Refactor package controller

pkg/controller/replication/replication_controller_utils.go

@@ -0,0 +1,72 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package replication
+
+import (
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
+	"github.com/golang/glog"
+)
+
+// updateReplicaCount attempts to update the Status.Replicas of the given controller, with a single GET/PUT retry.
+func updateReplicaCount(rcClient client.ReplicationControllerInterface, controller api.ReplicationController, numReplicas int) (updateErr error) {
+	// This is the steady state. It happens when the rc doesn't have any expectations, since
+	// we do a periodic relist every 30s. If the generations differ but the replicas are
+	// the same, a caller might've resized to the same replica count.
+	if controller.Status.Replicas == numReplicas &&
+		controller.Generation == controller.Status.ObservedGeneration {
+		return nil
+	}
+	// Save the generation number we acted on, otherwise we might wrongfully indicate
+	// that we've seen a spec update when we retry.
+	// TODO: This can clobber an update if we allow multiple agents to write to the
+	// same status.
+	generation := controller.Generation
+
+	var getErr error
+	for i, rc := 0, &controller; ; i++ {
+		glog.V(4).Infof("Updating replica count for rc: %v, %d->%d (need %d), sequence No: %v->%v",
+			controller.Name, controller.Status.Replicas, numReplicas, controller.Spec.Replicas, controller.Status.ObservedGeneration, generation)
+
+		rc.Status = api.ReplicationControllerStatus{Replicas: numReplicas, ObservedGeneration: generation}
+		_, updateErr = rcClient.Update(rc)
+		if updateErr == nil || i >= statusUpdateRetries {
+			return updateErr
+		}
+		// Update the controller with the latest resource version for the next poll
+		if rc, getErr = rcClient.Get(controller.Name); getErr != nil {
+			// If the GET fails we can't trust status.Replicas anymore. This error
+			// is bound to be more interesting than the update failure.
+			return getErr
+		}
+	}
+	// Failed 2 updates one of which was with the latest controller, return the update error
+	return
+}
+
+// OverlappingControllers sorts a list of controllers by creation timestamp, using their names as a tie breaker.
+type overlappingControllers []api.ReplicationController
+
+func (o overlappingControllers) Len() int      { return len(o) }
+func (o overlappingControllers) Swap(i, j int) { o[i], o[j] = o[j], o[i] }
+
+func (o overlappingControllers) Less(i, j int) bool {
+	if o[i].CreationTimestamp.Equal(o[j].CreationTimestamp) {
+		return o[i].Name < o[j].Name
+	}
+	return o[i].CreationTimestamp.Before(o[j].CreationTimestamp)
+}