Send initial metadata

include/grpc++/server_context.h

@@ -53,12 +53,18 @@ class ServerContext {
 
   std::chrono::system_clock::time_point absolute_deadline() { return deadline_; }
 
+  void AddInitialMetadata(const grpc::string& key, const grpc::string& value);
+  void AddTrailingMetadata(const grpc::string& key, const grpc::string& value);
+
  private:
   friend class ::grpc::Server;
   ServerContext(gpr_timespec deadline, grpc_metadata *metadata, size_t metadata_count);
 
   const std::chrono::system_clock::time_point deadline_;
-  std::multimap<grpc::string, grpc::string> metadata_;
+  bool sent_initial_metadata_ = false;
+  std::multimap<grpc::string, grpc::string> client_metadata_;
+  std::multimap<grpc::string, grpc::string> initial_metadata_;
+  std::multimap<grpc::string, grpc::string> trailing_metadata_;
 };
 
 }  // namespace grpc

src/cpp/server/server.cc

@@ -172,10 +172,13 @@ class Server::MethodRequestData final : public CompletionQueueTag {
       auto status = method_->handler()->RunHandler(
           MethodHandler::HandlerParameter(&call_, &ctx_, req.get(), res.get()));
       CallOpBuffer buf;
-      buf.AddServerSendStatus(nullptr, status);
+      if (!ctx_.sent_initial_metadata_) {
+        buf.AddSendInitialMetadata(&ctx_.initial_metadata_);
+      }
       if (has_response_payload_) {
         buf.AddSendMessage(*res);
       }
+      buf.AddServerSendStatus(&ctx_.trailing_metadata_, status);
       call_.PerformOps(&buf);
       GPR_ASSERT(cq_.Pluck(&buf));
     }

src/cpp/server/server_context.cc

@@ -37,11 +37,14 @@
 
 namespace grpc {
 
-ServerContext::ServerContext(gpr_timespec deadline, grpc_metadata *metadata, size_t metadata_count)
-	: deadline_(Timespec2Timepoint(deadline)) {
+ServerContext::ServerContext(gpr_timespec deadline, grpc_metadata *metadata,
+                             size_t metadata_count)
+    : deadline_(Timespec2Timepoint(deadline)) {
   for (size_t i = 0; i < metadata_count; i++) {
-  	metadata_.insert(std::make_pair(grpc::string(metadata[i].key),
-  		grpc::string(metadata[i].value, metadata[i].value + metadata[i].value_length)));
+    client_metadata_.insert(std::make_pair(
+        grpc::string(metadata[i].key),
+        grpc::string(metadata[i].value,
+                     metadata[i].value + metadata[i].value_length)));
   }
 }