private void CallWithNonPumpingWait(Action callback)
{
SynchronizationContext oldSynchronizationContext = SynchronizationContext.Current;
NonPumpingSynchronizationContext nonPumpingSynchronizationContext =
Interlocked.Exchange <NonPumpingSynchronizationContext>(ref _defaultSynchronizationContext, null);
// if the default non-pumping context is in use, allocate a new one
bool usingDefaultContext = (nonPumpingSynchronizationContext != null);
if (!usingDefaultContext)
{
nonPumpingSynchronizationContext = new NonPumpingSynchronizationContext();
}
try
{
// install the non-pumping context
nonPumpingSynchronizationContext.Parent = oldSynchronizationContext;
SynchronizationContext.SetSynchronizationContext(nonPumpingSynchronizationContext);
// invoke the callback
callback();
}
finally
{
// restore the old context
SynchronizationContext.SetSynchronizationContext(oldSynchronizationContext);
// put the default non-pumping context back into play
if (usingDefaultContext)
{
Interlocked.Exchange <NonPumpingSynchronizationContext>(ref _defaultSynchronizationContext, nonPumpingSynchronizationContext);
}
}
}
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
#region Constructors
internal ReaderWriterLockWrapper()
{
// ideally we'd like to use the NoRecursion policy, but RWLock supports
// recursion so we allow recursion for compat. It's needed for at least
// one pattern - a weak event manager for an event A that delegates to
// a second event B via a second weak event manager. There's at least
// one instance of this within WPF (CanExecuteChanged delegates to
// RequerySuggested), and it could also happen in user code.
_rwLock = new ReaderWriterLockSlim(LockRecursionPolicy.SupportsRecursion);
_defaultSynchronizationContext = new NonPumpingSynchronizationContext();
Initialize(!MS.Internal.BaseAppContextSwitches.EnableWeakEventMemoryImprovements);
}
