// watchRelationUnits starts watching the relation units for the given
// relation, waits for its first event, and records the information in
// the current snapshot.
func (w *RemoteStateWatcher) watchRelationUnits(
rel Relation, relationTag names.RelationTag, in apiwatcher.RelationUnitsWatcher,
) error {
relationSnapshot := RelationSnapshot{
Life: rel.Life(),
Members: make(map[string]int64),
}
select {
case <-w.tomb.Dying():
return tomb.ErrDying
case change, ok := <-in.Changes():
if !ok {
return watcher.EnsureErr(in)
}
for unit, settings := range change.Changed {
relationSnapshot.Members[unit] = settings.Version
}
}
w.current.Relations[rel.Id()] = relationSnapshot
w.relations[relationTag] = newRelationUnitsWatcher(
rel.Id(), in, w.relationUnitsChanges,
)
return nil
}
