https://github.com/kessler/qool

Qool, a leveldb backed Queue
https://github.com/kessler/qool

database javascript leveldb node-js nodejs queue

Last synced: about 1 month ago
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Qool, a leveldb backed Queue

• Host: GitHub
• URL: https://github.com/kessler/qool
• Owner: kessler
• License: mit
• Archived: true
• Created: 2016-07-10T03:41:40.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2016-08-09T19:29:44.000Z (over 8 years ago)
• Last Synced: 2024-12-01T00:31:58.535Z (about 1 month ago)
• Topics: database, javascript, leveldb, node-js, nodejs, queue
• Language: JavaScript
• Homepage:
• Size: 50.8 KB
• Stars: 42
• Watchers: 4
• Forks: 0
• Open Issues: 1
• Metadata Files:
  • Readme: readme.md
  • License: LICENSE

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README

        
# qool

**a leveldb backed [Queue](https://en.wikipedia.org/wiki/Queue_(abstract_data_type))**

[![npm status](http://img.shields.io/npm/v/qool.svg?style=flat-square)](https://www.npmjs.org/package/qool) 

- durable

- strict FIFO ordering

- dequeus with timeouts (called lease())

- embeddable

## Example

### Simple

```javascript

const Qool = require('qool')

const level = require('level-bytewise')

const db = level('db')

const queue = Qool.create(db)

queue.enqueue('a')

queue.enqueue('b', (err) => {})

queue.dequeue()

queue.dequeue((err, value) => {})

```

##### notes

Enqueue and Dequeue are batched under the hood, so callbacks are invoked synchronously. This means that you can only include a last callback and forgo all the others for Enqueues and Dequeues that happen in the same tick

### Lease

```javascript

const Qool = require('qool')

const level = require('level-bytewise')

const db = level('db')

const queue = Qool.create(db, 1000 * 10)

queue.enqueue('a')

queue.enqueue('b', (err) => {})

queue.lease((err, leaseKey, value) => {

    // do something with the data

    // delete the item permanently from the queue

    queue.delete(leaseKey, (err) => {

    })

})

// TBD

// lease with a non default timeout

//queue.leaseWithTimeout(1000 * 2, (err, leaseKey, value) => {})

```

### Peek

```javascript

const Qool = require('qool')

const level = require('level-bytewise')

const db = level('db')

const queue = Qool.create(db)

queue.enqueue('a')

queue.enqueue('b', (err) => {})

queue.peek((err, value) => {

    // value === 'a'

})

queue.peekMany((err, results) => {

    // results === [{ key: ..., value: 'a' }, { key: ..., value: 'b' }]

})

```

Some ramblings on internal design are [here](./notes.md)

## license

### TODO

- enhance tests

- implement length property

- should we have a version of dequeue that "waits" if the queue is empty

- expiry for enqueued items

[MIT](http://opensource.org/licenses/MIT) © yaniv kessler