ChannelPinger.java

/*
 * The MIT License
 *
 * Copyright (c) 2011, Nathan Parry
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package hudson.slaves;

import hudson.Extension;
import hudson.FilePath;
import jenkins.util.SystemProperties;
import hudson.model.Computer;
import hudson.model.Slave;
import hudson.model.TaskListener;
import hudson.remoting.Channel;
import hudson.remoting.PingThread;
import jenkins.security.MasterToSlaveCallable;
import jenkins.slaves.PingFailureAnalyzer;

import java.io.IOException;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.logging.Logger;

import static java.util.logging.Level.*;

/**
 * Establish a periodic ping to keep connections between {@link Slave slaves}
 * and the main Jenkins node alive. This prevents network proxies from
 * terminating connections that are idle for too long.
 *
 * @since 1.405
 */
@Extension
public class ChannelPinger extends ComputerListener {
    private static final Logger LOGGER = Logger.getLogger(ChannelPinger.class.getName());
    private static final String SYS_PROPERTY_NAME  = ChannelPinger.class.getName() + ".pingInterval";

    /**
     * Interval for the ping in minutes.
     */
    private int pingInterval = 5;

    public ChannelPinger() {
        String interval = SystemProperties.getString(SYS_PROPERTY_NAME);
        if (interval != null) {
            try {
                pingInterval = Integer.valueOf(interval);
            } catch (NumberFormatException e) {
                LOGGER.warning("Ignoring invalid " + SYS_PROPERTY_NAME + "=" + interval);
            }
        }
    }

    @Override
    public void preOnline(Computer c, Channel channel, FilePath root, TaskListener listener)  {
        install(channel);
    }

    public void install(Channel channel) {
        if (pingInterval < 1) {
            LOGGER.fine("Agent ping is disabled");
            return;
        }

        try {
            channel.call(new SetUpRemotePing(pingInterval));
            LOGGER.fine("Set up a remote ping for " + channel.getName());
        } catch (Exception e) {
            LOGGER.severe("Failed to set up a ping for " + channel.getName());
        }

        // set up ping from both directions, so that in case of a router dropping a connection,
        // both sides can notice it and take compensation actions.
        setUpPingForChannel(channel, pingInterval, true);
    }

    private static class SetUpRemotePing extends MasterToSlaveCallable<Void, IOException> {
        private static final long serialVersionUID = -2702219700841759872L;
        private int pingInterval;
        public SetUpRemotePing(int pingInterval) {
            this.pingInterval = pingInterval;
        }

        public Void call() throws IOException {
            setUpPingForChannel(Channel.current(), pingInterval, false);
            return null;
        }
    }

    private static void setUpPingForChannel(final Channel channel, int interval, final boolean analysis) {
        LOGGER.log(FINE, "setting up ping on {0} at interval {1}m", new Object[] {channel.getName(), interval});
        final AtomicBoolean isInClosed = new AtomicBoolean(false);
        final PingThread t = new PingThread(channel, interval * 60 * 1000) {
            @Override
            protected void onDead(Throwable cause) {
                try {
                    if (analysis) {
                        analyze(cause);
                    }
                    if (isInClosed.get()) {
                        LOGGER.log(FINE,"Ping failed after the channel "+channel.getName()+" is already partially closed.",cause);
                    } else {
                        LOGGER.log(INFO,"Ping failed. Terminating the channel "+channel.getName()+".",cause);
                        channel.close(cause);
                    }
                } catch (IOException e) {
                    LOGGER.log(SEVERE,"Failed to terminate the channel "+channel.getName(),e);
                }
            }
            /** Keep in a separate method so we do not even try to do class loading on {@link PingFailureAnalyzer} from an agent JVM. */
            private void analyze(Throwable cause) throws IOException {
                for (PingFailureAnalyzer pfa : PingFailureAnalyzer.all()) {
                    pfa.onPingFailure(channel,cause);
                }
            }
            @Deprecated
            @Override
            protected void onDead() {
                onDead(null);
            }
        };

        channel.addListener(new Channel.Listener() {
            @Override
            public void onClosed(Channel channel, IOException cause) {
                LOGGER.fine("Terminating ping thread for " + channel.getName());
                isInClosed.set(true);
                t.interrupt();  // make sure the ping thread is terminated
            }
        });

        t.start();
        LOGGER.fine("Ping thread started for " + channel + " with a " + interval + " minute interval");
    }
}