Merge remote-tracking branch 'living180/cache_panel_work'

* living180/cache_panel_work:
  Re-architect cache call recording
  Add a .ready() method to the panel API
  Use request toolbar for cache integration tests
  Allow integration tests to access the toolbar
  Add dependency on asgiref

Author: matthiask

debug_toolbar/apps.py

@@ -17,9 +17,10 @@ class DebugToolbarConfig(AppConfig):
     def ready(self):
         from debug_toolbar.toolbar import DebugToolbar
 
-        # Import the panels when the app is ready. This allows panels
-        # like CachePanel to enable the instrumentation immediately.
-        DebugToolbar.get_panel_classes()
+        # Import the panels when the app is ready and call their ready() methods.  This
+        # allows panels like CachePanel to enable their instrumentation immediately.
+        for cls in DebugToolbar.get_panel_classes():
+            cls.ready()
 
 
 def check_template_config(config):

debug_toolbar/panels/__init__.py

@@ -114,6 +114,19 @@ def scripts(self):
         """
         return []
 
+    # Panel early initialization
+
+    @classmethod
+    def ready(cls):
+        """
+        Perform early initialization for the panel.
+
+        This should only include initialization or instrumentation that needs to
+        be done unconditionally for the panel regardless of whether it is
+        enabled for a particular request.  It should be idempotent.
+        """
+        pass
+
     # URLs for panel-specific views
 
     @classmethod