mirror of
https://github.com/ncblakely/GiantsTools
synced 2024-11-05 06:45:37 +01:00
405 lines
12 KiB
C++
405 lines
12 KiB
C++
/**
|
|
* MIT License
|
|
*
|
|
* Copyright (c) 2018 Thibaut Goetghebuer-Planchon <tessil@gmx.com>
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
* of this software and associated documentation files (the "Software"), to deal
|
|
* in the Software without restriction, including without limitation the rights
|
|
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
* copies of the Software, and to permit persons to whom the Software is
|
|
* furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be included in
|
|
* all copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
|
|
* SOFTWARE.
|
|
*/
|
|
#ifndef TSL_HOPSCOTCH_GROWTH_POLICY_H
|
|
#define TSL_HOPSCOTCH_GROWTH_POLICY_H
|
|
|
|
#include <algorithm>
|
|
#include <array>
|
|
#include <climits>
|
|
#include <cmath>
|
|
#include <cstddef>
|
|
#include <cstdint>
|
|
#include <iterator>
|
|
#include <limits>
|
|
#include <ratio>
|
|
#include <stdexcept>
|
|
|
|
/**
|
|
* Only activate tsl_hh_assert if TSL_DEBUG is defined.
|
|
* This way we avoid the performance hit when NDEBUG is not defined with assert
|
|
* as tsl_hh_assert is used a lot (people usually compile with "-O3" and not
|
|
* "-O3 -DNDEBUG").
|
|
*/
|
|
#ifdef TSL_DEBUG
|
|
#define tsl_hh_assert(expr) assert(expr)
|
|
#else
|
|
#define tsl_hh_assert(expr) (static_cast<void>(0))
|
|
#endif
|
|
|
|
/**
|
|
* If exceptions are enabled, throw the exception passed in parameter, otherwise
|
|
* call std::terminate.
|
|
*/
|
|
#if (defined(__cpp_exceptions) || defined(__EXCEPTIONS) || \
|
|
(defined(_MSC_VER) && defined(_CPPUNWIND))) && \
|
|
!defined(TSL_NO_EXCEPTIONS)
|
|
#define TSL_HH_THROW_OR_TERMINATE(ex, msg) throw ex(msg)
|
|
#else
|
|
#define TSL_HH_NO_EXCEPTIONS
|
|
#ifdef NDEBUG
|
|
#define TSL_HH_THROW_OR_TERMINATE(ex, msg) std::terminate()
|
|
#else
|
|
#include <iostream>
|
|
#define TSL_HH_THROW_OR_TERMINATE(ex, msg) \
|
|
do { \
|
|
std::cerr << msg << std::endl; \
|
|
std::terminate(); \
|
|
} while (0)
|
|
#endif
|
|
#endif
|
|
|
|
namespace tsl {
|
|
namespace hh {
|
|
|
|
/**
|
|
* Grow the hash table by a factor of GrowthFactor keeping the bucket count to a
|
|
* power of two. It allows the table to use a mask operation instead of a modulo
|
|
* operation to map a hash to a bucket.
|
|
*
|
|
* GrowthFactor must be a power of two >= 2.
|
|
*/
|
|
template <std::size_t GrowthFactor>
|
|
class power_of_two_growth_policy {
|
|
public:
|
|
/**
|
|
* Called on the hash table creation and on rehash. The number of buckets for
|
|
* the table is passed in parameter. This number is a minimum, the policy may
|
|
* update this value with a higher value if needed (but not lower).
|
|
*
|
|
* If 0 is given, min_bucket_count_in_out must still be 0 after the policy
|
|
* creation and bucket_for_hash must always return 0 in this case.
|
|
*/
|
|
explicit power_of_two_growth_policy(std::size_t& min_bucket_count_in_out) {
|
|
if (min_bucket_count_in_out > max_bucket_count()) {
|
|
TSL_HH_THROW_OR_TERMINATE(std::length_error,
|
|
"The hash table exceeds its maximum size.");
|
|
}
|
|
|
|
if (min_bucket_count_in_out > 0) {
|
|
min_bucket_count_in_out =
|
|
round_up_to_power_of_two(min_bucket_count_in_out);
|
|
m_mask = min_bucket_count_in_out - 1;
|
|
} else {
|
|
m_mask = 0;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Return the bucket [0, bucket_count()) to which the hash belongs.
|
|
* If bucket_count() is 0, it must always return 0.
|
|
*/
|
|
std::size_t bucket_for_hash(std::size_t hash) const noexcept {
|
|
return hash & m_mask;
|
|
}
|
|
|
|
/**
|
|
* Return the bucket count to use when the bucket array grows on rehash.
|
|
*/
|
|
std::size_t next_bucket_count() const {
|
|
if ((m_mask + 1) > max_bucket_count() / GrowthFactor) {
|
|
TSL_HH_THROW_OR_TERMINATE(std::length_error,
|
|
"The hash table exceeds its maximum size.");
|
|
}
|
|
|
|
return (m_mask + 1) * GrowthFactor;
|
|
}
|
|
|
|
/**
|
|
* Return the maximum number of buckets supported by the policy.
|
|
*/
|
|
std::size_t max_bucket_count() const {
|
|
// Largest power of two.
|
|
return (std::numeric_limits<std::size_t>::max() / 2) + 1;
|
|
}
|
|
|
|
/**
|
|
* Reset the growth policy as if it was created with a bucket count of 0.
|
|
* After a clear, the policy must always return 0 when bucket_for_hash is
|
|
* called.
|
|
*/
|
|
void clear() noexcept { m_mask = 0; }
|
|
|
|
private:
|
|
static std::size_t round_up_to_power_of_two(std::size_t value) {
|
|
if (is_power_of_two(value)) {
|
|
return value;
|
|
}
|
|
|
|
if (value == 0) {
|
|
return 1;
|
|
}
|
|
|
|
--value;
|
|
for (std::size_t i = 1; i < sizeof(std::size_t) * CHAR_BIT; i *= 2) {
|
|
value |= value >> i;
|
|
}
|
|
|
|
return value + 1;
|
|
}
|
|
|
|
static constexpr bool is_power_of_two(std::size_t value) {
|
|
return value != 0 && (value & (value - 1)) == 0;
|
|
}
|
|
|
|
private:
|
|
static_assert(is_power_of_two(GrowthFactor) && GrowthFactor >= 2,
|
|
"GrowthFactor must be a power of two >= 2.");
|
|
|
|
std::size_t m_mask;
|
|
};
|
|
|
|
/**
|
|
* Grow the hash table by GrowthFactor::num / GrowthFactor::den and use a modulo
|
|
* to map a hash to a bucket. Slower but it can be useful if you want a slower
|
|
* growth.
|
|
*/
|
|
template <class GrowthFactor = std::ratio<3, 2>>
|
|
class mod_growth_policy {
|
|
public:
|
|
explicit mod_growth_policy(std::size_t& min_bucket_count_in_out) {
|
|
if (min_bucket_count_in_out > max_bucket_count()) {
|
|
TSL_HH_THROW_OR_TERMINATE(std::length_error,
|
|
"The hash table exceeds its maximum size.");
|
|
}
|
|
|
|
if (min_bucket_count_in_out > 0) {
|
|
m_mod = min_bucket_count_in_out;
|
|
} else {
|
|
m_mod = 1;
|
|
}
|
|
}
|
|
|
|
std::size_t bucket_for_hash(std::size_t hash) const noexcept {
|
|
return hash % m_mod;
|
|
}
|
|
|
|
std::size_t next_bucket_count() const {
|
|
if (m_mod == max_bucket_count()) {
|
|
TSL_HH_THROW_OR_TERMINATE(std::length_error,
|
|
"The hash table exceeds its maximum size.");
|
|
}
|
|
|
|
const double next_bucket_count =
|
|
std::ceil(double(m_mod) * REHASH_SIZE_MULTIPLICATION_FACTOR);
|
|
if (!std::isnormal(next_bucket_count)) {
|
|
TSL_HH_THROW_OR_TERMINATE(std::length_error,
|
|
"The hash table exceeds its maximum size.");
|
|
}
|
|
|
|
if (next_bucket_count > double(max_bucket_count())) {
|
|
return max_bucket_count();
|
|
} else {
|
|
return std::size_t(next_bucket_count);
|
|
}
|
|
}
|
|
|
|
std::size_t max_bucket_count() const { return MAX_BUCKET_COUNT; }
|
|
|
|
void clear() noexcept { m_mod = 1; }
|
|
|
|
private:
|
|
static constexpr double REHASH_SIZE_MULTIPLICATION_FACTOR =
|
|
1.0 * GrowthFactor::num / GrowthFactor::den;
|
|
static const std::size_t MAX_BUCKET_COUNT =
|
|
std::size_t(double(std::numeric_limits<std::size_t>::max() /
|
|
REHASH_SIZE_MULTIPLICATION_FACTOR));
|
|
|
|
static_assert(REHASH_SIZE_MULTIPLICATION_FACTOR >= 1.1,
|
|
"Growth factor should be >= 1.1.");
|
|
|
|
std::size_t m_mod;
|
|
};
|
|
|
|
namespace detail {
|
|
|
|
#if SIZE_MAX >= ULLONG_MAX
|
|
#define TSL_HH_NB_PRIMES 51
|
|
#elif SIZE_MAX >= ULONG_MAX
|
|
#define TSL_HH_NB_PRIMES 40
|
|
#else
|
|
#define TSL_HH_NB_PRIMES 23
|
|
#endif
|
|
|
|
static constexpr const std::array<std::size_t, TSL_HH_NB_PRIMES> PRIMES = {{
|
|
1u,
|
|
5u,
|
|
17u,
|
|
29u,
|
|
37u,
|
|
53u,
|
|
67u,
|
|
79u,
|
|
97u,
|
|
131u,
|
|
193u,
|
|
257u,
|
|
389u,
|
|
521u,
|
|
769u,
|
|
1031u,
|
|
1543u,
|
|
2053u,
|
|
3079u,
|
|
6151u,
|
|
12289u,
|
|
24593u,
|
|
49157u,
|
|
#if SIZE_MAX >= ULONG_MAX
|
|
98317ul,
|
|
196613ul,
|
|
393241ul,
|
|
786433ul,
|
|
1572869ul,
|
|
3145739ul,
|
|
6291469ul,
|
|
12582917ul,
|
|
25165843ul,
|
|
50331653ul,
|
|
100663319ul,
|
|
201326611ul,
|
|
402653189ul,
|
|
805306457ul,
|
|
1610612741ul,
|
|
3221225473ul,
|
|
4294967291ul,
|
|
#endif
|
|
#if SIZE_MAX >= ULLONG_MAX
|
|
6442450939ull,
|
|
12884901893ull,
|
|
25769803751ull,
|
|
51539607551ull,
|
|
103079215111ull,
|
|
206158430209ull,
|
|
412316860441ull,
|
|
824633720831ull,
|
|
1649267441651ull,
|
|
3298534883309ull,
|
|
6597069766657ull,
|
|
#endif
|
|
}};
|
|
|
|
template <unsigned int IPrime>
|
|
static constexpr std::size_t mod(std::size_t hash) {
|
|
return hash % PRIMES[IPrime];
|
|
}
|
|
|
|
// MOD_PRIME[iprime](hash) returns hash % PRIMES[iprime]. This table allows for
|
|
// faster modulo as the compiler can optimize the modulo code better with a
|
|
// constant known at the compilation.
|
|
static constexpr const std::array<std::size_t (*)(std::size_t),
|
|
TSL_HH_NB_PRIMES>
|
|
MOD_PRIME = {{
|
|
&mod<0>, &mod<1>, &mod<2>, &mod<3>, &mod<4>, &mod<5>,
|
|
&mod<6>, &mod<7>, &mod<8>, &mod<9>, &mod<10>, &mod<11>,
|
|
&mod<12>, &mod<13>, &mod<14>, &mod<15>, &mod<16>, &mod<17>,
|
|
&mod<18>, &mod<19>, &mod<20>, &mod<21>, &mod<22>,
|
|
#if SIZE_MAX >= ULONG_MAX
|
|
&mod<23>, &mod<24>, &mod<25>, &mod<26>, &mod<27>, &mod<28>,
|
|
&mod<29>, &mod<30>, &mod<31>, &mod<32>, &mod<33>, &mod<34>,
|
|
&mod<35>, &mod<36>, &mod<37>, &mod<38>, &mod<39>,
|
|
#endif
|
|
#if SIZE_MAX >= ULLONG_MAX
|
|
&mod<40>, &mod<41>, &mod<42>, &mod<43>, &mod<44>, &mod<45>,
|
|
&mod<46>, &mod<47>, &mod<48>, &mod<49>, &mod<50>,
|
|
#endif
|
|
}};
|
|
|
|
} // namespace detail
|
|
|
|
/**
|
|
* Grow the hash table by using prime numbers as bucket count. Slower than
|
|
* tsl::hh::power_of_two_growth_policy in general but will probably distribute
|
|
* the values around better in the buckets with a poor hash function.
|
|
*
|
|
* To allow the compiler to optimize the modulo operation, a lookup table is
|
|
* used with constant primes numbers.
|
|
*
|
|
* With a switch the code would look like:
|
|
* \code
|
|
* switch(iprime) { // iprime is the current prime of the hash table
|
|
* case 0: hash % 5ul;
|
|
* break;
|
|
* case 1: hash % 17ul;
|
|
* break;
|
|
* case 2: hash % 29ul;
|
|
* break;
|
|
* ...
|
|
* }
|
|
* \endcode
|
|
*
|
|
* Due to the constant variable in the modulo the compiler is able to optimize
|
|
* the operation by a series of multiplications, substractions and shifts.
|
|
*
|
|
* The 'hash % 5' could become something like 'hash - (hash * 0xCCCCCCCD) >> 34)
|
|
* * 5' in a 64 bits environment.
|
|
*/
|
|
class prime_growth_policy {
|
|
public:
|
|
explicit prime_growth_policy(std::size_t& min_bucket_count_in_out) {
|
|
auto it_prime = std::lower_bound(
|
|
detail::PRIMES.begin(), detail::PRIMES.end(), min_bucket_count_in_out);
|
|
if (it_prime == detail::PRIMES.end()) {
|
|
TSL_HH_THROW_OR_TERMINATE(std::length_error,
|
|
"The hash table exceeds its maximum size.");
|
|
}
|
|
|
|
m_iprime = static_cast<unsigned int>(
|
|
std::distance(detail::PRIMES.begin(), it_prime));
|
|
if (min_bucket_count_in_out > 0) {
|
|
min_bucket_count_in_out = *it_prime;
|
|
} else {
|
|
min_bucket_count_in_out = 0;
|
|
}
|
|
}
|
|
|
|
std::size_t bucket_for_hash(std::size_t hash) const noexcept {
|
|
return detail::MOD_PRIME[m_iprime](hash);
|
|
}
|
|
|
|
std::size_t next_bucket_count() const {
|
|
if (m_iprime + 1 >= detail::PRIMES.size()) {
|
|
TSL_HH_THROW_OR_TERMINATE(std::length_error,
|
|
"The hash table exceeds its maximum size.");
|
|
}
|
|
|
|
return detail::PRIMES[m_iprime + 1];
|
|
}
|
|
|
|
std::size_t max_bucket_count() const { return detail::PRIMES.back(); }
|
|
|
|
void clear() noexcept { m_iprime = 0; }
|
|
|
|
private:
|
|
unsigned int m_iprime;
|
|
|
|
static_assert(std::numeric_limits<decltype(m_iprime)>::max() >=
|
|
detail::PRIMES.size(),
|
|
"The type of m_iprime is not big enough.");
|
|
};
|
|
|
|
} // namespace hh
|
|
} // namespace tsl
|
|
|
|
#endif
|