luau/tests/DenseHash.test.cpp
2023-01-27 13:28:45 -08:00

79 lines
2 KiB
C++

// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
#include "Luau/DenseHash.h"
#include "doctest.h"
/** So... why are we picking a very specific number to fill the DenseHash(Map|Set)?
*
* That's because that's the count that happens to trigger a specific bug.
*
* DHT determines if it is full by checking whether the count is greater than or equal to 75% of
* its capacity. Once this condition triggers, it rehashes everything by doubling its buffer.
*
* If DHT gets rehashed, the iterator gets invalidated, but it's very important that we support
* the use case of overwriting/merging DHTs while iterating.
*/
TEST_SUITE_BEGIN("DenseHashTests");
TEST_CASE("overwriting_an_existing_field_when_full_shouldnt_rehash")
{
// See the note at the top on why these numbers were chosen.
Luau::DenseHashMap<int, int> m{-1};
for (int i = 0; i < 12; ++i)
m[i] = i;
REQUIRE(m.size() == 12);
for (auto [k, a] : m)
m[k] = a + 1;
for (int i = 0; i < m.size(); ++i)
{
int* a = m.find(i);
REQUIRE(a);
CHECK(i + 1 == *a);
}
}
TEST_CASE("merging_another_map_and_resolve_conflicts_that_also_just_so_happens_to_rehash_while_iterating")
{
// See the note at the top on why these numbers were chosen.
Luau::DenseHashMap<int, int> m1{-1};
for (int i = 0; i < 12; ++i)
m1[i] = i;
Luau::DenseHashMap<int, int> m2{-1};
for (int i = 8; i < 24; ++i)
m2[i] = i;
REQUIRE(m1.size() == 12);
REQUIRE(m2.size() == 16);
for (auto [k, a] : m1)
{
if (int* b = m2.find(k))
m1[k] = a + *b;
}
for (auto [k, a] : m2)
{
if (!m1.find(k))
m1[k] = a;
}
REQUIRE(m1.size() == 24);
for (int i = 0; i < m1.size(); ++i)
{
int* a = m1.find(i);
REQUIRE(a);
if (i < 8 || i >= 12)
CHECK(i == *a);
else
CHECK(i + i == *a);
}
}
TEST_SUITE_END();