org.apache.cassandra.io.util.LimitingRebufferer Maven / Gradle / Ivy
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*
* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* KIND, either express or implied. See the License for the
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*/
package org.apache.cassandra.io.util;
import java.nio.ByteBuffer;
import com.google.common.primitives.Ints;
import com.google.common.util.concurrent.RateLimiter;
/**
* Rebufferer wrapper that applies rate limiting.
*
* Instantiated once per RandomAccessReader, thread-unsafe.
* The instances reuse themselves as the BufferHolder to avoid having to return a new object for each rebuffer call.
*/
public class LimitingRebufferer implements Rebufferer, Rebufferer.BufferHolder
{
final private Rebufferer wrapped;
final private RateLimiter limiter;
final private int limitQuant;
private BufferHolder bufferHolder;
private ByteBuffer buffer;
private long offset;
public LimitingRebufferer(Rebufferer wrapped, RateLimiter limiter, int limitQuant)
{
this.wrapped = wrapped;
this.limiter = limiter;
this.limitQuant = limitQuant;
}
@Override
public BufferHolder rebuffer(long position)
{
bufferHolder = wrapped.rebuffer(position);
buffer = bufferHolder.buffer();
offset = bufferHolder.offset();
int posInBuffer = Ints.checkedCast(position - offset);
int remaining = buffer.limit() - posInBuffer;
if (remaining == 0)
return this;
if (remaining > limitQuant)
{
buffer.limit(posInBuffer + limitQuant); // certainly below current limit
remaining = limitQuant;
}
limiter.acquire(remaining);
return this;
}
@Override
public ChannelProxy channel()
{
return wrapped.channel();
}
@Override
public long fileLength()
{
return wrapped.fileLength();
}
@Override
public double getCrcCheckChance()
{
return wrapped.getCrcCheckChance();
}
@Override
public void close()
{
wrapped.close();
}
@Override
public void closeReader()
{
wrapped.closeReader();
}
@Override
public String toString()
{
return "LimitingRebufferer[" + limiter.toString() + "]:" + wrapped.toString();
}
// BufferHolder methods
@Override
public ByteBuffer buffer()
{
return buffer;
}
@Override
public long offset()
{
return offset;
}
@Override
public void release()
{
bufferHolder.release();
}
}