libjava/java/nio/channels/spi/AbstractSelector.java

   1 /* AbstractSelector.java --
   2    Copyright (C) 2002, 2003 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.nio.channels.spi;
  40
  41 import java.io.IOException;
  42 import java.nio.channels.ClosedSelectorException;
  43 import java.nio.channels.SelectionKey;
  44 import java.nio.channels.Selector;
  45 import java.util.Set;
  46 import java.util.HashSet;
  47
  48 public abstract class AbstractSelector extends Selector
  49 {
  50   private boolean closed = false;
  51   private SelectorProvider provider;
  52   private HashSet cancelledKeys;
  53
  54   /**
  55    * Initializes the slector.
  56    */
  57   protected AbstractSelector (SelectorProvider provider)
  58   {
  59     this.provider = provider;
  60     this.cancelledKeys = new HashSet();
  61   }
  62
  63   /**
  64    * Closes the channel.
  65    *
  66    * @exception IOException If an error occurs
  67    */
  68   public final synchronized void close () throws IOException
  69   {
  70     if (closed)
  71       return;
  72
  73     implCloseSelector();
  74     closed = true;
  75   }
  76
  77   /**
  78    * Tells whether this channel is open or not.
  79    */
  80   public final boolean isOpen ()
  81   {
  82     return ! closed;
  83   }
  84
  85   /**
  86    * Marks the beginning of an I/O operation that might block indefinitely.
  87    */
  88   protected final void begin()
  89   {
  90   }
  91
  92   /**
  93    * Marks the end of an I/O operation that might block indefinitely.
  94    */
  95   protected final void end()
  96   {
  97   }
  98
  99   public final SelectorProvider provider ()
 100   {
 101     return provider;
 102   }
 103
 104   protected final Set cancelledKeys()
 105   {
 106     if (!isOpen())
 107       throw new ClosedSelectorException();
 108
 109     return cancelledKeys;
 110   }
 111
 112   final void cancelKey (AbstractSelectionKey key)
 113   {
 114     synchronized (cancelledKeys)
 115       {
 116         cancelledKeys.remove(key);
 117       }
 118   }
 119
 120   /**
 121    * Closes the channel.
 122    */
 123   protected abstract void implCloseSelector () throws IOException;
 124
 125   protected abstract SelectionKey register (AbstractSelectableChannel ch,
 126                                             int ops, Object att);
 127
 128   protected final void deregister (AbstractSelectionKey key)
 129   {
 130     // FIXME
 131   }
 132 }