Extract more redundancy

pkg/registry/etcd_registry.go

@@ -71,7 +71,8 @@ func makePodKey(machine, podID string) string {
 func (registry *EtcdRegistry) ListPods(query labels.Query) ([]api.Pod, error) {
 	pods := []api.Pod{}
 	for _, machine := range registry.machines {
-		machinePods, err := registry.listPodsForMachine(machine)
+		var machinePods []api.Pod
+		err := registry.extractList("/registry/hosts/"+machine+"/pods", &machinePods)
 		if err != nil {
 			return pods, err
 		}
@@ -120,9 +121,30 @@ func (r *EtcdRegistry) extractList(key string, slicePtr interface{}) error {
 	return nil
 }
 
-func (registry *EtcdRegistry) listPodsForMachine(machine string) (pods []api.Pod, err error) {
+// Unmarshals json found at key into objPtr.
-	err = registry.extractList("/registry/hosts/"+machine+"/pods", &pods)
+func (r *EtcdRegistry) extractObj(key string, objPtr interface{}, ignoreNotFound bool) error {
-	return
+	response, err := r.etcdClient.Get(key, false, false)
+	returnZero := false
+	if err != nil {
+		if ignoreNotFound && isEtcdNotFound(err) {
+			returnZero = true
+		} else {
+			return err
+		}
+	}
+	if !returnZero && (response.Node == nil || len(response.Node.Value) == 0) {
+		if ignoreNotFound {
+			returnZero = true
+		} else {
+			return fmt.Errorf("key '%v' found no nodes field: %#v", key, response)
+		}
+	}
+	if returnZero {
+		pv := reflect.ValueOf(objPtr)
+		pv.Elem().Set(reflect.Zero(pv.Type().Elem()))
+		return nil
+	}
+	return json.Unmarshal([]byte(response.Node.Value), objPtr)
 }
 
 func (registry *EtcdRegistry) GetPod(podID string) (*api.Pod, error) {
@@ -134,19 +156,9 @@ func makeContainerKey(machine string) string {
 	return "/registry/hosts/" + machine + "/kubelet"
 }
 
-func (registry *EtcdRegistry) loadManifests(machine string) ([]api.ContainerManifest, error) {
+func (registry *EtcdRegistry) loadManifests(machine string) (manifests []api.ContainerManifest, err error) {
-	var manifests []api.ContainerManifest
+	err = registry.extractObj(makeContainerKey(machine), &manifests, true)
-	response, err := registry.etcdClient.Get(makeContainerKey(machine), false, false)
+	return
-
-	if err != nil {
-		if isEtcdNotFound(err) {
-			err = nil
-			manifests = []api.ContainerManifest{}
-		}
-	} else {
-		err = json.Unmarshal([]byte(response.Node.Value), &manifests)
-	}
-	return manifests, err
 }
 
 func (registry *EtcdRegistry) updateManifests(machine string, manifests []api.ContainerManifest) error {
@@ -227,23 +239,14 @@ func (registry *EtcdRegistry) deletePodFromMachine(machine, podID string) error
 	return err
 }
 
-func (registry *EtcdRegistry) getPodForMachine(machine, podID string) (api.Pod, error) {
+func (registry *EtcdRegistry) getPodForMachine(machine, podID string) (pod api.Pod, err error) {
 	key := makePodKey(machine, podID)
-	result, err := registry.etcdClient.Get(key, false, false)
+	err = registry.extractObj(key, &pod, false)
 	if err != nil {
-		if isEtcdNotFound(err) {
+		return
-			return api.Pod{}, fmt.Errorf("not found (%#v).", err)
-		} else {
-			return api.Pod{}, err
-		}
 	}
-	if result.Node == nil || len(result.Node.Value) == 0 {
-		return api.Pod{}, fmt.Errorf("no nodes field: %#v", result)
-	}
-	pod := api.Pod{}
-	err = json.Unmarshal([]byte(result.Node.Value), &pod)
 	pod.CurrentState.Host = machine
-	return pod, err
+	return
 }
 
 func (registry *EtcdRegistry) findPod(podID string) (api.Pod, string, error) {
@@ -286,19 +289,11 @@ func makeControllerKey(id string) string {
 func (registry *EtcdRegistry) GetController(controllerID string) (*api.ReplicationController, error) {
 	var controller api.ReplicationController
 	key := makeControllerKey(controllerID)
-	result, err := registry.etcdClient.Get(key, false, false)
+	err := registry.extractObj(key, &controller, false)
 	if err != nil {
-		if isEtcdNotFound(err) {
+		return nil, err
-			return nil, fmt.Errorf("controller %s not found", controllerID)
-		} else {
-			return nil, err
-		}
 	}
-	if result.Node == nil || len(result.Node.Value) == 0 {
+	return &controller, nil
-		return nil, fmt.Errorf("no nodes field: %#v", result)
-	}
-	err = json.Unmarshal([]byte(result.Node.Value), &controller)
-	return &controller, err
 }
 
 func (registry *EtcdRegistry) CreateController(controller api.ReplicationController) error {
@@ -344,20 +339,12 @@ func (registry *EtcdRegistry) CreateService(svc api.Service) error {
 
 func (registry *EtcdRegistry) GetService(name string) (*api.Service, error) {
 	key := makeServiceKey(name)
-	response, err := registry.etcdClient.Get(key, false, false)
-	if err != nil {
-		if isEtcdNotFound(err) {
-			return nil, fmt.Errorf("service %s was not found.", name)
-		} else {
-			return nil, err
-		}
-	}
 	var svc api.Service
-	err = json.Unmarshal([]byte(response.Node.Value), &svc)
+	err := registry.extractObj(key, &svc, false)
 	if err != nil {
 		return nil, err
 	}
-	return &svc, err
+	return &svc, nil
 }
 
 func (registry *EtcdRegistry) DeleteService(name string) error {