From 2c9fcd7c1402a48165f4bfab8798ed6ed98b2f84 Mon Sep 17 00:00:00 2001
From: Christian Schwarz <me@cschwarz.com>
Date: Sun, 19 Sep 2021 20:00:06 +0200
Subject: [PATCH] rpc/dataconn: always close send stream returned from
 Sender.Send()

discovered while debugging #457
---
 rpc/dataconn/dataconn_server.go | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/rpc/dataconn/dataconn_server.go b/rpc/dataconn/dataconn_server.go
index 93bf0fd..dee14e0 100644
--- a/rpc/dataconn/dataconn_server.go
+++ b/rpc/dataconn/dataconn_server.go
@@ -172,6 +172,15 @@ func (s *Server) serveConnRequest(ctx context.Context, endpoint string, c *strea
 			return
 		}
 		res, sendStream, handlerErr = s.h.Send(ctx, &req) // SHADOWING
+		// ensure that we always close the sendStream
+		if sendStream != nil {
+			defer func() {
+				err := sendStream.Close()
+				if err != nil {
+					s.log.WithError(err).Error("cannot close send stream")
+				}
+			}()
+		}
 	case EndpointRecv:
 		var req pdu.ReceiveReq
 		if err := proto.Unmarshal(reqStructured, &req); err != nil {
@@ -239,12 +248,9 @@ func (s *Server) serveConnRequest(ctx context.Context, endpoint string, c *strea
 
 	if sendStream != nil {
 		err := c.SendStream(ctx, sendStream, ZFSStream)
-		closeErr := sendStream.Close()
-		if closeErr != nil {
-			s.log.WithError(closeErr).Error("cannot close send stream")
-		}
 		if err != nil {
 			s.log.WithError(err).Error("cannot write send stream")
 		}
+		// sendStream.Close() done via defer above
 	}
 }