Method loadLeaf

source/core/StarBTreeDatabase.cpp:622–677

}

auto BTreeDatabase::BTreeImpl::loadLeaf(Pointer pointer) -> Leaf {
  auto leaf = make_shared<LeafNode>();
  leaf->self = pointer;

  BlockIndex currentLeafBlock = leaf->self;
  DataStreamBuffer leafBuffer;
  leafBuffer.reset(parent->m_blockSize);
  parent->readBlock(currentLeafBlock, 0, leafBuffer.ptr(), parent->m_blockSize);

  if (leafBuffer.readBytes(2) != ByteArray(LeafMagic, 2))
    throw DBException("Error, incorrect leaf block signature.");

  DataStreamFunctions leafInput([&](char* data, size_t len) -> size_t {
      size_t pos = 0;
      size_t left = len;

      while (left > 0) {
        if (leafBuffer.pos() + left < parent->m_blockSize - sizeof(BlockIndex)) {
          leafBuffer.readData(data + pos, left);
          pos += left;
          left = 0;
        } else {
          size_t toRead = parent->m_blockSize - sizeof(BlockIndex) - leafBuffer.pos();
          leafBuffer.readData(data + pos, toRead);
          pos += toRead;
          left -= toRead;
        }

        if (leafBuffer.pos() == (parent->m_blockSize - sizeof(BlockIndex)) && left > 0) {
          currentLeafBlock = leafBuffer.read<BlockIndex>();
          if (currentLeafBlock != InvalidBlockIndex) {
            leafBuffer.reset(parent->m_blockSize);
            parent->readBlock(currentLeafBlock, 0, leafBuffer.ptr(), parent->m_blockSize);

            if (leafBuffer.readBytes(2) != ByteArray(LeafMagic, 2))
              throw DBException("Error, incorrect leaf block signature.");

          } else {
            throw DBException("Leaf read off end of Leaf list.");
          }
        }
      }

      return len;
    }, {});

  uint32_t count = leafInput.read<uint32_t>();
  leaf->elements.resize(count);
  for (uint32_t i = 0; i < count; ++i) {
    auto& element = leaf->elements[i];
    element.key = leafInput.readBytes(parent->m_keySize);
    element.data = leafInput.read<ByteArray>();
  }

  return leaf;
}

bool BTreeDatabase::BTreeImpl::leafNeedsShift(Leaf const& l) {