func sequenceCacheKeyPrint(key roachpb.Key) string {
b, id, err := encoding.DecodeBytesAscending([]byte(key), nil)
if err != nil {
return fmt.Sprintf("/%q/err:%v", key, err)
}
txnID, err := uuid.FromBytes(id)
if err != nil {
return fmt.Sprintf("/%q/err:%v", key, err)
}
if len(b) == 0 {
return fmt.Sprintf("/%q", txnID)
}
b, epoch, err := encoding.DecodeUint32Descending(b)
if err != nil {
return fmt.Sprintf("/%q/err:%v", txnID, err)
}
_, seq, err := encoding.DecodeUint32Descending(b)
if err != nil {
return fmt.Sprintf("/%q/epoch:%d/err:%v", txnID, epoch, err)
}
return fmt.Sprintf("/%q/epoch:%d/seq:%d", txnID, epoch, seq)
}
// DecodeSequenceCacheKey decodes the provided sequence cache entry,
// returning the transaction ID, the epoch, and the sequence number.
func DecodeSequenceCacheKey(key roachpb.Key, dest []byte) (*uuid.UUID, uint32, uint32, error) {
// TODO(tschottdorf): redundant check.
if !bytes.HasPrefix(key, LocalRangeIDPrefix) {
return nil, 0, 0, util.Errorf("key %s does not have %s prefix", key, LocalRangeIDPrefix)
}
// Cut the prefix, the Range ID, and the infix specifier.
b := key[len(LocalRangeIDPrefix):]
b, _, err := encoding.DecodeUvarintAscending(b)
if err != nil {
return nil, 0, 0, err
}
b = b[1:]
if !bytes.HasPrefix(b, LocalSequenceCacheSuffix) {
return nil, 0, 0, util.Errorf("key %s does not contain the sequence cache suffix %s",
key, LocalSequenceCacheSuffix)
}
// Cut the sequence cache suffix.
b = b[len(LocalSequenceCacheSuffix):]
// Decode the id.
b, idBytes, err := encoding.DecodeBytesAscending(b, dest)
if err != nil {
return nil, 0, 0, err
}
// Decode the epoch.
b, epoch, err := encoding.DecodeUint32Descending(b)
if err != nil {
return nil, 0, 0, err
}
// Decode the sequence number.
b, seq, err := encoding.DecodeUint32Descending(b)
if err != nil {
return nil, 0, 0, err
}
if len(b) > 0 {
return nil, 0, 0, util.Errorf("key %q has leftover bytes after decode: %s; indicates corrupt key",
key, b)
}
txnID, err := uuid.FromBytes(idBytes)
return txnID, epoch, seq, err
}