Android 6.0 PowerManagerService 之 updatePowerStateLocked函数

updatePowerStateLocked

/**
* Updates the global power state based on dirty bits recorded in mDirty.
*
* This is the main function that performs power state transitions.
* We centralize them here so that we can recompute the power state completely
* each time something important changes, and ensure that we do it the same
* way each time.  The point is to gather all of the transition logic here.
*/
private void updatePowerStateLocked() {
if (!mSystemReady || mDirty == 0) {
return;
}
if (!Thread.holdsLock(mLock)) {
Slog.wtf(TAG, "Power manager lock was not held when calling updatePowerStateLocked");
}

Trace.traceBegin(Trace.TRACE_TAG_POWER, "updatePowerState");
try {
// Phase 0: Basic state updates.
updateIsPoweredLocked(mDirty);
updateStayOnLocked(mDirty);
updateScreenBrightnessBoostLocked(mDirty);

// Phase 1: Update wakefulness.
// Loop because the wake lock and user activity computations are influenced
// by changes in wakefulness.
final long now = SystemClock.uptimeMillis();
int dirtyPhase2 = 0;
for (;;) {
int dirtyPhase1 = mDirty;
dirtyPhase2 |= dirtyPhase1;
mDirty = 0;

updateWakeLockSummaryLocked(dirtyPhase1);
updateUserActivitySummaryLocked(now, dirtyPhase1);
if (!updateWakefulnessLocked(dirtyPhase1)) {
break;
}
}

// Phase 2: Update display power state.
boolean displayBecameReady = updateDisplayPowerStateLocked(dirtyPhase2);

// Phase 3: Update dream state (depends on display ready signal).
updateDreamLocked(dirtyPhase2, displayBecameReady);

// Phase 4: Send notifications, if needed.
finishWakefulnessChangeIfNeededLocked();

// Phase 5: Update suspend blocker.
// Because we might release the last suspend blocker here, we need to make sure
// we finished everything else first!
updateSuspendBlockerLocked();
} finally {
Trace.traceEnd(Trace.TRACE_TAG_POWER);
}
}

updateIsPoweredLocked

/**
* Updates the value of mIsPowered.
* Sets DIRTY_IS_POWERED if a change occurred.
*/
private void updateIsPoweredLocked(int dirty) {
if ((dirty & DIRTY_BATTERY_STATE) != 0) {
final boolean wasPowered = mIsPowered;
final int oldPlugType = mPlugType;
final boolean oldLevelLow = mBatteryLevelLow;
mIsPowered = mBatteryManagerInternal.isPowered(BatteryManager.BATTERY_PLUGGED_ANY);//从BatteryService获取
mPlugType = mBatteryManagerInternal.getPlugType();
mBatteryLevel = mBatteryManagerInternal.getBatteryLevel();
mBatteryLevelLow = mBatteryManagerInternal.getBatteryLevelLow();

if (DEBUG_SPEW) {
Slog.d(TAG, "updateIsPoweredLocked: wasPowered=" + wasPowered
+ ", mIsPowered=" + mIsPowered
+ ", oldPlugType=" + oldPlugType
+ ", mPlugType=" + mPlugType
+ ", mBatteryLevel=" + mBatteryLevel);
}

if (wasPowered != mIsPowered || oldPlugType != mPlugType) {
mDirty |= DIRTY_IS_POWERED;

// Update wireless dock detection state.
final boolean dockedOnWirelessCharger = mWirelessChargerDetector.update(
mIsPowered, mPlugType, mBatteryLevel);

// Treat plugging and unplugging the devices as a user activity.
// Users find it disconcerting when they plug or unplug the device
// and it shuts off right away.
// Some devices also wake the device when plugged or unplugged because
// they don't have a charging LED.
final long now = SystemClock.uptimeMillis();
if (shouldWakeUpWhenPluggedOrUnpluggedLocked(wasPowered, oldPlugType,
dockedOnWirelessCharger)) {//是否需要唤醒设备
wakeUpNoUpdateLocked(now, "android.server.power:POWER", Process.SYSTEM_UID,
mContext.getOpPackageName(), Process.SYSTEM_UID);
}
userActivityNoUpdateLocked(
now, PowerManager.USER_ACTIVITY_EVENT_OTHER, 0, Process.SYSTEM_UID);

// Tell the notifier whether wireless charging has started so that
// it can provide feedback to the user.
if (dockedOnWirelessCharger) {
mNotifier.onWirelessChargingStarted();
}
}

if (wasPowered != mIsPowered || oldLevelLow != mBatteryLevelLow) {
if (oldLevelLow != mBatteryLevelLow && !mBatteryLevelLow) {
if (DEBUG_SPEW) {
Slog.d(TAG, "updateIsPoweredLocked: resetting low power snooze");
}
mAutoLowPowerModeSnoozing = false;
}
updateLowPowerModeLocked();//更新低功耗模式
}
}
}

首先systemReady函数会把mDirty置位为DIRTY_BATTERY_STATE，还有收BatterySevice发出来的广播，也会置这个标志位

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();
}

shouldWakeUpWhenPluggedOrUnpluggedLocked

private boolean shouldWakeUpWhenPluggedOrUnpluggedLocked(
boolean wasPowered, int oldPlugType, boolean dockedOnWirelessCharger) {
// Don't wake when powered unless configured to do so.
if (!mWakeUpWhenPluggedOrUnpluggedConfig) {
return false;
}

// Don't wake when undocked from wireless charger.
// See WirelessChargerDetector for justification.
if (wasPowered && !mIsPowered
&& oldPlugType == BatteryManager.BATTERY_PLUGGED_WIRELESS) {
return false;
}

// Don't wake when docked on wireless charger unless we are certain of it.
// See WirelessChargerDetector for justification.
if (!wasPowered && mIsPowered
&& mPlugType == BatteryManager.BATTERY_PLUGGED_WIRELESS
&& !dockedOnWirelessCharger) {
return false;
}

// If already dreaming and becoming powered, then don't wake.
if (mIsPowered && mWakefulness == WAKEFULNESS_DREAMING) {
return false;
}

// Don't wake while theater mode is enabled.
if (mTheaterModeEnabled && !mWakeUpWhenPluggedOrUnpluggedInTheaterModeConfig) {
return false;
}

// Otherwise wake up!
return true;
}

updateStayOnLocked

继续分析updatePowerStateLocked函数，分析updateStayOnLocked函数。一般这个函数mStatyon为fasle，除非在资源中设置哪种充电状态下可以长亮。

/**
* Updates the value of mStayOn.
* Sets DIRTY_STAY_ON if a change occurred.
*/
private void updateStayOnLocked(int dirty) {
if ((dirty & (DIRTY_BATTERY_STATE | DIRTY_SETTINGS)) != 0) {//当dirty是电池状态和设置的状态改变时
final boolean wasStayOn = mStayOn;
if (mStayOnWhilePluggedInSetting != 0 //这个值从资源中读取，一般设置的话代表哪种充电时可以常亮
&& !isMaximumScreenOffTimeoutFromDeviceAdminEnforcedLocked()) {//看有没有设mMaximumScreenOffTimeoutFromDeviceAdmin屏幕最大亮屏时间，没设默认最大。那么这个函数返回是false
mStayOn = mBatteryManagerInternal.isPowered(mStayOnWhilePluggedInSetting);
} else {
mStayOn = false;
}

if (mStayOn != wasStayOn) {
mDirty |= DIRTY_STAY_ON;
}
}
}

updateScreenBrightnessBoostLocked

这个函数是更新屏幕是否保持最亮状态

private void updateScreenBrightnessBoostLocked(int dirty) {
//这个状态实在boostScreenBrightnessInternal函数中设置最亮时置位，当然下面发送消息MSG_SCREEN_BRIGHTNESS_BOOST_TIMEOUT也会将这个标志位置位
 if ((dirty & DIRTY_SCREEN_BRIGHTNESS_BOOST) != 0) {
if (mScreenBrightnessBoostInProgress) {//当前正在最亮屏幕这个状态
final long now = SystemClock.uptimeMillis();
mHandler.removeMessages(MSG_SCREEN_BRIGHTNESS_BOOST_TIMEOUT);
if (mLastScreenBrightnessBoostTime > mLastSleepTime) {
final long boostTimeout = mLastScreenBrightnessBoostTime +
SCREEN_BRIGHTNESS_BOOST_TIMEOUT;
if (boostTimeout > now) {//看当前时间是否小于最亮屏幕结束的时间
Message msg = mHandler.obtainMessage(MSG_SCREEN_BRIGHTNESS_BOOST_TIMEOUT);
msg.setAsynchronous(true);
mHandler.sendMessageAtTime(msg, boostTimeout);//发送一个延迟的消息，到最亮屏幕结束的时候接受到消息，将标志位置为DIRTY_SCREEN_BRIGHTNESS_BOOST后，重新再回到这个函数
return;
}
}
mScreenBrightnessBoostInProgress = false;
mNotifier.onScreenBrightnessBoostChanged();
userActivityNoUpdateLocked(now,
PowerManager.USER_ACTIVITY_EVENT_OTHER, 0, Process.SYSTEM_UID);
}
}
}

接下来看updatePowerStateLocked函数的另一个阶段,

// Phase 1: Update wakefulness.
// Loop because the wake lock and user activity computations are influenced
// by changes in wakefulness.
final long now = SystemClock.uptimeMillis();
int dirtyPhase2 = 0;
for (;;) {
int dirtyPhase1 = mDirty;//这个循环中每次新的mDirty全部给dirtyPhase1，并且在这个循环中使用这个dirty
dirtyPhase2 |= dirtyPhase1;//dirtyPhase2 会把之前所有的mDirty状态全部或上，然后用这个状态继续下面的函数
mDirty = 0;

updateWakeLockSummaryLocked(dirtyPhase1);
updateUserActivitySummaryLocked(now, dirtyPhase1);
if (!updateWakefulnessLocked(dirtyPhase1)) {
break;
}
}

updateWakeLockSummaryLocked

/**
* Updates the value of mWakeLockSummary to summarize the state of all active wake locks.
* Note that most wake-locks are ignored when the system is asleep.
*
* This function must have no other side-effects.
*/
@SuppressWarnings("deprecation")
private void updateWakeLockSummaryLocked(int dirty) {
if ((dirty & (DIRTY_WAKE_LOCKS | DIRTY_WAKEFULNESS)) != 0) {
mWakeLockSummary = 0;

final int numWakeLocks = mWakeLocks.size();
for (int i = 0; i < numWakeLocks; i++) {
final WakeLock wakeLock = mWakeLocks.get(i);
switch (wakeLock.mFlags & PowerManager.WAKE_LOCK_LEVEL_MASK) {
case PowerManager.PARTIAL_WAKE_LOCK:
if (!wakeLock.mDisabled) {
// We only respect this if the wake lock is not disabled.
mWakeLockSummary |= WAKE_LOCK_CPU;
}
break;
case PowerManager.FULL_WAKE_LOCK:
mWakeLockSummary |= WAKE_LOCK_SCREEN_BRIGHT | WAKE_LOCK_BUTTON_BRIGHT;
break;
case PowerManager.SCREEN_BRIGHT_WAKE_LOCK:
mWakeLockSummary |= WAKE_LOCK_SCREEN_BRIGHT;
break;
case PowerManager.SCREEN_DIM_WAKE_LOCK:
mWakeLockSummary |= WAKE_LOCK_SCREEN_DIM;
break;
case PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK:
mWakeLockSummary |= WAKE_LOCK_PROXIMITY_SCREEN_OFF;
break;
case PowerManager.DOZE_WAKE_LOCK:
mWakeLockSummary |= WAKE_LOCK_DOZE;
break;
case PowerManager.DRAW_WAKE_LOCK:
mWakeLockSummary |= WAKE_LOCK_DRAW;
break;
}
}

// Cancel wake locks that make no sense based on the current state.
if (mWakefulness != WAKEFULNESS_DOZING) {
mWakeLockSummary &= ~(WAKE_LOCK_DOZE | WAKE_LOCK_DRAW);//下面根据各种状态，将上面或上的mWakeLockSummary，减去
}
if (mWakefulness == WAKEFULNESS_ASLEEP
|| (mWakeLockSummary & WAKE_LOCK_DOZE) != 0) {
mWakeLockSummary &= ~(WAKE_LOCK_SCREEN_BRIGHT | WAKE_LOCK_SCREEN_DIM
| WAKE_LOCK_BUTTON_BRIGHT);
if (mWakefulness == WAKEFULNESS_ASLEEP) {
mWakeLockSummary &= ~WAKE_LOCK_PROXIMITY_SCREEN_OFF;
}
}

// Infer implied wake locks where necessary based on the current state.
if ((mWakeLockSummary & (WAKE_LOCK_SCREEN_BRIGHT | WAKE_LOCK_SCREEN_DIM)) != 0) {//只要有屏幕锁，cpu锁必须持有
if (mWakefulness == WAKEFULNESS_AWAKE) {
mWakeLockSummary |= WAKE_LOCK_CPU | WAKE_LOCK_STAY_AWAKE;
} else if (mWakefulness == WAKEFULNESS_DREAMING) {
mWakeLockSummary |= WAKE_LOCK_CPU;
}
}
if ((mWakeLockSummary & WAKE_LOCK_DRAW) != 0) {
mWakeLockSummary |= WAKE_LOCK_CPU;
}

if (DEBUG_SPEW) {
Slog.d(TAG, "updateWakeLockSummaryLocked: mWakefulness="
+ PowerManagerInternal.wakefulnessToString(mWakefulness)
+ ", mWakeLockSummary=0x" + Integer.toHexString(mWakeLockSummary));
}
}
}

updateUserActivitySummaryLocked

/**
* Updates the value of mUserActivitySummary to summarize the user requested
* state of the system such as whether the screen should be bright or dim.
* Note that user activity is ignored when the system is asleep.
*
* This function must have no other side-effects.
*/
private void updateUserActivitySummaryLocked(long now, int dirty) {
// Update the status of the user activity timeout timer.
if ((dirty & (DIRTY_WAKE_LOCKS | DIRTY_USER_ACTIVITY
| DIRTY_WAKEFULNESS | DIRTY_SETTINGS)) != 0) {
mHandler.removeMessages(MSG_USER_ACTIVITY_TIMEOUT);

long nextTimeout = 0;
if (mWakefulness == WAKEFULNESS_AWAKE
|| mWakefulness == WAKEFULNESS_DREAMING
|| mWakefulness == WAKEFULNESS_DOZING) {
final int sleepTimeout = getSleepTimeoutLocked();
final int screenOffTimeout = getScreenOffTimeoutLocked(sleepTimeout);
final int screenDimDuration = getScreenDimDurationLocked(screenOffTimeout);

mUserActivitySummary = 0;
if (mLastUserActivityTime >= mLastWakeTime) {//userActivity的time大于上次唤醒时间
nextTimeout = mLastUserActivityTime
+ screenOffTimeout - screenDimDuration;
if (now < nextTimeout) {
mUserActivitySummary = USER_ACTIVITY_SCREEN_BRIGHT;
} else {
nextTimeout = mLastUserActivityTime + screenOffTimeout;
if (now < nextTimeout) {
mUserActivitySummary = USER_ACTIVITY_SCREEN_DIM;
}
}
}
if (mUserActivitySummary == 0
&& mLastUserActivityTimeNoChangeLights >= mLastWakeTime) {
nextTimeout = mLastUserActivityTimeNoChangeLights + screenOffTimeout;
if (now < nextTimeout) {
if (mDisplayPowerRequest.policy == DisplayPowerRequest.POLICY_BRIGHT) {
mUserActivitySummary = USER_ACTIVITY_SCREEN_BRIGHT;
} else if (mDisplayPowerRequest.policy == DisplayPowerRequest.POLICY_DIM) {
mUserActivitySummary = USER_ACTIVITY_SCREEN_DIM;
}
}
}
if (mUserActivitySummary == 0) {
if (sleepTimeout >= 0) {
final long anyUserActivity = Math.max(mLastUserActivityTime,
mLastUserActivityTimeNoChangeLights);
if (anyUserActivity >= mLastWakeTime) {
nextTimeout = anyUserActivity + sleepTimeout;
if (now < nextTimeout) {
mUserActivitySummary = USER_ACTIVITY_SCREEN_DREAM;
}
}
} else {
mUserActivitySummary = USER_ACTIVITY_SCREEN_DREAM;
nextTimeout = -1;//该值为-1，下面就不会发送消息了
}
}
if (mUserActivitySummary != 0 && nextTimeout >= 0) {
Message msg = mHandler.obtainMessage(MSG_USER_ACTIVITY_TIMEOUT);
msg.setAsynchronous(true);
mHandler.sendMessageAtTime(msg, nextTimeout);
}
} else {
mUserActivitySummary = 0;
}

if (DEBUG_SPEW) {
Slog.d(TAG, "updateUserActivitySummaryLocked: mWakefulness="
+ PowerManagerInternal.wakefulnessToString(mWakefulness)
+ ", mUserActivitySummary=0x" + Integer.toHexString(mUserActivitySummary)
+ ", nextTimeout=" + TimeUtils.formatUptime(nextTimeout));
}
}
}

MSG_USER_ACTIVITY_TIMEOUT的消息处理

/**
* Handler for asynchronous operations performed by the power manager.
*/
private final class PowerManagerHandler extends Handler {
public PowerManagerHandler(Looper looper) {
super(looper, null, true /*async*/);
}

@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_USER_ACTIVITY_TIMEOUT:
handleUserActivityTimeout();
break;
case MSG_SANDMAN:
handleSandman();
break;
case MSG_SCREEN_BRIGHTNESS_BOOST_TIMEOUT:
handleScreenBrightnessBoostTimeout();
break;
}
}
}

updateWakefulnessLocked

/**
* Updates the wakefulness of the device.
*
* This is the function that decides whether the device should start dreaming
* based on the current wake locks and user activity state.  It may modify mDirty
* if the wakefulness changes.
*
* Returns true if the wakefulness changed and we need to restart power state calculation.
*/
private boolean updateWakefulnessLocked(int dirty) {
boolean changed = false;
if ((dirty & (DIRTY_WAKE_LOCKS | DIRTY_USER_ACTIVITY | DIRTY_BOOT_COMPLETED
| DIRTY_WAKEFULNESS | DIRTY_STAY_ON | DIRTY_PROXIMITY_POSITIVE
| DIRTY_DOCK_STATE)) != 0) {
if (mWakefulness == WAKEFULNESS_AWAKE && isItBedTimeYetLocked()) {
if (DEBUG_SPEW) {
Slog.d(TAG, "updateWakefulnessLocked: Bed time...");
}
final long time = SystemClock.uptimeMillis();
if (shouldNapAtBedTimeLocked()) {
changed = napNoUpdateLocked(time, Process.SYSTEM_UID);
} else {
changed = goToSleepNoUpdateLocked(time,
PowerManager.GO_TO_SLEEP_REASON_TIMEOUT, 0, Process.SYSTEM_UID);
}
}
}
return changed;
}

再来看看isItBedTimeYetLocked函数，isBeingKeptAwakeLocked函数，如果isBeingKeptAwakeLocked返回true代表处于亮屏状态，isItBedTimeYetLocked返回false，上面的for死循环退出

/**
* Returns true if the device is being kept awake by a wake lock, user activity
* or the stay on while powered setting.  We also keep the phone awake when
* the proximity sensor returns a positive result so that the device does not
* lock while in a phone call.  This function only controls whether the device
* will go to sleep or dream which is independent of whether it will be allowed
* to suspend.
*/
private boolean isBeingKeptAwakeLocked() {
return mStayOn
|| mProximityPositive
|| (mWakeLockSummary & WAKE_LOCK_STAY_AWAKE) != 0
|| (mUserActivitySummary & (USER_ACTIVITY_SCREEN_BRIGHT
| USER_ACTIVITY_SCREEN_DIM)) != 0
|| mScreenBrightnessBoostInProgress;
}

如果isBeingKeptAwakeLocked返回false，并且mBootCompleted 为true开机完成了。那么updateWakefulnessLocked函数进入判断条件

那再来看看shouldNapAtBedTimeLocked函数，就是看有没有做梦这个设置，如果没有直接到goToSleepNoUpdateLocked函数，到了goToSleepNoUpdateLocked函数后将mWakefulness 设为WAKEFULNESS_DOZING显示返回true还要继续循环，下次到updateWakefulnessLocked这个函数，不是awake类型的，也返回false，直接退出死循环了。到napNoUpdateLocked函数也是一样的先是将mWakefulness置为WAKEFULNESS_DREAMING，返回true，继续循环，下次不是awake类型就返回false，退出循环了。

/**
* Returns true if the device should automatically nap and start dreaming when the user
* activity timeout has expired and it's bedtime.
*/
private boolean shouldNapAtBedTimeLocked() {
return mDreamsActivateOnSleepSetting
|| (mDreamsActivateOnDockSetting
&& mDockState != Intent.EXTRA_DOCK_STATE_UNDOCKED);
}

下篇博客继续分析updatePowerStateLocked中的

// Phase 2: Update display power state.
boolean displayBecameReady = updateDisplayPowerStateLocked(dirtyPhase2);