上篇在ServerThread.run函數中啓動註冊核心server，這當中就包括AMS
<span style="font-size:14px;"> Slog.i(TAG, "Activity Manager");
context = ActivityManagerService.main(factoryTest);
...
...
...
ActivityManagerService.setSystemProcess();
...
...
Slog.i(TAG, "System Content Providers");
ActivityManagerService.installSystemProviders();
...
// only initialize the power service after we have started the
// lights service, content providers and the battery service.
power.init(context, lights, ActivityManagerService.self(), battery,
BatteryStatsService.getService(), display);
Slog.i(TAG, "Alarm Manager");
alarm = new AlarmManagerService(context);
ServiceManager.addService(Context.ALARM_SERVICE, alarm);
Slog.i(TAG, "Init Watchdog");
Watchdog.getInstance().init(context, battery, power, alarm,
ActivityManagerService.self());
Slog.i(TAG, "Input Manager");
inputManager = new InputManagerService(context, wmHandler);
Slog.i(TAG, "Window Manager");
wm = WindowManagerService.main(context, power, display, inputManager,
uiHandler, wmHandler,
factoryTest != SystemServer.FACTORY_TEST_LOW_LEVEL,
!firstBoot, onlyCore);
ServiceManager.addService(Context.WINDOW_SERVICE, wm);
ServiceManager.addService(Context.INPUT_SERVICE, inputManager);
ActivityManagerService.self().setWindowManager(wm);
...
...
...
// We now tell the activity manager it is okay to run third party
// code. It will call back into us once it has gotten to the state
// where third party code can really run (but before it has actually
// started launching the initial applications), for us to complete our
// initialization.
ActivityManagerService.self().systemReady(new Runnable() {
public void run() {
Slog.i(TAG, "Making services ready");
try {
ActivityManagerService.self().startObservingNativeCrashes();
} catch (Throwable e) {
reportWtf("observing native crashes", e);
}
if (!headless) startSystemUi(contextF);
try {
if (mountServiceF != null) mountServiceF.systemReady();
} catch (Throwable e) {
reportWtf("making Mount Service ready", e);
}
...
...
}
});</span>首先是main函數
<span style="font-size:14px;"> public static final Context main(int factoryTest) {
AThread thr = new AThread();
thr.start();
synchronized (thr) {
while (thr.mService == null) {
try {
thr.wait();
} catch (InterruptedException e) {
}
}
}
ActivityManagerService m = thr.mService;
mSelf = m;
ActivityThread at = ActivityThread.systemMain();
mSystemThread = at;
Context context = at.getSystemContext();
context.setTheme(android.R.style.Theme_Holo);
m.mContext = context;
m.mFactoryTest = factoryTest;
m.mMainStack = new ActivityStack(m, context, true, thr.mLooper);
m.mIntentFirewall = new IntentFirewall(m.new IntentFirewallInterface());
m.mBatteryStatsService.publish(context);
m.mUsageStatsService.publish(context);
m.mAppOpsService.publish(context);
synchronized (thr) {
thr.mReady = true;
thr.notifyAll();
}
m.startRunning(null, null, null, null);
return context;
}</span><span style="font-size:14px;"> static class AThread extends Thread {
ActivityManagerService mService;
Looper mLooper;
boolean mReady = false;
public AThread() {
super("ActivityManager");
}
public void run() {
Looper.prepare();
android.os.Process.setThreadPriority(
android.os.Process.THREAD_PRIORITY_FOREGROUND);
android.os.Process.setCanSelfBackground(false);
ActivityManagerService m = new ActivityManagerService();
synchronized (this) {
mService = m;
mLooper = Looper.myLooper();
notifyAll();
}
synchronized (this) {
while (!mReady) {
try {
wait();
} catch (InterruptedException e) {
}
}
}
// For debug builds, log event loop stalls to dropbox for analysis.
if (StrictMode.conditionallyEnableDebugLogging()) {
Slog.i(TAG, "Enabled StrictMode logging for AThread's Looper");
}
Looper.loop();
}
}</span>AMS的構造函數如下
<span style="font-size:14px;"> private ActivityManagerService() {
Slog.i(TAG, "Memory class: " + ActivityManager.staticGetMemoryClass());
mFgBroadcastQueue = new BroadcastQueue(this, "foreground", BROADCAST_FG_TIMEOUT);
mBgBroadcastQueue = new BroadcastQueue(this, "background", BROADCAST_BG_TIMEOUT);
mBroadcastQueues[0] = mFgBroadcastQueue;
mBroadcastQueues[1] = mBgBroadcastQueue;
mServices = new ActiveServices(this);
mProviderMap = new ProviderMap(this);
//創建/data/system目錄
File dataDir = Environment.getDataDirectory();
File systemDir = new File(dataDir, "system");
systemDir.mkdirs();
//創建BatteryStatsService
mBatteryStatsService = new BatteryStatsService(new File(
systemDir, "batterystats.bin").toString());
mBatteryStatsService.getActiveStatistics().readLocked();
mBatteryStatsService.getActiveStatistics().writeAsyncLocked();
mOnBattery = DEBUG_POWER ? true
: mBatteryStatsService.getActiveStatistics().getIsOnBattery();
mBatteryStatsService.getActiveStatistics().setCallback(this);
//創建UsageStatsService
mUsageStatsService = new UsageStatsService(new File(
systemDir, "usagestats").toString());
mAppOpsService = new AppOpsService(new File(systemDir, "appops.xml"));
mHeadless = "1".equals(SystemProperties.get("ro.config.headless", "0"));
// 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();
//獲取OpenGl版本
GL_ES_VERSION = SystemProperties.getInt("ro.opengles.version",
ConfigurationInfo.GL_ES_VERSION_UNDEFINED);
//字體、語言
mConfiguration.setToDefaults();
mConfiguration.setLocale(Locale.getDefault());
mConfigurationSeq = mConfiguration.seq = 1;
//讀取並解析/proc/state文件，用於統計cpu、內存等信息
mProcessStats.init();
//解析packages-compat.xml文件，用於解決屏幕尺寸的相關問題
mCompatModePackages = new CompatModePackages(this, systemDir);
// Add ourself to the Watchdog monitors.
Watchdog.getInstance().addMonitor(this);
//創建一個新線程用於定時更新系統信息
mProcessStatsThread = new Thread("ProcessStats") {
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) {
mProcessStatsMutexFree.set(true);
this.wait(nextCpuDelay);
}
}
} catch (InterruptedException e) {
}
updateCpuStatsNow();
} catch (Exception e) {
Slog.e(TAG, "Unexpected exception collecting process stats", e);
}
}
}
};
mProcessStatsThread.start();
}</span><span style="font-size:14px;"> synchronized (thr) {
while (thr.mService == null) {
try {
thr.wait();
} catch (InterruptedException e) {
}
}
}
ActivityManagerService m = thr.mService;
mSelf = m;
ActivityThread at = ActivityThread.systemMain();</span>ActivityThread代表應用進程的主線程
<span style="font-size:14px;"> public static ActivityThread systemMain() {
//禁止硬件渲染加速
HardwareRenderer.disable(true);
ActivityThread thread = new ActivityThread();
thread.attach(true);
return thread;
}</span><span style="font-size:14px;"> ActivityThread at = ActivityThread.systemMain();
mSystemThread = at;
Context context = at.getSystemContext();</span><span style="font-size:14px;"> private void attach(boolean system) {
sCurrentActivityThread = this;
mSystemThread = system;
if (!system) {//應用進程的處理
ViewRootImpl.addFirstDrawHandler(new Runnable() {
public void run() {
ensureJitEnabled();
}
});
android.ddm.DdmHandleAppName.setAppName("<pre-initialized>",
UserHandle.myUserId());
RuntimeInit.setApplicationObject(mAppThread.asBinder());
IActivityManager mgr = ActivityManagerNative.getDefault();
try {
mgr.attachApplication(mAppThread);
} catch (RemoteException ex) {
// Ignore
}
} else {//系統進程的處理
// Don't set application object here -- if the system crashes,
// we can't display an alert, we just want to die die die.
android.ddm.DdmHandleAppName.setAppName("system_process",
UserHandle.myUserId());
try {
mInstrumentation = new Instrumentation();
ContextImpl context = new ContextImpl();
context.init(getSystemContext().mPackageInfo, null, this);
Application app = Instrumentation.newApplication(Application.class, context);
mAllApplications.add(app);
mInitialApplication = app;
app.onCreate();
} catch (Exception e) {
throw new RuntimeException(
"Unable to instantiate Application():" + e.toString(), e);
}
}
// add dropbox logging to libcore
DropBox.setReporter(new DropBoxReporter());
...
}</span>Instrumentation，這是一個工具類，系統先創建它，再通過它創建其他組件。系統與組件的交互也通過它來完成。
Application，經常遇到，保存一個全局的application狀態
Context，這實質是一個接口類，獲取和操作Application對應的資源、類以及組件
在上述代碼中，當context進行初始化，也就是init函數，第一個參數爲getSystemContext().mPackageInfo
getSystemContext函數的代碼實現
<span style="font-size:14px;"> public ContextImpl getSystemContext() {
synchronized (this) {
if (mSystemContext == null) {
ContextImpl context =
ContextImpl.createSystemContext(this);
LoadedApk info = new LoadedApk(this, "android", context, null,
CompatibilityInfo.DEFAULT_COMPATIBILITY_INFO);
context.init(info, null, this);
context.getResources().updateConfiguration(
getConfiguration(), getDisplayMetricsLocked(
Display.DEFAULT_DISPLAY,
CompatibilityInfo.DEFAULT_COMPATIBILITY_INFO));
mSystemContext = context;
//Slog.i(TAG, "Created system resources " + context.getResources()
// + ": " + context.getResources().getConfiguration());
}
}
return mSystemContext;
}</span>在attach中創建的是一個與系統資源相關的context，再通過這個context創建一個Application對象實例，所以說，這裏的ActivityThread是system_server的主線程。
所以，我們可知，main函數在這裏爲system_server準備了一個和應用進程一樣的運行環境。
<span style="font-size:14px;"> context.setTheme(android.R.style.Theme_Holo);
m.mContext = context;
m.mFactoryTest = factoryTest;
m.mMainStack = new ActivityStack(m, context, true, thr.mLooper);
m.mIntentFirewall = new IntentFirewall(m.new IntentFirewallInterface());
m.mBatteryStatsService.publish(context);
m.mUsageStatsService.publish(context);
m.mAppOpsService.publish(context);
synchronized (thr) {
thr.mReady = true;
thr.notifyAll();
}</span>然後給AThread一個信號，AThread就可以處理消息循環了。
下面看AMS的startRunning函數，在main的最後調用
<span style="font-size:14px;"> public final void startRunning(String pkg, String cls, String action,
String data) {
synchronized(this) {
if (mStartRunning) {
return;
}
mStartRunning = true;
mTopComponent = pkg != null && cls != null
? new ComponentName(pkg, cls) : null;
mTopAction = action != null ? action : Intent.ACTION_MAIN;
mTopData = data;
if (!mSystemReady) {
return;
}
}
systemReady(null);
}</span>main函數結束後是setSystemProcess
<span style="font-size:14px;"> public static void setSystemProcess() {
try {
ActivityManagerService m = mSelf;
//向ServiceManager註冊服務
ServiceManager.addService("activity", m, true);
ServiceManager.addService("meminfo", new MemBinder(m));
ServiceManager.addService("gfxinfo", new GraphicsBinder(m));
ServiceManager.addService("dbinfo", new DbBinder(m));
if (MONITOR_CPU_USAGE) {
ServiceManager.addService("cpuinfo", new CpuBinder(m));
}
ServiceManager.addService("permission", new PermissionController(m));
ApplicationInfo info =
mSelf.mContext.getPackageManager().getApplicationInfo(
"android", STOCK_PM_FLAGS);
mSystemThread.installSystemApplicationInfo(info);
synchronized (mSelf) {
//ProcessRecord用於AMS對進程的管理
ProcessRecord app = mSelf.newProcessRecordLocked(
mSystemThread.getApplicationThread(), info,
info.processName, false);
app.persistent = true;
app.pid = MY_PID;
app.maxAdj = ProcessList.SYSTEM_ADJ;
mSelf.mProcessNames.put(app.processName, app.uid, app);
synchronized (mSelf.mPidsSelfLocked) {
mSelf.mPidsSelfLocked.put(app.pid, app);
}
mSelf.updateLruProcessLocked(app, true);
}
} catch (PackageManager.NameNotFoundException e) {
throw new RuntimeException(
"Unable to find android system package", e);
}
}</span>AMS通過IApplicationThread來和另一個進程進行交互，除此之外有關的進程信息都保存在ProcessRecord中。
<span style="font-size:14px;"> final ProcessRecord newProcessRecordLocked(IApplicationThread thread,
ApplicationInfo info, String customProcess, boolean isolated) {
String proc = customProcess != null ? customProcess : info.processName;
BatteryStatsImpl.Uid.Proc ps = null;
BatteryStatsImpl stats = mBatteryStatsService.getActiveStatistics();
int uid = info.uid;
if (isolated) {
int userId = UserHandle.getUserId(uid);
int stepsLeft = Process.LAST_ISOLATED_UID - Process.FIRST_ISOLATED_UID + 1;
uid = 0;
while (true) {
if (mNextIsolatedProcessUid < Process.FIRST_ISOLATED_UID
|| mNextIsolatedProcessUid > Process.LAST_ISOLATED_UID) {
mNextIsolatedProcessUid = Process.FIRST_ISOLATED_UID;
}
uid = UserHandle.getUid(userId, mNextIsolatedProcessUid);
mNextIsolatedProcessUid++;
if (mIsolatedProcesses.indexOfKey(uid) < 0) {
// No process for this uid, use it.
break;
}
stepsLeft--;
if (stepsLeft <= 0) {
return null;
}
}
}
synchronized (stats) {
ps = stats.getProcessStatsLocked(info.uid, proc);
}
return new ProcessRecord(ps, thread, info, proc, uid);
}</span> ProcessRecord(BatteryStatsImpl.Uid.Proc _batteryStats, IApplicationThread _thread,
ApplicationInfo _info, String _processName, int _uid) {
batteryStats = _batteryStats;
info = _info;
isolated = _info.uid != _uid;
uid = _uid;
userId = UserHandle.getUserId(_uid);
processName = _processName;
pkgList.add(_info.packageName);
thread = _thread;
maxAdj = ProcessList.HIDDEN_APP_MAX_ADJ;
hiddenAdj = clientHiddenAdj = emptyAdj = ProcessList.HIDDEN_APP_MIN_ADJ;
curRawAdj = setRawAdj = -100;
curAdj = setAdj = -100;
persistent = false;
removed = false;
}此處創建的ProcessRecord保存的對應進程是system_server
下面是installSystemProviders函數
這個函數會加載SettingProvider.apk，將SettingProvider放到system_server進程中
<span style="font-size:14px;"> public static final void installSystemProviders() {
List<ProviderInfo> providers;
synchronized (mSelf) {
ProcessRecord app = mSelf.mProcessNames.get("system", Process.SYSTEM_UID);
providers = mSelf.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);
}
mSelf.mCoreSettingsObserver = new CoreSettingsObserver(mSelf);
mSelf.mUsageStatsService.monitorPackages();
}</span>一個是ActivityThread的installSystemProviders，爲進程安全ContestProvider
最後一個分析點是AMS的systemReady
函數很長，主要工作分爲三個階段
<span style="font-size:14px;"> public void systemReady(final Runnable goingCallback) {
synchronized(this) {
if (mSystemReady) {
if (goingCallback != null) goingCallback.run();
return;
}
// Check to see if there are any update receivers to run.
if (!mDidUpdate) {//是否系統升級
if (mWaitingUpdate) {//未完成升級
return;
}
//準備PRE_BOOT_COMPLETED廣播
Intent intent = new Intent(Intent.ACTION_PRE_BOOT_COMPLETED);
List<ResolveInfo> ris = null;
try {
//向PKMS查詢廣播接收者
ris = AppGlobals.getPackageManager().queryIntentReceivers(
intent, null, 0, 0);
} catch (RemoteException e) {
}
if (ris != null) {
for (int i=ris.size()-1; i>=0; i--) {
if ((ris.get(i).activityInfo.applicationInfo.flags
&ApplicationInfo.FLAG_SYSTEM) == 0) {
ris.remove(i);//刪除非系統APK的接收者
}
}
intent.addFlags(Intent.FLAG_RECEIVER_BOOT_UPGRADE);
//獲取上一次已經接收並處理了廣播的組件
ArrayList<ComponentName> lastDoneReceivers = readLastDonePreBootReceivers();
final ArrayList<ComponentName> doneReceivers = new ArrayList<ComponentName>();
for (int i=0; i<ris.size(); i++) {
ActivityInfo ai = ris.get(i).activityInfo;
ComponentName comp = new ComponentName(ai.packageName, ai.name);
if (lastDoneReceivers.contains(comp)) {
ris.remove(i);//刪除上次已經處理過的組件
i--;
}
}
final int[] users = getUsersLocked();
for (int i=0; i<ris.size(); i++) {
ActivityInfo ai = ris.get(i).activityInfo;
ComponentName comp = new ComponentName(ai.packageName, ai.name);
doneReceivers.add(comp);
intent.setComponent(comp);
for (int j=0; j<users.length; j++) {
IIntentReceiver finisher = null;
if (i == ris.size()-1 && j == users.length-1) {
//給最後一個接收者創建一個回調
finisher = new IIntentReceiver.Stub() {
public void performReceive(Intent intent, int resultCode,
String data, Bundle extras, boolean ordered,
boolean sticky, int sendingUser) {
// The raw IIntentReceiver interface is called
// with the AM lock held, so redispatch to
// execute our code without the lock.
mHandler.post(new Runnable() {
public void run() {
synchronized (ActivityManagerService.this) {
mDidUpdate = true;
}
writeLastDonePreBootReceivers(doneReceivers);
showBootMessage(mContext.getText(
R.string.android_upgrading_complete),
false);
systemReady(goingCallback);
}
});
}
};
}
Slog.i(TAG, "Sending system update to " + intent.getComponent()
+ " for user " + users[j]);
broadcastIntentLocked(null, null, intent, null, finisher,
0, null, null, null, AppOpsManager.OP_NONE,
true, false, MY_PID, Process.SYSTEM_UID,
users[j]);
if (finisher != null) {
mWaitingUpdate = true;
}
}
}
}
if (mWaitingUpdate) {
return;
}
mDidUpdate = true;
}</span>
<span style="font-size:14px;"> ArrayList<ProcessRecord> procsToKill = null;
synchronized(mPidsSelfLocked) {
for (int i=mPidsSelfLocked.size()-1; i>=0; i--) {
ProcessRecord proc = mPidsSelfLocked.valueAt(i);
if (!isAllowedWhileBooting(proc.info)){
if (procsToKill == null) {
procsToKill = new ArrayList<ProcessRecord>();
}
procsToKill.add(proc);
}
}
}
synchronized(this) {
if (procsToKill != null) {
for (int i=procsToKill.size()-1; i>=0; i--) {
ProcessRecord proc = procsToKill.get(i);
Slog.i(TAG, "Removing system update proc: " + proc);
removeProcessLocked(proc, true, false, "system update done");
}
}
// Now that we have cleaned up any update processes, we
// are ready to start launching real processes and know that
// we won't trample on them any more.
mProcessesReady = true;
}
Slog.i(TAG, "System now ready");
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_AMS_READY,
SystemClock.uptimeMillis());
synchronized(this) {
// Make sure we have no pre-ready processes sitting around.
if (mFactoryTest == SystemServer.FACTORY_TEST_LOW_LEVEL) {
ResolveInfo ri = mContext.getPackageManager()
.resolveActivity(new Intent(Intent.ACTION_FACTORY_TEST),
STOCK_PM_FLAGS);
CharSequence errorMsg = null;
if (ri != null) {
ActivityInfo ai = ri.activityInfo;
ApplicationInfo app = ai.applicationInfo;
if ((app.flags&ApplicationInfo.FLAG_SYSTEM) != 0) {
mTopAction = Intent.ACTION_FACTORY_TEST;
mTopData = null;
mTopComponent = new ComponentName(app.packageName,
ai.name);
} else {
errorMsg = mContext.getResources().getText(
com.android.internal.R.string.factorytest_not_system);
}
} else {
errorMsg = mContext.getResources().getText(
com.android.internal.R.string.factorytest_no_action);
}
if (errorMsg != null) {
mTopAction = null;
mTopData = null;
mTopComponent = null;
Message msg = Message.obtain();
msg.what = SHOW_FACTORY_ERROR_MSG;
msg.getData().putCharSequence("msg", errorMsg);
mHandler.sendMessage(msg);
}
}
}
retrieveSettings();</span>debug_app：需要debug的app
wait_for_debugger：如果爲1，等待調試器
always_finish_activities：當一個activity不再有地方使用時，是否destroy
font_scale：控制字體放大倍數
<span style="font-size:14px;"> if (goingCallback != null) goingCallback.run();
synchronized (this) {
if (mFactoryTest != SystemServer.FACTORY_TEST_LOW_LEVEL) {
try {
List apps = AppGlobals.getPackageManager().
getPersistentApplications(STOCK_PM_FLAGS);
if (apps != null) {
int N = apps.size();
int i;
for (i=0; i<N; i++) {
ApplicationInfo info
= (ApplicationInfo)apps.get(i);
if (info != null &&
!info.packageName.equals("android")) {
addAppLocked(info, false);
}
}
}
} catch (RemoteException ex) {
// pm is in same process, this will never happen.
}
}
// Start up initial activity.
mBooting = true;
try {
if (AppGlobals.getPackageManager().hasSystemUidErrors()) {
Message msg = Message.obtain();
msg.what = SHOW_UID_ERROR_MSG;
mHandler.sendMessage(msg);
}
} catch (RemoteException e) {
}
long ident = Binder.clearCallingIdentity();
try {
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,
android.Manifest.permission.INTERACT_ACROSS_USERS, AppOpsManager.OP_NONE,
true, false, MY_PID, Process.SYSTEM_UID, UserHandle.USER_ALL);
} finally {
Binder.restoreCallingIdentity(ident);
}
mMainStack.resumeTopActivityLocked(null);
sendUserSwitchBroadcastsLocked(-1, mCurrentUserId);
}
}</span>設置systemReady的回調對象goingCallback的run函數
啓動聲明爲persistent的APK
啓動桌面