Android Service、 BroadcastReceiver、ContentProvider ANR 原理详解

本文主要是介绍Android Service、 BroadcastReceiver、ContentProvider ANR 原理详解，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

Service ANR：

启动Service 的时候，会调用到ActiveServices 类的 realStartServiceLocked方法。

    private final void realStartServiceLocked(ServiceRecord r,ProcessRecord app, boolean execInFg) throws RemoteException {//发送延迟消息bumpServiceExecutingLocked(r, execInFg, "create");}

    private final void bumpServiceExecutingLocked(ServiceRecord r, boolean fg, String why) {boolean timeoutNeeded = true;long now = SystemClock.uptimeMillis();if (r.app != null) {r.app.executingServices.add(r);r.app.execServicesFg |= fg;if (timeoutNeeded && r.app.executingServices.size() == 1) {scheduleServiceTimeoutLocked(r.app);}}} else if (r.app != null && fg && !r.app.execServicesFg) {r.app.execServicesFg = true;if (timeoutNeeded) {scheduleServiceTimeoutLocked(r.app);}}r.executeFg |= fg;r.executeNesting++;r.executingStart = now;}

继续调用scheduleServiceTimeoutLocked

    void scheduleServiceTimeoutLocked(ProcessRecord proc) {if (proc.executingServices.size() == 0 || proc.thread == null) {return;}Message msg = mAm.mHandler.obtainMessage(ActivityManagerService.SERVICE_TIMEOUT_MSG);msg.obj = proc;mAm.mHandler.sendMessageDelayed(msg,proc.execServicesFg ? SERVICE_TIMEOUT : SERVICE_BACKGROUND_TIMEOUT);}

可以看到，里面拿到AtivityManagerService 的 Mainhandler 发送一个延期消息。

当Service 启动之后，就会移除掉消息。（ActiveServices）见下面：

private void serviceDoneExecutingLocked(ServiceRecord r, boolean inDestroying,boolean finishing) {      if (r.executeNesting <= 0) {if (r.app != null) {     if (r.app.executingServices.size() == 0) {                  mAm.mHandler.removeMessages(ActivityManagerService.SERVICE_TIMEOUT_MSG, r.app);

BroadcastReceiver ANR：

当处理广播的时候，会走到下面的processNextBroadcastLocked 方法：

    final void processNextBroadcastLocked(boolean fromMsg, boolean skipOomAdj) {BroadcastRecord r;// First, deliver any non-serialized broadcasts right away.while (mParallelBroadcasts.size() > 0) {if (mService.mProcessesReady && r.dispatchTime > 0) {long now = SystemClock.uptimeMillis();if ((numReceivers > 0) &&(now > r.dispatchTime + (2*mTimeoutPeriod*numReceivers))) {broadcastTimeoutLocked(false); // forcibly finish this broadcastforceReceive = true;r.state = BroadcastRecord.IDLE;cancelBroadcastTimeoutLocked();}}

broadcastTimeoutLocked 里面会调用setBroadcastTimeoutLocked 方法，设置超时时间。

setBroadcastTimeoutLocked：

    final void setBroadcastTimeoutLocked(long timeoutTime) {if (! mPendingBroadcastTimeoutMessage) {Message msg = mHandler.obtainMessage(BROADCAST_TIMEOUT_MSG, this);mHandler.sendMessageAtTime(msg, timeoutTime);mPendingBroadcastTimeoutMessage = true;}}

BroadcastHandler 是自己的Handler，但是Looper 是ActivityManagerService 的 MainHandler 的Looper.

private final class BroadcastHandler extends Handler {public BroadcastHandler(Looper looper) {super(looper, null, true);}@Overridepublic void handleMessage(Message msg) {switch (msg.what) {case BROADCAST_INTENT_MSG: {if (DEBUG_BROADCAST) Slog.v(TAG_BROADCAST, "Received BROADCAST_INTENT_MSG");processNextBroadcast(true);} break;case BROADCAST_TIMEOUT_MSG: {synchronized (mService) {broadcastTimeoutLocked(true);}} break;}}}

处理ANR:

    final void broadcastTimeoutLocked(boolean fromMsg) {if (!debugging && anrMessage != null) {// Post the ANR to the handler since we do not want to process ANRs while// potentially holding our lock.mHandler.post(new AppNotResponding(app, anrMessage));}}

处理ANR:

    private final class AppNotResponding implements Runnable {private final ProcessRecord mApp;private final String mAnnotation;public AppNotResponding(ProcessRecord app, String annotation) {mApp = app;mAnnotation = annotation;}@Overridepublic void run() {mService.mAppErrors.appNotResponding(mApp, null, null, false, mAnnotation);}}

ContentProvider ANR：

ContentProvider Timeout是位于”ActivityManager”线程中的AMS.MainHandler收到CONTENT_PROVIDER_PUBLISH_TIMEOUT_MSG消息时触发。
ContentProvider 超时为CONTENT_PROVIDER_PUBLISH_TIMEOUT = 10s. 这个跟前面的Service和BroadcastQueue完全不同, 由Provider进程启动过程相关.

ContentProvider 是在app 启动的时候，初始化的。初始话的时候，会发一条延迟消息，CONTENT_PROVIDER_PUBLISH_TIMEOUT_MSG

if (providers != null && checkAppInLaunchingProvidersLocked(app)) {Message msg = mHandler.obtainMessage(CONTENT_PROVIDER_PUBLISH_TIMEOUT_MSG);msg.obj = app;mHandler.sendMessageDelayed(msg, CONTENT_PROVIDER_PUBLISH_TIMEOUT);}

当发布成功之后，就会移除掉这条消息。

    public final void publishContentProviders(IApplicationThread caller,List<ContentProviderHolder> providers) {if (wasInLaunchingProviders) {mHandler.removeMessages(CONTENT_PROVIDER_PUBLISH_TIMEOUT_MSG, r);}}}}

https://www.jianshu.com/p/1c827675f457

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