Summary:
This is a proof of concept of a RocksDB blob log file. The actual value of the Put() is appended to a blob log using normal data block format, and the handle of the block is written as the value of the key in RocksDB.
The prototype only supports Put() and Get(). It doesn't support DB restart, garbage collection, Write() call, iterator, snapshots, etc.
Test Plan: Add unit tests.
Reviewers: arahut
Reviewed By: arahut
Subscribers: kradhakrishnan, leveldb, andrewkr, dhruba
Differential Revision: https://reviews.facebook.net/D61485
