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

Comparing AnyEvent-Fork-RPC/RPC.pm (file contents):
Revision 1.13 by root, Thu Apr 18 11:11:26 2013 UTC vs.
Revision 1.45 by root, Thu Sep 12 15:15:49 2019 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 function 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 = 1.25;
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.
…		…
351	been successfully handled. This is useful when you queue some requests and	439	been successfully handled. This is useful when you queue some requests and
352	want the child to go away after it has handled them. The problem is that	440	want the child to go away after it has handled them. The problem is that
353	the parent must not exit either until all requests have been handled, and	441	the parent must not exit either until all requests have been handled, and
354	this can be accomplished by waiting for this callback.	442	this can be accomplished by waiting for this callback.
355		443
356	=item init => $function (default none)	444	=item init => $function (default: none)
357		445
358	When specified (by name), this function is called in the child as the very	446	When specified (by name), this function is called in the child as the very
359	first thing when taking over the process, with all the arguments normally	447	first thing when taking over the process, with all the arguments normally
360	passed to the C<AnyEvent::Fork::run> function, except the communications	448	passed to the C<AnyEvent::Fork::run> function, except the communications
361	socket.	449	socket.
…		…
366	It is called very early - before the serialisers are created or the	454	It is called very early - before the serialisers are created or the
367	C<$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::run> 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 => $boolean (default: C<0>)
372		474
373	The default server used in the child does all I/O blockingly, and only	475	The default server used in the child does all I/O blockingly, and only
374	allows a single RPC call to execute concurrently.	476	allows a single RPC call to execute concurrently.
375		477
376	Setting C<async> to a true value switches to another implementation that	478	Setting C<async> to a true value switches to another implementation that
377	uses L<AnyEvent> in the child and allows multiple concurrent RPC calls.	479	uses L<AnyEvent> in the child and allows multiple concurrent RPC calls (it
		480	does not support recursion in the event loop however, blocking condvar
		481	calls will fail).
378		482
379	The actual API in the child is documented in the section that describes	483	The actual API in the child is documented in the section that describes
380	the calling semantics of the returned C<$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 => $string (default: C<$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,
396	is reasonably fast and efficient.	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).
397		503
398	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
399	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
400	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
401	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
…		…
403		509
404	If you need an external module for serialisation, then you can either	510	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>	511	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.	512	or C<require> statement into the serialiser string. Or both.
407		513
		514	Here are some examples - all of them are also available as global
		515	variables that make them easier to use.
		516
		517	=over 4
		518
		519	=item C<$AnyEvent::Fork::RPC::STRING_SERIALISER> - octet strings only
		520
		521	This serialiser (currently the default) concatenates length-prefixes octet
		522	strings, and is the default. That means you can only pass (and return)
		523	strings containing character codes 0-255.
		524
		525	The main advantages of this serialiser are the high speed and that it
		526	doesn't need another module. The main disadvantage is that you are very
		527	limited in what you can pass - only octet strings.
		528
		529	Implementation:
		530
		531	(
		532	sub { pack "(w/a)", @_ },
		533	sub { unpack "(w/a)", shift }
		534	)
		535
		536	=item C<$AnyEvent::Fork::RPC::CBOR_XS_SERIALISER> - uses L<CBOR::XS>
		537
		538	This serialiser creates CBOR::XS arrays - you have to make sure the
		539	L<CBOR::XS> module is installed for this serialiser to work. It can be
		540	beneficial for sharing when you preload the L<CBOR::XS> module in a template
		541	process.
		542
		543	L<CBOR::XS> is about as fast as the octet string serialiser, but supports
		544	complex data structures (similar to JSON) and is faster than any of the
		545	other serialisers. If you have the L<CBOR::XS> module available, it's the
		546	best choice.
		547
		548	The encoder enables C<allow_sharing> (so this serialisation method can
		549	encode cyclic and self-referencing data structures).
		550
		551	Implementation:
		552
		553	use CBOR::XS ();
		554	(
		555	sub { CBOR::XS::encode_cbor_sharing \@_ },
		556	sub { @{ CBOR::XS::decode_cbor shift } }
		557	)
		558
		559	=item C<$AnyEvent::Fork::RPC::JSON_SERIALISER> - uses L<JSON::XS> or L<JSON>
		560
		561	This serialiser creates JSON arrays - you have to make sure the L<JSON>
		562	module is installed for this serialiser to work. It can be beneficial for
		563	sharing when you preload the L<JSON> module in a template process.
		564
		565	L<JSON> (with L<JSON::XS> installed) is slower than the octet string
		566	serialiser, but usually much faster than L<Storable>, unless big chunks of
		567	binary data need to be transferred.
		568
		569	Implementation:
		570
		571	use JSON ();
		572	(
		573	sub { JSON::encode_json \@_ },
		574	sub { @{ JSON::decode_json shift } }
		575	)
		576
		577	=item C<$AnyEvent::Fork::RPC::STORABLE_SERIALISER> - L<Storable>
		578
		579	This serialiser uses L<Storable>, which means it has high chance of
		580	serialising just about anything you throw at it, at the cost of having
		581	very high overhead per operation. It also comes with perl. It should be
		582	used when you need to serialise complex data structures.
		583
		584	Implementation:
		585
		586	use Storable ();
		587	(
		588	sub { Storable::freeze \@_ },
		589	sub { @{ Storable::thaw shift } }
		590	)
		591
		592	=item C<$AnyEvent::Fork::RPC::NSTORABLE_SERIALISER> - portable Storable
		593
		594	This serialiser also uses L<Storable>, but uses it's "network" format
		595	to serialise data, which makes it possible to talk to different
		596	perl binaries (for example, when talking to a process created with
		597	L<AnyEvent::Fork::Remote>).
		598
		599	Implementation:
		600
		601	use Storable ();
		602	(
		603	sub { Storable::nfreeze \@_ },
		604	sub { @{ Storable::thaw shift } }
		605	)
		606
		607	=back
		608
		609	=item buflen => $bytes (default: C<512 - 16>)
		610
		611	The starting size of the read buffer for request and response data.
		612
		613	C<AnyEvent::Fork::RPC> ensures that the buffer for reeading request and
		614	response data is large enough for at leats aingle request or response, and
		615	will dynamically enlarge the buffer if needed.
		616
		617	While this ensures that memory is not overly wasted, it typically leads
		618	to having to do one syscall per request, which can be inefficient in some
		619	cases. In such cases, it can be beneficient to increase the buffer size to
		620	hold more than one request.
		621
		622	=item buflen_req => $bytes (default: same as C<buflen>)
		623
		624	Overrides C<buflen> for request data (as read by the forked process).
		625
		626	=item buflen_res => $bytes (default: same as C<buflen>)
		627
		628	Overrides C<buflen> for response data (replies read by the parent process).
		629
408	=back	630	=back
409		631
410	See the examples section earlier in this document for some actual	632	See the examples section earlier in this document for some actual
411	examples.	633	examples.
412		634
413	=cut	635	=cut
414		636
415	our $STRING_SERIALISER = '(sub { pack "(w/a)", @_ }, sub { unpack "(w/a)", shift })';	637	our $STRING_SERIALISER = '(sub { pack "(w/a)", @_ }, sub { unpack "(w/a)", shift })';
		638	our $CBOR_XS_SERIALISER = 'use CBOR::XS (); (sub { CBOR::XS::encode_cbor_sharing \@_ }, sub { @{ CBOR::XS::decode_cbor shift } })';
		639	our $JSON_SERIALISER = 'use JSON (); (sub { JSON::encode_json \@_ }, sub { @{ JSON::decode_json shift } })';
		640	our $STORABLE_SERIALISER = 'use Storable (); (sub { Storable::freeze \@_ }, sub { @{ Storable::thaw shift } })';
		641	our $NSTORABLE_SERIALISER = 'use Storable (); (sub { Storable::nfreeze \@_ }, sub { @{ Storable::thaw shift } })';
416		642
417	sub run {	643	sub run {
418	my ($self, $function, %arg) = @_;	644	my ($self, $function, %arg) = @_;
419		645
420	my $serialiser = delete $arg{serialiser} \|\| $STRING_SERIALISER;	646	my $serialiser = delete $arg{serialiser} \|\| $STRING_SERIALISER;
…		…
423	my $on_destroy = delete $arg{on_destroy};	649	my $on_destroy = delete $arg{on_destroy};
424		650
425	# default for on_error is to on_event, if specified	651	# default for on_error is to on_event, if specified
426	$on_error \|\|= $on_event	652	$on_error \|\|= $on_event
427	? sub { $on_event->(error => shift) }	653	? sub { $on_event->(error => shift) }
428	: sub { die "AnyEvent::Fork::RPC: uncaught error: $_[0].\n" };	654	: sub { AE::log die => "AnyEvent::Fork::RPC: uncaught error: $_[0]." };
429		655
430	# default for on_event is to raise an error	656	# default for on_event is to raise an error
431	$on_event \|\|= sub { $on_error->("event received, but no on_event handler") };	657	$on_event \|\|= sub { $on_error->("event received, but no on_event handler") };
432		658
433	my ($f, $t) = eval $serialiser; die $@ if $@;	659	my ($f, $t) = eval $serialiser; die $@ if $@;
434		660
435	my (@rcb, %rcb, $fh, $shutdown, $wbuf, $ww);	661	my (@rcb, %rcb, $fh, $shutdown, $wbuf, $ww);
436	my ($rlen, $rbuf, $rw) = 512 - 16;	662	my ($rlen, $rbuf, $rw) = $arg{buflen_res} \|\| $arg{buflen} \|\| 512 - 16;
437		663
438	my $wcb = sub {	664	my $wcb = sub {
439	my $len = syswrite $fh, $wbuf;	665	my $len = syswrite $fh, $wbuf;
440		666
441	unless (defined $len) {	667	unless (defined $len) {
…		…
453	}	679	}
454	};	680	};
455		681
456	my $module = "AnyEvent::Fork::RPC::" . ($arg{async} ? "Async" : "Sync");	682	my $module = "AnyEvent::Fork::RPC::" . ($arg{async} ? "Async" : "Sync");
457		683
458	$self->require ($module)	684	$self->eval ("use $module 2 ()")
459	->send_arg ($function, $arg{init}, $serialiser)	685	->send_arg (
		686	function => $function,
		687	init => $arg{init},
		688	serialiser => $serialiser,
		689	done => $arg{done} \|\| "$module\::do_exit",
		690	rlen => $arg{buflen_req} \|\| $arg{buflen} \|\| 512 - 16,
		691	-10 # the above are 10 arguments
		692	)
460	->run ("$module\::run", sub {	693	->run ("$module\::run", sub {
461	$fh = shift;	694	$fh = shift
		695	or return $on_error->("connection failed");
462		696
463	my ($id, $len);	697	my ($id, $len);
464	$rw = AE::io $fh, 0, sub {	698	$rw = AE::io $fh, 0, sub {
465	$rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf;	699	$rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf;
466	$len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf;	700	$len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf;
467		701
468	if ($len) {	702	if ($len) {
469	while (8 <= length $rbuf) {	703	while (8 <= length $rbuf) {
470	($id, $len) = unpack "LL", $rbuf;	704	($id, $len) = unpack "NN", $rbuf;
471	8 + $len <= length $rbuf	705	8 + $len <= length $rbuf
472	or last;	706	or last;
473		707
474	my @r = $t->(substr $rbuf, 8, $len);	708	my @r = $t->(substr $rbuf, 8, $len);
475	substr $rbuf, 0, 8 + $len, "";	709	substr $rbuf, 0, 8 + $len, "";
…		…
491	undef $rw; undef $ww; # it ends here	725	undef $rw; undef $ww; # it ends here
492		726
493	if (@rcb \|\| %rcb) {	727	if (@rcb \|\| %rcb) {
494	$on_error->("unexpected eof");	728	$on_error->("unexpected eof");
495	} else {	729	} else {
496	$on_destroy->();	730	$on_destroy->()
		731	if $on_destroy;
497	}	732	}
498	} elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {	733	} elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {
499	undef $rw; undef $ww; # it ends here	734	undef $rw; undef $ww; # it ends here
500	$on_error->("read: $!");	735	$on_error->("read: $!");
501	}	736	}
…		…
504	$ww \|\|= AE::io $fh, 1, $wcb;	739	$ww \|\|= AE::io $fh, 1, $wcb;
505	});	740	});
506		741
507	my $guard = Guard::guard {	742	my $guard = Guard::guard {
508	$shutdown = 1;	743	$shutdown = 1;
509	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	744
		745	shutdown $fh, 1 if $fh && !$ww;
510	};	746	};
511		747
512	my $id;	748	my $id;
513		749
514	$arg{async}	750	$arg{async}
…		…
516	$id = ($id == 0xffffffff ? 0 : $id) + 1;	752	$id = ($id == 0xffffffff ? 0 : $id) + 1;
517	$id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops	753	$id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops
518		754
519	$rcb{$id} = pop;	755	$rcb{$id} = pop;
520		756
521	$guard; # keep it alive	757	$guard if 0; # keep it alive
522		758
523	$wbuf .= pack "LL/a*", $id, &$f;	759	$wbuf .= pack "NN/a*", $id, &$f;
524	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	760	$ww \|\|= $fh && AE::io $fh, 1, $wcb;
525	}	761	}
526	: sub {	762	: sub {
527	push @rcb, pop;	763	push @rcb, pop;
528		764
529	$guard; # keep it alive	765	$guard; # keep it alive
530		766
531	$wbuf .= pack "L/a*", &$f;	767	$wbuf .= pack "N/a*", &$f;
532	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	768	$ww \|\|= $fh && AE::io $fh, 1, $wcb;
533	}	769	}
534	}	770	}
535		771
536	=item $rpc->(..., $cb->(...))	772	=item $rpc->(..., $cb->(...))
…		…
575	child process to the parent, except that there is no notion of return	811	child process to the parent, except that there is no notion of return
576	values.	812	values.
577		813
578	See the examples section earlier in this document for some actual	814	See the examples section earlier in this document for some actual
579	examples.	815	examples.
		816
		817	Note: the event data, like any data send to the parent, might not be sent
		818	immediatelly but queued for later sending, so there is no guarantee that
		819	the event has been sent to the parent when the call returns - when you
		820	e.g. exit directly after calling this function, the parent might never
		821	receive the event.
		822
		823	=back
		824
		825	=head2 PROCESS EXIT
		826
		827	If and when the child process exits depends on the backend and
		828	configuration. Apart from explicit exits (e.g. by calling C<exit>) or
		829	runtime conditions (uncaught exceptions, signals etc.), the backends exit
		830	under these conditions:
		831
		832	=over 4
		833
		834	=item Synchronous Backend
		835
		836	The synchronous backend is very simple: when the process waits for another
		837	request to arrive and the writing side (usually in the parent) is closed,
		838	it will exit normally, i.e. as if your main program reached the end of the
		839	file.
		840
		841	That means that if your parent process exits, the RPC process will usually
		842	exit as well, either because it is idle anyway, or because it executes a
		843	request. In the latter case, you will likely get an error when the RPc
		844	process tries to send the results to the parent (because agruably, you
		845	shouldn't exit your parent while there are still outstanding requests).
		846
		847	The process is usually quiescent when it happens, so it should rarely be a
		848	problem, and C<END> handlers can be used to clean up.
		849
		850	=item Asynchronous Backend
		851
		852	For the asynchronous backend, things are more complicated: Whenever it
		853	listens for another request by the parent, it might detect that the socket
		854	was closed (e.g. because the parent exited). It will sotp listening for
		855	new requests and instead try to write out any remaining data (if any) or
		856	simply check whether the socket can be written to. After this, the RPC
		857	process is effectively done - no new requests are incoming, no outstanding
		858	request data can be written back.
		859
		860	Since chances are high that there are event watchers that the RPC server
		861	knows nothing about (why else would one use the async backend if not for
		862	the ability to register watchers?), the event loop would often happily
		863	continue.
		864
		865	This is why the asynchronous backend explicitly calls C<CORE::exit> when
		866	it is done (under other circumstances, such as when there is an I/O error
		867	and there is outstanding data to write, it will log a fatal message via
		868	L<AnyEvent::Log>, also causing the program to exit).
		869
		870	You can override this by specifying a function name to call via the C<done>
		871	parameter instead.
580		872
581	=back	873	=back
582		874
583	=head1 ADVANCED TOPICS	875	=head1 ADVANCED TOPICS
584		876
…		…
640	are queued and the jobs are slow, they will all run concurrently. The	932	are queued and the jobs are slow, they will all run concurrently. The
641	child must implement some queueing/limiting mechanism if this causes	933	child must implement some queueing/limiting mechanism if this causes
642	problems. Alternatively, the parent could limit the amount of rpc calls	934	problems. Alternatively, the parent could limit the amount of rpc calls
643	that are outstanding.	935	that are outstanding.
644		936
		937	Blocking use of condvars is not supported (in the main thread, outside of
		938	e.g. L<Coro> threads).
		939
645	Using event-based modules such as L<IO::AIO>, L<Gtk2>, L<Tk> and so on is	940	Using event-based modules such as L<IO::AIO>, L<Gtk2>, L<Tk> and so on is
646	easy.	941	easy.
647		942
648	=back	943	=back
649		944
…		…
665	half it has passed earlier.	960	half it has passed earlier.
666		961
667	Here is some (untested) pseudocode to that effect:	962	Here is some (untested) pseudocode to that effect:
668		963
669	use AnyEvent::Util;	964	use AnyEvent::Util;
		965	use AnyEvent::Fork;
670	use AnyEvent::Fork::RPC;	966	use AnyEvent::Fork::RPC;
671	use IO::FDPass;	967	use IO::FDPass;
672		968
673	my ($s1, $s2) = AnyEvent::Util::portable_socketpair;	969	my ($s1, $s2) = AnyEvent::Util::portable_socketpair;
674		970
…		…
710		1006
711	Of course, this might be blocking if you pass a lot of file descriptors,	1007	Of course, this might be blocking if you pass a lot of file descriptors,
712	so you might want to look into L<AnyEvent::FDpasser> which can handle the	1008	so you might want to look into L<AnyEvent::FDpasser> which can handle the
713	gory details.	1009	gory details.
714		1010
		1011	=head1 EXCEPTIONS
		1012
		1013	There are no provisions whatsoever for catching exceptions at this time -
		1014	in the child, exceptions might kill the process, causing calls to be lost
		1015	and the parent encountering a fatal error. In the parent, exceptions in
		1016	the result callback will not be caught and cause undefined behaviour.
		1017
715	=head1 SEE ALSO	1018	=head1 SEE ALSO
716		1019
717	L<AnyEvent::Fork> (to create the processes in the first place),	1020	L<AnyEvent::Fork>, to create the processes in the first place.
		1021
		1022	L<AnyEvent::Fork::Remote>, likewise, but helpful for remote processes.
		1023
718	L<AnyEvent::Fork::Pool> (to manage whole pools of processes).	1024	L<AnyEvent::Fork::Pool>, to manage whole pools of processes.
719		1025
720	=head1 AUTHOR AND CONTACT INFORMATION	1026	=head1 AUTHOR AND CONTACT INFORMATION
721		1027
722	Marc Lehmann <schmorp@schmorp.de>	1028	Marc Lehmann <schmorp@schmorp.de>
723	http://software.schmorp.de/pkg/AnyEvent-Fork-RPC	1029	http://software.schmorp.de/pkg/AnyEvent-Fork-RPC

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Comparing AnyEvent-Fork-RPC/RPC.pm (file contents): Revision 1.13 by root, Thu Apr 18 11:11:26 2013 UTC vs. Revision 1.45 by root, Thu Sep 12 15:15:49 2019 UTC

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Comparing AnyEvent-Fork-RPC/RPC.pm (file contents):
Revision 1.13 by root, Thu Apr 18 11:11:26 2013 UTC vs.
Revision 1.45 by root, Thu Sep 12 15:15:49 2019 UTC