Reuse gob.Encoder and Decoder in DeepCopy

pkg/conversion/deep_copy.go

@@ -20,24 +20,49 @@ import (
 	"bytes"
 	"encoding/gob"
 	"reflect"
+	"sync"
 )
 
-// DeepCopy makes a deep copy of source. Won't work for any private fields!
-// For nil slices, will return 0-length slices. These are equivilent in
-// basically every way except for the way that reflect.DeepEqual checks.
+// pool is a pool of copiers
+var pool = sync.Pool{
+	New: func() interface{} { return newGobCopier() },
+}
+
+// DeepCopy makes a deep copy of source or returns an error.
 func DeepCopy(source interface{}) (interface{}, error) {
 	v := reflect.New(reflect.TypeOf(source))
 
-	buff := &bytes.Buffer{}
-	enc := gob.NewEncoder(buff)
-	dec := gob.NewDecoder(buff)
-	err := enc.Encode(source)
-	if err != nil {
-		return nil, err
-	}
-	err = dec.Decode(v.Interface())
-	if err != nil {
+	c := pool.Get().(gobCopier)
+	defer pool.Put(c)
+	if err := c.CopyInto(v.Interface(), source); err != nil {
 		return nil, err
 	}
+
 	return v.Elem().Interface(), nil
 }
+
+// gobCopier provides a copy mechanism for objects using Gob.
+// This object is not safe for multiple threads because buffer
+// is shared.
+type gobCopier struct {
+	enc *gob.Encoder
+	dec *gob.Decoder
+}
+
+func newGobCopier() gobCopier {
+	buf := &bytes.Buffer{}
+	return gobCopier{
+		enc: gob.NewEncoder(buf),
+		dec: gob.NewDecoder(buf),
+	}
+}
+
+func (c *gobCopier) CopyInto(dst, src interface{}) error {
+	if err := c.enc.Encode(src); err != nil {
+		return err
+	}
+	if err := c.dec.Decode(dst); err != nil {
+		return err
+	}
+	return nil
+}

pkg/conversion/deep_copy_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package conversion
 
 import (
+	"math/rand"
 	"reflect"
 	"testing"
 
@@ -106,3 +107,37 @@ func TestDeepCopyPointerSeparate(t *testing.T) {
 		t.Errorf("deep copy wasn't deep: %#q %#q", x, y)
 	}
 }
+
+var result interface{}
+
+func BenchmarkDeepCopy(b *testing.B) {
+	table := []interface{}{
+		map[string]string{},
+		int(5),
+		"hello world",
+		struct {
+			A, B, C struct {
+				D map[string]int
+			}
+			X []int
+			Y []byte
+		}{},
+	}
+
+	f := fuzz.New().RandSource(rand.NewSource(1)).NilChance(.5).NumElements(0, 100)
+	for i := range table {
+		out := table[i]
+		obj := reflect.New(reflect.TypeOf(out)).Interface()
+		f.Fuzz(obj)
+		table[i] = obj
+	}
+
+	b.ResetTimer()
+	var r interface{}
+	for i := 0; i < b.N; i++ {
+		for j := range table {
+			r, _ = DeepCopy(table[j])
+		}
+	}
+	result = r
+}