Fix several issues

CHANGELOG.md

@@ -9,8 +9,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+* Added the option to pass arguments into the long running task of a background worker.
+* Added the option to manually control when the background worker task is set to **Done**.
+* Added dispose function to control resource deallocation in a background worker.
+
 ### Changed
 
+* Set background threads in the background worker as daemon threads to prevent blocking the main thread.
+* Changed base class of `Message` from `UserDict` to `object` because in IronPython 2.7 `UserDict` is an old-style class. The behavior of dictionary-like is still preserved.
+
 ### Removed
 
 

src/compas_eve/core.py

@@ -1,8 +1,5 @@
-# Python 2/3 compatibility import list
-try:
-    from collections import UserDict
-except ImportError:
-    from UserDict import UserDict
+from compas.data import json_dumps
+from compas.data import json_loads
 
 DEFAULT_TRANSPORT = None
 
@@ -61,21 +58,34 @@ def unadvertise(self, topic):
         pass
 
 
-class Message(UserDict):
+class Message(object):
     """Message objects used for publishing and subscribing to/from topics.
 
     A message is fundamentally a dictionary and behaves as one."""
 
+    def __init__(self, *args, **kwargs):
+        super(Message, self).__init__()
+        self.data = {}
+        self.data.update(*args, **kwargs)
+
+    def ToString(self):
+        return str(self)
+
     def __str__(self):
         return str(self.data)
 
     def __getattr__(self, name):
-        return self.__dict__["data"][name]
+        return self.data[name]
+
+    def __getitem__(self, key):
+        return self.data[key]
+
+    def __setitem__(self, key, value):
+        self.data[key] = value
 
     @classmethod
     def parse(cls, value):
-        instance = cls()
-        instance.update(value)
+        instance = cls(**value)
         return instance
 
 
@@ -103,6 +113,26 @@ def __init__(self, name, message_type, **options):
         self.message_type = message_type
         self.options = options
 
+    def _message_to_json(self, message):
+        """Convert a message to a JSON string.
+
+        Normally, this method expects sub-classes of ``Message`` as input.
+        However, it can deal with regular dictionaries as well as classes
+        implementing the COMPAS data framework.
+        """
+        try:
+            data = message.data
+        except (KeyError, AttributeError):
+            try:
+                data = message.__data__
+            except (KeyError, AttributeError):
+                data = dict(message)
+        return json_dumps(data)
+
+    def _message_from_json(self, json_message):
+        """Converts a JSON string back into a message instance."""
+        return self.message_type.parse(json_loads(json_message))
+
 
 class Publisher(object):
     """Publisher interface."""

src/compas_eve/ghpython/background.py

@@ -54,16 +54,27 @@ def do_something_long_and_complicated(worker):
         Grasshopper environment object
     long_running_function : function, optional
         This function will be the main entry point for the long-running task.
+    dispose_function : function, optional
+        If defined, this function will be called when the worker is disposed. It can be used for clean-up tasks
+        and resource deallocation.
+    auto_set_done : bool, optional
+        If true, the worker state will be automatically set to ``Done`` after the function returns.
+        Defaults to ``True``.
+    args : tuple, optional
+        List or tuple of arguments for the invocation of the ``long_running_function``. Defaults to ``()``.
     """
 
-    def __init__(self, ghenv, long_running_function=None):
+    def __init__(self, ghenv, long_running_function=None, dispose_function=None, auto_set_done=True, args=()):
         super(BackgroundWorker, self).__init__()
         self.ghenv = ghenv
         self._is_working = False
         self._is_done = False
         self._is_cancelled = False
         self._has_requested_cancellation = False
         self.long_running_function = long_running_function
+        self.dispose_function = dispose_function
+        self.auto_set_done = auto_set_done
+        self.args = args
 
     def is_working(self):
         """Indicate whether the worker is currently working or not."""
@@ -86,17 +97,37 @@ def start_work(self):
         def _long_running_task_wrapper(worker):
             try:
                 worker.set_internal_state_to_working()
-                result = self.long_running_function(self)
-                worker.set_internal_state_to_done(result)
+                result = self.long_running_function(self, *self.args)
+
+                # There are (at least) two types of long running functions:
+                # 1. Those that block the thread while working
+                #    (e.g. they have a busy-wait or some kind of `while` loop)
+                # 2. Those that hookup event handlers and return immediately
+                #    so then they don't need to block the thread.
+                # The first case means that we can set the state to "DONE"
+                # right after calling the function because if it returned, it really
+                # means it's done.
+                # The second case will return immediately, and setting the state to "DONE"
+                # would be wrong because the handlers are still going to trigger.
+                # In that case we can set the flag `auto_set_done` to `False` so that
+                # we don't automatically set the state to "DONE".
+                if self.auto_set_done:
+                    worker.set_internal_state_to_done(result)
             except Exception as e:
                 worker.display_message(str(e))
                 worker.set_internal_state_to_cancelled()
 
         target = _long_running_task_wrapper
         args = (self,)
         self.thread = threading.Thread(target=target, args=args)
+        self.thread.daemon = True
         self.thread.start()
 
+    def dispose(self):
+        """Invoked when the worker is being disposed."""
+        if callable(self.dispose_function):
+            self.dispose_function(self)
+
     def set_internal_state_to_working(self):
         """Set the internal state to ``working``."""
         self._is_working = True
@@ -159,7 +190,9 @@ def ui_callback():
         Rhino.RhinoApp.InvokeOnUiThread(System.Action(ui_callback))
 
     @classmethod
-    def instance_by_component(cls, ghenv, long_running_function=None, force_new=False):
+    def instance_by_component(
+        cls, ghenv, long_running_function=None, dispose_function=None, auto_set_done=True, force_new=False, args=()
+    ):
         """Get the worker instance assigned to the component.
 
         This will get a persistant instance of a background worker
@@ -172,8 +205,16 @@ def instance_by_component(cls, ghenv, long_running_function=None, force_new=Fals
             Grasshopper environment object
         long_running_function : function, optional
             This function will be the main entry point for the long-running task.
+        dispose_function : function, optional
+            If defined, this function will be called when the worker is disposed.
+            It can be used for clean-up tasks and resource deallocation.
+        auto_set_done : bool, optional
+            If true, the worker state will be automatically set to ``Done`` after the function returns.
+            Defaults to ``True``.
         force_new : bool, optional
             Force the creation of a new background worker, by default False.
+        args : tuple, optional
+            List or tuple of arguments for the invocation of the ``long_running_function``. Defaults to ``()``.
 
         Returns
         -------
@@ -186,11 +227,18 @@ def instance_by_component(cls, ghenv, long_running_function=None, force_new=Fals
 
         if worker and force_new:
             worker.request_cancellation()
+            worker.dispose()
             worker = None
             del scriptcontext.sticky[key]
 
         if not worker:
-            worker = cls(ghenv, long_running_function=long_running_function)
+            worker = cls(
+                ghenv,
+                long_running_function=long_running_function,
+                dispose_function=dispose_function,
+                auto_set_done=auto_set_done,
+                args=args,
+            )
             scriptcontext.sticky[key] = worker
 
         return worker
@@ -212,5 +260,6 @@ def stop_instance_by_component(cls, ghenv):
 
         if worker:
             worker.request_cancellation()
+            worker.dispose()
             worker = None
             del scriptcontext.sticky[key]

src/compas_eve/ghpython/components/Ce_BackgroundTask/code.py

@@ -17,7 +17,7 @@
 
 
 class BackgroundTaskComponent(component):
-    def RunScript(self, reset, task, on):
+    def RunScript(self, task, reset, on):
         if not on:
             BackgroundWorker.stop_instance_by_component(ghenv)  # noqa: F821
             return None

src/compas_eve/ghpython/components/Ce_BackgroundTask/metadata.json

@@ -10,14 +10,14 @@
         "isAdvancedMode": true,
         "iconDisplay": 2,
         "inputParameters": [
-            {
-                "name": "reset",
-                "description": "Resets the background worker."
-            },
             {
                 "name": "task",
                 "description": "A Python function that will be executed by the background worker. The function does not need to return quickly, it can even have an infinite loop and keep running, it will not block the UI."
             },
+            {
+                "name": "reset",
+                "description": "Resets the background worker."
+            },
             {
                 "name": "on",
                 "description": "Turn ON or OFF the background worker.",

src/compas_eve/mqtt/mqtt_cli.py

@@ -4,11 +4,7 @@
 from ..core import Transport
 from ..event_emitter import EventEmitterMixin
 
-from compas.data import json_dumps
-from compas.data import json_loads
-
 import clr
-import json
 import os
 import sys
 
@@ -75,11 +71,11 @@ def on_ready(self, callback):
             self.once("ready", callback)
 
     def publish(self, topic, message):
-        # TODO: can we avoid the additional cast to dict?
+        json_message = topic._message_to_json(message)
         application_message = (
             MqttApplicationMessageBuilder()
             .WithTopic(topic.name)
-            .WithPayload(json_dumps(dict(message)))
+            .WithPayload(json_message)
             .Build()
         )
 
@@ -94,7 +90,7 @@ def subscribe(self, topic, callback):
 
         def _local_callback(application_message):
             payload = Encoding.UTF8.GetString(application_message.Payload)
-            msg = topic.message_type.parse(json_loads(payload))
+            msg = topic._message_from_json(payload)
             callback(msg)
 
         def _subscribe_callback(**kwargs):

src/compas_eve/mqtt/mqtt_paho.py

@@ -1,6 +1,3 @@
-from compas.data import json_dumps
-from compas.data import json_loads
-
 from ..core import Transport
 from ..event_emitter import EventEmitterMixin
 
@@ -63,8 +60,7 @@ def publish(self, topic, message):
         """
 
         def _callback(**kwargs):
-            # TODO: can we avoid the additional cast to dict?
-            json_message = json_dumps(dict(message))
+            json_message = topic._message_to_json(message)
             self.client.publish(topic.name, json_message)
 
         self.on_ready(_callback)
@@ -91,7 +87,7 @@ def subscribe(self, topic, callback):
         subscribe_id = "{}:{}".format(event_key, id(callback))
 
         def _local_callback(msg):
-            msg = topic.message_type.parse(json_loads(msg.payload.decode()))
+            msg = topic._message_from_json(msg.payload.decode())
             callback(msg)
 
         def _subscribe_callback(**kwargs):