Merge pull request #1087 from muzarski/pubify-arced-errors

errors: expose pub getters for type-erased errors

Author: Lorak-mmk

scylla-cql/src/types/deserialize/mod.rs

@@ -179,7 +179,6 @@ pub use row::DeserializeRow;
 pub use value::DeserializeValue;
 
 use std::error::Error;
-use std::fmt::Display;
 use std::sync::Arc;
 
 use thiserror::Error;
@@ -202,7 +201,7 @@ use thiserror::Error;
 ///   It won't be returned by the `Session` directly, but it might be nested
 ///   in the [`row::BuiltinTypeCheckError`].
 #[derive(Debug, Clone, Error)]
-#[error(transparent)]
+#[error("TypeCheckError: {0}")]
 pub struct TypeCheckError(pub(crate) Arc<dyn std::error::Error + Send + Sync>);
 
 impl TypeCheckError {
@@ -211,6 +210,11 @@ impl TypeCheckError {
     pub fn new(err: impl std::error::Error + Send + Sync + 'static) -> Self {
         Self(Arc::new(err))
     }
+
+    /// Retrieve an error reason by downcasting to specific type.
+    pub fn downcast_ref<T: std::error::Error + 'static>(&self) -> Option<&T> {
+        self.0.downcast_ref()
+    }
 }
 
 /// An error indicating that a failure happened during deserialization.
@@ -228,6 +232,7 @@ impl TypeCheckError {
 ///   It won't be returned by the `Session` directly, but it might be nested
 ///   in the [`row::BuiltinDeserializationError`].
 #[derive(Debug, Clone, Error)]
+#[error("DeserializationError: {0}")]
 pub struct DeserializationError(Arc<dyn Error + Send + Sync>);
 
 impl DeserializationError {
@@ -236,11 +241,10 @@ impl DeserializationError {
     pub fn new(err: impl Error + Send + Sync + 'static) -> Self {
         Self(Arc::new(err))
     }
-}
 
-impl Display for DeserializationError {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "DeserializationError: {}", self.0)
+    /// Retrieve an error reason by downcasting to specific type.
+    pub fn downcast_ref<T: Error + 'static>(&self) -> Option<&T> {
+        self.0.downcast_ref()
     }
 }
 

scylla-cql/src/types/serialize/mod.rs

@@ -2,7 +2,7 @@
 
 //! Types and traits related to serialization of values to the CQL format.
 
-use std::{error::Error, fmt::Display, sync::Arc};
+use std::{error::Error, sync::Arc};
 
 use thiserror::Error;
 
@@ -33,6 +33,7 @@ pub use writers::{CellValueBuilder, CellWriter, RowWriter};
 ///   as an argument to the statement, and rewriting it using the new
 ///   `SerializeRow` interface fails.
 #[derive(Debug, Clone, Error)]
+#[error("SerializationError: {0}")]
 pub struct SerializationError(Arc<dyn Error + Send + Sync>);
 
 impl SerializationError {
@@ -41,10 +42,9 @@ impl SerializationError {
     pub fn new(err: impl Error + Send + Sync + 'static) -> SerializationError {
         SerializationError(Arc::new(err))
     }
-}
 
-impl Display for SerializationError {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "SerializationError: {}", self.0)
+    /// Retrieve an error reason by downcasting to specific type.
+    pub fn downcast_ref<T: Error + 'static>(&self) -> Option<&T> {
+        self.0.downcast_ref()
     }
 }

scylla/src/transport/connection.rs

@@ -2780,7 +2780,7 @@ mod tests {
         let err = error_receiver.await.unwrap();
         let err_inner: &BrokenConnectionErrorKind = match err {
             crate::transport::connection::ConnectionError::BrokenConnection(ref e) => {
-                e.get_reason().downcast_ref().unwrap()
+                e.downcast_ref().unwrap()
             }
             _ => panic!("Bad error type. Expected keepalive timeout."),
         };

scylla/src/transport/errors.rs

@@ -740,15 +740,15 @@ impl ConnectionSetupRequestError {
 pub struct BrokenConnectionError(Arc<dyn Error + Sync + Send>);
 
 impl BrokenConnectionError {
-    /// Retrieve an error reason.
-    pub fn get_reason(&self) -> &Arc<dyn Error + Sync + Send> {
-        &self.0
+    /// Retrieve an error reason by downcasting to specific type.
+    pub fn downcast_ref<T: Error + 'static>(&self) -> Option<&T> {
+        self.0.downcast_ref()
     }
 }
 
 /// A reason why connection was broken.
 ///
-/// See [`BrokenConnectionError::get_reason()`].
+/// See [`BrokenConnectionError::downcast_ref()`].
 /// You can retrieve the actual type by downcasting `Arc<dyn Error>`.
 #[derive(Error, Debug)]
 #[non_exhaustive]