Feature idea: strategy for when the queue is full

[cocowalla]

At present, the BackgroundWorkerSink will drop messages when the queue is full. It would be good to be able to configure this behaviour so there is an option to block instead of drop.

[nblumhardt]

I think this would be a great addition to the sink. It should be enough to represent it with a bool and switch behavior in Emit().

I'm not likely to pick this up in the short term, but can help with a PR if anyone decides to take it on.

[cocowalla]

@nblumhardt I'll have a crack at this one.

I also noticed there doesn't seem to be a test for the existing 'drop' behaviour, so I'll try to add tests for both the 'drop' and 'block' strategies.

The while (true) loop also doesn't seem a very elegant way to handle queue enumeration, so I'll switch to _queue.GetConsumingEnumerable() and call _queue.CompleteAdding() in Dispose(). This also means we can lose the CancellationToken, which will simplify the code a bit.

[cocowalla]

@nblumhardt I submitted PR #21 for this

[bartelink]

@cocowalla I'm going to go out on a limb and declare this Done Done ;)