Trace category groups and category filter.

base/debug/trace_event_impl.cc

Index: base/debug/trace_event_impl.cc
diff --git a/base/debug/trace_event_impl.cc b/base/debug/trace_event_impl.cc
index 07679d1131250fb101401191d02434dc6e59e8b8..f4d81a3f511f2247de0c3a284215a4eaff1d1a0d 100644
--- a/base/debug/trace_event_impl.cc
+++ b/base/debug/trace_event_impl.cc
@@ -393,18 +393,39 @@ const char* TraceLog::GetCategoryName(const unsigned char* category_enabled) {
   return g_categories[category_index];
 }
 
+static bool IsTagInCategory(const char* tag_expr, const char* category) {
+  CStringTokenizer tokens(category, category + strlen(category), ",");
+  while (tokens.GetNext()) {
+    if (MatchPattern(tokens.token().c_str(), tag_expr))
+      return true;
+  }
+  return false;
+}
+
+// A tag composite category name would be something like: "webkit,input"
+static bool IsTagCompositeCategory(const char* category) {
+  return strchr(category, ',');
+}
+
 static void EnableMatchingCategory(int category_index,

[nduca, 2013/01/09 09:43:33]

I'd like to update the naming convention throughout this file to be more obvious
what a given std::string is. FOr exmaple you have patterns passed in here --- is
that patterns on tags, or patterns on categories?

                                    const std::vector<std::string>& patterns,
                                    unsigned char matched_value,
                                    unsigned char unmatched_value) {
   std::vector<std::string>::const_iterator ci = patterns.begin();
   bool is_match = false;
+  bool has_matching_tag = false;
+  bool is_tag_composite_category =
+                          IsTagCompositeCategory(g_categories[category_index]);
   for (; ci != patterns.end(); ++ci) {
     is_match = MatchPattern(g_categories[category_index], ci->c_str());
-    if (is_match)

[nduca, 2013/01/09 09:43:33]

cant you make this just a change to MatchPattern? This code is insanely hard to
read. Figure out some way to make this read cleanly!

Maybe MatchPattern should be more like IsTagPatternAMatchForCategoryString()?

+    has_matching_tag = is_tag_composite_category &&
+                       IsTagInCategory(ci->c_str(),
+                                       g_categories[category_index]);
+
+    if (is_match || has_matching_tag)
       break;
   }
-  g_category_enabled[category_index] = is_match ?
+  g_category_enabled[category_index] = is_match || has_matching_tag ?
       matched_value : unmatched_value;
 }