https://github.com/charliehess/crash-safe-write-file

Writes a file atomically, plus fsync to flush contents
https://github.com/charliehess/crash-safe-write-file

Last synced: 17 days ago
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Writes a file atomically, plus fsync to flush contents

• Host: GitHub
• URL: https://github.com/charliehess/crash-safe-write-file
• Owner: CharlieHess
• License: mit
• Created: 2017-01-13T20:59:00.000Z (almost 8 years ago)
• Default Branch: master
• Last Pushed: 2017-01-19T21:09:52.000Z (almost 8 years ago)
• Last Synced: 2024-11-30T00:06:14.894Z (about 1 month ago)
• Language: JavaScript
• Size: 5.86 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# crash-safe-write-file

Write a file atomically and use fsync to flush its contents.

Node.js file operations, even `writeFileSync`, cannot guarantee that the contents of the file were written.

From http://www.daveeddy.com/2013/03/26/synchronous-file-io-in-nodejs/:

>`fs.writeFileSync` is synchronous in the sense that it blocks the event loop while it executes. It does NOT ask the Kernel to do a synchronous write to the underlying file system.

This is fine for most cases, but if you're trying to write a file that's immune to crashes, you need to get into the [`fsync`](http://blog.httrack.com/blog/2013/11/15/everything-you-always-wanted-to-know-about-fsync/) game. This library borrows graciously from the storage methods in [`nedb`](https://github.com/louischatriot/nedb).

## Install

```

npm install crash-safe-write-file --save

```

## Usage

``` js

const writeFile = require('crash-safe-write-file').writeFile;

writeFile(filename, data, callback);

```

``` js

import {writeFile} from 'crash-safe-write-file';

writeFile(filename, data, callback);

```

## Signature

``` js

/**

 * Fully write or rewrite the datafile, immune to crashes during the write

 * operation. Writes to a temporary file like `write-file-atomic`, but flushes

 * all buffers using fsync.

 *

 * Adapted from https://github.com/louischatriot/nedb/blob/master/lib/storage.js.

 *

 * @param {String} filename   The destination file

 * @param {String} data       The data to write

 * @param {Function} callback Optional callback on completion or error

 */

function writeFile(filename, data, callback);

```