[Android] Adding scheduling through GcmNetworkManager

components/background_task_scheduler/android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskSchedulerPrefs.java

+// Copyright 2017 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.components.background_task_scheduler;
+
+import android.content.SharedPreferences;
+
+import org.chromium.base.ContextUtils;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Class handling shared preference entries for BackgroundTaskScheduler.
+ */
+public class BackgroundTaskSchedulerPrefs {
+    private static final String TAG = "BTSPrefs";
+    private static final String KEY_SCHEDULED_TASKS = "bts_scheduled_tasks";
+    private static final String KEY_LAST_OS_VERSION = "bts_last_os_version";
+    private static final String KEY_LAST_APP_VERSION = "bts_last_app_version";
+    private static final String ENTRY_SEPARATOR = ":";
+
+    /** Adds a task to scheduler's preferences, so that it can be rescheduled with OS upgrade. */
+    public static void addScheduledTask(TaskInfo taskInfo) {
+        SharedPreferences prefs = ContextUtils.getAppSharedPreferences();
+        Set<String> scheduledTasks =
+                prefs.getStringSet(KEY_SCHEDULED_TASKS, new HashSet<String>(1));
+        String prefsEntry = toSharedPreferenceEntry(taskInfo);
+        if (scheduledTasks.contains(prefsEntry)) return;
+
+        // Set returned from getStringSet() should not be modified.
+        scheduledTasks = new HashSet<>(scheduledTasks);
+        scheduledTasks.add(prefsEntry);
+        updateScheduledTasks(prefs, scheduledTasks);
+    }
+
+    /** Removes a task from scheduler's preferences. */
+    public static void removeScheduledTask(int taskId) {
+        SharedPreferences prefs = ContextUtils.getAppSharedPreferences();
+        Set<String> scheduledTasks = prefs.getStringSet(KEY_SCHEDULED_TASKS, new HashSet<String>());
+
+        String entryToRemove = null;
+        String taskSuffix = ENTRY_SEPARATOR + taskId;
+        for (String entry : scheduledTasks) {
+            if (entry.endsWith(taskSuffix)) {
+                entryToRemove = entry;
+                break;
+            }
+        }
+
+        // Entry matching taskId was not found.
+        if (entryToRemove == null) return;
+
+        // Set returned from getStringSet() should not be modified.
+        scheduledTasks = new HashSet<>(scheduledTasks);
+        scheduledTasks.remove(entryToRemove);
+        updateScheduledTasks(prefs, scheduledTasks);
+    }
+
+    /** Gets a set of scheduled task class names. */
+    public static Set<String> getScheduledTasks() {
+        SharedPreferences prefs = ContextUtils.getAppSharedPreferences();
+        Set<String> prefsEntries = prefs.getStringSet(KEY_SCHEDULED_TASKS, new HashSet<String>(1));
+        Set<String> scheduledTasksClassNames = new HashSet<>(prefsEntries.size());
+        for (String entry : prefsEntries) {
+            String[] entryParts = entry.split(ENTRY_SEPARATOR);
+            if (entryParts.length != 2 || entryParts[0] == null || entryParts[0].isEmpty()) {
+                continue;
+            }
+            scheduledTasksClassNames.add(entryParts[0]);
+        }
+
+        return scheduledTasksClassNames;
+    }
+
+    private static void updateScheduledTasks(SharedPreferences prefs, Set<String> tasks) {
+        SharedPreferences.Editor editor = prefs.edit();
+        editor.putStringSet(KEY_SCHEDULED_TASKS, tasks);
+        editor.apply();
+    }
+
+    /**
+     * Converts a task info to a shared preference entry in the format:
+     * BACKGROUND_TASK_CLASS_NAME:TASK_ID.
+     * Task ID is necessary to be able to remove the entries from the shared preferences.
+     */
+    private static String toSharedPreferenceEntry(TaskInfo taskInfo) {
+        return taskInfo.getBackgroundTaskClass().getName() + ENTRY_SEPARATOR + taskInfo.getTaskId();
+    }
+}