settings: simplify the container

This commit uses the "value origin" field now throughout to decide
whether or not a setting was modified.

Release note: None

pkg/settings/updater.go

@@ -145,7 +145,6 @@ func (u updater) setInternal(
 ) error {
 	// Mark the setting as modified, such that
 	// (updater).ResetRemaining() does not touch it.
-	u.sv.container.modified[d.getSlot()] = true
 	u.sv.setValueOrigin(ctx, d.getSlot(), origin)
 
 	switch setting := d.(type) {
@@ -218,7 +217,6 @@ func (u updater) SetToDefault(ctx context.Context, key InternalKey) error {
 		return errors.Errorf("unknown setting '%s'", key)
 	}
 
-	u.sv.container.modified[d.getSlot()] = false
 	u.sv.setValueOrigin(ctx, d.getSlot(), OriginDefault)
 	d.setToDefault(ctx, u.sv)
 	return nil
@@ -227,18 +225,11 @@ func (u updater) SetToDefault(ctx context.Context, key InternalKey) error {
 // ResetRemaining sets all settings not updated by the updater to their default values.
 func (u updater) ResetRemaining(ctx context.Context) {
 	for _, v := range registry {
-		slot := v.getSlot()
-		if hasOverride := u.sv.container.modified[slot]; hasOverride {
-			u.sv.setValueOrigin(ctx, slot, OriginExplicitlySet)
-		} else {
-			u.sv.setValueOrigin(ctx, slot, OriginDefault)
-		}
-
 		if u.sv.SpecializedToVirtualCluster() && v.Class() == SystemOnly {
 			// Don't try to reset system settings on a non-system tenant.
 			continue
 		}
-		if m := u.sv.container.modified[slot]; !m {
+		if u.sv.getValueOrigin(ctx, v.getSlot()) == OriginDefault {
 			v.setToDefault(ctx, u.sv)
 		}
 	}

pkg/settings/values.go

@@ -86,12 +86,8 @@ type valuesContainer struct {
 	// tenant). Reading or writing such a setting causes panics in test builds.
 	forbidden [numSlots]bool
 
+	// hasValue contains the origin of the current value of the setting.
 	hasValue [numSlots]uint32
-
-	// modified is set when a setting is explictly set via Set()
-	// in the updater.
-	// TODO(knz): Check if this can be merged with hasValue above.
-	modified [numSlots]bool
 }
 
 func (c *valuesContainer) setGenericVal(slot slotIdx, newVal interface{}) {