Move scheduler code out of plugin directory.

This moves plugin/pkg/scheduler to pkg/scheduler and
plugin/cmd/kube-scheduler to cmd/kube-scheduler.

Bulk of the work was done with gomvpkg, except for kube-scheduler main
package.

pkg/scheduler/algorithm/priorities/node_affinity.go

@@ -0,0 +1,77 @@
+/*
+Copyright 2015 The Kubernetes Authors.
+
+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 priorities
+
+import (
+	"fmt"
+
+	"k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/labels"
+	v1helper "k8s.io/kubernetes/pkg/apis/core/v1/helper"
+	schedulerapi "k8s.io/kubernetes/pkg/scheduler/api"
+	"k8s.io/kubernetes/pkg/scheduler/schedulercache"
+)
+
+// CalculateNodeAffinityPriority prioritizes nodes according to node affinity scheduling preferences
+// indicated in PreferredDuringSchedulingIgnoredDuringExecution. Each time a node match a preferredSchedulingTerm,
+// it will a get an add of preferredSchedulingTerm.Weight. Thus, the more preferredSchedulingTerms
+// the node satisfies and the more the preferredSchedulingTerm that is satisfied weights, the higher
+// score the node gets.
+func CalculateNodeAffinityPriorityMap(pod *v1.Pod, meta interface{}, nodeInfo *schedulercache.NodeInfo) (schedulerapi.HostPriority, error) {
+	node := nodeInfo.Node()
+	if node == nil {
+		return schedulerapi.HostPriority{}, fmt.Errorf("node not found")
+	}
+
+	var affinity *v1.Affinity
+	if priorityMeta, ok := meta.(*priorityMetadata); ok {
+		affinity = priorityMeta.affinity
+	} else {
+		// We couldn't parse metadata - fallback to the podspec.
+		affinity = pod.Spec.Affinity
+	}
+
+	var count int32
+	// A nil element of PreferredDuringSchedulingIgnoredDuringExecution matches no objects.
+	// An element of PreferredDuringSchedulingIgnoredDuringExecution that refers to an
+	// empty PreferredSchedulingTerm matches all objects.
+	if affinity != nil && affinity.NodeAffinity != nil && affinity.NodeAffinity.PreferredDuringSchedulingIgnoredDuringExecution != nil {
+		// Match PreferredDuringSchedulingIgnoredDuringExecution term by term.
+		for i := range affinity.NodeAffinity.PreferredDuringSchedulingIgnoredDuringExecution {
+			preferredSchedulingTerm := &affinity.NodeAffinity.PreferredDuringSchedulingIgnoredDuringExecution[i]
+			if preferredSchedulingTerm.Weight == 0 {
+				continue
+			}
+
+			// TODO: Avoid computing it for all nodes if this becomes a performance problem.
+			nodeSelector, err := v1helper.NodeSelectorRequirementsAsSelector(preferredSchedulingTerm.Preference.MatchExpressions)
+			if err != nil {
+				return schedulerapi.HostPriority{}, err
+			}
+			if nodeSelector.Matches(labels.Set(node.Labels)) {
+				count += preferredSchedulingTerm.Weight
+			}
+		}
+	}
+
+	return schedulerapi.HostPriority{
+		Host:  node.Name,
+		Score: int(count),
+	}, nil
+}
+
+var CalculateNodeAffinityPriorityReduce = NormalizeReduce(schedulerapi.MaxPriority, false)