c++的静态类型变量初始化是原子操作吗?下面的单例有没有问题？请大神指点一二

[深度抽象]

c++的静态类型初始化是原子操作吗？

多线程的操作下会不会有问题啊？

class Singleton{
    private:
    Singleton(){cout << "singleton init" <<endl;}
    public:
    virtual ~Singleton(){cout << "singleton destroyed"<<endl;}
    static Singleton& GetInstance(){
        static Singleton ins;
        return ins;
    }
};

[ID870177103]

inline VAR _RANDOM_ () {
static CHAR mTable[32] = {3 ,0X9A319039 ,0X32D9C024 ,0X9B663182 ,0X5DA1F342 ,0XDE3B81E0 ,0XDF0A6FB5 ,0XF103BC02 ,0X48F340FB ,0X7449E56B ,0XBEB1DBB0 ,0XAB5C5918 ,0X946554FD ,0X8C2E680F ,0XEB3D799F ,0XB11EE0B7 ,0X2D436B86 ,0XDA672E2A ,0X1588CA88 ,0XE369735D ,0X904F35F7 ,0XD7158FD6 ,0X6FA6F051 ,0X616E6B96 ,0XAC94EFDC ,0X36413F93 ,0XC622C298 ,0XF5A42AB8 ,0X8A88D77B ,0XF5AD9D0E ,0X8999220B ,0X27FB47B9} ;
static INDEX mIndex1 = 4 ;
static INDEX mIndex2 = 1 ;
static const auto _initializer_ = [] (CHAR (&table)[32] ,INDEX &index1 ,INDEX &index2)->BOOL {
#ifdef _INC_TIME
table[0] = CHAR (time (NULL)) ;
for (INDEX i = 1 ; i < 31 ; i++)
table[i] = 1103515145 * table[i - 1] + 12345 ;
index1 = 3 ;
index2 = 0 ;
for (INDEX i = 0 ; i < 310 ; i++)
_RANDOM_ () ;
return TRUE ;
#else
return FALSE ;
#endif
} ;
static const BOOL mInitialized = _initializer_ (mTable ,mIndex1 ,mIndex2) ;
const VAR ret = VAR ((mTable[mIndex1] += mTable[mIndex2]) >> 1) ;
if (mIndex1++ >= 32)
mIndex1 = 1 ;
if (mIndex2++ >= 32)
mIndex2 = 1 ;
return ret ;
}
mInitialized仅被初始化一次

[珍惜生命远离CPP]

不是原子操作。

[深度抽象]

引用 1 楼 akirya 的回复:

不是原子操作。

深入的解释一下吧。

[fefe82]

C++11 以后是。 The zero-initialization (8.5) of all block-scope variables with static storage duration (3.7.1) or thread storage duration (3.7.2) is performed before any other initialization takes place. Constant initialization (3.6.2) of a block-scope entity with static storage duration, if applicable, is performed before its block is first entered. An implementation is permitted to perform early initialization of other block-scope variables with static or thread storage duration under the same conditions that an implementation is permitted to statically initialize a variable with static or thread storage duration in namespace scope (3.6.2). Otherwise such a variable is initialized the first time control passes through its declaration; such a variable is considered initialized upon the completion of its initialization. If the initialization exits by throwing an exception, the initialization is not complete, so it will be tried again the next time control enters the declaration. If control enters the declaration concurrently while the variable is being initialized, the concurrent execution shall wait for completion of the initialization. If control re-enters the declaration recursively while the variable is being initialized, the behavior is undefined.

[珍惜生命远离CPP]

引用 2 楼 wwwzys 的回复:

[quote=引用 1 楼 akirya 的回复:] 不是原子操作。

深入的解释一下吧。[/quote] 只有atmoc类型才是原子操作 google 单件 多线程

[ri_aje]

现在的 c++ 标准保证多线程初始化 static 变量不会发生 data race，可以视为原子操作。