// TestTxnMultipleCoord checks that a coordinator uses the Writing flag to
// enforce that only one coordinator can be used for transactional writes.
func TestTxnMultipleCoord(t *testing.T) {
defer leaktest.AfterTest(t)()
s, sender := createTestDB(t)
defer s.Stop()
testCases := []struct {
args roachpb.Request
writing bool
ok bool
}{
{roachpb.NewGet(roachpb.Key("a")), true, false},
{roachpb.NewGet(roachpb.Key("a")), false, true},
{roachpb.NewPut(roachpb.Key("a"), roachpb.Value{}), false, false}, // transactional write before begin
{roachpb.NewPut(roachpb.Key("a"), roachpb.Value{}), true, false}, // must have switched coordinators
}
for i, tc := range testCases {
txn := roachpb.NewTransaction("test", roachpb.Key("a"), 1, enginepb.SERIALIZABLE,
s.Clock.Now(), s.Clock.MaxOffset().Nanoseconds())
txn.Writing = tc.writing
reply, pErr := client.SendWrappedWith(context.Background(), sender, roachpb.Header{
Txn: txn,
}, tc.args)
if pErr == nil != tc.ok {
t.Errorf("%d: %T (writing=%t): success_expected=%t, but got: %v",
i, tc.args, tc.writing, tc.ok, pErr)
}
if pErr != nil {
continue
}
txn = reply.Header().Txn
// The transaction should come back rw if it started rw or if we just
// wrote.
isWrite := roachpb.IsTransactionWrite(tc.args)
if (tc.writing || isWrite) != txn.Writing {
t.Errorf("%d: unexpected writing state: %s", i, txn)
}
if !isWrite {
continue
}
// Abort for clean shutdown.
if _, pErr := client.SendWrappedWith(context.Background(), sender, roachpb.Header{
Txn: txn,
}, &roachpb.EndTransactionRequest{
Commit: false,
}); pErr != nil {
t.Fatal(pErr)
}
}
}
// 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 len(ba.Requests) == 0 {
return errors.Errorf("empty batch with txn")
}
if ba.Txn.ID == nil {
// Create transaction without a key. The key is set when a begin
// transaction request is received.
// The initial timestamp may be communicated by a higher layer.
// If so, use that. Otherwise make up a new one.
timestamp := ba.Txn.OrigTimestamp
if timestamp == hlc.ZeroTimestamp {
timestamp = tc.clock.Now()
}
newTxn := roachpb.NewTransaction(ba.Txn.Name, nil, ba.UserPriority,
ba.Txn.Isolation, timestamp, 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 errors.Errorf("begin transaction requested twice in the same transaction: %s", ba.Txn)
}
haveBeginTxn = true
if ba.Txn.Key == nil {
ba.Txn.Key = bt.Key
}
}
if roachpb.IsTransactionWrite(args) && !haveBeginTxn && !ba.Txn.Writing {
return errors.Errorf("transactional write before begin transaction")
}
}
return nil
}
// send runs the specified calls synchronously in a single batch and
// returns any errors. If the transaction is read-only or has already
// been successfully committed or aborted, a potential trailing
// EndTransaction call is silently dropped, allowing the caller to
// always commit or clean-up explicitly even when that may not be
// required (or even erroneous). Returns (nil, nil) for an empty batch.
func (txn *Txn) send(ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
if txn.Proto.Status != roachpb.PENDING || txn.IsFinalized() {
return nil, roachpb.NewErrorf(
"attempting to use transaction with wrong status or finalized: %s", txn.Proto.Status)
}
// It doesn't make sense to use inconsistent reads in a transaction. However,
// we still need to accept it as a parameter for this to compile.
if ba.ReadConsistency != roachpb.CONSISTENT {
return nil, roachpb.NewErrorf("cannot use %s ReadConsistency in txn",
ba.ReadConsistency)
}
lastIndex := len(ba.Requests) - 1
if lastIndex < 0 {
return nil, nil
}
// firstWriteIndex is set to the index of the first command which is
// a transactional write. If != -1, this indicates an intention to
// write. This is in contrast to txn.Proto.Writing, which is set by
// the coordinator when the first intent has been created, and which
// lives for the life of the transaction.
firstWriteIndex := -1
var firstWriteKey roachpb.Key
for i, ru := range ba.Requests {
args := ru.GetInner()
if i < lastIndex {
if _, ok := args.(*roachpb.EndTransactionRequest); ok {
return nil, roachpb.NewErrorf("%s sent as non-terminal call", args.Method())
}
}
if roachpb.IsTransactionWrite(args) && firstWriteIndex == -1 {
firstWriteKey = args.Header().Key
firstWriteIndex = i
}
}
haveTxnWrite := firstWriteIndex != -1
endTxnRequest, haveEndTxn := ba.Requests[lastIndex].GetInner().(*roachpb.EndTransactionRequest)
needBeginTxn := !txn.Proto.Writing && haveTxnWrite
needEndTxn := txn.Proto.Writing || haveTxnWrite
elideEndTxn := haveEndTxn && !needEndTxn
// If we're not yet writing in this txn, but intend to, insert a
// begin transaction request before the first write command.
if needBeginTxn {
// If the transaction already has a key (we're in a restart), make
// sure we set the key in the begin transaction request to the original.
bt := &roachpb.BeginTransactionRequest{
Span: roachpb.Span{
Key: firstWriteKey,
},
}
if txn.Proto.Key != nil {
bt.Key = txn.Proto.Key
}
// Inject the new request before position firstWriteIndex, taking
// care to avoid unnecessary allocations.
oldRequests := ba.Requests
ba.Requests = make([]roachpb.RequestUnion, len(ba.Requests)+1)
copy(ba.Requests, oldRequests[:firstWriteIndex])
ba.Requests[firstWriteIndex].MustSetInner(bt)
copy(ba.Requests[firstWriteIndex+1:], oldRequests[firstWriteIndex:])
}
if elideEndTxn {
ba.Requests = ba.Requests[:lastIndex]
}
br, pErr := txn.sendInternal(ba)
if elideEndTxn && pErr == nil {
// Check that read only transactions do not violate their deadline. This can NOT
// happen since the txn deadline is normally updated when it is about to expire
// or expired. We will just keep the code for safety (see TestReacquireLeaseOnRestart).
if endTxnRequest.Deadline != nil {
if endTxnRequest.Deadline.Less(txn.Proto.Timestamp) {
return nil, roachpb.NewErrorWithTxn(roachpb.NewTransactionAbortedError(), &txn.Proto)
}
}
// This normally happens on the server and sent back in response
// headers, but this transaction was optimized away. The caller may
// still inspect the transaction struct, so we manually update it
// here to emulate a true transaction.
if endTxnRequest.Commit {
txn.Proto.Status = roachpb.COMMITTED
} else {
txn.Proto.Status = roachpb.ABORTED
}
txn.finalized = true
}
// If we inserted a begin transaction request, remove it here.
if needBeginTxn {
if br != nil && br.Responses != nil {
br.Responses = append(br.Responses[:firstWriteIndex], br.Responses[firstWriteIndex+1:]...)
}
// Handle case where inserted begin txn confused an indexed error.
if pErr != nil && pErr.Index != nil {
idx := pErr.Index.Index
if idx == int32(firstWriteIndex) {
// An error was encountered on begin txn; disallow the indexing.
pErr.Index = nil
} else if idx > int32(firstWriteIndex) {
// An error was encountered after begin txn; decrement index.
pErr.SetErrorIndex(idx - 1)
}
}
}
return br, pErr
}
// TestSender mocks out some of the txn coordinator sender's
// functionality. It responds to PutRequests using testPutResp.
func newTestSender(
pre, post func(roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error),
) SenderFunc {
txnID := uuid.MakeV4()
return func(_ context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
if ba.UserPriority == 0 {
ba.UserPriority = 1
}
if ba.Txn != nil && ba.Txn.ID == nil {
ba.Txn.Key = txnKey
ba.Txn.ID = &txnID
}
var br *roachpb.BatchResponse
var pErr *roachpb.Error
if pre != nil {
br, pErr = pre(ba)
} else {
br = ba.CreateReply()
}
if pErr != nil {
return nil, pErr
}
var writing bool
status := roachpb.PENDING
for i, req := range ba.Requests {
args := req.GetInner()
if _, ok := args.(*roachpb.PutRequest); ok {
testPutRespCopy := testPutResp
union := &br.Responses[i] // avoid operating on copy
union.MustSetInner(&testPutRespCopy)
}
if roachpb.IsTransactionWrite(args) {
writing = true
}
}
if args, ok := ba.GetArg(roachpb.EndTransaction); ok {
et := args.(*roachpb.EndTransactionRequest)
writing = true
if et.Commit {
status = roachpb.COMMITTED
} else {
status = roachpb.ABORTED
}
}
if ba.Txn != nil {
txnClone := ba.Txn.Clone()
br.Txn = &txnClone
if pErr == nil {
br.Txn.Writing = writing
br.Txn.Status = status
}
}
if post != nil {
br, pErr = post(ba)
}
return br, pErr
}
}