[core][power_manager] review fixes

8 files changed, 117 insertions, 0 deletions

diff --git a/platform/CMakeLists.txt b/platform/CMakeLists.txt
index 36cdf3c03b..5f66116e94 100644
--- a/platform/CMakeLists.txt
+++ b/platform/CMakeLists.txt
@@ -6,6 +6,8 @@ set(CMAKE_AUTOMOC ON)
 
 set(
   SRC
+  battery_tracker.cpp
+  battery_tracker.hpp
   chunks_download_strategy.cpp
   chunks_download_strategy.hpp
   constants.hpp
diff --git a/platform/battery_tracker.cpp b/platform/battery_tracker.cpp
new file mode 100644
index 0000000000..a80ce09eed
--- /dev/null
+++ b/platform/battery_tracker.cpp
@@ -0,0 +1,68 @@
+#include "platform/battery_tracker.hpp"
+
+#include "platform/platform.hpp"
+
+namespace
+{
+auto const kBatteryTrackingInterval = std::chrono::minutes(10);
+
+bool IsLevelExpired(std::chrono::system_clock::time_point lastRequestTime)
+{
+  return std::chrono::system_clock::now() - lastRequestTime > kBatteryTrackingInterval;
+}
+}  // namespace
+
+namespace platform
+{
+void BatteryLevelTracker::Subscribe(Subscriber * subscriber)
+{
+  m_subscribers.push_back(subscriber);
+
+  if (IsLevelExpired(m_lastRequestTime))
+  {
+    // Run periodic requests when the first subscriber is added.
+    if (m_subscribers.size() == 1)
+      RequestBatteryLevel();
+  }
+  else
+  {
+    subscriber->OnBatteryLevelReceived(m_lastReceivedLevel);
+  }
+}
+
+void BatteryLevelTracker::Unsubscribe(Subscriber * subscriber)
+{
+  m_subscribers.erase(std::remove(m_subscribers.begin(), m_subscribers.end(), subscriber),
+                      m_subscribers.end());
+}
+
+void BatteryLevelTracker::UnsubscribeAll()
+{
+  m_subscribers.clear();
+}
+
+void BatteryLevelTracker::RequestBatteryLevel()
+{
+  if (m_subscribers.empty())
+    return;
+
+  if (IsLevelExpired(m_lastRequestTime))
+  {
+    m_lastReceivedLevel = GetPlatform().GetBatteryLevel();
+    m_lastRequestTime = std::chrono::system_clock::now();
+  }
+
+  for (auto s : m_subscribers)
+  {
+    s->OnBatteryLevelReceived(m_lastReceivedLevel);
+  }
+
+  GetPlatform().RunDelayedTask(Platform::Thread::Background, kBatteryTrackingInterval, [this]
+  {
+    GetPlatform().RunTask(Platform::Thread::Gui, [this]
+    {
+      RequestBatteryLevel();
+    });
+  });
+}
+}  // namespace platform
diff --git a/platform/battery_tracker.hpp b/platform/battery_tracker.hpp
new file mode 100644
index 0000000000..65a6b35f3b
--- /dev/null
+++ b/platform/battery_tracker.hpp
@@ -0,0 +1,30 @@
+#pragma once
+
+#include <chrono>
+#include <cstdint>
+#include <vector>
+
+namespace platform
+{
+// Note: this class is NOT thread-safe.
+class BatteryLevelTracker
+{
+public:
+  class Subscriber
+  {
+  public:
+    virtual void OnBatteryLevelReceived(uint8_t level) = 0;
+  };
+
+  void Subscribe(Subscriber * subscriber);
+  void Unsubscribe(Subscriber * subscriber);
+  void UnsubscribeAll();
+
+private:
+  void RequestBatteryLevel();
+
+  std::vector<Subscriber *> m_subscribers;
+  std::chrono::system_clock::time_point m_lastRequestTime;
+  uint8_t m_lastReceivedLevel = 0;
+};
+}  // platform
diff --git a/platform/platform.cpp b/platform/platform.cpp
index add77316ce..9303d4ad86 100644
--- a/platform/platform.cpp
+++ b/platform/platform.cpp
@@ -329,6 +329,9 @@ unsigned Platform::CpuCores() const
 void Platform::ShutdownThreads()
 {
   ASSERT(m_networkThread && m_fileThread && m_backgroundThread, ());
+
+  m_batteryTracker.UnsubscribeAll();
+
   m_networkThread->ShutdownAndJoin();
   m_fileThread->ShutdownAndJoin();
   m_backgroundThread->ShutdownAndJoin();
diff --git a/platform/platform.hpp b/platform/platform.hpp
index 9d92513670..3f832bcd07 100644
--- a/platform/platform.hpp
+++ b/platform/platform.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "platform/battery_tracker.hpp"
 #include "platform/country_defines.hpp"
 #include "platform/gui_thread.hpp"
 #include "platform/http_user_agent.hpp"
@@ -131,6 +132,8 @@ protected:
   std::unique_ptr<base::WorkerThread> m_fileThread;
   std::unique_ptr<base::WorkerThread> m_backgroundThread;
 
+  platform::BatteryLevelTracker m_batteryTracker;
+
 public:
   Platform();
   virtual ~Platform() = default;
@@ -291,6 +294,9 @@ public:
   static bool IsConnected() { return ConnectionStatus() != EConnectionType::CONNECTION_NONE; }
 
   static ChargingStatus GetChargingStatus();
+
+  // Returns current battery level. Possible values are from 0 to 100.
+  // Returns 100 when actual level is unknown.
   static uint8_t GetBatteryLevel();
 
   void SetupMeasurementSystem() const;
@@ -347,6 +353,8 @@ public:
   // Use this method for testing purposes only.
   void SetGuiThread(std::unique_ptr<base::TaskLoop> guiThread);
 
+  platform::BatteryLevelTracker & GetBatteryTracker() { return m_batteryTracker; }
+
 private:
   void RunThreads();
   void ShutdownThreads();
diff --git a/platform/platform_ios.mm b/platform/platform_ios.mm
index cd8c068800..e88d565870 100644
--- a/platform/platform_ios.mm
+++ b/platform/platform_ios.mm
@@ -228,6 +228,10 @@ Platform::ChargingStatus Platform::GetChargingStatus()
 uint8_t Platform::GetBatteryLevel()
 {
   auto const level = UIDevice.currentDevice.batteryLevel;
+
+  ASSERT_GREATER_OR_EQUAL(level, -1.0, ());
+  ASSERT_LESS_OR_EQUAL(level, 1.0, ());
+
   if (level == -1.0)
     return 100;
 
diff --git a/platform/platform_linux.cpp b/platform/platform_linux.cpp
index 0f014e0a9d..8a0a1306b0 100644
--- a/platform/platform_linux.cpp
+++ b/platform/platform_linux.cpp
@@ -262,6 +262,7 @@ Platform::ChargingStatus Platform::GetChargingStatus()
 
 uint8_t Platform::GetBatteryLevel()
 {
+  // This value is always 100 for desktop.
   return 100;
 }
 
diff --git a/platform/platform_mac.mm b/platform/platform_mac.mm
index 63f1ff6957..8f353108db 100644
--- a/platform/platform_mac.mm
+++ b/platform/platform_mac.mm
@@ -176,6 +176,7 @@ Platform::ChargingStatus Platform::GetChargingStatus()
 
 uint8_t Platform::GetBatteryLevel()
 {
+  // This value is always 100 for desktop.
   return 100;
 }