tidb local 代码
文件路径：/br/pkg/storage/local.go
/ Copyright 2020 PingCAP, Inc. Licensed under Apache-2.0.
package storage
import (
"bufio"
"context"
"os"
"path/filepath"
"strings"
"github.com/pingcap/errors"
)
const (
localDirPerm os.FileMode = 0o777
localFilePerm os.FileMode = 0o644
/ LocalURIPrefix represents the local storage prefix.
LocalURIPrefix = "file://"
)
/ LocalStorage represents local file system storage.
/
/ export for using in tests.
type LocalStorage struct {
base string
}
/ DeleteFile deletes the file.
func (l *LocalStorage) DeleteFile(_ context.Context, name string) error {
path := filepath.Join(l.base, name)
return os.Remove(path)
}
/ WriteFile writes data to a file to storage.
func (l *LocalStorage) WriteFile(_ context.Context, name string, data []byte) error {
/ because `os.WriteFile` is not atomic, directly write into it may reset the file
/ to an empty file if write is not finished.
tmpPath := filepath.Join(l.base, name) + ".tmp"
if err := os.WriteFile(tmpPath, data, localFilePerm); err != nil {
return errors.Trace(err)
}
if err := os.Rename(tmpPath, filepath.Join(l.base, name)); err != nil {
return errors.Trace(err)
}
return nil
}
/ ReadFile reads the file from the storage and returns the contents.
func (l *LocalStorage) ReadFile(_ context.Context, name string) ([]byte, error) {
path := filepath.Join(l.base, name)
return os.ReadFile(path)
}
/ FileExists implement ExternalStorage.FileExists.
func (l *LocalStorage) FileExists(_ context.Context, name string) (bool, error) {
path := filepath.Join(l.base, name)
return pathExists(path)
}
/ WalkDir traverse all the files in a dir.
/
/ fn is the function called for each regular file visited by WalkDir.
/ The first argument is the file path that can be used in `Open`
/ function; the second argument is the size in byte of the file determined
/ by path.
func (l *LocalStorage) WalkDir(_ context.Context, opt *WalkOption, fn func(string, int64) error) error {
if opt == nil {
opt = &WalkOption{}
}
base := filepath.Join(l.base, opt.SubDir)
return filepath.Walk(base, func(path string, f os.FileInfo, err error) error {
if os.IsNotExist(err) {
/ if path not exists, we should return nil to continue.
return nil
}
if err != nil {
return errors.Trace(err)
}
if f == nil || f.IsDir() {
return nil
}
/ in mac osx, the path parameter is absolute path; in linux, the path is relative path to execution base dir,
/ so use Rel to convert to relative path to l.base
path, _ = filepath.Rel(l.base, path)
if !strings.HasPrefix(path, opt.ObjPrefix) {
return nil
}
size := f.Size()
/ if not a regular file, we need to use os.stat to get the real file size
if !f.Mode().IsRegular() {
stat, err := os.Stat(filepath.Join(l.base, path))
if err != nil {
return errors.Trace(err)
}
size = stat.Size()
}
return fn(path, size)
})
}
/ URI returns the base path as an URI with a file:/// prefix.
func (l *LocalStorage) URI() string {
return LocalURIPrefix + "/" + l.base
}
/ Open a Reader by file path, path is a relative path to base path.
func (l *LocalStorage) Open(_ context.Context, path string) (ExternalFileReader, error) {
/nolint: gosec
return os.Open(filepath.Join(l.base, path))
}
/ Create implements ExternalStorage interface.
func (l *LocalStorage) Create(_ context.Context, name string) (ExternalFileWriter, error) {
file, err := os.Create(filepath.Join(l.base, name))
if err != nil {
return nil, errors.Trace(err)
}
buf := bufio.NewWriter(file)
return newFlushStorageWriter(buf, buf, file), nil
}
/ Rename implements ExternalStorage interface.
func (l *LocalStorage) Rename(_ context.Context, oldFileName, newFileName string) error {
return errors.Trace(os.Rename(filepath.Join(l.base, oldFileName), filepath.Join(l.base, newFileName)))
}
func pathExists(_path string) (bool, error) {
_, err := os.Stat(_path)
if err != nil {
if os.IsNotExist(err) {
return false, nil
}
return false, errors.Trace(err)
}
return true, nil
}
/ NewLocalStorage return a LocalStorage at directory `base`.
/
/ export for test.
func NewLocalStorage(base string) (*LocalStorage, error) {
ok, err := pathExists(base)
if err != nil {
return nil, errors.Trace(err)
}
if !ok {
err := mkdirAll(base)
if err != nil {
return nil, errors.Trace(err)
}
}
return &LocalStorage{base: base}, nil
}