Meters gather information from Sensors in a ResinSystem. Some sampled
meters like the CPU and JMX don't have an associated Sensor, but gather
the data as they are polled.
Meters typically gather information when polled and then reset any internal
accumulated counters. For example, a request counter meter will clear the
request count after being sampled.
Meter values can typically be peeked which will return the current value
without resetting internal counters.