org/sonews/daemon/NNTPConnection.java
author cli
Fri, 25 Dec 2009 15:42:46 +0100
changeset 25 dd05c3f2fa24
parent 15 f2293e8566f5
child 30 146b3275b792
permissions -rw-r--r--
Fix for too early disconnects on slow client connections. (#563)
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/*
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 *   SONEWS News Server
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 *   see AUTHORS for the list of contributors
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 *
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 *   This program is free software: you can redistribute it and/or modify
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 *   it under the terms of the GNU General Public License as published by
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 *   the Free Software Foundation, either version 3 of the License, or
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 *   (at your option) any later version.
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 *
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 *   This program is distributed in the hope that it will be useful,
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 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
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 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 *   GNU General Public License for more details.
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 *
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 *   You should have received a copy of the GNU General Public License
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 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
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 */
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package org.sonews.daemon;
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import java.io.IOException;
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import java.net.InetSocketAddress;
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import java.net.SocketException;
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import java.nio.ByteBuffer;
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import java.nio.CharBuffer;
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import java.nio.channels.ClosedChannelException;
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import java.nio.channels.SelectionKey;
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import java.nio.channels.SocketChannel;
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import java.nio.charset.Charset;
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import java.util.Arrays;
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import java.util.Timer;
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import java.util.TimerTask;
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import org.sonews.daemon.command.Command;
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import org.sonews.storage.Article;
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import org.sonews.storage.Channel;
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import org.sonews.util.Log;
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import org.sonews.util.Stats;
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/**
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 * For every SocketChannel (so TCP/IP connection) there is an instance of
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 * this class.
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 * @author Christian Lins
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 * @since sonews/0.5.0
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 */
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public final class NNTPConnection
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{
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  public static final String NEWLINE            = "\r\n";    // RFC defines this as newline
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  public static final String MESSAGE_ID_PATTERN = "<[^>]+>";
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  private static final Timer cancelTimer = new Timer(true); // Thread-safe? True for run as daemon
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  /** SocketChannel is generally thread-safe */
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  private SocketChannel   channel        = null;
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  private Charset         charset        = Charset.forName("UTF-8");
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  private Command         command        = null;
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  private Article         currentArticle = null;
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  private Channel         currentGroup   = null;
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  private volatile long   lastActivity   = System.currentTimeMillis();
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  private ChannelLineBuffers lineBuffers = new ChannelLineBuffers();
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  private int             readLock       = 0;
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  private final Object    readLockGate   = new Object();
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  private SelectionKey    writeSelKey    = null;
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  public NNTPConnection(final SocketChannel channel)
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    throws IOException
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  {
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    if(channel == null)
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    {
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      throw new IllegalArgumentException("channel is null");
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    }
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    this.channel = channel;
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    Stats.getInstance().clientConnect();
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  }
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  /**
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   * Tries to get the read lock for this NNTPConnection. This method is Thread-
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   * safe and returns true of the read lock was successfully set. If the lock
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   * is still hold by another Thread the method returns false.
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   */
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  boolean tryReadLock()
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  {
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    // As synchronizing simple types may cause deadlocks,
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    // we use a gate object.
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    synchronized(readLockGate)
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    {
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      if(readLock != 0)
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      {
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        return false;
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      }
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      else
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      {
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        readLock = Thread.currentThread().hashCode();
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        return true;
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      }
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    }
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  }
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  /**
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   * Releases the read lock in a Thread-safe way.
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   * @throws IllegalMonitorStateException if a Thread not holding the lock
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   * tries to release it.
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   */
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  void unlockReadLock()
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  {
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    synchronized(readLockGate)
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    {
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      if(readLock == Thread.currentThread().hashCode())
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      {
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        readLock = 0;
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      }
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      else
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      {
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        throw new IllegalMonitorStateException();
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      }
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    }
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  }
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  /**
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   * @return Current input buffer of this NNTPConnection instance.
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   */
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  public ByteBuffer getInputBuffer()
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  {
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    return this.lineBuffers.getInputBuffer();
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  }
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  /**
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   * @return Output buffer of this NNTPConnection which has at least one byte
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   * free storage.
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   */
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  public ByteBuffer getOutputBuffer()
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  {
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    return this.lineBuffers.getOutputBuffer();
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  }
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  /**
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   * @return ChannelLineBuffers instance associated with this NNTPConnection.
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   */
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  public ChannelLineBuffers getBuffers()
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  {
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    return this.lineBuffers;
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  }
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  /**
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   * @return true if this connection comes from a local remote address.
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   */
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  public boolean isLocalConnection()
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  {
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    return ((InetSocketAddress)this.channel.socket().getRemoteSocketAddress())
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      .getHostName().equalsIgnoreCase("localhost");
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  }
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  void setWriteSelectionKey(SelectionKey selKey)
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  {
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    this.writeSelKey = selKey;
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  }
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  public void shutdownInput()
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  {
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    try
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    {
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      // Closes the input line of the channel's socket, so no new data
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      // will be received and a timeout can be triggered.
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      this.channel.socket().shutdownInput();
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    }
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    catch(IOException ex)
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    {
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      Log.get().warning("Exception in NNTPConnection.shutdownInput(): " + ex);
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    }
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  }
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  public void shutdownOutput()
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  {
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    cancelTimer.schedule(new TimerTask() 
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    {
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      @Override
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      public void run()
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      {
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        try
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        {
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          // Closes the output line of the channel's socket.
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          channel.socket().shutdownOutput();
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          channel.close();
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        }
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        catch(SocketException ex)
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        {
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          // Socket was already disconnected
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          Log.get().info("NNTPConnection.shutdownOutput(): " + ex);
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        }
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        catch(Exception ex)
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        {
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          Log.get().warning("NNTPConnection.shutdownOutput(): " + ex);
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        }
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      }
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    }, 3000);
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  }
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  public SocketChannel getSocketChannel()
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  {
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    return this.channel;
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  }
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  public Article getCurrentArticle()
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  {
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    return this.currentArticle;
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  }
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  public Charset getCurrentCharset()
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  {
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    return this.charset;
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  }
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  /**
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   * @return The currently selected communication channel (not SocketChannel)
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   */
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  public Channel getCurrentChannel()
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  {
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    return this.currentGroup;
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  }
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  public void setCurrentArticle(final Article article)
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  {
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    this.currentArticle = article;
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  }
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  public void setCurrentGroup(final Channel group)
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  {
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    this.currentGroup = group;
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  }
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  public long getLastActivity()
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  {
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    return this.lastActivity;
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  }
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  /**
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   * Due to the readLockGate there is no need to synchronize this method.
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   * @param raw
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   * @throws IllegalArgumentException if raw is null.
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   * @throws IllegalStateException if calling thread does not own the readLock.
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   */
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  void lineReceived(byte[] raw)
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  {
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    if(raw == null)
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    {
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      throw new IllegalArgumentException("raw is null");
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    }
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    if(readLock == 0 || readLock != Thread.currentThread().hashCode())
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    {
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      throw new IllegalStateException("readLock not properly set");
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    }
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    this.lastActivity = System.currentTimeMillis();
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    String line = new String(raw, this.charset);
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    // There might be a trailing \r, but trim() is a bad idea
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    // as it removes also leading spaces from long header lines.
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    if(line.endsWith("\r"))
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    {
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      line = line.substring(0, line.length() - 1);
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      raw  = Arrays.copyOf(raw, raw.length - 1);
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    }
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    Log.get().fine("<< " + line);
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    if(command == null)
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    {
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      command = parseCommandLine(line);
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      assert command != null;
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    }
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    try
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    {
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      // The command object will process the line we just received
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      command.processLine(this, line, raw);
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    }
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    catch(ClosedChannelException ex0)
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    {
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      try
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      {
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        Log.get().info("Connection to " + channel.socket().getRemoteSocketAddress()
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            + " closed: " + ex0);
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      }
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      catch(Exception ex0a)
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      {
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        ex0a.printStackTrace();
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      }
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    }
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    catch(Exception ex1)
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    {
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      try
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      {
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        command = null;
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        ex1.printStackTrace();
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        println("500 Internal server error");
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      }
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      catch(Exception ex2)
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      {
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        ex2.printStackTrace();
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      }
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    }
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    if(command == null || command.hasFinished())
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    {
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      command = null;
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      charset = Charset.forName("UTF-8"); // Reset to default
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    }
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  }
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  /**
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   * This method determines the fitting command processing class.
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   * @param line
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   * @return
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   */
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  private Command parseCommandLine(String line)
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  {
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    String cmdStr = line.split(" ")[0];
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    return CommandSelector.getInstance().get(cmdStr);
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  }
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  /**
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   * Puts the given line into the output buffer, adds a newline character
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   * and returns. The method returns immediately and does not block until
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   * the line was sent. If line is longer than 510 octets it is split up in
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   * several lines. Each line is terminated by \r\n (NNTPConnection.NEWLINE).
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   * @param line
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   */
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  public void println(final CharSequence line, final Charset charset)
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    throws IOException
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  {    
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    writeToChannel(CharBuffer.wrap(line), charset, line);
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    writeToChannel(CharBuffer.wrap(NEWLINE), charset, null);
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  }
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  /**
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   * Writes the given raw lines to the output buffers and finishes with
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   * a newline character (\r\n).
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   * @param rawLines
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   */
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  public void println(final byte[] rawLines)
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    throws IOException
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  {
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    this.lineBuffers.addOutputBuffer(ByteBuffer.wrap(rawLines));
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    writeToChannel(CharBuffer.wrap(NEWLINE), charset, null);
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  }
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  /**
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   * Encodes the given CharBuffer using the given Charset to a bunch of
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   * ByteBuffers (each 512 bytes large) and enqueues them for writing at the
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   * connected SocketChannel.
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   * @throws java.io.IOException
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   */
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  private void writeToChannel(CharBuffer characters, final Charset charset,
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    CharSequence debugLine)
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    throws IOException
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  {
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    if(!charset.canEncode())
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    {
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      Log.get().severe("FATAL: Charset " + charset + " cannot encode!");
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      return;
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    }
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    // Write characters to output buffers
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    LineEncoder lenc = new LineEncoder(characters, charset);
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    lenc.encode(lineBuffers);
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    enableWriteEvents(debugLine);
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  }
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  private void enableWriteEvents(CharSequence debugLine)
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  {
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    // Enable OP_WRITE events so that the buffers are processed
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    try
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    {
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      this.writeSelKey.interestOps(SelectionKey.OP_WRITE);
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      ChannelWriter.getInstance().getSelector().wakeup();
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    }
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    catch(Exception ex) // CancelledKeyException and ChannelCloseException
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    {
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      Log.get().warning("NNTPConnection.writeToChannel(): " + ex);
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      return;
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    }
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    // Update last activity timestamp
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    this.lastActivity = System.currentTimeMillis();
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    if(debugLine != null)
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    {
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      Log.get().fine(">> " + debugLine);
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    }
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  }
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  public void println(final CharSequence line)
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    throws IOException
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  {
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    println(line, charset);
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  }
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  public void print(final String line)
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    throws IOException
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  {
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    writeToChannel(CharBuffer.wrap(line), charset, line);
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  }
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  public void setCurrentCharset(final Charset charset)
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  {
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    this.charset = charset;
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  }
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  void setLastActivity(long timestamp)
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  {
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    this.lastActivity = timestamp;
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  }
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}