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

Comparing AnyEvent-Fork-RPC/RPC.pm (file contents):
Revision 1.4 by root, Wed Apr 17 19:38:25 2013 UTC vs.
Revision 1.10 by root, Wed Apr 17 22:04:49 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;
8	use AnyEvent::Fork::RPC;	7	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 (
…		…
34	concurrently in the child, using AnyEvent.	34	concurrently in the child, using AnyEvent.
35		35
36	It also implements an asynchronous event mechanism from the child to the	36	It also implements an asynchronous event mechanism from the child to the
37	parent, that could be used for progress indications or other information.	37	parent, that could be used for progress indications or other information.
38		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
39	=head1 EXAMPLES	42	=head1 EXAMPLES
40		43
41	=head2 Synchronous Backend	44	=head2 Example 1: Synchronous Backend
42		45
43	Here is a simple example that implements a backend that executes C<unlink>	46	Here is a simple example that implements a backend that executes C<unlink>
44	and C<rmdir> calls, and reports their status back. It also reports the	47	and C<rmdir> calls, and reports their status back. It also reports the
45	number of requests it has processed every three requests, which is clearly	48	number of requests it has processed every three requests, which is clearly
46	silly, but illustrates the use of events.	49	silly, but illustrates the use of events.
…		…
55		58
56	my $rpc = AnyEvent::Fork	59	my $rpc = AnyEvent::Fork
57	->new	60	->new
58	->require ("MyWorker")	61	->require ("MyWorker")
59	->AnyEvent::Fork::RPC::run ("MyWorker::run",	62	->AnyEvent::Fork::RPC::run ("MyWorker::run",
		63	on_error => sub { warn "FATAL: $_[0]"; exit 1 },
60	on_event => sub { warn "$_[0] requests handled\n" },	64	on_event => sub { warn "$_[0] requests handled\n" },
61	on_destroy => $done,	65	on_destroy => $done,
62	);	66	);
63		67
64	for my $id (1..6) {	68	for my $id (1..6) {
…		…
102	dies with a fatal error - obviously, you must never let this happen :).	106	dies with a fatal error - obviously, you must never let this happen :).
103		107
104	Eventually it returns the status value true if the command was successful,	108	Eventually it returns the status value true if the command was successful,
105	or the status value 0 and the stringified error message.	109	or the status value 0 and the stringified error message.
106		110
107	On my system, running the first cdoe fragment with the given	111	On my system, running the first code fragment with the given
108	F<MyWorker.pm> in the current directory yields:	112	F<MyWorker.pm> in the current directory yields:
109		113
110	/tmp/somepath/1: No such file or directory	114	/tmp/somepath/1: No such file or directory
111	/tmp/somepath/2: No such file or directory	115	/tmp/somepath/2: No such file or directory
112	3 requests handled	116	3 requests handled
…		…
133		137
134	And as a final remark, there is a fine module on CPAN that can	138	And as a final remark, there is a fine module on CPAN that can
135	asynchronously C<rmdir> and C<unlink> and a lot more, and more efficiently	139	asynchronously C<rmdir> and C<unlink> and a lot more, and more efficiently
136	than this example, namely L<IO::AIO>.	140	than this example, namely L<IO::AIO>.
137		141
		142	=head3 Example 1a: the same with the asynchronous backend
		143
		144	This example only shows what needs to be changed to use the async backend
		145	instead. Doing this is not very useful, the purpose of this example is
		146	to show the minimum amount of change that is required to go from the
		147	synchronous to the asynchronous backend.
		148
		149	To use the async backend in the previous example, you need to add the
		150	C<async> parameter to the C<AnyEvent::Fork::RPC::run> call:
		151
		152	->AnyEvent::Fork::RPC::run ("MyWorker::run",
		153	async => 1,
		154	...
		155
		156	And since the function call protocol is now changed, you need to adopt
		157	C<MyWorker::run> to the async API.
		158
		159	First, you need to accept the extra initial C<$done> callback:
		160
		161	sub run {
		162	my ($done, $cmd, $path) = @_;
		163
		164	And since a response is now generated when C<$done> is called, as opposed
		165	to when the function returns, we need to call the C<$done> function with
		166	the status:
		167
		168	$done->($status or (0, "$!"));
		169
		170	A few remarks are in order. First, it's quite pointless to use the async
		171	backend for this example - but it I<is> possible. Second, you can call
		172	C<$done> before or after returning from the function. Third, having both
		173	returned from the function and having called the C<$done> callback, the
		174	child process may exit at any time, so you should call C<$done> only when
		175	you really I<are> done.
		176
		177	=head2 Example 2: Asynchronous Backend
		178
		179	#TODO
		180
138	=head1 PARENT PROCESS USAGE	181	=head1 PARENT PROCESS USAGE
139		182
140	This module exports nothing, and only implements a single function:	183	This module exports nothing, and only implements a single function:
141		184
142	=over 4	185	=over 4
…		…
149		192
150	use Errno ();	193	use Errno ();
151	use Guard ();	194	use Guard ();
152		195
153	use AnyEvent;	196	use AnyEvent;
154	#use AnyEvent::Fork;	197	use AnyEvent::Fork; # we don't actually depend on it, this is for convenience
155		198
156	our $VERSION = 0.1;	199	our $VERSION = 0.1;
157		200
158	=item my $rpc = AnyEvent::Fork::RPC::run $fork, $function, [key => value...]	201	=item my $rpc = AnyEvent::Fork::RPC::run $fork, $function, [key => value...]
159		202
…		…
197		240
198	Called when the C<$rpc> object has been destroyed and all requests have	241	Called when the C<$rpc> object has been destroyed and all requests have
199	been successfully handled. This is useful when you queue some requests and	242	been successfully handled. This is useful when you queue some requests and
200	want the child to go away after it has handled them. The problem is that	243	want the child to go away after it has handled them. The problem is that
201	the parent must not exit either until all requests have been handled, and	244	the parent must not exit either until all requests have been handled, and
202	this cna be accomplished by waiting for this callback.	245	this can be accomplished by waiting for this callback.
203		246
204	=item init => $function (default none)	247	=item init => $function (default none)
205		248
206	When specified (by name), this function is called in the child as the very	249	When specified (by name), this function is called in the child as the very
207	first thing when taking over the process, with all the arguments normally	250	first thing when taking over the process, with all the arguments normally
…		…
230	If you want to pre-load the actual back-end modules to enable memory	273	If you want to pre-load the actual back-end modules to enable memory
231	sharing, then you should load C<AnyEvent::Fork::RPC::Sync> for	274	sharing, then you should load C<AnyEvent::Fork::RPC::Sync> for
232	synchronous, and C<AnyEvent::Fork::RPC::Async> for asynchronous mode.	275	synchronous, and C<AnyEvent::Fork::RPC::Async> for asynchronous mode.
233		276
234	If you use a template process and want to fork both sync and async	277	If you use a template process and want to fork both sync and async
235	children, then it is permissible to laod both modules.	278	children, then it is permissible to load both modules.
236		279
237	=item serialiser => $string (default: '(sub { pack "(w/a)", @_ }, sub { unpack "(w/a)", shift })')	280	=item serialiser => $string (default: '(sub { pack "(w/a)", @_ }, sub { unpack "(w/a)", shift })')
238		281
239	All arguments, result data and event data have to be serialised to be	282	All arguments, result data and event data have to be serialised to be
240	transferred between the processes. For this, they have to be frozen and	283	transferred between the processes. For this, they have to be frozen and
…		…
252	If you need an external module for serialisation, then you can either	295	If you need an external module for serialisation, then you can either
253	pre-load it into your L<AnyEvent::Fork> process, or you can add a C<use>	296	pre-load it into your L<AnyEvent::Fork> process, or you can add a C<use>
254	or C<require> statement into the serialiser string. Or both.	297	or C<require> statement into the serialiser string. Or both.
255		298
256	=back	299	=back
		300
		301	See the examples section earlier in this document for some actual
		302	examples.
257		303
258	=cut	304	=cut
259		305
260	our $STRING_SERIALISER = '(sub { pack "(w/a)", @_ }, sub { unpack "(w/a)", shift })';	306	our $STRING_SERIALISER = '(sub { pack "(w/a)", @_ }, sub { unpack "(w/a)", shift })';
261		307
…		…
275	# default for on_event is to raise an error	321	# default for on_event is to raise an error
276	$on_event \|\|= sub { $on_error->("event received, but no on_event handler") };	322	$on_event \|\|= sub { $on_error->("event received, but no on_event handler") };
277		323
278	my ($f, $t) = eval $serialiser; die $@ if $@;	324	my ($f, $t) = eval $serialiser; die $@ if $@;
279		325
280	my (@rcb, $fh, $shutdown, $wbuf, $ww, $rw);	326	my (@rcb, %rcb, $fh, $shutdown, $wbuf, $ww);
281	my ($rlen, $rbuf) = 512 - 16;	327	my ($rlen, $rbuf, $rw) = 512 - 16;
282		328
283	my $wcb = sub {	329	my $wcb = sub {
284	my $len = syswrite $fh, $wbuf;	330	my $len = syswrite $fh, $wbuf;
285		331
286	if (!defined $len) {	332	unless (defined $len) {
287	if ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {	333	if ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {
288	undef $rw; undef $ww; # it ends here	334	undef $rw; undef $ww; # it ends here
289	$on_error->("$!");	335	$on_error->("$!");
290	}	336	}
291	}	337	}
…		…
302		348
303	$self->require ($module)	349	$self->require ($module)
304	->send_arg ($function, $arg{init}, $serialiser)	350	->send_arg ($function, $arg{init}, $serialiser)
305	->run ("$module\::run", sub {	351	->run ("$module\::run", sub {
306	$fh = shift;	352	$fh = shift;
		353
		354	my ($id, $len);
307	$rw = AE::io $fh, 0, sub {	355	$rw = AE::io $fh, 0, sub {
308	$rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf;	356	$rlen = $rlen * 2 + 16 if $rlen - 128 < length $rbuf;
309	my $len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf;	357	$len = sysread $fh, $rbuf, $rlen - length $rbuf, length $rbuf;
310		358
311	if ($len) {	359	if ($len) {
312	while (5 <= length $rbuf) {	360	while (8 <= length $rbuf) {
313	$len = unpack "L", $rbuf;	361	($id, $len) = unpack "LL", $rbuf;
314	4 + $len <= length $rbuf	362	8 + $len <= length $rbuf
315	or last;	363	or last;
316		364
317	my @r = $t->(substr $rbuf, 4, $len);	365	my @r = $t->(substr $rbuf, 8, $len);
318	substr $rbuf, 0, $len + 4, "";	366	substr $rbuf, 0, 8 + $len, "";
		367
		368	if ($id) {
		369	if (@rcb) {
		370	(shift @rcb)->(@r);
		371	} elsif (my $cb = delete $rcb{$id}) {
		372	$cb->(@r);
		373	} else {
		374	undef $rw; undef $ww;
		375	$on_error->("unexpected data from child");
319		376	}
320	if (pop @r) {	377	} else {
321	$on_event->(@r);	378	$on_event->(@r);
322	} elsif (@rcb) {
323	(shift @rcb)->(@r);
324	} else {
325	undef $rw; undef $ww;
326	$on_error->("unexpected data from child");
327	}	379	}
328	}	380	}
329	} elsif (defined $len) {	381	} elsif (defined $len) {
330	undef $rw; undef $ww; # it ends here	382	undef $rw; undef $ww; # it ends here
331		383
332	if (@rcb) {	384	if (@rcb \|\| %rcb) {
		385	use Data::Dump;ddx[\@rcb,\%rcb];#d#
333	$on_error->("unexpected eof");	386	$on_error->("unexpected eof");
334	} else {	387	} else {
335	$on_destroy->();	388	$on_destroy->();
336	}	389	}
337	} elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {	390	} elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) {
…		…
346	my $guard = Guard::guard {	399	my $guard = Guard::guard {
347	$shutdown = 1;	400	$shutdown = 1;
348	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	401	$ww \|\|= $fh && AE::io $fh, 1, $wcb;
349	};	402	};
350		403
		404	my $id;
		405
		406	$arg{async}
351	sub {	407	? sub {
352	push @rcb, pop;	408	$id = ($id == 0xffffffff ? 0 : $id) + 1;
		409	$id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops
353		410
		411	$rcb{$id} = pop;
		412
354	$guard; # keep it alive	413	$guard; # keep it alive
355		414
356	$wbuf .= pack "L/a*", &$f;	415	$wbuf .= pack "LL/a*", $id, &$f;
357	$ww \|\|= $fh && AE::io $fh, 1, $wcb;	416	$ww \|\|= $fh && AE::io $fh, 1, $wcb;
358	}	417	}
		418	: sub {
		419	push @rcb, pop;
		420
		421	$guard; # keep it alive
		422
		423	$wbuf .= pack "L/a*", &$f;
		424	$ww \|\|= $fh && AE::io $fh, 1, $wcb;
		425	}
359	}	426	}
360		427
361	=item $rpc->(..., $cb->(...))	428	=item $rpc->(..., $cb->(...))
362		429
363	The RPC object returned by C<AnyEvent::Fork::RPC::run> is actually a code	430	The RPC object returned by C<AnyEvent::Fork::RPC::run> is actually a code
…		…
378		445
379	The other thing that can be done with the RPC object is to destroy it. In	446	The other thing that can be done with the RPC object is to destroy it. In
380	this case, the child process will execute all remaining RPC calls, report	447	this case, the child process will execute all remaining RPC calls, report
381	their results, and then exit.	448	their results, and then exit.
382		449
		450	See the examples section earlier in this document for some actual
		451	examples.
		452
383	=back	453	=back
384		454
385	=head1 CHILD PROCESS USAGE	455	=head1 CHILD PROCESS USAGE
386		456
387	The following function is not available in this module. They are only	457	The following function is not available in this module. They are only
…		…
395		465
396	Send an event to the parent. Events are a bit like RPC calls made by the	466	Send an event to the parent. Events are a bit like RPC calls made by the
397	child process to the parent, except that there is no notion of return	467	child process to the parent, except that there is no notion of return
398	values.	468	values.
399		469
		470	See the examples section earlier in this document for some actual
		471	examples.
		472
400	=back	473	=back
401		474
402	=head1 SEE ALSO	475	=head1 SEE ALSO
403		476
404	L<AnyEvent::Fork> (to create the processes in the first place),	477	L<AnyEvent::Fork> (to create the processes in the first place),

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent-Fork-RPC/RPC.pm (file contents): Revision 1.4 by root, Wed Apr 17 19:38:25 2013 UTC vs. Revision 1.10 by root, Wed Apr 17 22:04:49 2013 UTC

Diff Legend

Comparing AnyEvent-Fork-RPC/RPC.pm (file contents):
Revision 1.4 by root, Wed Apr 17 19:38:25 2013 UTC vs.
Revision 1.10 by root, Wed Apr 17 22:04:49 2013 UTC