Merge pull request #76330 from wojtek-t/simplify_watchcache

Slightly simplify watchcache

staging/src/k8s.io/apiserver/pkg/storage/cacher/watch_cache.go

@@ -77,14 +77,6 @@ func storeElementKey(obj interface{}) (string, error) {
 	return elem.Key, nil
 }
 
-// watchCacheElement is a single "watch event" stored in a cache.
-// It contains the resource version of the object and the object
-// itself.
-type watchCacheElement struct {
-	resourceVersion uint64
-	watchCacheEvent *watchCacheEvent
-}
-
 // watchCache implements a Store interface.
 // However, it depends on the elements implementing runtime.Object interface.
 //
@@ -111,7 +103,7 @@ type watchCache struct {
 	// by endIndex (if cache is full it will be startIndex + capacity).
 	// Both startIndex and endIndex can be greater than buffer capacity -
 	// you should always apply modulo capacity to get an index in cache array.
-	cache      []watchCacheElement
+	cache      []*watchCacheEvent
 	startIndex int
 	endIndex   int
 
@@ -150,7 +142,7 @@ func newWatchCache(
 		capacity:            capacity,
 		keyFunc:             keyFunc,
 		getAttrsFunc:        getAttrsFunc,
-		cache:               make([]watchCacheElement, capacity),
+		cache:               make([]*watchCacheEvent, capacity),
 		startIndex:          0,
 		endIndex:            0,
 		store:               cache.NewStore(storeElementKey),
@@ -247,23 +239,23 @@ func (w *watchCache) processEvent(event watch.Event, resourceVersion uint64, upd
 		watchCacheEvent.PrevObjLabels = previousElem.Labels
 		watchCacheEvent.PrevObjFields = previousElem.Fields
 	}
+	w.updateCache(watchCacheEvent)
+	w.resourceVersion = resourceVersion
 
 	if w.onEvent != nil {
 		w.onEvent(watchCacheEvent)
 	}
-	w.updateCache(resourceVersion, watchCacheEvent)
-	w.resourceVersion = resourceVersion
 	w.cond.Broadcast()
 	return updateFunc(elem)
 }
 
 // Assumes that lock is already held for write.
-func (w *watchCache) updateCache(resourceVersion uint64, event *watchCacheEvent) {
+func (w *watchCache) updateCache(event *watchCacheEvent) {
 	if w.endIndex == w.startIndex+w.capacity {
 		// Cache is full - remove the oldest element.
 		w.startIndex++
 	}
-	w.cache[w.endIndex%w.capacity] = watchCacheElement{resourceVersion, event}
+	w.cache[w.endIndex%w.capacity] = event
 	w.endIndex++
 }
 
@@ -416,7 +408,7 @@ func (w *watchCache) GetAllEventsSinceThreadUnsafe(resourceVersion uint64) ([]*w
 	case size >= w.capacity:
 		// Once the watch event buffer is full, the oldest watch event we can deliver
 		// is the first one in the buffer.
-		oldest = w.cache[w.startIndex%w.capacity].resourceVersion
+		oldest = w.cache[w.startIndex%w.capacity].ResourceVersion
 	case w.listResourceVersion > 0:
 		// If the watch event buffer isn't full, the oldest watch event we can deliver
 		// is one greater than the resource version of the last full list.
@@ -426,7 +418,7 @@ func (w *watchCache) GetAllEventsSinceThreadUnsafe(resourceVersion uint64) ([]*w
 		// in the buffer.
 		// This should only happen in unit tests that populate the buffer without
 		// performing list/replace operations.
-		oldest = w.cache[w.startIndex%w.capacity].resourceVersion
+		oldest = w.cache[w.startIndex%w.capacity].ResourceVersion
 	default:
 		return nil, fmt.Errorf("watch cache isn't correctly initialized")
 	}
@@ -466,12 +458,12 @@ func (w *watchCache) GetAllEventsSinceThreadUnsafe(resourceVersion uint64) ([]*w
 
 	// Binary search the smallest index at which resourceVersion is greater than the given one.
 	f := func(i int) bool {
-		return w.cache[(w.startIndex+i)%w.capacity].resourceVersion > resourceVersion
+		return w.cache[(w.startIndex+i)%w.capacity].ResourceVersion > resourceVersion
 	}
 	first := sort.Search(size, f)
 	result := make([]*watchCacheEvent, size-first)
 	for i := 0; i < size-first; i++ {
-		result[i] = w.cache[(w.startIndex+first+i)%w.capacity].watchCacheEvent
+		result[i] = w.cache[(w.startIndex+first+i)%w.capacity]
 	}
 	return result, nil
 }