https://clickhouse-test-reports.s3.yandex.net/8367/333ec2e496f4fe4addd22d5fa7c5c2a499099c57/fuzzer/fuzzer.log#fail1
void operator()(const KeyRef key) const
    {
        keys_pool.freeKey(key);
    }
    ComplexKeysPool & keys_pool;
};
/*
    Class for operations with cache file and index.
    Supports GET/SET operations.
*/
class SSDComplexKeyCachePartition
{
public:
    struct Index final
    {
        bool inMemory() const;
        void setInMemory(const bool in_memory);
        bool exists() const;
        void setNotExists();
        size_t getAddressInBlock() const;
        void setAddressInBlock(const size_t address_in_block);
        size_t getBlockId() const;
        void setBlockId(const size_t block_id);
        bool operator< (const Index & rhs) const { return index < rhs.index; }
        
        uint64_t index = 0;
    };
    struct Metadata final
    {
        using time_point_t = std::chrono::system_clock::time_point;