1 /*

     2  * Copyright 2008-2009 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 

    26 package sun.nio.ch;

    27 

    28 import java.nio.channels.spi.AsynchronousChannelProvider;

    29 import java.nio.channels.*;

    30 import java.io.IOException;

    31 import java.io.Closeable;

    32 import java.io.FileDescriptor;

    33 import java.util.Map;

    34 import java.util.HashMap;

    35 import java.util.concurrent.locks.ReadWriteLock;

    36 import java.util.concurrent.locks.ReentrantReadWriteLock;

    37 

    38 /**

    39  * Base implementation of AsynchronousChannelGroupImpl for Unix systems.

    40  */

    41 

    42 abstract class Port extends AsynchronousChannelGroupImpl {

    43     static final short POLLIN       = 0x0001;

    44     static final short POLLOUT      = 0x0004;

    45     static final short POLLERR      = 0x0008;

    46     static final short POLLHUP      = 0x0010;

    47 

    48     /**

    49      * Implemented by clients registered with this port.

    50      */

    51     interface PollableChannel extends Closeable {

    52         void onEvent(int events);

    53     }

    54 

    55     // maps fd to "pollable" channel

    56     protected final ReadWriteLock fdToChannelLock = new ReentrantReadWriteLock();

    57     protected final Map<Integer,PollableChannel> fdToChannel =

    58         new HashMap<Integer,PollableChannel>();

    59 

    60 

    61     Port(AsynchronousChannelProvider provider, ThreadPool pool) {

    62         super(provider, pool);

    63     }

    64 

    65     /**

    66      * Register channel identified by its file descriptor

    67      */

    68     final void register(int fd, PollableChannel ch) {

    69         fdToChannelLock.writeLock().lock();

    70         try {

    71             if (isShutdown())

    72                 throw new ShutdownChannelGroupException();

    73             fdToChannel.put(Integer.valueOf(fd), ch);

    74         } finally {

    75             fdToChannelLock.writeLock().unlock();

    76         }

    77     }

    78 

    79     /**

    80      * Unregister channel identified by its file descriptor

    81      */

    82     final void unregister(int fd) {

    83         boolean checkForShutdown = false;

    84 

    85         fdToChannelLock.writeLock().lock();

    86         try {

    87             fdToChannel.remove(Integer.valueOf(fd));

    88 

    89             // last key to be removed so check if group is shutdown

    90             if (fdToChannel.isEmpty())

    91                 checkForShutdown = true;

    92 

    93         } finally {

    94             fdToChannelLock.writeLock().unlock();

    95         }

    96 

    97         // continue shutdown

    98         if (checkForShutdown && isShutdown()) {

    99             try {

   100                 shutdownNow();

   101             } catch (IOException ignore) { }

   102         }

   103     }

   104     /**

   105      * Register file descriptor with polling mechanism for given events.

   106      * The implementation should translate the events as required.

   107      */

   108     abstract void startPoll(int fd, int events);

   109 

   110     @Override

   111     final boolean isEmpty() {

   112         fdToChannelLock.writeLock().lock();

   113         try {

   114             return fdToChannel.isEmpty();

   115         } finally {

   116             fdToChannelLock.writeLock().unlock();

   117         }

   118     }

   119 

   120     @Override

   121     final Object attachForeignChannel(final Channel channel, FileDescriptor fd) {

   122         int fdVal = IOUtil.fdVal(fd);

   123         register(fdVal, new PollableChannel() {

   124             public void onEvent(int events) { }

   125             public void close() throws IOException {

   126                 channel.close();

   127             }

   128         });

   129         return Integer.valueOf(fdVal);

   130     }

   131 

   132     @Override

   133     final void detachForeignChannel(Object key) {

   134         unregister((Integer)key);

   135     }

   136 

   137     @Override

   138     final void closeAllChannels() {

   139         /**

   140          * Close channels in batches of up to 128 channels. This allows close

   141          * to remove the channel from the map without interference.

   142          */

   143         final int MAX_BATCH_SIZE = 128;

   144         PollableChannel channels[] = new PollableChannel[MAX_BATCH_SIZE];

   145         int count;

   146         do {

   147             // grab a batch of up to 128 channels

   148             fdToChannelLock.writeLock().lock();

   149             count = 0;

   150             try {

   151                 for (Integer fd: fdToChannel.keySet()) {

   152                     channels[count++] = fdToChannel.get(fd);

   153                     if (count >= MAX_BATCH_SIZE)

   154                         break;

   155                 }

   156             } finally {

   157                 fdToChannelLock.writeLock().unlock();

   158             }

   159 

   160             // close them

   161             for (int i=0; i<count; i++) {

   162                 try {

   163                     channels[i].close();

   164                 } catch (IOException ignore) { }

   165             }

   166         } while (count > 0);

   167     }

   168 }