From 8e6566c701470f680e4012551a677ac57fc892a3 Mon Sep 17 00:00:00 2001
From: ykadowak <yusuke.kadowaki.1231@gmail.com>
Date: Thu, 30 Nov 2023 02:49:22 +0000
Subject: [PATCH] Revert "Add CopyBuffer to copy.go (#2167)"

This reverts commit ed6118a84d7c7ed6110d518e2ef114299ba8c430.
---
 internal/io/copy.go            | 59 +++++++++++-----------------------
 internal/io/copy_bench_test.go | 20 ------------
 2 files changed, 19 insertions(+), 60 deletions(-)

diff --git a/internal/io/copy.go b/internal/io/copy.go
index 7ea5e3278d..e22dbdb030 100644
--- a/internal/io/copy.go
+++ b/internal/io/copy.go
@@ -22,7 +22,6 @@ import (
 	"io"
 	"math"
 	"sync/atomic"
-	"syscall"
 
 	"github.com/vdaas/vald/internal/errors"
 	"github.com/vdaas/vald/internal/sync"
@@ -34,13 +33,8 @@ 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 {
@@ -48,7 +42,9 @@ type copier struct {
 	pool    sync.Pool
 }
 
-var defaultBufferSize int = 16 * syscall.Getpagesize()
+const (
+	defaultBufferSize int = 64 * 1024
+)
 
 func NewCopier(size int) Copier {
 	c := new(copier)
@@ -66,22 +62,6 @@ 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")
 	}
@@ -101,25 +81,24 @@ func (c *copier) copyBuffer(dst io.Writer, src io.Reader, buf *bytes.Buffer) (wr
 		limit int64 = math.MaxInt64
 		size  int64 = atomic.LoadInt64(&c.bufSize)
 		l     *io.LimitedReader
+		buf   *bytes.Buffer
 	)
-	if buf == nil {
-		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))
-			}
-			buf.Reset()
-			c.pool.Put(buf)
-		}()
+	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))
+		}
+		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 ad33d00c17..3dd206e5f4 100644
--- a/internal/io/copy_bench_test.go
+++ b/internal/io/copy_bench_test.go
@@ -82,15 +82,6 @@ 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() {
@@ -122,14 +113,3 @@ 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)
-		}
-	})
-}