/*******************************************************************************
 *
 * Copyright (c) 2004-2012 Oracle Corporation.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *
 * Kohsuke Kawaguchi, Winston Prakash
 *
 *******************************************************************************/ 

package hudson.model;

import hudson.util.StreamTaskListener;

import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import org.eclipse.hudson.security.HudsonSecurityManager;

/**
 * {@link PeriodicWork} that takes a long time to run.
 *
 * <p> Subclasses will implement the {@link #execute(TaskListener)} method and
 * can carry out a long-running task. This runs in a separate thread so as not
 * to block the timer thread, and this class handles all those details.
 *
 * @author Kohsuke Kawaguchi
 */
public abstract class AsyncPeriodicWork extends PeriodicWork {

    /**
     * Name of the work.
     */
    public final String name;
    private Thread thread;

    protected AsyncPeriodicWork(String name) {
        this.name = name;
    }

    /**
     * Schedules this periodic work now in a new thread, if one isn't already
     * running.
     */
    public final void doRun() {
        try {
            if (thread != null && thread.isAlive()) {
                logger.log(Level.INFO, name + " thread is still running. Execution aborted.");
                return;
            }
            thread = new Thread(new Runnable() {
                public void run() {
                    logger.log(Level.INFO, "Started " + name);
                    long startTime = System.currentTimeMillis();

                    StreamTaskListener l = createListener();
                    try {
                        HudsonSecurityManager.grantFullControl();

                        execute(l);
                    } catch (IOException e) {
                        e.printStackTrace(l.fatalError(e.getMessage()));
                    } catch (InterruptedException e) {
                        e.printStackTrace(l.fatalError("aborted"));
                    } finally {
                        l.closeQuietly();
                    }

                    logger.log(Level.INFO, "Finished " + name + ". "
                            + (System.currentTimeMillis() - startTime) + " ms");
                }
            }, name + " thread");
            thread.start();
        } catch (Throwable t) {
            logger.log(Level.SEVERE, name + " thread failed with error", t);
        }
    }

    protected StreamTaskListener createListener() {
        try {
            return new StreamTaskListener(getLogFile());
        } catch (IOException e) {
            throw new Error(e);
        }
    }

    /**
     * Determines the log file that records the result of this task.
     */
    protected File getLogFile() {
        return new File(Hudson.getInstance().getRootDir(), name + ".log");
    }

    /**
     * Executes the task.
     *
     * @param listener Output sent will be reported to the users. (this work is
     * TBD.)
     * @throws InterruptedException The caller will record the exception and
     * moves on.
     * @throws IOException The caller will record the exception and moves on.
     */
    protected abstract void execute(TaskListener listener) throws IOException, InterruptedException;
}