安卓8.0 WIFI休眠策略分析

最新推荐文章于 2021-05-27 22:08:56 发布

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最新推荐文章于 2021-05-27 22:08:56 发布 · 4.7k 阅读

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本文深入分析了安卓8.0系统的WiFi休眠策略，包括不同休眠模式，如默认、插电时不休眠和从不休眠。通过`Settings.java`和`WifiController.java`中的代码展示了如何根据充电状态决定是否让WiFi保持清醒。同时，当设备熄屏且满足特定条件时，会设置一个15分钟的定时器。在充电状态改变时，会调整WiFi的休眠策略。此外，`WifiStateMachine.java`中的`WakeLock`用于保持WiFi连接，并与电池统计相关联，确保准确记录电源使用情况。

http://androidxref.com/8.0.0_r4

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/frameworks/base/core/java/android/provider/Settings.java

public static final String WIFI_SLEEP_POLICY = "wifi_sleep_policy";

public static final int WIFI_SLEEP_POLICY_DEFAULT = 0;
public static final int WIFI_SLEEP_POLICY_NEVER_WHILE_PLUGGED = 1;
public static final int WIFI_SLEEP_POLICY_NEVER = 2;

============================================================
/frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiController.java

private int mSleepPolicy; // 当前休眠策略
private int mPluggedType; // 当前充电状态  可选值如下
{
private static final int BATTERY_PLUGGED_NONE = 0;  // 手机没有充电
private static final int BATTERY_PLUGGED_AC = 1; // 注册充电
private static final int BATTERY_PLUGGED_USB = 2; // 连接电脑USB充电
private static final int BATTERY_PLUGGED_WIRELESS= 4;  // 无线充电
public static final int BATTERY_PLUGGED_ANY = 7;
}


    /**
     * Determines whether the Wi-Fi chipset should stay awake or be put to
     * sleep. Looks at the setting for the sleep policy and the current
     * conditions.  
     *
     * @see #shouldDeviceStayAwake(int)
     */
    private boolean shouldWifiStayAwake(int pluggedType) { //依据参数pluggedType和mSleepPolicy值 确定是否休眠
        if (mSleepPolicy == Settings.Global.WIFI_SLEEP_POLICY_NEVER) {
            // Never sleep
            return true;
        } else if ((mSleepPolicy == Settings.Global.WIFI_SLEEP_POLICY_NEVER_WHILE_PLUGGED) && (pluggedType != 0)) {
            // Never sleep while plugged, and we're plugged
            return true;
        } else {
            // Default
            return shouldDeviceStayAwake(pluggedType);
       }
  }
			
    /**
     * Observes changes to wifi sleep policy
     */
    private void registerForWifiSleepPolicyChange(Handler handler) {
        ContentObserver contentObserver = new ContentObserver(handler) {
            @Override
            public void onChange(boolean selfChange) {
                readWifiSleepPolicy();
            }
        };
        mFacade.registerContentObserver(mContext,Settings.Global.getUriFor(Settings.Global.WIFI_SLEEP_POLICY), false,
                contentObserver);
    }
	
    private void readWifiSleepPolicy() {
        mSleepPolicy = mFacade.getIntegerSetting(mContext,
                Settings.Global.WIFI_SLEEP_POLICY,
                Settings.Global.WIFI_SLEEP_POLICY_NEVER);
    }
	
	
	
	
 class DefaultState extends State {
        @Override
        public boolean processMessage(Message msg) {
            switch (msg.what) {
                case CMD_SCREEN_OFF:  // 灭屏情况下
                    mScreenOff = true;

                    if (!shouldWifiStayAwake(mPluggedType)) {
//private static final long DEFAULT_IDLE_MS = 15 * 60 * 1000  // 15分钟
//   private static final String ACTION_DEVICE_IDLE ="com.android.server.WifiManager.action.DEVICE_IDLE";
//public static final String WIFI_IDLE_MS = "wifi_idle_ms";
// mIdleMillis = mFacade.getLongSetting(mContext,Settings.Global.WIFI_IDLE_MS, DEFAULT_IDLE_MS); 
// Intent idleIntent = new Intent(ACTION_DEVICE_IDLE, null);  private static final int IDLE_REQUEST = 0;
// private PendingIntentmIdleIntent = mFacade.getBroadcast(mContext, IDLE_REQUEST, idleIntent, 0);
// 【如果不保持连接，那么设置mIdleMillis 15分钟之后发送 ACTION_DEVICE_IDLE的广播】
                        if (mNetworkInfo.getDetailedState() ==NetworkInfo.DetailedState.CONNECTED) {
                            if (DBG) Slog.d(TAG, "set idle timer: " + mIdleMillis + " ms");
                            mAlarmManager.set(AlarmManager.RTC_WAKEUP,System.currentTimeMillis() + mIdleMillis, mIdleIntent);
                        } else {
						//需要使机器不保持连接 当前连接状态不为连接那么就 直接使发送CMD_DEVICE_IDLE消息
                            sendMessage(CMD_DEVICE_IDLE);
                        }
                    }
                    break;

                case CMD_BATTERY_CHANGED:
                    int pluggedType = msg.arg1;
                    // 如果当前灭屏  
                    if (mScreenOff && shouldWifiStayAwake(mPluggedType)【CMD_BATTERY_CHANGED消息前记录的PluggedType】 
					&&!shouldWifiStayAwake(pluggedType) 【CMD_BATTERY_CHANGED携带的PluggedType】 ) {
					 // 以上条件满足 那么就发送 mIdleIntent 广播
                        long triggerTime = System.currentTimeMillis() + mIdleMillis;
                        if (DBG) Slog.d(TAG, "set idle timer for " + mIdleMillis + "ms");
                        mAlarmManager.set(AlarmManager.RTC_WAKEUP, triggerTime, mIdleIntent);
                    }

                    mPluggedType = pluggedType;
                    break;
					
					
					case CMD_DEVICE_IDLE:
                    mDeviceIdle = true;