Activity起動プロセス(Android 7.1ベース)
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Activity起動プロセス(Android 7.1ベース)
前に書いてあると
本稿ではcontextを追跡する.startActivityメソッドの実装により、activityの起動プロセスを詳細に理解できます.
テキストの開始
まず,startActivityメソッドの実装をContextImplで行う.
...
final ActivityThread mMainThread;
...
public void startActivity(Intent intent, Bundle options) {
warnIfCallingFromSystemProcess();
...
mMainThread.getInstrumentation().execStartActivity(
getOuterContext(), mMainThread.getApplicationThread(), null,
(Activity) null, intent, -1, options);
}
ここではInstrumentationのexecStartActivityメソッドが呼び出されます.Instrumentation.java
public ActivityResult execStartActivity(
Context who, IBinder contextThread, IBinder token, Activity target,
Intent intent, int requestCode, Bundle options){
...
int result = ActivityManagerNative.getDefault()
.startActivity(whoThread, who.getBasePackageName(), intent,
intent.resolveTypeIfNeeded(who.getContentResolver()),
token, target != null ? target.mEmbeddedID : null,
requestCode, 0, null, options);
...
}
見に行こうgetDefault()メソッド3.ActivityManagerNative.java
/**
* Retrieve the system's default/global activity manager.
*/
static public IActivityManager getDefault() {
return gDefault.get();
}
private static final Singleton gDefault = new Singleton() {
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;
}
};
getDefault()はIActivityManagerの実装クラスを返し、この実装クラスはgDefaultを介していることがわかる.get()メソッドで取得した、gDefaultはSingletonタイプであり、またこちらではbinderメカニズムを使用して、ServiceManagerに登録されているactivityというサービスを呼び出していることもわかります.Singletonというクラスを見て、get()メソッドで返されるIActivity Managerが何であるかを重点的に見てみましょう.4.Singleton.java
public abstract class Singleton {
private T mInstance;
protected abstract T create();
public final T get() {
synchronized (this) {
if (mInstance == null) {
mInstance = create();
}
return mInstance;
}
}
}
getメソッドは明らかですが、実は自分のcreateメソッドを呼び出し、3のcreate()メソッドの実装に戻ります.実際には、サービスマネージャに登録されているactivityというサービスを返します.サービスマネージャを検索することができます.addServiceキーワード検索実はこのactivityというサービスがActivity Management Service 5です.ActivityManagerService.java
public void setSystemProcess() {
...
ServiceManager.addService(Context.ACTIVITY_SERVICE, this, true);
...
}
2のstartActivityメソッドに戻り、最終的に呼び出されたのはActivity Management Serviceで対応するstartActivityメソッドであることがわかりました.
@Override
public final int startActivity(IApplicationThread caller, String callingPackage,
Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
int startFlags, ProfilerInfo profilerInfo, Bundle bOptions) {
return startActivityAsUser(caller, callingPackage, intent, resolvedType, resultTo,
resultWho, requestCode, startFlags, profilerInfo, bOptions,
UserHandle.getCallingUserId());
}
@Override
public final int startActivityAsUser(IApplicationThread caller, String callingPackage,
Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
int startFlags, ProfilerInfo profilerInfo, Bundle bOptions, int userId) {
enforceNotIsolatedCaller("startActivity");
userId = mUserController.handleIncomingUser(Binder.getCallingPid(), Binder.getCallingUid(),
userId, false, ALLOW_FULL_ONLY, "startActivity", null);
// TODO: Switch to user app stacks here.
return mActivityStarter.startActivityMayWait(caller, -1, callingPackage, intent,
resolvedType, null, null, resultTo, resultWho, requestCode, startFlags,
profilerInfo, null, null, bOptions, false, userId, null, null);
}
6.ActivityStarter.java
final int startActivityMayWait(IApplicationThread caller, int callingUid,
String callingPackage, Intent intent, String resolvedType,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
IBinder resultTo, String resultWho, int requestCode, int startFlags,
ProfilerInfo profilerInfo, IActivityManager.WaitResult outResult, Configuration config,
Bundle bOptions, boolean ignoreTargetSecurity, int userId,
IActivityContainer iContainer, TaskRecord inTask) {
...
int res = startActivityLocked(caller, intent, ephemeralIntent, resolvedType,
aInfo, rInfo, voiceSession, voiceInteractor,
resultTo, resultWho, requestCode, callingPid,
callingUid, callingPackage, realCallingPid, realCallingUid, startFlags,
options, ignoreTargetSecurity, componentSpecified, outRecord, container,
inTask);
...
}
final int startActivityLocked(IApplicationThread caller, Intent intent, Intent ephemeralIntent,
String resolvedType, ActivityInfo aInfo, ResolveInfo rInfo,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
IBinder resultTo, String resultWho, int requestCode, int callingPid, int callingUid,
String callingPackage, int realCallingPid, int realCallingUid, int startFlags,
ActivityOptions options, boolean ignoreTargetSecurity, boolean componentSpecified,
ActivityRecord[] outActivity, ActivityStackSupervisor.ActivityContainer container,
TaskRecord inTask) {
...
err = startActivityUnchecked(r, sourceRecord, voiceSession, voiceInteractor, startFlags,
true, options, inTask);
...
}
private int startActivityUnchecked(final ActivityRecord r, ActivityRecord sourceRecord,
IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
int startFlags, boolean doResume, ActivityOptions options, TaskRecord inTask) {
...
mTargetStack.startActivityLocked(mStartActivity, newTask, mKeepCurTransition, mOptions);
...
mSupervisor.resumeFocusedStackTopActivityLocked(mTargetStack, mStartActivity,
mOptions);
...
}
private ActivityStack mTargetStack;
private final ActivityStackSupervisor mSupervisor;
Activity Starterで一連の処理を経て,Activity StackのstartActivity LockedメソッドとActivity StackSupervisorのresumeFocusedStackTopActivity Lockedメソッドが最終的に呼び出されるのを見た.Activity StackのstartActivity Lockedメソッドは、起動するActivityをtaskスタックトップに押し込み、taskをスタックトップに調整する役割を果たします.Activity StackSupervisorのresumeFocusedStackTopActivity Locked法を重点的に解析した.7.ActivityStackSupervisor.java
/** The stack currently receiving input or launching the next activity. */
ActivityStack mFocusedStack;
boolean resumeFocusedStackTopActivityLocked(
ActivityStack targetStack, ActivityRecord target, ActivityOptions targetOptions) {
if (targetStack != null && isFocusedStack(targetStack)) {
return targetStack.resumeTopActivityUncheckedLocked(target, targetOptions);
}
final ActivityRecord r = mFocusedStack.topRunningActivityLocked();
if (r == null || r.state != RESUMED) {
mFocusedStack.resumeTopActivityUncheckedLocked(null, null);
}
return false;
}
8.ActivityStack.java
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;
if (mService.mLockScreenShown == ActivityManagerService.LOCK_SCREEN_LEAVING) {
mService.mLockScreenShown = ActivityManagerService.LOCK_SCREEN_HIDDEN;
mService.updateSleepIfNeededLocked();
}
result = resumeTopActivityInnerLocked(prev, options);
} finally {
mStackSupervisor.inResumeTopActivity = false;
}
return result;
}
/** Run all ActivityStacks through this */
final ActivityStackSupervisor mStackSupervisor;
private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) {
...
boolean pausing = mStackSupervisor.pauseBackStacks(userLeaving, next, dontWaitForPause);
...
mStackSupervisor.startSpecificActivityLocked(next, true, true);
...
}
resumeTopActivity InnerLockedメソッドが呼び出されているのを見て、このメソッドでは2つの重要なメソッドが呼び出されています.Activity StackSupervisorのpauseBackStacksメソッドとstartSpecificActivity Lockedメソッドが呼び出されています.pauseBackStacksというメソッドは元のフロントActivityのonPauseメソッドを呼び出し、startSpecificActivity Lockedは起動する必要があるActivityを起動します.startSpecificActivity Lockedという方法を重点的に見てみましょう.9.ActivityStackSupervisor.java
void startSpecificActivityLocked(ActivityRecord r,
boolean andResume, boolean checkConfig) {
// Is this activity's application already running?
ProcessRecord app = mService.getProcessRecordLocked(r.processName,
r.info.applicationInfo.uid, true);
r.task.stack.setLaunchTime(r);
if (app != null && app.thread != null) {
try {
if ((r.info.flags&ActivityInfo.FLAG_MULTIPROCESS) == 0
|| !"android".equals(r.info.packageName)) {
// Don't add this if it is a platform component that is marked
// to run in multiple processes, because this is actually
// part of the framework so doesn't make sense to track as a
// separate apk in the process.
app.addPackage(r.info.packageName, r.info.applicationInfo.versionCode,
mService.mProcessStats);
}
//1. application ， ， Activity，
realStartActivityLocked(r, app, andResume, checkConfig);
return;
} catch (RemoteException e) {
Slog.w(TAG, "Exception when starting activity "
+ r.intent.getComponent().flattenToShortString(), e);
}
// If a dead object exception was thrown -- fall through to
// restart the application.
}
//2. Application ， Activity Activity，
mService.startProcessLocked(r.processName, r.info.applicationInfo, true, 0,
"activity", r.intent.getComponent(), false, false, true);
}
2のコールドスタートを重点的に見てみましょう.ここのmServiceはActivity Management Service 10です.ActivityManagerService.java
final ProcessRecord startProcessLocked(String processName,
ApplicationInfo info, boolean knownToBeDead, int intentFlags,
String hostingType, ComponentName hostingName, boolean allowWhileBooting,
boolean isolated, boolean keepIfLarge) {
return startProcessLocked(processName, info, knownToBeDead, intentFlags, hostingType,
hostingName, allowWhileBooting, isolated, 0 /* isolatedUid */, keepIfLarge,
null /* ABI override */, null /* entryPoint */, null /* entryPointArgs */,
null /* crashHandler */);
}
final ProcessRecord startProcessLocked(String processName, ApplicationInfo info,
boolean knownToBeDead, int intentFlags, String hostingType, ComponentName hostingName,
boolean allowWhileBooting, boolean isolated, int isolatedUid, boolean keepIfLarge,
String abiOverride, String entryPoint, String[] entryPointArgs, Runnable crashHandler) {
...
startProcessLocked(
app, hostingType, hostingNameStr, abiOverride, entryPoint, entryPointArgs);
...
}
private final void startProcessLocked(ProcessRecord app, String hostingType,
String hostingNameStr, String abiOverride, String entryPoint, String[] entryPointArgs) {
...
Process.ProcessStartResult startResult = Process.start(entryPoint,
app.processName, uid, uid, gids, debugFlags, mountExternal,
app.info.targetSdkVersion, app.info.seinfo, requiredAbi, instructionSet,
app.info.dataDir, entryPointArgs);
...
}
プロセスが最終的に呼び出されたことがわかります.startメソッド11.Process.java
public static final ProcessStartResult start(final String processClass,
final String niceName,
int uid, int gid, int[] gids,
int debugFlags, int mountExternal,
int targetSdkVersion,
String seInfo,
String abi,
String instructionSet,
String appDataDir,
String[] zygoteArgs) {
try {
return startViaZygote(processClass, niceName, uid, gid, gids,
debugFlags, mountExternal, targetSdkVersion, seInfo,
abi, instructionSet, appDataDir, zygoteArgs);
} catch (ZygoteStartFailedEx ex) {
Log.e(LOG_TAG,
"Starting VM process through Zygote failed");
throw new RuntimeException(
"Starting VM process through Zygote failed", ex);
}
}
private static ProcessStartResult startViaZygote(final String processClass,
final String niceName,
final int uid, final int gid,
final int[] gids,
int debugFlags, int mountExternal,
int targetSdkVersion,
String seInfo,
String abi,
String instructionSet,
String appDataDir,
String[] extraArgs)
throws ZygoteStartFailedEx {
...
return zygoteSendArgsAndGetResult(openZygoteSocketIfNeeded(abi), argsForZygote);
}
最終的にzygoteSendArgsAndGetResult(openZygoteSocketIfNeeded(abi),argsForZygote)というメソッドを呼び出してプロセスを作成し,openZygoteSocketIfNeededによってsocketを介してZygoteプロセスにメッセージを送信することが分かったが,このときこちらのメソッドは実行済みであり,後にZygoteプロセスがSocket対端のメッセージを受け取った後にプロセスを作成し,プロセス作成が完了すると,変更プロセスのActivity Threadのmain()メソッドが呼び出されます.12.ActivityThread.java
public static void main(String[] args) {
...
ActivityThread thread = new ActivityThread();
thread.attach(false);
...
}
private void attach(boolean system) {
...
//3 ， binder AMS
final IActivityManager mgr = ActivityManagerNative.getDefault();
...
try {
mgr.attachApplication(mAppThread);
} catch (RemoteException ex) {
throw ex.rethrowFromSystemServer();
}
...
}
最終的に呼び出すのはAMSのattachApplicationメソッド13である.ActivityManagerService.java
public final void attachApplication(IApplicationThread thread) {
synchronized (this) {
int callingPid = Binder.getCallingPid();
final long origId = Binder.clearCallingIdentity();
attachApplicationLocked(thread, callingPid);
Binder.restoreCallingIdentity(origId);
}
}
private final boolean attachApplicationLocked(IApplicationThread thread,
int pid) {
...
// (1) bindApplication
thread.bindApplication(processName, appInfo, providers, app.instrumentationClass,
profilerInfo, app.instrumentationArguments, app.instrumentationWatcher,
app.instrumentationUiAutomationConnection, testMode,
mBinderTransactionTrackingEnabled, enableTrackAllocation,
isRestrictedBackupMode || !normalMode, app.persistent,
new Configuration(mConfiguration), app.compat,
getCommonServicesLocked(app.isolated),
mCoreSettingsObserver.getCoreSettingsLocked());
...
// See if the top visible activity is waiting to run in this process...
if (normalMode) {
try {
// (2) attachApplicationLocked
if (mStackSupervisor.attachApplicationLocked(app)) {
didSomething = true;
}
} catch (Exception e) {
Slog.wtf(TAG, "Exception thrown launching activities in " + app, e);
badApp = true;
}
}
...
}
この中で重要な2つの方法は(1)thread.bindApplication (2) mStackSupervisor.まず(1)を見てみましょうbindApplicationのこちらのthreadはActivity Threadから渡されたIApplicationThreadオブジェクトである、12のmAppThreadパラメータは初期化14である.ActivityThread.java
final ApplicationThread mAppThread = new ApplicationThread();
// ActivityThread
private class ApplicationThread extends ApplicationThreadNative {
...
public final void bindApplication(String processName, ApplicationInfo appInfo,
List 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 services, Bundle coreSettings) {
...
sendMessage(H.BIND_APPLICATION, data);
...
}
...
}
private void sendMessage(int what, Object obj) {
sendMessage(what, obj, 0, 0, false);
}
private void sendMessage(int what, Object obj, int arg1, int arg2, boolean async) {
if (DEBUG_MESSAGES) Slog.v(
TAG, "SCHEDULE " + what + " " + mH.codeToString(what)
+ ": " + arg1 + " / " + obj);
Message msg = Message.obtain();
msg.what = what;
msg.obj = obj;
msg.arg1 = arg1;
msg.arg2 = arg2;
if (async) {
msg.setAsynchronous(true);
}
mH.sendMessage(msg);
}
final H mH = new H();
// H Handler
private class H extends Handler {
public void handleMessage(Message msg) {
switch (msg.what) {
...
case BIND_APPLICATION:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "bindApplication");
AppBindData data = (AppBindData)msg.obj;
handleBindApplication(data);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
break;
...
}
}
}
private void handleBindApplication(AppBindData data) {
}
最終的に呼び出されたのはhandleBindApplicationメソッドで、こちらは終わり、新しいアプリケーションプロセスが起動し、Applicationとバインドされました.13の(2)mStackSupervisorに戻りますattachApplicationLocked 15.ActivityStackSupervisor.java
boolean attachApplicationLocked(ProcessRecord app) throws RemoteException {
...
if (realStartActivityLocked(hr, app, true, true)) {
didSomething = true;
}
...
}
final boolean realStartActivityLocked(ActivityRecord r, ProcessRecord app,
boolean andResume, boolean checkConfig) throws RemoteException {
...
app.thread.scheduleLaunchActivity(new Intent(r.intent), r.appToken,
System.identityHashCode(r), r.info, new Configuration(mService.mConfiguration),
new Configuration(task.mOverrideConfig), r.compat, r.launchedFromPackage,
task.voiceInteractor, app.repProcState, r.icicle, r.persistentState, results,
newIntents, !andResume, mService.isNextTransitionForward(), profilerInfo);
...
}
こちらのappはProcessRecordの例である、threadはIApplicationThreadの実装クラスである、実は14のActivity Thread内部クラスApplicationThread 16である.ActivityThread.java
private class ApplicationThread extends ApplicationThreadNative {
...
public final void scheduleLaunchActivity(Intent intent, IBinder token, int ident,
ActivityInfo info, Configuration curConfig, Configuration overrideConfig,
CompatibilityInfo compatInfo, String referrer, IVoiceInteractor voiceInteractor,
int procState, Bundle state, PersistableBundle persistentState,
List pendingResults, List pendingNewIntents,
boolean notResumed, boolean isForward, ProfilerInfo profilerInfo) {
...
sendMessage(H.LAUNCH_ACTIVITY, r);
...
}
...
}
この中のsendMessageの方法はすでに14の中で分析して、最終的にHの中のこのコードに呼び出すことができます
...
case LAUNCH_ACTIVITY: {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "activityStart");
final ActivityClientRecord r = (ActivityClientRecord) msg.obj;
r.packageInfo = getPackageInfoNoCheck(
r.activityInfo.applicationInfo, r.compatInfo);
handleLaunchActivity(r, null, "LAUNCH_ACTIVITY");
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
} break;
...
private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent, String reason) {
...
Activity a = performLaunchActivity(r, customIntent);
...
}
private Activity performLaunchActivity(ActivityClientRecord r, Intent customIntent) {
...
if (r.isPersistable()) {
mInstrumentation.callActivityOnCreate(activity, r.state, r.persistentState);
} else {
mInstrumentation.callActivityOnCreate(activity, r.state);
}
...
}
17.Instrumentation.java
public void callActivityOnCreate(Activity activity, Bundle icicle,
PersistableBundle persistentState) {
prePerformCreate(activity);
activity.performCreate(icicle, persistentState);
postPerformCreate(activity);
}
18.Activity.java
final void performCreate(Bundle icicle, PersistableBundle persistentState) {
restoreHasCurrentPermissionRequest(icicle);
onCreate(icicle, persistentState);
mActivityTransitionState.readState(icicle);
performCreateCommon();
}
これでActivityのonCreateメソッドが呼び出され,解析プロセス全体が終了するのを見た.
後に書くと
Androidシステム全体は非常に膨大ですが、私たちが心を静めて見れば、コード実行の流れを理解することができます.コードを見るときは詳細な論理にこだわる必要はありません.キーコードに注目すればいいのですが、キーコードには一般的に注釈があります.注釈を多く見ると、キーコードの実行過程を見つけることができます.