bool io_uring_context::try_submit_io()

in include/unifex/linux/io_uring_context.hpp [291:326]

• 27 lines of code
• 5 McCabe index (conditional complexity)

bool io_uring_context::try_submit_io(PopulateFn populateSqe) noexcept {
  UNIFEX_ASSERT(is_running_on_io_thread());

  if (pending_operation_count() < cqEntryCount_) {
    // Haven't reached limit of completion-queue yet.
    const auto tail = sqTail_->load(std::memory_order_relaxed);
    const auto head = sqHead_->load(std::memory_order_acquire);
    const auto usedCount = (tail - head);
    UNIFEX_ASSERT(usedCount <= sqEntryCount_);
    if (usedCount < sqEntryCount_) {
      // There is space in the submission-queue.
      const auto index = tail & sqMask_;
      auto& sqe = sqEntries_[index];

      static_assert(noexcept(populateSqe(sqe)));

      // nullify the struct
      std::memset(&sqe, 0, sizeof(sqe));

      if constexpr (std::is_void_v<decltype(populateSqe(sqe))>) {
        populateSqe(sqe);
      } else {
        if (!populateSqe(sqe)) {
          return false;
        }
      }

      sqIndexArray_[index] = index;
      sqTail_->store(tail + 1, std::memory_order_release);
      ++sqUnflushedCount_;
      return true;
    }
  }

  return false;
}