43inline T
reduce(RangeT range,
const T& identity,
const FuncT &func,
const JoinT &join)
45 if (range.empty())
return identity;
47 return tbb::parallel_reduce(range, identity, func, join);
49 if (
const size_t threadCount = std::thread::hardware_concurrency()>>1) {
50 std::vector<RangeT> rangePool{ range };
51 while(rangePool.size() < threadCount) {
52 const size_t oldSize = rangePool.size();
53 for (
size_t i = 0; i < oldSize && rangePool.size() < threadCount; ++i) {
54 auto &r = rangePool[i];
55 if (r.is_divisible()) rangePool.push_back(RangeT(r,
Split()));
57 if (rangePool.size() == oldSize)
break;
59 std::vector< std::future<T> > futurePool;
60 for (
auto &r : rangePool) {
61 auto task = std::async(std::launch::async, [&](){
return func(r, identity);});
62 futurePool.push_back( std::move(task) );
65 for (
auto &f : futurePool) {
66 result = join(result, f.get());
70 return static_cast<T
>(func(range, identity));
T reduce(size_t begin, size_t end, size_t grainSize, const T &identity, const FuncT &func, const JoinT &join)
Simple wrapper to the function defined above.
Definition Reduce.h:106