Show foreground notification for jobs when network is restricted.

Occasionally a job may be run when the app is in a network-restricted
mode, like a form of doze. When this happens, jobs can timeout due to
lack of network access, causing a cascade of job delays. This is
particularly bad in the case of message retrieval.

To prevent this, if a job that normally requires network detects that no
network is available when running, then we start a foreground
notification.

res/values/strings.xml

@@ -371,6 +371,9 @@
     <string name="InviteActivity_no_app_to_share_to">It looks like you don\'t have any apps to share to.</string>
     <string name="InviteActivity_friends_dont_let_friends_text_unencrypted">Friends don\'t let friends chat unencrypted.</string>
 
+    <!-- Job -->
+    <string name="Job_working_in_the_background">Working in the background...</string>
+
     <!-- MessageDetailsRecipient -->
     <string name="MessageDetailsRecipient_failed_to_send">Failed to send</string>
     <string name="MessageDetailsRecipient_new_safety_number">New safety number</string>
@@ -477,6 +480,9 @@
     <!-- PlayServicesProblemFragment -->
     <string name="PlayServicesProblemFragment_the_version_of_google_play_services_you_have_installed_is_not_functioning">The version of Google Play Services you have installed is not functioning correctly.  Please reinstall Google Play Services and try again.</string>
 
+    <!-- PushNotificationReceiveJob -->
+    <string name="PushNotificationReceiveJob_retrieving_a_message">Retrieving a message...</string>
+
     <!-- RatingManager -->
     <string name="RatingManager_rate_this_app">Rate this app</string>
     <string name="RatingManager_if_you_enjoy_using_this_app_please_take_a_moment">If you enjoy using this app, please take a moment to help us by rating it.</string>
@@ -556,6 +562,9 @@
     <string name="SearchFragment_header_contacts">Contacts</string>
     <string name="SearchFragment_header_messages">Messages</string>
 
+    <!-- SendJob -->
+    <string name="SendJob_sending_a_message">Sending a message...</string>
+
     <!-- SharedContactDetailsActivity -->
     <string name="SharedContactDetailsActivity_add_to_contacts">Add to Contacts</string>
     <string name="SharedContactDetailsActivity_invite_to_signal">Invite to Signal</string>

src/org/thoughtcrime/securesms/jobmanager/Job.java

@@ -5,10 +5,13 @@ import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 
 import org.thoughtcrime.securesms.ApplicationContext;
+import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.jobmanager.dependencies.ContextDependent;
+import org.thoughtcrime.securesms.jobmanager.requirements.NetworkRequirement;
 import org.thoughtcrime.securesms.jobs.requirements.MasterSecretRequirement;
 import org.thoughtcrime.securesms.jobs.requirements.SqlCipherMigrationRequirement;
 import org.thoughtcrime.securesms.logging.Log;
+import org.thoughtcrime.securesms.service.GenericForegroundService;
 
 import java.io.Serializable;
 import java.util.UUID;
@@ -26,6 +29,7 @@ public abstract class Job extends Worker implements Serializable {
   static final String KEY_RETRY_COUNT            = "Job_retry_count";
   static final String KEY_RETRY_UNTIL            = "Job_retry_until";
   static final String KEY_SUBMIT_TIME            = "Job_submit_time";
+  static final String KEY_REQUIRES_NETWORK       = "Job_requires_network";
   static final String KEY_REQUIRES_MASTER_SECRET = "Job_requires_master_secret";
   static final String KEY_REQUIRES_SQLCIPHER     = "Job_requires_sqlcipher";
 
@@ -58,10 +62,19 @@ public abstract class Job extends Worker implements Serializable {
 
     initialize(new SafeData(data));
 
+    boolean foregroundRunning = false;
+
     try {
       if (withinRetryLimits(data)) {
         if (requirementsMet(data)) {
+          if (needsForegroundService(data)) {
+            Log.i(TAG, "Running a foreground service with description '" + getDescription() + "' to aid in job execution." + logSuffix());
+            GenericForegroundService.startForegroundTask(getApplicationContext(), getDescription());
+            foregroundRunning = true;
+          }
+
           onRun();
+
           log("Successfully completed." + logSuffix());
           return Result.SUCCESS;
         } else {
@@ -79,6 +92,11 @@ public abstract class Job extends Worker implements Serializable {
       }
       warn("Failing due to an exception." + logSuffix(), e);
       return cancel();
+    } finally {
+      if (foregroundRunning) {
+        Log.i(TAG, "Stopping the foreground service." + logSuffix());
+        GenericForegroundService.stopForegroundTask(getApplicationContext());
+      }
     }
   }
 
@@ -95,6 +113,14 @@ public abstract class Job extends Worker implements Serializable {
     onAdded();
   }
 
+  /**
+   * @return A string that represents what the task does. Will be shown in a foreground notification
+   *         if necessary.
+   */
+  protected String getDescription() {
+    return getApplicationContext().getString(R.string.Job_working_in_the_background);
+  }
+
   /**
    * Called after a run has finished and we've determined a retry is required, but before the next
    * attempt is run.
@@ -158,7 +184,7 @@ public abstract class Job extends Worker implements Serializable {
     return Result.SUCCESS;
   }
 
-  private boolean requirementsMet(Data data) {
+  private boolean requirementsMet(@NonNull Data data) {
     boolean met = true;
 
     if (data.getBoolean(KEY_REQUIRES_MASTER_SECRET, false)) {
@@ -172,7 +198,7 @@ public abstract class Job extends Worker implements Serializable {
     return met;
   }
 
-  private boolean withinRetryLimits(Data data) {
+  private boolean withinRetryLimits(@NonNull Data data) {
     int  retryCount = data.getInt(KEY_RETRY_COUNT, 0);
     long retryUntil = data.getLong(KEY_RETRY_UNTIL, 0);
 
@@ -183,6 +209,13 @@ public abstract class Job extends Worker implements Serializable {
     return System.currentTimeMillis() < retryUntil;
   }
 
+  private boolean needsForegroundService(@NonNull Data data) {
+    NetworkRequirement networkRequirement = new NetworkRequirement(getApplicationContext());
+    boolean            requiresNetwork    = data.getBoolean(KEY_REQUIRES_NETWORK, false);
+
+    return requiresNetwork && !networkRequirement.isPresent();
+  }
+
   private void log(@NonNull String message) {
     log(message, null);
   }

src/org/thoughtcrime/securesms/jobmanager/JobManager.java

@@ -41,6 +41,7 @@ public class JobManager {
       Data.Builder dataBuilder = new Data.Builder().putInt(Job.KEY_RETRY_COUNT, jobParameters.getRetryCount())
                                                    .putLong(Job.KEY_RETRY_UNTIL, jobParameters.getRetryUntil())
                                                    .putLong(Job.KEY_SUBMIT_TIME, System.currentTimeMillis())
+                                                   .putBoolean(Job.KEY_REQUIRES_NETWORK, jobParameters.requiresNetwork())
                                                    .putBoolean(Job.KEY_REQUIRES_MASTER_SECRET, jobParameters.requiresMasterSecret())
                                                    .putBoolean(Job.KEY_REQUIRES_SQLCIPHER, jobParameters.requiresSqlCipher());
       Data data = job.serialize(dataBuilder);

src/org/thoughtcrime/securesms/jobs/PushNotificationReceiveJob.java

@@ -3,6 +3,7 @@ package org.thoughtcrime.securesms.jobs;
 import android.content.Context;
 import android.support.annotation.NonNull;
 
+import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.dependencies.InjectableType;
 import org.thoughtcrime.securesms.jobmanager.JobParameters;
 import org.thoughtcrime.securesms.jobmanager.SafeData;
@@ -43,6 +44,11 @@ public class PushNotificationReceiveJob extends PushReceivedJob implements Injec
     return dataBuilder.build();
   }
 
+  @Override
+  protected String getDescription() {
+    return context.getString(R.string.PushNotificationReceiveJob_retrieving_a_message);
+  }
+
   @Override
   public void onRun() throws IOException {
     receiver.retrieveMessages(new SignalServiceMessageReceiver.MessageReceivedCallback() {

src/org/thoughtcrime/securesms/jobs/SendJob.java

@@ -4,6 +4,7 @@ import android.content.Context;
 import android.support.annotation.NonNull;
 
 import org.thoughtcrime.securesms.BuildConfig;
+import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.TextSecureExpiredException;
 import org.thoughtcrime.securesms.attachments.Attachment;
 import org.thoughtcrime.securesms.crypto.MasterSecret;
@@ -31,6 +32,11 @@ public abstract class SendJob extends MasterSecretJob {
     super(context, parameters);
   }
 
+  @Override
+  protected String getDescription() {
+    return context.getString(R.string.SendJob_sending_a_message);
+  }
+
   @Override
   public final void onRun(MasterSecret masterSecret) throws Exception {
     if (Util.getDaysTillBuildExpiry() <= 0) {