Draft: Allow invoked pipelines to complete, mitigate blocking on status channel

[peteski22]

DRAFT: IN PROGRESS

This PR is intended to be used initially for discussion of potential changes/improvements to go-eventlogger.

Perceived issues:

• graph.process The Status channel is changed from unbuffered (default size) to buffered, the size will be the estimated number of nodes within all pipelines (number of root nodes * 3). This is to prevent occurrence of sending messages to a blocked channel is no longer being received on
• graph.process While ranging over the root nodes, do not invoke roots when we know the context is already Done
• graph.doProcess parameter tweaked so the channel supplied can only be used for sending
• broker.SetRequireAllPipelinesComplete Added broker-level setting (per event type) to decide whether process should allow all invoked pipelines to complete and return their status before gathering/fanning-in

[peteski22]

UPDATE:

Most of this was a waste of time 😄 as doProcess doesn't allow returning the status if the context is cancelled.

Side note: there was a bug in this anyway when we came to Store as we'd need to have checked if the pipeline already exists in the map and only increment if it didn't.

TL;DR: Not really relevant and I had the wrong end of the stick, I should read the Go docs next time!

doProcess: // # No Status is sent when a request is cancelled by the context