1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49

use std::ptr;
use std::cell::RefCell;

use page::Page;

thread_local!(static CURRENT_PAGE: RefCell<*mut Page> = RefCell::new(ptr::null_mut()));

pub struct Region {
    current_page: *mut Page,
}

impl Region {
    pub fn get() -> Region {
        unsafe {
            let current_page = Region::get_page();
            if current_page.is_null() {
                panic!("Out of memory.");
            }

            Region { current_page: current_page }
        }
    }

    unsafe fn get_page() -> *mut Page {
        let mut page: *mut Page = ptr::null_mut();
        CURRENT_PAGE.with(|p| {
            let pagerefborrow = *p.borrow();
            if pagerefborrow.is_null() {
                *p.borrow_mut() = Page::next(ptr::null_mut());
            }

            page = *p.borrow();
        });

        page
    }

    pub fn get_current_page(&self) -> *mut Page {
        self.current_page
    }
}

impl Drop for Region {
    fn drop(&mut self) {
        unsafe {
            (*(self.current_page)).deallocate();
        }
    }
}