863f55dc2f
Summary: Labels implementation Reviewers: buda, teon.banek Reviewed By: buda, teon.banek Subscribers: pullbot Differential Revision: https://phabricator.memgraph.io/D201
62 lines
1.4 KiB
C++
62 lines
1.4 KiB
C++
/* Plots the distribution histogram of the fast_binomial algorithm
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* (spoiler alert: it's pleasingly (1/2)^N 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 <iomanip>
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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/random/fast_binomial.hpp"
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static constexpr unsigned B = 24;
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static thread_local FastBinomial<> rnd;
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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<uint64_t>, B> buckets;
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void generate() {
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for (size_t i = 0; i < per_thread_iters; ++i)
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buckets[rnd(B) - 1].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(), (uint64_t)0,
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[](auto &acc, auto &x) { return std::max(acc, x.load()); });
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std::cout << std::fixed;
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for (size_t i = 0; i < buckets.size(); ++i) {
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auto x = buckets[i].load();
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auto rel = bar_len * x / max;
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std::cout << std::setw(2) << i + 1 << " ";
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for (size_t i = 0; i < rel; ++i) std::cout << "=";
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std::cout << " " << 100 * (double)x / N << "%" << std::endl;
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}
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return 0;
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}
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