Initial sketch

3 files changed, 30 insertions, 3 deletions

diff --git a/include/grpc++/completion_queue.h b/include/grpc++/completion_queue.h
index c5267f8563..9a4fa9f2e1 100644
--- a/include/grpc++/completion_queue.h
+++ b/include/grpc++/completion_queue.h
@@ -55,6 +55,7 @@ class ServerReaderWriter;
 
 class CompletionQueue;
 class Server;
+class ServerContext;
 
 class CompletionQueueTag {
  public:
@@ -62,7 +63,9 @@ class CompletionQueueTag {
   // Called prior to returning from Next(), return value
   // is the status of the operation (return status is the default thing
   // to do)
-  virtual void FinalizeResult(void **tag, bool *status) = 0;
+  // If this function returns false, the tag is dropped and not returned
+  // from the completion queue
+  virtual bool FinalizeResult(void **tag, bool *status) = 0;
 };
 
 // grpc_completion_queue wrapper class
@@ -99,6 +102,7 @@ class CompletionQueue {
   template <class R, class W>
   friend class ::grpc::ServerReaderWriter;
   friend class ::grpc::Server;
+  friend class ::grpc::ServerContext;
   friend Status BlockingUnaryCall(ChannelInterface *channel,
                                   const RpcMethod &method,
                                   ClientContext *context,
@@ -109,6 +113,9 @@ class CompletionQueue {
   // Cannot be mixed with calls to Next().
   bool Pluck(CompletionQueueTag *tag);
 
+  // Does a single polling pluck on tag
+  void TryPluck(CompletionQueueTag *tag);
+
   grpc_completion_queue *cq_;  // owned
 };
 
diff --git a/include/grpc++/impl/call.h b/include/grpc++/impl/call.h
index 4ab226339d..20c60fc545 100644
--- a/include/grpc++/impl/call.h
+++ b/include/grpc++/impl/call.h
@@ -65,7 +65,7 @@ class CallOpBuffer : public CompletionQueueTag {
   void AddSendInitialMetadata(
       std::multimap<grpc::string, grpc::string> *metadata);
   void AddSendInitialMetadata(ClientContext *ctx);
-  void AddRecvInitialMetadata(ClientContext* ctx);
+  void AddRecvInitialMetadata(ClientContext *ctx);
   void AddSendMessage(const google::protobuf::Message &message);
   void AddRecvMessage(google::protobuf::Message *message);
   void AddClientSendClose();
@@ -80,7 +80,7 @@ class CallOpBuffer : public CompletionQueueTag {
   void FillOps(grpc_op *ops, size_t *nops);
 
   // Called by completion queue just prior to returning from Next() or Pluck()
-  void FinalizeResult(void **tag, bool *status) override;
+  bool FinalizeResult(void **tag, bool *status) override;
 
   bool got_message = false;
 
diff --git a/include/grpc++/server_context.h b/include/grpc++/server_context.h
index 853f91f467..e2e14d9ef7 100644
--- a/include/grpc++/server_context.h
+++ b/include/grpc++/server_context.h
@@ -34,8 +34,11 @@
 #ifndef __GRPCPP_SERVER_CONTEXT_H_
 #define __GRPCPP_SERVER_CONTEXT_H_
 
+#include <grpc++/completion_queue.h>
+
 #include <chrono>
 #include <map>
+#include <mutex>
 
 #include "config.h"
 
@@ -76,6 +79,8 @@ class ServerContext final {
   void AddInitialMetadata(const grpc::string& key, const grpc::string& value);
   void AddTrailingMetadata(const grpc::string& key, const grpc::string& value);
 
+  bool IsCancelled() { return completion_op_.CheckCancelled(cq_); }
+
   std::multimap<grpc::string, grpc::string> client_metadata() {
     return client_metadata_;
   }
@@ -97,11 +102,26 @@ class ServerContext final {
   template <class R, class W>
   friend class ::grpc::ServerReaderWriter;
 
+  class CompletionOp final : public CompletionQueueTag {
+   public:
+    bool FinalizeResult(void** tag, bool* status) override;
+
+    bool CheckCancelled(CompletionQueue* cq);
+
+   private:
+    std::mutex mu_;
+    bool finalized_ = false;
+    int cancelled_ = 0;
+  };
+
   ServerContext(gpr_timespec deadline, grpc_metadata* metadata,
                 size_t metadata_count);
 
+  CompletionOp completion_op_;
+
   std::chrono::system_clock::time_point deadline_;
   grpc_call* call_ = nullptr;
+  CompletionQueue* cq_ = nullptr;
   bool sent_initial_metadata_ = false;
   std::multimap<grpc::string, grpc::string> client_metadata_;
   std::multimap<grpc::string, grpc::string> initial_metadata_;