82414b9111
Summary: Merge branch 'dev' into rename_assert Fix new files. Remove cassert. Reviewers: buda Reviewed By: buda Subscribers: pullbot Differential Revision: https://phabricator.memgraph.io/D66
62 lines
1.5 KiB
C++
62 lines
1.5 KiB
C++
/* Plots the distribution histogram of the xorshift algorithm
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* (spoiler alert: it's pleasingly uniform all the way :D)
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*/
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#include <array>
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#include <atomic>
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#include <cassert>
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#include <iostream>
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#include <thread>
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#include <sys/ioctl.h>
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#include <unistd.h>
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#include "utils/assert.hpp"
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#include "utils/random/xorshift128plus.hpp"
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static thread_local Xorshift128plus rnd;
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static constexpr unsigned B = 1 << 10;
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static constexpr uint64_t K = (uint64_t)(-1) / B;
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static constexpr unsigned M = 4;
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static constexpr size_t N = 1ULL << 34;
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static constexpr size_t per_thread_iters = N / M;
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std::array<std::atomic<unsigned>, B> buckets;
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void generate() {
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for (size_t i = 0; i < per_thread_iters; ++i) buckets[rnd() / K].fetch_add(1);
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}
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int main(void) {
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struct winsize w;
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ioctl(STDOUT_FILENO, TIOCGWINSZ, &w);
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auto bar_len = w.ws_col - 20;
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std::array<std::thread, M> threads;
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for (auto& bucket : buckets) bucket.store(0);
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for (auto& t : threads) t = std::thread([]() { generate(); });
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for (auto& t : threads) t.join();
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auto max = std::accumulate(
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buckets.begin(), buckets.end(), 0u,
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[](auto& acc, auto& x) { return std::max(acc, x.load()); });
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debug_assert(max != 0u, "max is 0.");
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std::cout << std::fixed;
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for (auto& bucket : buckets) {
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auto x = bucket.load();
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auto rel = bar_len * x / max;
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for (size_t i = 0; i < rel; ++i) std::cout << "=";
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std::cout << " " << 100.0 * x / N * B - 100 << "%" << std::endl;
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}
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return 0;
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}
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