org.eclipse.jetty.server.resource.SeekableByteChannelRangeWriter Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of jetty-server Show documentation
Show all versions of jetty-server Show documentation
The core jetty server artifact.
//
// ========================================================================
// Copyright (c) 1995 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//
package org.eclipse.jetty.server.resource;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.SeekableByteChannel;
import org.eclipse.jetty.util.BufferUtil;
import org.eclipse.jetty.util.IO;
public class SeekableByteChannelRangeWriter implements RangeWriter
{
public static final int NO_PROGRESS_LIMIT = 3;
public interface ChannelSupplier
{
SeekableByteChannel newSeekableByteChannel() throws IOException;
}
private final ChannelSupplier channelSupplier;
private final int bufSize;
private final ByteBuffer buffer;
private SeekableByteChannel channel;
private long pos;
private boolean defaultSeekMode = true;
public SeekableByteChannelRangeWriter(SeekableByteChannelRangeWriter.ChannelSupplier channelSupplier)
{
this(null, channelSupplier);
}
public SeekableByteChannelRangeWriter(SeekableByteChannel initialChannel, SeekableByteChannelRangeWriter.ChannelSupplier channelSupplier)
{
this.channel = initialChannel;
this.channelSupplier = channelSupplier;
this.bufSize = IO.bufferSize;
this.buffer = BufferUtil.allocate(this.bufSize);
}
@Override
public void close() throws IOException
{
if (this.channel != null)
{
this.channel.close();
}
}
@Override
public void writeTo(OutputStream outputStream, long skipTo, long length) throws IOException
{
skipTo(skipTo);
// copy from channel to output stream
long readTotal = 0;
while (readTotal < length)
{
BufferUtil.clearToFill(buffer);
int size = (int)Math.min(bufSize, length - readTotal);
buffer.limit(size);
int readLen = channel.read(buffer);
BufferUtil.flipToFlush(buffer, 0);
BufferUtil.writeTo(buffer, outputStream);
readTotal += readLen;
pos += readLen;
}
}
private void skipTo(long skipTo) throws IOException
{
if (channel == null)
{
channel = channelSupplier.newSeekableByteChannel();
pos = 0;
}
if (defaultSeekMode)
{
try
{
if (channel.position() != skipTo)
{
channel.position(skipTo);
pos = skipTo;
return;
}
}
catch (UnsupportedOperationException e)
{
defaultSeekMode = false;
fallbackSkipTo(skipTo);
}
}
else
{
// Fallback mode
fallbackSkipTo(skipTo);
}
}
private void fallbackSkipTo(long skipTo) throws IOException
{
if (skipTo < pos)
{
channel.close();
channel = channelSupplier.newSeekableByteChannel();
pos = 0;
}
if (pos < skipTo)
{
long skipSoFar = pos;
long actualSkipped;
int noProgressLoopLimit = NO_PROGRESS_LIMIT;
// loop till we reach desired point, break out on lack of progress.
while (noProgressLoopLimit > 0 && skipSoFar < skipTo)
{
BufferUtil.clearToFill(buffer);
int len = (int)Math.min(bufSize, (skipTo - skipSoFar));
buffer.limit(len);
actualSkipped = channel.read(buffer);
if (actualSkipped == 0)
{
noProgressLoopLimit--;
}
else if (actualSkipped > 0)
{
skipSoFar += actualSkipped;
noProgressLoopLimit = NO_PROGRESS_LIMIT;
}
else
{
// negative values means the stream was closed or reached EOF
// either way, we've hit a state where we can no longer
// fulfill the requested range write.
throw new IOException("EOF reached before SeekableByteChannel skip destination");
}
}
if (noProgressLoopLimit <= 0)
{
throw new IOException("No progress made to reach SeekableByteChannel skip position " + (skipTo - pos));
}
pos = skipTo;
}
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy