| /* |
| * |
| * 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 java.nio.ByteOrder; |
| |
| import org.apache.cassandra.utils.memory.BufferPool; |
| |
| /** |
| * Buffer manager used for reading from a ChunkReader when cache is not in use. Instances of this class are |
| * reader-specific and thus do not need to be thread-safe since the reader itself isn't. |
| * |
| * The instances reuse themselves as the BufferHolder to avoid having to return a new object for each rebuffer call. |
| */ |
| public abstract class BufferManagingRebufferer implements Rebufferer, Rebufferer.BufferHolder |
| { |
| protected final ChunkReader source; |
| protected final ByteBuffer buffer; |
| protected long offset = 0; |
| |
| abstract long alignedPosition(long position); |
| |
| protected BufferManagingRebufferer(ChunkReader wrapped) |
| { |
| this.source = wrapped; |
| buffer = BufferPool.get(wrapped.chunkSize(), wrapped.preferredBufferType()).order(ByteOrder.BIG_ENDIAN); |
| buffer.limit(0); |
| } |
| |
| @Override |
| public void closeReader() |
| { |
| BufferPool.put(buffer); |
| offset = -1; |
| } |
| |
| @Override |
| public void close() |
| { |
| assert offset == -1; // reader must be closed at this point. |
| source.close(); |
| } |
| |
| @Override |
| public ChannelProxy channel() |
| { |
| return source.channel(); |
| } |
| |
| @Override |
| public long fileLength() |
| { |
| return source.fileLength(); |
| } |
| |
| @Override |
| public BufferHolder rebuffer(long position) |
| { |
| offset = alignedPosition(position); |
| source.readChunk(offset, buffer); |
| return this; |
| } |
| |
| @Override |
| public double getCrcCheckChance() |
| { |
| return source.getCrcCheckChance(); |
| } |
| |
| @Override |
| public String toString() |
| { |
| return "BufferManagingRebufferer." + getClass().getSimpleName() + ":" + source.toString(); |
| } |
| |
| // BufferHolder methods |
| |
| public ByteBuffer buffer() |
| { |
| return buffer; |
| } |
| |
| public long offset() |
| { |
| return offset; |
| } |
| |
| @Override |
| public void release() |
| { |
| // nothing to do, we don't delete buffers before we're closed. |
| } |
| |
| public static class Unaligned extends BufferManagingRebufferer |
| { |
| public Unaligned(ChunkReader wrapped) |
| { |
| super(wrapped); |
| } |
| |
| @Override |
| long alignedPosition(long position) |
| { |
| return position; |
| } |
| } |
| |
| public static class Aligned extends BufferManagingRebufferer |
| { |
| public Aligned(ChunkReader wrapped) |
| { |
| super(wrapped); |
| assert Integer.bitCount(wrapped.chunkSize()) == 1; |
| } |
| |
| @Override |
| long alignedPosition(long position) |
| { |
| return position & -buffer.capacity(); |
| } |
| } |
| } |