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/client-go/util/workqueue/parallelizer.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2016 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 workqueue
+
+import (
+	"sync"
+
+	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
+)
+
+type DoWorkPieceFunc func(piece int)
+
+// Parallelize is a very simple framework that allow for parallelizing
+// N independent pieces of work.
+func Parallelize(workers, pieces int, doWorkPiece DoWorkPieceFunc) {
+	toProcess := make(chan int, pieces)
+	for i := 0; i < pieces; i++ {
+		toProcess <- i
+	}
+	close(toProcess)
+
+	if pieces < workers {
+		workers = pieces
+	}
+
+	wg := sync.WaitGroup{}
+	wg.Add(workers)
+	for i := 0; i < workers; i++ {
+		go func() {
+			defer utilruntime.HandleCrash()
+			defer wg.Done()
+			for piece := range toProcess {
+				doWorkPiece(piece)
+			}
+		}()
+	}
+	wg.Wait()
+}