android wakelock

1.android休眠控制锁

  powermanager.acquir(); 获取控制锁

 powermanager.release(); 释放控制锁

2.在powerManagerService中，有检测当前framework层中的wakelock锁的，并判断当前锁的状态。

 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);
            }
            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) {
                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));
            }
        }
        // mWakeLockSummary = 0;
    }

系统会根据mWakeLockSummary 变量的值来判定当前的状态。

android o wake lock包括的类型如下：

    /**
     * Wake lock level: Ensures that the CPU is running; the screen and keyboard
     * backlight will be allowed to go off.
     */
    public static final int PARTIAL_WAKE_LOCK = 0x00000001;

    /**
     * Wake lock level: Ensures that the screen is on (but may be dimmed);
     * the keyboard backlight will be allowed to go off.
     * <p>
     * If the user presses the power button, then the {@link #SCREEN_DIM_WAKE_LOCK} will be
     * implicitly released by the system, causing both the screen and the CPU to be turned off.
     * Contrast with {@link #PARTIAL_WAKE_LOCK}.
     * </p>
     */
    @Deprecated
    public static final int SCREEN_DIM_WAKE_LOCK = 0x00000006;

    /**
     * Wake lock level: Ensures that the screen is on at full brightness;
     * the keyboard backlight will be allowed to go off.
     * <p>
     * If the user presses the power button, then the {@link #SCREEN_BRIGHT_WAKE_LOCK} will be
     * implicitly released by the system, causing both the screen and the CPU to be turned off.
     * Contrast with {@link #PARTIAL_WAKE_LOCK}.
     * </p>
     */
    @Deprecated
    public static final int SCREEN_BRIGHT_WAKE_LOCK = 0x0000000a;

    /**
     * Wake lock level: Ensures that the screen and keyboard backlight are on at
     * full brightness.
     * <p>
     * If the user presses the power button, then the {@link #FULL_WAKE_LOCK} will be
     * implicitly released by the system, causing both the screen and the CPU to be turned off.
     * Contrast with {@link #PARTIAL_WAKE_LOCK}.
     * </p>
     */
    @Deprecated
    public static final int FULL_WAKE_LOCK = 0x0000001a;

    /**
     * Wake lock level: Turns the screen off when the proximity sensor activates.
     * <p>
     * If the proximity sensor detects that an object is nearby, the screen turns off
     * immediately.  Shortly after the object moves away, the screen turns on again.
     * </p><p>
     * A proximity wake lock does not prevent the device from falling asleep
     * unlike {@link #FULL_WAKE_LOCK}, {@link #SCREEN_BRIGHT_WAKE_LOCK} and
     * {@link #SCREEN_DIM_WAKE_LOCK}.  If there is no user activity and no other
     * wake locks are held, then the device will fall asleep (and lock) as usual.
     * However, the device will not fall asleep while the screen has been turned off
     * by the proximity sensor because it effectively counts as ongoing user activity.
     * </p><p>
     * Since not all devices have proximity sensors, use {@link #isWakeLockLevelSupported}
     * to determine whether this wake lock level is supported.
     * </p><p>
     * Cannot be used with {@link #ACQUIRE_CAUSES_WAKEUP}.
     * </p>
     */
    public static final int PROXIMITY_SCREEN_OFF_WAKE_LOCK = 0x00000020;

    /**
     * Wake lock level: Put the screen in a low power state and allow the CPU to suspend
     * if no other wake locks are held.
     * <p>
     * This is used by the dream manager to implement doze mode.  It currently
     * has no effect unless the power manager is in the dozing state.
     * </p>
     * {@hide}
     */
    public static final int DOZE_WAKE_LOCK = 0x00000040;

    /**
     * Wake lock level: Keep the device awake enough to allow drawing to occur.
     * <p>
     * This is used by the window manager to allow applications to draw while the
     * system is dozing.  It currently has no effect unless the power manager is in
     * the dozing state.
     * </p>
     * {@hide}
     */
    public static final int DRAW_WAKE_LOCK = 0x00000080;

    /**
     * Mask for the wake lock level component of a combined wake lock level and flags integer.
     *
     * @hide
     */
    public static final int WAKE_LOCK_LEVEL_MASK = 0x0000ffff;

    /**
     * Wake lock flag: Turn the screen on when the wake lock is acquired.
     * <p>
     * Normally wake locks don't actually wake the device, they just cause
     * the screen to remain on once it's already on.  Think of the video player
     * application as the normal behavior.  Notifications that pop up and want
     * the device to be on are the exception; use this flag to be like them.
     * </p>
     */
    public static final int ACQUIRE_CAUSES_WAKEUP = 0x10000000;

    /**
     * Wake lock flag: When this wake lock is released, poke the user activity timer
     * so the screen stays on for a little longer.
     * <p>
     * Will not turn the screen on if it is not already on.
     * See {@link #ACQUIRE_CAUSES_WAKEUP} if you want that.
     * </p>
     */
    public static final int ON_AFTER_RELEASE = 0x20000000;

    /**
     * Wake lock flag: This wake lock is not important for logging events.  If a later
     * wake lock is acquired that is important, it will be considered the one to log.
     * @hide
     */
    public static final int UNIMPORTANT_FOR_LOGGING = 0x40000000;

在updateSuspendBlockerLocked函数中，首先会判断mWakeLockSummary的状态，确定系统是否要进入autosuspend模式。

在调用 setHalAutoSuspendModeLocked(true);

// Summarizes the state of all active wakelocks.
    private static final int WAKE_LOCK_CPU = 1 << 0;
    private static final int WAKE_LOCK_SCREEN_BRIGHT = 1 << 1;
    private static final int WAKE_LOCK_SCREEN_DIM = 1 << 2;
    private static final int WAKE_LOCK_BUTTON_BRIGHT = 1 << 3;
    private static final int WAKE_LOCK_PROXIMITY_SCREEN_OFF = 1 << 4;
    private static final int WAKE_LOCK_STAY_AWAKE = 1 << 5; // only set if already awake
    private static final int WAKE_LOCK_DOZE = 1 << 6;
    private static final int WAKE_LOCK_DRAW = 1 << 7;

/**
     * Updates the suspend blocker that keeps the CPU alive.
     *
     * This function must have no other side-effects.
     */
    private void updateSuspendBlockerLocked() {
        final boolean needWakeLockSuspendBlocker = ((mWakeLockSummary & WAKE_LOCK_CPU) != 0);
        final boolean needDisplaySuspendBlocker = needDisplaySuspendBlockerLocked();
        final boolean autoSuspend = !needDisplaySuspendBlocker;
        final boolean interactive = mDisplayPowerRequest.isBrightOrDim();
        Slog.d(TAG, "####3updateSuspendBlockerLocked:"+ autoSuspend+ " ,"+mDecoupleHalAutoSuspendModeFromDisplayConfig);
        // Disable auto-suspend if needed.
        // FIXME We should consider just leaving auto-suspend enabled forever since
        // we already hold the necessary wakelocks.
        if (!autoSuspend && mDecoupleHalAutoSuspendModeFromDisplayConfig) {
            setHalAutoSuspendModeLocked(false);
        }
        ...
        ...

         // mWakeLockSuspendBlocker.release();
        // mHoldingWakeLockSuspendBlocker = false;
        // Enable auto-suspend if needed.
        if (autoSuspend && mDecoupleHalAutoSuspendModeFromDisplayConfig) {
            setHalAutoSuspendModeLocked(true);
        }
}

3.android 自动超时休眠

在函数updateUserActivitySummaryLocked中，

 nextTimeout = mLastUserActivityTime+ screenOffTimeout - screenDimDuration;

nextTimeout 是屏幕自动黑屏的超时时间，当从系统开机的相对时间到了的时候，调用 sendMessageAtTime函数发送消息，

 if (mUserActivitySummary != 0 && nextTimeout >= 0) {
                    Message msg = mHandler.obtainMessage(MSG_USER_ACTIVITY_TIMEOUT);
                    msg.setAsynchronous(true);
                    mHandler.sendMessageAtTime(msg, nextTimeout);
                    Slog.d(TAG,"###send MSG_USER_ACTIVITY_TIMEOUT message\n");
                }

  /**
     * 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();
                int screenOffTimeout = getScreenOffTimeoutLocked(sleepTimeout);
                final int screenDimDuration = getScreenDimDurationLocked(screenOffTimeout);
                final boolean userInactiveOverride = mUserInactiveOverrideFromWindowManager;
                Slog.d(TAG,"now:"+ TimeUtils.formatUptime(now) +" sleepTimeout:"+ TimeUtils.formatUptime(sleepTimeout) + "screenOffTimeout:"+ TimeUtils.formatUptime(screenOffTimeout) + 
                    "screenDimDuration:"+ TimeUtils.formatUptime(screenDimDuration) +"mLastWakeTime:"+ TimeUtils.formatUptime(mLastWakeTime));
                mUserActivitySummary = 0;
                if (mLastUserActivityTime >= mLastWakeTime) {
                    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
                                || mDisplayPowerRequest.policy == DisplayPowerRequest.POLICY_VR) {
                            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;
                    }
                }

                if (mUserActivitySummary != USER_ACTIVITY_SCREEN_DREAM && userInactiveOverride) {
                    if ((mUserActivitySummary &
                            (USER_ACTIVITY_SCREEN_BRIGHT | USER_ACTIVITY_SCREEN_DIM)) != 0) {
                        // Device is being kept awake by recent user activity
                        if (nextTimeout >= now && mOverriddenTimeout == -1) {
                            // Save when the next timeout would have occurred
                            mOverriddenTimeout = nextTimeout;
                        }
                    }
                    mUserActivitySummary = USER_ACTIVITY_SCREEN_DREAM;
                    nextTimeout = -1;
                }

                if (mUserActivitySummary != 0 && nextTimeout >= 0) {
                    Message msg = mHandler.obtainMessage(MSG_USER_ACTIVITY_TIMEOUT);
                    msg.setAsynchronous(true);
                    mHandler.sendMessageAtTime(msg, nextTimeout);
                    Slog.d(TAG,"###send MSG_USER_ACTIVITY_TIMEOUT message\n");
                }
            } else {
                mUserActivitySummary = 0;
            }

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

  当收到消息后，调用函数handleUserActivityTimeout，接着再调用updatePowerStateLocked函数。

 /**
     * Called when a user activity timeout has occurred.
     * Simply indicates that something about user activity has changed so that the new
     * state can be recomputed when the power state is updated.
     *
     * This function must have no other side-effects besides setting the dirty
     * bit and calling update power state.  Wakefulness transitions are handled elsewhere.
     */
    private void handleUserActivityTimeout() { // runs on handler thread
        synchronized (mLock) {
            if (DEBUG_SPEW) {
                Slog.d(TAG, "handleUserActivityTimeout");
            }
            Slog.d(TAG, "####handleUserActivityTimeout");
            mDirty |= DIRTY_USER_ACTIVITY;
            updatePowerStateLocked();
        }
    }

在updatePowerStateLocked()中，当检测到mDirty = DIRTY_USER_ACTIVITY时，在函数updateWakefulnessLocked()中会执行

goToSleepNoUpdateLocked(),r接着调用 setWakefulnessLocked(WAKEFULNESS_DOZING, reason);设置mWakefulness=WAKEFULNESS_DOZING；

/**
     * 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;
        }
        Slog.d(TAG, "###updatePowerStateLocked\n");
        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;
                Slog.d(TAG,"dirtyPhase1:"+ dirtyPhase1 + " dirtyPhase2:"+ dirtyPhase2);
                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);
        }
    }

 private boolean goToSleepNoUpdateLocked(long eventTime, int reason, int flags, int uid) {
    .....
try {
            switch (reason) {
                case PowerManager.GO_TO_SLEEP_REASON_DEVICE_ADMIN:
                    Slog.i(TAG, "Going to sleep due to device administration policy "
                            + "(uid " + uid +")...");
                    break;
                case PowerManager.GO_TO_SLEEP_REASON_TIMEOUT:
                    Slog.i(TAG, "Going to sleep due to screen timeout (uid " + uid +")...");
                    break;
                case PowerManager.GO_TO_SLEEP_REASON_LID_SWITCH:
                    Slog.i(TAG, "Going to sleep due to lid switch (uid " + uid +")...");
                    break;
                case PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON:
                    Slog.i(TAG, "Going to sleep due to power button (uid " + uid +")...");
                    break;
                case PowerManager.GO_TO_SLEEP_REASON_SLEEP_BUTTON:
                    Slog.i(TAG, "Going to sleep due to sleep button (uid " + uid +")...");
                    break;
                case PowerManager.GO_TO_SLEEP_REASON_HDMI:
                    Slog.i(TAG, "Going to sleep due to HDMI standby (uid " + uid +")...");
                    break;
                default:
                    Slog.i(TAG, "Going to sleep by application request (uid " + uid +")...");
                    reason = PowerManager.GO_TO_SLEEP_REASON_APPLICATION;
                    break;
            }

            mLastSleepTime = eventTime;
            mSandmanSummoned = true;
            setWakefulnessLocked(WAKEFULNESS_DOZING, reason);

.....
}

在 updatePowerStateLocked中的updateDreamLocked函数，通过发送消息MSG_SANDMAN,执行reallyGoToSleepNoUpdateLocked(),

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

/**
     * Determines whether to post a message to the sandman to update the dream state.
     */
    private void updateDreamLocked(int dirty, boolean displayBecameReady) {
        if ((dirty & (DIRTY_WAKEFULNESS
                | DIRTY_USER_ACTIVITY
                | DIRTY_WAKE_LOCKS
                | DIRTY_BOOT_COMPLETED
                | DIRTY_BOOT_IPO
                | DIRTY_SETTINGS
                | DIRTY_IS_POWERED
                | DIRTY_STAY_ON
                | DIRTY_PROXIMITY_POSITIVE
                | DIRTY_BATTERY_STATE)) != 0 || displayBecameReady) {
            if (mDisplayReady) {
                scheduleSandmanLocked();
            }
        }
    }

    private void scheduleSandmanLocked() {
        if (!mSandmanScheduled) {
            mSandmanScheduled = true;
            Message msg = mHandler.obtainMessage(MSG_SANDMAN);
            msg.setAsynchronous(true);
            mHandler.sendMessage(msg);
        }
    }


private void handleSandman() { 
.....
.....
  reallyGoToSleepNoUpdateLocked(SystemClock.uptimeMillis(), Process.SYSTEM_UID);
  updatePowerStateLocked();
....
}