Description:

cancellation token hoc081098

cancellation_token_hoc081098 #
Author: Petrus Nguyễn Thái Học #







Dart Cancellation Token.
Inspired by CancellationToken in C#.
A Dart utility package for easy async task cancellation.
Features #

✅ Reuse a single CancellationToken for multiple tasks, and cancel all of them with a single call to CancellationToken.cancel().
✅ Cancel futures and clean-up resources with token.guardFuture(block).
✅ Cancel streams and clean-up resources with token.guardStream(stream)/Stream.guardedBy(token).
✅ Integrate with rxdart/rxdart_ext with useCancellationToken.
✅ Very simple, lightweight, performant, and easy to use.

Getting started #
1. Add dependency #
dependencies:
cancellation_token_hoc081098: <latest_version>
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2. Import #
import 'package:cancellation_token_hoc081098/cancellation_token_hoc081098.dart';
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Usage #
1. guardFuture #
void main() async {
// Create a CancellationToken
final token = CancellationToken();

// Simulate a long-running task
Future<void> doWork(int number) async {
print('doWork($number) started');
await Future<void>.delayed(const Duration(milliseconds: 100));
print('doWork($number) finished');
}

// Guard a Future
final future = token.guardFuture(() async {
for (var i = 0; i < 10; i++) {
token.guard(); // Throws if token is cancelled
await doWork(i);
token.guard(); // Throws if token is cancelled
}
return 42;
});

future
.then((v) => print('Result: $v'))
.onError<Object>((e, st) => print('Error: $e'));

// Cancel the token after 300ms
await Future<void>.delayed(const Duration(milliseconds: 300));

// Cancel the token
token.cancel();

// Wait a little longer to ensure that the Future is cancelled
await Future<void>.delayed(const Duration(seconds: 2));

// Output:
// doWork(0) started
// doWork(0) finished
// doWork(1) started
// doWork(1) finished
// doWork(2) started
// Error: CancellationException
// doWork(2) finished
}
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2. guardStream #
void main() async {
// Create a CancellationToken
final token = CancellationToken();

// Simulate a long-running task
Future<void> doWork(int number) async {
print('doWork($number) started');
await Future<void>.delayed(const Duration(milliseconds: 100));
print('doWork($number) finished');
}

// Guard a Stream
final stream = Rx.fromCallable(() async {
for (var i = 0; i < 10; i++) {
token.guard(); // Throws if token is cancelled
await doWork(i);
token.guard(); // Throws if token is cancelled
}
return 42;
}).guardedBy(token);

stream
.doOnData((v) => print('Result: $v'))
.doOnError((e, st) => print('Error: $e'))
.listen(null);

// Cancel the token after 300ms
await Future<void>.delayed(const Duration(milliseconds: 300));

// Cancel the token
token.cancel();

// Wait a little longer to ensure that the stream is cancelled
await Future<void>.delayed(const Duration(seconds: 2));

// Output:
// doWork(0) started
// doWork(0) finished
// doWork(1) started
// doWork(1) finished
// doWork(2) started
// Error: CancellationException
// doWork(2) finished
}
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3. useCancellationToken #
import 'package:rxdart_ext/rxdart_ext.dart';

void main() async {
// Simulate a long-running task
Future<void> doWork(int number) async {
print('doWork($number) started');
await Future<void>.delayed(const Duration(milliseconds: 100));
print('doWork($number) finished');
}

// useCancellationToken
final Single<int> single = useCancellationToken((cancelToken) async {
for (var i = 0; i < 10; i++) {
cancelToken.guard(); // Throws if token is cancelled
await doWork(i);
cancelToken.guard(); // Throws if token is cancelled
}
return 42;
});

final subscription = single
.doOnData((v) => print('Result: $v'))
.doOnError((e, st) => print('Error: $e'))
.listen(null);

// Cancel the subscription after 300ms
await Future<void>.delayed(const Duration(milliseconds: 300));

// Cancel the subscription
await subscription.cancel();

// Wait a little longer to ensure that the stream is cancelled
await Future<void>.delayed(const Duration(seconds: 2));

// Output:
// doWork(0) started
// doWork(0) finished
// doWork(1) started
// doWork(1) finished
// doWork(2) started
// doWork(2) finished
}
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Features and bugs #
Please file feature requests and bugs at the issue tracker.
License #
MIT License

Copyright (c) 2022 Petrus Nguyễn Thái Học
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License

For personal and professional use. You cannot resell or redistribute these repositories in their original state.

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