BUG-1120: promote synchronization to all entrypoints

This is a temporary regression in performance: get rid of the
synchronized map at the cost of explicit synchronized methods.
Subsequent patches will remove the synchronization from the fast paths.

Change-Id: Ibe90e4e7ff99655a69b77c942ad50baec9df1ba2
Signed-off-by: Robert Varga <rovarga@cisco.com>