Add cache with multiple shards to decrease lock contention

pkg/util/cache_test.go

@@ -0,0 +1,65 @@
+/*
+Copyright 2014 The Kubernetes Authors All rights reserved.
+
+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 util
+
+import (
+	"testing"
+)
+
+const (
+	maxTestCacheSize int = shardsCount * 2
+)
+
+func ExpectEntry(t *testing.T, cache Cache, index uint64, expectedValue interface{}) {
+	elem, found := cache.Get(index)
+	if !found {
+		t.Error("Expected to find entry with key 1")
+	} else if elem != expectedValue {
+		t.Errorf("Expected to find %v, got %v", expectedValue, elem)
+	}
+}
+
+func TestBasic(t *testing.T) {
+	cache := NewCache(maxTestCacheSize)
+	cache.Add(1, "xxx")
+	ExpectEntry(t, cache, 1, "xxx")
+}
+
+func TestOverflow(t *testing.T) {
+	cache := NewCache(maxTestCacheSize)
+	for i := 0; i < maxTestCacheSize+1; i++ {
+		cache.Add(uint64(i), "xxx")
+	}
+	foundIndexes := make([]uint64, 0)
+	for i := 0; i < maxTestCacheSize+1; i++ {
+		_, found := cache.Get(uint64(i))
+		if found {
+			foundIndexes = append(foundIndexes, uint64(i))
+		}
+	}
+	if len(foundIndexes) != maxTestCacheSize {
+		t.Errorf("Expect to find %d elements, got %d %v", maxTestCacheSize, len(foundIndexes), foundIndexes)
+	}
+}
+
+func TestOverwrite(t *testing.T) {
+	cache := NewCache(maxTestCacheSize)
+	cache.Add(1, "xxx")
+	ExpectEntry(t, cache, 1, "xxx")
+	cache.Add(1, "yyy")
+	ExpectEntry(t, cache, 1, "yyy")
+}