Observers clear references (#298)

Process level (`CableReady::Config` - `@observer_peers`) channel clearing. Possible memory leak fix.

Fixes #297

lib/cable_ready/channels.rb

@@ -27,7 +27,7 @@ def broadcast(*identifiers, clear: true)
         .select { |channel| channel.identifier.is_a?(String) }
         .tap do |channels|
           channels.each { |channel| @channels[channel.identifier].broadcast(clear: clear) }
-          channels.each { |channel| @channels.except!(channel.identifier) if clear }
+          channels.each { |channel| clear_channel(channel) if clear }
         end
     end
 
@@ -37,8 +37,16 @@ def broadcast_to(model, *identifiers, clear: true)
         .reject { |channel| channel.identifier.is_a?(String) }
         .tap do |channels|
           channels.each { |channel| @channels[channel.identifier].broadcast_to(model, clear: clear) }
-          channels.each { |channel| @channels.except!(channel.identifier) if clear }
+          channels.each { |channel| clear_channel(channel) if clear }
         end
     end
+
+    private
+
+    def clear_channel(channel)
+      @channels.except!(channel.identifier)
+      observer = CableReady.config.observers.find { |o| o.try(:identifier) == channel.identifier }
+      CableReady.config.delete_observer(observer) if observer
+    end
   end
 end