Histograms for DOMStorage access

content/renderer/renderer_webstoragearea_impl.cc

Index: content/renderer/renderer_webstoragearea_impl.cc
diff --git a/content/renderer/renderer_webstoragearea_impl.cc b/content/renderer/renderer_webstoragearea_impl.cc
index d3063ecf9af3a4df50e982dfc942aa55e6819219..bd4d03b7b84c8410c9805afc6b31c80b19582ee1 100644
--- a/content/renderer/renderer_webstoragearea_impl.cc
+++ b/content/renderer/renderer_webstoragearea_impl.cc
@@ -4,6 +4,8 @@
 
 #include "content/renderer/renderer_webstoragearea_impl.h"
 
+#include "base/metrics/histogram.h"
+#include "base/time.h"
 #include "content/common/dom_storage_messages.h"
 #include "content/renderer/render_thread_impl.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebStorageNamespace.h"
@@ -25,22 +27,28 @@ RendererWebStorageAreaImpl::~RendererWebStorageAreaImpl() {
 
 unsigned RendererWebStorageAreaImpl::length() {
   unsigned length;
+  base::Time start = base::Time::Now();
   RenderThreadImpl::current()->Send(
       new DOMStorageHostMsg_Length(storage_area_id_, &length));
+  UMA_HISTOGRAM_TIMES("DOMStorage.length", base::Time::Now() - start);

[darin (slow to review), 2011/11/01 05:31:49]

it seems like we should have a convenience macro for cases like this:

  UMA_HISTOGRAM_TIMES_FOR_SCOPE

it could lay down a class, who's constructor would initialize the start time,
and who's destructor would do what UMA_HISTOGRAM_TIMES does.

[cbentzel, 2011/11/01 11:37:52]

Yes. I'll see how common this is. Most of the timing histograms I've added have
straddled across async callbacks, so the macro would not be useful then unless
it could get tied to a scoped_ptr.  

   return length;
 }
 
 WebString RendererWebStorageAreaImpl::key(unsigned index) {
   NullableString16 key;
+  base::Time start = base::Time::Now();
   RenderThreadImpl::current()->Send(
       new DOMStorageHostMsg_Key(storage_area_id_, index, &key));
+  UMA_HISTOGRAM_TIMES("DOMStorage.key", base::Time::Now() - start);
   return key;
 }
 
 WebString RendererWebStorageAreaImpl::getItem(const WebString& key) {
   NullableString16 value;
+  base::Time start = base::Time::Now();
   RenderThreadImpl::current()->Send(
       new DOMStorageHostMsg_GetItem(storage_area_id_, key, &value));
+  UMA_HISTOGRAM_TIMES("DOMStorage.getItem", base::Time::Now() - start);
   return value;
 }
 
@@ -53,21 +61,27 @@ void RendererWebStorageAreaImpl::setItem(
     return;
   }
   NullableString16 old_value;
+  base::Time start = base::Time::Now();
   RenderThreadImpl::current()->Send(new DOMStorageHostMsg_SetItem(
       storage_area_id_, key, value, url, &result, &old_value));
+  UMA_HISTOGRAM_TIMES("DOMStorage.setItem", base::Time::Now() - start);
   old_value_webkit = old_value;
 }
 
 void RendererWebStorageAreaImpl::removeItem(
     const WebString& key, const WebURL& url, WebString& old_value_webkit) {
   NullableString16 old_value;
+  base::Time start = base::Time::Now();
   RenderThreadImpl::current()->Send(
       new DOMStorageHostMsg_RemoveItem(storage_area_id_, key, url, &old_value));
+  UMA_HISTOGRAM_TIMES("DOMStorage.removeItem", base::Time::Now() - start);
   old_value_webkit = old_value;
 }
 
 void RendererWebStorageAreaImpl::clear(
     const WebURL& url, bool& cleared_something) {
+  base::Time start = base::Time::Now();
   RenderThreadImpl::current()->Send(
       new DOMStorageHostMsg_Clear(storage_area_id_, url, &cleared_something));
+  UMA_HISTOGRAM_TIMES("DOMStorage.clear", base::Time::Now() - start);
 }