1 /* 2 * Copyright (C) 2017-2019 Savoir-faire Linux Inc. 3 * Author : Adrien Béraud <adrien.beraud@savoirfairelinux.com> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 3 of the License, or 8 * (at your option) any later version. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program. If not, see <https://www.gnu.org/licenses/>. 17 */ 18 19 #pragma once 20 21 #include "utils.h" 22 #include <queue> 23 24 namespace dht { 25 26 template<size_t Quota, unsigned long Period=1> 27 class RateLimiter { 28 public: 29 /** Clear outdated records and return current quota usage */ maintain(const time_point & now)30 size_t maintain(const time_point& now) { 31 auto limit = now - std::chrono::seconds(Period); 32 while (not records.empty() and records.front() < limit) 33 records.pop(); 34 return records.size(); 35 } 36 /** Return false if quota is reached, insert record and return true otherwise. */ limit(const time_point & now)37 bool limit(const time_point& now) { 38 if (maintain(now) >= Quota) 39 return false; 40 records.emplace(now); 41 return true; 42 } empty()43 bool empty() const { 44 return records.empty(); 45 } 46 private: 47 std::queue<time_point> records {}; 48 }; 49 50 } 51