Getting the values recorded during an interval requires calling
`reset()`, which removes them for every other user of the histogram,
or copying and subtracting histograms, which silently produces a wrong
result when the source was reset in between.
Add `histogram.diff(other)`, which returns a new read-only `Histogram`
containing the values recorded after `other`, an earlier snapshot of
the histogram, was taken. Neither histogram is changed. Unlike
`subtract()`, it verifies that both histograms have the same layout,
and it throws instead of clamping when `other` contains values that
the histogram does not.
Add `histogram.resetCount`, the number of calls to `reset()` and
`subtract()`, which `snapshot()` copies. `diff()` throws when the
counts differ, so a reset between two snapshots is detected even when
every bucket has since grown past its previous count.
Signed-off-by: James M Snell <jasnell@gmail.com>
Assisted-by: OpenCode
PR-URL: https://github.com/nodejs/node/pull/66099
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
James M Snell
a3bb551ea7