1 #include <iostream>
2 using namespace std;
3
4 /************************************************************************/
5 /*Lazy Singletom(非线程安全) */
6 /************************************************************************/
7 class singleton
8 {
9 public:
10 static singleton& Instance()
11 {
12 if (ps == NULL)
13 {
14 ps = new singleton;
15 }
16 return *ps;
17 }
18 private:
19 singleton();
20 singleton(const singleton&);
21 ~singleton();
22 static singleton* ps;
23 };
24 singleton*singleton::ps = NULL;
25
26 /************************************************************************/
27 /* Eager singleton(线程安全) */
28 /* 函数外的staic对象在不同编译单元初始化顺序不固定，两个线程交互会产生问题*/
29 /************************************************************************/
30 class singleton
31 {
32 public:
33 static singleton& Instance()
34 {
35 return instance;
36 }
37 private:
38 singleton();
39 singleton(const singleton&);
40 ~singleton();
41 static singleton instance;
42 };
43 singleton singleton::instance;
44
45 /************************************************************************/
46 /* Meyes singleton C++11后为线程安全 */
47 /************************************************************************/
48 class singleton
49 {
50 public:
51 static singleton& Instance()
52 {
53 return static singleton instance;
54 }
55 private:
56 singleton();
57 singleton(const singleton&);
58 ~singleton();
59 };
60
61 /************************************************************************/
62 /* Double_lock 基于线程安全的懒加载 */
63 /************************************************************************/
64 class singleton
65 {
66 public:
67 static singleton& Instance()
68 {
69 if (ps == NULL)
70 {
71 lock();
72 if (ps == NULL)
73 {
74 ps = new singleton;
75 }
76 unlock();
77 }
78 return *ps;
79 }
80 private:
81 singleton();
82 ~singleton();
83 singleton(const singleton&);
84 static singleton* ps;
85 };
86 singleton* singleton::ps = NULL;
