bpo-42251: Add gettrace and getprofile to threading (GH-23125)

This allows to retrieve the functions that were set in these two, which might differ from sys.gettrace and sys.getprofile within a thread.

Lib/threading.py

@@ -28,7 +28,7 @@ __all__ = ['get_ident', 'active_count', 'Condition', 'current_thread',
            'Event', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Thread',
            'Barrier', 'BrokenBarrierError', 'Timer', 'ThreadError',
            'setprofile', 'settrace', 'local', 'stack_size',
-           'excepthook', 'ExceptHookArgs']
+           'excepthook', 'ExceptHookArgs', 'gettrace', 'getprofile']
 
 # Rename some stuff so "from threading import *" is safe
 _start_new_thread = _thread.start_new_thread
@@ -65,6 +65,10 @@ def setprofile(func):
     global _profile_hook
     _profile_hook = func
 
+def getprofile():
+    """Get the profiler function as set by threading.setprofile()."""
+    return _profile_hook
+
 def settrace(func):
     """Set a trace function for all threads started from the threading module.
 
@@ -75,6 +79,10 @@ def settrace(func):
     global _trace_hook
     _trace_hook = func
 
+def gettrace():
+    """Get the trace function as set by threading.settrace()."""
+    return _trace_hook
+
 # Synchronization classes
 
 Lock = _allocate_lock