FoundationalBits

Useful bits for foundational groundwork in C# applications.

Contents

• MessageBus for async dispatch of messages between components in the same process

  class Receiver : IHandle<string>{
    public void Handle(string message) =>
      Console.WriteLine(message);
  }
  
  ...
  
  var messageBus = MessageBus.Create()
  messageBus.Subscribe(
    new Receiver(),
    SubscriptionLifecycle.ExplicitUnsubscribe);
  
  ...
  
  await messageBus.Publish("Hello, World!");

• Stateful agent to handle shared mutable state without having to use explicit lock statements or other semaphores

  enum CounterCommand{
    Increment,
    Decrement,
    Current,
  }
  var counter = Agent.Start<CounterCommand,int,int>(
    0,
    (current,command) => command switch{
      CounterCommand.Increment => (current+1, current+1),
      CounterCommand.Decrement => (current-1, current-1),
      CounterCommand.Current => (current,current),
      _=>throw new ArgumentException("unknown command")
    }
  )
    
  ... 
  //thread/task 1
    
  await counter.Tell(CounterCommand.Increment);
    
  //thread/task 2
    
  await counter.Tell(CounterCommand.Decrement);
  
  ...
  //output: "0" regardless of context switches, as long as pervious two calls are started before
  Console.WriteLine(await counter.Tell(CounterCommand.Current));

• Stateless agent to ensure generalized sequential execution of actions triggered from different background tasks without explicit synchronization

Contributors

• Andreas Pfohl
• Dirk Peters