1 | // |
2 | // AtomicCounter.h |
3 | // |
4 | // Library: Foundation |
5 | // Package: Core |
6 | // Module: AtomicCounter |
7 | // |
8 | // Definition of the AtomicCounter class. |
9 | // |
10 | // Copyright (c) 2009, Applied Informatics Software Engineering GmbH. |
11 | // and Contributors. |
12 | // |
13 | // SPDX-License-Identifier: BSL-1.0 |
14 | // |
15 | |
16 | |
17 | #ifndef Foundation_AtomicCounter_INCLUDED |
18 | #define Foundation_AtomicCounter_INCLUDED |
19 | |
20 | |
21 | #include "Poco/Foundation.h" |
22 | #include <atomic> |
23 | |
24 | |
25 | namespace Poco { |
26 | |
27 | |
28 | class Foundation_API AtomicCounter |
29 | /// This class implements a simple counter, which |
30 | /// provides atomic operations that are safe to |
31 | /// use in a multithreaded environment. |
32 | /// |
33 | /// Typical usage of AtomicCounter is for implementing |
34 | /// reference counting and similar functionality. |
35 | { |
36 | public: |
37 | typedef int ValueType; /// The underlying integer type. |
38 | |
39 | AtomicCounter(); |
40 | /// Creates a new AtomicCounter and initializes it to zero. |
41 | |
42 | explicit AtomicCounter(ValueType initialValue); |
43 | /// Creates a new AtomicCounter and initializes it with |
44 | /// the given value. |
45 | |
46 | AtomicCounter(const AtomicCounter& counter); |
47 | /// Creates the counter by copying another one. |
48 | |
49 | ~AtomicCounter(); |
50 | /// Destroys the AtomicCounter. |
51 | |
52 | AtomicCounter& operator = (const AtomicCounter& counter); |
53 | /// Assigns the value of another AtomicCounter. |
54 | |
55 | AtomicCounter& operator = (ValueType value); |
56 | /// Assigns a value to the counter. |
57 | |
58 | operator ValueType () const; |
59 | /// Converts the AtomicCounter to ValueType. |
60 | |
61 | ValueType value() const; |
62 | /// Returns the value of the counter. |
63 | |
64 | ValueType operator ++ (); // prefix |
65 | /// Increments the counter and returns the result. |
66 | |
67 | ValueType operator ++ (int); // postfix |
68 | /// Increments the counter and returns the previous value. |
69 | |
70 | ValueType operator -- (); // prefix |
71 | /// Decrements the counter and returns the result. |
72 | |
73 | ValueType operator -- (int); // postfix |
74 | /// Decrements the counter and returns the previous value. |
75 | |
76 | bool operator ! () const; |
77 | /// Returns true if the counter is zero, false otherwise. |
78 | |
79 | private: |
80 | std::atomic<int> _counter; |
81 | }; |
82 | |
83 | |
84 | // |
85 | // inlines |
86 | // |
87 | |
88 | inline AtomicCounter::operator AtomicCounter::ValueType () const |
89 | { |
90 | return _counter.load(); |
91 | } |
92 | |
93 | |
94 | inline AtomicCounter::ValueType AtomicCounter::value() const |
95 | { |
96 | return _counter.load(); |
97 | } |
98 | |
99 | |
100 | inline AtomicCounter::ValueType AtomicCounter::operator ++ () // prefix |
101 | { |
102 | return ++_counter; |
103 | } |
104 | |
105 | |
106 | inline AtomicCounter::ValueType AtomicCounter::operator ++ (int) // postfix |
107 | { |
108 | return _counter++; |
109 | } |
110 | |
111 | |
112 | inline AtomicCounter::ValueType AtomicCounter::operator -- () // prefix |
113 | { |
114 | return --_counter; |
115 | } |
116 | |
117 | |
118 | inline AtomicCounter::ValueType AtomicCounter::operator -- (int) // postfix |
119 | { |
120 | return _counter--; |
121 | } |
122 | |
123 | |
124 | inline bool AtomicCounter::operator ! () const |
125 | { |
126 | return _counter.load() == 0; |
127 | } |
128 | |
129 | |
130 | } // namespace Poco |
131 | |
132 | |
133 | #endif // Foundation_AtomicCounter_INCLUDED |
134 | |