pad.js: fix freeze on pad deletion when it has many revisions

src/node/utils/promises.js

@@ -0,0 +1,32 @@
+/**
+ * Helpers to manipulate promises (like async but for promises).
+ */
+
+var timesLimit = function (ltMax, concurrency, promiseCreator) {
+  var done = 0
+  var current = 0
+
+  function addAnother () {
+    function _internalRun () {
+      done++
+
+      if (done < ltMax) {
+        addAnother()
+      }
+    }
+
+    promiseCreator(current)
+      .then(_internalRun)
+      .catch(_internalRun)
+
+    current++
+  }
+
+  for (var i = 0; i < concurrency && i < ltMax; i++) {
+    addAnother()
+  }
+}
+
+module.exports = {
+  timesLimit: timesLimit
+}