FixedSizeQueue::FixedSizeQueue(const std::string& filename, size_t size)
    : size_(size)
    , head_(0)
    , tail_(0)
{
    fopen_s(&file_, filename.c_str(), "w+");
    InitializeCriticalSection(&critical_section_);
}

void
FixedSizeQueue::push_values(int* values, size_t count)
{
    Logger::report("Called push_values");
    EnterCriticalSection(&critical_section_);
    size_t free_items = (tail_ > head_) ? size_ - tail_ + head_ : size_ - head_ + tail_;
    if (count > free_items)
    {
        Logger::report("Buffer is full, can't push new values.");
        exit(1);
    }

    size_t till_end = (tail_ >= head_) ? size_ - tail_ : head_ - tail_;

    if (count < till_end)
    {
        fseek(file_, tail_ * sizeof(int), SEEK_SET);
        int g = fwrite(values, sizeof(int), count, file_);
        assert(g == count);

        tail_ += count;
    }
    else
    {
        fseek(file_, tail_ * sizeof(int), SEEK_SET);
        int h = fwrite(values, sizeof(int), till_end, file_);
        assert(h == till_end);
        fseek(file_, tail_ * sizeof(int), SEEK_SET);
        h = fwrite(values + count, sizeof(int), count - till_end, file_);
        assert(h == count - till_end);

        tail_ = count - till_end;
    }
    fflush(file_);
    LeaveCriticalSection(&critical_section_);
}

size_t
FixedSizeQueue::get_values(int* values)
{
    Logger::report("Called get_values");
    EnterCriticalSection(&critical_section_);
    const size_t item_count = (tail_ >= head_) ? tail_ - head_ : size_ - head_ + tail_;
    if (tail_ > head_)
    {
        fseek(file_, head_ * sizeof(int), SEEK_SET);
        fread(values, sizeof(int), item_count, file_);
    }
    else
    {
        fseek(file_, (size_ - head_) * sizeof(int), SEEK_SET);
        fread(values, sizeof(int), size_ - head_, file_);
        fseek(file_, 0, SEEK_SET);
        fread(values + size_ - head_, sizeof(int), tail_, file_);
    }

    head_ = tail_ = 0;

    LeaveCriticalSection(&critical_section_);

    return item_count;
}

fopen_s( path, "wc") // w - write mode, c - allow immediate commit to disk

_flushall()

fclose()