add update() function to PriorityQueue

lib/riemann/dash/public/vendor/PriorityQueue.js

@@ -51,6 +51,35 @@ PriorityQueue.prototype = {
 		this._maitain();
 	},
 
+
+	/**
+	 * Update priority of something in the queue. Will silently add it if it
+	 * doesn't already exist.
+	 *
+	 * @param 	mixed 		value
+	 * @param 	integer		priority
+	 * @return 	void
+	 */
+	update: function(value, priority) {
+		known = false;
+		idx = 0;
+
+		this._queue.forEach(function() {
+			if (JSON.stringify(this._queue[idx].value) === JSON.stringify(value)) {
+				this._queue[idx].priority = priority;
+				known = true;
+				return;
+			}
+			idx++;
+		}, this);
+
+		if (!known) {
+			this._queue.push(new QueueItem(value, priority));
+		}
+		this._queue.sort(this.compare());
+		this._maitain();
+	},
+
 	/**
 	 * Removes the most important item and return its value. 
 	 *