High-performance single server worker implementation using EF Core transactional outbox pattern and SemaphoreSlim

[zejji]

When running Hangfire on a single server, there are currently two things which I would love to see:

• when using EF Core, I don't believe there is any way to implement the transactional outbox pattern with Hangfire so that jobs are only queued if other changes made to a DbContext are successfully saved; and
• short-polling or long-polling on a database storage are very inefficient, so it would be helpful to have a single-server implementation which uses a Semaphore to communicate to the worker when a job is ready to pick up.

Is there any possibility to implement this? If so, where would one start?

Also, I note that there was a highly-upvoted issue regarding an async method for EnqueueJob. Is this likely to happen at any point in the near future?