四大組件的ANR觸發(fā)機制
Service、BroadcastReceiver和ContentProvider的ANR觸發(fā)機制都可以簡述為在AMS端的埋炸彈和拆炸彈過程。
以Service為例
AMS端啟動service時往handler post一條超時消息，消息到了之后就觸發(fā)anr，期間如果service正常起來，會回調(diào)AMS，remove這條消息。
埋炸彈
com/android/server/am/ActiveServices.java
void scheduleServiceTimeoutLocked(ProcessRecord proc) {
if (proc.executingServices.size() == 0 || proc.thread == null) {
return;
}
long now = SystemClock.uptimeMillis();
Message msg = mAm.mHandler.obtainMessage(
ActivityManagerService.SERVICE_TIMEOUT_MSG);
msg.obj = proc;
//當(dāng)超時后仍沒有remove該SERVICE_TIMEOUT_MSG消息，則執(zhí)行service Timeout流程
mAm.mHandler.sendMessageAtTime(msg,
proc.execServicesFg ? (now+SERVICE_TIMEOUT) : (now+ SERVICE_BACKGROUND_TIMEOUT));
}
拆炸彈
ActivityThread.java
private void handleCreateService(CreateServiceData data) {
...
java.lang.ClassLoader cl = packageInfo.getClassLoader();
Service service = (Service) cl.loadClass(data.info.name).newInstance();
...
try {
//創(chuàng)建ContextImpl對象
ContextImpl context = ContextImpl.createAppContext(this, packageInfo);
context.setOuterContext(service);
//創(chuàng)建Application對象
Application app = packageInfo.makeApplication(false, mInstrumentation);
service.attach(context, this, data.info.name, data.token, app,
ActivityManagerNative.getDefault());
//調(diào)用服務(wù)onCreate()方法 service.onCreate();
// ActivityManagerNative.getDefault().serviceDoneExecuting(
data.token, SERVICE_DONE_EXECUTING_ANON, 0, 0);
} catch (Exception e) {
...
}
}
ActivityThread.java
private void handleCreateService(CreateServiceData data) {
...
java.lang.ClassLoader cl = packageInfo.getClassLoader();
Service service = (Service) cl.loadClass(data.info.name).newInstance();
...
try {
//創(chuàng)建ContextImpl對象
ContextImpl context = ContextImpl.createAppContext(this, packageInfo);
context.setOuterContext(service);
//創(chuàng)建Application對象
Application app = packageInfo.makeApplication(false, mInstrumentation);
service.attach(context, this, data.info.name, data.token, app,
ActivityManagerNative.getDefault());
//調(diào)用服務(wù)onCreate()方法 service.onCreate();
// ActivityManagerNative.getDefault().serviceDoneExecuting(
data.token, SERVICE_DONE_EXECUTING_ANON, 0, 0);
} catch (Exception e) {
...
}
}
引爆炸彈
// ActivityManagerService.java ::MainHandler
final class MainHandler extends Handler {
public MainHandler(Looper looper) {
super(looper, null, true);
}
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
......case SERVICE_TIMEOUT_MSG: {
mServices.serviceTimeout((ProcessRecord)msg.obj);
} break;
}
}
void serviceTimeout(ProcessRecord proc) {
String anrMessage = null;
synchronized(mAm) {
if (proc.executingServices.size() == 0 || proc.thread == null) {
return;
}
final long now = SystemClock.uptimeMillis();
final long maxTime = now -
(proc.execServicesFg ? SERVICE_TIMEOUT : SERVICE_BACKGROUND_TIMEOUT);
ServiceRecord timeout = null;
long nextTime = 0;
for (int i=proc.executingServices.size()-1; i>=0; i--) { // 從進(jìn)程里面獲取正在運行的 service
ServiceRecord sr = proc.executingServices.valueAt(i);
if (sr.executingStart < maxTime) {
timeout = sr;
break;
}
if (sr.executingStart > nextTime) {
nextTime = sr.executingStart;
}
}
if (timeout != null && mAm.mLruProcesses.contains(proc)) {
Slog.w(TAG, "Timeout executing service: " + timeout);
StringWriter sw = new StringWriter();
PrintWriter pw = new FastPrintWriter(sw, false, 1024);
pw.println(timeout);
timeout.dump(pw, " ");
pw.close();
mLastAnrDump = sw.toString();
mAm.mHandler.removeCallbacks(mLastAnrDumpClearer);
mAm.mHandler.postDelayed(mLastAnrDumpClearer, LAST_ANR_LIFETIME_DURATION_MSECS);
anrMessage = "executing service " + timeout.shortName;
}
}
if (anrMessage != null) {
//當(dāng)存在timeout的service，則執(zhí)行appNotResponding
mAm.appNotResponding(proc, null, null, false, anrMessage);
}
}
注意ContentProvider埋炸彈的時機是在進(jìn)程啟動過程相關(guān)（因為ContentProvider是在進(jìn)程啟動時開啟生命周期，并把自己publish到AMS）。
input 觸發(fā)anr機制
input擁有不同的的超時機制，即在每次上報事件的時候檢測一把是否爆炸。
對于key事件，每次分發(fā)的時候檢測一把是否有事件沒有分發(fā)完或者沒有收到app分發(fā)完成的回調(diào);
對于觸摸事件，則檢測一把是否距離上一次分發(fā)給app的事件是否超過500ms。
上述原因滿足一條則進(jìn)入anr邏輯，在下一次事件分發(fā)時檢測時間是否超過5s且期間沒有收到app分發(fā)完成的回調(diào)，則正式觸發(fā)anr。
std::string InputDispatcher::checkWindowReadyForMoreInputLocked(nsecs_t currentTime,
const sp<InputWindowHandle>& windowHandle, const EventEntry* eventEntry,
const char* targetType) {
...
// Ensure that the dispatch queues aren't too far backed up for this event.
if (eventEntry->type == EventEntry::TYPE_KEY) {
// If the event is a key event, then we must wait for all previous events to
// complete before delivering it because previous events may have the
// side-effect of transferring focus to a different window and we want to
// ensure that the following keys are sent to the new window.
//
// Suppose the user touches a button in a window then immediately presses "A".
// If the button causes a pop-up window to appear then we want to ensure that
// the "A" key is delivered to the new pop-up window. This is because users
// often anticipate pending UI changes when typing on a keyboard.
// To obtain this behavior, we must serialize key events with respect to all
// prior input events.
if (!connection->outboundQueue.isEmpty() || !connection->waitQueue.isEmpty()) {
return StringPrintf("Waiting to send key event because the %s window has not "
"finished processing all of the input events that were previously "
"delivered to it. Outbound queue length: %d. Wait queue length: %d.",
targetType, connection->outboundQueue.count(), connection->waitQueue.count());
}
} else {
// Touch events can always be sent to a window immediately because the user intended
// to touch whatever was visible at the time. Even if focus changes or a new
// window appears moments later, the touch event was meant to be delivered to
// whatever window happened to be on screen at the time.
//
// Generic motion events, such as trackball or joystick events are a little trickier.
// Like key events, generic motion events are delivered to the focused window.
// Unlike key events, generic motion events don't tend to transfer focus to other
// windows and it is not important for them to be serialized. So we prefer to deliver
// generic motion events as soon as possible to improve efficiency and reduce lag
// through batching.
//
// The one case where we pause input event delivery is when the wait queue is piling
// up with lots of events because the application is not responding.
// This condition ensures that ANRs are detected reliably.
if (!connection->waitQueue.isEmpty()
&& currentTime >= connection->waitQueue.head->deliveryTime
+ STREAM_AHEAD_EVENT_TIMEOUT) {
return StringPrintf("Waiting to send non-key event because the %s window has not "
"finished processing certain input events that were delivered to it over "
"%0.1fms ago. Wait queue length: %d. Wait queue head age: %0.1fms.",
targetType, STREAM_AHEAD_EVENT_TIMEOUT * 0.000001f,
connection->waitQueue.count(),
(currentTime - connection->waitQueue.head->deliveryTime) * 0.000001f);
}
}
return "";
}
int32_t InputDispatcher::handleTargetsNotReadyLocked(nsecs_t currentTime){
// 如果失敗的原因是因為上一個任務(wù)未處理完，則不需要給超時時間重新賦值
if (mInputTargetWaitCause != INPUT_TARGET_WAIT_CAUSE_APPLICATION_NOT_READY) {
// 設(shè)置InputTargetWaitCause
mInputTargetWaitCause = INPUT_TARGET_WAIT_CAUSE_APPLICATION_NOT_READY;
//這里的currentTime是指執(zhí)行dispatchOnceInnerLocked方法體的起點
mInputTargetWaitStartTime = currentTime;
// timeout為5s
mInputTargetWaitTimeoutTime = currentTime + timeout;
mInputTargetWaitTimeoutExpired = false;
mInputTargetWaitApplicationHandle.clear();
}
//當(dāng)超時5s，則進(jìn)入ANR流程
if (currentTime >= mInputTargetWaitTimeoutTime) {
onANRLocked(currentTime, applicationHandle, windowHandle,
entry->eventTime, mInputTargetWaitStartTime, reason);
*nextWakeupTime = LONG_LONG_MIN; //強制立刻執(zhí)行輪詢來執(zhí)行ANR策略
return INPUT_EVENT_INJECTION_PENDING;
}
}
其他
anr觸發(fā)后通過發(fā)信號的方式觸發(fā)堆棧搜集。
final void appNotResponding(ProcessRecord app, ActivityRecord activity,
ActivityRecord parent, boolean aboveSystem, final String annotation) {
...
if (tracesFile == null) {
// There is no trace file, so dump (only) the alleged culprit's threads to the log
Process.sendSignal(app.pid, Process.SIGNAL_QUIT);
}
...
}
Image.png
No Window Focus Timeout，Window Timeout，Window Monitor Timeout。
