/* AbstractInterruptibleChannel.java -- 
   Copyright (C) 2002, 2004 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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General Public License for more details.

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02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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permission to link this library with independent modules to produce an
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package java.nio.channels.spi;

import java.io.IOException;
import java.nio.channels.AsynchronousCloseException;
import java.nio.channels.Channel;
import java.nio.channels.ClosedByInterruptException;
import java.nio.channels.InterruptibleChannel;


/**
 * @author Michael Koch
 * @since 1.4
 */
public abstract class AbstractInterruptibleChannel
  implements Channel, InterruptibleChannel
{
  private boolean closed;

  /**
   * Initializes the channel.
   */
  protected AbstractInterruptibleChannel()
  {
  }

  /**
   * Marks the beginning of an I/O operation that might block indefinitely.
   */
  protected final void begin()
  {
  }
    
  /**
   * Closes the channel.
   * 
   * @exception IOException If an error occurs
   */
  public final void close() throws IOException
  {
    if (! closed)
  {
	closed = true;
	implCloseChannel();
      }
  }

  /**
   * Marks the end of an I/O operation that might block indefinitely.
   * 
   * @param completed true if the task completed successfully,
   * false otherwise
   *
   * @exception AsynchronousCloseException If the channel was asynchronously
   * closed.
   * @exception ClosedByInterruptException If the thread blocked in the
   * I/O operation was interrupted.
   */
  protected final void end(boolean completed)
    throws AsynchronousCloseException
  {
    // FIXME: check more here.
    
    if (closed) throw new AsynchronousCloseException();
  }   

  /**
   * Closes the channel.
   * 
   * @exception IOException If an error occurs
   */
  protected abstract void implCloseChannel() throws IOException;

  /**
   * Tells whether or not this channel is open.
   * 
   * @return true if the channel is open, false otherwise 
   */
  public final boolean isOpen()
  {
    return ! closed;
  }
}