Disk Cache: Split some time histograms in groups based...

net/disk_cache/backend_impl.cc

Index: net/disk_cache/backend_impl.cc
===================================================================
--- net/disk_cache/backend_impl.cc	(revision 19175)
+++ net/disk_cache/backend_impl.cc	(working copy)
@@ -361,7 +361,7 @@
   DCHECK(entry);
   *entry = cache_entry;
 
-  CACHE_UMA(AGE_MS, "OpenTime", 0, start);
+  CACHE_UMA(AGE_MS, "OpenTime", GetSizeGroup(), start);
   stats_.OnEvent(Stats::OPEN_HIT);
   return true;
 }
@@ -439,7 +439,7 @@
 
   cache_entry.swap(reinterpret_cast<EntryImpl**>(entry));
 
-  CACHE_UMA(AGE_MS, "CreateTime", 0, start);
+  CACHE_UMA(AGE_MS, "CreateTime", GetSizeGroup(), start);
   stats_.OnEvent(Stats::CREATE_HIT);
   Trace("create entry hit ");
   return true;
@@ -750,6 +750,17 @@
   return StringPrintf("DiskCache.%d.%s_%d", cache_type_, name, experiment);
 }
 
+int BackendImpl::GetSizeGroup() {
+  if (disabled_)
+    return 0;
+
+  // We want to report times grouped by the current cache size (50 MB groups).
+  int group = data_->header.num_bytes / (50 * 1024 * 1024);
+  if (group > 6)
+    group = 6;  // Limit the number of groups, just in case.
+  return group;
+}
+
 // We want to remove biases from some histograms so we only send data once per
 // week.
 bool BackendImpl::ShouldReportAgain() {