blockchain: keep a rolling long term block weight median

2 files changed, 203 insertions, 0 deletions

diff --git a/tests/unit_tests/CMakeLists.txt b/tests/unit_tests/CMakeLists.txt
index 56a1f8c4d..1c4c4384c 100644
--- a/tests/unit_tests/CMakeLists.txt
+++ b/tests/unit_tests/CMakeLists.txt
@@ -72,6 +72,7 @@ set(unit_tests_sources
   parse_amount.cpp
   pruning.cpp
   random.cpp
+  rolling_median.cpp
   serialization.cpp
   sha256.cpp
   slow_memmem.cpp
diff --git a/tests/unit_tests/rolling_median.cpp b/tests/unit_tests/rolling_median.cpp
new file mode 100644
index 000000000..6d6adcc7d
--- /dev/null
+++ b/tests/unit_tests/rolling_median.cpp
@@ -0,0 +1,202 @@
+// Copyright (c) 2019, 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.
+
+#include <random>
+#include "gtest/gtest.h"
+#include "misc_language.h"
+#include "rolling_median.h"
+#include "crypto/crypto.h"
+
+TEST(rolling_median, one)
+{
+  epee::misc_utils::rolling_median_t<uint64_t> m(1);
+  m.insert(42);
+  ASSERT_EQ(m.median(), 42);
+  m.insert(18);
+  ASSERT_EQ(m.median(), 18);
+  m.insert(7483);
+  ASSERT_EQ(m.median(), 7483);
+}
+
+TEST(rolling_median, two)
+{
+  epee::misc_utils::rolling_median_t<uint64_t> m(2);
+  m.insert(42);
+  ASSERT_EQ(m.median(), 42);
+  m.insert(45);
+  ASSERT_EQ(m.median(), 43);
+  m.insert(49);
+  ASSERT_EQ(m.median(), 47);
+  m.insert(41);
+  ASSERT_EQ(m.median(), 45);
+  m.insert(43);
+  ASSERT_EQ(m.median(), 42);
+  m.insert(40);
+  ASSERT_EQ(m.median(), 41);
+  m.insert(41);
+  ASSERT_EQ(m.median(), 40);
+}
+
+TEST(rolling_median, series)
+{
+  epee::misc_utils::rolling_median_t<uint64_t> m(100);
+  std::vector<uint64_t> v;
+  v.reserve(100);
+  for (int i = 0; i < 10000; ++i)
+  {
+    uint64_t r = rand();
+    v.push_back(r);
+    if (v.size() > 100)
+      v.erase(v.begin());
+    m.insert(r);
+    std::vector<uint64_t> vcopy = v;
+    ASSERT_EQ(m.median(), epee::misc_utils::median(vcopy));
+  }
+}
+
+TEST(rolling_median, clear_whole)
+{
+  epee::misc_utils::rolling_median_t<uint64_t> m(100);
+  std::vector<uint64_t> random, median;
+  random.reserve(10000);
+  median.reserve(10000);
+  for (int i = 0; i < 10000; ++i)
+  {
+    random.push_back(rand());
+    m.insert(random.back());
+    median.push_back(m.median());
+  }
+  m.clear();
+  for (int i = 0; i < 10000; ++i)
+  {
+    m.insert(random[i]);
+    ASSERT_EQ(median[i], m.median());
+  }
+}
+
+TEST(rolling_median, clear_partway)
+{
+  epee::misc_utils::rolling_median_t<uint64_t> m(100);
+  std::vector<uint64_t> random, median;
+  random.reserve(10000);
+  median.reserve(10000);
+  for (int i = 0; i < 10000; ++i)
+  {
+    random.push_back(rand());
+    m.insert(random.back());
+    median.push_back(m.median());
+  }
+  m.clear();
+  for (int i = 10000 - 100; i < 10000; ++i)
+  {
+    m.insert(random[i]);
+  }
+  ASSERT_EQ(median[10000-1], m.median());
+}
+
+TEST(rolling_median, order)
+{
+  epee::misc_utils::rolling_median_t<uint64_t> m(1000);
+  std::vector<uint64_t> random;
+  random.reserve(1000);
+  for (int i = 0; i < 1000; ++i)
+  {
+    random.push_back(rand());
+    m.insert(random.back());
+  }
+  const uint64_t med = m.median();
+
+  std::sort(random.begin(), random.end(), [](uint64_t a, uint64_t b) { return a < b; });
+  m.clear();
+  for (int i = 0; i < 1000; ++i)
+    m.insert(random[i]);
+  ASSERT_EQ(med, m.median());
+
+  std::sort(random.begin(), random.end(), [](uint64_t a, uint64_t b) { return a > b; });
+  m.clear();
+  for (int i = 0; i < 1000; ++i)
+    m.insert(random[i]);
+  ASSERT_EQ(med, m.median());
+
+  std::shuffle(random.begin(), random.end(), std::default_random_engine(crypto::rand<unsigned>()));
+  m.clear();
+  for (int i = 0; i < 1000; ++i)
+    m.insert(random[i]);
+  ASSERT_EQ(med, m.median());
+}
+
+TEST(rolling_median, history_blind)
+{
+  epee::misc_utils::rolling_median_t<uint64_t> m(10);
+
+  uint64_t median = 0;
+  for (int i = 0; i < 1000; ++i)
+  {
+    m.clear();
+    int history_length = 743723 % (i+1);
+    while (history_length--)
+      m.insert(743284 % (i+1));
+    for (int j = 0; j < 10; ++j)
+      m.insert(8924829384 % (j+1));
+    if (i == 0)
+      median = m.median();
+    else
+      ASSERT_EQ(median, m.median());
+  }
+}
+
+TEST(rolling_median, size)
+{
+  epee::misc_utils::rolling_median_t<uint64_t> m(10);
+
+  ASSERT_EQ(m.size(), 0);
+  m.insert(1);
+  ASSERT_EQ(m.size(), 1);
+  m.insert(2);
+  ASSERT_EQ(m.size(), 2);
+  m.clear();
+  ASSERT_EQ(m.size(), 0);
+  for (int i = 0; i < 10; ++i)
+  {
+    m.insert(80 % (i + 1));
+    ASSERT_EQ(m.size(), i + 1);
+  }
+  m.insert(1);
+  ASSERT_EQ(m.size(), 10);
+  m.insert(2);
+  ASSERT_EQ(m.size(), 10);
+  m.clear();
+  ASSERT_EQ(m.size(), 0);
+  m.insert(4);
+  ASSERT_EQ(m.size(), 1);
+  for (int i = 0; i < 1000; ++i)
+  {
+    m.insert(80 % (i + 1));
+    ASSERT_EQ(m.size(), std::min<int>(10, i + 2));
+  }
+}