Merge #95579

95579: kvserver: fix store disable gossip lease override r=andrewbaptist a=kvoli

In #93945 the store gossip logic was refactored to take into account the relative difference rather than cumulative number of changes. This led to a bug where disabling lease capacity changes from triggering gossip wasn't adhered to in all cases.

This introduced a flake where `TestStoreRangeGossipOnSplits` and the underlying behavior being tested diverged slightly. This patch fixes the issue.

Fixes: #95566

Release note: None

Co-authored-by: Austen McClernon <[email protected]>

pkg/kv/kvserver/client_split_test.go

@@ -2308,6 +2308,12 @@ func TestStoreRangeGossipOnSplits(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 	defer log.Scope(t).Close(t)
 
+	// 50% for testing We can't properly test how frequently changes in the
+	// number of ranges trigger the store to gossip its capacities if we have
+	// to worry about changes in the number of leases also triggering store
+	// gossip.
+	overrideCapacityFraction := 0.5
+
 	ctx := context.Background()
 	serv, _, _ := serverutils.StartServer(t, base.TestServerArgs{
 		Knobs: base.TestingKnobs{
@@ -2316,11 +2322,8 @@ func TestStoreRangeGossipOnSplits(t *testing.T) {
 				DisableSplitQueue: true,
 				DisableScanner:    true,
 				GossipTestingKnobs: kvserver.StoreGossipTestingKnobs{
-					OverrideGossipWhenCapacityDeltaExceedsFraction: 0.5, // 50% for testing
-					// We can't properly test how frequently changes in the number of ranges
-					// trigger the store to gossip its capacities if we have to worry about
-					// changes in the number of leases also triggering store gossip.
-					DisableLeaseCapacityGossip: true,
+					OverrideGossipWhenCapacityDeltaExceedsFraction: overrideCapacityFraction,
+					DisableLeaseCapacityGossip:                     true,
 				},
 			},
 		},
@@ -2385,7 +2388,10 @@ func TestStoreRangeGossipOnSplits(t *testing.T) {
 		}
 		select {
 		case rangeCount = <-rangeCountCh:
-			changeCount := int32(math.Ceil(math.Max(float64(lastRangeCount)*0.5, 10)))
+			changeCount := int32(math.Ceil(math.Max(
+				float64(lastRangeCount)*overrideCapacityFraction,
+				kvserver.GossipWhenRangeCountDeltaExceeds,
+			)))
 			diff := rangeCount - (lastRangeCount + changeCount)
 			if diff < -1 || diff > 1 {
 				t.Errorf("gossiped range count %d more than 1 away from expected %d", rangeCount, lastRangeCount+changeCount)

pkg/kv/kvserver/store_gossip.go

@@ -44,11 +44,11 @@ const (
 	//  gossip interval.
 	gossipWhenLeaseCountDeltaExceeds = 5
 
-	// gossipWhenRangeCountDeltaExceeds specifies the absolute change from the
+	// GossipWhenRangeCountDeltaExceeds specifies the absolute change from the
 	// last gossiped store capacity range count which needs to be exceeded
 	// before the store will gossip immediately without waiting for the
 	// periodic gossip interval.
-	gossipWhenRangeCountDeltaExceeds = 5
+	GossipWhenRangeCountDeltaExceeds = 5
 
 	// gossipWhenLoadDeltaExceedsFraction specifies the fraction from the last
 	// gossiped store capacity load which needs to be exceeded before the store
@@ -394,9 +394,6 @@ const (
 // immediate gossip of this store's descriptor, to include updated
 // capacity information.
 func (s *StoreGossip) MaybeGossipOnCapacityChange(ctx context.Context, cce CapacityChangeEvent) {
-	if s.knobs.DisableLeaseCapacityGossip && (cce == LeaseAddEvent || cce == LeaseRemoveEvent) {
-		return
-	}
 
 	// Incrementally adjust stats to keep them up to date even if the
 	// capacity is gossiped, but isn't due yet to be recomputed from scratch.
@@ -460,16 +457,18 @@ func (s *StoreGossip) shouldGossipOnCapacityDelta() (should bool, reason string)
 	updateForWPS, deltaWPS := deltaExceedsThreshold(
 		s.cachedCapacity.lastGossiped.WritesPerSecond, s.cachedCapacity.cached.WritesPerSecond,
 		gossipMinAbsoluteDelta, gossipWhenLoadDeltaExceedsFraction)
-
 	updateForRangeCount, deltaRangeCount := deltaExceedsThreshold(
 		float64(s.cachedCapacity.lastGossiped.RangeCount), float64(s.cachedCapacity.cached.RangeCount),
-		gossipWhenRangeCountDeltaExceeds, gossipWhenCapacityDeltaExceedsFraction)
-
+		GossipWhenRangeCountDeltaExceeds, gossipWhenCapacityDeltaExceedsFraction)
 	updateForLeaseCount, deltaLeaseCount := deltaExceedsThreshold(
 		float64(s.cachedCapacity.lastGossiped.LeaseCount), float64(s.cachedCapacity.cached.LeaseCount),
 		gossipWhenLeaseCountDeltaExceeds, gossipWhenCapacityDeltaExceedsFraction)
 	s.cachedCapacity.Unlock()
 
+	if s.knobs.DisableLeaseCapacityGossip {
+		updateForLeaseCount = false
+	}
+
 	if updateForQPS {
 		reason += fmt.Sprintf("queries-per-second(%.1f) ", deltaQPS)
 	}