 AUTHOR	1317	=head1 AUTHOR
777		1318
778	Marc Lehmann <schmorp@schmorp.de>	1319	Marc Lehmann <schmorp@schmorp.de>
779	http://home.schmorp.de/	1320	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs. Revision 1.110 by root, Sun Jul 8 09:09:34 2007 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs.
Revision 1.110 by root, Sun Jul 8 09:09:34 2007 UTC