* If the last refcount on a python lambda/temp function is released when a
wrapping std::function is destroyed in a C++ invoke, we can't destroy it
safely. Instead we queue up that decref and process it the next chance we're
able (which is either when the current execution finishes for a python shell
execution, or on the next function call which handles extensions).
* When calling the register() function there is no frame or globals, so we need
to set an internal handle external to that.
* This means functions that get wrapped know that there's a global handler for
exceptions, which just prints to the log. Otherwise they think they're running
synchronously and write to an invalid exception handling object.
* Instead of checking on the filename, we look for a specially named
exported symbol somewhere in a module that's already loaded.
* This allows us to mark the python module as a replay program, so if
it's loaded into the python interpreter it will be able to use the
replay API.
* In future we could handle async exceptions by storing the exception
information in a std::function derived object (instead of the separate
ExceptionHandling that lives on the stack) and query it out in a new
WaitForInvoke function maybe. Right now we just print the exception
to the output log and abort the callback.
baldurk