include/libtorrent/bandwidth_limit.hpp

   1 /*
   2
   3 Copyright (c) 2007, Arvid Norberg
   4 All rights reserved.
   5
   6 Redistribution and use in source and binary forms, with or without
   7 modification, are permitted provided that the following conditions
   8 are met:
   9
  10     * Redistributions of source code must retain the above copyright
  11       notice, this list of conditions and the following disclaimer.
  12     * Redistributions in binary form must reproduce the above copyright
  13       notice, this list of conditions and the following disclaimer in
  14       the documentation and/or other materials provided with the distribution.
  15     * Neither the name of the author nor the names of its
  16       contributors may be used to endorse or promote products derived
  17       from this software without specific prior written permission.
  18
  19 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  20 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  23 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29 POSSIBILITY OF SUCH DAMAGE.
  30
  31 */
  32
  33 #ifndef TORRENT_BANDWIDTH_LIMIT_HPP_INCLUDED
  34 #define TORRENT_BANDWIDTH_LIMIT_HPP_INCLUDED
  35
  36 #include <boost/integer_traits.hpp>
  37
  38 #include "libtorrent/assert.hpp"
  39
  40 namespace libtorrent {
  41
  42 // member of peer_connection
  43 struct bandwidth_limit
  44 {
  45         static const int inf = boost::integer_traits<int>::const_max;
  46
  47         bandwidth_limit()
  48                 : m_quota_left(0)
  49                 , m_local_limit(inf)
  50                 , m_current_rate(0)
  51         {}
  52
  53         void throttle(int limit)
  54         {
  55                 TORRENT_ASSERT(limit > 0);
  56                 m_local_limit = limit;
  57         }
  58
  59         int throttle() const
  60         {
  61                 return m_local_limit;
  62         }
  63
  64         void assign(int amount)
  65         {
  66                 TORRENT_ASSERT(amount >= 0);
  67                 m_current_rate += amount;
  68                 m_quota_left += amount;
  69         }
  70
  71         void use_quota(int amount)
  72         {
  73                 TORRENT_ASSERT(amount <= m_quota_left);
  74                 m_quota_left -= amount;
  75         }
  76
  77         int quota_left() const
  78         {
  79                 return (std::max)(m_quota_left, 0);
  80         }
  81
  82         void expire(int amount)
  83         {
  84                 TORRENT_ASSERT(amount >= 0);
  85                 m_current_rate -= amount;
  86         }
  87
  88         int max_assignable() const
  89         {
  90                 if (m_local_limit == inf) return inf;
  91                 if (m_local_limit <= m_current_rate) return 0;
  92                 return m_local_limit - m_current_rate;
  93         }
  94
  95 private:
  96
  97         // this is the amount of bandwidth we have
  98         // been assigned without using yet. i.e.
  99         // the bandwidth that we use up every time
 100         // we receive or send a message. Once this
 101         // hits zero, we need to request more
 102         // bandwidth from the torrent which
 103         // in turn will request bandwidth from
 104         // the bandwidth manager
 105         int m_quota_left;
 106
 107         // the local limit is the number of bytes
 108         // per window size we are allowed to use.
 109         int m_local_limit;
 110
 111         // the current rate is the number of
 112         // bytes we have been assigned within
 113         // the window size.
 114         int m_current_rate;
 115 };
 116
 117 }
 118
 119 #endif
 120