Snapshot cluster state for scheduler every loop

Change-Id: If9d162b83ccc914fe1b02e4689bfe1f4b264407f

cluster-autoscaler/core/static_autoscaler.go

@@ -194,6 +194,10 @@ func (a *StaticAutoscaler) RunOnce(currentTime time.Time) errors.AutoscalerError
 	klog.V(4).Info("Starting main loop")
 
 	stateUpdateStart := time.Now()
+	if err := a.PredicateChecker.SnapshotClusterState(); err != nil {
+		return errors.ToAutoscalerError(errors.ApiCallError, fmt.Errorf("could not snapshot cluster state in scheduler; %v", err))
+	}
+
 	allNodes, readyNodes, typedErr := a.obtainNodeLists(a.CloudProvider)
 	if typedErr != nil {
 		klog.Errorf("Failed to get node list: %v", typedErr)

cluster-autoscaler/simulator/predicates.go

@@ -63,6 +63,7 @@ type PredicateChecker struct {
 	predicates                []PredicateInfo
 	predicateMetadataProducer predicates.MetadataProducer
 	enableAffinityPredicate   bool
+	scheduler                 *scheduler.Scheduler
 }
 
 // We run some predicates first as they are cheap to check and they should be enough
@@ -162,6 +163,7 @@ func NewPredicateChecker(kubeClient kube_client.Interface, stop <-chan struct{})
 		predicates:                predicateList,
 		predicateMetadataProducer: sched.Algorithm.PredicateMetadataProducer(),
 		enableAffinityPredicate:   true,
+		scheduler:                 sched,
 	}, nil
 }
 
@@ -199,6 +201,15 @@ func NewCustomTestPredicateChecker(predicateInfos []PredicateInfo) *PredicateChe
 	}
 }
 
+// SnapshotClusterState updates cluster snapshot used by the predicate checker.
+// It should be called every CA loop iteration.
+func (p *PredicateChecker) SnapshotClusterState() error {
+	if p.scheduler != nil {
+		return p.scheduler.Algorithm.Snapshot()
+	}
+	return nil
+}
+
 // SetAffinityPredicateEnabled can be used to enable or disable checking MatchInterPodAffinity
 // predicate. This will cause incorrect CA behavior if there is at least a single pod in
 // cluster using affinity/antiaffinity. However, checking affinity predicate is extremely