C++ and the Perils of Double-Checked Locking: Part II
By Scott Meyers and Andrei Alexandrescu, August 01, 2004
In this installment, Scott and Andrei examine the relationship between thread safety and the volatile keyword.
August, 2004: C++ and the Perils of Double-Checked Locking: Part II
class Singleton {
public:
static volatile Singleton* volatile instance();
...
private:
// one more volatile added
static volatile Singleton* volatile pInstance;
};
// from the implementation file
volatile Singleton* volatile Singleton::pInstance = 0;
volatile Singleton* volatile Singleton::instance() {
if (pInstance == 0) {
Lock lock;
if (pInstance == 0) {
// one more volatile added
volatile Singleton* volatile temp =
new volatile Singleton;
pInstance = temp;
}
}
return pInstance;
}
Example 9: A glorified version of Singleton.
