1  // Copyright (c) 2009-2010 Satoshi Nakamoto
 2  // Copyright (c) 2009-present The Bitcoin Core developers
 3  // Distributed under the MIT software license, see the accompanying
 4  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 5  
 6  #ifndef BITCOIN_POLICY_FEERATE_H
 7  #define BITCOIN_POLICY_FEERATE_H
 8  
 9  #include <consensus/amount.h>
10  #include <serialize.h>
11  #include <util/feefrac.h>
12  #include <util/fees.h>
13  
14  
15  #include <cstdint>
16  #include <string>
17  #include <type_traits>
18  
19  const std::string CURRENCY_UNIT = "BTC"; // One formatted unit
20  const std::string CURRENCY_ATOM = "sat"; // One indivisible minimum value unit
21  
22  enum class FeeRateFormat {
23      BTC_KVB, //!< Use BTC/kvB fee rate unit
24      SAT_VB,  //!< Use sat/vB fee rate unit
25  };
26  
27  /**
28   * Fee rate in satoshis per virtualbyte: CAmount / vB
29   * the feerate is represented internally as FeeFrac
30   */
31  class CFeeRate
32  {
33  private:
34      /** Fee rate in sats/vB (satoshis per N virtualbytes) */
35      FeePerVSize m_feerate;
36  
37  public:
38      /** Fee rate of 0 satoshis per 0 vB */
39      CFeeRate() = default;
40      template<std::integral I> // Disallow silent float -> int conversion
41      explicit CFeeRate(const I m_feerate_kvb) : m_feerate(FeePerVSize(m_feerate_kvb, 1000)) {}
42  
43      /**
44       * Construct a fee rate from a fee in satoshis and a vsize in vB.
45       *
46       * Passing any virtual_bytes less than or equal to 0 will result in 0 fee rate per 0 size.
47       */
48      CFeeRate(const CAmount& nFeePaid, int32_t virtual_bytes);
49  
50      /**
51       * Return the fee in satoshis for the given vsize in vbytes.
52       * If the calculated fee would have fractional satoshis, then the
53       * returned fee will always be rounded up to the nearest satoshi.
54       */
55      CAmount GetFee(int32_t virtual_bytes) const;
56  
57      FeePerVSize GetFeePerVSize() const { return m_feerate; }
58  
59      /**
60       * Return the fee in satoshis for a vsize of 1000 vbytes
61       */
62      CAmount GetFeePerK() const { return CAmount(m_feerate.EvaluateFeeDown(1000)); }
63      friend std::strong_ordering operator<=>(const CFeeRate& a, const CFeeRate& b) noexcept
64      {
65          return ByRatio{a.m_feerate} <=> ByRatio{b.m_feerate};
66      }
67      friend bool operator==(const CFeeRate& a, const CFeeRate& b) noexcept
68      {
69          return ByRatio{a.m_feerate} == ByRatio{b.m_feerate};
70      }
71      CFeeRate& operator+=(const CFeeRate& a) {
72          m_feerate = FeePerVSize(GetFeePerK() + a.GetFeePerK(), 1000);
73          return *this;
74      }
75      std::string ToString(FeeRateFormat fee_rate_format = FeeRateFormat::BTC_KVB) const;
76      friend CFeeRate operator*(const CFeeRate& f, int a) { return CFeeRate(a * f.m_feerate.fee, f.m_feerate.size); }
77      friend CFeeRate operator*(int a, const CFeeRate& f) { return CFeeRate(a * f.m_feerate.fee, f.m_feerate.size); }
78  
79      SERIALIZE_METHODS(CFeeRate, obj) { READWRITE(obj.m_feerate.fee, obj.m_feerate.size); }
80  };
81  
82  #endif // BITCOIN_POLICY_FEERATE_H