89 lines
2.3 KiB
Rust
89 lines
2.3 KiB
Rust
use std::{
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ptr,
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sync::{atomic::{AtomicPtr, AtomicU64, Ordering}, Arc, Mutex},
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time::{Duration, SystemTime, UNIX_EPOCH},
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};
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use tokio::spawn;
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use crate::error::{Error, Result};
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type UpdateFn<T> = Box<dyn Fn() -> Result<T>>;
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#[derive(Clone, Debug, Default)]
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pub struct Opts {
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return_last_good: bool,
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no_wait: bool,
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}
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pub struct Cache<T: Copy> {
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update_fn: UpdateFn<T>,
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ttl: Duration,
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opts: Opts,
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val: AtomicPtr<T>,
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last_update_ms: AtomicU64,
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updating: Arc<Mutex<bool>>,
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}
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impl<T: Copy> Cache<T> {
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pub fn new(update_fn: UpdateFn<T>, ttl: Duration, opts: Opts) -> Self {
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let val = AtomicPtr::new(ptr::null_mut());
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Self {
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update_fn,
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ttl,
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opts,
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val,
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last_update_ms: AtomicU64::new(0),
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updating: Arc::new(Mutex::new(false)),
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}
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}
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pub fn get(&self) -> Result<T> {
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let v_ptr = self.val.load(Ordering::SeqCst);
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let v = if v_ptr.is_null() { None } else { Some(unsafe { *v_ptr }) };
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let now = SystemTime::now()
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.duration_since(UNIX_EPOCH)
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.expect("Time went backwards")
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.as_secs();
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if v.is_some() && now - self.last_update_ms.load(Ordering::SeqCst) < self.ttl.as_secs() {
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return Ok(v.unwrap());
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}
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if self.opts.no_wait && v.is_some() && now - self.last_update_ms.load(Ordering::SeqCst) < self.ttl.as_secs() * 2 {
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if self.updating.try_lock().is_ok() {
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let this = self.clone();
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spawn(async {
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let _ = this.update().await;
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});
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self.update();
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}
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return Ok(v.unwrap());
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}
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match self.updating.lock() {
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Ok(_) => {
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if let Ok(duration) = SystemTime::now().duration_since(UNIX_EPOCH + Duration::from_secs(self.last_update_ms.load(Ordering::SeqCst))) {
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if duration < self.ttl {
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return Ok(v.unwrap());
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}
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}
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match self.update() {
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}
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},
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Err(err) => {
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return Err(Error::from_string(err.to_string()));
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}
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}
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todo!()
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}
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async fn update(&self) -> Result<()> {
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todo!()
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}
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}
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