volatile

来源： https://stackoverflow.com/questions/53780267/an-equivalent-to-java-volatile-in-python

来源： https://stackoverflow.com/questions/53780267/an-equivalent-to-java-volatile-in-python

来源： https://stackoverflow.com/questions/53780267/an-equivalent-to-java-volatile-in-python

问题 This question already has an answer here : When are const volatile objects necessary? (1 answer) Closed 4 years ago . Say I have some object declared as const volatile : According to the C++ standard ($7.1.5.1/8): [..] volatile is a hint to the implementation to avoid aggressive optimization involving the object because the value of the object might be changed by means undetectable by an implementation.[...] However, the const qualifier implies than the object is not subject to change, so the

问题 This question already has an answer here : When are const volatile objects necessary? (1 answer) Closed 4 years ago . Say I have some object declared as const volatile : According to the C++ standard ($7.1.5.1/8): [..] volatile is a hint to the implementation to avoid aggressive optimization involving the object because the value of the object might be changed by means undetectable by an implementation.[...] However, the const qualifier implies than the object is not subject to change, so the

问题 public class Factory { private Singleton instance; public Singleton getInstance() { Singleton res = instance; if (res == null) { synchronized (this) { res = instance; if (res == null) { res = new Singleton(); instance = res; } } } return res; } } It is almost correct implementation of thread-safe Singleton . The only problem I see is: The thread #1 that is initializing the instance field can published before it will be initialized completely. Now, the second thread can read instance in a

问题 According to cppreference, most uses of the volatile keyword are to be deprecated in C++20. What is the disadvantage of volatile ? And what is the alternative solution when not using volatile ? 回答1: There's a good talk by the c++ committee language evolution chair on why. Brief summary, many of the places that volatile is being removed from didn't have any understandable meaning and just caused confusion. 来源： https://stackoverflow.com/questions/59223814/why-is-volatile-deprecated-in-c20

问题 According to cppreference, most uses of the volatile keyword are to be deprecated in C++20. What is the disadvantage of volatile ? And what is the alternative solution when not using volatile ? 回答1: There's a good talk by the c++ committee language evolution chair on why. Brief summary, many of the places that volatile is being removed from didn't have any understandable meaning and just caused confusion. 来源： https://stackoverflow.com/questions/59223814/why-is-volatile-deprecated-in-c20

问题 In the following code... #include <stdlib.h> #include <stdint.h> extern void get_buffer_from_HW_driver(volatile uint32_t **p); void getBuffer(volatile uint32_t **pp) { // Write an address into pp, that is obtained from a driver // The underlying HW will be DMA-ing into this address, // so the data pointed-to by the pointer returned by this // call are volatile. get_buffer_from_HW_driver(pp); } void work() { uint32_t *p = NULL; getBuffer((volatile uint32_t **)&p); } ...the compiler rightfully

问题 In the following code... #include <stdlib.h> #include <stdint.h> extern void get_buffer_from_HW_driver(volatile uint32_t **p); void getBuffer(volatile uint32_t **pp) { // Write an address into pp, that is obtained from a driver // The underlying HW will be DMA-ing into this address, // so the data pointed-to by the pointer returned by this // call are volatile. get_buffer_from_HW_driver(pp); } void work() { uint32_t *p = NULL; getBuffer((volatile uint32_t **)&p); } ...the compiler rightfully