dyn_size_of 是 Piotr Beling 编写的 Rust 库，用于报告变量消耗的内存量，包括堆上分配的内存。

示例

简单使用

use dyn_size_of::GetSize;

let bs = vec![1u32, 2u32, 3u32].into_boxed_slice();
assert_eq!(bs.size_bytes_dyn(), 3*4);
assert_eq!(bs.size_bytes(), 3*4 + std::mem::size_of_val(&bs));

为自定义类型实现 GetSize

use dyn_size_of::GetSize;

struct NoHeapMem {
    a: u32,
    b: u8
}

// default implementation is fine for types that do not use heap allocations
impl GetSize for NoHeapMem {}

struct WithHeapMem {
    a: Vec<u32>,
    b: Vec<u8>,
    c: u32
}

// For types that use heap allocations:
impl GetSize for WithHeapMem {
    // size_bytes_dyn must be implemented and return amount of heap memory used
    fn size_bytes_dyn(&self) -> usize {
        self.a.size_bytes_dyn() + self.b.size_bytes_dyn()
    }
    // USES_DYN_MEM must be set to true
    const USES_DYN_MEM: bool = true;
}

let s = NoHeapMem { a: 1, b: 2 };
assert_eq!(NoHeapMem::USES_DYN_MEM, false);
assert_eq!(s.size_bytes_dyn(), 0);
assert_eq!(s.size_bytes(), std::mem::size_of_val(&s));

let d = WithHeapMem { a: vec![1, 2], b: vec![3, 4], c: 5 };
assert_eq!(WithHeapMem::USES_DYN_MEM, true);
assert_eq!(d.size_bytes_dyn(), 2*4 + 2*1);
assert_eq!(d.size_bytes(), 2*4 + 2*1 + std::mem::size_of_val(&d));