components/script/mem.rs


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

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

//! Routines for handling measuring the memory usage of arbitrary DOM nodes.

use dom::bindings::conversions::get_dom_class;
use dom::bindings::reflector::DomObject;
use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
use std::os::raw::c_void;

// This is equivalent to measuring a Box<T>, except that DOM objects lose their
// associated box in order to stash their pointers in a reserved slot of their
// JS reflector.
#[allow(unsafe_code)]
pub fn malloc_size_of_including_self<T: DomObject + MallocSizeOf>(
    ops: &mut MallocSizeOfOps, obj: &T) -> usize
{
    unsafe {
        let class = get_dom_class(obj.reflector().get_jsobject().get()).unwrap();
        (class.malloc_size_of)(ops, obj as *const T as *const c_void)
    }
}

/// Used by codegen to include the pointer to the `MallocSizeOf` implementation of each
/// IDL interface. This way we don't have to find the most-derived interface of DOM
/// objects by hand in code.
#[allow(unsafe_code)]
pub unsafe fn malloc_size_of_including_raw_self<T: MallocSizeOf>(
    ops: &mut MallocSizeOfOps, obj: *const c_void) -> usize
{
    ops.malloc_size_of(obj) + (*(obj as *const T)).size_of(ops)
}