util.js in riemann-dash-0.2.0

- old
+ new

@@ -1,6 +1,7 @@
 var util = (function() {
+  // Unique IDs
   var uniqueId = function(bytes) {
     bytes = bytes || 20;
     var s = '';
     for (var i = 0; i < bytes * 2; i++) {
       s += Math.floor(Math.random() * 16).toString(16);
@@ -11,11 +12,41 @@
   // Merge two maps nondestructively.
   var merge = function(m1, m2) {
     return _.extend(_.clone(m1), m2);
   }
 
+  // Wraps a function in another, which calls f at most once every period
+  // milliseconds. Tries to minimize latency.
+  var slur = function(period, f) {
+    var lastRun = new Date();
+    lastRun.setYear(0);
+    var queued = false;
+    var execute = function(context, args) {
+      f.apply(context, args);
+      lastRun = new Date();
+      queued = false;
+    };
+
+    return function() {
+      // If queued, do nothing
+      if (queued) {
+        return;
+      }
+
+      var dt = (new Date()) - lastRun;
+      if (period <= dt) {
+        // We're free to go
+        execute(this, arguments);
+      } else {
+        // Too soon, enqueue a new job.
+        window.setTimeout(execute, period - dt, this, arguments);
+      }
+    }
+  }
+
   return {
     merge: merge,
+    slur: slur,
     uniqueId: uniqueId
   }
 })();
 
 $(function() {