ANR代码流程分析.doc

Android ANR代码分析（技术文档）内容目录181 什么是ANR52 ANR代码执行流程52.1 事件分发超时ANR52.2 启动输入分发线程（InputDispatcherThread）52.3 输入事件的分发流程72.4 ANR处理流程132.5 针对Service超时的ANR处理流程172.6 针对Broadcast超时的ANR处理流程182.7 ANR超时时间222.8 序列图241 什么是ANRANR是“Application Not Responding”的缩写，即“应用程序无响应”。在Android中，ActivityManagerService（简称AMS）和WindowManagerService（简称WMS）会监测应用程序的响应时间，如果应用程序主线程（即UI线程）在超时时间内对输入事件没有处理完毕，或者对特定操作没有执行完毕，就会出现ANR。对于输入事件没有处理完毕产生的ANR，Android会显示一个对话框，提示用户当前应用程序没有响应，用户可以选择继续等待或者关闭这个应用程序（也就是杀掉这个应用程序的进程）。2 ANR代码执行流程本文档所有分析均基于Android 4.4原生代码。2.1 事件分发超时ANR响应事件超时的ANR流程大概如下，在系统输入管理服务进程（InputManagerService）中有一个单独线程（InputDispatcherThread）会专门管理输入事件分发，在该线程处理输入事件的过程中，会调用InputDispatcher不断的检测处理过程是否超时，一旦超时，会通过一系列的回调通知WMS的notifyANR函数，最终会触发AMS中mHandler对象里的SHOW_NOT_RESPONDING_MSG这个事件并在AMS中进行相应处理，此时界面上就会显示系统ANR提示对话框。2.2 启动输入分发线程（InputDispatcherThread）InputDispatcherThread作为输入事件分发处理的核心线程，会随系统服务InputManagerService的启动而启动。.frameworkbaseservicesjavacomandroidserverinputInputManagerService.javapublic class InputManagerService extends IInputManager.Stub implements Watchdog.Monitor, DisplayManagerService.InputManagerFuncs public InputManagerService(Context context, Handler handler) . mPtr = nativeInit(this, mContext, mHandler.getLooper().getQueue(); public void start() Slog.i(TAG, Starting input manager); nativeStart(mPtr); . InputManagerService在启动时会调用nativeStart方法，其中会启动InputDispatcherThread线程。具体代码在JNI方法nativeInit和nativeStart中实现。.frameworkbaseservicesjnicom_android_server_input_InputManagerService.cppstatic jint nativeInit(JNIEnv* env, jclass clazz, jobject serviceObj, jobject contextObj, jobject messageQueueObj) . NativeInputManager* im = new NativeInputManager(contextObj, serviceObj, messageQueue-getLooper(); im-incStrong(0); return reinterpret_cast(im);static void nativeStart(JNIEnv* env, jclass clazz, jint ptr) NativeInputManager* im = reinterpret_cast(ptr); status_t result = im-getInputManager()-start(); .在nativeInit中新建InputManager对象，并在nativeStart中调用InutManager的start方法。.frameworkbaseservicesinputInputManager.cppInputManager:InputManager( const sp& eventHub, const sp& readerPolicy, const sp& dispatcherPolicy) mDispatcher = new InputDispatcher(dispatcherPolicy); mReader = new InputReader(eventHub, readerPolicy, mDispatcher); initialize();void InputManager:initialize() mReaderThread = new InputReaderThread(mReader); mDispatcherThread = new InputDispatcherThread(mDispatcher); status_t InputManager:start() status_t result = mDispatcherThread-run(InputDispatcher, PRIORITY_URGENT_DISPLAY); . return OK;在InputManager构造方法中，会新建InputDispatcher对象，该对象会做为一个核心对象来处理所有输入事件分发逻辑。在initialize方法中，分发线程对象被建立，并在start方法中启动InputDispatcherThread线程。2.3 输入事件的分发流程输入事件的分发逻辑主要是在InputDispatcher类中实现的。先看一下InputDispatcherThread线程类：.frameworkbaseservicesinputInputDispatcher.cppInputDispatcherThread:InputDispatcherThread(const sp& dispatcher) : Thread(/*canCallJava*/ true), mDispatcher(dispatcher) bool InputDispatcherThread:threadLoop() mDispatcher-dispatchOnce(); return true;该线程的loop方法中，只执行InputDispatcher类的dispatchOnce方法。下面集中讨论一下InputDispatcher类：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); / 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);InputDispatcher类维护了一个command队列，在dispatchOnce方法中会检查该队列中是否有command项，没有的话会调用dispatchOnceInnerLocked方法做进一步处理，有的话则依序处理队列中所有command，并设置等待时间触发下一次轮询。DispatchOnceInnerLocked方法主要是检查是否有pending event，有的话就进行分发处理，下面具体关注与ANR相关的部分代码。void InputDispatcher:dispatchOnceInnerLocked(nsecs_t* nextWakeupTime) nsecs_t currentTime = now(); . switch (mPendingEvent-type) . case EventEntry:TYPE_KEY: KeyEntry* typedEntry = static_cast(mPendingEvent); . done = dispatchKeyLocked(currentTime, typedEntry, &dropReason, nextWakeupTime); break; case EventEntry:TYPE_MOTION: MotionEntry* typedEntry = static_cast(mPendingEvent); . done = dispatchMotionLocked(currentTime, typedEntry, &dropReason, nextWakeupTime); break; default: ALOG_ASSERT(false); break; 根据输入事件的类型进行分发处理，和ANR相关的有两种类型：按键和触摸。先看按键事件处理：bool InputDispatcher:dispatchKeyLocked(nsecs_t currentTime, KeyEntry* entry, DropReason* dropReason, nsecs_t* nextWakeupTime) . / Identify targets. Vector inputTargets; int32_t injectionResult = findFocusedWindowTargetsLocked(currentTime, entry, inputTargets, nextWakeupTime); if (injectionResult = INPUT_EVENT_INJECTION_PENDING) return false; setInjectionResultLocked(entry, injectionResult); if (injectionResult != INPUT_EVENT_INJECTION_SUCCEEDED) return true; addMonitoringTargetsLocked(inputTargets); / Dispatch the key. dispatchEventLocked(currentTime, entry, inputTargets); return true;.int32_t InputDispatcher:findFocusedWindowTargetsLocked(nsecs_t currentTime, const EventEntry* entry, Vector& inputTargets, nsecs_t* nextWakeupTime) int32_t injectionResult; / If there is no currently focused window and no focused application / then drop the event. if (mFocusedWindowHandle = NULL) if (mFocusedApplicationHandle != NULL) injectionResult = handleTargetsNotReadyLocked(currentTime, entry, mFocusedApplicationHandle, NULL, nextWakeupTime, Waiting because no window has focus but there is a focused application that may eventually add a window when it finishes starting up.); goto Unresponsive; ALOGI(Dropping event because there is no focused window or focused application.); injectionResult = INPUT_EVENT_INJECTION_FAILED; goto Failed; . / If the currently focused window is paused then keep waiting. if (mFocusedWindowHandle-getInfo()-paused) injectionResult = handleTargetsNotReadyLocked(currentTime, entry, mFocusedApplicationHandle, mFocusedWindowHandle, nextWakeupTime, Waiting because the focused window is paused.); goto Unresponsive; / If the currently focused window is still working on previous events then keep waiting. if (!isWindowReadyForMoreInputLocked(currentTime, mFocusedWindowHandle, entry) injectionResult = handleTargetsNotReadyLocked(currentTime, entry, mFocusedApplicationHandle, mFocusedWindowHandle, nextWakeupTime, Waiting because the focused window has not finished processing the input events that were previously delivered to it.); goto Unresponsive; .在该处理过程中，有一步是获取响应该事件的window target，主要是调用findFocusedWindowTargetsLocked完成。对此有三种情况，系统会认为没有ready的target：1）没有找到focused window和focused application; 2) focused window当前正处于pause状态； 3）focused window还没有处理完之前的事件。这些时候，handleTargetsNotReadyLocked方法就会被调用来处理这些异常情况。/ Default input dispatching timeout if there is no focused application or paused window/ from which to determine an appropriate dispatching timeout.const nsecs_t DEFAULT_INPUT_DISPATCHING_TIMEOUT = 5000 * 1000000LL; / 5 32_t InputDispatcher:handleTargetsNotReadyLocked(nsecs_t currentTime, const EventEntry* entry, const sp& applicationHandle, const sp& windowHandle, nsecs_t* nextWakeupTime, const char* reason) . if (applicationHandle = NULL & windowHandle = NULL) if (mInputTargetWaitCause != INPUT_TARGET_WAIT_CAUSE_SYSTEM_NOT_READY) mInputTargetWaitCause = INPUT_TARGET_WAIT_CAUSE_SYSTEM_NOT_READY; mInputTargetWaitStartTime = currentTime; mInputTargetWaitTimeoutTime = LONG_LONG_MAX; mInputTargetWaitTimeoutExpired = false; mInputTargetWaitApplicationHandle.clear(); else if (mInputTargetWaitCause != INPUT_TARGET_WAIT_CAUSE_APPLICATION_NOT_READY) nsecs_t timeout; 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; mInputTargetWaitCause = INPUT_TARGET_WAIT_CAUSE_APPLICATION_NOT_READY; mInputTargetWaitStartTime = currentTime; mInputTargetWaitTimeoutTime = currentTime + timeout; mInputTargetWaitTimeoutExpired = false; mInputTargetWaitApplicationHandle.clear(); . if (currentTime = mInputTargetWaitTimeoutTime) onANRLocked(currentTime, applicationHandle, windowHandle, entry-eventTime, mInputTargetWaitStartTime, reason); / Force poll loop to wake up immediately on next iteration once we get the / ANR response back from the policy. *nextWakeupTime = LONG_LONG_MIN; return INPUT_EVENT_INJECTION_PENDING; else / Force poll loop to wake up when timeout is due. if (mInputTargetWaitTimeoutTime *nextWakeupTime) *nextWakeupTime = mInputTargetWaitTimeoutTime; return INPUT_EVENT_INJECTION_PENDING; 当等待时间超时之后，就会触发ANR事件，并调用onANRLocked方法来做进一步处理。再看触摸事件的流程：bool InputDispatcher:dispatchMotionLocked( nsecs_t currentTime, MotionEntry* entry, DropReason* dropReason, nsecs_t* nextWakeupTime) Vector inputTargets; bool conflictingPointerActions = false; int32_t injectionResult; 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); .int32_t InputDispatcher:findTouchedWindowTargetsLocked(nsecs_t currentTime, const MotionEntry* entry, Vector& inputTargets, nsecs_t* nextWakeupTime, bool* outConflictingPointerActions) . / If there is an error window but it is not taking focus (typically because / it is invisible) then wait for it. Any other focused window may in / fact be in ANR state. if (topErrorWindowHandle != NULL & newTouchedWindowHandle != topErrorWindowHandle) injectionResult = handleTargetsNotReadyLocked(currentTime, entry, NULL, NULL, nextWakeupTime, Waiting because a system error window is about to be displayed.); injectionPermission = INJECTION_PERMISSION_UNKNOWN; goto Unresponsive; . / Ensure all touched foreground windows are ready for new input. for (size_t i = 0; i getInfo()-paused) injectionResult = handleTargetsNotReadyLocked(currentTime, entry, NULL, touchedWindow.windowHandle, nextWakeupTime, Waiting because the touched window is paused.); goto Unresponsive; / If the touched window is still working on previous events then keep waiting. if (!isWindowReadyForMoreInputLocked(currentTime, touchedWindow.windowHandle, entry) injectionResult = handleTargetsNotReadyLocked(currentTime, entry, NULL, touchedWindow.windowHandle, nextWakeupTime, Waiting because the touched window has not finished processing the input events that were previously delivered to it.); goto Unresponsive; 该流程ANR相关部分与按键处理流程类似，对于异常情况最终也调用handleTargetsNotReadyLocked方法来处理。2.4 ANR处理流程void InputDispatcher:onANRLocked( nsecs_t currentTime, const sp& applicationHandle, const sp& windowHandle, nsecs_t eventTime, nsecs_t waitStartTime, const char* reason) . CommandEntry* commandEntry = postCommandLocked( & InputDispatcher:doNotifyANRLockedInterruptible); commandEntry-inputApplicationHandle = applicationHandle; commandEntry-inputWindowHandle = windowHandle; commandEntry-reason = reason;InputDispatcher类的onANRLocked方法，会在command队列中post一个command，在处理该command时会调用关联的doNotifyANRLockedInterruptible方法。void InputDispatcher:doNotifyANRLockedInterruptible( CommandEntry* commandEntry) . nsecs_t newTimeout = mPolicy-notifyANR( commandEntry-inputApplicationHandle, commandEntry-inputWindowHandle, commandEntry-reason); .该方法会调用policy接口的notifyANR方法，其中通过com_android_server_input_InputManagerService.cpp中的JNI接口调用InputManagerService的notifyANR方法，该方法也是一个wrapper method，最终实现是在InputMonitor类的notifyANR方法中。.frameworkbaseservicesjavacomandroidserverinputInputManagerService.java private long notifyANR(InputApplicationHandle inputApplicationHandle, InputWindowHandle inputWindowHandle, String reason) return mWindowManagerCallbacks.notifyANR( inputApplicationHandle, inputWindowHandle, reason); 通过一系列调用，最终由ActivityManagerService弹出ANR对话框向用户提示“应用无响应”信息。.frameworkbaseservicesjavacomandroidserverwmInputMonitor.java public long notifyANR(InputApplicationHandle inputApplicationHandle, InputWindowHandle inputWindowHandle, String reason) . if (appWindowToken != null & appWindowToken.appToken != null) try / Notify the activity manager about the timeout and let it decide whether / to abort dispatching or keep waiting. boolean abort = appWindowToken.appToken.keyDispatchingTimedOut(reason); if (! abort) / The activity manager declined to abort dispatching. / Wait a bit longer and timeout again later. return appWindowToken.inputDispatchingTimeoutNanos; catch (RemoteException ex) else if (windowState != null) try / Notify the activity manager about the timeout and let it decide whether / to abort dispatching or keep waiting. long timeout = ActivityManagerNative.getDefault().inputDispatchingTimedOut( windowState.mSession.mPid, aboveSystem, reason); if (timeout = 0) / The activity manager declined to abort dispatching. / Wait a bit longer and timeout again later. return timeout; catch (RemoteException ex) return 0; / abort dispatching .frameworkbaseservicesjavacomandroidserveramActivityManagerService.java public boolean inputDispatchingTimedOut(final ProcessRecord proc, final ActivityRecord activity, final ActivityRecord parent, final boolean aboveSystem, String reason) . mHandler.post(new Runnable