[Android5.1]ActivityManagerService启动过程分析
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ActivityManagerService(简称AMS)是android系统的关键服务之一。它的主要作用如下:
- 管理系统中所有应用进程的整个生命周期
- 管理应用进程中的Activity、Service、Broadcast和ContentProvider
- 内存管理,低内存释放等
AMS是一个服务端,定义了IBinder接口,其他的进程可以通过Binder机制与AMS进行通信。
AMS由system_server进程启动的,并作为一个独立线程运行在system_server进程中。
下面就简略分析一下AMS的启动过程
system_server启动AMS
PATH:frameworks/base/services/java/com/android/server/SystemServer.java
启动过程大致如下:
SystemServer.main()–>SystemServer.run()。
private void run()
......
startBootstrapServices();
startOtherServices();
......
private void startBootstrapServices()
......
// 启动AMS服务
mActivityManagerService = mSystemServiceManager.startService(
ActivityManagerService.Lifecycle.class).getService();
// 初始化AMS的成员变量mSystemServiceManager
mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
// 初始化AMS的成员变量mInstaller
mActivityManagerService.setInstaller(installer);
......
// 主要是创建system_server对应的ProcessRecord,并初始化
mActivityManagerService.setSystemProcess();
......
private void startOtherServices()
......
// 主要是创建并注册SettingsProvider
mActivityManagerService.installSystemProviders();
......
// 系统启动前的准备工作,启动SystemUI和Home界面等
mActivityManagerService.systemReady(new Runnable() ...);
重点看一下mSystemServiceManager.startService():
public SystemService startService(String className)
final Class<SystemService> serviceClass;
try
serviceClass = (Class<SystemService>)Class.forName(className);
catch (ClassNotFoundException ex)
......
return startService(serviceClass);
public <T extends SystemService> T startService(Class<T> serviceClass)
final String name = serviceClass.getName();
Slog.i(TAG, "Starting " + name);
// Create the service.
if (!SystemService.class.isAssignableFrom(serviceClass))
throw new RuntimeException("Failed to create " + name
+ ": service must extend " + SystemService.class.getName());
final T service;
try
Constructor<T> constructor = serviceClass.getConstructor(Context.class);
//创建ActivityManagerService.Lifecycle对象
service = constructor.newInstance(mContext);
catch (InstantiationException ex)
......
// 添加到成员变量mServices中
mServices.add(service);
// Start it.
try
// 执行ActivityManagerService.Lifecycle.onStart()
service.onStart();
catch (RuntimeException ex)
throw new RuntimeException("Failed to start service " + name
+ ": onStart threw an exception", ex);
return service;
ActivityManagerService.Lifecycle
PATH:frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
public static final class Lifecycle extends SystemService
private final ActivityManagerService mService;
public Lifecycle(Context context)
super(context);
// 创建ActivityManagerServiceEx对象
mService = new ActivityManagerServiceEx(context);
@Override
public void onStart()
mService.start(); //执行ActivityManagerServiceEx.start()
public ActivityManagerService getService()
return mService;
其中,ActivityManagerServiceEx是ActivityManagerService的子类,定义如下:
public final class ActivityManagerServiceEx extends ActivityManagerService
......
public ActivityManagerServiceEx(Context systemContext)
super(systemContext);
mIsInHome = true;
......
这样,在new ActivityManagerServiceEx()时候,会调用到其父类ActivityManagerService的构造函数。
ActivityManagerService构造函数
PATH:frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
public ActivityManagerService(Context systemContext)
mContext = systemContext;
mFactoryTest = FactoryTest.getMode();
mSystemThread = ActivityThread.currentActivityThread();
Slog.i(TAG, "Memory class: " + ActivityManager.staticGetMemoryClass());
//创建名称为“ActivityManager”的消息循环线程,
mHandlerThread = new ServiceThread(TAG,
android.os.Process.THREAD_PRIORITY_FOREGROUND, false /*allowIo*/);
mHandlerThread.start();
//将该线程绑定到MainHandler,由MainHandler完成消息的处理
mHandler = new MainHandler(mHandlerThread.getLooper());
//创建前台广播接收器,运行超时为10s
mFgBroadcastQueue = new BroadcastQueue(this, mHandler,
"foreground", BROADCAST_FG_TIMEOUT, false);
//创建后台广播接收器,运行超时为60s
mBgBroadcastQueue = new BroadcastQueue(this, mHandler,
"background", BROADCAST_BG_TIMEOUT, true);
mBroadcastQueues[0] = mFgBroadcastQueue;
mBroadcastQueues[1] = mBgBroadcastQueue;
mServices = new ActiveServicesEx(this);
mProviderMap = new ProviderMap(this);
//新建/data/system目录
File dataDir = Environment.getDataDirectory();
File systemDir = new File(dataDir, "system");
systemDir.mkdirs();
//创建BatteryStatsService服务
mBatteryStatsService = new BatteryStatsService(systemDir, mHandler);
mBatteryStatsService.getActiveStatistics().readLocked();
mBatteryStatsService.getActiveStatistics().writeAsyncLocked();
mOnBattery = DEBUG_POWER ? true
: mBatteryStatsService.getActiveStatistics().getIsOnBattery();
mBatteryStatsService.getActiveStatistics().setCallback(this);
//创建ProcessStatsService服务
mProcessStats = new ProcessStatsService(this, new File(systemDir, "procstats"));
//创建AppOpsService服务
mAppOpsService = new AppOpsService(new File(systemDir, "appops.xml"), mHandler);
//创建AtomicFile文件
mGrantFile = new AtomicFile(new File(systemDir, "urigrants.xml"));
// User 0 is the first and only user that runs at boot.
mStartedUsers.put(0, new UserStartedState(new UserHandle(0), true));
mUserLru.add(Integer.valueOf(0));
updateStartedUserArrayLocked();
GL_ES_VERSION = SystemProperties.getInt("ro.opengles.version",
ConfigurationInfo.GL_ES_VERSION_UNDEFINED);
mTrackingAssociations = "1".equals(SystemProperties.get("debug.track-associations"));
mConfiguration.setToDefaults();
mConfiguration.locale = Locale.getDefault();
mConfigurationSeq = mConfiguration.seq = 1;
mProcessCpuTracker.init();
mCompatModePackages = new CompatModePackages(this, systemDir, mHandler);
mIntentFirewall = new IntentFirewall(new IntentFirewallInterface(), mHandler);
mStackSupervisor = new ActivityStackSupervisor(this);
mTaskPersister = new TaskPersister(systemDir, mStackSupervisor);
mProcessCpuThread = new Thread("CpuTracker")
@Override
public void run()
while (true)
try
try
synchronized(this)
final long now = SystemClock.uptimeMillis();
long nextCpuDelay = (mLastCpuTime.get()+MONITOR_CPU_MAX_TIME)-now;
long nextWriteDelay = (mLastWriteTime+BATTERY_STATS_TIME)-now;
//Slog.i(TAG, "Cpu delay=" + nextCpuDelay
// + ", write delay=" + nextWriteDelay);
if (nextWriteDelay < nextCpuDelay)
nextCpuDelay = nextWriteDelay;
if (nextCpuDelay > 0)
mProcessCpuMutexFree.set(true);
this.wait(nextCpuDelay);
catch (InterruptedException e)
updateCpuStatsNow();
catch (Exception e)
Slog.e(TAG, "Unexpected exception collecting process stats", e);
;
Watchdog.getInstance().addMonitor(this);
Watchdog.getInstance().addThread(mHandler);
首先,创建了一个名为“ActivityManager”的消息循环线程,不断地接收其他进程发给AMS的消息;并把该消息循环线程与MainHandler绑定,这样,由MainHandler完成消息的具体处理。
然后,创建了一些服务,并在/data/system目录下创建该服务需要的文件或文件夹,具体如下:
服务 | 服务说明 | 文件 | 文件说明 |
---|---|---|---|
BatteryStatsService | 电池状态管理 | /data/system/batterystats.bin | 记录包括电压在内的各种电池信息 |
ProcessStatsService | 进程状态管理 | /data/system/procstats | 记录各个进程的状态信息 |
AppOpsService | 应用操作权限管理 | /data/system/appops.xml | 存储各个app的权限设置和操作信息 |
另外,还创建了一个AtomicFile类型的文件mGrantFile ,文件路径为/data/system/urigrants.xml。
AtomicFile文件是通过创建一个备份文件来执行原子性操作的帮助类,保证文件读写的完整。
这样,system_server就完成AMS的构造和启动。
回到system_server中,我们看到又调用了AMS的setSystemProcess方法,下面就分析一下该方法。
ActivityManagerService.setSystemProcess
public void setSystemProcess()
try
ServiceManager.addService(Context.ACTIVITY_SERVICE, this, true);
ServiceManager.addService(ProcessStats.SERVICE_NAME, mProcessStats);
ServiceManager.addService("meminfo", new MemBinder(this));
ServiceManager.addService("gfxinfo", new GraphicsBinder(this));
ServiceManager.addService("dbinfo", new DbBinder(this));
if (MONITOR_CPU_USAGE)
ServiceManager.addService("cpuinfo", new CpuBinder(this));
ServiceManager.addService("permission", new PermissionController(this));
ApplicationInfo info = mContext.getPackageManager().getApplicationInfo(
"android", STOCK_PM_FLAGS);
mSystemThread.installSystemApplicationInfo(info, getClass().getClassLoader());
synchronized (this)
ProcessRecord app = newProcessRecordLocked(info, info.processName, false, 0);
app.persistent = true;
app.pid = MY_PID;
app.maxAdj = ProcessList.SYSTEM_ADJ;
app.makeActive(mSystemThread.getApplicationThread(), mProcessStats);
mProcessNames.put(app.processName, app.uid, app);
synchronized (mPidsSelfLocked)
mPidsSelfLocked.put(app.pid, app);
updateLruProcessLocked(app, false, null);
updateOomAdjLocked();
catch (PackageManager.NameNotFoundException e)
throw new RuntimeException(
"Unable to find android system package", e);
首先,向SystemServiceManager中添加了若干个服务:
服务 | 服务说明 |
---|---|
activity | AMS服务本身 |
procstats | 进程状态管理 |
meminfo | 获取内存信息 |
gfxinfo | 监控分析GPU profiling信息 |
dbinfo | 数据库相关服务 |
cpuinfo | 获取cpu相关信息 |
permission | 权限控制相关服务 |
然后,调用PMS的getApplicationInfo接口,获取名为”android”的应用程序信息。包名为”android”的apk即/system/framework/framework-res.apk,里面保存着系统GUI美化的相关文件,包括图标,弹出对话框的样式,动作特效,界面布局等。调用installSystemApplicationInfo加载framework-res.apk文件。
接着,调用newProcessRecordLocked新建一个ProcessRecord 对象app。ProcessRecord用来描述一个进程的所有信息,包括该进程的所有activity和service等。在这里就是system_server(AMS就是在system_server进程中运行的)。创建后,对app的一些成员变量进行初始化,包括设置为常驻内存运行;设置system_server的pid等。
最后,调用mProcessNames.put()将创建的ProcessRecord 对象app加入到ProcessMap< ProcessRecord >类型的成员变量mProcessNames中。这里,app.processName=“system”。
这样,AMS就得到了system_server的ProcessRecord,以后AMS也可以管理system_server了。
继续回到system_server中,我们看到又调用了AMS的installSystemProviders方法,下面就分析一下该方法。
ActivityManagerService.installSystemProviders
public final void installSystemProviders()
List<ProviderInfo> providers;
synchronized (this)
ProcessRecord app = mProcessNames.get("system", Process.SYSTEM_UID);
providers = generateApplicationProvidersLocked(app);
if (providers != null)
for (int i=providers.size()-1; i>=0; i--)
ProviderInfo pi = (ProviderInfo)providers.get(i);
if ((pi.applicationInfo.flags&ApplicationInfo.FLAG_SYSTEM) == 0)
Slog.w(TAG, "Not installing system proc provider " + pi.name
+ ": not system .apk");
providers.remove(i);
if (providers != null)
mSystemThread.installSystemProviders(providers);
mCoreSettingsObserver = new CoreSettingsObserver(this);
//mUsageStatsService.monitorPackages();
首先,取出在setSystemProcess()中put到mProcessNames中的ProcessRecord对象app,即system_server的进程信息。
然后,调用generateApplicationProvidersLocked:
private final List<ProviderInfo> generateApplicationProvidersLocked(ProcessRecord app)
List<ProviderInfo> providers = null;
try
providers = AppGlobals.getPackageManager().
queryContentProviders(app.processName, app.uid,
STOCK_PM_FLAGS | PackageManager.GET_URI_PERMISSION_PATTERNS);
catch (RemoteException ex)
if (DEBUG_MU)
Slog.v(TAG_MU, "generateApplicationProvidersLocked, app.info.uid = " + app.uid);
int userId = app.userId;
if (providers != null)
int N = providers.size();
app.pubProviders.ensureCapacity(N + app.pubProviders.size());
for (int i=0; i<N; i++)
ProviderInfo cpi =
(ProviderInfo)providers.get(i);
boolean singleton = isSingleton(cpi.processName, cpi.applicationInfo,
cpi.name, cpi.flags);
if (singleton && UserHandle.getUserId(app.uid) != 0)
providers.remove(i);
N--;
i--;
continue;
ComponentName comp = new ComponentName(cpi.packageName, cpi.name);
ContentProviderRecord cpr = mProviderMap.getProviderByClass(comp, userId);
if (cpr == null)
cpr = new ContentProviderRecord(this, cpi, app.info, comp, singleton);
mProviderMap.putProviderByClass(comp, cpr);
if (DEBUG_MU)
Slog.v(TAG_MU, "generateApplicationProvidersLocked, cpi.uid = " + cpr.uid);
app.pubProviders.put(cpi.name, cpr);
if (!cpi.multiprocess || !"android".equals(cpi.packageName))
app.addPackage(cpi.applicationInfo.packageName, cpi.applicationInfo.versionCode,
mProcessStats);
ensurePackageDexOpt(cpi.applicationInfo.packageName);
return providers;
首先,调用PMS的queryContentProviders查找processName=“system”和uid=SYSTEM_UID的provider,即SettingsProvider,并获取其ProviderInfo 。
然后新建一个ContentProviderRecord(描述一个ContentProvider,这里为SettingsProvider),并添加到AMS的成员变量mProviderMap和ProcessRecord对象的pubProviders中。
最后将SettingsProvider所在的package加入到ProcessRecord对象的pkglist中。
继续回到installSystemProviders(),调用installSystemProviders,先创建后注册SettingsProvider。这样,其他进程就可以调用SettingsProvider,查询或修改一些系统设置了。
在installSystemProviders()的最后,注册一个ContentObserver来监听SettingsProvider中的状态变化。
继续回到system_server中,我们看到又调用了AMS的systemReady方法,下面就分析一下该方法。
ActivityManagerService.systemReady
该函数主要完成了以下几件事:
- 在当前运行的进程中,查找在systemReady之前不允许启动的进程,然后调用removeProcessLocked()终止该进程并释放资源。判断条件如下:
boolean isAllowedWhileBooting(ApplicationInfo ai)
return (ai.flags&ApplicationInfo.FLAG_PERSISTENT) != 0;
- 加载若干配置信息和资源信息,代码如下:
retrieveSettings();
loadResourcesOnSystemReady();
private void retrieveSettings()
final ContentResolver resolver = mContext.getContentResolver();
String debugApp = Settings.Global.getString(
resolver, Settings.Global.DEBUG_APP);
boolean waitForDebugger = Settings.Global.getInt(
resolver, Settings.Global.WAIT_FOR_DEBUGGER, 0) != 0;
boolean alwaysFinishActivities = Settings.Global.getInt(
resolver, Settings.Global.ALWAYS_FINISH_ACTIVITIES, 0) != 0;
boolean forceRtl = Settings.Global.getInt(
resolver, Settings.Global.DEVELOPMENT_FORCE_RTL, 0) != 0;
......
private void loadResourcesOnSystemReady()
final Resources res = mContext.getResources();
mHasRecents = res.getBoolean(com.android.internal.R.bool.config_hasRecents);
mThumbnailWidth = res.getDimensionPixelSize(com.android.internal.R.dimen.thumbnail_width);
mThumbnailHeight = res.getDimensionPixelSize(com.android.internal.R.dimen.thumbnail_height);
- 调用回调函数goingCallback.run(),主要完成两件事:执行其他系统服务的systemready()或systemRunning();启动SystemUI。
goingCallback.run()的实现在systemserver.java中:
mActivityManagerService.systemReady(new Runnable()
@Override
public void run()
Slog.i(TAG, "Making services ready");
mSystemServiceManager.startBootPhase(
SystemService.PHASE_ACTIVITY_MANAGER_READY);
try
mActivityManagerService.startObservingNativeCrashes();
catch (Throwable e)
reportWtf("observing native crashes", e);
Slog.i(TAG, "WebViewFactory preparation");
WebViewFactory.prepareWebViewInSystemServer();
try
startSystemUi(context); //启动SystemUI
catch (Throwable e)
reportWtf("starting System UI", e);
try
if (mountServiceF != null) mountServiceF.systemReady();
catch (Throwable e)
reportWtf("making Mount Service ready", e);
try
if (networkScoreF != null) networkScoreF.systemReady();
catch (Throwable e)
reportWtf("making Network Score Service ready", e);
try
if (networkManagementF != null) networkManagementF.systemReady();
catch (Throwable e)
reportWtf("making Network Managment Service ready", e);
try
if (networkStatsF != null) networkStatsF.systemReady();
catch (Throwable e)
reportWtf("making Network Stats Service ready", e);
try
if (networkPolicyF != null) networkPolicyF.systemReady();
catch (Throwable e)
reportWtf("making Network Policy Service ready", e);
try
if (connectivityF != null) connectivityF.systemReady();
catch (Throwable e)
reportWtf("making Connectivity Service ready", e);
try
if (audioserviceF != null) audioServiceF.systemReady();
catch (Throwable e)
reportWtf("Notifying AudioService running", e);
Watchdog.getInstance().start();
// It is now okay to let the various system services start their
// third party code...
mSystemServiceManager.startBootPhase(
SystemService.PHASE_THIRD_PARTY_APPS_CAN_START);
try
if (wallpaperF != null) wallpaperF.systemRunning();
catch (Throwable e)
reportWtf("Notifying WallpaperService running", e);
try
if (immF != null) immF.systemRunning(statusBarF);
catch (Throwable e)
reportWtf("Notifying InputMethodService running", e);
try
if (locationF != null) locationF.systemRunning();
catch (Throwable e)
reportWtf("Notifying Location Service running", e);
try
if (countryDetectorF != null) countryDetectorF.systemRunning();
catch (Throwable e)
reportWtf("Notifying CountryDetectorService running", e);
try
if (networkTimeUpdaterF != null) networkTimeUpdaterF.systemRunning();
catch (Throwable e)
reportWtf("Notifying NetworkTimeService running", e);
try
if (commonTimeMgmtServiceF != null)
commonTimeMgmtServiceF.systemRunning();
catch (Throwable e)
reportWtf("Notifying CommonTimeManagementService running", e);
try
if (textServiceManagerServiceF != null)
textServiceManagerServiceF.systemRunning();
catch (Throwable e)
reportWtf("Notifying TextServicesManagerService running", e);
try
if (atlasF != null) atlasF.systemRunning();
catch (Throwable e)
reportWtf("Notifying AssetAtlasService running", e);
try
// TODO(BT) Pass parameter to input manager
if (inputManagerF != null) inputManagerF.systemRunning();
catch (Throwable e)
reportWtf("Notifying InputManagerService running", e);
try
if (telephonyRegistryF != null) telephonyRegistryF.systemRunning();
catch (Throwable e)
reportWtf("Notifying TelephonyRegistry running", e);
try
if (mediaRouterF != null) mediaRouterF.systemRunning();
catch (Throwable e)
reportWtf("Notifying MediaRouterService running", e);
if (SystemProperties.get("persist.support.securetest").equals("1"))
if (securityF != null)
try
securityF.systemReady(context);
catch (Throwable e)
reportWtf("Security Service ready", e);
);
- 调用addAppLocked启动那些声明为“FLAG_SYSTEM|FLAG_PERSISTENT”的应用程序:
final ProcessRecord addAppLocked(ApplicationInfo info, boolean isolated,
String abiOverride)
ProcessRecord app;
if (!isolated)
app = getProcessRecordLocked(info.processName, info.uid, true);
else
......
......
// This package really, really can not be stopped.
try
AppGlobals.getPackageManager().setPackageStoppedState(
info.packageName, false, UserHandle.getUserId(app.uid));
catch (RemoteException e)
catch (IllegalArgumentException e)
Slog.w(TAG, "Failed trying to unstop package "
+ info.packageName + ": " + e);
//判断条件
if ((info.flags&(ApplicationInfo.FLAG_SYSTEM|ApplicationInfo.FLAG_PERSISTENT))
== (ApplicationInfo.FLAG_SYSTEM|ApplicationInfo.FLAG_PERSISTENT))
app.persistent = true;
app.maxAdj = ProcessList.PERSISTENT_PROC_ADJ;
//如果该app的IApplicationThread等于null,并且没有在ArrayList<ProcessRecord>类型
//的成员变量mPersistentStartingProcesses中,
//启动该app,并把它加入到mPersistentStartingProcesses中。
if (app.thread == null && mPersistentStartingProcesses.indexOf(app) < 0)
mPersistentStartingProcesses.add(app);
startProcessLocked(app, "added application", app.processName, abiOverride,
null /* entryPoint */, null /* entryPointArgs */);
return app;
- 广播两个消息:ACTION_USER_STARTED和ACTION_USER_STARTING,标识用户已经started
Intent intent = new Intent(Intent.ACTION_USER_STARTED);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
| Intent.FLAG_RECEIVER_FOREGROUND);
intent.putExtra(Intent.EXTRA_USER_HANDLE, mCurrentUserId);
broadcastIntentLocked(null, null, intent,
null, null, 0, null, null, null, AppOpsManager.OP_NONE,
false, false, MY_PID, Process.SYSTEM_UID, mCurrentUserId);
intent = new Intent(Intent.ACTION_USER_STARTING);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
intent.putExtra(Intent.EXTRA_USER_HANDLE, mCurrentUserId);
broadcastIntentLocked(null, null, intent,
null, new IIntentReceiver.Stub()
@Override
public void performReceive(Intent intent, int resultCode, String data,
Bundle extras, boolean ordered, boolean sticky, int sendingUser)
throws RemoteException
, 0, null, null,
INTERACT_ACROSS_USERS, AppOpsManager.OP_NONE,
true, false, MY_PID, Process.SYSTEM_UID, UserHandle.USER_ALL);
catch (Throwable t)
......
- 调用startHomeActivityLocked()启动HOME界面。
这样,ActivityManagerService的启动和初始化就完成了。
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