| /** |
| * 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.hadoop.io.erasurecode.rawcoder; |
| |
| import java.nio.ByteBuffer; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| |
| /** |
| * A raw encoder in XOR code scheme in pure Java, adapted from HDFS-RAID. |
| * |
| * XOR code is an important primitive code scheme in erasure coding and often |
| * used in advanced codes, like HitchHiker and LRC, though itself is rarely |
| * deployed independently. |
| */ |
| @InterfaceAudience.Private |
| public class XORRawEncoder extends AbstractRawErasureEncoder { |
| |
| public XORRawEncoder(int numDataUnits, int numParityUnits) { |
| super(numDataUnits, numParityUnits); |
| } |
| |
| protected void doEncode(ByteBuffer[] inputs, ByteBuffer[] outputs) { |
| ByteBuffer output = outputs[0]; |
| |
| // Get the first buffer's data. |
| int iIdx, oIdx; |
| for (iIdx = inputs[0].position(), oIdx = output.position(); |
| iIdx < inputs[0].limit(); iIdx++, oIdx++) { |
| output.put(oIdx, inputs[0].get(iIdx)); |
| } |
| |
| // XOR with everything else. |
| for (int i = 1; i < inputs.length; i++) { |
| for (iIdx = inputs[i].position(), oIdx = output.position(); |
| iIdx < inputs[i].limit(); |
| iIdx++, oIdx++) { |
| output.put(oIdx, (byte) (output.get(oIdx) ^ inputs[i].get(iIdx))); |
| } |
| } |
| } |
| |
| @Override |
| protected void doEncode(byte[][] inputs, int[] inputOffsets, int dataLen, |
| byte[][] outputs, int[] outputOffsets) { |
| byte[] output = outputs[0]; |
| resetBuffer(output, outputOffsets[0], dataLen); |
| |
| // Get the first buffer's data. |
| int iIdx, oIdx; |
| for (iIdx = inputOffsets[0], oIdx = outputOffsets[0]; |
| iIdx < inputOffsets[0] + dataLen; iIdx++, oIdx++) { |
| output[oIdx] = inputs[0][iIdx]; |
| } |
| |
| // XOR with everything else. |
| for (int i = 1; i < inputs.length; i++) { |
| for (iIdx = inputOffsets[i], oIdx = outputOffsets[0]; |
| iIdx < inputOffsets[i] + dataLen; iIdx++, oIdx++) { |
| output[oIdx] ^= inputs[i][iIdx]; |
| } |
| } |
| } |
| } |