Colin Goodheart-Smithe 2d64e3db9a
Adds trace logging to IndicesRequestCache (#34180)
* Adds trace logging to IndicesRequestCache

This change adds trace level logging to `IndicesrrequestCache` witht eh
primary aim of helping to identify the cause of teh failures in
https://github.com/elastic/elasticsearch/issues/32827. The cache will
log at trace level when a cache hit or miss occurs including the reader
version and the cache key. Note that this change adds a
`cacheKeyRenderer` whcih supplies a human readable String of the cache
key since the actual cache key itself is a `BytesReference` containing
the wire protocol serialised form of the request.

Logging is also added for the case where a search timeout occurs and fr
that reason the cache entry is invalidated.

* Adds comment to remaind us to remove cacheKeyRenderer
2018-10-03 08:58:33 +01:00
..