dynamic - 如何在Rust中清除libloading的内部缓存

Question

如标题所示。对于具有相同路径的库，在libloading中似乎有一个内部缓存。我将如何清除它或从中丢弃物品。

以下mwe。

use libloading::{Library, Symbol};
use std::process::Command;

fn write(i: i64) {
    std::fs::write("source.rs", format!("
#[no_mangle]
pub extern \"C\" fn fun() {{
    println!(\"{}\");
}}", i)).expect("write error");
}

fn compile() {
    Command::new("rustc")
        .arg("--crate-type")
        .arg("cdylib")
        .arg("source.rs")
        .arg("-o")
        .arg("binary.o")
        .output()
        .expect("compile error");
}

fn run() {
    let lib = Library::new("./binary.o").unwrap();

    unsafe {
        lib.get::<Symbol<unsafe extern "C" fn()>>(b"fun").unwrap()()
    }
}

fn main() {
    for i in 0..10 {
        write(i);
        compile();
        run();
    }
}

退货

0
0
0
...

但是我想要

0
1
2
...

Answer 1

我最终重新发明了轮子。如果有人偶然发现相同的问题:

use libc;

use std::ffi::CStr;
use std::mem::transmute;

pub struct SharedLib {
    handle: *mut libc::c_void,
}

impl SharedLib {
    pub fn new(path: &str) -> Self {
        let path = CStr::from_bytes_with_nul(path.as_bytes()).unwrap();
        let handle = unsafe { libc::dlopen(path.as_ptr(), libc::RTLD_NOW) };

        SharedLib {
            handle: handle,
        }
    }

    pub fn run<T>(&self, name: &str) -> T {
        if self.handle.is_null() {
            panic!("error");
        }

        let name = CStr::from_bytes_with_nul(name.as_bytes()).unwrap();
        unsafe {
            let ptr = libc::dlsym(self.handle, name.as_ptr());
            transmute::<_, fn() -> T>(ptr)()
        }
    }
}

impl Drop for SharedLib {
    fn drop(&mut self) {
        unsafe {
            libc::dlclose(self.handle);
        }
    }
}