From b25edb62cc1cb49b82760084a5dbe4e6d5a5c4d1 Mon Sep 17 00:00:00 2001
From: "Sahdev P. Zala" <spzala@us.ibm.com>
Date: Sun, 20 Jan 2019 11:39:28 -0500
Subject: [PATCH] clientV3watch: Watch Close should close successfully

Closing of watch by client will cancel the watch grpc stream and
can produce a context canceled error. However, since client
simply wanted to close the watcher the error can create confusion
that something went wrong instead of a successful close. Ensure
that Close do not return error.

Fixed #10340
---
 clientv3/integration/watch_test.go | 21 +++++++++++++++++++++
 clientv3/watch.go                  |  4 ++++
 2 files changed, 25 insertions(+)

diff --git a/clientv3/integration/watch_test.go b/clientv3/integration/watch_test.go
index 3482f31bd..bf751d679 100644
--- a/clientv3/integration/watch_test.go
+++ b/clientv3/integration/watch_test.go
@@ -1133,3 +1133,24 @@ func TestWatchCancelDisconnected(t *testing.T) {
 		t.Fatal("took too long to cancel disconnected watcher")
 	}
 }
+
+// TestWatchClose ensures that close does not return error
+func TestWatchClose(t *testing.T) {
+	runWatchTest(t, testWatchClose)
+}
+
+func testWatchClose(t *testing.T, wctx *watchctx) {
+	ctx, cancel := context.WithCancel(context.Background())
+	wch := wctx.w.Watch(ctx, "a")
+	cancel()
+	if wch == nil {
+		t.Fatalf("expected watcher channel, got nil")
+	}
+	if wctx.w.Close() != nil {
+		t.Fatalf("watch did not close successfully")
+	}
+	wresp, ok := <-wch
+	if ok {
+		t.Fatalf("read wch got %v; expected closed channel", wresp)
+	}
+}
diff --git a/clientv3/watch.go b/clientv3/watch.go
index 8ec58bb14..d50acbca3 100644
--- a/clientv3/watch.go
+++ b/clientv3/watch.go
@@ -371,6 +371,10 @@ func (w *watcher) Close() (err error) {
 			err = werr
 		}
 	}
+	// Consider context.Canceled as a successful close
+	if err == context.Canceled {
+		err = nil
+	}
 	return err
 }