isolates_helper 0.3.0

An easy way to create multiple long live isolates for computation, support try-catch block.

Isolates Helper

• An easy way to create multiple long live isolates for computation.

• This package is based on the power of isolate_manager (which is also written by me) but can be used with mutiple functions.

• Support try-catch block.

Usage

Define the number of isolates you want to live with concurrent parameter.

void main() async {
  // Create 3 isolates to solve the problems
  final isolates = IsolatesHelper(concurrent: 3);

  // Listen for the results from the stream.
  isolates.stream.listen((result) {
    if (result is double) {
      print('Stream get addFuture: $result');
    } else {
      print('Stream get add: $result');
    }
  });

  // Compute the values. The return type and parameter type will respect the type
  // of the function.
  final added = await isolates.compute(addFuture, [1.1, 2.2]);
  print('add: 1.1 + 2.2 = $added');

  // Multiple computations at the same time are allowed. It will be queued
  // automatically.
  for (int i = 0; i < 10; i++) {
    isolates(add, [i, i]).then((value) async {
      print('add: $i + $i = $value');
    });
  }

  // Stop the IsolateHelper instance after 5 seconds
  Timer(Duration(seconds: 5), () {
    isolates.stop();
  });
}

@pragma('vm:entry-point')
Future<double> addFuture(List<double> values) async {
  return values[0] + values[1];
}

@pragma('vm:entry-point')
int add(List<int> values) {
  return values[0] + values[1];
}

Use @pragma('vm:entry-point') notation to avoid the function being trimmed when building in release mode.

Here is the ways to use try-catch block:

// Catch the error from the stream
isolates.stream.listen((result) {
  print('Stream get add: $result');
}).onError((e) {
  print('Error from stream: $e');
});

// Catch the error from the try-catch block
try {
  await isolates.compute(addException, [1, 1]);
} catch (e) {
  print('Error from try-catch: $e');
}

The first compute will automatically wait for all isolates to started before doing the computation, if you want to wait for it manually, you can use:

await isolates.ensureStarted;

Or you can check if the current isolates are started or still in processing by using:

bool isStarted = isolates.isStarted;

You can restart all the isolates with:

await isolates.restart();

Remember to stop the isolates when you don't need it:

await isolates.stop();

Additional

• This package also provides the way to implement Worker for Web platform. To keeps this package simple to use, you can read here for more details when you need it.

Contributions

If you encounter any problems or feel the library is missing a feature, feel free to open an issue. Pull requests are also welcome.

Donations

If you like my work or the free stuff on this channel and want to say thanks, or encourage me to do more, you can buy me a coffee. Thank you so much!

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