atomicfile

package module
Version: v0.0.0-...-2c406a5 Latest Latest
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Published: Aug 18, 2021 License: BSD-2-Clause Imports: 6 Imported by: 1

README

atomicfile

A Go library to help create files atomically.

The file is created only if all writes succeeded.

To learn how to use it:

Documentation

Overview

To write to files in a robust way we should:

- handle error returned by `Close()`

- handle error returned by `Write()`

- remove partially written file if `Write()` or `Close()` returned an error

This logic is non-trivial.

Package atomicfile makes it easy to get this logic right:

func writeToFileAtomically(filePath string, data []byte) error {
	w, err := atomicfile.New(filePath)
	if err != nil {
		return err
	}
	// calling Close() twice is a no-op
	defer w.Close()

	_, err = w.Write(data)
	if err != nil {
		return err
	}
	return w.Close()
}

To learn more see https://presstige.io/p/atomicfile-22143bf788b542fda2262ca7aee57ae4

Index

Constants

This section is empty.

Variables

View Source
var (
	// ErrCancelled is returned by calls subsequent to Cancel()
	ErrCancelled = errors.New("cancelled")
)

Functions

This section is empty.

Types

type File

type File struct {
	// contains filtered or unexported fields
}

File allows writing to a file atomically i.e. if the while file is not written successfully, we make sure to clean things up

func New

func New(path string) (*File, error)

New creates new File

func (*File) Close

func (f *File) Close() error

Close closes the file. Can be called multiple times to make it easier to use via defer

func (*File) RemoveIfNotClosed

func (f *File) RemoveIfNotClosed()

RemoveIfNotClosed removes the temp file if we didn't Close the file yet. Destination file will not be created. Use it with defer to ensure cleanup in case of a panic on the same goroutine that happens before Close. RemoveIfNotClosed after Close is a no-op.

func (*File) Seek

func (f *File) Seek(offset int64, whence int) (ret int64, err error)

func (*File) SetWriteDeadline

func (f *File) SetWriteDeadline(t time.Time) error

func (*File) Sync

func (f *File) Sync() error

func (*File) Truncate

func (f *File) Truncate(size int64) error

func (*File) Write

func (f *File) Write(d []byte) (int, error)

Write writes data to a file

func (*File) WriteAt

func (f *File) WriteAt(b []byte, off int64) (n int, err error)

func (*File) WriteString

func (f *File) WriteString(s string) (n int, err error)

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