// 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, id []byte, dest *roachpb.SequenceCacheEntry) (uint32, uint32, error) { if len(id) == 0 { 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, id) 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 := 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 }
// GetAllTransactionID returns all the key-value pairs for the given transaction ID from // the engine. func (sc *SequenceCache) GetAllTransactionID(e engine.Engine, id []byte) ([]roachpb.KeyValue, error) { prefix := keys.SequenceCacheKeyPrefix(sc.rangeID, id) kvs, _, err := engine.MVCCScan(e, prefix, prefix.PrefixEnd(), 0, /* max */ roachpb.ZeroTimestamp, true /* consistent */, nil /* txn */) return kvs, err }
// Del removes all sequence cache entries for the given transaction. func (sc *SequenceCache) Del(e engine.Engine, ms *engine.MVCCStats, txnID *uuid.UUID) error { startKey := keys.SequenceCacheKeyPrefix(sc.rangeID, txnID) _, err := engine.MVCCDeleteRange(e, ms, startKey, startKey.PrefixEnd(), 0 /* max */, roachpb.ZeroTimestamp, nil /* txn */, false /*returnKeys*/) return err }