/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); 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.apache.brooklyn.util.core.internal.ssh;
import org.apache.brooklyn.util.exceptions.Exceptions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Allow replayable request to be retried a limited number of times, and impose an exponential back-off
* delay before returning.
* <p>
* Copied and modified from jclouds; original author was James Murty
*/
public class BackoffLimitedRetryHandler {
private static final Logger LOG = LoggerFactory.getLogger(BackoffLimitedRetryHandler.class);
private final int retryCountLimit;
private final long delayStart;
public BackoffLimitedRetryHandler() {
this(5, 50L);
}
public BackoffLimitedRetryHandler(int retryCountLimit, long delayStart) {
this.retryCountLimit = retryCountLimit;
this.delayStart = delayStart;
}
public void imposeBackoffExponentialDelay(int failureCount, String commandDescription) {
imposeBackoffExponentialDelay(delayStart, 2, failureCount, retryCountLimit, commandDescription);
}
public void imposeBackoffExponentialDelay(long period, int pow, int failureCount, int max, String commandDescription) {
imposeBackoffExponentialDelay(period, period * 10l, pow, failureCount, max, commandDescription);
}
public void imposeBackoffExponentialDelay(long period,
long maxPeriod,
int pow,
int failureCount,
int max,
String commandDescription) {
long delayMs = (long) (period * Math.pow(failureCount, pow));
delayMs = (delayMs > maxPeriod) ? maxPeriod : delayMs;
if (LOG.isDebugEnabled()) LOG.debug("Retry {}/{}: delaying for {} ms: {}",
new Object[] {failureCount, max, delayMs, commandDescription});
try {
Thread.sleep(delayMs);
} catch (InterruptedException e) {
Exceptions.propagate(e);
}
}
}