send_message() and send_message_oneway() are almost identical, implement
the later in terms of the former. The patch also fixes send_message() to
work properly with MsgIn = void.
Reviewed-by: Asias He <asias@cloudius-systems.com>
Currently we cast rpc call lambda to std::function (to put all lambdas
in one container) which removes its template properties and gives it
strictly typed interface. This is inconvenient since interface may either
receive an object by value (which requires copy during invocation),
or by reference (which require lifetime management), but not both. This
patch changes the implementation to no store lambda in one central
place, but create it with rpc::make_client() call when used. This way
template properties are preserved and send_message() arguments are
forwarded to rpc call with original types.
Reviewed-by: Asias He <asias@cloudius-systems.com>
message_service: create object using placement new()
Object reference may point to a unit member that was not properly
created, so assign will not work on it. Use placement new() instead.
It is built on top of seastar rpc infrastructure. I've sorted out all
the message VERBs which Origin use. All of them can be implemented using
this messaging_service.
Each Verb contains a handler. There are two types of handlers, one
will return a message back to sender, the other will not. The former
can be registered using ms.register_handler(), the latter can be
registered using ms.register_handler_oneway().
Usage example:
To use messaging_service to send a message. All you need is:
messaging_service& ms = get_local_messaging_service();
1) To register a message hander:
ms.register_handler(messaging_verb::ECHO, [] (int x, long y) {
print("Server got echo msg = (%d, %ld) \n", x, y);
std::tuple<int, long> ret(x*x, y*y);
return make_ready_future<decltype(ret)>(std::move(ret));
});
ms.register_handler_oneway(messaging_verb::GOSSIP_SHUTDOWN, [] (empty_msg msg) {
print("Server got shutdown msg = %s\n", msg);
return messaging_service::no_wait();
});
2) To send a message:
using RetMsg = std::tuple<int, long>;
return ms.send_message<RetMsg>(messaging_verb::ECHO, id, msg1, msg2).then([] (RetMsg msg) {
print("Client sent echo got reply = (%d , %ld)\n", std::get<0>(msg), std::get<1>(msg));
return sleep(100ms).then([]{
return make_ready_future<>();
});
});
return ms.send_message_oneway<void>(messaging_verb::GOSSIP_SHUTDOWN, std::move(id), std::move(msg)).then([] () {
print("Client sent gossip_shutdown got reply = void\n");
return make_ready_future<>();
});
Tests:
send to cpu 0
$ ./message --server 127.0.0.1 --cpuid 0 --smp 2
send to cpu 1
$ ./message --server 127.0.0.1 --cpuid 1 --smp 2
