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/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project 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.jboss.netty.channel;

import java.io.IOException;
import java.nio.channels.FileChannel;
import java.nio.channels.WritableByteChannel;

import org.jboss.netty.util.ExternalResourceReleasable;

/**
 * A region of a file that is sent via a {@link Channel} which supports
 * zero-copy file transfer.
 *
 * 

Upgrade your JDK / JRE

* * {@link FileChannel#transferTo(long, long, WritableByteChannel)} has at least * four known bugs in the old versions of Sun JDK and perhaps its derived ones. * Please upgrade your JDK to 1.6.0_18 or later version if you are going to use * zero-copy file transfer. *
    *
  • 5103988 * - FileChannel.transferTo() should return -1 for EAGAIN instead throws IOException
  • *
  • 6253145 * - FileChannel.transferTo() on Linux fails when going beyond 2GB boundary
  • *
  • 6427312 * - FileChannel.transferTo() throws IOException "system call interrupted"
  • *
  • 6470086 * - FileChannel.transferTo(2147483647, 1, channel) causes "Value too large" exception
  • *
* *

Check your operating system and JDK / JRE

* * If your operating system (or JDK / JRE) does not support zero-copy file * transfer, sending a file with {@link FileRegion} might fail or yield worse * performance. For example, sending a large file doesn't work well in Windows. * *

Not all transports support it

* * Currently, the NIO transport is the only transport that supports {@link FileRegion}. * Attempting to write a {@link FileRegion} to non-NIO {@link Channel} will trigger * a {@link ClassCastException} or a similar exception. */ public interface FileRegion extends ExternalResourceReleasable { // FIXME Make sure all transports support writing a FileRegion // Even if zero copy cannot be achieved, all transports should emulate it. /** * Returns the offset in the file where the transfer began. */ long getPosition(); /** * Returns the number of bytes to transfer. */ long getCount(); /** * Transfers the content of this file region to the specified channel. * * @param target the destination of the transfer * @param position the relative offset of the file where the transfer * begins from. For example, 0 will make the * transfer start from {@link #getPosition()}th byte and * {@link #getCount()} - 1 will make the last * byte of the region transferred. */ long transferTo(WritableByteChannel target, long position) throws IOException; }




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