| use std::cell::UnsafeCell; |
| use std::vec::Vec; |
| |
| /// A simple arena allocator for byte buffers. |
| pub struct Stash { |
| buffers: UnsafeCell<Vec<Vec<u8>>>, |
| } |
| |
| impl Stash { |
| pub fn new() -> Stash { |
| Stash { |
| buffers: UnsafeCell::new(Vec::new()), |
| } |
| } |
| |
| /// Allocates a buffer of the specified size and returns a mutable reference |
| /// to it. |
| pub fn allocate(&self, size: usize) -> &mut [u8] { |
| // SAFETY: this is the only function that ever constructs a mutable |
| // reference to `self.buffers`. |
| let buffers = unsafe { &mut *self.buffers.get() }; |
| let i = buffers.len(); |
| buffers.push(vec![0; size]); |
| // SAFETY: we never remove elements from `self.buffers`, so a reference |
| // to the data inside any buffer will live as long as `self` does. |
| &mut buffers[i] |
| } |
| } |