Disk cache: Allow the disk cache histograms to generate

more than one name so that we can move a user from one
group to another within the same session.

BUG=none
TEST=unittest


Review URL: http://codereview.chromium.org/2044007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@46931 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 71 insertions, 10 deletions

diff --git a/net/disk_cache/backend_unittest.cc b/net/disk_cache/backend_unittest.cc
index 2297b9f..41c8069 100644
--- a/net/disk_cache/backend_unittest.cc
+++ b/net/disk_cache/backend_unittest.cc
@@ -13,6 +13,7 @@
 #include "net/disk_cache/backend_impl.h"
 #include "net/disk_cache/disk_cache_test_base.h"
 #include "net/disk_cache/disk_cache_test_util.h"
+#include "net/disk_cache/histogram_macros.h"
 #include "net/disk_cache/mapped_file.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -1612,3 +1613,15 @@ TEST_F(DiskCacheTest, AutomaticMaxSize) {
   EXPECT_EQ(kint32max,
             disk_cache::PreferedCacheSize(largest_size * 10000));
 }
+
+// Tests that we can "migrate" a running instance from one experiment group to
+// another.
+TEST_F(DiskCacheBackendTest, Histograms) {
+  SetDirectMode();
+  InitCache();
+  disk_cache::BackendImpl* backend_ = cache_impl_;  // Needed be the macro.
+
+  for (int i = 1; i < 3; i++) {
+    CACHE_UMA(HOURS, "FillupTime", i, 28);
+  }
+}
diff --git a/net/disk_cache/histogram_macros.h b/net/disk_cache/histogram_macros.h
index 8d5966c..bbea303 100644
--- a/net/disk_cache/histogram_macros.h
+++ b/net/disk_cache/histogram_macros.h
@@ -11,22 +11,70 @@
 #ifndef NET_DISK_CACHE_HISTOGRAM_MACROS_H_
 #define NET_DISK_CACHE_HISTOGRAM_MACROS_H_
 
+// -----------------------------------------------------------------------------
+
+// These histograms follow the definition of UMA_HISTOGRAMN_XXX except that
+// whenever the name changes (the experiment group changes), the histrogram
+// object is re-created.
+
+#define CACHE_HISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count) \
+    do { \
+      static scoped_refptr<Histogram> counter; \
+      if (!counter || name != counter->histogram_name()) \
+        counter = Histogram::FactoryGet(name, min, max, bucket_count, \
+                                        Histogram::kUmaTargetedHistogramFlag); \
+      counter->Add(sample); \
+    } while (0)
+
+#define CACHE_HISTOGRAM_COUNTS(name, sample) CACHE_HISTOGRAM_CUSTOM_COUNTS( \
+    name, sample, 1, 1000000, 50)
+
+#define CACHE_HISTOGRAM_COUNTS_10000(name, sample) \
+    CACHE_HISTOGRAM_CUSTOM_COUNTS(name, sample, 1, 10000, 50)
+
+#define CACHE_HISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count) \
+    do { \
+      static scoped_refptr<Histogram> counter; \
+      if (!counter || name != counter->histogram_name()) \
+        counter = Histogram::FactoryGet(name, min, max, bucket_count, \
+                                        Histogram::kUmaTargetedHistogramFlag); \
+      counter->AddTime(sample); \
+    } while (0)
+
+#define CACHE_HISTOGRAM_TIMES(name, sample) CACHE_HISTOGRAM_CUSTOM_TIMES( \
+    name, sample, base::TimeDelta::FromMilliseconds(1), \
+    base::TimeDelta::FromSeconds(10), 50)
+
+#define CACHE_HISTOGRAM_ENUMERATION(name, sample, boundary_value) do { \
+    static scoped_refptr<Histogram> counter; \
+    if (!counter || name != counter->histogram_name()) \
+      counter = LinearHistogram::FactoryGet( \
+                    name, 1, boundary_value, boundary_value + 1, \
+                    Histogram::kUmaTargetedHistogramFlag); \
+    counter->Add(sample); \
+  } while (0)
+
+#define CACHE_HISTOGRAM_PERCENTAGE(name, under_one_hundred) \
+    CACHE_HISTOGRAM_ENUMERATION(name, under_one_hundred, 101)
+
+// -----------------------------------------------------------------------------
+
 // HISTOGRAM_HOURS will collect time related data with a granularity of hours
 // and normal values of a few months.
-#define UMA_HISTOGRAM_HOURS UMA_HISTOGRAM_COUNTS_10000
+#define CACHE_HISTOGRAM_HOURS CACHE_HISTOGRAM_COUNTS_10000
 
 // HISTOGRAM_AGE will collect time elapsed since |initial_time|, with a
 // granularity of hours and normal values of a few months.
-#define UMA_HISTOGRAM_AGE(name, initial_time) \
-    UMA_HISTOGRAM_COUNTS_10000(name, (Time::Now() - initial_time).InHours())
+#define CACHE_HISTOGRAM_AGE(name, initial_time) \
+    CACHE_HISTOGRAM_COUNTS_10000(name, (Time::Now() - initial_time).InHours())
 
 // HISTOGRAM_AGE_MS will collect time elapsed since |initial_time|, with the
 // normal resolution of the UMA_HISTOGRAM_TIMES.
-#define UMA_HISTOGRAM_AGE_MS(name, initial_time)\
-    UMA_HISTOGRAM_TIMES(name, TimeTicks::Now() - initial_time)
+#define CACHE_HISTOGRAM_AGE_MS(name, initial_time)\
+    CACHE_HISTOGRAM_TIMES(name, TimeTicks::Now() - initial_time)
 
-#define UMA_HISTOGRAM_CACHE_ERROR(name, sample) \
-    UMA_HISTOGRAM_ENUMERATION(name, sample, 50)
+#define CACHE_HISTOGRAM_CACHE_ERROR(name, sample) \
+    CACHE_HISTOGRAM_ENUMERATION(name, sample, 50)
 
 #ifdef NET_DISK_CACHE_BACKEND_IMPL_CC_
 #define BACKEND_OBJ this
@@ -48,13 +96,13 @@
     const std::string my_name = BACKEND_OBJ->HistogramName(name, experiment);\
     switch (BACKEND_OBJ->cache_type()) {\
       case net::DISK_CACHE:\
-        UMA_HISTOGRAM_##type(my_name.data(), sample);\
+        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
         break;\
       case net::MEDIA_CACHE:\
-        UMA_HISTOGRAM_##type(my_name.data(), sample);\
+        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
         break;\
       case net::APP_CACHE:\
-        UMA_HISTOGRAM_##type(my_name.data(), sample);\
+        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
         break;\
       default:\
         NOTREACHED();\