设置按下电源立刻锁屏失败

bug描述

“General description:
It needs about 1s to lock screen when press power key again to awake phone after set “”Immediately”” in screen lock.

---

Reproducibility:
10/10

---

Precondition:
None.

---

Step:
1.Main menu->Settings->Security->Screen lock settings->Turn off Power button instantly locks->Press Automatically lock->Select “”Immediately”“->Press power key twice quickly->Check.
2.Press power key to enter sleep->About 1s->Press power key again->Check.

---

Actual result:
Step 1:It don’t lock screen when press power key twice quickly to awake phone after set “”Immediately”” in screen lock.
Step 2:It needs about 1s to lock screen when press power key again to awake phone after set “”Immediately”” in screen lock.

---

Expect result:
Phone should be locked immediately when press power key to enter sleep after set “”Immediately”” in screen lock.

---

Reference phone result:
Phone is locked immediately when press power key twice after set “”Immediately”” in security.

android可以设置，按下电源键后一段时间不锁屏，这样对于那些手机控来说是一件很好的事，不需要频繁的在keyguard中解锁。这个bug意思是说当设定按下电源后立刻锁屏，结果自己操作时却没有立刻锁屏，而是要等大约一秒钟后在按电源键，才属于锁屏状态。

找源头

通过前面的分析，知道这个bug是keyguard的模块，我们还需要进一步的定位。在android5.0后，将keyguard加入到了SystemUI模块中，关于怎么判断keyguard属于SystemUI可以参考这篇文字Android6.0锁屏简介。
show keyguard有两个触发点。
screen off
systemReady

我们发现会通过KeyguardViewMediator.java处理。实际上，详细的流程是这样的

 private void doKeyguardLaterLocked(long timeout) {        // Lock in the future        long when = SystemClock.elapsedRealtime() + timeout;        Intent intent = new Intent(DELAYED_KEYGUARD_ACTION);        intent.putExtra("seq", mDelayedShowingSequence);        intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);        PendingIntent sender = PendingIntent.getBroadcast(mContext,                0, intent, PendingIntent.FLAG_CANCEL_CURRENT);        mAlarmManager.setExactAndAllowWhileIdle(AlarmManager.ELAPSED_REALTIME_WAKEUP, when, sender);        if (DEBUG) Log.d(TAG, "setting alarm to turn off keyguard, seq = "                         + mDelayedShowingSequence);        doKeyguardLaterForChildProfilesLocked();    }

在doKeyguardLaterLocked方法中，会发送一个广播DELAYED_KEYGUARD_ACTION，广播的注册是在setupLocked() 中注册的

  mContext.registerReceiver(mBroadcastReceiver, new IntentFilter(DELAYED_KEYGUARD_ACTION));

在doKeyguardLaterLocked的参数timeout是从settings.app传过来了，也就是我们设定的按键后隔多长时间锁屏的时间。

public void onStartedGoingToSleep(int why) {..... long timeout = getLockTimeout(KeyguardUpdateMonitor.getCurrentUser());}

点进去一看，就知道通过在数据库里查询setting设定的时间

    private long getLockTimeout(int userId) {        // if the screen turned off because of timeout or the user hit the power button        // and we don't need to lock immediately, set an alarm        // to enable it a little bit later (i.e, give the user a chance        // to turn the screen back on within a certain window without        // having to unlock the screen)        final ContentResolver cr = mContext.getContentResolver();        // From SecuritySettings        final long lockAfterTimeout = Settings.Secure.getIntForUser(cr,                Settings.Secure.LOCK_SCREEN_LOCK_AFTER_TIMEOUT,                KEYGUARD_LOCK_AFTER_DELAY_DEFAULT, userId);        // From DevicePolicyAdmin        final long policyTimeout = mLockPatternUtils.getDevicePolicyManager()                .getMaximumTimeToLockForUserAndProfiles(userId);        long timeout;        if (policyTimeout <= 0) {            timeout = lockAfterTimeout;        } else {            // From DisplaySettings            long displayTimeout = Settings.System.getIntForUser(cr, SCREEN_OFF_TIMEOUT,                    KEYGUARD_DISPLAY_TIMEOUT_DELAY_DEFAULT, userId);            // policy in effect. Make sure we don't go beyond policy limit.            displayTimeout = Math.max(displayTimeout, 0); // ignore negative values            timeout = Math.min(policyTimeout - displayTimeout, lockAfterTimeout);            timeout = Math.max(timeout, 0);        }        return timeout;    }

接下来看看广播时如何处理的，找到广播接收者

    private final BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {        @Override        public void onReceive(Context context, Intent intent) {            String action = intent.getAction();            if (DELAYED_KEYGUARD_ACTION.equals(action)) {                final int sequence = intent.getIntExtra("seq", 0);                if (DEBUG) Log.d(TAG, "received DELAYED_KEYGUARD_ACTION with seq = "                        + sequence + ", mDelayedShowingSequence = " + mDelayedShowingSequence);                synchronized (KeyguardViewMediator.this) {                    if (mDelayedShowingSequence==sequence)  {                     mSuppressNextLockSound = true;                   doKeyguardLocked(null);                    }                }            }              /// @}        }    };

mDelayedShowingSequence==sequence这两个变量相互控制，最后如果相等的话，就开始调用doKeyguardLocked方法，就是说经过timeout时间的等待，就开始锁屏幕了。看看doKeyguardLocked方法

 /**     * Enable the keyguard if the settings are appropriate.     */    private void doKeyguardLocked(Bundle options) {        // if another app is disabling us, don't show        if (!mExternallyEnabled || PowerOffAlarmManager.isAlarmBoot()) {            if (DEBUG) {                Log.d(TAG, "doKeyguard: not showing because externally disabled");                Log.d(TAG, "doKeyguard : externally disabled reason.." +                           "mExternallyEnabled = " + mExternallyEnabled) ;                Log.d(TAG, "doKeyguard : externally disabled reason.." +                           "PowerOffAlarmManager.isAlarmBoot() = " +                           PowerOffAlarmManager.isAlarmBoot()) ;            }            // note: we *should* set mNeedToReshowWhenReenabled=true here, but that makes            // for an occasional ugly flicker in this situation:            // 1) receive a call with the screen on (no keyguard) or make a call            // 2) screen times out            // 3) user hits key to turn screen back on            // instead, we reenable the keyguard when we know the screen is off and the call            // ends (see the broadcast receiver below)            // TODO: clean this up when we have better support at the window manager level            // for apps that wish to be on top of the keyguard            return;        }        // if the keyguard is already showing, don't bother        if (mStatusBarKeyguardViewManager.isShowing()) {            if (DEBUG) Log.d(TAG, "doKeyguard: not showing because it is already showing");            resetStateLocked();            if (DEBUG) {                Log.d(TAG, "doKeyguard: not showing because it is already showing");            }            return;        }        // In split system user mode, we never unlock system user.        if (!UserManager.isSplitSystemUser()                || KeyguardUpdateMonitor.getCurrentUser() != UserHandle.USER_SYSTEM                || !mUpdateMonitor.isDeviceProvisioned()) {            // if the setup wizard hasn't run yet, don't show            if (DEBUG) {                Log.d(TAG, "doKeyguard: get keyguard.no_require_sim property before");            }            final boolean requireSim = !SystemProperties.getBoolean(                    "keyguard.no_require_sim", true);            if (DEBUG) {                Log.d(TAG, "doKeyguard: get requireSim=" + requireSim);            }            final boolean provisioned = mUpdateMonitor.isDeviceProvisioned();            boolean lockedOrMissing = false;            for (int i = 0; i < KeyguardUtils.getNumOfPhone(); i++) {                if (isSimLockedOrMissing(i, requireSim)) {                    lockedOrMissing = true;                    break;                }            }            /// M: Add new condition DM lock is not true            boolean antiTheftLocked = AntiTheftManager.isAntiTheftLocked();            Log.d(TAG, "lockedOrMissing is " + lockedOrMissing + ", requireSim=" + requireSim                    + ", provisioned=" + provisioned +                    ", antiTheftLocked=" + antiTheftLocked);            if (!lockedOrMissing && shouldWaitForProvisioning() && !antiTheftLocked) {                if (DEBUG) {                    Log.d(TAG, "doKeyguard: not showing because device isn't provisioned"                        + " and the sim is not locked or missing");                }                return;            }            if (mLockPatternUtils.isLockScreenDisabled(KeyguardUpdateMonitor.getCurrentUser())                    && !lockedOrMissing && !antiTheftLocked) {                if (DEBUG) Log.d(TAG, "doKeyguard: not showing because lockscreen is off");                return;            }            final boolean otpLock = mOneTimePassLock.launchIfLockActive();            if (mLockPatternUtils.checkVoldPassword(KeyguardUpdateMonitor.getCurrentUser())                    && KeyguardUtils.isSystemEncrypted() &&                    !KeyguardSecurity.bootReasonIsCrash() &&                    !otpLock) {                if (DEBUG) Log.d(TAG, "Not showing lock screen since just decrypted");                // Without this, settings is not enabled until the lock screen first appears                setShowingLocked(false);                hideLocked();                mUpdateMonitor.reportSuccessfulStrongAuthUnlockAttempt();                return;            }            if (otpLock) {                boolean relaunchOTP = false;                // Wait while property sys.boot_completed is set in order to ensure that                // OTPLockscreenActivity will start sucessfully                while (!SystemProperties.getBoolean("sys.boot_completed", false)) {                    relaunchOTP = true;                    try {                        // Give some time to get property set                        if (DEBUG) {                            Log.i(TAG, "Boot not finished, sleeping...");                        }                        Thread.sleep(KEYGUARD_WAIT_TIME_MS);                    } catch (InterruptedException ex) {                        if (DEBUG) {                            Log.d(TAG, "doKeyguard: Exception in sleep");                        }                    }                }                // Restart Activity if first attempt failed                if (relaunchOTP) {                    // Disable status bar expand                    if (mStatusBarManager == null) {                        mStatusBarManager = (StatusBarManager)                             mContext.getSystemService(Context.STATUS_BAR_SERVICE);                    }                    if (mStatusBarManager != null) {                        mStatusBarManager.disable(StatusBarManager.DISABLE_EXPAND);                    }                    mOneTimePassLock.launchIfLockActive();                }            }        }        if (DEBUG) Log.d(TAG, "doKeyguard: showing the lock screen");        showLocked(options);    }

有兴趣可以详细看看，以后的流程没必要追究了，和这个bug的关系不大。
找bug是一件很麻烦的事，如果对流程不清楚的话就更加麻烦，我通过给这个文件调用的doKeyguardLaterLocked方法的地方前打印日志，发现在我触发关掉屏幕动作时会执行 public void onStartedGoingToSleep(int why) {

  public void onStartedGoingToSleep(int why) {        synchronized (this) {        ......  if ((why == WindowManagerPolicy.OFF_BECAUSE_OF_TIMEOUT && timeout > 0)                    || (why == WindowManagerPolicy.OFF_BECAUSE_OF_USER && !lockImmediately)                    && !mIsIPOShutDown) {                    Log日志                doKeyguardLaterLocked(timeout);                mLockLater = true;            }           ......    }

会发现当我的timeout设为0if语句也会成立，也就会执行 doKeyguardLaterLocked(timeout);所以就出现了设置按下按键后立刻锁屏是没有效果的。这就是这个bug的原因。

解决方法

 public void onStartedGoingToSleep(int why) {        synchronized (this) {        ......  if ((why == WindowManagerPolicy.OFF_BECAUSE_OF_TIMEOUT && timeout > 0)                    || (why == WindowManagerPolicy.OFF_BECAUSE_OF_USER && !lockImmediately)                    && !mIsIPOShutDown) {                    Log日志              if(timeout>0){             doKeyguardLaterLocked(timeout);                mLockLater = true;                }else{                 doKeyguardLocked(null);                 }            }           ......    }