semaphore 0.1.1

semaphore #

Semaphore is lightweight data type that is used for controlling the cooperative access to a common resource inside the isolate.

Version: 0.1.1

Example: #

import 'dart:async';

import 'package:semaphore/semaphore.dart';

Future<void> main() async {
  var maxCount = 3;
  var running = <int>[];
  var simultaneous = 0;
  var sm = new LocalSemaphore(maxCount);
  var tasks = <Future>[];
  for (var i = 0; i < 9; i++) {
    tasks.add(new Future(() async {
      try {
        await sm.acquire();
        running.add(i);
        if (simultaneous < running.length) {
          simultaneous = running.length;
        }

        print("Start $i, running $running");
        await _doWork(100);
        running.remove(i);
        print("End   $i, running $running");
      } finally {
        sm.release();
      }
    }));
  }

  await Future.wait(tasks);
  print("Max permits: $maxCount, max simultaneous runned: $simultaneous");
}

Future _doWork(int ms) {
  // Simulate work
  return new Future.delayed(new Duration(milliseconds: ms));
}

Output:

Start 0, running [0]
Start 1, running [0, 1]
Start 2, running [0, 1, 2]
End   0, running [1, 2]
Start 3, running [1, 2, 3]
End   1, running [2, 3]
Start 4, running [2, 3, 4]
End   2, running [3, 4]
Start 5, running [3, 4, 5]
End   3, running [4, 5]
Start 6, running [4, 5, 6]
End   4, running [5, 6]
Start 7, running [5, 6, 7]
End   5, running [6, 7]
Start 8, running [6, 7, 8]
End   6, running [7, 8]
End   7, running [8]
End   8, running []
Max permits: 3, max simultaneous runned: 3

0.1.1 #

  • Performed the modifications according to "pub.dartlang.org" suggestions.

example/example.dart

import 'dart:async';

import 'package:semaphore/semaphore.dart';

Future<void> main() async {
  var maxCount = 3;
  var running = <int>[];
  var simultaneous = 0;
  var sm = new LocalSemaphore(maxCount);
  var tasks = <Future>[];
  for (var i = 0; i < 9; i++) {
    tasks.add(new Future(() async {
      try {
        await sm.acquire();
        running.add(i);
        if (simultaneous < running.length) {
          simultaneous = running.length;
        }

        print("Start $i, running $running");
        await _doWork(100);
        running.remove(i);
        print("End   $i, running $running");
      } finally {
        sm.release();
      }
    }));
  }

  await Future.wait(tasks);
  print("Max permits: $maxCount, max simultaneous runned: $simultaneous");
}

Future _doWork(int ms) {
  // Simulate work
  return new Future.delayed(new Duration(milliseconds: ms));
}

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:


dependencies:
  semaphore: ^0.1.1

2. Install it

You can install packages from the command line:

with pub:


$ pub get

with Flutter:


$ flutter pub get

Alternatively, your editor might support pub get or flutter pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:


import 'package:semaphore/semaphore.dart';
  
Popularity:
Describes how popular the package is relative to other packages. [more]
80
Health:
Code health derived from static analysis. [more]
95
Maintenance:
Reflects how tidy and up-to-date the package is. [more]
100
Overall:
Weighted score of the above. [more]
89
Learn more about scoring.

We analyzed this package on Jan 29, 2020, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.7.1
  • pana: 0.13.4

Health suggestions

Fix lib/src/semaphore/semaphore.dart. (-4.89 points)

Analysis of lib/src/semaphore/semaphore.dart reported 10 hints, including:

line 3 col 1: Prefer using /// for doc comments.

line 13 col 19: Unnecessary new keyword.

line 23 col 1: Prefer using /// for doc comments.

line 38 col 33: Unnecessary new keyword.

line 42 col 13: Unnecessary new keyword.

Dependencies

Package Constraint Resolved Available
Direct dependencies
Dart SDK >=2.0.0 <3.0.0
Dev dependencies
test ^1.5.3