Hudson.java

package hudson.model;

import com.thoughtworks.xstream.XStream;
import hudson.BulkChange;
import hudson.FilePath;
import hudson.Functions;
import hudson.Launcher;
import hudson.Launcher.LocalLauncher;
import hudson.Plugin;
import hudson.PluginManager;
import hudson.PluginWrapper;
import hudson.ProxyConfiguration;
import hudson.StructuredForm;
import hudson.TcpSlaveAgentListener;
import hudson.Util;
import static hudson.Util.fixEmpty;
import hudson.WebAppMain;
import hudson.XmlFile;
import hudson.logging.LogRecorderManager;
import hudson.lifecycle.WindowsInstallerLink;
import hudson.lifecycle.Lifecycle;
import hudson.model.Descriptor.FormException;
import hudson.model.listeners.ItemListener;
import hudson.model.listeners.JobListener;
import hudson.model.listeners.JobListener.JobListenerAdapter;
import hudson.model.listeners.SCMListener;
import hudson.remoting.LocalChannel;
import hudson.remoting.VirtualChannel;
import hudson.scm.CVSSCM;
import hudson.scm.RepositoryBrowser;
import hudson.scm.RepositoryBrowsers;
import hudson.scm.SCM;
import hudson.scm.SCMDescriptor;
import hudson.scm.SCMS;
import hudson.scm.SubversionSCM;
import hudson.search.CollectionSearchIndex;
import hudson.search.SearchIndexBuilder;
import hudson.security.ACL;
import hudson.security.AccessControlled;
import hudson.security.AuthorizationStrategy;
import hudson.security.BasicAuthenticationFilter;
import hudson.security.HudsonFilter;
import hudson.security.LegacyAuthorizationStrategy;
import hudson.security.LegacySecurityRealm;
import hudson.security.Permission;
import hudson.security.PermissionGroup;
import hudson.security.SecurityMode;
import hudson.security.SecurityRealm;
import hudson.security.SecurityRealm.SecurityComponents;
import hudson.security.TokenBasedRememberMeServices2;
import hudson.slaves.ComputerListener;
import hudson.slaves.RetentionStrategy;
import hudson.tasks.BuildStep;
import hudson.tasks.BuildWrapper;
import hudson.tasks.BuildWrappers;
import hudson.tasks.Builder;
import hudson.tasks.DynamicLabeler;
import hudson.tasks.LabelFinder;
import hudson.tasks.Mailer;
import hudson.tasks.Publisher;
import hudson.triggers.Trigger;
import hudson.triggers.TriggerDescriptor;
import hudson.triggers.Triggers;
import hudson.util.CaseInsensitiveComparator;
import hudson.util.ClockDifference;
import hudson.util.CopyOnWriteList;
import hudson.util.CopyOnWriteMap;
import hudson.util.DaemonThreadFactory;
import hudson.util.FormFieldValidator;
import hudson.util.HudsonIsLoading;
import hudson.util.MultipartFormDataParser;
import hudson.util.RemotingDiagnostics;
import hudson.util.TextFile;
import hudson.util.XStream2;
import hudson.util.HudsonIsRestarting;
import hudson.widgets.Widget;
import net.sf.json.JSONObject;
import org.acegisecurity.AccessDeniedException;
import org.acegisecurity.Authentication;
import org.acegisecurity.GrantedAuthority;
import org.acegisecurity.GrantedAuthorityImpl;
import org.acegisecurity.context.SecurityContextHolder;
import org.acegisecurity.providers.anonymous.AnonymousAuthenticationToken;
import org.acegisecurity.ui.AbstractProcessingFilter;
import static org.acegisecurity.ui.rememberme.TokenBasedRememberMeServices.ACEGI_SECURITY_HASHED_REMEMBER_ME_COOKIE_KEY;
import org.apache.commons.logging.LogFactory;
import org.kohsuke.stapler.MetaClass;
import org.kohsuke.stapler.QueryParameter;
import org.kohsuke.stapler.Stapler;
import org.kohsuke.stapler.StaplerProxy;
import org.kohsuke.stapler.StaplerRequest;
import org.kohsuke.stapler.StaplerResponse;
import org.kohsuke.stapler.export.Exported;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import static javax.servlet.http.HttpServletResponse.SC_BAD_REQUEST;
import static javax.servlet.http.HttpServletResponse.SC_NOT_FOUND;
import javax.servlet.http.HttpSession;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.URL;
import java.security.SecureRandom;
import java.text.NumberFormat;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.Timer;
import java.util.TreeSet;
import java.util.Vector;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.logging.Level;
import java.util.logging.LogRecord;
import java.util.logging.Logger;
import java.util.regex.Pattern;
import java.nio.charset.Charset;
import javax.servlet.RequestDispatcher;

/**
 * Root object of the system.
 *
 * @author Kohsuke Kawaguchi
 */
public final class Hudson extends View implements ItemGroup<TopLevelItem>, Node, StaplerProxy, ViewGroup {
    private transient final Queue queue;

    /**
     * {@link Computer}s in this Hudson system. Read-only.
     */
    private transient final Map<Node,Computer> computers = new CopyOnWriteMap.Hash<Node,Computer>();

    /**
     * Number of executors of the master node.
     */
    private int numExecutors = 2;

    /**
     * Job allocation strategy.
     */
    private Mode mode = Mode.NORMAL;

    /**
     * False to enable anyone to do anything.
     * Left as a field so that we can still read old data that uses this flag.
     *
     * @see #authorizationStrategy
     * @see #securityRealm
     */
    private Boolean useSecurity;

    /**
     * Controls how the
     * <a href="http://en.wikipedia.org/wiki/Authorization">authorization</a>
     * is handled in Hudson.
     * <p>
     * This ultimately controls who has access to what.
     *
     * Never null.
     */
    private volatile AuthorizationStrategy authorizationStrategy;

    /**
     * Controls a part of the
     * <a href="http://en.wikipedia.org/wiki/Authentication">authentication</a>
     * handling in Hudson.
     * <p>
     * Intuitively, this corresponds to the user database.
     *
     * See {@link HudsonFilter} for the concrete authentication protocol.
     *
     * Never null. Always use {@link #setSecurityRealm(SecurityRealm)} to
     * update this field.
     *
     * @see #getSecurity()
     * @see #setSecurityRealm(SecurityRealm)
     */
    private volatile SecurityRealm securityRealm;

    /**
     * Message displayed in the top page.
     */
    private String systemMessage;

    /**
     * Root directory of the system.
     */
    public transient final File root;

    /**
     * All {@link Item}s keyed by their {@link Item#getName() name}s.
     */
    /*package*/ transient final Map<String,TopLevelItem> items = new CopyOnWriteMap.Tree<String,TopLevelItem>(CaseInsensitiveComparator.INSTANCE);

    /**
     * The sole instance.
     */
    private static Hudson theInstance;

    private transient volatile boolean isQuietingDown;
    private transient volatile boolean terminating;

    private List<JDK> jdks = new ArrayList<JDK>();

    /**
     * Widgets on Hudson.
     */
    private transient final List<Widget> widgets = new CopyOnWriteArrayList<Widget>();

    private transient volatile DependencyGraph dependencyGraph;

    /**
     * Set of installed cluster nodes.
     *
     * We use this field with copy-on-write semantics.
     * This field has mutable list (to keep the serialization look clean),
     * but it shall never be modified. Only new completely populated slave
     * list can be set here.
     */
    private volatile List<Slave> slaves;

    /**
     * Quiet period.
     *
     * This is {@link Integer} so that we can initialize it to '5' for upgrading users.
     */
    /*package*/ Integer quietPeriod;

    /**
     * {@link View}s.
     */
    private List<View> views;   // can't initialize it eagerly for backward compatibility

    private transient final FingerprintMap fingerprintMap = new FingerprintMap();

    /**
     * Loaded plugins.
     */
    public transient final PluginManager pluginManager;

    public transient volatile TcpSlaveAgentListener tcpSlaveAgentListener;

    /**
     * List of registered {@link JobListener}s.
     */
    private transient final CopyOnWriteList<ItemListener> itemListeners = new CopyOnWriteList<ItemListener>();

    /**
     * List of registered {@link SCMListener}s.
     */
    private transient final CopyOnWriteList<SCMListener> scmListeners = new CopyOnWriteList<SCMListener>();

    /**
     * List of registered {@link ComputerListener}s.
     */
    private transient final CopyOnWriteList<ComputerListener> computerListeners = new CopyOnWriteList<ComputerListener>();

    /**
     * TCP slave agent port.
     * 0 for random, -1 to disable.
     */
    private int slaveAgentPort =0;

    /**
     * All labels known to Hudson. This allows us to reuse the same label instances
     * as much as possible, even though that's not a strict requirement.
     */
    private transient final ConcurrentHashMap<String,Label> labels = new ConcurrentHashMap<String,Label>();
    private transient Set<Label> labelSet;
    private transient volatile Set<Label> dynamicLabels = null;

    public transient final ServletContext servletContext;

    /**
     * Transient action list. Useful for adding navigation items to the navigation bar
     * on the left.
     */
    private transient final List<Action> actions = new CopyOnWriteArrayList<Action>();

    public static Hudson getInstance() {
        return theInstance;
    }

    /**
     * Secrete key generated once and used for a long time, beyond
     * container start/stop.
     */
    private final String secretKey;

    private transient final UpdateCenter updateCenter = new UpdateCenter();

    /**
     * True if the user opted out from the statistics tracking. We'll never send anything if this is true.
     */
    private Boolean noUsageStatistics;

    /**
     * HTTP proxy configuration.
     */
    public transient volatile ProxyConfiguration proxy;

    /**
     * Bound to "/log".
     */
    private transient final LogRecorderManager log = new LogRecorderManager();

    public Hudson(File root, ServletContext context) throws IOException {
        super(null);
        this.root = root;
        this.servletContext = context;
        if(theInstance!=null)
            throw new IllegalStateException("second instance");
        theInstance = this;

        log.load();
        
        Trigger.timer = new Timer("Hudson cron thread");
        queue = new Queue();

        try {
            dependencyGraph = DependencyGraph.EMPTY;
        } catch (InternalError e) {
            if(e.getMessage().contains("window server")) {
                throw new Error("Looks like the server runs without X. Please specify -Djava.awt.headless=true as JVM option",e);
            }
            throw e;
        }

        // get or create the secret
        TextFile secretFile = new TextFile(new File(Hudson.getInstance().getRootDir(),"secret.key"));
        if(secretFile.exists()) {
            secretKey = secretFile.readTrim();
        } else {
            SecureRandom sr = new SecureRandom();
            byte[] random = new byte[32];
            sr.nextBytes(random);
            secretKey = Util.toHexString(random);
            secretFile.write(secretKey);
        }

        try {
            proxy = ProxyConfiguration.load();
        } catch (IOException e) {
            LOGGER.log(Level.SEVERE, "Failed to load proxy configuration", e);
        }

        // run the init code of SubversionSCM before we load plugins so that plugins can change SubversionWorkspaceSelector.
        SubversionSCM.DescriptorImpl.DESCRIPTOR.getDisplayName();

        // load plugins.
        pluginManager = new PluginManager(context);

        // if we are loading old data that doesn't have this field
        if(slaves==null)    slaves = new ArrayList<Slave>();

        // work around to have MavenModule register itself until we either move it to a plugin
        // or make it a part of the core.
        Items.LIST.hashCode();

        load();

//        try {
//            // fill up the cache
//            load();
//
//            Controller c = new Controller();
//            c.startCPUProfiling(ProfilingModes.CPU_TRACING,""); // "java.*");
//            load();
//            c.stopCPUProfiling();
//            c.captureSnapshot(ProfilingModes.SNAPSHOT_WITHOUT_HEAP);
//        } catch (Exception e) {
//            throw new Error(e);
//        }

        if(slaveAgentPort!=-1)
            tcpSlaveAgentListener = new TcpSlaveAgentListener(slaveAgentPort);
        else
            tcpSlaveAgentListener = null;

        updateComputerList();

        getQueue().load();

        for (ItemListener l : itemListeners)
            l.onLoaded();

        // create TokenBasedRememberMeServices, which depends on the availability of the secret key
        TokenBasedRememberMeServices2 rms = new TokenBasedRememberMeServices2();
        rms.setUserDetailsService(HudsonFilter.USER_DETAILS_SERVICE_PROXY);
        rms.setKey(getSecretKey());
        rms.setParameter("remember_me"); // this is the form field name in login.jelly
        HudsonFilter.REMEMBER_ME_SERVICES_PROXY.setDelegate(rms);

        WindowsInstallerLink.registerIfApplicable();
        UsageStatistics.register();
    }

    public TcpSlaveAgentListener getTcpSlaveAgentListener() {
        return tcpSlaveAgentListener;
    }

    @Exported
    public int getSlaveAgentPort() {
        return slaveAgentPort;
    }

    /**
     * If you are calling this on Hudson something is wrong.
     *
     * @deprecated
     */
    @Deprecated
    public String getNodeName() {
        return "";
    }

    public String getNodeDescription() {
        return "the master Hudson node";
    }

    public String getDescription() {
        return systemMessage;
    }

    public PluginManager getPluginManager() {
        return pluginManager;
    }

    public UpdateCenter getUpdateCenter() {
        return updateCenter;
    }

    public boolean isUsageStatisticsCollected() {
        return noUsageStatistics==null || !noUsageStatistics;
    }

    /**
     * Returns a secret key that survives across container start/stop.
     * <p>
     * This value is useful for implementing some of the security features.
     */
    public String getSecretKey() {
        return  secretKey;
    }

    /**
     * @deprecated
     *      {@link Hudson} can't be renamed unlike a regular view.
     */
    @Override
    public void rename(String newName) throws ParseException {
        throw new UnsupportedOperationException();
    }

    @Override
    public String getViewName() {
        return Messages.Hudson_ViewName();
    }

    /**
     * Gets the SCM descriptor by name. Primarily used for making them web-visible.
     */
    public Descriptor<SCM> getScm(String shortClassName) {
        return findDescriptor(shortClassName,SCMS.SCMS);
    }

    /**
     * Gets the repository browser descriptor by name. Primarily used for making them web-visible.
     */
    public Descriptor<RepositoryBrowser<?>> getRepositoryBrowser(String shortClassName) {
        return findDescriptor(shortClassName,RepositoryBrowsers.LIST);
    }

    /**
     * Gets the builder descriptor by name. Primarily used for making them web-visible.
     */
    public Descriptor<Builder> getBuilder(String shortClassName) {
        return findDescriptor(shortClassName, BuildStep.BUILDERS);
    }

    /**
     * Gets the build wrapper descriptor by name. Primarily used for making them web-visible.
     */
    public Descriptor<BuildWrapper> getBuildWrapper(String shortClassName) {
        return findDescriptor(shortClassName, BuildWrappers.WRAPPERS);
    }

    /**
     * Gets the publisher descriptor by name. Primarily used for making them web-visible.
     */
    public Descriptor<Publisher> getPublisher(String shortClassName) {
        return findDescriptor(shortClassName, BuildStep.PUBLISHERS);
    }

    /**
     * Gets the trigger descriptor by name. Primarily used for making them web-visible.
     */
    public TriggerDescriptor getTrigger(String shortClassName) {
        return (TriggerDescriptor)findDescriptor(shortClassName, Triggers.TRIGGERS);
    }

    /**
     * Gets the {@link JobPropertyDescriptor} by name. Primarily used for making them web-visible.
     */
    public JobPropertyDescriptor getJobProperty(String shortClassName) {
        // combining these two lines triggers javac bug. See issue #610.
        Descriptor d = findDescriptor(shortClassName, Jobs.PROPERTIES);
        return (JobPropertyDescriptor) d;
    }

    /**
     * @deprecated
     *      This method is really just implementing {@link View#getDescriptor()}.
     *      It's unlikely that your program wants to invoke this method explicitly.
     *      Perhaps you meant {@link #getDescriptor(String)} ?
     */
    public ViewDescriptor getDescriptor() {
        // TODO
        throw new UnsupportedOperationException();
    }

    /**
     * Exposes {@link Descriptor} by its name to URL.
     *
     * After doing all the {@code getXXX(shortClassName)} methods, I finally realized that
     * this just doesn't scale.
     */
    public Descriptor getDescriptor(String fullyQualifiedClassName) {
        for( Descriptor d : Descriptor.ALL )
            if(d.clazz.getName().equals(fullyQualifiedClassName))
                return d;
        return null;
    }

    /**
     * Gets the {@link SecurityRealm} descriptors by name. Primarily used for making them web-visible.
     */
    public Descriptor<SecurityRealm> getSecurityRealms(String shortClassName) {
        return findDescriptor(shortClassName,SecurityRealm.LIST);
    }

    /**
     * Finds a descriptor that has the specified name.
     */
    private <T extends Describable<T>>
    Descriptor<T> findDescriptor(String shortClassName, Collection<? extends Descriptor<T>> descriptors) {
        String name = '.'+shortClassName;
        for (Descriptor<T> d : descriptors) {
            if(d.clazz.getName().endsWith(name))
                return d;
        }
        return null;
    }

    /**
     * Adds a new {@link JobListener}.
     *
     * @deprecated
     *      Use {@code getJobListners().add(l)} instead.
     */
    public void addListener(JobListener l) {
        itemListeners.add(new JobListenerAdapter(l));
    }

    /**
     * Deletes an existing {@link JobListener}.
     *
     * @deprecated
     *      Use {@code getJobListners().remove(l)} instead.
     */
    public boolean removeListener(JobListener l ) {
        return itemListeners.remove(new JobListenerAdapter(l));
    }

    /**
     * Gets all the installed {@link ItemListener}s.
     */
    public CopyOnWriteList<ItemListener> getJobListeners() {
        return itemListeners;
    }

    /**
     * Gets all the installed {@link SCMListener}s.
     */
    public CopyOnWriteList<SCMListener> getSCMListeners() {
        return scmListeners;
    }

    /**
     * Gets all the installed {@link ComputerListener}s.
     */
    public CopyOnWriteList<ComputerListener> getComputerListeners() {
        return computerListeners;
    }

    /**
     * Gets the plugin object from its short name.
     *
     * <p>
     * This allows URL <tt>hudson/plugin/ID</tt> to be served by the views
     * of the plugin class.
     */
    public Plugin getPlugin(String shortName) {
        PluginWrapper p = pluginManager.getPlugin(shortName);
        if(p==null)     return null;
        return p.getPlugin();
    }

    /**
     * Gets the plugin object from its class.
     *
     * <p>
     * This allows easy storage of plugin information in the plugin singleton without
     * every plugin reimplementing the singleton pattern.
     *
     * @param clazz The plugin class (beware class-loader fun, this will probably only work
     * from within the hpi that defines the plugin class, it may or may not work in other cases)
     *
     * @return The plugin instance.
     */
    @SuppressWarnings("unchecked")
    public <P extends Plugin> P getPlugin(Class<P> clazz) {
        PluginWrapper p = pluginManager.getPlugin(clazz);
        if(p==null)     return null;
        return (P) p.getPlugin();
    }

    /**
     * Gets the plugin objects from their super-class.
     *
     * @param clazz The plugin class (beware class-loader fun)
     *
     * @return The plugin instances.
     */
    public <P extends Plugin> List<P> getPlugins(Class<P> clazz) {
        List<P> result = new ArrayList<P>();
        for (PluginWrapper w: pluginManager.getPlugins(clazz)) {
            result.add((P)w.getPlugin());
        }
        return Collections.unmodifiableList(result);
    }

    /**
     * Synonym to {@link #getNodeDescription()}.
     */
    public String getSystemMessage() {
        return systemMessage;
    }

    public Launcher createLauncher(TaskListener listener) {
        return new LocalLauncher(listener);
    }

    /**
     * Updates {@link #computers} by using {@link #getSlaves()}.
     *
     * <p>
     * This method tries to reuse existing {@link Computer} objects
     * so that we won't upset {@link Executor}s running in it.
     */
    private void updateComputerList() throws IOException {
        synchronized(computers) {// this synchronization is still necessary so that no two update happens concurrently
            Map<String,Computer> byName = new HashMap<String,Computer>();
            for (Computer c : computers.values()) {
                if(c.getNode()==null)
                    continue;   // this computer is gone
                byName.put(c.getNode().getNodeName(),c);
            }

            Set<Computer> old = new HashSet<Computer>(computers.values());
            Set<Computer> used = new HashSet<Computer>();

            updateComputer(this, byName, used);
            for (Slave s : getSlaves())
                updateComputer(s, byName, used);

            // find out what computers are removed, and kill off all executors.
            // when all executors exit, it will be removed from the computers map.
            // so don't remove too quickly
            old.removeAll(used);
            for (Computer c : old) {
                c.kill();
            }
        }
        getQueue().scheduleMaintenance();
    }

    private void updateComputer(Node n, Map<String,Computer> byNameMap, Set<Computer> used) {
        Computer c;
        c = byNameMap.get(n.getNodeName());
        if (c!=null) {
            c.setNode(n); // reuse
        } else {
            if(n.getNumExecutors()>0)
                computers.put(n,c=n.createComputer());
        }
        used.add(c);
    }

    /*package*/ void removeComputer(Computer computer) {
        for (Entry<Node, Computer> e : computers.entrySet()) {
            if (e.getValue() == computer) {
                computers.remove(e.getKey());
                return;
            }
        }
        throw new IllegalStateException("Trying to remove unknown computer");
    }

    public String getFullName() {
        return "";
    }

    public String getFullDisplayName() {
        return "";
    }

    /**
     * Returns the transient {@link Action}s associated with the top page.
     *
     * <p>
     * Adding {@link Action} is primarily useful for plugins to contribute
     * an item to the navigation bar of the top page. See existing {@link Action}
     * implementation for it affects the GUI.
     *
     * <p>
     * To register an {@link Action}, write code like
     * {@code Hudson.getInstance().getActions().add(...)}
     *
     * @return
     *      Live list where the changes can be made. Can be empty but never null.
     * @since 1.172
     */
    public List<Action> getActions() {
        return actions;
    }

    /**
     * Gets just the immediate children of {@link Hudson}.
     *
     * @see #getAllItems(Class)
     */
    public List<TopLevelItem> getItems() {
        return new ArrayList<TopLevelItem>(items.values());
    }

    /**
     * Gets just the immediate children of {@link Hudson} but of the given type.
     */
    public <T> List<T> getItems(Class<T> type) {
        List<T> r = new ArrayList<T>();
        for (TopLevelItem i : items.values())
            if (type.isInstance(i))
                 r.add(type.cast(i));
        return r;
    }

    /**
     * Gets all the {@link Item}s recursively in the {@link ItemGroup} tree
     * and filter them by the given type.
     */
    public <T extends Item> List<T> getAllItems(Class<T> type) {
        List<T> r = new ArrayList<T>();

        Stack<ItemGroup> q = new Stack<ItemGroup>();
        q.push(this);

        while(!q.isEmpty()) {
            ItemGroup<?> parent = q.pop();
            for (Item i : parent.getItems()) {
                if(type.isInstance(i))
                    r.add(type.cast(i));
                if(i instanceof ItemGroup)
                    q.push((ItemGroup)i);
            }
        }

        return r;
    }

    /**
     * Gets the list of all the projects.
     *
     * <p>
     * Since {@link Project} can only show up under {@link Hudson},
     * no need to search recursively.
     */
    public List<Project> getProjects() {
        return Util.createSubList(items.values(),Project.class);
    }

    /**
     * Gets the names of all the {@link Job}s.
     */
    public Collection<String> getJobNames() {
        List<String> names = new ArrayList<String>();
        for (Job j : getAllItems(Job.class))
            names.add(j.getFullName());
        return names;
    }

    /**
     * Gets the names of all the {@link TopLevelItem}s.
     */
    public Collection<String> getTopLevelItemNames() {
        List<String> names = new ArrayList<String>();
        for (TopLevelItem j : items.values())
            names.add(j.getName());
        return names;
    }

    /**
     * Every job belongs to us.
     *
     * @deprecated
     *      why are you calling a method that always return true?
     */
    @Deprecated
    public boolean contains(TopLevelItem view) {
        return true;
    }

    public synchronized View getView(String name) {
        if(views!=null) {
            for (View v : views) {
                if(v.getViewName().equals(name))
                    return v;
            }
        }
        if (this.getViewName().equals(name))
            return this;
        return null;
    }

    /**
     * Gets the read-only list of all {@link View}s.
     */
    @Exported
    public synchronized Collection<View> getViews() {
        if(views==null)
            return Collections.<View>singletonList(this);

        List<View> copy = new ArrayList<View>(views.size()+1);
        copy.add(this);
        copy.addAll(views);
        Collections.sort(copy, View.SORTER);
        return copy;
    }

    public synchronized void deleteView(View view) throws IOException {
        if(views!=null) {
            views.remove(view);
            save();
        }
    }

    /**
     * Gets the read-only list of all {@link Computer}s.
     */
    public Computer[] getComputers() {
        Computer[] r = computers.values().toArray(new Computer[computers.size()]);
        Arrays.sort(r,new Comparator<Computer>() {
            public int compare(Computer lhs, Computer rhs) {
                if(lhs.getNode()==Hudson.this)  return -1;
                if(rhs.getNode()==Hudson.this)  return 1;
                return lhs.getDisplayName().compareTo(rhs.getDisplayName());
            }
        });
        return r;
    }

    /*package*/ Computer getComputer(Node n) {
        return computers.get(n);
    }

    public Computer getComputer(String name) {
        if(name.equals("(master)"))
            name = "";

        for (Computer c : computers.values()) {
            if(c.getNode().getNodeName().equals(name))
                return c;
        }
        return null;
    }

    /**
     * @deprecated
     *      UI method. Not meant to be used programatically.
     */
    public ComputerSet getComputer() {
        return new ComputerSet();
    }

    public Computer toComputer() {
        return getComputer(this);
    }

    /**
     * Gets the label that exists on this system by the name.
     *
     * @return null if no such label exists.
     */
    public Label getLabel(String name) {
        if(name==null)  return null;
        while(true) {
            Label l = labels.get(name);
            if(l!=null)
                return l;

            // non-existent
            labels.putIfAbsent(name,new Label(name));
        }
    }

    /**
     * Gets all the active labels in the current system.
     */
    public Set<Label> getLabels() {
        Set<Label> r = new TreeSet<Label>();
        for (Label l : labels.values()) {
            if(!l.getNodes().isEmpty())
                r.add(l);
        }
        return r;
    }

    public Queue getQueue() {
        return queue;
    }

    public String getDisplayName() {
        return Messages.Hudson_DisplayName();
    }

    public List<JDK> getJDKs() {
        if(jdks==null)
            jdks = new ArrayList<JDK>();
        return jdks;
    }

    /**
     * Gets the JDK installation of the given name, or returns null.
     */
    public JDK getJDK(String name) {
        if(name==null) {
            // if only one JDK is configured, "default JDK" should mean that JDK.
            List<JDK> jdks = getJDKs();
            if(jdks.size()==1)  return jdks.get(0);
            return null;
        }
        for (JDK j : getJDKs()) {
            if(j.getName().equals(name))
                return j;
        }
        return null;
    }

    /**
     * Gets the slave node of the give name, hooked under this Hudson.
     */
    public Slave getSlave(String name) {
        for (Slave s : getSlaves()) {
            if(s.getNodeName().equals(name))
                return s;
        }
        return null;
    }

    public List<Slave> getSlaves() {
        return Collections.unmodifiableList(slaves);
    }

    /**
     * Updates the slave list.
     */
    public void setSlaves(List<Slave> slaves) throws IOException {
        this.slaves = new ArrayList<Slave>(slaves);
        updateComputerList();

        // label trim off
        for (Iterator<Label> itr = labels.values().iterator(); itr.hasNext();) {
            Label l = itr.next();
            l.reset();
            if(l.getNodes().isEmpty())
                itr.remove();
        }

        save();
    }

    /**
     * Gets the system default quiet period.
     */
    public int getQuietPeriod() {
        return quietPeriod!=null ? quietPeriod : 5;
    }

    /**
     * @deprecated
     *      Why are you calling a method that always returns ""?
     *      Perhaps you meant {@link #getRootUrl()}.
     */
    public String getUrl() {
        return "";
    }

    public void onViewRenamed(View view, String oldName, String newName) {
        // implementation of Hudson is immune to view name change.
    }

    @Override
    public SearchIndexBuilder makeSearchIndex() {
        return super.makeSearchIndex()
            .add("configure", "config","configure")
            .add("manage")
            .add("log")
            .add(new CollectionSearchIndex() {// for computers
                protected Computer get(String key) { return getComputer(key); }
                protected Collection<Computer> all() { return computers.values(); }
            })
            .add(new CollectionSearchIndex() {// for users
                protected User get(String key) { return User.get(key,false); }
                protected Collection<User> all() { return User.getAll(); }
            })
            .add(new CollectionSearchIndex() {// for views
                protected View get(String key) { return getView(key); }
                protected Collection<View> all() { return views; }
            });
    }

    public String getUrlChildPrefix() {
        return "job";
    }

    /**
     * Gets the absolute URL of Hudson,
     * such as "http://localhost/hudson/".
     *
     * <p>
     * Also note that when serving user requests from HTTP, you should always use
     * {@link HttpServletRequest} to determine the full URL, instead of using this
     * (this is because one host may have multiple names, and {@link HttpServletRequest}
     * accurately represents what the current user used.)
     *
     * <p>
     * This information is rather only meant to be useful for sending out messages
     * via non-HTTP channels, like SMTP or IRC, with a link back to Hudson website.
     *
     * @return
     *      This method returns null if this parameter is not configured by the user.
     *      The caller must gracefully deal with this situation.
     *      The returned URL will always have the trailing '/'.
     * @since 1.66
     * @see Descriptor#getCheckUrl(String)
     * @see #getRootUrlFromRequest()
     */
    public String getRootUrl() {
        // for compatibility. the actual data is stored in Mailer
        String url = Mailer.DESCRIPTOR.getUrl();
        if(url!=null)   return url;

        StaplerRequest req = Stapler.getCurrentRequest();
        if(req!=null)
            return getRootUrlFromRequest();
        return null;
    }

    /**
     * Gets the absolute URL of Hudson top page, such as "http://localhost/hudson/".
     *
     * <p>
     * Unlike {@link #getRootUrl()}, which uses the manually configured value,
     * this one uses the current request to reconstruct the URL. The benefit is
     * that this is immune to the configuration mistake (users often fail to set the root URL
     * correctly, especially when a migration is involved), but the downside
     * is that unless you are processing a request, this method doesn't work.
     *
     * @since 1.263
     */
    public String getRootUrlFromRequest() {
        StaplerRequest req = Stapler.getCurrentRequest();
        StringBuilder buf = new StringBuilder();
        buf.append("http://");
        buf.append(req.getServerName());
        if(req.getServerPort()!=80)
            buf.append(':').append(req.getServerPort());
        buf.append(req.getContextPath()).append('/');
        return buf.toString();
    }

    public File getRootDir() {
        return root;
    }

    public FilePath getWorkspaceFor(TopLevelItem item) {
        return new FilePath(new File(item.getRootDir(),"workspace"));
    }

    public FilePath getRootPath() {
        return new FilePath(getRootDir());
    }

    public FilePath createPath(String absolutePath) {
        return new FilePath((VirtualChannel)null,absolutePath);
    }

    public ClockDifference getClockDifference() {
        return ClockDifference.ZERO;
    }

    /**
     * For binding {@link LogRecorderManager} to "/log".
     * Everything below here is admin-only, so do the check here.
     */
    public LogRecorderManager getLog() {
        checkPermission(ADMINISTER);
        return log;
    }

    /**
     * A convenience method to check if there's some security
     * restrictions in place.
     */
    public boolean isUseSecurity() {
        return securityRealm!=SecurityRealm.NO_AUTHENTICATION || authorizationStrategy!=AuthorizationStrategy.UNSECURED;
    }

    /**
     * Returns the constant that captures the three basic security modes
     * in Hudson.
     */
    public SecurityMode getSecurity() {
        // fix the variable so that this code works under concurrent modification to securityRealm.
        SecurityRealm realm = securityRealm;

        if(realm==SecurityRealm.NO_AUTHENTICATION)
            return SecurityMode.UNSECURED;
        if(realm instanceof LegacySecurityRealm)
            return SecurityMode.LEGACY;
        return SecurityMode.SECURED;
    }

    /**
     * @return
     *      never null.
     */
    public SecurityRealm getSecurityRealm() {
        return securityRealm;
    }

    public void setSecurityRealm(SecurityRealm securityRealm) {
        if(securityRealm==null)
            securityRealm= SecurityRealm.NO_AUTHENTICATION;
        this.securityRealm = securityRealm;
        SecurityComponents sc = securityRealm.createSecurityComponents();
        HudsonFilter.AUTHENTICATION_MANAGER.setDelegate(sc.manager);
        HudsonFilter.USER_DETAILS_SERVICE_PROXY.setDelegate(sc.userDetails);
    }
    
    public Lifecycle getLifecycle() {
        return Lifecycle.get();
    }

    /**
     * Returns the root {@link ACL}.
     *
     * @see AuthorizationStrategy#getRootACL()
     */
    public ACL getACL() {
        return authorizationStrategy.getRootACL();
    }

    @Override
    public void onJobRenamed(Item item, String oldName, String newName) {
        // noop
    }

    /**
     * @return
     *      never null.
     */
    public AuthorizationStrategy getAuthorizationStrategy() {
        return authorizationStrategy;
    }

    /**
     * Returns true if Hudson is quieting down.
     * <p>
     * No further jobs will be executed unless it
     * can be finished while other current pending builds
     * are still in progress.
     */
    public boolean isQuietingDown() {
        return isQuietingDown;
    }

    /**
     * Returns true if the container initiated the termination of the web application.
     */
    public boolean isTerminating() {
        return terminating;
    }

    public void setNumExecutors(int n) throws IOException {
        this.numExecutors = n;
        save();
    }

    /**
     * @deprecated
     *      Left only for the compatibility of URLs.
     *      Should not be invoked for any other purpose.
     */
    public TopLevelItem getJob(String name) {
        return getItem(name);
    }

    /**
     * @deprecated
     *      Used only for mapping jobs to URL in a case-insensitive fashion.
     */
    public TopLevelItem getJobCaseInsensitive(String name) {
        for (Entry<String, TopLevelItem> e : items.entrySet()) {
            if(Functions.toEmailSafeString(e.getKey()).equalsIgnoreCase(Functions.toEmailSafeString(name)))
                return e.getValue();
        }
        return null;
    }

    /**
     * {@inheritDoc}.
     *
     * Note that the look up is case-insensitive.
     */
    @Override
    public TopLevelItem getItem(String name) {
        return items.get(name);
    }

    public File getRootDirFor(TopLevelItem child) {
        return getRootDirFor(child.getName());
    }

    private File getRootDirFor(String name) {
        return new File(new File(getRootDir(),"jobs"), name);
    }

    /**
     * Gets the {@link Item} object by its full name.
     * Full names are like path names, where each name of {@link Item} is
     * combined by '/'.
     *
     * @return
     *      null if either such {@link Item} doesn't exist under the given full name,
     *      or it exists but it's no an instance of the given type.
     */
    public <T extends Item> T getItemByFullName(String fullName, Class<T> type) {
        StringTokenizer tokens = new StringTokenizer(fullName,"/");
        ItemGroup parent = this;

        while(true) {
            Item item = parent.getItem(tokens.nextToken());
            if(!tokens.hasMoreTokens()) {
                if(type.isInstance(item))
                    return type.cast(item);
                else
                    return null;
            }

            if(!(item instanceof ItemGroup))
                return null;    // this item can't have any children

            parent = (ItemGroup) item;
        }
    }

    public Item getItemByFullName(String fullName) {
        return getItemByFullName(fullName,Item.class);
    }

    /**
     * Gets the user of the given name.
     *
     * @return
     *      This method returns a non-null object for any user name, without validation.
     */
    public User getUser(String name) {
        return User.get(name);
    }

    /**
     * Creates a new job.
     *
     * @throws IllegalArgumentException
     *      if the project of the given name already exists.
     */
    public synchronized TopLevelItem createProject( TopLevelItemDescriptor type, String name ) throws IOException {
        if(items.containsKey(name))
            throw new IllegalArgumentException();

        TopLevelItem item;
        try {
            item = type.newInstance(name);
        } catch (Exception e) {
            throw new IllegalArgumentException(e);
        }

        item.save();
        items.put(name,item);
        return item;
    }

    /**
     * Called in response to {@link Job#doDoDelete(StaplerRequest, StaplerResponse)}
     */
    /*package*/ void deleteJob(TopLevelItem item) throws IOException {
        for (ItemListener l : itemListeners)
            l.onDeleted(item);

        items.remove(item.getName());
        if(views!=null) {
            for (View v : views)
                v.onJobRenamed(item, item.getName(), null);
            save();
        }
    }

    /**
     * Called by {@link Job#renameTo(String)} to update relevant data structure.
     * assumed to be synchronized on Hudson by the caller.
     */
    /*package*/ void onRenamed(TopLevelItem job, String oldName, String newName) throws IOException {
        items.remove(oldName);
        items.put(newName,job);

        if(views!=null) {
            for (View v : views)
                v.onJobRenamed(job, oldName, newName);
            save();
        }
    }

    public FingerprintMap getFingerprintMap() {
        return fingerprintMap;
    }

    // if no finger print matches, display "not found page".
    public Object getFingerprint( String md5sum ) throws IOException {
        Fingerprint r = fingerprintMap.get(md5sum);
        if(r==null)     return new NoFingerprintMatch(md5sum);
        else            return r;
    }

    /**
     * Gets a {@link Fingerprint} object if it exists.
     * Otherwise null.
     */
    public Fingerprint _getFingerprint( String md5sum ) throws IOException {
        return fingerprintMap.get(md5sum);
    }

    /**
     * The file we save our configuration.
     */
    private XmlFile getConfigFile() {
        return new XmlFile(XSTREAM, new File(root,"config.xml"));
    }

    public int getNumExecutors() {
        return numExecutors;
    }

    public Mode getMode() {
        return mode;
    }

    public Set<Label> getAssignedLabels() {
        if (labelSet == null) {
            Set<Label> r = new HashSet<Label>();
            r.addAll(getDynamicLabels());
            r.add(getSelfLabel());
            this.labelSet = Collections.unmodifiableSet(r);
        }
        return labelSet;
    }

    /**
     * Returns the possibly empty set of labels that it has been determined as supported by this node.
     *
     * @see hudson.tasks.LabelFinder
     */
    public Set<Label> getDynamicLabels() {
        if (dynamicLabels == null) {
            // in the worst cast, two threads end up doing the same computation twice,
            // but that won't break the semantics.
            // OTOH, not locking prevents dead-lock. See #1390
            Set<Label> r = new HashSet<Label>();
            Computer comp = getComputer("");
            if (comp != null) {
                VirtualChannel channel = comp.getChannel();
                if (channel != null) {
                    for (DynamicLabeler labeler : LabelFinder.LABELERS) {
                        for (String label : labeler.findLabels(channel)) {
                            r.add(getLabel(label));
                        }
                    }
                }
            }
            dynamicLabels = r;
        }
        return dynamicLabels;
    }

    public Label getSelfLabel() {
        return getLabel("master");
    }

    public Computer createComputer() {
        return new MasterComputer();
    }

    private synchronized void load() throws IOException {
        long startTime = System.currentTimeMillis();
        XmlFile cfg = getConfigFile();
        if(cfg.exists())
            cfg.unmarshal(this);

        File projectsDir = new File(root,"jobs");
        if(!projectsDir.isDirectory() && !projectsDir.mkdirs()) {
            if(projectsDir.exists())
                throw new IOException(projectsDir+" is not a directory");
            throw new IOException("Unable to create "+projectsDir+"\nPermission issue? Please create this directory manually.");
        }
        File[] subdirs = projectsDir.listFiles(new FileFilter() {
            public boolean accept(File child) {
                return child.isDirectory() && Items.getConfigFile(child).exists();
            }
        });
        items.clear();
        if(PARALLEL_LOAD) {
            // load jobs in parallel for better performance
            LOGGER.info("Loading in "+TWICE_CPU_NUM+" parallel threads");
            List<Future<TopLevelItem>> loaders = new ArrayList<Future<TopLevelItem>>();
            for (final File subdir : subdirs) {
                loaders.add(threadPoolForLoad.submit(new Callable<TopLevelItem>() {
                    public TopLevelItem call() throws Exception {
                        long start = System.currentTimeMillis();
                        TopLevelItem item = (TopLevelItem) Items.load(Hudson.this, subdir);
                        if(LOG_STARTUP_PERFORMANCE)
                            LOGGER.info("Loaded "+item.getName()+" in "+(System.currentTimeMillis()-start)+"ms by "+Thread.currentThread().getName());
                        return item;
                    }
                }));
            }

            for (Future<TopLevelItem> loader : loaders) {
                try {
                    TopLevelItem item = loader.get();
                    items.put(item.getName(), item);
                } catch (ExecutionException e) {
                    LOGGER.log(Level.WARNING, "Failed to load a project",e.getCause());
                } catch (InterruptedException e) {
                    e.printStackTrace(); // this is probably not the right thing to do
                }
            }
        } else {
            for (File subdir : subdirs) {
                try {
                    long start = System.currentTimeMillis();
                    TopLevelItem item = (TopLevelItem)Items.load(this,subdir);
                    if(LOG_STARTUP_PERFORMANCE)
                        LOGGER.info("Loaded "+item.getName()+" in "+(System.currentTimeMillis()-start)+"ms");
                    items.put(item.getName(), item);
                } catch (Error e) {
                    LOGGER.log(Level.WARNING, "Failed to load "+subdir,e);
                } catch (RuntimeException e) {
                    LOGGER.log(Level.WARNING, "Failed to load "+subdir,e);
                } catch (IOException e) {
                    LOGGER.log(Level.WARNING, "Failed to load "+subdir,e);
                }
            }
        }
        rebuildDependencyGraph();

        // recompute label objects
        if (null != slaves) { // only if we have slaves
            for (Slave slave : slaves)
                slave.getAssignedLabels();
        }

        // read in old data that doesn't have the security field set
        if(authorizationStrategy==null) {
            if(useSecurity==null || !useSecurity)
                authorizationStrategy = AuthorizationStrategy.UNSECURED;
            else
                authorizationStrategy = new LegacyAuthorizationStrategy();
        }
        if(securityRealm==null) {
            if(useSecurity==null || !useSecurity)
                setSecurityRealm(SecurityRealm.NO_AUTHENTICATION);
            else
                setSecurityRealm(new LegacySecurityRealm());
        } else {
            // force the set to proxy
            setSecurityRealm(securityRealm);
        }

        if(useSecurity!=null && !useSecurity) {
            // forced reset to the unsecure mode.
            // this works as an escape hatch for people who locked themselves out.
            authorizationStrategy = AuthorizationStrategy.UNSECURED;
            setSecurityRealm(SecurityRealm.NO_AUTHENTICATION);
        }


        LOGGER.info(String.format("Took %s ms to load",System.currentTimeMillis()-startTime));
        if(KILL_AFTER_LOAD)
            System.exit(0);
    }

    /**
     * Save the settings to a file.
     */
    public synchronized void save() throws IOException {
        if(BulkChange.contains(this))   return;
        getConfigFile().write(this);
    }


    /**
     * Called to shut down the system.
     */
    public void cleanUp() {
        terminating = true;
        for( Computer c : computers.values() ) {
            c.interrupt();
            c.kill();
            c.disconnect();
        }
        ExternalJob.reloadThread.interrupt();
        Trigger.timer.cancel();
        Trigger.timer = null;
        if(tcpSlaveAgentListener!=null)
            tcpSlaveAgentListener.shutdown();

        if(pluginManager!=null) // be defensive. there could be some ugly timing related issues
            pluginManager.stop();

        if(getRootDir().exists())
            // if we are aborting because we failed to create HUDSON_HOME,
            // don't try to save. Issue #536
            getQueue().save();

        threadPoolForLoad.shutdown();
        
        LogFactory.releaseAll();

        theInstance = null;
    }

    public Object getDynamic(String token, StaplerRequest req, StaplerResponse rsp) {
        for (Action a : getActions())
            if(a.getUrlName().equals(token))
                return a;
        for (Action a : getManagementLinks())
            if(a.getUrlName().equals(token))
                return a;
        return null;
    }


//
//
// actions
//
//
    /**
     * Accepts submission from the configuration page.
     */
    public synchronized void doConfigSubmit( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        try {
            checkPermission(ADMINISTER);

            req.setCharacterEncoding("UTF-8");

            JSONObject json = req.getSubmittedForm();

            // keep using 'useSecurity' field as the main configuration setting
            // until we get the new security implementation working
            // useSecurity = null;
            if (json.has("use_security")) {
                useSecurity = true;
                JSONObject security = json.getJSONObject("use_security");
                setSecurityRealm(SecurityRealm.LIST.newInstanceFromRadioList(security,"realm"));
                authorizationStrategy = AuthorizationStrategy.LIST.newInstanceFromRadioList(security,"authorization");
                if(authorizationStrategy==null)
                    authorizationStrategy = AuthorizationStrategy.UNSECURED;
            } else {
                useSecurity = null;
                setSecurityRealm(SecurityRealm.NO_AUTHENTICATION);
                authorizationStrategy = AuthorizationStrategy.UNSECURED;
            }

            noUsageStatistics = json.has("usageStatisticsCollected") ? null : true;

            {
                String v = req.getParameter("slaveAgentPortType");
                if(!isUseSecurity() || v==null || v.equals("random"))
                    slaveAgentPort = 0;
                else
                if(v.equals("disable"))
                    slaveAgentPort = -1;
                else {
                    try {
                        slaveAgentPort = Integer.parseInt(req.getParameter("slaveAgentPort"));
                    } catch (NumberFormatException e) {
                        throw new FormException(Messages.Hudson_BadPortNumber(req.getParameter("slaveAgentPort")),"slaveAgentPort");
                    }
                }

                // relaunch the agent
                if(tcpSlaveAgentListener==null) {
                    if(slaveAgentPort!=-1)
                        tcpSlaveAgentListener = new TcpSlaveAgentListener(slaveAgentPort);
                } else {
                    if(tcpSlaveAgentListener.configuredPort!=slaveAgentPort) {
                        tcpSlaveAgentListener.shutdown();
                        tcpSlaveAgentListener = null;
                        if(slaveAgentPort!=-1)
                            tcpSlaveAgentListener = new TcpSlaveAgentListener(slaveAgentPort);
                    }
                }
            }

            quietPeriod = Integer.parseInt(req.getParameter("quiet_period"));

            systemMessage = Util.nullify(req.getParameter("system_message"));

            {// update JDK installations
                jdks.clear();
                String[] names = req.getParameterValues("jdk_name");
                String[] homes = req.getParameterValues("jdk_home");
                if(names!=null && homes!=null) {
                    int len = Math.min(names.length,homes.length);
                    for(int i=0;i<len;i++) {
                        jdks.add(new JDK(names[i],homes[i]));
                    }
                }
            }

            boolean result = true;

            for( Descriptor<Builder> d : BuildStep.BUILDERS )
                result &= configureDescriptor(req,json,d);

            for( Descriptor<Publisher> d : BuildStep.PUBLISHERS )
                result &= configureDescriptor(req,json,d);

            for( Descriptor<BuildWrapper> d : BuildWrappers.WRAPPERS )
                result &= configureDescriptor(req,json,d);

            for( SCMDescriptor scmd : SCMS.SCMS )
                result &= configureDescriptor(req,json,scmd);

            for( TriggerDescriptor d : Triggers.TRIGGERS )
                result &= configureDescriptor(req,json,d);

            for( JobPropertyDescriptor d : Jobs.PROPERTIES )
                result &= configureDescriptor(req,json,d);

            for( PageDecorator d : PageDecorator.ALL )
                result &= configureDescriptor(req,json,d);

            for( JSONObject o : StructuredForm.toList(json,"plugin"))
                pluginManager.getPlugin(o.getString("name")).getPlugin().configure(o);

            save();
            if(result)
                rsp.sendRedirect(req.getContextPath()+'/');  // go to the top page
            else
                rsp.sendRedirect("configure"); // back to config
        } catch (FormException e) {
            sendError(e,req,rsp);
        }
    }

    public synchronized void doTestPost( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        JSONObject form = req.getSubmittedForm();
        rsp.sendRedirect("foo");
    }

    private boolean configureDescriptor(StaplerRequest req, JSONObject json, Descriptor<?> d) throws FormException {
        // collapse the structure to remain backward compatible with the JSON structure before 1.
        String name = d.getJsonSafeClassName();
        JSONObject js = json.has(name) ? json.getJSONObject(name) : new JSONObject(); // if it doesn't have the property, the method returns invalid null object.
        json.putAll(js);
        return d.configure(req, js);
    }

    /**
     * Accepts submission from the configuration page.
     */
    public synchronized void doConfigExecutorsSubmit( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        checkPermission(ADMINISTER);

        BulkChange bc = new BulkChange(this);
        try {
            JSONObject json = req.getSubmittedForm();

            setNumExecutors(Integer.parseInt(req.getParameter("numExecutors")));
            if(req.hasParameter("master.mode"))
                mode = Mode.valueOf(req.getParameter("master.mode"));
            else
                mode = Mode.NORMAL;

            setSlaves(req.bindJSONToList(Slave.class,json.get("slaves")));
        } finally {
            bc.commit();
        }

        rsp.sendRedirect(req.getContextPath()+'/');  // go to the top page
    }

    /**
     * Accepts the new description.
     */
    public synchronized void doSubmitDescription( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        checkPermission(ADMINISTER);

        req.setCharacterEncoding("UTF-8");
        systemMessage = req.getParameter("description");
        save();
        rsp.sendRedirect(".");
    }

    public synchronized void doQuietDown(StaplerResponse rsp) throws IOException, ServletException {
        checkPermission(ADMINISTER);
        isQuietingDown = true;
        rsp.sendRedirect2(".");
    }

    public synchronized void doCancelQuietDown(StaplerResponse rsp) throws IOException, ServletException {
        checkPermission(ADMINISTER);
        isQuietingDown = false;
        getQueue().scheduleMaintenance();
        rsp.sendRedirect2(".");
    }

    /**
     * Backward compatibility. Redirect to the thread dump.
     */
    public void doClassicThreadDump(StaplerResponse rsp) throws IOException, ServletException {
        rsp.sendRedirect2("threadDump");
    }

    public synchronized Item doCreateItem( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        checkPermission(Job.CREATE);

        TopLevelItem result;

        String requestContentType = req.getContentType();
        if(requestContentType==null) {
            rsp.sendError(HttpServletResponse.SC_BAD_REQUEST,"No Content-Type header set");
            return null;
        }
        boolean isXmlSubmission = requestContentType.startsWith("application/xml") || requestContentType.startsWith("text/xml");
        if(!isXmlSubmission) {
            // containers often implement RFCs incorrectly in that it doesn't interpret query parameter
            // decoding with UTF-8. This will ensure we get it right.
            // but doing this for config.xml submission could potentiall overwrite valid
            // "text/xml;charset=xxx"
            req.setCharacterEncoding("UTF-8");
        }

        String name = req.getParameter("name");
        if(name==null) {
            rsp.sendError(HttpServletResponse.SC_BAD_REQUEST,"Query parameter 'name' is required");
            return null;
        }
        name = name.trim();
        String mode = req.getParameter("mode");

        try {
            checkGoodName(name);
        } catch (ParseException e) {
            rsp.setStatus(SC_BAD_REQUEST);
            sendError(e,req,rsp);
            return null;
        }

        if(getItem(name)!=null) {
            rsp.setStatus(SC_BAD_REQUEST);
            sendError(Messages.Hudson_JobAlreadyExists(name),req,rsp);
            return null;
        }

        if(mode!=null && mode.equals("copyJob")) {
            String from = req.getParameter("from");
            TopLevelItem src = getItem(from);
            if(src==null) {
                rsp.setStatus(SC_BAD_REQUEST);
                if(Util.fixEmpty(from)==null)
                    sendError("Specify which job to copy",req,rsp);
                else
                    sendError("No such job: "+from,req,rsp);
                return null;
            }

            result = createProject(src.getDescriptor(),name);

            // copy config
            Util.copyFile(Items.getConfigFile(src).getFile(),Items.getConfigFile(result).getFile());

            // reload from the new config
            result = (TopLevelItem)Items.load(this,result.getRootDir());
            result.onCopiedFrom(src);
            items.put(name,result);
        } else {
            if(isXmlSubmission) {
                // config.xml submission

                // first copy it as config.xml
                File configXml = Items.getConfigFile(getRootDirFor(name)).getFile();
                configXml.getParentFile().mkdirs();
                try {
                    FileOutputStream fos = new FileOutputStream(configXml);
                    try {
                        Util.copyStream(req.getInputStream(),fos);
                    } finally {
                        fos.close();
                    }

                    // load it
                    result = (TopLevelItem)Items.load(this,configXml.getParentFile());
                    items.put(name,result);
                } catch (IOException e) {
                    // if anything fails, delete the config file to avoid further confusion
                    Util.deleteRecursive(configXml.getParentFile());
                    throw e;
                }
            } else {
                // create empty job and redirect to the project config screen
                if(mode==null) {
                    rsp.sendError(SC_BAD_REQUEST);
                    return null;
                }
                result = createProject(Items.getDescriptor(mode), name);
            }
        }

        for (ItemListener l : itemListeners)
            l.onCreated(result);

        if(isXmlSubmission) {
            // it worked
            rsp.setStatus(HttpServletResponse.SC_OK);
        } else {
            // send the browser to the config page
            rsp.sendRedirect2(result.getUrl()+"configure");
        }

        return result;
    }

    public synchronized void doCreateView( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        try {
            checkPermission(View.CREATE);

            req.setCharacterEncoding("UTF-8");

            String name = req.getParameter("name");
            String mode = req.getParameter("mode");

            try {
                checkGoodName(name);
            } catch (ParseException e) {
                sendError(e, req, rsp);
                return;
            }

            // create a view
            View v = View.LIST.findByName(mode).newInstance(req,req.getSubmittedForm());
            v.owner = this;
            if(views==null)
                views = new Vector<View>();
            views.add(v);
            save();

            // redirect to the config screen
            rsp.sendRedirect2("./"+v.getUrl()+v.getPostConstructLandingPage());
        } catch (FormException e) {
            sendError(e,req,rsp);
        }
    }

    /**
     * Check if the given name is suitable as a name
     * for job, view, etc.
     *
     * @throws ParseException
     *      if the given name is not good
     */
    public static void checkGoodName(String name) throws ParseException {
        if(name==null || name.length()==0)
            throw new ParseException(Messages.Hudson_NoName(),0);

        for( int i=0; i<name.length(); i++ ) {
            char ch = name.charAt(i);
            if(Character.isISOControl(ch)) {
                throw new ParseException(Messages.Hudson_ControlCodeNotAllowed(toPrintableName(name)),i);
            }
            if("?*/\\%!@#$^&|<>[]:;".indexOf(ch)!=-1)
                throw new ParseException(Messages.Hudson_UnsafeChar(ch),i);
        }

        // looks good
    }

    private static String toPrintableName(String name) {
        StringBuffer printableName = new StringBuffer();
        for( int i=0; i<name.length(); i++ ) {
            char ch = name.charAt(i);
            if(Character.isISOControl(ch))
                printableName.append("\\u").append((int)ch).append(';');
            else
                printableName.append(ch);
        }
        return printableName.toString();
    }

    /**
     * Checks if the user was successfully authenticated.
     *
     * @see BasicAuthenticationFilter
     */
    public void doSecured( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        if(req.getUserPrincipal()==null) {
            // authentication must have failed
            rsp.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
            return;
        }

        // the user is now authenticated, so send him back to the target
        String path = req.getContextPath()+req.getRestOfPath();
        String q = req.getQueryString();
        if(q!=null)
            path += '?'+q;

        rsp.sendRedirect2(path);
    }

    /**
     * Called once the user logs in. Just forward to the top page.
     */
    public void doLoginEntry( StaplerRequest req, StaplerResponse rsp ) throws IOException {
        if(req.getUserPrincipal()==null)
            rsp.sendRedirect2("noPrincipal");

        String from = req.getParameter("from");
        if(from!=null && from.startsWith("/") && !from.equals("/loginError")) {
            rsp.sendRedirect2(from);    // I'm bit uncomfortable letting users redircted to other sites, make sure the URL falls into this domain
            return;
        }

        String url = AbstractProcessingFilter.obtainFullRequestUrl(req);
        if(url!=null) {
            // if the login redirect is initiated by Acegi
            // this should send the user back to where s/he was from.
            rsp.sendRedirect2(url);
            return;
        }

        rsp.sendRedirect2(".");
    }

    /**
     * Called once the user logs in. Just forward to the top page.
     */
    public void doLogout( StaplerRequest req, StaplerResponse rsp ) throws IOException {
        HttpSession session = req.getSession(false);
        if(session!=null)
            session.invalidate();
        SecurityContextHolder.clearContext();

        // reset remember-me cookie
        Cookie cookie = new Cookie(ACEGI_SECURITY_HASHED_REMEMBER_ME_COOKIE_KEY,"");
        cookie.setPath(req.getContextPath().length()>0 ? req.getContextPath() : "/");
        rsp.addCookie(cookie);

        rsp.sendRedirect2(req.getContextPath()+"/");
    }

    /**
     * Serves jar files for JNLP slave agents.
     */
    public Slave.JnlpJar getJnlpJars(String fileName) {
        return new Slave.JnlpJar(fileName);
    }

    /**
     * RSS feed for log entries.
     *
     * @deprecated
     *   As on 1.267, moved to "/log/rss..."
     */
    public void doLogRss( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        String qs = req.getQueryString();
        rsp.sendRedirect2("./log/rss"+(qs==null?"":'?'+qs));
    }

    /**
     * Reloads the configuration.
     */
    public synchronized void doReload( StaplerRequest req, StaplerResponse rsp ) throws IOException {
        checkPermission(ADMINISTER);

        // engage "loading ..." UI and then run the actual task in a separate thread
        final ServletContext context = req.getServletContext();
        context.setAttribute("app",new HudsonIsLoading());

        rsp.sendRedirect2(req.getContextPath()+"/");

        new Thread("Hudson config reload thread") {
            public void run() {
                try {
                    load();
                    User.reload();
                    context.setAttribute("app",Hudson.this);
                } catch (IOException e) {
                    LOGGER.log(Level.SEVERE,"Failed to reload Hudson config",e);
                }
            }
        }.start();
    }

    /**
     * Do a finger-print check.
     */
    public void doDoFingerprintCheck( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        // Parse the request
        MultipartFormDataParser p = new MultipartFormDataParser(req);
        try {
            rsp.sendRedirect2(req.getContextPath()+"/fingerprint/"+
                Util.getDigestOf(p.getFileItem("name").getInputStream())+'/');
        } finally {
            p.cleanUp();
        }
    }

    /**
     * Serves static resources without the "Last-Modified" header to work around
     * a bug in Firefox.
     *
     * <p>
     * See https://bugzilla.mozilla.org/show_bug.cgi?id=89419
     */
    public void doNocacheImages( StaplerRequest req, StaplerResponse rsp ) throws IOException {
        String path = req.getRestOfPath();

        if(path.length()==0)
            path = "/";

        if(path.indexOf("..")!=-1 || path.length()<1) {
            // don't serve anything other than files in the artifacts dir
            rsp.sendError(SC_BAD_REQUEST);
            return;
        }

        File f = new File(req.getServletContext().getRealPath("/images"),path.substring(1));
        if(!f.exists()) {
            rsp.sendError(SC_NOT_FOUND);
            return;
        }

        if(f.isDirectory()) {
            // listing not allowed
            rsp.sendError(HttpServletResponse.SC_FORBIDDEN);
            return;
        }

        FileInputStream in = new FileInputStream(f);
        // serve the file
        String contentType = req.getServletContext().getMimeType(f.getPath());
        rsp.setContentType(contentType);
        rsp.setContentLength((int)f.length());
        Util.copyStream(in,rsp.getOutputStream());
        in.close();
    }

    /**
     * For debugging. Expose URL to perform GC.
     */
    public void doGc(StaplerResponse rsp) throws IOException {
        System.gc();
        rsp.setStatus(HttpServletResponse.SC_OK);
        rsp.setContentType("text/plain");
        rsp.getWriter().println("GCed");
    }

    /**
     * Perform a restart of Hudson, if we can.
     */
    public void doRestart(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
        requirePOST();
        checkPermission(ADMINISTER);
        try {
            Lifecycle.get().restart();
            servletContext.setAttribute("app",new HudsonIsRestarting());
            rsp.sendRedirect2(".");
        } catch (UnsupportedOperationException e) {
            sendError("Restart is not supported in this running mode.",req,rsp);
        } catch (IOException e) {
            sendError(e,req,rsp);
        } catch (InterruptedException e) {
            sendError(e,req,rsp);
        }
    }

    /**
     * Shutdown the system.
     * @since 1.161
     */
    public void doExit( StaplerRequest req, StaplerResponse rsp ) throws IOException {
        checkPermission(ADMINISTER);
        LOGGER.severe(String.format("Shutting down VM as requested by %s from %s",
                getAuthentication(), req.getRemoteAddr()));
        rsp.setStatus(HttpServletResponse.SC_OK);
        rsp.setContentType("text/plain");
        PrintWriter w = rsp.getWriter();
        w.println("Shutting down");
        w.close();

        System.exit(0);
    }

    /**
     * Gets the {@link Authentication} object that represents the user
     * associated with the current request.
     */
    public static Authentication getAuthentication() {
        Authentication a = SecurityContextHolder.getContext().getAuthentication();
        // on Tomcat while serving the login page, this is null despite the fact
        // that we have filters. Looking at the stack trace, Tomcat doesn't seem to
        // run the request through filters when this is the login request.
        // see http://www.nabble.com/Matrix-authorization-problem-tp14602081p14886312.html
        if(a==null)
            a = new AnonymousAuthenticationToken("anonymous","anonymous",new GrantedAuthority[]{new GrantedAuthorityImpl("anonymous")});
        return a;
    }

    /**
     * Configure the logging level.
     */
    public void doConfigLogger(StaplerResponse rsp, @QueryParameter String name, @QueryParameter String level) throws IOException {
        checkPermission(ADMINISTER);
        Level lv;
        if(level.equals("inherit"))
            lv = null;
        else
            lv = Level.parse(level.toUpperCase());
        Logger.getLogger(name).setLevel(lv);
        rsp.sendRedirect2("log");
    }

    /**
     * For system diagnostics.
     * Run arbitrary Groovy script.
     */
    public void doScript(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
        doScript(req, rsp, req.getView(this, "_script.jelly"));
    }
    
    /**
     * Run arbitrary Groovy script and return result as plain text.
     */
    public void doScriptText(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
        doScript(req, rsp, req.getView(this, "_scriptText.jelly"));
    }

    private void doScript(StaplerRequest req, StaplerResponse rsp, RequestDispatcher view) throws IOException, ServletException {
        // ability to run arbitrary script is dangerous
        checkPermission(ADMINISTER);

        String text = req.getParameter("script");
        if (text != null) {
            try {
                req.setAttribute("output",
                        RemotingDiagnostics.executeGroovy(text, MasterComputer.localChannel));
            } catch (InterruptedException e) {
                throw new ServletException(e);
            }
        }

        view.forward(req, rsp);
    }

    /**
     * Sign up for the user account.
     */
    public void doSignup( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        req.getView(getSecurityRealm(),"signup.jelly").forward(req,rsp);
    }

    /**
     * Changes the icon size by changing the cookie
     */
    public void doIconSize( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        String qs = req.getQueryString();
        if(qs==null || !ICON_SIZE.matcher(qs).matches())
            throw new ServletException();
        Cookie cookie = new Cookie("iconSize", qs);
        cookie.setMaxAge(/* ~4 mo. */9999999); // #762
        rsp.addCookie(cookie);
        String ref = req.getHeader("Referer");
        if(ref==null)   ref=".";
        rsp.sendRedirect2(ref);
    }

    public void doFingerprintCleanup(StaplerResponse rsp) throws IOException {
        FingerprintCleanupThread.invoke();
        rsp.setStatus(HttpServletResponse.SC_OK);
        rsp.setContentType("text/plain");
        rsp.getWriter().println("Invoked");
    }

    public void doWorkspaceCleanup(StaplerResponse rsp) throws IOException {
        WorkspaceCleanupThread.invoke();
        rsp.setStatus(HttpServletResponse.SC_OK);
        rsp.setContentType("text/plain");
        rsp.getWriter().println("Invoked");
    }

    /**
     * Checks if the path is a valid path.
     */
    public void doCheckLocalFSRoot( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        // this can be used to check the existence of a file on the server, so needs to be protected
        new FormFieldValidator.WorkspaceDirectory(req,rsp,true).process();
    }

    /**
     * Checks if the JAVA_HOME is a valid JAVA_HOME path.
     */
    public void doJavaHomeCheck( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        // this can be used to check the existence of a file on the server, so needs to be protected
        new FormFieldValidator(req,rsp,true) {
            public void check() throws IOException, ServletException {
                File f = getFileParameter("value");
                if(!f.isDirectory()) {
                    error(Messages.Hudson_NotADirectory(f));
                    return;
                }

                File toolsJar = new File(f,"lib/tools.jar");
                File mac = new File(f,"lib/dt.jar");
                if(!toolsJar.exists() && !mac.exists()) {
                    error(Messages.Hudson_NotJDKDir(f));
                    return;
                }

                ok();
            }
        }.process();
    }

    /**
     * If the user chose the default JDK, make sure we got 'java' in PATH.
     */
    public void doDefaultJDKCheck( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
        new FormFieldValidator(req,rsp,true) {
            public void check() throws IOException, ServletException {
                String v = request.getParameter("value");
                if(!v.equals("(Default)"))
                    // assume the user configured named ones properly in system config ---
                    // or else system config should have reported form field validation errors.
                    ok();
                else {
                    // default JDK selected. Does such java really exist?
                    if(JDK.isDefaultJDKValid(Hudson.this))
                        ok();
                    else
                        errorWithMarkup(Messages.Hudson_NoJavaInPath(request.getContextPath()));
                }
            }
        }.process();
    }

    /**
     * Checks if the top-level item with the given name exists.
     */
    public void doItemExistsCheck(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
        // this method can be used to check if a file exists anywhere in the file system,
        // so it should be protected.
        new FormFieldValidator(req,rsp,Item.CREATE) {
            protected void check() throws IOException, ServletException {
                String job = fixEmpty(request.getParameter("value"));
                if(job==null) {
                    ok(); // nothing is entered yet
                    return;
                }

                if(getItem(job)==null)
                    ok();
                else
                    error(Messages.Hudson_JobAlreadyExists(job));
            }
        }.process();
    }

    /**
     * Checks if a top-level view with the given name exists.
     */
    public void doViewExistsCheck(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
        new FormFieldValidator(req,rsp,View.CREATE) {
            protected void check() throws IOException, ServletException {
                String view = fixEmpty(request.getParameter("value"));
                if(view==null) {
                    ok(); // nothing is entered yet
                    return;
                }

                if(getView(view)==null)
                    ok();
                else
                    error(Messages.Hudson_ViewAlreadyExists(view));
            }
        }.process();
    }


    /**
     * Checks if the value for a field is set; if not an error or warning text is displayed.
     * If the parameter "value" is not set then the parameter "errorText" is displayed
     * as an error text. If the parameter "errorText" is not set, then the parameter "warningText" is
     * displayed as a warning text.
     * <p/>
     * If the text is set and the parameter "type" is set, it will validate that the value is of the
     * correct type. Supported types are "number, "number-positive" and "number-negative".
     * @param req containing the parameter value and the errorText to display if the value isnt set
     * @param rsp used by FormFieldValidator
     * @throws IOException thrown by FormFieldValidator.check()
     * @throws ServletException thrown by FormFieldValidator.check()
     */
    public void doFieldCheck(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
        new FormFieldValidator(req, rsp, false) {

            /**
             * Display the error text or warning text.
             */
            private void fieldCheckFailed() throws IOException, ServletException {
                String v = fixEmpty(request.getParameter("errorText"));
                if (v != null) {
                    error(v);
                    return;
                }
                v = fixEmpty(request.getParameter("warningText"));
                if (v != null) {
                    warning(v);
                    return;
                }
                error("No error or warning text was set for fieldCheck().");
                return;
            }

            /**
             * Checks if the value is of the correct type.
             * @param type the type of string
             * @param value the actual value to check
             * @return true, if the type was valid; false otherwise
             */
            private boolean checkType(String type, String value) throws IOException, ServletException {
                try {
                    if (type.equalsIgnoreCase("number")) {
                        NumberFormat.getInstance().parse(value);
                    } else if (type.equalsIgnoreCase("number-positive")) {
                        if (NumberFormat.getInstance().parse(value).floatValue() <= 0) {
                            error(Messages.Hudson_NotAPositiveNumber());
                            return false;
                        }
                    } else if (type.equalsIgnoreCase("number-negative")) {
                        if (NumberFormat.getInstance().parse(value).floatValue() >= 0) {
                            error(Messages.Hudson_NotANegativeNumber());
                            return false;
                        }
                    }
                } catch (ParseException e) {
                    error(Messages.Hudson_NotANumber());
                    return false;
                }
                return true;
            }

            @Override
            protected void check() throws IOException, ServletException {
                String value = fixEmpty(request.getParameter("value"));
                if (value == null) {
                    fieldCheckFailed();
                    return;
                }
                String type = fixEmpty(request.getParameter("type"));
                if (type != null) {
                    if (!checkType(type, value)) {
                        return;
                    }
                }
                ok();
            }
        }.process();
    }

    /**
     * Performs syntactical check on the remote FS for slaves.
     *
     * TODO: find a better home for this method.
     */
    public void doRemoteFSCheck(StaplerRequest req, StaplerResponse rsp, @QueryParameter final String value) throws IOException, ServletException {
        new FormFieldValidator(req,rsp,false) {
            protected void check() throws IOException, ServletException {
                if(Util.fixEmptyAndTrim(value)==null) {
                    error("Remote directory is mandatory");
                    return;
                }

                if(value.startsWith("\\\\") || value.startsWith("/net/")) {
                    warning("Are you sure you want to use network mounted file system for FS root? " +
                            "Note that this directory needs not be visible to the master.");
                    return;
                }

                ok();
            }
        }.process();
    }

    /**
     * Serves static resources placed along with Jelly view files.
     * <p>
     * This method can serve a lot of files, so care needs to be taken
     * to make this method secure. It's not clear to me what's the best
     * strategy here, though the current implementation is based on
     * file extensions.
     */
    public void doResources(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
        String path = req.getRestOfPath();
        // cut off the "..." portion of /resources/.../path/to/file
        // as this is only used to make path unique (which in turn
        // allows us to set a long expiration date
        path = path.substring(1);
        path = path.substring(path.indexOf('/')+1);

        int idx = path.lastIndexOf('.');
        String extension = path.substring(idx+1);
        if(ALLOWED_RESOURCE_EXTENSIONS.contains(extension)) {
            URL url = pluginManager.uberClassLoader.getResource(path);
            if(url!=null) {
                long expires = MetaClass.NO_CACHE ? 0 : 365L * 24 * 60 * 60 * 1000; /*1 year*/
                rsp.serveFile(req,url,expires);
                return;
            }
        }
        rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
    }

    /**
     * Extension list that {@link #doResources(StaplerRequest, StaplerResponse)} can serve.
     * This set is mutable to allow plugins to add additional extensions.
     */
    public static final Set<String> ALLOWED_RESOURCE_EXTENSIONS = new HashSet<String>(Arrays.asList(
        "js|css|jpeg|jpg|png|gif|html|htm".split("\\|")
    ));

    /**
     * Checks if container uses UTF-8 to decode URLs. See
     * http://hudson.gotdns.com/wiki/display/HUDSON/Tomcat#Tomcat-i18n
     *
     * @param req containing the parameter value
     * @param rsp used by FormFieldValidator
     * @throws IOException thrown by FormFieldValidator.check()
     * @throws ServletException thrown by FormFieldValidator.check()
     */
    public void doCheckURIEncoding(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
        new FormFieldValidator(req, rsp, true) {
            @Override
            protected void check() throws IOException, ServletException {
                request.setCharacterEncoding("UTF-8");
                // expected is non-ASCII String
                final String expected = "\u57f7\u4e8b";
                final String value = fixEmpty(request.getParameter("value"));
                if (!expected.equals(value)) {
                    warningWithMarkup(Messages.Hudson_NotUsesUTF8ToDecodeURL());
                    return;
                }
                ok();
            }
        }.process();
    }

    /**
     * Does not check when system default encoding is "ISO-8859-1".
     */
    public static boolean isCheckURIEncodingEnabled() {
        return !"ISO-8859-1".equalsIgnoreCase(System.getProperty("file.encoding"));
    }

    public static boolean isWindows() {
        return File.pathSeparatorChar==';';
    }

    /**
     * Returns all {@code CVSROOT} strings used in the current Hudson installation.
     *
     * <p>
     * Ideally this shouldn't be defined in here
     * but EL doesn't provide a convenient way of invoking a static function,
     * so I'm putting it here for now.
     */
    public Set<String> getAllCvsRoots() {
        Set<String> r = new TreeSet<String>();
        for( AbstractProject p : getAllItems(AbstractProject.class) ) {
            SCM scm = p.getScm();
            if (scm instanceof CVSSCM) {
                CVSSCM cvsscm = (CVSSCM) scm;
                r.add(cvsscm.getCvsRoot());
            }
        }

        return r;
    }

    /**
     * Rebuilds the dependency map.
     */
    public void rebuildDependencyGraph() {
        dependencyGraph = new DependencyGraph();
    }

    public DependencyGraph getDependencyGraph() {
        return dependencyGraph;
    }

    // for Jelly
    public List<ManagementLink> getManagementLinks() {
        return ManagementLink.LIST;
    }

    /**
     * Gets the {@link Widget}s registered on this object.
     *
     * <p>
     * Plugins who wish to contribute boxes on the side panel can add widgets
     * by {@code getWidgets().add(new MyWidget())} from {@link Plugin#start()}.
     */
    public List<Widget> getWidgets() {
        return widgets;
    }

    public Object getTarget() {
        try {
            checkPermission(READ);
        } catch (AccessDeniedException e) {
            String rest = Stapler.getCurrentRequest().getRestOfPath();
            if(rest.startsWith("/login")
            || rest.startsWith("/logout")
            || rest.startsWith("/accessDenied")
            || rest.startsWith("/signup")
            || rest.startsWith("/jnlpJars/")
            || rest.startsWith("/securityRealm"))
                return this;    // URLs that are always visible without READ permission
            throw e;
        }
        return this;
    }

    public static final class MasterComputer extends Computer {
        private MasterComputer() {
            super(Hudson.getInstance());
        }

        /**
         * Returns "" to match with {@link Hudson#getNodeName()}.
         */
        public String getName() {
            return "";
        }

        @Override
        public String getDisplayName() {
            return Messages.Hudson_Computer_DisplayName();
        }

        @Override
        public String getCaption() {
            return Messages.Hudson_Computer_Caption();
        }

        public String getUrl() {
            return "computer/(master)/";
        }

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

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

        @Override
        public Charset getDefaultCharset() {
            return Charset.defaultCharset();
        }

        public List<LogRecord> getLogRecords() throws IOException, InterruptedException {
            return logRecords;
        }

        public void doLaunchSlaveAgent(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
            // this computer never returns null from channel, so
            // this method shall never be invoked.
            rsp.sendError(SC_NOT_FOUND);
        }

        public void launch() {
            // noop
        }

        /**
         * {@link LocalChannel} instance that can be used to execute programs locally.
         */
        public static final LocalChannel localChannel = new LocalChannel(threadPoolForRemoting);
    }

    /**
     * @deprecated
     *      Use {@link #checkPermission(Permission)}
     */
    public static boolean adminCheck() throws IOException {
        return adminCheck(Stapler.getCurrentRequest(), Stapler.getCurrentResponse());
    }

    /**
     * @deprecated
     *      Use {@link #checkPermission(Permission)}
     */
    public static boolean adminCheck(StaplerRequest req,StaplerResponse rsp) throws IOException {
        if (isAdmin(req)) return true;

        rsp.sendError(StaplerResponse.SC_FORBIDDEN);
        return false;
    }

    /**
     * Checks if the current user (for which we are processing the current request)
     * has the admin access.
     *
     * @deprecated
     *      This method is deprecated when Hudson moved from simple Unix root-like model
     *      of "admin gets to do everything, and others don't have any privilege" to more
     *      complex {@link ACL} and {@link Permission} based scheme.
     *
     *      <p>
     *      For a quick migration, use {@code Hudson.getInstance().getACL().hasPermission(Hudson.ADMINISTER)}
     *      To check if the user has the 'administer' role in Hudson.
     *
     *      <p>
     *      But ideally, your plugin should first identify a suitable {@link Permission} (or create one,
     *      if appropriate), then identify a suitable {@link AccessControlled} object to check its permission
     *      against. 
     */
    public static boolean isAdmin() {
        return Hudson.getInstance().getACL().hasPermission(ADMINISTER);
    }

    /**
     * @deprecated
     *      Define a custom {@link Permission} and check against ACL.
     *      See {@link #isAdmin()} for more instructions.
     */
    public static boolean isAdmin(StaplerRequest req) {
        return isAdmin();
    }

    /**
     * Live view of recent {@link LogRecord}s produced by Hudson.
     */
    public static List<LogRecord> logRecords = Collections.emptyList(); // initialized to dummy value to avoid NPE

    /**
     * Thread-safe reusable {@link XStream}.
     */
    public static final XStream XSTREAM = new XStream2();

    private static final int TWICE_CPU_NUM = Runtime.getRuntime().availableProcessors() * 2;

    /**
     * Thread pool used to load configuration in parallel, to improve the start up time.
     * <p>
     * The idea here is to overlap the CPU and I/O, so we want more threads than CPU numbers.
     */
    /*package*/ static final ExecutorService threadPoolForLoad = new ThreadPoolExecutor(
        TWICE_CPU_NUM, TWICE_CPU_NUM,
        5L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(), new DaemonThreadFactory());



    /**
     * Version number of this Hudson.
     */
    public static String VERSION="?";

    /**
     * Prefix to static resources like images and javascripts in the war file.
     * Either "" or strings like "/static/VERSION", which avoids Hudson to pick up
     * stale cache when the user upgrades to a different version.
     * <p>
     * Value computed in {@link WebAppMain}.
     */
    public static String RESOURCE_PATH = "";

    /**
     * Prefix to resources alongside view scripts.
     * Strings like "/resources/VERSION", which avoids Hudson to pick up
     * stale cache when the user upgrades to a different version.
     * <p>
     * Value computed in {@link WebAppMain}.
     */
    public static String VIEW_RESOURCE_PATH = "/resources/TBD";

    public static boolean PARALLEL_LOAD = Boolean.getBoolean(Hudson.class.getName()+".parallelLoad");
    public static boolean KILL_AFTER_LOAD = Boolean.getBoolean(Hudson.class.getName()+".killAfterLoad");
    public static boolean LOG_STARTUP_PERFORMANCE = Boolean.getBoolean(Hudson.class.getName()+".logStartupPerformance");

    private static final Logger LOGGER = Logger.getLogger(Hudson.class.getName());

    private static final Pattern ICON_SIZE = Pattern.compile("\\d+x\\d+");

    public static final PermissionGroup PERMISSIONS = new PermissionGroup(Hudson.class,Messages._Hudson_Permissions_Title());
    public static final Permission ADMINISTER = new Permission(PERMISSIONS,"Administer",Messages._Hudson_AdministerPermission_Description(), Permission.FULL_CONTROL);
    public static final Permission READ = new Permission(PERMISSIONS,"Read",Messages._Hudson_ReadPermission_Description(),Permission.READ);

    static {
        XSTREAM.alias("hudson",Hudson.class);
        XSTREAM.alias("slave",Slave.class);
        XSTREAM.alias("jdk",JDK.class);
        // for backward compatibility with <1.75, recognize the tag name "view" as well.
        XSTREAM.alias("view", ListView.class);
        XSTREAM.alias("listView", ListView.class);
        // this seems to be necessary to force registration of converter early enough
        Mode.class.getEnumConstants();
    }
}