func (rc *ResponseCache) decodeResponseCacheKey(encKey roachpb.EncodedKey) (roachpb.ClientCmdID, error) {
ret := roachpb.ClientCmdID{}
key, _, isValue, err := engine.MVCCDecodeKey(encKey)
if err != nil {
return ret, err
}
if isValue {
return ret, util.Errorf("key %s is not a raw MVCC value", encKey)
}
if !bytes.HasPrefix(key, keys.LocalRangeIDPrefix) {
return ret, util.Errorf("key %s does not have %s prefix", key, keys.LocalRangeIDPrefix)
}
// Cut the prefix and the Range ID.
b := key[len(keys.LocalRangeIDPrefix):]
b, _, err = encoding.DecodeUvarint(b)
if err != nil {
return ret, err
}
if !bytes.HasPrefix(b, keys.LocalResponseCacheSuffix) {
return ret, util.Errorf("key %s does not contain the response cache suffix %s",
key, keys.LocalResponseCacheSuffix)
}
// Cut the response cache suffix.
b = b[len(keys.LocalResponseCacheSuffix):]
// Now, decode the command ID.
b, wt, err := encoding.DecodeUvarint(b)
if err != nil {
return ret, err
}
b, rd, err := encoding.DecodeUint64(b)
if err != nil {
return ret, err
}
if len(b) > 0 {
return ret, util.Errorf("key %s has leftover bytes after decode: %s; indicates corrupt key",
encKey, b)
}
ret.WallTime = int64(wt)
ret.Random = int64(rd)
return ret, nil
}
