It would be useful to get more information from the DIH during an indexing run. The initial requirements for this patch are:
1. Add a cumulative "documents per second" calculation for the currently-running index process
2. Add the ability for each EntityProcessor to report its own custom statistics in a manner appropriate to the nature of its work
For example, the SQLEntityProcessor might show the total number of queries performed, the average time to execute each of those queries, the total amount of time it spent executing its queries, etc.
The CachedSQLEntityProcessor might show cache hit counts, cache miss counts, the current size of the cache, etc.