#3759 [HHQ-3256] RegisteredTriggers has bad concurrency semantics

[Hyperic Team]

http://jira.hyperic.com/browse/HHQ-3256
Found by code inspection.

RegisteredTriggers.keyedByType and keyedByTrigger are used in a thread-unsafe way. RegisteredTriggers.getInterestedTriggers() is one path into the bad semantics. The private method getTriggerMap() does most of the unsafe access, but other places in RegisteredTriggers also access these data structures.

This bug is untestable by QA, so the fix would have to be validated by unittests. A suitable unittest must have concurrent registering and unregistering of triggers for verious event types to exercise the lookup code in concurrent threads.