perf: add file pool to reduce allocations

archiver.go

@@ -265,7 +265,7 @@ func (a *Archiver) archive(file *pool.File) error {
 		return errors.Errorf("ERROR: could not write raw header for %s", file.Path)
 	}
 
-	_, err = io.Copy(fileWriter, &file.CompressedData)
+	_, err = io.Copy(fileWriter, file.CompressedData)
 	if err != nil {
 		return errors.Errorf("ERROR: could not write content for %s", file.Path)
 	}
@@ -281,6 +281,8 @@ func (a *Archiver) archive(file *pool.File) error {
 		os.Remove(file.Overflow.Name())
 	}
 
+	pool.FilePool.Put(file)
+
 	return nil
 }
 

archiver_test.go

@@ -156,7 +156,7 @@ func TestCompress(t *testing.T) {
 		file, err := pool.NewFile(helloTxtFileFixture, info, "")
 		assert.NoError(t, err)
 		bufCap := 5
-		file.CompressedData = *bytes.NewBuffer(make([]byte, 0, bufCap))
+		file.CompressedData = bytes.NewBuffer(make([]byte, 0, bufCap))
 
 		err = archiver.compress(file)
 		assert.NoError(t, err)

pool/file.go

@@ -6,33 +6,51 @@ import (
 	"io/fs"
 	"os"
 	"path/filepath"
+	"sync"
 
 	"github.com/pkg/errors"
 )
 
-const defaultBufferSize = 2 * 1024 * 1024
+const DefaultBufferSize = 2 * 1024 * 1024
+
+var FilePool = sync.Pool{
+	New: func() any {
+		return &File{CompressedData: bytes.NewBuffer(make([]byte, DefaultBufferSize))}
+	},
+}
 
 type File struct {
 	Path           string
 	Info           fs.FileInfo
 	Header         *zip.FileHeader
-	CompressedData bytes.Buffer
+	CompressedData *bytes.Buffer
 	Overflow       *os.File
 	written        int64
 }
 
 func NewFile(path string, info fs.FileInfo, relativeTo string) (*File, error) {
+	f := FilePool.Get().(*File)
+	err := f.Reset(path, info, relativeTo)
+	return f, err
+}
+
+func (f *File) Reset(path string, info fs.FileInfo, relativeTo string) error {
 	hdr, err := zip.FileInfoHeader(info)
 	if err != nil {
-		return nil, errors.Errorf("ERROR: could not get file info header for %s: %v", path, err)
+		errors.Errorf("ERROR: could not get file info header for %s: %v", path, err)
 	}
+	f.Path = path
+	f.Info = info
+	f.Header = hdr
+	f.CompressedData.Reset()
+	f.Overflow = nil
+	f.written = 0
 
-	f := &File{Path: path, Info: info, Header: hdr, CompressedData: *bytes.NewBuffer(make([]byte, 0, defaultBufferSize))}
 	if relativeTo != "" {
 		f.setNameRelativeTo(relativeTo)
 	}
 
-	return f, nil
+	return nil
 }
 
 func (f *File) Write(p []byte) (n int, err error) {

pool/file_test.go

@@ -45,4 +45,22 @@ func TestNewFile(t *testing.T) {
 
 		assert.Equal(t, "hello/nested/hello.md", file.Header.Name)
 	})
+
+	t.Run("resets file as new", func(t *testing.T) {
+		filePath := filepath.Join(helloDirectoryFixture, "nested/hello.md")
+		info := testutils.GetFileInfo(t, filePath)
+
+		file, err := pool.NewFile(filePath, info, helloDirectoryFixture)
+		assert.NoError(t, err)
+
+		newInfo := testutils.GetFileInfo(t, helloTxtFileFixture)
+		err = file.Reset(helloTxtFileFixture, newInfo, "")
+		assert.NoError(t, err)
+
+		assert.Equal(t, helloTxtFileFixture, file.Path)
+		assert.Equal(t, newInfo, file.Info)
+		assert.Equal(t, "hello.txt", file.Header.Name)
+		assert.Equal(t, 0, file.CompressedData.Len())
+		assert.Equal(t, pool.DefaultBufferSize, file.CompressedData.Cap())
+	})
 }