157 lines
2.9 KiB
C++
157 lines
2.9 KiB
C++
/*
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* \brief Reference-counting smart pointer
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* \author Norman Feske
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* \date 2011-02-17
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*/
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/*
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* Copyright (C) 2011-2013 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _NOUX__SHARED_POINTER_PTR_H_
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#define _NOUX__SHARED_POINTER_PTR_H_
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/* Genode includes */
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#include <base/printf.h>
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#include <base/lock.h>
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#include <base/allocator.h>
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#include <base/printf.h>
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/* Noux includes */
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#include <noux_session/sysio.h>
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namespace Noux {
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class Shared_pointer_base;
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class Reference_counter
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{
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private:
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Lock _lock;
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long _value;
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friend class Shared_pointer_base;
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void _inc_ref_count()
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{
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Lock::Guard guard(_lock);
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_value++;
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}
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/**
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* \return reference counter after decrement
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*/
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long _dec_ref_count()
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{
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Lock::Guard guard(_lock);
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return --_value;
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}
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public:
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Reference_counter() : _value(0) { }
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};
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class Shared_pointer_base
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{
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protected:
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Reference_counter *_ref_counter;
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Shared_pointer_base(Reference_counter *ref_counter)
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: _ref_counter(ref_counter) { }
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void _inc_ref_count() {
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if (_ref_counter) _ref_counter->_inc_ref_count(); }
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bool _dec_ref_count() {
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return _ref_counter && (_ref_counter->_dec_ref_count() == 0); }
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long count() const { return _ref_counter ? _ref_counter->_value : -99; }
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};
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template <typename T>
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class Shared_pointer : public Shared_pointer_base
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{
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private:
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T *_ptr;
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Allocator *_alloc;
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void _dec_ref_count()
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{
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if (Shared_pointer_base::_dec_ref_count()) {
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if (0)
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PINF("ref count for %p reached zero -> delete object", _ptr);
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destroy(_alloc, _ptr);
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_ptr = 0;
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_alloc = 0;
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_ref_counter = 0;
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}
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}
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public:
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Shared_pointer() : Shared_pointer_base(0), _ptr(0), _alloc(0) { }
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Shared_pointer(T *ptr, Allocator *alloc)
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: Shared_pointer_base(ptr), _ptr(ptr), _alloc(alloc)
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{
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_inc_ref_count();
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}
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Shared_pointer(Shared_pointer const & from)
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:
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Shared_pointer_base(from._ref_counter),
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_ptr(from._ptr), _alloc(from._alloc)
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{
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_inc_ref_count();
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}
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Shared_pointer & operator=(const Shared_pointer& from)
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{
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/* check for self assignment */
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if (_ptr == from._ptr)
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return *this;
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/* forget about original pointed-to object */
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_dec_ref_count();
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_ref_counter = from._ref_counter;
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_ptr = from._ptr;
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_alloc = from._alloc;
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/* account for newly assigned pointed-to object */
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_inc_ref_count();
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return *this;
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}
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~Shared_pointer()
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{
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_dec_ref_count();
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}
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T * operator -> () { return _ptr; }
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T const* operator -> () const { return _ptr; }
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operator bool () const { return _ptr != 0; }
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template<typename To>
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Shared_pointer<To> dynamic_pointer_cast()
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{
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return Shared_pointer<To>(dynamic_cast<To *>(_ptr), _alloc);
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}
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};
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}
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#endif /* _NOUX__SHARED_POINTER_H_ */
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