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Set max epoch number constant
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Define the maximum value of epoch number this Ethash library supports.
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@chfast
chfast committed Nov 10, 2021
1 parent a725a2f commit 7731aa3
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Showing 5 changed files with 67 additions and 26 deletions.
3 changes: 3 additions & 0 deletions include/ethash/ethash.h
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,9 @@ extern "C" {
#define ETHASH_FULL_DATASET_ITEM_SIZE 128
#define ETHASH_NUM_DATASET_ACCESSES 64

/// The maximum epoch number supported by this implementation.
#define ETHASH_MAX_EPOCH_NUMBER 32639

/** Ethash error codes. */
enum ethash_errc
{
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11 changes: 7 additions & 4 deletions include/ethash/ethash.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -37,10 +37,13 @@ namespace ethash
{
constexpr auto revision = ETHASH_REVISION;

static constexpr int epoch_length = ETHASH_EPOCH_LENGTH;
static constexpr int light_cache_item_size = ETHASH_LIGHT_CACHE_ITEM_SIZE;
static constexpr int full_dataset_item_size = ETHASH_FULL_DATASET_ITEM_SIZE;
static constexpr int num_dataset_accesses = ETHASH_NUM_DATASET_ACCESSES;
constexpr int epoch_length = ETHASH_EPOCH_LENGTH;
constexpr int light_cache_item_size = ETHASH_LIGHT_CACHE_ITEM_SIZE;
constexpr int full_dataset_item_size = ETHASH_FULL_DATASET_ITEM_SIZE;
constexpr int num_dataset_accesses = ETHASH_NUM_DATASET_ACCESSES;

/// The maximum epoch number supported by this implementation.
constexpr int max_epoch_number = ETHASH_MAX_EPOCH_NUMBER;

using epoch_context = ethash_epoch_context;
using epoch_context_full = ethash_epoch_context_full;
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25 changes: 16 additions & 9 deletions lib/ethash/ethash.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -57,8 +57,6 @@ inline hash512 bitwise_xor(const hash512& x, const hash512& y) noexcept

int find_epoch_number(const hash256& seed) noexcept
{
static constexpr int num_tries = 30000; // Divisible by 16.

// Thread-local cache of the last search.
static thread_local int cached_epoch_number = 0;
static thread_local hash256 cached_seed = {};
Expand All @@ -82,7 +80,7 @@ int find_epoch_number(const hash256& seed) noexcept

// Search for matching seed starting from epoch 0.
s = {};
for (int i = 0; i < num_tries; ++i)
for (int i = 0; i <= max_epoch_number; ++i)
{
if (s.word32s[0] == seed_part)
{
Expand Down Expand Up @@ -135,6 +133,9 @@ epoch_context_full* create_epoch_context(
static_assert(sizeof(epoch_context_full) < sizeof(hash512), "epoch_context too big");
static constexpr size_t context_alloc_size = sizeof(hash512);

if (epoch_number > max_epoch_number)
return nullptr;

const int light_cache_num_items = calculate_light_cache_num_items(epoch_number);
const int full_dataset_num_items = calculate_full_dataset_num_items(epoch_number);
const size_t light_cache_size = get_light_cache_size(light_cache_num_items);
Expand Down Expand Up @@ -428,29 +429,35 @@ ethash_hash256 ethash_calculate_epoch_seed(int epoch_number) noexcept

int ethash_calculate_light_cache_num_items(int epoch_number) noexcept
{
static constexpr int item_size = sizeof(hash512);
static constexpr int num_items_init = light_cache_init_size / item_size;
static constexpr int num_items_growth = light_cache_growth / item_size;
constexpr int item_size = sizeof(hash512);
constexpr int num_items_init = light_cache_init_size / item_size;
constexpr int num_items_growth = light_cache_growth / item_size;
static_assert(
light_cache_init_size % item_size == 0, "light_cache_init_size not multiple of item size");
static_assert(
light_cache_growth % item_size == 0, "light_cache_growth not multiple of item size");

if (epoch_number > max_epoch_number)
return 0;

int num_items_upper_bound = num_items_init + epoch_number * num_items_growth;
int num_items = ethash_find_largest_prime(num_items_upper_bound);
return num_items;
}

int ethash_calculate_full_dataset_num_items(int epoch_number) noexcept
{
static constexpr int item_size = sizeof(hash1024);
static constexpr int num_items_init = full_dataset_init_size / item_size;
static constexpr int num_items_growth = full_dataset_growth / item_size;
constexpr int item_size = sizeof(hash1024);
constexpr int num_items_init = full_dataset_init_size / item_size;
constexpr int num_items_growth = full_dataset_growth / item_size;
static_assert(full_dataset_init_size % item_size == 0,
"full_dataset_init_size not multiple of item size");
static_assert(
full_dataset_growth % item_size == 0, "full_dataset_growth not multiple of item size");

if (epoch_number > max_epoch_number)
return 0;

int num_items_upper_bound = num_items_init + epoch_number * num_items_growth;
int num_items = ethash_find_largest_prime(num_items_upper_bound);
return num_items;
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8 changes: 6 additions & 2 deletions test/benchmarks/ethash_benchmarks.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,9 @@ static void calculate_light_cache_num_items(benchmark::State& state)
benchmark::DoNotOptimize(&answer);
}
}
BENCHMARK(calculate_light_cache_num_items)->Arg(32638)->Arg(32639);
BENCHMARK(calculate_light_cache_num_items)
->Arg(ethash::max_epoch_number - 1)
->Arg(ethash::max_epoch_number);

static void calculate_full_dataset_num_items(benchmark::State& state)
{
Expand All @@ -32,7 +34,9 @@ static void calculate_full_dataset_num_items(benchmark::State& state)
benchmark::DoNotOptimize(&answer);
}
}
BENCHMARK(calculate_full_dataset_num_items)->Arg(32638)->Arg(32639);
BENCHMARK(calculate_full_dataset_num_items)
->Arg(ethash::max_epoch_number - 1)
->Arg(ethash::max_epoch_number);


static void seed(benchmark::State& state)
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46 changes: 35 additions & 11 deletions test/unittests/test_ethash.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -190,7 +190,9 @@ static dataset_size_test_case dataset_size_test_cases[] = {
{1956, 273153856, 17481857408},
{2047, 285081536, 18245220736},
{30000, 3948936512, 252731976832},
{32639, 4294836032, 274869514624},
{max_epoch_number, 4294836032, 274'869'514'624},
{max_epoch_number + 1, 0, 0},
{max_epoch_number * 2, 0, 0},
};

TEST(ethash, light_cache_size)
Expand Down Expand Up @@ -220,21 +222,23 @@ struct epoch_seed_test_case
const char* const epoch_seed_hex;
};

static epoch_seed_test_case epoch_seed_test_cases[] = {
constexpr epoch_seed_test_case epoch_seed_test_cases[] = {
{0, "0000000000000000000000000000000000000000000000000000000000000000"},
{1, "290decd9548b62a8d60345a988386fc84ba6bc95484008f6362f93160ef3e563"},
{171, "a9b0e0c9aca72c07ba06b5bbdae8b8f69e61878301508473379bb4f71807d707"},
{2048, "20a7678ca7b50829183baac2e1e3c43fa3c4bcbc171b11cf5a9f30bebd172920"},
{29998, "1222b1faed7f93098f8ae498621fb3479805a664b70186063861c46596c66164"},
{29999, "ee1d0f61b054dff0f3025ebba821d405c8dc19a983e582e9fa5436fc3e7a07d8"},
{max_epoch_number - 1, "9472a82f992649315e3977120843a5a246e375715bd70ee98b3dd77c63154e99"},
{max_epoch_number, "09b435f2d92d0ddee038c379be8db1f895c904282e9ceb790f519a6aa3f83810"},
};

TEST(ethash, calculate_epoch_seed)
{
for (auto& t : epoch_seed_test_cases)
{
const hash256 epoch_seed = calculate_epoch_seed(t.epoch_number);
EXPECT_EQ(epoch_seed, to_hash256(t.epoch_seed_hex));
EXPECT_EQ(to_hex(epoch_seed), t.epoch_seed_hex);
}
}

Expand Down Expand Up @@ -268,19 +272,30 @@ TEST(ethash, find_epoch_number_double_descending)
TEST(ethash, find_epoch_number_sequential)
{
hash256 seed = {};
for (int i = 0; i < 30000; ++i)
for (int i = 0; i < max_epoch_number; ++i)
{
auto e = find_epoch_number(seed);
EXPECT_EQ(e, i);
seed = keccak256(seed);
}
}

TEST(ethash, find_epoch_number_max)
{
const auto seed_max = to_hash256(epoch_seed_test_cases[7].epoch_seed_hex);
const auto seed_out_of_range = keccak256(seed_max);

find_epoch_number({}); // Reset cache.
EXPECT_EQ(find_epoch_number(seed_out_of_range), -1);
find_epoch_number({}); // Reset cache.
EXPECT_EQ(find_epoch_number(seed_max), max_epoch_number);
}

TEST(ethash, find_epoch_number_sequential_gap)
{
constexpr int start_epoch = 200;
hash256 seed = calculate_epoch_seed(start_epoch);
for (int i = start_epoch; i < 30000; ++i)
for (int i = start_epoch; i < max_epoch_number; ++i)
{
auto e = find_epoch_number(seed);
EXPECT_EQ(e, i);
Expand Down Expand Up @@ -315,7 +330,7 @@ TEST(ethash, find_epoch_number_invalid)

TEST(ethash, find_epoch_number_epoch_too_high)
{
hash256 seed = calculate_epoch_seed(30000);
hash256 seed = calculate_epoch_seed(max_epoch_number + 1);
int epoch = find_epoch_number(seed);
EXPECT_EQ(epoch, -1);
}
Expand All @@ -324,7 +339,7 @@ TEST(ethash_multithreaded, find_epoch_number_sequential)
{
auto fn = [] {
hash256 seed = {};
for (int i = 0; i < 30000; ++i)
for (int i = 0; i < max_epoch_number; ++i)
{
auto e = find_epoch_number(seed);
EXPECT_EQ(e, i);
Expand All @@ -348,6 +363,9 @@ TEST(ethash, get_epoch_number)
EXPECT_EQ(get_epoch_number(30001), 1);
EXPECT_EQ(get_epoch_number(30002), 1);
EXPECT_EQ(get_epoch_number(5000000), 166);
EXPECT_EQ(get_epoch_number(max_epoch_number * epoch_length), max_epoch_number);
constexpr auto max_block = max_epoch_number * epoch_length + epoch_length - 1;
EXPECT_EQ(get_epoch_number(max_block), max_epoch_number);
}

TEST(ethash, light_cache)
Expand Down Expand Up @@ -462,7 +480,10 @@ TEST(ethash, fake_dataset_items)
{740620450,
"7e4a3533ef6f0d9fa7e41b8304e08fe9e52556334cad0cc861337bd1155bbea211cf0b0198b4f08567cc47fcc964bbbdfb2f851437da1edba7c6f4bd3fd61a3a",
"f20969bd0407bb76560e7c099224a1ea185214808950519fafdcd02ba2874e9b4ebf1797cafb3b80e903b13a87ddac5d54d67ed58acf49bb12e03b81eb6c99af"},
{4294967295,
{2147418082, // Max index for epoch 32639.
"a79eaa61a5c2256eb3bf9c78a2b6509929780d8826d7a7d1324328ab786ca9c23fc1437e1efb432ab823c5d5448b4183893d16168aebe21470e3515104eab67f",
"496baeac6ea83fdd5a6a20827029ddd73d1be507dc7f210c2aed29f0757eefea72ab7e4c92aab9ee34ed46027bdc9918e047b0f845c7fbbd254b8014141c7605"},
{0x7fffffff, // Max allowed index value.
"21471504c1f31007c14acd107a8ade1aad6c2a6c2ad879b3aca3b12517105483502d0e3e902acf3b128d294c0a69f2cc199bf8813be1f8bb4b5625822b70ec09",
"8e4fdb5dc602598f10a42b5061132eec05299380db872a3caf04aa21e3d4970350394dfbd58c5ab54571b1be0cc9001d788c6b14cbf003d7decc2aaef1232b8c"},
};
Expand Down Expand Up @@ -527,9 +548,12 @@ TEST(ethash, dataset_items_epoch13)
{740620450,
"df0c2e2f4df033a64b1bcd207c30c7ce48c7d8ca8edd1284c87a91d54372ed0cb513d1876b1dbef6fc06c496941039cba6c50676596d6379152689d9841c97e4",
"357bacef5baf4687c87e7ff07d5ab104ce39badcf9633c22ee31c3c3de0887b296f9385ea27573cb94bc3423cc39ab2a733be97a98e860290c31e94f03f39814"},
{4294967295,
"11fab5bafdf0e29f199cad053a542f777fcd8b4fb8a0203bf720b9a01718e8c76d0e374e979ebf0e1faf8ce992638a5e92ea8be8000c47e8307acad261df1abb",
"164ff9a893a162319f9ccb4294e33fb6ae50ea05d02a753fd4797662676c1fad6d70b11db6d4aa0298d6aa695c9be8dea3dad70f953368cb11b283eb145d17e3"},
{2147418082, // Max index for epoch 32639.
"9705a12d9f1a193ffea9b9c6603b8d17315896b84ea6649e613fec1578c867535e6bbfd71cb18ce0c0dd6ca8051f7bfb5cfa2d89b29d1bf25a0b36ae57505844",
"c2f3475bf52ec727a0b684d9fbc5ce9234331abc585c383e87fa70e8c860819b35c12e6173df081f3f84bea218633ad54c9da6051ba90efc3985e887530cb89e"},
{0x7fffffff, // Max allowed index value.
"d463d63e393e6ccc31b240d3d12301a14e0410377657b0554d6041541303c2ddc8ec026432adf73311b56de486f6fdca808f87f3824587b413a4e4f7a571d046",
"9e15d844f137ae66e7fc23934cc51d53a36ec28a5d1a246d50773471252ae9ea30fe20e817434e771bbf77577899cf2cce8de11578b925a12af2ad9dd316f0ec"},
};
// clang-format on

Expand Down

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