Android 6.0 启动startService()源码分析（3）
闲话少说，接上一篇《Android 6.0 启动startService()源码分析（2）》
10.9 ActiveServices.bumpServiceExecutingLocked 发送SERVICE_TIMEOUT_MSG用来判断是否ANR
private final void bumpServiceExecutingLocked(ServiceRecord r, boolean fg, String why) {
if (DEBUG_SERVICE) Slog.v(TAG_SERVICE, ">>> EXECUTING "
+ why + " of " + r + " in app " + r.app);
else if (DEBUG_SERVICE_EXECUTING) Slog.v(TAG_SERVICE_EXECUTING, ">>> EXECUTING "
+ why + " of " + r.shortName);
long now = SystemClock.uptimeMillis();
【executeNesting 记录前台次数，第一次为0，fg是启动前台还是后台服务】
if (r.executeNesting == 0) {
r.executeFg = fg;
ProcessStats.ServiceState stracker = r.getTracker();
if (stracker != null) {
stracker.setExecuting(true, mAm.mProcessStats.getMemFactorLocked(), now);
}
if (r.app != null) {
r.app.executingServices.add(r);
r.app.execServicesFg |= fg;
if (r.app.executingServices.size() == 1) {
scheduleServiceTimeoutLocked(r.app); 【10.9.1 发送SERVICE_TIMEOUT_MSG】
}
}
} else if (r.app != null && fg && !r.app.execServicesFg) {
r.app.execServicesFg = true;
scheduleServiceTimeoutLocked(r.app);
}
r.executeFg |= fg;
r.executeNesting++;
r.executingStart = now;
}10.9.1 发送SERVICE_TIMEOUT_MSG
void scheduleServiceTimeoutLocked(ProcessRecord proc) {
if (proc.executingServices.size() == 0 || proc.thread == null) {
return;
}
long now = SystemClock.uptimeMillis();
Message msg = mAm.mHandler.obtainMessage(
ActivityManagerService.SERVICE_TIMEOUT_MSG);
msg.obj = proc;
【发送SERVICE_TIMEOUT_MSG消息】
mAm.mHandler.sendMessageAtTime(msg,
proc.execServicesFg ? (now+SERVICE_TIMEOUT) : (now+ SERVICE_BACKGROUND_TIMEOUT));
}前台服务 SERVICE_TIMEOUT是20s
后台服务 SERVICE_BACKGROUND_TIMEOUT是200s
如果超过上面时间，没有移除SERVICE_TIMEOUT_MSG消息，就会弹出ANR消息。
10.10 ActivityThread.scheduleCreateService
app.thread.scheduleCreateService(r, r.serviceInfo,mAm.compatibilityInfoForPackageLocked(r.serviceInfo.applicationInfo),app.repProcState);其实调用的方法是ApplicationThreadProxy中的scheduleCreateService()，代码写在ApplicationThreadNative.java中
public final void scheduleCreateService(IBinder token, ServiceInfo info,
CompatibilityInfo compatInfo, int processState) throws RemoteException {
Parcel data = Parcel.obtain();
data.writeInterfaceToken(IApplicationThread.descriptor);
data.writeStrongBinder(token);
info.writeToParcel(data, 0);
compatInfo.writeToParcel(data, 0);
data.writeInt(processState);
try {
【是不是很熟悉，，，binder....然后到了ApplicationThreadNative的onTransact()】
mRemote.transact(SCHEDULE_CREATE_SERVICE_TRANSACTION, data, null,
IBinder.FLAG_ONEWAY);
} catch (TransactionTooLargeException e) {
Log.e("CREATE_SERVICE", "Binder failure starting service; service=" + info);
throw e;
}
data.recycle();
}mRemote.transact()这是不是很熟悉啊，，参考前面《Android 6.0 启动startService()源码分析（1）》中ActivityManagerProxy、ActivityManagerNative和ActivityManagerService的关系，这里省略
最后运行到了ApplicationThread.scheduleCreateService()
10.11 ApplicationThread.scheduleCreateService()
ApplicationThread是在ActivityThread.java中
public final void scheduleCreateService(IBinder token,
ServiceInfo info, CompatibilityInfo compatInfo, int processState) {
updateProcessState(processState, false);
CreateServiceData s = new CreateServiceData();
s.token = token;
s.info = info;
s.compatInfo = compatInfo;
【发送CREATE_SERVICE消息】
sendMessage(H.CREATE_SERVICE, s);
} case CREATE_SERVICE:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "serviceCreate");
【handleCreateService】
handleCreateService((CreateServiceData)msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
break; private void handleCreateService(CreateServiceData data) {
// If we are getting ready to gc after going to the background, well
// we are back active so skip it.
unscheduleGcIdler();
.....
try {
if (localLOGV) Slog.v(TAG, "Creating service " + data.info.name);
ContextImpl context = ContextImpl.createAppContext(this, packageInfo);
context.setOuterContext(service);
Application app = packageInfo.makeApplication(false, mInstrumentation);
service.attach(context, this, data.info.name, data.token, app,
ActivityManagerNative.getDefault());
【service.onCreate()创建】
service.onCreate();
mServices.put(data.token, service);
try {
【10.12 这里调用的是ActivityManagerService.serviceDoneExecuting()此时出传入type=SERVICE_DONE_EXECUTING_ANON 】
ActivityManagerNative.getDefault().serviceDoneExecuting(
data.token, SERVICE_DONE_EXECUTING_ANON, 0, 0);
} catch (RemoteException e) {
// nothing to do.
}
} catch (Exception e) {
if (!mInstrumentation.onException(service, e)) {
throw new RuntimeException(
"Unable to create service " + data.info.name
+ ": " + e.toString(), e);
}
}
}10.12 ActivityManagerService.serviceDoneExecuting()
public void serviceDoneExecuting(IBinder token, int type, int startId, int res) {
synchronized(this) {
if (!(token instanceof ServiceRecord)) {
Slog.e(TAG, "serviceDoneExecuting: Invalid service token=" + token);
throw new IllegalArgumentException("Invalid service token");
}
【10.13 serviceDoneExecutingLocked】
mServices.serviceDoneExecutingLocked((ServiceRecord)token, type, startId, res);
}
}10.13 ActiveServices.serviceDoneExecutingLocked()
在onCreate时候传入的type是SERVICE_DONE_EXECUTING_ANON，上面可以看到。
void serviceDoneExecutingLocked(ServiceRecord r, int type, int startId, int res) {
boolean inDestroying = mDestroyingServices.contains(r);
if (r != null) {
if (type == ActivityThread.SERVICE_DONE_EXECUTING_START) {
.....
} else if (type == ActivityThread.SERVICE_DONE_EXECUTING_STOP) {
......
}
final long origId = Binder.clearCallingIdentity();
// 10.14 type 都不符合上面条件，因此直接走这里serviceDoneExecutingLocked
serviceDoneExecutingLocked(r, inDestroying, inDestroying);
Binder.restoreCallingIdentity(origId);
} else {
Slog.w(TAG, "Done executing unknown service from pid "
+ Binder.getCallingPid());
}
}// 10.14 serviceDoneExecutingLocked
private void serviceDoneExecutingLocked(ServiceRecord r, boolean inDestroying,
boolean finishing) {
r.executeNesting--;
if (r.executeNesting <= 0) {
if (r.app != null) {
if (DEBUG_SERVICE) Slog.v(TAG_SERVICE,
"Nesting at 0 of " + r.shortName);
r.app.execServicesFg = false;
r.app.executingServices.remove(r);
if (r.app.executingServices.size() == 0) {
if (DEBUG_SERVICE || DEBUG_SERVICE_EXECUTING) Slog.v(TAG_SERVICE_EXECUTING,
"No more executingServices of " + r.shortName);
【移除超时SERVICE_TIMEOUT_MSG消息，否则就会ANR】
mAm.mHandler.removeMessages(ActivityManagerService.SERVICE_TIMEOUT_MSG, r.app);
} else if (r.executeFg) {
// Need to re-evaluate whether the app still needs to be in the foreground.
for (int i=r.app.executingServices.size()-1; i>=0; i--) {
if (r.app.executingServices.valueAt(i).executeFg) {
r.app.execServicesFg = true;
break;
}
}
}
......
}
}如果没有移除超时消息SERVICE_TIMEOUT_MSG，就会ANR。
onCreate()执行完后，接着是前面提到的sendServiceArgsLocked()，我们继续
11. 0 sendServiceArgsLocked 服务进入onStartCommand()
private final void sendServiceArgsLocked(ServiceRecord r, boolean execInFg,
boolean oomAdjusted) throws TransactionTooLargeException {
final int N = r.pendingStarts.size();
if (N == 0) {
return;
}
while (r.pendingStarts.size() > 0) {
Exception caughtException = null;
ServiceRecord.StartItem si;
try {
si = r.pendingStarts.remove(0);
if (DEBUG_SERVICE) Slog.v(TAG_SERVICE, "Sending arguments to: "
+ r + " " + r.intent + " args=" + si.intent);
if (si.intent == null && N > 1) {
// If somehow we got a dummy null intent in the middle,
// then skip it. DO NOT skip a null intent when it is
// the only one in the list -- this is to support the
// onStartCommand(null) case.
continue;
}
si.deliveredTime = SystemClock.uptimeMillis();
r.deliveredStarts.add(si);
si.deliveryCount++;
if (si.neededGrants != null) {
mAm.grantUriPermissionUncheckedFromIntentLocked(si.neededGrants,
si.getUriPermissionsLocked());
}
【和 10.9 ActiveServices.bumpServiceExecutingLocked 发送SERVICE_TIMEOUT_MSG用来判断是否ANR，一样】
bumpServiceExecutingLocked(r, execInFg, "start");
if (!oomAdjusted) {
oomAdjusted = true;
mAm.updateOomAdjLocked(r.app);
}
int flags = 0;
if (si.deliveryCount > 1) {
flags |= Service.START_FLAG_RETRY;
}
if (si.doneExecutingCount > 0) {
flags |= Service.START_FLAG_REDELIVERY;
}
【启动onStartCommand，这个和启动onCreate()的路径都一样，这里都不在重复】
r.app.thread.scheduleServiceArgs(r, si.taskRemoved, si.id, flags, si.intent);
} catch (TransactionTooLargeException e) {
if (DEBUG_SERVICE) Slog.v(TAG_SERVICE, "Transaction too large: intent="
+ si.intent);
caughtException = e;
} catch (RemoteException e) {
// Remote process gone... we'll let the normal cleanup take care of this.
if (DEBUG_SERVICE) Slog.v(TAG_SERVICE, "Crashed while sending args: " + r);
caughtException = e;
} catch (Exception e) {
Slog.w(TAG, "Unexpected exception", e);
caughtException = e;
}
if (caughtException != null) {
// Keep nesting count correct
final boolean inDestroying = mDestroyingServices.contains(r);
serviceDoneExecutingLocked(r, inDestroying, inDestroying);
if (caughtException instanceof TransactionTooLargeException) {
throw (TransactionTooLargeException)caughtException;
}
break;
}
}
}启动onStartCommand()和onCreate()流程差不多，这个就不再重复。流程很长，细节部分都丢了。
总结
1、在流程中，我们看到了在ActivityThread.java中初始化了Looper.prepareMainLooper()和开启了Looper.loop()
2、前台服务20m没有执行完就会ANR，后台服务200s没有启动就ANR
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