changed log from printing stack trace to meaning logs stating waiting for either broker or key manager

components/extensions/cdmf-transport-adapters/input/org.wso2.carbon.device.mgt.input.adapter.mqtt/src/main/java/org/wso2/carbon/device/mgt/input/adapter/mqtt/util/MQTTAdapterListener.java

@@ -24,6 +24,7 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.http.HttpResponse;
 import org.apache.http.client.HttpClient;
 import org.apache.http.client.methods.HttpPost;
+import org.apache.http.conn.HttpHostConnectException;
 import org.apache.http.entity.ContentType;
 import org.apache.http.entity.StringEntity;
 import org.apache.http.message.BasicHeader;
@@ -131,7 +132,7 @@ public class MQTTAdapterListener implements MqttCallback, Runnable {
         }
     }
 
-    public void startListener() throws MqttException {
+    public boolean startListener() throws MqttException {
         if (this.mqttBrokerConnectionConfiguration.getUsername() != null &&
                 this.mqttBrokerConnectionConfiguration.getDcrUrl() != null) {
             String username = this.mqttBrokerConnectionConfiguration.getUsername();
@@ -182,21 +183,29 @@ public class MQTTAdapterListener implements MqttCallback, Runnable {
                             log.error(msg, e);
                         }
                     }
+                } catch (HttpHostConnectException e) {
+                    log.error("Keymanager is unreachable, Waiting....");
+                    return false;
                 } catch (MalformedURLException e) {
                     log.error("Invalid dcrUrl : " + dcrUrlString);
+                    return false;
                 } catch (JWTClientException | UserStoreException e) {
                     log.error("Failed to create an oauth token with jwt grant type.", e);
+                    return false;
                 } catch (NoSuchAlgorithmException | KeyManagementException | KeyStoreException | IOException e) {
                     log.error("Failed to create a http connection.", e);
+                    return false;
                 }
             }
         }
         try {
             mqttClient.connect(connectionOptions);
         } catch (MqttException e) {
-            log.error("Broker is unreachable, Waiting.....");
+            log.warn("Broker is unreachable, Waiting.....");
+            return false;
         }
         mqttClient.subscribe(topic);
+        return true;
 
     }
 
@@ -271,10 +280,14 @@ public class MQTTAdapterListener implements MqttCallback, Runnable {
         while (!connectionSucceeded) {
             try {
                 connectionDuration = connectionDuration * MQTTEventAdapterConstants.RECONNECTION_PROGRESS_FACTOR;
+                if (connectionDuration > MQTTEventAdapterConstants.MAXIMUM_RECONNECTION_DURATION) {
+                    connectionDuration = MQTTEventAdapterConstants.MAXIMUM_RECONNECTION_DURATION;
+                }
                 Thread.sleep(connectionDuration);
-                startListener();
+                if (startListener()) {
                     connectionSucceeded = true;
                     log.info("MQTT Connection successful");
+                }
             } catch (InterruptedException e) {
                 log.error("Interruption occurred while waiting for reconnection", e);
             } catch (MqttException e) {

components/extensions/cdmf-transport-adapters/input/org.wso2.carbon.device.mgt.input.adapter.mqtt/src/main/java/org/wso2/carbon/device/mgt/input/adapter/mqtt/util/MQTTEventAdapterConstants.java

@@ -50,6 +50,7 @@ public class MQTTEventAdapterConstants {
 
     public static final int INITIAL_RECONNECTION_DURATION = 4000;
     public static final int RECONNECTION_PROGRESS_FACTOR = 2;
+    public static final int MAXIMUM_RECONNECTION_DURATION = 60000;
 
     public static final String EMPTY_STRING = "";
     public static final String GRANT_TYPE_PARAM_NAME = "grant_type";