Histogram first paint PLT's for Cache Sensitivity Analysis.

chrome/renderer/page_load_histograms.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/renderer/page_load_histograms.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
@@ skipping 226 matching lines @@
   PLT_HISTOGRAM("PLT.StartToCommit", start_to_commit);
   PLT_HISTOGRAM("PLT.CommitToFinishDoc", finish_doc - commit);
   PLT_HISTOGRAM("PLT.FinishDocToFinish", finish_all_loads - finish_doc);
   PLT_HISTOGRAM("PLT.BeginToCommit", commit - begin);
   PLT_HISTOGRAM("PLT.StartToFinish", start_to_finish_all_loads);
   if (!request.is_null()) {
     PLT_HISTOGRAM("PLT.RequestToStart", start - request);
     PLT_HISTOGRAM("PLT.RequestToFinish", finish_all_loads - request);
   }
   PLT_HISTOGRAM("PLT.CommitToFinish", finish_all_loads - commit);
+
+  scoped_ptr<TimeDelta> begin_to_first_paint;

[rvargas (doing something else), 2012/12/04 22:55:48]

How about TimeDelta foo = TimeDelta::FromInternalValue(-1) (really hacky!) or
keeping a boolean to signal initialization (cleaner).

[tburkard, 2012/12/04 23:09:08]

I thought about both of these, and I find scoped_ptr's more elegant. Unless you
feel really strongly about one of these alternatives.

[James Hawkins, 2012/12/04 23:11:56]

I'm fine w/ scoped_ptr.  NULLness (or non-) indicates readiness of the contained
data.

+  scoped_ptr<TimeDelta> commit_to_first_paint;
   if (!first_paint.is_null()) {
     // 'first_paint' can be before 'begin' for an unknown reason.
     // See bug http://crbug.com/125273 for details.
     if (begin <= first_paint) {
-      PLT_HISTOGRAM("PLT.BeginToFirstPaint", first_paint - begin);
+      begin_to_first_paint.reset(new TimeDelta(first_paint - begin));
+      PLT_HISTOGRAM("PLT.BeginToFirstPaint", *begin_to_first_paint);
     }
     DCHECK(commit <= first_paint);
-    PLT_HISTOGRAM("PLT.CommitToFirstPaint", first_paint - commit);
+    commit_to_first_paint.reset(new TimeDelta(first_paint - commit));
+    PLT_HISTOGRAM("PLT.CommitToFirstPaint", *commit_to_first_paint);
   }
   if (!first_paint_after_load.is_null()) {
     // 'first_paint_after_load' can be before 'begin' for an unknown reason.
     // See bug http://crbug.com/125273 for details.
     if (begin <= first_paint_after_load) {
       PLT_HISTOGRAM("PLT.BeginToFirstPaintAfterLoad",
           first_paint_after_load - begin);
     }
     DCHECK(commit <= first_paint_after_load);
     PLT_HISTOGRAM("PLT.CommitToFirstPaintAfterLoad",
@@ skipping 537 matching lines @@
   // Record histograms for cache sensitivity analysis.
   static const bool cache_sensitivity_histogram =
       base::FieldTrialList::TrialExists("CacheSensitivityAnalysis");
   if (cache_sensitivity_histogram) {
     PLT_HISTOGRAM(base::FieldTrial::MakeName(
         "PLT.BeginToFinishDoc_CacheSensitivity", "CacheSensitivityAnalysis"),
                   begin_to_finish_doc);
     PLT_HISTOGRAM(base::FieldTrial::MakeName(
         "PLT.BeginToFinish_CacheSensitivity", "CacheSensitivityAnalysis"),
                   begin_to_finish_all_loads);
+    if (begin_to_first_paint.get()) {
+    PLT_HISTOGRAM(base::FieldTrial::MakeName(
+        "PLT.BeginToFirstPaint_CacheSensitivity", "CacheSensitivityAnalysis"),
+                  *begin_to_first_paint);
+    }
+    if (commit_to_first_paint.get()) {
+      PLT_HISTOGRAM(base::FieldTrial::MakeName(
+        "PLT.CommitToFirstPaint_CacheSensitivity", "CacheSensitivityAnalysis"),
+                    *commit_to_first_paint);
+    }
   }
 
   // Since there are currently no guarantees that renderer histograms will be
   // sent to the browser, we initiate a PostTask here to be sure that we send
   // the histograms we generated.  Without this call, pages that don't have an
   // on-close-handler might generate data that is lost when the renderer is
   // shutdown abruptly (perchance because the user closed the tab).
   // TODO(jar) BUG=33233: This needs to be moved to a PostDelayedTask, and it
   // should post when the onload is complete, so that it doesn't interfere with
   // the next load.
@@ skipping 27 matching lines @@
 
   DCHECK(document_state);
   DCHECK(ds);
   GURL url(ds->request().url());
   Time start = document_state->start_load_time();
   Time finish = document_state->finish_load_time();
   // TODO(mbelshe): should we log more stats?
   VLOG(1) << "PLT: " << (finish - start).InMilliseconds() << "ms "
           << url.spec();
 }