简介
回顾我们上一次说的一个app进程的启动过程，比如现在是当我们点击桌面上应用的图标，就会通过AMS，也就是system_server进程去和zygoteinit所在进程也就是zygote进程通过socket方式将启动进程所需要的参数传递给zygote，zygote在一个循环中一直在监听，当监有数据到来时候将数据封装之后fork出来子进程，子进程创建完成之后做一些Android环境的初始化，最终通过抛出异常的方式将调用到ActivityThread.main方法中。
我们今天的主题就接着上次说，开始我们可见的app之旅吧。
简介
回顾我们上一次说的一个app进程的启动过程，比如现在是当我们点击桌面上应用的图标，就会通过AMS，也就是system_server进程去和zygoteinit所在进程也就是zygote进程通过socket方式将启动进程所需要的参数传递给zygote，zygote在一个循环中一直在监听，当监有数据到来时候将数据封装之后fork出来子进程，子进程创建完成之后做一些Android环境的初始化，最终通过抛出异常的方式将调用到ActivityThread.main方法中。
我们今天的主题就接着上次说，开始我们可见的app之旅吧。
AT.main().png
扫个盲
//ZygoteInit.main()
public static void main(String argv[]) {
try {
runSelectLoop(abiList);
....
} catch (MethodAndArgsCaller caller) {
caller.run();
} catch (RuntimeException ex) {
closeServerSocket();
throw ex;
}
}
我们昨天一开始就执行这段代码，这段代码最终又跑去子进程的这段代码中caller.run();所以故事发生在主线程
1. ActivityThread.main()
public static void main(String[] args) {
//性能统计默认是关闭的
SamplingProfilerIntegration.start();
//将当前进程所在userId赋值给sCurrentUser
Environment.initForCurrentUser();
EventLogger.setReporter(new EventLoggingReporter());
AndroidKeyStoreProvider.install();
//确保可信任的CA证书存放在正确的位置
final File configDir = Environment.getUserConfigDirectory(UserHandle.myUserId());
TrustedCertificateStore.setDefaultUserDirectory(configDir);
Process.setArgV0("<pre-initialized>");
//创建主线程的Looper对象, 该Looper是不运行退出
Looper.prepareMainLooper();
//创建ActivityThread对象
ActivityThread thread = new ActivityThread();
//建立Binder通道
thread.attach(false);//[2]
if (sMainThreadHandler == null) {
sMainThreadHandler = thread.getHandler();
}
// 当设置为true时，可打开消息队列的debug log信息
if (false) {
Looper.myLooper().setMessageLogging(new LogPrinter(Log.DEBUG, "ActivityThread"));
}
Looper.loop(); //消息循环运行
throw new RuntimeException("Main thread loop unexpectedly exited");
}
这里注意事项：
ActivityThread还有一个地方可以创建就是在：
SystemServer.run()
createSystemContext()
ActivityThread.systemMain()
ActivityThread thread = new ActivityThread();
thread.attach(true);//这里是true
小节上面：
- 创建主线程的Looper对象, 该Looper是不运行退出
- 创建ActivityThread对象
我们还要注意，在创建AT中发生了什么：
- 创建了ResourcesManager对象
ActivityThread() {
mResourcesManager = ResourcesManager.getInstance();
}
- 成员变量中创建了
ApplicationThread mAppThread = new ApplicationThread(); -
H mH = new H();给主线程发送消息的Handler对象
2. ActivityThread.attach()
ActivityThread.java
//这里system=false
private void attach(boolean system) {
sCurrentActivityThread = this;
mSystemThread = system;
if (!system) {
//开启虚拟机的jit即时编译功能
ViewRootImpl.addFirstDrawHandler(new Runnable() {
@Override
public void run() {
ensureJitEnabled();
}
});
android.ddm.DdmHandleAppName.setAppName("<pre-initialized>", UserHandle.myUserId());
RuntimeInit.setApplicationObject(mAppThread.asBinder());
//创建ActivityManagerProxy对象
final IActivityManager mgr = ActivityManagerNative.getDefault();
try {
//调用基于IActivityManager接口的Binder通道
mgr.attachApplication(mAppThread);//[3]
} catch (RemoteException ex) {
}
//观察是否快接近heap的上限
BinderInternal.addGcWatcher(new Runnable() {
@Override public void run() {
if (!mSomeActivitiesChanged) {
return;
}
Runtime runtime = Runtime.getRuntime();
long dalvikMax = runtime.maxMemory();
long dalvikUsed = runtime.totalMemory() - runtime.freeMemory();
if (dalvikUsed > ((3*dalvikMax)/4)) {
mSomeActivitiesChanged = false;
try {
//当已用内存超过最大内存的3/4,则请求释放内存空间
mgr.releaseSomeActivities(mAppThread);
} catch (RemoteException e) {
}
}
}
});
} else {
...
}
//添加dropbox日志到libcore
DropBox.setReporter(new DropBoxReporter());
//添加Config回调接口
ViewRootImpl.addConfigCallback(new ComponentCallbacks2() {
@Override
public void onConfigurationChanged(Configuration newConfig) {
synchronized (mResourcesManager) {
if (mResourcesManager.applyConfigurationToResourcesLocked(newConfig, null)) {
if (mPendingConfiguration == null ||
mPendingConfiguration.isOtherSeqNewer(newConfig)) {
mPendingConfiguration = newConfig;
sendMessage(H.CONFIGURATION_CHANGED, newConfig);
}
}
}
}
@Override
public void onLowMemory() {
}
@Override
public void onTrimMemory(int level) {
}
});
}
这里做的事情：
- ensureJitEnabled();具体是啥不知道
-
android.ddm.DdmHandleAppName.setAppName("<pre-initialized>",UserHandle.myUserId());设置进程名 - 创建AMP
- 给AMP绑定ApplicationThread对象
- 看app进程内存情况，如果太大则释放内存
- 给ViewRootImpl添加一个config的回调接口
这里需要注意：
final IActivityManager mgr = ActivityManagerNative.getDefault();
static public IActivityManager getDefault() {
return gDefault.get();
}
这里得到的Service是activity,activity是在SystemServer中通过AMS.setSystemProcess()中添加的服务，对应AMS
private static final Singleton<IActivityManager> gDefault = new Singleton<IActivityManager>() {
protected IActivityManager create() {
IBinder b = ServiceManager.getService("activity");
if (false) {
Log.v("ActivityManager", "default service binder = " + b);
}
IActivityManager am = asInterface(b);
if (false) {
Log.v("ActivityManager", "default service = " + am);
}
return am;
}
};
3. AMS.attachApplication()
ActivityManagerService.java
在这里我们把握一个核心，这里子进程已经通过Binder调用到了AMS所在进程，也就是system_server进程了
private final boolean attachApplicationLocked(IApplicationThread thread,
int pid) {//此pid是调用者的pid
ProcessRecord app;
if (pid != MY_PID && pid >= 0) {
synchronized (mPidsSelfLocked) {
app = mPidsSelfLocked.get(pid); // 根据pid获取ProcessRecord对象
}
} else {
app = null;
}
if (app == null) {
if (pid > 0 && pid != MY_PID) {
//ProcessRecord为空，则杀掉该进程
Process.killProcessQuiet(pid);
} else {
//退出新建进程的Looper
thread.scheduleExit();
}
return false;
}
//还刚进入attach过程,此时thread应该为null,若不为null则表示该app附到上一个进程，则立刻清空
if (app.thread != null) {
handleAppDiedLocked(app, true, true);
}
final String processName = app.processName;
try {
//绑定死亡通知，注意这里是ApplicationThread的代理对象要linkToDeath
//也就是如果ApplicationThread（继承Binder）挂掉了在AppDeathRecipient中可以接收到信息
AppDeathRecipient adr = new AppDeathRecipient(app, pid, thread);
thread.asBinder().linkToDeath(adr, 0);
app.deathRecipient = adr;
} catch (RemoteException e) {
app.resetPackageList(mProcessStats);
startProcessLocked(app, "link fail", processName); //重新启动进程
return false;
}
//重置进程信息
app.makeActive(thread, mProcessStats); //执行完该语句,则app.thread便不再为空
app.curAdj = app.setAdj = -100;
app.curSchedGroup = app.setSchedGroup = Process.THREAD_GROUP_DEFAULT;
app.forcingToForeground = null;
updateProcessForegroundLocked(app, false, false);
app.hasShownUi = false;
app.debugging = false;
app.cached = false;
app.killedByAm = false;
mHandler.removeMessages(PROC_START_TIMEOUT_MSG, app); //移除进程启动超时的消息，这里超时是在AMS启动进程时候加上去的，所以这里一旦启动就要移除
//系统处于ready状态或者该app为FLAG_PERSISTENT进程,则为true
boolean normalMode = mProcessesReady || isAllowedWhileBooting(app.info);
List<ProviderInfo> providers = normalMode ? generateApplicationProvidersLocked(app) : null;
//app进程存在正在启动中的provider,则超时10s后发送CONTENT_PROVIDER_PUBLISH_TIMEOUT_MSG消息
//这里已经开始provider的操作了
if (providers != null && checkAppInLaunchingProvidersLocked(app)) {
Message msg = mHandler.obtainMessage(CONTENT_PROVIDER_PUBLISH_TIMEOUT_MSG);
msg.obj = app;
mHandler.sendMessageDelayed(msg, CONTENT_PROVIDER_PUBLISH_TIMEOUT);
}
try {
...
//获取应用appInfo
ApplicationInfo appInfo = app.instrumentationInfo != null
? app.instrumentationInfo : app.info;
...
// 绑定应用[4]
thread.bindApplication(processName, appInfo, providers, app.instrumentationClass,
profilerInfo, app.instrumentationArguments, app.instrumentationWatcher,
app.instrumentationUiAutomationConnection, testMode, enableOpenGlTrace,
isRestrictedBackupMode || !normalMode, app.persistent,
new Configuration(mConfiguration), app.compat,
getCommonServicesLocked(app.isolated),
mCoreSettingsObserver.getCoreSettingsLocked());
//更新进程LRU队列
updateLruProcessLocked(app, false, null);
app.lastRequestedGc = app.lastLowMemory = SystemClock.uptimeMillis();
} catch (Exception e) {
app.resetPackageList(mProcessStats);
app.unlinkDeathRecipient();
//每当bind操作失败,则重启启动进程, 此处有可能会导致进程无限重启
startProcessLocked(app, "bind fail", processName);
return false;
}
mPersistentStartingProcesses.remove(app);
mProcessesOnHold.remove(app);
boolean badApp = false;
boolean didSomething = false;
//Activity: 检查最顶层可见的Activity是否等待在该进程中运行
if (normalMode) {
try {
if (mStackSupervisor.attachApplicationLocked(app)) {
didSomething = true;
}
} catch (Exception e) {
badApp = true;
}
}
//Service: 寻找所有需要在该进程中运行的服务
if (!badApp) {
try {
didSomething |= mServices.attachApplicationLocked(app, processName);
} catch (Exception e) {
badApp = true;
}
}
//Broadcast: 检查是否在这个进程中有下一个广播接收者
if (!badApp && isPendingBroadcastProcessLocked(pid)) {
try {
didSomething |= sendPendingBroadcastsLocked(app);
} catch (Exception e) {
badApp = true;
}
}
//检查是否在这个进程中有下一个backup代理
if (!badApp && mBackupTarget != null && mBackupTarget.appInfo.uid == app.uid) {
ensurePackageDexOpt(mBackupTarget.appInfo.packageName);
try {
thread.scheduleCreateBackupAgent(mBackupTarget.appInfo,
compatibilityInfoForPackageLocked(mBackupTarget.appInfo),
mBackupTarget.backupMode);
} catch (Exception e) {
badApp = true;
}
}
if (badApp) { //杀掉bad应用
app.kill("error during init", true);
handleAppDiedLocked(app, false, true);
return false;
}
if (!didSomething) {
updateOomAdjLocked(); //更新adj的值
}
return true;
}
我们这里必须小节一下：
- 设置代表该应用进程的ProcessRecord对象的一些成员变量
- 初步设置oo_adj的值，这个是进程优先级核心
- 撤销PROC_START+TIMEOUT_MSG对应操作
- 调用ApplicationThread的binderApplication
- 通知应用进程启动Acivity，Service等组件其中用于启动activity的函数是realStartActivityLocked
4. ApplicationThread.bindApplication()
我们通过APP所在进程，然后通过binder跨到AMS，通过AMS做一些处理之后，然后又调用到APP的进程中保存一些AMS处理过后的信息
public final void bindApplication(String processName, ApplicationInfo appInfo,
List<ProviderInfo> providers, ComponentName instrumentationName,
ProfilerInfo profilerInfo, Bundle instrumentationArgs,
IInstrumentationWatcher instrumentationWatcher,
IUiAutomationConnection instrumentationUiConnection, int debugMode,
boolean enableBinderTracking, boolean trackAllocation,
boolean isRestrictedBackupMode, boolean persistent, Configuration config,
CompatibilityInfo compatInfo, Map<String, IBinder> services, Bundle coreSettings) {
if (services != null) {
//保存AMS传递来系统service的信息
ServiceManager.initServiceCache(services);
}
setCoreSettings(coreSettings);//给主线程发消息H.SET_CORE_SETTINGS保存coreSettings的值
AppBindData data = new AppBindData();//存储变量的
data.processName = processName;
data.appInfo = appInfo;
data.providers = providers;
data.instrumentationName = instrumentationName;
data.instrumentationArgs = instrumentationArgs;
data.instrumentationWatcher = instrumentationWatcher;
data.instrumentationUiAutomationConnection = instrumentationUiConnection;
data.debugMode = debugMode;
data.enableBinderTracking = enableBinderTracking;
data.trackAllocation = trackAllocation;
data.restrictedBackupMode = isRestrictedBackupMode;
data.persistent = persistent;
data.config = config;
data.compatInfo = compatInfo;
data.initProfilerInfo = profilerInfo;
sendMessage(H.BIND_APPLICATION, data);//[5]给主线程发送消息BIND_APPLICATION，将data传递过去
}
其中setCoreSettings(coreSettings);这一句也很重要
private void handleSetCoreSettings(Bundle coreSettings) {
synchronized (mResourcesManager) {
mCoreSettings = coreSettings;
}
onCoreSettingsChange();
}
private void onCoreSettingsChange() {
boolean debugViewAttributes = mCoreSettings.getInt(Settings.Global.DEBUG_VIEW_ATTRIBUTES, 0) != 0;
if (debugViewAttributes != View.mDebugViewAttributes) {
View.mDebugViewAttributes = debugViewAttributes;
// 由于发生改变, 请求所有的activities重启启动
for (Map.Entry<IBinder, ActivityClientRecord> entry : mActivities.entrySet()) {
requestRelaunchActivity(entry.getKey(), null, null, 0, false, null, null, false);
}
}
}
5. ActivityThread.handleBindApplication(data);
private void handleBindApplication(AppBindData data) {
mBoundApplication = data;
mConfiguration = new Configuration(data.config);
mCompatConfiguration = new Configuration(data.config);
...
//设置进程名, 也就是说进程名是在进程真正创建以后的BIND_APPLICATION过程中才取名，前面那个名字不算
Process.setArgV0(data.processName);
android.ddm.DdmHandleAppName.setAppName(data.processName, UserHandle.myUserId());
if (data.persistent) {
//低内存设备, persistent进程不采用硬件加速绘制,以节省内存使用量
if (!ActivityManager.isHighEndGfx()) {
HardwareRenderer.disable(false);
}
}
//重置时区
TimeZone.setDefault(null);
Locale.setDefault(data.config.locale);
//更新系统配置
mResourcesManager.applyConfigurationToResourcesLocked(data.config, data.compatInfo);
mCurDefaultDisplayDpi = data.config.densityDpi;
applyCompatConfiguration(mCurDefaultDisplayDpi);
//获取LoadedApk对象[5.1]
data.info = getPackageInfoNoCheck(data.appInfo, data.compatInfo);
...
// 创建ContextImpl上下文
final ContextImpl appContext = ContextImpl.createAppContext(this, data.info);
if (!Process.isIsolated()) {
final File cacheDir = appContext.getCacheDir();
if (cacheDir != null) {
System.setProperty("java.io.tmpdir", cacheDir.getAbsolutePath());
}
//用于存储产生/编译的图形代码
final File codeCacheDir = appContext.getCodeCacheDir();
if (codeCacheDir != null) {
setupGraphicsSupport(data.info, codeCacheDir);
}
}
...
//当处于调试模式,则运行应用生成systrace信息
boolean appTracingAllowed = (data.appInfo.flags&ApplicationInfo.FLAG_DEBUGGABLE) != 0;
Trace.setAppTracingAllowed(appTracingAllowed);
//初始化 默认的http代理
IBinder b = ServiceManager.getService(Context.CONNECTIVITY_SERVICE);
if (b != null) {
IConnectivityManager service = IConnectivityManager.Stub.asInterface(b);
final ProxyInfo proxyInfo = service.getProxyForNetwork(null);
Proxy.setHttpProxySystemProperty(proxyInfo);
}
if (data.instrumentationName != null) {
...
} else {
mInstrumentation = new Instrumentation();
}
//FLAG_LARGE_HEAP则清除内存增长上限
if ((data.appInfo.flags&ApplicationInfo.FLAG_LARGE_HEAP) != 0) {
dalvik.system.VMRuntime.getRuntime().clearGrowthLimit();
} else {
dalvik.system.VMRuntime.getRuntime().clampGrowthLimit();
}
try {
// 此处data.info是指LoadedApk, 通过反射创建目标应用Application对象[5.2]
Application app = data.info.makeApplication(data.restrictedBackupMode, null);
mInitialApplication = app;
if (!data.restrictedBackupMode) {
List<ProviderInfo> providers = data.providers;
if (providers != null) {
installContentProviders(app, providers);
mH.sendEmptyMessageDelayed(H.ENABLE_JIT, 10*1000);
}
}
mInstrumentation.onCreate(data.instrumentationArgs);
//调用Application.onCreate()回调方法.
mInstrumentation.callApplicationOnCreate(app);
} finally {
StrictMode.setThreadPolicy(savedPolicy);
}
}
小节：
- 创建一个Application对象，该对象是本进程中运行的第一个Application，是通过指LoadedApk
- 如果该Application有ContentProvider则应该安装他们
在这里就开始创建ContentProvider了，所以ContentProvider的创建比其他组件要早。
5.1 ActivityThread.getPackageInfoNoCheck()
public final LoadedApk getPackageInfoNoCheck(ApplicationInfo ai,
CompatibilityInfo compatInfo) {
return getPackageInfo(ai, compatInfo, null, false, true, false);
}
private LoadedApk getPackageInfo(ApplicationInfo aInfo, CompatibilityInfo compatInfo,
ClassLoader baseLoader, boolean securityViolation, boolean includeCode,
boolean registerPackage) {
final boolean differentUser = (UserHandle.myUserId() != UserHandle.getUserId(aInfo.uid));
synchronized (mResourcesManager) {
WeakReference<LoadedApk> ref;
if (differentUser) {
// Caching not supported across users
ref = null;
} else if (includeCode) {
ref = mPackages.get(aInfo.packageName);
} else {
ref = mResourcePackages.get(aInfo.packageName);
}
LoadedApk packageInfo = ref != null ? ref.get() : null;
if (packageInfo == null || (packageInfo.mResources != null
&& !packageInfo.mResources.getAssets().isUpToDate())) {
packageInfo =
new LoadedApk(this, aInfo, compatInfo, baseLoader,
securityViolation, includeCode &&
(aInfo.flags&ApplicationInfo.FLAG_HAS_CODE) != 0, registerPackage);
if (mSystemThread && "android".equals(aInfo.packageName)) {
packageInfo.installSystemApplicationInfo(aInfo,
getSystemContext().mPackageInfo.getClassLoader());
}
if (differentUser) {
// Caching not supported across users
} else if (includeCode) {
mPackages.put(aInfo.packageName,
new WeakReference<LoadedApk>(packageInfo));
} else {
mResourcePackages.put(aInfo.packageName,
new WeakReference<LoadedApk>(packageInfo));
}
}
return packageInfo;
}
}
5.1做的事情主要就是创建了LoadedApk然后返回
5.2 LoadedApk.makeApplication()
public Application makeApplication(boolean forceDefaultAppClass,
Instrumentation instrumentation) {
if (mApplication != null) {
return mApplication;
}
Application app = null;
String appClass = mApplicationInfo.className;
if (forceDefaultAppClass || (appClass == null)) {
appClass = "android.app.Application";//默认在这里
}
try {
java.lang.ClassLoader cl = getClassLoader();
if (!mPackageName.equals("android")) {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER,
"initializeJavaContextClassLoader");
initializeJavaContextClassLoader();
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
}
ContextImpl appContext = ContextImpl.createAppContext(mActivityThread, this);//创建ContextImpl对象
//创建Application对象, 该对象名来自于mApplicationInfo.className.
app = mActivityThread.mInstrumentation.newApplication(
cl, appClass, appContext);
appContext.setOuterContext(app);
} catch (Exception e) {
...
}
mActivityThread.mAllApplications.add(app);
mApplication = app;
if (instrumentation != null) {
try {
instrumentation.callApplicationOnCreate(app);
} catch (Exception e) {
...
}
}
// Rewrite the R 'constants' for all library apks.
SparseArray<String> packageIdentifiers = getAssets(mActivityThread)
.getAssignedPackageIdentifiers();
final int N = packageIdentifiers.size();
for (int i = 0; i < N; i++) {
final int id = packageIdentifiers.keyAt(i);
if (id == 0x01 || id == 0x7f) {
continue;
}
//写R常量
rewriteRValues(getClassLoader(), packageIdentifiers.valueAt(i), id);
}
return app;
}
主要做了三件事
- 创建ContextImpl对象
- 创建Application对象, 该对象名来自于mApplicationInfo.className.
- 重写了R常量
扫个盲
//ZygoteInit.main()
public static void main(String argv[]) {
try {
runSelectLoop(abiList);
....
} catch (MethodAndArgsCaller caller) {
caller.run();
} catch (RuntimeException ex) {
closeServerSocket();
throw ex;
}
}
我们昨天一开始就执行这段代码，这段代码最终又跑去子进程的这段代码中caller.run();所以故事发生在主线程
1. ActivityThread.main()
public static void main(String[] args) {
//性能统计默认是关闭的
SamplingProfilerIntegration.start();
//将当前进程所在userId赋值给sCurrentUser
Environment.initForCurrentUser();
EventLogger.setReporter(new EventLoggingReporter());
AndroidKeyStoreProvider.install();
//确保可信任的CA证书存放在正确的位置
final File configDir = Environment.getUserConfigDirectory(UserHandle.myUserId());
TrustedCertificateStore.setDefaultUserDirectory(configDir);
Process.setArgV0("<pre-initialized>");
//创建主线程的Looper对象, 该Looper是不运行退出
Looper.prepareMainLooper();
//创建ActivityThread对象
ActivityThread thread = new ActivityThread();
//建立Binder通道
thread.attach(false);//[2]
if (sMainThreadHandler == null) {
sMainThreadHandler = thread.getHandler();
}
// 当设置为true时，可打开消息队列的debug log信息
if (false) {
Looper.myLooper().setMessageLogging(new LogPrinter(Log.DEBUG, "ActivityThread"));
}
Looper.loop(); //消息循环运行
throw new RuntimeException("Main thread loop unexpectedly exited");
}
这里注意事项：
ActivityThread还有一个地方可以创建就是在：
SystemServer.run()
createSystemContext()
ActivityThread.systemMain()
ActivityThread thread = new ActivityThread();
thread.attach(true);//这里是true
小节上面：
- 创建主线程的Looper对象, 该Looper是不运行退出
- 创建ActivityThread对象
我们还要注意，在创建AT中发生了什么：
- 创建了ResourcesManager对象
ActivityThread() {
mResourcesManager = ResourcesManager.getInstance();
}
- 成员变量中创建了
ApplicationThread mAppThread = new ApplicationThread(); -
H mH = new H();给主线程发送消息的Handler对象
2. ActivityThread.attach()
ActivityThread.java
//这里system=false
private void attach(boolean system) {
sCurrentActivityThread = this;
mSystemThread = system;
if (!system) {
//开启虚拟机的jit即时编译功能
ViewRootImpl.addFirstDrawHandler(new Runnable() {
@Override
public void run() {
ensureJitEnabled();
}
});
android.ddm.DdmHandleAppName.setAppName("<pre-initialized>", UserHandle.myUserId());
RuntimeInit.setApplicationObject(mAppThread.asBinder());
//创建ActivityManagerProxy对象
final IActivityManager mgr = ActivityManagerNative.getDefault();
try {
//调用基于IActivityManager接口的Binder通道
mgr.attachApplication(mAppThread);//[3]
} catch (RemoteException ex) {
}
//观察是否快接近heap的上限
BinderInternal.addGcWatcher(new Runnable() {
@Override public void run() {
if (!mSomeActivitiesChanged) {
return;
}
Runtime runtime = Runtime.getRuntime();
long dalvikMax = runtime.maxMemory();
long dalvikUsed = runtime.totalMemory() - runtime.freeMemory();
if (dalvikUsed > ((3*dalvikMax)/4)) {
mSomeActivitiesChanged = false;
try {
//当已用内存超过最大内存的3/4,则请求释放内存空间
mgr.releaseSomeActivities(mAppThread);
} catch (RemoteException e) {
}
}
}
});
} else {
...
}
//添加dropbox日志到libcore
DropBox.setReporter(new DropBoxReporter());
//添加Config回调接口
ViewRootImpl.addConfigCallback(new ComponentCallbacks2() {
@Override
public void onConfigurationChanged(Configuration newConfig) {
synchronized (mResourcesManager) {
if (mResourcesManager.applyConfigurationToResourcesLocked(newConfig, null)) {
if (mPendingConfiguration == null ||
mPendingConfiguration.isOtherSeqNewer(newConfig)) {
mPendingConfiguration = newConfig;
sendMessage(H.CONFIGURATION_CHANGED, newConfig);
}
}
}
}
@Override
public void onLowMemory() {
}
@Override
public void onTrimMemory(int level) {
}
});
}
这里做的事情：
- ensureJitEnabled();具体是啥不知道
-
android.ddm.DdmHandleAppName.setAppName("<pre-initialized>",UserHandle.myUserId());设置进程名 - 创建AMP
- 给AMP绑定ApplicationThread对象
- 看app进程内存情况，如果太大则释放内存
- 给ViewRootImpl添加一个config的回调接口
这里需要注意：
final IActivityManager mgr = ActivityManagerNative.getDefault();
static public IActivityManager getDefault() {
return gDefault.get();
}
这里得到的Service是activity,activity是在SystemServer中通过AMS.setSystemProcess()中添加的服务，对应AMS
private static final Singleton<IActivityManager> gDefault = new Singleton<IActivityManager>() {
protected IActivityManager create() {
IBinder b = ServiceManager.getService("activity");
if (false) {
Log.v("ActivityManager", "default service binder = " + b);
}
IActivityManager am = asInterface(b);
if (false) {
Log.v("ActivityManager", "default service = " + am);
}
return am;
}
};
3. AMS.attachApplication()
ActivityManagerService.java
在这里我们把握一个核心，这里子进程已经通过Binder调用到了AMS所在进程，也就是system_server进程了
private final boolean attachApplicationLocked(IApplicationThread thread,
int pid) {//此pid是调用者的pid
ProcessRecord app;
if (pid != MY_PID && pid >= 0) {
synchronized (mPidsSelfLocked) {
app = mPidsSelfLocked.get(pid); // 根据pid获取ProcessRecord对象
}
} else {
app = null;
}
if (app == null) {
if (pid > 0 && pid != MY_PID) {
//ProcessRecord为空，则杀掉该进程
Process.killProcessQuiet(pid);
} else {
//退出新建进程的Looper
thread.scheduleExit();
}
return false;
}
//还刚进入attach过程,此时thread应该为null,若不为null则表示该app附到上一个进程，则立刻清空
if (app.thread != null) {
handleAppDiedLocked(app, true, true);
}
final String processName = app.processName;
try {
//绑定死亡通知，注意这里是ApplicationThread的代理对象要linkToDeath
//也就是如果ApplicationThread（继承Binder）挂掉了在AppDeathRecipient中可以接收到信息
AppDeathRecipient adr = new AppDeathRecipient(app, pid, thread);
thread.asBinder().linkToDeath(adr, 0);
app.deathRecipient = adr;
} catch (RemoteException e) {
app.resetPackageList(mProcessStats);
startProcessLocked(app, "link fail", processName); //重新启动进程
return false;
}
//重置进程信息
app.makeActive(thread, mProcessStats); //执行完该语句,则app.thread便不再为空
app.curAdj = app.setAdj = -100;
app.curSchedGroup = app.setSchedGroup = Process.THREAD_GROUP_DEFAULT;
app.forcingToForeground = null;
updateProcessForegroundLocked(app, false, false);
app.hasShownUi = false;
app.debugging = false;
app.cached = false;
app.killedByAm = false;
mHandler.removeMessages(PROC_START_TIMEOUT_MSG, app); //移除进程启动超时的消息，这里超时是在AMS启动进程时候加上去的，所以这里一旦启动就要移除
//系统处于ready状态或者该app为FLAG_PERSISTENT进程,则为true
boolean normalMode = mProcessesReady || isAllowedWhileBooting(app.info);
List<ProviderInfo> providers = normalMode ? generateApplicationProvidersLocked(app) : null;
//app进程存在正在启动中的provider,则超时10s后发送CONTENT_PROVIDER_PUBLISH_TIMEOUT_MSG消息
//这里已经开始provider的操作了
if (providers != null && checkAppInLaunchingProvidersLocked(app)) {
Message msg = mHandler.obtainMessage(CONTENT_PROVIDER_PUBLISH_TIMEOUT_MSG);
msg.obj = app;
mHandler.sendMessageDelayed(msg, CONTENT_PROVIDER_PUBLISH_TIMEOUT);
}
try {
...
//获取应用appInfo
ApplicationInfo appInfo = app.instrumentationInfo != null
? app.instrumentationInfo : app.info;
...
// 绑定应用[4]
thread.bindApplication(processName, appInfo, providers, app.instrumentationClass,
profilerInfo, app.instrumentationArguments, app.instrumentationWatcher,
app.instrumentationUiAutomationConnection, testMode, enableOpenGlTrace,
isRestrictedBackupMode || !normalMode, app.persistent,
new Configuration(mConfiguration), app.compat,
getCommonServicesLocked(app.isolated),
mCoreSettingsObserver.getCoreSettingsLocked());
//更新进程LRU队列
updateLruProcessLocked(app, false, null);
app.lastRequestedGc = app.lastLowMemory = SystemClock.uptimeMillis();
} catch (Exception e) {
app.resetPackageList(mProcessStats);
app.unlinkDeathRecipient();
//每当bind操作失败,则重启启动进程, 此处有可能会导致进程无限重启
startProcessLocked(app, "bind fail", processName);
return false;
}
mPersistentStartingProcesses.remove(app);
mProcessesOnHold.remove(app);
boolean badApp = false;
boolean didSomething = false;
//Activity: 检查最顶层可见的Activity是否等待在该进程中运行
if (normalMode) {
try {
if (mStackSupervisor.attachApplicationLocked(app)) {
didSomething = true;
}
} catch (Exception e) {
badApp = true;
}
}
//Service: 寻找所有需要在该进程中运行的服务
if (!badApp) {
try {
didSomething |= mServices.attachApplicationLocked(app, processName);
} catch (Exception e) {
badApp = true;
}
}
//Broadcast: 检查是否在这个进程中有下一个广播接收者
if (!badApp && isPendingBroadcastProcessLocked(pid)) {
try {
didSomething |= sendPendingBroadcastsLocked(app);
} catch (Exception e) {
badApp = true;
}
}
//检查是否在这个进程中有下一个backup代理
if (!badApp && mBackupTarget != null && mBackupTarget.appInfo.uid == app.uid) {
ensurePackageDexOpt(mBackupTarget.appInfo.packageName);
try {
thread.scheduleCreateBackupAgent(mBackupTarget.appInfo,
compatibilityInfoForPackageLocked(mBackupTarget.appInfo),
mBackupTarget.backupMode);
} catch (Exception e) {
badApp = true;
}
}
if (badApp) { //杀掉bad应用
app.kill("error during init", true);
handleAppDiedLocked(app, false, true);
return false;
}
if (!didSomething) {
updateOomAdjLocked(); //更新adj的值
}
return true;
}
我们这里必须小节一下：
- 设置代表该应用进程的ProcessRecord对象的一些成员变量
- 初步设置oo_adj的值，这个是进程优先级核心
- 撤销PROC_START+TIMEOUT_MSG对应操作
- 调用ApplicationThread的binderApplication
- 通知应用进程启动Acivity，Service等组件其中用于启动activity的函数是realStartActivityLocked
4. ApplicationThread.bindApplication()
我们通过APP所在进程，然后通过binder跨到AMS，通过AMS做一些处理之后，然后又调用到APP的进程中保存一些AMS处理过后的信息
public final void bindApplication(String processName, ApplicationInfo appInfo,
List<ProviderInfo> providers, ComponentName instrumentationName,
ProfilerInfo profilerInfo, Bundle instrumentationArgs,
IInstrumentationWatcher instrumentationWatcher,
IUiAutomationConnection instrumentationUiConnection, int debugMode,
boolean enableBinderTracking, boolean trackAllocation,
boolean isRestrictedBackupMode, boolean persistent, Configuration config,
CompatibilityInfo compatInfo, Map<String, IBinder> services, Bundle coreSettings) {
if (services != null) {
//保存AMS传递来系统service的信息
ServiceManager.initServiceCache(services);
}
setCoreSettings(coreSettings);//给主线程发消息H.SET_CORE_SETTINGS保存coreSettings的值
AppBindData data = new AppBindData();//存储变量的
data.processName = processName;
data.appInfo = appInfo;
data.providers = providers;
data.instrumentationName = instrumentationName;
data.instrumentationArgs = instrumentationArgs;
data.instrumentationWatcher = instrumentationWatcher;
data.instrumentationUiAutomationConnection = instrumentationUiConnection;
data.debugMode = debugMode;
data.enableBinderTracking = enableBinderTracking;
data.trackAllocation = trackAllocation;
data.restrictedBackupMode = isRestrictedBackupMode;
data.persistent = persistent;
data.config = config;
data.compatInfo = compatInfo;
data.initProfilerInfo = profilerInfo;
sendMessage(H.BIND_APPLICATION, data);//[5]给主线程发送消息BIND_APPLICATION，将data传递过去
}
其中setCoreSettings(coreSettings);这一句也很重要
private void handleSetCoreSettings(Bundle coreSettings) {
synchronized (mResourcesManager) {
mCoreSettings = coreSettings;
}
onCoreSettingsChange();
}
private void onCoreSettingsChange() {
boolean debugViewAttributes = mCoreSettings.getInt(Settings.Global.DEBUG_VIEW_ATTRIBUTES, 0) != 0;
if (debugViewAttributes != View.mDebugViewAttributes) {
View.mDebugViewAttributes = debugViewAttributes;
// 由于发生改变, 请求所有的activities重启启动
for (Map.Entry<IBinder, ActivityClientRecord> entry : mActivities.entrySet()) {
requestRelaunchActivity(entry.getKey(), null, null, 0, false, null, null, false);
}
}
}
5. ActivityThread.handleBindApplication(data);
private void handleBindApplication(AppBindData data) {
mBoundApplication = data;
mConfiguration = new Configuration(data.config);
mCompatConfiguration = new Configuration(data.config);
...
//设置进程名, 也就是说进程名是在进程真正创建以后的BIND_APPLICATION过程中才取名，前面那个名字不算
Process.setArgV0(data.processName);
android.ddm.DdmHandleAppName.setAppName(data.processName, UserHandle.myUserId());
if (data.persistent) {
//低内存设备, persistent进程不采用硬件加速绘制,以节省内存使用量
if (!ActivityManager.isHighEndGfx()) {
HardwareRenderer.disable(false);
}
}
//重置时区
TimeZone.setDefault(null);
Locale.setDefault(data.config.locale);
//更新系统配置
mResourcesManager.applyConfigurationToResourcesLocked(data.config, data.compatInfo);
mCurDefaultDisplayDpi = data.config.densityDpi;
applyCompatConfiguration(mCurDefaultDisplayDpi);
//获取LoadedApk对象[5.1]
data.info = getPackageInfoNoCheck(data.appInfo, data.compatInfo);
...
// 创建ContextImpl上下文
final ContextImpl appContext = ContextImpl.createAppContext(this, data.info);
if (!Process.isIsolated()) {
final File cacheDir = appContext.getCacheDir();
if (cacheDir != null) {
System.setProperty("java.io.tmpdir", cacheDir.getAbsolutePath());
}
//用于存储产生/编译的图形代码
final File codeCacheDir = appContext.getCodeCacheDir();
if (codeCacheDir != null) {
setupGraphicsSupport(data.info, codeCacheDir);
}
}
...
//当处于调试模式,则运行应用生成systrace信息
boolean appTracingAllowed = (data.appInfo.flags&ApplicationInfo.FLAG_DEBUGGABLE) != 0;
Trace.setAppTracingAllowed(appTracingAllowed);
//初始化 默认的http代理
IBinder b = ServiceManager.getService(Context.CONNECTIVITY_SERVICE);
if (b != null) {
IConnectivityManager service = IConnectivityManager.Stub.asInterface(b);
final ProxyInfo proxyInfo = service.getProxyForNetwork(null);
Proxy.setHttpProxySystemProperty(proxyInfo);
}
if (data.instrumentationName != null) {
...
} else {
mInstrumentation = new Instrumentation();
}
//FLAG_LARGE_HEAP则清除内存增长上限
if ((data.appInfo.flags&ApplicationInfo.FLAG_LARGE_HEAP) != 0) {
dalvik.system.VMRuntime.getRuntime().clearGrowthLimit();
} else {
dalvik.system.VMRuntime.getRuntime().clampGrowthLimit();
}
try {
// 此处data.info是指LoadedApk, 通过反射创建目标应用Application对象[5.2]
Application app = data.info.makeApplication(data.restrictedBackupMode, null);
mInitialApplication = app;
if (!data.restrictedBackupMode) {
List<ProviderInfo> providers = data.providers;
if (providers != null) {
installContentProviders(app, providers);
mH.sendEmptyMessageDelayed(H.ENABLE_JIT, 10*1000);
}
}
mInstrumentation.onCreate(data.instrumentationArgs);
//调用Application.onCreate()回调方法.
mInstrumentation.callApplicationOnCreate(app);
} finally {
StrictMode.setThreadPolicy(savedPolicy);
}
}
小节：
- 创建一个Application对象，该对象是本进程中运行的第一个Application，是通过指LoadedApk
- 如果该Application有ContentProvider则应该安装他们
在这里就开始创建ContentProvider了，所以ContentProvider的创建比其他组件要早。
5.1 ActivityThread.getPackageInfoNoCheck()
public final LoadedApk getPackageInfoNoCheck(ApplicationInfo ai,
CompatibilityInfo compatInfo) {
return getPackageInfo(ai, compatInfo, null, false, true, false);
}
private LoadedApk getPackageInfo(ApplicationInfo aInfo, CompatibilityInfo compatInfo,
ClassLoader baseLoader, boolean securityViolation, boolean includeCode,
boolean registerPackage) {
final boolean differentUser = (UserHandle.myUserId() != UserHandle.getUserId(aInfo.uid));
synchronized (mResourcesManager) {
WeakReference<LoadedApk> ref;
if (differentUser) {
// Caching not supported across users
ref = null;
} else if (includeCode) {
ref = mPackages.get(aInfo.packageName);
} else {
ref = mResourcePackages.get(aInfo.packageName);
}
LoadedApk packageInfo = ref != null ? ref.get() : null;
if (packageInfo == null || (packageInfo.mResources != null
&& !packageInfo.mResources.getAssets().isUpToDate())) {
packageInfo =
new LoadedApk(this, aInfo, compatInfo, baseLoader,
securityViolation, includeCode &&
(aInfo.flags&ApplicationInfo.FLAG_HAS_CODE) != 0, registerPackage);
if (mSystemThread && "android".equals(aInfo.packageName)) {
packageInfo.installSystemApplicationInfo(aInfo,
getSystemContext().mPackageInfo.getClassLoader());
}
if (differentUser) {
// Caching not supported across users
} else if (includeCode) {
mPackages.put(aInfo.packageName,
new WeakReference<LoadedApk>(packageInfo));
} else {
mResourcePackages.put(aInfo.packageName,
new WeakReference<LoadedApk>(packageInfo));
}
}
return packageInfo;
}
}
5.1做的事情主要就是创建了LoadedApk然后返回
5.2 LoadedApk.makeApplication()
public Application makeApplication(boolean forceDefaultAppClass,
Instrumentation instrumentation) {
if (mApplication != null) {
return mApplication;
}
Application app = null;
String appClass = mApplicationInfo.className;
if (forceDefaultAppClass || (appClass == null)) {
appClass = "android.app.Application";//默认在这里
}
try {
java.lang.ClassLoader cl = getClassLoader();
if (!mPackageName.equals("android")) {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER,
"initializeJavaContextClassLoader");
initializeJavaContextClassLoader();
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
}
ContextImpl appContext = ContextImpl.createAppContext(mActivityThread, this);//创建ContextImpl对象
//创建Application对象, 该对象名来自于mApplicationInfo.className.
app = mActivityThread.mInstrumentation.newApplication(
cl, appClass, appContext);
appContext.setOuterContext(app);
} catch (Exception e) {
...
}
mActivityThread.mAllApplications.add(app);
mApplication = app;
if (instrumentation != null) {
try {
instrumentation.callApplicationOnCreate(app);
} catch (Exception e) {
...
}
}
// Rewrite the R 'constants' for all library apks.
SparseArray<String> packageIdentifiers = getAssets(mActivityThread)
.getAssignedPackageIdentifiers();
final int N = packageIdentifiers.size();
for (int i = 0; i < N; i++) {
final int id = packageIdentifiers.keyAt(i);
if (id == 0x01 || id == 0x7f) {
continue;
}
//写R常量
rewriteRValues(getClassLoader(), packageIdentifiers.valueAt(i), id);
}
return app;
}
主要做了三件事
- 创建ContextImpl对象
- 创建Application对象, 该对象名来自于mApplicationInfo.className.
- 重写了R常量
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