Use a reference count with SensorManagers created by SensorManagerFactory

MyTracks/src/com/google/android/apps/mytracks/SensorStateActivity.java

@@ -168,8 +168,6 @@ public class SensorStateActivity extends Activity {
     // If no temp sensor manager is present, create one, and start it.
     if (tempSensorManager == null) {
       tempSensorManager = SensorManagerFactory.getSensorManager(this);
-      if (tempSensorManager != null)
-        tempSensorManager.onStartTrack();
     }
 
     //  If a temp sensor manager is available, use states from temp sensor
@@ -226,7 +224,7 @@ public class SensorStateActivity extends Activity {
    */
   private void stopTempSensorManager() {
     if (tempSensorManager != null) {
-      tempSensorManager.shutdown();
+      SensorManagerFactory.releaseSensorManager(tempSensorManager);
       tempSensorManager = null;
     }
   }

MyTracks/src/com/google/android/apps/mytracks/services/TrackRecordingService.java

@@ -358,7 +358,7 @@ public class TrackRecordingService extends Service {
     unregisterLocationListener();
     shutdownTaskExecutors();
     if (sensorManager != null) {
-      sensorManager.shutdown();
+      SensorManagerFactory.releaseSensorManager(sensorManager);
       sensorManager = null;
     }
 
@@ -602,9 +602,6 @@ public class TrackRecordingService extends Service {
     showNotification();
     registerLocationListener();
     sensorManager = SensorManagerFactory.getSensorManager(this);    
-    if (sensorManager != null) {
-      sensorManager.onStartTrack();
-    }
 
     // Reset the number of auto-resume retries.
     setAutoResumeTrackRetries(0);
@@ -1038,7 +1035,7 @@ public class TrackRecordingService extends Service {
     prefManager.setRecordingTrack(recordingTrackId = -1);
 
     if (sensorManager != null) {
-      sensorManager.shutdown();
+      SensorManagerFactory.releaseSensorManager(sensorManager);
       sensorManager = null;
     }
 

MyTracks/src/com/google/android/apps/mytracks/services/sensors/SensorManagerFactory.java

@@ -35,7 +35,7 @@ public class SensorManagerFactory {
   }
 
   /**
-   * Get a new sensor manager.
+   * Get and start a new sensor manager.
    * @param context Context to fetch system preferences.
    * @return The sensor manager that corresponds to the sensor type setting.
    */
@@ -52,18 +52,59 @@ public class SensorManagerFactory {
     Log.i(Constants.TAG, "Creating sensor of type: " + sensor);
 
     if (sensor == null) {
+      reset();
       return null;
-    } else if (sensor.equals(context.getString(R.string.sensor_type_value_ant))) {
+    }
-      return new AntDirectSensorManager(context);
+    if (sensor.equals(activeSensorType)) {
+      Log.i(Constants.TAG, "Returning existing sensor manager.");
+      refCount++;
+      return activeSensorManager;
+    }
+    reset();
+
+    if (sensor.equals(context.getString(R.string.sensor_type_value_ant))) {
+      activeSensorManager = new AntDirectSensorManager(context);
     } else if (sensor.equals(context.getString(R.string.sensor_type_value_srm_ant_bridge))) {
-      return new AntSrmBridgeSensorManager(context);
+      activeSensorManager = new AntSrmBridgeSensorManager(context);
     } else if (sensor.equals(context.getString(R.string.sensor_type_value_zephyr))) {
-      return new ZephyrSensorManager(context);
+      activeSensorManager = new ZephyrSensorManager(context);
     } else if (sensor.equals(context.getString(R.string.sensor_type_value_polar))) {
-      return new PolarSensorManager(context);
+      activeSensorManager = new PolarSensorManager(context);
     } else  {
       Log.w(Constants.TAG, "Unable to find sensor type: " + sensor);      
       return null;
     }
+    activeSensorType = sensor;
+    refCount = 1;
+    activeSensorManager.onStartTrack();
+    return activeSensorManager;
   }
+
+  /**
+   * Finish using a sensor manager.
+   */
+
+  public static void releaseSensorManager(SensorManager sensorManager) {
+    Log.i(Constants.TAG, "releaseSensorManager: " + activeSensorType + " " + refCount);
+    if (sensorManager != activeSensorManager) {
+      Log.e(Constants.TAG, "invalid parameter to releaseSensorManager");
+    }
+    if (--refCount > 0) {
+      return;
+    }
+    reset();
+  }
+
+  private static void reset() {
+    activeSensorType = null;
+    if (activeSensorManager != null) {
+      activeSensorManager.shutdown();
+    }
+    activeSensorManager = null;
+    refCount = 0;
+  }
+
+  private static String activeSensorType = null;
+  private static SensorManager activeSensorManager = null;
+  private static int refCount = 0;
 }

MyTracksTest/src/com/google/android/apps/mytracks/services/sensors/SensorManagerFactoryTest.java

@@ -52,5 +52,6 @@ public class SensorManagerFactoryTest extends AndroidTestCase {
     SensorManager sm = SensorManagerFactory.getSensorManager(getContext());
     assertNotNull(sm);
     assertTrue(c.isInstance(sm));
+    SensorManagerFactory.releaseSensorManager(sm);
   }
 }