consumer-queue

 

This module implements a simple unbounded producer-consumer queue (similar to a BlockingQueue in Java).
Multiple asynchronous tasks can push data, and one task can pull data from the queue and process it.

Installation

``
npm install consumer-queue
`

Usage

On the consumer side:

`javascript
const ConsumerQueue = require('consumer-queue');
const queue = new ConsumerQueue();
function loop() {
return queue.pop().then((value) => {
// ... do something with value ...
return loop();
});
}
`

On the producer side:
`javascript
// ... produce value ...
queue.push(value);
// ... produce second value ...
queue.push(value);
`

API

$3

#### constructor

`javascript
constructor()
`

Construct a new empty queue.

#### method push

`javascript
function push(value : any)
`

Push a new value at the end of the queue

#### method hasWaiter

`javascript
function hasWaiter() : bool
`

Returns true if a consumer is currently waiting for the next value, false otherwise.

#### method cancelWait

`javascript
function cancelWait(err : Error?)
`

If a consumer is currently waiting on the queue, causes the consumer to stop waiting.
The consumer promise will be rejected with err, if given, or a generic error otherwise.

#### method pop

`javascript
function pop() : Promise
`

Asynchronously returns the next value in queue. This method returns a promise that will
be fulfilled immediately if the queue already contains a value, and will be fulfilled
when the producer calls push() otherwise.

#### method tryPop

`javascript
function tryPop() : any?
`

Synchronously checks for the presence of a value in queue, and pops it if so.
This method returns null` if the queue is empty.