org.apache.activemq.thread.SchedulerTimerTask Maven / Gradle / Ivy
/**
* 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.activemq.thread;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.TimerTask;
/**
* A TimeTask for a Runnable object
*
*/
public class SchedulerTimerTask extends TimerTask {
private static final Logger LOGGER = LoggerFactory.getLogger(SchedulerTimerTask.class);
private final Runnable task;
public SchedulerTimerTask(Runnable task) {
this.task = task;
}
public void run() {
try {
this.task.run();
} catch (Error error) {
// Very bad error. Can't swallow this but can log it.
LOGGER.error("Scheduled task error", error);
throw error;
} catch (Exception exception) {
// It is a known issue of java.util.Timer that if a TimerTask.run() method throws an exception, the
// Timer's thread exits as if Timer.cancel() had been called. This makes the Timer completely unusable from
// that point on - whenever the Timer triggers there is an 'IllegalStateException: Timer already cancelled'
// and the task does not get executed.
//
// In practice, this makes the ActiveMQ client unable to refresh connections to brokers. Generally, tasks
// are well coded to not throw exceptions but if they do, problems ensue...
//
// The answer, here, is to log the exception and then carry on without throwing further. This gives the
// added benefit that, having seen the exception thrown, one can then go and fix the offending task!
LOGGER.error("Scheduled task exception", exception);
}
}
}