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

Comparing AnyEvent-Fork-RPC/RPC.pm (file contents):
Revision 1.12 by root, Thu Apr 18 10:40:34 2013 UTC vs.
Revision 1.33 by root, Tue Oct 15 09:15:59 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) {
…		…
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 => $boolean (default: 0)
372		474
373	The default server used in the child does all I/O blockingly, and only	475	The default server used in the child does all I/O blockingly, and only
374	allows a single RPC call to execute concurrently.	476	allows a single RPC call to execute concurrently.
375		477
376	Setting C<async> to a true value switches to another implementation that	478	Setting C<async> to a true value switches to another implementation that
377	uses L<AnyEvent> in the child and allows multiple concurrent RPC calls.	479	uses L<AnyEvent> in the child and allows multiple concurrent RPC calls (it
		480	does not support recursion in the event loop however, blocking condvar
		481	calls will fail).
378		482
379	The actual API in the child is documented in the section that describes	483	The actual API in the child is documented in the section that describes
380	the calling semantics of the returned C<$rpc> function.	484	the calling semantics of the returned C<$rpc> function.
381		485
382	If you want to pre-load the actual back-end modules to enable memory	486	If you want to pre-load the actual back-end modules to enable memory
…		…
384	synchronous, and C<AnyEvent::Fork::RPC::Async> for asynchronous mode.	488	synchronous, and C<AnyEvent::Fork::RPC::Async> for asynchronous mode.
385		489
386	If you use a template process and want to fork both sync and async	490	If you use a template process and want to fork both sync and async
387	children, then it is permissible to load both modules.	491	children, then it is permissible to load both modules.
388		492
389	=item serialiser => $string (default: '(sub { pack "(w/a)", @_ }, sub { unpack "(w/a)", shift })')	493	=item serialiser => $string (default: $AnyEvent::Fork::RPC::STRING_SERIALISER)
390		494
391	All arguments, result data and event data have to be serialised to be	495	All arguments, result data and event data have to be serialised to be
392	transferred between the processes. For this, they have to be frozen and	496	transferred between the processes. For this, they have to be frozen and
393	thawed in both parent and child processes.	497	thawed in both parent and child processes.
394		498
395	By default, only octet strings can be passed between the processes, which	499	By default, only octet strings can be passed between the processes, which
396	is reasonably fast and efficient.	500	is reasonably fast and efficient and requires no extra modules.
397		501
398	For more complicated use cases, you can provide your own freeze and thaw	502	For more complicated use cases, you can provide your own freeze and thaw
399	functions, by specifying a string with perl source code. It's supposed to	503	functions, by specifying a string with perl source code. It's supposed to
400	return two code references when evaluated: the first receives a list of	504	return two code references when evaluated: the first receives a list of
401	perl values and must return an octet string. The second receives the octet	505	perl values and must return an octet string. The second receives the octet
…		…
403		507
404	If you need an external module for serialisation, then you can either	508	If you need an external module for serialisation, then you can either
405	pre-load it into your L<AnyEvent::Fork> process, or you can add a C<use>	509	pre-load it into your L<AnyEvent::Fork> process, or you can add a C<use>
406	or C<require> statement into the serialiser string. Or both.	510	or C<require> statement into the serialiser string. Or both.
407		511
		512	Here are some examples - some of them are also available as global
		513	variables that make them easier to use.
		514
		515	=over 4
		516
		517	=item octet strings - C<$AnyEvent::Fork::RPC::STRING_SERIALISER>
		518
		519	This serialiser concatenates length-prefixes octet strings, and is the
		520	default. That means you can only pass (and return) strings containing
		521	character codes 0-255.
		522
		523	Implementation:
		524
		525	(
		526	sub { pack "(w/a)", @_ },
		527	sub { unpack "(w/a)", shift }
		528	)
		529
		530	=item json - C<$AnyEvent::Fork::RPC::JSON_SERIALISER>
		531
		532	This serialiser creates JSON arrays - you have to make sure the L<JSON>
		533	module is installed for this serialiser to work. It can be beneficial for
		534	sharing when you preload the L<JSON> module in a template process.
		535
		536	L<JSON> (with L<JSON::XS> installed) is slower than the octet string
		537	serialiser, but usually much faster than L<Storable>, unless big chunks of
		538	binary data need to be transferred.
		539
		540	Implementation:
		541
		542	use JSON ();
		543	(
		544	sub { JSON::encode_json \@_ },
		545	sub { @{ JSON::decode_json shift } }
		546	)
		547
		548	=item storable - C<$AnyEvent::Fork::RPC::STORABLE_SERIALISER>
		549
		550	This serialiser uses L<Storable>, which means it has high chance of
		551	serialising just about anything you throw at it, at the cost of having
		552	very high overhead per operation. It also comes with perl. It should be
		553	used when you need to serialise complex data structures.
		554
		555	Implementation:
		556
		557	use Storable ();
		558	(
		559	sub { Storable::freeze \@_ },
		560	sub { @{ Storable::thaw shift } }
		561	)
		562
		563	=item portable storable - C<$AnyEvent::Fork::RPC::NSTORABLE_SERIALISER>
		564
		565	This serialiser also uses L<Storable>, but uses it's "network" format
		566	to serialise data, which makes it possible to talk to different
		567	perl binaries (for example, when talking to a process created with
		568	L<AnyEvent::Fork::Remote>).
		569
		570	Implementation:
		571
		572	use Storable ();
		573	(
		574	sub { Storable::nfreeze \@_ },
		575	sub { @{ Storable::thaw shift } }
		576	)
		577
		578	=back
		579
408	=back	580	=back
409		581
410	See the examples section earlier in this document for some actual	582	See the examples section earlier in this document for some actual
411	examples.	583	examples.
412		584
413	=cut	585	=cut
414		586
415	our $STRING_SERIALISER = '(sub { pack "(w/a)", @_ }, sub { unpack "(w/a)", shift })';	587	our $STRING_SERIALISER = '(sub { pack "(w/a)", @_ }, sub { unpack "(w/a)", shift })';
		588	our $JSON_SERIALISER = 'use JSON (); (sub { JSON::encode_json \@_ }, sub { @{ JSON::decode_json shift } })';
		589	our $STORABLE_SERIALISER = 'use Storable (); (sub { Storable::freeze \@_ }, sub { @{ Storable::thaw shift } })';
		590	our $NSTORABLE_SERIALISER = 'use Storable (); (sub { Storable::nfreeze \@_ }, sub { @{ Storable::thaw shift } })';
416		591
417	sub run {	592	sub run {
418	my ($self, $function, %arg) = @_;	593	my ($self, $function, %arg) = @_;
419		594
420	my $serialiser = delete $arg{serialiser} \|\| $STRING_SERIALISER;	595	my $serialiser = delete $arg{serialiser} \|\| $STRING_SERIALISER;
…		…
423	my $on_destroy = delete $arg{on_destroy};	598	my $on_destroy = delete $arg{on_destroy};
424		599
425	# default for on_error is to on_event, if specified	600	# default for on_error is to on_event, if specified
426	$on_error \|\|= $on_event	601	$on_error \|\|= $on_event
427	? sub { $on_event->(error => shift) }	602	? sub { $on_event->(error => shift) }
428	: sub { die "AnyEvent::Fork::RPC: uncaught error: $_[0].\n" };	603	: sub { AE::log die => "AnyEvent::Fork::RPC: uncaught error: $_[0]." };
429		604
430	# default for on_event is to raise an error	605	# default for on_event is to raise an error
431	$on_event \|\|= sub { $on_error->("event received, but no on_event handler") };	606	$on_event \|\|= sub { $on_error->("event received, but no on_event handler") };
432		607
433	my ($f, $t) = eval $serialiser; die $@ if $@;	608	my ($f, $t) = eval $serialiser; die $@ if $@;
…		…
454	};	629	};
455		630
456	my $module = "AnyEvent::Fork::RPC::" . ($arg{async} ? "Async" : "Sync");	631	my $module = "AnyEvent::Fork::RPC::" . ($arg{async} ? "Async" : "Sync");
457		632
458	$self->require ($module)	633	$self->require ($module)
459	->send_arg ($function, $arg{init}, $serialiser)	634	->send_arg ($function, $arg{init}, $serialiser, $arg{done} \|\| "$module\::do_exit")
460	->run ("$module\::run", sub {	635	->run ("$module\::run", sub {
461	$fh = shift;	636	$fh = shift;
462		637
463	my ($id, $len);	638	my ($id, $len);
464	$rw = AE::io $fh, 0, sub {	639	$rw = AE::io $fh, 0, sub {
465	$rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf;	640	$rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf;
466	$len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf;	641	$len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf;
467		642
468	if ($len) {	643	if ($len) {
469	while (8 <= length $rbuf) {	644	while (8 <= length $rbuf) {
470	($id, $len) = unpack "LL", $rbuf;	645	($id, $len) = unpack "NN", $rbuf;
471	8 + $len <= length $rbuf	646	8 + $len <= length $rbuf
472	or last;	647	or last;
473		648
474	my @r = $t->(substr $rbuf, 8, $len);	649	my @r = $t->(substr $rbuf, 8, $len);
475	substr $rbuf, 0, 8 + $len, "";	650	substr $rbuf, 0, 8 + $len, "";
…		…
489	}	664	}
490	} elsif (defined $len) {	665	} elsif (defined $len) {
491	undef $rw; undef $ww; # it ends here	666	undef $rw; undef $ww; # it ends here
492		667
493	if (@rcb \|\| %rcb) {	668	if (@rcb \|\| %rcb) {
494	use Data::Dump;ddx[\@rcb,\%rcb];#d#
495	$on_error->("unexpected eof");	669	$on_error->("unexpected eof");
496	} else {	670	} else {
497	$on_destroy->();	671	$on_destroy->()
		672	if $on_destroy;
498	}	673	}
499	} elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {	674	} elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {
500	undef $rw; undef $ww; # it ends here	675	undef $rw; undef $ww; # it ends here
501	$on_error->("read: $!");	676	$on_error->("read: $!");
502	}	677	}
…		…
505	$ww \|\|= AE::io $fh, 1, $wcb;	680	$ww \|\|= AE::io $fh, 1, $wcb;
506	});	681	});
507		682
508	my $guard = Guard::guard {	683	my $guard = Guard::guard {
509	$shutdown = 1;	684	$shutdown = 1;
510	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	685
		686	shutdown $fh, 1 if $fh && !$ww;
511	};	687	};
512		688
513	my $id;	689	my $id;
514		690
515	$arg{async}	691	$arg{async}
…		…
517	$id = ($id == 0xffffffff ? 0 : $id) + 1;	693	$id = ($id == 0xffffffff ? 0 : $id) + 1;
518	$id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops	694	$id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops
519		695
520	$rcb{$id} = pop;	696	$rcb{$id} = pop;
521		697
522	$guard; # keep it alive	698	$guard if 0; # keep it alive
523		699
524	$wbuf .= pack "LL/a*", $id, &$f;	700	$wbuf .= pack "NN/a*", $id, &$f;
525	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	701	$ww \|\|= $fh && AE::io $fh, 1, $wcb;
526	}	702	}
527	: sub {	703	: sub {
528	push @rcb, pop;	704	push @rcb, pop;
529		705
530	$guard; # keep it alive	706	$guard; # keep it alive
531		707
532	$wbuf .= pack "L/a*", &$f;	708	$wbuf .= pack "N/a*", &$f;
533	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	709	$ww \|\|= $fh && AE::io $fh, 1, $wcb;
534	}	710	}
535	}	711	}
536		712
537	=item $rpc->(..., $cb->(...))	713	=item $rpc->(..., $cb->(...))
…		…
576	child process to the parent, except that there is no notion of return	752	child process to the parent, except that there is no notion of return
577	values.	753	values.
578		754
579	See the examples section earlier in this document for some actual	755	See the examples section earlier in this document for some actual
580	examples.	756	examples.
		757
		758	=back
		759
		760	=head2 PROCESS EXIT
		761
		762	If and when the child process exits depends on the backend and
		763	configuration. Apart from explicit exits (e.g. by calling C<exit>) or
		764	runtime conditions (uncaught exceptions, signals etc.), the backends exit
		765	under these conditions:
		766
		767	=over 4
		768
		769	=item Synchronous Backend
		770
		771	The synchronous backend is very simple: when the process waits for another
		772	request to arrive and the writing side (usually in the parent) is closed,
		773	it will exit normally, i.e. as if your main program reached the end of the
		774	file.
		775
		776	That means that if your parent process exits, the RPC process will usually
		777	exit as well, either because it is idle anyway, or because it executes a
		778	request. In the latter case, you will likely get an error when the RPc
		779	process tries to send the results to the parent (because agruably, you
		780	shouldn't exit your parent while there are still outstanding requests).
		781
		782	The process is usually quiescent when it happens, so it should rarely be a
		783	problem, and C<END> handlers can be used to clean up.
		784
		785	=item Asynchronous Backend
		786
		787	For the asynchronous backend, things are more complicated: Whenever it
		788	listens for another request by the parent, it might detect that the socket
		789	was closed (e.g. because the parent exited). It will sotp listening for
		790	new requests and instead try to write out any remaining data (if any) or
		791	simply check whether the socket cna be written to. After this, the RPC
		792	process is effectively done - no new requests are incoming, no outstanding
		793	request data can be written back.
		794
		795	Since chances are high that there are event watchers that the RPC server
		796	knows nothing about (why else would one use the async backend if not for
		797	the ability to register watchers?), the event loop would often happily
		798	continue.
		799
		800	This is why the asynchronous backend explicitly calls C<CORE::exit> when
		801	it is done (under other circumstances, such as when there is an I/O error
		802	and there is outstanding data to write, it will log a fatal message via
		803	L<AnyEvent::Log>, also causing the program to exit).
		804
		805	You can override this by specifying a function name to call via the C<done>
		806	parameter instead.
581		807
582	=back	808	=back
583		809
584	=head1 ADVANCED TOPICS	810	=head1 ADVANCED TOPICS
585		811
…		…
641	are queued and the jobs are slow, they will all run concurrently. The	867	are queued and the jobs are slow, they will all run concurrently. The
642	child must implement some queueing/limiting mechanism if this causes	868	child must implement some queueing/limiting mechanism if this causes
643	problems. Alternatively, the parent could limit the amount of rpc calls	869	problems. Alternatively, the parent could limit the amount of rpc calls
644	that are outstanding.	870	that are outstanding.
645		871
		872	Blocking use of condvars is not supported.
		873
646	Using event-based modules such as L<IO::AIO>, L<Gtk2>, L<Tk> and so on is	874	Using event-based modules such as L<IO::AIO>, L<Gtk2>, L<Tk> and so on is
647	easy.	875	easy.
648		876
649	=back	877	=back
650		878
…		…
666	half it has passed earlier.	894	half it has passed earlier.
667		895
668	Here is some (untested) pseudocode to that effect:	896	Here is some (untested) pseudocode to that effect:
669		897
670	use AnyEvent::Util;	898	use AnyEvent::Util;
		899	use AnyEvent::Fork;
671	use AnyEvent::Fork::RPC;	900	use AnyEvent::Fork::RPC;
672	use IO::FDPass;	901	use IO::FDPass;
673		902
674	my ($s1, $s2) = AnyEvent::Util::portable_socketpair;	903	my ($s1, $s2) = AnyEvent::Util::portable_socketpair;
675		904
…		…
711		940
712	Of course, this might be blocking if you pass a lot of file descriptors,	941	Of course, this might be blocking if you pass a lot of file descriptors,
713	so you might want to look into L<AnyEvent::FDpasser> which can handle the	942	so you might want to look into L<AnyEvent::FDpasser> which can handle the
714	gory details.	943	gory details.
715		944
		945	=head1 EXCEPTIONS
		946
		947	There are no provisions whatsoever for catching exceptions at this time -
		948	in the child, exeptions might kill the process, causing calls to be lost
		949	and the parent encountering a fatal error. In the parent, exceptions in
		950	the result callback will not be caught and cause undefined behaviour.
		951
716	=head1 SEE ALSO	952	=head1 SEE ALSO
717		953
718	L<AnyEvent::Fork> (to create the processes in the first place),	954	L<AnyEvent::Fork>, to create the processes in the first place.
		955
		956	L<AnyEvent::Fork::Remote>, likewise, but helpful for remote processes.
		957
719	L<AnyEvent::Fork::Pool> (to manage whole pools of processes).	958	L<AnyEvent::Fork::Pool>, to manage whole pools of processes.
720		959
721	=head1 AUTHOR AND CONTACT INFORMATION	960	=head1 AUTHOR AND CONTACT INFORMATION
722		961
723	Marc Lehmann <schmorp@schmorp.de>	962	Marc Lehmann <schmorp@schmorp.de>
724	http://software.schmorp.de/pkg/AnyEvent-Fork-RPC	963	http://software.schmorp.de/pkg/AnyEvent-Fork-RPC

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Comparing AnyEvent-Fork-RPC/RPC.pm (file contents): Revision 1.12 by root, Thu Apr 18 10:40:34 2013 UTC vs. Revision 1.33 by root, Tue Oct 15 09:15:59 2013 UTC

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Comparing AnyEvent-Fork-RPC/RPC.pm (file contents):
Revision 1.12 by root, Thu Apr 18 10:40:34 2013 UTC vs.
Revision 1.33 by root, Tue Oct 15 09:15:59 2013 UTC