From 2816c6fa2a1613e5eeb7967cde0793019ce62feb Mon Sep 17 00:00:00 2001
From: Aymeric Augustin
Date: Sat, 9 Nov 2013 19:07:38 +0100
Subject: Load the content of panels dynamically.

This should drastically reduce the overhead of the browser toolbar when
a page has a complex template structure or many SQL queries.

This change is backwards-incompatible for third-party panels because it
changes the signature of __init__.

The JavaScript could probably be improved; I'm outside my comfort zone.
---
 debug_toolbar/panels/__init__.py                 |  2 +-
 debug_toolbar/static/debug_toolbar/js/toolbar.js | 17 +++++++++++++++++
 debug_toolbar/templates/debug_toolbar/base.html  | 13 +++++++------
 debug_toolbar/toolbar/loader.py                  | 23 +++++++++++++++++++++--
 debug_toolbar/urls.py                            |  1 +
 debug_toolbar/views.py                           | 21 ++++++++++++++++++++-
 6 files changed, 67 insertions(+), 10 deletions(-)

diff --git a/debug_toolbar/panels/__init__.py b/debug_toolbar/panels/__init__.py
index a48b1b3..c830bb2 100644
--- a/debug_toolbar/panels/__init__.py
+++ b/debug_toolbar/panels/__init__.py
@@ -11,7 +11,7 @@ class DebugPanel(object):
     """
     # name = 'Base'
     # template = 'debug_toolbar/panels/base.html'
-    has_content = False  # If content returns something, set to true in subclass
+    has_content = False  # If content returns something, set to True in subclass
 
     # We'll maintain a local context instance so we can expose our template
     # context variables to panels which need them:
diff --git a/debug_toolbar/static/debug_toolbar/js/toolbar.js b/debug_toolbar/static/debug_toolbar/js/toolbar.js
index 094c3ac..0b7d1ec 100644
--- a/debug_toolbar/static/debug_toolbar/js/toolbar.js
+++ b/debug_toolbar/static/debug_toolbar/js/toolbar.js
@@ -28,6 +28,23 @@
                     $(this).parent().removeClass('active');
                 } else {
                     $('.panelContent').hide(); // Hide any that are already open
+                    var inner = current.find('.djDebugPanelContent .scroll').first();
+                    if ($(inner).empty()) {
+                        var ajax_data = {
+                            data: {
+                                toolbar_id: $('#djDebug').data('toolbar-id'),
+                                panel_id: this.className
+                            },
+                            type: 'GET',
+                            url: $('#djDebug').data('render-panel-url')
+                        };
+                        $.ajax(ajax_data).done(function(data){
+                            inner.html(data);
+                        }).fail(function(xhr){
+                            var message = '<div class="djDebugPanelTitle"><a class="djDebugClose djDebugBack" href="">Back</a><h3>'+xhr.status+': '+xhr.statusText+'</h3></div>';
+                            $('#djDebugWindow').html(message).show();
+                        });
+                    }
                     current.show();
                     $('#djDebugToolbar li').removeClass('active');
                     $(this).parent().addClass('active');
diff --git a/debug_toolbar/templates/debug_toolbar/base.html b/debug_toolbar/templates/debug_toolbar/base.html
index e214044..d5a356c 100644
--- a/debug_toolbar/templates/debug_toolbar/base.html
+++ b/debug_toolbar/templates/debug_toolbar/base.html
@@ -8,7 +8,9 @@ if(!window.jQuery) document.write('<scr'+'ipt src="{{ STATIC_URL }}debug_toolbar
 //]]></script>
 <script src="{{ STATIC_URL }}debug_toolbar/js/jquery.cookie.js"></script>
 <script src="{{ STATIC_URL }}debug_toolbar/js/toolbar.js"></script>
-<div id="djDebug" style="display:none;" dir="ltr" {{ TOOLBAR_ROOT_TAG_ATTRS|safe }}>
+<div id="djDebug" style="display:none;" dir="ltr"
+     data-toolbar-id="{{ toolbar_id }}" data-render-panel-url="/__debug__/render_panel/"
+     {{ TOOLBAR_ROOT_TAG_ATTRS|safe }}>
 	<div style="display:none;" id="djDebugToolbar">
 		<ul id="djDebugPanelList">
 			{% if panels %}
@@ -22,7 +24,7 @@ if(!window.jQuery) document.write('<scr'+'ipt src="{{ STATIC_URL }}debug_toolbar
 					{% if panel.has_content and panel.enabled %}
 						<a href="{{ panel.url|default:"#" }}" title="{{ panel.title }}" class="{{ panel.dom_id }}">
 					{% else %}
-					    <div class="contentless{% if panel.disabled %} disabled{% endif %}">
+						<div class="contentless{% if panel.disabled %} disabled{% endif %}">
 					{% endif %}
 					{{ panel.nav_title }}
 					{% if panel.enabled %}
@@ -33,7 +35,7 @@ if(!window.jQuery) document.write('<scr'+'ipt src="{{ STATIC_URL }}debug_toolbar
 					{% if panel.has_content and panel.enabled %}
 						</a>
 					{% else %}
-					    </div>
+						</div>
 					{% endif %}
 				</li>
 			{% endfor %}
@@ -50,9 +52,8 @@ if(!window.jQuery) document.write('<scr'+'ipt src="{{ STATIC_URL }}debug_toolbar
 					<h3>{{ panel.title|safe }}</h3>
 				</div>
 				<div class="djDebugPanelContent">
-				    <div class="scroll">
-				        {{ panel.content|safe }}
-				    </div>
+					<div class="scroll">
+					</div>
 				</div>
 			</div>
 		{% endif %}
diff --git a/debug_toolbar/toolbar/loader.py b/debug_toolbar/toolbar/loader.py
index 7b525b6..de4aa93 100644
--- a/debug_toolbar/toolbar/loader.py
+++ b/debug_toolbar/toolbar/loader.py
@@ -46,7 +46,6 @@ class DebugToolbar(object):
         global panel_classes
         for panel_class in panel_classes:
             panel_instance = panel_class(self, context=self.template_context)
-
             self._panels[panel_class] = panel_instance
 
     def render_toolbar(self):
@@ -56,8 +55,8 @@ class DebugToolbar(object):
         context = self.template_context.copy()
         context.update({
             'panels': self.panels,
+            'toolbar_id': save_toolbar(self),
         })
-
         return render_to_string('debug_toolbar/base.html', context)
 
 
@@ -101,3 +100,23 @@ def load_panel_classes():
                 'Toolbar Panel module "%s" does not define a "%s" class' %
                 (panel_module, panel_classname))
         panel_classes.append(panel_class)
+
+
+toolbar_counter = 0
+toolbar_maxsize = 10            # keep data for the last 10 requests
+toolbar_results = SortedDict()
+
+
+def save_toolbar(toolbar):
+    global toolbar_counter, toolbar_results
+    toolbar_counter += 1
+    toolbar_results[toolbar_counter] = toolbar
+    for _ in range(len(toolbar_results) - toolbar_maxsize):
+        # When we drop support for Python 2.6 and switch to
+        # collections.OrderedDict, use popitem(last=False).
+        del toolbar_results[toolbar_results.keyOrder[0]]
+    return toolbar_counter
+
+
+def get_saved_toolbar(toolbar_id):
+    return toolbar_results.get(toolbar_id)
diff --git a/debug_toolbar/urls.py b/debug_toolbar/urls.py
index 1a6daf8..05ef245 100644
--- a/debug_toolbar/urls.py
+++ b/debug_toolbar/urls.py
@@ -12,6 +12,7 @@ from django.conf.urls import patterns, url
 _PREFIX = '__debug__'
 
 urlpatterns = patterns('debug_toolbar.views',                           # noqa
+    url(r'^%s/render_panel/$' % _PREFIX, 'render_panel', name='render_panel'),
     url(r'^%s/sql_select/$' % _PREFIX, 'sql_select', name='sql_select'),
     url(r'^%s/sql_explain/$' % _PREFIX, 'sql_explain', name='sql_explain'),
     url(r'^%s/sql_profile/$' % _PREFIX, 'sql_profile', name='sql_profile'),
diff --git a/debug_toolbar/views.py b/debug_toolbar/views.py
index 8b3e63c..21f4747 100644
--- a/debug_toolbar/views.py
+++ b/debug_toolbar/views.py
@@ -6,11 +6,30 @@ views in any other way is generally not advised.
 
 from __future__ import unicode_literals
 
-from django.http import HttpResponseBadRequest
+from django.http import HttpResponse, HttpResponseBadRequest
 from django.shortcuts import render
+from django.utils.html import escape
+from django.utils.translation import ugettext as _
 from django.views.decorators.csrf import csrf_exempt
 
 from debug_toolbar.forms import SQLSelectForm
+from debug_toolbar.toolbar.loader import get_saved_toolbar
+
+
+def render_panel(request):
+    """Render the contents of a panel"""
+    toolbar = get_saved_toolbar(int(request.GET['toolbar_id']))
+    if toolbar is None:
+        content = _("Data for this panel isn't available anymore. "
+                    "Please reload the page and retry.")
+        content = "<p>%s</p>" % escape(content)
+    else:
+        panel_id = request.GET['panel_id']
+        for panel in toolbar.panels:
+            if panel.dom_id() == panel_id:
+                content = panel.content()
+                break
+    return HttpResponse(content)
 
 
 @csrf_exempt
-- 
cgit v1.2.3