AgentPoller.java

/**
 *  Copyright (C) 2008 Progress Software, Inc. All rights reserved.
 *  http://fusesource.com
 *
 *  The software in this package is published under the terms of the AGPL license
 *  a copy of which has been included with this distribution in the license.txt file.
 */
package org.fusesource.cloudmix.agent;

import java.net.ConnectException;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.Callable;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;

/**
 * A polling spring bean which can poll any of the available agents such as
 * {@link InstallerAgent}
 * 
 * @version $Revision: 1.1 $
 */
public class AgentPoller implements InitializingBean, DisposableBean {
    private static final transient Log LOG = LogFactory.getLog(AgentPoller.class);
    private Callable<Object> agent = new InstallerAgent();
    private Timer timer;
    private long pollingPeriod = 1000L;
    private long initialPollingDelay = 500L;
    private long lastConnectWarning = 0;

    public AgentPoller() {
    }

    public AgentPoller(Callable<Object> agent) {
        this.agent = agent;
    }

    public void afterPropertiesSet() throws Exception {
        start();
    }

    public void start() throws Exception {
        timer = new Timer(true);
        timer.scheduleAtFixedRate(new TimerTask() {
            public void run() {
                agentPoll();
            }
        }, initialPollingDelay, pollingPeriod);
    }

    public void agentPoll() {
        try {
            agent.call();
        } catch (ConnectException e) {
            handleConnectException(e);
        } catch (Exception e) {
            if (e.getCause() instanceof ConnectException) {
                handleConnectException((ConnectException) e.getCause());
            } else {
                LOG.warn("Caught exception while polling Agent: ", e);
            }
        }
        catch (Error e) {
            LOG.warn("Error in poll", e);
            throw e;
        }
    }

    private void handleConnectException(ConnectException ce) {
        long now = System.currentTimeMillis();
        if (now - lastConnectWarning > 60000) {
            LOG.warn("polling attempt failed: cloudmix server unavailable");
            lastConnectWarning = now;
        } else {
            LOG.debug("polling attempt failed: cloudmix server unavailable");
        }
    }

    public void destroy() throws Exception {
        timer.cancel();
    }

    // Properties
    //-------------------------------------------------------------------------

    public long getPollingPeriod() {
        return pollingPeriod;
    }

    public void setPollingPeriod(long pollingPeriod) {
        this.pollingPeriod = pollingPeriod;
    }

    public long getInitialPollingDelay() {
        return initialPollingDelay;
    }

    public void setInitialPollingDelay(long initialPollingDelay) {
        this.initialPollingDelay = initialPollingDelay;
    }

    public Timer getTimer() {
        return timer;
    }

    public void setTimer(Timer timer) {
        this.timer = timer;
    }

    public Callable<Object> getAgent() {
        return agent;
    }

    public void setAgent(Callable<Object> agent) {
        this.agent = agent;
    }

    public void setInstallerAgent(InstallerAgent agnt) {
        setAgent(agnt);
    }

}