// 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()
}
if intentGroup != nil {
// Adding the intents even on error reduces the likelihood of dangling
// intents blocking concurrent writers for extended periods of time.
// See #3346.
ba.IntentSpanIterate(func(key, endKey roachpb.Key) {
addKeyRange(intentGroup, key, endKey)
})
if txnMeta == nil && intentGroup.Len() > 0 {
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.
if _, isEnding := ba.GetArg(roachpb.EndTransaction); pErr != nil || !isEnding {
log.Trace(ctx, "coordinator spawns")
txnMeta = &txnMetadata{
txn: *newTxn,
keys: intentGroup,
firstUpdateNanos: startNS,
lastUpdateNanos: tc.clock.PhysicalNow(),
timeoutDuration: tc.clientTimeout,
txnEnd: make(chan struct{}),
}
tc.txns[txnID] = txnMeta
if !tc.stopper.RunAsyncTask(func() {
tc.heartbeatLoop(ctx, txnID)
}) {
// The system is already draining and we can't start the
// heartbeat. We refuse new transactions for now because
// they're likely not going to have all intents committed.
// In principle, we can relax this as needed though.
tc.unregisterTxnLocked(txnID)
return roachpb.NewError(&roachpb.NodeUnavailableError{})
}
} else {
// If this was a successful one phase commit, update stats
// directly as they won't otherwise be updated on heartbeat
// loop shutdown.
etArgs, ok := br.Responses[len(br.Responses)-1].GetInner().(*roachpb.EndTransactionResponse)
tc.updateStats(tc.clock.PhysicalNow()-startNS, 0, newTxn.Status, ok && etArgs.OnePhaseCommit)
}
}
}
// Update our record of this transaction, even on error.
if txnMeta != nil {
txnMeta.txn = *newTxn
if !txnMeta.txn.Writing {
panic("tracking a non-writing txn")
}
txnMeta.setLastUpdate(tc.clock.PhysicalNow())
}
if pErr == nil {
// For successful transactional requests, always send the updated txn
// record back.
br.Txn = newTxn
}
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 {
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.
if _, isEnding := ba.GetArg(roachpb.EndTransaction); pErr != nil || !isEnding {
trace.Event("coordinator spawns")
txnMeta = &txnMetadata{
txn: *newTxn,
keys: cache.NewIntervalCache(cache.Config{Policy: cache.CacheNone}),
firstUpdateNanos: tc.clock.PhysicalNow(),
lastUpdateNanos: tc.clock.PhysicalNow(),
timeoutDuration: tc.clientTimeout,
txnEnd: make(chan struct{}),
}
tc.txns[id] = txnMeta
if !tc.stopper.RunAsyncTask(func() {
tc.heartbeatLoop(id)
}) {
// The system is already draining and we can't start the
// heartbeat. We refuse new transactions for now because
// they're likely not going to have all intents committed.
// In principle, we can relax this as needed though.
tc.unregisterTxnLocked(id)
return roachpb.NewError(&roachpb.NodeUnavailableError{})
}
}
}
}
// Update our record of this transaction, even on error.
if txnMeta != nil {
txnMeta.txn = *newTxn
if !txnMeta.txn.Writing {
panic("tracking a non-writing txn")
}
txnMeta.setLastUpdate(tc.clock.PhysicalNow())
// Adding the intents even on error reduces the likelyhood of dangling
// intents blocking concurrent writers for extended periods of time.
// See #3346.
for _, intent := range intents {
txnMeta.addKeyRange(intent.Key, intent.EndKey)
}
}
if pErr == nil {
// For successful transactional requests, always send the updated txn
// record back.
br.Txn = newTxn
}
return pErr
}()
}
// 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
// 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.
if _, isEnding := ba.GetArg(roachpb.EndTransaction); pErr != nil || !isEnding {
sp.LogEvent("coordinator spawns")
txnMeta = &txnMetadata{
txn: *newTxn,
keys: cache.NewIntervalCache(cache.Config{Policy: cache.CacheNone}),
firstUpdateNanos: tc.clock.PhysicalNow(),
lastUpdateNanos: tc.clock.PhysicalNow(),
timeoutDuration: tc.clientTimeout,
txnEnd: make(chan struct{}),
}
tc.txns[txnID] = txnMeta
if !tc.stopper.RunAsyncTask(func() {
tc.heartbeatLoop(txnID)
}) {
// The system is already draining and we can't start the
// heartbeat. We refuse new transactions for now because
// they're likely not going to have all intents committed.
// In principle, we can relax this as needed though.
tc.unregisterTxnLocked(txnID)
return roachpb.NewError(&roachpb.NodeUnavailableError{})
}
}
}
}
// Update our record of this transaction, even on error.
if txnMeta != nil {
txnMeta.txn = *newTxn
if !txnMeta.txn.Writing {
panic("tracking a non-writing txn")
}
txnMeta.setLastUpdate(tc.clock.PhysicalNow())
// Adding the intents even on error reduces the likelihood of dangling
// intents blocking concurrent writers for extended periods of time.
// See #3346.
for _, intent := range intents {
txnMeta.addKeyRange(intent.Key, intent.EndKey)
}
}
if pErr == nil {
// For successful transactional requests, always send the updated txn
// record back.
br.Txn = newTxn
}
return pErr
}