32 lines
874 B
C++
32 lines
874 B
C++
template<typename Iterator,typename T>
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T parallel_accumulate(Iterator first,Iterator last,T init)
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{
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unsigned long const length=std::distance(first,last);
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if(!length)
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return init;
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unsigned long const block_size=25;
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unsigned long const num_blocks=(length+block_size-1)/block_size;
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std::vector<std::future<T> > futures(num_blocks-1);
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thread_pool pool;
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Iterator block_start=first;
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for(unsigned long i=0;i<(num_threads-1);++i)
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{
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Iterator block_end=block_start;
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std::advance(block_end,block_size);
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futures[i]=pool.submit(accumulate_block<Iterator,T>());
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block_start=block_end;
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}
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T last_result=accumulate_block()(block_start,last);
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T result=init;
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for(unsigned long i=0;i<(num_blocks-1);++i)
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{
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result+=futures[i].get();
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}
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result += last_result;
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return result;
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}
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