SlaveComputer.java

package hudson.slaves;

import hudson.model.*;
import hudson.remoting.Channel;
import hudson.remoting.Which;
import hudson.remoting.VirtualChannel;
import hudson.remoting.Callable;
import hudson.util.StreamTaskListener;
import hudson.util.NullStream;
import hudson.util.RingBufferLogHandler;
import hudson.util.Futures;
import hudson.FilePath;
import hudson.lifecycle.WindowsSlaveInstaller;
import hudson.Util;
import hudson.maven.agent.Main;
import hudson.maven.agent.PluginManagerInterceptor;

import java.io.File;
import java.io.OutputStream;
import java.io.FileOutputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.logging.Level;
import java.util.logging.LogRecord;
import java.util.logging.Logger;
import java.util.List;
import java.util.Collections;
import java.util.ArrayList;
import java.nio.charset.Charset;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.Future;

import org.kohsuke.stapler.StaplerRequest;
import org.kohsuke.stapler.StaplerResponse;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletResponse;

/**
 * {@link Computer} for {@link Slave}s.
 *
 * @author Kohsuke Kawaguchi
 */
public class SlaveComputer extends Computer {
    private volatile Channel channel;
    private volatile transient boolean acceptingTasks = true;
    private Charset defaultCharset;
    private Boolean isUnix;
    /**
     * Effective {@link ComputerLauncher} that hides the details of
     * how we launch a slave agent on this computer.
     *
     * <p>
     * This is normally the same as {@link Slave#getLauncher()} but
     * can be different. See {@link #grabLauncher(Node)}. 
     */
    private ComputerLauncher launcher;

    /**
     * Number of failed attempts to reconnect to this node
     * (so that if we keep failing to reconnect, we can stop
     * trying.)
     */
    private transient int numRetryAttempt;

    /**
     * Tracks the status of the last launch operation, which is always asynchronous.
     * This can be used to wait for the completion, or cancel the launch activity.
     */
    private volatile Future<?> lastConnectActivity = null;

    private Object constructed = new Object();

    public SlaveComputer(Slave slave) {
        super(slave);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isAcceptingTasks() {
        return acceptingTasks;
    }

    /**
     * Allows a {@linkplain hudson.slaves.ComputerLauncher} or a {@linkplain hudson.slaves.RetentionStrategy} to
     * suspend tasks being accepted by the slave computer.
     *
     * @param acceptingTasks {@code true} if the slave can accept tasks.
     */
    public void setAcceptingTasks(boolean acceptingTasks) {
        this.acceptingTasks = acceptingTasks;
    }

    /**
     * True if this computer is a Unix machine (as opposed to Windows machine).
     *
     * @return
     *      null if the computer is disconnected and therefore we don't know whether it is Unix or not.
     */
    public Boolean isUnix() {
        return isUnix;
    }

    public Slave getNode() {
        return (Slave)super.getNode();
    }

    @Override
    public String getIcon() {
        Future<?> l = lastConnectActivity;
        if(l!=null && !l.isDone())
            return "computer-flash.gif";
        return super.getIcon();
    }

    @Override
    @Deprecated
    public boolean isJnlpAgent() {
        return launcher instanceof JNLPLauncher;
    }

    @Override
    public boolean isLaunchSupported() {
        return launcher.isLaunchSupported();
    }

    public ComputerLauncher getLauncher() {
        return launcher;
    }

    public Future<?> connect(boolean forceReconnect) {
        if(channel!=null)   return Futures.precomputed(null);
        if(!forceReconnect && lastConnectActivity!=null)
            return lastConnectActivity;
        if(forceReconnect && lastConnectActivity!=null)
            logger.fine("Forcing a reconnect");

        closeChannel();
        return lastConnectActivity = Computer.threadPoolForRemoting.submit(new java.util.concurrent.Callable<Object>() {
            public Object call() throws Exception {
                // do this on another thread so that the lengthy launch operation
                // (which is typical) won't block UI thread.
                StreamTaskListener listener = new StreamTaskListener(openLogFile());
                try {
                    launcher.launch(SlaveComputer.this, listener);
                    return null;
                } catch (IOException e) {
                    Util.displayIOException(e,listener);
                    e.printStackTrace(listener.error(Messages.ComputerLauncher_unexpectedError()));
                    throw e;
                } catch (InterruptedException e) {
                    e.printStackTrace(listener.error(Messages.ComputerLauncher_abortedLaunch()));
                    throw e;
                }
            }
        });
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void taskAccepted(Executor executor, Queue.Task task) {
        super.taskAccepted(executor, task);
        if (launcher instanceof ExecutorListener) {
            ((ExecutorListener)launcher).taskAccepted(executor, task);
        }
        if (getNode().getRetentionStrategy() instanceof ExecutorListener) {
            ((ExecutorListener)getNode().getRetentionStrategy()).taskAccepted(executor, task);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void taskCompleted(Executor executor, Queue.Task task, long durationMS) {
        super.taskCompleted(executor, task, durationMS);
        if (launcher instanceof ExecutorListener) {
            ((ExecutorListener)launcher).taskCompleted(executor, task, durationMS);
        }
        if (getNode().getRetentionStrategy() instanceof ExecutorListener) {
            ((ExecutorListener)getNode().getRetentionStrategy()).taskCompleted(executor, task, durationMS);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void taskCompletedWithProblems(Executor executor, Queue.Task task, long durationMS, Throwable problems) {
        super.taskCompletedWithProblems(executor, task, durationMS, problems);
        if (launcher instanceof ExecutorListener) {
            ((ExecutorListener)launcher).taskCompletedWithProblems(executor, task, durationMS, problems);
        }
        if (getNode().getRetentionStrategy() instanceof ExecutorListener) {
            ((ExecutorListener)getNode().getRetentionStrategy()).taskCompletedWithProblems(executor, task, durationMS,
                    problems);
        }
    }

    @Override
    public boolean isConnecting() {
        Future<?> l = lastConnectActivity;
        return isOffline() && l!=null && !l.isDone();
    }

    public OutputStream openLogFile() {
        OutputStream os;
        try {
            os = new FileOutputStream(getLogFile());
        } catch (FileNotFoundException e) {
            logger.log(Level.SEVERE, "Failed to create log file "+getLogFile(),e);
            os = new NullStream();
        }
        return os;
    }

    private final Object channelLock = new Object();

    public void setChannel(InputStream in, OutputStream out, TaskListener taskListener, Channel.Listener listener) throws IOException, InterruptedException {
        setChannel(in,out,taskListener.getLogger(),listener);
    }

    /**
     * Creates a {@link Channel} from the given stream and sets that to this slave.
     *
     * @param in
     *      Stream connected to the remote "slave.jar". It's the caller's responsibility to do
     *      buffering on this stream, if that's necessary.
     * @param out
     *      Stream connected to the remote peer. It's the caller's responsibility to do
     *      buffering on this stream, if that's necessary.
     * @param launchLog
     *      If non-null, receive the portion of data in <tt>is</tt> before
     *      the data goes into the "binary mode". This is useful
     *      when the established communication channel might include some data that might
     *      be useful for debugging/trouble-shooting.
     * @param listener
     *      Gets a notification when the channel closes, to perform clean up.
     */
    public void setChannel(InputStream in, OutputStream out, OutputStream launchLog, Channel.Listener listener) throws IOException, InterruptedException {
        if(this.channel!=null)
            throw new IllegalStateException("Already connected");

        Channel channel = new Channel(nodeName,threadPoolForRemoting, Channel.Mode.NEGOTIATE,
            in,out, launchLog);
        channel.addListener(new Channel.Listener() {
            public void onClosed(Channel c,IOException cause) {
                SlaveComputer.this.channel = null;
            }
        });
        channel.addListener(listener);

        PrintWriter log = new PrintWriter(launchLog,true);

        boolean _isUnix = channel.call(new DetectOS());
        log.println(_isUnix? hudson.model.Messages.Slave_UnixSlave():hudson.model.Messages.Slave_WindowsSlave());

        String defaultCharsetName = channel.call(new DetectDefaultCharset());

        String remoteFs = getNode().getRemoteFS();
        if(_isUnix && !remoteFs.contains("/") && remoteFs.contains("\\"))
            log.println("WARNING: "+remoteFs+" looks suspiciously like Windows path. Maybe you meant "+remoteFs.replace('\\','/')+"?");

        {// send jars that we need for our operations
            // TODO: maybe I should generalize this kind of "post initialization" processing
            FilePath dst = new FilePath(channel, remoteFs);
            copyJar(log, dst, Main.class, "maven-agent");
            copyJar(log, dst, PluginManagerInterceptor.class, "maven-interceptor");
        }

        channel.call(new LogInstaller());
        channel.call(new WindowsSlaveInstaller(remoteFs));

        // update the data structure atomically to prevent others from seeing a channel that's not properly initialized yet
        synchronized(channelLock) {
            if(this.channel!=null) {
                // check again. we used to have this entire method in a big sycnhronization block,
                // but Channel constructor blocks for an external process to do the connection
                // if CommandLauncher is used, and that cannot be interrupted because it blocks at InputStream.
                // so if the process hangs, it hangs the thread in a lock, and since Hudson will try to relaunch,
                // we'll end up queuing the lot of threads in a pseudo deadlock.
                // This implementation prevents that by avoiding a lock. HUDSON-1705 is likely a manifestation of this.
                channel.close();
                throw new IllegalStateException("Already connected");
            }
            isUnix = _isUnix;
            numRetryAttempt = 0;
            this.channel = channel;
            defaultCharset = Charset.forName(defaultCharsetName);
        }
        for (ComputerListener cl : Hudson.getInstance().getComputerListeners())
            cl.onOnline(this);
        Hudson.getInstance().getQueue().scheduleMaintenance();
    }

    /**
     * Copies a jar file from the master to slave.
     */
    private void copyJar(PrintWriter log, FilePath dst, Class<?> representative, String seedName) throws IOException, InterruptedException {
        // in normal execution environment, the master should be loading 'representative' from this jar, so
        // in that way we can find it.
        File jar = Which.jarFile(representative);

        if(jar.isDirectory()) {
            // but during the development and unit test environment, we may be picking the class up from the classes dir,
            // in which case we need to find this in a tricker way.
            String dir = Hudson.getInstance().servletContext.getRealPath("/WEB-INF/lib");
            FilePath[] paths = new FilePath(new File(dir)).list(seedName + "-*.jar");
            jar = new File(paths[0].getRemote());
        }

        new FilePath(jar).copyTo(dst.child(seedName +".jar"));
        log.println("Copied "+seedName+".jar");
    }

    @Override
    public VirtualChannel getChannel() {
        return channel;
    }

    public Charset getDefaultCharset() {
        return defaultCharset;
    }

    public List<LogRecord> getLogRecords() throws IOException, InterruptedException {
        if(channel==null)
            return Collections.emptyList();
        else
            return channel.call(new Callable<List<LogRecord>,RuntimeException>() {
                public List<LogRecord> call() {
                    return new ArrayList<LogRecord>(SLAVE_LOG_HANDLER.getView());
                }
            });
    }

    public void doDoDisconnect(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
        checkPermission(Hudson.ADMINISTER);
        disconnect();
        rsp.sendRedirect(".");
    }

    @Override
    public Future<?> disconnect() {
        return Computer.threadPoolForRemoting.submit(new Runnable() {
            public void run() {
                // do this on another thread so that any lengthy disconnect operation
                // (which could be typical) won't block UI thread.
                StreamTaskListener listener = new StreamTaskListener(openLogFile());
                launcher.beforeDisconnect(SlaveComputer.this, listener);
                closeChannel();
                launcher.afterDisconnect(SlaveComputer.this, listener);
            }
        });
    }

    public void doLaunchSlaveAgent(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
        if(channel!=null) {
            rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
            return;
        }

        connect(true);

        // TODO: would be nice to redirect the user to "launching..." wait page,
        // then spend a few seconds there and poll for the completion periodically.
        rsp.sendRedirect("log");
    }

    public void tryReconnect() {
        numRetryAttempt++;
        if(numRetryAttempt<6 || (numRetryAttempt%12)==0) {
            // initially retry several times quickly, and after that, do it infrequently.
            logger.info("Attempting to reconnect "+nodeName);
            connect(true);
        }
    }

    /**
     * Serves jar files for JNLP slave agents.
     *
     * @deprecated
     *      This URL binding is no longer used and moved up directly under to {@link Hudson},
     *      but it's left here for now just in case some old JNLP slave agents request it.
     */
    public Slave.JnlpJar getJnlpJars(String fileName) {
        return new Slave.JnlpJar(fileName);
    }

    @Override
    protected void kill() {
        super.kill();
        closeChannel();
    }

    public RetentionStrategy getRetentionStrategy() {
        return getNode().getRetentionStrategy();
    }

    /**
     * If still connected, disconnect.
     */
    private void closeChannel() {
        // TODO: race condition between this and the setChannel method.
        Channel c = channel;
        channel = null;
        isUnix = null;
        if (c != null) {
            try {
                c.close();
            } catch (IOException e) {
                logger.log(Level.SEVERE, "Failed to terminate channel to " + getDisplayName(), e);
            }
        }
        for (ComputerListener cl : Hudson.getInstance().getComputerListeners())
            cl.onOffline(this);
    }

    @Override
    protected void setNode(Node node) {
        super.setNode(node);
        launcher = grabLauncher(node);

        // maybe the configuration was changed to relaunch the slave, so try to re-launch now.
        // "constructed==null" test is an ugly hack to avoid launching before the object is fully
        // constructed.
        if(constructed!=null)
            connect(false);
    }

    /**
     * Grabs a {@link ComputerLauncher} out of {@link Node} to keep it in this {@link Computer}.
     * The returned launcher will be set to {@link #launcher} and used to carry out the actual launch operation.
     *
     * <p>
     * Subtypes that needs to decorate {@link ComputerLauncher} can do so by overriding this method.
     * This is useful for {@link SlaveComputer}s for clouds for example, where one normally needs
     * additional pre-launch step (such as waiting for the provisioned node to become available)
     * before the user specified launch step (like SSH connection) kicks in.
     *
     * @see ComputerLauncherFilter
     */
    protected ComputerLauncher grabLauncher(Node node) {
        return ((Slave)node).getLauncher();
    }

    private static final Logger logger = Logger.getLogger(SlaveComputer.class.getName());

    private static final class DetectOS implements Callable<Boolean,IOException> {
        public Boolean call() throws IOException {
            return File.pathSeparatorChar==':';
        }
    }

    private static final class DetectDefaultCharset implements Callable<String,IOException> {
        public String call() throws IOException {
            return Charset.defaultCharset().name();
        }
    }

    /**
     * This field is used on each slave node to record log records on the slave.
     */
    private static final RingBufferLogHandler SLAVE_LOG_HANDLER = new RingBufferLogHandler();

    private static class LogInstaller implements Callable<Void,RuntimeException> {
        public Void call() {
            // avoid double installation of the handler
            Logger logger = Logger.getLogger("hudson");
            logger.removeHandler(SLAVE_LOG_HANDLER);
            logger.addHandler(SLAVE_LOG_HANDLER);
            return null;
        }
        private static final long serialVersionUID = 1L;
    }
}