Updated to handle CasError in wasm mapping, ensure new cas is returned to client

Signed-off-by: Darwin Boersma <[email protected]>

Author: ogghead

crates/factor-key-value/src/host.rs

@@ -358,6 +358,13 @@ impl wasi_keyvalue::atomics::HostCas for KeyValueDispatch {
 
 #[async_trait]
 impl wasi_keyvalue::atomics::Host for KeyValueDispatch {
+    fn convert_cas_error(
+        &mut self,
+        error: spin_world::wasi::keyvalue::atomics::CasError,
+    ) -> std::result::Result<spin_world::wasi::keyvalue::atomics::CasError, anyhow::Error> {
+        Ok(error)
+    }
+
     #[instrument(name = "spin_key_value.increment", skip(self, bucket, key, delta), err(level = Level::INFO), fields(otel.kind = "client"))]
     async fn increment(
         &mut self,
@@ -374,27 +381,29 @@ impl wasi_keyvalue::atomics::Host for KeyValueDispatch {
         &mut self,
         cas_res: Resource<atomics::Cas>,
         value: Vec<u8>,
-    ) -> Result<std::result::Result<(), CasError>> {
+    ) -> Result<(), CasError> {
         let cas_rep = cas_res.rep();
         let cas = self
             .get_cas(Resource::<Bucket>::new_own(cas_rep))
             .map_err(|e| CasError::StoreError(atomics::Error::Other(e.to_string())))?;
 
         match cas.swap(value).await {
-            Ok(_) => Ok(Ok(())),
+            Ok(_) => Ok(()),
             Err(err) => match err {
                 SwapError::CasFailed(_) => {
                     let bucket = Resource::new_own(cas.bucket_rep().await);
-                    let new_cas = self.new(bucket, cas.key().await).await?;
+                    let new_cas = self
+                        .new(bucket, cas.key().await)
+                        .await
+                        .map_err(CasError::StoreError)?;
                     let new_cas_rep = new_cas.rep();
-                    self.current(Resource::new_own(new_cas_rep)).await?;
-                    Err(anyhow::Error::new(CasError::CasFailed(Resource::new_own(
-                        new_cas_rep,
-                    ))))
+                    self.current(Resource::new_own(new_cas_rep))
+                        .await
+                        .map_err(CasError::StoreError)?;
+                    let res = Resource::new_own(new_cas_rep);
+                    Err(CasError::CasFailed(res))
                 }
-                SwapError::Other(msg) => Err(anyhow::Error::new(CasError::StoreError(
-                    atomics::Error::Other(msg),
-                ))),
+                SwapError::Other(msg) => Err(CasError::StoreError(atomics::Error::Other(msg))),
             },
         }
     }

crates/key-value-spin/src/store.rs

@@ -522,15 +522,10 @@ mod test {
         let res = kv.swap(Resource::new_own(cas.rep()), cas_final_value).await;
         match res {
             Ok(_) => panic!("expected a CAS failure"),
-            Err(err) => {
-                for cause in err.chain() {
-                    if let Some(cas_err) = cause.downcast_ref::<CasError>() {
-                        assert!(matches!(cas_err, CasError::CasFailed(_)));
-                        return Ok(());
-                    }
-                }
-                panic!("expected a CAS failure")
-            }
+            Err(err) => match err {
+                CasError::CasFailed(_) => Ok(()),
+                CasError::StoreError(_) => panic!("expected a CasFailed error"),
+            },
         }
     }
 

crates/world/src/lib.rs

@@ -33,6 +33,7 @@ wasmtime::component::bindgen!({
         "spin:postgres/postgres/error" => spin::postgres::postgres::Error,
         "wasi:config/[email protected]/error" => wasi::config::store::Error,
         "wasi:keyvalue/store/error" => wasi::keyvalue::store::Error,
+        "wasi:keyvalue/atomics/cas-error" => wasi::keyvalue::atomics::CasError,
     },
     trappable_imports: true,
 });

wit/deps/keyvalue-2024-10-17/atomic.wit

@@ -13,22 +13,22 @@ interface atomics {
 
   /// The error returned by a CAS operation
   variant cas-error {
-	/// A store error occurred when performing the operation
-	store-error(error),
+    /// A store error occurred when performing the operation
+    store-error(error),
 	  /// The CAS operation failed because the value was too old. This returns a new CAS handle
 	  /// for easy retries. Implementors MUST return a CAS handle that has been updated to the
 	  /// latest version or transaction.
-	cas-failed(cas),
+	  cas-failed(cas),
   }
 
   /// A handle to a CAS (compare-and-swap) operation.
   resource cas {
-	/// Construct a new CAS operation. Implementors can map the underlying functionality
-	/// (transactions, versions, etc) as desired.
-	new: static func(bucket: borrow<bucket>, key: string) -> result<cas, error>;
-	/// Get the current value of the key (if it exists). This allows for avoiding reads if all
-	/// that is needed to ensure the atomicity of the operation
-	current: func() -> result<option<list<u8>>, error>;
+    /// Construct a new CAS operation. Implementors can map the underlying functionality
+    /// (transactions, versions, etc) as desired.
+    new: static func(bucket: borrow<bucket>, key: string) -> result<cas, error>;
+    /// Get the current value of the key (if it exists). This allows for avoiding reads if all
+    /// that is needed to ensure the atomicity of the operation
+    current: func() -> result<option<list<u8>>, error>;
   }
 
   /// Atomically increment the value associated with the key in the store by the given delta. It

wit/deps/keyvalue-2024-10-17/world.wit

@@ -1,4 +1,4 @@
-package wasi: [email protected];
+package wasi:keyvalue@0.2.0-draft2;
 
 /// The `wasi:keyvalue/imports` world provides common APIs for interacting with key-value stores.
 /// Components targeting this world will be able to do: