forked from premiere/premiere-libtorrent
108 lines
3.2 KiB
C++
108 lines
3.2 KiB
C++
/*
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Copyright (c) 2009-2015, 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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#include "libtorrent/timestamp_history.hpp"
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namespace libtorrent {
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enum
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{
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TIME_MASK = 0xffffffff
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};
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// defined in utp_stream.cpp
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bool compare_less_wrap(boost::uint32_t lhs, boost::uint32_t rhs
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, boost::uint32_t mask);
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boost::uint32_t timestamp_history::add_sample(boost::uint32_t sample, bool step)
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{
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if (!initialized())
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{
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for (int i = 0; i < history_size; ++i)
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m_history[i] = sample;
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m_base = sample;
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m_num_samples = 0;
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}
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// don't let the counter wrap
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if (m_num_samples < 0xfffe) ++m_num_samples;
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// if sample is less than base, update the base
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// and update the history entry (because it will
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// be less than that too)
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if (compare_less_wrap(sample, m_base, TIME_MASK))
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{
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m_base = sample;
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m_history[m_index] = sample;
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}
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// if sample is less than our history entry, update it
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else if (compare_less_wrap(sample, m_history[m_index], TIME_MASK))
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{
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m_history[m_index] = sample;
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}
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boost::uint32_t ret = sample - m_base;
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// don't step base delay history unless we have at least 120
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// samples. Anything less would suggest that the connection is
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// essentially idle and the samples are probably not very reliable
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if (step && m_num_samples > 120)
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{
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m_num_samples = 0;
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m_index = (m_index + 1) % history_size;
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m_history[m_index] = sample;
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// update m_base
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m_base = sample;
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for (int i = 0; i < history_size; ++i)
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{
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if (compare_less_wrap(m_history[i], m_base, TIME_MASK))
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m_base = m_history[i];
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}
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}
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return ret;
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}
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void timestamp_history::adjust_base(int change)
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{
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TORRENT_ASSERT(initialized());
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m_base += change;
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// make sure this adjustment sticks by updating all history slots
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for (int i = 0; i < history_size; ++i)
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{
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if (compare_less_wrap(m_history[i], m_base, TIME_MASK))
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m_history[i] = m_base;
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}
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}
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}
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