Fix long poll cancellation (#6538)

client/matching/client.go

@@ -152,6 +152,8 @@ func (c *clientImpl) PollForActivityTask(
 		partition,
 		resp.LoadBalancerHints,
 	)
+	// caller needs to know the actual partition for cancelling long poll, so modify the request to pass this information
+	request.PollRequest.TaskList.Name = partition
 	return resp, nil
 }
 
@@ -191,6 +193,8 @@ func (c *clientImpl) PollForDecisionTask(
 		partition,
 		resp.LoadBalancerHints,
 	)
+	// caller needs to know the actual partition for cancelling long poll, so modify the request to pass this information
+	request.PollRequest.TaskList.Name = partition
 	return resp, nil
 }
 

service/frontend/api/handler.go

@@ -365,6 +365,8 @@ func (wh *WorkflowHandler) PollForActivityTask(
 				tag.Error(err))
 			return nil, err
 		}
+		// Must be cancellation error.  Doesn't matter what we return here.  Client already went away.
+		return nil, nil
 	}
 	return &types.PollForActivityTaskResponse{
 		TaskToken:                       matchingResp.TaskToken,
@@ -501,7 +503,7 @@ func (wh *WorkflowHandler) PollForDecisionTask(
 			return nil, err
 		}
 
-		// Must be cancellation error.  Does'nt matter what we return here.  Client already went away.
+		// Must be cancellation error.  Doesn't matter what we return here.  Client already went away.
 		return nil, nil
 	}