Battery impact UMA

content/browser/power_usage_monitor_impl.cc

+// Copyright 2014 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 "content/browser/power_usage_monitor_impl.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram.h"
+#include "base/strings/stringprintf.h"
+#include "base/time/time.h"
+#include "content/common/battery_status_messages.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/notification_service.h"
+#include "content/public/browser/notification_source.h"
+#include "content/public/browser/notification_types.h"
+#include "content/public/browser/power_usage_monitor.h"
+#include "content/public/browser/render_process_host.h"
+
+namespace content {
+
+void StartPowerUsageMonitor() {
+  PowerUsageMonitor::GetInstance()->Initialize();
+}
+
+PowerUsageMonitor::HistogramRecorder::HistogramRecorder() :
+    weak_ptr_factory_(this) {
+}
+
+PowerUsageMonitor::HistogramRecorder::~HistogramRecorder() {
+}
+
+void PowerUsageMonitor::HistogramRecorder::CancelPendingHistgramReports() {
+  weak_ptr_factory_.InvalidateWeakPtrs();
+}
+
+void PowerUsageMonitor::HistogramRecorder::ReportBatteryLevelHistogram(
+    base::TimeDelta discharge_time) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  const std::string histogram_name =
+      base::StringPrintf("Power.BatteryDischarge_%d",
+      discharge_time.InMinutes());
+  base::HistogramBase* histogram = base::Histogram::FactoryGet(
+      histogram_name,
+      0,
+      100,
+      102,
+      base::Histogram::kUmaTargetedHistogramFlag);
+  double discharge_amount =
+      PowerUsageMonitor::GetInstance()->DischargeAmount();
+  histogram->Add(discharge_amount * 100);
+
+  PowerUsageMonitor::GetInstance()->BatteryLevelReported();
+}
+
+
+PowerUsageMonitor::PowerUsageMonitor() :

[Daniel Erat, 2014/09/30 23:55:24]

fix style here (please read the chromium and google c++ style guides)

+  histogram_recorder_(new HistogramRecorder()),
+  was_on_battery_power_(false),
+  initial_battery_level_(0),
+  current_battery_level_(0) {
+
+  // PowerUsageMonitor gets battery level information.
+  callback_ = base::Bind(&PowerUsageMonitor::OnBatteryStatusUpdate,
+                         base::Unretained(this));
+
+  // Power Monitor used to get suspend/resume notifications.
+  base::PowerMonitor::Get()->AddObserver(this);
+
+  registrar_.Add(this,
+                 NOTIFICATION_RENDERER_PROCESS_CREATED,
+                 NotificationService::AllBrowserContextsAndSources());
+
+  registrar_.Add(this,
+                 NOTIFICATION_RENDERER_PROCESS_TERMINATED,
+                 NotificationService::AllBrowserContextsAndSources());
+  registrar_.Add(this,
+                 NOTIFICATION_RENDERER_PROCESS_CLOSED,
+                 NotificationService::AllBrowserContextsAndSources());
+}
+
+PowerUsageMonitor::~PowerUsageMonitor() {
+  base::PowerMonitor::Get()->RemoveObserver(this);
+}
+
+PowerUsageMonitor* PowerUsageMonitor::GetInstance() {
+  return Singleton<PowerUsageMonitor,
+                   LeakySingletonTraits<PowerUsageMonitor> >::get();
+}
+
+void PowerUsageMonitor::Initialize() {
+  const base::TimeDelta delay = base::TimeDelta::FromSeconds(1);
+
+  BrowserThread::PostDelayedTask(BrowserThread::IO,
+      FROM_HERE, base::Bind(&PowerUsageMonitor::StartOnIOThread,
+          base::Unretained(this)), delay);
+}
+
+void PowerUsageMonitor::StartOnIOThread() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  subscription_ =
+      BatteryStatusService::GetInstance()->AddCallback(callback_);
+}
+
+void PowerUsageMonitor::DischargeStarted(double battery_level) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  // Cancel any in-progress ReportBatteryLevelHistogram() calls.
+  histogram_recorder_->CancelPendingHistgramReports();
+
+  // Rate-limit power recording to once every 24 hours.
+  if (!first_histogram_report_timestamp_.is_null()) {
+    base::TimeDelta time_since_last_report =
+        base::Time::Now() - first_histogram_report_timestamp_;
+    if (time_since_last_report.InHours() < 24)
+      return;
+
+    // More than 24 hours have passed, reset timestamp.
+    first_histogram_report_timestamp_ = base::Time();
+  }
+
+  was_on_battery_power_ = true;
+  initial_battery_level_ = battery_level;
+  current_battery_level_ = battery_level;
+  start_discharge_time_ = base::Time::Now();
+
+  const int kBatteryReportingIntervalMinutes[] = {5, 15, 30};
+
+  for (size_t i = 0; i < arraysize(kBatteryReportingIntervalMinutes); ++i) {
+    base::TimeDelta delay =
+        base::TimeDelta::FromMinutes(kBatteryReportingIntervalMinutes[i]);
+    BrowserThread::PostDelayedTask(BrowserThread::IO,

[Daniel Erat, 2014/09/30 23:55:24]

can you move this into HistogramRecorder so it doesn't need to expose its weak
pointers publicly?

+        FROM_HERE, base::Bind(
+            &PowerUsageMonitor::HistogramRecorder::ReportBatteryLevelHistogram,
+             histogram_recorder_->GetWeakPtr(), delay), delay);
+  }
+}
+
+void PowerUsageMonitor::WallPowerConnected(double battery_level) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  // Cancel any in-progress ReportBatteryLevelHistogram() calls.
+  histogram_recorder_->CancelPendingHistgramReports();
+
+  if (!start_discharge_time_.is_null()) {
+    base::TimeDelta discharge_time = base::Time::Now() - start_discharge_time_;
+    double discharge_percent = initial_battery_level_ - battery_level;
+    double discharge_rate = discharge_percent / discharge_time.InMinutes();
+
+    if (discharge_time.InMinutes() > 30)

[Daniel Erat, 2014/09/30 23:55:24]

need curly brackets here

+      UMA_HISTOGRAM_PERCENTAGE("Power.BatteryDischargeRateWhenUnplugged",
+          discharge_rate * 100.0);
+  }
+
+  was_on_battery_power_ = false;
+  initial_battery_level_ = 0;
+  current_battery_level_ = 0;
+  start_discharge_time_ = base::Time();
+}
+
+void PowerUsageMonitor::OnBatteryStatusUpdate(
+    const blink::WebBatteryStatus& status) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  bool now_on_battery_power = (status.charging == 0);
+  double battery_level = status.level;
+
+  if (now_on_battery_power == was_on_battery_power_) {
+    if (now_on_battery_power)
+      current_battery_level_ = battery_level;
+    return;
+  } else if (now_on_battery_power) {  // Wall power disconnected.
+    DischargeStarted(battery_level);
+  } else { // Wall power connected.
+    WallPowerConnected(battery_level);
+  }
+}
+
+void PowerUsageMonitor::BatteryLevelReported() {
+  if (first_histogram_report_timestamp_.is_null()) {
+    // Record timestamp of first histogram report.
+    first_histogram_report_timestamp_ = base::Time::Now();
+  }
+}
+
+void PowerUsageMonitor::SetHistogramRecorderForTest(
+    scoped_ptr<HistogramRecorder> recorder) {
+  histogram_recorder_ = recorder.Pass();
+}
+
+void PowerUsageMonitor::OnSuspend() {
+  BrowserThread::PostTask(BrowserThread::IO,
+      FROM_HERE,
+          base::Bind(

[Daniel Erat, 2014/09/30 23:55:24]

fix weird indenting -- i recommend clang-format

+              &PowerUsageMonitor::CancelPendingHistogramRecordingOnIOThread,
+              base::Unretained(this)));
+}
+
+void PowerUsageMonitor::Observe(int type,
+                                const NotificationSource& source,
+                                const NotificationDetails& details) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  RenderProcessHost* rph =
+      Source<RenderProcessHost>(source).ptr();
+
+  size_t previous_num_live_renderers = live_renderers_.size();
+
+  if(type == NOTIFICATION_RENDERER_PROCESS_CREATED) {

[Daniel Erat, 2014/09/30 23:55:24]

nit: add a space between 'if' and '(' here and everywhere else

+    live_renderers_.insert(rph->GetID());
+  } else if(type == NOTIFICATION_RENDERER_PROCESS_TERMINATED ||
+      type == NOTIFICATION_RENDERER_PROCESS_CLOSED) {
+    live_renderers_.erase(rph->GetID());
+  }
+
+  if (live_renderers_.size() == 0 && previous_num_live_renderers != 0) {
+    // All render processes have died.
+    BrowserThread::PostTask(BrowserThread::IO,
+      FROM_HERE,

[Daniel Erat, 2014/09/30 23:55:24]

fix indenting

+          base::Bind(
+              &PowerUsageMonitor::CancelPendingHistogramRecordingOnIOThread,
+              base::Unretained(this)));
+  }
+}
+
+void PowerUsageMonitor::CancelPendingHistogramRecordingOnIOThread() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  // Cancel any in-progress histogram reports and reporting of discharge UMA.
+  histogram_recorder_->CancelPendingHistgramReports();
+  start_discharge_time_ = base::Time();
+}
+
+}  // namespace content