libcryfs/implementations/onblocks/BlobOnBlocks.cpp

#include "BlobOnBlocks.h"

#include "datatreestore/DataTree.h"
#include "datanodestore/DataLeafNode.h"
#include "utils/Math.h"
#include <cmath>

using std::unique_ptr;
using std::function;
using blobstore::onblocks::datanodestore::DataLeafNode;
using blobstore::onblocks::datanodestore::DataNodeLayout;
using blockstore::Key;

namespace blobstore {
namespace onblocks {

using datatreestore::DataTree;

BlobOnBlocks::BlobOnBlocks(unique_ptr<DataTree> datatree)
: _datatree(std::move(datatree)) {
}

BlobOnBlocks::~BlobOnBlocks() {
}

uint64_t BlobOnBlocks::size() const {
  return _datatree->numStoredBytes();
}

void BlobOnBlocks::resize(uint64_t numBytes) {
  _datatree->resizeNumBytes(numBytes);
}

void BlobOnBlocks::traverseLeaves(uint64_t beginByte, uint64_t sizeBytes, function<void (uint64_t, DataLeafNode *leaf, uint32_t, uint32_t)> func) const {
  uint64_t endByte = beginByte + sizeBytes;
  assert(endByte <= size());
  uint32_t firstLeaf = beginByte / _datatree->maxBytesPerLeaf();
  uint32_t endLeaf = utils::ceilDivision(endByte, _datatree->maxBytesPerLeaf());
  _datatree->traverseLeaves(firstLeaf, endLeaf, [&func, beginByte, endByte](DataLeafNode *leaf, uint32_t leafIndex) {
    uint64_t indexOfFirstLeafByte = leafIndex * leaf->maxStoreableBytes();
    uint32_t dataBegin = utils::maxZeroSubtraction(beginByte, indexOfFirstLeafByte);
    uint32_t dataEnd = std::min((uint64_t)leaf->maxStoreableBytes(), endByte - indexOfFirstLeafByte);
    func(indexOfFirstLeafByte, leaf, dataBegin, dataEnd-dataBegin);
  });
}

void BlobOnBlocks::read(void *target, uint64_t offset, uint64_t size) const {
  traverseLeaves(offset, size, [target, offset] (uint64_t indexOfFirstLeafByte, const DataLeafNode *leaf, uint32_t leafDataOffset, uint32_t leafDataSize) {
    //TODO Simplify formula, make it easier to understand
    leaf->read((uint8_t*)target + indexOfFirstLeafByte - offset + leafDataOffset, leafDataOffset, leafDataSize);
  });
}

void BlobOnBlocks::write(const void *source, uint64_t offset, uint64_t size) {
  resizeIfSmallerThan(offset + size);
  traverseLeaves(offset, size, [source, offset] (uint64_t indexOfFirstLeafByte, DataLeafNode *leaf, uint32_t leafDataOffset, uint32_t leafDataSize) {
    //TODO Simplify formula, make it easier to understand
    leaf->write((uint8_t*)source + indexOfFirstLeafByte - offset + leafDataOffset, leafDataOffset, leafDataSize);
  });
}

void BlobOnBlocks::resizeIfSmallerThan(uint64_t neededSize) {
  //TODO This is inefficient, because size() and resizeNumBytes() both traverse the tree. Better: _datatree->ensureMinSize(x)
  if (neededSize > size()) {
    _datatree->resizeNumBytes(neededSize);
  }
}

Key BlobOnBlocks::key() const {
  return _datatree->key();
}

unique_ptr<DataTree> BlobOnBlocks::releaseTree() {
  return std::move(_datatree);
}

}
}