encoding/gob: make benchmarks parallel

There are lots of internal synchronization in gob,
so it makes sense to have parallel benchmarks.
Also add a benchmark with slices and interfaces.

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/115960043

diff --git a/src/pkg/encoding/gob/timing_test.go b/src/pkg/encoding/gob/timing_test.go
index acfb065b1288cce4820a86e1c3daf4360cd4e9f5..29c9b858b6b20dc873002bb20b99eb7f649fcbb2 100644 (file)
--- a/src/pkg/encoding/gob/timing_test.go
+++ b/src/pkg/encoding/gob/timing_test.go
@@ -19,33 +19,52 @@ type Bench struct {
        D []byte
 }
 
-func benchmarkEndToEnd(r io.Reader, w io.Writer, b *testing.B) {
-       b.StopTimer()
-       enc := NewEncoder(w)
-       dec := NewDecoder(r)
-       bench := &Bench{7, 3.2, "now is the time", bytes.Repeat([]byte("for all good men"), 100)}
-       b.StartTimer()
-       for i := 0; i < b.N; i++ {
-               if enc.Encode(bench) != nil {
-                       panic("encode error")
+func benchmarkEndToEnd(b *testing.B, v interface{}, pipe func() (r io.Reader, w io.Writer, err error)) {
+       b.RunParallel(func(pb *testing.PB) {
+               r, w, err := pipe()
+               if err != nil {
+                       b.Fatal("can't get pipe:", err)
                }
-               if dec.Decode(bench) != nil {
-                       panic("decode error")
+               enc := NewEncoder(w)
+               dec := NewDecoder(r)
+               for pb.Next() {
+                       if err := enc.Encode(v); err != nil {
+                               b.Fatal("encode error:", err)
+                       }
+                       if err := dec.Decode(v); err != nil {
+                               b.Fatal("decode error:", err)
+                       }
                }
-       }
+       })
 }
 
 func BenchmarkEndToEndPipe(b *testing.B) {
-       r, w, err := os.Pipe()
-       if err != nil {
-               b.Fatal("can't get pipe:", err)
-       }
-       benchmarkEndToEnd(r, w, b)
+       v := &Bench{7, 3.2, "now is the time", bytes.Repeat([]byte("for all good men"), 100)}
+       benchmarkEndToEnd(b, v, func() (r io.Reader, w io.Writer, err error) {
+               r, w, err = os.Pipe()
+               return
+       })
 }
 
 func BenchmarkEndToEndByteBuffer(b *testing.B) {
-       var buf bytes.Buffer
-       benchmarkEndToEnd(&buf, &buf, b)
+       v := &Bench{7, 3.2, "now is the time", bytes.Repeat([]byte("for all good men"), 100)}
+       benchmarkEndToEnd(b, v, func() (r io.Reader, w io.Writer, err error) {
+               var buf bytes.Buffer
+               return &buf, &buf, nil
+       })
+}
+
+func BenchmarkEndToEndSliceByteBuffer(b *testing.B) {
+       v := &Bench{7, 3.2, "now is the time", nil}
+       Register(v)
+       arr := make([]interface{}, 100)
+       for i := range arr {
+               arr[i] = v
+       }
+       benchmarkEndToEnd(b, &arr, func() (r io.Reader, w io.Writer, err error) {
+               var buf bytes.Buffer
+               return &buf, &buf, nil
+       })
 }
 
 func TestCountEncodeMallocs(t *testing.T) {