reduce calls to offlinestorage while uploading attachments using debounce

packages/stream_chat/lib/src/debounce.dart

@@ -0,0 +1,23 @@
+import 'dart:async';
+
+import 'package:meta/meta.dart';
+
+/// Map of timeouts being debounced
+Map timeouts = {};
+
+/// Runs a function avoiding calling it too many times in a [timeoutMS] window
+void debounce({
+  @required Duration timeout,
+  @required Function target,
+  @required List arguments,
+}) {
+  if (timeouts.containsKey(target)) {
+    timeouts[target].cancel();
+  }
+
+  final timer = Timer(timeout, () {
+    Function.apply(target, arguments);
+  });
+
+  timeouts[target] = timer;
+}