atomic.hpp

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#pragma once
 
 
#include <atomic>
 
USERVER_NAMESPACE_BEGIN
 
namespace utils {
 
template <typename T, typename Func>
T AtomicUpdate(std::atomic<T>& atomic, Func updater) {
  T old_value = atomic.load();
  while (true) {
    // make a copy to to keep old_value unchanged
    const T new_value = updater(T{old_value});
    if (atomic.compare_exchange_weak(old_value, new_value)) return new_value;
  }
}
 
template <typename T>
T AtomicMin(std::atomic<T>& atomic, T value) {
  return utils::AtomicUpdate(atomic, [value](T old_value) {
    return value < old_value ? value : old_value;
  });
}
 
template <typename T>
T AtomicMax(std::atomic<T>& atomic, T value) {
  return utils::AtomicUpdate(atomic, [value](T old_value) {
    return old_value < value ? value : old_value;
  });
}
 
}  // namespace utils
 
USERVER_NAMESPACE_END