Merge pull request #52753 from munnerz/sample-controller

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

sample-controller: add example CRD controller

**What this PR does / why we need it**:

Adds a sample-controller example repository

fixes #52752

**Special notes for your reviewer**:

This is currently based on the sttts:sttts-codegen-scripts branch and should not be merged until that is (ref https://github.com/kubernetes/kubernetes/pull/52186)

**Release note**:

```
Add sample-controller repository
```

/cc @sttts @nikhita @colemickens

Kubernetes-commit: 9a7800f7d2efb88b397674672ac56f898826cf7c

vendor/k8s.io/apimachinery/pkg/util/cache/cache.go

@@ -0,0 +1,83 @@
+/*
+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 cache
+
+import (
+	"sync"
+)
+
+const (
+	shardsCount int = 32
+)
+
+type Cache []*cacheShard
+
+func NewCache(maxSize int) Cache {
+	if maxSize < shardsCount {
+		maxSize = shardsCount
+	}
+	cache := make(Cache, shardsCount)
+	for i := 0; i < shardsCount; i++ {
+		cache[i] = &cacheShard{
+			items:   make(map[uint64]interface{}),
+			maxSize: maxSize / shardsCount,
+		}
+	}
+	return cache
+}
+
+func (c Cache) getShard(index uint64) *cacheShard {
+	return c[index%uint64(shardsCount)]
+}
+
+// Returns true if object already existed, false otherwise.
+func (c *Cache) Add(index uint64, obj interface{}) bool {
+	return c.getShard(index).add(index, obj)
+}
+
+func (c *Cache) Get(index uint64) (obj interface{}, found bool) {
+	return c.getShard(index).get(index)
+}
+
+type cacheShard struct {
+	items map[uint64]interface{}
+	sync.RWMutex
+	maxSize int
+}
+
+// Returns true if object already existed, false otherwise.
+func (s *cacheShard) add(index uint64, obj interface{}) bool {
+	s.Lock()
+	defer s.Unlock()
+	_, isOverwrite := s.items[index]
+	if !isOverwrite && len(s.items) >= s.maxSize {
+		var randomKey uint64
+		for randomKey = range s.items {
+			break
+		}
+		delete(s.items, randomKey)
+	}
+	s.items[index] = obj
+	return isOverwrite
+}
+
+func (s *cacheShard) get(index uint64) (obj interface{}, found bool) {
+	s.RLock()
+	defer s.RUnlock()
+	obj, found = s.items[index]
+	return
+}