9231335eef
TBB has a global task scheduler (that's one of the reason TBB is not
linked statically but dyanmically instead). This allows control over all
running threads, enabling us to use nested parallelism and the scheduler
doing all the task allocation itself.
That is, nested parallel execution such as in
parallel_for(seq, [](const auto& rng){
parallel_sort(rng);
});
is no problem at all, as the scheduler still claims control over the
global environment.
Therefore, use `parallel_sort` Range overload where possible.
References:
- https://www.threadingbuildingblocks.org/docs/help/hh_goto.htm#reference/algorithms.htm
- https://www.threadingbuildingblocks.org/docs/help/hh_goto.htm#reference/algorithms/parallel_sort_func.htm
- https://www.threadingbuildingblocks.org/docs/help/hh_goto.htm#reference/task_scheduler.htm
- https://www.threadingbuildingblocks.org/docs/help/hh_goto.htm#reference/task_scheduler/task_scheduler_init_cls.htm
- https://www.threadingbuildingblocks.org/docs/help/hh_goto.htm#tbb_userguide/Initializing_and_Terminating_the_Library.htm
115 lines
3.5 KiB
C++
115 lines
3.5 KiB
C++
/*
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Copyright (c) 2015, Project OSRM contributors
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All rights reserved.
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Redistribution and use in source and binary forms, with or without modification,
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are permitted provided that the following conditions are met:
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Redistributions of source code must retain the above copyright notice, this list
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of conditions and the following disclaimer.
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Redistributions in binary form must reproduce the above copyright notice, this
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list of conditions and the following disclaimer in the documentation and/or
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other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
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ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef CONTAINER_HPP
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#define CONTAINER_HPP
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#include <tbb/parallel_sort.h>
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#include <algorithm>
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#include <iterator>
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#include <vector>
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#include <utility>
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namespace osrm
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{
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namespace detail
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{
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// Culled by SFINAE if reserve does not exist or is not accessible
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template <typename T>
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constexpr auto has_resize_method(T &t) noexcept -> decltype(t.resize(0), bool())
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{
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return true;
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}
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// Used as fallback when SFINAE culls the template method
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constexpr bool has_resize_method(...) noexcept { return false; }
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}
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template <typename Container> void sort_unique_resize(Container &vector) noexcept
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{
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tbb::parallel_sort(vector);
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const auto number_of_unique_elements =
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std::unique(std::begin(vector), std::end(vector)) - std::begin(vector);
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if (detail::has_resize_method(vector))
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{
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vector.resize(number_of_unique_elements);
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}
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}
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// template <typename T> inline void sort_unique_resize_shrink_vector(std::vector<T> &vector)
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// {
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// sort_unique_resize(vector);
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// vector.shrink_to_fit();
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// }
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// template <typename T> inline void remove_consecutive_duplicates_from_vector(std::vector<T>
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// &vector)
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// {
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// const auto number_of_unique_elements = std::unique(vector.begin(), vector.end()) -
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// vector.begin();
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// vector.resize(number_of_unique_elements);
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// }
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template <typename ForwardIterator, typename Function>
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Function for_each_pair(ForwardIterator begin, ForwardIterator end, Function function)
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{
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if (begin == end)
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{
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return function;
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}
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auto next = begin;
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next = std::next(next);
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while (next != end)
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{
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function(*begin, *next);
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begin = std::next(begin);
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next = std::next(next);
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}
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return function;
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}
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template <class ContainerT, typename Function>
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Function for_each_pair(ContainerT &container, Function function)
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{
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return for_each_pair(std::begin(container), std::end(container), function);
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}
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template <class Container> void append_to_container(Container &&a) {}
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template <class Container, typename T, typename... Args>
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void append_to_container(Container &&container, T value, Args &&... args)
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{
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container.emplace_back(value);
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append_to_container(std::forward<Container>(container), std::forward<Args>(args)...);
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}
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} // namespace osrm
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#endif /* CONTAINER_HPP */
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