87 lines
2.9 KiB
C++
87 lines
2.9 KiB
C++
/*
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Copyright (c) 2009-2018, Arvid Norberg
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the distribution.
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* Neither the name of the author nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef TIMESTAMP_HISTORY_HPP
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#define TIMESTAMP_HISTORY_HPP
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#include <cstdint>
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#include <array>
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#include "libtorrent/config.hpp"
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#include "libtorrent/assert.hpp"
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namespace libtorrent {
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// timestamp history keeps a history of the lowest timestamps we've
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// seen in the last 20 minutes
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struct TORRENT_EXTRA_EXPORT timestamp_history
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{
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static constexpr int history_size = 20;
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timestamp_history() = default;
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bool initialized() const { return m_num_samples != not_initialized; }
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// add a sample to the timestamp history. If step is true, it's been
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// a minute since the last step
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std::uint32_t add_sample(std::uint32_t sample, bool step);
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std::uint32_t base() const { TORRENT_ASSERT(initialized()); return m_base; }
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void adjust_base(int change);
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private:
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// this is a circular buffer
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std::array<std::uint32_t, history_size> m_history;
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// this is the lowest sample seen in the
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// last 'history_size' minutes
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std::uint32_t m_base = 0;
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// and this is the index we're currently at
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// in the circular buffer
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std::uint16_t m_index = 0;
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static constexpr std::uint16_t not_initialized = 0xffff;
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// this is the number of samples since the
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// last time we stepped one minute. If we
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// don't have enough samples, we won't step
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// if this is set to 'not_initialized' we
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// have bit seen any samples at all yet
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// and m_base is not initialized yet
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std::uint16_t m_num_samples = not_initialized;
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};
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}
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#endif
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