static size_t grabFromCentralStore()

in dispenso/detail/small_buffer_allocator_impl.h [158:190]

• 32 lines of code
• 7 McCabe index (conditional complexity)

  static size_t grabFromCentralStore(char** buffers) {
    auto& queue = getThreadQueuingData();
    auto& globals = getSmallBufferGlobals<kChunkSize>();
    auto& lock = globals.backingStoreLock;
    auto& backingStore = globals.backingStore;
    while (true) {
      size_t grabbed = queue.try_dequeue_bulk(buffers, kIdealNumTLBuffers);
      if (grabbed) {
        return grabbed;
      }
      uint32_t allocId = lock.fetch_add(1, std::memory_order_acquire);
      if (allocId == 0) {
        char* buffer = reinterpret_cast<char*>(detail::alignedMalloc(kMallocBytes, kChunkSize));
        backingStore.push_back(buffer);

        constexpr size_t kNumToPush = kBuffersPerMalloc - kIdealNumTLBuffers;
        char* topush[kNumToPush];
        for (size_t i = 0; i < kNumToPush; ++i, buffer += kChunkSize) {
          topush[i] = buffer;
        }
        queue.enqueue_bulk(topush, kNumToPush);
        lock.store(0, std::memory_order_release);
        for (size_t i = 0; i < kIdealNumTLBuffers; ++i, buffer += kChunkSize) {
          buffers[i] = buffer;
        }
        return kIdealNumTLBuffers;
      } else {
        while (lock.load(std::memory_order_relaxed)) {
          std::this_thread::yield();
        }
      }
    }
  }