Add support for IsCancelled check

2 files changed, 18 insertions, 7 deletions

diff --git a/include/grpcpp/impl/codegen/callback_common.h b/include/grpcpp/impl/codegen/callback_common.h
index 8273ef2f4a..29deef658f 100644
--- a/include/grpcpp/impl/codegen/callback_common.h
+++ b/include/grpcpp/impl/codegen/callback_common.h
@@ -141,6 +141,9 @@ class CallbackWithSuccessTag
   // that are detected before the operations are internally processed.
   void force_run(bool ok) { Run(ok); }
 
+  /// check if this tag has ever been set
+  operator bool() const { return call_ != nullptr; }
+
  private:
   grpc_call* call_;
   std::function<void(bool)> func_;
@@ -153,13 +156,19 @@ class CallbackWithSuccessTag
   void Run(bool ok) {
     void* ignored = ops_;
     bool new_ok = ok;
-    GPR_CODEGEN_ASSERT(ops_->FinalizeResult(&ignored, &new_ok));
+    // Allow a "false" return value from FinalizeResult to silence the
+    // callback, just as it silences a CQ tag in the async cases
+    bool do_callback = ops_->FinalizeResult(&ignored, &new_ok);
     GPR_CODEGEN_ASSERT(ignored == ops_);
 
-    // Last use of func_, so ok to move it out for rvalue call above
-    auto func = std::move(func_);
-    func_ = nullptr;  // reset to clear this out for sure
-    CatchingCallback(std::move(func), ok);
+    if (do_callback) {
+      // Last use of func_, so ok to move it out for rvalue call above
+      auto func = std::move(func_);
+      func_ = nullptr;  // reset to clear this out for sure
+      CatchingCallback(std::move(func), ok);
+    } else {
+      func_ = nullptr;  // reset to clear this out for sure
+    }
     g_core_codegen_interface->grpc_call_unref(call_);
   }
 };
diff --git a/include/grpcpp/impl/codegen/server_context.h b/include/grpcpp/impl/codegen/server_context.h
index ecb9073cf9..82ee862f61 100644
--- a/include/grpcpp/impl/codegen/server_context.h
+++ b/include/grpcpp/impl/codegen/server_context.h
@@ -27,6 +27,7 @@
 
 #include <grpcpp/impl/codegen/call.h>
 #include <grpcpp/impl/codegen/call_op_set.h>
+#include <grpcpp/impl/codegen/callback_common.h>
 #include <grpcpp/impl/codegen/completion_queue_tag.h>
 #include <grpcpp/impl/codegen/config.h>
 #include <grpcpp/impl/codegen/create_auth_context.h>
@@ -139,7 +140,7 @@ class ServerContext {
   /// must end in "-bin".
   void AddTrailingMetadata(const grpc::string& key, const grpc::string& value);
 
-  /// IsCancelled is always safe to call when using sync API.
+  /// IsCancelled is always safe to call when using sync or callback API.
   /// When using async API, it is only safe to call IsCancelled after
   /// the AsyncNotifyWhenDone tag has been delivered.
   bool IsCancelled() const;
@@ -281,7 +282,7 @@ class ServerContext {
 
   class CompletionOp;
 
-  void BeginCompletionOp(internal::Call* call);
+  void BeginCompletionOp(internal::Call* call, bool callback);
   /// Return the tag queued by BeginCompletionOp()
   internal::CompletionQueueTag* GetCompletionOpTag();
 
@@ -312,6 +313,7 @@ class ServerContext {
   CompletionOp* completion_op_;
   bool has_notify_when_done_tag_;
   void* async_notify_when_done_tag_;
+  internal::CallbackWithSuccessTag completion_tag_;
 
   gpr_timespec deadline_;
   grpc_call* call_;