Fixes #61 - monitor.history=0 panic

CHANGELOG.md

@@ -17,6 +17,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - `rest/client.NewV1` renamed to `New`
 - `rest/client` package now embeds the shared `rest/model` structs into its own
   types
+- Fixed panic when `monitor.history` set to 0
 
 [1.2.0-rc1] - 2017-01-29
 ------------------------

msghub/hub.go

@@ -63,6 +63,7 @@ func New(ctx context.Context, historyLen int) *Hub {
 // history buffer and then relayed to all registered listeners.
 func (hub *Hub) Dispatch(msg Message) {
 	hub.opChan <- func(h *Hub) {
+		if h.history != nil {
 			// Add to history buffer
 			h.history.Value = msg
 			h.history = h.history.Next()
@@ -74,6 +75,7 @@ func (hub *Hub) Dispatch(msg Message) {
 			}
 		}
 	}
+}
 
 // AddListener registers a listener to receive broadcasted messages.
 func (hub *Hub) AddListener(l Listener) {

msghub/hub_test.go

@@ -60,6 +60,17 @@ func TestHubNew(t *testing.T) {
 	}
 }
 
+func TestHubZeroLen(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	hub := New(ctx, 0)
+	m := Message{}
+	for i := 0; i < 100; i++ {
+		hub.Dispatch(m)
+	}
+	// Just making sure Hub doesn't panic
+}
+
 func TestHubZeroListeners(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()