Android电源管理系统调研报告-（3）

一、 powermanagerservice.java 1 、 nest class

1) 、 private class UnsynchronizedWakeLock

从类名可以看出这个类实现的是异步获取唤醒锁。当 PowerManager.WakeLock 与 synchronizing on mLocks 之间发生死锁的时候，这个类可以重新实现 PowerManager.WakeLock 。由于它没有外部同步块，所以只有当拥有锁的时候才调用这个类。

该类实现的方法有：

public void acquire() public void release() public boolean isHeld() public String toString()

构造方法：

UnsynchronizedWakeLock(int flags, String tag, boolean refCounted)

 

2 ）、 private final class BatteryReceiver extends BroadcastReceiver

这个类是个广播接收，至于广播的使用，这里不作深入的探讨。该类重载了接收的方法。当然，接收的过程是有约束的，即同步 mLocks 。

@Override          public void onReceive(Context context, Intent intent)              synchronized (mLocks)  即使当 keyguard is on                       synchronized (mLocks) {                           forceUserActivityLocked();

 

3 ）、 private final class BootCompletedReceiver extends BroadcastReceiver

@Override          public void onReceive(Context context, Intent intent) {              bootCompleted();           }

该广播能接收到启动完成后的消息，而后调用 bootCompleted() 。

 

4 ）、 private final class DockReceiver extends BroadcastReceiver

 

5 ）、 private class SettingsObserver implements Observer

6 ）、 private class WakeLock implements IBinder.DeathRecipient

方法 public void binderDied() 会调用 releaseWakeLockLocked

synchronized (mLocks) {                  releaseWakeLockLocked(this.binder, 0, true);

 

7 ）、 private class PokeLock implements IBinder.DeathRecipient

方法 public void binderDied()  调用

             setPokeLock(0,this.binder, this.tag);

 

8 ）、 private class TimeoutTask implements Runnable

该类实现了 Runnable 接口，有一个 run 方法。

run 方法实现的是 Timeout 后进行的动作， setTimeoutLocked(now,SCREEN_DIM); ？ setTimeoutLocked(now,SCREEN_OFF);

 

9 ）、 class BrightnessState

该类定义的方法有

BrightnessState(int m) public void dump(PrintWriter pw, String prefix) boolean setTargetLocked(int target, int stepsToTarget, int initialValue,int nominalCurrentValue)   delta = (targetValue -(nominalCurrentValue >= 0 ?nominalCurrentValue : curValue))/ stepsToTarget;   boolean stepLocked()

 

10 ）、 private class LightAnimator implements Runnable

该类实现了 Runnable 接口，有一个 run 方法

run 方法实现的是亮度变化的控制：

ScreenBrightness KeyboardBrightness ButtonBrightness

这三个设备亮度分步控制。

if (mKeyboardBrightness.stepLocked()) {                      more = true;                  }                  if (mButtonBrightness.stepLocked()) {                      more = true;                   }                  if (more) {                       mHandler.postAtTime(mLightAnimator, now+(1000/60));

 

11 ）、 private class GservicesChangedReceiver extends BroadcastReceiver

该类继承了广播接口的类，方法 onReceive 调用了 updateGservicesValues() 。

该类当接收到 google service 改变的广播时，就受调用 updateGservicesValues() 。

 

12 ）、 private class LockList extends ArrayList<WakeLock>

方法：

void addLock(WakeLock wl) WakeLock removeLock(IBinder binder) int getIndex(IBinder binder) int gatherState() int reactivateScreenLocksLocked()

 

该类实践上是建立了一了锁队列 / 锁列表，该队列可以通过 addLock 新建一个锁，也可以通过 removeLock 从队列中摘除一个锁，可以通过 getIndex 查询指定锁在队列中的索引号

 

定义了一个该类的实例

private final LockList mLocks = new LockList();

整个 service 中方法的调用都同步这个对象 mLocks

synchronized (mLocks)

 

 

2 、相关的 service ： BatteryService

mBatteryService.isPowered()

mBatteryService.getBatteryLevel()

BatteryStatsService.getService()

Gservices Hardwareservice ActivityService

 

3 、参数

     //flags for setPowerState

     private static final intSCREEN_ON_BIT           = 0x00000001;

     private static final intSCREEN_BRIGHT_BIT       = 0x00000002;

     private static final intBUTTON_BRIGHT_BIT       = 0x00000004;

     private static final intKEYBOARD_BRIGHT_BIT     = 0x00000008;

     private static final intBATTERY_LOW_BIT         = 0x00000010;

 

     //SCREEN_OFF == everything off

     private static final intSCREEN_OFF          = 0x00000000;

 

     //SCREEN_DIM == screen on, screen backlight dim

     private static final intSCREEN_DIM          = SCREEN_ON_BIT;

 

     //SCREEN_BRIGHT == screen on, screen backlight bright

     private static final intSCREEN_BRIGHT       = SCREEN_ON_BIT |SCREEN_BRIGHT_BIT;

 

     //SCREEN_BUTTON_BRIGHT == screen on, screen and button backlights bright

     private static final intSCREEN_BUTTON_BRIGHT   = SCREEN_BRIGHT |BUTTON_BRIGHT_BIT;

 

     //SCREEN_BUTTON_BRIGHT == screen on, screen, button and keyboard backlightsbright

     private static final intALL_BRIGHT          = SCREEN_BUTTON_BRIGHT| KEYBOARD_BRIGHT_BIT;

 

 

4 、提供的相关服务

提供的这些服务之间并不是独立的，而是相互交织在一起，共同完成电源管理的：

1 ）、光感传感器

LIGHT_SENSOR

 

定义了光感传感器变化明暗变化的延时：

// How long to wait to debounce light sensor changes .       private static final int LIGHT_SENSOR_DELAY = 2000;

 

相关的参数有：

private Sensor mLightSensor;      private boolean mLightSensorEnabled;      private float mLightSensorValue = -1;      private int mHighestLightSensorValue = -1;      private float mLightSensorPendingValue = -1;      private int mLightSensorBrightness = -1;      private int mLightSensorWarmupTime;            private static final boolean mDebugLightSensor = (false || mSpew);

 

相关的方法：

private void enableLightSensor(boolean enable)      private int setScreenStateLocked      private int getPreferredBrightness()      private Runnable mAutoBrightnessTask = new Runnable()      private void lightSensorChangedLocked(int value)      public void setKeyboardVisibility(boolean visible)      private void setScreenBrightnessMode(int mode)      private void enableLightSensor(boolean enable)            SensorEventListener mLightListener = new SensorEventListener()

 

// force recompute of backlight values                          if (mLightSensorValue >= 0) {                               int value = (int)mLightSensorValue;                               mLightSensorValue = -1;                               lightSensorChangedLocked(value);

 

 

 

2 ）、接近 / 距离传感器

PROXIMITY_SENSOR

 

定义了接近传感器变化明暗变化的延时：

// For debouncing the proximity sensor.       private static final int PROXIMITY_SENSOR_DELAY = 1000;

 

定义了接近传感器触发的最大距离：

// trigger proximity if distance is less than 5 cm       private static final float PROXIMITY_THRESHOLD = 5.0f;

 

在 powermanager 类中定义的与接近传感器相关的参数有：

private static final int WAKE_BIT_PROXIMITY_SCREEN_OFF = 32;       public static final int PROXIMITY_SCREEN_OFF_WAKE_LOCK = WAKE_BIT_PROXIMITY_SCREEN_OFF

 

相关参数：

private int mProximityWakeLockCount = 0;      private boolean mProximitySensorEnabled = false;      private boolean mProximitySensorActive = false;      private int mProximityPendingValue = -1; // -1 == nothing, 0 == inactive, 1 == active       private long mLastProximityEventTime;        private UnsynchronizedWakeLock mProximityPartialLock;            private Sensor mProximitySensor;

 

相关方法：

SensorEventListener mProximityListener = new SensorEventListener()            private Runnable mProximityTask = new Runnable()

 

// 当拨出电话或接通电话时会调用该方法      private void enableProximityLockLocked()                              ......                              // 传感器的注册，三个参数分别是接收信号 Listener 的实例、传感器类型的列表、接收频度；                       mSensorManager.registerListener(mProximityListener, mProximitySensor,                           SensorManager.SENSOR_DELAY_NORMAL);                                // 当挂断电话时会调用该方法      private void disableProximityLockLocked()                              ......                              // 缷载传感器                mSensorManager.unregisterListener(mProximityListener);        private void proximityChangedLocked(boolean active) ｛                              ......                              // 小于触发距离触发接近传感器之后的动作＿灭屏。如打电话时屏幕 LCD 灯的熄灭                                if (active) {               goToSleepLocked(SystemClock.uptimeMillis(),                       WindowManagerPolicy.OFF_BECAUSE_OF_PROX_SENSOR);               mProximitySensorActive = true;                              ......       SensorEventListener mProximityListener = new SensorEventListener()

 

3 ）、提供明亮度动态变化：

animation for brightness changes ：

 

定义了可以明暗动态变化设备的宏，可以看出，不外乎这三个部分：屏幕灯、触摸按键灯和键盘灯

static final boolean ANIMATE_SCREEN_LIGHTS = true;      static final boolean ANIMATE_BUTTON_LIGHTS = false;// 如果有该部分的灯并需要亮度调节，找开这个宏      static final boolean ANIMATE_KEYBOARD_LIGHTS = false;// 如果有该部分的灯并需要亮度调节，找开这个宏

 

    

明暗变化的级别，分普通级别的较慢级别：

static final int ANIM_STEPS = 60/4;      // Slower animation for autobrightness changes      static final int AUTOBRIGHTNESS_ANIM_STEPS = 60;

 

 

相关类：

101010private class LightAnimator implements Runnable

 

相关方法：

private void updateLightsLocked(int newState, int forceState) private void lightSensorChangedLocked(int value) public void setBacklightBrightness(int brightness)

 

 

4 ）、允许用户用软件自动调节亮度

mUseSoftwareAutoBrightness

在 initThread 中初始化了这个变量

mUseSoftwareAutoBrightness =resources.getBoolean(com.android.internal.R.bool.config_automatic_brightness_available);

当这个变量获取到非零值

if (mUseSoftwareAutoBrightness) {               mAutoBrightnessLevels = resources.getIntArray(                       com.android.internal.R.array.config_autoBrightnessLevels);

 

自动调节亮度的功能与 LIGHT_SENSOR 相关，当外界光线强时，屏幕会相应提升亮度。