Method operator()

cpp/src/arrow/util/cache_internal.h:128–139

  // the cache entry may be evicted by another thread.

  Value operator()(const Key& key) {
    std::unique_lock<std::mutex> lock(mutex_);
    const Value* value_ptr;
    value_ptr = cache_.Find(key);
    if (ARROW_PREDICT_TRUE(value_ptr != nullptr)) {
      return *value_ptr;
    }
    lock.unlock();
    Value v = func_(key);
    lock.lock();
    return *cache_.Replace(key, std::move(v)).second;
  }

 private:
  std::mutex mutex_;