hadoop HHXORErasureDecodingStep 源码
haddop HHXORErasureDecodingStep 代码
文件路径：/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/coder/HHXORErasureDecodingStep.java
/**
* 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.coder;
import java.io.IOException;
import java.nio.ByteBuffer;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.io.erasurecode.ECBlock;
import org.apache.hadoop.io.erasurecode.ECChunk;
import org.apache.hadoop.io.erasurecode.coder.util.HHUtil;
import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureDecoder;
import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureEncoder;
/**
* Hitchhiker-XOR Erasure decoding step, a wrapper of all the necessary
* information to perform a decoding step involved in the whole process of
* decoding a block group.
*/
@InterfaceAudience.Private
public class HHXORErasureDecodingStep extends HHErasureCodingStep {
private int pbIndex;
private int[] piggyBackIndex;
private int[] piggyBackFullIndex;
private int[] erasedIndexes;
private RawErasureDecoder rsRawDecoder;
private RawErasureEncoder xorRawEncoder;
/**
* The constructor with all the necessary info.
* @param inputBlocks inputBlocks.
* @param erasedIndexes the indexes of erased blocks in inputBlocks array
* @param outputBlocks outputBlocks.
* @param rawDecoder underlying RS decoder for hitchhiker decoding
* @param rawEncoder underlying XOR encoder for hitchhiker decoding
*/
public HHXORErasureDecodingStep(ECBlock[] inputBlocks, int[] erasedIndexes,
ECBlock[] outputBlocks, RawErasureDecoder rawDecoder,
RawErasureEncoder rawEncoder) {
super(inputBlocks, outputBlocks);
this.pbIndex = rawDecoder.getNumParityUnits() - 1;
this.erasedIndexes = erasedIndexes;
this.rsRawDecoder = rawDecoder;
this.xorRawEncoder = rawEncoder;
this.piggyBackIndex = HHUtil.initPiggyBackIndexWithoutPBVec(
rawDecoder.getNumDataUnits(), rawDecoder.getNumParityUnits());
this.piggyBackFullIndex = HHUtil.initPiggyBackFullIndexVec(
rawDecoder.getNumDataUnits(), piggyBackIndex);
}
@Override
public void performCoding(ECChunk[] inputChunks, ECChunk[] outputChunks)
throws IOException {
if (erasedIndexes.length == 0) {
return;
}
ByteBuffer[] inputBuffers = ECChunk.toBuffers(inputChunks);
ByteBuffer[] outputBuffers = ECChunk.toBuffers(outputChunks);
performCoding(inputBuffers, outputBuffers);
}
private void performCoding(ByteBuffer[] inputs, ByteBuffer[] outputs)
throws IOException {
final int numDataUnits = rsRawDecoder.getNumDataUnits();
final int numParityUnits = rsRawDecoder.getNumParityUnits();
final int numTotalUnits = numDataUnits + numParityUnits;
final int subPacketSize = getSubPacketSize();
ByteBuffer fisrtValidInput = HHUtil.findFirstValidInput(inputs);
final int bufSize = fisrtValidInput.remaining();
if (inputs.length != numTotalUnits * getSubPacketSize()) {
throw new IllegalArgumentException("Invalid inputs length");
}
if (outputs.length != erasedIndexes.length * getSubPacketSize()) {
throw new IllegalArgumentException("Invalid outputs length");
}
// notes:inputs length = numDataUnits * subPacketizationSize
// first numDataUnits length is first sub-stripe,
// second numDataUnits length is second sub-stripe
ByteBuffer[][] newIn = new ByteBuffer[subPacketSize][numTotalUnits];
for (int i = 0; i < subPacketSize; ++i) {
for (int j = 0; j < numTotalUnits; ++j) {
newIn[i][j] = inputs[i * numTotalUnits + j];
}
}
ByteBuffer[][] newOut = new ByteBuffer[subPacketSize][erasedIndexes.length];
for (int i = 0; i < subPacketSize; ++i) {
for (int j = 0; j < erasedIndexes.length; ++j) {
newOut[i][j] = outputs[i * erasedIndexes.length + j];
}
}
if (erasedIndexes.length == 1 && erasedIndexes[0] < numDataUnits) {
// Only reconstruct one data unit missing
doDecodeSingle(newIn, newOut, erasedIndexes[0], bufSize,
fisrtValidInput.isDirect());
} else {
doDecodeMultiAndParity(newIn, newOut, erasedIndexes, bufSize);
}
}
private void doDecodeSingle(ByteBuffer[][] inputs, ByteBuffer[][] outputs,
int erasedLocationToFix, int bufSize,
boolean isDirect) throws IOException {
final int numDataUnits = rsRawDecoder.getNumDataUnits();
final int numParityUnits = rsRawDecoder.getNumParityUnits();
final int subPacketSize = getSubPacketSize();
int[][] inputPositions = new int[subPacketSize][inputs[0].length];
for (int i = 0; i < subPacketSize; ++i) {
for (int j = 0; j < inputs[i].length; ++j) {
if (inputs[i][j] != null) {
inputPositions[i][j] = inputs[i][j].position();
}
}
}
ByteBuffer[] tempInputs = new ByteBuffer[numDataUnits + numParityUnits];
for (int i = 0; i < tempInputs.length; ++i) {
tempInputs[i] = inputs[1][i];
}
ByteBuffer[][] tmpOutputs = new ByteBuffer[subPacketSize][numParityUnits];
for (int i = 0; i < getSubPacketSize(); ++i) {
for (int j = 0; j < erasedIndexes.length; ++j) {
tmpOutputs[i][j] = outputs[i][j];
}
for (int m = erasedIndexes.length; m < numParityUnits; ++m) {
tmpOutputs[i][m] = HHUtil.allocateByteBuffer(isDirect, bufSize);
}
}
// First consider the second subPacket
int[] erasedLocation = new int[numParityUnits];
erasedLocation[0] = erasedLocationToFix;
// assign the erased locations based on the locations not read for
// second subPacket but from decoding
for (int i = 1; i < numParityUnits; i++) {
erasedLocation[i] = numDataUnits + i;
tempInputs[numDataUnits + i] = null;
}
rsRawDecoder.decode(tempInputs, erasedLocation, tmpOutputs[1]);
int piggyBackParityIndex = piggyBackFullIndex[erasedLocationToFix];
ByteBuffer piggyBack = HHUtil.getPiggyBackForDecode(inputs, tmpOutputs,
piggyBackParityIndex, numDataUnits, numParityUnits, pbIndex);
// Second consider the first subPacket.
// get the value of the piggyback associated with the erased location
if (isDirect) {
// decode the erased value in the first subPacket by using the piggyback
int idxToWrite = 0;
doDecodeByPiggyBack(inputs[0], tmpOutputs[0][idxToWrite], piggyBack,
erasedLocationToFix);
} else {
ByteBuffer buffer;
byte[][][] newInputs = new byte[getSubPacketSize()][inputs[0].length][];
int[][] inputOffsets = new int[getSubPacketSize()][inputs[0].length];
byte[][][] newOutputs = new byte[getSubPacketSize()][numParityUnits][];
int[][] outOffsets = new int[getSubPacketSize()][numParityUnits];
for (int i = 0; i < getSubPacketSize(); ++i) {
for (int j = 0; j < inputs[0].length; ++j) {
buffer = inputs[i][j];
if (buffer != null) {
inputOffsets[i][j] = buffer.arrayOffset() + buffer.position();
newInputs[i][j] = buffer.array();
}
}
}
for (int i = 0; i < getSubPacketSize(); ++i) {
for (int j = 0; j < numParityUnits; ++j) {
buffer = tmpOutputs[i][j];
if (buffer != null) {
outOffsets[i][j] = buffer.arrayOffset() + buffer.position();
newOutputs[i][j] = buffer.array();
}
}
}
byte[] newPiggyBack = piggyBack.array();
// decode the erased value in the first subPacket by using the piggyback
int idxToWrite = 0;
doDecodeByPiggyBack(newInputs[0], inputOffsets[0],
newOutputs[0][idxToWrite], outOffsets[0][idxToWrite],
newPiggyBack, erasedLocationToFix, bufSize);
}
for (int i = 0; i < subPacketSize; ++i) {
for (int j = 0; j < inputs[i].length; ++j) {
if (inputs[i][j] != null) {
inputs[i][j].position(inputPositions[i][j] + bufSize);
}
}
}
}
private void doDecodeByPiggyBack(ByteBuffer[] inputs,
ByteBuffer outputs,
ByteBuffer piggyBack,
int erasedLocationToFix) {
final int thisPiggyBackSetIdx = piggyBackFullIndex[erasedLocationToFix];
final int startIndex = piggyBackIndex[thisPiggyBackSetIdx - 1];
final int endIndex = piggyBackIndex[thisPiggyBackSetIdx];
// recover first sub-stripe data by XOR piggyback
int bufSize = piggyBack.remaining();
for (int i = piggyBack.position();
i < piggyBack.position() + bufSize; i++) {
for (int j = startIndex; j < endIndex; j++) {
if (inputs[j] != null) {
piggyBack.put(i, (byte)
(piggyBack.get(i) ^ inputs[j].get(inputs[j].position() + i)));
}
}
outputs.put(outputs.position() + i, piggyBack.get(i));
}
}
private void doDecodeByPiggyBack(byte[][] inputs, int[] inputOffsets,
byte[] outputs, int outOffset,
byte[] piggyBack, int erasedLocationToFix,
int bufSize) {
final int thisPiggyBackSetIdx = piggyBackFullIndex[erasedLocationToFix];
final int startIndex = piggyBackIndex[thisPiggyBackSetIdx - 1];
final int endIndex = piggyBackIndex[thisPiggyBackSetIdx];
// recover first sub-stripe data by XOR piggyback
for (int i = 0; i < bufSize; i++) {
for (int j = startIndex; j < endIndex; j++) {
if (inputs[j] != null) {
piggyBack[i] = (byte) (piggyBack[i] ^ inputs[j][i + inputOffsets[j]]);
}
}
outputs[i + outOffset] = piggyBack[i];
}
}
private void doDecodeMultiAndParity(ByteBuffer[][] inputs,
ByteBuffer[][] outputs,
int[] erasedLocationToFix, int bufSize)
throws IOException {
final int numDataUnits = rsRawDecoder.getNumDataUnits();
final int numParityUnits = rsRawDecoder.getNumParityUnits();
final int numTotalUnits = numDataUnits + numParityUnits;
int[] parityToFixFlag = new int[numTotalUnits];
for (int i = 0; i < erasedLocationToFix.length; ++i) {
if (erasedLocationToFix[i] >= numDataUnits) {
parityToFixFlag[erasedLocationToFix[i]] = 1;
}
}
int[] inputPositions = new int[inputs[0].length];
for (int i = 0; i < inputPositions.length; i++) {
if (inputs[0][i] != null) {
inputPositions[i] = inputs[0][i].position();
}
}
// decoded first sub-stripe
rsRawDecoder.decode(inputs[0], erasedLocationToFix, outputs[0]);
for (int i = 0; i < inputs[0].length; i++) {
if (inputs[0][i] != null) {
// dataLen bytes consumed
inputs[0][i].position(inputPositions[i]);
}
}
ByteBuffer[] tempInput = new ByteBuffer[numDataUnits];
for (int i = 0; i < numDataUnits; ++i) {
tempInput[i] = inputs[0][i];
//
// if (!isDirect && tempInput[i] != null) {
// tempInput[i].position(tempInput[i].position() - bufSize);
// }
}
for (int i = 0; i < erasedLocationToFix.length; ++i) {
if (erasedLocationToFix[i] < numDataUnits) {
tempInput[erasedLocationToFix[i]] = outputs[0][i];
}
}
ByteBuffer[] piggyBack = HHUtil.getPiggyBacksFromInput(tempInput,
piggyBackIndex, numParityUnits, 0, xorRawEncoder);
for (int j = numDataUnits + 1; j < numTotalUnits; ++j) {
if (parityToFixFlag[j] == 0 && inputs[1][j] != null) {
// f(b) + f(a1,a2,a3....)
for (int k = inputs[1][j].position(),
m = piggyBack[j - numDataUnits - 1].position();
k < inputs[1][j].limit(); ++k, ++m) {
inputs[1][j].put(k, (byte)
(inputs[1][j].get(k) ^
piggyBack[j - numDataUnits - 1].get(m)));
}
}
}
// decoded second sub-stripe
rsRawDecoder.decode(inputs[1], erasedLocationToFix, outputs[1]);
// parity index = 0, the data have no piggyBack
for (int j = 0; j < erasedLocationToFix.length; ++j) {
if (erasedLocationToFix[j] < numTotalUnits
&& erasedLocationToFix[j] > numDataUnits) {
int parityIndex = erasedLocationToFix[j] - numDataUnits - 1;
for (int k = outputs[1][j].position(),
m = piggyBack[parityIndex].position();
k < outputs[1][j].limit(); ++k, ++m) {
outputs[1][j].put(k, (byte)
(outputs[1][j].get(k) ^ piggyBack[parityIndex].get(m)));
}
}
}
for (int i = 0; i < inputs[0].length; i++) {
if (inputs[0][i] != null) {
// dataLen bytes consumed
inputs[0][i].position(inputPositions[i] + bufSize);
}
}
}
}
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