| /* |
| * Copyright (C) 2014 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License |
| */ |
| |
| package android.app.task; |
| |
| import android.app.Service; |
| import android.content.Intent; |
| import android.os.Handler; |
| import android.os.IBinder; |
| import android.os.Looper; |
| import android.os.Message; |
| import android.os.RemoteException; |
| import android.util.Log; |
| |
| import com.android.internal.annotations.GuardedBy; |
| |
| /** |
| * <p>Entry point for the callback from the {@link android.content.TaskManager}.</p> |
| * <p>This is the base class that handles asynchronous requests that were previously scheduled. You |
| * are responsible for overriding {@link TaskService#onStartTask(TaskParams)}, which is where |
| * you will implement your task logic.</p> |
| * <p>This service executes each incoming task on a {@link android.os.Handler} running on your |
| * application's main thread. This means that you <b>must</b> offload your execution logic to |
| * another thread/handler/{@link android.os.AsyncTask} of your choosing. Not doing so will result |
| * in blocking any future callbacks from the TaskManager - specifically |
| * {@link #onStopTask(android.app.task.TaskParams)}, which is meant to inform you that the |
| * scheduling requirements are no longer being met.</p> |
| */ |
| public abstract class TaskService extends Service { |
| private static final String TAG = "TaskService"; |
| |
| /** |
| * Task services must be protected with this permission: |
| * |
| * <pre class="prettyprint"> |
| * <service android:name="MyTaskService" |
| * android:permission="android.permission.BIND_TASK_SERVICE" > |
| * ... |
| * </service> |
| * </pre> |
| * |
| * <p>If a task service is declared in the manifest but not protected with this |
| * permission, that service will be ignored by the OS. |
| */ |
| public static final String PERMISSION_BIND = |
| "android.permission.BIND_TASK_SERVICE"; |
| |
| /** |
| * Identifier for a message that will result in a call to |
| * {@link #onStartTask(android.app.task.TaskParams)}. |
| */ |
| private final int MSG_EXECUTE_TASK = 0; |
| /** |
| * Message that will result in a call to {@link #onStopTask(android.app.task.TaskParams)}. |
| */ |
| private final int MSG_STOP_TASK = 1; |
| /** |
| * Message that the client has completed execution of this task. |
| */ |
| private final int MSG_TASK_FINISHED = 2; |
| |
| /** Lock object for {@link #mHandler}. */ |
| private final Object mHandlerLock = new Object(); |
| |
| /** |
| * Handler we post tasks to. Responsible for calling into the client logic, and handling the |
| * callback to the system. |
| */ |
| @GuardedBy("mHandlerLock") |
| TaskHandler mHandler; |
| |
| /** Binder for this service. */ |
| ITaskService mBinder = new ITaskService.Stub() { |
| @Override |
| public void startTask(TaskParams taskParams) { |
| ensureHandler(); |
| Message m = Message.obtain(mHandler, MSG_EXECUTE_TASK, taskParams); |
| m.sendToTarget(); |
| } |
| @Override |
| public void stopTask(TaskParams taskParams) { |
| ensureHandler(); |
| Message m = Message.obtain(mHandler, MSG_STOP_TASK, taskParams); |
| m.sendToTarget(); |
| } |
| }; |
| |
| /** @hide */ |
| void ensureHandler() { |
| synchronized (mHandlerLock) { |
| if (mHandler == null) { |
| mHandler = new TaskHandler(getMainLooper()); |
| } |
| } |
| } |
| |
| /** |
| * Runs on application's main thread - callbacks are meant to offboard work to some other |
| * (app-specified) mechanism. |
| * @hide |
| */ |
| class TaskHandler extends Handler { |
| TaskHandler(Looper looper) { |
| super(looper); |
| } |
| |
| @Override |
| public void handleMessage(Message msg) { |
| final TaskParams params = (TaskParams) msg.obj; |
| switch (msg.what) { |
| case MSG_EXECUTE_TASK: |
| try { |
| boolean workOngoing = TaskService.this.onStartTask(params); |
| ackStartMessage(params, workOngoing); |
| } catch (Exception e) { |
| Log.e(TAG, "Error while executing task: " + params.getTaskId()); |
| throw new RuntimeException(e); |
| } |
| break; |
| case MSG_STOP_TASK: |
| try { |
| boolean ret = TaskService.this.onStopTask(params); |
| ackStopMessage(params, ret); |
| } catch (Exception e) { |
| Log.e(TAG, "Application unable to handle onStopTask.", e); |
| throw new RuntimeException(e); |
| } |
| break; |
| case MSG_TASK_FINISHED: |
| final boolean needsReschedule = (msg.arg2 == 1); |
| ITaskCallback callback = params.getCallback(); |
| if (callback != null) { |
| try { |
| callback.taskFinished(params.getTaskId(), needsReschedule); |
| } catch (RemoteException e) { |
| Log.e(TAG, "Error reporting task finish to system: binder has gone" + |
| "away."); |
| } |
| } else { |
| Log.e(TAG, "finishTask() called for a nonexistent task id."); |
| } |
| break; |
| default: |
| Log.e(TAG, "Unrecognised message received."); |
| break; |
| } |
| } |
| |
| private void ackStartMessage(TaskParams params, boolean workOngoing) { |
| final ITaskCallback callback = params.getCallback(); |
| final int taskId = params.getTaskId(); |
| if (callback != null) { |
| try { |
| callback.acknowledgeStartMessage(taskId, workOngoing); |
| } catch(RemoteException e) { |
| Log.e(TAG, "System unreachable for starting task."); |
| } |
| } else { |
| if (Log.isLoggable(TAG, Log.DEBUG)) { |
| Log.d(TAG, "Attempting to ack a task that has already been processed."); |
| } |
| } |
| } |
| |
| private void ackStopMessage(TaskParams params, boolean reschedule) { |
| final ITaskCallback callback = params.getCallback(); |
| final int taskId = params.getTaskId(); |
| if (callback != null) { |
| try { |
| callback.acknowledgeStopMessage(taskId, reschedule); |
| } catch(RemoteException e) { |
| Log.e(TAG, "System unreachable for stopping task."); |
| } |
| } else { |
| if (Log.isLoggable(TAG, Log.DEBUG)) { |
| Log.d(TAG, "Attempting to ack a task that has already been processed."); |
| } |
| } |
| } |
| } |
| |
| /** @hide */ |
| public final IBinder onBind(Intent intent) { |
| return mBinder.asBinder(); |
| } |
| |
| /** |
| * Override this method with the callback logic for your task. Any such logic needs to be |
| * performed on a separate thread, as this function is executed on your application's main |
| * thread. |
| * |
| * @param params Parameters specifying info about this task, including the extras bundle you |
| * optionally provided at task-creation time. |
| * @return True if your service needs to process the work (on a separate thread). False if |
| * there's no more work to be done for this task. |
| */ |
| public abstract boolean onStartTask(TaskParams params); |
| |
| /** |
| * This method is called if the system has determined that you must stop execution of your task |
| * even before you've had a chance to call {@link #taskFinished(TaskParams, boolean)}. |
| * |
| * <p>This will happen if the requirements specified at schedule time are no longer met. For |
| * example you may have requested WiFi with |
| * {@link android.content.Task.Builder#setRequiredNetworkCapabilities(int)}, yet while your |
| * task was executing the user toggled WiFi. Another example is if you had specified |
| * {@link android.content.Task.Builder#setRequiresDeviceIdle(boolean)}, and the phone left its |
| * idle maintenance window. You are solely responsible for the behaviour of your application |
| * upon receipt of this message; your app will likely start to misbehave if you ignore it. One |
| * immediate repercussion is that the system will cease holding a wakelock for you.</p> |
| * |
| * @param params Parameters specifying info about this task. |
| * @return True to indicate to the TaskManager whether you'd like to reschedule this task based |
| * on the retry criteria provided at task creation-time. False to drop the task. Regardless of |
| * the value returned, your task must stop executing. |
| */ |
| public abstract boolean onStopTask(TaskParams params); |
| |
| /** |
| * Callback to inform the TaskManager you've finished executing. This can be called from any |
| * thread, as it will ultimately be run on your application's main thread. When the system |
| * receives this message it will release the wakelock being held. |
| * <p> |
| * You can specify post-execution behaviour to the scheduler here with |
| * <code>needsReschedule </code>. This will apply a back-off timer to your task based on |
| * the default, or what was set with |
| * {@link android.content.Task.Builder#setBackoffCriteria(long, int)}. The original |
| * requirements are always honoured even for a backed-off task. Note that a task running in |
| * idle mode will not be backed-off. Instead what will happen is the task will be re-added |
| * to the queue and re-executed within a future idle maintenance window. |
| * </p> |
| * |
| * @param params Parameters specifying system-provided info about this task, this was given to |
| * your application in {@link #onStartTask(TaskParams)}. |
| * @param needsReschedule True if this task is complete, false if you want the TaskManager to |
| * reschedule you. |
| */ |
| public final void taskFinished(TaskParams params, boolean needsReschedule) { |
| ensureHandler(); |
| Message m = Message.obtain(mHandler, MSG_TASK_FINISHED, params); |
| m.arg2 = needsReschedule ? 1 : 0; |
| m.sendToTarget(); |
| } |
| } |