* fix redis caching issue
earlier redis cache was updated when there was any error including any
temporary connectivity issue. This would trigger set calls which would
further increase load and possibly connectivity errors from redis
leaving the system with continuous errors and high latency. Now the
cache is updated only when it is genuine cache miss. Other errors do not
trigger a cache update.
* add back tracker Hit() and Miss() calls
*squashed commits*
(cherry picked from commit 6f3e1c10260ef59ba4e9c42e939329fad9fdd8c3)
(cherry picked from commit 6738ff3320cf82cc2df919a95a1bde2f7789a501)
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
ce101280fe