leodos_protocols/transport/srspp/machine/receiver/utils/
bump_slab.rs

1/// Append-only bump allocator over a fixed byte buffer.
2pub struct BumpSlab<const N: usize> {
3    /// Backing byte storage.
4    data: [u8; N],
5    /// Number of bytes currently allocated.
6    len: usize,
7}
8
9impl<const N: usize> BumpSlab<N> {
10    /// Create a new empty slab.
11    pub const fn new() -> Self {
12        Self {
13            data: [0u8; N],
14            len: 0,
15        }
16    }
17
18    /// Append `payload` and return `(offset, len)`, or `None` if full.
19    pub fn alloc(&mut self, payload: &[u8]) -> Option<(usize, usize)> {
20        if self.len + payload.len() > N {
21            return None;
22        }
23        let offset = self.len;
24        self.data[offset..offset + payload.len()].copy_from_slice(payload);
25        self.len += payload.len();
26        Some((offset, payload.len()))
27    }
28
29    /// Get a slice of `len` bytes starting at `offset`.
30    pub fn get(&self, offset: usize, len: usize) -> &[u8] {
31        &self.data[offset..offset + len]
32    }
33
34    /// Reset the allocator, freeing all space.
35    pub fn clear(&mut self) {
36        self.len = 0;
37    }
38
39    /// Number of bytes currently allocated.
40    pub fn used(&self) -> usize {
41        self.len
42    }
43}
44
45#[cfg(test)]
46mod tests {
47    use super::*;
48
49    #[test]
50    fn bumpslab_alloc_get_clear() {
51        let mut slab = BumpSlab::<64>::new();
52        let (off1, len1) = slab.alloc(&[10, 20, 30]).unwrap();
53        let (off2, len2) = slab.alloc(&[40, 50]).unwrap();
54        assert_eq!(slab.get(off1, len1), &[10, 20, 30]);
55        assert_eq!(slab.get(off2, len2), &[40, 50]);
56        assert_eq!(slab.used(), 5);
57        slab.clear();
58        assert_eq!(slab.used(), 0);
59    }
60
61    #[test]
62    fn bumpslab_full() {
63        let mut slab = BumpSlab::<4>::new();
64        assert!(slab.alloc(&[1, 2, 3]).is_some());
65        assert!(slab.alloc(&[4, 5]).is_none());
66    }
67}
leodos_protocols/transport/srspp/machine/receiver/utils/bump_slab.rs

leodos_protocols/transport/srspp/machine/receiver/utils/
bump_slab.rs
