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Introduce a Shuffle for FastRandomContext and use it in wallet and coinselection

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This commit is contained in:
Pieter Wuille
2018-10-31 15:42:03 -07:00
parent 8098379be5
commit 3db746beb4
4 changed files with 60 additions and 3 deletions
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34
src/test/random_tests.cpp
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@@ -75,8 +75,42 @@ BOOST_AUTO_TEST_CASE(stdrandom_test)
for (int j = 1; j <= 10; ++j) {
BOOST_CHECK(std::find(test.begin(), test.end(), j) != test.end());
}
Shuffle(test.begin(), test.end(), ctx);
for (int j = 1; j <= 10; ++j) {
BOOST_CHECK(std::find(test.begin(), test.end(), j) != test.end());
}
}
}
/** Test that Shuffle reaches every permutation with equal probability. */
BOOST_AUTO_TEST_CASE(shuffle_stat_test)
{
FastRandomContext ctx(true);
uint32_t counts[5 * 5 * 5 * 5 * 5] = {0};
for (int i = 0; i < 12000; ++i) {
int data[5] = {0, 1, 2, 3, 4};
Shuffle(std::begin(data), std::end(data), ctx);
int pos = data[0] + data[1] * 5 + data[2] * 25 + data[3] * 125 + data[4] * 625;
++counts[pos];
}
unsigned int sum = 0;
double chi_score = 0.0;
for (int i = 0; i < 5 * 5 * 5 * 5 * 5; ++i) {
int i1 = i % 5, i2 = (i / 5) % 5, i3 = (i / 25) % 5, i4 = (i / 125) % 5, i5 = i / 625;
uint32_t count = counts[i];
if (i1 == i2 || i1 == i3 || i1 == i4 || i1 == i5 || i2 == i3 || i2 == i4 || i2 == i5 || i3 == i4 || i3 == i5 || i4 == i5) {
BOOST_CHECK(count == 0);
} else {
chi_score += ((count - 100.0) * (count - 100.0)) / 100.0;
BOOST_CHECK(count > 50);
BOOST_CHECK(count < 150);
sum += count;
}
}
BOOST_CHECK(chi_score > 58.1411); // 99.9999% confidence interval
BOOST_CHECK(chi_score < 210.275);
BOOST_CHECK_EQUAL(sum, 12000);
}
BOOST_AUTO_TEST_SUITE_END()