Fraud detection: limit number of measurements per round

[bajtos]

Detect when a checker node is submitting too many measurements.

In https://www.notion.so/pl-strflt/SPARK-tasking-v2-604e26d57f6b4892946525bcb3a77104, we are describing the following parameters:

• CC - “committee count” - how many committees we want to form. Initially, this will be a hardcoded parameter. We will manually tweak it over time based on the number of active checker nodes.
• TC - “tasks per committee” - how many tasks to define for each committee.
• TN - “tasks per node” - how many tasks a node performs. This value should be a fraction of TC, e.g. TN = TC/5

At the moment, CC=1 and TC=400.

Assuming retrievals are fast and can be completed in ~1 second, and the spark checker waits for 10 seconds between tasks, and the SPARK round is ~60 minutes, then an honest node can complete around 327 tasks per round.

Proposed changes:

• Add a new fraud detection step to reward only the measurements for the first 300 unique tasks. Because measurements are not associated with Station instances, we should use (participant_address, inet_group) as the identifier.

[bajtos]

@juliangruber I think you already implemented this, right?

It would also be great to add telemetry & visualisation - p5/p50/p95 values for the "number of measurements submitted by a node" so that we know how often we slash nodes.

Should we keep this issue open to remind us of this remaining task?

[bajtos]

See #101

[juliangruber]

@juliangruber I think you already implemented this, right?

Yes, in #101.

It would also be great to add telemetry & visualisation - p5/p50/p95 values for the "number of measurements submitted by a node" so that we know how often we slash nodes.

Good idea!

#104

Should we keep this issue open to remind us of this remaining task?

Merging that PR will close this issue :)