Some streaming progress

src/core/transport/chttp2_transport.c

diff --git a/src/core/transport/chttp2_transport.c b/src/core/transport/chttp2_transport.c
index 7d78bfa..65d11f1 100644
--- a/src/core/transport/chttp2_transport.c
+++ b/src/core/transport/chttp2_transport.c
@@ -1015,6 +1015,8 @@
   int had_outgoing;
   char buffer[GPR_LTOA_MIN_BUFSIZE];
 
+  gpr_log(GPR_DEBUG, "cancel %d", id);
+
   if (s) {
     /* clear out any unreported input & output: nobody cares anymore */
     had_outgoing = s->outgoing_sopb.nops != 0;
@@ -1185,6 +1187,8 @@
   transport *t = tp;
   stream *s = t->incoming_stream;
 
+  gpr_log(GPR_DEBUG, "on_header: %d %s %s", s->id, grpc_mdstr_as_c_string(md->key), grpc_mdstr_as_c_string(md->value));
+
   GPR_ASSERT(s);
   stream_list_join(t, s, PENDING_CALLBACKS);
   if (md->key == t->str_grpc_timeout) {

src/cpp/client/client_unary_call.cc

diff --git a/src/cpp/client/client_unary_call.cc b/src/cpp/client/client_unary_call.cc
index 30bf2d0..bc0e837 100644
--- a/src/cpp/client/client_unary_call.cc
+++ b/src/cpp/client/client_unary_call.cc
@@ -51,11 +51,12 @@
   Status status;
   buf.AddSendInitialMetadata(context);
   buf.AddSendMessage(request);
-  buf.AddRecvMessage(result);
+  bool got_message;
+  buf.AddRecvMessage(result, &got_message);
   buf.AddClientSendClose();
   buf.AddClientRecvStatus(nullptr, &status);  // TODO metadata
   call.PerformOps(&buf);
-  GPR_ASSERT(cq.Pluck(&buf));
+  GPR_ASSERT(cq.Pluck(&buf) && (got_message || !status.IsOk()));
   return status;
 }
 

src/cpp/common/call.cc

diff --git a/src/cpp/common/call.cc b/src/cpp/common/call.cc
index d90ef03..a20d4a0 100644
--- a/src/cpp/common/call.cc
+++ b/src/cpp/common/call.cc
@@ -58,6 +58,7 @@
   }
 
   recv_message_ = nullptr;
+  got_message_ = nullptr;
   if (recv_message_buf_) {
     grpc_byte_buffer_destroy(recv_message_buf_);
     recv_message_buf_ = nullptr;
@@ -128,8 +129,9 @@
   send_message_ = &message;
 }
 
-void CallOpBuffer::AddRecvMessage(google::protobuf::Message *message) {
+void CallOpBuffer::AddRecvMessage(google::protobuf::Message *message, bool* got_message) {
   recv_message_ = message;
+  got_message_ = got_message;
 }
 
 void CallOpBuffer::AddClientSendClose() {
@@ -239,10 +241,15 @@
     FillMetadataMap(&recv_initial_metadata_arr_, recv_initial_metadata_);
   }
   // Parse received message if any.
-  if (recv_message_ && recv_message_buf_) {
-    *status = DeserializeProto(recv_message_buf_, recv_message_);
-    grpc_byte_buffer_destroy(recv_message_buf_);
-    recv_message_buf_ = nullptr;
+  if (recv_message_) {
+    if (recv_message_buf_) {
+      *got_message_ = true;
+      *status = DeserializeProto(recv_message_buf_, recv_message_);
+      grpc_byte_buffer_destroy(recv_message_buf_);
+      recv_message_buf_ = nullptr;
+    } else {
+      *got_message_ = false;
+    }
   }
   // Parse received status.
   if (recv_status_) {

src/cpp/server/server.cc

diff --git a/src/cpp/server/server.cc b/src/cpp/server/server.cc
index be3d225..17b0543 100644
--- a/src/cpp/server/server.cc
+++ b/src/cpp/server/server.cc
@@ -177,9 +177,7 @@
       auto status = method_->handler()->RunHandler(
           MethodHandler::HandlerParameter(&call_, &ctx_, req.get(), res.get()));
       CallOpBuffer buf;
-      if (!ctx_.sent_initial_metadata_) {
-        buf.AddSendInitialMetadata(&ctx_.initial_metadata_);
-      }
+      ctx_.SendInitialMetadataIfNeeded(&buf);
       if (has_response_payload_) {
         buf.AddSendMessage(*res);
       }

src/cpp/server/server_context.cc

diff --git a/src/cpp/server/server_context.cc b/src/cpp/server/server_context.cc
index 2bf4104..06eeb39 100644
--- a/src/cpp/server/server_context.cc
+++ b/src/cpp/server/server_context.cc
@@ -32,6 +32,7 @@
  */
 
 #include <grpc++/server_context.h>
+#include <grpc++/impl/call.h>
 #include <grpc/grpc.h>
 #include "src/cpp/util/time.h"
 
@@ -48,4 +49,11 @@
   }
 }
 
+void ServerContext::SendInitialMetadataIfNeeded(CallOpBuffer* buf) {
+  if (!sent_initial_metadata_) {
+    buf->AddSendInitialMetadata(&initial_metadata_);
+    sent_initial_metadata_ = true;
+  }
+}
+
 }  // namespace grpc