70 lines
1.9 KiB
C++
70 lines
1.9 KiB
C++
// This file Copyright © Mnemosyne LLC.
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// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
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// or any future license endorsed by Mnemosyne LLC.
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// License text can be found in the licenses/ folder.
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#pragma once
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#ifndef __TRANSMISSION__
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#error only libtransmission should #include this header.
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#endif
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#include <array>
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#include <cstddef> // for size_t
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#include <cstdint> // for uint32_t
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#include <ctime> // for time_t
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/**
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* A short-term memory object that remembers how many times something
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* happened over the last Seconds seconds. `tr_peer` uses it to count
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* how many bytes transferred to estimate the speed over the last
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* Seconds seconds.
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*/
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template<typename SizeType, std::size_t Seconds = 60>
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class tr_recentHistory
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{
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public:
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/**
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* @brief add a counter to the recent history object.
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* @param now the current time in seconds, such as from tr_time()
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* @param n how many items to add to the history's counter
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*/
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constexpr void add(time_t now, SizeType n)
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{
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if (timestamps_[newest_] != now)
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{
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newest_ = (newest_ + 1) % Seconds;
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timestamps_[newest_] = now;
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count_[newest_] = {};
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}
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count_[newest_] += n;
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}
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/**
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* @brief count how many events have occurred in the last N seconds.
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* @param now the current time in seconds, such as from tr_time()
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* @param age_sec how many seconds to count back through.
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*/
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[[nodiscard]] constexpr SizeType count(time_t now, unsigned int age_sec) const
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{
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auto sum = SizeType{};
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time_t const oldest = now - age_sec;
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for (std::size_t i = 0; i < Seconds; ++i)
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{
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if (timestamps_[i] >= oldest)
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{
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sum += count_[i];
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}
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}
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return sum;
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}
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private:
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std::array<time_t, Seconds> timestamps_ = {};
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std::array<SizeType, Seconds> count_ = {};
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uint32_t newest_ = 0;
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};
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