ClickHouse/contrib/libpoco/Foundation/include/Poco/SingletonHolder.h

72 lines
1.3 KiB
C++

//
// SingletonHolder.h
//
// $Id: //poco/1.4/Foundation/include/Poco/SingletonHolder.h#1 $
//
// Library: Foundation
// Package: Core
// Module: SingletonHolder
//
// Definition of the SingletonHolder template.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_SingletonHolder_INCLUDED
#define Foundation_SingletonHolder_INCLUDED
#include "Poco/Foundation.h"
#include "Poco/Mutex.h"
namespace Poco {
template <class S>
class SingletonHolder
/// This is a helper template class for managing
/// singleton objects allocated on the heap.
/// The class ensures proper deletion (including
/// calling of the destructor) of singleton objects
/// when the application that created them terminates.
{
public:
SingletonHolder():
_pS(0)
/// Creates the SingletonHolder.
{
}
~SingletonHolder()
/// Destroys the SingletonHolder and the singleton
/// object that it holds.
{
delete _pS;
}
S* get()
/// Returns a pointer to the singleton object
/// hold by the SingletonHolder. The first call
/// to get will create the singleton.
{
FastMutex::ScopedLock lock(_m);
if (!_pS) _pS = new S;
return _pS;
}
private:
S* _pS;
FastMutex _m;
};
} // namespace Poco
#endif // Foundation_SingletonHolder_INCLUDED