Clean up names in equivalence package.

Remove stutter from names and provide more idiomatic patterns.

This makes call sites that use equivalence cache easier to read.

pkg/scheduler/core/equivalence/eqivalence.go

@@ -31,19 +31,51 @@ import (
 	"github.com/golang/glog"
 )
 
-// EquivalenceCache saves and reuses the output of predicate functions. Use
-// RunPredicate to get or update the cached results. An appropriate Invalidate*
-// function should be called when some predicate results are no longer valid.
+// Cache saves and reuses the output of predicate functions. Use RunPredicate to
+// get or update the cached results. An appropriate Invalidate* function should
+// be called when some predicate results are no longer valid.
 //
 // Internally, results are keyed by node name, predicate name, and "equivalence
-// class". (Equivalence class is defined in the `EquivalenceClassInfo` type.)
-// Saved results will be reused until an appropriate invalidation function is
-// called.
-type EquivalenceCache struct {
+// class". (Equivalence class is defined in the `Class` type.) Saved results
+// will be reused until an appropriate invalidation function is called.
+type Cache struct {
 	mu    sync.RWMutex
 	cache nodeMap
 }
 
+// NewCache returns an empty Cache.
+func NewCache() *Cache {
+	return &Cache{
+		cache: make(nodeMap),
+	}
+}
+
+// Class represents a set of pods which are equivalent from the perspective of
+// the scheduler. i.e. the scheduler would make the same decision for any pod
+// from the same class.
+type Class struct {
+	// Equivalence hash
+	hash uint64
+}
+
+// NewClass returns the equivalence class for a given Pod. The returned Class
+// objects will be equal for two Pods in the same class. nil values should not
+// be considered equal to each other.
+//
+// NOTE: Make sure to compare types of Class and not *Class.
+// TODO(misterikkit): Return error instead of nil *Class.
+func NewClass(pod *v1.Pod) *Class {
+	equivalencePod := getEquivalencePod(pod)
+	if equivalencePod != nil {
+		hash := fnv.New32a()
+		hashutil.DeepHashObject(hash, equivalencePod)
+		return &Class{
+			hash: uint64(hash.Sum32()),
+		}
+	}
+	return nil
+}
+
 // nodeMap stores PredicateCaches with node name as the key.
 type nodeMap map[string]predicateMap
 
@@ -59,25 +91,17 @@ type predicateResult struct {
 	FailReasons []algorithm.PredicateFailureReason
 }
 
-// NewEquivalenceCache returns EquivalenceCache to speed up predicates by caching
-// result from previous scheduling.
-func NewEquivalenceCache() *EquivalenceCache {
-	return &EquivalenceCache{
-		cache: make(nodeMap),
-	}
-}
-
 // RunPredicate returns a cached predicate result. In case of a cache miss, the predicate will be
 // run and its results cached for the next call.
 //
 // NOTE: RunPredicate will not update the equivalence cache if the given NodeInfo is stale.
-func (ec *EquivalenceCache) RunPredicate(
+func (c *Cache) RunPredicate(
 	pred algorithm.FitPredicate,
 	predicateKey string,
 	pod *v1.Pod,
 	meta algorithm.PredicateMetadata,
 	nodeInfo *schedulercache.NodeInfo,
-	equivClassInfo *EquivalenceClassInfo,
+	equivClass *Class,
 	cache schedulercache.Cache,
 ) (bool, []algorithm.PredicateFailureReason, error) {
 	if nodeInfo == nil || nodeInfo.Node() == nil {
@@ -85,7 +109,7 @@ func (ec *EquivalenceCache) RunPredicate(
 		return false, []algorithm.PredicateFailureReason{}, fmt.Errorf("nodeInfo is nil or node is invalid")
 	}
 
-	result, ok := ec.lookupResult(pod.GetName(), nodeInfo.Node().GetName(), predicateKey, equivClassInfo.hash)
+	result, ok := c.lookupResult(pod.GetName(), nodeInfo.Node().GetName(), predicateKey, equivClass.hash)
 	if ok {
 		return result.Fit, result.FailReasons, nil
 	}
@@ -94,13 +118,13 @@ func (ec *EquivalenceCache) RunPredicate(
 		return fit, reasons, err
 	}
 	if cache != nil {
-		ec.updateResult(pod.GetName(), predicateKey, fit, reasons, equivClassInfo.hash, cache, nodeInfo)
+		c.updateResult(pod.GetName(), predicateKey, fit, reasons, equivClass.hash, cache, nodeInfo)
 	}
 	return fit, reasons, nil
 }
 
 // updateResult updates the cached result of a predicate.
-func (ec *EquivalenceCache) updateResult(
+func (c *Cache) updateResult(
 	podName, predicateKey string,
 	fit bool,
 	reasons []algorithm.PredicateFailureReason,
@@ -108,8 +132,8 @@ func (ec *EquivalenceCache) updateResult(
 	cache schedulercache.Cache,
 	nodeInfo *schedulercache.NodeInfo,
 ) {
-	ec.mu.Lock()
-	defer ec.mu.Unlock()
+	c.mu.Lock()
+	defer c.mu.Unlock()
 	if nodeInfo == nil || nodeInfo.Node() == nil {
 		// This may happen during tests.
 		return
@@ -119,19 +143,19 @@ func (ec *EquivalenceCache) updateResult(
 		return
 	}
 	nodeName := nodeInfo.Node().GetName()
-	if _, exist := ec.cache[nodeName]; !exist {
-		ec.cache[nodeName] = make(predicateMap)
+	if _, exist := c.cache[nodeName]; !exist {
+		c.cache[nodeName] = make(predicateMap)
 	}
 	predicateItem := predicateResult{
 		Fit:         fit,
 		FailReasons: reasons,
 	}
 	// if cached predicate map already exists, just update the predicate by key
-	if predicates, ok := ec.cache[nodeName][predicateKey]; ok {
+	if predicates, ok := c.cache[nodeName][predicateKey]; ok {
 		// maps in golang are references, no need to add them back
 		predicates[equivalenceHash] = predicateItem
 	} else {
-		ec.cache[nodeName][predicateKey] =
+		c.cache[nodeName][predicateKey] =
 			resultMap{
 				equivalenceHash: predicateItem,
 			}
@@ -141,27 +165,27 @@ func (ec *EquivalenceCache) updateResult(
 
 // lookupResult returns cached predicate results and a bool saying whether a
 // cache entry was found.
-func (ec *EquivalenceCache) lookupResult(
+func (c *Cache) lookupResult(
 	podName, nodeName, predicateKey string,
 	equivalenceHash uint64,
 ) (value predicateResult, ok bool) {
-	ec.mu.RLock()
-	defer ec.mu.RUnlock()
+	c.mu.RLock()
+	defer c.mu.RUnlock()
 	glog.V(5).Infof("Begin to calculate predicate: %v for pod: %s on node: %s based on equivalence cache",
 		predicateKey, podName, nodeName)
-	value, ok = ec.cache[nodeName][predicateKey][equivalenceHash]
+	value, ok = c.cache[nodeName][predicateKey][equivalenceHash]
 	return value, ok
 }
 
 // InvalidatePredicates clears all cached results for the given predicates.
-func (ec *EquivalenceCache) InvalidatePredicates(predicateKeys sets.String) {
+func (c *Cache) InvalidatePredicates(predicateKeys sets.String) {
 	if len(predicateKeys) == 0 {
 		return
 	}
-	ec.mu.Lock()
-	defer ec.mu.Unlock()
-	// ec.cache uses nodeName as key, so we just iterate it and invalid given predicates
-	for _, predicates := range ec.cache {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	// c.cache uses nodeName as key, so we just iterate it and invalid given predicates
+	for _, predicates := range c.cache {
 		for predicateKey := range predicateKeys {
 			delete(predicates, predicateKey)
 		}
@@ -170,30 +194,30 @@ func (ec *EquivalenceCache) InvalidatePredicates(predicateKeys sets.String) {
 }
 
 // InvalidatePredicatesOnNode clears cached results for the given predicates on one node.
-func (ec *EquivalenceCache) InvalidatePredicatesOnNode(nodeName string, predicateKeys sets.String) {
+func (c *Cache) InvalidatePredicatesOnNode(nodeName string, predicateKeys sets.String) {
 	if len(predicateKeys) == 0 {
 		return
 	}
-	ec.mu.Lock()
-	defer ec.mu.Unlock()
+	c.mu.Lock()
+	defer c.mu.Unlock()
 	for predicateKey := range predicateKeys {
-		delete(ec.cache[nodeName], predicateKey)
+		delete(c.cache[nodeName], predicateKey)
 	}
 	glog.V(5).Infof("Done invalidating cached predicates: %v on node: %s", predicateKeys, nodeName)
 }
 
 // InvalidateAllPredicatesOnNode clears all cached results for one node.
-func (ec *EquivalenceCache) InvalidateAllPredicatesOnNode(nodeName string) {
-	ec.mu.Lock()
-	defer ec.mu.Unlock()
-	delete(ec.cache, nodeName)
+func (c *Cache) InvalidateAllPredicatesOnNode(nodeName string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	delete(c.cache, nodeName)
 	glog.V(5).Infof("Done invalidating all cached predicates on node: %s", nodeName)
 }
 
 // InvalidateCachedPredicateItemForPodAdd is a wrapper of
 // InvalidateCachedPredicateItem for pod add case
-// TODO: This logic does not belong with the equivalence cache implementation.
-func (ec *EquivalenceCache) InvalidateCachedPredicateItemForPodAdd(pod *v1.Pod, nodeName string) {
+// TODO: This does not belong with the equivalence cache implementation.
+func (c *Cache) InvalidateCachedPredicateItemForPodAdd(pod *v1.Pod, nodeName string) {
 	// MatchInterPodAffinity: we assume scheduler can make sure newly bound pod
 	// will not break the existing inter pod affinity. So we does not need to
 	// invalidate MatchInterPodAffinity when pod added.
@@ -226,30 +250,7 @@ func (ec *EquivalenceCache) InvalidateCachedPredicateItemForPodAdd(pod *v1.Pod,
 			}
 		}
 	}
-	ec.InvalidatePredicatesOnNode(nodeName, invalidPredicates)
-}
-
-// EquivalenceClassInfo holds equivalence hash which is used for checking
-// equivalence cache. We will pass this to podFitsOnNode to ensure equivalence
-// hash is only calculated per schedule.
-type EquivalenceClassInfo struct {
-	// Equivalence hash.
-	hash uint64
-}
-
-// GetEquivalenceClassInfo returns a hash of the given pod. The hashing function
-// returns the same value for any two pods that are equivalent from the
-// perspective of scheduling.
-func (ec *EquivalenceCache) GetEquivalenceClassInfo(pod *v1.Pod) *EquivalenceClassInfo {
-	equivalencePod := getEquivalencePod(pod)
-	if equivalencePod != nil {
-		hash := fnv.New32a()
-		hashutil.DeepHashObject(hash, equivalencePod)
-		return &EquivalenceClassInfo{
-			hash: uint64(hash.Sum32()),
-		}
-	}
-	return nil
+	c.InvalidatePredicatesOnNode(nodeName, invalidPredicates)
 }
 
 // equivalencePod is the set of pod attributes which must match for two pods to

pkg/scheduler/core/equivalence/eqivalence_test.go

@@ -247,8 +247,8 @@ func TestRunPredicate(t *testing.T) {
 			pod := &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "p1"}}
 			meta := algorithm.EmptyPredicateMetadataProducer(nil, nil)
 
-			ecache := NewEquivalenceCache()
-			equivClass := ecache.GetEquivalenceClassInfo(pod)
+			ecache := NewCache()
+			equivClass := NewClass(pod)
 			if test.expectCacheHit {
 				ecache.updateResult(pod.Name, "testPredicate", test.expectFit, test.expectedReasons, equivClass.hash, test.cache, node)
 			}
@@ -339,7 +339,7 @@ func TestUpdateResult(t *testing.T) {
 		},
 	}
 	for _, test := range tests {
-		ecache := NewEquivalenceCache()
+		ecache := NewCache()
 		if test.expectPredicateMap {
 			ecache.cache[test.nodeName] = make(predicateMap)
 			predicateItem := predicateResult{
@@ -473,7 +473,7 @@ func TestLookupResult(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		ecache := NewEquivalenceCache()
+		ecache := NewCache()
 		node := schedulercache.NewNodeInfo()
 		node.SetNode(&v1.Node{ObjectMeta: metav1.ObjectMeta{Name: test.nodeName}})
 		// set cached item to equivalence cache
@@ -527,9 +527,6 @@ func TestLookupResult(t *testing.T) {
 }
 
 func TestGetEquivalenceHash(t *testing.T) {
-
-	ecache := NewEquivalenceCache()
-
 	pod1 := makeBasicPod("pod1")
 	pod2 := makeBasicPod("pod2")
 
@@ -620,7 +617,7 @@ func TestGetEquivalenceHash(t *testing.T) {
 		t.Run(test.name, func(t *testing.T) {
 			for i, podInfo := range test.podInfoList {
 				testPod := podInfo.pod
-				eclassInfo := ecache.GetEquivalenceClassInfo(testPod)
+				eclassInfo := NewClass(testPod)
 				if eclassInfo == nil && podInfo.hashIsValid {
 					t.Errorf("Failed: pod %v is expected to have valid hash", testPod)
 				}
@@ -688,7 +685,7 @@ func TestInvalidateCachedPredicateItemOfAllNodes(t *testing.T) {
 			cache: &upToDateCache{},
 		},
 	}
-	ecache := NewEquivalenceCache()
+	ecache := NewCache()
 
 	for _, test := range tests {
 		node := schedulercache.NewNodeInfo()
@@ -760,7 +757,7 @@ func TestInvalidateAllCachedPredicateItemOfNode(t *testing.T) {
 			cache: &upToDateCache{},
 		},
 	}
-	ecache := NewEquivalenceCache()
+	ecache := NewCache()
 
 	for _, test := range tests {
 		node := schedulercache.NewNodeInfo()

pkg/scheduler/core/generic_scheduler.go

@@ -86,7 +86,7 @@ func (f *FitError) Error() string {
 
 type genericScheduler struct {
 	cache                    schedulercache.Cache
-	equivalenceCache         *equivalence.EquivalenceCache
+	equivalenceCache         *equivalence.Cache
 	schedulingQueue          SchedulingQueue
 	predicates               map[string]algorithm.FitPredicate
 	priorityMetaProducer     algorithm.PriorityMetadataProducer
@@ -343,10 +343,10 @@ func (g *genericScheduler) findNodesThatFit(pod *v1.Pod, nodes []*v1.Node) ([]*v
 		// We can use the same metadata producer for all nodes.
 		meta := g.predicateMetaProducer(pod, g.cachedNodeInfoMap)
 
-		var equivCacheInfo *equivalence.EquivalenceClassInfo
+		var equivClass *equivalence.Class
 		if g.equivalenceCache != nil {
 			// getEquivalenceClassInfo will return immediately if no equivalence pod found
-			equivCacheInfo = g.equivalenceCache.GetEquivalenceClassInfo(pod)
+			equivClass = equivalence.NewClass(pod)
 		}
 
 		checkNode := func(i int) {
@@ -360,7 +360,7 @@ func (g *genericScheduler) findNodesThatFit(pod *v1.Pod, nodes []*v1.Node) ([]*v
 				g.equivalenceCache,
 				g.schedulingQueue,
 				g.alwaysCheckAllPredicates,
-				equivCacheInfo,
+				equivClass,
 			)
 			if err != nil {
 				predicateResultLock.Lock()
@@ -460,10 +460,10 @@ func podFitsOnNode(
 	info *schedulercache.NodeInfo,
 	predicateFuncs map[string]algorithm.FitPredicate,
 	cache schedulercache.Cache,
-	ecache *equivalence.EquivalenceCache,
+	ecache *equivalence.Cache,
 	queue SchedulingQueue,
 	alwaysCheckAllPredicates bool,
-	equivCacheInfo *equivalence.EquivalenceClassInfo,
+	equivClass *equivalence.Class,
 ) (bool, []algorithm.PredicateFailureReason, error) {
 	var (
 		eCacheAvailable  bool
@@ -500,7 +500,7 @@ func podFitsOnNode(
 		// Bypass eCache if node has any nominated pods.
 		// TODO(bsalamat): consider using eCache and adding proper eCache invalidations
 		// when pods are nominated or their nominations change.
-		eCacheAvailable = equivCacheInfo != nil && !podsAdded
+		eCacheAvailable = equivClass != nil && !podsAdded
 		for _, predicateKey := range predicates.Ordering() {
 			var (
 				fit     bool
@@ -510,7 +510,7 @@ func podFitsOnNode(
 			//TODO (yastij) : compute average predicate restrictiveness to export it as Prometheus metric
 			if predicate, exist := predicateFuncs[predicateKey]; exist {
 				if eCacheAvailable {
-					fit, reasons, err = ecache.RunPredicate(predicate, predicateKey, pod, metaToUse, nodeInfoToUse, equivCacheInfo, cache)
+					fit, reasons, err = ecache.RunPredicate(predicate, predicateKey, pod, metaToUse, nodeInfoToUse, equivClass, cache)
 				} else {
 					fit, reasons, err = predicate(pod, metaToUse, nodeInfoToUse)
 				}
@@ -1057,7 +1057,7 @@ func podPassesBasicChecks(pod *v1.Pod, pvcLister corelisters.PersistentVolumeCla
 // NewGenericScheduler creates a genericScheduler object.
 func NewGenericScheduler(
 	cache schedulercache.Cache,
-	eCache *equivalence.EquivalenceCache,
+	eCache *equivalence.Cache,
 	podQueue SchedulingQueue,
 	predicates map[string]algorithm.FitPredicate,
 	predicateMetaProducer algorithm.PredicateMetadataProducer,

pkg/scheduler/core/generic_scheduler_test.go

@@ -1367,10 +1367,10 @@ func (c *syncingMockCache) UpdateNodeNameToInfoMap(infoMap map[string]*scheduler
 	return err
 }
 
-// TestEquivalenceCacheInvalidationRace tests that equivalence cache invalidation is correctly
+// TestCacheInvalidationRace tests that equivalence cache invalidation is correctly
 // handled when an invalidation event happens early in a scheduling cycle. Specifically, the event
 // occurs after schedulercache is snapshotted and before equivalence cache lock is acquired.
-func TestEquivalenceCacheInvalidationRace(t *testing.T) {
+func TestCacheInvalidationRace(t *testing.T) {
 	// Create a predicate that returns false the first time and true on subsequent calls.
 	podWillFit := false
 	var callCount int
@@ -1394,7 +1394,7 @@ func TestEquivalenceCacheInvalidationRace(t *testing.T) {
 		cacheInvalidated: make(chan struct{}),
 	}
 
-	eCache := equivalence.NewEquivalenceCache()
+	eCache := equivalence.NewCache()
 	// Ensure that equivalence cache invalidation happens after the scheduling cycle starts, but before
 	// the equivalence cache would be updated.
 	go func() {

pkg/scheduler/factory/factory.go

@@ -124,7 +124,7 @@ type configFactory struct {
 	hardPodAffinitySymmetricWeight int32
 
 	// Equivalence class cache
-	equivalencePodCache *equivalence.EquivalenceCache
+	equivalencePodCache *equivalence.Cache
 
 	// Enable equivalence class cache
 	enableEquivalenceClassCache bool
@@ -1075,7 +1075,7 @@ func (c *configFactory) CreateFromKeys(predicateKeys, priorityKeys sets.String,
 
 	// Init equivalence class cache
 	if c.enableEquivalenceClassCache {
-		c.equivalencePodCache = equivalence.NewEquivalenceCache()
+		c.equivalencePodCache = equivalence.NewCache()
 		glog.Info("Created equivalence class cache")
 	}
 

pkg/scheduler/scheduler.go

@@ -105,7 +105,7 @@ type Config struct {
 	SchedulerCache schedulercache.Cache
 	// Ecache is used for optimistically invalid affected cache items after
 	// successfully binding a pod
-	Ecache     *equivalence.EquivalenceCache
+	Ecache     *equivalence.Cache
 	NodeLister algorithm.NodeLister
 	Algorithm  algorithm.ScheduleAlgorithm
 	GetBinder  func(pod *v1.Pod) Binder