27 lines
934 B
Dart
27 lines
934 B
Dart
import 'dart:async';
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import 'dart:collection';
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import 'dart:ui';
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/// A simple Mutex implementation using a [Completer].
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class Mutex {
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final _completerQueue = Queue<Completer<void>>();
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/// Runs the given [run] function-block in a thread-safe/blocked zone. A convenient `unlock()`
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/// is provided, which can be called anywhere to signal re-entry.
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FutureOr<T> lockAndRun<T>({
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required FutureOr<T> Function(VoidCallback unlock) run,
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}) async {
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final completer = Completer<void>();
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_completerQueue.add(completer);
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if (_completerQueue.first != completer) {
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await _completerQueue.removeFirst().future;
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}
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final value = await run(completer.complete);
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return value;
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}
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/// Allows listening to the completion status of the last worker process to be released.
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Future<void> get lastOperationCompletionAwaiter =>
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_completerQueue.isNotEmpty ? _completerQueue.last.future : Future.value();
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}
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