// Get looks up the latest sequence number recorded for this transaction ID. // The latest entry is that with the highest epoch (and then, highest // sequence). On a miss, zero is returned for both. If an entry is found and a // SequenceCacheEntry is provided, it is populated from the found value. func (sc *SequenceCache) Get(e engine.Engine, txnID *uuid.UUID, dest *roachpb.SequenceCacheEntry) (uint32, uint32, error) { if txnID == nil { return 0, 0, errEmptyTxnID } // Pull response from disk and read into reply if available. Sequence // number sorts in decreasing order, so this gives us the largest entry or // an entry which isn't ours. To avoid encoding an end key for the scan, // we just scan and check via a simple prefix check whether we read a // key for "our" cache id. prefix := keys.SequenceCacheKeyPrefix(sc.rangeID, txnID) kvs, _, err := engine.MVCCScan(e, prefix, sc.max, 1, /* num */ roachpb.ZeroTimestamp, true /* consistent */, nil /* txn */) if err != nil || len(kvs) == 0 || !bytes.HasPrefix(kvs[0].Key, prefix) { return 0, 0, err } _, epoch, seq, err := keys.DecodeSequenceCacheKey(kvs[0].Key, sc.scratchBuf[:0]) if err != nil { return 0, 0, err } if dest != nil { dest.Reset() // Caller wants to have the unmarshaled value. if err := kvs[0].Value.GetProto(dest); err != nil { return 0, 0, err } } return epoch, seq, nil }
func trySequence(kv engine.MVCCKeyValue) (string, error) { if kv.Key.Timestamp != roachpb.ZeroTimestamp { return "", errors.New("not a sequence cache key") } _, _, _, err := keys.DecodeSequenceCacheKey(kv.Key.Key, nil) if err != nil { return "", err } var dest roachpb.SequenceCacheEntry if err := maybeUnmarshalInline(kv.Value, &dest); err != nil { return "", err } return fmt.Sprintf("ts=%s, key=%q\n", dest.Timestamp, dest.Key), nil }
// Iterate walks through the sequence cache, invoking the given callback for // each unmarshaled entry with the key, the transaction ID and the decoded // entry. func (sc *SequenceCache) Iterate(e engine.Engine, f func([]byte, *uuid.UUID, roachpb.SequenceCacheEntry)) { _, _ = engine.MVCCIterate(e, sc.min, sc.max, roachpb.ZeroTimestamp, true /* consistent */, nil /* txn */, false, /* !reverse */ func(kv roachpb.KeyValue) (bool, error) { var entry roachpb.SequenceCacheEntry txnID, _, _, err := keys.DecodeSequenceCacheKey(kv.Key, nil) if err != nil { panic(err) // TODO(tschottdorf): ReplicaCorruptionError } if err := kv.Value.GetProto(&entry); err != nil { panic(err) // TODO(tschottdorf): ReplicaCorruptionError } f(kv.Key, txnID, entry) return false, nil }) }
func decodeSequenceCacheMVCCKey(encKey engine.MVCCKey, dest []byte) (*uuid.UUID, uint32, uint32, error) { if encKey.IsValue() { return nil, 0, 0, util.Errorf("key %s is not a raw MVCC value", encKey) } return keys.DecodeSequenceCacheKey(encKey.Key, dest) }