001/* AbstractSelector.java -- 002 Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038package java.nio.channels.spi; 039 040import java.io.IOException; 041import java.nio.channels.ClosedSelectorException; 042import java.nio.channels.SelectionKey; 043import java.nio.channels.Selector; 044import java.util.HashSet; 045import java.util.Set; 046 047 048public abstract class AbstractSelector extends Selector 049{ 050 private boolean closed; 051 private SelectorProvider provider; 052 private HashSet<SelectionKey> cancelledKeys; 053 054 /** 055 * Initializes the slector. 056 * 057 * @param provider the provider that created this selector 058 */ 059 protected AbstractSelector(SelectorProvider provider) 060 { 061 this.provider = provider; 062 this.cancelledKeys = new HashSet<SelectionKey>(); 063 } 064 065 /** 066 * Closes the channel. 067 * 068 * @exception IOException If an error occurs 069 */ 070 public final synchronized void close() throws IOException 071 { 072 if (closed) 073 return; 074 075 implCloseSelector(); 076 closed = true; 077 } 078 079 /** 080 * Tells whether this channel is open or not. 081 * 082 * @return true if channel is open, false otherwise. 083 */ 084 public final boolean isOpen() 085 { 086 return ! closed; 087 } 088 089 /** 090 * Marks the beginning of an I/O operation that might block indefinitely. 091 */ 092 protected final void begin() 093 { 094 } 095 096 /** 097 * Marks the end of an I/O operation that might block indefinitely. 098 */ 099 protected final void end() 100 { 101 } 102 103 /** 104 * Returns the provider for this selector object. 105 * 106 * @return the SelectorProvider object that created this seletor 107 */ 108 public final SelectorProvider provider() 109 { 110 return provider; 111 } 112 113 /** 114 * Returns the cancelled keys set. 115 * 116 * @return the cancelled keys set 117 */ 118 protected final Set<SelectionKey> cancelledKeys() 119 { 120 if (! isOpen()) 121 throw new ClosedSelectorException(); 122 123 return cancelledKeys; 124 } 125 126 /** 127 * Cancels a selection key. 128 */ 129 130 // This method is only called by AbstractSelectionKey.cancel(). 131 final void cancelKey(AbstractSelectionKey key) 132 { 133 synchronized (cancelledKeys) 134 { 135 cancelledKeys.add(key); 136 } 137 } 138 139 /** 140 * Closes the channel. 141 * 142 * @exception IOException if an error occurs 143 */ 144 protected abstract void implCloseSelector() throws IOException; 145 146 /** 147 * Registers a channel for the selection process. 148 * 149 * @param ch the channel register 150 * @param ops the interested operations 151 * @param att an attachement to the selection key 152 * 153 * @return the registered selection key 154 */ 155 protected abstract SelectionKey register(AbstractSelectableChannel ch, 156 int ops, Object att); 157 158 /** 159 * Deregisters the given selection key. 160 * 161 * @param key the key to deregister 162 */ 163 protected final void deregister(AbstractSelectionKey key) 164 { 165 ((AbstractSelectableChannel) key.channel()).removeSelectionKey(key); 166 } 167}