4 files changed, 27 insertions, 13 deletions

diff --git a/include/grpc++/channel_interface.h b/include/grpc++/channel_interface.h
index 3631ea4d5d..b0366faabb 100644
--- a/include/grpc++/channel_interface.h
+++ b/include/grpc++/channel_interface.h
@@ -35,6 +35,7 @@
 #define __GRPCPP_CHANNEL_INTERFACE_H__
 
 #include <grpc++/status.h>
+#include <grpc++/impl/call.h>
 
 namespace google {
 namespace protobuf {
@@ -52,13 +53,12 @@ class CompletionQueue;
 class RpcMethod;
 class CallInterface;
 
-class ChannelInterface {
+class ChannelInterface : public CallHook {
  public:
   virtual ~ChannelInterface() {}
 
   virtual Call CreateCall(const RpcMethod &method, ClientContext *context,
                           CompletionQueue *cq) = 0;
-  virtual void PerformOpsOnCall(CallOpBuffer *ops, Call *call) = 0;
 };
 
 }  // namespace grpc
diff --git a/include/grpc++/client_context.h b/include/grpc++/client_context.h
index 0cf6bdc647..a6e8ccc67c 100644
--- a/include/grpc++/client_context.h
+++ b/include/grpc++/client_context.h
@@ -35,8 +35,8 @@
 #define __GRPCPP_CLIENT_CONTEXT_H__
 
 #include <chrono>
+#include <map>
 #include <string>
-#include <vector>
 
 #include <grpc/support/log.h>
 #include <grpc/support/time.h>
@@ -49,6 +49,8 @@ struct grpc_completion_queue;
 
 namespace grpc {
 
+class CallOpBuffer;
+
 class ClientContext {
  public:
   ClientContext();
@@ -67,6 +69,7 @@ class ClientContext {
   ClientContext(const ClientContext &);
   ClientContext &operator=(const ClientContext &);
 
+  friend class CallOpBuffer;
   friend class Channel;
   friend class StreamContext;
 
@@ -84,7 +87,7 @@ class ClientContext {
   grpc_call *call_;
   grpc_completion_queue *cq_;
   gpr_timespec absolute_deadline_;
-  std::vector<std::pair<grpc::string, grpc::string> > metadata_;
+  std::multimap<grpc::string, grpc::string> metadata_;
 };
 
 }  // namespace grpc
diff --git a/include/grpc++/impl/call.h b/include/grpc++/impl/call.h
index 40939e458f..8fed305ac6 100644
--- a/include/grpc++/impl/call.h
+++ b/include/grpc++/impl/call.h
@@ -52,7 +52,7 @@ struct grpc_op;
 
 namespace grpc {
 
-class ChannelInterface;
+class Call;
 
 class CallOpBuffer final : public CompletionQueueTag {
  public:
@@ -63,6 +63,7 @@ class CallOpBuffer final : public CompletionQueueTag {
   // Does not take ownership.
   void AddSendInitialMetadata(
       std::multimap<grpc::string, grpc::string> *metadata);
+  void AddSendInitialMetadata(ClientContext *ctx);
   void AddRecvInitialMetadata(
       std::multimap<grpc::string, grpc::string> *metadata);
   void AddSendMessage(const google::protobuf::Message &message);
@@ -102,12 +103,12 @@ class CallOpBuffer final : public CompletionQueueTag {
   Status* recv_status_ = nullptr;
   grpc_metadata_array recv_trailing_metadata_arr_ = {0, 0, nullptr};
   grpc_status_code status_code_ = GRPC_STATUS_OK;
-  char* status_details_ = nullptr;
+  char *status_details_ = nullptr;
   size_t status_details_capacity_ = 0;
   // Server send status
   Status* send_status_ = nullptr;
   size_t trailing_metadata_count_ = 0;
-  grpc_metadata* trailing_metadata_ = nullptr;
+  grpc_metadata *trailing_metadata_ = nullptr;
 };
 
 class CCallDeleter {
@@ -115,10 +116,17 @@ class CCallDeleter {
   void operator()(grpc_call *c);
 };
 
+// Channel and Server implement this to allow them to hook performing ops
+class CallHook {
+ public:
+  virtual ~CallHook() {}
+  virtual void PerformOpsOnCall(CallOpBuffer *ops, Call *call) = 0;
+};
+
 // Straightforward wrapping of the C call object
 class Call final {
  public:
-  Call(grpc_call *call, ChannelInterface *channel, CompletionQueue *cq);
+  Call(grpc_call *call, CallHook *call_hook_, CompletionQueue *cq);
 
   void PerformOps(CallOpBuffer *buffer);
 
@@ -126,7 +134,7 @@ class Call final {
   CompletionQueue *cq() { return cq_; }
 
  private:
-  ChannelInterface *channel_;
+  CallHook *call_hook_;
   CompletionQueue *cq_;
   std::unique_ptr<grpc_call, CCallDeleter> call_;
 };
diff --git a/include/grpc++/server.h b/include/grpc++/server.h
index b02c4130d9..98f3f17197 100644
--- a/include/grpc++/server.h
+++ b/include/grpc++/server.h
@@ -41,6 +41,7 @@
 
 #include <grpc++/completion_queue.h>
 #include <grpc++/config.h>
+#include <grpc++/impl/call.h>
 #include <grpc++/status.h>
 
 struct grpc_server;
@@ -59,7 +60,7 @@ class ServerCredentials;
 class ThreadPoolInterface;
 
 // Currently it only supports handling rpcs in a single thread.
-class Server {
+class Server final : private CallHook {
  public:
   ~Server();
 
@@ -72,7 +73,8 @@ class Server {
   class MethodRequestData;
 
   // ServerBuilder use only
-  Server(ThreadPoolInterface* thread_pool, bool thread_pool_owned, ServerCredentials* creds);
+  Server(ThreadPoolInterface* thread_pool, bool thread_pool_owned,
+         ServerCredentials* creds);
   Server();
   // Register a service. This call does not take ownership of the service.
   // The service must exist for the lifetime of the Server instance.
@@ -86,9 +88,10 @@ class Server {
   void RunRpc();
   void ScheduleCallback();
 
+  void PerformOpsOnCall(CallOpBuffer* ops, Call* call) override;
+
   // Completion queue.
-  std::unique_ptr<CompletionQueue> cq_sync_;
-  std::unique_ptr<CompletionQueue> cq_async_;
+  CompletionQueue cq_;
 
   // Sever status
   std::mutex mu_;