From ea73dc6f6fa236134d68544a93700a459358aee2 Mon Sep 17 00:00:00 2001
From: Alexander Morozov <lk4d4@docker.com>
Date: Thu, 13 Aug 2015 11:42:14 -0700
Subject: [PATCH 1/2] tar/storage: Benchmark for bufferFileGetPutter.Put

Signed-off-by: Alexander Morozov <lk4d4@docker.com>
---
 tar/storage/getter_test.go | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/tar/storage/getter_test.go b/tar/storage/getter_test.go
index 5a6fcc7..c06cff0 100644
--- a/tar/storage/getter_test.go
+++ b/tar/storage/getter_test.go
@@ -2,7 +2,9 @@ package storage
 
 import (
 	"bytes"
+	"fmt"
 	"io/ioutil"
+	"strings"
 	"testing"
 )
 
@@ -39,6 +41,7 @@ func TestGetter(t *testing.T) {
 		}
 	}
 }
+
 func TestPutter(t *testing.T) {
 	fp := NewDiscardFilePutter()
 	// map[filename]map[body]crc64sum
@@ -60,3 +63,22 @@ func TestPutter(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkPutter(b *testing.B) {
+	files := []string{
+		strings.Repeat("foo", 1000),
+		strings.Repeat("bar", 1000),
+		strings.Repeat("baz", 1000),
+		strings.Repeat("fooz", 1000),
+		strings.Repeat("vbatts", 1000),
+		strings.Repeat("systemd", 1000),
+	}
+	for i := 0; i < b.N; i++ {
+		fgp := NewBufferFileGetPutter()
+		for n, body := range files {
+			if _, _, err := fgp.Put(fmt.Sprintf("%d", n), bytes.NewBufferString(body)); err != nil {
+				b.Fatal(err)
+			}
+		}
+	}
+}

From 45399711c2466973d96d650eb2c9971fbf3816d7 Mon Sep 17 00:00:00 2001
From: Alexander Morozov <lk4d4@docker.com>
Date: Thu, 13 Aug 2015 11:42:43 -0700
Subject: [PATCH 2/2] tar/storage: Replace TeeReader with MultiWriter

It uses slightly less memory and more understandable.
Benchmar results:

benchmark             old ns/op     new ns/op     delta
BenchmarkPutter-4     57272         52375         -8.55%

benchmark             old allocs     new allocs     delta
BenchmarkPutter-4     21             19             -9.52%
benchmark             old bytes     new bytes     delta
BenchmarkPutter-4     19416         13336         -31.31%

Signed-off-by: Alexander Morozov <lk4d4@docker.com>
---
 tar/storage/getter.go | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tar/storage/getter.go b/tar/storage/getter.go
index 70fd378..ae11f8f 100644
--- a/tar/storage/getter.go
+++ b/tar/storage/getter.go
@@ -59,15 +59,15 @@ func (bfgp bufferFileGetPutter) Get(name string) (io.ReadCloser, error) {
 }
 
 func (bfgp *bufferFileGetPutter) Put(name string, r io.Reader) (int64, []byte, error) {
-	c := crc64.New(CRCTable)
-	tRdr := io.TeeReader(r, c)
-	b := bytes.NewBuffer([]byte{})
-	i, err := io.Copy(b, tRdr)
+	crc := crc64.New(CRCTable)
+	buf := bytes.NewBuffer(nil)
+	cw := io.MultiWriter(crc, buf)
+	i, err := io.Copy(cw, r)
 	if err != nil {
 		return 0, nil, err
 	}
-	bfgp.files[name] = b.Bytes()
-	return i, c.Sum(nil), nil
+	bfgp.files[name] = buf.Bytes()
+	return i, crc.Sum(nil), nil
 }
 
 type readCloserWrapper struct {