Hash Index 实验的 `LinearProbeHashTable::Resize` 的写法貌似有点问题 about cmu15-445 HOT 5 CLOSED

template <typename KeyType, typename ValueType, typename KeyComparator>
void HASH_TABLE_TYPE::Resize(size_t initial_size) {
  table_latch_.WLock();
  num_buckets_ = 2 * initial_size;
  num_pages_ = (num_buckets_ - 1) / BLOCK_ARRAY_SIZE + 1;
  last_block_array_size_ = num_buckets_ - (num_pages_ - 1) * BLOCK_ARRAY_SIZE;

  // save the old header page id
  auto old_header_page_id = header_page_id_;
  std::vector<page_id_t> old_page_ids(page_ids_);

  // get the new header page
  auto raw_header_page = buffer_pool_manager_->NewPage(&header_page_id_);
  raw_header_page->WLatch();
  InitHeaderPage(HeaderPageCast(raw_header_page));

  // move (key, value) pairs to new space
  for (size_t block_index = 0; block_index < num_pages_; ++block_index) {
    auto old_page_id = old_page_ids[block_index];
    auto raw_block_page = buffer_pool_manager_->FetchPage(old_page_id);
    raw_block_page->RLatch();
    auto block_page = BlockPageCast(raw_block_page);

    // move (key, value) pair from each readable slot
    for (slot_offset_t bucket_index = 0; bucket_index < GetBlockArraySize(block_index); ++bucket_index) {
      if (block_page->IsReadable(bucket_index)) {
        InsertImpl(nullptr, block_page->KeyAt(bucket_index), block_page->ValueAt(bucket_index));
      }
    }

    // delete old page
    raw_block_page->RUnlatch();
    buffer_pool_manager_->UnpinPage(old_page_id, false);
    buffer_pool_manager_->DeletePage(old_page_id);
  }

  raw_header_page->WUnlatch();
  buffer_pool_manager_->UnpinPage(header_page_id_, false);
  buffer_pool_manager_->DeletePage(old_header_page_id);
  table_latch_.WUnlock();
}