实现open file cache

internal/caches/open_file.go

@@ -0,0 +1,31 @@
+// Copyright 2022 Liuxiangchao iwind.liu@gmail.com. All rights reserved.
+
+package caches
+
+import (
+	"io"
+	"os"
+)
+
+type OpenFile struct {
+	fp      *os.File
+	meta    []byte
+	version int64
+}
+
+func NewOpenFile(fp *os.File, meta []byte) *OpenFile {
+	return &OpenFile{
+		fp:   fp,
+		meta: meta,
+	}
+}
+
+func (this *OpenFile) SeekStart() error {
+	_, err := this.fp.Seek(0, io.SeekStart)
+	return err
+}
+
+func (this *OpenFile) Close() error {
+	this.meta = nil
+	return this.fp.Close()
+}