monero/tests/unit_tests/fee.cpp

// Copyright (c) 2014-2022, The Monero Project
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// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers

#include "gtest/gtest.h"

#include "cryptonote_core/blockchain.h"

using namespace cryptonote;

namespace
{
  static uint64_t clamp_fee(uint64_t fee)
  {
    static uint64_t mask = 0;
    if (mask == 0)
    {
      mask = 1;
      for (size_t n = PER_KB_FEE_QUANTIZATION_DECIMALS; n < CRYPTONOTE_DISPLAY_DECIMAL_POINT; ++n)
        mask *= 10;
    }
    return (fee + mask - 1) / mask * mask;
  }

  //--------------------------------------------------------------------------------------------------------------------
  class fee : public ::testing::Test
  {
  };

  // try with blocks ~ 1GB. Passing 2 GB will break on 32 bit systems

  TEST_F(fee, 10xmr)
  {
    // CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 and lower are clamped
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2, 3), clamp_fee(2000000000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 2, 3), clamp_fee(2000000000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 100, 3), clamp_fee(2000000000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(10000000000000, 1, 3), 2000000000);

    // higher is inverse proportional
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 2, 3), clamp_fee(2000000000 / 2));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 10, 3), clamp_fee(2000000000 / 10));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 1000, 3), clamp_fee(2000000000 / 1000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 20000ull, 3), clamp_fee(2000000000 / 20000));
  }

  TEST_F(fee, 1xmr)
  {
    // CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 and lower are clamped
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2, 3), clamp_fee(200000000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 2, 3), clamp_fee(200000000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 100, 3), clamp_fee(200000000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(1000000000000, 1, 3), 200000000);

    // higher is inverse proportional
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 2, 3), clamp_fee(200000000 / 2));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 10, 3), clamp_fee(200000000 / 10));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 1000, 3), clamp_fee(200000000 / 1000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 20000ull, 3), clamp_fee(200000000 / 20000));
  }

  TEST_F(fee, dot3xmr)
  {
    // CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 and lower are clamped
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2, 3), clamp_fee(60000000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 2, 3), clamp_fee(60000000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 100, 3), clamp_fee(60000000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(300000000000, 1, 3), 60000000);

    // higher is inverse proportional
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 2, 3), clamp_fee(60000000 / 2));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 10, 3), clamp_fee(60000000 / 10));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 1000, 3), clamp_fee(60000000 / 1000));
    ASSERT_EQ(Blockchain::get_dynamic_base_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 20000ull, 3), clamp_fee(60000000 / 20000));
  }

  static bool is_more_or_less(double x, double y)
  {
    return fabs(y - x) < 0.001;
  }

  static const double MAX_MULTIPLIER = 166.f;

  TEST_F(fee, double_at_full)
  {
    static const uint64_t block_rewards[] = {
      20000000000000ull, // 20 monero
      13000000000000ull,
      1000000000000ull,
      600000000000ull, // .6 monero, minimum reward per block at 2min
      300000000000ull, // .3 monero, minimum reward per block at 1min
    };
    static const uint64_t median_block_weights[] = {
      CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2,
      CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 2,
      CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 10,
      CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 1000,
      // with clamping, the formula does not hold for such large blocks and small fees
      // CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 20000ull
    };

    for (uint64_t block_reward: block_rewards)
    {
      for (uint64_t median_block_weight: median_block_weights)
      {
        ASSERT_TRUE(is_more_or_less(Blockchain::get_dynamic_base_fee(block_reward, median_block_weight, 3) * (median_block_weight / 1024.) * MAX_MULTIPLIER / (double)block_reward, 1.992 * 1000 / 1024));
      }
    }
  }
}