refactor

veilid-tools/src/single_shot_eventual.rs

@@ -0,0 +1,44 @@
+use super::*;
+
+pub struct SingleShotEventual<T>
+where
+    T: Unpin,
+{
+    eventual: EventualValue<T>,
+    drop_value: Option<T>,
+}
+
+impl<T> Drop for SingleShotEventual<T>
+where
+    T: Unpin,
+{
+    fn drop(&mut self) {
+        if let Some(drop_value) = self.drop_value.take() {
+            self.eventual.resolve(drop_value);
+        }
+    }
+}
+
+impl<T> SingleShotEventual<T>
+where
+    T: Unpin,
+{
+    pub fn new(drop_value: Option<T>) -> Self {
+        Self {
+            eventual: EventualValue::new(),
+            drop_value,
+        }
+    }
+
+    // Can only call this once, it consumes the eventual
+    pub fn resolve(mut self, value: T) -> EventualResolvedFuture<EventualValue<T>> {
+        // If we resolve, we don't want to resolve again to the drop value
+        self.drop_value = None;
+        // Resolve to the specified value
+        self.eventual.resolve(value)
+    }
+
+    pub fn instance(&self) -> EventualValueFuture<T> {
+        self.eventual.instance()
+    }
+}