Use sampleBuf instead of maintaining lastValue. (#444)
Use sampleBuf instead of maintaining lastValue. (#444)

This cuts the size of memSize by 8B.

Signed-off-by: Brian Brazil <aadf89994a343dc176a47081f0c0bbea26f0a345@robustperception.io>
alileza/prometheus,keegancsmith/prometheus,Gouthamve/prometheus,prometheus/prometheus,prometheus/prometheus,Gouthamve/prometheus,kangwoo/prometheus,GoogleCloudPlatform/prometheus,alileza/prometheus,prometheus/prometheus,keegancsmith/prometheus,alileza/prometheus,prometheus/prometheus,keegancsmith/prometheus,GoogleCloudPlatform/prometheus,Gouthamve/tsdb,Gouthamve/prometheus,prometheus/tsdb,GoogleCloudPlatform/prometheus,keegancsmith/prometheus,alileza/prometheus,alileza/prometheus,kangwoo/prometheus,GoogleCloudPlatform/prometheus,prometheus/prometheus,keegancsmith/prometheus,kangwoo/prometheus,Gouthamve/prometheus,GoogleCloudPlatform/prometheus,kangwoo/prometheus