ts: don't send DeleteRange requests for time series with nothing to p…

[spencerkimball]

…rune

All the information was there, just needed to be put to use. This isn't
a huge deal in practice, but eliminates sending DeleteRange requests for
time series data which isn't ready for pruning.

---

This change is 

[mrtracy]

---

Review status: 0 of 2 files reviewed at latest revision, 1 unresolved discussion, some commit checks pending.

---

pkg/ts/pruning.go, line 118 at r1 (raw file):

		// Skip this time series if there's nothing to prune. We check the
		// oldest (first) time series record's timestamp against the
		// pruning threshold.

nit: You could also use the computeThresholds method for this.

// once at start of "findTimeSeries"
thresholds = computeThresholds(timestamp.WallTime)

// When deciding to skip
if threshold, ok := thresholds[res]; !ok || threshold > tsNanos

That mirrors what is done in the pruneTimeSeries method.

---

Comments from Reviewable

[spencerkimball]

Review status: 0 of 2 files reviewed at latest revision, 1 unresolved discussion, all commit checks successful.

---

pkg/ts/pruning.go, line 118 at r1 (raw file):

Previously, mrtracy wrote…

nit: You could also use the computeThresholds method for this.

// once at start of "findTimeSeries"
thresholds = computeThresholds(timestamp.WallTime)

// When deciding to skip
if threshold, ok := thresholds[res]; !ok || threshold > tsNanos

That mirrors what is done in the pruneTimeSeries method.

Done.

---

Comments from Reviewable

[tamird]

Looks like this caused some emergent flakiness in TestTimeSeriesMaintenanceQueueServer.