fixed exponential backup logic

components/iot-plugins/iot-base-plugin/org.wso2.carbon.device.mgt.iot.input.adapter.mqtt/src/main/java/org/wso2/carbon/device/mgt/iot/input/adapter/mqtt/util/MQTTAdapterListener.java

@@ -69,7 +69,6 @@ public class MQTTAdapterListener implements MqttCallback, Runnable {
 
     private InputEventAdapterListener eventAdapterListener = null;
 
-
     public MQTTAdapterListener(MQTTBrokerConnectionConfiguration mqttBrokerConnectionConfiguration,
                                String topic, String mqttClientId,
                                InputEventAdapterListener inputEventAdapterListener, int tenantId) {
@@ -173,8 +172,10 @@ public class MQTTAdapterListener implements MqttCallback, Runnable {
                     StringEntity requestEntity = new StringEntity(jsonString, ContentType.APPLICATION_JSON);
                     postMethod.setEntity(requestEntity);
                     HttpResponse httpResponse = httpClient.execute(postMethod);
+                    if (httpResponse != null) {
                         String response = MQTTUtil.getResponseString(httpResponse);
                         try {
+                            if (response != null) {
                                 JSONParser jsonParser = new JSONParser();
                                 JSONObject jsonPayload = (JSONObject) jsonParser.parse(response);
                                 String clientId = (String) jsonPayload.get(MQTTEventAdapterConstants.CLIENT_ID);
@@ -183,6 +184,7 @@ public class MQTTAdapterListener implements MqttCallback, Runnable {
                                 AccessTokenInfo accessTokenInfo = jwtClientManagerService.getJWTClient().getAccessToken(
                                         clientId, clientSecret, username, scopes);
                                 connectionOptions.setUserName(accessTokenInfo.getAccessToken());
+                            }
                         } catch (ParseException e) {
                             String msg = "error occurred while parsing client credential payload";
                             log.error(msg, e);
@@ -190,6 +192,7 @@ public class MQTTAdapterListener implements MqttCallback, Runnable {
                             String msg = "error occurred while parsing the response from JWT Client";
                             log.error(msg, e);
                         }
+                    }
                 } catch (MalformedURLException e) {
                     log.error("Invalid dcrUrl : " + dcrUrlString);
                 } catch (KeyManagementException | NoSuchAlgorithmException | KeyStoreException | IOException  e) {
@@ -263,10 +266,10 @@ public class MQTTAdapterListener implements MqttCallback, Runnable {
 
     @Override
     public void run() {
-        int connectionDuration = MQTTEventAdapterConstants.initialReconnectDuration;
+        int connectionDuration = MQTTEventAdapterConstants.INITIAL_RECONNECTION_DURATION;
         while (!connectionSucceeded) {
             try {
-                connectionDuration = connectionDuration * MQTTEventAdapterConstants.reconnectionProgressionFactor;
+                connectionDuration = connectionDuration * MQTTEventAdapterConstants.RECONNECTION_PROGRESS_FACTOR;
                 Thread.sleep(connectionDuration);
                 startListener();
                 connectionSucceeded = true;

components/iot-plugins/iot-base-plugin/org.wso2.carbon.device.mgt.iot.input.adapter.mqtt/src/main/java/org/wso2/carbon/device/mgt/iot/input/adapter/mqtt/util/MQTTEventAdapterConstants.java

@@ -47,8 +47,8 @@ public class MQTTEventAdapterConstants {
     public static final String ADAPTER_CONF_KEEP_ALIVE = "keepAlive";
     public static final int ADAPTER_CONF_DEFAULT_KEEP_ALIVE = 60000;
 
-    public static int initialReconnectDuration = 2000;
+    public static final int INITIAL_RECONNECTION_DURATION = 4000;
-    public static final int reconnectionProgressionFactor = 2;
+    public static final int RECONNECTION_PROGRESS_FACTOR = 2;
 
     public static final String EMPTY_STRING = "";
     public static final String GRANT_TYPE = "urn:ietf:params:oauth:grant-type:jwt-bearer refresh_token";

components/iot-plugins/iot-base-plugin/org.wso2.carbon.device.mgt.iot.input.adapter.xmpp/src/main/java/org/wso2/carbon/device/mgt/iot/input/adapter/xmpp/util/XMPPAdapterListener.java

@@ -203,9 +203,9 @@ public class XMPPAdapterListener implements Runnable {
     @Override
     public void run() {
         while (!connectionSucceeded) {
-            int connectionDuration = XMPPEventAdapterConstants.initialReconnectDuration;
+            int connectionDuration = XMPPEventAdapterConstants.INITIAL_RECONNECTION_DURATION;
             try {
-                connectionDuration = connectionDuration * XMPPEventAdapterConstants.reconnectionProgressionFactor;
+                connectionDuration = connectionDuration * XMPPEventAdapterConstants.RECONNECTION_PROGRESS_FACTOR;
                 Thread.sleep(connectionDuration);
                 startListener();
                 connectionSucceeded = true;

components/iot-plugins/iot-base-plugin/org.wso2.carbon.device.mgt.iot.input.adapter.xmpp/src/main/java/org/wso2/carbon/device/mgt/iot/input/adapter/xmpp/util/XMPPEventAdapterConstants.java

@@ -49,8 +49,8 @@ public class XMPPEventAdapterConstants {
     public static final int DEFAULT_XMPP_PORT = 5222;
     public static final int DEFAULT_TIMEOUT_INTERVAL = 5000;
 
-    public static int initialReconnectDuration = 2000;
+    public static int INITIAL_RECONNECTION_DURATION = 4000;
-    public static final int reconnectionProgressionFactor = 2;
+    public static final int RECONNECTION_PROGRESS_FACTOR = 2;
 
     public static final String DEFAULT = "default";