编程参考 - Fence函数介绍

内存栅栏（或内存屏障）功能可确保栅栏前后的内存操作不会被编译器或 CPU 重新排序。这在并发编程中至关重要，可在不同线程间保持适当的内存可见性和排序。

A memory fence (or memory barrier) function ensures that memory operations before and after the fence are not reordered by the compiler or the CPU. This is crucial in concurrent programming to maintain proper memory visibility and ordering across different threads.

带有 Release 和 Acquire 参数的 fence() 函数通常用于底层并发编程，以控制内存排序。它起到内存屏障的作用，确保栅栏前后的内存操作不会重新排序。这在多线程环境中至关重要，可避免出现竞赛条件，并确保线程间的正常同步。

The fence() function with parameters Release and Acquire is typically used in low-level concurrent programming to control memory ordering. It acts as a memory barrier, ensuring that memory operations before and after the fence are not reordered. This is crucial in multi-threaded environments to avoid race conditions and ensure proper synchronization between threads.

以下是对 "发布 "和 "获取 "语义的简要解释：

* 释放： 确保在后续内存写入之前，其他线程可以看到之前所有的内存写入（存储）。

* 获取： 确保所有后续内存读取（加载）都能看到其他线程在获取栅栏之前写入的内存。

Here's a brief explanation of Release and Acquire semantics:

* Release: Ensures that all previous memory writes (stores) are visible to other threads before any subsequent memory writes.

* Acquire: Ensures that all subsequent memory reads (loads) see any previous memory writes made visible by other threads before the acquire fence.

让我们来看一个使用原子操作和栅栏的 C++ 示例。这个示例假设了一个简单的场景：一个线程产生数据（向共享变量写入数据），另一个线程消耗数据（从共享变量读取数据）。

Let's see an example in C++ using atomic operations and fences. This example assumes a simple scenario where one thread produces data (writes to a shared variable) and another thread consumes data (reads from the shared variable).

Example

C and C++ (Using atomic_thread_fence)

#include <atomic>

#include <thread>

#include <iostream></