hook epics exit into interpreter lifecycle

allow interactive_ioc(call_exit=False) to cleanup
and exit cleanly.

Author: mdavidsaver

softioc/asyncio_dispatcher.py

@@ -1,7 +1,7 @@
 import asyncio
 import inspect
 import threading
-
+import atexit
 
 class AsyncioDispatcher:
     def __init__(self, loop=None):
@@ -14,7 +14,17 @@ def __init__(self, loop=None):
         if loop is None:
             # Make one and run it in a background thread
             self.loop = asyncio.new_event_loop()
-            threading.Thread(target=self.loop.run_forever).start()
+            worker = threading.Thread(target=self.loop.run_forever)
+            # Explicitly manage worker thread as part of interpreter shutdown.
+            # Otherwise threading module will deadlock trying to join()
+            # before our atexit hook runs, while the loop is still running.
+            worker.daemon = True
+
+            @atexit.register
+            def aioJoin(worker=worker, loop=self.loop):
+                loop.call_soon_threadsafe(loop.stop)
+                worker.join()
+            worker.start()
 
     def __call__(self, func, *args):
         async def async_wrapper():

softioc/imports.py

@@ -99,6 +99,10 @@ def auto_decode(result, func, args):
 epicsExit = Com.epicsExit
 epicsExit.argtypes = (c_int,)
 
+epicsExitCallAtExits = Com.epicsExitCallAtExits
+epicsExitCallAtExits.argtypes = ()
+epicsExitCallAtExits.restype = None
+
 
 __all__ = [
     'get_field_offsets',

softioc/softioc.py

@@ -11,7 +11,10 @@
 __all__ = ['dbLoadDatabase', 'iocInit', 'interactive_ioc']
 
 
-epicsExit = imports.epicsExit
+# tie in epicsAtExit() to interpreter lifecycle
+@atexit.register
+def epicsAtPyExit():
+    imports.epicsExitCallAtExits()
 
 
 def iocInit(dispatcher=None):
@@ -39,7 +42,7 @@ def iocInit(dispatcher=None):
 
 def safeEpicsExit(code=0):
     '''Calls epicsExit() after ensuring Python exit handlers called.'''
-    if hasattr(sys, 'exitfunc'): # py 2.x
+    if hasattr(sys, 'exitfunc'):  # py 2.x
         try:
             # Calling epicsExit() will bypass any atexit exit handlers, so call
             # them explicitly now.
@@ -48,12 +51,13 @@ def safeEpicsExit(code=0):
             # Make sure we don't try the exit handlers more than once!
             del sys.exitfunc
 
-    elif hasattr(atexit, '_run_exitfuncs'): # py 3.x
+    elif hasattr(atexit, '_run_exitfuncs'):  # py 3.x
         atexit._run_exitfuncs()
 
     # calls epicsExitCallAtExits()
     # and then OS exit()
-    epicsExit(code)
+    imports.epicsExit(code)
+epicsExit = safeEpicsExit
 
 # The following identifiers will be exported to interactive shell.
 command_names = []
@@ -240,10 +244,10 @@ def call_f(*args):
 # Hacked up exit object so that when soft IOC framework sends us an exit command
 # we actually exit.
 class Exiter:
-    def __repr__(self):
-        safeEpicsExit()
-    def __call__(self):
-        safeEpicsExit()
+    def __repr__(self):  # hack to exit when "called" with no parenthesis
+        sys.exit(0)
+    def __call__(self, code=0):
+        sys.exit(code)
 
 exit = Exiter()
 command_names.append('exit')
@@ -312,7 +316,12 @@ def interactive_ioc(context = {}, call_exit = True):
         # This suppresses irritating exit message introduced by Python3.  Alas,
         # this option is only available in Python 3.6!
         interact_args = dict(exitmsg = '')
-    code.interact(local = dict(exports, **context), **interact_args)
+    try:
+        code.interact(local = dict(exports, **context), **interact_args)
+    except SystemExit as e:
+        if call_exit:
+            safeEpicsExit(e.code)
+        raise
 
     if call_exit:
-        safeEpicsExit()
+        safeEpicsExit(0)