android ANR源码分析 --- 之三

4, inputDispatching Timeout

当input事件处理得慢就会触发ANR.

ANR时间区别便是指当前这次的事件dispatch过程中执行findFocusedWindowTargetsLocked()方法到下一次执行resetANRTimeoutsLocked()的时间区间.

在InputDispatcher.cpp的事件分发过程中, 如果是Key event事件,则会调用dispatchKeyLocked方法;

如果是Motion event事件,则会调用dispatchMotionLocked方法;

dispatchKeyLocked方法会调用findTouchedWindowTargetsLocked方法进行超时记录,如下,

int32_t injectionResult = findFocusedWindowTargetsLocked(currentTime,    entry, inputTargets, nextWakeupTime);

最后调用dispatchEventLocked继续处理事件。

dispatchEventLocked(currentTime, entry, inputTargets);

dispatchMotionLocked方法中会根据触摸事件是点触摸还是轨迹球事件分别进行超时记录,

if (isPointerEvent) {        // Pointer event.  (eg. touchscreen)        injectionResult = findTouchedWindowTargetsLocked(currentTime,                entry, inputTargets, nextWakeupTime, &conflictingPointerActions);} else {        // Non touch event.  (eg. trackball)        injectionResult = findFocusedWindowTargetsLocked(currentTime,                entry, inputTargets, nextWakeupTime);}

如果是点触摸则调用findTouchedWindowTargetsLocked方法进行处理;

如果是其他,例如轨迹球事件则调用findFocusedWindowTargetsLocked方法进行处理。

最后都调用dispatchEventLocked继续处理事件,

dispatchEventLocked(currentTime, entry, inputTargets);

最后无论是findTouchedWindowTargetsLocked还是findFocusedWindowTargetsLocked方法,都会调用handleTargetsNotReadyLocked方法。

injectionResult = handleTargetsNotReadyLocked(currentTime, entry,  mFocusedApplicationHandle, mFocusedWindowHandle, nextWakeupTime, reason.string());

4.1 handleTargetsNotReadyLocked

handleTargetsNotReadyLocked方法很关键,决定了是否调用onANRLocked方法,也就是ANR消息。

onANRLocked方法调用onANRLocked方法如下,

if (currentTime >= mInputTargetWaitTimeoutTime) {  onANRLocked(currentTime, applicationHandle, windowHandle,     entry->eventTime, mInputTargetWaitStartTime, reason);

逐步看onANRLocked方法执行的条件,

currentTime 就是系统的当前时间,这个没什么说的。主要是mInputTargetWaitTimeoutTime变量, mInputTargetWaitTimeoutTime 是一个全局变量,

1,如果applicationHandle和windowHandle 都为空,可能系统灭屏休眠了,这时候mInputTargetWaitTimeoutTime变量就设置一个比较大的值,

也就是说onANRLocked方法不会调用,

if (applicationHandle == NULL && windowHandle == NULL) {   if (mInputTargetWaitCause != INPUT_TARGET_WAIT_CAUSE_SYSTEM_NOT_READY) {   •••   mInputTargetWaitTimeoutTime = LONG_LONG_MAX;

2,如果不是上面的情况,并且apk已经完全启动,可以处理input事件,

else {if (mInputTargetWaitCause != INPUT_TARGET_WAIT_CAUSE_APPLICATION_NOT_READY) {    •••    nsecs_t timeout; //获取等待的时间值    if (windowHandle != NULL) {       timeout = windowHandle->getDispatchingTimeout(DEFAULT_INPUT_DISPATCHING_TIMEOUT);     } else if (applicationHandle != NULL) {        timeout = applicationHandle->getDispatchingTimeout(                        DEFAULT_INPUT_DISPATCHING_TIMEOUT);     } else {         timeout = DEFAULT_INPUT_DISPATCHING_TIMEOUT;     }••• mInputTargetWaitTimeoutTime = currentTime + timeout;// 为mInputTargetWaitTimeoutTime 赋值

Input事件ANR时间为5s,定义如下,

const nsecs_t DEFAULT_INPUT_DISPATCHING_TIMEOUT = 5000 * 1000000LL; // 5 sec

到下次执行resetANRTimeoutsLocked方法时,就会重置时间,因此onANRLocked方法也不会执行,

// Reset input target wait timeout.mInputTargetWaitCause = INPUT_TARGET_WAIT_CAUSE_NONE;mInputTargetWaitApplicationHandle.clear();

在InputDispatcher.cpp中,有以下方法可能会调用resetANRTimeoutsLocked方法,

resetAndDropEverythingLocked

releasePendingEventLocked

setFocusedApplication

dispatchOnceInnerLocked

setInputDispatchMode

因此, 以下4个场景,可能会调用resetANRTimeoutsLocked方法,

1,解冻屏幕, 系统开/关机的时刻点 (thawInputDispatchingLw, setEventDispatchingLw)

2,wms聚焦app的改变 (WMS.setFocusedApp, WMS.removeAppToken)

3,设置input filter的过程 (IMS.setInputFilter)

4,再次分发事件的过程(dispatchOnceInnerLocked)

以上都运行于input native进程中,接下来看看如何从input native进程通过JNI回调到system_server进程的。

4.2 onANRLocked

InputDispatcher.cpp的onANRLocked方法调用流程图如下,

4.2.1 C++流程

onANRLocked方法主要逻辑如下,

1,首先捕获ANR的现场信息,

time_t t = time(NULL);struct tm tm;localtime_r(&t, &tm);char timestr[64];strftime(timestr, sizeof(timestr), "%F %T", &tm);mLastANRState.clear();mLastANRState.append(INDENT "ANR:\n");mLastANRState.appendFormat(INDENT2 "Time: %s\n", timestr);mLastANRState.appendFormat(INDENT2 "Window: %s\n",getApplicationWindowLabelLocked(applicationHandle, windowHandle).string());mLastANRState.appendFormat(INDENT2 "DispatchLatency: %0.1fms\n", dispatchLatency);mLastANRState.appendFormat(INDENT2 "WaitDuration: %0.1fms\n", waitDuration);mLastANRState.appendFormat(INDENT2 "Reason: %s\n", reason);dumpDispatchStateLocked(mLastANRState);

2, 将ANR命令执行方法doNotifyANRLockedInterruptible加入mCommandQueue

CommandEntry* commandEntry = postCommandLocked(            & InputDispatcher::doNotifyANRLockedInterruptible);commandEntry->inputApplicationHandle = applicationHandle;commandEntry->inputWindowHandle = windowHandle;commandEntry->reason = reason;

发生ANR调用onANRLocked()的过程会将doNotifyANRLockedInterruptible加入mCommandQueue。 在下一轮InputDispatcher.dispatchOnce的

过程中会先执行runCommandsLockedInterruptible()方法，取出 mCommandQueue队列的所有命令逐一执行。那么ANR所对应的

命令doNotifyANRLockedInterruptible,该方法如下,

nsecs_t newTimeout = mPolicy->notifyANR(    commandEntry->inputApplicationHandle, commandEntry->inputWindowHandle,    commandEntry->reason);

mPolicy是指NativeInputManager对象, NativeInputManager是com_android_server_input_InputManagerService.cpp的内部类, 

NativeInputManager的notifyANR方法如下,

JNIEnv* env = jniEnv();jobject inputApplicationHandleObj =            getInputApplicationHandleObjLocalRef(env, inputApplicationHandle);jobject inputWindowHandleObj =            getInputWindowHandleObjLocalRef(env, inputWindowHandle);jstring reasonObj = env->NewStringUTF(reason.string());jlong newTimeout = env->CallLongMethod(mServiceObj,gServiceClassInfo.notifyANR, inputApplicationHandleObj, inputWindowHandleObj, reasonObj);

gServiceClassInfo是一个结构体,里面的变量一般指向InputManagerService.java中的方法,并且在register_android_server_InputManager方法中,给该结构体赋值,

GET_METHOD_ID(gServiceClassInfo.notifyANR, clazz,            "notifyANR",            "(Lcom/android/server/input/InputApplicationHandle;Lcom/android/server/input/InputWindowHandle;Ljava/lang/String;)J");

其中notifyANR变量指向的是InputManagerService的notifyANR方法,这样,流程终于走到Java层了。

4.2.2 Java层流程

InputManagerService的notifyANR方法如下,

return mWindowManagerCallbacks.notifyANR(                inputApplicationHandle, inputWindowHandle, reason);

WindowManagerCallbacks只是InputManagerService中的一个内部接口,具体的实现是在InputMonitor中,

 InputMonitor继承了WindowManagerCallbacks接口,并且实现了相对应的方法, InputMonitor的notifyANR方法如下,

如果是key 事件,就跨进程调用ActivityRecord 的内部类Token 的keyDispatchingTimedOut方法,

boolean abort = appWindowToken.appToken.keyDispatchingTimedOut(reason);

如果是触摸事件,跨进程调用AMS的inputDispatchingTimedOut方法,

long timeout = ActivityManagerNative.getDefault().inputDispatchingTimedOut(                        windowState.mSession.mPid, aboveSystem, reason);

ActivityRecord的内部类Token 的keyDispatchingTimedOut方法最后也会调用AMS的inputDispatchingTimedOut方法,该方法如下,

mHandler.post(new Runnable() {   @Override   public void run() {        appNotResponding(proc, activity, parent, aboveSystem, annotation);   }});

最后也是切换到主线程调用appNotResponding方法。