Experimental setting to keep a wakelock while Syncthing native binary is running

src/main/AndroidManifest.xml

@@ -10,6 +10,7 @@
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
     <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
 
     <application
         android:allowBackup="false"

src/main/java/com/nutomic/syncthingandroid/fragments/SettingsFragment.java

@@ -58,6 +58,7 @@ public class SettingsFragment extends PreferenceFragment
     private CheckBoxPreference mSyncOnlyWifi;
     private WifiSsidPreference mSyncOnlyOnSSIDs;
     private CheckBoxPreference mUseRoot;
+    private CheckBoxPreference mKeepWakelock;
     private PreferenceScreen mOptionsScreen;
     private PreferenceScreen mGuiScreen;
     private SyncthingService mSyncthingService;
@@ -134,6 +135,7 @@ public class SettingsFragment extends PreferenceFragment
         mSyncOnlyOnSSIDs = (WifiSsidPreference) findPreference(SyncthingService.PREF_SYNC_ONLY_WIFI_SSIDS);
         mSyncOnlyOnSSIDs.setDefaultValue(new TreeSet<String>()); // default to empty list
         mUseRoot = (CheckBoxPreference) findPreference(SyncthingService.PREF_USE_ROOT);
+        mKeepWakelock = (CheckBoxPreference) findPreference(SyncthingService.PREF_USE_WAKE_LOCK);
         Preference appVersion = screen.findPreference(APP_VERSION_KEY);
         mOptionsScreen = (PreferenceScreen) screen.findPreference(SYNCTHING_OPTIONS_KEY);
         mGuiScreen = (PreferenceScreen) screen.findPreference(SYNCTHING_GUI_KEY);
@@ -153,6 +155,7 @@ public class SettingsFragment extends PreferenceFragment
         mSyncOnlyWifi.setOnPreferenceChangeListener(this);
         mSyncOnlyOnSSIDs.setOnPreferenceChangeListener(this);
         mUseRoot.setOnPreferenceClickListener(this);
+        mKeepWakelock.setOnPreferenceClickListener(this);
         screen.findPreference(EXPORT_CONFIG).setOnPreferenceClickListener(this);
         screen.findPreference(IMPORT_CONFIG).setOnPreferenceClickListener(this);
         screen.findPreference(SYNCTHING_RESET).setOnPreferenceClickListener(this);
@@ -358,6 +361,9 @@ public class SettingsFragment extends PreferenceFragment
                     mSyncthingService.getApi().requireRestart(getActivity());
                 }
                 return true;
+            case SyncthingService.PREF_USE_WAKE_LOCK:
+                mSyncthingService.getApi().requireRestart(getActivity());
+                return true;
             case EXPORT_CONFIG:
                 new AlertDialog.Builder(getActivity())
                         .setMessage(R.string.dialog_confirm_export)

src/main/java/com/nutomic/syncthingandroid/syncthing/SyncthingRunnable.java

@@ -4,6 +4,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.os.Environment;
+import android.os.PowerManager;
 import android.preference.PreferenceManager;
 import android.text.TextUtils;
 import android.util.Log;
@@ -95,7 +96,14 @@ public class SyncthingRunnable implements Runnable {
         }
         // Loop Syncthing
         Process process = null;
+        // Potential fix for #498, keep the CPU running while native binary is running
+        PowerManager pm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
+        PowerManager.WakeLock wakeLock = useWakeLock()
+                ? pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, TAG)
+                : null;
         try {
+            if (wakeLock != null)
+                wakeLock.acquire();
             // Loop to handle Syncthing restarts (these always have an error code of 3).
             do {
                 ProcessBuilder pb = (useRoot())
@@ -132,6 +140,8 @@ public class SyncthingRunnable implements Runnable {
         } catch (IOException | InterruptedException e) {
             Log.e(TAG, "Failed to execute syncthing binary or read output", e);
         } finally {
+            if (wakeLock != null)
+                wakeLock.release();
             if (process != null)
                 process.destroy();
             if (ret != 0) {
@@ -149,6 +159,14 @@ public class SyncthingRunnable implements Runnable {
         return sp.getBoolean(SyncthingService.PREF_USE_ROOT, false) && Shell.SU.available();
     }
 
+    /**
+     * Returns true if the experimental setting for using wake locks has been enabled in settings.
+     */
+    private boolean useWakeLock() {
+        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(mContext);
+        return sp.getBoolean(SyncthingService.PREF_USE_WAKE_LOCK, false);
+    }
+
     /**
      * Look for a running libsyncthing.so process and nice its IO.
      */

src/main/java/com/nutomic/syncthingandroid/syncthing/SyncthingService.java

@@ -94,6 +94,7 @@ public class SyncthingService extends Service implements
     public static final String PREF_SYNC_ONLY_CHARGING       = "sync_only_charging";
     public static final String PREF_USE_ROOT                 = "use_root";
     private static final String PREF_NOTIFICATION_TYPE       = "notification_type";
+    public static final String PREF_USE_WAKE_LOCK            = "wakelock_while_binary_running";
 
     private static final int NOTIFICATION_ACTIVE = 1;
 

src/main/res/values/strings.xml

@@ -296,6 +296,12 @@ Please report any problems you encounter via Github.</string>
 
     <string name="export_config">Export Configuration</string>
 
+    <string name="experimental_settings">Experimental</string>
+
+    <string name="keep_wakelock_while_binary_running">Keep the CPU awake while Syncthing is running</string>
+
+    <string name="keep_wakelock_while_binary_running_summary">Use this setting if you experience unexpected disconnects while operating on battery. This will result in increased battery consumption.</string>
+
     <!-- Toast shown after config was successfully exported -->
     <string name="config_export_successful">Config was exported to %1$s</string>
 

src/main/res/xml/app_settings.xml

@@ -147,6 +147,18 @@
             android:title="@string/streset_title"
             android:singleLine="true" />
 
+        <PreferenceScreen
+            android:key="syncthing_experimental"
+            android:title="@string/experimental_settings">
+
+            <CheckBoxPreference
+                android:key="wakelock_while_binary_running"
+                android:title="@string/keep_wakelock_while_binary_running"
+                android:summary="@string/keep_wakelock_while_binary_running_summary"
+                android:defaultValue="false" />
+
+        </PreferenceScreen>
+
     </PreferenceCategory>
 
     <PreferenceCategory