Tim Vernum 90ba77951a
Fix memory leak in DLS bitset cache (#50946)
The Document Level Security BitSet cache stores a secondary "lookup
map" so that it can determine which cache entries to invalidate when
a Lucene index is closed (merged, etc).

There was a memory leak because this secondary map was not cleared
when entries were naturally evicted from the cache (due to size/ttl
limits).

This has been solved by adding a cache removal listener and processing
those removal events asyncronously.

Backport of: #50635
2020-01-14 13:19:05 +11:00
..