Put histogram code in disk_cache on a diet.

The CACHE_UMA macro expanded wildly and with all the static variables
in all blocks it was impossible for the compiler to shrink it. This
removes the static variables (for a minor performance hit) to save 75%
of the size of BackendImpl::ReportStats() and other changes elsewhere.

Examples (sorry, don't have data for symbols smaller than 6 KB so not exact):
disk_cache::BackendImpl::ReportStats()  55423 bytes -> 9788 bytes
disk_cache::BackendImpl::FirstEviction() 21361 bytes -> < 6 KB
disk_cache::BackendImpl::OpenEntryImpl: 16381 bytes -> < 6 KB
disk_cache::EntryImpl::ReportIOTime: 14626 bytes -> < 6 KB
disk_cache::Eviction::ReportListStats: 10099 bytes -> < 6 KB
disk_cache::Eviction::TrimCacheV2: 7820 bytes -> < 6 KB
disk_cache::Eviction::TrimCache: 7095 bytes -> < 6 KB

In total my stripped Linux x64 Release content_shell binary shrinks by 132 KB with this change (0.25%).

BUG=352555

R=gavinp@chromium.org

Review URL: https://codereview.chromium.org/196383016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257637 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 7 insertions, 24 deletions

diff --git a/net/disk_cache/blockfile/histogram_macros.h b/net/disk_cache/blockfile/histogram_macros.h
index a5d6f56..ecffc8f 100644
--- a/net/disk_cache/blockfile/histogram_macros.h
+++ b/net/disk_cache/blockfile/histogram_macros.h
@@ -14,16 +14,11 @@
 // -----------------------------------------------------------------------------
 
 // 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.
-// Note: These macros are only run on one thread, so the declarations of
-// |counter| was made static (i.e., there will be no race for reinitialization).
+// the counter is not cached locally.
 
 #define CACHE_HISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count) \
     do { \
-      static base::HistogramBase* counter(NULL); \
-      if (!counter || name != counter->histogram_name()) \
-        counter = base::Histogram::FactoryGet( \
+      base::HistogramBase* counter = base::Histogram::FactoryGet( \
             name, min, max, bucket_count, \
             base::Histogram::kUmaTargetedHistogramFlag); \
       counter->Add(sample); \
@@ -40,9 +35,7 @@
 
 #define CACHE_HISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count) \
     do { \
-      static base::HistogramBase* counter(NULL); \
-      if (!counter || name != counter->histogram_name()) \
-        counter = base::Histogram::FactoryTimeGet( \
+      base::HistogramBase* counter = base::Histogram::FactoryTimeGet( \
             name, min, max, bucket_count, \
             base::Histogram::kUmaTargetedHistogramFlag); \
       counter->AddTime(sample); \
@@ -53,9 +46,7 @@
     base::TimeDelta::FromSeconds(10), 50)
 
 #define CACHE_HISTOGRAM_ENUMERATION(name, sample, boundary_value) do { \
-    static base::HistogramBase* counter(NULL); \
-    if (!counter || name != counter->histogram_name()) \
-      counter = base::LinearHistogram::FactoryGet( \
+    base::HistogramBase* counter = base::LinearHistogram::FactoryGet( \
                     name, 1, boundary_value, boundary_value + 1, \
                     base::Histogram::kUmaTargetedHistogramFlag); \
     counter->Add(sample); \
@@ -98,24 +89,16 @@
     const std::string my_name =\
         CACHE_UMA_BACKEND_IMPL_OBJ->HistogramName(name, experiment);\
     switch (CACHE_UMA_BACKEND_IMPL_OBJ->cache_type()) {\
+      default:\
+        NOTREACHED();\
+        /* Fall-through. */\
       case net::DISK_CACHE:\
-        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
-        break;\
       case net::MEDIA_CACHE:\
-        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
-        break;\
       case net::APP_CACHE:\
-        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
-        break;\
       case net::SHADER_CACHE:\
-        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
-        break;\
       case net::PNACL_CACHE:\
         CACHE_HISTOGRAM_##type(my_name.data(), sample);\
         break;\
-      default:\
-        NOTREACHED();\
-        break;\
     }\
   }