types.go

/*
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 framework

import (
	"errors"
	"fmt"
	"sort"
	"strings"
	"sync/atomic"
	"time"

	v1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	utilerrors "k8s.io/apimachinery/pkg/util/errors"
	"k8s.io/apimachinery/pkg/util/sets"
	"k8s.io/klog/v2"
	schedutil "k8s.io/kubernetes/pkg/scheduler/util"
)

var generation int64

// ActionType is an integer to represent one type of resource change.
// Different ActionTypes can be bit-wised to compose new semantics.
type ActionType int64

// Constants for ActionTypes.
const (
	Add    ActionType = 1 << iota // 1
	Delete                        // 10
	// UpdateNodeXYZ is only applicable for Node events.
	UpdateNodeAllocatable // 100
	UpdateNodeLabel       // 1000
	UpdateNodeTaint       // 10000
	UpdateNodeCondition   // 100000

	All ActionType = 1<<iota - 1 // 111111

	// Use the general Update type if you don't either know or care the specific sub-Update type to use.
	Update = UpdateNodeAllocatable | UpdateNodeLabel | UpdateNodeTaint | UpdateNodeCondition
)

// GVK is short for group/version/kind, which can uniquely represent a particular API resource.
type GVK string

// Constants for GVKs.
const (
	Pod                   GVK = "Pod"
	Node                  GVK = "Node"
	PersistentVolume      GVK = "PersistentVolume"
	PersistentVolumeClaim GVK = "PersistentVolumeClaim"
	Service               GVK = "Service"
	StorageClass          GVK = "storage.k8s.io/StorageClass"
	CSINode               GVK = "storage.k8s.io/CSINode"
	CSIDriver             GVK = "storage.k8s.io/CSIDriver"
	CSIStorageCapacity    GVK = "storage.k8s.io/CSIStorageCapacity"
	WildCard              GVK = "*"
)

// ClusterEvent abstracts how a system resource's state gets changed.
// Resource represents the standard API resources such as Pod, Node, etc.
// ActionType denotes the specific change such as Add, Update or Delete.
type ClusterEvent struct {
	Resource   GVK
	ActionType ActionType
	Label      string
}

// IsWildCard returns true if ClusterEvent follows WildCard semantics
func (ce ClusterEvent) IsWildCard() bool {
	return ce.Resource == WildCard && ce.ActionType == All
}

// QueuedPodInfo is a Pod wrapper with additional information related to
// the pod's status in the scheduling queue, such as the timestamp when
// it's added to the queue.
type QueuedPodInfo struct {
	*PodInfo
	// The time pod added to the scheduling queue.
	Timestamp time.Time
	// Number of schedule attempts before successfully scheduled.
	// It's used to record the # attempts metric.
	Attempts int
	// The time when the pod is added to the queue for the first time. The pod may be added
	// back to the queue multiple times before it's successfully scheduled.
	// It shouldn't be updated once initialized. It's used to record the e2e scheduling
	// latency for a pod.
	InitialAttemptTimestamp time.Time
	// If a Pod failed in a scheduling cycle, record the plugin names it failed by.
	UnschedulablePlugins sets.String
}

// DeepCopy returns a deep copy of the QueuedPodInfo object.
func (pqi *QueuedPodInfo) DeepCopy() *QueuedPodInfo {
	return &QueuedPodInfo{
		PodInfo:                 pqi.PodInfo.DeepCopy(),
		Timestamp:               pqi.Timestamp,
		Attempts:                pqi.Attempts,
		InitialAttemptTimestamp: pqi.InitialAttemptTimestamp,
	}
}

// PodInfo is a wrapper to a Pod with additional pre-computed information to
// accelerate processing. This information is typically immutable (e.g., pre-processed
// inter-pod affinity selectors).
type PodInfo struct {
	Pod                        *v1.Pod
	RequiredAffinityTerms      []AffinityTerm
	RequiredAntiAffinityTerms  []AffinityTerm
	PreferredAffinityTerms     []WeightedAffinityTerm
	PreferredAntiAffinityTerms []WeightedAffinityTerm
	ParseError                 error
}

// DeepCopy returns a deep copy of the PodInfo object.
func (pi *PodInfo) DeepCopy() *PodInfo {
	return &PodInfo{
		Pod:                        pi.Pod.DeepCopy(),
		RequiredAffinityTerms:      pi.RequiredAffinityTerms,
		RequiredAntiAffinityTerms:  pi.RequiredAntiAffinityTerms,
		PreferredAffinityTerms:     pi.PreferredAffinityTerms,
		PreferredAntiAffinityTerms: pi.PreferredAntiAffinityTerms,
		ParseError:                 pi.ParseError,
	}
}

// Update creates a full new PodInfo by default. And only updates the pod when the PodInfo
// has been instantiated and the passed pod is the exact same one as the original pod.
func (pi *PodInfo) Update(pod *v1.Pod) {
	if pod != nil && pi.Pod != nil && pi.Pod.UID == pod.UID {
		// PodInfo includes immutable information, and so it is safe to update the pod in place if it is
		// the exact same pod
		pi.Pod = pod
		return
	}
	var preferredAffinityTerms []v1.WeightedPodAffinityTerm
	var preferredAntiAffinityTerms []v1.WeightedPodAffinityTerm
	if affinity := pod.Spec.Affinity; affinity != nil {
		if a := affinity.PodAffinity; a != nil {
			preferredAffinityTerms = a.PreferredDuringSchedulingIgnoredDuringExecution
		}
		if a := affinity.PodAntiAffinity; a != nil {
			preferredAntiAffinityTerms = a.PreferredDuringSchedulingIgnoredDuringExecution
		}
	}

	// Attempt to parse the affinity terms
	var parseErrs []error
	requiredAffinityTerms, err := getAffinityTerms(pod, getPodAffinityTerms(pod.Spec.Affinity))
	if err != nil {
		parseErrs = append(parseErrs, fmt.Errorf("requiredAffinityTerms: %w", err))
	}
	requiredAntiAffinityTerms, err := getAffinityTerms(pod,
		getPodAntiAffinityTerms(pod.Spec.Affinity))
	if err != nil {
		parseErrs = append(parseErrs, fmt.Errorf("requiredAntiAffinityTerms: %w", err))
	}
	weightedAffinityTerms, err := getWeightedAffinityTerms(pod, preferredAffinityTerms)
	if err != nil {
		parseErrs = append(parseErrs, fmt.Errorf("preferredAffinityTerms: %w", err))
	}
	weightedAntiAffinityTerms, err := getWeightedAffinityTerms(pod, preferredAntiAffinityTerms)
	if err != nil {
		parseErrs = append(parseErrs, fmt.Errorf("preferredAntiAffinityTerms: %w", err))
	}

	pi.Pod = pod
	pi.RequiredAffinityTerms = requiredAffinityTerms
	pi.RequiredAntiAffinityTerms = requiredAntiAffinityTerms
	pi.PreferredAffinityTerms = weightedAffinityTerms
	pi.PreferredAntiAffinityTerms = weightedAntiAffinityTerms
	pi.ParseError = utilerrors.NewAggregate(parseErrs)
}

// AffinityTerm is a processed version of v1.PodAffinityTerm.
type AffinityTerm struct {
	Namespaces        sets.String
	Selector          labels.Selector
	TopologyKey       string
	NamespaceSelector labels.Selector
}

// Matches returns true if the pod matches the label selector and namespaces or namespace selector.
func (at *AffinityTerm) Matches(pod *v1.Pod, nsLabels labels.Set) bool {
	if at.Namespaces.Has(pod.Namespace) || at.NamespaceSelector.Matches(nsLabels) {
		return at.Selector.Matches(labels.Set(pod.Labels))
	}
	return false
}

// WeightedAffinityTerm is a "processed" representation of v1.WeightedAffinityTerm.
type WeightedAffinityTerm struct {
	AffinityTerm
	Weight int32
}

// Diagnosis records the details to diagnose a scheduling failure.
type Diagnosis struct {
	NodeToStatusMap      NodeToStatusMap
	UnschedulablePlugins sets.String
	// PostFilterMsg records the messages returned from PostFilterPlugins.
	PostFilterMsg string
}

// FitError describes a fit error of a pod.
type FitError struct {
	Pod         *v1.Pod
	NumAllNodes int
	Diagnosis   Diagnosis
}

// NoNodeAvailableMsg is used to format message when no nodes available.
const NoNodeAvailableMsg = "0/%v nodes are available"

// Error returns detailed information of why the pod failed to fit on each node
func (f *FitError) Error() string {
	reasons := make(map[string]int)
	for _, status := range f.Diagnosis.NodeToStatusMap {
		for _, reason := range status.Reasons() {
			reasons[reason]++
		}
	}

	sortReasonsHistogram := func() []string {
		var reasonStrings []string
		for k, v := range reasons {
			reasonStrings = append(reasonStrings, fmt.Sprintf("%v %v", v, k))
		}
		sort.Strings(reasonStrings)
		return reasonStrings
	}
	reasonMsg := fmt.Sprintf(NoNodeAvailableMsg+": %v.", f.NumAllNodes, strings.Join(sortReasonsHistogram(), ", "))
	postFilterMsg := f.Diagnosis.PostFilterMsg
	if postFilterMsg != "" {
		reasonMsg += " " + postFilterMsg
	}
	return reasonMsg
}

func newAffinityTerm(pod *v1.Pod, term *v1.PodAffinityTerm) (*AffinityTerm, error) {
	selector, err := metav1.LabelSelectorAsSelector(term.LabelSelector)
	if err != nil {
		return nil, err
	}

	namespaces := getNamespacesFromPodAffinityTerm(pod, term)
	nsSelector, err := metav1.LabelSelectorAsSelector(term.NamespaceSelector)
	if err != nil {
		return nil, err
	}

	return &AffinityTerm{Namespaces: namespaces, Selector: selector, TopologyKey: term.TopologyKey, NamespaceSelector: nsSelector}, nil
}

// getAffinityTerms receives a Pod and affinity terms and returns the namespaces and
// selectors of the terms.
func getAffinityTerms(pod *v1.Pod, v1Terms []v1.PodAffinityTerm) ([]AffinityTerm, error) {
	if v1Terms == nil {
		return nil, nil
	}

	var terms []AffinityTerm
	for i := range v1Terms {
		t, err := newAffinityTerm(pod, &v1Terms[i])
		if err != nil {
			// We get here if the label selector failed to process
			return nil, err
		}
		terms = append(terms, *t)
	}
	return terms, nil
}

// getWeightedAffinityTerms returns the list of processed affinity terms.
func getWeightedAffinityTerms(pod *v1.Pod, v1Terms []v1.WeightedPodAffinityTerm) ([]WeightedAffinityTerm, error) {
	if v1Terms == nil {
		return nil, nil
	}

	var terms []WeightedAffinityTerm
	for i := range v1Terms {
		t, err := newAffinityTerm(pod, &v1Terms[i].PodAffinityTerm)
		if err != nil {
			// We get here if the label selector failed to process
			return nil, err
		}
		terms = append(terms, WeightedAffinityTerm{AffinityTerm: *t, Weight: v1Terms[i].Weight})
	}
	return terms, nil
}

// NewPodInfo returns a new PodInfo.
func NewPodInfo(pod *v1.Pod) *PodInfo {
	pInfo := &PodInfo{}
	pInfo.Update(pod)
	return pInfo
}

func getPodAffinityTerms(affinity *v1.Affinity) (terms []v1.PodAffinityTerm) {
	if affinity != nil && affinity.PodAffinity != nil {
		if len(affinity.PodAffinity.RequiredDuringSchedulingIgnoredDuringExecution) != 0 {
			terms = affinity.PodAffinity.RequiredDuringSchedulingIgnoredDuringExecution
		}
		// TODO: Uncomment this block when implement RequiredDuringSchedulingRequiredDuringExecution.
		//if len(affinity.PodAffinity.RequiredDuringSchedulingRequiredDuringExecution) != 0 {
		//	terms = append(terms, affinity.PodAffinity.RequiredDuringSchedulingRequiredDuringExecution...)
		//}
	}
	return terms
}

func getPodAntiAffinityTerms(affinity *v1.Affinity) (terms []v1.PodAffinityTerm) {
	if affinity != nil && affinity.PodAntiAffinity != nil {
		if len(affinity.PodAntiAffinity.RequiredDuringSchedulingIgnoredDuringExecution) != 0 {
			terms = affinity.PodAntiAffinity.RequiredDuringSchedulingIgnoredDuringExecution
		}
		// TODO: Uncomment this block when implement RequiredDuringSchedulingRequiredDuringExecution.
		//if len(affinity.PodAntiAffinity.RequiredDuringSchedulingRequiredDuringExecution) != 0 {
		//	terms = append(terms, affinity.PodAntiAffinity.RequiredDuringSchedulingRequiredDuringExecution...)
		//}
	}
	return terms
}

// returns a set of names according to the namespaces indicated in podAffinityTerm.
// If namespaces is empty it considers the given pod's namespace.
func getNamespacesFromPodAffinityTerm(pod *v1.Pod, podAffinityTerm *v1.PodAffinityTerm) sets.String {
	names := sets.String{}
	if len(podAffinityTerm.Namespaces) == 0 && podAffinityTerm.NamespaceSelector == nil {
		names.Insert(pod.Namespace)
	} else {
		names.Insert(podAffinityTerm.Namespaces...)
	}
	return names
}

// ImageStateSummary provides summarized information about the state of an image.
type ImageStateSummary struct {
	// Size of the image
	Size int64
	// Used to track how many nodes have this image
	NumNodes int
}

// NodeInfo is node level aggregated information.
type NodeInfo struct {
	// Overall node information.
	node *v1.Node

	// Pods running on the node.
	Pods []*PodInfo

	// The subset of pods with affinity.
	PodsWithAffinity []*PodInfo

	// The subset of pods with required anti-affinity.
	PodsWithRequiredAntiAffinity []*PodInfo

	// Ports allocated on the node.
	UsedPorts HostPortInfo

	// Total requested resources of all pods on this node. This includes assumed
	// pods, which scheduler has sent for binding, but may not be scheduled yet.
	Requested *Resource
	// Total requested resources of all pods on this node with a minimum value
	// applied to each container's CPU and memory requests. This does not reflect
	// the actual resource requests for this node, but is used to avoid scheduling
	// many zero-request pods onto one node.
	NonZeroRequested *Resource
	// We store allocatedResources (which is Node.Status.Allocatable.*) explicitly
	// as int64, to avoid conversions and accessing map.
	Allocatable *Resource

	// ImageStates holds the entry of an image if and only if this image is on the node. The entry can be used for
	// checking an image's existence and advanced usage (e.g., image locality scheduling policy) based on the image
	// state information.
	ImageStates map[string]*ImageStateSummary

	// PVCRefCounts contains a mapping of PVC names to the number of pods on the node using it.
	// Keys are in the format "namespace/name".
	PVCRefCounts map[string]int

	// Whenever NodeInfo changes, generation is bumped.
	// This is used to avoid cloning it if the object didn't change.
	Generation int64
}

// nextGeneration: Let's make sure history never forgets the name...
// Increments the generation number monotonically ensuring that generation numbers never collide.
// Collision of the generation numbers would be particularly problematic if a node was deleted and
// added back with the same name. See issue#63262.
func nextGeneration() int64 {
	return atomic.AddInt64(&generation, 1)
}

// Resource is a collection of compute resource.
type Resource struct {
	MilliCPU         int64
	Memory           int64
	EphemeralStorage int64
	// We store allowedPodNumber (which is Node.Status.Allocatable.Pods().Value())
	// explicitly as int, to avoid conversions and improve performance.
	AllowedPodNumber int
	// ScalarResources
	ScalarResources map[v1.ResourceName]int64
}

// NewResource creates a Resource from ResourceList
func NewResource(rl v1.ResourceList) *Resource {
	r := &Resource{}
	r.Add(rl)
	return r
}

// Add adds ResourceList into Resource.
func (r *Resource) Add(rl v1.ResourceList) {
	if r == nil {
		return
	}

	for rName, rQuant := range rl {
		switch rName {
		case v1.ResourceCPU:
			r.MilliCPU += rQuant.MilliValue()
		case v1.ResourceMemory:
			r.Memory += rQuant.Value()
		case v1.ResourcePods:
			r.AllowedPodNumber += int(rQuant.Value())
		case v1.ResourceEphemeralStorage:
			r.EphemeralStorage += rQuant.Value()
		default:
			if schedutil.IsScalarResourceName(rName) {
				r.AddScalar(rName, rQuant.Value())
			}
		}
	}
}

// Clone returns a copy of this resource.
func (r *Resource) Clone() *Resource {
	res := &Resource{
		MilliCPU:         r.MilliCPU,
		Memory:           r.Memory,
		AllowedPodNumber: r.AllowedPodNumber,
		EphemeralStorage: r.EphemeralStorage,
	}
	if r.ScalarResources != nil {
		res.ScalarResources = make(map[v1.ResourceName]int64)
		for k, v := range r.ScalarResources {
			res.ScalarResources[k] = v
		}
	}
	return res
}

// AddScalar adds a resource by a scalar value of this resource.
func (r *Resource) AddScalar(name v1.ResourceName, quantity int64) {
	r.SetScalar(name, r.ScalarResources[name]+quantity)
}

// SetScalar sets a resource by a scalar value of this resource.
func (r *Resource) SetScalar(name v1.ResourceName, quantity int64) {
	// Lazily allocate scalar resource map.
	if r.ScalarResources == nil {
		r.ScalarResources = map[v1.ResourceName]int64{}
	}
	r.ScalarResources[name] = quantity
}

// SetMaxResource compares with ResourceList and takes max value for each Resource.
func (r *Resource) SetMaxResource(rl v1.ResourceList) {
	if r == nil {
		return
	}

	for rName, rQuantity := range rl {
		switch rName {
		case v1.ResourceMemory:
			r.Memory = max(r.Memory, rQuantity.Value())
		case v1.ResourceCPU:
			r.MilliCPU = max(r.MilliCPU, rQuantity.MilliValue())
		case v1.ResourceEphemeralStorage:
			r.EphemeralStorage = max(r.EphemeralStorage, rQuantity.Value())
		default:
			if schedutil.IsScalarResourceName(rName) {
				r.SetScalar(rName, max(r.ScalarResources[rName], rQuantity.Value()))
			}
		}
	}
}

// NewNodeInfo returns a ready to use empty NodeInfo object.
// If any pods are given in arguments, their information will be aggregated in
// the returned object.
func NewNodeInfo(pods ...*v1.Pod) *NodeInfo {
	ni := &NodeInfo{
		Requested:        &Resource{},
		NonZeroRequested: &Resource{},
		Allocatable:      &Resource{},
		Generation:       nextGeneration(),
		UsedPorts:        make(HostPortInfo),
		ImageStates:      make(map[string]*ImageStateSummary),
		PVCRefCounts:     make(map[string]int),
	}
	for _, pod := range pods {
		ni.AddPod(pod)
	}
	return ni
}

// Node returns overall information about this node.
func (n *NodeInfo) Node() *v1.Node {
	if n == nil {
		return nil
	}
	return n.node
}

// Clone returns a copy of this node.
func (n *NodeInfo) Clone() *NodeInfo {
	clone := &NodeInfo{
		node:             n.node,
		Requested:        n.Requested.Clone(),
		NonZeroRequested: n.NonZeroRequested.Clone(),
		Allocatable:      n.Allocatable.Clone(),
		UsedPorts:        make(HostPortInfo),
		ImageStates:      n.ImageStates,
		PVCRefCounts:     make(map[string]int),
		Generation:       n.Generation,
	}
	if len(n.Pods) > 0 {
		clone.Pods = append([]*PodInfo(nil), n.Pods...)
	}
	if len(n.UsedPorts) > 0 {
		// HostPortInfo is a map-in-map struct
		// make sure it's deep copied
		for ip, portMap := range n.UsedPorts {
			clone.UsedPorts[ip] = make(map[ProtocolPort]struct{})
			for protocolPort, v := range portMap {
				clone.UsedPorts[ip][protocolPort] = v
			}
		}
	}
	if len(n.PodsWithAffinity) > 0 {
		clone.PodsWithAffinity = append([]*PodInfo(nil), n.PodsWithAffinity...)
	}
	if len(n.PodsWithRequiredAntiAffinity) > 0 {
		clone.PodsWithRequiredAntiAffinity = append([]*PodInfo(nil), n.PodsWithRequiredAntiAffinity...)
	}
	for key, value := range n.PVCRefCounts {
		clone.PVCRefCounts[key] = value
	}
	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, p := range n.Pods {
		podKeys[i] = p.Pod.Name
	}
	return fmt.Sprintf("&NodeInfo{Pods:%v, RequestedResource:%#v, NonZeroRequest: %#v, UsedPort: %#v, AllocatableResource:%#v}",
		podKeys, n.Requested, n.NonZeroRequested, n.UsedPorts, n.Allocatable)
}

// AddPodInfo adds pod information to this NodeInfo.
// Consider using this instead of AddPod if a PodInfo is already computed.
func (n *NodeInfo) AddPodInfo(podInfo *PodInfo) {
	res, non0CPU, non0Mem := calculateResource(podInfo.Pod)
	n.Requested.MilliCPU += res.MilliCPU
	n.Requested.Memory += res.Memory
	n.Requested.EphemeralStorage += res.EphemeralStorage
	if n.Requested.ScalarResources == nil && len(res.ScalarResources) > 0 {
		n.Requested.ScalarResources = map[v1.ResourceName]int64{}
	}
	for rName, rQuant := range res.ScalarResources {
		n.Requested.ScalarResources[rName] += rQuant
	}
	n.NonZeroRequested.MilliCPU += non0CPU
	n.NonZeroRequested.Memory += non0Mem
	n.Pods = append(n.Pods, podInfo)
	if podWithAffinity(podInfo.Pod) {
		n.PodsWithAffinity = append(n.PodsWithAffinity, podInfo)
	}
	if podWithRequiredAntiAffinity(podInfo.Pod) {
		n.PodsWithRequiredAntiAffinity = append(n.PodsWithRequiredAntiAffinity, podInfo)
	}

	// Consume ports when pods added.
	n.updateUsedPorts(podInfo.Pod, true)
	n.updatePVCRefCounts(podInfo.Pod, true)

	n.Generation = nextGeneration()
}

// AddPod is a wrapper around AddPodInfo.
func (n *NodeInfo) AddPod(pod *v1.Pod) {
	n.AddPodInfo(NewPodInfo(pod))
}

func podWithAffinity(p *v1.Pod) bool {
	affinity := p.Spec.Affinity
	return affinity != nil && (affinity.PodAffinity != nil || affinity.PodAntiAffinity != nil)
}

func podWithRequiredAntiAffinity(p *v1.Pod) bool {
	affinity := p.Spec.Affinity
	return affinity != nil && affinity.PodAntiAffinity != nil &&
		len(affinity.PodAntiAffinity.RequiredDuringSchedulingIgnoredDuringExecution) != 0
}

func removeFromSlice(s []*PodInfo, k string) []*PodInfo {
	for i := range s {
		k2, err := GetPodKey(s[i].Pod)
		if err != nil {
			klog.ErrorS(err, "Cannot get pod key", "pod", klog.KObj(s[i].Pod))
			continue
		}
		if k == k2 {
			// delete the element
			s[i] = s[len(s)-1]
			s = s[:len(s)-1]
			break
		}
	}
	return s
}

// RemovePod subtracts pod information from this NodeInfo.
func (n *NodeInfo) RemovePod(pod *v1.Pod) error {
	k, err := GetPodKey(pod)
	if err != nil {
		return err
	}
	if podWithAffinity(pod) {
		n.PodsWithAffinity = removeFromSlice(n.PodsWithAffinity, k)
	}
	if podWithRequiredAntiAffinity(pod) {
		n.PodsWithRequiredAntiAffinity = removeFromSlice(n.PodsWithRequiredAntiAffinity, k)
	}

	for i := range n.Pods {
		k2, err := GetPodKey(n.Pods[i].Pod)
		if err != nil {
			klog.ErrorS(err, "Cannot get pod key", "pod", klog.KObj(n.Pods[i].Pod))
			continue
		}
		if k == k2 {
			// delete the element
			n.Pods[i] = n.Pods[len(n.Pods)-1]
			n.Pods = n.Pods[:len(n.Pods)-1]
			// reduce the resource data
			res, non0CPU, non0Mem := calculateResource(pod)

			n.Requested.MilliCPU -= res.MilliCPU
			n.Requested.Memory -= res.Memory
			n.Requested.EphemeralStorage -= res.EphemeralStorage
			if len(res.ScalarResources) > 0 && n.Requested.ScalarResources == nil {
				n.Requested.ScalarResources = map[v1.ResourceName]int64{}
			}
			for rName, rQuant := range res.ScalarResources {
				n.Requested.ScalarResources[rName] -= rQuant
			}
			n.NonZeroRequested.MilliCPU -= non0CPU
			n.NonZeroRequested.Memory -= non0Mem

			// Release ports when remove Pods.
			n.updateUsedPorts(pod, false)
			n.updatePVCRefCounts(pod, false)

			n.Generation = nextGeneration()
			n.resetSlicesIfEmpty()
			return nil
		}
	}
	return fmt.Errorf("no corresponding pod %s in pods of node %s", pod.Name, n.node.Name)
}

// resets the slices to nil so that we can do DeepEqual in unit tests.
func (n *NodeInfo) resetSlicesIfEmpty() {
	if len(n.PodsWithAffinity) == 0 {
		n.PodsWithAffinity = nil
	}
	if len(n.PodsWithRequiredAntiAffinity) == 0 {
		n.PodsWithRequiredAntiAffinity = nil
	}
	if len(n.Pods) == 0 {
		n.Pods = nil
	}
}

func max(a, b int64) int64 {
	if a >= b {
		return a
	}
	return b
}

// resourceRequest = max(sum(podSpec.Containers), podSpec.InitContainers) + overHead
func calculateResource(pod *v1.Pod) (res Resource, non0CPU int64, non0Mem int64) {
	resPtr := &res
	for _, c := range pod.Spec.Containers {
		resPtr.Add(c.Resources.Requests)
		non0CPUReq, non0MemReq := schedutil.GetNonzeroRequests(&c.Resources.Requests)
		non0CPU += non0CPUReq
		non0Mem += non0MemReq
		// No non-zero resources for GPUs or opaque resources.
	}

	for _, ic := range pod.Spec.InitContainers {
		resPtr.SetMaxResource(ic.Resources.Requests)
		non0CPUReq, non0MemReq := schedutil.GetNonzeroRequests(&ic.Resources.Requests)
		non0CPU = max(non0CPU, non0CPUReq)
		non0Mem = max(non0Mem, non0MemReq)
	}

	// If Overhead is being utilized, add to the total requests for the pod
	if pod.Spec.Overhead != nil {
		resPtr.Add(pod.Spec.Overhead)
		if _, found := pod.Spec.Overhead[v1.ResourceCPU]; found {
			non0CPU += pod.Spec.Overhead.Cpu().MilliValue()
		}

		if _, found := pod.Spec.Overhead[v1.ResourceMemory]; found {
			non0Mem += pod.Spec.Overhead.Memory().Value()
		}
	}

	return
}

// updateUsedPorts updates the UsedPorts of NodeInfo.
func (n *NodeInfo) updateUsedPorts(pod *v1.Pod, add bool) {
	for _, container := range pod.Spec.Containers {
		for _, podPort := range container.Ports {
			if add {
				n.UsedPorts.Add(podPort.HostIP, string(podPort.Protocol), podPort.HostPort)
			} else {
				n.UsedPorts.Remove(podPort.HostIP, string(podPort.Protocol), podPort.HostPort)
			}
		}
	}
}

// updatePVCRefCounts updates the PVCRefCounts of NodeInfo.
func (n *NodeInfo) updatePVCRefCounts(pod *v1.Pod, add bool) {
	for _, v := range pod.Spec.Volumes {
		if v.PersistentVolumeClaim == nil {
			continue
		}

		key := GetNamespacedName(pod.Namespace, v.PersistentVolumeClaim.ClaimName)
		if add {
			n.PVCRefCounts[key] += 1
		} else {
			n.PVCRefCounts[key] -= 1
			if n.PVCRefCounts[key] <= 0 {
				delete(n.PVCRefCounts, key)
			}
		}
	}
}

// SetNode sets the overall node information.
func (n *NodeInfo) SetNode(node *v1.Node) {
	n.node = node
	n.Allocatable = NewResource(node.Status.Allocatable)
	n.Generation = nextGeneration()
}

// RemoveNode removes the node object, leaving all other tracking information.
func (n *NodeInfo) RemoveNode() {
	n.node = nil
	n.Generation = nextGeneration()
}

// GetPodKey returns the string key of a pod.
func GetPodKey(pod *v1.Pod) (string, error) {
	uid := string(pod.UID)
	if len(uid) == 0 {
		return "", errors.New("cannot get cache key for pod with empty UID")
	}
	return uid, nil
}

// GetNamespacedName returns the string format of a namespaced resource name.
func GetNamespacedName(namespace, name string) string {
	return fmt.Sprintf("%s/%s", namespace, name)
}

// DefaultBindAllHostIP defines the default ip address used to bind to all host.
const DefaultBindAllHostIP = "0.0.0.0"

// ProtocolPort represents a protocol port pair, e.g. tcp:80.
type ProtocolPort struct {
	Protocol string
	Port     int32
}

// NewProtocolPort creates a ProtocolPort instance.
func NewProtocolPort(protocol string, port int32) *ProtocolPort {
	pp := &ProtocolPort{
		Protocol: protocol,
		Port:     port,
	}

	if len(pp.Protocol) == 0 {
		pp.Protocol = string(v1.ProtocolTCP)
	}

	return pp
}

// HostPortInfo stores mapping from ip to a set of ProtocolPort
type HostPortInfo map[string]map[ProtocolPort]struct{}

// Add adds (ip, protocol, port) to HostPortInfo
func (h HostPortInfo) Add(ip, protocol string, port int32) {
	if port <= 0 {
		return
	}

	h.sanitize(&ip, &protocol)

	pp := NewProtocolPort(protocol, port)
	if _, ok := h[ip]; !ok {
		h[ip] = map[ProtocolPort]struct{}{
			*pp: {},
		}
		return
	}

	h[ip][*pp] = struct{}{}
}

// Remove removes (ip, protocol, port) from HostPortInfo
func (h HostPortInfo) Remove(ip, protocol string, port int32) {
	if port <= 0 {
		return
	}

	h.sanitize(&ip, &protocol)

	pp := NewProtocolPort(protocol, port)
	if m, ok := h[ip]; ok {
		delete(m, *pp)
		if len(h[ip]) == 0 {
			delete(h, ip)
		}
	}
}

// Len returns the total number of (ip, protocol, port) tuple in HostPortInfo
func (h HostPortInfo) Len() int {
	length := 0
	for _, m := range h {
		length += len(m)
	}
	return length
}

// CheckConflict checks if the input (ip, protocol, port) conflicts with the existing
// ones in HostPortInfo.
func (h HostPortInfo) CheckConflict(ip, protocol string, port int32) bool {
	if port <= 0 {
		return false
	}

	h.sanitize(&ip, &protocol)

	pp := NewProtocolPort(protocol, port)

	// If ip is 0.0.0.0 check all IP's (protocol, port) pair
	if ip == DefaultBindAllHostIP {
		for _, m := range h {
			if _, ok := m[*pp]; ok {
				return true
			}
		}
		return false
	}

	// If ip isn't 0.0.0.0, only check IP and 0.0.0.0's (protocol, port) pair
	for _, key := range []string{DefaultBindAllHostIP, ip} {
		if m, ok := h[key]; ok {
			if _, ok2 := m[*pp]; ok2 {
				return true
			}
		}
	}

	return false
}

// sanitize the parameters
func (h HostPortInfo) sanitize(ip, protocol *string) {
	if len(*ip) == 0 {
		*ip = DefaultBindAllHostIP
	}
	if len(*protocol) == 0 {
		*protocol = string(v1.ProtocolTCP)
	}
}