[ViewVC] Diff of: cvs/AnyEvent-Fork-RPC/RPC.pm

Comparing AnyEvent-Fork-RPC/RPC.pm (file contents):
Revision 1.15 by root, Thu Apr 18 13:15:23 2013 UTC vs.
Revision 1.36 by root, Sat Nov 30 17:41:46 2013 UTC

…		…
2		2
3	AnyEvent::Fork::RPC - simple RPC extension for AnyEvent::Fork	3	AnyEvent::Fork::RPC - simple RPC extension for AnyEvent::Fork
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
		7	use AnyEvent::Fork;
7	use AnyEvent::Fork::RPC;	8	use AnyEvent::Fork::RPC;
8	# use AnyEvent::Fork is not needed
9		9
10	my $rpc = AnyEvent::Fork	10	my $rpc = AnyEvent::Fork
11	->new	11	->new
12	->require ("MyModule")	12	->require ("MyModule")
13	->AnyEvent::Fork::RPC::run (	13	->AnyEvent::Fork::RPC::run (
14	"MyModule::server",	14	"MyModule::server",
15	);	15	);
16		16
		17	use AnyEvent;
		18
17	my $cv = AE::cv;	19	my $cv = AE::cv;
18		20
19	$rpc->(1, 2, 3, sub {	21	$rpc->(1, 2, 3, sub {
20	print "MyModule::server returned @_\n";	22	print "MyModule::server returned @_\n";
21	$cv->send;	23	$cv->send;
…		…
24	$cv->recv;	26	$cv->recv;
25		27
26	=head1 DESCRIPTION	28	=head1 DESCRIPTION
27		29
28	This module implements a simple RPC protocol and backend for processes	30	This module implements a simple RPC protocol and backend for processes
29	created via L<AnyEvent::Fork>, allowing you to call a function in the	31	created via L<AnyEvent::Fork> or L<AnyEvent::Fork::Remote>, allowing you
30	child process and receive its return values (up to 4GB serialised).	32	to call a function in the child process and receive its return values (up
		33	to 4GB serialised).
31		34
32	It implements two different backends: a synchronous one that works like a	35	It implements two different backends: a synchronous one that works like a
33	normal function call, and an asynchronous one that can run multiple jobs	36	normal function call, and an asynchronous one that can run multiple jobs
34	concurrently in the child, using AnyEvent.	37	concurrently in the child, using AnyEvent.
35		38
36	It also implements an asynchronous event mechanism from the child to the	39	It also implements an asynchronous event mechanism from the child to the
37	parent, that could be used for progress indications or other information.	40	parent, that could be used for progress indications or other information.
38
39	Loading this module also always loads L<AnyEvent::Fork>, so you can make a
40	separate C<use AnyEvent::Fork> if you wish, but you don't have to.
41		41
42	=head1 EXAMPLES	42	=head1 EXAMPLES
43		43
44	=head2 Example 1: Synchronous Backend	44	=head2 Example 1: Synchronous Backend
45		45
…		…
49	silly, but illustrates the use of events.	49	silly, but illustrates the use of events.
50		50
51	First the parent process:	51	First the parent process:
52		52
53	use AnyEvent;	53	use AnyEvent;
		54	use AnyEvent::Fork;
54	use AnyEvent::Fork::RPC;	55	use AnyEvent::Fork::RPC;
55		56
56	my $done = AE::cv;	57	my $done = AE::cv;
57		58
58	my $rpc = AnyEvent::Fork	59	my $rpc = AnyEvent::Fork
59	->new	60	->new
60	->require ("MyWorker")	61	->require ("MyWorker")
61	->AnyEvent::Fork::RPC::run ("MyWorker::run",	62	->AnyEvent::Fork::RPC::run ("MyWorker::run",
62	on_error => sub { warn "FATAL: $_[0]"; exit 1 },	63	on_error => sub { warn "ERROR: $_[0]"; exit 1 },
63	on_event => sub { warn "$_[0] requests handled\n" },	64	on_event => sub { warn "$_[0] requests handled\n" },
64	on_destroy => $done,	65	on_destroy => $done,
65	);	66	);
66		67
67	for my $id (1..6) {	68	for my $id (1..6) {
…		…
174	you really I<are> done.	175	you really I<are> done.
175		176
176	=head2 Example 2: Asynchronous Backend	177	=head2 Example 2: Asynchronous Backend
177		178
178	This example implements multiple count-downs in the child, using	179	This example implements multiple count-downs in the child, using
179	L<AnyEvent> timers. While this is a bit silly (one could use timers in te	180	L<AnyEvent> timers. While this is a bit silly (one could use timers in the
180	parent just as well), it illustrates the ability to use AnyEvent in the	181	parent just as well), it illustrates the ability to use AnyEvent in the
181	child and the fact that responses can arrive in a different order then the	182	child and the fact that responses can arrive in a different order then the
182	requests.	183	requests.
183		184
184	It also shows how to embed the actual child code into a C<__DATA__>	185	It also shows how to embed the actual child code into a C<__DATA__>
…		…
189	so silly anymore.	190	so silly anymore.
190		191
191	Without further ado, here is the code:	192	Without further ado, here is the code:
192		193
193	use AnyEvent;	194	use AnyEvent;
		195	use AnyEvent::Fork;
194	use AnyEvent::Fork::RPC;	196	use AnyEvent::Fork::RPC;
195		197
196	my $done = AE::cv;	198	my $done = AE::cv;
197		199
198	my $rpc = AnyEvent::Fork	200	my $rpc = AnyEvent::Fork
199	->new	201	->new
200	->require ("AnyEvent::Fork::RPC::Async")	202	->require ("AnyEvent::Fork::RPC::Async")
201	->eval (do { local $/; <DATA> })	203	->eval (do { local $/; <DATA> })
202	->AnyEvent::Fork::RPC::run ("run",	204	->AnyEvent::Fork::RPC::run ("run",
203	async => 1,	205	async => 1,
204	on_error => sub { warn "FATAL: $_[0]"; exit 1 },	206	on_error => sub { warn "ERROR: $_[0]"; exit 1 },
205	on_event => sub { print $_[0] },	207	on_event => sub { print $_[0] },
206	on_destroy => $done,	208	on_destroy => $done,
207	);	209	);
208		210
209	for my $count (3, 2, 1) {	211	for my $count (3, 2, 1) {
…		…
285		287
286	This concludes the async example. Since L<AnyEvent::Fork> does not	288	This concludes the async example. Since L<AnyEvent::Fork> does not
287	actually fork, you are free to use about any module in the child, not just	289	actually fork, you are free to use about any module in the child, not just
288	L<AnyEvent>, but also L<IO::AIO>, or L<Tk> for example.	290	L<AnyEvent>, but also L<IO::AIO>, or L<Tk> for example.
289		291
		292	=head2 Example 3: Asynchronous backend with Coro
		293
		294	With L<Coro> you can create a nice asynchronous backend implementation by
		295	defining an rpc server function that creates a new Coro thread for every
		296	request that calls a function "normally", i.e. the parameters from the
		297	parent process are passed to it, and any return values are returned to the
		298	parent process, e.g.:
		299
		300	package My::Arith;
		301
		302	sub add {
		303	return $_[0] + $_[1];
		304	}
		305
		306	sub mul {
		307	return $_[0] * $_[1];
		308	}
		309
		310	sub run {
		311	my ($done, $func, @arg) = @_;
		312
		313	Coro::async_pool {
		314	$done->($func->(@arg));
		315	};
		316	}
		317
		318	The C<run> function creates a new thread for every invocation, using the
		319	first argument as function name, and calls the C<$done> callback on it's
		320	return values. This makes it quite natural to define the C<add> and C<mul>
		321	functions to add or multiply two numbers and return the result.
		322
		323	Since this is the asynchronous backend, it's quite possible to define RPC
		324	function that do I/O or wait for external events - their execution will
		325	overlap as needed.
		326
		327	The above could be used like this:
		328
		329	my $rpc = AnyEvent::Fork
		330	->new
		331	->require ("MyWorker")
		332	->AnyEvent::Fork::RPC::run ("My::Arith::run",
		333	on_error => ..., on_event => ..., on_destroy => ...,
		334	);
		335
		336	$rpc->(add => 1, 3, Coro::rouse_cb); say Coro::rouse_wait;
		337	$rpc->(mul => 3, 2, Coro::rouse_cb); say Coro::rouse_wait;
		338
		339	The C<say>'s will print C<4> and C<6>.
		340
		341	=head2 Example 4: Forward AnyEvent::Log messages using C<on_event>
		342
		343	This partial example shows how to use the C<event> function to forward
		344	L<AnyEvent::Log> messages to the parent.
		345
		346	For this, the parent needs to provide a suitable C<on_event>:
		347
		348	->AnyEvent::Fork::RPC::run (
		349	on_event => sub {
		350	if ($_[0] eq "ae_log") {
		351	my (undef, $level, $message) = @_;
		352	AE::log $level, $message;
		353	} else {
		354	# other event types
		355	}
		356	},
		357	)
		358
		359	In the child, as early as possible, the following code should reconfigure
		360	L<AnyEvent::Log> to log via C<AnyEvent::Fork::RPC::event>:
		361
		362	$AnyEvent::Log::LOG->log_cb (sub {
		363	my ($timestamp, $orig_ctx, $level, $message) = @{+shift};
		364
		365	if (defined &AnyEvent::Fork::RPC::event) {
		366	AnyEvent::Fork::RPC::event (ae_log => $level, $message);
		367	} else {
		368	warn "[$$ before init] $message\n";
		369	}
		370	});
		371
		372	There is an important twist - the C<AnyEvent::Fork::RPC::event> function
		373	is only defined when the child is fully initialised. If you redirect the
		374	log messages in your C<init> function for example, then the C<event>
		375	function might not yet be available. This is why the log callback checks
		376	whether the fucntion is there using C<defined>, and only then uses it to
		377	log the message.
		378
290	=head1 PARENT PROCESS USAGE	379	=head1 PARENT PROCESS USAGE
291		380
292	This module exports nothing, and only implements a single function:	381	This module exports nothing, and only implements a single function:
293		382
294	=over 4	383	=over 4
…		…
301		390
302	use Errno ();	391	use Errno ();
303	use Guard ();	392	use Guard ();
304		393
305	use AnyEvent;	394	use AnyEvent;
306	use AnyEvent::Fork; # we don't actually depend on it, this is for convenience
307		395
308	our $VERSION = 0.1;	396	our $VERSION = 1.21;
309		397
310	=item my $rpc = AnyEvent::Fork::RPC::run $fork, $function, [key => value...]	398	=item my $rpc = AnyEvent::Fork::RPC::run $fork, $function, [key => value...]
311		399
312	The traditional way to call it. But it is way cooler to call it in the	400	The traditional way to call it. But it is way cooler to call it in the
313	following way:	401	following way:
…		…
333	Called on (fatal) errors, with a descriptive (hopefully) message. If	421	Called on (fatal) errors, with a descriptive (hopefully) message. If
334	this callback is not provided, but C<on_event> is, then the C<on_event>	422	this callback is not provided, but C<on_event> is, then the C<on_event>
335	callback is called with the first argument being the string C<error>,	423	callback is called with the first argument being the string C<error>,
336	followed by the error message.	424	followed by the error message.
337		425
338	If neither handler is provided it prints the error to STDERR and will	426	If neither handler is provided, then the error is reported with loglevel
339	start failing badly.	427	C<error> via C<AE::log>.
340		428
341	=item on_event => $cb->(...)	429	=item on_event => $cb->(...)
342		430
343	Called for every call to the C<AnyEvent::Fork::RPC::event> function in the	431	Called for every call to the C<AnyEvent::Fork::RPC::event> function in the
344	child, with the arguments of that function passed to the callback.	432	child, with the arguments of that function passed to the callback.
…		…
366	It is called very early - before the serialisers are created or the	454	It is called very early - before the serialisers are created or the
367	C<$function> name is resolved into a function reference, so it could be	455	C<$function> name is resolved into a function reference, so it could be
368	used to load any modules that provide the serialiser or function. It can	456	used to load any modules that provide the serialiser or function. It can
369	not, however, create events.	457	not, however, create events.
370		458
		459	=item done => $function (default C<CORE::exit>)
		460
		461	The function to call when the asynchronous backend detects an end of file
		462	condition when reading from the communications socket I<and> there are no
		463	outstanding requests. It's ignored by the synchronous backend.
		464
		465	By overriding this you can prolong the life of a RPC process after e.g.
		466	the parent has exited by running the event loop in the provided function
		467	(or simply calling it, for example, when your child process uses L<EV> you
		468	could provide L<EV::loop> as C<done> function).
		469
		470	Of course, in that case you are responsible for exiting at the appropriate
		471	time and not returning from
		472
371	=item async => $boolean (default: 0)	473	=item async => $boolean (default: 0)
372		474
373	The default server used in the child does all I/O blockingly, and only	475	The default server used in the child does all I/O blockingly, and only
374	allows a single RPC call to execute concurrently.	476	allows a single RPC call to execute concurrently.
375		477
…		…
392		494
393	All arguments, result data and event data have to be serialised to be	495	All arguments, result data and event data have to be serialised to be
394	transferred between the processes. For this, they have to be frozen and	496	transferred between the processes. For this, they have to be frozen and
395	thawed in both parent and child processes.	497	thawed in both parent and child processes.
396		498
397	By default, only octet strings can be passed between the processes, which	499	By default, only octet strings can be passed between the processes,
398	is reasonably fast and efficient and requires no extra modules.	500	which is reasonably fast and efficient and requires no extra modules
		501	(the C<AnyEvent::Fork::RPC> distribution does not provide these extra
		502	serialiser modules).
399		503
400	For more complicated use cases, you can provide your own freeze and thaw	504	For more complicated use cases, you can provide your own freeze and thaw
401	functions, by specifying a string with perl source code. It's supposed to	505	functions, by specifying a string with perl source code. It's supposed to
402	return two code references when evaluated: the first receives a list of	506	return two code references when evaluated: the first receives a list of
403	perl values and must return an octet string. The second receives the octet	507	perl values and must return an octet string. The second receives the octet
…		…
413	=over 4	517	=over 4
414		518
415	=item octet strings - C<$AnyEvent::Fork::RPC::STRING_SERIALISER>	519	=item octet strings - C<$AnyEvent::Fork::RPC::STRING_SERIALISER>
416		520
417	This serialiser concatenates length-prefixes octet strings, and is the	521	This serialiser concatenates length-prefixes octet strings, and is the
418	default.	522	default. That means you can only pass (and return) strings containing
		523	character codes 0-255.
419		524
420	Implementation:	525	Implementation:
421		526
422	(	527	(
423	sub { pack "(w/a)", @_ },	528	sub { pack "(w/a)", @_ },
424	sub { unpack "(w/a)", shift }	529	sub { unpack "(w/a)", shift }
		530	)
		531
		532	=item cbor - C<$AnyEvent::Fork::RPC::CBOR_XS_SERIALISER>
		533
		534	This serialiser creates CBOR::XS arrays - you have to make sure the
		535	L<CBOR::XS> module is installed for this serialiser to work. It can be
		536	beneficial for sharing when you preload the L<CBOR::XS> module in a template
		537	process.
		538
		539	L<CBOR::XS> is about as fast as the octet string serialiser, but supports
		540	complex data structures (similar to JSON) and is faster than any of the
		541	other serialisers. If you have the L<CBOR::XS> module available, it's the
		542	best choice.
		543
		544	The encoder enables C<allow_sharing> (so this serialisation method can
		545	encode cyclic and self-referencing data structures).
		546
		547	Implementation:
		548
		549	use CBOR::XS ();
		550	(
		551	sub { CBOR::XS::encode_cbor_sharing \@_ },
		552	sub { @{ CBOR::XS::decode_cbor shift } }
425	)	553	)
426		554
427	=item json - C<$AnyEvent::Fork::RPC::JSON_SERIALISER>	555	=item json - C<$AnyEvent::Fork::RPC::JSON_SERIALISER>
428		556
429	This serialiser creates JSON arrays - you have to make sure the L<JSON>	557	This serialiser creates JSON arrays - you have to make sure the L<JSON>
…		…
444		572
445	=item storable - C<$AnyEvent::Fork::RPC::STORABLE_SERIALISER>	573	=item storable - C<$AnyEvent::Fork::RPC::STORABLE_SERIALISER>
446		574
447	This serialiser uses L<Storable>, which means it has high chance of	575	This serialiser uses L<Storable>, which means it has high chance of
448	serialising just about anything you throw at it, at the cost of having	576	serialising just about anything you throw at it, at the cost of having
449	very high overhead per operation. It also comes with perl.	577	very high overhead per operation. It also comes with perl. It should be
		578	used when you need to serialise complex data structures.
450		579
451	Implementation:	580	Implementation:
452		581
453	use Storable ();	582	use Storable ();
454	(	583	(
455	sub { Storable::freeze \@_ },	584	sub { Storable::freeze \@_ },
456	sub { @{ Storable::thaw shift } }	585	sub { @{ Storable::thaw shift } }
457	)	586	)
458		587
		588	=item portable storable - C<$AnyEvent::Fork::RPC::NSTORABLE_SERIALISER>
		589
		590	This serialiser also uses L<Storable>, but uses it's "network" format
		591	to serialise data, which makes it possible to talk to different
		592	perl binaries (for example, when talking to a process created with
		593	L<AnyEvent::Fork::Remote>).
		594
		595	Implementation:
		596
		597	use Storable ();
		598	(
		599	sub { Storable::nfreeze \@_ },
		600	sub { @{ Storable::thaw shift } }
		601	)
		602
459	=back	603	=back
460		604
461	=back	605	=back
462		606
463	See the examples section earlier in this document for some actual	607	See the examples section earlier in this document for some actual
464	examples.	608	examples.
465		609
466	=cut	610	=cut
467		611
468	our $STRING_SERIALISER = '(sub { pack "(w/a)", @_ }, sub { unpack "(w/a)", shift })';	612	our $STRING_SERIALISER = '(sub { pack "(w/a)", @_ }, sub { unpack "(w/a)", shift })';
		613	our $CBOR_XS_SERIALISER = 'use CBOR::XS (); (sub { CBOR::XS::encode_cbor_sharing \@_ }, sub { @{ CBOR::XS::decode_cbor shift } })';
469	our $JSON_SERIALISER = 'use JSON (); (sub { JSON::encode_json \@_ }, sub { @{ JSON::decode_json shift } })';	614	our $JSON_SERIALISER = 'use JSON (); (sub { JSON::encode_json \@_ }, sub { @{ JSON::decode_json shift } })';
470	our $STORABLE_SERIALISER = 'use Storable (); (sub { Storable::freeze \@_ }, sub { @{ Storable::thaw shift } })';	615	our $STORABLE_SERIALISER = 'use Storable (); (sub { Storable::freeze \@_ }, sub { @{ Storable::thaw shift } })';
		616	our $NSTORABLE_SERIALISER = 'use Storable (); (sub { Storable::nfreeze \@_ }, sub { @{ Storable::thaw shift } })';
471		617
472	sub run {	618	sub run {
473	my ($self, $function, %arg) = @_;	619	my ($self, $function, %arg) = @_;
474		620
475	my $serialiser = delete $arg{serialiser} \|\| $STRING_SERIALISER;	621	my $serialiser = delete $arg{serialiser} \|\| $STRING_SERIALISER;
…		…
478	my $on_destroy = delete $arg{on_destroy};	624	my $on_destroy = delete $arg{on_destroy};
479		625
480	# default for on_error is to on_event, if specified	626	# default for on_error is to on_event, if specified
481	$on_error \|\|= $on_event	627	$on_error \|\|= $on_event
482	? sub { $on_event->(error => shift) }	628	? sub { $on_event->(error => shift) }
483	: sub { die "AnyEvent::Fork::RPC: uncaught error: $_[0].\n" };	629	: sub { AE::log die => "AnyEvent::Fork::RPC: uncaught error: $_[0]." };
484		630
485	# default for on_event is to raise an error	631	# default for on_event is to raise an error
486	$on_event \|\|= sub { $on_error->("event received, but no on_event handler") };	632	$on_event \|\|= sub { $on_error->("event received, but no on_event handler") };
487		633
488	my ($f, $t) = eval $serialiser; die $@ if $@;	634	my ($f, $t) = eval $serialiser; die $@ if $@;
…		…
509	};	655	};
510		656
511	my $module = "AnyEvent::Fork::RPC::" . ($arg{async} ? "Async" : "Sync");	657	my $module = "AnyEvent::Fork::RPC::" . ($arg{async} ? "Async" : "Sync");
512		658
513	$self->require ($module)	659	$self->require ($module)
514	->send_arg ($function, $arg{init}, $serialiser)	660	->send_arg ($function, $arg{init}, $serialiser, $arg{done} \|\| "$module\::do_exit")
515	->run ("$module\::run", sub {	661	->run ("$module\::run", sub {
516	$fh = shift;	662	$fh = shift;
517		663
518	my ($id, $len);	664	my ($id, $len);
519	$rw = AE::io $fh, 0, sub {	665	$rw = AE::io $fh, 0, sub {
520	$rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf;	666	$rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf;
521	$len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf;	667	$len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf;
522		668
523	if ($len) {	669	if ($len) {
524	while (8 <= length $rbuf) {	670	while (8 <= length $rbuf) {
525	($id, $len) = unpack "LL", $rbuf;	671	($id, $len) = unpack "NN", $rbuf;
526	8 + $len <= length $rbuf	672	8 + $len <= length $rbuf
527	or last;	673	or last;
528		674
529	my @r = $t->(substr $rbuf, 8, $len);	675	my @r = $t->(substr $rbuf, 8, $len);
530	substr $rbuf, 0, 8 + $len, "";	676	substr $rbuf, 0, 8 + $len, "";
…		…
546	undef $rw; undef $ww; # it ends here	692	undef $rw; undef $ww; # it ends here
547		693
548	if (@rcb \|\| %rcb) {	694	if (@rcb \|\| %rcb) {
549	$on_error->("unexpected eof");	695	$on_error->("unexpected eof");
550	} else {	696	} else {
551	$on_destroy->();	697	$on_destroy->()
		698	if $on_destroy;
552	}	699	}
553	} elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {	700	} elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {
554	undef $rw; undef $ww; # it ends here	701	undef $rw; undef $ww; # it ends here
555	$on_error->("read: $!");	702	$on_error->("read: $!");
556	}	703	}
…		…
559	$ww \|\|= AE::io $fh, 1, $wcb;	706	$ww \|\|= AE::io $fh, 1, $wcb;
560	});	707	});
561		708
562	my $guard = Guard::guard {	709	my $guard = Guard::guard {
563	$shutdown = 1;	710	$shutdown = 1;
564	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	711
		712	shutdown $fh, 1 if $fh && !$ww;
565	};	713	};
566		714
567	my $id;	715	my $id;
568		716
569	$arg{async}	717	$arg{async}
…		…
571	$id = ($id == 0xffffffff ? 0 : $id) + 1;	719	$id = ($id == 0xffffffff ? 0 : $id) + 1;
572	$id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops	720	$id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops
573		721
574	$rcb{$id} = pop;	722	$rcb{$id} = pop;
575		723
576	$guard; # keep it alive	724	$guard if 0; # keep it alive
577		725
578	$wbuf .= pack "LL/a*", $id, &$f;	726	$wbuf .= pack "NN/a*", $id, &$f;
579	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	727	$ww \|\|= $fh && AE::io $fh, 1, $wcb;
580	}	728	}
581	: sub {	729	: sub {
582	push @rcb, pop;	730	push @rcb, pop;
583		731
584	$guard; # keep it alive	732	$guard; # keep it alive
585		733
586	$wbuf .= pack "L/a*", &$f;	734	$wbuf .= pack "N/a*", &$f;
587	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	735	$ww \|\|= $fh && AE::io $fh, 1, $wcb;
588	}	736	}
589	}	737	}
590		738
591	=item $rpc->(..., $cb->(...))	739	=item $rpc->(..., $cb->(...))
…		…
630	child process to the parent, except that there is no notion of return	778	child process to the parent, except that there is no notion of return
631	values.	779	values.
632		780
633	See the examples section earlier in this document for some actual	781	See the examples section earlier in this document for some actual
634	examples.	782	examples.
		783
		784	=back
		785
		786	=head2 PROCESS EXIT
		787
		788	If and when the child process exits depends on the backend and
		789	configuration. Apart from explicit exits (e.g. by calling C<exit>) or
		790	runtime conditions (uncaught exceptions, signals etc.), the backends exit
		791	under these conditions:
		792
		793	=over 4
		794
		795	=item Synchronous Backend
		796
		797	The synchronous backend is very simple: when the process waits for another
		798	request to arrive and the writing side (usually in the parent) is closed,
		799	it will exit normally, i.e. as if your main program reached the end of the
		800	file.
		801
		802	That means that if your parent process exits, the RPC process will usually
		803	exit as well, either because it is idle anyway, or because it executes a
		804	request. In the latter case, you will likely get an error when the RPc
		805	process tries to send the results to the parent (because agruably, you
		806	shouldn't exit your parent while there are still outstanding requests).
		807
		808	The process is usually quiescent when it happens, so it should rarely be a
		809	problem, and C<END> handlers can be used to clean up.
		810
		811	=item Asynchronous Backend
		812
		813	For the asynchronous backend, things are more complicated: Whenever it
		814	listens for another request by the parent, it might detect that the socket
		815	was closed (e.g. because the parent exited). It will sotp listening for
		816	new requests and instead try to write out any remaining data (if any) or
		817	simply check whether the socket can be written to. After this, the RPC
		818	process is effectively done - no new requests are incoming, no outstanding
		819	request data can be written back.
		820
		821	Since chances are high that there are event watchers that the RPC server
		822	knows nothing about (why else would one use the async backend if not for
		823	the ability to register watchers?), the event loop would often happily
		824	continue.
		825
		826	This is why the asynchronous backend explicitly calls C<CORE::exit> when
		827	it is done (under other circumstances, such as when there is an I/O error
		828	and there is outstanding data to write, it will log a fatal message via
		829	L<AnyEvent::Log>, also causing the program to exit).
		830
		831	You can override this by specifying a function name to call via the C<done>
		832	parameter instead.
635		833
636	=back	834	=back
637		835
638	=head1 ADVANCED TOPICS	836	=head1 ADVANCED TOPICS
639		837
…		…
722	half it has passed earlier.	920	half it has passed earlier.
723		921
724	Here is some (untested) pseudocode to that effect:	922	Here is some (untested) pseudocode to that effect:
725		923
726	use AnyEvent::Util;	924	use AnyEvent::Util;
		925	use AnyEvent::Fork;
727	use AnyEvent::Fork::RPC;	926	use AnyEvent::Fork::RPC;
728	use IO::FDPass;	927	use IO::FDPass;
729		928
730	my ($s1, $s2) = AnyEvent::Util::portable_socketpair;	929	my ($s1, $s2) = AnyEvent::Util::portable_socketpair;
731		930
…		…
767		966
768	Of course, this might be blocking if you pass a lot of file descriptors,	967	Of course, this might be blocking if you pass a lot of file descriptors,
769	so you might want to look into L<AnyEvent::FDpasser> which can handle the	968	so you might want to look into L<AnyEvent::FDpasser> which can handle the
770	gory details.	969	gory details.
771		970
		971	=head1 EXCEPTIONS
		972
		973	There are no provisions whatsoever for catching exceptions at this time -
		974	in the child, exeptions might kill the process, causing calls to be lost
		975	and the parent encountering a fatal error. In the parent, exceptions in
		976	the result callback will not be caught and cause undefined behaviour.
		977
772	=head1 SEE ALSO	978	=head1 SEE ALSO
773		979
774	L<AnyEvent::Fork> (to create the processes in the first place),	980	L<AnyEvent::Fork>, to create the processes in the first place.
		981
		982	L<AnyEvent::Fork::Remote>, likewise, but helpful for remote processes.
		983
775	L<AnyEvent::Fork::Pool> (to manage whole pools of processes).	984	L<AnyEvent::Fork::Pool>, to manage whole pools of processes.
776		985
777	=head1 AUTHOR AND CONTACT INFORMATION	986	=head1 AUTHOR AND CONTACT INFORMATION
778		987
779	Marc Lehmann <schmorp@schmorp.de>	988	Marc Lehmann <schmorp@schmorp.de>
780	http://software.schmorp.de/pkg/AnyEvent-Fork-RPC	989	http://software.schmorp.de/pkg/AnyEvent-Fork-RPC

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Comparing AnyEvent-Fork-RPC/RPC.pm (file contents): Revision 1.15 by root, Thu Apr 18 13:15:23 2013 UTC vs. Revision 1.36 by root, Sat Nov 30 17:41:46 2013 UTC

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Comparing AnyEvent-Fork-RPC/RPC.pm (file contents):
Revision 1.15 by root, Thu Apr 18 13:15:23 2013 UTC vs.
Revision 1.36 by root, Sat Nov 30 17:41:46 2013 UTC