Add blocking flag and skeleton callback processing

Author: AlexanderWells-diamond

softioc/builder.py

@@ -8,6 +8,8 @@
 LoadDbdFile(os.path.join(os.path.dirname(__file__), 'device.dbd'))
 
 from . import device, pythonSoftIoc  # noqa
+# Re-export this so users only have to import the builder
+from .device import set_blocking # noqa
 
 PythonDevice = pythonSoftIoc.PythonDevice()
 
@@ -301,5 +303,7 @@ def UnsetDevice():
     'Action',
     # Other builder support functions
     'LoadDatabase',
-    'SetDeviceName', 'UnsetDevice'
+    'SetDeviceName', 'UnsetDevice',
+    # Device support functions
+    'set_blocking'
 ]

softioc/device.py

@@ -14,6 +14,15 @@
 # dispatcher(func, *args) will queue a callback to happen
 dispatcher = None
 
+# Global blocking flag, used to mark asynchronous (False) or synchronous (True)
+# processing modes for Out records.
+# Default False to maintain behaviour from previous versions.
+blocking = False
+
+def set_blocking(val):
+    global blocking
+    blocking = val
+
 
 # EPICS processing return codes
 EPICS_OK = 0
@@ -142,6 +151,8 @@ def __init__(self, name, **kargs):
         else:
             self._value = None
 
+        self._blocking = kargs.pop('blocking', blocking)
+
         self.__super.__init__(name, **kargs)
 
     def init_record(self, record):
@@ -162,6 +173,13 @@ def init_record(self, record):
             recGblResetAlarms(record)
         return self._epics_rc_
 
+    def __completion(self):
+        pass
+
+    def __wrap_completion(self, value):
+        self.__on_update(value)
+        self.__completion()
+
     def _process(self, record):
         '''Processing suitable for output records.  Performs immediate value
         validation and asynchronous update notification.'''
@@ -183,7 +201,7 @@ def _process(self, record):
             self._value = value
             record.UDF = 0
             if self.__on_update and self.__enable_write:
-                dispatcher(self.__on_update, python_value)
+                dispatcher(self.__wrap_completion, python_value)
             return EPICS_OK