implement async unary call

include/grpc++/client_context.h

@@ -57,6 +57,7 @@ namespace grpc {
 
 class CallOpBuffer;
 class ChannelInterface;
+class CompletionQueue;
 class RpcMethod;
 class Status;
 template <class R> class ClientReader;
@@ -106,6 +107,11 @@ class ClientContext {
                          ClientContext *context,
                          const google::protobuf::Message &request,
                          google::protobuf::Message *result);
+  friend void AsyncUnaryCall(ChannelInterface *channel, const RpcMethod &method,
+                             ClientContext *context,
+                             const google::protobuf::Message &request,
+                             google::protobuf::Message *result, Status *status,
+                             CompletionQueue *cq, void *tag);
 
   grpc_call *call() { return call_; }
   void set_call(grpc_call *call) {

include/grpc++/completion_queue.h

@@ -58,6 +58,7 @@ class Server;
 
 class CompletionQueueTag {
  public:
+  virtual ~CompletionQueueTag() {}
   // Called prior to returning from Next(), return value
   // is the status of the operation (return status is the default thing
   // to do)

include/grpc++/impl/call.h

@@ -54,7 +54,7 @@ namespace grpc {
 
 class Call;
 
-class CallOpBuffer final : public CompletionQueueTag {
+class CallOpBuffer : public CompletionQueueTag {
  public:
   CallOpBuffer() : return_tag_(this) {}
   ~CallOpBuffer();

src/cpp/client/client_unary_call.cc

@@ -62,11 +62,29 @@ Status BlockingUnaryCall(ChannelInterface *channel, const RpcMethod &method,
   return status;
 }
 
+class ClientAsyncRequest final : public CallOpBuffer {
+ public:
+  void FinalizeResult(void** tag, bool* status) override {
+    CallOpBuffer::FinalizeResult(tag, status);
+    delete this;
+  }
+};
+
 void AsyncUnaryCall(ChannelInterface *channel, const RpcMethod &method,
                     ClientContext *context,
                     const google::protobuf::Message &request,
                     google::protobuf::Message *result, Status *status,
                     CompletionQueue *cq, void *tag) {
-
+  ClientAsyncRequest* buf = new ClientAsyncRequest;
+  buf->Reset(tag);
+  Call call(channel->CreateCall(method, context, cq));
+  buf->AddSendInitialMetadata(context);
+  buf->AddSendMessage(request);
+  buf->AddRecvInitialMetadata(&context->recv_initial_metadata_);
+  buf->AddRecvMessage(result, nullptr);
+  buf->AddClientSendClose();
+  buf->AddClientRecvStatus(&context->trailing_metadata_, status);
+  call.PerformOps(buf);
 }
+
 }  // namespace grpc