| /* |
| * |
| * 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.cassandra.io.util; |
| |
| import javax.annotation.concurrent.NotThreadSafe; |
| |
| import com.google.common.primitives.Ints; |
| import com.google.common.util.concurrent.RateLimiter; |
| |
| /** |
| * Rebufferer wrapper that applies rate limiting. |
| * <p> |
| * 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. |
| * Only one BufferHolder can be active at a time. Calling {@link #rebuffer(long)} before the previously obtained |
| * buffer holder is released will throw {@link AssertionError}. |
| */ |
| @NotThreadSafe |
| public class LimitingRebufferer extends WrappingRebufferer |
| { |
| final private RateLimiter limiter; |
| final private int limitQuant; |
| |
| public LimitingRebufferer(Rebufferer wrapped, RateLimiter limiter, int limitQuant) |
| { |
| super(wrapped); |
| this.limiter = limiter; |
| this.limitQuant = limitQuant; |
| } |
| |
| @Override |
| public BufferHolder rebuffer(long position) |
| { |
| super.rebuffer(position); |
| 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 String toString() |
| { |
| return "LimitingRebufferer[" + limiter + "]:" + wrapped; |
| } |
| } |