Merge pull request kubernetes#75585 from tiffanyfay/cache

Updated client-go expiration cache to take in expiration policies

Author: k8s-ci-robot

staging/src/k8s.io/client-go/tools/cache/expiration_cache.go

@@ -48,7 +48,7 @@ type ExpirationCache struct {
 // ExpirationPolicy dictates when an object expires. Currently only abstracted out
 // so unittests don't rely on the system clock.
 type ExpirationPolicy interface {
-	IsExpired(obj *timestampedEntry) bool
+	IsExpired(obj *TimestampedEntry) bool
 }
 
 // TTLPolicy implements a ttl based ExpirationPolicy.
@@ -63,26 +63,29 @@ type TTLPolicy struct {
 
 // IsExpired returns true if the given object is older than the ttl, or it can't
 // determine its age.
-func (p *TTLPolicy) IsExpired(obj *timestampedEntry) bool {
-	return p.Ttl > 0 && p.Clock.Since(obj.timestamp) > p.Ttl
+func (p *TTLPolicy) IsExpired(obj *TimestampedEntry) bool {
+	return p.Ttl > 0 && p.Clock.Since(obj.Timestamp) > p.Ttl
 }
 
-// timestampedEntry is the only type allowed in a ExpirationCache.
-type timestampedEntry struct {
-	obj       interface{}
-	timestamp time.Time
+// TimestampedEntry is the only type allowed in a ExpirationCache.
+// Keep in mind that it is not safe to share timestamps between computers.
+// Behavior may be inconsistent if you get a timestamp from the API Server and
+// use it on the client machine as part of your ExpirationCache.
+type TimestampedEntry struct {
+	Obj       interface{}
+	Timestamp time.Time
 }
 
-// getTimestampedEntry returns the timestampedEntry stored under the given key.
-func (c *ExpirationCache) getTimestampedEntry(key string) (*timestampedEntry, bool) {
+// getTimestampedEntry returns the TimestampedEntry stored under the given key.
+func (c *ExpirationCache) getTimestampedEntry(key string) (*TimestampedEntry, bool) {
 	item, _ := c.cacheStorage.Get(key)
-	if tsEntry, ok := item.(*timestampedEntry); ok {
+	if tsEntry, ok := item.(*TimestampedEntry); ok {
 		return tsEntry, true
 	}
 	return nil, false
 }
 
-// getOrExpire retrieves the object from the timestampedEntry if and only if it hasn't
+// getOrExpire retrieves the object from the TimestampedEntry if and only if it hasn't
 // already expired. It holds a write lock across deletion.
 func (c *ExpirationCache) getOrExpire(key string) (interface{}, bool) {
 	// Prevent all inserts from the time we deem an item as "expired" to when we
@@ -95,11 +98,11 @@ func (c *ExpirationCache) getOrExpire(key string) (interface{}, bool) {
 		return nil, false
 	}
 	if c.expirationPolicy.IsExpired(timestampedItem) {
-		klog.V(4).Infof("Entry %v: %+v has expired", key, timestampedItem.obj)
+		klog.V(4).Infof("Entry %v: %+v has expired", key, timestampedItem.Obj)
 		c.cacheStorage.Delete(key)
 		return nil, false
 	}
-	return timestampedItem.obj, true
+	return timestampedItem.Obj, true
 }
 
 // GetByKey returns the item stored under the key, or sets exists=false.
@@ -126,7 +129,7 @@ func (c *ExpirationCache) List() []interface{} {
 
 	list := make([]interface{}, 0, len(items))
 	for _, item := range items {
-		obj := item.(*timestampedEntry).obj
+		obj := item.(*TimestampedEntry).Obj
 		if key, err := c.keyFunc(obj); err != nil {
 			list = append(list, obj)
 		} else if obj, exists := c.getOrExpire(key); exists {
@@ -151,7 +154,7 @@ func (c *ExpirationCache) Add(obj interface{}) error {
 	c.expirationLock.Lock()
 	defer c.expirationLock.Unlock()
 
-	c.cacheStorage.Add(key, &timestampedEntry{obj, c.clock.Now()})
+	c.cacheStorage.Add(key, &TimestampedEntry{obj, c.clock.Now()})
 	return nil
 }
 
@@ -184,7 +187,7 @@ func (c *ExpirationCache) Replace(list []interface{}, resourceVersion string) er
 		if err != nil {
 			return KeyError{item, err}
 		}
-		items[key] = &timestampedEntry{item, ts}
+		items[key] = &TimestampedEntry{item, ts}
 	}
 	c.expirationLock.Lock()
 	defer c.expirationLock.Unlock()
@@ -199,10 +202,15 @@ func (c *ExpirationCache) Resync() error {
 
 // NewTTLStore creates and returns a ExpirationCache with a TTLPolicy
 func NewTTLStore(keyFunc KeyFunc, ttl time.Duration) Store {
+	return NewExpirationStore(keyFunc, &TTLPolicy{ttl, clock.RealClock{}})
+}
+
+// NewExpirationStore creates and returns a ExpirationCache for a given policy
+func NewExpirationStore(keyFunc KeyFunc, expirationPolicy ExpirationPolicy) Store {
 	return &ExpirationCache{
 		cacheStorage:     NewThreadSafeStore(Indexers{}, Indices{}),
 		keyFunc:          keyFunc,
 		clock:            clock.RealClock{},
-		expirationPolicy: &TTLPolicy{ttl, clock.RealClock{}},
+		expirationPolicy: expirationPolicy,
 	}
 }

staging/src/k8s.io/client-go/tools/cache/expiration_cache_fakes.go

@@ -38,7 +38,7 @@ type FakeExpirationPolicy struct {
 	RetrieveKeyFunc KeyFunc
 }
 
-func (p *FakeExpirationPolicy) IsExpired(obj *timestampedEntry) bool {
+func (p *FakeExpirationPolicy) IsExpired(obj *TimestampedEntry) bool {
 	key, _ := p.RetrieveKeyFunc(obj)
 	return !p.NeverExpire.Has(key)
 }

staging/src/k8s.io/client-go/tools/cache/expiration_cache_test.go

@@ -34,7 +34,7 @@ func TestTTLExpirationBasic(t *testing.T) {
 		&FakeExpirationPolicy{
 			NeverExpire: sets.NewString(),
 			RetrieveKeyFunc: func(obj interface{}) (string, error) {
-				return obj.(*timestampedEntry).obj.(testStoreObject).id, nil
+				return obj.(*TimestampedEntry).Obj.(testStoreObject).id, nil
 			},
 		},
 		clock.RealClock{},
@@ -67,7 +67,7 @@ func TestReAddExpiredItem(t *testing.T) {
 	exp := &FakeExpirationPolicy{
 		NeverExpire: sets.NewString(),
 		RetrieveKeyFunc: func(obj interface{}) (string, error) {
-			return obj.(*timestampedEntry).obj.(testStoreObject).id, nil
+			return obj.(*TimestampedEntry).Obj.(testStoreObject).id, nil
 		},
 	}
 	ttlStore := NewFakeExpirationStore(
@@ -130,7 +130,7 @@ func TestTTLList(t *testing.T) {
 		&FakeExpirationPolicy{
 			NeverExpire: sets.NewString(testObjs[1].id),
 			RetrieveKeyFunc: func(obj interface{}) (string, error) {
-				return obj.(*timestampedEntry).obj.(testStoreObject).id, nil
+				return obj.(*TimestampedEntry).Obj.(testStoreObject).id, nil
 			},
 		},
 		clock.RealClock{},
@@ -168,15 +168,15 @@ func TestTTLPolicy(t *testing.T) {
 	expiredTime := fakeTime.Add(-(ttl + 1))
 
 	policy := TTLPolicy{ttl, clock.NewFakeClock(fakeTime)}
-	fakeTimestampedEntry := &timestampedEntry{obj: struct{}{}, timestamp: exactlyOnTTL}
+	fakeTimestampedEntry := &TimestampedEntry{Obj: struct{}{}, Timestamp: exactlyOnTTL}
 	if policy.IsExpired(fakeTimestampedEntry) {
 		t.Errorf("TTL cache should not expire entries exactly on ttl")
 	}
-	fakeTimestampedEntry.timestamp = fakeTime
+	fakeTimestampedEntry.Timestamp = fakeTime
 	if policy.IsExpired(fakeTimestampedEntry) {
 		t.Errorf("TTL Cache should not expire entries before ttl")
 	}
-	fakeTimestampedEntry.timestamp = expiredTime
+	fakeTimestampedEntry.Timestamp = expiredTime
 	if !policy.IsExpired(fakeTimestampedEntry) {
 		t.Errorf("TTL Cache should expire entries older than ttl")
 	}