Mpsc class

MPSC (Multiple-Producer Single-Consumer) channels - The workhorse of concurrent systems.

The most versatile channel type for fan-in patterns where multiple producers send data to a single consumer. Combines thread-safety for concurrent producers with single-consumer optimizations for maximum throughput.

Core Strengths

Thread-safe producers: Multiple threads can send concurrently
Single-consumer optimization: No consumer-side coordination overhead
Rich buffering strategies: Unbounded, bounded, rendezvous, latest-only
Advanced drop policies: Handle backpressure with oldest/newest dropping
Producer cloning: Create multiple sender handles from one channel
Flexible capacity: From 0 (rendezvous) to unlimited (unbounded)

When to Use MPSC

Event aggregation: Multiple event sources ↔ single event loop
Task queues: Multiple workers ↔ single dispatcher
Logging systems: Multiple threads ↔ single log writer
UI updates: Multiple components ↔ single UI thread
Data collection: Multiple sensors ↔ single processor
Request handling: Multiple clients ↔ single server

Performance Characteristics

Good throughput: ~535-950ns per operation
Latest-only mode: Extremely fast ~7ns per operation for coalescing buffers
Memory efficient: Chunked buffers available for unbounded channels
Scalable: Designed to handle multiple concurrent producers
Efficient design: Optimized for producer-consumer scenarios

Example

import 'package:cross_channel/mpsc.dart';

Future<void> main() async {
  // 1. Create an MPSC channel for N:1 communication
  final (eventTx, eventRx) = Mpsc.unbounded<String>();

  // 2. Multiple Producers (we clone the sender)
  final userTx = eventTx.clone();
  final networkTx = eventTx.clone();

  // Send from different sources concurrently
  await userTx.send('User clicked button');
  await networkTx.send('Data downloaded');

  // Close when done
  userTx.close();
  networkTx.close();
  eventTx.close(); // Close base sender

  // 3. Single Event Loop (Consumer)
  await for (final event in eventRx.stream()) {
    print('Processed Event: $event');
  }
}

Core Strengths

When to Use MPSC

Performance Characteristics

Example

Constructors

Properties

Methods

Operators

Static Methods

mpsc library