Broadcast<T> class final

Broadcast (Single-Producer Multi-Consumer) Ring Channel

Features:

• Pub/Sub: All subscribers see all messages (subject to capacity).
• Ring Buffer: Fixed capacity power-of-two buffer. Oldest messages are overwritten.
• Lag Detection: Slow subscribers detect gaps and can skip lost data.
• Replay: New subscribers can "replay" history by starting from the tail.

Best suited for:

• High-frequency local event buses (UI events, telemetry).
• Scenarios where slow consumers should not block the producer.

Example

import 'dart:async';

import 'package:cross_channel/broadcast.dart';

Future<void> main() async {
  // 1. Create a Broadcast (SPMC) ring channel
  final (tx, broadcast) = Broadcast.channel<String>(1024);

  // 2. Create multiple subscribers
  final sub1 = broadcast.subscribe();
  final sub2 = broadcast.subscribe();

  // 3. Publisher
  unawaited(Future.microtask(() async {
    await tx.send('System Update Available');
    await tx.send('Battery Low');
    tx.close();
  }));

  // 4. Consumers receive the SAME messages concurrently
  unawaited(Future.microtask(() async {
    await for (final msg in sub1.stream()) {
      print('UI Component 1 received: $msg');
    }
  }));

  unawaited(Future.microtask(() async {
    await for (final msg in sub2.stream()) {
      print('UI Component 2 received: $msg');
    }
  }));
}

Properties

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

subscribe({int replay = 0}) → BroadcastReceiver<T>

Creates a new subscriber.

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

channel<T>(int capacity, {String? metricsId}) → BroadcastChannel<T>

Creates a Broadcast channel with a fixed capacity (must be power-of-two).