public static ClrInstance?TryResolveContinuationInstance(ClrInstance continuation, CausalityContext context)
{
if (continuation.IsOfType(context.Registry.StandardTaskContinuationType))
{
return(continuation["m_task"].Instance);
}
if (continuation.IsTaskCompletionSource(context))
{
return(continuation["m_task"].Instance);
}
if (continuation.IsCompletedTaskContinuation(context))
{
// Continuation is a special sentinel instance that indicates that the task is completed.
return(null);
}
if (continuation.IsOfType(typeof(Action), context))
{
return(TryResolveContinuationForAction(continuation, context));
}
if (continuation.IsOfType(context.Registry.AwaitTaskContinuationIndex) || continuation.IsOfType(context.Registry.TaskIndex))
{
return(TryResolveContinuationForAction(continuation["m_action"].Instance, context));
}
// Need to compare by name since GetTypeByName does not work for the generic type during initialization
if (continuation.IsListOfObjects())
{
Contract.Assert(false, "Please call 'TryResolveContinuations' for a list of continuations.");
}
return(null);
}
public static ClrInstance?TryResolveContinuationForAction(ClrInstance instance, CausalityContext context)
{
Contract.Requires(instance.IsOfType(typeof(Action), context), $"A given instance should be of type System.Action, but was '{instance.Type.TypeToString(context.Registry)}'");
var continuation = instance;
var actionTarget = continuation["_target"].Instance;
if (actionTarget.IsOfType(context.Registry.ContinuationWrapperType))
{
// Do we need to look at the m_innerTask field as well here?
return(actionTarget["m_continuation"].Instance);
}
// If the action points to a closure, it is possible that the closure
// is responsible for setting the result of a task completion source.
// There is no simple way to detect whether this is the case or not, so we will add the "edge" unconditionally.
if (actionTarget.Type.IsClosure())
{
foreach (var field in actionTarget.Fields)
{
if (field.Instance.IsTaskCompletionSource(context))
{
return(field.Instance);
}
}
}
// m_stateMachine field is defined in AsyncMethodBuilderCore and in MoveNextRunner.
var stateMachine = actionTarget.TryGetFieldValue("m_stateMachine")?.Instance;
if (stateMachine.IsNull())
{
return(null);
}
return(stateMachine);
}