111 lines
2.5 KiB
C++
111 lines
2.5 KiB
C++
#pragma once
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#include <chrono>
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#include <deque>
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#include "common.hpp"
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#include "components/logger.hpp"
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#include "utils/scope.hpp"
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LEMONBUDDY_NS
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namespace throttle_util {
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using timewindow = chrono::duration<double, std::milli>;
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using timepoint_clock = chrono::high_resolution_clock;
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using timepoint = timepoint_clock::time_point;
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using queue = std::deque<timepoint>;
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using limit = size_t;
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namespace strategy {
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/**
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* Only pass events when there are slots available
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*/
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struct try_once_or_leave_yolo {
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bool operator()(queue& q, limit l, timewindow t) {
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if (q.size() >= l)
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return false;
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q.emplace_back(timepoint_clock::now());
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return true;
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}
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};
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/**
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* If no slots are available, wait the required
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* amount of time for a slot to become available
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* then let the event pass
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*/
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struct wait_patiently_by_the_door {
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bool operator()(queue& q, limit l, timewindow t) {
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auto now = timepoint_clock::now();
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q.emplace_back(now);
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if (q.size() >= l) {
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this_thread::sleep_for(now - q.front());
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}
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return true;
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}
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};
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}
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/**
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* Throttle events within a set window of time
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*
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* Example usage:
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* @code cpp
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* auto t = throttle_util::make_throttler(2, 1s);
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* if (t->passthrough())
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* ...
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* @endcode
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*/
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class event_throttler {
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public:
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/**
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* Construct throttler
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*/
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explicit event_throttler(int limit, timewindow timewindow)
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: m_limit(limit), m_timewindow(timewindow) {}
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/**
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* Check if event is allowed to pass
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* using specified strategy
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*/
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template <typename Strategy>
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bool passthrough(Strategy wait_strategy) {
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expire_timestamps();
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return wait_strategy(m_queue, m_limit, m_timewindow);
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}
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/**
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* Check if event is allowed to pass
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* using default strategy
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*/
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bool passthrough() {
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return passthrough(strategy::try_once_or_leave_yolo{});
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}
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protected:
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/**
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* Expire old timestamps
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*/
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void expire_timestamps() {
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auto now = timepoint_clock::now();
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while (m_queue.size() > 0) {
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if ((now - m_queue.front()) < m_timewindow)
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break;
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m_queue.pop_front();
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}
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}
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private:
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queue m_queue;
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limit m_limit;
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timewindow m_timewindow;
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};
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template <typename... Args>
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auto make_throttler(Args&&... args) {
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return make_unique<event_throttler>(forward<Args>(args)...);
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}
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}
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LEMONBUDDY_NS_END
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