[Offline pages] Creating BackgroundJobScheduler, which uses JobScheduler

chrome/android/java/src/org/chromium/chrome/browser/offlinepages/BackgroundScheduler.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.offlinepages;
 
 import android.content.Context;
-import android.os.Bundle;
-
-import com.google.android.gms.gcm.GcmNetworkManager;
-import com.google.android.gms.gcm.OneoffTask;
-import com.google.android.gms.gcm.Task;
-
-import org.chromium.chrome.browser.ChromeBackgroundService;
 
 /**
  * The background scheduler class is for setting GCM Network Manager tasks.
  */
-public class BackgroundScheduler {
+public abstract class BackgroundScheduler {
     private static final long ONE_WEEK_IN_SECONDS = 60 * 60 * 24 * 7;

[nyquist, 2017/02/16 23:49:32]

Nit: TimeUnit.DAYS.toSeconds(7) ?

[fgorski, 2017/02/17 22:31:15]

Done.

     private static final long NO_DELAY = 0;
     private static final boolean OVERWRITE = true;
 
     /**
-     * For the given Triggering conditions, start a new GCM Network Manager request.
+     * Context used by the scheduler to access services. Extracted to a field, to clean up method
+     * signatures.
      */
-    public static void schedule(Context context, TriggerConditions triggerConditions) {
-        schedule(context, triggerConditions, NO_DELAY, OVERWRITE);
+    private Context mContext;
+
+    /**
+     * Provides an instance of BackgroundScheduler for given context and current API level.
+     * <p>
+     * Warning: Don't cache the returned value, as it is bound to {@code context}. Consumers should
+     * simply get an instance every time.
+     * @return An instance of BackgroundScheduler.
+     */
+    public static BackgroundScheduler getInstance(Context context) {
+        // TODO(fgorski): Enable JobScheduler for >= N_MR1 once service implemented.

[nyquist, 2017/02/16 23:49:32]

If a user upgrades the OS, do we need to force-cancel the old GCM-based jobs
before scheduling new ones? You don't have to address that in this CL though,
but maybe food for thought.

[fgorski, 2017/02/17 22:31:15]

We thought about that:

The first job that comes will be from Gcm. The subsequent scheduling will use
JobScheduler. We can detect the switch and release the wake-lock immediately
without doing any work.
Will that work? Or do you think the first job may not even be invoked?

[nyquist, 2017/02/21 18:40:13]

Yeah, I think that should work. And yeah; I do think the job should be invoked
by gcm. Doing the switchover at that time should be fine.

It should be even more better if it happened automatically, but that might not
be easy, given we don't have access to the original JobInfo / TaskInfo, so you
running your own thing immediately should work.

+        return new BackgroundGcmScheduler(context);
+    }
+
+    protected BackgroundScheduler(Context context) {
+        mContext = context;
+    }
+
+    /** Schedules a GCM Network Manager task for provided triggering conditions. */
+    public void schedule(TriggerConditions triggerConditions) {
+        scheduleImpl(triggerConditions, NO_DELAY, ONE_WEEK_IN_SECONDS, OVERWRITE);
     }
 
     /**
      * If there is no currently scheduled task, then start a GCM Network Manager request
-     * for the given Triggering conditions but delayed to run after {@code delayStartSecs}.
+     * for the given Triggering conditions but delayed to run after {@code delayStartSeconds}.
      * Typically, the Request Coordinator will overwrite this task after task processing
      * and/or queue updates. This is a backup task in case processing is killed by the
      * system.
      */
-    public static void backupSchedule(
-            Context context, TriggerConditions triggerConditions, long delayStartSecs) {
-        schedule(context, triggerConditions, delayStartSecs, !OVERWRITE);
+    public void scheduleBackup(TriggerConditions triggerConditions, long delayStartSeconds) {
+        scheduleImpl(triggerConditions, delayStartSeconds, ONE_WEEK_IN_SECONDS, !OVERWRITE);
     }
 
-    /**
-     * Cancel any outstanding GCM Network Manager requests.
-     */
-    public static void unschedule(Context context) {
-        // Get the GCM Network Scheduler.
-        GcmNetworkManager gcmNetworkManager = GcmNetworkManager.getInstance(context);
-        gcmNetworkManager.cancelTask(OfflinePageUtils.TASK_TAG, ChromeBackgroundService.class);
-    }
+    /** Cancel any outstanding GCM Network Manager requests. */
+    public abstract void cancel();
 
     /**
      * For the given Triggering conditions, start a new GCM Network Manager request allowed
      * to run after {@code delayStartSecs} seconds.
      */
-    private static void schedule(Context context, TriggerConditions triggerConditions,
-            long delayStartSecs, boolean overwrite) {
-        // Get the GCM Network Scheduler.
-        GcmNetworkManager gcmNetworkManager = GcmNetworkManager.getInstance(context);
+    protected abstract void scheduleImpl(TriggerConditions triggerConditions,
+            long delayStartSeconds, long executionDeadlineSeconds, boolean overwrite);
 
-        Bundle taskExtras = new Bundle();
-        TaskExtrasPacker.packTimeInBundle(taskExtras);
-        TaskExtrasPacker.packTriggerConditionsInBundle(taskExtras, triggerConditions);
-
-        Task task = new OneoffTask.Builder()
-                            .setService(ChromeBackgroundService.class)
-                            .setExecutionWindow(delayStartSecs, ONE_WEEK_IN_SECONDS)
-                            .setTag(OfflinePageUtils.TASK_TAG)
-                            .setUpdateCurrent(overwrite)
-                            .setRequiredNetwork(triggerConditions.requireUnmeteredNetwork()
-                                            ? Task.NETWORK_STATE_UNMETERED
-                                            : Task.NETWORK_STATE_CONNECTED)
-                            .setRequiresCharging(triggerConditions.requirePowerConnected())
-                            .setExtras(taskExtras)
-                            .build();
-
-        gcmNetworkManager.schedule(task);
+    /** @return Context used to access OS services. */
+    protected Context getContext() {
+        return mContext;
     }
 
     /**
      * Get the latest power conditions from the android APIs.
      */
     public static boolean getPowerConditions(Context context) {
         return OfflinePageUtils.getPowerConditions(context);
     }
 
     /**
      * Get the latest battery conditions from the android APIs.
      */
     public static int getBatteryConditions(Context context) {
         return OfflinePageUtils.getBatteryConditions(context);
     }
 
     /**
      * Get the latest network conditions from the android APIs.
      */
     public static int getNetworkConditions(Context context) {
         return OfflinePageUtils.getNetworkConditions(context);
     }
 }