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Versions: 8
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Stored size: 1.72 KB
Contents
#![allow(clippy::all)]
// only used on Linux right now, so allow dead code elsewhere
#![cfg_attr(not(target_os = "linux"), allow(dead_code))]
use super::Mmap;
use alloc::vec;
use alloc::vec::Vec;
use core::cell::UnsafeCell;
/// A simple arena allocator for byte buffers.
pub struct Stash {
buffers: UnsafeCell<Vec<Vec<u8>>>,
mmaps: UnsafeCell<Vec<Mmap>>,
}
impl Stash {
pub fn new() -> Stash {
Stash {
buffers: UnsafeCell::new(Vec::new()),
mmaps: 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]
}
/// Stores a `Mmap` for the lifetime of this `Stash`, returning a pointer
/// which is scoped to just this lifetime.
pub fn cache_mmap(&self, map: Mmap) -> &[u8] {
// SAFETY: this is the only location for a mutable pointer to
// `mmaps`, and this structure isn't threadsafe to shared across
// threads either. We also never remove elements from `self.mmaps`,
// so a reference to the data inside the map will live as long as
// `self` does.
unsafe {
let mmaps = &mut *self.mmaps.get();
mmaps.push(map);
mmaps.last().unwrap()
}
}
}
Version data entries
8 entries across 8 versions & 1 rubygems