From f136d8391fafccb666e99aa6c55015cec70bd9f4 Mon Sep 17 00:00:00 2001
From: kpango <kpango@vdaas.org>
Date: Wed, 6 Sep 2023 12:06:44 +0900
Subject: [PATCH] [WIP] add CopyBuffer to copy.go [WIP] add CopyBuffer to
 copy.go

Signed-off-by: kpango <kpango@vdaas.org>
---
 internal/io/copy.go            | 59 +++++++++++++++++++++++-----------
 internal/io/copy_bench_test.go | 20 ++++++++++++
 2 files changed, 60 insertions(+), 19 deletions(-)

diff --git a/internal/io/copy.go b/internal/io/copy.go
index e22dbdb030..7ea5e3278d 100644
--- a/internal/io/copy.go
+++ b/internal/io/copy.go
@@ -22,6 +22,7 @@ import (
 	"io"
 	"math"
 	"sync/atomic"
+	"syscall"
 
 	"github.com/vdaas/vald/internal/errors"
 	"github.com/vdaas/vald/internal/sync"
@@ -33,8 +34,13 @@ func Copy(dst io.Writer, src io.Reader) (written int64, err error) {
 	return cio.Copy(dst, src)
 }
 
+func CopyBuffer(dst io.Writer, src io.Reader, buf []byte) (written int64, err error) {
+	return cio.CopyBuffer(dst, src, buf)
+}
+
 type Copier interface {
 	Copy(dst io.Writer, src io.Reader) (written int64, err error)
+	CopyBuffer(dst io.Writer, src io.Reader, buf []byte) (written int64, err error)
 }
 
 type copier struct {
@@ -42,9 +48,7 @@ type copier struct {
 	pool    sync.Pool
 }
 
-const (
-	defaultBufferSize int = 64 * 1024
-)
+var defaultBufferSize int = 16 * syscall.Getpagesize()
 
 func NewCopier(size int) Copier {
 	c := new(copier)
@@ -62,6 +66,22 @@ func NewCopier(size int) Copier {
 }
 
 func (c *copier) Copy(dst io.Writer, src io.Reader) (written int64, err error) {
+	return c.copyBuffer(dst, src, nil)
+}
+
+func (c *copier) CopyBuffer(dst io.Writer, src io.Reader, buf []byte) (written int64, err error) {
+	if buf == nil {
+		return c.Copy(dst, src)
+	}
+	if buf != nil && len(buf) == 0 {
+		panic("empty buffer in CopyBuffer")
+	}
+	b := bytes.NewBuffer(buf)
+	defer b.Reset()
+	return c.copyBuffer(dst, src, b)
+}
+
+func (c *copier) copyBuffer(dst io.Writer, src io.Reader, buf *bytes.Buffer) (written int64, err error) {
 	if dst == nil || src == nil {
 		return 0, errors.New("empty source or destination")
 	}
@@ -81,24 +101,25 @@ func (c *copier) Copy(dst io.Writer, src io.Reader) (written int64, err error) {
 		limit int64 = math.MaxInt64
 		size  int64 = atomic.LoadInt64(&c.bufSize)
 		l     *io.LimitedReader
-		buf   *bytes.Buffer
 	)
-	if l, ok = src.(*io.LimitedReader); ok && l.N >= 1 && size > l.N {
-		limit = l.N
-		size = limit
-	}
-	buf, ok = c.pool.Get().(*bytes.Buffer)
-	if !ok || buf == nil {
-		buf = bytes.NewBuffer(make([]byte, size))
-	}
-	defer func() {
-		if atomic.LoadInt64(&c.bufSize) < size {
-			atomic.StoreInt64(&c.bufSize, size)
-			buf.Grow(int(size))
+	if buf == nil {
+		if l, ok = src.(*io.LimitedReader); ok && l.N >= 1 && size > l.N {
+			limit = l.N
+			size = limit
 		}
-		buf.Reset()
-		c.pool.Put(buf)
-	}()
+		buf, ok = c.pool.Get().(*bytes.Buffer)
+		if !ok || buf == nil {
+			buf = bytes.NewBuffer(make([]byte, size))
+		}
+		defer func() {
+			if atomic.LoadInt64(&c.bufSize) < size {
+				atomic.StoreInt64(&c.bufSize, size)
+				buf.Grow(int(size))
+			}
+			buf.Reset()
+			c.pool.Put(buf)
+		}()
+	}
 	if size > int64(buf.Cap()) {
 		size = int64(buf.Cap())
 	}
diff --git a/internal/io/copy_bench_test.go b/internal/io/copy_bench_test.go
index 3dd206e5f4..ad33d00c17 100644
--- a/internal/io/copy_bench_test.go
+++ b/internal/io/copy_bench_test.go
@@ -82,6 +82,15 @@ func BenchmarkValdIOCopy(b *testing.B) {
 	}
 }
 
+func BenchmarkValdIOCopyBuffer(b *testing.B) {
+	c := NewCopier(bufferLength)
+	for i := 0; i < b.N; i++ {
+		w := &writer{}
+		r := &reader{len: readerLength}
+		c.CopyBuffer(w, r, nil)
+	}
+}
+
 func BenchmarkStandardIOCopyParallel(b *testing.B) {
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
@@ -113,3 +122,14 @@ func BenchmarkValdIOCopyParallel(b *testing.B) {
 		}
 	})
 }
+
+func BenchmarkValdIOCopyBufferParallel(b *testing.B) {
+	c := NewCopier(bufferLength)
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			w := &writer{}
+			r := &reader{len: readerLength}
+			c.CopyBuffer(w, r, nil)
+		}
+	})
+}