/*
Copyright 2014 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 factory can set up a scheduler. This code is here instead of
// cmd/scheduler for both testability and reuse.
package factory

import (
	"fmt"
	"time"

	"k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/fields"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/sets"
	"k8s.io/apimachinery/pkg/util/wait"
	utilfeature "k8s.io/apiserver/pkg/util/feature"
	appsinformers "k8s.io/client-go/informers/apps/v1"
	coreinformers "k8s.io/client-go/informers/core/v1"
	policyinformers "k8s.io/client-go/informers/policy/v1beta1"
	storageinformersv1 "k8s.io/client-go/informers/storage/v1"
	storageinformersv1beta1 "k8s.io/client-go/informers/storage/v1beta1"
	clientset "k8s.io/client-go/kubernetes"
	appslisters "k8s.io/client-go/listers/apps/v1"
	corelisters "k8s.io/client-go/listers/core/v1"
	policylisters "k8s.io/client-go/listers/policy/v1beta1"
	storagelistersv1 "k8s.io/client-go/listers/storage/v1"
	storagelistersv1beta1 "k8s.io/client-go/listers/storage/v1beta1"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/events"
	"k8s.io/klog"
	podutil "k8s.io/kubernetes/pkg/api/v1/pod"
	"k8s.io/kubernetes/pkg/features"
	"k8s.io/kubernetes/pkg/scheduler/algorithm"
	"k8s.io/kubernetes/pkg/scheduler/algorithm/predicates"
	"k8s.io/kubernetes/pkg/scheduler/algorithm/priorities"
	schedulerapi "k8s.io/kubernetes/pkg/scheduler/api"
	"k8s.io/kubernetes/pkg/scheduler/api/validation"
	"k8s.io/kubernetes/pkg/scheduler/apis/config"
	"k8s.io/kubernetes/pkg/scheduler/core"
	framework "k8s.io/kubernetes/pkg/scheduler/framework/v1alpha1"
	internalcache "k8s.io/kubernetes/pkg/scheduler/internal/cache"
	cachedebugger "k8s.io/kubernetes/pkg/scheduler/internal/cache/debugger"
	internalqueue "k8s.io/kubernetes/pkg/scheduler/internal/queue"
	"k8s.io/kubernetes/pkg/scheduler/volumebinder"
)

const (
	initialGetBackoff = 100 * time.Millisecond
	maximalGetBackoff = time.Minute
)

// Binder knows how to write a binding.
type Binder interface {
	Bind(binding *v1.Binding) error
}

// PodConditionUpdater updates the condition of a pod based on the passed
// PodCondition
type PodConditionUpdater interface {
	Update(pod *v1.Pod, podCondition *v1.PodCondition) error
}

// Config is an implementation of the Scheduler's configured input data.
// TODO over time we should make this struct a hidden implementation detail of the scheduler.
type Config struct {
	SchedulerCache internalcache.Cache

	Algorithm core.ScheduleAlgorithm
	GetBinder func(pod *v1.Pod) Binder
	// PodConditionUpdater is used only in case of scheduling errors. If we succeed
	// with scheduling, PodScheduled condition will be updated in apiserver in /bind
	// handler so that binding and setting PodCondition it is atomic.
	PodConditionUpdater PodConditionUpdater
	// PodPreemptor is used to evict pods and update 'NominatedNode' field of
	// the preemptor pod.
	PodPreemptor PodPreemptor
	// Framework runs scheduler plugins at configured extension points.
	Framework framework.Framework

	// NextPod should be a function that blocks until the next pod
	// is available. We don't use a channel for this, because scheduling
	// a pod may take some amount of time and we don't want pods to get
	// stale while they sit in a channel.
	NextPod func() *v1.Pod

	// WaitForCacheSync waits for scheduler cache to populate.
	// It returns true if it was successful, false if the controller should shutdown.
	WaitForCacheSync func() bool

	// Error is called if there is an error. It is passed the pod in
	// question, and the error
	Error func(*v1.Pod, error)

	// Recorder is the EventRecorder to use
	Recorder events.EventRecorder

	// Close this to shut down the scheduler.
	StopEverything <-chan struct{}

	// VolumeBinder handles PVC/PV binding for the pod.
	VolumeBinder *volumebinder.VolumeBinder

	// Disable pod preemption or not.
	DisablePreemption bool

	// SchedulingQueue holds pods to be scheduled
	SchedulingQueue internalqueue.SchedulingQueue
}

// PodPreemptor has methods needed to delete a pod and to update 'NominatedPod'
// field of the preemptor pod.
type PodPreemptor interface {
	GetUpdatedPod(pod *v1.Pod) (*v1.Pod, error)
	DeletePod(pod *v1.Pod) error
	SetNominatedNodeName(pod *v1.Pod, nominatedNode string) error
	RemoveNominatedNodeName(pod *v1.Pod) error
}

// Configurator defines I/O, caching, and other functionality needed to
// construct a new scheduler.
type Configurator struct {
	client clientset.Interface
	// a means to list all PersistentVolumes
	pVLister corelisters.PersistentVolumeLister
	// a means to list all PersistentVolumeClaims
	pVCLister corelisters.PersistentVolumeClaimLister
	// a means to list all services
	serviceLister corelisters.ServiceLister
	// a means to list all controllers
	controllerLister corelisters.ReplicationControllerLister
	// a means to list all replicasets
	replicaSetLister appslisters.ReplicaSetLister
	// a means to list all statefulsets
	statefulSetLister appslisters.StatefulSetLister
	// a means to list all PodDisruptionBudgets
	pdbLister policylisters.PodDisruptionBudgetLister
	// a means to list all StorageClasses
	storageClassLister storagelistersv1.StorageClassLister
	// a means to list all CSINodes
	csiNodeLister storagelistersv1beta1.CSINodeLister
	// a means to list all Nodes
	nodeLister corelisters.NodeLister
	// a means to list all Pods
	podLister corelisters.PodLister

	// Close this to stop all reflectors
	StopEverything <-chan struct{}

	scheduledPodsHasSynced cache.InformerSynced

	schedulerCache internalcache.Cache

	// RequiredDuringScheduling affinity is not symmetric, but there is an implicit PreferredDuringScheduling affinity rule
	// corresponding to every RequiredDuringScheduling affinity rule.
	// HardPodAffinitySymmetricWeight represents the weight of implicit PreferredDuringScheduling affinity rule, in the range 0-100.
	hardPodAffinitySymmetricWeight int32

	// Handles volume binding decisions
	volumeBinder *volumebinder.VolumeBinder

	// Always check all predicates even if the middle of one predicate fails.
	alwaysCheckAllPredicates bool

	// Disable pod preemption or not.
	disablePreemption bool

	// percentageOfNodesToScore specifies percentage of all nodes to score in each scheduling cycle.
	percentageOfNodesToScore int32

	bindTimeoutSeconds int64

	enableNonPreempting bool

	// framework configuration arguments.
	registry     framework.Registry
	plugins      *config.Plugins
	pluginConfig []config.PluginConfig
}

// ConfigFactoryArgs is a set arguments passed to NewConfigFactory.
type ConfigFactoryArgs struct {
	Client                         clientset.Interface
	NodeInformer                   coreinformers.NodeInformer
	PodInformer                    coreinformers.PodInformer
	PvInformer                     coreinformers.PersistentVolumeInformer
	PvcInformer                    coreinformers.PersistentVolumeClaimInformer
	ReplicationControllerInformer  coreinformers.ReplicationControllerInformer
	ReplicaSetInformer             appsinformers.ReplicaSetInformer
	StatefulSetInformer            appsinformers.StatefulSetInformer
	ServiceInformer                coreinformers.ServiceInformer
	PdbInformer                    policyinformers.PodDisruptionBudgetInformer
	StorageClassInformer           storageinformersv1.StorageClassInformer
	CSINodeInformer                storageinformersv1beta1.CSINodeInformer
	HardPodAffinitySymmetricWeight int32
	DisablePreemption              bool
	PercentageOfNodesToScore       int32
	BindTimeoutSeconds             int64
	StopCh                         <-chan struct{}
	Registry                       framework.Registry
	Plugins                        *config.Plugins
	PluginConfig                   []config.PluginConfig
}

// NewConfigFactory initializes the default implementation of a Configurator. To encourage eventual privatization of the struct type, we only
// return the interface.
func NewConfigFactory(args *ConfigFactoryArgs) *Configurator {
	stopEverything := args.StopCh
	if stopEverything == nil {
		stopEverything = wait.NeverStop
	}
	schedulerCache := internalcache.New(30*time.Second, stopEverything)

	// storageClassInformer is only enabled through VolumeScheduling feature gate
	var storageClassLister storagelistersv1.StorageClassLister
	if args.StorageClassInformer != nil {
		storageClassLister = args.StorageClassInformer.Lister()
	}

	var csiNodeLister storagelistersv1beta1.CSINodeLister
	if args.CSINodeInformer != nil {
		csiNodeLister = args.CSINodeInformer.Lister()
	}

	c := &Configurator{
		client:                         args.Client,
		pVLister:                       args.PvInformer.Lister(),
		pVCLister:                      args.PvcInformer.Lister(),
		serviceLister:                  args.ServiceInformer.Lister(),
		controllerLister:               args.ReplicationControllerInformer.Lister(),
		replicaSetLister:               args.ReplicaSetInformer.Lister(),
		statefulSetLister:              args.StatefulSetInformer.Lister(),
		pdbLister:                      args.PdbInformer.Lister(),
		nodeLister:                     args.NodeInformer.Lister(),
		podLister:                      args.PodInformer.Lister(),
		storageClassLister:             storageClassLister,
		csiNodeLister:                  csiNodeLister,
		schedulerCache:                 schedulerCache,
		StopEverything:                 stopEverything,
		hardPodAffinitySymmetricWeight: args.HardPodAffinitySymmetricWeight,
		disablePreemption:              args.DisablePreemption,
		percentageOfNodesToScore:       args.PercentageOfNodesToScore,
		bindTimeoutSeconds:             args.BindTimeoutSeconds,
		enableNonPreempting:            utilfeature.DefaultFeatureGate.Enabled(features.NonPreemptingPriority),
		registry:                       args.Registry,
		plugins:                        args.Plugins,
		pluginConfig:                   args.PluginConfig,
	}
	// Setup volume binder
	c.volumeBinder = volumebinder.NewVolumeBinder(args.Client, args.NodeInformer, args.PvcInformer, args.PvInformer, args.StorageClassInformer, time.Duration(args.BindTimeoutSeconds)*time.Second)
	c.scheduledPodsHasSynced = args.PodInformer.Informer().HasSynced

	return c
}

// GetHardPodAffinitySymmetricWeight is exposed for testing.
func (c *Configurator) GetHardPodAffinitySymmetricWeight() int32 {
	return c.hardPodAffinitySymmetricWeight
}

// Create creates a scheduler with the default algorithm provider.
func (c *Configurator) Create() (*Config, error) {
	return c.CreateFromProvider(DefaultProvider)
}

// CreateFromProvider creates a scheduler from the name of a registered algorithm provider.
func (c *Configurator) CreateFromProvider(providerName string) (*Config, error) {
	klog.V(2).Infof("Creating scheduler from algorithm provider '%v'", providerName)
	provider, err := GetAlgorithmProvider(providerName)
	if err != nil {
		return nil, err
	}
	return c.CreateFromKeys(provider.FitPredicateKeys, provider.PriorityFunctionKeys, []algorithm.SchedulerExtender{})
}

// CreateFromConfig creates a scheduler from the configuration file
func (c *Configurator) CreateFromConfig(policy schedulerapi.Policy) (*Config, error) {
	klog.V(2).Infof("Creating scheduler from configuration: %v", policy)

	// validate the policy configuration
	if err := validation.ValidatePolicy(policy); err != nil {
		return nil, err
	}

	predicateKeys := sets.NewString()
	if policy.Predicates == nil {
		klog.V(2).Infof("Using predicates from algorithm provider '%v'", DefaultProvider)
		provider, err := GetAlgorithmProvider(DefaultProvider)
		if err != nil {
			return nil, err
		}
		predicateKeys = provider.FitPredicateKeys
	} else {
		for _, predicate := range policy.Predicates {
			klog.V(2).Infof("Registering predicate: %s", predicate.Name)
			predicateKeys.Insert(RegisterCustomFitPredicate(predicate))
		}
	}

	priorityKeys := sets.NewString()
	if policy.Priorities == nil {
		klog.V(2).Infof("Using priorities from algorithm provider '%v'", DefaultProvider)
		provider, err := GetAlgorithmProvider(DefaultProvider)
		if err != nil {
			return nil, err
		}
		priorityKeys = provider.PriorityFunctionKeys
	} else {
		for _, priority := range policy.Priorities {
			klog.V(2).Infof("Registering priority: %s", priority.Name)
			priorityKeys.Insert(RegisterCustomPriorityFunction(priority))
		}
	}

	var extenders []algorithm.SchedulerExtender
	if len(policy.ExtenderConfigs) != 0 {
		ignoredExtendedResources := sets.NewString()
		var ignorableExtenders []algorithm.SchedulerExtender
		for ii := range policy.ExtenderConfigs {
			klog.V(2).Infof("Creating extender with config %+v", policy.ExtenderConfigs[ii])
			extender, err := core.NewHTTPExtender(&policy.ExtenderConfigs[ii])
			if err != nil {
				return nil, err
			}
			if !extender.IsIgnorable() {
				extenders = append(extenders, extender)
			} else {
				ignorableExtenders = append(ignorableExtenders, extender)
			}
			for _, r := range policy.ExtenderConfigs[ii].ManagedResources {
				if r.IgnoredByScheduler {
					ignoredExtendedResources.Insert(string(r.Name))
				}
			}
		}
		// place ignorable extenders to the tail of extenders
		extenders = append(extenders, ignorableExtenders...)
		predicates.RegisterPredicateMetadataProducerWithExtendedResourceOptions(ignoredExtendedResources)
	}
	// Providing HardPodAffinitySymmetricWeight in the policy config is the new and preferred way of providing the value.
	// Give it higher precedence than scheduler CLI configuration when it is provided.
	if policy.HardPodAffinitySymmetricWeight != 0 {
		c.hardPodAffinitySymmetricWeight = policy.HardPodAffinitySymmetricWeight
	}
	// When AlwaysCheckAllPredicates is set to true, scheduler checks all the configured
	// predicates even after one or more of them fails.
	if policy.AlwaysCheckAllPredicates {
		c.alwaysCheckAllPredicates = policy.AlwaysCheckAllPredicates
	}

	return c.CreateFromKeys(predicateKeys, priorityKeys, extenders)
}

// CreateFromKeys creates a scheduler from a set of registered fit predicate keys and priority keys.
func (c *Configurator) CreateFromKeys(predicateKeys, priorityKeys sets.String, extenders []algorithm.SchedulerExtender) (*Config, error) {
	klog.V(2).Infof("Creating scheduler with fit predicates '%v' and priority functions '%v'", predicateKeys, priorityKeys)

	if c.GetHardPodAffinitySymmetricWeight() < 1 || c.GetHardPodAffinitySymmetricWeight() > 100 {
		return nil, fmt.Errorf("invalid hardPodAffinitySymmetricWeight: %d, must be in the range 1-100", c.GetHardPodAffinitySymmetricWeight())
	}

	predicateFuncs, err := c.GetPredicates(predicateKeys)
	if err != nil {
		return nil, err
	}

	priorityConfigs, err := c.getPriorityFunctionConfigs(priorityKeys)
	if err != nil {
		return nil, err
	}

	priorityMetaProducer, err := c.getPriorityMetadataProducer()
	if err != nil {
		return nil, err
	}

	predicateMetaProducer, err := c.GetPredicateMetadataProducer()
	if err != nil {
		return nil, err
	}

	framework, err := framework.NewFramework(c.registry, c.plugins, c.pluginConfig)
	if err != nil {
		klog.Fatalf("error initializing the scheduling framework: %v", err)
	}

	podQueue := internalqueue.NewSchedulingQueue(c.StopEverything, framework)

	// Setup cache debugger
	debugger := cachedebugger.New(
		c.nodeLister,
		c.podLister,
		c.schedulerCache,
		podQueue,
	)
	debugger.ListenForSignal(c.StopEverything)

	go func() {
		<-c.StopEverything
		podQueue.Close()
	}()

	algo := core.NewGenericScheduler(
		c.schedulerCache,
		podQueue,
		predicateFuncs,
		predicateMetaProducer,
		priorityConfigs,
		priorityMetaProducer,
		framework,
		extenders,
		c.volumeBinder,
		c.pVCLister,
		c.pdbLister,
		c.alwaysCheckAllPredicates,
		c.disablePreemption,
		c.percentageOfNodesToScore,
		c.enableNonPreempting,
	)

	return &Config{
		SchedulerCache:      c.schedulerCache,
		Algorithm:           algo,
		GetBinder:           getBinderFunc(c.client, extenders),
		PodConditionUpdater: &podConditionUpdater{c.client},
		PodPreemptor:        &podPreemptor{c.client},
		Framework:           framework,
		WaitForCacheSync: func() bool {
			return cache.WaitForCacheSync(c.StopEverything, c.scheduledPodsHasSynced)
		},
		NextPod:         internalqueue.MakeNextPodFunc(podQueue),
		Error:           MakeDefaultErrorFunc(c.client, podQueue, c.schedulerCache, c.StopEverything),
		StopEverything:  c.StopEverything,
		VolumeBinder:    c.volumeBinder,
		SchedulingQueue: podQueue,
	}, nil
}

// getBinderFunc returns a func which returns an extender that supports bind or a default binder based on the given pod.
func getBinderFunc(client clientset.Interface, extenders []algorithm.SchedulerExtender) func(pod *v1.Pod) Binder {
	defaultBinder := &binder{client}
	return func(pod *v1.Pod) Binder {
		for _, extender := range extenders {
			if extender.IsBinder() && extender.IsInterested(pod) {
				return extender
			}
		}
		return defaultBinder
	}
}

func (c *Configurator) getPriorityFunctionConfigs(priorityKeys sets.String) ([]priorities.PriorityConfig, error) {
	pluginArgs, err := c.getPluginArgs()
	if err != nil {
		return nil, err
	}

	return getPriorityFunctionConfigs(priorityKeys, *pluginArgs)
}

func (c *Configurator) getPriorityMetadataProducer() (priorities.PriorityMetadataProducer, error) {
	pluginArgs, err := c.getPluginArgs()
	if err != nil {
		return nil, err
	}

	return getPriorityMetadataProducer(*pluginArgs)
}

// GetPredicateMetadataProducer returns a function to build Predicate Metadata.
// It is used by the scheduler and other components, such as k8s.io/autoscaler/cluster-autoscaler.
func (c *Configurator) GetPredicateMetadataProducer() (predicates.PredicateMetadataProducer, error) {
	return getPredicateMetadataProducer()
}

// GetPredicates returns the predicate functions.
// It is used by the scheduler and other components, such as k8s.io/autoscaler/cluster-autoscaler.
func (c *Configurator) GetPredicates(predicateKeys sets.String) (map[string]predicates.FitPredicate, error) {
	pluginArgs, err := c.getPluginArgs()
	if err != nil {
		return nil, err
	}

	return getFitPredicateFunctions(predicateKeys, *pluginArgs)
}

func (c *Configurator) getPluginArgs() (*PluginFactoryArgs, error) {
	return &PluginFactoryArgs{
		PodLister:                      c.schedulerCache,
		ServiceLister:                  c.serviceLister,
		ControllerLister:               c.controllerLister,
		ReplicaSetLister:               c.replicaSetLister,
		StatefulSetLister:              c.statefulSetLister,
		NodeLister:                     c.schedulerCache,
		PDBLister:                      c.pdbLister,
		NodeInfo:                       c.schedulerCache,
		CSINodeInfo:                    c.schedulerCache,
		PVInfo:                         &predicates.CachedPersistentVolumeInfo{PersistentVolumeLister: c.pVLister},
		PVCInfo:                        &predicates.CachedPersistentVolumeClaimInfo{PersistentVolumeClaimLister: c.pVCLister},
		StorageClassInfo:               &predicates.CachedStorageClassInfo{StorageClassLister: c.storageClassLister},
		VolumeBinder:                   c.volumeBinder,
		HardPodAffinitySymmetricWeight: c.hardPodAffinitySymmetricWeight,
	}, nil
}

type podInformer struct {
	informer cache.SharedIndexInformer
}

func (i *podInformer) Informer() cache.SharedIndexInformer {
	return i.informer
}

func (i *podInformer) Lister() corelisters.PodLister {
	return corelisters.NewPodLister(i.informer.GetIndexer())
}

// NewPodInformer creates a shared index informer that returns only non-terminal pods.
func NewPodInformer(client clientset.Interface, resyncPeriod time.Duration) coreinformers.PodInformer {
	selector := fields.ParseSelectorOrDie(
		"status.phase!=" + string(v1.PodSucceeded) +
			",status.phase!=" + string(v1.PodFailed))
	lw := cache.NewListWatchFromClient(client.CoreV1().RESTClient(), string(v1.ResourcePods), metav1.NamespaceAll, selector)
	return &podInformer{
		informer: cache.NewSharedIndexInformer(lw, &v1.Pod{}, resyncPeriod, cache.Indexers{cache.NamespaceIndex: cache.MetaNamespaceIndexFunc}),
	}
}

// MakeDefaultErrorFunc construct a function to handle pod scheduler error
func MakeDefaultErrorFunc(client clientset.Interface, podQueue internalqueue.SchedulingQueue, schedulerCache internalcache.Cache, stopEverything <-chan struct{}) func(pod *v1.Pod, err error) {
	return func(pod *v1.Pod, err error) {
		if err == core.ErrNoNodesAvailable {
			klog.V(2).Infof("Unable to schedule %v/%v: no nodes are registered to the cluster; waiting", pod.Namespace, pod.Name)
		} else {
			if _, ok := err.(*core.FitError); ok {
				klog.V(2).Infof("Unable to schedule %v/%v: no fit: %v; waiting", pod.Namespace, pod.Name, err)
			} else if errors.IsNotFound(err) {
				klog.V(2).Infof("Unable to schedule %v/%v: possibly due to node not found: %v; waiting", pod.Namespace, pod.Name, err)
				if errStatus, ok := err.(errors.APIStatus); ok && errStatus.Status().Details.Kind == "node" {
					nodeName := errStatus.Status().Details.Name
					// when node is not found, We do not remove the node right away. Trying again to get
					// the node and if the node is still not found, then remove it from the scheduler cache.
					_, err := client.CoreV1().Nodes().Get(nodeName, metav1.GetOptions{})
					if err != nil && errors.IsNotFound(err) {
						node := v1.Node{ObjectMeta: metav1.ObjectMeta{Name: nodeName}}
						if err := schedulerCache.RemoveNode(&node); err != nil {
							klog.V(4).Infof("Node %q is not found; failed to remove it from the cache.", node.Name)
						}
					}
				}
			} else {
				klog.Errorf("Error scheduling %v/%v: %v; retrying", pod.Namespace, pod.Name, err)
			}
		}

		podSchedulingCycle := podQueue.SchedulingCycle()
		// Retry asynchronously.
		// Note that this is extremely rudimentary and we need a more real error handling path.
		go func() {
			defer runtime.HandleCrash()
			podID := types.NamespacedName{
				Namespace: pod.Namespace,
				Name:      pod.Name,
			}

			// An unschedulable pod will be placed in the unschedulable queue.
			// This ensures that if the pod is nominated to run on a node,
			// scheduler takes the pod into account when running predicates for the node.
			// Get the pod again; it may have changed/been scheduled already.
			getBackoff := initialGetBackoff
			for {
				pod, err := client.CoreV1().Pods(podID.Namespace).Get(podID.Name, metav1.GetOptions{})
				if err == nil {
					if len(pod.Spec.NodeName) == 0 {
						if err := podQueue.AddUnschedulableIfNotPresent(pod, podSchedulingCycle); err != nil {
							klog.Error(err)
						}
					}
					break
				}
				if errors.IsNotFound(err) {
					klog.Warningf("A pod %v no longer exists", podID)
					return
				}
				klog.Errorf("Error getting pod %v for retry: %v; retrying...", podID, err)
				if getBackoff = getBackoff * 2; getBackoff > maximalGetBackoff {
					getBackoff = maximalGetBackoff
				}
				time.Sleep(getBackoff)
			}
		}()
	}
}

type binder struct {
	Client clientset.Interface
}

// Bind just does a POST binding RPC.
func (b *binder) Bind(binding *v1.Binding) error {
	klog.V(3).Infof("Attempting to bind %v to %v", binding.Name, binding.Target.Name)
	return b.Client.CoreV1().Pods(binding.Namespace).Bind(binding)
}

type podConditionUpdater struct {
	Client clientset.Interface
}

func (p *podConditionUpdater) Update(pod *v1.Pod, condition *v1.PodCondition) error {
	klog.V(3).Infof("Updating pod condition for %s/%s to (%s==%s, Reason=%s)", pod.Namespace, pod.Name, condition.Type, condition.Status, condition.Reason)
	if podutil.UpdatePodCondition(&pod.Status, condition) {
		_, err := p.Client.CoreV1().Pods(pod.Namespace).UpdateStatus(pod)
		return err
	}
	return nil
}

type podPreemptor struct {
	Client clientset.Interface
}

func (p *podPreemptor) GetUpdatedPod(pod *v1.Pod) (*v1.Pod, error) {
	return p.Client.CoreV1().Pods(pod.Namespace).Get(pod.Name, metav1.GetOptions{})
}

func (p *podPreemptor) DeletePod(pod *v1.Pod) error {
	return p.Client.CoreV1().Pods(pod.Namespace).Delete(pod.Name, &metav1.DeleteOptions{})
}

func (p *podPreemptor) SetNominatedNodeName(pod *v1.Pod, nominatedNodeName string) error {
	podCopy := pod.DeepCopy()
	podCopy.Status.NominatedNodeName = nominatedNodeName
	_, err := p.Client.CoreV1().Pods(pod.Namespace).UpdateStatus(podCopy)
	return err
}

func (p *podPreemptor) RemoveNominatedNodeName(pod *v1.Pod) error {
	if len(pod.Status.NominatedNodeName) == 0 {
		return nil
	}
	return p.SetNominatedNodeName(pod, "")
}