diff -r dd05c3f2fa24 -r ed84c8bdd87b src/org/sonews/daemon/ChannelLineBuffers.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/sonews/daemon/ChannelLineBuffers.java	Sun Aug 29 17:28:58 2010 +0200
@@ -0,0 +1,283 @@
+/*
+ *   SONEWS News Server
+ *   see AUTHORS for the list of contributors
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.sonews.daemon;
+
+import java.nio.ByteBuffer;
+import java.nio.channels.ClosedChannelException;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Class holding ByteBuffers for SocketChannels/NNTPConnection.
+ * Due to the complex nature of AIO/NIO we must properly handle the line 
+ * buffers for the input and output of the SocketChannels.
+ * @author Christian Lins
+ * @since sonews/0.5.0
+ */
+public class ChannelLineBuffers 
+{
+  
+  /**
+   * Size of one small buffer; 
+   * per default this is 512 bytes to fit one standard line.
+   */
+  public static final int BUFFER_SIZE = 512;
+  
+  private static int maxCachedBuffers = 2048; // Cached buffers maximum
+  
+  private static final List<ByteBuffer> freeSmallBuffers
+    = new ArrayList<ByteBuffer>(maxCachedBuffers);
+  
+  /**
+   * Allocates a predefined number of direct ByteBuffers (allocated via
+   * ByteBuffer.allocateDirect()). This method is Thread-safe, but should only
+   * called at startup.
+   */
+  public static void allocateDirect()
+  {
+    synchronized(freeSmallBuffers)
+    {
+      for(int n = 0; n < maxCachedBuffers; n++)
+      {
+        ByteBuffer buffer = ByteBuffer.allocateDirect(BUFFER_SIZE);
+        freeSmallBuffers.add(buffer);
+      }
+    }
+  }
+  
+  private ByteBuffer       inputBuffer   = newLineBuffer();
+  private List<ByteBuffer> outputBuffers = new ArrayList<ByteBuffer>();
+  
+  /**
+   * Add the given ByteBuffer to the list of buffers to be send to the client.
+   * This method is Thread-safe.
+   * @param buffer
+   * @throws java.nio.channels.ClosedChannelException If the client channel was
+   * already closed.
+   */
+  public void addOutputBuffer(ByteBuffer buffer)
+    throws ClosedChannelException
+  {
+    if(outputBuffers == null)
+    {
+      throw new ClosedChannelException();
+    }
+    
+    synchronized(outputBuffers)
+    {
+      outputBuffers.add(buffer);
+    }
+  }
+  
+  /**
+   * Currently a channel has only one input buffer. This *may* be a bottleneck
+   * and should investigated in the future.
+   * @param channel
+   * @return The input buffer associated with given channel.
+   */
+  public ByteBuffer getInputBuffer()
+  {
+    return inputBuffer;
+  }
+  
+  /**
+   * Returns the current output buffer for writing(!) to SocketChannel.
+   * @param channel
+   * @return The next input buffer that contains unprocessed data or null
+   * if the connection was closed or there are no more unprocessed buffers.
+   */
+  public ByteBuffer getOutputBuffer()
+  {
+    synchronized(outputBuffers)
+    {
+      if(outputBuffers == null || outputBuffers.isEmpty())
+      {
+        return null;
+      }
+      else
+      {
+        ByteBuffer buffer = outputBuffers.get(0);
+        if(buffer.remaining() == 0)
+        {
+          outputBuffers.remove(0);
+          // Add old buffers to the list of free buffers
+          recycleBuffer(buffer);
+          buffer = getOutputBuffer();
+        }
+        return buffer;
+      }
+    }
+  }
+
+  /**
+   * @return false if there are output buffers pending to be written to the
+   * client.
+   */
+  boolean isOutputBufferEmpty()
+  {
+    synchronized(outputBuffers)
+    {
+      return outputBuffers.isEmpty();
+    }
+  }
+  
+  /**
+   * Goes through the input buffer of the given channel and searches
+   * for next line terminator. If a '\n' is found, the bytes up to the
+   * line terminator are returned as array of bytes (the line terminator
+   * is omitted). If none is found the method returns null.
+   * @param channel
+   * @return A ByteBuffer wrapping the line.
+   */
+  ByteBuffer nextInputLine()
+  {
+    if(inputBuffer == null)
+    {
+      return null;
+    }
+    
+    synchronized(inputBuffer)
+    {
+      ByteBuffer buffer = inputBuffer;
+
+      // Mark the current write position
+      int mark = buffer.position();
+
+      // Set position to 0 and limit to current position
+      buffer.flip();
+
+      ByteBuffer lineBuffer = newLineBuffer();
+
+      while (buffer.position() < buffer.limit())
+      {
+        byte b = buffer.get();
+        if (b == 10) // '\n'
+        {
+          // The bytes between the buffer's current position and its limit, 
+          // if any, are copied to the beginning of the buffer. That is, the 
+          // byte at index p = position() is copied to index zero, the byte at 
+          // index p + 1 is copied to index one, and so forth until the byte 
+          // at index limit() - 1 is copied to index n = limit() - 1 - p. 
+          // The buffer's position is then set to n+1 and its limit is set to 
+          // its capacity.
+          buffer.compact();
+
+          lineBuffer.flip(); // limit to position, position to 0
+          return lineBuffer;
+        }
+        else
+        {
+          lineBuffer.put(b);
+        }
+      }
+
+      buffer.limit(BUFFER_SIZE);
+      buffer.position(mark);
+
+      if(buffer.hasRemaining())
+      {
+        return null;
+      }
+      else
+      {
+        // In the first 512 was no newline found, so the input is not standard
+        // compliant. We return the current buffer as new line and add a space
+        // to the beginning of the next line which corrects some overlong header
+        // lines.
+        inputBuffer = newLineBuffer();
+        inputBuffer.put((byte)' ');
+        buffer.flip();
+        return buffer;
+      }
+    }
+  }
+  
+  /**
+   * Returns a at least 512 bytes long ByteBuffer ready for usage.
+   * The method first try to reuse an already allocated (cached) buffer but
+   * if that fails returns a newly allocated direct buffer.
+   * Use recycleBuffer() method when you do not longer use the allocated buffer.
+   */
+  static ByteBuffer newLineBuffer()
+  {
+    ByteBuffer buf = null;
+    synchronized(freeSmallBuffers)
+    {
+      if(!freeSmallBuffers.isEmpty())
+      {
+        buf = freeSmallBuffers.remove(0);
+      }
+    }
+      
+    if(buf == null)
+    {
+      // Allocate a non-direct buffer
+      buf = ByteBuffer.allocate(BUFFER_SIZE);
+    }
+    
+    assert buf.position() == 0;
+    assert buf.limit() >= BUFFER_SIZE;
+    
+    return buf;
+  }
+  
+  /**
+   * Adds the given buffer to the list of free buffers if it is a valuable
+   * direct allocated buffer.
+   * @param buffer
+   */
+  public static void recycleBuffer(ByteBuffer buffer)
+  {
+    assert buffer != null;
+
+    if(buffer.isDirect())
+    {
+      assert buffer.capacity() >= BUFFER_SIZE;
+      
+      // Add old buffers to the list of free buffers
+      synchronized(freeSmallBuffers)
+      {
+        buffer.clear(); // Set position to 0 and limit to capacity
+        freeSmallBuffers.add(buffer);
+      }
+    } // if(buffer.isDirect())
+  }
+  
+  /**
+   * Recycles all buffers of this ChannelLineBuffers object.
+   */
+  public void recycleBuffers()
+  {
+    synchronized(inputBuffer)
+    {
+      recycleBuffer(inputBuffer);
+      this.inputBuffer = null;
+    }
+    
+    synchronized(outputBuffers)
+    {
+      for(ByteBuffer buf : outputBuffers)
+      {
+        recycleBuffer(buf);
+      }
+      outputBuffers = null;
+    }
+  }
+  
+}