Question

Does anyone have any experience integrating autofac and Quartz.Net? If so, where is it best to control lifetime management — the IJobFactory, within the Execute of the IJob, or through event listeners?

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Right now, I’m using a custom autofac IJobFactory to create the IJob instances, but I don’t have an easy way to plug in to a ILifetimeScope in the IJobFactory to ensure any expensive resources that are injected in the IJob are cleaned up. The job factory just creates an instance of a job and returns it. Here are my current ideas (hopefully there are better ones…)

• It looks like most AutoFac integrations somehow wrap a ILifetimeScope around the unit of work they create. The obvious brute force way seems to be to pass an ILifetimeScope into the IJob and have the Execute method create a child ILifetimeScope and instantiate any dependencies there. This seems a little too close to a service locator pattern, which in turn seems to go against the spirit of autofac, but it might be the most obvious way to ensure proper handling of a scope.

• I could plug into some of the Quartz events to handle the different phases of the Job execution stack, and handle lifetime management there. That would probably be a lot more work, but possibly worth it if it gets cleaner separation of concerns.

• Ensure that an IJob is a simple wrapper around an IServiceComponent type, which would do all the work, and request it as Owned<T>, or Func<Owned<T>>. I like how this seems to vibe more with autofac, but I don’t like that its not strictly enforceable for all implementors of IJob.

Answer 1

Without knowing too much about Quartz.Net and IJobs, I’ll venture a suggestion still.

Consider the following Job wrapper:

public class JobWrapper<T>: IJob where T:IJob
{
    private Func<Owned<T>> _jobFactory;

    public JobWrapper(Func<Owned<T>> jobFactory)
    {
        _jobFactory = jobFactory;
    }


    void IJob.Execute()
    {
        using (var ownedJob = _jobFactory())
        {
            var theJob = ownedJob.Value;
            theJob.Execute();
        }
    }
}

Given the following registrations:

builder.RegisterGeneric(typeof(JobWrapper<>));
builder.RegisterType<SomeJob>();

A job factory could now resolve this wrapper:

var job = _container.Resolve<JobWrapper<SomeJob>>();

Note: a lifetime scope will be created as part of the ownedJob instance, which in this case is of type Owned<SomeJob>. Any dependencies required by SomeJob that is InstancePerLifetimeScope or InstancePerDependency will be created and destroyed along with the Owned instance.