// EndTransaction either commits or aborts (rolls back) an extant
// transaction according to the args.Commit parameter.
func (r *Range) EndTransaction(args *proto.EndTransactionRequest, reply *proto.EndTransactionResponse) {
	reply.SetGoError(util.Error("unimplemented"))
}

// EndTransaction either commits or aborts (rolls back) an extant
// transaction according to the args.Commit parameter.
func (r *Range) EndTransaction(batch engine.Engine, ms *engine.MVCCStats, args *proto.EndTransactionRequest, reply *proto.EndTransactionResponse) {
	if args.Txn == nil {
		reply.SetGoError(util.Errorf("no transaction specified to EndTransaction"))
		return
	}
	key := keys.TransactionKey(args.Txn.Key, args.Txn.ID)

	// Fetch existing transaction if possible.
	existTxn := &proto.Transaction{}
	ok, err := engine.MVCCGetProto(batch, key, proto.ZeroTimestamp, true, nil, existTxn)
	if err != nil {
		reply.SetGoError(err)
		return
	}
	// If the transaction record already exists, verify that we can either
	// commit it or abort it (according to args.Commit), and also that the
	// Timestamp and Epoch have not suffered regression.
	if ok {
		// Use the persisted transaction record as final transaction.
		reply.Txn = gogoproto.Clone(existTxn).(*proto.Transaction)

		if existTxn.Status == proto.COMMITTED {
			reply.SetGoError(proto.NewTransactionStatusError(existTxn, "already committed"))
			return
		} else if existTxn.Status == proto.ABORTED {
			reply.SetGoError(proto.NewTransactionAbortedError(existTxn))
			return
		} else if args.Txn.Epoch < existTxn.Epoch {
			reply.SetGoError(proto.NewTransactionStatusError(existTxn, fmt.Sprintf("epoch regression: %d", args.Txn.Epoch)))
			return
		} else if args.Txn.Epoch == existTxn.Epoch && existTxn.Timestamp.Less(args.Txn.OrigTimestamp) {
			// The transaction record can only ever be pushed forward, so it's an
			// error if somehow the transaction record has an earlier timestamp
			// than the original transaction timestamp.
			reply.SetGoError(proto.NewTransactionStatusError(existTxn, fmt.Sprintf("timestamp regression: %s", args.Txn.OrigTimestamp)))
			return
		}
		// Take max of requested epoch and existing epoch. The requester
		// may have incremented the epoch on retries.
		if reply.Txn.Epoch < args.Txn.Epoch {
			reply.Txn.Epoch = args.Txn.Epoch
		}
		// Take max of requested priority and existing priority. This isn't
		// terribly useful, but we do it for completeness.
		if reply.Txn.Priority < args.Txn.Priority {
			reply.Txn.Priority = args.Txn.Priority
		}
	} else {
		// The transaction doesn't exist yet on disk; use the supplied version.
		reply.Txn = gogoproto.Clone(args.Txn).(*proto.Transaction)
	}

	// Take max of requested timestamp and possibly "pushed" txn
	// record timestamp as the final commit timestamp.
	if reply.Txn.Timestamp.Less(args.Timestamp) {
		reply.Txn.Timestamp = args.Timestamp
	}

	// Set transaction status to COMMITTED or ABORTED as per the
	// args.Commit parameter.
	if args.Commit {
		// If the isolation level is SERIALIZABLE, return a transaction
		// retry error if the commit timestamp isn't equal to the txn
		// timestamp.
		if args.Txn.Isolation == proto.SERIALIZABLE && !reply.Txn.Timestamp.Equal(args.Txn.OrigTimestamp) {
			reply.SetGoError(proto.NewTransactionRetryError(reply.Txn))
			return
		}
		reply.Txn.Status = proto.COMMITTED
	} else {
		reply.Txn.Status = proto.ABORTED
	}

	// Persist the transaction record with updated status (& possibly timestamp).
	if err := engine.MVCCPutProto(batch, ms, key, proto.ZeroTimestamp, nil, reply.Txn); err != nil {
		reply.SetGoError(err)
		return
	}

	// Run triggers if successfully committed. Any failures running
	// triggers will set an error and prevent the batch from committing.
	if ct := args.InternalCommitTrigger; ct != nil {
		// Resolve any explicit intents.
		for _, key := range ct.Intents {
			if log.V(1) {
				log.Infof("resolving intent at %s on end transaction [%s]", key, reply.Txn.Status)
			}
			if err := engine.MVCCResolveWriteIntent(batch, ms, key, reply.Txn.Timestamp, reply.Txn); err != nil {
				reply.SetGoError(err)
				return
			}
			reply.Resolved = append(reply.Resolved, key)
		}
		// Run appropriate trigger.
		if reply.Txn.Status == proto.COMMITTED {
			if ct.SplitTrigger != nil {
				*ms = engine.MVCCStats{} // clear stats, as split will recompute from scratch.
				reply.SetGoError(r.splitTrigger(batch, ct.SplitTrigger))
//.........这里部分代码省略.........

// EndTransaction either commits or aborts (rolls back) an extant
// transaction according to the args.Commit parameter.
func (r *Range) EndTransaction(args *proto.EndTransactionRequest, reply *proto.EndTransactionResponse) {
	// Create the actual key to the system-local transaction table.
	key := engine.MakeKey(engine.KeyLocalTransactionPrefix, args.Key)
	// Start with supplied transaction, then possibly load from txn record.
	reply.Txn = gogoproto.Clone(args.Txn).(*proto.Transaction)

	// Fetch existing transaction if possible.
	existTxn := &proto.Transaction{}
	ok, err := engine.GetProto(r.engine, key, existTxn)
	if err != nil {
		reply.SetGoError(err)
		return
	}
	// If the transaction record already exists, verify that we can either
	// commit it or abort it (according to args.Commit), and also that the
	// Timestamp and Epoch have not suffered regression.
	if ok {
		if existTxn.Status == proto.COMMITTED {
			reply.SetGoError(proto.NewTransactionStatusError(existTxn, "already committed"))
			return
		} else if existTxn.Status == proto.ABORTED {
			reply.SetGoError(proto.NewTransactionStatusError(existTxn, "already aborted"))
			return
		} else if args.Txn.Epoch < existTxn.Epoch {
			reply.SetGoError(proto.NewTransactionStatusError(existTxn, fmt.Sprintf("epoch regression: %d", args.Txn.Epoch)))
			return
		} else if existTxn.Timestamp.Less(args.Txn.Timestamp) {
			// The transaction record can only ever be pushed forward, so it's an
			// error if somehow the transaction record has an earlier timestamp
			// than the transaction timestamp.
			reply.SetGoError(proto.NewTransactionStatusError(existTxn, fmt.Sprintf("timestamp regression: %+v", args.Txn.Timestamp)))
			return
		}
		// Use the persisted transaction record as final transaction.
		gogoproto.Merge(reply.Txn, existTxn)
	}

	// Take max of requested timestamp and possibly "pushed" txn
	// record timestamp as the final commit timestamp.
	if reply.Txn.Timestamp.Less(args.Timestamp) {
		reply.Txn.Timestamp = args.Timestamp
	}

	// Set transaction status to COMMITTED or ABORTED as per the
	// args.Commit parameter.
	if args.Commit {
		// If the isolation level is SERIALIZABLE, return a transaction
		// retry error if the commit timestamp isn't equal to the txn
		// timestamp.
		if args.Txn.Isolation == proto.SERIALIZABLE && !reply.Txn.Timestamp.Equal(args.Txn.Timestamp) {
			reply.SetGoError(proto.NewTransactionRetryError(reply.Txn))
			return
		}
		reply.Txn.Status = proto.COMMITTED
	} else {
		reply.Txn.Status = proto.ABORTED
	}

	// Persist the transaction record with updated status (& possibly timestmap).
	if err := engine.PutProto(r.engine, key, reply.Txn); err != nil {
		reply.SetGoError(err)
		return
	}
}