encoding/pem: eliminate allocations for newlines during encoding

benchmark           old MB/s     new MB/s     speedup
BenchmarkEncode     243.20       279.89       1.15x

benchmark           old allocs     new allocs     delta
BenchmarkEncode     1370           4              -99.71%

Change-Id: I3920bcc04b6dd89efa5da89db5594d4434426d74
Reviewed-on: https://go-review.googlesource.com/1924
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/encoding/pem/pem.go b/src/encoding/pem/pem.go
index 8ff7ee8c33ab4387b7f34f50280335efd0e8fd4e..90fe3dc50cf16cca37e1269807544545a768ab9a 100644 (file)
--- a/src/encoding/pem/pem.go
+++ b/src/encoding/pem/pem.go
@@ -171,6 +171,8 @@ type lineBreaker struct {
        out  io.Writer
 }
 
+var nl = []byte{'\n'}
+
 func (l *lineBreaker) Write(b []byte) (n int, err error) {
        if l.used+len(b) < pemLineLength {
                copy(l.line[l.used:], b)
@@ -190,7 +192,7 @@ func (l *lineBreaker) Write(b []byte) (n int, err error) {
                return
        }
 
-       n, err = l.out.Write([]byte{'\n'})
+       n, err = l.out.Write(nl)
        if err != nil {
                return
        }
@@ -204,7 +206,7 @@ func (l *lineBreaker) Close() (err error) {
                if err != nil {
                        return
                }
-               _, err = l.out.Write([]byte{'\n'})
+               _, err = l.out.Write(nl)
        }
 
        return
@@ -248,7 +250,7 @@ func Encode(out io.Writer, b *Block) error {
                                return err
                        }
                }
-               if _, err := out.Write([]byte{'\n'}); err != nil {
+               if _, err := out.Write(nl); err != nil {
                        return err
                }
        }

diff --git a/src/encoding/pem/pem_test.go b/src/encoding/pem/pem_test.go
index ccce42cf1ffa538143b05712af00e5e19570eafc..92451feff89ed46062749c0ddb67c948fea558ae 100644 (file)
--- a/src/encoding/pem/pem_test.go
+++ b/src/encoding/pem/pem_test.go
@@ -6,6 +6,7 @@ package pem
 
 import (
        "bytes"
+       "io/ioutil"
        "reflect"
        "testing"
 )
@@ -116,6 +117,24 @@ func TestLineBreaker(t *testing.T) {
        }
 }
 
+func BenchmarkEncode(b *testing.B) {
+       data := &Block{Bytes: make([]byte, 65536)}
+       b.SetBytes(int64(len(data.Bytes)))
+       for i := 0; i < b.N; i++ {
+               Encode(ioutil.Discard, data)
+       }
+}
+
+func BenchmarkDecode(b *testing.B) {
+       block := &Block{Bytes: make([]byte, 65536)}
+       data := EncodeToMemory(block)
+       b.SetBytes(int64(len(data)))
+       b.ResetTimer()
+       for i := 0; i < b.N; i++ {
+               Decode(data)
+       }
+}
+
 var pemData = `verify return:0
 -----BEGIN CERTIFICATE-----
 sdlfkjskldfj