// We don't have a finalizer (~TransactionScope) because all it would be able to do is try to
// operate on other managed objects (the transaction), which is not safe to do because they may
// already have been finalized.
public void Dispose()
{
bool successful = false;
TransactionsEtwProvider etwLog = TransactionsEtwProvider.Log;
if (etwLog.IsEnabled())
{
etwLog.MethodEnter(TraceSourceType.TraceSourceBase, this);
}
if (_disposed)
{
if (etwLog.IsEnabled())
{
etwLog.MethodExit(TraceSourceType.TraceSourceBase, this);
}
return;
}
// Dispose for a scope can only be called on the thread where the scope was created.
if ((_scopeThread != Thread.CurrentThread) && !AsyncFlowEnabled)
{
if (etwLog.IsEnabled())
{
etwLog.InvalidOperation("TransactionScope", "InvalidScopeThread");
}
throw new InvalidOperationException(SR.InvalidScopeThread);
}
Exception exToThrow = null;
try
{
// Single threaded from this point
_disposed = true;
// First, lets pop the "stack" of TransactionScopes and dispose each one that is above us in
// the stack, making sure they are NOT consistent before disposing them.
// Optimize the first lookup by getting both the actual current scope and actual current
// transaction at the same time.
TransactionScope actualCurrentScope = _threadContextData.CurrentScope;
Transaction current = Transaction.FastGetTransaction(actualCurrentScope, _threadContextData, out Transaction contextTransaction);
if (!Equals(actualCurrentScope))
{
// Ok this is bad. But just how bad is it. The worst case scenario is that someone is
// poping scopes out of order and has placed a new transaction in the top level scope.
// Check for that now.
if (actualCurrentScope == null)
{
// Something must have gone wrong trying to clean up a bad scope
// stack previously.
// Make a best effort to abort the active transaction.
Transaction rollbackTransaction = _committableTransaction;
if (rollbackTransaction == null)
{
rollbackTransaction = _dependentTransaction;
}
Debug.Assert(rollbackTransaction != null);
rollbackTransaction.Rollback();
successful = true;
throw TransactionException.CreateInvalidOperationException(
TraceSourceType.TraceSourceBase, SR.TransactionScopeInvalidNesting, null, rollbackTransaction.DistributedTxId);
}
// Verify that expectedCurrent is the same as the "current" current if we the interopOption value is None.
else if (EnterpriseServicesInteropOption.None == actualCurrentScope._interopOption)
{
if (((null != actualCurrentScope._expectedCurrent) && (!actualCurrentScope._expectedCurrent.Equals(current)))
||
((null != current) && (null == actualCurrentScope._expectedCurrent))
)
{
TransactionTraceIdentifier myId;
TransactionTraceIdentifier currentId;
if (null == current)
{
currentId = TransactionTraceIdentifier.Empty;
}
else
{
currentId = current.TransactionTraceId;
}
if (null == _expectedCurrent)
{
myId = TransactionTraceIdentifier.Empty;
}
else
{
myId = _expectedCurrent.TransactionTraceId;
}
if (etwLog.IsEnabled())
{
etwLog.TransactionScopeCurrentChanged(currentId, myId);
}
exToThrow = TransactionException.CreateInvalidOperationException(TraceSourceType.TraceSourceBase, SR.TransactionScopeIncorrectCurrent, null,
current == null ? Guid.Empty : current.DistributedTxId);
// If there is a current transaction, abort it.
if (null != current)
{
try
{
current.Rollback();
}
catch (TransactionException)
{
// we are already going to throw and exception, so just ignore this one.
}
catch (ObjectDisposedException)
{
// Dito
}
}
}
}
// Now fix up the scopes
while (!Equals(actualCurrentScope))
{
if (null == exToThrow)
{
exToThrow = TransactionException.CreateInvalidOperationException(TraceSourceType.TraceSourceBase, SR.TransactionScopeInvalidNesting, null,
current == null ? Guid.Empty : current.DistributedTxId);
}
if (null == actualCurrentScope._expectedCurrent)
{
if (etwLog.IsEnabled())
{
etwLog.TransactionScopeNestedIncorrectly(TransactionTraceIdentifier.Empty);
}
}
else
{
if (etwLog.IsEnabled())
{
etwLog.TransactionScopeNestedIncorrectly(actualCurrentScope._expectedCurrent.TransactionTraceId);
}
}
actualCurrentScope._complete = false;
try
{
actualCurrentScope.InternalDispose();
}
catch (TransactionException)
{
// we are already going to throw an exception, so just ignore this one.
}
actualCurrentScope = _threadContextData.CurrentScope;
// We want to fail this scope, too, because work may have been done in one of these other
// nested scopes that really should have been done in my scope.
_complete = false;
}
}
else
{
// Verify that expectedCurrent is the same as the "current" current if we the interopOption value is None.
// If we got here, actualCurrentScope is the same as "this".
if (EnterpriseServicesInteropOption.None == _interopOption)
{
if (((null != _expectedCurrent) && (!_expectedCurrent.Equals(current))) ||
((null != current) && (null == _expectedCurrent))
)
{
TransactionTraceIdentifier myId;
TransactionTraceIdentifier currentId;
if (null == current)
{
currentId = TransactionTraceIdentifier.Empty;
}
else
{
currentId = current.TransactionTraceId;
}
if (null == _expectedCurrent)
{
myId = TransactionTraceIdentifier.Empty;
}
else
{
myId = _expectedCurrent.TransactionTraceId;
}
if (etwLog.IsEnabled())
{
etwLog.TransactionScopeCurrentChanged(currentId, myId);
}
if (null == exToThrow)
{
exToThrow = TransactionException.CreateInvalidOperationException(TraceSourceType.TraceSourceBase, SR.TransactionScopeIncorrectCurrent, null,
current == null ? Guid.Empty : current.DistributedTxId);
}
// If there is a current transaction, abort it.
if (null != current)
{
try
{
current.Rollback();
}
catch (TransactionException)
{
// we are already going to throw and exception, so just ignore this one.
}
catch (ObjectDisposedException)
{
// Dito
}
}
// Set consistent to false so that the subsequent call to
// InternalDispose below will rollback this.expectedCurrent.
_complete = false;
}
}
}
successful = true;
}
finally
{
if (!successful)
{
PopScope();
}
}
// No try..catch here. Just let any exception thrown by InternalDispose go out.
InternalDispose();
if (null != exToThrow)
{
throw exToThrow;
}
if (etwLog.IsEnabled())
{
etwLog.MethodExit(TraceSourceType.TraceSourceBase, this);
}
}
// Override of get_RecoveryInformation to be more specific with the exception string.
internal override byte[] RecoveryInformation(InternalEnlistment enlistment)
{
throw TransactionException.CreateInvalidOperationException(TraceSourceType.TraceSourceLtm,
SR.VolEnlistNoRecoveryInfo, null, enlistment == null ? Guid.Empty : enlistment.DistributedTxId);
}
// Process a timer event
private void ThreadTimer(Object state)
{
//
// Theory of operation.
//
// To timeout transactions we must walk down the list starting from the head
// until we find a link with an absolute timeout that is greater than our own.
// At that point everything further down in the list is elegable to be timed
// out. So simply remove that link in the list and walk down from that point
// timing out any transaction that is found.
//
// There could be a race between this callback being queued and the timer
// being disabled. If we get here when the timer is disabled, just return.
if (!_timerEnabled)
{
return;
}
// Increment the number of ticks
_ticks++;
_lastTimerTime = DateTime.UtcNow.Ticks;
//
// First find the starting point of transactions that should time out. Every transaction after
// that point will timeout so once we've found it then it is just a matter of traversing the
// structure.
//
BucketSet lastBucketSet = null;
BucketSet currentBucketSet = _headBucketSet; // The list always has a head.
// Acquire a writer lock before checking to see if we should disable the timer.
// Adding of transactions acquires a reader lock and might insert a new BucketSet.
// If that races with our check for a BucketSet existing, we may not timeout that
// transaction that is being added.
WeakReference nextWeakSet = null;
BucketSet nextBucketSet = null;
nextWeakSet = (WeakReference)currentBucketSet.nextSetWeak;
if (nextWeakSet != null)
{
nextBucketSet = (BucketSet)nextWeakSet.Target;
}
if (nextBucketSet == null)
{
_rwLock.EnterWriteLock();
try
{
// Access the nextBucketSet again in writer lock to account for any race before disabling the timeout.
nextWeakSet = (WeakReference)currentBucketSet.nextSetWeak;
if (nextWeakSet != null)
{
nextBucketSet = (BucketSet)nextWeakSet.Target;
}
if (nextBucketSet == null)
{
//
// Special case to allow for disabling the timer.
//
// If there are no transactions on the timeout list we can disable the
// timer.
if (!_timer.Change(Timeout.Infinite, Timeout.Infinite))
{
throw TransactionException.CreateInvalidOperationException(
TraceSourceType.TraceSourceLtm,
SR.UnexpectedTimerFailure,
null
);
}
_timerEnabled = false;
return;
}
}
finally
{
_rwLock.ExitWriteLock();
}
}
// Note it is slightly subtle that we always skip the head node. This is done
// on purpose because the head node contains transactions with essentially
// an infinite timeout.
do
{
do
{
nextWeakSet = (WeakReference)currentBucketSet.nextSetWeak;
if (nextWeakSet == null)
{
// Nothing more to do.
return;
}
nextBucketSet = (BucketSet)nextWeakSet.Target;
if (nextBucketSet == null)
{
// Again nothing more to do.
return;
}
lastBucketSet = currentBucketSet;
currentBucketSet = nextBucketSet;
}while (currentBucketSet.AbsoluteTimeout > _ticks);
//
// Pinch off the list at this point making sure it is still the correct set.
//
// Note: We may lose a race with an "Add" thread that is inserting a BucketSet in this location in
// the list. If that happens, this CompareExchange will not be performed and the returned abortingSetsWeak
// value will NOT equal nextWeakSet. But we check for that and if this condition occurs, this iteration of
// the timer thread will simply return, not timing out any transactions. When the next timer interval
// expires, the thread will walk the list again, find the appropriate BucketSet to pinch off, and
// then time out the transactions. This means that it is possible for a transaction to live a bit longer,
// but not much.
WeakReference abortingSetsWeak =
(WeakReference)Interlocked.CompareExchange(ref lastBucketSet.nextSetWeak, null, nextWeakSet);
if (abortingSetsWeak == nextWeakSet)
{
// Yea - now proceed to abort the transactions.
BucketSet abortingBucketSets = null;
do
{
if (abortingSetsWeak != null)
{
abortingBucketSets = (BucketSet)abortingSetsWeak.Target;
}
else
{
abortingBucketSets = null;
}
if (abortingBucketSets != null)
{
abortingBucketSets.TimeoutTransactions();
abortingSetsWeak = (WeakReference)abortingBucketSets.nextSetWeak;
}
}while (abortingBucketSets != null);
// That's all we needed to do.
break;
}
// We missed pulling the right transactions off. Loop back up and try again.
currentBucketSet = lastBucketSet;
}while (true);
}
