Discussion: How do we handle resets of empty groups?

[mattdodge]

Consider the following situation:

• A counter block has a few groups (groupA, groupB, groupC) accumulating signals.
• A reset happens, the block notifies positive cumulative counts for all three groups
• More signals come in, but only for groups A and B
• When the reset happens, should a cumulative_count of 0 be notified for groupC?

Pros to notifying a 0 cumulative count:

• You want to know that no signals came for group C

Cons to notifying a 0 cumulative count:

• Assumes "fixed" groups - groups can never die basically

[hansmosh]

Not notifying 0 - In some services, it is important to know that a group has 0 signals since the last reset. If the counter block did not output the 0 count groups, is there another block that could be put after the counter to get those 0 count signals? If so, we could add that info as a helpful tip in the counter README.

Notifying 0 - If we decide to leave it, we could at least add a flag to the "reset" command to clear empty groups. Or even a bool property on the block.