mesos/spark — pull request #463 by stephenh (2013-02-11 16:38:23+00:00)
Title: Add IndexedSet to help manage workers/jobs.

This is admittedly somewhat cute, but I like the idea of more strictly/DRYly applying the "remove the job from all xxxToJob indexes" logic, instead of having to manually remember to do the "xxxToJob -= job" calls.