Context
Found while reviewing #478.
The stable process differential creates a data point at wall-clock now and immediately sends an empty watermark at now + 2 seconds:
ddsketch_export(METRIC, sample_ns, &raw_values)
ddsketch_export(METRIC, sample_ns + 2_000_000_000, &[])
This makes the test fast, but it exercises acceptance of future event time rather than the normal collector/backend timing contract. It may hide bugs in real window close, allowed lateness, watermark progression, and query evaluation relative to wall clock. The whole-backend E2E already avoids this by waiting for the controller-selected window to actually end.
Reproduction
./scripts/e2e.sh differential
Location: data_plane/tests/promql_differential_process_e2e.rs, around lines 235-242.
Expected
The stable production-process differential should not require future-dated telemetry.
Preferred options:
- wait for the one-second window to end, then emit a wall-clock watermark; or
- expose and wait for an explicit ingest/window-commit signal without modifying event timestamps.
Done when
The test passes using realistic non-future timestamps and deterministically observes the committed window without a fixed blind sleep.
Context
Found while reviewing #478.
The stable process differential creates a data point at wall-clock
nowand immediately sends an empty watermark atnow + 2 seconds:This makes the test fast, but it exercises acceptance of future event time rather than the normal collector/backend timing contract. It may hide bugs in real window close, allowed lateness, watermark progression, and query evaluation relative to wall clock. The whole-backend E2E already avoids this by waiting for the controller-selected window to actually end.
Reproduction
Location:
data_plane/tests/promql_differential_process_e2e.rs, around lines 235-242.Expected
The stable production-process differential should not require future-dated telemetry.
Preferred options:
Done when
The test passes using realistic non-future timestamps and deterministically observes the committed window without a fixed blind sleep.