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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.109 by root, Sun Jun 3 09:44:17 2007 UTC

…		…
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", O_RDONLY, 0, sub {
10	my ($fh) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
…		…
51	=head1 DESCRIPTION	52	=head1 DESCRIPTION
52		53
53	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
54	operating system supports.	55	operating system supports.
55		56
		57	Asynchronous means that operations that can normally block your program
		58	(e.g. reading from disk) will be done asynchronously: the operation
		59	will still block, but you can do something else in the meantime. This
		60	is extremely useful for programs that need to stay interactive even
		61	when doing heavy I/O (GUI programs, high performance network servers
		62	etc.), but can also be used to easily do operations in parallel that are
		63	normally done sequentially, e.g. stat'ing many files, which is much faster
		64	on a RAID volume or over NFS when you do a number of stat operations
		65	concurrently.
		66
		67	While most of this works on all types of file descriptors (for
		68	example sockets), using these functions on file descriptors that
		69	support nonblocking operation (again, sockets, pipes etc.) is very
		70	inefficient. Use an event loop for that (such as the L<Event\|Event>
		71	module): IO::AIO will naturally fit into such an event loop itself.
		72
56	Currently, a number of threads are started that execute your read/writes	73	In this version, a number of threads are started that execute your
57	and signal their completion. You don't need thread support in perl, and	74	requests and signal their completion. You don't need thread support
58	the threads created by this module will not be visible to perl. In the	75	in perl, and the threads created by this module will not be visible
59	future, this module might make use of the native aio functions available	76	to perl. In the future, this module might make use of the native aio
60	on many operating systems. However, they are often not well-supported	77	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	78	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	and they would only support aio_read and aio_write, so the remaining	79	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	80	aio_write, so the remaining functionality would have to be implemented
		81	using threads anyway.
64		82
65	Although the module will work with in the presence of other threads,	83	Although the module will work in the presence of other (Perl-) threads,
66	it is currently not reentrant in any way, so use appropriate locking	84	it is currently not reentrant in any way, so use appropriate locking
67	yourself, always call C<poll_cb> from within the same thread, or never	85	yourself, always call C<poll_cb> from within the same thread, or never
68	call C<poll_cb> (or other C<aio_> functions) recursively.	86	call C<poll_cb> (or other C<aio_> functions) recursively.
69		87
		88	=head2 EXAMPLE
		89
		90	This is a simple example that uses the Event module and loads
		91	F</etc/passwd> asynchronously:
		92
		93	use Fcntl;
		94	use Event;
		95	use IO::AIO;
		96
		97	# register the IO::AIO callback with Event
		98	Event->io (fd => IO::AIO::poll_fileno,
		99	poll => 'r',
		100	cb => \&IO::AIO::poll_cb);
		101
		102	# queue the request to open /etc/passwd
		103	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		104	my $fh = shift
		105	or die "error while opening: $!";
		106
		107	# stat'ing filehandles is generally non-blocking
		108	my $size = -s $fh;
		109
		110	# queue a request to read the file
		111	my $contents;
		112	aio_read $fh, 0, $size, $contents, 0, sub {
		113	$_[0] == $size
		114	or die "short read: $!";
		115
		116	close $fh;
		117
		118	# file contents now in $contents
		119	print $contents;
		120
		121	# exit event loop and program
		122	Event::unloop;
		123	};
		124	};
		125
		126	# possibly queue up other requests, or open GUI windows,
		127	# check for sockets etc. etc.
		128
		129	# process events as long as there are some:
		130	Event::loop;
		131
		132	=head1 REQUEST ANATOMY AND LIFETIME
		133
		134	Every C<aio_*> function creates a request. which is a C data structure not
		135	directly visible to Perl.
		136
		137	If called in non-void context, every request function returns a Perl
		138	object representing the request. In void context, nothing is returned,
		139	which saves a bit of memory.
		140
		141	The perl object is a fairly standard ref-to-hash object. The hash contents
		142	are not used by IO::AIO so you are free to store anything you like in it.
		143
		144	During their existance, aio requests travel through the following states,
		145	in order:
		146
		147	=over 4
		148
		149	=item ready
		150
		151	Immediately after a request is created it is put into the ready state,
		152	waiting for a thread to execute it.
		153
		154	=item execute
		155
		156	A thread has accepted the request for processing and is currently
		157	executing it (e.g. blocking in read).
		158
		159	=item pending
		160
		161	The request has been executed and is waiting for result processing.
		162
		163	While request submission and execution is fully asynchronous, result
		164	processing is not and relies on the perl interpreter calling C<poll_cb>
		165	(or another function with the same effect).
		166
		167	=item result
		168
		169	The request results are processed synchronously by C<poll_cb>.
		170
		171	The C<poll_cb> function will process all outstanding aio requests by
		172	calling their callbacks, freeing memory associated with them and managing
		173	any groups they are contained in.
		174
		175	=item done
		176
		177	Request has reached the end of its lifetime and holds no resources anymore
		178	(except possibly for the Perl object, but its connection to the actual
		179	aio request is severed and calling its methods will either do nothing or
		180	result in a runtime error).
		181
		182	=back
		183
70	=cut	184	=cut
71		185
72	package IO::AIO;	186	package IO::AIO;
73		187
74	no warnings;	188	no warnings;
75	use strict 'vars';	189	use strict 'vars';
76		190
77	use base 'Exporter';	191	use base 'Exporter';
78		192
79	BEGIN {	193	BEGIN {
80	our $VERSION = '2.0';	194	our $VERSION = '2.4';
81		195
82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	196	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
83	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
84	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
85	aio_group aio_nop);	199	aio_move aio_copy aio_group aio_nop aio_mknod aio_load aio_rmtree aio_mkdir
		200	aio_chown aio_chmod aio_utime);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice aio_block));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	203	min_parallel max_parallel max_idle
		204	nreqs nready npending nthreads
		205	max_poll_time max_poll_reqs);
89		206
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		208
92	require XSLoader;	209	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
94	}	211	}
95		212
96	=head1 FUNCTIONS	213	=head1 FUNCTIONS
97		214
98	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
99		216
100	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
101	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
102	and they all accept an additional (and optional) C<$callback> argument	219	and they all accept an additional (and optional) C<$callback> argument
103	which must be a code reference. This code reference will get called with	220	which must be a code reference. This code reference will get called with
…		…
106	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
107		224
108	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
109	internally until the request has finished.	226	internally until the request has finished.
110		227
111	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
112	manipulation of those requests while they are in-flight.	229	further manipulation of those requests while they are in-flight.
113		230
114	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
115	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
116	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
117	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
118	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
119		237
120	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
121	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
122	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	240	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
123	your pathnames to the locale (or other) encoding in effect in the user	241	your pathnames to the locale (or other) encoding in effect in the user
124	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	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.
126		247
127	=over 4	248	=over 4
128		249
129	=item aioreq_pri $pri	250	=item $prev_pri = aioreq_pri [$pri]
130		251
131	Sets the priority for the next aio request. The default priority	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
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	255	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	256	and C<4>, respectively. Requests with higher priority will be serviced
		257	first.
134		258
135	The priority will be reset to C<0> after each call to one of the C<aio_>	259	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	260	functions.
137		261
138	Example: open a file with low priority, then read something from it with	262	Example: open a file with low priority, then read something from it with
139	higher priority so the read request is serviced before other low priority	263	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	264	open requests (potentially spamming the cache):
…		…
147	aio_read $_[0], ..., sub {	271	aio_read $_[0], ..., sub {
148	...	272	...
149	};	273	};
150	};	274	};
151		275
		276
152	=item aioreq_nice $pri_adjust	277	=item aioreq_nice $pri_adjust
153		278
154	Similar to C<aioreq_pri>, but subtracts the given value from the current	279	Similar to C<aioreq_pri>, but subtracts the given value from the current
155	priority, so effects are cumulative.	280	priority, so the effect is cumulative.
		281
156		282
157	=item aio_open $pathname, $flags, $mode, $callback->($fh)	283	=item aio_open $pathname, $flags, $mode, $callback->($fh)
158		284
159	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
160	created filehandle for the file.	286	created filehandle for the file.
…		…
166	list. They are the same as used by C<sysopen>.	292	list. They are the same as used by C<sysopen>.
167		293
168	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
169	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>,
170	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,
171	and C<0666> or C<0777> if you do).	297	and C<0666> or C<0777> if you do). Note that the C<$mode> will be modified
		298	by the umask in effect then the request is being executed, so better never
		299	change the umask.
172		300
173	Example:	301	Example:
174		302
175	aio_open "/etc/passwd", O_RDONLY, 0, sub {	303	aio_open "/etc/passwd", O_RDONLY, 0, sub {
176	if ($_[0]) {	304	if ($_[0]) {
…		…
179	} else {	307	} else {
180	die "open failed: $!\n";	308	die "open failed: $!\n";
181	}	309	}
182	};	310	};
183		311
		312
184	=item aio_close $fh, $callback->($status)	313	=item aio_close $fh, $callback->($status)
185		314
186	Asynchronously close a file and call the callback with the result	315	Asynchronously close a file and call the callback with the result
187	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
188	filehandle here, as perl will likely close the file descriptor another	317	filehandle here, as perl will likely close the file descriptor another
…		…
190	C<close> or just let filehandles go out of scope.	319	C<close> or just let filehandles go out of scope.
191		320
192	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
193	therefore best to avoid this function.	322	therefore best to avoid this function.
194		323
		324
195	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	325	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
196		326
197	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	327	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
198		328
199	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<$offset>
200	into the scalar given by C<data> and offset C<dataoffset> and calls the	330	into the scalar given by C<$data> and offset C<$dataoffset> and calls the
201	callback without the actual number of bytes read (or -1 on error, just	331	callback without the actual number of bytes read (or -1 on error, just
202	like the syscall).	332	like the syscall).
203		333
		334	If C<$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
204	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
205	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
206	necessary/optional hardware is installed).	344	the necessary/optional hardware is installed).
207		345
208	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
209	offset C<0> within the scalar:	347	offset C<0> within the scalar:
210		348
211	aio_read $fh, 7, 15, $buffer, 0, sub {	349	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	350	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	351	print "read $_[0] bytes: <$buffer>\n";
214	};	352	};
215		353
216	=item aio_move $srcpath, $dstpath, $callback->($status)
217
218	[EXPERIMENTAL due to internal aio_group use]
219
220	Try to move the I<file> (directories not supported as either source or
221	destination) from C<$srcpath> to C<$dstpath> and call the callback with
222	the C<0> (error) or C<-1> ok.
223
224	This is a composite request that tries to rename(2) the file first. If
225	rename files with C<EXDEV>, it creates the destination file with mode 0200
226	and copies the contents of the source file into it using C<aio_sendfile>,
227	followed by restoring atime, mtime, access mode and uid/gid, in that
228	order, and unlinking the C<$srcpath>.
229
230	If an error occurs, the partial destination file will be unlinked, if
231	possible, except when setting atime, mtime, access mode and uid/gid, where
232	errors are being ignored.
233
234	=cut
235
236	sub aio_move($$$) {
237	my ($src, $dst, $cb) = @_;
238
239	my $grp = aio_group $cb;
240
241	add $grp aio_rename $src, $dst, sub {
242	if ($_[0] && $! == EXDEV) {
243	add $grp aio_open $src, O_RDONLY, 0, sub {
244	if (my $src_fh = $_[0]) {
245	my @stat = stat $src_fh;
246
247	add $grp aio_open $dst, O_WRONLY, 0200, sub {
248	if (my $dst_fh = $_[0]) {
249	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
250	close $src_fh;
251
252	if ($_[0] == $stat[7]) {
253	utime $stat[8], $stat[9], $dst;
254	chmod $stat[2] & 07777, $dst_fh;
255	chown $stat[4], $stat[5], $dst_fh;
256	close $dst_fh;
257
258	add $grp aio_unlink $src, sub {
259	$grp->result ($_[0]);
260	};
261	} else {
262	my $errno = $!;
263	add $grp aio_unlink $dst, sub {
264	$! = $errno;
265	$grp->result (-1);
266	};
267	}
268	};
269	} else {
270	$grp->result (-1);
271	}
272	},
273
274	} else {
275	$grp->result (-1);
276	}
277	};
278	} else {
279	$grp->result ($_[0]);
280	}
281	};
282
283	$grp
284	}
285		354
286	=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)
287		356
288	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
289	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
…		…
303	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
304	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
305	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
306	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
307	read.	376	read.
		377
308		378
309	=item aio_readahead $fh,$offset,$length, $callback->($retval)	379	=item aio_readahead $fh,$offset,$length, $callback->($retval)
310		380
311	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
312	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>
…		…
318	file. The current file offset of the file is left unchanged.	388	file. The current file offset of the file is left unchanged.
319		389
320	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
321	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.
322		392
		393
323	=item aio_stat $fh_or_path, $callback->($status)	394	=item aio_stat $fh_or_path, $callback->($status)
324		395
325	=item aio_lstat $fh, $callback->($status)	396	=item aio_lstat $fh, $callback->($status)
326		397
327	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
…		…
340	aio_stat "/etc/passwd", sub {	411	aio_stat "/etc/passwd", sub {
341	$_[0] and die "stat failed: $!";	412	$_[0] and die "stat failed: $!";
342	print "size is ", -s _, "\n";	413	print "size is ", -s _, "\n";
343	};	414	};
344		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_chmod $fh_or_path, $mode, $callback->($status)
		449
		450	Works like perl's C<chmod> function.
		451
		452
345	=item aio_unlink $pathname, $callback->($status)	453	=item aio_unlink $pathname, $callback->($status)
346		454
347	Asynchronously unlink (delete) a file and call the callback with the	455	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	456	result code.
349		457
		458
		459	=item aio_mknod $path, $mode, $dev, $callback->($status)
		460
		461	[EXPERIMENTAL]
		462
		463	Asynchronously create a device node (or fifo). See mknod(2).
		464
		465	The only (POSIX-) portable way of calling this function is:
		466
		467	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		468
		469
350	=item aio_link $srcpath, $dstpath, $callback->($status)	470	=item aio_link $srcpath, $dstpath, $callback->($status)
351		471
352	Asynchronously create a new link to the existing object at C<$srcpath> at	472	Asynchronously create a new link to the existing object at C<$srcpath> at
353	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.
354		474
		475
355	=item aio_symlink $srcpath, $dstpath, $callback->($status)	476	=item aio_symlink $srcpath, $dstpath, $callback->($status)
356		477
357	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	478	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
358	the path C<$dstpath> and call the callback with the result code.	479	the path C<$dstpath> and call the callback with the result code.
359		480
		481
		482	=item aio_readlink $path, $callback->($link)
		483
		484	Asynchronously read the symlink specified by C<$path> and pass it to
		485	the callback. If an error occurs, nothing or undef gets passed to the
		486	callback.
		487
		488
360	=item aio_rename $srcpath, $dstpath, $callback->($status)	489	=item aio_rename $srcpath, $dstpath, $callback->($status)
361		490
362	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	491	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
363	rename(2) and call the callback with the result code.	492	rename(2) and call the callback with the result code.
364		493
		494
		495	=item aio_mkdir $pathname, $mode, $callback->($status)
		496
		497	Asynchronously mkdir (create) a directory and call the callback with
		498	the result code. C<$mode> will be modified by the umask at the time the
		499	request is executed, so do not change your umask.
		500
		501
365	=item aio_rmdir $pathname, $callback->($status)	502	=item aio_rmdir $pathname, $callback->($status)
366		503
367	Asynchronously rmdir (delete) a directory and call the callback with the	504	Asynchronously rmdir (delete) a directory and call the callback with the
368	result code.	505	result code.
		506
369		507
370	=item aio_readdir $pathname, $callback->($entries)	508	=item aio_readdir $pathname, $callback->($entries)
371		509
372	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	510	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
373	directory (i.e. opendir + readdir + closedir). The entries will not be	511	directory (i.e. opendir + readdir + closedir). The entries will not be
374	sorted, and will B<NOT> include the C<.> and C<..> entries.	512	sorted, and will B<NOT> include the C<.> and C<..> entries.
375		513
376	The callback a single argument which is either C<undef> or an array-ref	514	The callback a single argument which is either C<undef> or an array-ref
377	with the filenames.	515	with the filenames.
378		516
		517
		518	=item aio_load $path, $data, $callback->($status)
		519
		520	This is a composite request that tries to fully load the given file into
		521	memory. Status is the same as with aio_read.
		522
		523	=cut
		524
		525	sub aio_load($$;$) {
		526	aio_block {
		527	my ($path, undef, $cb) = @_;
		528	my $data = \$_[1];
		529
		530	my $pri = aioreq_pri;
		531	my $grp = aio_group $cb;
		532
		533	aioreq_pri $pri;
		534	add $grp aio_open $path, O_RDONLY, 0, sub {
		535	my $fh = shift
		536	or return $grp->result (-1);
		537
		538	aioreq_pri $pri;
		539	add $grp aio_read $fh, 0, (-s $fh), $$data, 0, sub {
		540	$grp->result ($_[0]);
		541	};
		542	};
		543
		544	$grp
		545	}
		546	}
		547
		548	=item aio_copy $srcpath, $dstpath, $callback->($status)
		549
		550	Try to copy the I<file> (directories not supported as either source or
		551	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		552	the C<0> (error) or C<-1> ok.
		553
		554	This is a composite request that it creates the destination file with
		555	mode 0200 and copies the contents of the source file into it using
		556	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		557	uid/gid, in that order.
		558
		559	If an error occurs, the partial destination file will be unlinked, if
		560	possible, except when setting atime, mtime, access mode and uid/gid, where
		561	errors are being ignored.
		562
		563	=cut
		564
		565	sub aio_copy($$;$) {
		566	aio_block {
		567	my ($src, $dst, $cb) = @_;
		568
		569	my $pri = aioreq_pri;
		570	my $grp = aio_group $cb;
		571
		572	aioreq_pri $pri;
		573	add $grp aio_open $src, O_RDONLY, 0, sub {
		574	if (my $src_fh = $_[0]) {
		575	my @stat = stat $src_fh;
		576
		577	aioreq_pri $pri;
		578	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		579	if (my $dst_fh = $_[0]) {
		580	aioreq_pri $pri;
		581	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		582	if ($_[0] == $stat[7]) {
		583	$grp->result (0);
		584	close $src_fh;
		585
		586	# those should not normally block. should. should.
		587	utime $stat[8], $stat[9], $dst;
		588	chmod $stat[2] & 07777, $dst_fh;
		589	chown $stat[4], $stat[5], $dst_fh;
		590	close $dst_fh;
		591	} else {
		592	$grp->result (-1);
		593	close $src_fh;
		594	close $dst_fh;
		595
		596	aioreq $pri;
		597	add $grp aio_unlink $dst;
		598	}
		599	};
		600	} else {
		601	$grp->result (-1);
		602	}
		603	},
		604
		605	} else {
		606	$grp->result (-1);
		607	}
		608	};
		609
		610	$grp
		611	}
		612	}
		613
		614	=item aio_move $srcpath, $dstpath, $callback->($status)
		615
		616	Try to move the I<file> (directories not supported as either source or
		617	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		618	the C<0> (error) or C<-1> ok.
		619
		620	This is a composite request that tries to rename(2) the file first. If
		621	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		622	that is successful, unlinking the C<$srcpath>.
		623
		624	=cut
		625
		626	sub aio_move($$;$) {
		627	aio_block {
		628	my ($src, $dst, $cb) = @_;
		629
		630	my $pri = aioreq_pri;
		631	my $grp = aio_group $cb;
		632
		633	aioreq_pri $pri;
		634	add $grp aio_rename $src, $dst, sub {
		635	if ($_[0] && $! == EXDEV) {
		636	aioreq_pri $pri;
		637	add $grp aio_copy $src, $dst, sub {
		638	$grp->result ($_[0]);
		639
		640	if (!$_[0]) {
		641	aioreq_pri $pri;
		642	add $grp aio_unlink $src;
		643	}
		644	};
		645	} else {
		646	$grp->result ($_[0]);
		647	}
		648	};
		649
		650	$grp
		651	}
		652	}
		653
379	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	654	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
380		655
381	[EXPERIMENTAL due to internal aio_group use]
382
383	Scans a directory (similar to C<aio_readdir>) but additionally tries to	656	Scans a directory (similar to C<aio_readdir>) but additionally tries to
384	separate the entries of directory C<$path> into two sets of names, ones	657	efficiently separate the entries of directory C<$path> into two sets of
385	you can recurse into (directories or links to them), and ones you cannot	658	names, directories you can recurse into (directories), and ones you cannot
386	recurse into (everything else).	659	recurse into (everything else, including symlinks to directories).
387		660
388	C<aio_scandir> is a composite request that creates of many sub requests_	661	C<aio_scandir> is a composite request that creates of many sub requests_
389	C<$maxreq> specifies the maximum number of outstanding aio requests that	662	C<$maxreq> specifies the maximum number of outstanding aio requests that
390	this function generates. If it is C<< <= 0 >>, then a suitable default	663	this function generates. If it is C<< <= 0 >>, then a suitable default
391	will be chosen (currently 6).	664	will be chosen (currently 4).
392		665
393	On error, the callback is called without arguments, otherwise it receives	666	On error, the callback is called without arguments, otherwise it receives
394	two array-refs with path-relative entry names.	667	two array-refs with path-relative entry names.
395		668
396	Example:	669	Example:
…		…
430	as those tend to return 0 or 1 as link counts, which disables the	703	as those tend to return 0 or 1 as link counts, which disables the
431	directory counting heuristic.	704	directory counting heuristic.
432		705
433	=cut	706	=cut
434		707
435	sub aio_scandir($$$) {	708	sub aio_scandir($$;$) {
		709	aio_block {
436	my ($path, $maxreq, $cb) = @_;	710	my ($path, $maxreq, $cb) = @_;
437		711
		712	my $pri = aioreq_pri;
		713
438	my $grp = aio_group $cb;	714	my $grp = aio_group $cb;
439		715
440	$maxreq = 6 if $maxreq <= 0;	716	$maxreq = 4 if $maxreq <= 0;
441		717
442	# stat once	718	# stat once
		719	aioreq_pri $pri;
443	add $grp aio_stat $path, sub {	720	add $grp aio_stat $path, sub {
444	return $grp->result () if $_[0];	721	return $grp->result () if $_[0];
445	my $now = time;	722	my $now = time;
446	my $hash1 = join ":", (stat _)[0,1,3,7,9];	723	my $hash1 = join ":", (stat _)[0,1,3,7,9];
447		724
448	# read the directory entries	725	# read the directory entries
		726	aioreq_pri $pri;
449	add $grp aio_readdir $path, sub {	727	add $grp aio_readdir $path, sub {
450	my $entries = shift	728	my $entries = shift
451	or return $grp->result ();	729	or return $grp->result ();
452		730
453	# stat the dir another time	731	# stat the dir another time
		732	aioreq_pri $pri;
454	add $grp aio_stat $path, sub {	733	add $grp aio_stat $path, sub {
455	my $hash2 = join ":", (stat _)[0,1,3,7,9];	734	my $hash2 = join ":", (stat _)[0,1,3,7,9];
456		735
457	my $ndirs;	736	my $ndirs;
458		737
459	# take the slow route if anything looks fishy	738	# take the slow route if anything looks fishy
460	if ($hash1 ne $hash2 or (stat _)[9] == $now) {	739	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
461	$ndirs = -1;	740	$ndirs = -1;
462	} else {	741	} else {
463	# if nlink == 2, we are finished	742	# if nlink == 2, we are finished
464	# on non-posix-fs's, we rely on nlink < 2	743	# on non-posix-fs's, we rely on nlink < 2
465	$ndirs = (stat _)[3] - 2	744	$ndirs = (stat _)[3] - 2
466	or return $grp->result ([], $entries);	745	or return $grp->result ([], $entries);
467	}	746	}
468		747
469	# sort into likely dirs and likely nondirs	748	# sort into likely dirs and likely nondirs
470	# dirs == files without ".", short entries first	749	# dirs == files without ".", short entries first
471	$entries = [map $_->[0],	750	$entries = [map $_->[0],
472	sort { $b->[1] cmp $a->[1] }	751	sort { $b->[1] cmp $a->[1] }
473	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	752	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
474	@$entries];	753	@$entries];
475		754
476	my (@dirs, @nondirs);	755	my (@dirs, @nondirs);
477		756
478	my ($statcb, $schedcb);
479	my $nreq = 0;
480
481	my $statgrp = add $grp aio_group;	757	my $statgrp = add $grp aio_group sub {
482
483	$schedcb = sub {
484	if (@$entries) {
485	if ($nreq < $maxreq) {
486	my $ent = pop @$entries;
487	$nreq++;
488	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
489	}
490	} elsif (!$nreq) {
491	# finished
492	$statgrp->cancel;
493	undef $statcb;
494	undef $schedcb;
495	$grp->result (\@dirs, \@nondirs);	758	$grp->result (\@dirs, \@nondirs);
496	}	759	};
		760
		761	limit $statgrp $maxreq;
		762	feed $statgrp sub {
		763	return unless @$entries;
		764	my $entry = pop @$entries;
		765
		766	aioreq_pri $pri;
		767	add $statgrp aio_stat "$path/$entry/.", sub {
		768	if ($_[0] < 0) {
		769	push @nondirs, $entry;
		770	} else {
		771	# need to check for real directory
		772	aioreq_pri $pri;
		773	add $statgrp aio_lstat "$path/$entry", sub {
		774	if (-d _) {
		775	push @dirs, $entry;
		776
		777	unless (--$ndirs) {
		778	push @nondirs, @$entries;
		779	feed $statgrp;
		780	}
		781	} else {
		782	push @nondirs, $entry;
		783	}
		784	}
		785	}
		786	};
		787	};
497	};	788	};
498	$statcb = sub {
499	my ($status, $entry) = @_;
500
501	if ($status < 0) {
502	$nreq--;
503	push @nondirs, $entry;
504	&$schedcb;
505	} else {
506	# need to check for real directory
507	add $grp aio_lstat "$path/$entry", sub {
508	$nreq--;
509
510	if (-d _) {
511	push @dirs, $entry;
512
513	if (!--$ndirs) {
514	push @nondirs, @$entries;
515	$entries = [];
516	}
517	} else {
518	push @nondirs, $entry;
519	}
520
521	&$schedcb;
522	}
523	}
524	};
525
526	&$schedcb while @$entries && $nreq < $maxreq;
527	};	789	};
528	};	790	};
		791
		792	$grp
529	};	793	}
		794	}
530		795
		796	=item aio_rmtree $path, $callback->($status)
		797
		798	Delete a directory tree starting (and including) C<$path>, return the
		799	status of the final C<rmdir> only. This is a composite request that
		800	uses C<aio_scandir> to recurse into and rmdir directories, and unlink
		801	everything else.
		802
		803	=cut
		804
		805	sub aio_rmtree;
		806	sub aio_rmtree($;$) {
		807	aio_block {
		808	my ($path, $cb) = @_;
		809
		810	my $pri = aioreq_pri;
		811	my $grp = aio_group $cb;
		812
		813	aioreq_pri $pri;
		814	add $grp aio_scandir $path, 0, sub {
		815	my ($dirs, $nondirs) = @_;
		816
		817	my $dirgrp = aio_group sub {
		818	add $grp aio_rmdir $path, sub {
		819	$grp->result ($_[0]);
		820	};
		821	};
		822
		823	(aioreq_pri $pri), add $dirgrp aio_rmtree "$path/$_" for @$dirs;
		824	(aioreq_pri $pri), add $dirgrp aio_unlink "$path/$_" for @$nondirs;
		825
		826	add $grp $dirgrp;
		827	};
		828
531	$grp	829	$grp
		830	}
532	}	831	}
533		832
534	=item aio_fsync $fh, $callback->($status)	833	=item aio_fsync $fh, $callback->($status)
535		834
536	Asynchronously call fsync on the given filehandle and call the callback	835	Asynchronously call fsync on the given filehandle and call the callback
…		…
544	If this call isn't available because your OS lacks it or it couldn't be	843	If this call isn't available because your OS lacks it or it couldn't be
545	detected, it will be emulated by calling C<fsync> instead.	844	detected, it will be emulated by calling C<fsync> instead.
546		845
547	=item aio_group $callback->(...)	846	=item aio_group $callback->(...)
548		847
549	[EXPERIMENTAL]
550
551	This is a very special aio request: Instead of doing something, it is a	848	This is a very special aio request: Instead of doing something, it is a
552	container for other aio requests, which is useful if you want to bundle	849	container for other aio requests, which is useful if you want to bundle
553	many requests into a single, composite, request.	850	many requests into a single, composite, request with a definite callback
		851	and the ability to cancel the whole request with its subrequests.
554		852
555	Returns an object of class L<IO::AIO::GRP>. See its documentation below	853	Returns an object of class L<IO::AIO::GRP>. See its documentation below
556	for more info.	854	for more info.
557		855
558	Example:	856	Example:
…		…
577	phase and still requires a worker thread. Thus, the callback will not	875	phase and still requires a worker thread. Thus, the callback will not
578	be executed immediately but only after other requests in the queue have	876	be executed immediately but only after other requests in the queue have
579	entered their execution phase. This can be used to measure request	877	entered their execution phase. This can be used to measure request
580	latency.	878	latency.
581		879
582	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	880	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
583		881
584	Mainly used for debugging and benchmarking, this aio request puts one of	882	Mainly used for debugging and benchmarking, this aio request puts one of
585	the request workers to sleep for the given time.	883	the request workers to sleep for the given time.
586		884
587	While it is theoretically handy to have simple I/O scheduling requests	885	While it is theoretically handy to have simple I/O scheduling requests
588	like sleep and file handle readable/writable, the overhead this creates	886	like sleep and file handle readable/writable, the overhead this creates is
589	is immense, so do not use this function except to put your application	887	immense (it blocks a thread for a long time) so do not use this function
590	under artificial I/O pressure.	888	except to put your application under artificial I/O pressure.
591		889
592	=back	890	=back
593		891
594	=head2 IO::AIO::REQ CLASS	892	=head2 IO::AIO::REQ CLASS
595		893
596	All non-aggregate C<aio_*> functions return an object of this class when	894	All non-aggregate C<aio_*> functions return an object of this class when
597	called in non-void context.	895	called in non-void context.
598
599	A request always moves through the following five states in its lifetime,
600	in order: B<ready> (request has been created, but has not been executed
601	yet), B<execute> (request is currently being executed), B<pending>
602	(request has been executed but callback has not been called yet),
603	B<result> (results are being processed synchronously, includes calling the
604	callback) and B<done> (request has reached the end of its lifetime and
605	holds no resources anymore).
606		896
607	=over 4	897	=over 4
608		898
609	=item cancel $req	899	=item cancel $req
610		900
…		…
664	=item * They can also can also be added to other IO::AIO::GRP objects.	954	=item * They can also can also be added to other IO::AIO::GRP objects.
665		955
666	=item * You must not add requests to a group from within the group callback (or	956	=item * You must not add requests to a group from within the group callback (or
667	any later time).	957	any later time).
668		958
669	=item * This does not harmonise well with C<max_outstanding>, so best do
670	not combine C<aio_group> with it. Groups and feeders are recommended for
671	this kind of concurrency-limiting.
672
673	=back	959	=back
674		960
675	Their lifetime, simplified, looks like this: when they are empty, they	961	Their lifetime, simplified, looks like this: when they are empty, they
676	will finish very quickly. If they contain only requests that are in the	962	will finish very quickly. If they contain only requests that are in the
677	C<done> state, they will also finish. Otherwise they will continue to	963	C<done> state, they will also finish. Otherwise they will continue to
…		…
692	be added, including other groups, as long as you do not create circular	978	be added, including other groups, as long as you do not create circular
693	dependencies.	979	dependencies.
694		980
695	Returns all its arguments.	981	Returns all its arguments.
696		982
		983	=item $grp->cancel_subs
		984
		985	Cancel all subrequests and clears any feeder, but not the group request
		986	itself. Useful when you queued a lot of events but got a result early.
		987
697	=item $grp->result (...)	988	=item $grp->result (...)
698		989
699	Set the result value(s) that will be passed to the group callback when all	990	Set the result value(s) that will be passed to the group callback when all
700	subrequests have finished. By default, no argument will be passed.	991	subrequests have finished and set thre groups errno to the current value
		992	of errno (just like calling C<errno> without an error number). By default,
		993	no argument will be passed and errno is zero.
		994
		995	=item $grp->errno ([$errno])
		996
		997	Sets the group errno value to C<$errno>, or the current value of errno
		998	when the argument is missing.
		999
		1000	Every aio request has an associated errno value that is restored when
		1001	the callback is invoked. This method lets you change this value from its
		1002	default (0).
		1003
		1004	Calling C<result> will also set errno, so make sure you either set C<$!>
		1005	before the call to C<result>, or call c<errno> after it.
701		1006
702	=item feed $grp $callback->($grp)	1007	=item feed $grp $callback->($grp)
703
704	[VERY EXPERIMENTAL]
705		1008
706	Sets a feeder/generator on this group: every group can have an attached	1009	Sets a feeder/generator on this group: every group can have an attached
707	generator that generates requests if idle. The idea behind this is that,	1010	generator that generates requests if idle. The idea behind this is that,
708	although you could just queue as many requests as you want in a group,	1011	although you could just queue as many requests as you want in a group,
709	this might starve other requests for a potentially long time. For	1012	this might starve other requests for a potentially long time. For
…		…
746		1049
747	=back	1050	=back
748		1051
749	=head2 SUPPORT FUNCTIONS	1052	=head2 SUPPORT FUNCTIONS
750		1053
		1054	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
		1055
751	=over 4	1056	=over 4
752		1057
753	=item $fileno = IO::AIO::poll_fileno	1058	=item $fileno = IO::AIO::poll_fileno
754		1059
755	Return the I<request result pipe file descriptor>. This filehandle must be	1060	Return the I<request result pipe file descriptor>. This filehandle must be
…		…
759		1064
760	See C<poll_cb> for an example.	1065	See C<poll_cb> for an example.
761		1066
762	=item IO::AIO::poll_cb	1067	=item IO::AIO::poll_cb
763		1068
764	Process all outstanding events on the result pipe. You have to call this	1069	Process some outstanding events on the result pipe. You have to call this
765	regularly. Returns the number of events processed. Returns immediately	1070	regularly. Returns the number of events processed. Returns immediately
766	when no events are outstanding.	1071	when no events are outstanding. The amount of events processed depends on
		1072	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		1073
		1074	If not all requests were processed for whatever reason, the filehandle
		1075	will still be ready when C<poll_cb> returns.
767		1076
768	Example: Install an Event watcher that automatically calls	1077	Example: Install an Event watcher that automatically calls
769	IO::AIO::poll_cb with high priority:	1078	IO::AIO::poll_cb with high priority:
770		1079
771	Event->io (fd => IO::AIO::poll_fileno,	1080	Event->io (fd => IO::AIO::poll_fileno,
772	poll => 'r', async => 1,	1081	poll => 'r', async => 1,
773	cb => \&IO::AIO::poll_cb);	1082	cb => \&IO::AIO::poll_cb);
774		1083
		1084	=item IO::AIO::max_poll_reqs $nreqs
		1085
		1086	=item IO::AIO::max_poll_time $seconds
		1087
		1088	These set the maximum number of requests (default C<0>, meaning infinity)
		1089	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		1090	the maximum amount of time (default C<0>, meaning infinity) spent in
		1091	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		1092	of time C<poll_cb> is allowed to use).
		1093
		1094	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		1095	syscall per request processed, which is not normally a problem unless your
		1096	callbacks are really really fast or your OS is really really slow (I am
		1097	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		1098
		1099	Setting these is useful if you want to ensure some level of
		1100	interactiveness when perl is not fast enough to process all requests in
		1101	time.
		1102
		1103	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		1104
		1105	Example: Install an Event watcher that automatically calls
		1106	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		1107	program get the CPU sometimes even under high AIO load.
		1108
		1109	# try not to spend much more than 0.1s in poll_cb
		1110	IO::AIO::max_poll_time 0.1;
		1111
		1112	# use a low priority so other tasks have priority
		1113	Event->io (fd => IO::AIO::poll_fileno,
		1114	poll => 'r', nice => 1,
		1115	cb => &IO::AIO::poll_cb);
		1116
775	=item IO::AIO::poll_wait	1117	=item IO::AIO::poll_wait
776		1118
		1119	If there are any outstanding requests and none of them in the result
777	Wait till the result filehandle becomes ready for reading (simply does a	1120	phase, wait till the result filehandle becomes ready for reading (simply
778	C<select> on the filehandle. This is useful if you want to synchronously wait	1121	does a C<select> on the filehandle. This is useful if you want to
779	for some requests to finish).	1122	synchronously wait for some requests to finish).
780		1123
781	See C<nreqs> for an example.	1124	See C<nreqs> for an example.
782		1125
		1126	=item IO::AIO::poll
		1127
		1128	Waits until some requests have been handled.
		1129
		1130	Returns the number of requests processed, but is otherwise strictly
		1131	equivalent to:
		1132
		1133	IO::AIO::poll_wait, IO::AIO::poll_cb
		1134
783	=item IO::AIO::nreqs	1135	=item IO::AIO::flush
784		1136
785	Returns the number of requests currently outstanding (i.e. for which their	1137	Wait till all outstanding AIO requests have been handled.
786	callback has not been invoked yet).
787		1138
788	Example: wait till there are no outstanding requests anymore:	1139	Strictly equivalent to:
789		1140
790	IO::AIO::poll_wait, IO::AIO::poll_cb	1141	IO::AIO::poll_wait, IO::AIO::poll_cb
791	while IO::AIO::nreqs;	1142	while IO::AIO::nreqs;
792		1143
793	=item IO::AIO::flush	1144	=back
794		1145
795	Wait till all outstanding AIO requests have been handled.	1146	=head3 CONTROLLING THE NUMBER OF THREADS
796		1147
797	Strictly equivalent to:	1148	=over
798
799	IO::AIO::poll_wait, IO::AIO::poll_cb
800	while IO::AIO::nreqs;
801
802	=item IO::AIO::poll
803
804	Waits until some requests have been handled.
805
806	Strictly equivalent to:
807
808	IO::AIO::poll_wait, IO::AIO::poll_cb
809	if IO::AIO::nreqs;
810		1149
811	=item IO::AIO::min_parallel $nthreads	1150	=item IO::AIO::min_parallel $nthreads
812		1151
813	Set the minimum number of AIO threads to C<$nthreads>. The current	1152	Set the minimum number of AIO threads to C<$nthreads>. The current
814	default is C<8>, which means eight asynchronous operations can execute	1153	default is C<8>, which means eight asynchronous operations can execute
815	concurrently at any one time (the number of outstanding requests,	1154	concurrently at any one time (the number of outstanding requests,
816	however, is unlimited).	1155	however, is unlimited).
817		1156
818	IO::AIO starts threads only on demand, when an AIO request is queued and	1157	IO::AIO starts threads only on demand, when an AIO request is queued and
819	no free thread exists.	1158	no free thread exists. Please note that queueing up a hundred requests can
		1159	create demand for a hundred threads, even if it turns out that everything
		1160	is in the cache and could have been processed faster by a single thread.
820		1161
821	It is recommended to keep the number of threads relatively low, as some	1162	It is recommended to keep the number of threads relatively low, as some
822	Linux kernel versions will scale negatively with the number of threads	1163	Linux kernel versions will scale negatively with the number of threads
823	(higher parallelity => MUCH higher latency). With current Linux 2.6	1164	(higher parallelity => MUCH higher latency). With current Linux 2.6
824	versions, 4-32 threads should be fine.	1165	versions, 4-32 threads should be fine.
…		…
838	This module automatically runs C<max_parallel 0> at program end, to ensure	1179	This module automatically runs C<max_parallel 0> at program end, to ensure
839	that all threads are killed and that there are no outstanding requests.	1180	that all threads are killed and that there are no outstanding requests.
840		1181
841	Under normal circumstances you don't need to call this function.	1182	Under normal circumstances you don't need to call this function.
842		1183
		1184	=item IO::AIO::max_idle $nthreads
		1185
		1186	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1187	threads that did not get a request to process within 10 seconds). That
		1188	means if a thread becomes idle while C<$nthreads> other threads are also
		1189	idle, it will free its resources and exit.
		1190
		1191	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1192	to allow for extremely high load situations, but want to free resources
		1193	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1194
		1195	The default is probably ok in most situations, especially if thread
		1196	creation is fast. If thread creation is very slow on your system you might
		1197	want to use larger values.
		1198
843	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1199	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
844		1200
845	[DEPRECATED]	1201	This is a very bad function to use in interactive programs because it
		1202	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1203	use an C<aio_group> together with a feed callback.
846		1204
847	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1205	Sets the maximum number of outstanding requests to C<$nreqs>. If you
848	try to queue up more than this number of requests, the caller will block until	1206	to queue up more than this number of requests, the next call to the
849	some requests have been handled.	1207	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1208	function will block until the limit is no longer exceeded.
850		1209
851	The default is very large, so normally there is no practical limit. If you	1210	The default value is very large, so there is no practical limit on the
852	queue up many requests in a loop it often improves speed if you set	1211	number of outstanding requests.
853	this to a relatively low number, such as C<100>.
854		1212
855	This function does not work well together with C<aio_group>'s, and their	1213	You can still queue as many requests as you want. Therefore,
856	feeder interface is better suited to limiting concurrency, so do not use	1214	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
857	this function.	1215	as a stop gap to shield against fatal memory overflow (with large values).
858		1216
859	Under normal circumstances you don't need to call this function.	1217	=back
		1218
		1219	=head3 STATISTICAL INFORMATION
		1220
		1221	=over
		1222
		1223	=item IO::AIO::nreqs
		1224
		1225	Returns the number of requests currently in the ready, execute or pending
		1226	states (i.e. for which their callback has not been invoked yet).
		1227
		1228	Example: wait till there are no outstanding requests anymore:
		1229
		1230	IO::AIO::poll_wait, IO::AIO::poll_cb
		1231	while IO::AIO::nreqs;
		1232
		1233	=item IO::AIO::nready
		1234
		1235	Returns the number of requests currently in the ready state (not yet
		1236	executed).
		1237
		1238	=item IO::AIO::npending
		1239
		1240	Returns the number of requests currently in the pending state (executed,
		1241	but not yet processed by poll_cb).
860		1242
861	=back	1243	=back
862		1244
863	=cut	1245	=cut
864		1246
…		…
878	*$sym	1260	*$sym
879	}	1261	}
880		1262
881	min_parallel 8;	1263	min_parallel 8;
882		1264
883	END {	1265	END { flush }
884	max_parallel 0;
885	}
886		1266
887	1;	1267	1;
888		1268
889	=head2 FORK BEHAVIOUR	1269	=head2 FORK BEHAVIOUR
890		1270
891	This module should do "the right thing" when the process using it forks:	1271	This module should do "the right thing" when the process using it forks:
892		1272
893	Before the fork, IO::AIO enters a quiescent state where no requests	1273	Before the fork, IO::AIO enters a quiescent state where no requests
894	can be added in other threads and no results will be processed. After	1274	can be added in other threads and no results will be processed. After
895	the fork the parent simply leaves the quiescent state and continues	1275	the fork the parent simply leaves the quiescent state and continues
896	request/result processing, while the child clears the request/result	1276	request/result processing, while the child frees the request/result queue
897	queue (so the requests started before the fork will only be handled in	1277	(so that the requests started before the fork will only be handled in the
898	the parent). Threads will be started on demand until the limit ste in the	1278	parent). Threads will be started on demand until the limit set in the
899	parent process has been reached again.	1279	parent process has been reached again.
900		1280
901	In short: the parent will, after a short pause, continue as if fork had	1281	In short: the parent will, after a short pause, continue as if fork had
902	not been called, while the child will act as if IO::AIO has not been used	1282	not been called, while the child will act as if IO::AIO has not been used
903	yet.	1283	yet.
904		1284
905	=head2 MEMORY USAGE	1285	=head2 MEMORY USAGE
906		1286
		1287	Per-request usage:
		1288
907	Each aio request uses - depending on your architecture - around 128 bytes	1289	Each aio request uses - depending on your architecture - around 100-200
908	of memory. In addition, stat requests need a stat buffer (possibly a few	1290	bytes of memory. In addition, stat requests need a stat buffer (possibly
909	hundred bytes). Perl scalars and other data passed into aio requests will	1291	a few hundred bytes), readdir requires a result buffer and so on. Perl
910	also be locked.	1292	scalars and other data passed into aio requests will also be locked and
		1293	will consume memory till the request has entered the done state.
911		1294
912	This is now awfully much, so queuing lots of requests is not usually a	1295	This is now awfully much, so queuing lots of requests is not usually a
913	problem.	1296	problem.
914		1297
915	Each thread needs a stack area which is usually around 16k, sometimes much	1298	Per-thread usage:
916	larger, depending on the OS.	1299
		1300	In the execution phase, some aio requests require more memory for
		1301	temporary buffers, and each thread requires a stack and other data
		1302	structures (usually around 16k-128k, depending on the OS).
		1303
		1304	=head1 KNOWN BUGS
		1305
		1306	Known bugs will be fixed in the next release.
917		1307
918	=head1 SEE ALSO	1308	=head1 SEE ALSO
919		1309
920	L<Coro::AIO>.	1310	L<Coro::AIO>.
921		1311

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs. Revision 1.109 by root, Sun Jun 3 09:44:17 2007 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.109 by root, Sun Jun 3 09:44:17 2007 UTC