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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <mutex>
namespace vespalib {
template <typename T>
class VarHolder
{
T _v;
mutable std::mutex _lock;
public:
VarHolder() : _v(), _lock() {}
explicit VarHolder(T v) : _v(std::move(v)), _lock() {}
VarHolder(const VarHolder &) = delete;
VarHolder & operator = (const VarHolder &) = delete;
~VarHolder();
void set(T v) {
T old;
{
std::lock_guard guard(_lock);
old = std::move(_v);
_v = std::move(v);
}
}
void clear() { set(T()); }
T get() const {
std::lock_guard guard(_lock);
return _v;
}
};
template <typename T>
VarHolder<T>::~VarHolder() = default;
}
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