Tracing pre-filtering

base/trace_event/trace_config_unittest.cc

Index: base/trace_event/trace_config_unittest.cc
diff --git a/base/trace_event/trace_config_unittest.cc b/base/trace_event/trace_config_unittest.cc
index 1fb41f86fb9eef43d13ac122c7bff135ac8d3e04..0f5f12712a3e7a7c378ba49bb94a089d6419615d 100644
--- a/base/trace_event/trace_config_unittest.cc
+++ b/base/trace_event/trace_config_unittest.cc
@@ -5,6 +5,7 @@
 #include <stddef.h>
 
 #include "base/json/json_reader.h"
+#include "base/json/json_writer.h"
 #include "base/macros.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "base/trace_event/trace_config.h"
@@ -27,6 +28,14 @@ const char kDefaultTraceConfigString[] =
 
 const char kCustomTraceConfigString[] =
   "{"
+    "\"category_event_filters\":["
+      "{"
+        "\"args\":{\"event_name_whitelist\":[\"a snake\",\"a dog\"]},"
+        "\"excluded_categories\":[\"unfiltered_cat\"],"
+        "\"included_categories\":[\"*\"],"
+        "\"predicate\":\"event_whitelist_predicate\""

[Primiano Tucci (use gerrit), 2016/05/11 16:11:57]

maybe if these were called

predicate -> filter_predicate
args -> filter_args
would be a bit more clear. Args feels a bit too generic, this is really args for
the given predicate.

Also, I wonder if this section should just be "event_filters" instead of
"category_event_filters". I know that you want to capture the fact that the
category is somehow prioritary, but for somebody who reads this for the first
time "category_event_filters" makes it harder to guess what this is about.
The reality is that you filter by category AND event, but IMHO the category is
more a detail of the filter.

Also I think would help if in this example (and the other file below), predicate
and args were back to back, e.g. in this sequence:
 - excluded_cat
 - included_cat
 - predicate
 - args

[oystein (OOO til 10th of July), 2016/05/20 20:03:43]

Yeah, I like that better; done. The ordering I can't do much about, it has to be
alphabetical (has to be transitive when parsed to and back from JSON).

+      "}"
+    "],"
     "\"enable_argument_filter\":true,"
     "\"enable_sampling\":true,"
     "\"enable_systrace\":true,"
@@ -279,6 +288,8 @@ TEST(TraceConfigTest, ConstructDefaultTraceConfig) {
   EXPECT_TRUE(tc.IsCategoryGroupEnabled("CategoryDebug,Category1"));
   EXPECT_TRUE(tc.IsCategoryGroupEnabled("CategoryTest,not-excluded-category"));
   EXPECT_FALSE(tc.IsCategoryGroupEnabled("CategoryDebug,CategoryTest"));
+
+  EXPECT_TRUE(tc.category_event_filters().empty());
 }
 
 TEST(TraceConfigTest, TraceConfigFromDict) {
@@ -329,6 +340,14 @@ TEST(TraceConfigTest, TraceConfigFromValidString) {
   // Using some non-empty config string.
   const char config_string[] =
     "{"
+      "\"category_event_filters\":["
+        "{"
+          "\"args\":{\"event_name_whitelist\":[\"a snake\",\"a dog\"]},"
+          "\"excluded_categories\":[\"unfiltered_cat\"],"
+          "\"included_categories\":[\"*\"],"
+          "\"predicate\":\"event_whitelist_predicate\""
+        "}"
+      "],"
       "\"enable_argument_filter\":true,"
       "\"enable_sampling\":true,"
       "\"enable_systrace\":true,"
@@ -375,6 +394,23 @@ TEST(TraceConfigTest, TraceConfigFromValidString) {
   EXPECT_STREQ("test.Delay1;16", tc.GetSyntheticDelayValues()[0].c_str());
   EXPECT_STREQ("test.Delay2;32", tc.GetSyntheticDelayValues()[1].c_str());
 
+  EXPECT_EQ(tc.category_event_filters().size(), 1u);
+  const TraceConfig::CategoryEventFilterConfig& category_filter =
+      tc.category_event_filters()[0];
+  EXPECT_STREQ(category_filter.predicate_name().c_str(),
+               "event_whitelist_predicate");
+  EXPECT_EQ(category_filter.included_categories().size(), 1u);
+  EXPECT_STREQ(category_filter.included_categories()[0].c_str(), "*");
+  EXPECT_EQ(category_filter.excluded_categories().size(), 1u);
+  EXPECT_STREQ(category_filter.excluded_categories()[0].c_str(),
+               "unfiltered_cat");
+  EXPECT_TRUE(category_filter.args());
+
+  std::string json_out;
+  base::JSONWriter::Write(*category_filter.args(), &json_out);
+  EXPECT_STREQ(json_out.c_str(),
+               "{\"event_name_whitelist\":[\"a snake\",\"a dog\"]}");
+
   const char config_string_2[] = "{\"included_categories\":[\"*\"]}";
   TraceConfig tc2(config_string_2);
   EXPECT_TRUE(tc2.IsCategoryEnabled("non-disabled-by-default-pattern"));