From bc1283c43b2e568a5d1dd690fd40a6cb634536fc Mon Sep 17 00:00:00 2001
From: Jan Tattermusch <jtattermusch@google.com>
Date: Wed, 24 Jul 2019 07:39:43 -0400
Subject: [PATCH] forbid BeginOp and EndOp for sync completion queue altogether

---
 .../Internal/CompletionQueueSafeHandle.cs        | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs b/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
index 25540b40a10..6103ba99aab 100644
--- a/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
+++ b/src/csharp/Grpc.Core/Internal/CompletionQueueSafeHandle.cs
@@ -104,20 +104,16 @@ namespace Grpc.Core.Internal
 
         private void BeginOp()
         {
-            if (shutdownRefcount != null)
-            {
-                bool success = false;
-                shutdownRefcount.IncrementIfNonzero(ref success);
-                GrpcPreconditions.CheckState(success, "Shutdown has already been called");
-            }
+            GrpcPreconditions.CheckNotNull(shutdownRefcount, nameof(shutdownRefcount));
+            bool success = false;
+            shutdownRefcount.IncrementIfNonzero(ref success);
+            GrpcPreconditions.CheckState(success, "Shutdown has already been called");
         }
 
         private void EndOp()
         {
-            if (shutdownRefcount != null)
-            {
-                DecrementShutdownRefcount();
-            }
+            GrpcPreconditions.CheckNotNull(shutdownRefcount, nameof(shutdownRefcount));
+            DecrementShutdownRefcount();
         }
 
         // Allows declaring BeginOp and EndOp of a completion queue with a using statement.