[desc] Execute pre & post process in the farm

meshroom/core/desc/node.py

@@ -58,6 +58,19 @@ class MrNodeType(enum.Enum):
     INPUT = enum.auto()
 
 
+def add_method_flag(methodName: str):
+    """ Decorator used to add a flag to a method. A flag is simply a variable set to True.
+    It will be used in this context to track whether a method is overloaded or not.
+
+    Args:
+        methodName (str): Name of the annotation to set
+    """
+    def wrapper(method):
+        method.__annotations__[methodName] = True
+        return method
+    return wrapper
+
+
 class BaseNode(object):
     """
     """
@@ -164,6 +177,7 @@ def postUpdate(cls, node):
         """
         pass
 
+    @add_method_flag("disabled_preprocess")
     def preprocess(self, node):
         """ Gets invoked just before the processChunk method for the node.
 
@@ -172,6 +186,11 @@ def preprocess(self, node):
         """
         pass
 
+    def _hasPreprocess(self):
+        """ Returns True if the class has a preprocess """
+        return not self.preprocess.__annotations__.get("disabled_preprocess", False)
+
+    @add_method_flag("disabled_postprocess")
     def postprocess(self, node):
         """ Gets invoked after the processChunk method for the node.
 
@@ -180,6 +199,10 @@ def postprocess(self, node):
         """
         pass
 
+    def _hasPostprocess(self):
+        """ Returns True if the class has a postprocess """
+        return not self.postprocess.__annotations__.get("disabled_postprocess", False)
+
     def process(self, node):
         raise NotImplementedError(f'No process implementation on node: "{node.name}"')