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#pragma once
#include <memory>
namespace DB
{
class Context;
class MergeTreeTransaction;
/// TODO maybe replace with raw pointer? It should not be shared, only MergeTreeTransactionHolder can own a transaction object
using MergeTreeTransactionPtr = std::shared_ptr<MergeTreeTransaction>;
/// Owns a MergeTreeTransactionObject.
/// Rolls back a transaction in dtor if it was not committed.
/// If `autocommit` flag is true, then it commits transaction if dtor is called normally
/// or rolls it back if dtor was called due to an exception.
class MergeTreeTransactionHolder
{
public:
MergeTreeTransactionHolder() = default;
MergeTreeTransactionHolder(const MergeTreeTransactionPtr & txn_, bool autocommit_, const Context * owned_by_session_context_ = nullptr);
MergeTreeTransactionHolder(MergeTreeTransactionHolder && rhs) noexcept;
MergeTreeTransactionHolder & operator=(MergeTreeTransactionHolder && rhs) noexcept;
~MergeTreeTransactionHolder();
/// NOTE: We cannot make it noncopyable, because we use it as a field of Context.
/// So the following copy constructor and operator does not copy anything,
/// they just leave txn nullptr.
MergeTreeTransactionHolder(const MergeTreeTransactionHolder & rhs);
MergeTreeTransactionHolder & operator=(const MergeTreeTransactionHolder & rhs);
MergeTreeTransactionPtr getTransaction() const { return txn; }
private:
void onDestroy() noexcept;
MergeTreeTransactionPtr txn;
bool autocommit = false;
const Context * owned_by_session_context = nullptr;
};
}
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