void parallel_for_staticImpl()

in dispenso/parallel_for.h [229:287]
48 lines of code
6 McCabe index (conditional complexity)

void parallel_for_staticImpl(
    TaskSetT& taskSet,
    StateContainer& states,
    const StateGen& defaultState,
    const ChunkedRange<IntegerT>& range,
    F&& f,
    ParForOptions options) {
  ssize_t numThreads = std::min<ssize_t>(taskSet.numPoolThreads(), options.maxThreads);
  // Reduce threads used if they exceed work to be done.
  numThreads = std::min<ssize_t>(numThreads, range.size());

  for (ssize_t i = 0; i < numThreads; ++i) {
    states.emplace_back(defaultState());
  }

  auto chunking = detail::staticChunkSize(range.size(), numThreads);
  IntegerT chunkSize = static_cast<IntegerT>(chunking.ceilChunkSize);

  bool perfectlyChunked = chunking.transitionTaskIndex == numThreads;

  // (!perfectlyChunked) ? chunking.transitionTaskIndex : numThreads - 1;
  ssize_t firstLoopLen = chunking.transitionTaskIndex - perfectlyChunked;

  auto stateIt = states.begin();
  IntegerT start = range.start;
  ssize_t t;
  for (t = 0; t < firstLoopLen; ++t) {
    IntegerT next = static_cast<IntegerT>(start + chunkSize);
    taskSet.schedule([it = stateIt++, start, next, f]() {
      auto recurseInfo = detail::PerPoolPerThreadInfo::parForRecurse();
      f(*it, start, next);
    });
    start = next;
  }

  // Reduce the remaining chunk sizes by 1.
  chunkSize = static_cast<IntegerT>(chunkSize - !perfectlyChunked);
  // Finish submitting all but the last item.
  for (; t < numThreads - 1; ++t) {
    IntegerT next = static_cast<IntegerT>(start + chunkSize);
    taskSet.schedule([it = stateIt++, start, next, f]() {
      auto recurseInfo = detail::PerPoolPerThreadInfo::parForRecurse();
      f(*it, start, next);
    });
    start = next;
  }

  if (options.wait) {
    f(*stateIt, start, range.end);
    taskSet.wait();
  } else {
    taskSet.schedule(
        [stateIt, start, end = range.end, f]() {
          auto recurseInfo = detail::PerPoolPerThreadInfo::parForRecurse();
          f(*stateIt, start, end);
        },
        ForceQueuingTag());
  }
}