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#pragma once
#include "public.h"
#include "helpers.h"
#include <library/cpp/yt/assert/assert.h>
#include <util/generic/array_ref.h>
#include <util/generic/ptr.h>
#include <util/generic/singleton.h>
#include <vector>
extern "C" {
#include <contrib/libs/isa-l/include/erasure_code.h>
}
namespace NErasure {
template <class TBlobType>
static inline unsigned char* ConstCast(typename TBlobType::const_iterator blobIter) {
return const_cast<unsigned char*>(reinterpret_cast<const unsigned char*>(blobIter));
}
template <int DataPartCount, int ParityPartCount, class TCodecTraits, class TBlobType = typename TCodecTraits::TBlobType, class TMutableBlobType = typename TCodecTraits::TMutableBlobType>
std::vector<TBlobType> ISAErasureEncode(
const std::vector<unsigned char>& encodeGFTables,
const std::vector<TBlobType>& dataBlocks)
{
YT_VERIFY(dataBlocks.size() == DataPartCount);
size_t blockLength = dataBlocks.front().Size();
for (size_t i = 1; i < dataBlocks.size(); ++i) {
YT_VERIFY(dataBlocks[i].Size() == blockLength);
}
std::vector<unsigned char*> dataPointers;
for (const auto& block : dataBlocks) {
dataPointers.emplace_back(ConstCast<TBlobType>(block.Begin()));
}
std::vector<TMutableBlobType> parities(ParityPartCount);
std::vector<unsigned char*> parityPointers(ParityPartCount);
for (size_t i = 0; i < ParityPartCount; ++i) {
parities[i] = TCodecTraits::AllocateBlob(blockLength);
parityPointers[i] = ConstCast<TBlobType>(parities[i].Begin());
memset(parityPointers[i], 0, blockLength);
}
ec_encode_data(
blockLength,
DataPartCount,
ParityPartCount,
const_cast<unsigned char*>(encodeGFTables.data()),
dataPointers.data(),
parityPointers.data());
return std::vector<TBlobType>(parities.begin(), parities.end());
}
template <int DataPartCount, int ParityPartCount, class TCodecTraits, class TBlobType = typename TCodecTraits::TBlobType, class TMutableBlobType = typename TCodecTraits::TMutableBlobType>
std::vector<TBlobType> ISAErasureDecode(
const std::vector<TBlobType>& dataBlocks,
const TPartIndexList& erasedIndices,
TConstArrayRef<TPartIndexList> groups,
const std::vector<unsigned char>& fullGeneratorMatrix)
{
YT_VERIFY(dataBlocks.size() >= DataPartCount);
YT_VERIFY(erasedIndices.size() <= ParityPartCount);
size_t blockLength = dataBlocks.front().Size();
for (size_t i = 1; i < dataBlocks.size(); ++i) {
YT_VERIFY(dataBlocks[i].Size() == blockLength);
}
std::vector<unsigned char> partialGeneratorMatrix(DataPartCount * DataPartCount, 0);
std::vector<unsigned char*> recoveryBlocks;
for (size_t i = 0; i < DataPartCount; ++i) {
recoveryBlocks.emplace_back(ConstCast<TBlobType>(dataBlocks[i].Begin()));
}
// Groups check is specific for LRC.
std::vector<int> isGroupHealthy(2, 1);
for (size_t i = 0; i < 2; ++i) {
for (const auto& index : erasedIndices) {
if (!groups.empty() && Contains(groups[0], index)) {
isGroupHealthy[0] = 0;
} else if (!groups.empty() && Contains(groups[1], index)) {
isGroupHealthy[1] = 0;
}
}
}
// When a group is healthy we cannot use its local parity, thus skip it using gap.
size_t gap = 0;
size_t decodeMatrixIndex = 0;
size_t erasedBlockIndex = 0;
while (decodeMatrixIndex < DataPartCount) {
size_t globalIndex = decodeMatrixIndex + erasedBlockIndex + gap;
if (erasedBlockIndex < erasedIndices.size() &&
globalIndex == static_cast<size_t>(erasedIndices[erasedBlockIndex]))
{
++erasedBlockIndex;
continue;
}
if (!groups.empty() && globalIndex >= DataPartCount && globalIndex < DataPartCount + 2) {
if (Contains(groups[0], globalIndex) && isGroupHealthy[0]) {
++gap;
continue;
}
if (Contains(groups[1], globalIndex) && isGroupHealthy[1]) {
++gap;
continue;
}
}
memcpy(&partialGeneratorMatrix[decodeMatrixIndex * DataPartCount], &fullGeneratorMatrix[globalIndex * DataPartCount], DataPartCount);
++decodeMatrixIndex;
}
std::vector<unsigned char> invertedGeneratorMatrix(DataPartCount * DataPartCount, 0);
int res = gf_invert_matrix(partialGeneratorMatrix.data(), invertedGeneratorMatrix.data(), DataPartCount);
YT_VERIFY(res == 0);
std::vector<unsigned char> decodeMatrix(DataPartCount * (DataPartCount + ParityPartCount), 0);
//! Some magical code from library example.
for (size_t i = 0; i < erasedIndices.size(); ++i) {
if (erasedIndices[i] < DataPartCount) {
memcpy(&decodeMatrix[i * DataPartCount], &invertedGeneratorMatrix[erasedIndices[i] * DataPartCount], DataPartCount);
} else {
for (int k = 0; k < DataPartCount; ++k) {
int val = 0;
for (int j = 0; j < DataPartCount; ++j) {
val ^= gf_mul_erasure(invertedGeneratorMatrix[j * DataPartCount + k], fullGeneratorMatrix[DataPartCount * erasedIndices[i] + j]);
}
decodeMatrix[DataPartCount * i + k] = val;
}
}
}
std::vector<unsigned char> decodeGFTables(DataPartCount * erasedIndices.size() * 32);
ec_init_tables(DataPartCount, erasedIndices.size(), decodeMatrix.data(), decodeGFTables.data());
std::vector<TMutableBlobType> recoveredParts;
std::vector<unsigned char*> recoveredPartsPointers;
for (size_t i = 0; i < erasedIndices.size(); ++i) {
recoveredParts.emplace_back(TCodecTraits::AllocateBlob(blockLength));
recoveredPartsPointers.emplace_back(ConstCast<TBlobType>(recoveredParts.back().Begin()));
memset(recoveredPartsPointers.back(), 0, blockLength);
}
ec_encode_data(
blockLength,
DataPartCount,
erasedIndices.size(),
decodeGFTables.data(),
recoveryBlocks.data(),
recoveredPartsPointers.data());
return std::vector<TBlobType>(recoveredParts.begin(), recoveredParts.end());
}
} // namespace NErasure
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