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JobScheduler调度器过程（JobSchedulerService的启动过程）
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JobSchedulerService启动过程，最主要工作是从jobs.xml文件收集所有的jobs，放入到JobStore的成员变量mJobSet，转成jobinfo。
JobScheduler服务启动
2.1 startOtherServices
2.1 startOtherServices
[-> SystemServer.java]
private void startOtherServices() {
...
mSystemServiceManager.startService(JobSchedulerService.class);
...
}
该方法先初始化JSS，然后再调用其onStart()方法。
2.2 JobSchedulerService
[-> JobSchedulerService.java]
JobSchedulerService {
List<StateController> mControllers;
final JobHandler mHandler;
final JobSchedulerStub mJobSchedulerStub;
final JobStore mJobs;
...
public JobSchedulerService(Context context) {
super(context);
mControllers = new ArrayList<StateController>();
mControllers.add(ConnectivityController.get(this));
mControllers.add(TimeController.get(this));
mControllers.add(IdleController.get(this));
mControllers.add(BatteryController.get(this));
mControllers.add(AppIdleController.get(this));
//创建主线程的looper[见小节2.3]
mHandler = new JobHandler(context.getMainLooper());
//创建binder服务端[见小节2.4]
mJobSchedulerStub = new JobSchedulerStub();
//[见小节2.5]
mJobs = JobStore.initAndGet(this);
}
public void onStart() {
publishBinderService(Context.JOB_SCHEDULER_SERVICE, mJobSchedulerStub);
}
}
创建了5个不同的StateController，分别添加到mControllers。
| 类型 | 说明 |
|---|---|
| ConnectivityController | 注册监听网络连接状态的广播 |
| TimeController | 注册监听job时间到期的广播 |
| IdleController | 注册监听屏幕亮/灭,dream进入/退出,状态改变的广播 |
| BatteryController | 注册监听电池是否充电,电量状态的广播 |
| AppIdleController | 监听app是否空闲 |
接下来,以ConnectivityController为例,说一说相应Controller的创建过程, 其他Controller也基本类似.
2.2.1 ConnectivityController
[-> ConnectivityController.java]
public class ConnectivityController extends StateController implements ConnectivityManager.OnNetworkActiveListener {
public static ConnectivityController get(JobSchedulerService jms) {
synchronized (sCreationLock) {
if (mSingleton == null) {
//单例模式
mSingleton = new ConnectivityController(jms, jms.getContext());
}
return mSingleton;
}
}
private ConnectivityController(StateChangedListener stateChangedListener, Context context) {
super(stateChangedListener, context);
//注册监听网络连接状态的广播，且采用BackgroundThread线程
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
mContext.registerReceiverAsUser(
mConnectivityChangedReceiver, UserHandle.ALL, intentFilter, null,
BackgroundThread.getHandler());
ConnectivityService cs =
(ConnectivityService)ServiceManager.getService(Context.CONNECTIVITY_SERVICE);
if (cs != null) {
if (cs.getActiveNetworkInfo() != null) {
mNetworkConnected = cs.getActiveNetworkInfo().isConnected();
}
mNetworkUnmetered = mNetworkConnected && !cs.isActiveNetworkMetered();
}
}
}
当监听到CONNECTIVITY_ACTION广播，onReceive方法的执行位于“android.bg”线程。
2.3 JSS.JobHandler
[-> JobSchedulerService.java ::JobHandler]
public class JobSchedulerService extends com.android.server.SystemService implements StateChangedListener, JobCompletedListener {
private class JobHandler extends Handler {
public JobHandler(Looper looper) {
super(looper);
}
public void handleMessage(Message message) {
synchronized (mJobs) {
//当系统启动到phase 600，则mReadyToRock=true.
if (!mReadyToRock) {
return;
}
}
switch (message.what) {
case MSG_JOB_EXPIRED: ...
case MSG_CHECK_JOB: ...
}
maybeRunPendingJobsH();
removeMessages(MSG_CHECK_JOB);
}
JobHandler采用的是system_server进程的主线程Looper，也就是该过程运行在主线程。
2.4 JobSchedulerStub
[-> JobSchedulerService.java ::JobSchedulerStub]
final class JobSchedulerStub extends IJobScheduler.Stub {
...
}
JobSchedulerStub作为实现接口IJobScheduler的binder服务端。
2.5 JS.initAndGet
[-> JobStore.java]
static JobStore initAndGet(JobSchedulerService jobManagerService) {
synchronized (sSingletonLock) {
if (sSingleton == null) {
//[见小节2.6]
sSingleton = new JobStore(jobManagerService.getContext(),
Environment.getDataDirectory());
}
return sSingleton;
}
}
2.6 创建JobStore
[-> JobStore.java]
public class JobStore {
final ArraySet<JobStatus> mJobSet;
private final Handler mIoHandler = IoThread.getHandler();
...
private JobStore(Context context, File dataDir) {
mContext = context;
mDirtyOperations = 0;
File systemDir = new File(dataDir, "system");
File jobDir = new File(systemDir, "job");
jobDir.mkdirs();
// 创建/data/system/job/jobs.xml
mJobsFile = new AtomicFile(new File(jobDir, "jobs.xml"));
mJobSet = new ArraySet<JobStatus>();
//[见小节2.7.1]
readJobMapFromDisk(mJobSet);
}
}
该方法会创建job目录以及jobs.xml文件, 以及从文件中读取所有的JobStatus。
2.7 xml解析
2.7.1 ReadJobMapFromDiskRunnable
[-> JobStore.java]
private class ReadJobMapFromDiskRunnable implements Runnable {
private final ArraySet<JobStatus> jobSet;
ReadJobMapFromDiskRunnable(ArraySet<JobStatus> jobSet) {
this.jobSet = jobSet;
}
public void run() {
List<JobStatus> jobs;
FileInputStream fis = mJobsFile.openRead();
synchronized (JobStore.this) {
jobs = readJobMapImpl(fis); //[见小节2.7.2]
if (jobs != null) {
for (int i=0; i<jobs.size(); i++) {
this.jobSet.add(jobs.get(i));
}
}
}
fis.close();
}
}
此处mJobsFile便是/data/system/job/jobs.xml。
2.7.2 readJobMapImpl
[-> JobStore.java]
private List<JobStatus> readJobMapImpl(FileInputStream fis)
throws XmlPullParserException, IOException {
XmlPullParser parser = Xml.newPullParser();
parser.setInput(fis, StandardCharsets.UTF_8.name());
...
String tagName = parser.getName();
if ("job-info".equals(tagName)) {
final List<JobStatus> jobs = new ArrayList<JobStatus>();
...
eventType = parser.next();
do {
//读取每一个 <job/>
if (eventType == XmlPullParser.START_TAG) {
tagName = parser.getName();
if ("job".equals(tagName)) {
//[见小节2.7.3]
JobStatus persistedJob = restoreJobFromXml(parser);
if (persistedJob != null) {
jobs.add(persistedJob);
}
}
}
eventType = parser.next();
} while (eventType != XmlPullParser.END_DOCUMENT);
return jobs;
}
return null;
}
从文件jobs.xml中读取并创建JobStatus，然后添加到mJobSet.
2.7.3 restoreJobFromXml
[-> JobStore.java]
private JobStatus restoreJobFromXml(XmlPullParser parser) throws XmlPullParserException, IOException {
JobInfo.Builder jobBuilder;
int uid;
//创建用于获取jobInfo的Builder[见小节2.7.4]
jobBuilder = buildBuilderFromXml(parser);
jobBuilder.setPersisted(true);
uid = Integer.valueOf(parser.getAttributeValue(null, "uid"));
...
buildConstraintsFromXml(jobBuilder, parser); //读取常量
//读取job执行的两个时间点：delay和deadline
Pair<Long, Long> elapsedRuntimes = buildExecutionTimesFromXml(parser);
...
//[见小节2.8]
return new JobStatus(jobBuilder.build(), uid,
elapsedRuntimes.first, elapsedRuntimes.second);
}
2.7.4 buildBuilderFromXml
[-> JobStore.java]
private JobInfo.Builder buildBuilderFromXml(XmlPullParser parser) throws NumberFormatException {
int jobId = Integer.valueOf(parser.getAttributeValue(null, "jobid"));
String packageName = parser.getAttributeValue(null, "package");
String className = parser.getAttributeValue(null, "class");
ComponentName cname = new ComponentName(packageName, className);
//[见小节2.7.5]
return new JobInfo.Builder(jobId, cname);
}
创建的JobInfo对象，记录着任务的jobid, package, class。
2.7.5 创建JobInfo
[-> JobInfo.java]
public class JobInfo implements Parcelable {
public static final class Builder {
public Builder(int jobId, ComponentName jobService) {
mJobService = jobService;
mJobId = jobId;
}
public JobInfo build() {
mExtras = new PersistableBundle(mExtras);
return new JobInfo(this); //创建JobInfo
}
}
}
2.8 创建JobStatus
[-> JobStatus.java]
public JobStatus(JobInfo job, int uId, long earliestRunTimeElapsedMillis, long latestRunTimeElapsedMillis) {
this(job, uId, 0);
this.earliestRunTimeElapsedMillis = earliestRunTimeElapsedMillis;
this.latestRunTimeElapsedMillis = latestRunTimeElapsedMillis;
}
private JobStatus(JobInfo job, int uId, int numFailures) {
this.job = job;
this.uId = uId;
this.name = job.getService().flattenToShortString();
this.tag = "*job*/" + this.name;
this.numFailures = numFailures;
}
JobStatus对象记录着任务的jobId, ComponentName, uid以及标签和失败次数信息。
2.9 JSS.onBootPhase
public void onBootPhase(int phase) {
if (PHASE_SYSTEM_SERVICES_READY == phase) {
//阶段500，则开始注册package和use移除的广播监听
final IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_REMOVED);
filter.addDataScheme("package");
getContext().registerReceiverAsUser(
mBroadcastReceiver, UserHandle.ALL, filter, null, null);
final IntentFilter userFilter = new IntentFilter(Intent.ACTION_USER_REMOVED);
userFilter.addAction(PowerManager.ACTION_DEVICE_IDLE_MODE_CHANGED);
getContext().registerReceiverAsUser(
mBroadcastReceiver, UserHandle.ALL, userFilter, null, null);
mPowerManager = (PowerManager)getContext().getSystemService(Context.POWER_SERVICE);
} else if (phase == PHASE_THIRD_PARTY_APPS_CAN_START) {
synchronized (mJobs) {
mReadyToRock = true;
mBatteryStats = IBatteryStats.Stub.asInterface(ServiceManager.getService(
BatteryStats.SERVICE_NAME));
for (int i = 0; i < MAX_JOB_CONTEXTS_COUNT; i++) {
//创建JobServiceContext对象
mActiveServices.add(
new JobServiceContext(this, mBatteryStats,
getContext().getMainLooper()));
}
ArraySet<JobStatus> jobs = mJobs.getJobs();
for (int i=0; i<jobs.size(); i++) {
JobStatus job = jobs.valueAt(i);
for (int controller=0; controller<mControllers.size(); controller++) {
mControllers.get(controller).deviceIdleModeChanged(mDeviceIdleMode);
mControllers.get(controller).maybeStartTrackingJob(job);
}
}
//[见小节3.8]
mHandler.obtainMessage(MSG_CHECK_JOB).sendToTarget();
}
}
}
对于低内存的设备，则只创建一个创建JobServiceContext对象；否则创建3个该对象。
2.9.1 创建JobServiceContext
[-> JobServiceContext.java]
JobServiceContext(JobSchedulerService service, IBatteryStats batteryStats, Looper looper) {
this(service.getContext(), batteryStats, service, looper);
}
JobServiceContext(Context context, IBatteryStats batteryStats,
JobCompletedListener completedListener, Looper looper) {
mContext = context;
mBatteryStats = batteryStats;
mCallbackHandler = new JobServiceHandler(looper);
mCompletedListener = completedListener;
mAvailable = true;
}
此处的JobServiceHandler采用的是system_server进程的主线程。
2.10 小结
- JSS.JobHandler运行在system_server进程的主线程；
- JobServiceContext.JobServiceHandler运行在system_server进程的主线程；
- JobSchedulerStub作为实现接口IJobScheduler的binder服务端；
- JobStore：其成员变量mIoHandler运行在”android.io”线程；
- JobStatus：从/data/system/job/jobs.xml文件中读取每个JobInfo,再解析成JobStatus对象，添加到mJobSet。
