| /* |
| * 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 java.nio.ByteBuffer; |
| import javax.annotation.concurrent.NotThreadSafe; |
| |
| /** |
| * 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 buffer holder can be active at a time. Calling {@link #rebuffer(long)} before the previously obtained |
| * buffer holder is released will throw {@link AssertionError}. We will get that exception also in case we try to close |
| * the rebufferer without closing the recently obtained buffer holder. |
| * <p> |
| * Calling methods of {@link BufferHolder} will also produce {@link AssertionError} if buffer holder is not acquired. |
| * <p> |
| * The overriding classes must conform to the aforementioned rules. |
| */ |
| @NotThreadSafe |
| public abstract class WrappingRebufferer implements Rebufferer, Rebufferer.BufferHolder |
| { |
| protected final Rebufferer wrapped; |
| |
| protected BufferHolder bufferHolder; |
| protected ByteBuffer buffer; |
| protected long offset; |
| |
| public WrappingRebufferer(Rebufferer wrapped) |
| { |
| this.wrapped = wrapped; |
| } |
| |
| @Override |
| public BufferHolder rebuffer(long position) |
| { |
| assert buffer == null; |
| bufferHolder = wrapped.rebuffer(position); |
| buffer = bufferHolder.buffer(); |
| offset = bufferHolder.offset(); |
| |
| 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() |
| { |
| assert buffer == null : "Rebufferer is attempted to be closed but the buffer holder has not been released"; |
| wrapped.close(); |
| } |
| |
| @Override |
| public void closeReader() |
| { |
| wrapped.closeReader(); |
| } |
| |
| @Override |
| public String toString() |
| { |
| return String.format("%s[]:%s", getClass().getSimpleName(), wrapped.toString()); |
| } |
| |
| @Override |
| public ByteBuffer buffer() |
| { |
| assert buffer != null : "Buffer holder has not been acquired"; |
| return buffer; |
| } |
| |
| @Override |
| public long offset() |
| { |
| assert buffer != null : "Buffer holder has not been acquired"; |
| return offset; |
| } |
| |
| @Override |
| public void release() |
| { |
| assert buffer != null; |
| if (bufferHolder != null) |
| { |
| bufferHolder.release(); |
| bufferHolder = null; |
| } |
| buffer = null; |
| } |
| } |