如果函数执行失败，将返回一个空字符串。

This function returns an empty string on failure.

youdao

如果此代码在执行c 3行后且在完成该构造函数前被另一个线程中断，则双重检查锁定就会失败。

If this code is interrupted by another thread after executing line C3 but before completing the constructor, double-checked locking fails.

youdao

如果调用线程并不拥有这个互斥信号量，那么这个函数的执行将会失败。

If the calling thread has no ownership of this mutex, this function fails.

youdao