14 #ifndef NANOVDB_REDUCE_H_HAS_BEEN_INCLUDED 15 #define NANOVDB_REDUCE_H_HAS_BEEN_INCLUDED 19 #ifdef NANOVDB_USE_TBB 20 #include <tbb/parallel_reduce.h> 41 template <
typename RangeT,
typename T,
typename FuncT,
typename JoinT>
42 inline T
reduce(RangeT range,
const T& identity,
const FuncT &func,
const JoinT &join)
44 if (range.empty())
return identity;
45 #ifdef NANOVDB_USE_TBB 46 return tbb::parallel_reduce(range, identity, func, join);
47 #else// naive and likely slow alternative based on std::future 48 if (
const size_t threadCount = std::thread::hardware_concurrency()>>1) {
49 std::vector<RangeT> rangePool{ range };
50 while(rangePool.size() < threadCount) {
51 const size_t oldSize = rangePool.size();
52 for (
size_t i = 0; i < oldSize && rangePool.size() < threadCount; ++i) {
53 auto &r = rangePool[i];
54 if (r.is_divisible()) rangePool.push_back(RangeT(r,
Split()));
56 if (rangePool.size() == oldSize)
break;
58 std::vector< std::future<T> > futurePool;
59 for (
auto &r : rangePool) {
60 auto task = std::async(std::launch::async, [&](){
return func(r, identity);});
61 futurePool.push_back( std::move(task) );
64 for (
auto &f : futurePool) {
65 result = join(result, f.get());
69 return static_cast<T
>(func(range, identity));
76 template <
typename T,
typename FuncT,
typename JoinT >
77 inline T
reduce(
size_t begin,
size_t end,
size_t grainSize,
const T& identity,
const FuncT& func,
const JoinT& join)
79 Range1D range(begin, end, grainSize);
80 return reduce( range, identity, func, join );
84 template <
template<
typename...>
class ContainerT,
typename... ArgT,
typename T,
typename FuncT,
typename JoinT >
85 inline T
reduce(
const ContainerT<ArgT...> &c,
const T& identity,
const FuncT& func,
const JoinT& join)
88 return reduce( range, identity, func, join );
93 template <
template<
typename...>
class ContainerT,
typename... ArgT,
typename T,
typename FuncT,
typename JoinT >
94 inline T
reduce(
const ContainerT<ArgT...> &c,
size_t grainSize,
const T& identity,
const FuncT& func,
const JoinT& join)
96 Range1D range(0, c.size(), grainSize);
97 return reduce( range, identity, func, join );
102 #endif // NANOVDB_REDUCE_H_HAS_BEEN_INCLUDED Definition: NanoVDB.h:247
Custom Range class that is compatible with the tbb::blocked_range classes.
T reduce(RangeT range, const T &identity, const FuncT &func, const JoinT &join)
Definition: Reduce.h:42