flow like the river

BACK_BACK/node_modules/promise-queue/README.md

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+# promise-queue [![NPM Version](https://badge.fury.io/js/promise-queue.png)](https://npmjs.org/package/promise-queue) [![Build Status](https://travis-ci.org/azproduction/promise-queue.png?branch=master)](https://travis-ci.org/azproduction/promise-queue) [![Coverage Status](https://coveralls.io/repos/azproduction/promise-queue/badge.png?branch=master)](https://coveralls.io/r/azproduction/promise-queue) [![Dependency Status](https://gemnasium.com/azproduction/promise-queue.png)](https://gemnasium.com/azproduction/promise-queue)
+
+Promise-based queue
+
+## Installation
+
+`promise-queue` can be installed using `npm`:
+
+```
+npm install promise-queue
+```
+
+## 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
+
+### Configure queue
+
+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();
+});
+```
+
+### Queue one by one example
+
+```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);
+});
+```
+
+### Getting number of pending promises and queue(buffered promises) length
+
+```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](http://jsfiddle.net/RVuEU/1/)