Stability improvement: Delaying BLE operations after Bluetooth enabled

app/src/main/java/no/nordicsemi/android/nrftoolbox/profile/BleProfileService.java

@@ -209,6 +209,14 @@ public abstract class BleProfileService extends Service implements BleManagerCal
 		}
 	}
 
+	/**
+	 * Returns a handler that is created in onCreate().
+	 * The handler may be used to postpone execution of some operations or to run them in UI thread.
+	 */
+	protected Handler getHandler() {
+		return mHandler;
+	}
+
 	/**
 	 * Returns the binder implementation. This must return class implementing the additional manager interface that may be used in the bound activity.
 	 *
@@ -361,6 +369,7 @@ public abstract class BleProfileService extends Service implements BleManagerCal
 		mBluetoothDevice = null;
 		mDeviceName = null;
 		mLogSession = null;
+		mHandler = null;
 	}
 
 	/**

app/src/main/java/no/nordicsemi/android/nrftoolbox/profile/multiconnect/BleMulticonnectProfileService.java

@@ -88,7 +88,15 @@ public abstract class BleMulticonnectProfileService extends Service implements B
 
 			switch (state) {
 				case BluetoothAdapter.STATE_ON:
-					onBluetoothEnabled();
+					// On older phones (tested on Nexus 4 with Android 5.0.1) the Bluetooth requires some time
+					// after it has been enabled before some operations can start. Starting the GATT server here
+					// without a delay is very likely to cause a DeadObjectException from BluetoothManager#openGattServer(...).
+					mHandler.postDelayed(new Runnable() {
+						@Override
+						public void run() {
+							onBluetoothEnabled();
+						}
+					}, 600);
 					break;
 				case BluetoothAdapter.STATE_TURNING_OFF:
 				case BluetoothAdapter.STATE_OFF:
@@ -224,6 +232,14 @@ public abstract class BleMulticonnectProfileService extends Service implements B
 		}
 	}
 
+	/**
+	 * Returns a handler that is created in onCreate().
+	 * The handler may be used to postpone execution of some operations or to run them in UI thread.
+	 */
+	protected Handler getHandler() {
+		return mHandler;
+	}
+
 	/**
 	 * Returns the binder implementation. This must return class implementing the additional manager interface that may be used in the bound activity.
 	 *
@@ -360,6 +376,7 @@ public abstract class BleMulticonnectProfileService extends Service implements B
 	public void onDestroy() {
 		super.onDestroy();
 		onServiceStopped();
+		mHandler = null;
 	}
 
 	/**

app/src/main/java/no/nordicsemi/android/nrftoolbox/proximity/ProximityService.java

@@ -73,6 +73,9 @@ public class ProximityService extends BleMulticonnectProfileService implements P
 	 */
 	private List<BluetoothDevice> mDevicesWithAlarm;
 
+	private int mAttempt;
+	private final static int MAX_ATTEMPTS = 1;
+
 	/**
 	 * This local binder is an interface for the bonded activity to operate with the proximity sensor
 	 */
@@ -170,18 +173,33 @@ public class ProximityService extends BleMulticonnectProfileService implements P
 
 	@Override
 	protected void onBluetoothEnabled() {
-		// Start the GATT Server only if Bluetooth is enabled
-		mServerManager.openGattServer(this, new ProximityServerManager.OnServerOpenCallback() {
+		mAttempt = 0;
+		getHandler().post(new Runnable() {
 			@Override
-			public void onGattServerOpen() {
-				// We are now ready to reconnect devices
-				ProximityService.super.onBluetoothEnabled();
-			}
+			public void run() {
+				final Runnable that = this;
+				// Start the GATT Server only if Bluetooth is enabled
+				mServerManager.openGattServer(ProximityService.this, new ProximityServerManager.OnServerOpenCallback() {
+					@Override
+					public void onGattServerOpen() {
+						// We are now ready to reconnect devices
+						ProximityService.super.onBluetoothEnabled();
+					}
 
-			@Override
-			public void onGattServerFailed(final int error) {
-				mServerManager.closeGattServer();
-				showToast(getString(R.string.proximity_server_error, error));
+					@Override
+					public void onGattServerFailed(final int error) {
+						mServerManager.closeGattServer();
+
+						if (mAttempt < MAX_ATTEMPTS) {
+							mAttempt++;
+							getHandler().postDelayed(that, 2000);
+						} else {
+							showToast(getString(R.string.proximity_server_error, error));
+							// GATT server failed to start, but we may connect as a client
+							ProximityService.super.onBluetoothEnabled();
+						}
+					}
+				});
 			}
 		});
 	}