Improve EventHandler response sending pattern

lib/tfw/builtins/directory_snapshotting_event_handler.py

@@ -53,7 +53,7 @@ class DirectorySnapshottingEventHandler(EventHandler):
         try:
             data = message['data']
             message['data'] = self.command_handlers[data['command']](data)
-            return message
+            self.send_message(message)
         except KeyError:
             LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)
 

lib/tfw/builtins/frontend_event_handler.py

@@ -17,7 +17,7 @@ class FrontendEventHandler(EventHandler):
         self._frontend_message_storage.save_message(message)
         if message['key'] == 'recover':
             self.recover_frontend()
-        return message
+        self.send_message(message)
 
     def recover_frontend(self):
         for message in self._frontend_message_storage.messages:

lib/tfw/builtins/fsm_aware_event_handler.py

@@ -21,6 +21,5 @@ class FSMAwareEventHandler(EventHandler, FSMAware, ABC):
         self.subscribe('fsm_update')
 
     def dispatch_handling(self, message):
-        if self.refresh_on_fsm_update(message):
-            return None
-        return super().dispatch_handling(message)
+        if not self.refresh_on_fsm_update(message):
+            super().dispatch_handling(message)

lib/tfw/builtins/fsm_managing_event_handler.py

@@ -46,7 +46,7 @@ class FSMManagingEventHandler(EventHandler):
                 sign_message(self.auth_key, message)
                 sign_message(self.auth_key, fsm_update_message)
                 self.server_connector.send_message(fsm_update_message, Scope.BROADCAST)
-            return message
+            self.send_message(message)
         except KeyError:
             LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)
 

lib/tfw/builtins/ide_event_handler.py

@@ -187,7 +187,7 @@ class IdeEventHandler(EventHandler):
             data = message['data']
             message['data'] = self.commands[data['command']](data)
             self.attach_fileinfo(data)
-            return message
+            self.send_message(message)
         except KeyError:
             LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)
 

lib/tfw/builtins/process_managing_event_handler.py

@@ -58,6 +58,6 @@ class ProcessManagingEventHandler(EventHandler):
                     data['process_name'],
                     self.log_tail
                 )
-            return message
+            self.send_message(message)
         except KeyError:
             LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)

lib/tfw/builtins/terminal_event_handler.py

@@ -56,7 +56,7 @@ class TerminalEventHandler(EventHandler):
         try:
             data = message['data']
             message['data'] = self.commands[data['command']](data)
-            return message
+            self.send_message(message)
         except KeyError:
             LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)
 

lib/tfw/event_handlers/event_handler_base.py

@@ -5,8 +5,6 @@ import logging
 from inspect import currentframe
 from typing import Iterable
 
-from tfw.networking import Scope
-
 LOG = logging.getLogger(__name__)
 
 
@@ -17,7 +15,7 @@ class EventHandlerBase:
 
     Derived classes must implement the handle_event() method
     """
-    def __init__(self, key, server_connector, scope=Scope.ZMQ):
+    def __init__(self, key, server_connector, scope):
         self.server_connector = server_connector
         self.scope = scope
         self.keys = []
@@ -29,12 +27,18 @@ class EventHandlerBase:
         self.subscribe(*self.keys)
         self.server_connector.register_callback(self.event_handler_callback)
 
-    @property
-    def key(self):
+    def subscribe(self, *keys):
         """
-        Returns the oldest key this EventHandler was subscribed to.
+        Subscribe this EventHandler to receive events for given keys.
+        Note that you can subscribe to the same key several times in which
+        case you will need to unsubscribe multiple times in order to stop
+        receiving events.
+
+        :param keys: list of keys to subscribe to
         """
-        return self.keys[0]
+        for key in keys:
+            self.server_connector.subscribe(key)
+            self.keys.append(key)
 
     def event_handler_callback(self, message):
         """
@@ -43,15 +47,8 @@ class EventHandlerBase:
         a response back in case the handler returned something.
         This is subscribed in __init__().
         """
-        if not self.check_key(message):
-            return
-
-        response = self.dispatch_handling(message)
-        if response:
-            self.send_message(response)
-
-    def send_message(self, message):
-        self.server_connector.send_message(message, self.scope)
+        if self.check_key(message):
+            self.dispatch_handling(message)
 
     def check_key(self, message):
         """
@@ -74,7 +71,7 @@ class EventHandlerBase:
         :param message: the message received
         :returns: the message to send back
         """
-        return self.handle_event(message)
+        self.handle_event(message)
 
     def handle_event(self, message):
         """
@@ -85,18 +82,8 @@ class EventHandlerBase:
         """
         raise NotImplementedError
 
-    def subscribe(self, *keys):
-        """
-        Subscribe this EventHandler to receive events for given keys.
-        Note that you can subscribe to the same key several times in which
-        case you will need to unsubscribe multiple times in order to stop
-        receiving events.
-
-        :param keys: list of keys to subscribe to
-        """
-        for key in keys:
-            self.server_connector.subscribe(key)
-            self.keys.append(key)
+    def send_message(self, message):
+        self.server_connector.send_message(message, self.scope)
 
     def unsubscribe(self, *keys):
         """