Merge pull request #21016 from hongchaodeng/cache

Auto commit by PR queue bot

plugin/pkg/scheduler/schedulercache/cache.go

@@ -0,0 +1,264 @@
+/*
+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 schedulercache
+
+import (
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/golang/glog"
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/labels"
+	"k8s.io/kubernetes/pkg/util/wait"
+)
+
+var (
+	cleanAssumedPeriod = 1 * time.Second
+)
+
+// New returns a Cache implementation.
+// It automatically starts a go routine that manages expiration of assumed pods.
+// "ttl" is how long the assumed pod will get expired.
+// "stop" is the channel that would close the background goroutine.
+func New(ttl time.Duration, stop chan struct{}) Cache {
+	cache := newSchedulerCache(ttl, cleanAssumedPeriod, stop)
+	cache.run()
+	return cache
+}
+
+type schedulerCache struct {
+	stop   chan struct{}
+	ttl    time.Duration
+	period time.Duration
+
+	// This mutex guards all fields within this cache struct.
+	mu sync.Mutex
+	// a set of assumed pod keys.
+	// The key could further be used to get an entry in podStates.
+	assumedPods map[string]bool
+	// a map from pod key to podState.
+	podStates map[string]*podState
+	nodes     map[string]*NodeInfo
+}
+
+type podState struct {
+	pod *api.Pod
+	// Used by assumedPod to determinate expiration.
+	deadline time.Time
+}
+
+func newSchedulerCache(ttl, period time.Duration, stop chan struct{}) *schedulerCache {
+	return &schedulerCache{
+		ttl:    ttl,
+		period: period,
+		stop:   stop,
+
+		nodes:       make(map[string]*NodeInfo),
+		assumedPods: make(map[string]bool),
+		podStates:   make(map[string]*podState),
+	}
+}
+
+func (cache *schedulerCache) GetNodeNameToInfoMap() (map[string]*NodeInfo, error) {
+	nodeNameToInfo := make(map[string]*NodeInfo)
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+	for name, info := range cache.nodes {
+		nodeNameToInfo[name] = info.Clone()
+	}
+	return nodeNameToInfo, nil
+}
+
+func (cache *schedulerCache) List(selector labels.Selector) ([]*api.Pod, error) {
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+	var pods []*api.Pod
+	for _, info := range cache.nodes {
+		for _, pod := range info.pods {
+			if selector.Matches(labels.Set(pod.Labels)) {
+				pods = append(pods, pod)
+			}
+		}
+	}
+	return pods, nil
+}
+
+func (cache *schedulerCache) AssumePodIfBindSucceed(pod *api.Pod, bind func() bool) error {
+	return cache.assumePodIfBindSucceed(pod, bind, time.Now())
+}
+
+// assumePodScheduled exists for making test deterministic by taking time as input argument.
+func (cache *schedulerCache) assumePodIfBindSucceed(pod *api.Pod, bind func() bool, now time.Time) error {
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+
+	if !bind() {
+		return nil
+	}
+
+	key, err := getPodKey(pod)
+	if err != nil {
+		return err
+	}
+	if _, ok := cache.podStates[key]; ok {
+		return fmt.Errorf("pod state wasn't initial but get assumed. Pod key: %v", key)
+	}
+
+	cache.addPod(pod)
+	ps := &podState{
+		pod:      pod,
+		deadline: now.Add(cache.ttl),
+	}
+	cache.podStates[key] = ps
+	cache.assumedPods[key] = true
+	return nil
+}
+
+func (cache *schedulerCache) AddPod(pod *api.Pod) error {
+	key, err := getPodKey(pod)
+	if err != nil {
+		return err
+	}
+
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+
+	_, ok := cache.podStates[key]
+	switch {
+	case ok && cache.assumedPods[key]:
+		delete(cache.assumedPods, key)
+	case !ok:
+		// Pod was expired. We should add it back.
+		cache.addPod(pod)
+	default:
+		return fmt.Errorf("pod was already in added state. Pod key: %v", key)
+	}
+	return nil
+}
+
+func (cache *schedulerCache) UpdatePod(oldPod, newPod *api.Pod) error {
+	key, err := getPodKey(oldPod)
+	if err != nil {
+		return err
+	}
+
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+
+	_, ok := cache.podStates[key]
+	switch {
+	// An assumed pod won't have Update/Remove event. It needs to have Add event
+	// before Update event, in which case the state would change from Assumed to Added.
+	case ok && !cache.assumedPods[key]:
+		if err := cache.updatePod(oldPod, newPod); err != nil {
+			return err
+		}
+	default:
+		return fmt.Errorf("pod state wasn't added but get updated. Pod key: %v", key)
+	}
+	return nil
+}
+
+func (cache *schedulerCache) updatePod(oldPod, newPod *api.Pod) error {
+	if err := cache.deletePod(oldPod); err != nil {
+		return err
+	}
+	cache.addPod(newPod)
+	return nil
+}
+
+func (cache *schedulerCache) addPod(pod *api.Pod) {
+	n, ok := cache.nodes[pod.Spec.NodeName]
+	if !ok {
+		n = NewNodeInfo()
+		cache.nodes[pod.Spec.NodeName] = n
+	}
+	n.addPod(pod)
+}
+
+func (cache *schedulerCache) deletePod(pod *api.Pod) error {
+	n := cache.nodes[pod.Spec.NodeName]
+	if err := n.removePod(pod); err != nil {
+		return err
+	}
+	if len(n.pods) == 0 {
+		delete(cache.nodes, pod.Spec.NodeName)
+	}
+	return nil
+}
+
+func (cache *schedulerCache) RemovePod(pod *api.Pod) error {
+	key, err := getPodKey(pod)
+	if err != nil {
+		return err
+	}
+
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+
+	_, ok := cache.podStates[key]
+	switch {
+	// An assumed pod won't have Delete/Remove event. It needs to have Add event
+	// before Remove event, in which case the state would change from Assumed to Added.
+	case ok && !cache.assumedPods[key]:
+		err := cache.deletePod(pod)
+		if err != nil {
+			return err
+		}
+		delete(cache.podStates, key)
+	default:
+		return fmt.Errorf("pod state wasn't added but get removed. Pod key: %v", key)
+	}
+	return nil
+}
+
+func (cache *schedulerCache) run() {
+	go wait.Until(cache.cleanupExpiredAssumedPods, cache.period, cache.stop)
+}
+
+func (cache *schedulerCache) cleanupExpiredAssumedPods() {
+	cache.cleanupAssumedPods(time.Now())
+}
+
+// cleanupAssumedPods exists for making test deterministic by taking time as input argument.
+func (cache *schedulerCache) cleanupAssumedPods(now time.Time) {
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+
+	// The size of assumedPods should be small
+	for key := range cache.assumedPods {
+		ps, ok := cache.podStates[key]
+		if !ok {
+			panic("Key found in assumed set but not in podStates. Potentially a logical error.")
+		}
+		if now.After(ps.deadline) {
+			if err := cache.expirePod(key, ps); err != nil {
+				glog.Errorf(" expirePod failed for %s: %v", key, err)
+			}
+		}
+	}
+}
+
+func (cache *schedulerCache) expirePod(key string, ps *podState) error {
+	if err := cache.deletePod(ps.pod); err != nil {
+		return err
+	}
+	delete(cache.assumedPods, key)
+	delete(cache.podStates, key)
+	return nil
+}

plugin/pkg/scheduler/schedulercache/cache_test.go

@@ -0,0 +1,482 @@
+/*
+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 schedulercache
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+	"time"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/resource"
+	"k8s.io/kubernetes/pkg/labels"
+	priorityutil "k8s.io/kubernetes/plugin/pkg/scheduler/algorithm/priorities/util"
+)
+
+// TestAssumePodScheduled tests that after a pod is assumed, its information is aggregated
+// on node level.
+func TestAssumePodScheduled(t *testing.T) {
+	nodeName := "node"
+	testPods := []*api.Pod{
+		makeBasePod(nodeName, "test", "100m", "500", []api.ContainerPort{{HostPort: 80}}),
+		makeBasePod(nodeName, "test-1", "100m", "500", []api.ContainerPort{{HostPort: 80}}),
+		makeBasePod(nodeName, "test-2", "200m", "1Ki", []api.ContainerPort{{HostPort: 8080}}),
+		makeBasePod(nodeName, "test-nonzero", "", "", []api.ContainerPort{{HostPort: 80}}),
+	}
+
+	tests := []struct {
+		pods []*api.Pod
+
+		wNodeInfo *NodeInfo
+	}{{
+		pods: []*api.Pod{testPods[0]},
+		wNodeInfo: &NodeInfo{
+			requestedResource: &Resource{
+				MilliCPU: 100,
+				Memory:   500,
+			},
+			nonzeroRequest: &Resource{
+				MilliCPU: 100,
+				Memory:   500,
+			},
+			pods: []*api.Pod{testPods[0]},
+		},
+	}, {
+		pods: []*api.Pod{testPods[1], testPods[2]},
+		wNodeInfo: &NodeInfo{
+			requestedResource: &Resource{
+				MilliCPU: 300,
+				Memory:   1524,
+			},
+			nonzeroRequest: &Resource{
+				MilliCPU: 300,
+				Memory:   1524,
+			},
+			pods: []*api.Pod{testPods[1], testPods[2]},
+		},
+	}, { // test non-zero request
+		pods: []*api.Pod{testPods[3]},
+		wNodeInfo: &NodeInfo{
+			requestedResource: &Resource{
+				MilliCPU: 0,
+				Memory:   0,
+			},
+			nonzeroRequest: &Resource{
+				MilliCPU: priorityutil.DefaultMilliCpuRequest,
+				Memory:   priorityutil.DefaultMemoryRequest,
+			},
+			pods: []*api.Pod{testPods[3]},
+		},
+	}}
+
+	for i, tt := range tests {
+		cache := newSchedulerCache(time.Second, time.Second, nil)
+		for _, pod := range tt.pods {
+			if err := cache.AssumePodIfBindSucceed(pod, alwaysTrue); err != nil {
+				t.Fatalf("AssumePodScheduled failed: %v", err)
+			}
+		}
+		n := cache.nodes[nodeName]
+		if !reflect.DeepEqual(n, tt.wNodeInfo) {
+			t.Errorf("#%d: node info get=%s, want=%s", i, n, tt.wNodeInfo)
+		}
+	}
+}
+
+type testExpirePodStruct struct {
+	pod         *api.Pod
+	assumedTime time.Time
+}
+
+// TestExpirePod tests that assumed pods will be removed if expired.
+// The removal will be reflected in node info.
+func TestExpirePod(t *testing.T) {
+	nodeName := "node"
+	testPods := []*api.Pod{
+		makeBasePod(nodeName, "test-1", "100m", "500", []api.ContainerPort{{HostPort: 80}}),
+		makeBasePod(nodeName, "test-2", "200m", "1Ki", []api.ContainerPort{{HostPort: 8080}}),
+	}
+	now := time.Now()
+	ttl := 10 * time.Second
+	tests := []struct {
+		pods        []*testExpirePodStruct
+		cleanupTime time.Time
+
+		wNodeInfo *NodeInfo
+	}{{ // assumed pod would expires
+		pods: []*testExpirePodStruct{
+			{pod: testPods[0], assumedTime: now},
+		},
+		cleanupTime: now.Add(2 * ttl),
+		wNodeInfo:   nil,
+	}, { // first one would expire, second one would not.
+		pods: []*testExpirePodStruct{
+			{pod: testPods[0], assumedTime: now},
+			{pod: testPods[1], assumedTime: now.Add(3 * ttl / 2)},
+		},
+		cleanupTime: now.Add(2 * ttl),
+		wNodeInfo: &NodeInfo{
+			requestedResource: &Resource{
+				MilliCPU: 200,
+				Memory:   1024,
+			},
+			nonzeroRequest: &Resource{
+				MilliCPU: 200,
+				Memory:   1024,
+			},
+			pods: []*api.Pod{testPods[1]},
+		},
+	}}
+
+	for i, tt := range tests {
+		cache := newSchedulerCache(ttl, time.Second, nil)
+
+		for _, pod := range tt.pods {
+			if err := cache.assumePodIfBindSucceed(pod.pod, alwaysTrue, pod.assumedTime); err != nil {
+				t.Fatalf("assumePod failed: %v", err)
+			}
+		}
+		// pods that have assumedTime + ttl < cleanupTime will get expired and removed
+		cache.cleanupAssumedPods(tt.cleanupTime)
+		n := cache.nodes[nodeName]
+		if !reflect.DeepEqual(n, tt.wNodeInfo) {
+			t.Errorf("#%d: node info get=%s, want=%s", i, n, tt.wNodeInfo)
+		}
+	}
+}
+
+// TestAddPodWillConfirm tests that a pod being Add()ed will be confirmed if assumed.
+// The pod info should still exist after manually expiring unconfirmed pods.
+func TestAddPodWillConfirm(t *testing.T) {
+	nodeName := "node"
+	now := time.Now()
+	ttl := 10 * time.Second
+
+	testPods := []*api.Pod{
+		makeBasePod(nodeName, "test-1", "100m", "500", []api.ContainerPort{{HostPort: 80}}),
+		makeBasePod(nodeName, "test-2", "200m", "1Ki", []api.ContainerPort{{HostPort: 8080}}),
+	}
+	tests := []struct {
+		podsToAssume []*api.Pod
+		podsToAdd    []*api.Pod
+
+		wNodeInfo *NodeInfo
+	}{{ // two pod were assumed at same time. But first one is called Add() and gets confirmed.
+		podsToAssume: []*api.Pod{testPods[0], testPods[1]},
+		podsToAdd:    []*api.Pod{testPods[0]},
+		wNodeInfo: &NodeInfo{
+			requestedResource: &Resource{
+				MilliCPU: 100,
+				Memory:   500,
+			},
+			nonzeroRequest: &Resource{
+				MilliCPU: 100,
+				Memory:   500,
+			},
+			pods: []*api.Pod{testPods[0]},
+		},
+	}}
+
+	for i, tt := range tests {
+		cache := newSchedulerCache(ttl, time.Second, nil)
+		for _, podToAssume := range tt.podsToAssume {
+			if err := cache.assumePodIfBindSucceed(podToAssume, alwaysTrue, now); err != nil {
+				t.Fatalf("assumePod failed: %v", err)
+			}
+		}
+		for _, podToAdd := range tt.podsToAdd {
+			if err := cache.AddPod(podToAdd); err != nil {
+				t.Fatalf("AddPod failed: %v", err)
+			}
+		}
+		cache.cleanupAssumedPods(now.Add(2 * ttl))
+		// check after expiration. confirmed pods shouldn't be expired.
+		n := cache.nodes[nodeName]
+		if !reflect.DeepEqual(n, tt.wNodeInfo) {
+			t.Errorf("#%d: node info get=%s, want=%s", i, n, tt.wNodeInfo)
+		}
+	}
+}
+
+// TestAddPodAfterExpiration tests that a pod being Add()ed will be added back if expired.
+func TestAddPodAfterExpiration(t *testing.T) {
+	nodeName := "node"
+	ttl := 10 * time.Second
+	basePod := makeBasePod(nodeName, "test", "100m", "500", []api.ContainerPort{{HostPort: 80}})
+	tests := []struct {
+		pod *api.Pod
+
+		wNodeInfo *NodeInfo
+	}{{
+		pod: basePod,
+		wNodeInfo: &NodeInfo{
+			requestedResource: &Resource{
+				MilliCPU: 100,
+				Memory:   500,
+			},
+			nonzeroRequest: &Resource{
+				MilliCPU: 100,
+				Memory:   500,
+			},
+			pods: []*api.Pod{basePod},
+		},
+	}}
+
+	now := time.Now()
+	for i, tt := range tests {
+		cache := newSchedulerCache(ttl, time.Second, nil)
+		if err := cache.assumePodIfBindSucceed(tt.pod, alwaysTrue, now); err != nil {
+			t.Fatalf("assumePod failed: %v", err)
+		}
+		cache.cleanupAssumedPods(now.Add(2 * ttl))
+		// It should be expired and removed.
+		n := cache.nodes[nodeName]
+		if n != nil {
+			t.Errorf("#%d: expecting nil node info, but get=%v", i, n)
+		}
+		if err := cache.AddPod(tt.pod); err != nil {
+			t.Fatalf("AddPod failed: %v", err)
+		}
+		// check after expiration. confirmed pods shouldn't be expired.
+		n = cache.nodes[nodeName]
+		if !reflect.DeepEqual(n, tt.wNodeInfo) {
+			t.Errorf("#%d: node info get=%s, want=%s", i, n, tt.wNodeInfo)
+		}
+	}
+}
+
+// TestUpdatePod tests that a pod will be updated if added before.
+func TestUpdatePod(t *testing.T) {
+	nodeName := "node"
+	ttl := 10 * time.Second
+	testPods := []*api.Pod{
+		makeBasePod(nodeName, "test", "100m", "500", []api.ContainerPort{{HostPort: 80}}),
+		makeBasePod(nodeName, "test", "200m", "1Ki", []api.ContainerPort{{HostPort: 8080}}),
+	}
+	tests := []struct {
+		podsToAssume []*api.Pod
+		podsToAdd    []*api.Pod
+		podsToUpdate []*api.Pod
+
+		wNodeInfo []*NodeInfo
+	}{{ // Pod is assumed and added. Then it would be updated twice.
+		podsToAssume: []*api.Pod{testPods[0]},
+		podsToAdd:    []*api.Pod{testPods[0]},
+		podsToUpdate: []*api.Pod{testPods[0], testPods[1], testPods[0]},
+		wNodeInfo: []*NodeInfo{{
+			requestedResource: &Resource{
+				MilliCPU: 200,
+				Memory:   1024,
+			},
+			nonzeroRequest: &Resource{
+				MilliCPU: 200,
+				Memory:   1024,
+			},
+			pods: []*api.Pod{testPods[1]},
+		}, {
+			requestedResource: &Resource{
+				MilliCPU: 100,
+				Memory:   500,
+			},
+			nonzeroRequest: &Resource{
+				MilliCPU: 100,
+				Memory:   500,
+			},
+			pods: []*api.Pod{testPods[0]},
+		}},
+	}}
+
+	now := time.Now()
+	for _, tt := range tests {
+		cache := newSchedulerCache(ttl, time.Second, nil)
+		for _, podToAssume := range tt.podsToAssume {
+			if err := cache.assumePodIfBindSucceed(podToAssume, alwaysTrue, now); err != nil {
+				t.Fatalf("assumePod failed: %v", err)
+			}
+		}
+		for _, podToAdd := range tt.podsToAdd {
+			if err := cache.AddPod(podToAdd); err != nil {
+				t.Fatalf("AddPod failed: %v", err)
+			}
+		}
+
+		for i := range tt.podsToUpdate {
+			if i == 0 {
+				continue
+			}
+			if err := cache.UpdatePod(tt.podsToUpdate[i-1], tt.podsToUpdate[i]); err != nil {
+				t.Fatalf("UpdatePod failed: %v", err)
+			}
+			// check after expiration. confirmed pods shouldn't be expired.
+			n := cache.nodes[nodeName]
+			if !reflect.DeepEqual(n, tt.wNodeInfo[i-1]) {
+				t.Errorf("#%d: node info get=%s, want=%s", i-1, n, tt.wNodeInfo)
+			}
+		}
+	}
+}
+
+// TestRemovePod tests after added pod is removed, its information should also be subtracted.
+func TestRemovePod(t *testing.T) {
+	nodeName := "node"
+	basePod := makeBasePod(nodeName, "test", "100m", "500", []api.ContainerPort{{HostPort: 80}})
+	tests := []struct {
+		pod *api.Pod
+
+		wNodeInfo *NodeInfo
+	}{{
+		pod: basePod,
+		wNodeInfo: &NodeInfo{
+			requestedResource: &Resource{
+				MilliCPU: 100,
+				Memory:   500,
+			},
+			nonzeroRequest: &Resource{
+				MilliCPU: 100,
+				Memory:   500,
+			},
+			pods: []*api.Pod{basePod},
+		},
+	}}
+
+	for i, tt := range tests {
+		cache := newSchedulerCache(time.Second, time.Second, nil)
+		if err := cache.AssumePodIfBindSucceed(tt.pod, alwaysTrue); err != nil {
+			t.Fatalf("assumePod failed: %v", err)
+		}
+		if err := cache.AddPod(tt.pod); err != nil {
+			t.Fatalf("AddPod failed: %v", err)
+		}
+		n := cache.nodes[nodeName]
+		if !reflect.DeepEqual(n, tt.wNodeInfo) {
+			t.Errorf("#%d: node info get=%s, want=%s", i, n, tt.wNodeInfo)
+		}
+
+		if err := cache.RemovePod(tt.pod); err != nil {
+			t.Fatalf("RemovePod failed: %v", err)
+		}
+
+		n = cache.nodes[nodeName]
+		if n != nil {
+			t.Errorf("#%d: expecting pod deleted and nil node info, get=%s", i, n)
+		}
+	}
+}
+
+func BenchmarkGetNodeNameToInfoMap1kNodes30kPods(b *testing.B) {
+	cache := setupCacheOf1kNodes30kPods(b)
+	b.ResetTimer()
+	for n := 0; n < b.N; n++ {
+		cache.GetNodeNameToInfoMap()
+	}
+}
+
+func BenchmarkList1kNodes30kPods(b *testing.B) {
+	cache := setupCacheOf1kNodes30kPods(b)
+	b.ResetTimer()
+	for n := 0; n < b.N; n++ {
+		cache.List(labels.Everything())
+	}
+}
+
+func BenchmarkExpire100Pods(b *testing.B) {
+	benchmarkExpire(b, 100)
+}
+
+func BenchmarkExpire1kPods(b *testing.B) {
+	benchmarkExpire(b, 1000)
+}
+
+func BenchmarkExpire10kPods(b *testing.B) {
+	benchmarkExpire(b, 10000)
+}
+
+func benchmarkExpire(b *testing.B, podNum int) {
+	now := time.Now()
+	for n := 0; n < b.N; n++ {
+		b.StopTimer()
+		cache := setupCacheWithAssumedPods(b, podNum, now)
+		b.StartTimer()
+		cache.cleanupAssumedPods(now.Add(2 * time.Second))
+	}
+}
+
+func makeBasePod(nodeName, objName, cpu, mem string, ports []api.ContainerPort) *api.Pod {
+	req := api.ResourceList{}
+	if cpu != "" {
+		req = api.ResourceList{
+			api.ResourceCPU:    resource.MustParse(cpu),
+			api.ResourceMemory: resource.MustParse(mem),
+		}
+	}
+	return &api.Pod{
+		ObjectMeta: api.ObjectMeta{
+			Namespace: "node_info_cache_test",
+			Name:      objName,
+		},
+		Spec: api.PodSpec{
+			Containers: []api.Container{{
+				Resources: api.ResourceRequirements{
+					Requests: req,
+				},
+				Ports: ports,
+			}},
+			NodeName: nodeName,
+		},
+	}
+}
+
+func setupCacheOf1kNodes30kPods(b *testing.B) Cache {
+	cache := newSchedulerCache(time.Second, time.Second, nil)
+	for i := 0; i < 1000; i++ {
+		nodeName := fmt.Sprintf("node-%d", i)
+		for j := 0; j < 30; j++ {
+			objName := fmt.Sprintf("%s-pod-%d", nodeName, j)
+			pod := makeBasePod(nodeName, objName, "0", "0", nil)
+
+			err := cache.AssumePodIfBindSucceed(pod, alwaysTrue)
+			if err != nil {
+				b.Fatalf("AssumePodIfBindSucceed failed: %v", err)
+			}
+			err = cache.AddPod(pod)
+			if err != nil {
+				b.Fatalf("AddPod failed: %v", err)
+			}
+		}
+	}
+	return cache
+}
+
+func setupCacheWithAssumedPods(b *testing.B, podNum int, assumedTime time.Time) *schedulerCache {
+	cache := newSchedulerCache(time.Second, time.Second, nil)
+	for i := 0; i < podNum; i++ {
+		nodeName := fmt.Sprintf("node-%d", i/10)
+		objName := fmt.Sprintf("%s-pod-%d", nodeName, i%10)
+		pod := makeBasePod(nodeName, objName, "0", "0", nil)
+
+		err := cache.assumePodIfBindSucceed(pod, alwaysTrue, assumedTime)
+		if err != nil {
+			b.Fatalf("assumePodIfBindSucceed failed: %v", err)
+		}
+	}
+	return cache
+}
+
+func alwaysTrue() bool {
+	return true
+}

plugin/pkg/scheduler/schedulercache/interface.go

@@ -0,0 +1,81 @@
+/*
+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 schedulercache
+
+import (
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/labels"
+)
+
+// Cache collects pods' information and provides node-level aggregated information.
+// It's intended for generic scheduler to do efficient lookup.
+// Cache's operations are pod centric. It incrementally updates itself based on pod events.
+// Pod events are sent via network. We don't have guaranteed delivery of all events:
+// We use Reflector to list and watch from remote.
+// Reflector might be slow and do a relist, which would lead to missing events.
+//
+// State Machine of a pod's events in scheduler's cache:
+//
+//                                                +-------+
+//                                                |       |
+//                                                |       | Update
+//           Assume                Add            +       |
+// Initial +--------> Assumed +------------+---> Added <--+
+//                       +                 |       +
+//                       |                 |       |
+//                       |             Add |       | Remove
+//                       |                 |       |
+//                       |                 +       |
+//                       +-------------> Expired   +----> Deleted
+//                          Expire
+//
+// Note that an assumed pod can expire, because if we haven't received Add event notifying us
+// for a while, there might be some problems and we shouldn't keep the pod in cache anymore.
+//
+// Note that "Initial", "Expired", and "Deleted" pods do not actually exist in cache.
+// Based on existing use cases, we are making the following assumptions:
+// - No pod would be assumed twice
+// - If a pod wasn't added, it wouldn't be removed or updated.
+// - Both "Expired" and "Deleted" are valid end states. In case of some problems, e.g. network issue,
+//   a pod might have changed its state (e.g. added and deleted) without delivering notification to the cache.
+type Cache interface {
+	// AssumePodIfBindSucceed assumes a pod to be scheduled if binding the pod succeeded.
+	// If binding return true, the pod's information is aggregated into designated node.
+	// Note that both binding and assuming are done as one atomic operation from cache's view.
+	// No other events like Add would happen in between binding and assuming.
+	// We are passing the binding function and let implementation take care of concurrency control details.
+	// The implementation also decides the policy to expire pod before being confirmed (receiving Add event).
+	// After expiration, its information would be subtracted.
+	AssumePodIfBindSucceed(pod *api.Pod, bind func() bool) error
+
+	// AddPod either confirms a pod if it's assumed, or adds it back if it's expired.
+	// If added back, the pod's information would be added again.
+	AddPod(pod *api.Pod) error
+
+	// UpdatePod removes oldPod's information and adds newPod's information.
+	UpdatePod(oldPod, newPod *api.Pod) error
+
+	// RemovePod removes a pod. The pod's information would be subtracted from assigned node.
+	RemovePod(pod *api.Pod) error
+
+	// GetNodeNameToInfoMap returns a map of node names to node info. The node info contains
+	// aggregated information of pods scheduled (including assumed to be) on this node.
+	GetNodeNameToInfoMap() (map[string]*NodeInfo, error)
+
+	// List lists all cached pods (including assumed ones).
+	List(labels.Selector) ([]*api.Pod, error)
+}

plugin/pkg/scheduler/schedulercache/node_info.go

@@ -19,7 +19,11 @@ package schedulercache
 import (
 	"fmt"
 
+	"github.com/golang/glog"
+
 	"k8s.io/kubernetes/pkg/api"
+	clientcache "k8s.io/kubernetes/pkg/client/cache"
+	priorityutil "k8s.io/kubernetes/plugin/pkg/scheduler/algorithm/priorities/util"
 )
 
 var emptyResource = Resource{}
@@ -31,6 +35,7 @@ type NodeInfo struct {
 	// didn't get it as scheduled yet.
 	requestedResource *Resource
 	pods              []*api.Pod
+	nonzeroRequest    *Resource
 }
 
 // Resource is a collection of compute resource.
@@ -45,6 +50,7 @@ type Resource struct {
 func NewNodeInfo(pods ...*api.Pod) *NodeInfo {
 	ni := &NodeInfo{
 		requestedResource: &Resource{},
+		nonzeroRequest:    &Resource{},
 	}
 	for _, pod := range pods {
 		ni.addPod(pod)
@@ -68,29 +74,86 @@ func (n *NodeInfo) RequestedResource() Resource {
 	return *n.requestedResource
 }
 
+// NonZeroRequest returns aggregated nonzero resource request of pods on this node.
+func (n *NodeInfo) NonZeroRequest() Resource {
+	if n == nil {
+		return emptyResource
+	}
+	return *n.nonzeroRequest
+}
+
+func (n *NodeInfo) Clone() *NodeInfo {
+	pods := append([]*api.Pod(nil), n.pods...)
+	clone := &NodeInfo{
+		requestedResource: &(*n.requestedResource),
+		nonzeroRequest:    &(*n.nonzeroRequest),
+		pods:              pods,
+	}
+	return clone
+}
+
 // String returns representation of human readable format of this NodeInfo.
 func (n *NodeInfo) String() string {
 	podKeys := make([]string, len(n.pods))
 	for i, pod := range n.pods {
 		podKeys[i] = pod.Name
 	}
-	return fmt.Sprintf("&NodeInfo{Pods:%v, RequestedResource:%#v}", podKeys, n.requestedResource)
+	return fmt.Sprintf("&NodeInfo{Pods:%v, RequestedResource:%#v, NonZeroRequest: %#v}", podKeys, n.requestedResource, n.nonzeroRequest)
 }
 
 // addPod adds pod information to this NodeInfo.
 func (n *NodeInfo) addPod(pod *api.Pod) {
-	cpu, mem := calculateResource(pod)
+	cpu, mem, non0_cpu, non0_mem := calculateResource(pod)
 	n.requestedResource.MilliCPU += cpu
 	n.requestedResource.Memory += mem
+	n.nonzeroRequest.MilliCPU += non0_cpu
+	n.nonzeroRequest.Memory += non0_mem
 	n.pods = append(n.pods, pod)
 }
 
-func calculateResource(pod *api.Pod) (int64, int64) {
+// removePod subtracts pod information to this NodeInfo.
-	var cpu, mem int64
+func (n *NodeInfo) removePod(pod *api.Pod) error {
+	k1, err := getPodKey(pod)
+	if err != nil {
+		return err
+	}
+
+	cpu, mem, non0_cpu, non0_mem := calculateResource(pod)
+	n.requestedResource.MilliCPU -= cpu
+	n.requestedResource.Memory -= mem
+	n.nonzeroRequest.MilliCPU -= non0_cpu
+	n.nonzeroRequest.Memory -= non0_mem
+
+	for i := range n.pods {
+		k2, err := getPodKey(n.pods[i])
+		if err != nil {
+			glog.Errorf("Cannot get pod key, err: %v", err)
+			continue
+		}
+		if k1 == k2 {
+			// delete the element
+			n.pods[i] = n.pods[len(n.pods)-1]
+			n.pods = n.pods[:len(n.pods)-1]
+			return nil
+		}
+	}
+	return fmt.Errorf("no corresponding pod in pods")
+}
+
+func calculateResource(pod *api.Pod) (cpu int64, mem int64, non0_cpu int64, non0_mem int64) {
 	for _, c := range pod.Spec.Containers {
 		req := c.Resources.Requests
 		cpu += req.Cpu().MilliValue()
 		mem += req.Memory().Value()
+
+		non0_cpu_req, non0_mem_req := priorityutil.GetNonzeroRequests(&req)
+		non0_cpu += non0_cpu_req
+		non0_mem += non0_mem_req
 	}
-	return cpu, mem
+	return
+}
+
+// getPodKey returns the string key of a pod.
+func getPodKey(pod *api.Pod) (string, error) {
+	return clientcache.MetaNamespaceKeyFunc(pod)
 }