Issue 6440 - Use long-lived connections to listen to extension events

messageResponder.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 111 matching lines @@
     {
       let name;
       if (type == "filter" && action == "loaded")
         name = "load";
       else
         name = type + "." + action;
 
       if (!(name in listenedFilterChanges))
       {
         listenedFilterChanges[name] = null;
-        FilterNotifier.on(name, (...args) =>
+        FilterNotifier.on(name, (item) =>
         {
-          sendMessage(type, action, args[0]);

[a.giammarchi, 2018/03/07 08:14:29]

I understand you want to keep doors opened in the `sendMessage` callback
signature, but reading FilterNotifier source code it's clear to me not even them
cafre much about extra arguments, undocumented param1, param2, and param3, *but*
they clearly emit an `item`.

Wouldn't be cleaner to have that clear knowledge of the received value in here
too?

`FilterNotifier.on(name, item => sendMessage(type, action, item));`

[Thomas Greiner, 2018/03/07 14:05:31]

Done.

+          sendMessage(type, action, item);
         });
       }
     }
-  }
-
-  function getListenerFilters(page)
-  {
-    let listenerFilters = changeListeners.get(page);
-    if (!listenerFilters)
-    {
-      listenerFilters = Object.create(null);
-      changeListeners.set(page, listenerFilters);
-    }
-    return listenerFilters;
   }
 
   function addSubscription(subscription, properties)
   {
     subscription.disabled = false;
     if ("title" in properties)
       subscription.title = properties.title;
     if ("homepage" in properties)
       subscription.homepage = properties.homepage;
 
@@ skipping 309 matching lines @@
     let filters = new Map();
     uiPorts.set(uiPort, filters);
 
     uiPort.onDisconnect.addListener(() =>
     {
       uiPorts.delete(uiPort);
     });
 
     uiPort.onMessage.addListener((message) =>
     {
-      let [type,  action] = message.type.split(".", 2);

[a.giammarchi, 2018/03/07 08:14:29]

WOW, first time in my life I've found a use case for the second argument of a
split!

+      let [type, action] = message.type.split(".", 2);
 
       // For now we're only using long-lived connections for handling
       // "*.listen" messages to tackle #6440
       if (action == "listen")
       {
         listen(type, filters, message.filter);
       }
     });
   }
 
   browser.runtime.onConnect.addListener(onConnect);
 })(this);