Skip leadership check if the etcd instance is active processing heartbeat

Signed-off-by: Benjamin Wang <benjamin.ahrtr@gmail.com>

server/etcdserver/server_test.go

@@ -29,6 +29,7 @@ import (
 
 	"github.com/coreos/go-semver/semver"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zaptest"
 
@@ -1538,3 +1539,45 @@ func TestWaitAppliedIndex(t *testing.T) {
 		})
 	}
 }
+
+func TestIsActive(t *testing.T) {
+	cases := []struct {
+		name                  string
+		tickMs                uint
+		durationSinceLastTick time.Duration
+		expectActive          bool
+	}{
+		{
+			name:                  "1.5*tickMs,active",
+			tickMs:                100,
+			durationSinceLastTick: 150 * time.Millisecond,
+			expectActive:          true,
+		},
+		{
+			name:                  "2*tickMs,active",
+			tickMs:                200,
+			durationSinceLastTick: 400 * time.Millisecond,
+			expectActive:          true,
+		},
+		{
+			name:                  "4*tickMs,not active",
+			tickMs:                150,
+			durationSinceLastTick: 600 * time.Millisecond,
+			expectActive:          false,
+		},
+	}
+
+	for _, tc := range cases {
+		s := EtcdServer{
+			Cfg: config.ServerConfig{
+				TickMs: tc.tickMs,
+			},
+			r: raftNode{
+				tickMu:       new(sync.RWMutex),
+				latestTickTs: time.Now().Add(-tc.durationSinceLastTick),
+			},
+		}
+
+		require.Equal(t, tc.expectActive, s.isActive())
+	}
+}