Dart Streams: How to load balacing? - dart

Question

Is it possible to make a stream in Dart to load balance its emited datas?
Example:
I have one Stream and 3 listeners (A), (B) and (C):
Emits 0, (A) receives but not (B) and (C)
Then it emits 1, (B) receives but not (A) and (C)
Then it emits 2, (C) receives but not (A) and (B)
How to acomplish it in Dart ?

Answer 1

This is just a draft solution but you can do something like this (and properly add some utility methods like e.g. removing streams when they are stopping listening):
import 'dart:async';
void main() {
final splitter = StreamSplitter(
Stream<int>.periodic(const Duration(seconds: 1), (i) => i));
splitter
.getLoadBalancedStream()
.forEach((element) => print('Called Stream 1 with: $element'));
splitter
.getLoadBalancedStream()
.forEach((element) => print('Called Stream 2 with: $element'));
splitter
.getLoadBalancedStream()
.forEach((element) => print('Called Stream 3 with: $element'));
// Called Stream 1 with: 0
// Called Stream 2 with: 1
// Called Stream 3 with: 2
// Called Stream 1 with: 3
// Called Stream 2 with: 4
// Called Stream 3 with: 5
// Called Stream 1 with: 6
}
class StreamSplitter<T> {
List<StreamController<T>> streamControllers = [];
StreamSplitter(Stream<T> stream) {
final controller = _controllers().iterator;
stream.listen((event) => controller
..moveNext()
..current.add(event));
}
Stream<T> getLoadBalancedStream() {
final controller = StreamController<T>();
streamControllers.add(controller);
return controller.stream;
}
Iterable<StreamController<T>> _controllers() sync* {
// ignore: literal_only_boolean_expressions
while (true) {
for (var i = 0; i < streamControllers.length; i++) {
yield streamControllers[i];
}
}
}
}