get system free memory in rust

main.rs
extern crate jemalloc_sys;

use std::mem;

fn main() {
    let mut mib = [jemalloc_sys::CTL_HW, jemalloc_sys::HW_MEMSIZE, jemalloc_sys::CTL_KERN, jemalloc_sys::KERN_USRSTACK64];
    let mut memsize: usize = mem::size_of::<usize>();
    unsafe {
        jemalloc_sys::mallctl(
            b"hw.pagesize\0".as_ptr() as *const i8,
            std::ptr::null_mut(),
            &mut memsize as *mut usize as *mut libc::c_void,
            &mut memsize,
            std::ptr::null(),
            0,
        );
        jemalloc_sys::mallctl(
            b"vm.stats.vm.v_free_count\0".as_ptr() as *const i8,
            std::ptr::null_mut(),
            &mut memsize as *mut usize as *mut libc::c_void,
            &mut memsize,
            std::ptr::null(),
            0,
        );
        let bytes = (memsize as u64) * (*mib.last().unwrap() as u64);
        println!("Free Memory: {:?}", bytes);
    }
}
902 chars
29 lines