Refactor ClientHandler::clientRequest().

Mainly a lot of early returns and some restructuring.

The ExecuteResponse is now sent as soon as the Request Id is known.

Signed-off-by: Jacob Kiers <jacob@alphacomm.nl>
Refactor ClientHandler::clientFetch().

Mostly improved log messages and early returns.

Signed-off-by: Jacob Kiers <jacob@alphacomm.nl>
Refactor ClientHandler::sendResponseToClients().

The most important part of this change is extracting the poison status
check. That improves readability a lot.

Signed-off-by: Jacob Kiers <jacob@alphacomm.nl>
Improve ClientHandler::handleExpiredWorkerHandlers().

Mainly readability improvements, and a better log message.

Signed-off-by: Jacob Kiers <jacob@alphacomm.nl>
Add and use Request::get/setWorkerHandlerId().

The functions were called Request::get/setWorker(), but in actuality
these didn't set the worker, but the ID of the Worker Handler.

Made the old functions proxy the new ones, and deprecated them.

Signed-off-by: Jacob Kiers <jacob@alphacomm.nl>