fix: DecisionLoader and downcast trait (#414)

core/engine/Cargo.toml

@@ -28,9 +28,9 @@ zen-types = { path = "../types", version = "0.51.1" }
 zen-expression = { path = "../expression", version = "0.51.1" }
 zen-tmpl = { path = "../template", version = "0.51.1" }
 nohash-hasher = { workspace = true }
+downcast-rs = { version = "2.0", features = ["std", "sync"] }
 
 [dev-dependencies]
-chrono = { workspace = true }
 tokio = { workspace = true, features = ["rt-multi-thread", "macros"] }
 criterion = { workspace = true, features = ["async_tokio"] }
 insta = { version = "1.43", features = ["yaml", "redactions"] }

core/engine/src/engine.rs

@@ -182,4 +182,7 @@ impl DecisionEngine {
         let content = self.loader.load(key).await?;
         Ok(self.create_decision(content))
     }
+    pub fn loader(&self) -> DynamicLoader {
+        self.loader.clone()
+    }
 }

core/engine/src/loader/closure.rs

@@ -32,7 +32,7 @@ where
 
 impl<F, O> DecisionLoader for ClosureLoader<F>
 where
-    F: Fn(String) -> O + Sync + Send,
+    F: Fn(String) -> O + Sync + Send + 'static,
     O: Future<Output = LoaderResponse> + Send,
 {
     fn load<'a>(

core/engine/src/loader/mod.rs

@@ -1,8 +1,8 @@
+use downcast_rs::{impl_downcast, DowncastSync};
 use std::fmt::Debug;
 use std::future::Future;
 use std::pin::Pin;
 use std::sync::Arc;
-
 use thiserror::Error;
 
 pub use cached::CachedLoader;
@@ -19,19 +19,21 @@ mod filesystem;
 mod memory;
 mod noop;
 
-pub type DynamicLoader = Arc<dyn DecisionLoader + Send + Sync>;
+pub type DynamicLoader = Arc<dyn DecisionLoader>;
 
 pub type LoaderResult<T> = Result<T, LoaderError>;
 pub type LoaderResponse = LoaderResult<Arc<DecisionContent>>;
 
 /// Trait used for implementing a loader for decisions
-pub trait DecisionLoader: Debug + Send {
+pub trait DecisionLoader: Debug + Send + Sync + DowncastSync {
     fn load<'a>(
         &'a self,
         key: &'a str,
     ) -> Pin<Box<dyn Future<Output = LoaderResponse> + 'a + Send>>;
 }
 
+impl_downcast!(sync DecisionLoader);
+
 #[derive(Error, Debug)]
 pub enum LoaderError {
     #[error("Loader did not find item with key {0}")]