240 lines
6.3 KiB
C++
240 lines
6.3 KiB
C++
/*
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Copyright (c) 2003, Magnus Jonsson
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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 TORRENT_ALLOCATE_RESOURCES_IMPL_HPP_INCLUDED
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#define TORRENT_ALLOCATE_RESOURCES_IMPL_HPP_INCLUDED
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#include <map>
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#include <utility>
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#include <boost/shared_ptr.hpp>
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#include "libtorrent/resource_request.hpp"
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#include "libtorrent/peer_id.hpp"
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#include "libtorrent/socket.hpp"
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#include "libtorrent/size_type.hpp"
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#ifdef min
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#undef min
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#endif
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#ifdef max
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#undef max
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#endif
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namespace libtorrent
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{
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int saturated_add(int a, int b);
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namespace aux
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{
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// give num_resources to r,
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// return how how many were actually accepted.
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inline int give(resource_request& r, int num_resources)
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{
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assert(num_resources >= 0);
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assert(r.given <= r.max);
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int accepted = (std::min)(num_resources, r.max - r.given);
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assert(accepted >= 0);
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r.given += accepted;
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assert(r.given <= r.max);
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return accepted;
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}
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#ifndef NDEBUG
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template<class It, class T>
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class allocate_resources_contract_check
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{
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int m_resources;
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It m_start;
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It m_end;
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resource_request T::* m_res;
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public:
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allocate_resources_contract_check(
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int resources
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, It start
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, It end
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, resource_request T::* res)
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: m_resources(resources)
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, m_start(start)
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, m_end(end)
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, m_res(res)
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{
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assert(m_resources >= 0);
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for (It i = m_start, end(m_end); i != end; ++i)
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{
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assert(((*i).*m_res).max >= 0);
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assert(((*i).*m_res).given >= 0);
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}
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}
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~allocate_resources_contract_check()
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{
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int sum_given = 0;
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int sum_max = 0;
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int sum_min = 0;
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for (It i = m_start, end(m_end); i != end; ++i)
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{
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assert(((*i).*m_res).max >= 0);
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assert(((*i).*m_res).min >= 0);
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assert(((*i).*m_res).max >= ((*i).*m_res).min);
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assert(((*i).*m_res).given >= 0);
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assert(((*i).*m_res).given <= ((*i).*m_res).max);
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sum_given = saturated_add(sum_given, ((*i).*m_res).given);
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sum_max = saturated_add(sum_max, ((*i).*m_res).max);
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sum_min = saturated_add(sum_min, ((*i).*m_res).min);
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}
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assert(sum_given == (std::min)(std::max(m_resources, sum_min), sum_max));
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}
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};
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#endif
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template<class It, class T>
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void allocate_resources_impl(
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int resources
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, It start
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, It end
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, resource_request T::* res)
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{
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assert(resources >= 0);
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#ifndef NDEBUG
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allocate_resources_contract_check<It, T> contract_check(
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resources
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, start
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, end
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, res);
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#endif
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if (resources == resource_request::inf)
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{
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// No competition for resources.
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// Just give everyone what they want.
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for (It i = start; i != end; ++i)
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{
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((*i).*res).given = ((*i).*res).max;
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}
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return;
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}
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// Resources are scarce
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int sum_max = 0;
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int sum_min = 0;
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for (It i = start; i != end; ++i)
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{
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sum_max = saturated_add(sum_max, ((*i).*res).max);
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assert(((*i).*res).min < resource_request::inf);
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assert(((*i).*res).min >= 0);
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assert(((*i).*res).min <= ((*i).*res).max);
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sum_min += ((*i).*res).min;
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((*i).*res).given = ((*i).*res).min;
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}
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if (resources == 0 || sum_max == 0)
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return;
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resources = (std::max)(resources, sum_min);
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int resources_to_distribute = (std::min)(resources, sum_max) - sum_min;
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assert(resources_to_distribute >= 0);
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#ifndef NDEBUG
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int prev_resources_to_distribute = resources_to_distribute;
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#endif
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while (resources_to_distribute > 0)
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{
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size_type total_used = 0;
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size_type max_used = 0;
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for (It i = start; i != end; ++i)
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{
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resource_request& r = (*i).*res;
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if(r.given == r.max) continue;
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assert(r.given < r.max);
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max_used = (std::max)(max_used, (size_type)r.used + 1);
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total_used += (size_type)r.used + 1;
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}
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size_type kNumer = resources_to_distribute;
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size_type kDenom = total_used;
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assert(kNumer >= 0);
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assert(kDenom >= 0);
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assert(kNumer <= (std::numeric_limits<int>::max)());
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assert(total_used < (std::numeric_limits<int>::max)());
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if (kNumer * max_used <= kDenom)
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{
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kNumer = 1;
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kDenom = max_used;
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assert(kDenom >= 0);
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assert(kDenom <= (std::numeric_limits<int>::max)());
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}
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for (It i = start; i != end && resources_to_distribute > 0; ++i)
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{
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resource_request& r = (*i).*res;
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if (r.given == r.max) continue;
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assert(r.given < r.max);
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size_type used = (size_type)r.used + 1;
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if (used < 1) used = 1;
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size_type to_give = used * kNumer / kDenom;
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if (to_give > resources_to_distribute)
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to_give = resources_to_distribute;
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assert(to_give >= 0);
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assert(to_give <= resources_to_distribute);
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resources_to_distribute -= give(r, (int)to_give);
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assert(resources_to_distribute >= 0);
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}
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assert(resources_to_distribute >= 0);
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assert(resources_to_distribute < prev_resources_to_distribute);
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#ifndef NDEBUG
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prev_resources_to_distribute = resources_to_distribute;
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#endif
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}
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}
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} // namespace libtorrent::aux
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}
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#endif
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