1 files changed, 392 insertions, 0 deletions
diff --git a/java/com/android/voicemailomtp/scheduling/TaskSchedulerService.java b/java/com/android/voicemailomtp/scheduling/TaskSchedulerService.java
new file mode 100644
index 000000000..90b50e913
--- /dev/null
+++ b/java/com/android/voicemailomtp/scheduling/TaskSchedulerService.java
@@ -0,0 +1,392 @@
+/*
+ * Copyright (C) 2016 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 com.android.voicemailomtp.scheduling;
+
+import android.app.AlarmManager;
+import android.app.PendingIntent;
+import android.app.Service;
+import android.content.Context;
+import android.content.Intent;
+import android.os.Binder;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.IBinder;
+import android.os.Looper;
+import android.os.Message;
+import android.os.PowerManager;
+import android.os.PowerManager.WakeLock;
+import android.os.SystemClock;
+import android.support.annotation.MainThread;
+import android.support.annotation.Nullable;
+import android.support.annotation.VisibleForTesting;
+import android.support.annotation.WorkerThread;
+import com.android.voicemailomtp.Assert;
+import com.android.voicemailomtp.NeededForTesting;
+import com.android.voicemailomtp.VvmLog;
+import com.android.voicemailomtp.scheduling.Task.TaskId;
+import java.util.ArrayDeque;
+import java.util.Queue;
+
+/**
+ * A service to queue and run {@link Task} on a worker thread. Only one task will be ran at a time,
+ * and same task cannot exist in the queue at the same time. The service will be started when a
+ * intent is received, and stopped when there are no more tasks in the queue.
+ */
+public class TaskSchedulerService extends Service {
+
+    private static final String TAG = "VvmTaskScheduler";
+
+    private static final String ACTION_WAKEUP = "action_wakeup";
+
+    private static final int READY_TOLERANCE_MILLISECONDS = 100;
+
+    /**
+     * Threshold to determine whether to do a short or long sleep when a task is scheduled in the
+     * future.
+     *
+     * <p>A short sleep will continue to held the wake lock and use {@link
+     * Handler#postDelayed(Runnable, long)} to wait for the next task.
+     *
+     * <p>A long sleep will release the wake lock and set a {@link AlarmManager} alarm. The alarm is
+     * exact and will wake up the device. Note: as this service is run in the telephony process it
+     * does not seem to be restricted by doze or sleep, it will fire exactly at the moment. The
+     * unbundled version should take doze into account.
+     */
+    private static final int SHORT_SLEEP_THRESHOLD_MILLISECONDS = 60_000;
+    /**
+     * When there are no more tasks to be run the service should be stopped. But when all tasks has
+     * finished there might still be more tasks in the message queue waiting to be processed,
+     * especially the ones submitted in {@link Task#onCompleted()}. Wait for a while before stopping
+     * the service to make sure there are no pending messages.
+     */
+    private static final int STOP_DELAY_MILLISECONDS = 5_000;
+    private static final String EXTRA_CLASS_NAME = "extra_class_name";
+
+    private static final String WAKE_LOCK_TAG = "TaskSchedulerService_wakelock";
+
+    // The thread to run tasks on
+    private volatile WorkerThreadHandler mWorkerThreadHandler;
+
+    private Context mContext = this;
+    /**
+     * Used by tests to turn task handling into a single threaded process by calling {@link
+     * Handler#handleMessage(Message)} directly
+     */
+    private MessageSender mMessageSender = new MessageSender();
+
+    private MainThreadHandler mMainThreadHandler;
+
+    private WakeLock mWakeLock;
+
+    /**
+     * Main thread only, access through {@link #getTasks()}
+     */
+    private final Queue<Task> mTasks = new ArrayDeque<>();
+    private boolean mWorkerThreadIsBusy = false;
+
+    private final Runnable mStopServiceWithDelay = new Runnable() {
+        @Override
+        public void run() {
+            VvmLog.d(TAG, "Stopping service");
+            stopSelf();
+        }
+    };
+    /**
+     * Should attempt to run the next task when a task has finished or been added.
+     */
+    private boolean mTaskAutoRunDisabledForTesting = false;
+
+    @VisibleForTesting
+    final class WorkerThreadHandler extends Handler {
+
+        public WorkerThreadHandler(Looper looper) {
+            super(looper);
+        }
+
+        @Override
+        @WorkerThread
+        public void handleMessage(Message msg) {
+            Assert.isNotMainThread();
+            Task task = (Task) msg.obj;
+            try {
+                VvmLog.v(TAG, "executing task " + task);
+                task.onExecuteInBackgroundThread();
+            } catch (Throwable throwable) {
+                VvmLog.e(TAG, "Exception while executing task " + task + ":", throwable);
+            }
+
+            Message schedulerMessage = mMainThreadHandler.obtainMessage();
+            schedulerMessage.obj = task;
+            mMessageSender.send(schedulerMessage);
+        }
+    }
+
+    @VisibleForTesting
+    final class MainThreadHandler extends Handler {
+
+        public MainThreadHandler(Looper looper) {
+            super(looper);
+        }
+
+        @Override
+        @MainThread
+        public void handleMessage(Message msg) {
+            Assert.isMainThread();
+            Task task = (Task) msg.obj;
+            getTasks().remove(task);
+            task.onCompleted();
+            mWorkerThreadIsBusy = false;
+            maybeRunNextTask();
+        }
+    }
+
+    @Override
+    @MainThread
+    public void onCreate() {
+        super.onCreate();
+        mWakeLock = getSystemService(PowerManager.class)
+                .newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, WAKE_LOCK_TAG);
+        mWakeLock.setReferenceCounted(false);
+        HandlerThread thread = new HandlerThread("VvmTaskSchedulerService");
+        thread.start();
+
+        mWorkerThreadHandler = new WorkerThreadHandler(thread.getLooper());
+        mMainThreadHandler = new MainThreadHandler(Looper.getMainLooper());
+    }
+
+    @Override
+    public void onDestroy() {
+        mWorkerThreadHandler.getLooper().quit();
+        mWakeLock.release();
+    }
+
+    @Override
+    @MainThread
+    public int onStartCommand(@Nullable Intent intent, int flags, int startId) {
+        Assert.isMainThread();
+        // maybeRunNextTask() will release the wakelock either by entering a long sleep or stopping
+        // the service.
+        mWakeLock.acquire();
+        if (ACTION_WAKEUP.equals(intent.getAction())) {
+            VvmLog.d(TAG, "woke up by AlarmManager");
+        } else {
+            Task task = createTask(intent, flags, startId);
+            if (task == null) {
+                VvmLog.e(TAG, "cannot create task form intent");
+            } else {
+                addTask(task);
+            }
+        }
+        maybeRunNextTask();
+        // STICKY means the service will be automatically restarted will the last intent if it is
+        // killed.
+        return START_NOT_STICKY;
+    }
+
+    @MainThread
+    @VisibleForTesting
+    void addTask(Task task) {
+        Assert.isMainThread();
+        if (task.getId().id == Task.TASK_INVALID) {
+            throw new AssertionError("Task id was not set to a valid value before adding.");
+        }
+        if (task.getId().id != Task.TASK_ALLOW_DUPLICATES) {
+            Task oldTask = getTask(task.getId());
+            if (oldTask != null) {
+                oldTask.onDuplicatedTaskAdded(task);
+                return;
+            }
+        }
+        mMainThreadHandler.removeCallbacks(mStopServiceWithDelay);
+        getTasks().add(task);
+        maybeRunNextTask();
+    }
+
+    @MainThread
+    @Nullable
+    private Task getTask(TaskId taskId) {
+        Assert.isMainThread();
+        for (Task task : getTasks()) {
+            if (task.getId().equals(taskId)) {
+                return task;
+            }
+        }
+        return null;
+    }
+
+    @MainThread
+    private Queue<Task> getTasks() {
+        Assert.isMainThread();
+        return mTasks;
+    }
+
+    /**
+     * Create an intent that will queue the <code>task</code>
+     */
+    public static Intent createIntent(Context context, Class<? extends Task> task) {
+        Intent intent = new Intent(context, TaskSchedulerService.class);
+        intent.putExtra(EXTRA_CLASS_NAME, task.getName());
+        return intent;
+    }
+
+    @VisibleForTesting
+    @MainThread
+    @Nullable
+    Task createTask(@Nullable Intent intent, int flags, int startId) {
+        Assert.isMainThread();
+        if (intent == null) {
+            return null;
+        }
+        String className = intent.getStringExtra(EXTRA_CLASS_NAME);
+        VvmLog.d(TAG, "create task:" + className);
+        if (className == null) {
+            throw new IllegalArgumentException("EXTRA_CLASS_NAME expected");
+        }
+        try {
+            Task task = (Task) Class.forName(className).newInstance();
+            task.onCreate(mContext, intent, flags, startId);
+            return task;
+        } catch (ClassNotFoundException | IllegalAccessException | InstantiationException e) {
+            throw new IllegalArgumentException(e);
+        }
+    }
+
+    @MainThread
+    private void maybeRunNextTask() {
+        Assert.isMainThread();
+        if (mWorkerThreadIsBusy) {
+            return;
+        }
+        if (mTaskAutoRunDisabledForTesting) {
+            // If mTaskAutoRunDisabledForTesting is true, runNextTask() must be explicitly called
+            // to run the next task.
+            return;
+        }
+
+        runNextTask();
+    }
+
+    @VisibleForTesting
+    @MainThread
+    void runNextTask() {
+        Assert.isMainThread();
+        // The current alarm is no longer valid, a new one will be set up if required.
+        getSystemService(AlarmManager.class).cancel(getWakeupIntent());
+        if (getTasks().isEmpty()) {
+            prepareStop();
+            return;
+        }
+        Long minimalWaitTime = null;
+        for (Task task : getTasks()) {
+            long waitTime = task.getReadyInMilliSeconds();
+            if (waitTime < READY_TOLERANCE_MILLISECONDS) {
+                task.onBeforeExecute();
+                Message message = mWorkerThreadHandler.obtainMessage();
+                message.obj = task;
+                mWorkerThreadIsBusy = true;
+                mMessageSender.send(message);
+                return;
+            } else {
+                if (minimalWaitTime == null || waitTime < minimalWaitTime) {
+                    minimalWaitTime = waitTime;
+                }
+            }
+        }
+        VvmLog.d(TAG, "minimal wait time:" + minimalWaitTime);
+        if (!mTaskAutoRunDisabledForTesting && minimalWaitTime != null) {
+            // No tasks are currently ready. Sleep until the next one should be.
+            // If a new task is added during the sleep the service will wake immediately.
+            sleep(minimalWaitTime);
+        }
+    }
+
+    private void sleep(long timeMillis) {
+        if (timeMillis < SHORT_SLEEP_THRESHOLD_MILLISECONDS) {
+            mMainThreadHandler.postDelayed(new Runnable() {
+                @Override
+                public void run() {
+                    maybeRunNextTask();
+                }
+            }, timeMillis);
+            return;
+        }
+
+        // Tasks does not have a strict timing requirement, use AlarmManager.set() so the OS could
+        // optimize the battery usage. As this service currently run in the telephony process the
+        // OS give it privileges to behave the same as setExact(), but set() is the targeted
+        // behavior once this is unbundled.
+        getSystemService(AlarmManager.class).set(AlarmManager.ELAPSED_REALTIME_WAKEUP,
+                SystemClock.elapsedRealtime() + timeMillis,
+                getWakeupIntent());
+        mWakeLock.release();
+        VvmLog.d(TAG, "Long sleep for " + timeMillis + " millis");
+    }
+
+    private PendingIntent getWakeupIntent() {
+        Intent intent = new Intent(ACTION_WAKEUP, null, this, getClass());
+        return PendingIntent.getService(this, 0, intent, PendingIntent.FLAG_CANCEL_CURRENT);
+    }
+
+    private void prepareStop() {
+        VvmLog.d(TAG,
+                "No more tasks, stopping service if no task are added in "
+                        + STOP_DELAY_MILLISECONDS + " millis");
+        mMainThreadHandler.postDelayed(mStopServiceWithDelay, STOP_DELAY_MILLISECONDS);
+    }
+
+    static class MessageSender {
+
+        public void send(Message message) {
+            message.sendToTarget();
+        }
+    }
+
+    @NeededForTesting
+    void setContextForTest(Context context) {
+        mContext = context;
+    }
+
+    @NeededForTesting
+    void setTaskAutoRunDisabledForTest(boolean value) {
+        mTaskAutoRunDisabledForTesting = value;
+    }
+
+    @NeededForTesting
+    void setMessageSenderForTest(MessageSender sender) {
+        mMessageSender = sender;
+    }
+
+    @NeededForTesting
+    void clearTasksForTest() {
+        mTasks.clear();
+    }
+
+    @Override
+    @Nullable
+    public IBinder onBind(Intent intent) {
+        return new LocalBinder();
+    }
+
+    @NeededForTesting
+    class LocalBinder extends Binder {
+
+        @NeededForTesting
+        public TaskSchedulerService getService() {
+            return TaskSchedulerService.this;
+        }
+    }
+}