Android6.0 按键流程（三）InputDispatcher分发输入消息

上一篇博客分析了InputReader中扫描码与键盘码的转化，今天我们再来分析下InputDispatcher

 

一、InputDispatcher的notifyKey函数

接上一篇我们我们分析到InputDispatcher的notifyKey函数：

void InputDispatcher::notifyKey(const NotifyKeyArgs* args) {
    if (!validateKeyEvent(args->action)) {
        return;
    }

    uint32_t policyFlags = args->policyFlags;
    int32_t flags = args->flags;
    int32_t metaState = args->metaState;
    if ((policyFlags & POLICY_FLAG_VIRTUAL) || (flags & AKEY_EVENT_FLAG_VIRTUAL_HARD_KEY)) {
        policyFlags |= POLICY_FLAG_VIRTUAL;
        flags |= AKEY_EVENT_FLAG_VIRTUAL_HARD_KEY;
    }
    if (policyFlags & POLICY_FLAG_FUNCTION) {
        metaState |= AMETA_FUNCTION_ON;
    }

    policyFlags |= POLICY_FLAG_TRUSTED;

    int32_t keyCode = args->keyCode;
    if (metaState & AMETA_META_ON && args->action == AKEY_EVENT_ACTION_DOWN) {
        int32_t newKeyCode = AKEYCODE_UNKNOWN;
        if (keyCode == AKEYCODE_DEL) {
            newKeyCode = AKEYCODE_BACK;
        } else if (keyCode == AKEYCODE_ENTER) {
            newKeyCode = AKEYCODE_HOME;
        }
        if (newKeyCode != AKEYCODE_UNKNOWN) {
            AutoMutex _l(mLock);
            struct KeyReplacement replacement = {keyCode, args->deviceId};
            mReplacedKeys.add(replacement, newKeyCode);
            keyCode = newKeyCode;
            metaState &= ~AMETA_META_ON;
        }
    } else if (args->action == AKEY_EVENT_ACTION_UP) {
        // In order to maintain a consistent stream of up and down events, check to see if the key
        // going up is one we've replaced in a down event and haven't yet replaced in an up event,
        // even if the modifier was released between the down and the up events.
        AutoMutex _l(mLock);
        struct KeyReplacement replacement = {keyCode, args->deviceId};
        ssize_t index = mReplacedKeys.indexOfKey(replacement);
        if (index >= 0) {
            keyCode = mReplacedKeys.valueAt(index);
            mReplacedKeys.removeItemsAt(index);
            metaState &= ~AMETA_META_ON;
        }
    }

    KeyEvent event;
    event.initialize(args->deviceId, args->source, args->action,
            flags, keyCode, args->scanCode, metaState, 0,
            args->downTime, args->eventTime);

    mPolicy->interceptKeyBeforeQueueing(&event, /*byref*/ policyFlags);//这个函数是调用了java的PhoneWindowManager

    bool needWake;
    { // acquire lock
        mLock.lock();

        if (shouldSendKeyToInputFilterLocked(args)) {
            mLock.unlock();

            policyFlags |= POLICY_FLAG_FILTERED;
            if (!mPolicy->filterInputEvent(&event, policyFlags)) {
                return; // event was consumed by the filter
            }

            mLock.lock();
        }

        int32_t repeatCount = 0;
        KeyEntry* newEntry = new KeyEntry(args->eventTime,
                args->deviceId, args->source, policyFlags,
                args->action, flags, keyCode, args->scanCode,
                metaState, repeatCount, args->downTime);

        needWake = enqueueInboundEventLocked(newEntry);//将KeyEntry放入到队列中
        mLock.unlock();
    } // release lock

    if (needWake) {
        mLooper->wake();//唤醒进程
    }
}

我们先来看看mPolicy是构造函数中传进来的，那么我们就要去看InputManager中

InputDispatcher::InputDispatcher(const sp& policy) :
    mPolicy(policy),

InputManager的构造函数，还是在InputManager中传入的，那么我们就要跟到NativeInputManager了。

 

InputManager::InputManager(
        const sp& eventHub,
        const sp& readerPolicy,
        const sp& dispatcherPolicy) {
    mDispatcher = new InputDispatcher(dispatcherPolicy);
    mReader = new InputReader(eventHub, readerPolicy, mDispatcher);

NativeInputManager是把自己传进来了，

 

 

NativeInputManager::NativeInputManager(jobject contextObj,
        jobject serviceObj, const sp& looper) :
        mLooper(looper), mInteractive(true) {
    JNIEnv* env = jniEnv();

    mContextObj = env->NewGlobalRef(contextObj);
    mServiceObj = env->NewGlobalRef(serviceObj);

    {
        AutoMutex _l(mLock);
        mLocked.systemUiVisibility = ASYSTEM_UI_VISIBILITY_STATUS_BAR_VISIBLE;
        mLocked.pointerSpeed = 0;
        mLocked.pointerGesturesEnabled = true;
        mLocked.showTouches = false;
    }
    mInteractive = true;

    sp eventHub = new EventHub();
    mInputManager = new InputManager(eventHub, this, this);

因此在InputDispatcher中调用interceptKeyBeforeQueueing，是调用了NativeInputManager的interceptKeyBeforeQueueing函数

void NativeInputManager::interceptKeyBeforeQueueing(const KeyEvent* keyEvent,
        uint32_t& policyFlags) {
    // Policy:
    // - Ignore untrusted events and pass them along.
    // - Ask the window manager what to do with normal events and trusted injected events.
    // - For normal events wake and brighten the screen if currently off or dim.
    bool interactive = mInteractive.load();
    if (interactive) {
        policyFlags |= POLICY_FLAG_INTERACTIVE;
    }
    if ((policyFlags & POLICY_FLAG_TRUSTED)) {
        nsecs_t when = keyEvent->getEventTime();
        JNIEnv* env = jniEnv();
        jobject keyEventObj = android_view_KeyEvent_fromNative(env, keyEvent);
        jint wmActions;
        if (keyEventObj) {
            wmActions = env->CallIntMethod(mServiceObj,//反调用PhoneWindowManager
                    gServiceClassInfo.interceptKeyBeforeQueueing,
                    keyEventObj, policyFlags);
            if (checkAndClearExceptionFromCallback(env, "interceptKeyBeforeQueueing")) {
                wmActions = 0;
            }
            android_view_KeyEvent_recycle(env, keyEventObj);
            env->DeleteLocalRef(keyEventObj);
        } else {
            ALOGE("Failed to obtain key event object for interceptKeyBeforeQueueing.");
            wmActions = 0;
        }

        handleInterceptActions(wmActions, when, /*byref*/ policyFlags);
    } else {
        if (interactive) {
            policyFlags |= POLICY_FLAG_PASS_TO_USER;
        }
    }
}

在这个函数中会反调到PhoneWindowManager中的interceptKeyBeforeQueueing函数，在上层的result返回result &= ~ACTION_PASS_TO_USER就不会发送到应用进程了。

返回结果保存在wmActions中，然后调用了handleInterceptActions函数：

 

void NativeInputManager::handleInterceptActions(jint wmActions, nsecs_t when,
        uint32_t& policyFlags) {
    if (wmActions & WM_ACTION_PASS_TO_USER) {
        policyFlags |= POLICY_FLAG_PASS_TO_USER;
    } else {
    }
}

如果PhoneWindowManager返回的是result &= ~ACTION_PASS_TO_USER，policyFlags |= POLICY_FLAG_PASS_TO_USER就没有了。

继续分析InputDispatcher::notifyKey函数，调用完interceptKeyBeforeQueueing，然后 新建了一个KeyEntry对象后，调用enqueueInboundEventLocked函数。

 

 

 

bool InputDispatcher::enqueueInboundEventLocked(EventEntry* entry) {
    bool needWake = mInboundQueue.isEmpty();
    mInboundQueue.enqueueAtTail(entry);//放入队列尾
    traceInboundQueueLengthLocked();

    switch (entry->type) {
    case EventEntry::TYPE_KEY: {//各个不同类型
        // Optimize app switch latency.
        // If the application takes too long to catch up then we drop all events preceding
        // the app switch key.
        KeyEntry* keyEntry = static_cast(entry);
        if (isAppSwitchKeyEventLocked(keyEntry)) {
            if (keyEntry->action == AKEY_EVENT_ACTION_DOWN) {
                mAppSwitchSawKeyDown = true;
            } else if (keyEntry->action == AKEY_EVENT_ACTION_UP) {
                if (mAppSwitchSawKeyDown) {
#if DEBUG_APP_SWITCH
                    ALOGD("App switch is pending!");
#endif
                    mAppSwitchDueTime = keyEntry->eventTime + APP_SWITCH_TIMEOUT;
                    mAppSwitchSawKeyDown = false;
                    needWake = true;
                }
            }
        }
        break;
    }

继续分析InputDispatcher::notifyKey函数，最后会调用mLooper的wake函数唤醒线程，这个我们就不详细分析了。之前分析过。

 

 

 

二、InputDispatcher分发

notifyKey我们分析完了，接下来我们分析之前的InputDispatcherThread，线程不断的循环调用了InputDispatcher的dispatchOnce函数，下面我们来看下：

 

void InputDispatcher::dispatchOnce() {
    nsecs_t nextWakeupTime = LONG_LONG_MAX;
    { // acquire lock
        AutoMutex _l(mLock);
        mDispatcherIsAliveCondition.broadcast();

        // Run a dispatch loop if there are no pending commands.
        // The dispatch loop might enqueue commands to run afterwards.
        if (!haveCommandsLocked()) {
            dispatchOnceInnerLocked(&nextWakeupTime);//分发消息
        }

        // Run all pending commands if there are any.
        // If any commands were run then force the next poll to wake up immediately.
        if (runCommandsLockedInterruptible()) {
            nextWakeupTime = LONG_LONG_MIN;
        }
    } // release lock

    // Wait for callback or timeout or wake.  (make sure we round up, not down)
    nsecs_t currentTime = now();
    int timeoutMillis = toMillisecondTimeoutDelay(currentTime, nextWakeupTime);
    mLooper->pollOnce(timeoutMillis);//进入epoll
}

 

 

继续分析dispatchOnceInnerLocked函数

void InputDispatcher::dispatchOnceInnerLocked(nsecs_t* nextWakeupTime) {
    ........

    switch (mPendingEvent->type) {//根据类型不同
    case EventEntry::TYPE_CONFIGURATION_CHANGED: {
        ConfigurationChangedEntry* typedEntry =
                static_cast(mPendingEvent);
        done = dispatchConfigurationChangedLocked(currentTime, typedEntry);
        dropReason = DROP_REASON_NOT_DROPPED; // configuration changes are never dropped
        break;
    }

    case EventEntry::TYPE_DEVICE_RESET: {
        DeviceResetEntry* typedEntry =
                static_cast(mPendingEvent);
        done = dispatchDeviceResetLocked(currentTime, typedEntry);
        dropReason = DROP_REASON_NOT_DROPPED; // device resets are never dropped
        break;
    }

    case EventEntry::TYPE_KEY: {
        KeyEntry* typedEntry = static_cast(mPendingEvent);
        if (isAppSwitchDue) {
            if (isAppSwitchKeyEventLocked(typedEntry)) {
                resetPendingAppSwitchLocked(true);
                isAppSwitchDue = false;
            } else if (dropReason == DROP_REASON_NOT_DROPPED) {
                dropReason = DROP_REASON_APP_SWITCH;
            }
        }
        if (dropReason == DROP_REASON_NOT_DROPPED
                && isStaleEventLocked(currentTime, typedEntry)) {
            dropReason = DROP_REASON_STALE;
        }
        if (dropReason == DROP_REASON_NOT_DROPPED && mNextUnblockedEvent) {
            dropReason = DROP_REASON_BLOCKED;
        }
        done = dispatchKeyLocked(currentTime, typedEntry, &dropReason, nextWakeupTime);
        break;
    }

    case EventEntry::TYPE_MOTION: {
        MotionEntry* typedEntry = static_cast(mPendingEvent);
        if (dropReason == DROP_REASON_NOT_DROPPED && isAppSwitchDue) {
            dropReason = DROP_REASON_APP_SWITCH;
        }
        if (dropReason == DROP_REASON_NOT_DROPPED
                && isStaleEventLocked(currentTime, typedEntry)) {
            dropReason = DROP_REASON_STALE;
        }
        if (dropReason == DROP_REASON_NOT_DROPPED && mNextUnblockedEvent) {
            dropReason = DROP_REASON_BLOCKED;
        }
        done = dispatchMotionLocked(currentTime, typedEntry,
                &dropReason, nextWakeupTime);
        break;
    }

    default:
        ALOG_ASSERT(false);
        break;
    }

    if (done) {
        if (dropReason != DROP_REASON_NOT_DROPPED) {
            dropInboundEventLocked(mPendingEvent, dropReason);
        }
        mLastDropReason = dropReason;

        releasePendingEventLocked();
        *nextWakeupTime = LONG_LONG_MIN;  // force next poll to wake up immediately
    }
}

这个函数中，最后会根据类型不同调用不同的方法，我们是TYPE_KEY，调用了dispatchKeyLocked方法，一路跟下去有很多函数，我们就直接到最后的函数startDispatchCycleLocked函数：

 

void InputDispatcher::startDispatchCycleLocked(nsecs_t currentTime,
        const sp& connection) {

    while (connection->status == Connection::STATUS_NORMAL
            && !connection->outboundQueue.isEmpty()) {
        DispatchEntry* dispatchEntry = connection->outboundQueue.head;
        dispatchEntry->deliveryTime = currentTime;

        // Publish the event.
        status_t status;
        EventEntry* eventEntry = dispatchEntry->eventEntry;
        switch (eventEntry->type) {
        case EventEntry::TYPE_KEY: {
            KeyEntry* keyEntry = static_cast(eventEntry);

            // Publish the key event.
            status = connection->inputPublisher.publishKeyEvent(dispatchEntry->seq,
                    keyEntry->deviceId, keyEntry->source,
                    dispatchEntry->resolvedAction, dispatchEntry->resolvedFlags,
                    keyEntry->keyCode, keyEntry->scanCode,
                    keyEntry->metaState, keyEntry->repeatCount, keyEntry->downTime,
                    keyEntry->eventTime);
            break;
        }

这个函数会根据Event类型来分别处理，最后调用了connection对象的inputPublisher的publishKeyEvent函数。
 

 

 

下篇博客我们来继续分析下connection这个对象从何而来？