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A Flutter package give an easy way to create multiple long live isolates for computation, support try-catch block.

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lamnhan066/isolates_helper

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Isolates Helper

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  • Creates multiple long-lived isolates to compute multiple functions.

  • Supports Worker and WASM on the Web with an efficient generator using the @isolatesHelperWorker annotation.

  • This package is based on the power of isolate_manager but can be used to compute multiple 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();
  });
}

Future<double> addFuture(List<double> values) async {
  return values[0] + values[1];
}

int add(List<int> values) {
  return values[0] + values[1];
}

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();

Worker

You need to do a little bit more works then using normal Isolate but don't worry, the below steps will help you to do it easily.

  • Step 1: Add @isolatesHelperWorker annotation to the functions that you want to use for the Worker

    @isolatesHelperWorker
    Future<double> addFuture(List<double> values) async {
      return values[0] + values[1];
    }
    
    @isolatesHelperWorker
    int add(List<int> values) {
      return values[0] + values[1];
    }
  • Step 2: Run this command

    dart run isolates_helper:generate
  • Step 3: Add the worker to the IsolatesHelper

    final isolates = IsolatesHelper(
      concurrent: 3,
      worker: 'worker',
      isDebug: true,
    );
  • Step 4: Here is the way to execute a Worker function

    final result = await isolates(
      // Here is the normal function
      add, 
    
      // Here is the normal params
      [2, 3], 
    
      // Here is the name of the function that is mapped in the step 2
      workerFunction: 'add',
      
      // [Optional] the normal params will be used if this value is null
      workerParams: [2, 3], 
      );

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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A Flutter package give an easy way to create multiple long live isolates for computation, support try-catch block.

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