xref: /onnv-gate/usr/src/cmd/lms/SyncLib/Include/SPtr.h (revision 9203:3ebffd0a1b10)
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30*9203SMark.Logan@Sun.COM 
31*9203SMark.Logan@Sun.COM //////////////////////////////////////////////////////////////////////////
32*9203SMark.Logan@Sun.COM //  SPtr.h
33*9203SMark.Logan@Sun.COM //
34*9203SMark.Logan@Sun.COM //  This is a smart pointer class. It receives an initialized object in
35*9203SMark.Logan@Sun.COM //  the constructor, and maintains a reference count to this object. It
36*9203SMark.Logan@Sun.COM //  deletes the object only when the reference count reaches 0.
37*9203SMark.Logan@Sun.COM //
38*9203SMark.Logan@Sun.COM //////////////////////////////////////////////////////////////////////////
39*9203SMark.Logan@Sun.COM 
40*9203SMark.Logan@Sun.COM #ifndef _SPTR_H_
41*9203SMark.Logan@Sun.COM #define _SPTR_H_
42*9203SMark.Logan@Sun.COM 
43*9203SMark.Logan@Sun.COM #include <memory>
44*9203SMark.Logan@Sun.COM #include "Semaphore.h"
45*9203SMark.Logan@Sun.COM 
46*9203SMark.Logan@Sun.COM template
47*9203SMark.Logan@Sun.COM <class T>
48*9203SMark.Logan@Sun.COM class SPtr
49*9203SMark.Logan@Sun.COM {
50*9203SMark.Logan@Sun.COM public:
51*9203SMark.Logan@Sun.COM 	// constructor
52*9203SMark.Logan@Sun.COM 	explicit SPtr(T *ptr_p = 0) :
_ptr(ptr_p)53*9203SMark.Logan@Sun.COM 		_ptr(ptr_p),
54*9203SMark.Logan@Sun.COM 		_pref_count(new int(1)),
55*9203SMark.Logan@Sun.COM 		_psem(new Semaphore(1)) {}
56*9203SMark.Logan@Sun.COM 
57*9203SMark.Logan@Sun.COM 	// copy constructor
58*9203SMark.Logan@Sun.COM 	template<class X>
SPtr(const SPtr<X> & other_sptr_p)59*9203SMark.Logan@Sun.COM 	SPtr(const SPtr<X> &other_sptr_p)
60*9203SMark.Logan@Sun.COM 	{
61*9203SMark.Logan@Sun.COM 		other_sptr_p.getSem()->acquire();
62*9203SMark.Logan@Sun.COM 		_ptr = other_sptr_p.get();
63*9203SMark.Logan@Sun.COM 		_pref_count = other_sptr_p.getRefcnt();
64*9203SMark.Logan@Sun.COM 		_psem = other_sptr_p.getSem();
65*9203SMark.Logan@Sun.COM 		++(*_pref_count);
66*9203SMark.Logan@Sun.COM 		_psem->release();
67*9203SMark.Logan@Sun.COM 	}
68*9203SMark.Logan@Sun.COM 
SPtr(const SPtr & other_sptr_p)69*9203SMark.Logan@Sun.COM 	SPtr(const SPtr &other_sptr_p)
70*9203SMark.Logan@Sun.COM 	{
71*9203SMark.Logan@Sun.COM 		other_sptr_p.getSem()->acquire();
72*9203SMark.Logan@Sun.COM 		_ptr = other_sptr_p.get();
73*9203SMark.Logan@Sun.COM 		_pref_count = other_sptr_p.getRefcnt();
74*9203SMark.Logan@Sun.COM 		_psem = other_sptr_p.getSem();
75*9203SMark.Logan@Sun.COM 		++(*_pref_count);
76*9203SMark.Logan@Sun.COM 		_psem->release();
77*9203SMark.Logan@Sun.COM 	}
78*9203SMark.Logan@Sun.COM 
79*9203SMark.Logan@Sun.COM 	// destructor
~SPtr()80*9203SMark.Logan@Sun.COM 	~SPtr()
81*9203SMark.Logan@Sun.COM 	{
82*9203SMark.Logan@Sun.COM 		_psem->acquire();
83*9203SMark.Logan@Sun.COM 		if (--(*_pref_count) == 0) {
84*9203SMark.Logan@Sun.COM 			// delete pointer only on last destruction
85*9203SMark.Logan@Sun.COM 			delete _pref_count;
86*9203SMark.Logan@Sun.COM 			delete _psem;
87*9203SMark.Logan@Sun.COM 			if (_ptr) {
88*9203SMark.Logan@Sun.COM 				delete _ptr;
89*9203SMark.Logan@Sun.COM 			}
90*9203SMark.Logan@Sun.COM 			_ptr = 0;
91*9203SMark.Logan@Sun.COM 		} else {
92*9203SMark.Logan@Sun.COM 			_psem->release();
93*9203SMark.Logan@Sun.COM 		}
94*9203SMark.Logan@Sun.COM 	}
95*9203SMark.Logan@Sun.COM 
96*9203SMark.Logan@Sun.COM 	// operator=
97*9203SMark.Logan@Sun.COM 	// if 'this' already points to an object, unreference it
98*9203SMark.Logan@Sun.COM 	template<class X>
99*9203SMark.Logan@Sun.COM 	SPtr &operator= (const SPtr<X> &other_sptr_p)
100*9203SMark.Logan@Sun.COM 	{
101*9203SMark.Logan@Sun.COM 		if ((void *)&other_sptr_p == this) {
102*9203SMark.Logan@Sun.COM 			return *this;
103*9203SMark.Logan@Sun.COM 		}
104*9203SMark.Logan@Sun.COM 		_psem->acquire();
105*9203SMark.Logan@Sun.COM 		if (--(*_pref_count) == 0) {
106*9203SMark.Logan@Sun.COM 			delete _pref_count;
107*9203SMark.Logan@Sun.COM 			delete _psem;
108*9203SMark.Logan@Sun.COM 			if (_ptr) {
109*9203SMark.Logan@Sun.COM 				delete _ptr;
110*9203SMark.Logan@Sun.COM 			}
111*9203SMark.Logan@Sun.COM 		} else {
112*9203SMark.Logan@Sun.COM 			_psem->release();
113*9203SMark.Logan@Sun.COM 		}
114*9203SMark.Logan@Sun.COM 		other_sptr_p.getSem()->acquire();
115*9203SMark.Logan@Sun.COM 		_ptr = (T *)other_sptr_p.get();
116*9203SMark.Logan@Sun.COM 		_pref_count = other_sptr_p.getRefcnt();
117*9203SMark.Logan@Sun.COM 		_psem = other_sptr_p.getSem();
118*9203SMark.Logan@Sun.COM 		++(*_pref_count);
119*9203SMark.Logan@Sun.COM 		_psem->release();
120*9203SMark.Logan@Sun.COM 		return *this;
121*9203SMark.Logan@Sun.COM 	}
122*9203SMark.Logan@Sun.COM 
123*9203SMark.Logan@Sun.COM 	SPtr &operator=(const SPtr &other_sptr_p)
124*9203SMark.Logan@Sun.COM 	{
125*9203SMark.Logan@Sun.COM 		if (&other_sptr_p == this) {
126*9203SMark.Logan@Sun.COM 			return *this;
127*9203SMark.Logan@Sun.COM 		}
128*9203SMark.Logan@Sun.COM 		_psem->acquire();
129*9203SMark.Logan@Sun.COM 		if (--(*_pref_count) == 0) {
130*9203SMark.Logan@Sun.COM 			delete _pref_count;
131*9203SMark.Logan@Sun.COM 			delete _psem;
132*9203SMark.Logan@Sun.COM 			if (_ptr) {
133*9203SMark.Logan@Sun.COM 				delete _ptr;
134*9203SMark.Logan@Sun.COM 			}
135*9203SMark.Logan@Sun.COM 		} else {
136*9203SMark.Logan@Sun.COM 			_psem->release();
137*9203SMark.Logan@Sun.COM 		}
138*9203SMark.Logan@Sun.COM 		other_sptr_p.getSem()->acquire();
139*9203SMark.Logan@Sun.COM 		_ptr = other_sptr_p.get();
140*9203SMark.Logan@Sun.COM 		_pref_count = other_sptr_p.getRefcnt();
141*9203SMark.Logan@Sun.COM 		_psem = other_sptr_p.getSem();
142*9203SMark.Logan@Sun.COM 		++(*_pref_count);
143*9203SMark.Logan@Sun.COM 		_psem->release();
144*9203SMark.Logan@Sun.COM 		return *this;
145*9203SMark.Logan@Sun.COM 	}
146*9203SMark.Logan@Sun.COM 
147*9203SMark.Logan@Sun.COM 	// operator*
148*9203SMark.Logan@Sun.COM 	T &operator*() const
149*9203SMark.Logan@Sun.COM 	{
150*9203SMark.Logan@Sun.COM 		return *_ptr;
151*9203SMark.Logan@Sun.COM 	}
152*9203SMark.Logan@Sun.COM 
153*9203SMark.Logan@Sun.COM 	// operator->
154*9203SMark.Logan@Sun.COM 	T *operator->() const
155*9203SMark.Logan@Sun.COM 	{
156*9203SMark.Logan@Sun.COM 		return _ptr;
157*9203SMark.Logan@Sun.COM 	}
158*9203SMark.Logan@Sun.COM 
159*9203SMark.Logan@Sun.COM 	// get - return inner pointer
get()160*9203SMark.Logan@Sun.COM 	T *get() const
161*9203SMark.Logan@Sun.COM 	{
162*9203SMark.Logan@Sun.COM 		return _ptr;
163*9203SMark.Logan@Sun.COM 	}
164*9203SMark.Logan@Sun.COM 
getRefcnt()165*9203SMark.Logan@Sun.COM 	int *getRefcnt() const
166*9203SMark.Logan@Sun.COM 	{
167*9203SMark.Logan@Sun.COM 		return _pref_count;
168*9203SMark.Logan@Sun.COM 	}
169*9203SMark.Logan@Sun.COM 
getSem()170*9203SMark.Logan@Sun.COM 	Semaphore *getSem() const
171*9203SMark.Logan@Sun.COM 	{
172*9203SMark.Logan@Sun.COM 		return _psem;
173*9203SMark.Logan@Sun.COM 	}
174*9203SMark.Logan@Sun.COM 
175*9203SMark.Logan@Sun.COM private:
176*9203SMark.Logan@Sun.COM 	// the pointer itself
177*9203SMark.Logan@Sun.COM 	T *_ptr;
178*9203SMark.Logan@Sun.COM 	// a pointer to the reference count
179*9203SMark.Logan@Sun.COM 	int *_pref_count;
180*9203SMark.Logan@Sun.COM 	Semaphore *_psem;
181*9203SMark.Logan@Sun.COM } ;
182*9203SMark.Logan@Sun.COM 
183*9203SMark.Logan@Sun.COM template
184*9203SMark.Logan@Sun.COM <class T>
185*9203SMark.Logan@Sun.COM inline bool operator==(const SPtr<T> &x, const SPtr<T> &y) {
186*9203SMark.Logan@Sun.COM 	return(x.get() == y.get());
187*9203SMark.Logan@Sun.COM }
188*9203SMark.Logan@Sun.COM 
189*9203SMark.Logan@Sun.COM template
190*9203SMark.Logan@Sun.COM <class T>
191*9203SMark.Logan@Sun.COM inline bool operator!=(const SPtr<T> &x, const SPtr<T> &y) {
192*9203SMark.Logan@Sun.COM 	return(x.get() != y.get());
193*9203SMark.Logan@Sun.COM }
194*9203SMark.Logan@Sun.COM 
195*9203SMark.Logan@Sun.COM #endif // _SPTR_H_
196*9203SMark.Logan@Sun.COM 
197