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#pragma once
#include <memory>
#include <atomic>
namespace DB
{
class ActionBlocker;
using StorageActionBlockType = size_t;
/// Blocks related action while a ActionLock instance exists
/// ActionBlocker could be destroyed before the lock, in this case ActionLock will safely do nothing in its destructor
class ActionLock
{
public:
ActionLock() = default;
explicit ActionLock(const ActionBlocker & blocker);
ActionLock(ActionLock && other) noexcept;
ActionLock & operator=(ActionLock && other) noexcept;
ActionLock(const ActionLock & other) = delete;
ActionLock & operator=(const ActionLock & other) = delete;
bool expired() const
{
return counter_ptr.expired();
}
~ActionLock()
{
if (auto counter = counter_ptr.lock())
--(*counter);
}
private:
using Counter = std::atomic<int>;
using CounterWeakPtr = std::weak_ptr<Counter>;
CounterWeakPtr counter_ptr;
};
}
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