Dynamic Parallel Queue

Features

Easy to use(so, no example file), Efficient, Pure

Getting started

import 'package:dynamic_parallel_queue/dynamic_parallel_queue.dart';

Usage

Serial queue

void main() async {
  // Now it's a serial queue, parallel default is 5
  final queue = Queue(parallel: 1);

  final List<int> res = [];

  // Add a async function, return Future
  final task1 = queue.add(() async {
    await Future.delayed(Duration(milliseconds: 30));
    res.add(1);
  });
  // You can wait it done.
  await task1;

  // add a list, return Future
  final tasks = queue.addAll([
        () async {
      await Future.delayed(Duration(milliseconds: 20));
      res.add(2);
    },
        () async {
      await Future.delayed(Duration(milliseconds: 10));
      res.add(3);
    },
  ]);

  /// You can wait for the tasks to complete
  /// But not need here
  // await tasks;


  /// Remove all pending tasks
  // queue.clear();

  /// Wait for the queue to complete
  await queue.whenComplete();
}

Although their wait times are different, buy they are executed in order.

Console output: [1, 2, 3]

Parallel Queue

void main() async {
  final queue = Queue();
  final List<int> res = [];

  queue.addAll([
        () async {
      await Future.delayed(Duration(milliseconds: 30));
      res.add(1);
    },
        () async {
      await Future.delayed(Duration(milliseconds: 20));
      res.add(2);
    },
        () async {
      await Future.delayed(Duration(milliseconds: 10));
      res.add(3);
    },
  ]);

  /// Wait for the queue to complete
  await queue.whenComplete();
  print(res); // [3, 2, 1]
}

Serial queue change to parallel queue

void main() async {
  final queue = Queue(parallel: 1);
  final List<int> res = [];
  final task1 = queue.add(() async {
    await Future.delayed(Duration(milliseconds: 50));

    /// You can change it at any time.
    queue.parallel = 5;

    res.add(1);
  });
  await task1;
  queue.addAll([
        () async {
      await Future.delayed(Duration(milliseconds: 30));
      res.add(2);
    },
        () async {
      await Future.delayed(Duration(milliseconds: 20));
      res.add(3);
    },
        () async {
      await Future.delayed(Duration(milliseconds: 10));
      res.add(4);
    },
  ]);
  await queue.whenComplete();
  print(res); // [1, 4, 3, 2]
}

About priority(default priority is 1)

The fewer value is mean the higher priority.

void main() async {
  final queue = Queue(parallel: 2);
  final List<int> res = [];
  queue.addAll([
        () async => res.add(1),
        () async => res.add(2),
  ], priority: 10); // Because the queue is empty, so it's running as soon as it's added
  queue.add(() async => res.add(3), priority: 3);
  queue.add(() async => res.add(4), priority: 2);
  queue.add(() async => res.add(0), priority: -1); // Support negative number
  await queue.whenComplete();
  print(res); // [1, 2, 0, 4, 3]
}

Libraries

dynamic_parallel_queue