Adjustment of Barrier behavior to make it similar to other overload

src/autowiring/DispatchQueue.cpp

@@ -279,12 +279,8 @@ void DispatchQueue::PendExisting(std::unique_lock<std::mutex>&& lk, DispatchThun
 }
 
 bool DispatchQueue::Barrier(std::chrono::nanoseconds timeout) {
-  // Optimistic check first:
-  if (!m_count)
-    return true;
-
   // Short-circuit if zero is specified as the timeout value
-  if (timeout.count() == 0)
+  if (!m_count && timeout.count() == 0)
     return false;
 
   // Now lock and double-check:
@@ -294,10 +290,6 @@ bool DispatchQueue::Barrier(std::chrono::nanoseconds timeout) {
   if (onAborted)
     throw dispatch_aborted_exception("Dispatch queue was aborted before a timed wait was attempted");
 
-  // Short-circuit if the queue is already empty
-  if (!m_count)
-    return true;
-
   // Set up the lambda.  Note that the queue size CANNOT be 1, because we just checked to verify
   // that it is non-empty.  Thus, we do not need to signal the m_queueUpdated condition variable.
   auto complete = std::make_shared<bool>(false);