and5.1PowerManagerService深入分析（一） PMS的初始化以及低功耗模式

之前已经分析过PMS了，但是不是非常详细。

现在准备详细的分析下PMS。

一、构造函数

先看下构造函数：

    public PowerManagerService(Context context) {        super(context);        mContext = context;        mHandlerThread = new ServiceThread(TAG,                Process.THREAD_PRIORITY_DISPLAY, false /*allowIo*/);        mHandlerThread.start();        mHandler = new PowerManagerHandler(mHandlerThread.getLooper());//新建一个handler，并且handler的线程也是新建的        synchronized (mLock) {            mWakeLockSuspendBlocker = createSuspendBlockerLocked("PowerManagerService.WakeLocks");//通过JNI调用底层的wakelock函数            mDisplaySuspendBlocker = createSuspendBlockerLocked("PowerManagerService.Display");            mDisplaySuspendBlocker.acquire();//持锁            mHoldingDisplaySuspendBlocker = true;            mHalAutoSuspendModeEnabled = false;            mHalInteractiveModeEnabled = true;            mWakefulness = WAKEFULNESS_AWAKE;//mWakefulness 初始状态            nativeInit();            nativeSetAutoSuspend(false);            nativeSetInteractive(true);        }    }

先看下createSuspendBlockerLocked函数

    private SuspendBlocker createSuspendBlockerLocked(String name) {        SuspendBlocker suspendBlocker = new SuspendBlockerImpl(name);        mSuspendBlockers.add(suspendBlocker);        return suspendBlocker;    }

再看下SuspendBlockerImpl 函数，其中acquire，是通过JNI

    private final class SuspendBlockerImpl implements SuspendBlocker {        private final String mName;        private final String mTraceName;        private int mReferenceCount;        public SuspendBlockerImpl(String name) {            mName = name;            mTraceName = "SuspendBlocker (" + name + ")";        }        @Override        protected void finalize() throws Throwable {            try {                if (mReferenceCount != 0) {                    Slog.wtf(TAG, "Suspend blocker \"" + mName                            + "\" was finalized without being released!");                    mReferenceCount = 0;                    nativeReleaseSuspendBlocker(mName);                    Trace.asyncTraceEnd(Trace.TRACE_TAG_POWER, mTraceName, 0);                }            } finally {                super.finalize();            }        }        @Override        public void acquire() {            synchronized (this) {                mReferenceCount += 1;                if (mReferenceCount == 1) {                    if (DEBUG_SPEW) {                        Slog.d(TAG, "Acquiring suspend blocker \"" + mName + "\".");                    }                    Trace.asyncTraceBegin(Trace.TRACE_TAG_POWER, mTraceName, 0);                    nativeAcquireSuspendBlocker(mName);                }            }        }

nativeAcquireSuspendBlocker将上面传下来的name，然后是PARTIAL_WAKE_LOCK类型的lock

static void nativeAcquireSuspendBlocker(JNIEnv *env, jclass clazz, jstring nameStr) {    ScopedUtfChars name(env, nameStr);    acquire_wake_lock(PARTIAL_WAKE_LOCK, name.c_str());}

nativeInit也类似初始的时候写入cpu节点值。我们先看下jni

static void nativeInit(JNIEnv* env, jobject obj) {    gPowerManagerServiceObj = env->NewGlobalRef(obj);    status_t err = hw_get_module(POWER_HARDWARE_MODULE_ID,            (hw_module_t const**)&gPowerModule);    if (!err) {        gPowerModule->init(gPowerModule);    } else {        ALOGE("Couldn't load %s module (%s)", POWER_HARDWARE_MODULE_ID, strerror(-err));    }}

我们再看下power module的初始化：

struct lc_power_module HAL_MODULE_INFO_SYM = {    base: {        common: {            tag: HARDWARE_MODULE_TAG,            module_api_version: POWER_MODULE_API_VERSION_0_2,            hal_api_version: HARDWARE_HAL_API_VERSION,            id: POWER_HARDWARE_MODULE_ID,            name: "LC Power HAL",            author: "Leadcore Technology Co.,Ltd",            methods: &power_module_methods,        },        init: power_init,        setInteractive: lc_power_set_interactive,        powerHint: lc_power_hint,    },..........};

init函数对应power_init函数

static void power_init(struct power_module *module){    ALOGV("%s", __func__);    power_init_internal(module);}

power_init函数又调用了power_init_internal函数

void power_init_internal(struct power_module *module){    char buf[MAX_LENGTH];    int len = 0;    struct lc_power_module *lc = (struct lc_power_module *) module;    if (lc->power_lc_inited) {        ALOGD_IF(lc->log_hint, "Power HAL is inited!");        return;    }    char property[PROPERTY_VALUE_MAX];    if(property_get("debug.power.loghint", property, "0") > 0) {        if(atoi(property) == 1) {            lc->log_hint = 1;            ALOGI("enable power hint log!");        }    }    len = sizeof(buf);    sysfs_read("/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq", buf, &len);    buf[len-1] = '\0';    ALOGD_IF(lc->log_hint, "cpuinfo_max_freq %s readlen=%d", buf, len);    if (atoi(buf) != 0) {        lc->cpu_max_freq = atoi(buf);    }    if(system("set_middle_performance.sh"))    {        ALOGW("failed to run shell script!");        sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/timer_rate",                    "40000");        sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/timer_slack",                    "50000");        sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/min_sample_time",                    "40000");        sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/above_hispeed_delay",                    "1");    }    if(lc->cpu_max_freq == 1599000) {        sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/hispeed_freq",                    HISPEED_FREQ_1_6);    } else if(lc->cpu_max_freq == 1807000) {        sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/hispeed_freq",                    HISPEED_FREQ_1_8);    } else if(lc->cpu_max_freq == 1495000) {        sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/hispeed_freq",                    HISPEED_FREQ_1_5);    } else {        ALOGW("unknown cpu frequency %d", lc->cpu_max_freq);    }    sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/boostpulse_duration",                BOOSTPULSE_DURATION);    sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/io_is_busy", "1");    sysfs_write("/sys/module/comip_hotplug/parameters/load_h0", "15");    sysfs_write("/sys/module/comip_hotplug/parameters/load_h1", "30");    sysfs_write("/sys/module/comip_hotplug/parameters/load_h2", "55");    sysfs_write("/sys/module/comip_hotplug/parameters/load_l1", "15");    sysfs_write("/sys/module/comip_hotplug/parameters/load_l2", "28");    sysfs_write("/sys/module/comip_hotplug/parameters/load_l3", "50");    sysfs_write("/sys/devices/platform/comip-hotplug/hotplug/boost_duration",                BOOSTPULSE_DURATION_HOTPLUG);  //boost duration 1s    lasthint = 0;    activity_hint = 0;    camera_hint = 0;    ALOGD_IF(lc->log_hint, "%s done\n", __func__);}

nativeSetInteractive也是通过JNI，最后调到这里，当然各个hardware都有自己的实现方式。这个函数里面只是在cpu的节点里面写入一些值。

static void lc_power_set_interactive(struct power_module *module, int on){    char buf[100];    int len;    /*     * Lower maximum frequency when screen is off.  CPU 0 and 1 share a     * cpufreq policy.     */    //sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq",    //            on ? "1599000" : "799500");    if(on) {        len = sizeof(buf);        sysfs_read("/sys/devices/platform/mali.0/perf_level", buf, &len);        buf[len-1] = '\0';        ALOGD_IF(log_hint, "interactive on gpu pref_level %s\n", buf);        if(atoi(buf) == 2) {            system("set_middle_performance.sh");        } else if(atoi(buf) == 3) {            system("set_high_performance.sh");        }    } else {        sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/timer_rate",                    "60000");        sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/timer_slack",                    "50000");        sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/min_sample_time",                    "1");        sysfs_write("/sys/devices/system/cpu/cpu0/cpufreq/interactive/above_hispeed_delay",                    "1");    }    ALOGD("power_set_interactive: %d done\n", on);}

二、onStart函数

下面是走onStart函数，将BinderService和localServicepublish出去，同时将自己和handler加入watchdog中。

    @Override    public void onStart() {        publishBinderService(Context.POWER_SERVICE, new BinderService());        publishLocalService(PowerManagerInternal.class, new LocalService());        Watchdog.getInstance().addMonitor(this);        Watchdog.getInstance().addThread(mHandler);    }

三、systemReady函数

下面走的是systemReady函数

    public void systemReady(IAppOpsService appOps) {        synchronized (mLock) {            mSystemReady = true;//成员变量置位            mAppOps = appOps;            mDreamManager = getLocalService(DreamManagerInternal.class);            mDisplayManagerInternal = getLocalService(DisplayManagerInternal.class);            mPolicy = getLocalService(WindowManagerPolicy.class);            mBatteryManagerInternal = getLocalService(BatteryManagerInternal.class);            PowerManager pm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);            mScreenBrightnessSettingMinimum = pm.getMinimumScreenBrightnessSetting();            mScreenBrightnessSettingMaximum = pm.getMaximumScreenBrightnessSetting();            mScreenBrightnessSettingDefault = pm.getDefaultScreenBrightnessSetting();            SensorManager sensorManager = new SystemSensorManager(mContext, mHandler.getLooper());            // The notifier runs on the system server's main looper so as not to interfere            // with the animations and other critical functions of the power manager.            mBatteryStats = BatteryStatsService.getService();            mNotifier = new Notifier(Looper.getMainLooper(), mContext, mBatteryStats,                    mAppOps, createSuspendBlockerLocked("PowerManagerService.Broadcasts"),                    mPolicy);            mWirelessChargerDetector = new WirelessChargerDetector(sensorManager,                    createSuspendBlockerLocked("PowerManagerService.WirelessChargerDetector"),                    mHandler);            mSettingsObserver = new SettingsObserver(mHandler);            mLightsManager = getLocalService(LightsManager.class);            mAttentionLight = mLightsManager.getLight(LightsManager.LIGHT_ID_ATTENTION);            // Initialize display power management.            mDisplayManagerInternal.initPowerManagement(                    mDisplayPowerCallbacks, mHandler, sensorManager);            // Register for broadcasts from other components of the system.            IntentFilter filter = new IntentFilter();            filter.addAction(Intent.ACTION_BATTERY_CHANGED);            filter.setPriority(IntentFilter.SYSTEM_HIGH_PRIORITY);            mContext.registerReceiver(new BatteryReceiver(), filter, null, mHandler);//接受电池变化的广播            filter = new IntentFilter();            filter.addAction(Intent.ACTION_DREAMING_STARTED);            filter.addAction(Intent.ACTION_DREAMING_STOPPED);            mContext.registerReceiver(new DreamReceiver(), filter, null, mHandler);//接受做梦结束或者开始的广播            filter = new IntentFilter();            filter.addAction(Intent.ACTION_USER_SWITCHED);            mContext.registerReceiver(new UserSwitchedReceiver(), filter, null, mHandler);//用户切换的广播            filter = new IntentFilter();            filter.addAction(Intent.ACTION_DOCK_EVENT);            mContext.registerReceiver(new DockReceiver(), filter, null, mHandler);            // Register for settings changes.            final ContentResolver resolver = mContext.getContentResolver();            resolver.registerContentObserver(Settings.Secure.getUriFor(//这个是注册每个Settings数据库中值的一个观察者，一旦值有变就会调用mSettingsObserver                    Settings.Secure.SCREENSAVER_ENABLED),                    false, mSettingsObserver, UserHandle.USER_ALL);            resolver.registerContentObserver(Settings.Secure.getUriFor(                    Settings.Secure.SCREENSAVER_ACTIVATE_ON_SLEEP),                    false, mSettingsObserver, UserHandle.USER_ALL);            resolver.registerContentObserver(Settings.Secure.getUriFor(                    Settings.Secure.SCREENSAVER_ACTIVATE_ON_DOCK),                    false, mSettingsObserver, UserHandle.USER_ALL);            resolver.registerContentObserver(Settings.System.getUriFor(                    Settings.System.SCREEN_OFF_TIMEOUT),                    false, mSettingsObserver, UserHandle.USER_ALL);            resolver.registerContentObserver(Settings.Secure.getUriFor(                    Settings.Secure.SLEEP_TIMEOUT),                    false, mSettingsObserver, UserHandle.USER_ALL);            resolver.registerContentObserver(Settings.Global.getUriFor(                    Settings.Global.STAY_ON_WHILE_PLUGGED_IN),                    false, mSettingsObserver, UserHandle.USER_ALL);            resolver.registerContentObserver(Settings.System.getUriFor(                    Settings.System.SCREEN_BRIGHTNESS),                    false, mSettingsObserver, UserHandle.USER_ALL);            resolver.registerContentObserver(Settings.System.getUriFor(                    Settings.System.SCREEN_BRIGHTNESS_MODE),                    false, mSettingsObserver, UserHandle.USER_ALL);            resolver.registerContentObserver(Settings.System.getUriFor(                    Settings.System.SCREEN_AUTO_BRIGHTNESS_ADJ),                    false, mSettingsObserver, UserHandle.USER_ALL);            resolver.registerContentObserver(Settings.Global.getUriFor(                    Settings.Global.LOW_POWER_MODE),                    false, mSettingsObserver, UserHandle.USER_ALL);            resolver.registerContentObserver(Settings.Global.getUriFor(                    Settings.Global.LOW_POWER_MODE_TRIGGER_LEVEL),                    false, mSettingsObserver, UserHandle.USER_ALL);            resolver.registerContentObserver(Settings.Global.getUriFor(                    Settings.Global.THEATER_MODE_ON),                    false, mSettingsObserver, UserHandle.USER_ALL);            // Go.            readConfigurationLocked();            updateSettingsLocked();            mDirty |= DIRTY_BATTERY_STATE;            updatePowerStateLocked();        }    }

接受电池变化的广播

    private final class BatteryReceiver extends BroadcastReceiver {        @Override        public void onReceive(Context context, Intent intent) {            synchronized (mLock) {                handleBatteryStateChangedLocked();            }        }    }

    private void handleBatteryStateChangedLocked() {        mDirty |= DIRTY_BATTERY_STATE;        updatePowerStateLocked();    }

接受做梦的开始或者结束

    private final class DreamReceiver extends BroadcastReceiver {        @Override        public void onReceive(Context context, Intent intent) {            synchronized (mLock) {                scheduleSandmanLocked();            }        }    }

    private void scheduleSandmanLocked() {        if (!mSandmanScheduled) {            mSandmanScheduled = true;            Message msg = mHandler.obtainMessage(MSG_SANDMAN);            msg.setAsynchronous(true);            mHandler.sendMessage(msg);//通过发送消息        }    }

        @Override        public void handleMessage(Message msg) {            switch (msg.what) {                case MSG_USER_ACTIVITY_TIMEOUT:                    handleUserActivityTimeout();                    break;                case MSG_SANDMAN:                    handleSandman();//这个函数是对做梦的处理，后面详细分析                    break;                case MSG_SCREEN_BRIGHTNESS_BOOST_TIMEOUT:                    handleScreenBrightnessBoostTimeout();                    break;            }        }

mSettingsObserver对Setting数据库中的一些变量进行观察，一旦变化就调这个onChange这个函数。在上面的SystemReady中已经注册了各个变量的观察。

    private final class SettingsObserver extends ContentObserver {        public SettingsObserver(Handler handler) {            super(handler);        }        @Override        public void onChange(boolean selfChange, Uri uri) {            synchronized (mLock) {                handleSettingsChangedLocked();            }        }    }

handleSettingsChangedLocked函数

    private void handleSettingsChangedLocked() {        updateSettingsLocked();//更新各个设置参数        updatePowerStateLocked();//更新power状态，后面详细分析    }

下面看下updateSettingsLocked函数，其中的各个参数后面用到再分析

   private void updateSettingsLocked() {        final ContentResolver resolver = mContext.getContentResolver();        mDreamsEnabledSetting = (Settings.Secure.getIntForUser(resolver,                Settings.Secure.SCREENSAVER_ENABLED,                mDreamsEnabledByDefaultConfig ? 1 : 0,                UserHandle.USER_CURRENT) != 0);        mDreamsActivateOnSleepSetting = (Settings.Secure.getIntForUser(resolver,                Settings.Secure.SCREENSAVER_ACTIVATE_ON_SLEEP,                mDreamsActivatedOnSleepByDefaultConfig ? 1 : 0,                UserHandle.USER_CURRENT) != 0);        mDreamsActivateOnDockSetting = (Settings.Secure.getIntForUser(resolver,                Settings.Secure.SCREENSAVER_ACTIVATE_ON_DOCK,                mDreamsActivatedOnDockByDefaultConfig ? 1 : 0,                UserHandle.USER_CURRENT) != 0);        mScreenOffTimeoutSetting = Settings.System.getIntForUser(resolver,                Settings.System.SCREEN_OFF_TIMEOUT, DEFAULT_SCREEN_OFF_TIMEOUT,//屏幕自动灭屏的一个timeout                UserHandle.USER_CURRENT);        mSleepTimeoutSetting = Settings.Secure.getIntForUser(resolver,                Settings.Secure.SLEEP_TIMEOUT, DEFAULT_SLEEP_TIMEOUT,                UserHandle.USER_CURRENT);        mStayOnWhilePluggedInSetting = Settings.Global.getInt(resolver,                Settings.Global.STAY_ON_WHILE_PLUGGED_IN, BatteryManager.BATTERY_PLUGGED_AC);        mTheaterModeEnabled = Settings.Global.getInt(mContext.getContentResolver(),                Settings.Global.THEATER_MODE_ON, 0) == 1;        final int oldScreenBrightnessSetting = mScreenBrightnessSetting;        mScreenBrightnessSetting = Settings.System.getIntForUser(resolver,                Settings.System.SCREEN_BRIGHTNESS, mScreenBrightnessSettingDefault,                UserHandle.USER_CURRENT);        if (oldScreenBrightnessSetting != mScreenBrightnessSetting) {            mTemporaryScreenBrightnessSettingOverride = -1;        }        final float oldScreenAutoBrightnessAdjustmentSetting =                mScreenAutoBrightnessAdjustmentSetting;        mScreenAutoBrightnessAdjustmentSetting = Settings.System.getFloatForUser(resolver,                Settings.System.SCREEN_AUTO_BRIGHTNESS_ADJ, 0.0f,                UserHandle.USER_CURRENT);        if (oldScreenAutoBrightnessAdjustmentSetting != mScreenAutoBrightnessAdjustmentSetting) {            mTemporaryScreenAutoBrightnessAdjustmentSettingOverride = Float.NaN;        }        mScreenBrightnessModeSetting = Settings.System.getIntForUser(resolver,                Settings.System.SCREEN_BRIGHTNESS_MODE,                Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL, UserHandle.USER_CURRENT);        final boolean lowPowerModeEnabled = Settings.Global.getInt(resolver,                Settings.Global.LOW_POWER_MODE, 0) != 0;//低功耗模式        final boolean autoLowPowerModeConfigured = Settings.Global.getInt(resolver,//低功耗自动模式                Settings.Global.LOW_POWER_MODE_TRIGGER_LEVEL, 0) != 0;        if (lowPowerModeEnabled != mLowPowerModeSetting//两种模式其中一个改变了就调用updateLowPowerModeLocked函数                || autoLowPowerModeConfigured != mAutoLowPowerModeConfigured) {            mLowPowerModeSetting = lowPowerModeEnabled;            mAutoLowPowerModeConfigured = autoLowPowerModeConfigured;            updateLowPowerModeLocked();        }        mDirty |= DIRTY_SETTINGS;//Dirty的DIRTY_SETTINGS改变了    }

四、省电模式

下面分析下updateLowPowerModeLocked函数

    void updateLowPowerModeLocked() {        if (mIsPowered && mLowPowerModeSetting) {//如果当前插着电源，并且mLowPowerModeSetting为true。也是不能开启低功耗的，将其改为fasle，存入setting            if (DEBUG_SPEW) {                Slog.d(TAG, "updateLowPowerModeLocked: powered, turning setting off");            }            // Turn setting off if powered            Settings.Global.putInt(mContext.getContentResolver(),                    Settings.Global.LOW_POWER_MODE, 0);            mLowPowerModeSetting = false;        }        final boolean autoLowPowerModeEnabled = !mIsPowered && mAutoLowPowerModeConfigured//自动模式开启需要四个。没有充电、开启自动配置、mAutoLowPowerModeSnoozing为false、低电量                && !mAutoLowPowerModeSnoozing && mBatteryLevelLow;        final boolean lowPowerModeEnabled = mLowPowerModeSetting || autoLowPowerModeEnabled;//主动的低电量模式只要开启，不在充电就可以了；主动模式和自动模式两者满足其一，就开启低电量模式        if (mLowPowerModeEnabled != lowPowerModeEnabled) {            mLowPowerModeEnabled = lowPowerModeEnabled;            powerHintInternal(POWER_HINT_LOW_POWER, lowPowerModeEnabled ? 1 : 0);//将低功耗模式，以及是否开启通过JNI，到hardware的power模块，但是我们hardware的power模块好像还不支持低功耗模式            BackgroundThread.getHandler().post(new Runnable() {//在消息线程里面处理                @Override                public void run() {                    Intent intent = new Intent(PowerManager.ACTION_POWER_SAVE_MODE_CHANGING)//发送正在处理低功耗的广播                            .putExtra(PowerManager.EXTRA_POWER_SAVE_MODE, mLowPowerModeEnabled)                            .addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);                    mContext.sendBroadcast(intent);                    ArrayList<PowerManagerInternal.LowPowerModeListener> listeners;                    synchronized (mLock) {                        listeners = new ArrayList<PowerManagerInternal.LowPowerModeListener>(                                mLowPowerModeListeners);                    }                    for (int i=0; i<listeners.size(); i++) {                        listeners.get(i).onLowPowerModeChanged(lowPowerModeEnabled);//这里也是像MountService中一样是注册的各个回调，后续去看看都有谁注册了这些回调。                    }                    intent = new Intent(PowerManager.ACTION_POWER_SAVE_MODE_CHANGED);//发送低功耗处理完了的广播                    intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);                    mContext.sendBroadcast(intent);                }            });        }    }

通过binder接口setPowerSaveMode设置低功耗模式

        @Override // Binder call        public boolean setPowerSaveMode(boolean mode) {            mContext.enforceCallingOrSelfPermission(                    android.Manifest.permission.DEVICE_POWER, null);            final long ident = Binder.clearCallingIdentity();            try {                return setLowPowerModeInternal(mode);            } finally {                Binder.restoreCallingIdentity(ident);            }        }

setLowPowerModeInternal函数，如果在充电直接返回

    private boolean setLowPowerModeInternal(boolean mode) {        synchronized (mLock) {            if (DEBUG) Slog.d(TAG, "setLowPowerModeInternal " + mode + " mIsPowered=" + mIsPowered);            if (mIsPowered) {                return false;            }            Settings.Global.putInt(mContext.getContentResolver(),//将手动模式保存                    Settings.Global.LOW_POWER_MODE, mode ? 1 : 0);            mLowPowerModeSetting = mode;            if (mAutoLowPowerModeConfigured && mBatteryLevelLow) {//如果自动模式开启，并且低电量的时候                if (mode && mAutoLowPowerModeSnoozing) {                    if (DEBUG_SPEW) {                        Slog.d(TAG, "setLowPowerModeInternal: clearing low power mode snooze");                    }                    mAutoLowPowerModeSnoozing = false; //这个参数为false，是自动低功耗模式开启的必要条件                } else if (!mode && !mAutoLowPowerModeSnoozing) {                    if (DEBUG_SPEW) {                        Slog.d(TAG, "setLowPowerModeInternal: snoozing low power mode");                    }                    mAutoLowPowerModeSnoozing = true;                }            }            updateLowPowerModeLocked();//更新低功耗模式            return true;        }    }

低功耗模式可以通过setPowerSaveMode接口设置，也可以通过Setting中的数据库监听来设置。

而当省电模式改变时，又有两种模式通知，一种是发广播，另一种的通知回调。上面在updateLowPowerModeLocked已经有描述。

注册回调的接口

        @Override        public void registerLowPowerModeObserver(LowPowerModeListener listener) {            synchronized (mLock) {                mLowPowerModeListeners.add(listener);            }        }

因为是LocalService的接口只能是SystemServer注册的。

下面我们来看看到底会通知那些服务或者应用。

1.回调通知

在NetworkPolicyManagerService会监听，进入省电模式后，网络切断。

BatteryStatsService、VibratorService、WindowManagerService(不放动画)也会处理。

2.广播通知

而广播的是GpsLocationProvider(关闭Gps)，PowerUI(显示通知栏等)、声音处理等。

五、继续systemReady函数

继续分析systemReady函数:

            readConfigurationLocked();//读取资源中的配置信息            updateSettingsLocked();            mDirty |= DIRTY_BATTERY_STATE;//修改mDirty 状态            updatePowerStateLocked();//更新power状态        }    }

readConfigurationLocked函数

private void readConfigurationLocked() {        final Resources resources = mContext.getResources();        mDecoupleHalAutoSuspendModeFromDisplayConfig = resources.getBoolean(                com.android.internal.R.bool.config_powerDecoupleAutoSuspendModeFromDisplay);        mDecoupleHalInteractiveModeFromDisplayConfig = resources.getBoolean(                com.android.internal.R.bool.config_powerDecoupleInteractiveModeFromDisplay);        mWakeUpWhenPluggedOrUnpluggedConfig = resources.getBoolean(                com.android.internal.R.bool.config_unplugTurnsOnScreen);        mWakeUpWhenPluggedOrUnpluggedInTheaterModeConfig = resources.getBoolean(                com.android.internal.R.bool.config_allowTheaterModeWakeFromUnplug);        mSuspendWhenScreenOffDueToProximityConfig = resources.getBoolean(                com.android.internal.R.bool.config_suspendWhenScreenOffDueToProximity);        mDreamsSupportedConfig = resources.getBoolean(                com.android.internal.R.bool.config_dreamsSupported);        mDreamsEnabledByDefaultConfig = resources.getBoolean(                com.android.internal.R.bool.config_dreamsEnabledByDefault);        mDreamsActivatedOnSleepByDefaultConfig = resources.getBoolean(                com.android.internal.R.bool.config_dreamsActivatedOnSleepByDefault);        mDreamsActivatedOnDockByDefaultConfig = resources.getBoolean(                com.android.internal.R.bool.config_dreamsActivatedOnDockByDefault);        mDreamsEnabledOnBatteryConfig = resources.getBoolean(                com.android.internal.R.bool.config_dreamsEnabledOnBattery);        mDreamsBatteryLevelMinimumWhenPoweredConfig = resources.getInteger(                com.android.internal.R.integer.config_dreamsBatteryLevelMinimumWhenPowered);        mDreamsBatteryLevelMinimumWhenNotPoweredConfig = resources.getInteger(                com.android.internal.R.integer.config_dreamsBatteryLevelMinimumWhenNotPowered);        mDreamsBatteryLevelDrainCutoffConfig = resources.getInteger(                com.android.internal.R.integer.config_dreamsBatteryLevelDrainCutoff);        mDozeAfterScreenOffConfig = resources.getBoolean(                com.android.internal.R.bool.config_dozeAfterScreenOff);        mMinimumScreenOffTimeoutConfig = resources.getInteger(                com.android.internal.R.integer.config_minimumScreenOffTimeout);        mMaximumScreenDimDurationConfig = resources.getInteger(                com.android.internal.R.integer.config_maximumScreenDimDuration);        mMaximumScreenDimRatioConfig = resources.getFraction(                com.android.internal.R.fraction.config_maximumScreenDimRatio, 1, 1);    }

好那么pms的一些初始化工作分析完了，下面接下来分析。