Color-code SQL query "Timeline" stripes according to stacktrace

3 files changed, 31 insertions, 2 deletions

diff --git a/debug_toolbar/panels/sql/panel.py b/debug_toolbar/panels/sql/panel.py
index 2534849..cae5214 100644
--- a/debug_toolbar/panels/sql/panel.py
+++ b/debug_toolbar/panels/sql/panel.py
@@ -10,7 +10,7 @@ from django.utils.translation import ugettext_lazy as _, ungettext_lazy as __
 from debug_toolbar.panels import Panel
 from debug_toolbar.panels.sql.forms import SQLSelectForm
 from debug_toolbar.utils import render_stacktrace
-from debug_toolbar.panels.sql.utils import reformat_sql
+from debug_toolbar.panels.sql.utils import reformat_sql, contrasting_color_generator
 from debug_toolbar.panels.sql.tracking import wrap_cursor, unwrap_cursor
 
 
@@ -136,6 +136,8 @@ class SQLPanel(Panel):
             unwrap_cursor(connection)
 
     def process_response(self, request, response):
+        colors = contrasting_color_generator()
+        trace_colors = {}
         if self._queries:
             width_ratio_tally = 0
             factor = int(256.0 / (len(self._databases) * 2.5))
@@ -196,6 +198,11 @@ class SQLPanel(Panel):
                 query['stacktrace'] = render_stacktrace(query['stacktrace'])
                 i += 1
 
+                if not trace_colors.get(query['stacktrace']):
+                    c = colors.next()
+                    trace_colors[query['stacktrace']] = c
+                query['trace_color'] = trace_colors[query['stacktrace']]
+
             if trans_id:
                 self._queries[(i - 1)][1]['ends_trans'] = True
 
diff --git a/debug_toolbar/panels/sql/utils.py b/debug_toolbar/panels/sql/utils.py
index 3943168..d6f0173 100644
--- a/debug_toolbar/panels/sql/utils.py
+++ b/debug_toolbar/panels/sql/utils.py
@@ -35,3 +35,25 @@ def swap_fields(sql):
             r'<a class="djDebugCollapsed djDebugToggle" href="#">\1</a> '
             r'<strong>FROM')
     return re.sub(expr, subs, sql)
+
+
+def contrasting_color_generator():
+    """
+    Generate constrasting colors by varying most significant bit of RGB first,
+    and then vary subsebequent bits systematically.
+    """
+    def rgb_to_hex(rgb):
+        return '#%02x%02x%02x' % tuple(rgb)
+
+    triples = [(1, 0, 0), (0, 1, 0), (0, 0, 1),
+               (1, 1, 0), (0, 1, 1), (1, 0, 1), (1, 1, 1)]
+    n = 128
+    so_far = [[0, 0, 0]]
+    while (1):
+        copy_so_far = list(so_far)
+        for triple in triples:
+            for previous in copy_so_far:
+                rgb = [n * triple[i] + previous[i] for i in range(3)]
+                so_far.append(rgb)
+                yield rgb_to_hex(rgb)
+        n = n / 2
diff --git a/debug_toolbar/templates/debug_toolbar/panels/sql.html b/debug_toolbar/templates/debug_toolbar/panels/sql.html
index f927e5d..4d95a80 100644
--- a/debug_toolbar/templates/debug_toolbar/panels/sql.html
+++ b/debug_toolbar/templates/debug_toolbar/panels/sql.html
@@ -34,7 +34,7 @@
 						</div>
 					</td>
 					<td class="timeline">
-						<div class="djDebugTimeline"><div class="djDebugLineChart{% if query.is_slow %} djDebugLineChartWarning{% endif %}" style="left:{{ query.start_offset|unlocalize }}%;"><strong style="width:{{ query.width_ratio_relative|unlocalize }}%;">{{ query.width_ratio }}%</strong></div></div>
+						<div class="djDebugTimeline"><div class="djDebugLineChart{% if query.is_slow %} djDebugLineChartWarning{% endif %}" style="left:{{ query.start_offset|unlocalize }}%;"><strong style="width:{{ query.width_ratio_relative|unlocalize }}%; background-color:{{ query.trace_color }};">{{ query.width_ratio }}%</strong></div></div>
 					</td>
 					<td class="time">
 						{{ query.duration|floatformat:"2" }}