rust处理全局变量的策略

Rust 的静态变量不会在程序退出时自动调用 Drop，因为它们的生命周期与进程绑定。

use std::sync::OnceLock;struct GlobalData {content: String,
}impl Drop for GlobalData {fn drop(&mut self) {println!("Cleaning up: {}", self.content);}
}static GLOBAL_DATA: OnceLock<GlobalData> = OnceLock::new();fn main() {GLOBAL_DATA.get_or_init(|| GlobalData {content: "Hello, world!".to_string(),});println!("Program is running...");// When the program exits, the Drop implementation for GlobalData is called.
}

Program is running...

方法1：在main中自动Drop全局变量

全局变量的生命周期应该和main的程序生命周期是一样长的，所以可以在main中创建一个CleanUp局部对象，为CleanUp()实现Drop特征，在Drop()特征中，完成释放全局变量的资源的功能。

struct Cleanup;impl Drop for Cleanup {fn drop(&mut self) {//调用某些全局变量的释放方法 或者 C库中的方法println!("Cleanup executed on program exit.");}
}fn main() {let _cleanup = Cleanup; // The `Drop` method will be called when `_cleanup` goes out of scopeprintln!("Program is running...");
}

测试：

Program is running...
Cleanup executed on program exit.

eg:

use std::sync::OnceLock;struct Cleanup;impl Drop for Cleanup {fn drop(&mut self) {GlobalData::free();println!("Cleanup executed on program exit.");}
}struct GlobalData {content: String,
}impl GlobalData{pub fn free(){println!("GlobalData::free...");}}static GLOBAL_DATA: OnceLock<GlobalData> = OnceLock::new();fn main() {GLOBAL_DATA.get_or_init(|| GlobalData {content: "Hello, world!".to_string(),});let _cleanup = Cleanup; // The `Drop` method will be called when `_cleanup` goes out of scopeprintln!("Program is running...");
}

Program is running...
GlobalData::free...
Cleanup executed on program exit.

参考