09f71cb40d
Adds a generic C++ based caching library to support material external modules. This is a template based library which means there is nothing to build or link. The only modification is to the CMakeLists.txt file to enable integration with FreeCAD, Original source: https://github.com/goldsborough/lru-cache
77 lines
2.8 KiB
C++
77 lines
2.8 KiB
C++
/// The MIT License (MIT)
|
|
/// Copyright (c) 2016 Peter Goldsborough
|
|
///
|
|
/// 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.
|
|
|
|
#include <iostream>
|
|
|
|
#include "lru/lru.hpp"
|
|
|
|
using Cache = LRU::Cache<std::uint64_t, std::uint64_t>;
|
|
|
|
std::uint64_t fibonacci(std::uint64_t n, Cache& cache) {
|
|
if (n < 2) return 1;
|
|
|
|
// We std::uint64_ternally keep track of the last accessed key, meaning a
|
|
// `contains(key)` + `lookup(key)` sequence will involve only a single hash
|
|
// table lookup.
|
|
if (cache.contains(n)) return cache[n];
|
|
|
|
auto value = fibonacci(n - 1, cache) + fibonacci(n - 2, cache);
|
|
|
|
// Caches are 100% move-aware and we have implemented
|
|
// `unordered_map` style emplacement and insertion.
|
|
cache.emplace(n, value);
|
|
|
|
return value;
|
|
}
|
|
|
|
std::uint64_t fibonacci(std::uint64_t n) {
|
|
// Use a capacity of 100 (after 100 insertions, the next insertion will evict
|
|
// the least-recently inserted element). The default capacity is 128. Note
|
|
// that for fibonacci, a capacity of 2 is sufficient (and ideal).
|
|
Cache cache(100);
|
|
cache.monitor(2, 3, 4, 5);
|
|
auto value = fibonacci(n, cache);
|
|
|
|
for (auto i : {2, 3, 4, 5}) {
|
|
auto stats = cache.stats().stats_for(i);
|
|
// clang-format off
|
|
std::cout << "Statistics for " << i << ": "
|
|
<< stats.hits << " hit(s), "
|
|
<< stats.misses << " miss(es)."
|
|
<< std::endl;
|
|
}
|
|
|
|
// You'll notice we'll always have n - 1 misses, for each time we access
|
|
// one of the numbers in [0, n] for the first time.
|
|
std::cout << "Overall: "
|
|
<< cache.stats().total_hits() << " hit(s), "
|
|
<< cache.stats().total_misses() << " miss(es)."
|
|
<< std::endl;
|
|
// clang-format on
|
|
|
|
return value;
|
|
}
|
|
|
|
auto main() -> int {
|
|
// The last number that fits into a 64 bit unsigned number
|
|
std::cout << fibonacci(92) << std::endl;
|
|
}
|