Files
flatbuffers/grpc/samples/greeter/client.cpp
Lawrence Chan da67c0a71f [C++] Improve flatbuffers + gRPC integration (#4310)
* Rework flatbuffers + gRPC integration

- Introduce `flatbuffers::grpc::Message<T>`, a `grpc_slice`-backed
message buffer that handles refcounting and allows flatbuffers to
transfer ownership to gRPC efficiently. This replaces
`flatbuffers::BufferRef<T>`, which required a copy call and was also
unsafe w.r.t. buffer lifetime.
- Introduce `flatbuffers::grpc::MessageBuilder`, a gRPC-specific builder
that forces a `grpc_slice`-backed allocator and also adds some helpful
`Message<T>`-related methods.
- Update serializers accordingly (now zero-copy between flatbuffers and
gRPC).

* gRPC: verify messages by default, but allow user to override

* gRPC: fix some formatting issues

* Disable verification by default, but add helper method

* Make FlatBufferBuilder fields protected + remove vec accessor

* Use bool add_ref parameter to toggle refcount incr

* Remove unnecessary inline specifiers

* Fix formatting

* Use auto

* Remove empty lines

* Use grpc_slice helper macros

* Simplify reset code

* Disable Message copy ctor and assignment by default

* Remove unused member

* Enable gRPC verification by default

* Use auto

* Bake in message verification (remove template specialization)

* Add RoundUp func

* Consolidate gRPC message copy flag

* Make vector_downward allocations fully lazy

* Test message verification failure code/message

* Add grpctest verification test comments

* Simplify reallocate implementation

* Make initial_size a size_t

* Use ternary op for growth_policy

* Use truthiness rather than dont explicit nullptr check

* Indent preprocessor directives

* Remove grpc message copy/assignment

* Fix a few bugs

* Add gRPC example

* Add basic gRPC docs

* Use doxygen EXAMPLE_PATH + @include

* Reference example fbs in grpc docs

* Move gRPC examples into grpc/samples

* Fix pointer/reference formatting

* Use std::function rather than templated callback func

* Create fresh message builder for each request

* Use Clear() in Reset() impl

* Use FLATBUFFERS_CONSTEXPR
2017-06-07 13:56:49 -07:00

86 lines
2.5 KiB
C++

#include "greeter.grpc.fb.h"
#include "greeter_generated.h"
#include <grpc++/grpc++.h>
#include <iostream>
#include <memory>
#include <string>
class GreeterClient {
public:
GreeterClient(std::shared_ptr<grpc::Channel> channel)
: stub_(Greeter::NewStub(channel)) {}
std::string SayHello(const std::string &name) {
flatbuffers::grpc::MessageBuilder mb;
auto name_offset = mb.CreateString(name);
auto request_offset = CreateHelloRequest(mb, name_offset);
mb.Finish(request_offset);
auto request_msg = mb.ReleaseMessage<HelloRequest>();
flatbuffers::grpc::Message<HelloReply> response_msg;
grpc::ClientContext context;
auto status = stub_->SayHello(&context, request_msg, &response_msg);
if (status.ok()) {
const HelloReply *response = response_msg.GetRoot();
return response->message()->str();
} else {
std::cerr << status.error_code() << ": " << status.error_message()
<< std::endl;
return "RPC failed";
}
}
void SayManyHellos(const std::string &name, int num_greetings,
std::function<void(const std::string &)> callback) {
flatbuffers::grpc::MessageBuilder mb;
auto name_offset = mb.CreateString(name);
auto request_offset =
CreateManyHellosRequest(mb, name_offset, num_greetings);
mb.Finish(request_offset);
auto request_msg = mb.ReleaseMessage<ManyHellosRequest>();
flatbuffers::grpc::Message<HelloReply> response_msg;
grpc::ClientContext context;
auto stream = stub_->SayManyHellos(&context, request_msg);
while (stream->Read(&response_msg)) {
const HelloReply *response = response_msg.GetRoot();
callback(response->message()->str());
}
auto status = stream->Finish();
if (!status.ok()) {
std::cerr << status.error_code() << ": " << status.error_message()
<< std::endl;
callback("RPC failed");
}
}
private:
std::unique_ptr<Greeter::Stub> stub_;
};
int main(int argc, char **argv) {
std::string server_address("localhost:50051");
auto channel =
grpc::CreateChannel(server_address, grpc::InsecureChannelCredentials());
GreeterClient greeter(channel);
std::string name("world");
std::string message = greeter.SayHello(name);
std::cerr << "Greeter received: " << message << std::endl;
int num_greetings = 10;
greeter.SayManyHellos(name, num_greetings, [](const std::string &message) {
std::cerr << "Greeter received: " << message << std::endl;
});
return 0;
}