001    /*
002     * Copyright (C) 2010 eXo Platform SAS.
003     *
004     * This is free software; you can redistribute it and/or modify it
005     * under the terms of the GNU Lesser General Public License as
006     * published by the Free Software Foundation; either version 2.1 of
007     * the License, or (at your option) any later version.
008     *
009     * This software is distributed in the hope that it will be useful,
010     * but WITHOUT ANY WARRANTY; without even the implied warranty of
011     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012     * Lesser General Public License for more details.
013     *
014     * You should have received a copy of the GNU Lesser General Public
015     * License along with this software; if not, write to the Free
016     * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
017     * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
018     */
019    
020    package org.crsh.shell.impl.async;
021    
022    import org.crsh.cmdline.CommandCompletion;
023    import org.crsh.shell.Shell;
024    
025    import java.io.Closeable;
026    import java.util.Collections;
027    import java.util.HashSet;
028    import java.util.Set;
029    import java.util.concurrent.CompletionService;
030    import java.util.concurrent.Executor;
031    import java.util.concurrent.ExecutorCompletionService;
032    
033    /**
034     * <p>The async shell wraps a shell and provides command cancellation. The shell executes the command in a separate thread
035     * allowing using the wrapped shell to which it delegates the business command execution. This implementation allows the
036     * execution of several process in parallel</p>
037     *
038     * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
039     * @version $Revision$
040     */
041    public class AsyncShell implements Shell, Closeable {
042    
043      /** . */
044      final Shell shell;
045    
046      /** . */
047      private AsyncProcess current;
048    
049      /** . */
050      final CompletionService<AsyncProcess> executor;
051    
052      /** . */
053      boolean closed;
054    
055      /** . */
056      final Object lock = new Object();
057    
058      /** . */
059      final Set<AsyncProcess> processes;
060    
061      public AsyncShell(Executor executor, Shell shell) {
062        this.shell = shell;
063        this.current = null;
064        this.executor = new ExecutorCompletionService<AsyncProcess>(executor);
065        this.closed = false;
066        this.processes = Collections.synchronizedSet(new HashSet<AsyncProcess>());
067      }
068    
069      public void close() {
070    
071        AsyncProcess[] toCancel = null;
072        synchronized (lock) {
073          if (closed) {
074            toCancel = null;
075          } else {
076            closed = true;
077            toCancel = processes.toArray(new AsyncProcess[processes.size()]);
078          }
079        }
080    
081        // Cancel all process
082        if (toCancel != null) {
083          for (AsyncProcess process : toCancel) {
084            process.cancel();
085          }
086        }
087      }
088    
089      // Shell implementation **********************************************************************************************
090    
091      public String getWelcome() {
092        return shell.getWelcome();
093      }
094    
095      public String getPrompt() {
096        return shell.getPrompt();
097      }
098    
099      public CommandCompletion complete(String prefix) {
100        return shell.complete(prefix);
101      }
102    
103      public AsyncProcess createProcess(String request) {
104        synchronized (lock) {
105          if (closed) {
106            throw new IllegalStateException();
107          }
108        }
109        return new AsyncProcess(this, request);
110      }
111    }