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

Comparing AnyEvent-Fork-RPC/RPC.pm (file contents):
Revision 1.14 by root, Thu Apr 18 13:11:12 2013 UTC vs.
Revision 1.46 by root, Sun Sep 15 20:18:14 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 = '2.0';
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 is 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: $AnyEvent::Fork::RPC::STRING_SERIALISER)	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 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).
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
408	Here are some examples - some of them are also available as global	514	Here are some examples - all of them are also available as global
409	variables that make them easier to use.	515	variables that make them easier to use.
410		516
411	=over 4	517	=over 4
412		518
413	=item octet strings - C<$AnyEvent::Fork::RPC::STRING_SERIALISER>	519	=item C<$AnyEvent::Fork::RPC::STRING_SERIALISER> - octet strings only
414		520
415	This serialiser concatenates length-prefixes octet strings, and is the	521	This serialiser (currently the default) concatenates length-prefixes octet
416	default.	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.
417		528
418	Implementation:	529	Implementation:
419		530
420	(	531	(
421	sub { pack "(w/a)", @_ },	532	sub { pack "(w/a)", @_ },
422	sub { unpack "(w/a)", shift }	533	sub { unpack "(w/a)", shift }
423	)	534	)
424		535
425	=item json - C<$AnyEvent::Fork::RPC::JSON_SERIALISER>	536	=item C<$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<$AnyEvent::Fork::RPC::JSON_SERIALISER> - uses L<JSON::XS> or L<JSON>
426		560
427	This serialiser creates JSON arrays - you have to make sure the L<JSON>	561	This serialiser creates JSON arrays - you have to make sure the L<JSON>
428	module is installed for this serialiser to work. It can be beneficial for	562	module is installed for this serialiser to work. It can be beneficial for
429	sharing when you preload the L<JSON> module in a template process.	563	sharing when you preload the L<JSON> module in a template process.
430		564
…		…
438	(	572	(
439	sub { JSON::encode_json \@_ },	573	sub { JSON::encode_json \@_ },
440	sub { @{ JSON::decode_json shift } }	574	sub { @{ JSON::decode_json shift } }
441	)	575	)
442		576
443	=item storable - C<$AnyEvent::Fork::RPC::STORABLE_SERIALISER>	577	=item C<$AnyEvent::Fork::RPC::STORABLE_SERIALISER> - L<Storable>
444		578
445	This serialiser uses L<Storable>, which means it has high chance of	579	This serialiser uses L<Storable>, which means it has high chance of
446	serialising just about anything you throw at it, at the cost of having	580	serialising just about anything you throw at it, at the cost of having
447	very high overhead per operation. It also comes with perl.	581	very high overhead per operation. It also comes with perl. It should be
		582	used when you need to serialise complex data structures.
448		583
449	Implementation:	584	Implementation:
450		585
451	use Storable ();	586	use Storable ();
452	(	587	(
453	sub { Storable::freeze \@_ },	588	sub { Storable::freeze \@_ },
454	sub { @{ Storable::thaw shift } }	589	sub { @{ Storable::thaw shift } }
455	)	590	)
456		591
		592	=item C<$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
457	=back	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).
458		629
459	=back	630	=back
460		631
461	See the examples section earlier in this document for some actual	632	See the examples section earlier in this document for some actual
462	examples.	633	examples.
463		634
464	=cut	635	=cut
465		636
466	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 } })';
467	our $JSON_SERIALISER = 'use JSON (); (sub { JSON::encode_json \@_ }, sub { @{ JSON::decode_json shift } })';	639	our $JSON_SERIALISER = 'use JSON (); (sub { JSON::encode_json \@_ }, sub { @{ JSON::decode_json shift } })';
468	our $STORABLE_SERIALISER = 'use Storable (); (sub { Storable::freeze \@_ }, sub { @{ Storable::thaw shift } })';	640	our $STORABLE_SERIALISER = 'use Storable (); (sub { Storable::freeze \@_ }, sub { @{ Storable::thaw shift } })';
		641	our $NSTORABLE_SERIALISER = 'use Storable (); (sub { Storable::nfreeze \@_ }, sub { @{ Storable::thaw shift } })';
469		642
470	sub run {	643	sub run {
471	my ($self, $function, %arg) = @_;	644	my ($self, $function, %arg) = @_;
472		645
473	my $serialiser = delete $arg{serialiser} \|\| $STRING_SERIALISER;	646	my $serialiser = delete $arg{serialiser} \|\| $STRING_SERIALISER;
…		…
476	my $on_destroy = delete $arg{on_destroy};	649	my $on_destroy = delete $arg{on_destroy};
477		650
478	# default for on_error is to on_event, if specified	651	# default for on_error is to on_event, if specified
479	$on_error \|\|= $on_event	652	$on_error \|\|= $on_event
480	? sub { $on_event->(error => shift) }	653	? sub { $on_event->(error => shift) }
481	: sub { die "AnyEvent::Fork::RPC: uncaught error: $_[0].\n" };	654	: sub { AE::log die => "AnyEvent::Fork::RPC: uncaught error: $_[0]." };
482		655
483	# default for on_event is to raise an error	656	# default for on_event is to raise an error
484	$on_event \|\|= sub { $on_error->("event received, but no on_event handler") };	657	$on_event \|\|= sub { $on_error->("event received, but no on_event handler") };
485		658
486	my ($f, $t) = eval $serialiser; die $@ if $@;	659	my ($f, $t) = eval $serialiser; die $@ if $@;
487		660
488	my (@rcb, %rcb, $fh, $shutdown, $wbuf, $ww);	661	my (@rcb, %rcb, $fh, $shutdown, $wbuf, $ww);
489	my ($rlen, $rbuf, $rw) = 512 - 16;	662	my ($rlen, $rbuf, $rw) = $arg{buflen_res} \|\| $arg{buflen} \|\| 512 - 16;
490		663
491	my $wcb = sub {	664	my $wcb = sub {
492	my $len = syswrite $fh, $wbuf;	665	my $len = syswrite $fh, $wbuf;
493		666
494	unless (defined $len) {	667	unless (defined $len) {
…		…
506	}	679	}
507	};	680	};
508		681
509	my $module = "AnyEvent::Fork::RPC::" . ($arg{async} ? "Async" : "Sync");	682	my $module = "AnyEvent::Fork::RPC::" . ($arg{async} ? "Async" : "Sync");
510		683
511	$self->require ($module)	684	$self->eval ("use $module 2 ()")
512	->send_arg ($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} \|\| $arg{buflen} \|\| 512 - 16,
		691	-10 # the above are 10 arguments
		692	)
513	->run ("$module\::run", sub {	693	->run ("$module\::run", sub {
514	$fh = shift;	694	$fh = shift
		695	or return $on_error->("connection failed");
515		696
516	my ($id, $len);	697	my ($id, $len);
517	$rw = AE::io $fh, 0, sub {	698	$rw = AE::io $fh, 0, sub {
518	$rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf;	699	$rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf;
519	$len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf;	700	$len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf;
520		701
521	if ($len) {	702	if ($len) {
522	while (8 <= length $rbuf) {	703	while (8 <= length $rbuf) {
523	($id, $len) = unpack "LL", $rbuf;	704	($id, $len) = unpack "NN", $rbuf;
524	8 + $len <= length $rbuf	705	8 + $len <= length $rbuf
525	or last;	706	or last;
526		707
527	my @r = $t->(substr $rbuf, 8, $len);	708	my @r = $t->(substr $rbuf, 8, $len);
528	substr $rbuf, 0, 8 + $len, "";	709	substr $rbuf, 0, 8 + $len, "";
…		…
544	undef $rw; undef $ww; # it ends here	725	undef $rw; undef $ww; # it ends here
545		726
546	if (@rcb \|\| %rcb) {	727	if (@rcb \|\| %rcb) {
547	$on_error->("unexpected eof");	728	$on_error->("unexpected eof");
548	} else {	729	} else {
549	$on_destroy->();	730	$on_destroy->()
		731	if $on_destroy;
550	}	732	}
551	} elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {	733	} elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {
552	undef $rw; undef $ww; # it ends here	734	undef $rw; undef $ww; # it ends here
553	$on_error->("read: $!");	735	$on_error->("read: $!");
554	}	736	}
…		…
557	$ww \|\|= AE::io $fh, 1, $wcb;	739	$ww \|\|= AE::io $fh, 1, $wcb;
558	});	740	});
559		741
560	my $guard = Guard::guard {	742	my $guard = Guard::guard {
561	$shutdown = 1;	743	$shutdown = 1;
562	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	744
		745	shutdown $fh, 1 if $fh && !$ww;
563	};	746	};
564		747
565	my $id;	748	my $id;
566		749
567	$arg{async}	750	$arg{async}
…		…
569	$id = ($id == 0xffffffff ? 0 : $id) + 1;	752	$id = ($id == 0xffffffff ? 0 : $id) + 1;
570	$id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops	753	$id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops
571		754
572	$rcb{$id} = pop;	755	$rcb{$id} = pop;
573		756
574	$guard; # keep it alive	757	$guard if 0; # keep it alive
575		758
576	$wbuf .= pack "LL/a*", $id, &$f;	759	$wbuf .= pack "NN/a*", $id, &$f;
577	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	760	$ww \|\|= $fh && AE::io $fh, 1, $wcb;
578	}	761	}
579	: sub {	762	: sub {
580	push @rcb, pop;	763	push @rcb, pop;
581		764
582	$guard; # keep it alive	765	$guard; # keep it alive
583		766
584	$wbuf .= pack "L/a*", &$f;	767	$wbuf .= pack "N/a*", &$f;
585	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	768	$ww \|\|= $fh && AE::io $fh, 1, $wcb;
586	}	769	}
587	}	770	}
588		771
589	=item $rpc->(..., $cb->(...))	772	=item $rpc->(..., $cb->(...))
…		…
618	The following function is not available in this module. They are only	801	The following function is not available in this module. They are only
619	available in the namespace of this module when the child is running,	802	available in the namespace of this module when the child is running,
620	without having to load any extra modules. They are part of the child-side	803	without having to load any extra modules. They are part of the child-side
621	API of L<AnyEvent::Fork::RPC>.	804	API of L<AnyEvent::Fork::RPC>.
622		805
		806	Note that these functions are typically not yet declared when code is
		807	compiled into the child, because the backend module is only loaded when
		808	you call C<run>, which is typically the last method you call on the fork
		809	object.
		810
		811	Therefore, you either have to explicitly pre-load the right backend module
		812	or mark calls to these functions as function calls, e.g.:
		813
		814	AnyEvent::Fork::RPC::event (0 => "five");
		815	AnyEvent::Fork::RPC::event->(0 => "five");
		816	&AnyEvent::Fork::RPC::flush;
		817
623	=over 4	818	=over 4
624		819
625	=item AnyEvent::Fork::RPC::event ...	820	=item AnyEvent::Fork::RPC::event (...)
626		821
627	Send an event to the parent. Events are a bit like RPC calls made by the	822	Send an event to the parent. Events are a bit like RPC calls made by the
628	child process to the parent, except that there is no notion of return	823	child process to the parent, except that there is no notion of return
629	values.	824	values.
630		825
631	See the examples section earlier in this document for some actual	826	See the examples section earlier in this document for some actual
632	examples.	827	examples.
		828
		829	Note: the event data, like any data send to the parent, might not be sent
		830	immediatelly but queued for later sending, so there is no guarantee that
		831	the event has been sent to the parent when the call returns - when you
		832	e.g. exit directly after calling this function, the parent might never
		833	receive the event. See the next function for a remedy.
		834
		835	=item $success = AnyEvent::Fork::RPC::flush ()
		836
		837	Synchronously wait and flush the reply data to the parent. Returns true on
		838	success and false otherwise (i.e. when the reply data cannot be written at
		839	all). Ignoring the success status is a common and healthy behaviour.
		840
		841	Only the "async" backend does something on C<flush> - the "sync" backend
		842	is not buffering reply data and always returns true from this function.
		843
		844	Normally, reply data might or might not be written to the parent
		845	immediatelly but is buffered. This can greatly improve performance and
		846	efficiency, but sometimes can get in your way: for example. when you want
		847	to send an error message just before exiting, or when you want to ensure
		848	replies timely reach the parent before starting a long blocking operation.
		849
		850	In these cases, you can call this function to flush any outstanding reply
		851	data to the parent. This is done blockingly, so no requests will be
		852	handled and no event callbacks will be called.
		853
		854	For example, you could wrap your request function in a C<eval> block and
		855	report the exception string back to the caller just before exiting:
		856
		857	sub req {
		858	...
		859
		860	eval {
		861	...
		862	};
		863
		864	if ($@) {
		865	AnyEvent::RPC::event (throw => "$@");
		866	AnyEvent::RPC::flush ();
		867	exit;
		868	}
		869
		870	...
		871	}
		872
		873	=back
		874
		875	=head2 PROCESS EXIT
		876
		877	If and when the child process exits depends on the backend and
		878	configuration. Apart from explicit exits (e.g. by calling C<exit>) or
		879	runtime conditions (uncaught exceptions, signals etc.), the backends exit
		880	under these conditions:
		881
		882	=over 4
		883
		884	=item Synchronous Backend
		885
		886	The synchronous backend is very simple: when the process waits for another
		887	request to arrive and the writing side (usually in the parent) is closed,
		888	it will exit normally, i.e. as if your main program reached the end of the
		889	file.
		890
		891	That means that if your parent process exits, the RPC process will usually
		892	exit as well, either because it is idle anyway, or because it executes a
		893	request. In the latter case, you will likely get an error when the RPc
		894	process tries to send the results to the parent (because agruably, you
		895	shouldn't exit your parent while there are still outstanding requests).
		896
		897	The process is usually quiescent when it happens, so it should rarely be a
		898	problem, and C<END> handlers can be used to clean up.
		899
		900	=item Asynchronous Backend
		901
		902	For the asynchronous backend, things are more complicated: Whenever it
		903	listens for another request by the parent, it might detect that the socket
		904	was closed (e.g. because the parent exited). It will sotp listening for
		905	new requests and instead try to write out any remaining data (if any) or
		906	simply check whether the socket can be written to. After this, the RPC
		907	process is effectively done - no new requests are incoming, no outstanding
		908	request data can be written back.
		909
		910	Since chances are high that there are event watchers that the RPC server
		911	knows nothing about (why else would one use the async backend if not for
		912	the ability to register watchers?), the event loop would often happily
		913	continue.
		914
		915	This is why the asynchronous backend explicitly calls C<CORE::exit> when
		916	it is done (under other circumstances, such as when there is an I/O error
		917	and there is outstanding data to write, it will log a fatal message via
		918	L<AnyEvent::Log>, also causing the program to exit).
		919
		920	You can override this by specifying a function name to call via the C<done>
		921	parameter instead.
633		922
634	=back	923	=back
635		924
636	=head1 ADVANCED TOPICS	925	=head1 ADVANCED TOPICS
637		926
…		…
693	are queued and the jobs are slow, they will all run concurrently. The	982	are queued and the jobs are slow, they will all run concurrently. The
694	child must implement some queueing/limiting mechanism if this causes	983	child must implement some queueing/limiting mechanism if this causes
695	problems. Alternatively, the parent could limit the amount of rpc calls	984	problems. Alternatively, the parent could limit the amount of rpc calls
696	that are outstanding.	985	that are outstanding.
697		986
		987	Blocking use of condvars is not supported (in the main thread, outside of
		988	e.g. L<Coro> threads).
		989
698	Using event-based modules such as L<IO::AIO>, L<Gtk2>, L<Tk> and so on is	990	Using event-based modules such as L<IO::AIO>, L<Gtk2>, L<Tk> and so on is
699	easy.	991	easy.
700		992
701	=back	993	=back
702		994
…		…
718	half it has passed earlier.	1010	half it has passed earlier.
719		1011
720	Here is some (untested) pseudocode to that effect:	1012	Here is some (untested) pseudocode to that effect:
721		1013
722	use AnyEvent::Util;	1014	use AnyEvent::Util;
		1015	use AnyEvent::Fork;
723	use AnyEvent::Fork::RPC;	1016	use AnyEvent::Fork::RPC;
724	use IO::FDPass;	1017	use IO::FDPass;
725		1018
726	my ($s1, $s2) = AnyEvent::Util::portable_socketpair;	1019	my ($s1, $s2) = AnyEvent::Util::portable_socketpair;
727		1020
…		…
763		1056
764	Of course, this might be blocking if you pass a lot of file descriptors,	1057	Of course, this might be blocking if you pass a lot of file descriptors,
765	so you might want to look into L<AnyEvent::FDpasser> which can handle the	1058	so you might want to look into L<AnyEvent::FDpasser> which can handle the
766	gory details.	1059	gory details.
767		1060
		1061	=head1 EXCEPTIONS
		1062
		1063	There are no provisions whatsoever for catching exceptions at this time -
		1064	in the child, exceptions might kill the process, causing calls to be lost
		1065	and the parent encountering a fatal error. In the parent, exceptions in
		1066	the result callback will not be caught and cause undefined behaviour.
		1067
768	=head1 SEE ALSO	1068	=head1 SEE ALSO
769		1069
770	L<AnyEvent::Fork> (to create the processes in the first place),	1070	L<AnyEvent::Fork>, to create the processes in the first place.
		1071
		1072	L<AnyEvent::Fork::Remote>, likewise, but helpful for remote processes.
		1073
771	L<AnyEvent::Fork::Pool> (to manage whole pools of processes).	1074	L<AnyEvent::Fork::Pool>, to manage whole pools of processes.
772		1075
773	=head1 AUTHOR AND CONTACT INFORMATION	1076	=head1 AUTHOR AND CONTACT INFORMATION
774		1077
775	Marc Lehmann <schmorp@schmorp.de>	1078	Marc Lehmann <schmorp@schmorp.de>
776	http://software.schmorp.de/pkg/AnyEvent-Fork-RPC	1079	http://software.schmorp.de/pkg/AnyEvent-Fork-RPC

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Comparing AnyEvent-Fork-RPC/RPC.pm (file contents): Revision 1.14 by root, Thu Apr 18 13:11:12 2013 UTC vs. Revision 1.46 by root, Sun Sep 15 20:18:14 2019 UTC

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Comparing AnyEvent-Fork-RPC/RPC.pm (file contents):
Revision 1.14 by root, Thu Apr 18 13:11:12 2013 UTC vs.
Revision 1.46 by root, Sun Sep 15 20:18:14 2019 UTC