Per-host V8 histograms.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index db5696ef5821bc8bd93f23e49ce82fc5ce00b008..957bc42e2009d9e55d14f1aa99b1b871a793a8fc 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -159,22 +159,33 @@ class RenderViewZoomer : public content::RenderViewVisitor {
   DISALLOW_COPY_AND_ASSIGN(RenderViewZoomer);
 };
 
-}  // namespace
+std::string HostToCustomPage(const std::string& host) {

[Charlie Reis, 2012/08/22 23:09:59]

HostToCustomHistogramSuffix?

[marja, 2012/08/23 14:15:00]

Done.

+  if (host == "mail.google.com")
+    return ".gmail";
+  if (host == "docs.google.com" || host == "drive.google.com")
+    return ".docs";
+  if (host == "plus.google.com")
+    return ".plus";
+  return "";
+}
 
-static void* CreateHistogram(
+void* CreateHistogram(
     const char *name, int min, int max, size_t buckets) {
   if (min <= 0)
     min = 1;
   base::Histogram* histogram = base::Histogram::FactoryGet(
-      name, min, max, buckets, base::Histogram::kUmaTargetedHistogramFlag);
+      RenderThreadImpl::current()->ConvertToCustomHistogramName(name),
+      min, max, buckets, base::Histogram::kUmaTargetedHistogramFlag);
   return histogram;
 }
 
-static void AddHistogramSample(void* hist, int sample) {
+void AddHistogramSample(void* hist, int sample) {
   base::Histogram* histogram = static_cast<base::Histogram*>(hist);
   histogram->Add(sample);
 }
 
+}  // namespace
+
 class RenderThreadImpl::GpuVDAContextLostCallback
     : public WebKit::WebGraphicsContext3D::WebGraphicsContextLostCallback {
  public:
@@ -284,6 +295,8 @@ void RenderThreadImpl::Init() {
   if (!media_path.empty())
     media::InitializeMediaLibrary(media_path);
 
+  InitializeCustomHistograms();
+
   TRACE_EVENT_END_ETW("RenderThreadImpl::Init", 0, "");
 }
 
@@ -812,6 +825,28 @@ RenderThreadImpl::GetAudioRendererMixerManager() {
   return audio_renderer_mixer_manager_.get();
 }
 
+void RenderThreadImpl::RenderViewNavigatedToHost(const std::string& host,
+                                                 size_t view_count) {
+  // Check if all RenderViews are displaying a page from the same host. If there
+  // is only one RenderView, the common host is this view's host. If there are
+  // many, check if this one shares the common host of the other
+  // RenderViews. It's ok to not detect some cases where the RenderViews share a

[Charlie Reis, 2012/08/22 23:09:59]

I'm glad you have this disclaimer.  One case that comes to mind is opening a
second render view in the same process before the first one commits, in which
case you'll never have a common host, even if they both commit to the same host.
 That's fine (and likely rare), though.

[marja, 2012/08/23 14:15:00]

Ack. Yes, we don't need to catch all the possible cases where we could produce a
custom histogram.

+  // common host. This information is only used for producing custom histograms.
+  if (view_count == 1)
+    SetCommonHost(host);
+  else if (host != common_host_)
+    SetCommonHost(std::string());
+}
+
+std::string RenderThreadImpl::ConvertToCustomHistogramName(
+    const char* histogram_name) {
+  std::string name(histogram_name);
+  if (!custom_page_.empty() &&
+      custom_histograms_.find(name) != custom_histograms_.end())

[Charlie Reis, 2012/08/22 23:09:59]

nit: Condition doesn't fit on one line, so needs braces.

[marja, 2012/08/23 14:15:00]

counter-nit: Doesn't it only needs braces if the *body* doesn't fit on one line?

[Charlie Reis, 2012/08/23 16:30:39]

Ah, ambiguous style guides!  :)  Looks like there was a thread on this in
November 2010:

https://groups.google.com/a/chromium.org/forum/?fromgroups=#!searchin/chromiu...

I was siding with Marc-Andre and Finnur, but it sounds like Brett and Peter
argued that braces are optional for multiline conditionals, depending on
readability.  So you're right, they're not strictly needed!

+    name += custom_page_;
+  return name;
+}
+
 #if defined(OS_WIN)
 void RenderThreadImpl::PreCacheFont(const LOGFONT& log_font) {
   Send(new ChildProcessHostMsg_PreCacheFont(log_font));
@@ -1080,3 +1115,30 @@ RenderThreadImpl::GetFileThreadMessageLoopProxy() {
   }
   return file_thread_->message_loop_proxy();
 }
+
+void RenderThreadImpl::SetCommonHost(const std::string& host) {
+  if (host != common_host_) {
+    common_host_ = host;
+    custom_page_ = HostToCustomPage(host);
+    v8::V8::SetCreateHistogramFunction(CreateHistogram);
+  }
+}
+
+void RenderThreadImpl::InitializeCustomHistograms() {
+  custom_histograms_.insert("V8.GCCompactor");
+  custom_histograms_.insert("V8.GCScavenger");
+  custom_histograms_.insert("V8.GCContext");
+  custom_histograms_.insert("V8.Parse");
+  custom_histograms_.insert("V8.ParseLazy");
+  custom_histograms_.insert("V8.PreParse");
+  custom_histograms_.insert("V8.Compile");
+  custom_histograms_.insert("V8.CompileEval");
+  custom_histograms_.insert("V8.CompileLazy");
+  custom_histograms_.insert("V8.MemoryExternalFragmentationTotal");
+  custom_histograms_.insert("V8.MemoryExternalFragmentationOldPointerSpace");
+  custom_histograms_.insert("V8.MemoryExternalFragmentationOldDataSpace");
+  custom_histograms_.insert("V8.MemoryExternalFragmentationCodeSpace");
+  custom_histograms_.insert("V8.MemoryExternalFragmentationMapSpace");
+  custom_histograms_.insert("V8.MemoryExternalFragmentationCellSpace");
+  custom_histograms_.insert("V8.MemoryExternalFragmentationLoSpace");
+}