Currently each stat item has a separate index value which basically
counts each single value added to the item and which can be used by
a reporter to get all new values that have not been reported yet.
The drawback is, that such an index must be stored for each stat
item.
This commit introduces a global index which is incremented for each
new stat item value. This index is then stored together with the item
value. So a single stored index per reporter is sufficient to make
sure that only new values are reported.
Sponsored-by: On-Waves ehf
This commit adds instrumentation function to gather measurement
and statistical values similar to counter groups.
Multiple values can be stored per item, which can be retrieved in
FIFO order. Getting values from the item does not modify its state to
allow for multiple independant backends (e.g. VTY and statd).
When a new value is set, the oldest value gets silently overwritten.
Lost values are skipped when getting values from the item.
Sponsored-by: On-Waves ehf
Jacob Erlbeck