[ViewVC] Diff of: cvs/cvsroot/Async-Interrupt/Interrupt.pm

Comparing cvsroot/Async-Interrupt/Interrupt.pm (file contents):
Revision 1.10 by root, Sun Jul 12 23:03:36 2009 UTC vs.
Revision 1.17 by root, Tue Jul 28 01:19:44 2009 UTC

…		…
53		53
54	For example the deliantra game server uses a variant of this technique	54	For example the deliantra game server uses a variant of this technique
55	to interrupt background processes regularly to send map updates to game	55	to interrupt background processes regularly to send map updates to game
56	clients.	56	clients.
57		57
		58	Or L<EV::Loop::Async> uses an interrupt object to wake up perl when new
		59	events have arrived.
		60
58	L<IO::AIO> and L<BDB> could also use this to speed up result reporting.	61	L<IO::AIO> and L<BDB> could also use this to speed up result reporting.
59		62
60	=item Speedy event loop invocation	63	=item Speedy event loop invocation
61		64
62	One could use this module e.g. in L<Coro> to interrupt a running coro-thread	65	One could use this module e.g. in L<Coro> to interrupt a running coro-thread
…		…
88	I<running> interpreter, there is optional support for signalling a pipe	91	I<running> interpreter, there is optional support for signalling a pipe
89	- that means you can also wait for the pipe to become readable (e.g. via	92	- that means you can also wait for the pipe to become readable (e.g. via
90	L<EV> or L<AnyEvent>). This, of course, incurs the overhead of a C<read>	93	L<EV> or L<AnyEvent>). This, of course, incurs the overhead of a C<read>
91	and C<write> syscall.	94	and C<write> syscall.
92		95
		96	=head1 THE Async::Interrupt CLASS
		97
93	=over 4	98	=over 4
94		99
95	=cut	100	=cut
96		101
97	package Async::Interrupt;	102	package Async::Interrupt;
98		103
99	use common::sense;	104	use common::sense;
100		105
101	BEGIN {	106	BEGIN {
		107	# the next line forces initialisation of internal
		108	# signal handling # variables
		109	$SIG{KILL} = sub { };
		110
102	our $VERSION = '0.041';	111	our $VERSION = '0.6';
103		112
104	require XSLoader;	113	require XSLoader;
105	XSLoader::load Async::Interrupt::, $VERSION;	114	XSLoader::load ("Async::Interrupt", $VERSION);
106	}	115	}
107		116
108	our $DIED = sub { warn "$@" };	117	our $DIED = sub { warn "$@" };
109		118
110	=item $async = new Async::Interrupt key => value...	119	=item $async = new Async::Interrupt key => value...
…		…
153	might use (the exception is C<errno>, which is saved and restored by	162	might use (the exception is C<errno>, which is saved and restored by
154	Async::Interrupt). The callback itself runs as part of the perl context,	163	Async::Interrupt). The callback itself runs as part of the perl context,
155	so you can call any perl functions and modify any perl data structures (in	164	so you can call any perl functions and modify any perl data structures (in
156	which case the requirements set out for C<cb> apply as well).	165	which case the requirements set out for C<cb> apply as well).
157		166
		167	=item var => $scalar_ref
		168
		169	When specified, then the given argument must be a reference to a
		170	scalar. The scalar will be set to C<0> initially. Signalling the interrupt
		171	object will set it to the passed value, handling the interrupt will reset
		172	it to C<0> again.
		173
		174	Note that the only thing you are legally allowed to do is to is to check
		175	the variable in a boolean or integer context (e.g. comparing it with a
		176	string, or printing it, will I<destroy> it and might cause your program to
		177	crash or worse).
		178
158	=item signal => $signame_or_value	179	=item signal => $signame_or_value
159		180
160	When this parameter is specified, then the Async::Interrupt will hook the	181	When this parameter is specified, then the Async::Interrupt will hook the
161	given signal, that is, it will effectively call C<< ->signal (0) >> each time	182	given signal, that is, it will effectively call C<< ->signal (0) >> each time
162	the given signal is caught by the process.	183	the given signal is caught by the process.
…		…
171	be written to it, and before the callback is being invoked, it will be	192	be written to it, and before the callback is being invoked, it will be
172	read again. Due to races, it is unlikely but possible that multiple octets	193	read again. Due to races, it is unlikely but possible that multiple octets
173	are written. It is required that the file handles are both in nonblocking	194	are written. It is required that the file handles are both in nonblocking
174	mode.	195	mode.
175		196
176	You can get a portable pipe and set non-blocking mode portably by using
177	e.g. L<AnyEvent::Util> from the L<AnyEvent> distribution.
178
179	It is also possible to pass in a linux eventfd as both read and write
180	handle (which is faster than a pipe).
181
182	The object will keep a reference to the file handles.	197	The object will keep a reference to the file handles.
183		198
184	This can be used to ensure that async notifications will interrupt event	199	This can be used to ensure that async notifications will interrupt event
185	frameworks as well.	200	frameworks as well.
186		201
		202	Note that C<Async::Interrupt> will create a suitable signal fd
		203	automatically when your program requests one, so you don't have to specify
		204	this argument when all you want is an extra file descriptor to watch.
		205
		206	If you want to share a single event pipe between multiple Async::Interrupt
		207	objects, you can use the C<Async::Interrupt::EventPipe> class to manage
		208	those.
		209
187	=back	210	=back
188		211
189	=cut	212	=cut
190		213
191	sub new {	214	sub new {
192	my ($class, %arg) = @_;	215	my ($class, %arg) = @_;
193		216
194	bless \(_alloc $arg{cb}, @{$arg{c_cb}}[0,1], @{$arg{pipe}}[0,1], $arg{signal}), $class	217	bless \(_alloc $arg{cb}, @{$arg{c_cb}}[0,1], @{$arg{pipe}}[0,1], $arg{signal}, $arg{var}), $class
195	}	218	}
196		219
197	=item ($signal_func, $signal_arg) = $async->signal_func	220	=item ($signal_func, $signal_arg) = $async->signal_func
198		221
199	Returns the address of a function to call asynchronously. The function has	222	Returns the address of a function to call asynchronously. The function
200	the following prototype and needs to be passed the specified C<$c_arg>,	223	has the following prototype and needs to be passed the specified
201	which is a C<void *> cast to C<IV>:	224	C<$signal_arg>, which is a C<void *> cast to C<IV>:
202		225
203	void (signal_func) (void signal_arg, int value)	226	void (signal_func) (void signal_arg, int value)
204		227
205	An example call would look like:	228	An example call would look like:
206		229
207	signal_func (signal_arg, 0);	230	signal_func (signal_arg, 0);
208		231
209	The function is safe to call from within signal and thread contexts, at	232	The function is safe to call from within signal and thread contexts, at
210	any time. The specified C<value> is passed to both C and Perl callback.	233	any time. The specified C<value> is passed to both C and Perl callback.
211		234
212	C<$value> must be in the valid range for a C<sig_atomic_t> (0..127 is	235	C<$value> must be in the valid range for a C<sig_atomic_t>, except C<0>
213	portable).	236	(1..127 is portable).
214		237
215	If the function is called while the Async::Interrupt object is already	238	If the function is called while the Async::Interrupt object is already
216	signaled but before the callbacks are being executed, then the stored	239	signaled but before the callbacks are being executed, then the stored
217	C<value> is either the old or the new one. Due to the asynchronous	240	C<value> is either the old or the new one. Due to the asynchronous
218	nature of the code, the C<value> can even be passed to two consecutive	241	nature of the code, the C<value> can even be passed to two consecutive
219	invocations of the callback.	242	invocations of the callback.
220		243
		244	=item $address = $async->c_var
		245
		246	Returns the address (cast to IV) of an C<IV> variable. The variable is set
		247	to C<0> initially and gets set to the passed value whenever the object
		248	gets signalled, and reset to C<0> once the interrupt has been handled.
		249
		250	Note that it is often beneficial to just call C<PERL_ASYNC_CHECK ()> to
		251	handle any interrupts.
		252
		253	Example: call some XS function to store the address, then show C code
		254	waiting for it.
		255
		256	my_xs_func $async->c_var;
		257
		258	static IV *valuep;
		259
		260	void
		261	my_xs_func (void *addr)
		262	CODE:
		263	valuep = (IV *)addr;
		264
		265	// code in a loop, waiting
		266	while (!*valuep)
		267	; // do something
		268
221	=item $async->signal ($value=0)	269	=item $async->signal ($value=1)
222		270
223	This signals the given async object from Perl code. Semi-obviously, this	271	This signals the given async object from Perl code. Semi-obviously, this
224	will instantly trigger the callback invocation.	272	will instantly trigger the callback invocation (it does not, as the name
		273	might imply, do anything with POSIX signals).
225		274
226	C<$value> must be in the valid range for a C<sig_atomic_t> (0..127 is	275	C<$value> must be in the valid range for a C<sig_atomic_t>, except C<0>
227	portable).	276	(1..127 is portable).
		277
		278	=item $async->signal_hysteresis ($enable)
		279
		280	Enables or disables signal hysteresis (default: disabled). If a POSIX
		281	signal is used as a signal source for the interrupt object, then enabling
		282	signal hysteresis causes Async::Interrupt to reset the signal action to
		283	C<SIG_IGN> in the signal handler and restore it just before handling the
		284	interruption.
		285
		286	When you expect a lot of signals (e.g. when using SIGIO), then enabling
		287	signal hysteresis can reduce the number of handler invocations
		288	considerably, at the cost of two extra syscalls.
		289
		290	Note that setting the signal to C<SIG_IGN> can have unintended side
		291	effects when you fork and exec other programs, as often they do nto expect
		292	signals to be ignored by default.
228		293
229	=item $async->block	294	=item $async->block
230		295
231	=item $async->unblock	296	=item $async->unblock
232		297
…		…
247	This call C<< $async->block >> and installs a handler that is called when	312	This call C<< $async->block >> and installs a handler that is called when
248	the current scope is exited (via an exception, by canceling the Coro	313	the current scope is exited (via an exception, by canceling the Coro
249	thread, by calling last/goto etc.).	314	thread, by calling last/goto etc.).
250		315
251	This is the recommended (and fastest) way to implement critical sections.	316	This is the recommended (and fastest) way to implement critical sections.
		317
		318	=item ($block_func, $block_arg) = $async->scope_block_func
		319
		320	Returns the address of a function that implements the C<scope_block>
		321	functionality.
		322
		323	It has the following prototype and needs to be passed the specified
		324	C<$block_arg>, which is a C<void *> cast to C<IV>:
		325
		326	void (block_func) (void block_arg)
		327
		328	An example call would look like:
		329
		330	block_func (block_arg);
		331
		332	The function is safe to call only from within the toplevel of a perl XS
		333	function and will call C<LEAVE> and C<ENTER> (in this order!).
252		334
253	=item $async->pipe_enable	335	=item $async->pipe_enable
254		336
255	=item $async->pipe_disable	337	=item $async->pipe_disable
256		338
…		…
258	enabled). Writing to a pipe is relatively expensive, so it can be disabled	340	enabled). Writing to a pipe is relatively expensive, so it can be disabled
259	when you know you are not waiting for it (for example, with L<EV> you	341	when you know you are not waiting for it (for example, with L<EV> you
260	could disable the pipe in a check watcher, and enable it in a prepare	342	could disable the pipe in a check watcher, and enable it in a prepare
261	watcher).	343	watcher).
262		344
263	Note that when C<fd_disable> is in effect, no attempt to read from the	345	Note that currently, while C<pipe_disable> is in effect, no attempt to
264	pipe will be done.	346	read from the pipe will be done when handling events. This might change as
		347	soon as I realize why this is a mistake.
		348
		349	=item $fileno = $async->pipe_fileno
		350
		351	Returns the reading side of the signalling pipe. If no signalling pipe is
		352	currently attached to the object, it will dynamically create one.
		353
		354	Note that the only valid oepration on this file descriptor is to wait
		355	until it is readable. The fd might belong currently to a pipe, a tcp
		356	socket, or an eventfd, depending on the platform, and is guaranteed to be
		357	C<select>able.
		358
		359	=item $async->pipe_autodrain ($enable)
		360
		361	Enables (C<1>) or disables (C<0>) automatic draining of the pipe (default:
		362	enabled). When automatic draining is enabled, then Async::Interrupt will
		363	automatically clear the pipe. Otherwise the user is responsible for this
		364	draining.
		365
		366	This is useful when you want to share one pipe among many Async::Interrupt
		367	objects.
		368
		369	=item $async->post_fork
		370
		371	The object will not normally be usable after a fork (as the pipe fd is
		372	shared between processes). Calling this method after a fork in the child
		373	ensures that the object will work as expected again. It only needs to be
		374	called when the async object is used in the child.
		375
		376	This only works when the pipe was created by Async::Interrupt.
		377
		378	Async::Interrupt ensures that the reading file descriptor does not change
		379	it's value.
		380
		381	=back
		382
		383	=head1 THE Async::Interrupt::EventPipe CLASS
		384
		385	Pipes are the predominent utility to make asynchronous signals
		386	synchronous. However, pipes are hard to come by: they don't exist on the
		387	broken windows platform, and on GNU/Linux systems, you might want to use
		388	an C<eventfd> instead.
		389
		390	This class creates selectable event pipes in a portable fashion: on
		391	windows, it will try to create a tcp socket pair, on GNU/Linux, it will
		392	try to create an eventfd and everywhere else it will try to use a normal
		393	pipe.
		394
		395	=over 4
		396
		397	=item $epipe = new Async::Interrupt::EventPipe
		398
		399	This creates and returns an eventpipe object. This object is simply a
		400	blessed array reference:
		401
		402	=item ($r_fd, $w_fd) = $epipe->filenos
		403
		404	Returns the read-side file descriptor and the write-side file descriptor.
		405
		406	Example: pass an eventpipe object as pipe to the Async::Interrupt
		407	constructor, and create an AnyEvent watcher for the read side.
		408
		409	my $epipe = new Async::Interrupt::EventPipe;
		410	my $asy = new Async::Interrupt pipe => [$epipe->filenos];
		411	my $iow = AnyEvent->io (fh => $epipe->fileno, poll => 'r', cb => sub { });
		412
		413	=item $r_fd = $epipe->fileno
		414
		415	Return only the reading/listening side.
		416
		417	=item $epipe->signal
		418
		419	Write something to the pipe, in a portable fashion.
		420
		421	=item $epipe->drain
		422
		423	Drain (empty) the pipe.
		424
		425	=item $epipe->renew
		426
		427	Recreates the pipe (useful after a fork). The reading side will not change
		428	it's file descriptor number, but the writing side might.
		429
		430	=back
265		431
266	=cut	432	=cut
267		433
268	1;	434	1;
269
270	=back
271		435
272	=head1 EXAMPLE	436	=head1 EXAMPLE
273		437
274	There really should be a complete C/XS example. Bug me about it. Better	438	There really should be a complete C/XS example. Bug me about it. Better
275	yet, create one.	439	yet, create one.
…		…
283	then intercepts the interpreter handling it. This makes normal signal	447	then intercepts the interpreter handling it. This makes normal signal
284	handling slower (probably unmeasurably, though), but has the advantage	448	handling slower (probably unmeasurably, though), but has the advantage
285	of not requiring a special runops function, nor slowing down normal perl	449	of not requiring a special runops function, nor slowing down normal perl
286	execution a bit.	450	execution a bit.
287		451
288	It assumes that C<sig_atomic_t> and C<int> are both async-safe to modify	452	It assumes that C<sig_atomic_t>, C<int> and C<IV> are all async-safe to
289	(C<sig_atomic_> is used by this module, and perl itself uses C<int>, so we	453	modify.
290	can assume that this is quite portable, at least w.r.t. signals).
291		454
292	=head1 AUTHOR	455	=head1 AUTHOR
293		456
294	Marc Lehmann <schmorp@schmorp.de>	457	Marc Lehmann <schmorp@schmorp.de>
295	http://home.schmorp.de/	458	http://home.schmorp.de/

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Comparing cvsroot/Async-Interrupt/Interrupt.pm (file contents): Revision 1.10 by root, Sun Jul 12 23:03:36 2009 UTC vs. Revision 1.17 by root, Tue Jul 28 01:19:44 2009 UTC

Diff Legend

Comparing cvsroot/Async-Interrupt/Interrupt.pm (file contents):
Revision 1.10 by root, Sun Jul 12 23:03:36 2009 UTC vs.
Revision 1.17 by root, Tue Jul 28 01:19:44 2009 UTC