4. std::weak_ptr expire实现机制的内部细节 std::weak_ptr 的expired 方法通过检查其内部持有的控制块中的引用计数是否为零来实现。如果引用计数为零,则表示所有 std::shared_ptr 实例都已经被销毁,对象也被销毁,因此 weak_ptr 过期。 具体来说,std::weak_ptr 内部持有一个指向 std::shared_ptr 控制块的指...
Run this code #include <iostream>#include <memory>std::weak_ptr<int>gw;voidf(){if(!gw.expired())std::cout<<"gw is valid\n";elsestd::cout<<"gw is expired\n";}intmain(){{autosp=std::make_shared<int>(42);gw=sp;f();}f();} ...
Using theweak_ptr::lock()member function. This technique doesn’t throw.lock()returns an emptyshared_ptrif*thishas expired. Otherwise, it returns ashared_ptrobject that owns the resource to which*thisis pointing (you may have noticed thatlock()does whatfunc()does). In addition toexpire(),...
What kind of tests are run on shared_ptr/weak_ptr internally at Espressif, if any? I (84376) Worker: User count 300, expire count: 27556 I (92659) MemStat: [INTERNAL] I (92666) MemStat: 8-bit F:45976 LB:32716 M:35068 | 32-bit: F:67668 LB:32716 M:56740 I (92666) MemStat: [...
Becauseweak_ptrdoesn’t increment or decrement the use count, it can’t own a resource that isn’t already owned by ashared_ptrobject. Furthermore, aweak_ptrobject mightexpirewhile it’s still alive. This can happen when the lastshared_ptrobject has been destroyed and released the resource...