continue logging to disk if interrupted (wake-lock)

When the app goes out of foreground while logging to disk, e.g., because the screen turns off or another app is started, acquire partial wake-lock and continue logging. If not logging to disk, behavior is unchanged, i.e., updates are suspended. This feature is (particularly) experimental and definitely needs testing and/or a review. See #1
tjanson · Mar 12, 2015 · 10b4a8a · 10b4a8a
1 parent 8751617
commit 10b4a8a
Show file tree

Hide file tree

Showing 3 changed files with 59 additions and 12 deletions.
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
@@ -7,6 +7,7 @@
     <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
     <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
 
     <application
         android:allowBackup="true"

diff --git a/app/src/main/java/com/tomjanson/wifilocationlogger/MainActivity.java b/app/src/main/java/com/tomjanson/wifilocationlogger/MainActivity.java
@@ -7,6 +7,7 @@
 import android.location.Location;
 import android.os.Build;
 import android.os.Bundle;
+import android.os.PowerManager;
 import android.support.annotation.NonNull;
 import android.view.View;
 import android.widget.Button;
@@ -74,7 +75,10 @@ public class MainActivity extends Activity implements
 
     // toggles logging location+wifi to file
     // debug logs may be created regardless of this
-    boolean logToFile = false;
+    boolean loggingToFile = false;
+
+    // wake-lock to (hopefully) continue logging while screen is off
+    PowerManager.WakeLock wakeLock;
 
     // UI Elements
     Button   loggingButton;
@@ -110,6 +114,9 @@ public void onCreate(Bundle savedInstanceState) {
         // restore state on Activity recreation
         updateValuesFromBundle(savedInstanceState);
 
+        PowerManager powerManager = (PowerManager) getSystemService(POWER_SERVICE);
+        wakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "MyWakelockTag");
+
         buildGoogleApiClient();
 
         initWifiScan();
@@ -141,15 +148,28 @@ void updateUI() {
             wifiTV.setText(wifiListString);
         }
 
-        if (logToFile) {
+        if (loggingToFile) {
             loggingButton.setText(R.string.logging_stop);
         } else {
             loggingButton.setText(R.string.logging_start);
         }
     }
 
+    /**
+     * Toggles logging data points to file and aquires wake-lock to do so while screen is off.
+     */
     public void toggleLogging(View view) {
-        logToFile = !logToFile;
+        loggingToFile = !loggingToFile;
+        log.info((loggingToFile ? "En" : "Dis") + "abled logging to disk");
+
+        if (loggingToFile) {
+            wakeLock.acquire();
+            log.debug("Acquired wake-lock");
+        } else if (wakeLock.isHeld()) {
+            wakeLock.release();
+            log.debug("Released wake-lock");
+        }
+
         updateUI();
     }
 
@@ -244,26 +264,33 @@ protected void onResume() {
         if (googleApiClient.isConnected()) {
             startLocationUpdates();
         }
-        this.registerReceiver(wifiBroadcastReceiver, wifiIntentFilter);
-        log.debug("Registered wifiBroadcastReceiver");
-        wifiManager.startScan();
+
+        if (!loggingToFile) {
+            this.registerReceiver(wifiBroadcastReceiver, wifiIntentFilter);
+            log.trace("Registered WifiBroadcastReceiver");
+            wifiManager.startScan();
+        }
     }
 
     @Override
     protected void onPause() {
         super.onPause();
-        this.unregisterReceiver(wifiBroadcastReceiver);
-        log.debug("Unregistered wifiBroadcastReceiver");
-        if (googleApiClient.isConnected()) {
+
+        if (!loggingToFile) {
+            this.unregisterReceiver(wifiBroadcastReceiver);
+            log.debug("Unregistered WifiBroadcastReceiver");
             stopLocationUpdates();
+        } else {
+            log.debug("onPause called, but logging to file; we'll keep going");
         }
     }
 
     @Override
     protected void onStop() {
         super.onStop();
-        if (googleApiClient.isConnected()) {
-            googleApiClient.disconnect();
+
+        if (!loggingToFile) {
+            disconnectGoogleApiClient();
         }
 
         // save preferences or other persisting stuff
@@ -272,6 +299,25 @@ protected void onStop() {
         prefEditor.apply();
     }
 
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+
+        disconnectGoogleApiClient();
+
+        if (loggingToFile) {
+            this.unregisterReceiver(wifiBroadcastReceiver);
+            log.trace("Unregistered WifiBroadcastReceiver");
+        }
+    }
+
+    private void disconnectGoogleApiClient() {
+        if (googleApiClient.isConnected()) {
+            googleApiClient.disconnect();
+            log.trace("GoogleApiClient disconnected");
+        }
+    }
+
     /**
      * Runs when a GoogleApiClient object successfully connects.
      */

diff --git a/app/src/main/java/com/tomjanson/wifilocationlogger/WifiBroadcastReceiver.java b/app/src/main/java/com/tomjanson/wifilocationlogger/WifiBroadcastReceiver.java
@@ -70,7 +70,7 @@ public void run() {
     }
 
     private void log(ScanResult wifi) {
-        if (m.logToFile) {
+        if (m.loggingToFile) {
             m.diskLog.info(m.currentLocation.getLatitude()
                  + "," + m.currentLocation.getLongitude()
                  + "," + m.currentLocation.getAltitude()