From 5a4a095e29627f13c480b8a1140bc0d628107aef Mon Sep 17 00:00:00 2001
From: Hongchao Deng <hongchaodeng1@gmail.com>
Date: Fri, 16 Sep 2016 14:51:17 -0700
Subject: [PATCH] etcd watcher: centralize error handling

---
 pkg/storage/etcd3/watcher.go      | 12 ++++--------
 pkg/storage/etcd3/watcher_test.go | 23 +++++++++++++----------
 2 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/pkg/storage/etcd3/watcher.go b/pkg/storage/etcd3/watcher.go
index c2880a4205..544787925b 100644
--- a/pkg/storage/etcd3/watcher.go
+++ b/pkg/storage/etcd3/watcher.go
@@ -31,8 +31,6 @@ import (
 	etcdrpc "github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
 	"github.com/golang/glog"
 	"golang.org/x/net/context"
-	"google.golang.org/grpc"
-	"google.golang.org/grpc/codes"
 )
 
 const (
@@ -109,6 +107,10 @@ func (wc *watchChan) run() {
 
 	select {
 	case err := <-wc.errChan:
+		if err == context.Canceled {
+			wc.cancel() // just in case
+			break
+		}
 		errResult := parseError(err)
 		if errResult != nil {
 			// error result is guaranteed to be received by user before closing ResultChan.
@@ -294,12 +296,6 @@ func parseError(err error) *watch.Event {
 }
 
 func (wc *watchChan) sendError(err error) {
-	// Context.canceled is an expected behavior.
-	// We should just stop all goroutines in watchChan without returning error.
-	// TODO: etcd client should return context.Canceled instead of grpc specific error.
-	if grpc.Code(err) == codes.Canceled || err == context.Canceled {
-		return
-	}
 	select {
 	case wc.errChan <- err:
 	case <-wc.ctx.Done():
diff --git a/pkg/storage/etcd3/watcher_test.go b/pkg/storage/etcd3/watcher_test.go
index 8781750e03..4f77e9f4b4 100644
--- a/pkg/storage/etcd3/watcher_test.go
+++ b/pkg/storage/etcd3/watcher_test.go
@@ -196,17 +196,20 @@ func TestWatchContextCancel(t *testing.T) {
 	defer cluster.Terminate(t)
 	canceledCtx, cancel := context.WithCancel(ctx)
 	cancel()
-	w := store.watcher.createWatchChan(canceledCtx, "/abc", 0, false, storage.Everything)
-	// When we do a client.Get with a canceled context, it will return error.
-	// Nonetheless, when we try to send it over internal errChan, we should detect
-	// it's context canceled and not send it.
-	err := w.sync()
-	w.ctx = ctx
-	w.sendError(err)
+	// When we watch with a canceled context, we should detect that it's context canceled.
+	// We won't take it as error and also close the watcher.
+	w, err := store.watcher.Watch(canceledCtx, "/abc", 0, false, storage.Everything)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	select {
-	case err := <-w.errChan:
-		t.Errorf("cancelling context shouldn't return any error. Err: %v", err)
-	default:
+	case _, ok := <-w.ResultChan():
+		if ok {
+			t.Error("ResultChan() should be closed")
+		}
+	case <-time.After(wait.ForeverTestTimeout):
+		t.Errorf("timeout after %v", wait.ForeverTestTimeout)
 	}
 }