diff options
author | Michael Yeh <miyeh@cisco.com> | 2016-05-04 12:39:20 -0700 |
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committer | Michael Yeh <miyeh@cisco.com> | 2016-05-04 12:39:20 -0700 |
commit | 470cbd1c6e0f1e4d49265a1ed403ffb1219fffa6 (patch) | |
tree | 2486ab66f9c311affda1a6b46a553aff2f5db7eb /examples/cpp/helloworld/greeter_async_client.cc | |
parent | 2df7d409144af95c99cdabefcc7a3ad841c464d0 (diff) |
Created a new sample async client that is non-blocking. A reader thread is spawned to handle all the RPC results.
Diffstat (limited to 'examples/cpp/helloworld/greeter_async_client.cc')
-rw-r--r-- | examples/cpp/helloworld/greeter_async_client.cc | 93 |
1 files changed, 36 insertions, 57 deletions
diff --git a/examples/cpp/helloworld/greeter_async_client.cc b/examples/cpp/helloworld/greeter_async_client.cc index ca5a7defb0..35014267fe 100644 --- a/examples/cpp/helloworld/greeter_async_client.cc +++ b/examples/cpp/helloworld/greeter_async_client.cc @@ -36,7 +36,6 @@ #include <string> #include <grpc++/grpc++.h> -#include <thread> #include "helloworld.grpc.pb.h" @@ -56,91 +55,71 @@ class GreeterClient { // Assambles the client's payload, sends it and presents the response back // from the server. - void SayHello(const std::string& user) { + std::string SayHello(const std::string& user) { // Data we are sending to the server. HelloRequest request; request.set_name(user); - AsyncClientCall* call = new 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; + + // The producer-consumer queue we use to communicate asynchronously with the + // gRPC runtime. + CompletionQueue cq; + + // Storage for the status of the RPC upon completion. + Status status; // stub_->AsyncSayHello() perform the RPC call, returning an instance we // store in "rpc". Because we are using the asynchronous API, we need the - // hold on to the "rpc" instance in order to get updates on the ongoing RPC. - call->response_reader = stub_->AsyncSayHello(&call->context, request, &cq_); - + // hold on to the "rpc" instance in order to get updates on the ongoig RPC. + std::unique_ptr<ClientAsyncResponseReader<HelloReply> > rpc( + stub_->AsyncSayHello(&context, request, &cq)); // 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 call object. - call->response_reader->Finish(&call->reply, &call->status, (void*)call); - - } - void AsyncCompleteRpc() - { + // was successful. Tag the request with the integer 1. + rpc->Finish(&reply, &status, (void*)1); void* got_tag; bool ok = false; - // Block until the next result is available in the completion queue "cq". - while (cq_.Next(&got_tag, &ok)) - { - AsyncClientCall* call = static_cast<AsyncClientCall*>(got_tag); - if (ok) - std::cout << "Greeter received: " << call->reply.message() << std::endl; - else - std::cout << "RPC failed" << std::endl; - delete call; + cq.Next(&got_tag, &ok); + + // Verify that the result from "cq" corresponds, by its tag, our previous + // request. + GPR_ASSERT(got_tag == (void*)1); + // ... and that the request was completed successfully. Note that "ok" + // corresponds solely to the request for updates introduced by Finish(). + GPR_ASSERT(ok); + + // Act upon the status of the actual RPC. + if (status.ok()) { + return reply.message(); + } else { + return "RPC failed"; } } private: - - // Structure 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 + std::string user("world"); + std::string reply = greeter.SayHello(user); // The actual RPC call! + std::cout << "Greeter received: " << reply << std::endl; return 0; } |