Move prerender histograms out of prerender manager.

chrome/browser/prerender/prerender_histograms.cc

Index: chrome/browser/prerender/prerender_histograms.cc
===================================================================
--- chrome/browser/prerender/prerender_histograms.cc	(revision 0)
+++ chrome/browser/prerender/prerender_histograms.cc	(revision 0)
@@ -0,0 +1,214 @@
+// Copyright (c) 2011 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/browser/prerender/prerender_histograms.h"
+
+#include <string>
+
+#include "base/metrics/field_trial.h"
+#include "base/metrics/histogram.h"
+#include "chrome/browser/prerender/prerender_util.h"
+
+namespace prerender {
+
+namespace {
+
+// Time window for which we will record windowed PLT's from the last
+// observed link rel=prefetch tag.
+const int kWindowDurationSeconds = 30;
+
+std::string ComposeHistogramName(const std::string& prefix_type,
+                                 const std::string& name) {
+  if (prefix_type.empty())
+    return std::string("Prerender.") + name;
+  return std::string("Prerender.") + prefix_type + std::string("_") + name;
+}
+
+std::string GetHistogramName(Origin origin, uint8 experiment_id,
+                             const std::string& name) {
+  switch (origin) {
+    case ORIGIN_OMNIBOX:
+      if (experiment_id != kNoExperiment)
+        return ComposeHistogramName("wash", name);
+      return ComposeHistogramName("omnibox", name);
+    case ORIGIN_LINK_REL_PRERENDER:
+      if (experiment_id != kNoExperiment)
+        return ComposeHistogramName("wash", name);
+      return ComposeHistogramName("", name);
+    case ORIGIN_GWS_PRERENDER:
+      if (experiment_id == kNoExperiment)
+        return ComposeHistogramName("gws", name);
+      return ComposeHistogramName("exp" + std::string(1, experiment_id + '0'),
+                                  name);
+    default:
+      NOTREACHED();
+      break;
+  };
+
+  // Dummy return value to make the compiler happy.
+  NOTREACHED();
+  return ComposeHistogramName("wash", name);
+}
+
+}  // namespace
+
+// Helper macros for experiment-based and origin-based histogram reporting.
+#define PREFIXED_HISTOGRAM(histogram) \
+  PREFIXED_HISTOGRAM_INTERNAL(GetCurrentOrigin(), GetCurrentExperimentId(), \
+                              IsOriginExperimentWash(), histogram)
+
+#define PREFIXED_HISTOGRAM_ORIGIN_EXPERIMENT(origin, experiment, histogram) \
+  PREFIXED_HISTOGRAM_INTERNAL(origin, experiment, false, histogram)
+
+#define PREFIXED_HISTOGRAM_INTERNAL(origin, experiment, wash, histogram) { \
+  static uint8 recording_experiment = kNoExperiment; \
+  if (recording_experiment == kNoExperiment && experiment != kNoExperiment) \
+    recording_experiment = experiment; \
+  if (wash) { \
+    histogram; \
+  } else if (experiment != kNoExperiment && \
+             (origin != ORIGIN_GWS_PRERENDER || \
+              experiment != recording_experiment)) { \
+  } else if (origin == ORIGIN_LINK_REL_PRERENDER) { \
+    histogram; \
+  } else if (origin == ORIGIN_OMNIBOX) { \
+    histogram; \
+  } else if (experiment != kNoExperiment) { \
+    histogram; \
+  } else { \
+    histogram; \
+  } \
+}
+
+PrerenderHistograms::PrerenderHistograms()
+    : last_experiment_id_(kNoExperiment),
+      last_origin_(ORIGIN_LINK_REL_PRERENDER),
+      origin_experiment_wash_(false) {
+}
+
+void PrerenderHistograms::RecordPrerender(Origin origin, const GURL& url) {
+  // Check if we are doing an experiment.
+  uint8 experiment = GetQueryStringBasedExperiment(url);
+
+  // We need to update last_experiment_id_, last_origin_, and
+  // origin_experiment_wash_.
+  if (!WithinWindow()) {
+    // If we are outside a window, this is a fresh start and we are fine,
+    // and there is no mix.
+    origin_experiment_wash_ = false;
+  } else {
+    // If we are inside the last window, there is a mish mash of origins
+    // and experiments if either there was a mish mash before, or the current
+    // experiment/origin does not match the previous one.
+    if (experiment != last_experiment_id_ || origin != last_origin_)
+      origin_experiment_wash_ = true;
+  }
+
+  last_origin_ = origin;
+  last_experiment_id_ = experiment;
+
+  // If we observe multiple tags within the 30 second window, we will still
+  // reset the window to begin at the most recent occurrence, so that we will
+  // always be in a window in the 30 seconds from each occurrence.
+  last_prerender_seen_time_ = GetCurrentTimeTicks();
+}
+
+base::TimeTicks PrerenderHistograms::GetCurrentTimeTicks() const {
+  return base::TimeTicks::Now();
+}
+
+// Helper macro for histograms.
+#define RECORD_PLT(tag, perceived_page_load_time) { \
+  PREFIXED_HISTOGRAM( \
+    UMA_HISTOGRAM_CUSTOM_TIMES( \
+        base::FieldTrial::MakeName(GetDefaultHistogramName(tag), "Prefetch"), \
+        perceived_page_load_time, \
+        base::TimeDelta::FromMilliseconds(10), \
+        base::TimeDelta::FromSeconds(60), \
+        100)); \
+}
+
+void PrerenderHistograms::RecordPerceivedPageLoadTime(
+    base::TimeDelta perceived_page_load_time, bool was_prerender) const {
+  bool within_window = WithinWindow();
+  RECORD_PLT("PerceivedPLT", perceived_page_load_time);
+  if (within_window)
+    RECORD_PLT("PerceivedPLTWindowed", perceived_page_load_time);
+  if (was_prerender) {
+    RECORD_PLT("PerceivedPLTMatched", perceived_page_load_time);
+  } else {
+    if (within_window)
+      RECORD_PLT("PerceivedPLTWindowNotMatched", perceived_page_load_time);
+  }
+}
+
+bool PrerenderHistograms::WithinWindow() const {
+  if (last_prerender_seen_time_.is_null())
+    return false;
+  base::TimeDelta elapsed_time =
+      base::TimeTicks::Now() - last_prerender_seen_time_;
+  return elapsed_time <= base::TimeDelta::FromSeconds(kWindowDurationSeconds);
+}
+
+
+void PrerenderHistograms::RecordTimeUntilUsed(
+    base::TimeDelta time_until_used, base::TimeDelta max_age) const {
+  PREFIXED_HISTOGRAM(UMA_HISTOGRAM_CUSTOM_TIMES(
+      GetDefaultHistogramName("TimeUntilUsed"),
+      time_until_used,
+      base::TimeDelta::FromMilliseconds(10),
+      max_age,
+      50));
+}
+
+void PrerenderHistograms::RecordPerSessionCount(int count) const {
+  PREFIXED_HISTOGRAM(UMA_HISTOGRAM_COUNTS(
+      GetDefaultHistogramName("PrerendersPerSessionCount"), count));
+}
+
+void PrerenderHistograms::RecordTimeBetweenPrerenderRequests(
+    base::TimeDelta time) const {
+  PREFIXED_HISTOGRAM(UMA_HISTOGRAM_TIMES(
+      GetDefaultHistogramName("TimeBetweenPrerenderRequests"), time));
+}
+
+void PrerenderHistograms::RecordFinalStatus(Origin origin,
+                                            uint8 experiment_id,
+                                            FinalStatus final_status) const {
+  DCHECK(final_status != FINAL_STATUS_MAX);
+  PREFIXED_HISTOGRAM_ORIGIN_EXPERIMENT(origin, experiment_id,
+                     UMA_HISTOGRAM_ENUMERATION(
+                         GetHistogramName(origin, experiment_id, "FinalStatus"),
+                         final_status,
+                         FINAL_STATUS_MAX));
+}
+
+std::string PrerenderHistograms::GetDefaultHistogramName(
+    const std::string& name) const {
+  if (!WithinWindow())
+    return ComposeHistogramName("", name);
+  if (origin_experiment_wash_)
+    return ComposeHistogramName("wash", name);
+  return GetHistogramName(last_origin_, last_experiment_id_, name);
+}
+
+uint8 PrerenderHistograms::GetCurrentExperimentId() const {
+  if (!WithinWindow())
+    return kNoExperiment;
+  return last_experiment_id_;
+}
+
+Origin PrerenderHistograms::GetCurrentOrigin() const {
+  if (!WithinWindow())
+    return ORIGIN_LINK_REL_PRERENDER;
+  return last_origin_;
+}
+
+bool PrerenderHistograms::IsOriginExperimentWash() const {
+  if (!WithinWindow())
+    return false;
+  return origin_experiment_wash_;
+}
+
+}  // namespace prerender