Click the power saving mode button in the drop-down bar of SystuemUI. The first call is setPowerSaveMode() of BatteryControllerImpl.java
@Override
public void setPowerSaveMode(boolean powerSave) {
BatterySaverUtils.setPowerSaveMode(mContext, powerSave, /*needFirstTimeWarning*/ true);
}
When the power saving mode is activated, the parameter here powerSavewill be set to true, and BatterySaverUtils is SettingsLiba class in
public static synchronized boolean setPowerSaveMode(Context context,
boolean enable, boolean needFirstTimeWarning) {
if (DEBUG) {
Log.d(TAG, "Battery saver turning " + (enable ? "ON" : "OFF"));
}
final ContentResolver cr = context.getContentResolver();
if (enable && needFirstTimeWarning && maybeShowBatterySaverConfirmation(context)) {
return false;
}
if (enable && !needFirstTimeWarning) {
setBatterySaverConfirmationAcknowledged(context);
}
if (context.getSystemService(PowerManager.class).setPowerSaveMode(enable)) {
if (enable) {
final int count =
Secure.getInt(cr, Secure.LOW_POWER_MANUAL_ACTIVATION_COUNT, 0) + 1;
Secure.putInt(cr, Secure.LOW_POWER_MANUAL_ACTIVATION_COUNT, count);
final Parameters parameters = new Parameters(context);
if ((count >= parameters.startNth)
&& (count <= parameters.endNth)
&& Global.getInt(cr, Global.LOW_POWER_MODE_TRIGGER_LEVEL, 0) == 0
&& Secure.getInt(cr,
Secure.SUPPRESS_AUTO_BATTERY_SAVER_SUGGESTION, 0) == 0) {
showAutoBatterySaverSuggestion(context);
}
}
return true;
}
return false;
}In this class, the method implemented is mainly context.getSystemService(PowerManager.class).setPowerSaveMode(enable).
It will get the PowerManager object through getSystemService, and then call the setPowerSaveMode function to make specific settings.
PowerManager.java-->setPowerSaveMode()
public boolean setPowerSaveMode(boolean mode) {
try {
return mService.setPowerSaveMode(mode);
} catch (RemoteException e) {
throw e.rethrowFromSystemServer();
}
}PowerManagerService.java-->setPowerSaveMode()
@Override // Binder call
public boolean setPowerSaveMode(boolean enabled) {
mContext.enforceCallingOrSelfPermission(
android.Manifest.permission.DEVICE_POWER, null);
final long ident = Binder.clearCallingIdentity();
try {
return setLowPowerModeInternal(enabled);
} finally {
Binder.restoreCallingIdentity(ident);
}
}First call enforceCallingOrSelfPermission to check permissions, and then call setLowPowerModeInternal()
private boolean setLowPowerModeInternal(boolean enabled) {
synchronized (mLock) {
if (DEBUG) {
Slog.d(TAG, "setLowPowerModeInternal " + enabled + " mIsPowered=" + mIsPowered);
}
mBatterySaverStateMachine.setBatterySaverEnabledManually(enabled);
return true;
}
}Manual switch power saving mode:
BatterySaverStateMachine.java-->setBatterySaverEnabledManually()
public void setBatterySaverEnabledManually(boolean enabled) {
if (DEBUG) {
Slog.d(TAG, "setBatterySaverEnabledManually: enabled=" + enabled);
}
synchronized (mLock) {
enableBatterySaverLocked(/*enable=*/ enabled, /*manual=*/ true,
(enabled ? BatterySaverController.REASON_MANUAL_ON
: BatterySaverController.REASON_MANUAL_OFF),
(enabled ? "Manual ON" : "Manual OFF"));
}
}BatterySaverStateMachine.java-->enableBatterySaverLocked()
/**
* Actually enable / disable battery saver. Write the new state to the global settings
* and propagate it to {@link #mBatterySaverController}.
*/
private void enableBatterySaverLocked(boolean enable, boolean manual, int intReason,
String strReason) {
if (DEBUG) {
Slog.d(TAG, "enableBatterySaver: enable=" + enable + " manual=" + manual
+ " reason=" + strReason + "(" + intReason + ")");
}
final boolean wasEnabled = mBatterySaverController.isEnabled();
//省电模式状态没有改变的话直接return
if (wasEnabled == enable) {
if (DEBUG) {
Slog.d(TAG, "Already " + (enable ? "enabled" : "disabled"));
}
return;
}
//充电情况下尝试打开 省电模式 直接return
if (enable && mIsPowered) {
if (DEBUG) Slog.d(TAG, "Can't enable: isPowered");
return;
}
//记录此次改变省电模式状态的 reason ，各个 reason 的值定义在 BatterySaverController 中
mLastChangedIntReason = intReason;
mLastChangedStrReason = strReason;
//mBatterySaverSnoozing 主要是用于记录 低电量情况下，用户是否手动关闭 了省电模式，防止用户手动关闭 省电模式后，又被自动打开
if (manual) {
if (enable) {
updateSnoozingLocked(false, "Manual snooze OFF");
} else {
// When battery saver is disabled manually (while battery saver is enabled)
// when the battery level is low, we "snooze" BS -- i.e. disable auto battery saver.
// We resume auto-BS once the battery level is not low, or the device is plugged in.
if (isBatterySaverEnabled() && mIsBatteryLevelLow) {
updateSnoozingLocked(true, "Manual snooze");
}
}
}
mSettingBatterySaverEnabled = enable;
//更新 省电模式状态 到 settings 数据库字段中
putGlobalSetting(Global.LOW_POWER_MODE, enable ? 1 : 0);
if (manual) {
mSettingBatterySaverEnabledSticky = enable;
putGlobalSetting(Global.LOW_POWER_MODE_STICKY, enable ? 1 : 0);
}
//好了，前面这些全部都是前戏，这里才开始真正的做 省电的动作
mBatterySaverController.enableBatterySaver(enable, intReason);
if (DEBUG) {
Slog.d(TAG, "Battery saver: Enabled=" + enable
+ " manual=" + manual
+ " reason=" + strReason + "(" + intReason + ")");
}
}1. WasEnabled will first determine whether it has been enabled before, and if it is, then return.
2. If isPowered is true, it will return directly.
3.mLastChangedIntReason, the value of mLastChangedStrReason will be saved as the value passed in before, that is, mLastChangedIntReason=2, mLastChangedStrReason="Manual ON".
4. Both manual and enable are in the true state, so it will upateSnoozingLocked. And this function is actually Just set the value of mBatterySaverSnoozing to true. And the use of this value, we will encounter later.
5.putGlobalSetting(Global.LOW_POWER_MODE, enable? 1: 0);, set the value of LOW_POWER_MODE to 1.
6.putGlobalSetting(Global.LOW_POWER_MODE_STICKY, enable? 1: 0);, set the value of LOW_POWER_MODE_STICKY in the database Set to 1.
7.mBatterySaverController.enableBatterySaver(enable, intReason); After saving the corresponding database, this function will be called to perform the actual operation.
BatterySaverController.java-->enableBatterySaver()
/**
* Called by {@link PowerManagerService} to update the battery saver stete.
*/
public void enableBatterySaver(boolean enable, int reason) {
synchronized (mLock) {
if (mEnabled == enable) {
return;
}
mEnabled = enable;
mHandler.postStateChanged(/*sendBroadcast=*/ true, reason);
}
}In calling the enableBatterySaver function of the controller, mEnable is mainly set to true. And pass the actual reason to the Handler.
public void postStateChanged(boolean sendBroadcast, int reason) {
obtainMessage(MSG_STATE_CHANGED, sendBroadcast ?
ARG_SEND_BROADCAST : ARG_DONT_SEND_BROADCAST, reason).sendToTarget();
} @Override
public void dispatchMessage(Message msg) {
switch (msg.what) {
case MSG_STATE_CHANGED:
handleBatterySaverStateChanged(
msg.arg1 == ARG_SEND_BROADCAST,
msg.arg2);
break;
case MSG_SYSTEM_READY:
for (Plugin p : mPlugins) {
p.onSystemReady(BatterySaverController.this);
}
break;
}
}BatterySaverController.java-->handleBatterySaverStateChanged()
/**
* Dispatch power save events to the listeners.
*
* This method is always called on the handler thread.
*
* This method is called only in the following cases:
* - When battery saver becomes activated.
* - When battery saver becomes deactivated.
* - When battery saver is on the interactive state changes.
* - When battery saver is on the battery saver policy changes.
*/
void handleBatterySaverStateChanged(boolean sendBroadcast, int reason) {
final LowPowerModeListener[] listeners;
final boolean enabled;
//isInteractive 用于标志设备是否处于可交互状态
final boolean isInteractive = getPowerManager().isInteractive();
final ArrayMap<String, String> fileValues;
synchronized (mLock) {
//battery_saver_mode: [1,0,1,,1] event log的格式，大致含义根据变量名就可以看出来
EventLogTags.writeBatterySaverMode(
mPreviouslyEnabled ? 1 : 0, // Previously off or on.
mEnabled ? 1 : 0, // Now off or on.
isInteractive ? 1 : 0, // Device interactive state.
mEnabled ? mBatterySaverPolicy.toEventLogString() : "",
reason);
mPreviouslyEnabled = mEnabled;
listeners = mListeners.toArray(new LowPowerModeListener[mListeners.size()]);
enabled = mEnabled;
mIsInteractive = isInteractive;
if (enabled) {
fileValues = mBatterySaverPolicy.getFileValues(isInteractive);
} else {
fileValues = null;
}
}
//似乎是 CPU 频率相关的设置，下面是 到JNI里，没有去跟
final PowerManagerInternal pmi = LocalServices.getService(PowerManagerInternal.class);
if (pmi != null) {
pmi.powerHint(PowerHint.LOW_POWER, enabled ? 1 : 0);
}
updateBatterySavingStats();
if (ArrayUtils.isEmpty(fileValues)) {
mFileUpdater.restoreDefault();
} else {
mFileUpdater.writeFiles(fileValues);
}
//目前来看，原生的代码里只有一种 BatterySaverLocationPlugin
// plugins.add(new BatterySaverLocationPlugin(mContext));
for (Plugin p : mPlugins) {
p.onBatterySaverChanged(this);
}
if (sendBroadcast) {
if (DEBUG) {
Slog.i(TAG, "Sending broadcasts for mode: " + enabled);
}
// Send the broadcasts and notify the listeners. We only do this when the battery saver
// mode changes, but not when only the screen state changes.
Intent intent = new Intent(PowerManager.ACTION_POWER_SAVE_MODE_CHANGING)
.putExtra(PowerManager.EXTRA_POWER_SAVE_MODE, enabled)
.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
mContext.sendBroadcastAsUser(intent, UserHandle.ALL);
intent = new Intent(PowerManager.ACTION_POWER_SAVE_MODE_CHANGED);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
mContext.sendBroadcastAsUser(intent, UserHandle.ALL);
// Send internal version that requires signature permission.
intent = new Intent(PowerManager.ACTION_POWER_SAVE_MODE_CHANGED_INTERNAL);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
mContext.sendBroadcastAsUser(intent, UserHandle.ALL,
Manifest.permission.DEVICE_POWER);
//回调 所有注册了 LowPowerModeListener 的client
//主要有 VibratorService，NetworkPolicyManagerService，WindowManagerService
for (LowPowerModeListener listener : listeners) {
final PowerSaveState result =
mBatterySaverPolicy.getBatterySaverPolicy(
listener.getServiceType(), enabled);
listener.onLowPowerModeChanged(result);
}
}
}1. First call final boolean isInteractive = getPowerManager().isInteractive();
public static boolean isInteractive(int wakefulness) {
return wakefulness == WAKEFULNESS_AWAKE || wakefulness == WAKEFULNESS_DREAMING;
}In fact, it is judging whether wakefulnessthe value is WAKEFULNESS_AWAKEor WAKEFULNESS_DREAMING, so what does this value represent?
WAKEFULNESS_ASLEEP：表示系统当前处于休眠状态，只能被wakeUp()调用唤醒。
WAKEFULNESS_AWAKE：表示系统目前处于正常运行状态。
WAKEFULNESS_DREAMING：表示系统当前正处于互动屏保的状态。
WAKEFULNESS_DOZING：表示系统正处于“doze”状态
2. listeners = mListeners.toArray(new LowPowerModeListener[mListeners.size()]);
The mListeners here are actually all services that add LowPowerModeListener when registered before. Contains VibratorService, NetworkPolicyManagerService, etc. These contents will be saved once to facilitate subsequent message distribution.
3. Look at updateBatterySavingStats() below
private void updateBatterySavingStats() {
final PowerManager pm = getPowerManager();
if (pm == null) {
Slog.wtf(TAG, "PowerManager not initialized");
return;
}
final boolean isInteractive = pm.isInteractive();
final int dozeMode =
pm.isDeviceIdleMode() ? DozeState.DEEP
: pm.isLightDeviceIdleMode() ? DozeState.LIGHT
: DozeState.NOT_DOZING;
synchronized (mLock) {
if (mIsPluggedIn) {
mBatterySavingStats.startCharging();
return;
}
mBatterySavingStats.transitionState(
mEnabled ? BatterySaverState.ON : BatterySaverState.OFF,
isInteractive ? InteractiveState.INTERACTIVE : InteractiveState.NON_INTERACTIVE,
dozeMode);
}
}The core of this function is transitionState, but it is only used to save the current state, so we will not go into it.
fileValuesThe default is empty, we do not deal with analysis.- The next Plugin is a bit interesting, because it is operated by plug-ins.
for (Plugin p : mPlugins) {
p.onBatterySaverChanged(this);
}But the real realization, aosp only realizes one:
onBatterySaverChanged
frameworks/base/services/core/java/com/android/server/power/batterysaver/BatterySaverLocationPlugin.java
The specific implementation here is:
@Override
public void onBatterySaverChanged(BatterySaverController caller) {
if (DEBUG) {
Slog.d(TAG, "onBatterySaverChanged");
}
updateLocationState(caller);
} private void updateLocationState(BatterySaverController caller) {
final boolean kill =
(caller.getBatterySaverPolicy().getGpsMode()
== PowerManager.LOCATION_MODE_ALL_DISABLED_WHEN_SCREEN_OFF) &&
caller.isEnabled() && !caller.isInteractive();
boolean gpsMode = (caller.getBatterySaverPolicy().getGpsMode() == PowerManager.LOCATION_MODE_ALL_DISABLED_WHEN_SCREEN_OFF);
if (DEBUG) {
Slog.d(TAG, "Battery saver " + (kill ? "stopping" : "restoring") + " location.");
}
Settings.Global.putInt(mContext.getContentResolver(),
Global.LOCATION_GLOBAL_KILL_SWITCH, kill ? 1 : 0);
}We will then conduct a one-to-one analysis of the three broadcasts.
ACTION_POWER_SAVE_MODE_CHANGING
The broadcast first adds a flag asFLAG_RECEIVER_REGISTERED_ONLY, which means that only dynamically registered reception is possible.
The main accepted places are:
BatterySaverReceiver.java (PowerManager.ACTION_POWER_SAVE_MODE_CHANGING.equals(action))
BatteryControllerImpl.java (action.equals(PowerManager.ACTION_POWER_SAVE_MODE_CHANGING))
One is located in Packages/apps/Settings and the
other is frameworks/base/packages/SystemUI/.
For BatterySaverReceiver, the update here is mainly the status in the settings.
For sBatteryControllerImpl, the call here is
private void setPowerSave(boolean powerSave) {
if (powerSave == mPowerSave) return;
mPowerSave = powerSave;
// AOD power saving setting might be different from PowerManager power saving mode.
PowerSaveState state = mPowerManager.getPowerSaveState(PowerManager.ServiceType.AOD);
mAodPowerSave = state.batterySaverEnabled;
if (DEBUG) Log.d(TAG, "Power save is " + (mPowerSave ? "on" : "off"));
firePowerSaveChanged();
}
Here will PowerSavesave the state, and call the firePowerSaveChangedmethod to achieve.
private void firePowerSaveChanged() {
synchronized (mChangeCallbacks) {
final int N = mChangeCallbacks.size();
for (int i = 0; i < N; i++) {
mChangeCallbacks.get(i).onPowerSaveChanged(mPowerSave);
}
}
}Here will go to traverse mChangeCallbacks, and callback onPowerSaveChangedmethod.
The main methods for implementing callbacks are:
BatteryMeterView.java
StatusBar.java
KeyguardStatusBarView.java
LightBarController.java
BatterySaverTile.java
Here are some operations on SystemUI and interface display.
ACTION_POWER_SAVE_MODE_CHANGED
The broadcast is the same as the previous one, but it also adds a Flag: FLAG_RECEIVER_REGISTERED_ONLY
receiver. The main operations are:
BatteryBroadcastReceiver.java
(PowerManager.ACTION_POWER_SAVE_MODE_CHANGED.equals(intent.getAction())
BatteryControllerImpl.java
(action.equals(PowerManager.ACTION_POWER_SAVE_MODE_CHANGED))
PowerUI.java
(PowerManager.ACTION_POWER_SAVE_MODE_CHANGED.equals(action))
DeviceStateMonitor.java
case PowerManager.ACTION_POWER_SAVE_MODE_CHANGED:
SoundTriggerHelper.java
if (!PowerManager.ACTION_POWER_SAVE_MODE_CHANGED.equals(intent.getAction())) {
GnssLocationProvider.java
PowerManager.ACTION_POWER_SAVE_MODE_CHANGED.equals(action)
And what did these six broadcast receiving places do?
DeviceStateMonitorThe final call is as follows:
/**
* Send the device state to the modem.
*
* @param type Device state type. See DeviceStateType defined in types.hal.
* @param state True if enabled/on, otherwise disabled/off
*/
private void sendDeviceState(int type, boolean state) {
log("send type: " + deviceTypeToString(type) + ", state=" + state, true);
mPhone.mCi.sendDeviceState(type, state, null);
}
SoundTriggerHelperThe implementation of is to change the mIsPowerSaveModevalue, the effect is as follows:
// Whether we are allowed to run any recognition at all. The conditions that let us run
// a recognition include: no active phone call or not being in a power save mode. Also,
// the native service should be enabled.
private boolean isRecognitionAllowed() {
return !mCallActive && !mServiceDisabled && !mIsPowerSaveMode;
}GnssLocationProviderThe call is implemented as follows, which can be easily read from the comments.
private void updateLowPowerMode() {
// Disable GPS if we are in device idle mode.
boolean disableGps = mPowerManager.isDeviceIdleMode();
final PowerSaveState result =
mPowerManager.getPowerSaveState(ServiceType.GPS);
switch (result.gpsMode) {
case PowerManager.LOCATION_MODE_GPS_DISABLED_WHEN_SCREEN_OFF:
// If we are in battery saver mode and the screen is off, disable GPS.
disableGps |= result.batterySaverEnabled && !mPowerManager.isInteractive();
break;
}
if (disableGps != mDisableGps) {
mDisableGps = disableGps;
updateRequirements();
}
}Finally, an array callback function saved before:
for (LowPowerModeListener listener : listeners) {
final PowerSaveState result =
mBatterySaverPolicy.getBatterySaverPolicy(
listener.getServiceType(), enabled);
listener.onLowPowerModeChanged(result);
}Listeners were also mentioned in our previous article, here is a detailed summary:
| class | effect |
|---|---|
| VibratorService.java | Cancel the vibration effect of the phone |
| NetworkPolicyManagerService.java | Update the whitelist and restrictions on network access by applications |
| WindowManagerService.java | Cancel window animation |
NetworkPolicyManagerServiceThe call is as follows
// NOTE: since both fw_dozable and fw_powersave uses the same map
// (mPowerSaveTempWhitelistAppIds) for whitelisting, we can reuse their logic in this method.
private void updateRulesForWhitelistedPowerSaveUL(boolean enabled, int chain,
SparseIntArray rules) {
if (enabled) {
// Sync the whitelists before enabling the chain. We don't care about the rules if
// we are disabling the chain.
final SparseIntArray uidRules = rules;
uidRules.clear();
final List<UserInfo> users = mUserManager.getUsers();
for (int ui = users.size() - 1; ui >= 0; ui--) {
UserInfo user = users.get(ui);
updateRulesForWhitelistedAppIds(uidRules, mPowerSaveTempWhitelistAppIds, user.id);
updateRulesForWhitelistedAppIds(uidRules, mPowerSaveWhitelistAppIds, user.id);
if (chain == FIREWALL_CHAIN_POWERSAVE) {
updateRulesForWhitelistedAppIds(uidRules,
mPowerSaveWhitelistExceptIdleAppIds, user.id);
}
}
for (int i = mUidState.size() - 1; i >= 0; i--) {
if (isProcStateAllowedWhileIdleOrPowerSaveMode(mUidState.valueAt(i))) {
uidRules.put(mUidState.keyAt(i), FIREWALL_RULE_ALLOW);
}
}
setUidFirewallRulesUL(chain, uidRules, CHAIN_TOGGLE_ENABLE);
} else {
setUidFirewallRulesUL(chain, null, CHAIN_TOGGLE_DISABLE);
}
}- Updating the temporary whitelist, whitelist, and whitelists other than idle apps will allow network access
- If the process priority is above the foreground service, network access is allowed
private int updateRulesForPowerRestrictionsULInner(int uid, int oldUidRules, boolean paroled) {
if (!isUidValidForBlacklistRules(uid)) {
if (LOGD) Slog.d(TAG, "no need to update restrict power rules for uid " + uid);
return RULE_NONE;
}
final boolean isIdle = !paroled && isUidIdle(uid);
final boolean restrictMode = isIdle || mRestrictPower || mDeviceIdleMode;
final boolean isForeground = isUidForegroundOnRestrictPowerUL(uid);
final boolean isWhitelisted = isWhitelistedBatterySaverUL(uid, mDeviceIdleMode);
final int oldRule = oldUidRules & MASK_ALL_NETWORKS;
int newRule = RULE_NONE;
// First step: define the new rule based on user restrictions and foreground state.
// NOTE: if statements below could be inlined, but it's easier to understand the logic
// by considering the foreground and non-foreground states.
if (isForeground) {
if (restrictMode) {
newRule = RULE_ALLOW_ALL;
}
} else if (restrictMode) {
newRule = isWhitelisted ? RULE_ALLOW_ALL : RULE_REJECT_ALL;
}
final int newUidRules = (oldUidRules & MASK_METERED_NETWORKS) | newRule;
if (LOGV) {
Log.v(TAG, "updateRulesForPowerRestrictionsUL(" + uid + ")"
+ ", isIdle: " + isIdle
+ ", mRestrictPower: " + mRestrictPower
+ ", mDeviceIdleMode: " + mDeviceIdleMode
+ ", isForeground=" + isForeground
+ ", isWhitelisted=" + isWhitelisted
+ ", oldRule=" + uidRulesToString(oldRule)
+ ", newRule=" + uidRulesToString(newRule)
+ ", newUidRules=" + uidRulesToString(newUidRules)
+ ", oldUidRules=" + uidRulesToString(oldUidRules));
}
// Second step: notify listeners if state changed.
if (newRule != oldRule) {
if (newRule == RULE_NONE || hasRule(newRule, RULE_ALLOW_ALL)) {
if (LOGV) Log.v(TAG, "Allowing non-metered access for UID " + uid);
} else if (hasRule(newRule, RULE_REJECT_ALL)) {
if (LOGV) Log.v(TAG, "Rejecting non-metered access for UID " + uid);
} else {
// All scenarios should have been covered above
Log.wtf(TAG, "Unexpected change of non-metered UID state for " + uid
+ ": foreground=" + isForeground
+ ", whitelisted=" + isWhitelisted
+ ", newRule=" + uidRulesToString(newUidRules)
+ ", oldRule=" + uidRulesToString(oldUidRules));
}
mHandler.obtainMessage(MSG_RULES_CHANGED, uid, newUidRules).sendToTarget();
}
return newUidRules;
}isUidValidForBlacklistRulesWhen it uidis mediaor the drmtype is not needed, or the app that has been authorized for Internet access before, update is not allowed
// TODO: the MEDIA / DRM restriction might not be needed anymore, in which case both
// methods below could be merged into a isUidValidForRules() method.
private boolean isUidValidForBlacklistRules(int uid) {
// allow rules on specific system services, and any apps
if (uid == android.os.Process.MEDIA_UID || uid == android.os.Process.DRM_UID
|| (UserHandle.isApp(uid) && hasInternetPermissions(uid))) {
return true;
}
return false;
}- If it is a foreground process, it will allow access to the network even in restricted mode
- Other processes, non-whitelist will be set to deny access RULE_REJECT_ALL
if (isForeground) {
if (restrictMode) {
newRule = RULE_ALLOW_ALL;
}
} else if (restrictMode) {
newRule = isWhitelisted ? RULE_ALLOW_ALL : RULE_REJECT_ALL;
}For WindowManagerService, the role is to remove window animation effects.
@Override
public void onLowPowerModeChanged(PowerSaveState result) {
synchronized (mWindowMap) {
final boolean enabled = result.batterySaverEnabled;
if (mAnimationsDisabled != enabled && !mAllowAnimationsInLowPowerMode) {
mAnimationsDisabled = enabled;
dispatchNewAnimatorScaleLocked(null);
}
}
}Limit vibration VibratorService.java
Callback in VibratorService.java:
public void systemReady() {
Trace.traceBegin(Trace.TRACE_TAG_VIBRATOR, "VibratorService#systemReady");
try {
..........................
mPowerManagerInternal = LocalServices.getService(PowerManagerInternal.class);
mPowerManagerInternal.registerLowPowerModeObserver(
new PowerManagerInternal.LowPowerModeListener() {
@Override
public int getServiceType() {
return ServiceType.VIBRATION;
}
@Override
public void onLowPowerModeChanged(PowerSaveState result) {
updateVibrators();//更改低电量状态
}
});
..........................
} private void updateVibrators() {
synchronized (mLock) {
boolean devicesUpdated = updateInputDeviceVibratorsLocked();
boolean lowPowerModeUpdated = updateLowPowerModeLocked();//更改低电量状态
updateVibrationIntensityLocked();
if (devicesUpdated || lowPowerModeUpdated) {
// If the state changes out from under us then just reset.
doCancelVibrateLocked();
}
}
} private boolean updateLowPowerModeLocked() {
boolean lowPowerMode = mPowerManagerInternal
.getLowPowerState(ServiceType.VIBRATION).batterySaverEnabled;//看看这个值怎么拿到的
if (lowPowerMode != mLowPowerMode) {
mLowPowerMode = lowPowerMode;//mLowPowerMode这个变量判断要不要震动会用到
return true;
}
return false;
}frameworks\base\services\core\java\com\android\server\power\PowerManagerService.java :
@Override
public PowerSaveState getLowPowerState(@ServiceType int serviceType) {
return mBatterySaverPolicy.getBatterySaverPolicy(serviceType,
mBatterySaverController.isEnabled());//这个方法根据传入的serviceType 决定要不要对省电模式做出反应，很关键的方法
}frameworks\base\services\core\java\com\android\server\power\BatterySaverPolicy.java :
/**
* Get the {@link PowerSaveState} based on {@paramref type} and {@paramref realMode}.
* The result will have {@link PowerSaveState#batterySaverEnabled} and some other
* parameters when necessary.
*
* @param type type of the service, one of {@link ServiceType}
* @param realMode whether the battery saver is on by default
* @return State data that contains battery saver data
*/
public PowerSaveState getBatterySaverPolicy(@ServiceType int type, boolean realMode) {
synchronized (mLock) {
final PowerSaveState.Builder builder = new PowerSaveState.Builder()
.setGlobalBatterySaverEnabled(realMode);
if (!realMode) {
return builder.setBatterySaverEnabled(realMode)
.build();
}
switch (type) {
case ServiceType.GPS:
return builder.setBatterySaverEnabled(realMode)
.setGpsMode(mGpsMode)
.build();
case ServiceType.ANIMATION:
return builder.setBatterySaverEnabled(mAnimationDisabled)
.build();//mVibrationDisabledEffective决定省电模式下要不要取消动画
case ServiceType.FULL_BACKUP:
return builder.setBatterySaverEnabled(mFullBackupDeferred)
.build();
case ServiceType.KEYVALUE_BACKUP:
return builder.setBatterySaverEnabled(mKeyValueBackupDeferred)
.build();
case ServiceType.NETWORK_FIREWALL:
return builder.setBatterySaverEnabled(!mFireWallDisabled)
.build();
case ServiceType.SCREEN_BRIGHTNESS:
return builder.setBatterySaverEnabled(!mAdjustBrightnessDisabled)
.setBrightnessFactor(mAdjustBrightnessFactor)
.build();
case ServiceType.DATA_SAVER:
return builder.setBatterySaverEnabled(!mDataSaverDisabled)
.build();
case ServiceType.SOUND:
return builder.setBatterySaverEnabled(mSoundTriggerDisabled)
.build();
case ServiceType.VIBRATION:
return builder.setBatterySaverEnabled(mVibrationDisabledEffective)
.build();//mVibrationDisabledEffective决定省电模式下要不要禁止振动
case ServiceType.FORCE_ALL_APPS_STANDBY:
return builder.setBatterySaverEnabled(mForceAllAppsStandby)
.build();
case ServiceType.FORCE_BACKGROUND_CHECK:
return builder.setBatterySaverEnabled(mForceBackgroundCheck)
.build();
case ServiceType.OPTIONAL_SENSORS:
return builder.setBatterySaverEnabled(mOptionalSensorsDisabled)
.build();
case ServiceType.AOD:
return builder.setBatterySaverEnabled(mAodDisabled)
.build();
default:
return builder.setBatterySaverEnabled(realMode)
.build();
}
}
}The BatterySaverPolicy.java class is very important. All the default configurations of the power saving mode are initialized in this class. If you want to customize the behavior of the power saving mode, this class will be used.
The ultimate goal of the callback process is to modify the value of the mLowPowerMode variable according to the configuration. This value will be used when the vibration is called to determine whether or not to vibrate.
@GuardedBy("mLock")
private void startVibrationLocked(final Vibration vib) {
Trace.traceBegin(Trace.TRACE_TAG_VIBRATOR, "startVibrationLocked");
try {
//关于省电模式下是否允许振动在这个方法里判断
if (!isAllowedToVibrateLocked(vib)) {
return;
}
//
final int intensity = getCurrentIntensityLocked(vib);
if (intensity == Vibrator.VIBRATION_INTENSITY_OFF) {
return;
}
//如果是来电且响铃时振动开关未打开，则不振动
if (vib.isRingtone() && !shouldVibrateForRingtone()) {
if (DEBUG) {
Slog.e(TAG, "Vibrate ignored, not vibrating for ringtones");
}
return;
}
........................
} private boolean isAllowedToVibrateLocked(Vibration vib) {
//如果不在省电模式则允许振动,如果在省电模式，排除掉以下几种情况外都不允许震动
if (!mLowPowerMode) {
return true;
}
//省电模式对铃声振动不影响
if (vib.usageHint == AudioAttributes.USAGE_NOTIFICATION_RINGTONE) {
return true;
}
//省电模式对 闹钟，辅助功能和 VoIP通话，视频通话 的振动不影响
if (vib.usageHint == AudioAttributes.USAGE_ALARM ||
vib.usageHint == AudioAttributes.USAGE_ASSISTANCE_ACCESSIBILITY ||
vib.usageHint == AudioAttributes.USAGE_NOTIFICATION_COMMUNICATION_REQUEST) {
return true;
}
return false;
}2. Decrease screen brightness
frameworks\base\services\core\java\com\android\server\power\PowerManagerService.java :
/**
* Updates the display power state asynchronously.
* When the update is finished, mDisplayReady will be set to true. The display
* controller posts a message to tell us when the actual display power state
* has been updated so we come back here to double-check and finish up.
*
* This function recalculates the display power state each time.
*
* @return True if the display became ready.
*/
private boolean updateDisplayPowerStateLocked(int dirty) {
.......................
updatePowerRequestFromBatterySaverPolicy(mDisplayPowerRequest);
..........................
mDisplayReady = mDisplayManagerInternal.requestPowerState(mDisplayPowerRequest,
mRequestWaitForNegativeProximity);
..........................
} @VisibleForTesting
void updatePowerRequestFromBatterySaverPolicy(DisplayPowerRequest displayPowerRequest) {
PowerSaveState state = mBatterySaverPolicy.
getBatterySaverPolicy(ServiceType.SCREEN_BRIGHTNESS,
mBatterySaverController.isEnabled());
displayPowerRequest.lowPowerMode = state.batterySaverEnabled;
displayPowerRequest.screenLowPowerBrightnessFactor = state.brightnessFactor;
}frameworks\base\services\core\java\com\android\server\display\DisplayManagerService.java :
public boolean requestPowerState(DisplayPowerRequest request,
boolean waitForNegativeProximity) {
synchronized (mSyncRoot) {
return mDisplayPowerController.requestPowerState(request,
waitForNegativeProximity);
}
}frameworks\base\services\core\java\com\android\server\display\DisplayPowerController.java
public boolean requestPowerState(DisplayPowerRequest request,
boolean waitForNegativeProximity) {
................................
if (changed && !mPendingRequestChangedLocked) {
mPendingRequestChangedLocked = true;
sendUpdatePowerStateLocked();
}
.................................
}
}sendUpdatePowerStateLocked is handled internally by the Handler message, and eventually the updatePowerState method will be called:
private void updatePowerState() {
............................
// If low power mode is enabled, scale brightness by screenLowPowerBrightnessFactor
// as long as it is above the minimum threshold.
if (mPowerRequest.lowPowerMode) {
if (brightness > mScreenBrightnessRangeMinimum) {
final float brightnessFactor =
Math.min(mPowerRequest.screenLowPowerBrightnessFactor, 1);// 亮度缩放比例
final int lowPowerBrightness = (int) (brightness * brightnessFactor);
brightness = Math.max(lowPowerBrightness, mScreenBrightnessRangeMinimum);
}
}
............................
}The default brightness scaling defined in BatterySaverPolicy.java is 0.5, and the brightness is reduced by half
mAdjustBrightnessDisabled = parser.getBoolean(KEY_ADJUST_BRIGHTNESS_DISABLED, true); //原生的配置是省电模式情况下默认不调节亮度
mAdjustBrightnessFactor = parser.getFloat(KEY_ADJUST_BRIGHTNESS_FACTOR, 0.5f);
3. WindowManagerService animation
frameworks\base\services\core\java\com\android\server\wm\WindowManagerService.java ：
mPowerManagerInternal.registerLowPowerModeObserver(
new PowerManagerInternal.LowPowerModeListener() {
@Override
public int getServiceType() {
return ServiceType.ANIMATION;
}
@Override
public void onLowPowerModeChanged(PowerSaveState result) {
synchronized (mWindowMap) {
//BatterySaverPolicy中配置的是否要在低电量中关闭动画，android P上是 false，默认不关闭动画，8.0上是true的
final boolean enabled = result.batterySaverEnabled;
//mAllowAnimationsInLowPowerMode代表是否在允许在低电模式下继续使用动画(默认是false，就是不允许)，如果在低电模式下会把WMS的动画都关闭
if (mAnimationsDisabled != enabled && !mAllowAnimationsInLowPowerMode) {
mAnimationsDisabled = enabled;
dispatchNewAnimatorScaleLocked(null);
}
}
}
});The animation is not turned off in low battery mode on 9.0, and it is turned off on 8.0.
4. NetworkPolicyManagerService.java Network firewall
frameworks\base\services\core\java\com\android\server\net\NetworkPolicyManagerService.java
private void updateRulesForRestrictPowerUL() {
Trace.traceBegin(Trace.TRACE_TAG_NETWORK, "updateRulesForRestrictPowerUL");
try {
updateRulesForDeviceIdleUL();
updateRulesForPowerSaveUL();
updateRulesForAllAppsUL(TYPE_RESTRICT_POWER);
} finally {
Trace.traceEnd(Trace.TRACE_TAG_NETWORK);
}
}In the low battery mode, the main purpose is to update the rules of network access. I did not study it carefully and dare not say anything. There is no limit on Android P by default, and the low battery mode does not restrict the network.
5. Restrictions on GPS location information
private void updateLocationState(BatterySaverController caller) {
final boolean kill =
(caller.getBatterySaverPolicy().getGpsMode()
== PowerManager.LOCATION_MODE_ALL_DISABLED_WHEN_SCREEN_OFF) &&
caller.isEnabled() && !caller.isInteractive();
if (DEBUG) {
Slog.d(TAG, "Battery saver " + (kill ? "stopping" : "restoring") + " location.");
}
Settings.Global.putInt(mContext.getContentResolver(),
Global.LOCATION_GLOBAL_KILL_SWITCH, kill ? 1 : 0);
} /**
* If set to 1, {@link Secure#LOCATION_MODE} will be set to {@link Secure#LOCATION_MODE_OFF}
* temporarily for all users.
*
* @hide
*/
@TestApi
public static final String LOCATION_GLOBAL_KILL_SWITCH =
"location_global_kill_switch";When the battery is low, the GPS will be turned off after the screen is off, temporarily restricting all apps from accessing location information.
All of the above are automatically called back in BatterySaverController.java after the low battery mode is turned on. The following is the processing of each module after listening to the ACTION_POWER_SAVE_MODE_CHANGED broadcast.
6. Voice interaction function
frameworks\base\services\voiceinteraction\java\com\android\server\soundtrigger\SoundTriggerHelper.java ：
// A single routine that implements the start recognition logic for both generic and keyphrase
// models.
private int startRecognitionLocked(ModelData modelData, boolean notify) {
...........................
if (!isRecognitionAllowed()) {
// Nothing to do here.
Slog.w(TAG, "startRecognition requested but not allowed.");
MetricsLogger.count(mContext, "sth_start_recognition_not_allowed", 1);
return STATUS_OK;
}
} // Whether we are allowed to run any recognition at all. The conditions that let us run
// a recognition include: no active phone call or not being in a power save mode. Also,
// the native service should be enabled.
private boolean isRecognitionAllowed() {
return !mCallActive && !mServiceDisabled && !mIsPowerSaveMode;
}Voice is not recognized in low battery mode
Other upper-level modules, such as settings, systemUI also monitor the ACTION_POWER_SAVE_MODE_CHANGED broadcast, mainly to make some UI changes