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use std::{borrow::Borrow, sync::Arc};
use arc_swap::{ArcSwap, Guard};
use im::HashMap;
use std::hash::Hash;
use tokio::sync::{mpsc, oneshot};
pub type AtomicOp<K, V> = Box<dyn FnOnce(&HashMap<K, V>) -> Option<HashMap<K, V>> + Send>;
enum MpmcMapMutationOp<
K: Send + Sync + Hash + Clone + Eq + 'static,
V: Send + Clone + Sync + 'static,
> {
Reset(Arc<HashMap<K, V>>),
Atomic(AtomicOp<K, V>),
Insert(K, V),
Remove(K),
}
enum MpmcMapMutationResponse<V: Send + Clone + Sync + 'static> {
None,
Bool(bool),
Value(V),
}
struct MpmcMapMutation<
K: Send + Sync + Hash + Clone + Eq + 'static,
V: Send + Clone + Sync + 'static,
> {
op: MpmcMapMutationOp<K, V>,
response: oneshot::Sender<MpmcMapMutationResponse<V>>,
}
#[derive(Debug)]
pub struct MpmcMap<K: Send + Sync + Hash + Clone + Eq + 'static, V: Send + Clone + Sync + 'static> {
inner: Arc<ArcSwap<HashMap<K, V>>>,
sender: mpsc::Sender<MpmcMapMutation<K, V>>,
}
impl<K: Send + Sync + Hash + Clone + Eq + 'static, V: Send + Clone + Sync + 'static> Default
for MpmcMap<K, V>
{
fn default() -> Self {
Self::new()
}
}
impl<K: Send + Sync + Hash + Clone + Eq + 'static, V: Send + Clone + Sync + 'static> Clone
for MpmcMap<K, V>
{
fn clone(&self) -> Self {
Self {
inner: self.inner.clone(),
sender: self.sender.clone(),
}
}
}
impl<K: Send + Sync + Hash + Clone + Eq + 'static, V: Send + Clone + Sync + 'static> MpmcMap<K, V> {
pub fn new() -> Self {
let (sender, receiver) = mpsc::channel(512);
let new_self = MpmcMap {
inner: Arc::new(ArcSwap::new(Arc::new(HashMap::new()))),
sender,
};
tokio::spawn(Self::updater(new_self.inner.clone(), receiver));
new_self
}
async fn updater(
map: Arc<ArcSwap<HashMap<K, V>>>,
mut receiver: mpsc::Receiver<MpmcMapMutation<K, V>>,
) {
while let Some(mutation) = receiver.recv().await {
match mutation.op {
MpmcMapMutationOp::Insert(key, value) => {
let map_load = map.load();
if let Some((old_value, prior)) = map_load.extract(&key) {
let new_map = prior.update(key, value);
map.store(Arc::new(new_map));
mutation
.response
.send(MpmcMapMutationResponse::Value(old_value))
.ok();
} else {
let new_map = map_load.update(key, value);
map.store(Arc::new(new_map));
mutation.response.send(MpmcMapMutationResponse::None).ok();
}
}
MpmcMapMutationOp::Remove(key) => {
if let Some((old_value, new_map)) = map.load().extract(&key) {
map.store(Arc::new(new_map));
mutation
.response
.send(MpmcMapMutationResponse::Value(old_value))
.ok();
} else {
mutation.response.send(MpmcMapMutationResponse::None).ok();
}
}
MpmcMapMutationOp::Reset(value) => {
map.store(value);
mutation.response.send(MpmcMapMutationResponse::None).ok();
}
MpmcMapMutationOp::Atomic(op) => {
let map_load = map.load();
let new_map = op(&**map_load);
let mutated = new_map.is_some();
if let Some(new_map) = new_map {
map.store(Arc::new(new_map));
}
mutation.response.send(MpmcMapMutationResponse::Bool(mutated)).ok();
}
}
}
}
pub async fn insert(&self, key: K, value: V) -> Option<V> {
let (response, receiver) = oneshot::channel::<MpmcMapMutationResponse<V>>();
self.sender
.send(MpmcMapMutation {
op: MpmcMapMutationOp::Insert(key, value),
response,
})
.await
.ok()
.expect("failed to send insert mutation");
match receiver
.await
.expect("failed to receive mpmc map mutation response")
{
MpmcMapMutationResponse::None => None,
MpmcMapMutationResponse::Bool(_) => None,
MpmcMapMutationResponse::Value(v) => Some(v),
}
}
pub async fn remove(&self, key: K) -> Option<V> {
let (response, receiver) = oneshot::channel::<MpmcMapMutationResponse<V>>();
self.sender
.send(MpmcMapMutation {
op: MpmcMapMutationOp::Remove(key),
response,
})
.await
.ok()
.expect("failed to send insert mutation");
match receiver
.await
.expect("failed to receive mpmc map mutation response")
{
MpmcMapMutationResponse::None => None,
MpmcMapMutationResponse::Bool(_) => None,
MpmcMapMutationResponse::Value(v) => Some(v),
}
}
pub fn get<BK: ?Sized>(&self, key: &BK) -> Option<V>
where
BK: Hash + Eq,
K: Borrow<BK>,
{
self.inner.load().get(key).cloned()
}
pub fn contains_key<BK: ?Sized>(&self, key: &BK) -> bool
where
BK: Hash + Eq,
K: Borrow<BK>,
{
self.inner.load().contains_key(key)
}
pub fn inner_full(&self) -> Arc<HashMap<K, V>> {
self.inner.load_full()
}
pub fn inner(&self) -> Guard<Arc<HashMap<K, V>>> {
self.inner.load()
}
#[doc(hidden)]
pub fn reset_now(&self, value: Arc<HashMap<K, V>>) {
self.inner.store(value);
}
pub async fn reset(&self, value: Arc<HashMap<K, V>>) {
let (response, receiver) = oneshot::channel::<MpmcMapMutationResponse<V>>();
self.sender
.send(MpmcMapMutation {
op: MpmcMapMutationOp::Reset(value),
response,
})
.await
.ok()
.expect("failed to send insert mutation");
receiver
.await
.expect("failed to receive mpmc map mutation response");
}
pub async fn atomic(&self, op: AtomicOp<K, V>) -> bool {
let (response, receiver) = oneshot::channel::<MpmcMapMutationResponse<V>>();
self.sender
.send(MpmcMapMutation {
op: MpmcMapMutationOp::Atomic(op),
response,
})
.await
.ok()
.expect("failed to send insert mutation");
match receiver
.await
.expect("failed to receive mpmc map mutation response")
{
MpmcMapMutationResponse::None => false,
MpmcMapMutationResponse::Bool(b) => b,
MpmcMapMutationResponse::Value(_) => false,
}
}
pub fn len(&self) -> usize {
self.inner().len()
}
pub fn is_empty(&self) -> bool {
self.inner().is_empty()
}
}