Color-code SQL: code review changes; fallback to black after 2**24 colors

Author: wolfe

debug_toolbar/panels/sql/panel.py

@@ -2,6 +2,7 @@
 
 import uuid
 from copy import copy
+from collections import defaultdict
 
 from django.conf.urls import patterns, url
 from django.db import connections
@@ -137,7 +138,7 @@ def disable_instrumentation(self):
 
     def process_response(self, request, response):
         colors = contrasting_color_generator()
-        trace_colors = {}
+        trace_colors = defaultdict(lambda: next(colors))
         if self._queries:
             width_ratio_tally = 0
             factor = int(256.0 / (len(self._databases) * 2.5))
@@ -198,8 +199,6 @@ def process_response(self, request, response):
                 query['stacktrace'] = render_stacktrace(query['stacktrace'])
                 i += 1
 
-                if query['stacktrace'] not in trace_colors:
-                    trace_colors[query['stacktrace']] = colors.next()
                 query['trace_color'] = trace_colors[query['stacktrace']]
 
             if trans_id:

debug_toolbar/panels/sql/utils.py

@@ -40,20 +40,22 @@ def swap_fields(sql):
 def contrasting_color_generator():
     """
     Generate constrasting colors by varying most significant bit of RGB first,
-    and then vary subsebequent bits systematically.
+    and then vary subsequent 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
+    n = 1 << 7
     so_far = [[0, 0, 0]]
-    while (1):
+    while True:
+        if n == 0:  # This happens after 2**24 colours; presumably, never
+            yield "#000000"  # black
         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
+        n >>= 1