perform the initial poll for devices quicker (#11356)
* perform the initial poll for devices quicker
* add a Poller class
* test the new Poller class
diff --git a/packages/flutter_tools/lib/src/base/utils.dart b/packages/flutter_tools/lib/src/base/utils.dart
index 31ee099..fddf40c 100644
--- a/packages/flutter_tools/lib/src/base/utils.dart
+++ b/packages/flutter_tools/lib/src/base/utils.dart
@@ -10,6 +10,7 @@
import 'package:intl/intl.dart';
import 'package:quiver/time.dart';
+import '../globals.dart';
import 'context.dart';
import 'file_system.dart';
import 'platform.dart';
@@ -216,3 +217,42 @@
}
Clock get clock => context.putIfAbsent(Clock, () => const Clock());
+
+typedef Future<Null> AsyncCallback();
+
+/// A [Timer] inspired class that:
+/// - has a different initial value for the first callback delay
+/// - waits for a callback to be complete before it starts the next timer
+class Poller {
+ Poller(this.callback, this.pollingInterval, { this.initialDelay: Duration.ZERO }) {
+ new Future<Null>.delayed(initialDelay, _handleCallback);
+ }
+
+ final AsyncCallback callback;
+ final Duration initialDelay;
+ final Duration pollingInterval;
+
+ bool _cancelled = false;
+ Timer _timer;
+
+ Future<Null> _handleCallback() async {
+ if (_cancelled)
+ return;
+
+ try {
+ await callback();
+ } catch (error) {
+ printTrace('Error from poller: $error');
+ }
+
+ if (!_cancelled)
+ _timer = new Timer(pollingInterval, _handleCallback);
+ }
+
+ /// Cancels the poller.
+ void cancel() {
+ _cancelled = true;
+ _timer?.cancel();
+ _timer = null;
+ }
+}
