Lifetime Management

A lifetime is made up of two parts, the Lifetime instance, which is passed around and used to register callbacks, and a LifetimeDefinition which is used to manage the lifetime.

LifetimeDefinition

You cannot terminate a Lifetime instance; unless you create it, you do not own it, therefore you shouldn't terminate it. Instead, when you create a Lifetime, you receive an instance of LifetimeDefinition, and this class allows you to terminate the Lifetime. Here's what it looks like:

public class LifetimeDefinition
{
  public void Terminate();
  public bool IsTerminated { get; }
  public Lifetime Lifetime { get; }
}

It is a very simple class. You can get the Lifetime instance it is associated with, and calling Terminate will terminate this instance. The IsTerminated property will return true if Terminate has been called.

When terminating, the callbacks registered to the Lifetime are called in reverse order of registration. That is, most recently registered first. All callbacks are called, even if one throws an exception - the exception is logged, and then ignored (favouring continuing cleanup over exception reporting).

Lifetime Creation

You can use the Lifetimes class to create your own Lifetime instances.

Short lived Lifetimes

If you only need a Lifetime for a short period of time, the Lifetimes.Using(Action<Lifetime> f) method will create a new instance, call your method and then immediately terminate the Lifetime. There is also an overload that takes in a Func<Lifetime, TRetval> to allow your method to return a value.

Nested Lifetimes

If you want a longer-lived Lifetime, you can call Lifetimes.Define:

Lifetimes.Define(Lifetime lifetime, string id, Action<LifetimeDefinition, Lifetime> action, ILogger logger);

This method takes in a Lifetime to act as a parent; the new Lifetime is a "nested" lifetime. Terminating the parent Lifetime will also terminate this new child Lifetime. Of course, if the child terminates first, it removes itself from the parent's cleanup.

The Define method has a number of optional parameters, firstly an id, which is only used for diagnostic purposes. Secondly, an action that is called as soon as the LifetimeDefinition has been created. And finally, an optional instance of ILogger. If no logger is passed in, the default logger instance from Logger.Interface is used (see the Logging section for more details on logging).

Last modified: 20 April 2023