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[pf3gnuchains/gcc-fork.git] / libjava / classpath / java / nio / channels / spi / AbstractSelector.java

diff --git a/libjava/classpath/java/nio/channels/spi/AbstractSelector.java b/libjava/classpath/java/nio/channels/spi/AbstractSelector.java
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+/* AbstractSelector.java --
+   Copyright (C) 2002, 2003, 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
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+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
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package java.nio.channels.spi;
+
+import java.io.IOException;
+import java.nio.channels.ClosedSelectorException;
+import java.nio.channels.SelectionKey;
+import java.nio.channels.Selector;
+import java.util.HashSet;
+import java.util.Set;
+
+
+public abstract class AbstractSelector extends Selector
+{
+  private boolean closed;
+  private SelectorProvider provider;
+  private HashSet cancelledKeys;
+
+  /**
+   * Initializes the slector.
+   *
+   * @param provider the provider that created this selector
+   */
+  protected AbstractSelector(SelectorProvider provider)
+  {
+    this.provider = provider;
+    this.cancelledKeys = new HashSet();
+  }
+
+  /**
+   * Closes the channel.
+   *
+   * @exception IOException If an error occurs
+   */
+  public final synchronized void close() throws IOException
+  {
+    if (closed)
+      return;
+
+    implCloseSelector();
+    closed = true;
+  }
+
+  /**
+   * Tells whether this channel is open or not.
+   *
+   * @return true if channel is open, false otherwise.
+   */
+  public final boolean isOpen()
+  {
+    return ! closed;
+  }
+
+  /**
+   * Marks the beginning of an I/O operation that might block indefinitely.
+   */
+  protected final void begin()
+  {
+  }
+
+  /**
+   * Marks the end of an I/O operation that might block indefinitely.
+   */
+  protected final void end()
+  {
+  }
+
+  /**
+   * Returns the provider for this selector object.
+   *
+   * @return the SelectorProvider object that created this seletor
+   */
+  public final SelectorProvider provider()
+  {
+    return provider;
+  }
+
+  /**
+   * Returns the cancelled keys set.
+   *
+   * @return the cancelled keys set
+   */
+  protected final Set cancelledKeys()
+  {
+    if (! isOpen())
+      throw new ClosedSelectorException();
+
+    return cancelledKeys;
+  }
+
+  /**
+   * Cancels a selection key.
+   */
+
+  // This method is only called by AbstractSelectionKey.cancel().
+  final void cancelKey(AbstractSelectionKey key)
+  {
+    synchronized (cancelledKeys)
+      {
+       cancelledKeys.add(key);
+      }
+  }
+
+  /**
+   * Closes the channel.
+   *
+   * @exception IOException if an error occurs
+   */
+  protected abstract void implCloseSelector() throws IOException;
+
+  /**
+   * Registers a channel for the selection process.
+   *
+   * @param ch the channel register
+   * @param ops the interested operations
+   * @param att an attachement to the selection key
+   *
+   * @return the registered selection key
+   */
+  protected abstract SelectionKey register(AbstractSelectableChannel ch,
+                                           int ops, Object att);
+
+  /**
+   * Deregisters the given selection key.
+   *
+   * @param key the key to deregister
+   */
+  protected final void deregister(AbstractSelectionKey key)
+  {
+    ((AbstractSelectableChannel) key.channel()).removeSelectionKey(key);
+  }
+}