fix(shared-error): carry backtrace on the first cast to anyhow error (#1044)

Author: georgeh0

src/builder/analyzed_flow.rs

@@ -41,7 +41,7 @@ impl AnalyzedFlow {
     }
 
     pub async fn get_execution_plan(&self) -> Result<Arc<plan::ExecutionPlan>> {
-        let execution_plan = self.execution_plan.clone().await.std_result()?;
+        let execution_plan = self.execution_plan.clone().await.anyhow_result()?;
         Ok(execution_plan)
     }
 }

src/execution/memoization.rs

@@ -247,7 +247,7 @@ where
                 async move { fut.await.map_err(SharedError::new) }
             })
             .await
-            .std_result()?,
+            .anyhow_result()?,
         ),
         None => Cow::Owned(compute().await?),
     };

src/execution/source_indexer.rs

@@ -531,7 +531,7 @@ impl SourceIndexingContext {
                 pending_update_fut
             }
         };
-        pending_update_fut.await.std_result()?;
+        pending_update_fut.await.anyhow_result()?;
         Ok(())
     }
 

src/service/error.rs

@@ -71,45 +71,91 @@ impl From<ApiError> for PyErr {
     }
 }
 
+pub struct ResidualErrorData {
+    message: String,
+    debug: String,
+}
+
 #[derive(Clone)]
-pub struct SharedError {
-    pub err: Arc<anyhow::Error>,
+pub struct ResidualError(Arc<ResidualErrorData>);
+
+impl Display for ResidualError {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "{}", self.0.message)
+    }
+}
+
+impl Debug for ResidualError {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "{}", self.0.debug)
+    }
+}
+
+impl Error for ResidualError {}
+
+enum SharedErrorState {
+    Anyhow(anyhow::Error),
+    ResidualErrorMessage(ResidualError),
 }
 
+/// SharedError allows to be cloned.
+/// The original `anyhow::Error` can be extracted once, and later it decays to `ResidualError` which preserves the message and debug information.
+#[derive(Clone)]
+pub struct SharedError(Arc<Mutex<SharedErrorState>>);
+
 impl SharedError {
     pub fn new(err: anyhow::Error) -> Self {
-        Self { err: Arc::new(err) }
+        Self(Arc::new(Mutex::new(SharedErrorState::Anyhow(err))))
+    }
+
+    fn extract_anyhow_error(&self) -> anyhow::Error {
+        let mut state = self.0.lock().unwrap();
+        let mut_state = &mut *state;
+
+        let residual_err = match mut_state {
+            SharedErrorState::ResidualErrorMessage(err) => {
+                return anyhow::Error::from(err.clone());
+            }
+            SharedErrorState::Anyhow(err) => ResidualError(Arc::new(ResidualErrorData {
+                message: format!("{}", err),
+                debug: format!("{:?}", err),
+            })),
+        };
+        let orig_state = std::mem::replace(
+            mut_state,
+            SharedErrorState::ResidualErrorMessage(residual_err),
+        );
+        let SharedErrorState::Anyhow(err) = orig_state else {
+            panic!("Expected anyhow error");
+        };
+        err
     }
 }
 impl Debug for SharedError {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        Debug::fmt(&self.err, f)
+        let state = self.0.lock().unwrap();
+        match &*state {
+            SharedErrorState::Anyhow(err) => Debug::fmt(err, f),
+            SharedErrorState::ResidualErrorMessage(err) => Debug::fmt(err, f),
+        }
     }
 }
 
 impl Display for SharedError {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        Display::fmt(&self.err, f)
+        let state = self.0.lock().unwrap();
+        match &*state {
+            SharedErrorState::Anyhow(err) => Display::fmt(err, f),
+            SharedErrorState::ResidualErrorMessage(err) => Display::fmt(err, f),
+        }
     }
 }
 
 impl<E: std::error::Error + Send + Sync + 'static> From<E> for SharedError {
     fn from(err: E) -> Self {
-        Self {
-            err: Arc::new(anyhow::Error::from(err)),
-        }
-    }
-}
-
-impl AsRef<dyn std::error::Error> for SharedError {
-    fn as_ref(&self) -> &(dyn std::error::Error + 'static) {
-        self.err.as_ref().as_ref()
-    }
-}
-
-impl AsRef<dyn std::error::Error + Send + Sync> for SharedError {
-    fn as_ref(&self) -> &(dyn std::error::Error + Send + Sync + 'static) {
-        self.err.as_ref().as_ref()
+        Self(Arc::new(Mutex::new(SharedErrorState::Anyhow(
+            anyhow::Error::from(err),
+        ))))
     }
 }
 
@@ -119,48 +165,28 @@ pub fn shared_ok<T>(value: T) -> Result<T, SharedError> {
 
 pub type SharedResult<T> = Result<T, SharedError>;
 
-pub struct SharedErrorWrapper(SharedError);
-
-impl Display for SharedErrorWrapper {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        Display::fmt(&self.0, f)
-    }
-}
-
-impl Debug for SharedErrorWrapper {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        Debug::fmt(&self.0, f)
-    }
-}
-
-impl Error for SharedErrorWrapper {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        self.0.err.as_ref().source()
-    }
-}
-
 pub trait SharedResultExt<T> {
-    fn std_result(self) -> Result<T, SharedErrorWrapper>;
+    fn anyhow_result(self) -> Result<T, anyhow::Error>;
 }
 
 impl<T> SharedResultExt<T> for Result<T, SharedError> {
-    fn std_result(self) -> Result<T, SharedErrorWrapper> {
+    fn anyhow_result(self) -> Result<T, anyhow::Error> {
         match self {
             Ok(value) => Ok(value),
-            Err(err) => Err(SharedErrorWrapper(err)),
+            Err(err) => Err(err.extract_anyhow_error()),
         }
     }
 }
 
 pub trait SharedResultExtRef<'a, T> {
-    fn std_result(self) -> Result<&'a T, SharedErrorWrapper>;
+    fn anyhow_result(self) -> Result<&'a T, anyhow::Error>;
 }
 
 impl<'a, T> SharedResultExtRef<'a, T> for &'a Result<T, SharedError> {
-    fn std_result(self) -> Result<&'a T, SharedErrorWrapper> {
+    fn anyhow_result(self) -> Result<&'a T, anyhow::Error> {
         match self {
             Ok(value) => Ok(value),
-            Err(err) => Err(SharedErrorWrapper(err.clone())),
+            Err(err) => Err(err.extract_anyhow_error()),
         }
     }
 }