nip10: fetch unknown replied-to notes

Signed-off-by: William Casarin <jb55@jb55.com>

src/timecache.rs

@@ -1,26 +1,40 @@
+use std::rc::Rc;
 use std::time::{Duration, Instant};
 
+#[derive(Clone)]
 pub struct TimeCached<T> {
     last_update: Instant,
     expires_in: Duration,
     value: Option<T>,
-    refresh: Box<dyn Fn() -> T + 'static>,
+    refresh: Rc<dyn Fn() -> T + 'static>,
 }
 
 impl<T> TimeCached<T> {
-    pub fn new(expires_in: Duration, refresh: Box<dyn Fn() -> T + 'static>) -> Self {
+    pub fn new(expires_in: Duration, refresh: impl Fn() -> T + 'static) -> Self {
         TimeCached {
             last_update: Instant::now(),
             expires_in,
             value: None,
-            refresh,
+            refresh: Rc::new(refresh),
         }
     }
 
-    pub fn get(&mut self) -> &T {
-        if self.value.is_none() || self.last_update.elapsed() > self.expires_in {
-            self.last_update = Instant::now();
-            self.value = Some((self.refresh)());
+    pub fn needs_update(&self) -> bool {
+        self.value.is_none() || self.last_update.elapsed() > self.expires_in
+    }
+
+    pub fn update(&mut self) {
+        self.last_update = Instant::now();
+        self.value = Some((self.refresh)());
+    }
+
+    pub fn get(&self) -> Option<&T> {
+        self.value.as_ref()
+    }
+
+    pub fn get_mut(&mut self) -> &T {
+        if self.needs_update() {
+            self.update();
         }
         self.value.as_ref().unwrap() // This unwrap is safe because we just set the value if it was None.
     }