Add a system modeler to scheduler

So it can try to predict the effect its bindings will have.

plugin/pkg/scheduler/modeler_test.go

@@ -0,0 +1,111 @@
+/*
+Copyright 2015 Google Inc. 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 scheduler
+
+import (
+	"testing"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/cache"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
+)
+
+type nn struct {
+	namespace, name string
+}
+
+type names []nn
+
+func (ids names) list() []api.Pod {
+	out := make([]api.Pod, len(ids))
+	for i, id := range ids {
+		out[i] = api.Pod{
+			ObjectMeta: api.ObjectMeta{
+				Namespace: id.namespace,
+				Name:      id.name,
+			},
+		}
+	}
+	return out
+}
+
+func (ids names) has(pod *api.Pod) bool {
+	for _, id := range ids {
+		if pod.Namespace == id.namespace && pod.Name == id.name {
+			return true
+		}
+	}
+	return false
+}
+
+func TestModeler(t *testing.T) {
+	table := []struct {
+		queuedPods    []api.Pod
+		scheduledPods []api.Pod
+		assumedPods   []api.Pod
+		expectPods    names
+	}{
+		{
+			queuedPods:    names{}.list(),
+			scheduledPods: names{{"default", "foo"}, {"custom", "foo"}}.list(),
+			assumedPods:   names{{"default", "foo"}}.list(),
+			expectPods:    names{{"default", "foo"}, {"custom", "foo"}},
+		}, {
+			queuedPods:    names{}.list(),
+			scheduledPods: names{{"default", "foo"}}.list(),
+			assumedPods:   names{{"default", "foo"}, {"custom", "foo"}}.list(),
+			expectPods:    names{{"default", "foo"}, {"custom", "foo"}},
+		}, {
+			queuedPods:    names{{"custom", "foo"}}.list(),
+			scheduledPods: names{{"default", "foo"}}.list(),
+			assumedPods:   names{{"default", "foo"}, {"custom", "foo"}}.list(),
+			expectPods:    names{{"default", "foo"}},
+		},
+	}
+
+	for _, item := range table {
+		q := &cache.StoreToPodLister{cache.NewStore(cache.MetaNamespaceKeyFunc)}
+		for i := range item.queuedPods {
+			q.Store.Add(&item.queuedPods[i])
+		}
+		s := &cache.StoreToPodLister{cache.NewStore(cache.MetaNamespaceKeyFunc)}
+		for i := range item.scheduledPods {
+			s.Store.Add(&item.scheduledPods[i])
+		}
+		m := NewSimpleModeler(q, s)
+		for i := range item.assumedPods {
+			m.AssumePod(&item.assumedPods[i])
+		}
+
+		list, err := m.PodLister().List(labels.Everything())
+		if err != nil {
+			t.Errorf("unexpected error: %v", err)
+		}
+
+		found := 0
+		for _, pod := range list {
+			if item.expectPods.has(&pod) {
+				found++
+			} else {
+				t.Errorf("found unexpected pod %#v", pod)
+			}
+		}
+		if e, a := item.expectPods, found; len(e) != a {
+			t.Errorf("Expected pods:\n%+v\nFound pods:\n%v\n", e, list)
+		}
+	}
+}