Merge pull request #12645 from vjpai/generic_unary

C++ GenericStub: add unary call mode

include/grpc++/generic/generic_stub.h

@@ -20,6 +20,7 @@
 #define GRPCXX_GENERIC_GENERIC_STUB_H
 
 #include <grpc++/support/async_stream.h>
+#include <grpc++/support/async_unary_call.h>
 #include <grpc++/support/byte_buffer.h>
 
 namespace grpc {
@@ -27,6 +28,7 @@ namespace grpc {
 class CompletionQueue;
 typedef ClientAsyncReaderWriter<ByteBuffer, ByteBuffer>
     GenericClientAsyncReaderWriter;
+typedef ClientAsyncResponseReader<ByteBuffer> GenericClientAsyncResponseReader;
 
 /// Generic stubs provide a type-unsafe interface to call gRPC methods
 /// by name.
@@ -51,6 +53,14 @@ class GenericStub final {
   std::unique_ptr<GenericClientAsyncReaderWriter> PrepareCall(
       ClientContext* context, const grpc::string& method, CompletionQueue* cq);
 
+  /// Setup a unary call to a named method \a method using \a context, and don't
+  /// start it. Let it be started explicitly with StartCall.
+  /// The return value only indicates whether or not registration of the call
+  /// succeeded (i.e. the call won't proceed if the return value is nullptr).
+  std::unique_ptr<GenericClientAsyncResponseReader> PrepareUnaryCall(
+      ClientContext* context, const grpc::string& method,
+      const ByteBuffer& request, CompletionQueue* cq);
+
  private:
   std::shared_ptr<ChannelInterface> channel_;
 };

src/cpp/client/generic_stub.cc

@@ -47,4 +47,14 @@ std::unique_ptr<GenericClientAsyncReaderWriter> GenericStub::PrepareCall(
   return CallInternal(channel_.get(), context, method, cq, false, nullptr);
 }
 
+// setup a unary call to a named method
+std::unique_ptr<GenericClientAsyncResponseReader> GenericStub::PrepareUnaryCall(
+    ClientContext* context, const grpc::string& method,
+    const ByteBuffer& request, CompletionQueue* cq) {
+  return std::unique_ptr<GenericClientAsyncResponseReader>(
+      GenericClientAsyncResponseReader::Create(
+          channel_.get(), cq, RpcMethod(method.c_str(), RpcMethod::NORMAL_RPC),
+          context, request, false));
+}
+
 }  // namespace grpc

test/cpp/end2end/generic_end2end_test.cc

@@ -196,6 +196,62 @@ TEST_F(GenericEnd2endTest, SequentialRpcs) {
   SendRpc(10);
 }
 
+TEST_F(GenericEnd2endTest, SequentialUnaryRpcs) {
+  ResetStub();
+  const int num_rpcs = 10;
+  const grpc::string kMethodName("/grpc.cpp.test.util.EchoTestService/Echo");
+  for (int i = 0; i < num_rpcs; i++) {
+    EchoRequest send_request;
+    EchoRequest recv_request;
+    EchoResponse send_response;
+    EchoResponse recv_response;
+    Status recv_status;
+
+    ClientContext cli_ctx;
+    GenericServerContext srv_ctx;
+    GenericServerAsyncReaderWriter stream(&srv_ctx);
+
+    // The string needs to be long enough to test heap-based slice.
+    send_request.set_message("Hello world. Hello world. Hello world.");
+
+    std::unique_ptr<ByteBuffer> cli_send_buffer =
+        SerializeToByteBuffer(&send_request);
+    std::unique_ptr<GenericClientAsyncResponseReader> call =
+        generic_stub_->PrepareUnaryCall(&cli_ctx, kMethodName,
+                                        *cli_send_buffer.get(), &cli_cq_);
+    call->StartCall();
+    ByteBuffer cli_recv_buffer;
+    call->Finish(&cli_recv_buffer, &recv_status, tag(1));
+
+    generic_service_.RequestCall(&srv_ctx, &stream, srv_cq_.get(),
+                                 srv_cq_.get(), tag(4));
+
+    verify_ok(srv_cq_.get(), 4, true);
+    EXPECT_EQ(server_host_, srv_ctx.host().substr(0, server_host_.length()));
+    EXPECT_EQ(kMethodName, srv_ctx.method());
+
+    ByteBuffer srv_recv_buffer;
+    stream.Read(&srv_recv_buffer, tag(5));
+    server_ok(5);
+    EXPECT_TRUE(ParseFromByteBuffer(&srv_recv_buffer, &recv_request));
+    EXPECT_EQ(send_request.message(), recv_request.message());
+
+    send_response.set_message(recv_request.message());
+    std::unique_ptr<ByteBuffer> srv_send_buffer =
+        SerializeToByteBuffer(&send_response);
+    stream.Write(*srv_send_buffer, tag(6));
+    server_ok(6);
+
+    stream.Finish(Status::OK, tag(7));
+    server_ok(7);
+
+    client_ok(1);
+    EXPECT_TRUE(ParseFromByteBuffer(&cli_recv_buffer, &recv_response));
+    EXPECT_EQ(send_response.message(), recv_response.message());
+    EXPECT_TRUE(recv_status.ok());
+  }
+}
+
 // One ping, one pong.
 TEST_F(GenericEnd2endTest, SimpleBidiStreaming) {
   ResetStub();