Add printer benchmarks (#109085)

* Code cleanup

- Remove redundant parentheses.
- Remove unnecessary type conversion of string to string.
- Fix wrong function name in comment.

* Add printer benchmarks

staging/src/k8s.io/cli-runtime/pkg/printers/bench_test.go

@@ -0,0 +1,152 @@
+/*
+Copyright 2022 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 printers
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/client-go/kubernetes/scheme"
+)
+
+func newBenchmarkList() *unstructured.UnstructuredList {
+	list := &unstructured.UnstructuredList{
+		Object: map[string]interface{}{
+			"apiVersion": "v1",
+			"kind":       "PodList",
+		},
+		Items: []unstructured.Unstructured{},
+	}
+	for i := 0; i < 1000; i++ {
+		list.Items = append(list.Items, unstructured.Unstructured{
+			Object: map[string]interface{}{
+				"apiVersion": "v1",
+				"kind":       "Pod",
+				"metadata": map[string]interface{}{
+					"name":      fmt.Sprintf("pod%d", i),
+					"namespace": "ns",
+					"labels": map[string]interface{}{
+						"first-label":  "12",
+						"second-label": "label-value",
+					},
+				},
+			},
+		})
+	}
+	return list
+}
+
+func newBenchmarkTable() *metav1.Table {
+	table := &metav1.Table{
+		ColumnDefinitions: []metav1.TableColumnDefinition{
+			{Name: "Name", Type: "string"},
+			{Name: "Ready", Type: "string"},
+			{Name: "Status", Type: "string"},
+			{Name: "Retries", Type: "integer"},
+			{Name: "Age", Type: "string"},
+		},
+		Rows: []metav1.TableRow{},
+	}
+	for _, pod := range newBenchmarkList().Items {
+		raw, _ := json.Marshal(pod)
+		table.Rows = append(table.Rows, metav1.TableRow{
+			Cells: []interface{}{pod.GetName(), "1/1", "Ready", int64(0), "20h"},
+			Object: runtime.RawExtension{
+				Raw:    raw,
+				Object: &pod,
+			},
+		})
+	}
+	return table
+}
+
+func BenchmarkDiscardingPrinter(b *testing.B) {
+	data := newBenchmarkList()
+	b.ResetTimer()
+	benchmarkPrinter(b, func() ResourcePrinter { return NewDiscardingPrinter() }, data)
+}
+
+func BenchmarkJSONPrinter(b *testing.B) {
+	data := newBenchmarkList()
+	b.ResetTimer()
+	benchmarkPrinter(b, func() ResourcePrinter { return &JSONPrinter{} }, data)
+}
+
+func BenchmarkJSONPathPrinter(b *testing.B) {
+	data := newBenchmarkList()
+	b.ResetTimer()
+	benchmarkPrinter(b, func() ResourcePrinter {
+		printer, _ := NewJSONPathPrinter("{range .items[*]}{.metadata.name}\n{end}")
+		return printer
+	}, data)
+}
+
+func BenchmarkYAMLPrinter(b *testing.B) {
+	data := newBenchmarkList()
+	b.ResetTimer()
+	benchmarkPrinter(b, func() ResourcePrinter { return &YAMLPrinter{} }, data)
+}
+
+func BenchmarkTablePrinter(b *testing.B) {
+	data := newBenchmarkTable()
+	b.ResetTimer()
+	benchmarkPrinter(b, func() ResourcePrinter { return NewTablePrinter(PrintOptions{}) }, data)
+}
+
+func BenchmarkGoTemplatePrinter(b *testing.B) {
+	data := newBenchmarkList()
+	b.ResetTimer()
+	benchmarkPrinter(b, func() ResourcePrinter {
+		printer, _ := NewGoTemplatePrinter([]byte("{{range .items}}{{.metadata.name}}{{\"\\n\"}}{{end}}"))
+		return printer
+	}, data)
+}
+
+func BenchmarkNamePrinter(b *testing.B) {
+	data := newBenchmarkList()
+	b.ResetTimer()
+	benchmarkPrinter(b, func() ResourcePrinter { return &NamePrinter{} }, data)
+}
+
+func BenchmarkOmitManagedFieldsPrinter(b *testing.B) {
+	data := newBenchmarkList()
+	b.ResetTimer()
+	benchmarkPrinter(b, func() ResourcePrinter { return &OmitManagedFieldsPrinter{Delegate: NewDiscardingPrinter()} }, data)
+}
+
+func BenchmarkTypeSetterPrinter(b *testing.B) {
+	data := newBenchmarkList()
+	b.ResetTimer()
+	benchmarkPrinter(b, func() ResourcePrinter { return NewTypeSetter(scheme.Scheme).ToPrinter(NewDiscardingPrinter()) }, data)
+}
+
+func benchmarkPrinter(b *testing.B, printerFunc func() ResourcePrinter, data runtime.Object) {
+	b.ReportAllocs()
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			buf := &bytes.Buffer{}
+			if err := printerFunc().PrintObj(data, buf); err != nil {
+				b.Errorf("PrintObj failed: %v", err)
+			}
+		}
+	})
+}

staging/src/k8s.io/cli-runtime/pkg/printers/interface.go

@@ -33,7 +33,7 @@ func (fn ResourcePrinterFunc) PrintObj(obj runtime.Object, w io.Writer) error {
 
 // ResourcePrinter is an interface that knows how to print runtime objects.
 type ResourcePrinter interface {
-	// Print receives a runtime object, formats it and prints it to a writer.
+	// PrintObj receives a runtime object, formats it and prints it to a writer.
 	PrintObj(runtime.Object, io.Writer) error
 }
 

staging/src/k8s.io/cli-runtime/pkg/printers/tableprinter.go

@@ -449,7 +449,7 @@ func formatEventType(eventType string) string {
 	if formatted, ok := formattedEventType[eventType]; ok {
 		return formatted
 	}
-	return string(eventType)
+	return eventType
 }
 
 // printRows writes the provided rows to output.
@@ -499,7 +499,7 @@ func formatLabelHeaders(columnLabels []string) []string {
 	formHead := make([]string, len(columnLabels))
 	for i, l := range columnLabels {
 		p := strings.Split(l, "/")
-		formHead[i] = strings.ToUpper((p[len(p)-1]))
+		formHead[i] = strings.ToUpper(p[len(p)-1])
 	}
 	return formHead
 }