Golang Error.GetTxn方法代碼示例

// Exec executes fn in the context of a distributed transaction.
// Execution is controlled by opt (see comments in TxnExecOptions).
//
// opt is passed to fn, and it's valid for fn to modify opt as it sees
// fit during each execution attempt.
//
// It's valid for txn to be nil (meaning the txn has already aborted) if fn
// can handle that. This is useful for continuing transactions that have been
// aborted because of an error in a previous batch of statements in the hope
// that a ROLLBACK will reset the state. Neither opt.AutoRetry not opt.AutoCommit
// can be set in this case.
//
// If an error is returned, the txn has been aborted.
func (txn *Txn) Exec(
	opt TxnExecOptions,
	fn func(txn *Txn, opt *TxnExecOptions) *roachpb.Error) *roachpb.Error {
	// Run fn in a retry loop until we encounter a success or
	// error condition this loop isn't capable of handling.
	var pErr *roachpb.Error
	var retryOptions retry.Options
	if txn == nil && (opt.AutoRetry || opt.AutoCommit) {
		panic("asked to retry  or commit a txn that is already aborted")
	}
	if opt.AutoRetry {
		retryOptions = txn.db.txnRetryOptions
	}
RetryLoop:
	for r := retry.Start(retryOptions); r.Next(); {
		pErr = fn(txn, &opt)
		if (pErr == nil) && opt.AutoCommit && (txn.Proto.Status == roachpb.PENDING) {
			// fn succeeded, but didn't commit.
			pErr = txn.commit(nil)
		}

		if pErr == nil {
			break
		}

		// Make sure the txn record that pErr carries is for this txn.
		// We check only when txn.Proto.ID has been initialized after an initial successful send.
		if pErr.GetTxn() != nil && txn.Proto.ID != nil {
			if errTxn := pErr.GetTxn(); !errTxn.Equal(&txn.Proto) {
				return roachpb.NewErrorf("mismatching transaction record in the error:\n%s\nv.s.\n%s",
					errTxn, txn.Proto)
			}
		}

		if !opt.AutoRetry {
			break RetryLoop
		}
		switch pErr.TransactionRestart {
		case roachpb.TransactionRestart_IMMEDIATE:
			r.Reset()
		case roachpb.TransactionRestart_BACKOFF:
		default:
			break RetryLoop
		}
		if log.V(2) {
			log.Infof("automatically retrying transaction: %s because of error: %s",
				txn.DebugName(), pErr)
		}
	}
	if txn != nil {
		// TODO(andrei): don't do Cleanup() on retriable errors here.
		// Let the sql executor do it.
		txn.Cleanup(pErr)
	}
	if pErr != nil {
		pErr.StripErrorTransaction()
	}
	return pErr
}

func (txn *Txn) exec(retryable func(txn *Txn) *roachpb.Error) *roachpb.Error {
	// Run retryable in a retry loop until we encounter a success or
	// error condition this loop isn't capable of handling.
	var pErr *roachpb.Error
	for r := retry.Start(txn.db.txnRetryOptions); r.Next(); {
		pErr = retryable(txn)
		if pErr == nil && txn.Proto.Status == roachpb.PENDING {
			// retryable succeeded, but didn't commit.
			pErr = txn.commit(nil)
		}

		if pErr != nil {
			// Make sure the txn record that pErr carries is for this txn.
			// We check only when txn.Proto.ID has been initialized after an initial successful send.
			if pErr.GetTxn() != nil && txn.Proto.ID != nil {
				if errTxn := pErr.GetTxn(); !errTxn.Equal(&txn.Proto) {
					return roachpb.NewErrorf("mismatching transaction record in the error:\n%s\nv.s.\n%s",
						errTxn, txn.Proto)
				}
			}

			switch pErr.TransactionRestart {
			case roachpb.TransactionRestart_IMMEDIATE:
				if log.V(2) {
					log.Warning(pErr)
				}
				r.Reset()
				continue
			case roachpb.TransactionRestart_BACKOFF:
				if log.V(2) {
					log.Warning(pErr)
				}
				continue
			}
			// By default, fall through and break.
		}
		break
	}
	txn.Cleanup(pErr)
	return pErr
}

// updateState updates the transaction state in both the success and
// error cases, applying those updates to the corresponding txnMeta
// object when adequate. It also updates certain errors with the
// updated transaction for use by client restarts.
func (tc *TxnCoordSender) updateState(
	startNS int64, ctx context.Context, ba roachpb.BatchRequest,
	br *roachpb.BatchResponse, pErr *roachpb.Error) *roachpb.Error {
	newTxn := &roachpb.Transaction{}
	newTxn.Update(ba.Txn)
	if pErr == nil {
		newTxn.Update(br.Txn)
	} else {
		newTxn.Update(pErr.GetTxn())
	}

	switch t := pErr.GetDetail().(type) {
	case *roachpb.TransactionStatusError:
		// Likely already committed or more obscure errors such as epoch or
		// timestamp regressions; consider txn dead.
		defer tc.cleanupTxn(ctx, *pErr.GetTxn())
	case *roachpb.OpRequiresTxnError:
		panic("OpRequiresTxnError must not happen at this level")
	case *roachpb.ReadWithinUncertaintyIntervalError:
		// If the reader encountered a newer write within the uncertainty
		// interval, we advance the txn's timestamp just past the last observed
		// timestamp from the node.
		restartTS, ok := newTxn.GetObservedTimestamp(pErr.OriginNode)
		if !ok {
			pErr = roachpb.NewError(util.Errorf("no observed timestamp for node %d found on uncertainty restart", pErr.OriginNode))
		} else {
			newTxn.Timestamp.Forward(restartTS)
			newTxn.Restart(ba.UserPriority, newTxn.Priority, newTxn.Timestamp)
		}
	case *roachpb.TransactionAbortedError:
		// Increase timestamp if applicable.
		newTxn.Timestamp.Forward(pErr.GetTxn().Timestamp)
		newTxn.Priority = pErr.GetTxn().Priority
		// Clean up the freshly aborted transaction in defer(), avoiding a
		// race with the state update below.
		defer tc.cleanupTxn(ctx, *newTxn)
	case *roachpb.TransactionPushError:
		// Increase timestamp if applicable, ensuring that we're
		// just ahead of the pushee.
		newTxn.Timestamp.Forward(t.PusheeTxn.Timestamp)
		newTxn.Restart(ba.UserPriority, t.PusheeTxn.Priority-1, newTxn.Timestamp)
	case *roachpb.TransactionRetryError:
		// Increase timestamp so on restart, we're ahead of any timestamp
		// cache entries or newer versions which caused the restart.
		newTxn.Restart(ba.UserPriority, pErr.GetTxn().Priority, newTxn.Timestamp)
	case *roachpb.WriteTooOldError:
		newTxn.Restart(ba.UserPriority, newTxn.Priority, t.ActualTimestamp)
	case nil:
		// Nothing to do here, avoid the default case.
	default:
		if pErr.GetTxn() != nil {
			if pErr.CanRetry() {
				panic("Retryable internal error must not happen at this level")
			} else {
				// Do not clean up the transaction here since the client might still
				// want to continue the transaction. For example, a client might
				// continue its transaction after receiving ConditionFailedError, which
				// can come from a unique index violation.
			}
		}
	}

	if pErr != nil && pErr.GetTxn() != nil {
		// Avoid changing existing errors because sometimes they escape into
		// goroutines and then there are races. Fairly sure there isn't one
		// here, but better safe than sorry.
		pErrShallow := *pErr
		pErrShallow.SetTxn(newTxn)
		pErr = &pErrShallow
	}

	if newTxn.ID == nil {
		return pErr
	}
	txnID := *newTxn.ID
	tc.Lock()
	defer tc.Unlock()
	txnMeta := tc.txns[txnID]
	// For successful transactional requests, keep the written intents and
	// the updated transaction record to be sent along with the reply.
	// The transaction metadata is created with the first writing operation.
	// A tricky edge case is that of a transaction which "fails" on the
	// first writing request, but actually manages to write some intents
	// (for example, due to being multi-range). In this case, there will
	// be an error, but the transaction will be marked as Writing and the
	// coordinator must track the state, for the client's retry will be
	// performed with a Writing transaction which the coordinator rejects
	// unless it is tracking it (on top of it making sense to track it;
	// after all, it **has** laid down intents and only the coordinator
	// can augment a potential EndTransaction call). See #3303.
	var intentGroup interval.RangeGroup
	if txnMeta != nil {
		intentGroup = txnMeta.keys
	} else if pErr == nil || newTxn.Writing {
		intentGroup = interval.NewRangeTree()
	}
//.........這裏部分代碼省略.........

// updateState updates the transaction state in both the success and
// error cases, applying those updates to the corresponding txnMeta
// object when adequate. It also updates certain errors with the
// updated transaction for use by client restarts.
func (tc *TxnCoordSender) updateState(ctx context.Context, ba roachpb.BatchRequest, br *roachpb.BatchResponse, pErr *roachpb.Error) *roachpb.Error {
	trace := tracer.FromCtx(ctx)
	newTxn := &roachpb.Transaction{}
	newTxn.Update(ba.Txn)
	// TODO(tamird): remove this clone. It's currently needed to avoid race conditions.
	pErr = proto.Clone(pErr).(*roachpb.Error)
	// TODO(bdarnell): We're writing to errors here (and where using ErrorWithIndex);
	// since there's no concept of ownership copy-on-write is always preferable.
	switch t := pErr.GetDetail().(type) {
	case nil:
		newTxn.Update(br.Txn)
		// Move txn timestamp forward to response timestamp if applicable.
		// TODO(tschottdorf): see (*Replica).executeBatch and comments within.
		// Looks like this isn't necessary any more, nor did it prevent a bug
		// referenced in a TODO there.
		newTxn.Timestamp.Forward(br.Timestamp)
	case *roachpb.TransactionStatusError:
		// Likely already committed or more obscure errors such as epoch or
		// timestamp regressions; consider txn dead.
		defer tc.cleanupTxn(trace, *pErr.GetTxn())
	case *roachpb.OpRequiresTxnError:
		panic("OpRequiresTxnError must not happen at this level")
	case *roachpb.ReadWithinUncertaintyIntervalError:
		// Mark the host as certain. See the protobuf comment for
		// Transaction.CertainNodes for details.
		if t.NodeID == 0 {
			panic("no replica set in header on uncertainty restart")
		}
		newTxn.Update(pErr.GetTxn())
		newTxn.CertainNodes.Add(t.NodeID)
		// If the reader encountered a newer write within the uncertainty
		// interval, move the timestamp forward, just past that write or
		// up to MaxTimestamp, whichever comes first.
		candidateTS := newTxn.MaxTimestamp
		candidateTS.Backward(t.ExistingTimestamp.Add(0, 1))
		newTxn.Timestamp.Forward(candidateTS)
		newTxn.Restart(ba.UserPriority, newTxn.Priority, newTxn.Timestamp)
		pErr.SetTxn(newTxn)
	case *roachpb.TransactionAbortedError:
		trace.SetError()
		newTxn.Update(pErr.GetTxn())
		// Increase timestamp if applicable.
		newTxn.Timestamp.Forward(pErr.GetTxn().Timestamp)
		newTxn.Priority = pErr.GetTxn().Priority
		pErr.SetTxn(newTxn)
		// Clean up the freshly aborted transaction in defer(), avoiding a
		// race with the state update below.
		defer tc.cleanupTxn(trace, *pErr.GetTxn())
	case *roachpb.TransactionPushError:
		newTxn.Update(t.Txn)
		// Increase timestamp if applicable, ensuring that we're
		// just ahead of the pushee.
		newTxn.Timestamp.Forward(t.PusheeTxn.Timestamp.Add(0, 1))
		newTxn.Restart(ba.UserPriority, t.PusheeTxn.Priority-1, newTxn.Timestamp)
		t.Txn = newTxn
		pErr.SetTxn(newTxn)
	case *roachpb.TransactionRetryError:
		newTxn.Update(pErr.GetTxn())
		newTxn.Restart(ba.UserPriority, pErr.GetTxn().Priority, newTxn.Timestamp)
		pErr.SetTxn(newTxn)
	default:
		trace.SetError()
	}

	return func() *roachpb.Error {
		if len(newTxn.ID) <= 0 {
			return pErr
		}
		id := string(newTxn.ID)
		tc.Lock()
		defer tc.Unlock()
		txnMeta := tc.txns[id]
		// For successful transactional requests, keep the written intents and
		// the updated transaction record to be sent along with the reply.
		// The transaction metadata is created with the first writing operation.
		// A tricky edge case is that of a transaction which "fails" on the
		// first writing request, but actually manages to write some intents
		// (for example, due to being multi-range). In this case, there will
		// be an error, but the transaction will be marked as Writing and the
		// coordinator must track the state, for the client's retry will be
		// performed with a Writing transaction which the coordinator rejects
		// unless it is tracking it (on top of it making sense to track it;
		// after all, it **has** laid down intents and only the coordinator
		// can augment a potential EndTransaction call). See #3303.
		intents := ba.GetIntentSpans()
		if len(intents) > 0 && (pErr == nil || newTxn.Writing) {
			if txnMeta == nil {
				if !newTxn.Writing {
					panic("txn with intents marked as non-writing")
				}
				// If the transaction is already over, there's no point in
				// launching a one-off coordinator which will shut down right
				// away. If we ended up here with an error, we'll always start
				// the coordinator - the transaction has laid down intents, so
				// we expect it to be committed/aborted at some point in the
				// future.
//.........這裏部分代碼省略.........

// Exec executes fn in the context of a distributed transaction.
// Execution is controlled by opt (see comments in TxnExecOptions).
//
// opt is passed to fn, and it's valid for fn to modify opt as it sees
// fit during each execution attempt.
//
// It's valid for txn to be nil (meaning the txn has already aborted) if fn
// can handle that. This is useful for continuing transactions that have been
// aborted because of an error in a previous batch of statements in the hope
// that a ROLLBACK will reset the state. Neither opt.AutoRetry not opt.AutoCommit
// can be set in this case.
//
// When this method returns, txn might be in any state; Exec does not attempt
// to clean up the transaction before returning an error. In case of
// TransactionAbortedError, txn is reset to a fresh transaction, ready to be
// used.
//
// TODO(andrei): Make Exec() return error; make fn return an error + a retriable
// bit. There's no reason to propagate roachpb.Error (protos) above this point.
func (txn *Txn) Exec(
	opt TxnExecOptions,
	fn func(txn *Txn, opt *TxnExecOptions) *roachpb.Error) *roachpb.Error {
	// Run fn in a retry loop until we encounter a success or
	// error condition this loop isn't capable of handling.
	var pErr *roachpb.Error
	var retryOptions retry.Options
	if txn == nil && (opt.AutoRetry || opt.AutoCommit) {
		panic("asked to retry or commit a txn that is already aborted")
	}

	if opt.AutoRetry {
		retryOptions = txn.db.txnRetryOptions
	}
RetryLoop:
	for r := retry.Start(retryOptions); r.Next(); {
		if txn != nil {
			// If we're looking at a brand new transaction, then communicate
			// what should be used as initial timestamp for the KV txn created
			// by TxnCoordSender.
			if txn.Proto.OrigTimestamp == roachpb.ZeroTimestamp {
				txn.Proto.OrigTimestamp = opt.MinInitialTimestamp
			}
		}

		pErr = fn(txn, &opt)
		if txn != nil {
			txn.retrying = true
			defer func() {
				txn.retrying = false
			}()
		}
		if (pErr == nil) && opt.AutoCommit && (txn.Proto.Status == roachpb.PENDING) {
			// fn succeeded, but didn't commit.
			pErr = txn.Commit()
		}

		if pErr == nil {
			break
		}

		// Make sure the txn record that pErr carries is for this txn.
		// We check only when txn.Proto.ID has been initialized after an initial successful send.
		if pErr.GetTxn() != nil && txn.Proto.ID != nil {
			if errTxn := pErr.GetTxn(); !errTxn.Equal(&txn.Proto) {
				return roachpb.NewErrorf("mismatching transaction record in the error:\n%s\nv.s.\n%s",
					errTxn, txn.Proto)
			}
		}

		if !opt.AutoRetry {
			break RetryLoop
		}
		switch pErr.TransactionRestart {
		case roachpb.TransactionRestart_IMMEDIATE:
			r.Reset()
		case roachpb.TransactionRestart_BACKOFF:
		default:
			break RetryLoop
		}
		if log.V(2) {
			log.Infof("automatically retrying transaction: %s because of error: %s",
				txn.DebugName(), pErr)
		}
	}

	if pErr != nil {
		pErr.StripErrorTransaction()
	}
	return pErr
}

// updateState updates the transaction state in both the success and
// error cases, applying those updates to the corresponding txnMeta
// object when adequate. It also updates certain errors with the
// updated transaction for use by client restarts.
func (tc *TxnCoordSender) updateState(ctx context.Context, ba roachpb.BatchRequest, br *roachpb.BatchResponse, pErr *roachpb.Error) *roachpb.Error {
	sp, cleanupSp := tracing.SpanFromContext(opTxnCoordSender, tc.tracer, ctx)
	defer cleanupSp()

	newTxn := &roachpb.Transaction{}
	newTxn.Update(ba.Txn)
	if pErr == nil {
		newTxn.Update(br.Txn)
	} else {
		newTxn.Update(pErr.GetTxn())
	}

	// If the request was successful but we're in a transaction which needs to
	// restart but doesn't know it yet, let it restart now (as opposed to
	// waiting until EndTransaction).
	if pErr == nil && newTxn.Isolation == roachpb.SERIALIZABLE &&
		!newTxn.OrigTimestamp.Equal(newTxn.Timestamp) {
		pErr = roachpb.NewErrorWithTxn(roachpb.NewTransactionRetryError(), br.Txn)
		br = nil
	}

	switch t := pErr.GetDetail().(type) {
	case nil:
		// Move txn timestamp forward to response timestamp if applicable.
		// TODO(tschottdorf): see (*Replica).executeBatch and comments within.
		// Looks like this isn't necessary any more, nor did it prevent a bug
		// referenced in a TODO there.
		newTxn.Timestamp.Forward(br.Timestamp)
	case *roachpb.TransactionStatusError:
		// Likely already committed or more obscure errors such as epoch or
		// timestamp regressions; consider txn dead.
		defer tc.cleanupTxn(sp, *pErr.GetTxn())
	case *roachpb.OpRequiresTxnError:
		panic("OpRequiresTxnError must not happen at this level")
	case *roachpb.ReadWithinUncertaintyIntervalError:
		// If the reader encountered a newer write within the uncertainty
		// interval, we advance the txn's timestamp just past the last observed
		// timestamp from the node.
		restartTS, ok := newTxn.GetObservedTimestamp(pErr.OriginNode)
		if !ok {
			pErr = roachpb.NewError(util.Errorf("no observed timestamp for node %d found on uncertainty restart", pErr.OriginNode))
		} else {
			newTxn.Timestamp.Forward(restartTS)
			newTxn.Restart(ba.UserPriority, newTxn.Priority, newTxn.Timestamp)
		}
	case *roachpb.TransactionAbortedError:
		// Increase timestamp if applicable.
		newTxn.Timestamp.Forward(pErr.GetTxn().Timestamp)
		newTxn.Priority = pErr.GetTxn().Priority
		// Clean up the freshly aborted transaction in defer(), avoiding a
		// race with the state update below.
		defer tc.cleanupTxn(sp, *newTxn)
	case *roachpb.TransactionPushError:
		// Increase timestamp if applicable, ensuring that we're
		// just ahead of the pushee.
		newTxn.Timestamp.Forward(t.PusheeTxn.Timestamp.Add(0, 1))
		newTxn.Restart(ba.UserPriority, t.PusheeTxn.Priority-1, newTxn.Timestamp)
	case *roachpb.TransactionRetryError:
		newTxn.Restart(ba.UserPriority, pErr.GetTxn().Priority, newTxn.Timestamp)
	default:
		if pErr.GetTxn() != nil {
			if pErr.CanRetry() {
				panic("Retryable internal error must not happen at this level")
			} else {
				// Do not clean up the transaction here since the client might still
				// want to continue the transaction. For example, a client might
				// continue its transaction after receiving ConditionFailedError, which
				// can come from a unique index violation.
			}
		}
	}

	if pErr != nil && pErr.GetTxn() != nil {
		// Avoid changing existing errors because sometimes they escape into
		// goroutines and then there are races. Fairly sure there isn't one
		// here, but better safe than sorry.
		pErrShallow := *pErr
		pErrShallow.SetTxn(newTxn)
		pErr = &pErrShallow
	}

	if newTxn.ID == nil {
		return pErr
	}
	txnID := *newTxn.ID
	tc.Lock()
	defer tc.Unlock()
	txnMeta := tc.txns[txnID]
	// For successful transactional requests, keep the written intents and
	// the updated transaction record to be sent along with the reply.
	// The transaction metadata is created with the first writing operation.
	// A tricky edge case is that of a transaction which "fails" on the
	// first writing request, but actually manages to write some intents
	// (for example, due to being multi-range). In this case, there will
	// be an error, but the transaction will be marked as Writing and the
	// coordinator must track the state, for the client's retry will be
//.........這裏部分代碼省略.........