经典好文推荐，通过阅读本文，您将收获以下知识点:
一、Crash 概述
二、Crash处理流程
三、handleApplicationCrash处理分析
四、handleApplicationCrashInner 处理分析
五、APP Error info分析
六、makeAppCrashingLocked处理分析
七、startAppProblemLocked处理分析
八、stopFreezingAllLocked处理分析九、 AppErrors.handleAppCrashLocked()
十、UIHandler
十一、 killProcess
十二、小结
Android 9.0 Crash 机制调用链
/frameworks/base/core/java/com/android/internal/os/RuntimeInit.java
/frameworks/base/core/java/android/app/ActivityManagerNative.java (含内部类AMP)
/frameworks/base/core/java/android/app/ApplicationErrorReport.java/frameworks/base/services/core/java/com/android/server/
- am/ActivityManagerService.java
- am/ProcessRecord.java
- am/ActivityRecord.java
- am/ActivityStackSupervisor.java
- am/ActivityStack.java
- am/ActivityRecord.java
- am/BroadcastQueue.java
- wm/WindowManagerService.java
/libcore/libart/src/main/java/java/lang/Thread.java
App Crash (全称Application Crash), 对于Crash可分为Native Crash和 Framework Crash(包含app crash在内)，对于Crash相信很多app开发者都会遇到，那么上层什么时候会出现Crash呢，系统又是如何处理Crash的呢。例如，在app大家经常使用try...catch语句，那么如果没有有效catch exception，就是导致应用Crash，发生没有catch exception，系统便会来进行捕获，并进入Crash流程。如果你是从事Android系统开发或者架构相关工作，或者遇到需要解系统性的疑难杂症，那么很有必要了解系统Crash处理流程，知其然还需知其所以然；如果你仅仅是App初级开发，可能本文并非很适合阅读，整个系统流程错综复杂。
在Android系统启动系列文章，已讲述过上层应用都是由Zygote fork孵化而来，分为system_server系统进程和各种应用进程，在这些进程创建之初会设置未捕获异常的处理器，当系统抛出未捕获的异常时，最终都交给异常处理器。
对于
system_server进程：system_server启动过程中由RuntimeInit.java的commonInit方法设置UncaughtHandler，用于处理未捕获异常；对于普通应用进程：进程创建过程中，同样会调用
RuntimeInit.java的commonInit方法设置UncaughtHandler。
1.1 crash调用链
crash流程的方法调用关系如下：
AMP.handleApplicationCrash
AMS.handleApplicationCrash
AMS.findAppProcess
AMS.handleApplicationCrashInner
AMS.addErrorToDropBox
AMS.crashApplication
AMS.makeAppCrashingLocked
AMS.startAppProblemLocked
ProcessRecord.stopFreezingAllLocked
ActivityRecord.stopFreezingScreenLocked
WMS.stopFreezingScreenLocked
WMS.stopFreezingDisplayLocked
AMS.handleAppCrashLocked
mUiHandler.sendMessage(SHOW_ERROR_MSG)Process.killProcess(Process.myPid());
System.exit(10);
RuntimeInit.java类的 main方法会调用commonInit()方法。
public static final void main(String[] argv) {
enableDdms();
if (argv.length == 2 && argv[1].equals("application")) {
if (DEBUG) Slog.d(TAG, "RuntimeInit: Starting application");
redirectLogStreams();
} else {
if (DEBUG) Slog.d(TAG, "RuntimeInit: Starting tool");
}
// AP Crash 处理流程初始化
commonInit(); // Native Crash 处理流程初始化
nativeFinishInit();
if (DEBUG) Slog.d(TAG, "Leaving RuntimeInit!");
}
那么接下来以commonInit()方法为起点来展开说明。
1. RuntimeInit.commonInit
RuntimeInit.java
protected static final void commonInit() { /*
* set handlers; these apply to all threads in the VM. Apps can replace
* the default handler, but not the pre handler.
*/
LoggingHandler loggingHandler = new LoggingHandler();
// app不能 替换 setUncaughtExceptionPreHandler
Thread.setUncaughtExceptionPreHandler(loggingHandler);
// 将异常处理器handler对象赋给Thread成员变量,
Thread.setDefaultUncaughtExceptionHandler(new KillApplicationHandler(loggingHandler));
... ...
}
接下来我们看看LoggingHandler的实现。LoggingHandler实现 Thread.UncaughtExceptionHandler 方法。
private static class LoggingHandler implements Thread.UncaughtExceptionHandler {
public volatile boolean mTriggered = false; @Override
public void uncaughtException(Thread t, Throwable e) {
mTriggered = true;
//保证crash处理过程不会重入
if (mCrashing) return;
//mApplicationObject等于null,一定不是普通的app进程.
//但是除了system进程, 也有可能是shell进程,
//即通过app_process + 命令参数 的方式创建的进程.
if (mApplicationObject == null && (Process.SYSTEM_UID == Process.myUid())) {
//系统 进程Crash打印的Log 信息
/**
发生 系统Crash 时候可以搜索 关键字 FATAL EXCEPTION IN SYSTEM PROCESS
**/
Clog_e(TAG, "*** FATAL EXCEPTION IN SYSTEM PROCESS: " + t.getName(), e);
} else {
/**
发生 APP Crash 时候可以搜索 关键字 FATAL EXCEPTION
**/
StringBuilder message = new StringBuilder();
message.append("FATAL EXCEPTION: ").append(t.getName()).append("\n");
final String processName = ActivityThread.currentProcessName();
if (processName != null) {
message.append("Process: ").append(processName).append(", ");
}
message.append("PID: ").append(Process.myPid());
Clog_e(TAG, message.toString(), e);
}
}
}
1.当System进程Crash的信息：
开头 FATAL EXCEPTION IN SYSTEM PROCESS [线程名],接着输出Crash时的调用栈信息；
2.当app进程Crash时的信息：
开头 FATAL EXCEPTION: [线程名],紧接着 Process: [进程名], PID: [进程id]；最后输出发生Crash时的调用栈信息。
看到这里，你就会发现要从log中搜索Crash信息，只需要搜索关键词 FATAL EXCEPTION,即可查看出是那种异常；如果需要进一步筛选只搜索系统crash信息，则可以搜索的关键词可以有多样，比如 FATAL EXCEPTION IN SYSTEM PROCESS。
当输出完Crash信息到logcat里面，这只是Crash流程的刚开始阶段，接下来弹出Crash对话框，ActivityManagerNative.getDefault()返回的是ActivityManagerProxy（简称AMP），AMP经过binder调用最终交给ActivityManagerService(简称AMS)中相应的方法去处理,然后调用的是AMS.handleApplicationCrash()。
分析完LoggingHandler后，我们继续看setDefaultUncaughtExceptionHandler()，它只是将异常处理器handler对象赋给Thread成员变量,即Thread.setDefaultUncaughtExceptionHandler(new KillApplicationHandler(loggingHandler));。接下来看看KillApplicationHandler对象实例化过程。
2. KillApplicationHandler
RuntimeInit.java
KillApplicationHandler 实现 Thread.UncaughtExceptionHandler方法,主要处理由于未捕获的异常Crash导致APP 崩溃,运行在Main Thread的Framework 代码会捕获这些异常。
KillApplicationHandler 方法需要传递一个LoggingHandler的参数，
既 LoggingHandler loggingHandler = new LoggingHandler();，LoggingHandler在上文已经分析过，接下来我们看看KillApplicationHandler方法.
KillApplicationHandler方法如下:
private static class KillApplicationHandler implements Thread.UncaughtExceptionHandler {
private final LoggingHandler mLoggingHandler;
public KillApplicationHandler(LoggingHandler loggingHandler) {
// 构造方法，初始化 loggingHandler
this.mLoggingHandler = Objects.requireNonNull(loggingHandler);
} @Override
public void uncaughtException(Thread t, Throwable e) {
try {
ensureLogging(t, e);
// 保证crash处理过程不会重入
if (mCrashing) return;
mCrashing = true;
... ...
//启动crash对话框，等待处理完成 【见小节2.1和3】
ActivityManager.getService().handleApplicationCrash(
mApplicationObject, new ApplicationErrorReport.ParcelableCrashInfo(e));
} catch (Throwable t2) {
... ...
} finally {
//确保当前进程彻底杀掉【见小节11】
Process.killProcess(Process.myPid());
System.exit(10);
}
}
... ...
}
接下来我们看看启动Crash弹窗的处理。new ApplicationErrorReport.ParcelableCrashInfo(e)方法。
2.1 ApplicationErrorReport.ParcelableCrashInfo
ApplicationErrorReport 主要用来描述 APP Error信息。
APP ERROR 信息分类如下：
TYPE_CRASH：APP Crash 信息
TYPE_ANR：APP ANR 信息
TYPE_BATTERY：Battery 使用信息
TYPE_RUNNING_SERVICE：正在运行的Service 相关信息
// 主要处理 APP Error 信息
public class ApplicationErrorReport implements Parcelable { ... ...
public static class ParcelableCrashInfo extends CrashInfo implements Parcelable {
//创建 CrashInfo 实例，初始化异常信息
public ParcelableCrashInfo(Throwable tr) {
super(tr);
}
... ...
public static final Parcelable.Creator<ParcelableCrashInfo> CREATOR =
new Parcelable.Creator<ParcelableCrashInfo>() {
@Override
public ParcelableCrashInfo createFromParcel(Parcel in) {
return new ParcelableCrashInfo(in);
}
@Override
public ParcelableCrashInfo[] newArray(int size) {
return new ParcelableCrashInfo[size];
}
};
}
... ...
}
ParcelableCrashInfo 继承 CrashInfo,接下来我们看看 CrashInfo的实现。
CrashInfo
**CrashInfo ** 主要是将Crash信息文件名，类名，方法名，对应行号以及异常信息都封装到CrashInfo对象。
// 描述 Crash 信息
public static class CrashInfo { ... ...
public CrashInfo() {
}
//CrashInfo 初始化实例
public CrashInfo(Throwable tr) {
StringWriter sw = new StringWriter();
PrintWriter pw = new FastPrintWriter(sw, false, 256);
//输出栈trace
tr.printStackTrace(pw);
pw.flush();
stackTrace = sanitizeString(sw.toString());
exceptionMessage = tr.getMessage();
// 显示异常的根本原因
Throwable rootTr = tr;
while (tr.getCause() != null) {
tr = tr.getCause();
if (tr.getStackTrace() != null && tr.getStackTrace().length > 0) {
rootTr = tr;
}
String msg = tr.getMessage();
if (msg != null && msg.length() > 0) {
exceptionMessage = msg;
}
}
// Crash 异常类名称
exceptionClassName = rootTr.getClass().getName();
if (rootTr.getStackTrace().length > 0) {
StackTraceElement trace = rootTr.getStackTrace()[0];
// 获取 trace 文件名、类名、方法名、Crash 行号
throwFileName = trace.getFileName();
throwClassName = trace.getClassName();
throwMethodName = trace.getMethodName();
throwLineNumber = trace.getLineNumber();
} else {
throwFileName = "unknown";
... ...
}
exceptionMessage = sanitizeString(exceptionMessage);
}
handleApplicationCrash 会通过 JNI接口调用AMS中的方法。
//发送 Crash 弹窗handler，直到Dialog dismiss
ActivityManager.getService().handleApplicationCrash(
mApplicationObject, new ApplicationErrorReport.ParcelableCrashInfo(e));
ActivityManagerService.javahandleApplicationCrash 通过JNI 回调用 AMS中的handleApplicationCrash方法，进而调用AMS 中的内部方法handleApplicationCrashInner。
handleApplicationCrash
1.当远程
IBinder对象为空Null时，则进程名为system_server；2.当远程
IBinder对象不为空，且ProcessRecord为空时，则进程名为unknown;3.当远程
IBinder对象不为空，且ProcessRecord不为空时，则进程名为ProcessRecord对象中相应进程名。
// 当app Crash 时候，会调用此方法。
//调用结束后 ，app 进程就会推出
public void handleApplicationCrash(IBinder app,
ApplicationErrorReport.ParcelableCrashInfo crashInfo) {
// findAppProcess 详见 3.1 分析
ProcessRecord r = findAppProcess(app, "Crash");
// system_server 进程 为Null
final String processName = app == null ? "system_server"
: (r == null ? "unknown" : r.processName);
//handleApplicationCrashInner 详见 4 分析
handleApplicationCrashInner("crash", r, processName, crashInfo);
}
handleApplicationCrashInner主要是调用 AppErrors类中的crashApplication 方法处理。
void handleApplicationCrashInner(String eventType, ProcessRecord r, String processName,
ApplicationErrorReport.CrashInfo crashInfo) {
... ...
//调用APP Error 类方法中的 crashApplication
mAppErrors.crashApplication(r, crashInfo);
}3.1 findAppProcess
ActivityManagerService.javafindAppProcess主要是通过for循环遍历查找出IBinder对应的Process.
private ProcessRecord findAppProcess(IBinder app, String reason) {
... ...
synchronized (this) {
final int NP = mProcessNames.getMap().size();
for (int ip=0; ip<NP; ip++) {
SparseArray<ProcessRecord> apps = mProcessNames.getMap().valueAt(ip);
final int NA = apps.size();
for (int ia=0; ia<NA; ia++) {
ProcessRecord p = apps.valueAt(ia);
//当找到目标进程则返回
if (p.thread != null && p.thread.asBinder() == app) {
return p;
}
}
}
//如果代码执行到这里，表明无法找到应用所在的进程
return null;
}
}
其中 mProcessNames = new ProcessMap<ProcessRecord>();对于代码mProcessNames.getMap()返回的是mMap，而mMap= new ArrayMap<String, SparseArray<ProcessRecord>>();
知识延伸：SparseArray和ArrayMap是Android专门针对内存优化而设计的取代Java API中的HashMap的数据结构。
对于key是int类型则使用SparseArray，可避免自动装箱过程；
对于key为其他类型则使用ArrayMap。HashMap的查找和插入时间复杂度为O(1)的代价是牺牲大量的内存来实现的，而SparseArray和ArrayMap性能略逊于HashMap，但更节省内存。
再回到mMap，这是以进程name为key，再以(uid为key，以ProcessRecord为Value的)结构体作为value。下面看看其get()和put()方法
public E get(String name, int uid) {
SparseArray<E> uids = mMap.get(name);
if (uids == null) return null;
return uids.get(uid);
} public E put(String name, int uid, E value) {
SparseArray<E> uids = mMap.get(name);
if (uids == null) {
uids = new SparseArray<E>(2);
mMap.put(name, uids);
}
uids.put(uid, value);
return value;
}
findAppProcess()根据app(IBinder类型)来查询相应的目标对象ProcessRecord。
有了进程记录对象ProcessRecord和进程名processName，则进入执行Crash处理方法 AppErrors.java，继续往下看。
ActivityManagerService.java
void handleApplicationCrashInner(String eventType, ProcessRecord r, String processName,
ApplicationErrorReport.CrashInfo crashInfo) {
... ...
//将错误信息追加到DropBox
addErrorToDropBox(eventType, r, processName, null, null, null, null, null, crashInfo);
//【见小节5】
mAppErrors.crashApplication(r, crashInfo);
}
其中addErrorToDropBox是将Crash的信息输出到目录/data/system/dropbox。例如system_server的dropbox文件名为[email protected] (xxx代表的是时间戳)
AppErrors.java
AppErrors 主要是 控制APP Crash的场景条件。
void crashApplication(ProcessRecord r, ApplicationErrorReport.CrashInfo crashInfo) {
... ...
try {
// 调用内部 crashApplicationInner方法
crashApplicationInner(r, crashInfo, callingPid, callingUid);
} finally {
Binder.restoreCallingIdentity(origId);
}
}
crashApplicationInner内部方法
void crashApplicationInner(ProcessRecord r, ApplicationErrorReport.CrashInfo crashInfo,
int callingPid, int callingUid) {
... ...
AppErrorResult result = new AppErrorResult();
TaskRecord task;
synchronized (mService) {
// 如果是通过IActivityController 实例导致的Crash ，则不显示弹窗
// 详见5.1
if (handleAppCrashInActivityController(r, crashInfo, shortMsg, longMsg, stackTrace,
timeMillis, callingPid, callingUid)) {
return;
}
... ...
AppErrorDialog.Data data = new AppErrorDialog.Data();
data.result = result;
data.proc = r;
// 无法势必的进程 也不显示Crash 弹窗【见小节6】
if (r == null || !makeAppCrashingLocked(r, shortMsg, longMsg, stackTrace, data)) {
return;
} final Message msg = Message.obtain();
msg.what = ActivityManagerService.SHOW_ERROR_UI_MSG;
task = data.task;
msg.obj = data;
//发送消息SHOW_ERROR_MSG，弹出提示crash的对话框，等待用户选择【见小节10】
mService.mUiHandler.sendMessage(msg);
}
//进入阻塞等待，直到用户选择crash对话框"退出"或者"退出并报告"
int res = result.get();
Intent appErrorIntent = null;
MetricsLogger.action(mContext, MetricsProto.MetricsEvent.ACTION_APP_CRASH, res);
if (res == AppErrorDialog.TIMEOUT || res == AppErrorDialog.CANCEL) {
res = AppErrorDialog.FORCE_QUIT;
}
... ...
}
5.1 handleAppCrashInActivityController
handleAppCrashInActivityController,通过IActivityController 实例导致的Crash ，则不显示弹窗.AppError.java
private boolean handleAppCrashInActivityController(ProcessRecord r,
ApplicationErrorReport.CrashInfo crashInfo,
String shortMsg, String longMsg,
String stackTrace, long timeMillis,
int callingPid, int callingUid) {
... ...
// 当存在ActivityController的情况,比如monkey
try {
String name = r != null ? r.processName : null;
int pid = r != null ? r.pid : callingPid;
int uid = r != null ? r.info.uid : callingUid;
//调用monkey的 appCrashed
if (!mService.mController.appCrashed(name, pid,
shortMsg, longMsg, timeMillis, crashInfo.stackTrace)) {
if ("1".equals(SystemProperties.get(SYSTEM_DEBUGGABLE, "0"))
&& "Native crash".equals(crashInfo.exceptionClassName)) {
Slog.w(TAG, "Skip killing native crashed app " + name
+ "(" + pid + ") during testing");
} else {
Slog.w(TAG, "Force-killing crashed app " + name
+ " at watcher's request");
if (r != null) {
//调用`makeAppCrashingLocked`，继续处理crash流程
// 详见 小结 6
if (!makeAppCrashingLocked(r, shortMsg, longMsg, stackTrace, null))
{
r.kill("crash", true);
}
} else {
// Huh.
Process.killProcess(pid);
ActivityManagerService.killProcessGroup(uid, pid);
}
}
return true;
}
} catch (RemoteException e) {
mService.mController = null;
Watchdog.getInstance().setActivityController(null);
}
return false;
}
该方法主要做的两件事：
调用
makeAppCrashingLocked，继续处理Crash流程；发送消息
SHOW_ERROR_MSG，弹出提示Crash的对话框，等待用户选择；
接下来我们看makeAppCrashingLocked实现。
AppError.java
private boolean makeAppCrashingLocked(ProcessRecord app,
String shortMsg, String longMsg, String stackTrace, AppErrorDialog.Data data) {
app.crashing = true;
//封装crash信息到crashingReport对象
app.crashingReport = generateProcessError(app,
ActivityManager.ProcessErrorStateInfo.CRASHED, null, shortMsg, longMsg, stackTrace);
//【见小节7】
startAppProblemLocked(app);
//停止屏幕冻结【见小节8】
app.stopFreezingAllLocked();
//【见小节9】
return handleAppCrashLocked(app, "force-crash" /*reason*/, shortMsg, longMsg, stackTrace,
data);
}
AppError.javastartAppProblemLocked 该方法主要功能：
获取当前用户下的
crash应用的error receiver；忽略当前
App的广播接收；
void startAppProblemLocked(ProcessRecord app) {
// 如果不是当前user正在运行 app，这置为空
app.errorReportReceiver = null; for (int userId : mService.mUserController.getCurrentProfileIds()) {
if (app.userId == userId) {
//获取当前用户下的crash应用的error receiver【见小节7.1】
app.errorReportReceiver = ApplicationErrorReport.getErrorReportReceiver(
mContext, app.info.packageName, app.info.flags);
}
}
//忽略当前app的广播接收【见小节7.2】
mService.skipCurrentReceiverLocked(app);
}
7.1 getErrorReportReceiver
ApplicationErrorReport.java
获取当前用户下的Crash应用的error receiver
public static ComponentName getErrorReportReceiver(Context context,
String packageName, int appFlags) {
//检查Settings中的"send_action_app_error"是否使能错误报告的功能
int enabled = Settings.Global.getInt(context.getContentResolver(),
Settings.Global.SEND_ACTION_APP_ERROR, 0);
if (enabled == 0) {
//1.当未使能时，则直接返回
return null;
} PackageManager pm = context.getPackageManager();
// look for receiver in the installer package
String candidate = null;
ComponentName result = null;
try {
//获取该crash应用的安装器的包名
candidate = pm.getInstallerPackageName(packageName);
} catch (IllegalArgumentException e) {
// the package could already removed
}
if (candidate != null) {
result = getErrorReportReceiver(pm, packageName, candidate);
if (result != null) {
//2.当找到该crash应用的安装器，则返回；
return result;
}
}
//该系统属性名为"ro.error.receiver.system.apps"
if ((appFlags&ApplicationInfo.FLAG_SYSTEM) != 0) {
candidate = SystemProperties.get(SYSTEM_APPS_ERROR_RECEIVER_PROPERTY);
// 通过上下文对象传参，调用类内部方法
result = getErrorReportReceiver(pm, packageName, candidate);
if (result != null) {
//3.当crash应用是系统应用时，且系统属性指定error receiver时，则返回；
return result;
}
}
//该默认属性名为"ro.error.receiver.default"
candidate = SystemProperties.get(DEFAULT_ERROR_RECEIVER_PROPERTY);
//4.当默认属性值指定error receiver时，则返回；
return getErrorReportReceiver(pm, packageName, candidate);
}
getErrorReportReceiver：这是同名不同输入参数的另一个方法：
static ComponentName getErrorReportReceiver(PackageManager pm, String errorPackage,
String receiverPackage) {
if (receiverPackage == null || receiverPackage.length() == 0) {
return null;
} //当安装应用程序的安装器Crash，则直接返回
if (receiverPackage.equals(errorPackage)) {
return null;
}
//ACTION_APP_ERROR值为"android.intent.action.APP_ERROR"
Intent intent = new Intent(Intent.ACTION_APP_ERROR);
intent.setPackage(receiverPackage);
ResolveInfo info = pm.resolveActivity(intent, 0);
if (info == null || info.activityInfo == null) {
return null;
}
//创建包名为receiverPackage的组件
return new ComponentName(receiverPackage, info.activityInfo.name);
}
7.2 skipCurrentReceiverLocked
ActivityManagerService.java
忽略当前app的广播接收
void skipCurrentReceiverLocked(ProcessRecord app) {
for (BroadcastQueue queue : mBroadcastQueues) {
// 会调用BroadcastQueue 中的方法【见小节7.2.1】
queue.skipCurrentReceiverLocked(app);
}
}
7.2.1 skipCurrentReceiverLocked
BroadcastQueue.java skipCurrentReceiverLocked忽略当前app的广播接收.
public void skipCurrentReceiverLocked(ProcessRecord app) {
BroadcastRecord r = null;
//查看app进程中的广播
if (mOrderedBroadcasts.size() > 0) {
BroadcastRecord br = mOrderedBroadcasts.get(0);
// 判断是否一致
if (br.curApp == app) {
r = br;
}
}
... ...
if (r != null) {
// 见7.2.2
skipReceiverLocked(r);
}
}
7.2.2 skipReceiverLocked
BroadcastQueue.java
private void skipReceiverLocked(BroadcastRecord r) {
logBroadcastReceiverDiscardLocked(r);
//结束app进程的广播结束
finishReceiverLocked(r, r.resultCode, r.resultData,
r.resultExtras, r.resultAbort, false);
//执行广播调度
scheduleBroadcastsLocked();
}AppError.java中的 makeAppCrashingLocked方法（第6步），会调用stopFreezingAllLocked 方法
ProcessRecord.java
public void stopFreezingAllLocked() {
int i = activities.size();
while (i > 0) {
i--;
// 停止进程里所有的`Activity`. 详见8.1
activities.get(i).stopFreezingScreenLocked(true);
}
}其中activities类型为ArrayList<ActivityRecord>，停止进程里所有的Activity.
8.1 AR.stopFreezingScreenLocked
ActivityRecord.java,stopFreezingScreenLocked停止进程里所有的Activity.
public void stopFreezingScreenLocked(boolean force) {
if (force || frozenBeforeDestroy) {
frozenBeforeDestroy = false;
// mWindowContainerController 见【8.1.1】
mWindowContainerController.stopFreezingScreen(force);
}
}
8.1.1mWindowContainerController.stopFreezingScreen
stopFreezingScreen.java
public void stopFreezingScreen(boolean force) {
synchronized(mWindowMap) {
if (mContainer == null) {
return;
}
if (DEBUG_ORIENTATION) Slog.v(TAG_WM, "Clear freezing of " + mToken + ": hidden="
+ mContainer.isHidden() + " freezing=" + mContainer.isFreezingScreen());
mContainer.stopFreezingScreen(true, force);
}
}
8.1.1.1 WMS.stopFreezingScreenLocked
WindowManagerService.java
@Override
public void stopFreezingScreen() {
... ...
synchronized(mWindowMap) {
if (mClientFreezingScreen) {
mClientFreezingScreen = false;
mLastFinishedFreezeSource = "client";
final long origId = Binder.clearCallingIdentity();
try {
// 详见 8.1.1.2
stopFreezingDisplayLocked();
} finally {
Binder.restoreCallingIdentity(origId);
}
}
}
}
8.1.1.2 stopFreezingDisplayLocked();
WindowManagerService.java
该方法主要功能：
处理屏幕旋转相关逻辑；
移除冻屏的超时消息；
屏幕旋转动画的相关操作;
使能输入事件分发功能；display冻结时，执行gc操作；
更新当前的屏幕方向；
向mH发送configuraion改变的消息
rivate void stopFreezingDisplayLocked() {
if (!mDisplayFrozen) {
return; //显示没有冻结，则直接返回
} //往往跟屏幕旋转相关
...
mDisplayFrozen = false;
//从上次冻屏到现在的总时长
mLastDisplayFreezeDuration = (int)(SystemClock.elapsedRealtime() - mDisplayFreezeTime);
//移除冻屏的超时消息
mH.removeMessages(H.APP_FREEZE_TIMEOUT);
mH.removeMessages(H.CLIENT_FREEZE_TIMEOUT);
boolean updateRotation = false;
//获取默认的DisplayContent
final DisplayContent displayContent = getDefaultDisplayContentLocked();
final int displayId = displayContent.getDisplayId();
ScreenRotationAnimation screenRotationAnimation =
mAnimator.getScreenRotationAnimationLocked(displayId);
//屏幕旋转动画的相关操作
if (CUSTOM_SCREEN_ROTATION && screenRotationAnimation != null
&& screenRotationAnimation.hasScreenshot()) {
DisplayInfo displayInfo = displayContent.getDisplayInfo();
boolean isDimming = displayContent.isDimming();
if (!mPolicy.validateRotationAnimationLw(mExitAnimId, mEnterAnimId, isDimming)) {
mExitAnimId = mEnterAnimId = 0;
}
//加载动画最大时长为10s
if (screenRotationAnimation.dismiss(mFxSession, MAX_ANIMATION_DURATION,
getTransitionAnimationScaleLocked(), displayInfo.logicalWidth,
displayInfo.logicalHeight, mExitAnimId, mEnterAnimId)) {
scheduleAnimationLocked();
} else {
screenRotationAnimation.kill();
mAnimator.setScreenRotationAnimationLocked(displayId, null);
updateRotation = true;
}
} else {
if (screenRotationAnimation != null) {
screenRotationAnimation.kill();
mAnimator.setScreenRotationAnimationLocked(displayId, null);
}
updateRotation = true;
}
//经过层层调用到InputManagerService服务，IMS服务使能输入事件分发功能
mInputMonitor.thawInputDispatchingLw();
boolean configChanged;
//当display被冻结时不再计算屏幕方向，以避免不连续的状态。
configChanged = updateOrientationFromAppTokensLocked(false);
//display冻结时，执行gc操作
mH.removeMessages(H.FORCE_GC);
mH.sendEmptyMessageDelayed(H.FORCE_GC, 2000);
//mScreenFrozenLock的类型为PowerManager.WakeLock，即释放屏幕冻结的锁
mScreenFrozenLock.release();
if (updateRotation) {
//更新当前的屏幕方向
configChanged |= updateRotationUncheckedLocked(false);
}
if (configChanged) {
//向mH发送configuraion改变的消息
mH.sendEmptyMessage(H.SEND_NEW_CONFIGURATION);
}
}
九、 AppErrors.handleAppCrashLocked()
AppErrors.java
1.当同一进程在时间间隔小于1分钟时连续两次Crash，则执行的情况下：
对于非persistent进程：
[9.1] mStackSupervisor.handleAppCrashLocked(app);
[9.2] removeProcessLocked(app, false, false, “crash”);
[9.3] mStackSupervisor.resumeTopActivitiesLocked();
对于persistent进程，则只执行
[9.3] mStackSupervisor.resumeTopActivitiesLocked();
2.否则执行
[9.4] mStackSupervisor.finishTopCrashedActivitiesLocked(app, reason);
boolean handleAppCrashLocked(ProcessRecord app, String reason,
String shortMsg, String longMsg, String stackTrace, AppErrorDialog.Data data) {
final long now = SystemClock.uptimeMillis();
final boolean showBackground = Settings.Secure.getInt(mContext.getContentResolver(),
Settings.Secure.ANR_SHOW_BACKGROUND, 0) != 0; final boolean procIsBoundForeground =
(app.curProcState == ActivityManager.PROCESS_STATE_BOUND_FOREGROUND_SERVICE);
Long crashTime;
Long crashTimePersistent;
boolean tryAgain = false;
if (!app.isolated) {
crashTime = mProcessCrashTimes.get(app.info.processName, app.uid);
crashTimePersistent = mProcessCrashTimesPersistent.get(app.info.processName, app.uid);
} else {
crashTime = crashTimePersistent = null;
}
// Bump up the crash count of any services currently running in the proc.
//运行在当前进程中的所有服务的crash次数操作
for (int i = app.services.size() - 1; i >= 0; i--) {
// list 所有的Service
ServiceRecord sr = app.services.valueAt(i);
// Service 一会自动起来 重置count 为1，否则+1
if (now > sr.restartTime + ProcessList.MIN_CRASH_INTERVAL) {
sr.crashCount = 1;
} else {
sr.crashCount++;
}
// 允许重启正在Crash的服务以及 前台Service，wallpapers 等
if (sr.crashCount < mService.mConstants.BOUND_SERVICE_MAX_CRASH_RETRY
&& (sr.isForeground || procIsBoundForeground)) {
tryAgain = true;
}
}
//当同一个进程，连续两次crash的时间间隔小于1分钟时，则认为crash太过于频繁
if (crashTime != null && now < crashTime + ProcessList.MIN_CRASH_INTERVAL) {
Slog.w(TAG, "Process " + app.info.processName
+ " has crashed too many times: killing!");
EventLog.writeEvent(EventLogTags.AM_PROCESS_CRASHED_TOO_MUCH,
app.userId, app.info.processName, app.uid);
//【见小节9.1】
mService.mStackSupervisor.handleAppCrashLocked(app);
if (!app.persistent) {
//不再重启非persistent进程，除非用户显式地调用
EventLog.writeEvent(EventLogTags.AM_PROC_BAD, app.userId, app.uid,
app.info.processName);
if (!app.isolated) {
//将当前app加入到mBadProcesses
mBadProcesses.put(app.info.processName, app.uid,
new BadProcessInfo(now, shortMsg, longMsg, stackTrace));
mProcessCrashTimes.remove(app.info.processName, app.uid);
}
app.bad = true;
app.removed = true;
//移除非persistent 进程的所有服务，保证不再重启【见小节9.2】
mService.removeProcessLocked(app, false, tryAgain, "crash");
//恢复最顶部的Activity【见小节9.3】
mService.mStackSupervisor.resumeFocusedStackTopActivityLocked();
if (!showBackground) {
return false;
}
}
mService.mStackSupervisor.resumeFocusedStackTopActivityLocked();
} else {
//此处reason="force-crash"【见小节9.4】
final TaskRecord affectedTask =
mService.mStackSupervisor.finishTopRunningActivityLockedfinishTopRunningActivityLocked(app, reason);
if (data != null) {
data.task = affectedTask;
}
if (data != null && crashTimePersistent != null
&& now < crashTimePersistent + ProcessList.MIN_CRASH_INTERVAL) {
data.repeating = true;
}
}
if (data != null && tryAgain) {
data.isRestartableForService = true;
}
//当桌面Home 进程 应用crash，并且被三方app所取代，那么需要清空桌面应用的偏爱选项。
final ArrayList<ActivityRecord> activities = app.activities;
if (app == mService.mHomeProcess && activities.size() > 0
&& (mService.mHomeProcess.info.flags & ApplicationInfo.FLAG_SYSTEM) == 0) {
for (int activityNdx = activities.size() - 1; activityNdx >= 0; --activityNdx) {
final ActivityRecord r = activities.get(activityNdx);
if (r.isActivityTypeHome()) {
Log.i(TAG, "Clearing package preferred activities from " + r.packageName);
try {
//清空偏爱应用
ActivityThread.getPackageManager()
.clearPackagePreferredActivities(r.packageName);
} catch (RemoteException c) {
// pm is in same process, this will never happen.
}
}
}
}
if (!app.isolated) {
//无法记录孤立进程的crash时间点，由于他们并没有一个固定身份.
mProcessCrashTimes.put(app.info.processName, app.uid, now);
mProcessCrashTimesPersistent.put(app.info.processName, app.uid, now);
}
//当app存在crash的handler，那么交给其处理
if (app.crashHandler != null) mService.mHandler.post(app.crashHandler);
return true;
}
ActivityStackSupervisor.java
void handleAppCrashLocked(ProcessRecord app) {
for (int displayNdx = mActivityDisplays.size() - 1; displayNdx >= 0; --displayNdx) {
final ActivityDisplay display = mActivityDisplays.valueAt(displayNdx);
for (int stackNdx = display.getChildCount() - 1; stackNdx >= 0; --stackNdx) {
final ActivityStack stack = display.getChildAt(stackNdx);
//调用ActivityStack【见小节9.1.1】
stack.handleAppCrashLocked(app);
}
}
}
9.1.1 AS.handleAppCrashLocked
ActivityStack.java
void handleAppCrashLocked(ProcessRecord app) {
for (int taskNdx = mTaskHistory.size() - 1; taskNdx >= 0; --taskNdx) {
final ArrayList<ActivityRecord> activities = mTaskHistory.get(taskNdx).mActivities;
for (int activityNdx = activities.size() - 1; activityNdx >= 0; --activityNdx) {
final ActivityRecord r = activities.get(activityNdx);
if (r.app == app) {
Slog.w(TAG, " Force finishing activity "
+ r.intent.getComponent().flattenToShortString());
// Force the destroy to skip right to removal.
r.app = null;
mWindowManager.prepareAppTransition(TRANSIT_CRASHING_ACTIVITY_CLOSE,
false /* alwaysKeepCurrent */);
//结束当前activity
finishCurrentActivityLocked(r, FINISH_IMMEDIATELY, false,
"handleAppCrashedLocked");
}
}
}
}
这里的mTaskHistory数据类型为ArrayList，记录着所有先前的后台activities。遍历所有activities，找到位于该ProcessRecord的所有ActivityRecord，并结束该Acitivity。
9.2 AMS.removeProcessLocked
ActivityManagerService.java
@GuardedBy("this")
boolean removeProcessLocked(ProcessRecord app,
boolean callerWillRestart, boolean allowRestart, String reason) {
final String name = app.processName;
final int uid = app.uid;
if (DEBUG_PROCESSES) Slog.d(TAG_PROCESSES,
"Force removing proc " + app.toShortString() + " (" + name + "/" + uid + ")"); ProcessRecord old = mProcessNames.get(name, uid);
if (old != app) {
// This process is no longer active, so nothing to do.
Slog.w(TAG, "Ignoring remove of inactive process: " + app);
return false;
}
//从mProcessNames移除该进程
removeProcessNameLocked(name, uid);
if (mHeavyWeightProcess == app) {
mHandler.sendMessage(mHandler.obtainMessage(CANCEL_HEAVY_NOTIFICATION_MSG,
mHeavyWeightProcess.userId, 0));
mHeavyWeightProcess = null;
}
boolean needRestart = false;
if ((app.pid > 0 && app.pid != MY_PID) || (app.pid == 0 && app.pendingStart)) {
int pid = app.pid;
if (pid > 0) {
synchronized (mPidsSelfLocked) {
mPidsSelfLocked.remove(pid);
mHandler.removeMessages(PROC_START_TIMEOUT_MSG, app);
}
mBatteryStatsService.noteProcessFinish(app.processName, app.info.uid);
if (app.isolated) {
mBatteryStatsService.removeIsolatedUid(app.uid, app.info.uid);
getPackageManagerInternalLocked().removeIsolatedUid(app.uid);
}
}
boolean willRestart = false;
//对于非孤立的persistent进程设置成可重启flags
if (app.persistent && !app.isolated) {
if (!callerWillRestart) {
willRestart = true;
} else {
needRestart = true;
}
}
// 杀进程【9.2.1】
app.kill(reason, true);
//移除进程并清空该进程相关联的activity/service等组件 【9.2.2】
handleAppDiedLocked(app, willRestart, allowRestart);
if (willRestart) {
//此处willRestart=false，不进入该分支
removeLruProcessLocked(app);
addAppLocked(app.info, null, false, null /* ABI override */);
}
} else {
mRemovedProcesses.add(app);
}
return needRestart;
}
mProcessNames数据类型为ProcessMap，这是以进程名为key，记录着所有的ProcessRecord信息mPidsSelfLocked数据类型为SparseArray,这是以pid为key，记录着所有的ProcessRecord信息。该对象的同步保护是通过自身锁，而非全局ActivityManager锁。
9.2.1 app.kill
ProcessRecord.java]
void kill(String reason, boolean noisy) {
//通过am 杀进程
if (!killedByAm) { // 如果不想让am kill 当前进程，可以在这地方跳过
if (!mService.mAmsExt.shouldKilledByAm(this.processName, reason)) {
return;
}
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "kill");
if (mService != null && (noisy || info.uid == mService.mCurOomAdjUid)) {
mService.reportUidInfoMessageLocked(TAG,
"Killing " + toShortString() + " (adj " + setAdj + "): " + reason,
info.uid);
}
if (pid > 0) {
EventLog.writeEvent(EventLogTags.AM_KILL, userId, pid, processName, setAdj, reason);
// pid > 0 杀进程以及所在的进程组
Process.killProcessQuiet(pid);
ActivityManagerService.killProcessGroup(uid, pid);
} else {
pendingStart = false;
}
if (!persistent) {
killed = true;
killedByAm = true;
}
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
}
}
此处reason为“crash”.
9.2.2 handleAppDiedLocked
ActivityManagerService.java
// 通过AM 移除当前存在的进程，不存在，则清除当前进程包含的所有内容
@GuardedBy("this")
private final void handleAppDiedLocked(ProcessRecord app,
boolean restarting, boolean allowRestart) {
int pid = app.pid;
final boolean clearLaunchStartTime = !restarting && app.removed && app.foregroundActivities;
//清除应用中service/receiver/ContentProvider信息
boolean kept = cleanUpApplicationRecordLocked(app, restarting, allowRestart, -1,
false /*replacingPid*/);
if (!kept && !restarting) {
// 根据LRU 算法移除 app 进程
removeLruProcessLocked(app);
if (pid > 0) {
//从list 移除对应的pid
ProcessList.remove(pid);
}
} if (mProfileProc == app) {
clearProfilerLocked();
}
//清除应用中activity相关信息
boolean hasVisibleActivities = mStackSupervisor.handleAppDiedLocked(app);
app.clearRecentTasks();
app.activities.clear();
if (app.instr != null) {
Slog.w(TAG, "Crash of app " + app.processName
+ " running instrumentation " + app.instr.mClass);
Bundle info = new Bundle();
info.putString("shortMsg", "Process crashed.");
finishInstrumentationLocked(app, Activity.RESULT_CANCELED, info);
}
mWindowManager.deferSurfaceLayout();
try {
if (!restarting && hasVisibleActivities
&& !mStackSupervisor.resumeFocusedStackTopActivityLocked()) {
// If there was nothing to resume, and we are not already restarting this process, but
// there is a visible activity that is hosted by the process... then make sure all
// visible activities are running, taking care of restarting this process.
mStackSupervisor.ensureActivitiesVisibleLocked(null, 0, !PRESERVE_WINDOWS);
}
} finally {
mWindowManager.continueSurfaceLayout();
}
// TODO (b/67683350)
// When an app process is removed, activities from the process may be relaunched. In the
// case of forceStopPackageLocked the activities are finished before any window is drawn,
// and the launch time is not cleared. This will be incorrectly used to calculate launch
// time for the next launched activity launched in the same windowing mode.
if (clearLaunchStartTime) {
final LaunchTimeTracker.Entry entry = mStackSupervisor
.getLaunchTimeTracker().getEntry(mStackSupervisor.getWindowingMode());
if (entry != null) {
entry.mLaunchStartTime = 0;
}
}
}
ActivityStackSupervisor.java
boolean resumeFocusedStackTopActivityLocked() {
return resumeFocusedStackTopActivityLocked(null, null, null);
} boolean resumeFocusedStackTopActivityLocked(
ActivityStack targetStack, ActivityRecord target, ActivityOptions targetOptions) {
if (!readyToResume()) {
return false;
}
if (targetStack != null && isFocusedStack(targetStack)) {
//【见小节9.3.1】
return targetStack.resumeTopActivityUncheckedLocked(target, targetOptions);
}
final ActivityRecord r = mFocusedStack.topRunningActivityLocked();
if (r == null || !r.isState(RESUMED)) {
mFocusedStack.resumeTopActivityUncheckedLocked(null, null);
} else if (r.isState(RESUMED)) {
// Kick off any lingering app transitions form the MoveTaskToFront operation.
mFocusedStack.executeAppTransition(targetOptions);
}
return false;
}
9.3.1 AS.resumeTopActivityLocked
ActivityStack.java
//确保 top Activity 在resumed 状态
// 最好使用ActivityStackSupervisor#ActivityStackSupervisor#resumeFocusedStackTopActivityLockedActivityStackSupervisor#resumeFocusedStackTopActivityLocked 待替此方法
boolean resumeTopActivityUncheckedLocked(ActivityRecord prev, ActivityOptions options) {
if (mStackSupervisor.inResumeTopActivity) {
// Don't even start recursing.
return false;
} boolean result = false;
try {
// Protect against recursion.
mStackSupervisor.inResumeTopActivity = true;
result = resumeTopActivityInnerLocked(prev, options);
// When resuming the top activity, it may be necessary to pause the top activity (for
// example, returning to the lock screen. We suppress the normal pause logic in
// {@link #resumeTopActivityUncheckedLocked}, since the top activity is resumed at the
// end. We call the {@link ActivityStackSupervisor#checkReadyForSleepLocked} again here
// to ensure any necessary pause logic occurs. In the case where the Activity will be
// shown regardless of the lock screen, the call to
// {@link ActivityStackSupervisor#checkReadyForSleepLocked} is skipped.
final ActivityRecord next = topRunningActivityLocked(true /* focusableOnly */);
if (next == null || !next.canTurnScreenOn()) {
checkReadyForSleep();
}
} finally {
mStackSupervisor.inResumeTopActivity = false;
}
return result;
}
ActivityStackSupervisor.java
//Finish the topmost activities in all stacks that belong to the crashed app
TaskRecord finishTopCrashedActivitiesLocked(ProcessRecord app, String reason) {
TaskRecord finishedTask = null;
ActivityStack focusedStack = getFocusedStack();
for (int displayNdx = mActivityDisplays.size() - 1; displayNdx >= 0; --displayNdx) {
final ActivityDisplay display = mActivityDisplays.valueAt(displayNdx);
// It is possible that request to finish activity might also remove its task and stack,
// so we need to be careful with indexes in the loop and check child count every time.
for (int stackNdx = 0; stackNdx < display.getChildCount(); ++stackNdx) {
final ActivityStack stack = display.getChildAt(stackNdx);
////此处reason= "force-crash" 见小节9.4.1
final TaskRecord t = stack.finishTopCrashedActivityLocked(app, reason);
if (stack == focusedStack || finishedTask == null) {
finishedTask = t;
}
}
}
return finishedTask;
}
9.4.1AS.finishTopCrashedActivityLocked
ActivityStack.java
/**
* Finish the topmost activity that belongs to the crashed app. We may also finish the activity
* that requested launch of the crashed one to prevent launch-crash loop.
*/
final TaskRecord finishTopCrashedActivityLocked(ProcessRecord app, String reason) {
ActivityRecord r = topRunningActivityLocked();
TaskRecord finishedTask = null;
if (r == null || r.app != app) {
return null;
}
Slog.w(TAG, " Force finishing activity "
+ r.intent.getComponent().flattenToShortString());
finishedTask = r.getTask();
int taskNdx = mTaskHistory.indexOf(finishedTask);
final TaskRecord task = finishedTask;
int activityNdx = task.mActivities.indexOf(r);
mWindowManager.prepareAppTransition(TRANSIT_CRASHING_ACTIVITY_CLOSE,
false /* alwaysKeepCurrent */);
// 见小结 9.4.2
finishActivityLocked(r, Activity.RESULT_CANCELED, null, reason, false);
finishedTask = task;
// Also terminate any activities below it that aren't yet
// stopped, to avoid a situation where one will get
// re-start our crashing activity once it gets resumed again.
--activityNdx;
if (activityNdx < 0) {
do {
--taskNdx;
if (taskNdx < 0) {
break;
}
activityNdx = mTaskHistory.get(taskNdx).mActivities.size() - 1;
} while (activityNdx < 0);
}
if (activityNdx >= 0) {
r = mTaskHistory.get(taskNdx).mActivities.get(activityNdx);
if (r.isState(RESUMED, PAUSING, PAUSED)) {
if (!r.isActivityTypeHome() || mService.mHomeProcess != r.app) {
Slog.w(TAG, " Force finishing activity "
+ r.intent.getComponent().flattenToShortString());
finishActivityLocked(r, Activity.RESULT_CANCELED, null, reason, false);
}
}
}
return finishedTask;
}9.4.2 AS.finishActivityLocked
ActivityStack.java
/**
* See {@link #finishActivityLocked(ActivityRecord, int, Intent, String, boolean, boolean)}
*/
final boolean finishActivityLocked(ActivityRecord r, int resultCode, Intent resultData,
String reason, boolean oomAdj) {
return finishActivityLocked(r, resultCode, resultData, reason, oomAdj, !PAUSE_IMMEDIATELY);
} /**
* @return Returns true if this activity has been removed from the history
* list, or false if it is still in the list and will be removed later.
*/
final boolean finishActivityLocked(ActivityRecord r, int resultCode, Intent resultData,
String reason, boolean oomAdj, boolean pauseImmediately) {
if (r.finishing) {
Slog.w(TAG, "Duplicate finish request for " + r);
return false;
}
mWindowManager.deferSurfaceLayout();
try {
//设置finish状态的activity不可见
r.makeFinishingLocked();
final TaskRecord task = r.getTask();
EventLog.writeEvent(EventLogTags.AM_FINISH_ACTIVITY,
r.userId, System.identityHashCode(r),
task.taskId, r.shortComponentName, reason);
final ArrayList<ActivityRecord> activities = task.mActivities;
final int index = activities.indexOf(r);
if (index < (activities.size() - 1)) {
task.setFrontOfTask();
if ((r.intent.getFlags() & Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET) != 0) {
// If the caller asked that this activity (and all above it)
// be cleared when the task is reset, don't lose that information,
// but propagate it up to the next activity.
ActivityRecord next = activities.get(index+1);
next.intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
}
}
//暂停key的分发事件
r.pauseKeyDispatchingLocked();
adjustFocusedActivityStack(r, "finishActivity");
finishActivityResultsLocked(r, resultCode, resultData);
final boolean endTask = index <= 0 && !task.isClearingToReuseTask();
final int transit = endTask ? TRANSIT_TASK_CLOSE : TRANSIT_ACTIVITY_CLOSE;
if (mResumedActivity == r) {
if (DEBUG_VISIBILITY || DEBUG_TRANSITION) Slog.v(TAG_TRANSITION,
"Prepare close transition: finishing " + r);
if (endTask) {
mService.mTaskChangeNotificationController.notifyTaskRemovalStarted(
task.taskId);
}
mWindowManager.prepareAppTransition(transit, false);
// Tell window manager to prepare for this one to be removed.
r.setVisibility(false);
if (mPausingActivity == null) {
if (DEBUG_PAUSE) Slog.v(TAG_PAUSE, "Finish needs to pause: " + r);
if (DEBUG_USER_LEAVING) Slog.v(TAG_USER_LEAVING,
"finish() => pause with userLeaving=false");
//回调activity的onPause方法
startPausingLocked(false, false, null, pauseImmediately);
/// M: onBeforeActivitySwitch @{
ActivityRecord nextResumedActivity =
mStackSupervisor.getFocusedStack().topRunningActivityLocked();
if (nextResumedActivity != null) {
mService.mAmsExt.onBeforeActivitySwitch(
mService.mLastResumedActivity,
nextResumedActivity, true, nextResumedActivity.getActivityType());
}
/// M: onBeforeActivitySwitch @}
}
if (endTask) {
mService.getLockTaskController().clearLockedTask(task);
}
} else if (!r.isState(PAUSING)) {
// If the activity is PAUSING, we will complete the finish once
// it is done pausing; else we can just directly finish it here.
if (DEBUG_PAUSE) Slog.v(TAG_PAUSE, "Finish not pausing: " + r);
if (r.visible) {
prepareActivityHideTransitionAnimation(r, transit);
}
final int finishMode = (r.visible || r.nowVisible) ? FINISH_AFTER_VISIBLE
: FINISH_AFTER_PAUSE;
final boolean removedActivity = finishCurrentActivityLocked(r, finishMode, oomAdj,
"finishActivityLocked") == null;
// The following code is an optimization. When the last non-task overlay activity
// is removed from the task, we remove the entire task from the stack. However,
// since that is done after the scheduled destroy callback from the activity, that
// call to change the visibility of the task overlay activities would be out of
// sync with the activitiy visibility being set for this finishing activity above.
// In this case, we can set the visibility of all the task overlay activities when
// we detect the last one is finishing to keep them in sync.
if (task.onlyHasTaskOverlayActivities(true /* excludeFinishing */)) {
for (ActivityRecord taskOverlay : task.mActivities) {
if (!taskOverlay.mTaskOverlay) {
continue;
}
prepareActivityHideTransitionAnimation(taskOverlay, transit);
}
}
return removedActivity;
} else {
if (DEBUG_PAUSE) Slog.v(TAG_PAUSE, "Finish waiting for pause of: " + r);
}
return false;
} finally {
mWindowManager.continueSurfaceLayout();
}
}
通过mUiHandler发送message，且消息的msg.waht=SHOW_ERROR_MSG，接下来进入UiHandler来看看handleMessage的处理过程。
ActivityManagerService.java
final class UiHandler extends Handler {
public void handleMessage(Message msg) {
switch (msg.what) {
case SHOW_ERROR_MSG: {
HashMap<String, Object> data = (HashMap<String, Object>) msg.obj;
synchronized (ActivityManagerService.this) {
ProcessRecord proc = (ProcessRecord)data.get("app");
AppErrorResult res = (AppErrorResult) data.get("result");
、
boolean isBackground = (UserHandle.getAppId(proc.uid)
>= Process.FIRST_APPLICATION_UID
&& proc.pid != MY_PID);
... if (mShowDialogs && !mSleeping && !mShuttingDown) {
//创建提示crash对话框，等待用户选择，5分钟操作等待。
Dialog d = new AppErrorDialog(mContext,
ActivityManagerService.this, res, proc);
d.show();
proc.crashDialog = d;
} else {
//当处于sleep状态，则默认选择退出。
if (res != null) {
res.set(0);
}
}
}
} break;
...
}
}
在发生Crash时，默认系统会弹出提示crash的对话框，并阻塞等待用户选择是“退出”或 “退出并报告”，当用户不做任何选择时5min超时后，默认选择“退出”，当手机休眠时也默认选择“退出”。到这里也并没有真正结束，在小节2.uncaughtException中在finnally语句块还有一个杀进程的动作。
Process.killProcess(Process.myPid());
System.exit(10);
通过finnally语句块保证能执行并彻底杀掉Crash进程。当Crash进程被杀后，并没有完全结束，还有Binder死亡通知的流程还没有处理完成
当进程抛出未捕获异常时，则系统会处理该异常并进入Crash处理流程。
Crash处理流程
其中最为核心的工作图中红色部分AMS.handleAppCrashLocked的主要功能：
当同一进程1分钟之内连续两次
Crash，则执行的情况下：
对于非persistent进程：
-ASS.handleAppCrashLocked, 直接结束该应用所有activity
AMS.removeProcessLocked，杀死该进程以及同一个进程组下的所有进
-ASS.resumeTopActivitiesLocked，恢复栈顶第一个非finishing状态的activity
对于persistent进程，则只执行
ASS.resumeTopActivitiesLocked，恢复栈顶第一个非finishing状态的activity
2.否则，当进程没连续频繁crash
ASS.finishTopRunningActivityLocked，执行结束栈顶正在运行activity
另外，AMS.handleAppCrashLocked，该方法内部主要调用链，如下：
AMS.handleAppCrashLocked
ASS.handleAppCrashLocked
AS.handleAppCrashLocked
AS.finishCurrentActivityLocked
AMS.removeProcessLocked
ProcessRecord.kill
AMS.handleAppDiedLocked
ASS.handleAppDiedLocked
AMS.cleanUpApplicationRecordLocked
AS.handleAppDiedLocked
AS.removeHistoryRecordsForAppLocked ASS.resumeTopActivitiesLocked
AS.resumeTopActivityLocked
AS.resumeTopActivityInnerLocked
ASS.finishTopRunningActivityLocked
AS.finishTopRunningActivityLocked
AS.finishActivityLocked
推荐阅读
Android ANR/Crash Log日志分析技巧总结(建议收藏)
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