| /* |
| * |
| * Copyright 2015, Google Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| * |
| */ |
| |
| #include <memory> |
| #include <iostream> |
| #include <string> |
| #include <thread> |
| |
| #include <grpc++/grpc++.h> |
| #include <grpc/support/log.h> |
| |
| #include "helloworld.grpc.pb.h" |
| |
| using grpc::Server; |
| using grpc::ServerAsyncResponseWriter; |
| using grpc::ServerBuilder; |
| using grpc::ServerContext; |
| using grpc::ServerCompletionQueue; |
| using grpc::Status; |
| using helloworld::HelloRequest; |
| using helloworld::HelloReply; |
| using helloworld::Greeter; |
| |
| class ServerImpl final { |
| public: |
| ~ServerImpl() { |
| server_->Shutdown(); |
| // Always shutdown the completion queue after the server. |
| cq_->Shutdown(); |
| } |
| |
| // There is no shutdown handling in this code. |
| void Run() { |
| std::string server_address("0.0.0.0:50051"); |
| |
| ServerBuilder builder; |
| // Listen on the given address without any authentication mechanism. |
| builder.AddListeningPort(server_address, grpc::InsecureServerCredentials()); |
| // Register "service_" as the instance through which we'll communicate with |
| // clients. In this case it corresponds to an *asynchronous* service. |
| builder.RegisterService(&service_); |
| // Get hold of the completion queue used for the asynchronous communication |
| // with the gRPC runtime. |
| cq_ = builder.AddCompletionQueue(); |
| // Finally assemble the server. |
| server_ = builder.BuildAndStart(); |
| std::cout << "Server listening on " << server_address << std::endl; |
| |
| // Proceed to the server's main loop. |
| HandleRpcs(); |
| } |
| |
| private: |
| // Class encompasing the state and logic needed to serve a request. |
| class CallData { |
| public: |
| // Take in the "service" instance (in this case representing an asynchronous |
| // server) and the completion queue "cq" used for asynchronous communication |
| // with the gRPC runtime. |
| CallData(Greeter::AsyncService* service, ServerCompletionQueue* cq) |
| : service_(service), cq_(cq), responder_(&ctx_), status_(CREATE) { |
| // Invoke the serving logic right away. |
| Proceed(); |
| } |
| |
| void Proceed() { |
| if (status_ == CREATE) { |
| // Make this instance progress to the PROCESS state. |
| status_ = PROCESS; |
| |
| // As part of the initial CREATE state, we *request* that the system |
| // start processing SayHello requests. In this request, "this" acts are |
| // the tag uniquely identifying the request (so that different CallData |
| // instances can serve different requests concurrently), in this case |
| // the memory address of this CallData instance. |
| service_->RequestSayHello(&ctx_, &request_, &responder_, cq_, cq_, |
| this); |
| } else if (status_ == PROCESS) { |
| // Spawn a new CallData instance to serve new clients while we process |
| // the one for this CallData. The instance will deallocate itself as |
| // part of its FINISH state. |
| new CallData(service_, cq_); |
| |
| // The actual processing. |
| std::string prefix("Hello "); |
| reply_.set_message(prefix + request_.name()); |
| |
| // And we are done! Let the gRPC runtime know we've finished, using the |
| // memory address of this instance as the uniquely identifying tag for |
| // the event. |
| status_ = FINISH; |
| responder_.Finish(reply_, Status::OK, this); |
| } else { |
| GPR_ASSERT(status_ == FINISH); |
| // Once in the FINISH state, deallocate ourselves (CallData). |
| delete this; |
| } |
| } |
| |
| private: |
| // The means of communication with the gRPC runtime for an asynchronous |
| // server. |
| Greeter::AsyncService* service_; |
| // The producer-consumer queue where for asynchronous server notifications. |
| ServerCompletionQueue* cq_; |
| // Context for the rpc, allowing to tweak aspects of it such as the use |
| // of compression, authentication, as well as to send metadata back to the |
| // client. |
| ServerContext ctx_; |
| |
| // What we get from the client. |
| HelloRequest request_; |
| // What we send back to the client. |
| HelloReply reply_; |
| |
| // The means to get back to the client. |
| ServerAsyncResponseWriter<HelloReply> responder_; |
| |
| // Let's implement a tiny state machine with the following states. |
| enum CallStatus { CREATE, PROCESS, FINISH }; |
| CallStatus status_; // The current serving state. |
| }; |
| |
| // This can be run in multiple threads if needed. |
| void HandleRpcs() { |
| // Spawn a new CallData instance to serve new clients. |
| new CallData(&service_, cq_.get()); |
| void* tag; // uniquely identifies a request. |
| bool ok; |
| while (true) { |
| // Block waiting to read the next event from the completion queue. The |
| // event is uniquely identified by its tag, which in this case is the |
| // memory address of a CallData instance. |
| // The return value of Next should always be checked. This return value |
| // tells us whether there is any kind of event or cq_ is shutting down. |
| GPR_ASSERT(cq_->Next(&tag, &ok)); |
| GPR_ASSERT(ok); |
| static_cast<CallData*>(tag)->Proceed(); |
| } |
| } |
| |
| std::unique_ptr<ServerCompletionQueue> cq_; |
| Greeter::AsyncService service_; |
| std::unique_ptr<Server> server_; |
| }; |
| |
| int main(int argc, char** argv) { |
| ServerImpl server; |
| server.Run(); |
| |
| return 0; |
| } |