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-rwxr-xr-xsrc/lib.rs53
1 files changed, 31 insertions, 22 deletions
diff --git a/src/lib.rs b/src/lib.rs
index 61d667b..a77193f 100755
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,7 +10,7 @@ use core::{
cell::UnsafeCell,
cmp,
marker::PhantomData,
- mem,
+ mem::{self, MaybeUninit},
sync::atomic::{AtomicUsize, Ordering},
};
@@ -38,7 +38,7 @@ pub struct RingBuffer<T> {
// Backing store needs to be UnsafeCell to make sure it's not
// stored in read-only data sections.
- buf: UnsafeCell<[T; CAPACITY]>,
+ buf: UnsafeCell<MaybeUninit<[T; CAPACITY]>>,
}
impl<T> RingBuffer<T>
@@ -46,14 +46,11 @@ where
T: Copy,
{
/// Create a new RingBuffer.
- ///
- /// The `default` element isn't important, but is, unfortunately,
- /// currently required to make stable rust happy.
- pub const fn new(default: T) -> Self {
+ pub const fn new() -> Self {
Self {
head: AtomicUsize::new(0),
tail: AtomicUsize::new(0),
- buf: UnsafeCell::new([default; CAPACITY]),
+ buf: UnsafeCell::new(MaybeUninit::uninit()),
}
}
@@ -132,8 +129,8 @@ where
} else {
let nh = (h + 1) % CAPACITY;
let rc = unsafe {
- let buf = &mut *rb.buf.get();
- Some(*buf.get_unchecked(h))
+ let buf: &MaybeUninit<[T; CAPACITY]> = &*rb.buf.get();
+ Some(Self::load_val_at(h, buf))
};
rb.head.store(nh, Ordering::SeqCst);
rc
@@ -154,9 +151,9 @@ where
let len = cmp::min(mylen, buflen);
unsafe {
- let rbuf = &mut *rb.buf.get();
+ let rbuf: &MaybeUninit<[T; CAPACITY]> = &*rb.buf.get();
for i in 0..len {
- *buf.get_unchecked_mut(i) = *rbuf.get_unchecked(h);
+ *buf.get_unchecked_mut(i) = Self::load_val_at(h, rbuf);
h = (h + 1) % CAPACITY;
}
}
@@ -164,6 +161,12 @@ where
rb.head.store(h, Ordering::SeqCst);
len
}
+
+ #[inline(always)]
+ unsafe fn load_val_at(i: usize, buf: &MaybeUninit<[T; CAPACITY]>) -> T {
+ let b: &[T; CAPACITY] = &*buf.as_ptr();
+ *b.get_unchecked(i)
+ }
}
impl<T> Iterator for Reader<'_, T>
@@ -202,7 +205,7 @@ where
} else {
unsafe {
let buf = &mut *rb.buf.get();
- *buf.get_unchecked_mut(t) = v;
+ Self::store_val_at(t, buf, v);
}
rb.tail.store(nt, Ordering::SeqCst);
Ok(())
@@ -225,7 +228,7 @@ where
unsafe {
let rbuf = &mut *rb.buf.get();
for i in 0..len {
- *rbuf.get_unchecked_mut(t) = *buf.get_unchecked(i);
+ Self::store_val_at(t, rbuf, *buf.get_unchecked(i));
t = (t + 1) % CAPACITY;
}
}
@@ -233,6 +236,12 @@ where
rb.tail.store(t, Ordering::SeqCst);
len
}
+
+ #[inline(always)]
+ unsafe fn store_val_at(i: usize, buf: &mut MaybeUninit<[T; CAPACITY]>, val: T) {
+ let b: &mut [T; CAPACITY] = &mut *buf.as_mut_ptr();
+ *b.get_unchecked_mut(i) = val
+ }
}
#[cfg(test)]
@@ -241,7 +250,7 @@ mod test {
#[test]
fn detects_empty() {
- let rb = RingBuffer::<bool>::new(false);
+ let rb = RingBuffer::<bool>::new();
let (mut rbr, mut rbw) = rb.split();
assert!(rbr.is_empty());
rbw.unshift(true).ok();
@@ -252,7 +261,7 @@ mod test {
#[test]
fn len_matches() {
- let rb = RingBuffer::<bool>::new(false);
+ let rb = RingBuffer::<bool>::new();
let (mut rbr, mut rbw) = rb.split();
// Count length up.
@@ -273,7 +282,7 @@ mod test {
#[test]
fn can_wrap() {
- let rb = RingBuffer::<usize>::new(0);
+ let rb = RingBuffer::<usize>::new();
let (mut rbr, mut rbw) = rb.split();
// Make sure we can store n-1 elements.
@@ -289,7 +298,7 @@ mod test {
#[test]
fn cannot_overwrite() {
- let rb = RingBuffer::<usize>::new(0);
+ let rb = RingBuffer::<usize>::new();
let (mut rbr, mut rbw) = rb.split();
for i in 0..CAPACITY - 1 {
@@ -304,7 +313,7 @@ mod test {
#[test]
fn can_iter() {
- let rb = RingBuffer::<usize>::new(0);
+ let rb = RingBuffer::<usize>::new();
let (rbr, mut rbw) = rb.split();
for i in 0..CAPACITY - 1 {
@@ -320,7 +329,7 @@ mod test {
#[test]
fn shift_into_smaller() {
- let rb = RingBuffer::<usize>::new(0);
+ let rb = RingBuffer::<usize>::new();
let (mut rbr, mut rbw) = rb.split();
for i in 0..CAPACITY - 1 {
assert_eq!(rbw.unshift(i), Ok(()));
@@ -337,7 +346,7 @@ mod test {
#[test]
fn shift_into_bigger() {
- let rb = RingBuffer::<usize>::new(0);
+ let rb = RingBuffer::<usize>::new();
let (mut rbr, mut rbw) = rb.split();
for i in 0..CAPACITY - 1 {
assert_eq!(rbw.unshift(i), Ok(()));
@@ -357,7 +366,7 @@ mod test {
#[test]
fn unshift_from_smaller() {
- let rb = RingBuffer::<usize>::new(0);
+ let rb = RingBuffer::<usize>::new();
let (mut rbr, mut rbw) = rb.split();
let buf: [usize; CAPACITY / 2] = [0xdead; CAPACITY / 2];
@@ -370,7 +379,7 @@ mod test {
#[test]
fn unshift_from_bigger() {
- let rb = RingBuffer::<usize>::new(0);
+ let rb = RingBuffer::<usize>::new();
let (mut rbr, mut rbw) = rb.split();
let buf: [usize; CAPACITY * 2] = [0xdead; CAPACITY * 2];