xbot/myirc/ratelimit.cpp

#include "myirc/ratelimit.hpp"

#include <chrono>

namespace myirc {

using namespace std::literals;
using ms = std::chrono::milliseconds;

auto Rfc1459RateLimit::query(size_t want_to_send) -> std::pair<ms, size_t>
{
    const auto now = clock::now();
    if (horizon_ < now) horizon_ = now;

    auto gap = std::chrono::floor<ms>(now + allowance_ - horizon_);
    auto send = gap / cost_;
    if (std::cmp_greater(send, want_to_send)) send = want_to_send;

    if (send > 0) {
        horizon_ += send * cost_;
        return {0ms, send};
    } else {
        horizon_ += cost_;
        return {cost_ - gap, 1};
    }
}

} // namespace myirc