此类型在静态位置常用于惰性全局初始化。

AtomicRef 只能包含 Sized 类型，因为未大小类型具有宽指针，无法原子地写入或读取。

排序

使用 Relaxed 内存排序加载或存储原子引用是不安全的，因为这些操作没有对引用背后的数据的写入排序。为了避免此问题，加载和存储操作实际上使用 Acquire、Release 或 AcqRel 排序，具体取决于情况。

示例

静态日志状态

use atomic_ref::AtomicRef;
use std::sync::atomic::Ordering;
use std::io::{stdout, Write};

// Define the idea of a logger
trait Logger {
    fn log(&self, msg: &str) {}
}
struct LoggerInfo {
    logger: &'static (dyn Logger + Sync)
}

// The methods for working with our currently defined static logger
static LOGGER: AtomicRef<LoggerInfo> = AtomicRef::new(None);
fn log(msg: &str) -> bool {
    if let Some(info) = LOGGER.load(Ordering::SeqCst) {
        info.logger.log(msg);
        true
    } else {
        false
    }
}
fn set_logger(logger: Option<&'static LoggerInfo>) {
    LOGGER.store(logger, Ordering::SeqCst);
}

// Defining the standard out example logger
struct StdoutLogger;
impl Logger for StdoutLogger {
    fn log(&self, msg: &str) {
        stdout().write(msg.as_bytes());
    }
}
static STDOUT_LOGGER: LoggerInfo = LoggerInfo { logger: &StdoutLogger };

fn main() {
    let res = log("This will fail");
    assert!(!res);
    set_logger(Some(&STDOUT_LOGGER));
    let res = log("This will succeed");
    assert!(res);
}