random_source.hpp

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// Copyright (c) 2021 MIT Digital Currency Initiative,
//                    Federal Reserve Bank of Boston
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#ifndef OPENCBDC_TX_SRC_COMMON_RANDOM_SOURCE_H_
#define OPENCBDC_TX_SRC_COMMON_RANDOM_SOURCE_H_
 
#include "crypto/sha256.h"
#include "hash.hpp"
 
#include <limits>
#include <mutex>
#include <queue>
 
namespace cbdc {
    class random_source {
      public:
        using result_type = unsigned int;
 
        explicit random_source(const std::string& source_file);
        ~random_source() = default;
 
        random_source(const random_source& other) = delete;
        auto operator=(const random_source& other) = delete;
 
        random_source(random_source&& other) = delete;
        auto operator=(random_source&& other) = delete;
 
        auto operator()() -> result_type;
 
        static constexpr auto min() -> result_type {
            return std::numeric_limits<result_type>::min();
        }
 
        static constexpr auto max() -> result_type {
            return std::numeric_limits<result_type>::max();
        }
 
        auto random_hash() -> hash_t;
 
      private:
        auto hash_at_index(uint64_t idx) -> hash_t;
 
        std::mutex m_mut;
 
        std::queue<unsigned char> m_buf;
 
        CSHA256 m_sha;
        uint64_t m_counter{};
    };
}
 
#endif // OPENCBDC_TX_SRC_COMMON_RANDOM_SOURCE_H_