func loadRangeDescriptor(
db engine.Engine, rangeID roachpb.RangeID,
) (roachpb.RangeDescriptor, error) {
var desc roachpb.RangeDescriptor
handleKV := func(kv engine.MVCCKeyValue) (bool, error) {
if kv.Key.Timestamp == hlc.ZeroTimestamp {
// We only want values, not MVCCMetadata.
return false, nil
}
if err := checkRangeDescriptorKey(kv.Key); err != nil {
// Range descriptor keys are interleaved with others, so if it
// doesn't parse as a range descriptor just skip it.
return false, nil
}
if err := getProtoValue(kv.Value, &desc); err != nil {
return false, err
}
return desc.RangeID == rangeID, nil
}
// Range descriptors are stored by key, so we have to scan over the
// range-local data to find the one for this RangeID.
start := engine.MakeMVCCMetadataKey(keys.LocalRangePrefix)
end := engine.MakeMVCCMetadataKey(keys.LocalRangeMax)
if err := db.Iterate(start, end, handleKV); err != nil {
return roachpb.RangeDescriptor{}, err
}
if desc.RangeID == rangeID {
return desc, nil
}
return roachpb.RangeDescriptor{}, fmt.Errorf("range descriptor %d not found", rangeID)
}
