C++ High Performance

Implementation

Implementation-wise, it's quite a small bit of code. The incoming range is recursively split into two chunks; the first chunk is recursively invoked as a new task, and the second chunk is processed on the same task:

template <typename SrcIt, typename DstIt, typename Func> 
auto par_transform(SrcIt first,SrcIt last,DstIt dst,Func f,size_t chunk_sz) { 
  const auto n = static_cast<size_t>(std::distance(first, last));  if (n <= chunk_sz) { 
    std::transform(first, last, dst, f); 
    return; 
  } 
  const auto src_middle = std::next(first, n/2); 
  // Branch of first part to another task 
  auto future = std::async([=, &func]{ 
    par_transform(first, src_middle, dst, f, chunk_sz); 
  }); 
  // Recursively handle the second part const auto dst_middle = std::next(dst, ...