// maybeBeginTxn begins a new transaction if a txn has been specified
// in the request but has a nil ID. The new transaction is initialized
// using the name and isolation in the otherwise uninitialized txn.
// The Priority, if non-zero is used as a minimum.
func (tc *TxnCoordSender) maybeBeginTxn(ba *roachpb.BatchRequest) {
if ba.Txn == nil {
return
}
if len(ba.Requests) == 0 {
panic("empty batch with txn")
}
if len(ba.Txn.ID) == 0 {
// TODO(tschottdorf): should really choose the first txn write here.
firstKey := ba.Requests[0].GetInner().Header().Key
newTxn := roachpb.NewTransaction(ba.Txn.Name, keys.KeyAddress(firstKey), ba.GetUserPriority(),
ba.Txn.Isolation, tc.clock.Now(), tc.clock.MaxOffset().Nanoseconds())
// Use existing priority as a minimum. This is used on transaction
// aborts to ratchet priority when creating successor transaction.
if newTxn.Priority < ba.Txn.Priority {
newTxn.Priority = ba.Txn.Priority
}
ba.Txn = newTxn
}
}
// maybeBeginTxn begins a new transaction if a txn has been specified
// in the request but has a nil ID. The new transaction is initialized
// using the name and isolation in the otherwise uninitialized txn.
// The Priority, if non-zero is used as a minimum.
//
// No transactional writes are allowed unless preceded by a begin
// transaction request within the same batch. The exception is if the
// transaction is already in state txn.Writing=true.
func (tc *TxnCoordSender) maybeBeginTxn(ba *roachpb.BatchRequest) error {
if ba.Txn == nil {
return nil
}
if len(ba.Requests) == 0 {
return util.Errorf("empty batch with txn")
}
if len(ba.Txn.ID) == 0 {
// Create transaction without a key. The key is set when a begin
// transaction request is received.
newTxn := roachpb.NewTransaction(ba.Txn.Name, nil, ba.GetUserPriority(),
ba.Txn.Isolation, tc.clock.Now(), tc.clock.MaxOffset().Nanoseconds())
// Use existing priority as a minimum. This is used on transaction
// aborts to ratchet priority when creating successor transaction.
if newTxn.Priority < ba.Txn.Priority {
newTxn.Priority = ba.Txn.Priority
}
ba.Txn = newTxn
}
// Check for a begin transaction to set txn key based on the key of
// the first transactional write. Also enforce that no transactional
// writes occur before a begin transaction.
var haveBeginTxn bool
for _, req := range ba.Requests {
args := req.GetInner()
if bt, ok := args.(*roachpb.BeginTransactionRequest); ok {
if haveBeginTxn || ba.Txn.Writing {
return util.Errorf("begin transaction requested twice in the same transaction")
}
haveBeginTxn = true
ba.Txn.Key = bt.Key
}
if roachpb.IsTransactionWrite(args) && !haveBeginTxn && !ba.Txn.Writing {
return util.Errorf("transactional write before begin transaction")
}
}
return nil
}
// TODO(tschottdorf): this method is somewhat awkward but unless we want to
// give this error back to the client, our options are limited. We'll have to
// run the whole thing for them, or any restart will still end up at the client
// which will not be prepared to be handed a Txn.
func (tc *TxnCoordSender) resendWithTxn(ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
// Run a one-off transaction with that single command.
if log.V(1) {
log.Infof("%s: auto-wrapping in txn and re-executing: ", ba)
}
tmpDB := client.NewDBWithPriority(tc, ba.GetUserPriority())
var br *roachpb.BatchResponse
err := tmpDB.Txn(func(txn *client.Txn) error {
txn.SetDebugName("auto-wrap", 0)
b := &client.Batch{}
for _, arg := range ba.Requests {
req := arg.GetInner()
b.InternalAddRequest(req)
}
var err error
br, err = txn.CommitInBatchWithResponse(b)
return err
})
if err != nil {
return nil, roachpb.NewError(err)
}
br.Txn = nil // hide the evidence
return br, nil
}
// 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.GetTxn())
// TODO(tamird): remove this clone. It's currently needed to avoid race conditions.
pErr = proto.Clone(pErr).(*roachpb.Error)
err := pErr.GoError()
// 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 := err.(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, t.Txn)
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(&t.Txn)
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.GetUserPriority(), newTxn.Priority, newTxn.Timestamp)
t.Txn = *newTxn
case *roachpb.TransactionAbortedError:
trace.SetError()
newTxn.Update(&t.Txn)
// Increase timestamp if applicable.
newTxn.Timestamp.Forward(t.Txn.Timestamp)
newTxn.Priority = t.Txn.Priority
t.Txn = *newTxn
// Clean up the freshly aborted transaction in defer(), avoiding a
// race with the state update below.
defer tc.cleanupTxn(trace, t.Txn)
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.GetUserPriority(), t.PusheeTxn.Priority-1, newTxn.Timestamp)
t.Txn = newTxn
case *roachpb.TransactionRetryError:
newTxn.Update(&t.Txn)
newTxn.Restart(ba.GetUserPriority(), t.Txn.Priority, newTxn.Timestamp)
t.Txn = *newTxn
case roachpb.TransactionRestartError:
// Assertion: The above cases should exhaust all ErrorDetails which
// carry a Transaction.
if pErr.Detail != nil {
panic(fmt.Sprintf("unhandled TransactionRestartError %T", err))
}
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).
// consider re-using those.
if intents := ba.GetIntents(); len(intents) > 0 && (err == nil || newTxn.Writing) {
if txnMeta == nil {
if !newTxn.Writing {
panic("txn with intents marked as non-writing")
}
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 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); err != nil || !isEnding {
trace.Event("coordinator spawns")
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{})
}
}
}
for _, intent := range intents {
txnMeta.addKeyRange(intent.Key, intent.EndKey)
}
}
// 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 err == 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.GetTxn())
err := pErr.GoError()
switch t := err.(type) {
case nil:
newTxn.Update(br.GetTxn())
// 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, t.Txn)
case *roachpb.OpRequiresTxnError:
// TODO(tschottdorf): range-spanning autowrap currently broken.
panic("TODO(tschottdorf): disabled")
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.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.GetUserPriority(), newTxn.Priority, newTxn.Timestamp)
t.Txn = *newTxn
case *roachpb.TransactionAbortedError:
// Increase timestamp if applicable.
newTxn.Timestamp.Forward(t.Txn.Timestamp)
newTxn.Priority = t.Txn.Priority
t.Txn = *newTxn
// Clean up the freshly aborted transaction in defer(), avoiding a
// race with the state update below.
defer tc.cleanupTxn(trace, t.Txn)
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.GetUserPriority(), t.PusheeTxn.Priority-1, newTxn.Timestamp)
t.Txn = newTxn
case *roachpb.TransactionRetryError:
// Increase timestamp if applicable.
newTxn.Timestamp.Forward(t.Txn.Timestamp)
newTxn.Restart(ba.GetUserPriority(), t.Txn.Priority, newTxn.Timestamp)
t.Txn = *newTxn
case roachpb.TransactionRestartError:
// Assertion: The above cases should exhaust all ErrorDetails which
// carry a Transaction.
if pErr.Detail != nil {
panic(fmt.Sprintf("unhandled TransactionRestartError %T", err))
}
}
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
// TODO(tschottdorf): already computed the intents prior to sending,
// consider re-using those.
if intents := ba.GetIntents(); len(intents) > 0 && err == nil {
if txnMeta == nil {
newTxn.Writing = true
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 the transaction is already over, there's no point in
// launching a one-off coordinator which will shut down right
// away.
if _, isEnding := ba.GetArg(roachpb.EndTransaction); !isEnding {
trace.Event("coordinator spawns")
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{})
}
}
}
for _, intent := range intents {
txnMeta.addKeyRange(intent.Key, intent.EndKey)
}
}
// Update our record of this transaction, even on error.
if txnMeta != nil {
txnMeta.txn.Update(newTxn) // better to replace after #2300
if !txnMeta.txn.Writing {
panic("tracking a non-writing txn")
}
txnMeta.setLastUpdate(tc.clock.PhysicalNow())
}
if err == nil {
// For successful transactional requests, always send the updated txn
// record back.
if br.Txn == nil {
br.Txn = &roachpb.Transaction{}
}
*br.Txn = *newTxn
}
return pErr
}()
}