iota9star · October 7, 2022 13:26 · Oct 7, 2022
diff --git a/mutex.dart b/mutex.dart
@@ -0,0 +1,40 @@
+import 'dart:async';
+
+class Mutex {
+  Completer<void>? _completer;
+
+  Future<void> lock() async {
+    while (_completer != null) {
+      await _completer!.future;
+    }
+    _completer = Completer<void>();
+  }
+
+  /// Notice: must be call [unlock] after [lock] method called to prevent the deadlock.
+  /// ```dart
+  /// final mutex = Mutex();
+  /// // ...
+  /// Future<void> doSth() async {
+  ///   try {
+  ///     await mutex.lock();
+  ///     // do something...
+  ///   } finally {
+  ///     mutex.unlock();
+  ///   }
+  /// }
+  /// ```
+  void unlock() {
+    final completer = _completer;
+    _completer = null;
+    completer?.complete();
+  }
+
+  Future<T> withLock<T>(FutureOr<T> Function() block) async {
+    try {
+      await lock();
+      return await block();
+    } finally {
+      unlock();
+    }
+  }
+}