Background job processing in Hangfire is all about moving a background job from one state to another. States are used to clearly decide what to do with a background job. For example, EnqueuedState tells Hangfire that a job should be processed by a Worker, and FailedState tells Hangfire that a job should be investigated by a developer.

Each state have some essential properties like Name, IsFinal and a custom ones that are exposed through the SerializeData method. Serialized data may be used during the processing stage.

Hangfire allows you to define custom states to extend the processing pipeline. IStateHandler interface implementation can be used to define additional work for a state transition, and IBackgroundProcess interface implementation can be used to process background jobs in a new state. For example, delayed jobs and their ScheduledState, continuations and their AwaitingState can be simply moved to an extension package.

Let's create a new state. Consider you haves background jobs that throw a transient exception from time to time, and you want to simply ignore those exceptions. By default, Hangfire will move a job that throwed an exception to the FailedState, however a job in the failed state will live in a Failed jobs page forever, unless we use AutomaticRetryAttribute, delete or retry it manually, because the FailedState is not a final state.

Our new state will look like a FailedState, but we define the state as a final one, letting Hangfire to expire faulted jobs. Please refer to the IState interface properties to learn about their details.

In articles related to IStateHandler and IElectStateFilter interfaces we'll discuss how to use this new state.

public class FaultedState : IState
{
    public static readonly string StateName = "Faulted";

    public FaultedState(Exception exception)
    {
        Message = exception.Message;
        Details = exception.ToString();
    }

    public string Name => StateName;
    public string Reason { get; set; }

    public bool IsFinal => true;
    public bool IgnoreJobLoadException => true;

    // Here are our custom properties, we'll made them
    // accessible through the Dashboard UI.
    public string Message { get; }
    public string Details { get; }

    public Dictionary<string, string> SerializeData()
    {
        return new Dictionary<string, string>
        {
            { "Message", Message },
            { "Details", Details }
        };
    }
}

Reference