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pub mod font;
pub mod user;
use std::future::Future;
use std::time::*;
use std::collections::HashMap;
use std::hash::Hash;
use std::sync::Arc;
use std::pin::Pin;
use tokio::sync::RwLock;
use reqwest::StatusCode;
#[derive(Debug)]
pub struct AsyncCache<K, V, F> {
func: F,
cache: HashMap<K, (Instant, V)>,
interval: Duration
}
impl<K, V, F, Fut> AsyncCache<K, V, F>
where
for<'a> F: FnMut(&'a K) -> Fut + 'a,
K: Hash + PartialEq + Eq + Clone,
Fut: Future<Output = Result<V, (StatusCode, &'static str)>> + Send + Sync
{
pub fn new(interval: Duration, func: F) -> Self {
Self{
cache: HashMap::new(),
interval, func
}
}
pub async fn get(&mut self, key: &K) -> Result<&V, (StatusCode, &'static str)> {
if self.is_stale(key) {
log::trace!("MISS : interval = {:?}", self.interval);
self.renew(key).await
} else {
log::trace!("HIT : interval = {:?}", self.interval);
Ok(&self.cache.get(key).unwrap().1)
}
}
pub async fn renew(&mut self, key: &K) -> Result<&V, (StatusCode, &'static str)> {
let val = (self.func)(key).await?;
self.cache.insert(key.clone(), (Instant::now(), val));
Ok(&self.cache.get(key).unwrap().1)
}
pub fn is_stale(&self, key: &K) -> bool {
if let Some((last_update, _)) = self.cache.get(key) {
let now = Instant::now();
log::trace!("Key exists, last update {:?} ago.", now - *last_update);
now > (*last_update + self.interval)
}
else { true }
}
pub async fn get_opt(&self, key: &K) -> Option<&V> {
if self.is_stale(key) {
self.cache.get(key).map(|(_, v)| v)
}
else { None }
}
pub fn interval(&self) -> Duration { self.interval }
}
impl<K, V, F, Fut> AsyncCache<K, V, F>
where
for<'a> F: FnMut(&'a K) -> Fut + 'a,
K: Hash + PartialEq + Eq + Clone,
V: Clone,
Fut: Future<Output = Result<V, (StatusCode, &'static str)>> + Send + Sync
{
pub async fn get_owned(&mut self, key: &K) -> Result<V, (StatusCode, &'static str)> {
self.get(key).await.cloned()
}
}
pub type CacheFuture<Output> = Pin<Box<(dyn Future<Output = Result<Output, (StatusCode, &'static str)>> + Send + Sync)>>;
pub type CacheGetter<Output> = fn(&String) -> CacheFuture<Output>;
pub type Cache<Output> = Arc<RwLock<AsyncCache<String, Output, CacheGetter<Output>>>>;
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