atomic_store
时间: 2024-08-14 07:09:15 浏览: 26
`atomic_store`是一个原子操作,通常在并行编程或多线程编程中使用,用于将一个值存储到特定位置的内存地址,保证这个操作在单个处理器周期内完成,不会被其他线程干扰。它是原子操作的一部分,这意味着它要么全部成功,要么完全失败,不会因为中间状态而引起数据竞争。在C++标准库中的`std::atomic`头文件中能找到这个函数,比如`atomic<int> my_var; atomic_store(&my_var, 42);`这会原子地将整数值42存储到`my_var`变量的位置。原子操作对于需要保证数据一致性、避免竞态条件的并发程序至关重要。
相关问题
std::atomic_store
std::atomic_store is a function in the C++ standard library that allows you to atomically store a value into an atomic object. It ensures that the operation is performed as a single, indivisible operation, without any intermediate states visible to other threads.
The syntax for std::atomic_store is as follows:
```cpp
void atomic_store(std::atomic<T>* obj, const T& value);
```
Here, `obj` is a pointer to an std::atomic object, and `value` is the new value to be stored.
For example, let's say we have an atomic integer `std::atomic<int> count` and we want to store the value 10 atomically:
```cpp
std::atomic<int> count;
std::atomic_store(&count, 10);
```
In this case, the value 10 would be stored into `count` atomically, ensuring that no other thread can observe intermediate states during the operation.
It's important to note that std::atomic_store only performs the store operation and does not return any value. If you need to retrieve the previous value, you can use std::atomic_exchange instead.
std::atomic_load 和 std::atomic_store:分别用于读取和写入原子变量的值举例说明
下面是 std::atomic_load 和 std::atomic_store 的示例代码:
```cpp
#include <iostream>
#include <thread>
#include <atomic>
std::atomic<int> counter(0);
void increment_counter() {
for (int i = 0; i < 1000000; ++i) {
counter.store(counter.load() + 1); // 原子地读取和写入计数器的值
}
}
int main() {
std::thread t1(increment_counter);
std::thread t2(increment_counter);
t1.join();
t2.join();
std::cout << "Final counter value is " << counter.load() << std::endl; // 原子地读取计数器的最终值
return 0;
}
```
在这个例子中,我们创建了一个 std::atomic<int> 类型的计数器,它会在两个线程中被并发地访问。每个线程都会调用 increment_counter 函数,该函数会对计数器执行100万次自增操作。在自增操作中,我们使用了 std::atomic_load 和 std::atomic_store 函数来原子地读取和写入计数器的值,以避免多个线程同时修改计数器值时可能产生的竞态条件问题。最后,我们使用 counter.load() 函数来原子地读取计数器的最终值,并输出到控制台上。
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