added unit testing, and started implementing unit tests...phew

node_modules/async/internal/queue.js

@@ -0,0 +1,204 @@
+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+exports.default = queue;
+
+var _baseIndexOf = require('lodash/_baseIndexOf');
+
+var _baseIndexOf2 = _interopRequireDefault(_baseIndexOf);
+
+var _isArray = require('lodash/isArray');
+
+var _isArray2 = _interopRequireDefault(_isArray);
+
+var _noop = require('lodash/noop');
+
+var _noop2 = _interopRequireDefault(_noop);
+
+var _onlyOnce = require('./onlyOnce');
+
+var _onlyOnce2 = _interopRequireDefault(_onlyOnce);
+
+var _setImmediate = require('./setImmediate');
+
+var _setImmediate2 = _interopRequireDefault(_setImmediate);
+
+var _DoublyLinkedList = require('./DoublyLinkedList');
+
+var _DoublyLinkedList2 = _interopRequireDefault(_DoublyLinkedList);
+
+var _wrapAsync = require('./wrapAsync');
+
+var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+function queue(worker, concurrency, payload) {
+    if (concurrency == null) {
+        concurrency = 1;
+    } else if (concurrency === 0) {
+        throw new Error('Concurrency must not be zero');
+    }
+
+    var _worker = (0, _wrapAsync2.default)(worker);
+    var numRunning = 0;
+    var workersList = [];
+
+    var processingScheduled = false;
+    function _insert(data, insertAtFront, callback) {
+        if (callback != null && typeof callback !== 'function') {
+            throw new Error('task callback must be a function');
+        }
+        q.started = true;
+        if (!(0, _isArray2.default)(data)) {
+            data = [data];
+        }
+        if (data.length === 0 && q.idle()) {
+            // call drain immediately if there are no tasks
+            return (0, _setImmediate2.default)(function () {
+                q.drain();
+            });
+        }
+
+        for (var i = 0, l = data.length; i < l; i++) {
+            var item = {
+                data: data[i],
+                callback: callback || _noop2.default
+            };
+
+            if (insertAtFront) {
+                q._tasks.unshift(item);
+            } else {
+                q._tasks.push(item);
+            }
+        }
+
+        if (!processingScheduled) {
+            processingScheduled = true;
+            (0, _setImmediate2.default)(function () {
+                processingScheduled = false;
+                q.process();
+            });
+        }
+    }
+
+    function _next(tasks) {
+        return function (err) {
+            numRunning -= 1;
+
+            for (var i = 0, l = tasks.length; i < l; i++) {
+                var task = tasks[i];
+
+                var index = (0, _baseIndexOf2.default)(workersList, task, 0);
+                if (index === 0) {
+                    workersList.shift();
+                } else if (index > 0) {
+                    workersList.splice(index, 1);
+                }
+
+                task.callback.apply(task, arguments);
+
+                if (err != null) {
+                    q.error(err, task.data);
+                }
+            }
+
+            if (numRunning <= q.concurrency - q.buffer) {
+                q.unsaturated();
+            }
+
+            if (q.idle()) {
+                q.drain();
+            }
+            q.process();
+        };
+    }
+
+    var isProcessing = false;
+    var q = {
+        _tasks: new _DoublyLinkedList2.default(),
+        concurrency: concurrency,
+        payload: payload,
+        saturated: _noop2.default,
+        unsaturated: _noop2.default,
+        buffer: concurrency / 4,
+        empty: _noop2.default,
+        drain: _noop2.default,
+        error: _noop2.default,
+        started: false,
+        paused: false,
+        push: function (data, callback) {
+            _insert(data, false, callback);
+        },
+        kill: function () {
+            q.drain = _noop2.default;
+            q._tasks.empty();
+        },
+        unshift: function (data, callback) {
+            _insert(data, true, callback);
+        },
+        remove: function (testFn) {
+            q._tasks.remove(testFn);
+        },
+        process: function () {
+            // Avoid trying to start too many processing operations. This can occur
+            // when callbacks resolve synchronously (#1267).
+            if (isProcessing) {
+                return;
+            }
+            isProcessing = true;
+            while (!q.paused && numRunning < q.concurrency && q._tasks.length) {
+                var tasks = [],
+                    data = [];
+                var l = q._tasks.length;
+                if (q.payload) l = Math.min(l, q.payload);
+                for (var i = 0; i < l; i++) {
+                    var node = q._tasks.shift();
+                    tasks.push(node);
+                    workersList.push(node);
+                    data.push(node.data);
+                }
+
+                numRunning += 1;
+
+                if (q._tasks.length === 0) {
+                    q.empty();
+                }
+
+                if (numRunning === q.concurrency) {
+                    q.saturated();
+                }
+
+                var cb = (0, _onlyOnce2.default)(_next(tasks));
+                _worker(data, cb);
+            }
+            isProcessing = false;
+        },
+        length: function () {
+            return q._tasks.length;
+        },
+        running: function () {
+            return numRunning;
+        },
+        workersList: function () {
+            return workersList;
+        },
+        idle: function () {
+            return q._tasks.length + numRunning === 0;
+        },
+        pause: function () {
+            q.paused = true;
+        },
+        resume: function () {
+            if (q.paused === false) {
+                return;
+            }
+            q.paused = false;
+            (0, _setImmediate2.default)(q.process);
+        }
+    };
+    return q;
+}
+module.exports = exports['default'];