/**
* 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.util;
import java.nio.ByteBuffer;
import org.apache.hadoop.HadoopIllegalArgumentException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureEncoder;
import org.apache.hadoop.io.erasurecode.rawcoder.util.RSUtil;
/**
* Some utilities for Hitchhiker coding.
*/
@InterfaceAudience.Private
public final class HHUtil {
private HHUtil() {
// No called
}
public static int[] initPiggyBackIndexWithoutPBVec(int numDataUnits,
int numParityUnits) {
final int piggyBackSize = numDataUnits / (numParityUnits - 1);
int[] piggyBackIndex = new int[numParityUnits];
for (int i = 0; i < numDataUnits; ++i) {
if ((i % piggyBackSize) == 0) {
piggyBackIndex[i / piggyBackSize] = i;
}
}
piggyBackIndex[numParityUnits - 1] = numDataUnits;
return piggyBackIndex;
}
public static int[] initPiggyBackFullIndexVec(int numDataUnits,
int[] piggyBackIndex) {
int[] piggyBackFullIndex = new int[numDataUnits];
for (int i = 1; i < piggyBackIndex.length; ++i) {
for (int j = piggyBackIndex[i - 1]; j < piggyBackIndex[i]; ++j) {
piggyBackFullIndex[j] = i;
}
}
return piggyBackFullIndex;
}
public static ByteBuffer[] getPiggyBacksFromInput(ByteBuffer[] inputs,
int[] piggyBackIndex,
int numParityUnits,
int pgIndex,
RawErasureEncoder encoder) {
ByteBuffer[] emptyInput = new ByteBuffer[inputs.length];
ByteBuffer[] tempInput = new ByteBuffer[inputs.length];
int[] inputPositions = new int[inputs.length];
for (int m = 0; m < inputs.length; ++m) {
if (inputs[m] != null) {
emptyInput[m] = allocateByteBuffer(inputs[m].isDirect(),
inputs[m].remaining());
}
}
ByteBuffer[] tempOutput = new ByteBuffer[numParityUnits];
for (int m = 0; m < numParityUnits; ++m) {
tempOutput[m] = allocateByteBuffer(inputs[m].isDirect(),
inputs[0].remaining());
}
ByteBuffer[] piggyBacks = new ByteBuffer[numParityUnits - 1];
assert (piggyBackIndex.length >= numParityUnits);
// using underlying RS code to create piggybacks
for (int i = 0; i < numParityUnits - 1; ++i) {
for (int k = piggyBackIndex[i]; k < piggyBackIndex[i + 1]; ++k) {
tempInput[k] = inputs[k];
inputPositions[k] = inputs[k].position();
}
for (int n = 0; n < emptyInput.length; ++n) {
if (tempInput[n] == null) {
tempInput[n] = emptyInput[n];
inputPositions[n] = emptyInput[n].position();
}
}
encoder.encode(tempInput, tempOutput);
piggyBacks[i] = cloneBufferData(tempOutput[pgIndex]);
for (int j = 0; j < tempInput.length; j++) {
if (tempInput[j] != null) {
tempInput[j].position(inputPositions[j]);
tempInput[j] = null;
}
}
for (int j = 0; j < tempOutput.length; j++) {
tempOutput[j].clear();
}
}
return piggyBacks;
}
private static ByteBuffer cloneBufferData(ByteBuffer srcBuffer) {
ByteBuffer destBuffer;
byte[] bytesArr = new byte[srcBuffer.remaining()];
srcBuffer.mark();
srcBuffer.get(bytesArr);
srcBuffer.reset();
if (!srcBuffer.isDirect()) {
destBuffer = ByteBuffer.wrap(bytesArr);
} else {
destBuffer = ByteBuffer.allocateDirect(srcBuffer.remaining());
destBuffer.put(bytesArr);
destBuffer.flip();
}
return destBuffer;
}
public static ByteBuffer allocateByteBuffer(boolean useDirectBuffer,
int bufSize) {
if (useDirectBuffer) {
return ByteBuffer.allocateDirect(bufSize);
} else {
return ByteBuffer.allocate(bufSize);
}
}
public static ByteBuffer getPiggyBackForDecode(ByteBuffer[][] inputs,
ByteBuffer[][] outputs,
int pbParityIndex,
int numDataUnits,
int numParityUnits,
int pbIndex) {
ByteBuffer fisrtValidInput = HHUtil.findFirstValidInput(inputs[0]);
int bufSize = fisrtValidInput.remaining();
ByteBuffer piggybacks = allocateByteBuffer(fisrtValidInput.isDirect(),
bufSize);
// Use piggyBackParityIndex to figure out which parity location has the
// associated piggyBack
// Obtain the piggyback by subtracting the decoded (second sub-packet
// only ) parity value from the actually read parity value
if (pbParityIndex < numParityUnits) {
// not the last piggybackSet
int inputIdx = numDataUnits + pbParityIndex;
int inputPos = inputs[1][inputIdx].position();
int outputPos = outputs[1][pbParityIndex].position();
for (int m = 0, k = inputPos, n = outputPos; m < bufSize; k++, m++, n++) {
int valueWithPb = 0xFF & inputs[1][inputIdx].get(k);
int valueWithoutPb = 0xFF & outputs[1][pbParityIndex].get(n);
piggybacks.put(m, (byte) RSUtil.GF.add(valueWithPb, valueWithoutPb));
}
} else {
// last piggybackSet
int sum = 0;
for (int k = 0; k < bufSize; k++) {
sum = 0;
for (int i = 1; i < numParityUnits; i++) {
int inIdx = numDataUnits + i;
int inPos = inputs[1][numDataUnits + i].position();
int outPos = outputs[1][i].position();
sum = RSUtil.GF.add(sum, (0xFF & inputs[1][inIdx].get(inPos + k)));
sum = RSUtil.GF.add(sum, (0xFF & outputs[1][i].get(outPos + k)));
}
sum = RSUtil.GF.add(sum,
(0xFF & inputs[0][numDataUnits + pbIndex].get(
inputs[0][numDataUnits + pbIndex].position() + k)));
piggybacks.put(k, (byte) sum);
}
}
return piggybacks;
}
/**
* Find the valid input from all the inputs.
* @param inputs input buffers to look for valid input
* @return the first valid input
*/
public static <T> T findFirstValidInput(T[] inputs) {
for (T input : inputs) {
if (input != null) {
return input;
}
}
throw new HadoopIllegalArgumentException(
"Invalid inputs are found, all being null");
}
}