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80 lines
1.9 KiB
80 lines
1.9 KiB
4 years ago
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# steno [](https://www.npmjs.org/package/steno) [](https://travis-ci.org/typicode/steno)
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> Simple file writer with __atomic writing__ and __race condition prevention__.
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Can be used as a drop-in replacement to `fs.writeFile()`.
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Built on [graceful-fs](https://github.com/isaacs/node-graceful-fs) and used in [lowdb](https://github.com/typicode/lowdb).
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## Install
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```
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npm install steno --save
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```
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## Usage
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```javascript
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const steno = require('steno')
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steno.writeFile('file.json', data, err => {
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if (err) throw err
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})
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```
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## The problem it solves
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### Without steno
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Let's say you have a server and want to save data to disk:
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```javascript
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var data = { counter: 0 }
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server.post('/', (req, res) => {
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// Increment counter
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++data.counter
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// Save data asynchronously
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fs.writeFile('data.json', JSON.stringify(data), err => {
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if (err) throw err
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res.end()
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})
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})
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```
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Now if you have many requests, for example `1000`, there's a risk that you end up with:
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```javascript
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// In your server
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data.counter === 1000
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// In data.json
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data.counter === 865 // ... or any other value
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```
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Why? Because, `fs.write` doesn't guarantee that the call order will be kept. Also, if the server is killed while `data.json` is being written, the file can get corrupted.
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### With steno
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```javascript
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server.post('/increment', (req, res) => {
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++data.counter
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steno.writeFile('data.json', JSON.stringify(data), err => {
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if (err) throw err
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res.end()
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})
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})
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```
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With steno you'll always have the same data in your server and file. And in case of a crash, file integrity will be preserved.
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if needed, you can also use `steno.writeFileSync()` which offers atomic writing too.
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__Important: works only in a single instance of Node.__
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## License
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MIT - [Typicode](https://github.com/typicode)
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