org.camunda.bpm.client.backoff.ExponentialErrorBackoffStrategy Maven / Gradle / Ivy
/*
* Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
* under one or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information regarding copyright
* ownership. Camunda licenses this file to you under the Apache License,
* Version 2.0; you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.camunda.bpm.client.backoff;
import org.camunda.bpm.client.exception.ExternalTaskClientException;
import org.camunda.bpm.client.task.ExternalTask;
import java.util.List;
/**
* Provides an exponential backoff strategy when an error occurs fetching external tasks.
*
*
Note this strategy does not provide any backoff when no external tasks are received. It
* should therefore only be used with long polling (asyncResponseTimeout) to ensure appropriate
* throttling of requests.
*/
public class ExponentialErrorBackoffStrategy implements ErrorAwareBackoffStrategy {
protected long initTime;
protected float factor;
protected int level;
protected long maxTime;
public ExponentialErrorBackoffStrategy() {
this(500L, 2, 60000L);
}
/**
* @param initTime in milliseconds for which the client is suspended after the first request
* @param factor is the base of the power by which the waiting time increases
* @param maxTime in milliseconds for which the client can be suspended
*/
public ExponentialErrorBackoffStrategy(long initTime, float factor, long maxTime) {
this.initTime = initTime;
this.factor = factor;
this.level = 0;
this.maxTime = maxTime;
}
@Override
public void reconfigure(List externalTasks, ExternalTaskClientException error) {
if (error != null) {
level++;
} else {
level = 0;
}
}
@Override
public long calculateBackoffTime() {
if (level == 0) {
return 0L;
}
long backoffTime = (long) (initTime * Math.pow(factor, level - 1));
return Math.min(backoffTime, maxTime);
}
}