Dart: Asynchronous

Dart makes asynchronous programming easy and intuitive with features like Futures, Streams and Isolates. Let's learn how to write asynchronous code in Dart.

Futures

Futures represent the result of an asynchronous operation. They allow you to run code asynchronously and handle the result later when it completes.

A Future is created using async/await or the future() constructor.

Future<int> fetchData() async {
  // Asynchronous operation 
  int data = await ...;  
  return data; 
}

void main() {
  var future = fetchData();
}

You can then use future.then() to handle the result when it completes:

future.then((data) {
  // Use data
});

This allows your main thread to continue executing while the asynchronous operation completes in the background.

You can also use await to wait for a Future to complete:

int data = await future;

Streams

Streams represent a series of events over time. They are useful for representing things like user input, server events etc.

You create a Stream using a StreamController and listen to it using a StreamSubscription:

StreamController<int> controller = StreamController();

StreamSubscription subscription = controller.stream.listen((data) {
  // Handle data
});

You can then add data to the stream using add() on the controller:

controller.add(1); 
controller.add(2);

The listener will be notified each time data is added.

Isolates

Isolates are separate execution threads that can run truly in parallel. They allow you to run CPU intensive tasks in the background.

You spawn an Isolate using spawn() and pass it a top-level function:

var isolate = await Isolate.spawn(computation);

You can then send messages to the Isolate using SendPort and receive them using ReceivePort.

Isolates allow you to achieve true parallelism and scale your Dart applications.

Use-Cases

Here are some use-cases for asynchronous programming in Dart along with their advantages and disadvantages:

Network Requests:

Advantage: User interface remains responsive while network requests are processed in background.
Disadvantage: Code can become complex to manage multiple asynchronous tasks.

File I/O:

Advantage: Other tasks can run while file I/O is in progress.
Disadvantage: More resources required to manage asynchronous tasks.

Database Operations:

Advantage: Queries can run in background without blocking the main thread.
Disadvantage: Debugging asynchronous code can be difficult.

CPU Intensive Tasks:

Advantage: Isolates can provide significant performance gains for CPU intensive tasks.
Disadvantage: Isolates require more memory to run in separate VM instances.

Event Handling:

Advantage: Asynchronous event handlers can be registered easily using Streams.
Disadvantage: Streams require managing stream controllers and subscriptions.

Animation:

Advantage: Animations can run smoothly while other tasks execute.
Disadvantage: Asynchronous code can become complex with many Futures and Streams.

In summary, while asynchronous programming provides advantages like responsiveness, scalability and better resource utilization, it also has some disadvantages like increased complexity, memory usage and difficulty debugging. The biggest advantage is providing a responsive user interface by offloading long running tasks to background threads.

The key is to use asynchronous programming judiciously where it provides significant benefits. Dart's asynchronous features like Futures, Streams and Isolates make it easy to write asynchronous code while managing its complexity.

Disclaim: I have ask the questions to Rix (AI bot). I have not verified the examples and I have no experience using Dart. If you have some experience and advice, comment below.

Dart: Asynchronous