| /* |
| * |
| * Copyright 2015 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| #include <iostream> |
| #include <memory> |
| #include <string> |
| |
| #include <grpc++/grpc++.h> |
| #include <grpc/support/log.h> |
| #include <thread> |
| |
| #include "helloworld.grpc.pb.h" |
| |
| using grpc::Channel; |
| using grpc::ClientAsyncResponseReader; |
| using grpc::ClientContext; |
| using grpc::CompletionQueue; |
| using grpc::Status; |
| using helloworld::HelloRequest; |
| using helloworld::HelloReply; |
| using helloworld::Greeter; |
| |
| class GreeterClient { |
| public: |
| explicit GreeterClient(std::shared_ptr<Channel> channel) |
| : stub_(Greeter::NewStub(channel)) {} |
| |
| // Assembles the client's payload and sends it to the server. |
| void SayHello(const std::string& user) { |
| // Data we are sending to the server. |
| HelloRequest request; |
| request.set_name(user); |
| |
| // Call object to store rpc data |
| AsyncClientCall* call = new AsyncClientCall; |
| |
| // stub_->PrepareAsyncSayHello() creates an RPC object, returning |
| // an instance to store in "call" but does not actually start the RPC |
| // Because we are using the asynchronous API, we need to hold on to |
| // the "call" instance in order to get updates on the ongoing RPC. |
| call->response_reader = |
| stub_->PrepareAsyncSayHello(&call->context, request, &cq_); |
| |
| // StartCall initiates the RPC call |
| call->response_reader->StartCall(); |
| |
| // Request that, upon completion of the RPC, "reply" be updated with the |
| // server's response; "status" with the indication of whether the operation |
| // was successful. Tag the request with the memory address of the call object. |
| call->response_reader->Finish(&call->reply, &call->status, (void*)call); |
| |
| } |
| |
| // Loop while listening for completed responses. |
| // Prints out the response from the server. |
| void AsyncCompleteRpc() { |
| void* got_tag; |
| bool ok = false; |
| |
| // Block until the next result is available in the completion queue "cq". |
| while (cq_.Next(&got_tag, &ok)) { |
| // The tag in this example is the memory location of the call object |
| AsyncClientCall* call = static_cast<AsyncClientCall*>(got_tag); |
| |
| // Verify that the request was completed successfully. Note that "ok" |
| // corresponds solely to the request for updates introduced by Finish(). |
| GPR_ASSERT(ok); |
| |
| if (call->status.ok()) |
| std::cout << "Greeter received: " << call->reply.message() << std::endl; |
| else |
| std::cout << "RPC failed" << std::endl; |
| |
| // Once we're complete, deallocate the call object. |
| delete call; |
| } |
| } |
| |
| private: |
| |
| // struct for keeping state and data information |
| struct AsyncClientCall { |
| // Container for the data we expect from the server. |
| HelloReply reply; |
| |
| // Context for the client. It could be used to convey extra information to |
| // the server and/or tweak certain RPC behaviors. |
| ClientContext context; |
| |
| // Storage for the status of the RPC upon completion. |
| Status status; |
| |
| |
| std::unique_ptr<ClientAsyncResponseReader<HelloReply>> response_reader; |
| }; |
| |
| // Out of the passed in Channel comes the stub, stored here, our view of the |
| // server's exposed services. |
| std::unique_ptr<Greeter::Stub> stub_; |
| |
| // The producer-consumer queue we use to communicate asynchronously with the |
| // gRPC runtime. |
| CompletionQueue cq_; |
| }; |
| |
| int main(int argc, char** argv) { |
| |
| |
| // Instantiate the client. It requires a channel, out of which the actual RPCs |
| // are created. This channel models a connection to an endpoint (in this case, |
| // localhost at port 50051). We indicate that the channel isn't authenticated |
| // (use of InsecureChannelCredentials()). |
| GreeterClient greeter(grpc::CreateChannel( |
| "localhost:50051", grpc::InsecureChannelCredentials())); |
| |
| // Spawn reader thread that loops indefinitely |
| std::thread thread_ = std::thread(&GreeterClient::AsyncCompleteRpc, &greeter); |
| |
| for (int i = 0; i < 100; i++) { |
| std::string user("world " + std::to_string(i)); |
| greeter.SayHello(user); // The actual RPC call! |
| } |
| |
| std::cout << "Press control-c to quit" << std::endl << std::endl; |
| thread_.join(); //blocks forever |
| |
| return 0; |
| } |