Support use of ByteBuffer for request-side of code-gen unary

src/compiler/cpp_generator.cc

@@ -580,6 +580,10 @@ void PrintHeaderClientMethodCallbackInterfaces(
                    "virtual void $Method$(::grpc::ClientContext* context, "
                    "const $Request$* request, $Response$* response, "
                    "std::function<void(::grpc::Status)>) = 0;\n");
+    printer->Print(*vars,
+                   "virtual void $Method$(::grpc::ClientContext* context, "
+                   "const ::grpc::ByteBuffer* request, $Response$* response, "
+                   "std::function<void(::grpc::Status)>) = 0;\n");
   } else if (ClientOnlyStreaming(method)) {
     printer->Print(*vars,
                    "virtual void $Method$(::grpc::ClientContext* context, "
@@ -642,6 +646,10 @@ void PrintHeaderClientMethodCallback(grpc_generator::Printer* printer,
                    "void $Method$(::grpc::ClientContext* context, "
                    "const $Request$* request, $Response$* response, "
                    "std::function<void(::grpc::Status)>) override;\n");
+    printer->Print(*vars,
+                   "void $Method$(::grpc::ClientContext* context, "
+                   "const ::grpc::ByteBuffer* request, $Response$* response, "
+                   "std::function<void(::grpc::Status)>) override;\n");
   } else if (ClientOnlyStreaming(method)) {
     printer->Print(*vars,
                    "void $Method$(::grpc::ClientContext* context, "
@@ -1643,6 +1651,16 @@ void PrintSourceClientMethod(grpc_generator::Printer* printer,
                    "(stub_->channel_.get(), stub_->rpcmethod_$Method$_, "
                    "context, request, response, std::move(f));\n}\n\n");
 
+    printer->Print(*vars,
+                   "void $ns$$Service$::Stub::experimental_async::$Method$("
+                   "::grpc::ClientContext* context, "
+                   "const ::grpc::ByteBuffer* request, $Response$* response, "
+                   "std::function<void(::grpc::Status)> f) {\n");
+    printer->Print(*vars,
+                   "  return ::grpc::internal::CallbackUnaryCall"
+                   "(stub_->channel_.get(), stub_->rpcmethod_$Method$_, "
+                   "context, request, response, std::move(f));\n}\n\n");
+
     for (auto async_prefix : async_prefixes) {
       (*vars)["AsyncPrefix"] = async_prefix.prefix;
       (*vars)["AsyncStart"] = async_prefix.start;

test/cpp/end2end/client_callback_end2end_test.cc

@@ -220,6 +220,36 @@ class ClientCallbackEnd2endTest
     }
   }
 
+  void SendRpcsRawReq(int num_rpcs) {
+    grpc::string test_string("Hello raw world.");
+    EchoRequest request;
+    request.set_message(test_string);
+    std::unique_ptr<ByteBuffer> send_buf = SerializeToByteBuffer(&request);
+
+    for (int i = 0; i < num_rpcs; i++) {
+      EchoResponse response;
+      ClientContext cli_ctx;
+
+      std::mutex mu;
+      std::condition_variable cv;
+      bool done = false;
+      stub_->experimental_async()->Echo(
+          &cli_ctx, send_buf.get(), &response,
+          [&request, &response, &done, &mu, &cv](Status s) {
+            GPR_ASSERT(s.ok());
+
+            EXPECT_EQ(request.message(), response.message());
+            std::lock_guard<std::mutex> l(mu);
+            done = true;
+            cv.notify_one();
+          });
+      std::unique_lock<std::mutex> l(mu);
+      while (!done) {
+        cv.wait(l);
+      }
+    }
+  }
+
   void SendRpcsGeneric(int num_rpcs, bool maybe_except) {
     const grpc::string kMethodName("/grpc.testing.EchoTestService/Echo");
     grpc::string test_string("");
@@ -347,6 +377,12 @@ TEST_P(ClientCallbackEnd2endTest, SequentialRpcs) {
   SendRpcs(10, false);
 }
 
+TEST_P(ClientCallbackEnd2endTest, SequentialRpcsRawReq) {
+  MAYBE_SKIP_TEST;
+  ResetStub();
+  SendRpcsRawReq(10);
+}
+
 TEST_P(ClientCallbackEnd2endTest, SendClientInitialMetadata) {
   MAYBE_SKIP_TEST;
   ResetStub();