Summary:
* Introduce is histogram in statistics.h
* stop watch to measure time.
* introduce two timers as a poc.
Replaced NULL with nullptr to fight some lint errors
Should be useful for google.
Test Plan:
ran db_bench and check stats.
make all check
Reviewers: dhruba, heyongqiang
Reviewed By: dhruba
CC: leveldb
Differential Revision: https://reviews.facebook.net/D8637
Summary:
Earlier way to record in histogram=>
Linear search BucketLimit array to find the bucket and increment the
counter
Current way to record in histogram=>
Store a HistMap statically which points the buckets of each value in the
range [kFirstValue, kLastValue);
In the proccess use vectors instead of array's and refactor some code to
HistogramHelper class.
Test Plan:
run db_bench with histogram=1 and see a histogram being
printed.
Reviewers: dhruba, chip, heyongqiang
Reviewed By: chip
CC: leveldb
Differential Revision: https://reviews.facebook.net/D8265
