promise-dequeue   

This is fork of promise-queue, promise-based queue. Main difference from original project is that Javascript array replaced by double-ended queue. It increases perfomance on highload queues, test

Installation

promise-dequeue can be installed using npm:

``
npm install promise-dequeue
`

Interface

- new Queue(Number maxConcurrent, Number maxQueued): Queue
- Queue#add(Function generator): Promise - adds function argument that generates a promise to the queue
- Queue#getQueueLength(): Number - returns current length of buffer(added but not started promise generators) it <= maxQueued
- Queue#getPendingLength(): Number - returns number of pending(concurrently running) promises it <= maxConcurrent

Example

$3

By default Queue tries to use global Promises, but you can specify your own promises.

`js
Queue.configure(require('vow').Promise);
`

Or use old-style promises approach:

`js
Queue.configure(function (handler) {
var dfd = $.Deferred();
try {
handler(dfd.resolve, dfd.reject, dfd.notify);
} catch (e) {
dfd.reject(e);
}
return dfd.promise();
});
`

$3

`js
var maxConcurrent = 1;
var maxQueue = Infinity;
var queue = new Queue(maxConcurrent, maxQueue);

app.get('/version/:user/:repo', function (req, res, next) {
queue.add(function () {
// Assume that this action is a way too expensive
// Call of this function will be delayed on second request
return downloadTarballFromGithub(req.params);
})
.then(parseJson('package.json'))
.then(function (package) {
res.send(package.version);
})
.catch(next);
});
`

$3

`js
var maxConcurrent = 1;
var maxQueue = 1;
var queue = new Queue(maxConcurrent, maxQueue);

queue.add(function () {
queue.getQueueLength() === 0;
queue.getPendingLength() === 1;
return somePromise();
});

queue.add(function () {
queue.getQueueLength() === 0;
queue.getPendingLength() === 0;
return somePromise();
});

queue.getQueueLength() === 1;
queue.getPendingLength() === 1;
``

Live example