garage/src/util/sled_counter.rs

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use std::sync::{
atomic::{AtomicUsize, Ordering},
Arc,
};
use sled::{CompareAndSwapError, IVec, Iter, Result, Tree};
#[derive(Clone)]
pub struct SledCountedTree(Arc<SledCountedTreeInternal>);
struct SledCountedTreeInternal {
tree: Tree,
len: AtomicUsize,
}
impl SledCountedTree {
pub fn new(tree: Tree) -> Self {
let len = tree.len();
Self(Arc::new(SledCountedTreeInternal {
tree,
len: AtomicUsize::new(len),
}))
}
pub fn len(&self) -> usize {
self.0.len.load(Ordering::Relaxed)
}
pub fn is_empty(&self) -> bool {
self.0.tree.is_empty()
}
pub fn get<K: AsRef<[u8]>>(&self, key: K) -> Result<Option<IVec>> {
self.0.tree.get(key)
}
pub fn iter(&self) -> Iter {
self.0.tree.iter()
}
// ---- writing functions ----
pub fn insert<K, V>(&self, key: K, value: V) -> Result<Option<IVec>>
where
K: AsRef<[u8]>,
V: Into<IVec>,
{
let res = self.0.tree.insert(key, value);
if res == Ok(None) {
self.0.len.fetch_add(1, Ordering::Relaxed);
}
res
}
pub fn pop_min(&self) -> Result<Option<(IVec, IVec)>> {
let res = self.0.tree.pop_min();
if let Ok(Some(_)) = &res {
self.0.len.fetch_sub(1, Ordering::Relaxed);
};
res
}
pub fn compare_and_swap<K, OV, NV>(
&self,
key: K,
old: Option<OV>,
new: Option<NV>,
) -> Result<std::result::Result<(), CompareAndSwapError>>
where
K: AsRef<[u8]>,
OV: AsRef<[u8]>,
NV: Into<IVec>,
{
let old_some = old.is_some();
let new_some = new.is_some();
let res = self.0.tree.compare_and_swap(key, old, new);
if res == Ok(Ok(())) {
match (old_some, new_some) {
(false, true) => {
self.0.len.fetch_add(1, Ordering::Relaxed);
}
(true, false) => {
self.0.len.fetch_sub(1, Ordering::Relaxed);
}
_ => (),
}
}
res
}
}