[core] Implements UniformGenerator.
[core] Implements UniformGenerator.

gaoning777/YCSB-C-DTranx,basicthinker/YCSB-C,basicthinker/YCSB-C,basicthinker/YCSB-C,gaoning777/YCSB-C-DTranx,gaoning777/YCSB-C-DTranx,basicthinker/YCSB-C,gaoning777/YCSB-C-DTranx,gaoning777/YCSB-C-DTranx,basicthinker/YCSB-C