nioprocessor.java

mina是以Java实现的一个开源的网络程序框架

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 *
 */
package org.apache.mina.transport.socket.nio;

import java.io.IOException;
import java.nio.channels.ByteChannel;
import java.nio.channels.SelectableChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.Executor;

import org.apache.mina.core.RuntimeIoException;
import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.file.FileRegion;
import org.apache.mina.core.polling.AbstractPollingIoProcessor;

/**
 * TODO Add documentation
 * 
 * @author The Apache MINA Project ([e-mail])
 * @version $Rev: 751744 $, $Date: 2009-03-09 17:53:13 +0100 (Mon, 09 Mar 2009) $
 */
public final class NioProcessor extends AbstractPollingIoProcessor<NioSession> {
    /** The selector associated with this processor */
    private final Selector selector;

    /**
     * 
     * Creates a new instance of NioProcessor.
     *
     * @param executor
     */
    public NioProcessor(Executor executor) {
        super(executor);
        try {
            // Open a new selector
            selector = Selector.open();
        } catch (IOException e) {
            throw new RuntimeIoException("Failed to open a selector.", e);
        }
    }

    @Override
    protected void dispose0() throws Exception {
        selector.close();
    }

    @Override
    protected int select(long timeout) throws Exception {
        return selector.select(timeout);
    }

    @Override
    protected int select() throws Exception {
        return selector.select();
    }

    @Override
    protected boolean isSelectorEmpty() {
        return selector.keys().isEmpty();
    }

    @Override
    protected void wakeup() {
        selector.wakeup();
    }

    @Override
    protected Iterator<NioSession> allSessions() {
        return new IoSessionIterator(selector.keys());
    }

    @Override
    protected Iterator<NioSession> selectedSessions() {
        return new IoSessionIterator(selector.selectedKeys());
    }

    @Override
    protected void init(NioSession session) throws Exception {
        SelectableChannel ch = (SelectableChannel) session.getChannel();
        ch.configureBlocking(false);
        session.setSelectionKey(ch.register(selector, SelectionKey.OP_READ, session));
    }

    @Override
    protected void destroy(NioSession session) throws Exception {
        ByteChannel ch = session.getChannel();
        SelectionKey key = session.getSelectionKey();
        if (key != null) {
            key.cancel();
        }
        ch.close();
    }

    @Override
    protected SessionState state(NioSession session) {
        SelectionKey key = session.getSelectionKey();
        if (key == null) {
            return SessionState.PREPARING;
        }

        return key.isValid()? SessionState.OPEN : SessionState.CLOSED;
    }

    @Override
    protected boolean isReadable(NioSession session) {
        SelectionKey key = session.getSelectionKey();
        return key.isValid() && key.isReadable();
    }

    @Override
    protected boolean isWritable(NioSession session) {
        SelectionKey key = session.getSelectionKey();
        return key.isValid() && key.isWritable();
    }

    @Override
    protected boolean isInterestedInRead(NioSession session) {
        SelectionKey key = session.getSelectionKey();
        return key.isValid() && (key.interestOps() & SelectionKey.OP_READ) != 0;
    }

    @Override
    protected boolean isInterestedInWrite(NioSession session) {
        SelectionKey key = session.getSelectionKey();
        return key.isValid() && (key.interestOps() & SelectionKey.OP_WRITE) != 0;
    }

    @Override
    protected void setInterestedInRead(NioSession session, boolean value) throws Exception {
        SelectionKey key = session.getSelectionKey();
        int oldInterestOps = key.interestOps();
        int newInterestOps;
        if (value) {
            newInterestOps = oldInterestOps | SelectionKey.OP_READ;
        } else {
            newInterestOps = oldInterestOps & ~SelectionKey.OP_READ;
        }
        if (oldInterestOps != newInterestOps) {
            key.interestOps(newInterestOps);
        }
    }

    @Override
    protected void setInterestedInWrite(NioSession session, boolean value) throws Exception {
        SelectionKey key = session.getSelectionKey();
        int oldInterestOps = key.interestOps();
        int newInterestOps;
        if (value) {
            newInterestOps = oldInterestOps | SelectionKey.OP_WRITE;
        } else {
            newInterestOps = oldInterestOps & ~SelectionKey.OP_WRITE;
        }
        if (oldInterestOps != newInterestOps) {
            key.interestOps(newInterestOps);
        }
    }

    @Override
    protected int read(NioSession session, IoBuffer buf) throws Exception {
        return session.getChannel().read(buf.buf());
    }

    @Override
    protected int write(NioSession session, IoBuffer buf, int length) throws Exception {
        if (buf.remaining() <= length) {
            return session.getChannel().write(buf.buf());
        } else {
            int oldLimit = buf.limit();
            buf.limit(buf.position() + length);
            try {
                return session.getChannel().write(buf.buf());
            } finally {
                buf.limit(oldLimit);
            }
        }
    }

    @Override
    protected int transferFile(NioSession session, FileRegion region, int length) throws Exception {
        try {
            return (int) region.getFileChannel().transferTo(region.getPosition(), length, session.getChannel());
        } catch (IOException e) {
            // Check to see if the IOException is being thrown due to
            // http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5103988
            String message = e.getMessage();
            if (message != null && message.contains("temporarily unavailable")) {
                return 0;
            } else {
                throw e;
            }
        }
    }

    /**
     * An encapsulating iterator around the  {@link Selector#selectedKeys()} 
     * or the {@link Selector#keys()} iterator;
     */
    protected static class IoSessionIterator implements Iterator<NioSession> {
        private final Iterator<SelectionKey> iterator;
        
        /**
         * Create this iterator as a wrapper on top of the selectionKey
         * Set.
         * @param keys
         */
        private IoSessionIterator(Set<SelectionKey> keys) {
        	iterator = keys.iterator();
        }
        
        /**
         * {@inheritDoc}
         */
        public boolean hasNext() {
            return iterator.hasNext();
        }

        /**
         * {@inheritDoc}
         */
        public NioSession next() {
            SelectionKey key = iterator.next();
            NioSession nioSession =  (NioSession) key.attachment();
            return nioSession;
        }

        /**
         * {@inheritDoc}
         */
        public void remove() {
        	iterator.remove();
        }
    }
}