Add chunk size option to ParallelizeUntil

Signed-off-by: Aldo Culquicondor <acondor@google.com>

Kubernetes-commit: 36efa035e292480d4b0ccc7a4ffbf9aa579fbf30

util/workqueue/parallelizer_test.go

@@ -0,0 +1,106 @@
+/*
+Copyright 2020 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 (
+	"context"
+	"fmt"
+	"sync/atomic"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+type testCase struct {
+	pieces    int
+	workers   int
+	chunkSize int
+}
+
+func (c testCase) String() string {
+	return fmt.Sprintf("pieces:%d,workers:%d,chunkSize:%d", c.pieces, c.workers, c.chunkSize)
+}
+
+var cases = []testCase{
+	{
+		pieces:    1000,
+		workers:   10,
+		chunkSize: 1,
+	},
+	{
+		pieces:    1000,
+		workers:   10,
+		chunkSize: 10,
+	},
+	{
+		pieces:    1000,
+		workers:   10,
+		chunkSize: 100,
+	},
+	{
+		pieces:    999,
+		workers:   10,
+		chunkSize: 13,
+	},
+}
+
+func TestParallelizeUntil(t *testing.T) {
+	for _, tc := range cases {
+		t.Run(tc.String(), func(t *testing.T) {
+			seen := make([]int32, tc.pieces)
+			ctx := context.Background()
+			ParallelizeUntil(ctx, tc.workers, tc.pieces, func(p int) {
+				atomic.AddInt32(&seen[p], 1)
+			}, WithChunkSize(tc.chunkSize))
+
+			wantSeen := make([]int32, tc.pieces)
+			for i := 0; i < tc.pieces; i++ {
+				wantSeen[i] = 1
+			}
+			if diff := cmp.Diff(wantSeen, seen); diff != "" {
+				t.Errorf("bad number of visits (-want,+got):\n%s", diff)
+			}
+		})
+	}
+}
+
+func BenchmarkParallelizeUntil(b *testing.B) {
+	for _, tc := range cases {
+		b.Run(tc.String(), func(b *testing.B) {
+			ctx := context.Background()
+			isPrime := make([]bool, tc.pieces)
+			for c := 0; c < b.N; c++ {
+				ParallelizeUntil(ctx, tc.workers, tc.pieces, func(p int) {
+					if p <= 1 {
+						return
+					}
+					isPrime[p] = true
+					for i := 2; i*i <= p; i++ {
+						if p%i == 0 {
+							isPrime[p] = false
+							return
+						}
+					}
+				}, WithChunkSize(tc.chunkSize))
+			}
+			want := []bool{false, false, true, true, false, true, false, true, false, false, false, true}
+			if diff := cmp.Diff(want, isPrime[:len(want)]); diff != "" {
+				b.Errorf("miscalculated isPrime (-want,+got):\n%s", diff)
+			}
+		})
+	}
+}