core: dynamic fee algorithm from ArticMine

The fee will vary based on the base reward and the current
block size limit:

fee = (R/R0) * (M0/M) * F0

R: base reward
R0: reference base reward (10 monero)
M: block size limit
M0: minimum block size limit (60000)
F0: 0.002 monero

Starts applying at v4

2 files changed, 122 insertions, 0 deletions

diff --git a/tests/unit_tests/CMakeLists.txt b/tests/unit_tests/CMakeLists.txt
index b7fdc333f..f3658b9ff 100644
--- a/tests/unit_tests/CMakeLists.txt
+++ b/tests/unit_tests/CMakeLists.txt
@@ -39,6 +39,7 @@ set(unit_tests_sources
   dns_resolver.cpp
   epee_boosted_tcp_server.cpp
   epee_levin_protocol_handler_async.cpp
+  fee.cpp
   get_xtype_from_string.cpp
   main.cpp
   mnemonics.cpp
diff --git a/tests/unit_tests/fee.cpp b/tests/unit_tests/fee.cpp
new file mode 100644
index 000000000..6f1413c69
--- /dev/null
+++ b/tests/unit_tests/fee.cpp
@@ -0,0 +1,121 @@
+// Copyright (c) 2014-2016, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+// 
+// 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
+{
+  //--------------------------------------------------------------------------------------------------------------------
+  class fee : public ::testing::Test
+  {
+  };
+
+  TEST_F(fee, 10xmr)
+  {
+    // CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 and lower are clamped
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2), 2000000000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 2), 2000000000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 100), 2000000000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(10000000000000, 1), 2000000000);
+
+    // higher is inverse proportional
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 2), 2000000000 / 2);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 10), 2000000000 / 10);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 1000), 2000000000 / 1000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(10000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 1000000ull), 2000000000 / 1000000);
+  }
+
+  TEST_F(fee, 1xmr)
+  {
+    // CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 and lower are clamped
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2), 200000000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 2), 200000000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 100), 200000000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(1000000000000, 1), 200000000);
+
+    // higher is inverse proportional
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 2), 200000000 / 2);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 10), 200000000 / 10);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 1000), 200000000 / 1000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(1000000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 1000000ull), 200000000 / 1000000);
+  }
+
+  TEST_F(fee, dot3xmr)
+  {
+    // CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 and lower are clamped
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2), 60000000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 2), 60000000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 / 100), 60000000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(300000000000, 1), 60000000);
+
+    // higher is inverse proportional
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 2), 60000000 / 2);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 10), 60000000 / 10);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 1000), 60000000 / 1000);
+    ASSERT_EQ(Blockchain::get_dynamic_per_kb_fee(300000000000, CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 1000000ull), 60000000 / 1000000);
+  }
+
+  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_sizes[] = {
+      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,
+      CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V2 * 1000000ull
+    };
+
+    for (uint64_t block_reward: block_rewards)
+    {
+      for (uint64_t median_block_size: median_block_sizes)
+      {
+        ASSERT_TRUE(is_more_or_less(Blockchain::get_dynamic_per_kb_fee(block_reward, median_block_size) * (median_block_size / 1024.) * MAX_MULTIPLIER / (double)block_reward, 1.992 * 1000 / 1024));
+      }
+    }
+  }
+}