Disable instrumentation for disabled panels.

This eliminates the performance overhead when a panel is disabled.

1 files changed, 20 insertions, 7 deletions

diff --git a/debug_toolbar/panels/__init__.py b/debug_toolbar/panels/__init__.py
index d4a61da..9586e80 100644
--- a/debug_toolbar/panels/__init__.py
+++ b/debug_toolbar/panels/__init__.py
@@ -22,31 +22,44 @@ class DebugPanel(object):
     context = {}
 
     # Panel methods
+
     def __init__(self, toolbar, context={}):
         self.toolbar = toolbar
         self.context.update(context)
         self.slug = slugify(self.name)
 
+    def content(self):
+        if self.has_content:
+            context = self.context.copy()
+            context.update(self.get_stats())
+            return render_to_string(self.template, context)
+
     def dom_id(self):
         return 'djDebug%sPanel' % (self.name.replace(' ', ''))
 
+    # Titles and subtitles
+
     def nav_title(self):
-        """Title showing in toolbar"""
+        """Title showing in sidebar"""
         raise NotImplementedError
 
     def nav_subtitle(self):
-        """Subtitle showing until title in toolbar"""
+        """Subtitle showing under title in sidebar"""
         return ''
 
     def title(self):
         """Title showing in panel"""
         raise NotImplementedError
 
-    def content(self):
-        if self.has_content:
-            context = self.context.copy()
-            context.update(self.get_stats())
-            return render_to_string(self.template, context)
+    # Enable and disable (expensive) instrumentation
+
+    def enable_instrumentation(self):
+        pass
+
+    def disable_instrumentation(self):
+        pass
+
+    # Store and retrieve stats (shared between panels)
 
     def record_stats(self, stats):
         panel_stats = self.toolbar.stats.get(self.slug)