Simple request level cache for JENKINS-64036

[aubelix]

Cache for expensive Database Queries during DownstreamPipelineTriggerRunListener#onCompleted

This cache is only used during the execution of onComplete and destroyed afterwards

We did this fix to tune the DownstreamPipelineTriggerRunListener for a very large setup. Before the fix it took up to 30 minutes. After the fix some seconds

Maybee PR-323 is also a win, this was not integrated, when we tested it

[bguerin]

Hello @aubelix

Thank you for your pull request. I understand it solves your performance problem and I see how, but it is a solution I would like to avoid. Consuming memory with such a cache seems a way to hide a real problem to me and I would prefer to address the problem in the first place.

Pull request 323 is now merged and version 3.11.0 of the plugin has been released this afternoon. Could you please git this version a try and send a feedback if performance is better or not ? If not, I will consider merge your cache in.