Export more perf_context and iostats_context

[yoshinorim]

Recently RocksDB added more status counters -- https://reviews.facebook.net/D39177
We need to export these stats into information_schema.

[yoshinorim]

And some other status counters, such as rocksdb.db.mutex.wait.micros.

[jtuple]

Added several additional metrics in commit d9eb6ec. Not sure what other metrics we should export. Is there any reason we shouldn't just export all pertf_context and iostats_context stats?

[yoshinorim]

@jtuple You're right, we should just export all *_context stats. We haven't found a way to keep track of RocksDB side changes (RocksDB added some stats after we initially supported perf_context).

[jkedgar]

Just to be clear... You want all the values in perf_context.h (currently a total of 34) and iostats_context.h (currently a total of 9) to show up in information_schema.rocksdb_perf_context_global. Correct?

[yoshinorim]

Yes.

[jkedgar]

Closed with https://reviews.facebook.net/D46437