Make SystemMonitor not a Singleton and move it out of base

SystemMonitor makes an assumption that through its lifetime a MessageLoop exists and stays the same. It is difficult and error-prone to satisfy that when it is a Singleton. It has caused problems in the past.

Additionally, extract HighResoltionTimerManager out of time_win.cc, eliminating yet another Singleton.

TEST=none
BUG=none

Review URL: http://codereview.chromium.org/431008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@33214 0039d316-1c4b-4281-b951-d872f2087c98

9 files changed, 446 insertions, 0 deletions

diff --git a/app/app.gyp b/app/app.gyp
index 78f9978..4ddfb8a 100644
--- a/app/app.gyp
+++ b/app/app.gyp
@@ -105,6 +105,9 @@
         'gfx/text_elider.h',
         'gtk_dnd_util.cc',
         'gtk_dnd_util.h',
+        'hi_res_timer_manager_posix.cc',
+        'hi_res_timer_manager_win.cc',
+        'hi_res_timer_manager.h',
         'l10n_util.cc',
         'l10n_util.h',
         'l10n_util_mac.h',
@@ -134,6 +137,10 @@
         'sql/statement.h',
         'sql/transaction.cc',
         'sql/transaction.h',
+        'system_monitor.cc',
+        'system_monitor.h',
+        'system_monitor_posix.cc',
+        'system_monitor_win.cc',
         'table_model.cc',
         'table_model.h',
         'table_model_observer.h',
@@ -244,6 +251,7 @@
         'l10n_util_unittest.cc',
         'os_exchange_data_win_unittest.cc',
         'run_all_unittests.cc',
+        'system_monitor_unittest.cc',
         'test_suite.h',
         'sql/connection_unittest.cc',
         'sql/statement_unittest.cc',
diff --git a/app/hi_res_timer_manager.h b/app/hi_res_timer_manager.h
new file mode 100644
index 0000000..17a0522
--- /dev/null
+++ b/app/hi_res_timer_manager.h
@@ -0,0 +1,29 @@
+// Copyright (c) 2009 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.
+
+#ifndef APP_HI_RES_TIMER_MANAGER_H_
+#define APP_HI_RES_TIMER_MANAGER_H_
+
+#include "app/system_monitor.h"
+
+// Ensures that the Windows high resolution timer is only used
+// when not running on battery power.
+class HighResolutionTimerManager : public SystemMonitor::PowerObserver {
+ public:
+  HighResolutionTimerManager();
+  virtual ~HighResolutionTimerManager();
+
+  // SystemMonitor::PowerObserver:
+  void OnPowerStateChange(bool on_battery_power);
+
+ private:
+  // Enable or disable the faster multimedia timer.
+  void UseHiResClock(bool use);
+
+  bool hi_res_clock_used_;
+
+  DISALLOW_COPY_AND_ASSIGN(HighResolutionTimerManager);
+};
+
+#endif  // APP_HI_RES_TIMER_MANAGER_H_
diff --git a/app/hi_res_timer_manager_posix.cc b/app/hi_res_timer_manager_posix.cc
new file mode 100644
index 0000000..f0562fd
--- /dev/null
+++ b/app/hi_res_timer_manager_posix.cc
@@ -0,0 +1,19 @@
+// Copyright (c) 2009 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 "app/hi_res_timer_manager.h"
+
+// On POSIX we don't need to do anything special with the system timer.
+
+HighResolutionTimerManager::HighResolutionTimerManager() {
+}
+
+HighResolutionTimerManager::~HighResolutionTimerManager() {
+}
+
+void HighResolutionTimerManager::OnPowerStateChange(bool on_battery_power) {
+}
+
+void HighResolutionTimerManager::UseHiResClock(bool use) {
+}
diff --git a/app/hi_res_timer_manager_win.cc b/app/hi_res_timer_manager_win.cc
new file mode 100644
index 0000000..b7cee1d
--- /dev/null
+++ b/app/hi_res_timer_manager_win.cc
@@ -0,0 +1,31 @@
+// Copyright (c) 2009 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 "app/hi_res_timer_manager.h"
+
+#include "base/time.h"
+
+HighResolutionTimerManager::HighResolutionTimerManager()
+    : hi_res_clock_used_(false) {
+  SystemMonitor* system_monitor = SystemMonitor::Get();
+  system_monitor->AddObserver(this);
+  UseHiResClock(!system_monitor->BatteryPower());
+}
+
+HighResolutionTimerManager::~HighResolutionTimerManager() {
+  SystemMonitor::Get()->RemoveObserver(this);
+  UseHiResClock(false);
+}
+
+void HighResolutionTimerManager::OnPowerStateChange(bool on_battery_power) {
+  UseHiResClock(!on_battery_power);
+}
+
+void HighResolutionTimerManager::UseHiResClock(bool use) {
+  if (use == hi_res_clock_used_)
+    return;
+  bool result = base::Time::UseHighResolutionTimer(use);
+  DCHECK(result);
+  hi_res_clock_used_ = use;
+}
diff --git a/app/system_monitor.cc b/app/system_monitor.cc
new file mode 100644
index 0000000..b0e715a
--- /dev/null
+++ b/app/system_monitor.cc
@@ -0,0 +1,98 @@
+// Copyright (c) 2009 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 "app/system_monitor.h"
+
+#include "base/logging.h"
+#include "base/message_loop.h"
+#include "base/time.h"
+
+static SystemMonitor* g_system_monitor = NULL;
+
+#if defined(ENABLE_BATTERY_MONITORING)
+// The amount of time (in ms) to wait before running the initial
+// battery check.
+static int kDelayedBatteryCheckMs = 10 * 1000;
+#endif  // defined(ENABLE_BATTERY_MONITORING)
+
+SystemMonitor::SystemMonitor()
+    : observer_list_(new ObserverListThreadSafe<PowerObserver>()),
+      battery_in_use_(false),
+      suspended_(false) {
+  DCHECK(!g_system_monitor);
+  g_system_monitor = this;
+
+  DCHECK(MessageLoop::current());
+#if defined(ENABLE_BATTERY_MONITORING)
+  delayed_battery_check_.Start(
+      base::TimeDelta::FromMilliseconds(kDelayedBatteryCheckMs), this,
+      &SystemMonitor::BatteryCheck);
+#endif  // defined(ENABLE_BATTERY_MONITORING)
+}
+
+SystemMonitor::~SystemMonitor() {
+  DCHECK_EQ(this, g_system_monitor);
+  g_system_monitor = NULL;
+}
+
+// static
+SystemMonitor* SystemMonitor::Get() {
+  return g_system_monitor;
+}
+
+void SystemMonitor::ProcessPowerMessage(PowerEvent event_id) {
+  // Suppress duplicate notifications.  Some platforms may
+  // send multiple notifications of the same event.
+  switch (event_id) {
+    case POWER_STATE_EVENT:
+      {
+        bool on_battery = IsBatteryPower();
+        if (on_battery != battery_in_use_) {
+          battery_in_use_ = on_battery;
+          NotifyPowerStateChange();
+        }
+      }
+      break;
+    case RESUME_EVENT:
+      if (suspended_) {
+        suspended_ = false;
+        NotifyResume();
+      }
+      break;
+    case SUSPEND_EVENT:
+      if (!suspended_) {
+        suspended_ = true;
+        NotifySuspend();
+      }
+      break;
+  }
+}
+
+void SystemMonitor::AddObserver(PowerObserver* obs) {
+  observer_list_->AddObserver(obs);
+}
+
+void SystemMonitor::RemoveObserver(PowerObserver* obs) {
+  observer_list_->RemoveObserver(obs);
+}
+
+void SystemMonitor::NotifyPowerStateChange() {
+  LOG(INFO) << L"PowerStateChange: "
+           << (BatteryPower() ? L"On" : L"Off") << L" battery";
+  observer_list_->Notify(&PowerObserver::OnPowerStateChange, BatteryPower());
+}
+
+void SystemMonitor::NotifySuspend() {
+  LOG(INFO) << L"Power Suspending";
+  observer_list_->Notify(&PowerObserver::OnSuspend);
+}
+
+void SystemMonitor::NotifyResume() {
+  LOG(INFO) << L"Power Resuming";
+  observer_list_->Notify(&PowerObserver::OnResume);
+}
+
+void SystemMonitor::BatteryCheck() {
+  ProcessPowerMessage(SystemMonitor::POWER_STATE_EVENT);
+}
diff --git a/app/system_monitor.h b/app/system_monitor.h
new file mode 100644
index 0000000..abafe4f
--- /dev/null
+++ b/app/system_monitor.h
@@ -0,0 +1,118 @@
+// Copyright (c) 2009 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.
+
+#ifndef APP_SYSTEM_MONITOR_H_
+#define APP_SYSTEM_MONITOR_H_
+
+#include "build/build_config.h"
+
+// Windows HiRes timers drain the battery faster so we need to know the battery
+// status.  This isn't true for other platforms.
+#if defined(OS_WIN)
+#define ENABLE_BATTERY_MONITORING 1
+#else
+#undef ENABLE_BATTERY_MONITORING
+#endif  // !OS_WIN
+
+#include "base/observer_list_threadsafe.h"
+#if defined(ENABLE_BATTERY_MONITORING)
+#include "base/timer.h"
+#endif  // defined(ENABLE_BATTERY_MONITORING)
+
+// Class for monitoring various system-related subsystems
+// such as power management, network status, etc.
+// TODO(mbelshe):  Add support beyond just power management.
+class SystemMonitor {
+ public:
+  // Create SystemMonitor. Only one SystemMonitor instance per application
+  // is allowed.
+  SystemMonitor();
+  ~SystemMonitor();
+
+  // Get the application-wide SystemMonitor (if not present, returns NULL).
+  static SystemMonitor* Get();
+
+  //
+  // Power-related APIs
+  //
+
+  // Is the computer currently on battery power.
+  // Can be called on any thread.
+  bool BatteryPower() const {
+    // Using a lock here is not necessary for just a bool.
+    return battery_in_use_;
+  }
+
+  // Normalized list of power events.
+  enum PowerEvent {
+    POWER_STATE_EVENT,  // The Power status of the system has changed.
+    SUSPEND_EVENT,      // The system is being suspended.
+    RESUME_EVENT        // The system is being resumed.
+  };
+
+  // Callbacks will be called on the thread which creates the SystemMonitor.
+  // During the callback, Add/RemoveObserver will block until the callbacks
+  // are finished. Observers should implement quick callback functions; if
+  // lengthy operations are needed, the observer should take care to invoke
+  // the operation on an appropriate thread.
+  class PowerObserver {
+   public:
+    // Notification of a change in power status of the computer, such
+    // as from switching between battery and A/C power.
+    virtual void OnPowerStateChange(bool on_battery_power) {}
+
+    // Notification that the system is suspending.
+    virtual void OnSuspend() {}
+
+    // Notification that the system is resuming.
+    virtual void OnResume() {}
+  };
+
+  // Add a new observer.
+  // Can be called from any thread.
+  // Must not be called from within a notification callback.
+  void AddObserver(PowerObserver* obs);
+
+  // Remove an existing observer.
+  // Can be called from any thread.
+  // Must not be called from within a notification callback.
+  void RemoveObserver(PowerObserver* obs);
+
+#if defined(OS_WIN)
+  // Windows-specific handling of a WM_POWERBROADCAST message.
+  // Embedders of this API should hook their top-level window
+  // message loop and forward WM_POWERBROADCAST through this call.
+  void ProcessWmPowerBroadcastMessage(int event_id);
+#endif
+
+  // Cross-platform handling of a power event.
+  void ProcessPowerMessage(PowerEvent event_id);
+
+ private:
+  // Platform-specific method to check whether the system is currently
+  // running on battery power.  Returns true if running on batteries,
+  // false otherwise.
+  bool IsBatteryPower();
+
+  // Checks the battery status and notifies observers if the battery
+  // status has changed.
+  void BatteryCheck();
+
+  // Functions to trigger notifications.
+  void NotifyPowerStateChange();
+  void NotifySuspend();
+  void NotifyResume();
+
+  scoped_refptr<ObserverListThreadSafe<PowerObserver> > observer_list_;
+  bool battery_in_use_;
+  bool suspended_;
+
+#if defined(ENABLE_BATTERY_MONITORING)
+  base::OneShotTimer<SystemMonitor> delayed_battery_check_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(SystemMonitor);
+};
+
+#endif  // APP_SYSTEM_MONITOR_H_
diff --git a/app/system_monitor_posix.cc b/app/system_monitor_posix.cc
new file mode 100644
index 0000000..5ac7a12
--- /dev/null
+++ b/app/system_monitor_posix.cc
@@ -0,0 +1,10 @@
+// Copyright (c) 2009 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 "app/system_monitor.h"
+
+bool SystemMonitor::IsBatteryPower() {
+  NOTIMPLEMENTED();
+  return false;
+}
diff --git a/app/system_monitor_unittest.cc b/app/system_monitor_unittest.cc
new file mode 100644
index 0000000..5b107aa
--- /dev/null
+++ b/app/system_monitor_unittest.cc
@@ -0,0 +1,87 @@
+// Copyright (c) 2009 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 "app/system_monitor.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+class PowerTest : public SystemMonitor::PowerObserver {
+ public:
+  PowerTest()
+      : battery_(false),
+        power_state_changes_(0),
+        suspends_(0),
+        resumes_(0) {
+  }
+
+  // PowerObserver callbacks.
+  void OnPowerStateChange(bool on_battery_power) {
+    power_state_changes_++;
+  }
+
+  void OnSuspend() {
+    suspends_++;
+  }
+
+  void OnResume() {
+    resumes_++;
+  }
+
+  // Test status counts.
+  bool battery() { return battery_; }
+  int power_state_changes() { return power_state_changes_; }
+  int suspends() { return suspends_; }
+  int resumes() { return resumes_; }
+
+ private:
+  bool battery_;   // Do we currently think we're on battery power.
+  int power_state_changes_;  // Count of OnPowerStateChange notifications.
+  int suspends_;  // Count of OnSuspend notifications.
+  int resumes_;  // Count of OnResume notifications.
+};
+
+TEST(SystemMonitor, PowerNotifications) {
+  const int kObservers = 5;
+
+  // Initialize a message loop for this to run on.
+  MessageLoop loop;
+  // Initialize time() since it registers as a SystemMonitor observer.
+  base::Time now = base::Time::Now();
+
+  SystemMonitor system_monitor;
+  PowerTest test[kObservers];
+  for (int index = 0; index < kObservers; ++index)
+    system_monitor.AddObserver(&test[index]);
+
+  // Send a bunch of power changes.  Since the battery power hasn't
+  // actually changed, we shouldn't get notifications.
+  for (int index = 0; index < 5; index++) {
+    system_monitor.ProcessPowerMessage(SystemMonitor::POWER_STATE_EVENT);
+    EXPECT_EQ(test[0].power_state_changes(), 0);
+  }
+
+  // Sending resume when not suspended should have no effect.
+  system_monitor.ProcessPowerMessage(SystemMonitor::RESUME_EVENT);
+  loop.RunAllPending();
+  EXPECT_EQ(test[0].resumes(), 0);
+
+  // Pretend we suspended.
+  system_monitor.ProcessPowerMessage(SystemMonitor::SUSPEND_EVENT);
+  loop.RunAllPending();
+  EXPECT_EQ(test[0].suspends(), 1);
+
+  // Send a second suspend notification.  This should be suppressed.
+  system_monitor.ProcessPowerMessage(SystemMonitor::SUSPEND_EVENT);
+  loop.RunAllPending();
+  EXPECT_EQ(test[0].suspends(), 1);
+
+  // Pretend we were awakened.
+  system_monitor.ProcessPowerMessage(SystemMonitor::RESUME_EVENT);
+  loop.RunAllPending();
+  EXPECT_EQ(test[0].resumes(), 1);
+
+  // Send a duplicate resume notification.  This should be suppressed.
+  system_monitor.ProcessPowerMessage(SystemMonitor::RESUME_EVENT);
+  loop.RunAllPending();
+  EXPECT_EQ(test[0].resumes(), 1);
+}
diff --git a/app/system_monitor_win.cc b/app/system_monitor_win.cc
new file mode 100644
index 0000000..c9347dc
--- /dev/null
+++ b/app/system_monitor_win.cc
@@ -0,0 +1,46 @@
+// Copyright (c) 2009 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 "app/system_monitor.h"
+
+void SystemMonitor::ProcessWmPowerBroadcastMessage(int event_id) {
+  PowerEvent power_event;
+  switch (event_id) {
+    case PBT_APMPOWERSTATUSCHANGE:  // The power status changed.
+      power_event = POWER_STATE_EVENT;
+      break;
+    case PBT_APMRESUMEAUTOMATIC:  // Resume from suspend.
+    //case PBT_APMRESUMESUSPEND:  // User-initiated resume from suspend.
+                                  // We don't notify for this latter event
+                                  // because if it occurs it is always sent as a
+                                  // second event after PBT_APMRESUMEAUTOMATIC.
+      power_event = RESUME_EVENT;
+      break;
+    case PBT_APMSUSPEND:  // System has been suspended.
+      power_event = SUSPEND_EVENT;
+      break;
+    default:
+      return;
+
+    // Other Power Events:
+    // PBT_APMBATTERYLOW - removed in Vista.
+    // PBT_APMOEMEVENT - removed in Vista.
+    // PBT_APMQUERYSUSPEND - removed in Vista.
+    // PBT_APMQUERYSUSPENDFAILED - removed in Vista.
+    // PBT_APMRESUMECRITICAL - removed in Vista.
+    // PBT_POWERSETTINGCHANGE - user changed the power settings.
+  }
+  ProcessPowerMessage(power_event);
+}
+
+// Function to query the system to see if it is currently running on
+// battery power.  Returns true if running on battery.
+bool SystemMonitor::IsBatteryPower() {
+  SYSTEM_POWER_STATUS status;
+  if (!GetSystemPowerStatus(&status)) {
+    LOG(ERROR) << "GetSystemPowerStatus failed: " << GetLastError();
+    return false;
+  }
+  return (status.ACLineStatus == 0);
+}