attempt at error refactoring

services/src/contexts/error.rs

@@ -0,0 +1,66 @@
+use snafu::Snafu;
+
+/// High-level error, reported to the user.
+#[derive(Debug, Snafu)]
+#[snafu(visibility(pub(crate)))]
+#[snafu(context(suffix(false)))] // disables default `Snafu` suffix
+pub enum ApplicationContextError {
+    CreateContext { source: InternalError },
+    SessionById { source: InternalError },
+}
+
+#[derive(Debug, Snafu)]
+#[snafu(visibility(pub(crate)))]
+#[snafu(context(suffix(false)))] // disables default `Snafu` suffix
+pub enum SimpleApplicationContextError {
+    DefaultSession { source: InternalError },
+    UpdateDefaultSessionProject { source: InternalError },
+    UpdateDefaultSessionView { source: InternalError },
+    DefaultSessionContext { source: InternalError },
+}
+
+#[derive(Debug, Snafu)]
+#[snafu(visibility(pub(crate)))]
+#[snafu(context(suffix(false)))] // disables default `Snafu` suffix
+pub enum SessionContextError {
+    Volumes,
+}
+
+/// Low-level internal error, not (directly) reported to the user.
+#[derive(Debug, Snafu)]
+#[snafu(visibility(pub(crate)))]
+#[snafu(context(suffix(false)))] // disables default `Snafu` suffix
+pub enum InternalError {
+    CouldNotGetPostgresConfig,
+    CouldNotGetSchemaStatus {
+        source: tokio_postgres::Error,
+    },
+    CouldNotGetClearDatabaseOnStartConfig {
+        source: tokio_postgres::Error,
+    },
+    #[snafu(display(
+        "Database cannot be cleared on startup because it was initially started without that setting."
+    ))]
+    ClearDatabaseOnStartupNotAllowed,
+    CouldNotRecreateDatabaseSchema {
+        source: tokio_postgres::Error,
+    },
+    CouldNotInitializeSchema {
+        source: tokio_postgres::Error,
+    },
+    CouldNotCreateDefaultSession {
+        source: tokio_postgres::Error,
+    },
+    CouldNotLoadDefaultSession {
+        source: tokio_postgres::Error,
+    },
+    InvalidSession,
+    Postgres {
+        source: tokio_postgres::Error,
+    },
+    Bb8 {
+        source: bb8_postgres::bb8::RunError<tokio_postgres::Error>,
+    },
+    // TODO: add source error from user db once it is refactored
+    CouldNotGetSessionById,
+}

services/src/contexts/mod.rs

@@ -1,5 +1,4 @@
 use crate::datasets::upload::Volume;
-use crate::error::Result;
 use crate::layers::listing::{DatasetLayerCollectionProvider, LayerCollectionProvider};
 use crate::layers::storage::{LayerDb, LayerProviderDb};
 use crate::tasks::{TaskContext, TaskManager};
@@ -16,6 +15,7 @@ use tokio::fs::File;
 use tokio::io::AsyncWriteExt;
 use tokio::sync::RwLock;
 
+pub mod error;
 mod postgres;
 mod session;
 mod simple_context;
@@ -34,10 +34,13 @@ use geoengine_operators::engine::{
 use geoengine_operators::mock::MockDatasetDataSourceLoadingInfo;
 use geoengine_operators::source::{GdalLoadingInfo, OgrSourceDataset};
 
+pub use error::ApplicationContextError;
 pub use postgres::{PostgresContext, PostgresDb, PostgresSessionContext};
 pub use session::{MockableSession, Session, SessionId, SimpleSession};
 pub use simple_context::SimpleApplicationContext;
 
+use self::error::SessionContextError;
+
 pub type Db<T> = Arc<RwLock<T>>;
 
 /// The application context bundles shared resources.
@@ -51,7 +54,10 @@ pub trait ApplicationContext: 'static + Send + Sync + Clone {
     fn session_context(&self, session: Self::Session) -> Self::SessionContext;
 
     /// Load a session by its id
-    async fn session_by_id(&self, session_id: SessionId) -> Result<Self::Session>;
+    async fn session_by_id(
+        &self,
+        session_id: SessionId,
+    ) -> Result<Self::Session, ApplicationContextError>;
 }
 
 /// The session context bundles resources that are specific to a session.
@@ -71,13 +77,13 @@ pub trait SessionContext: 'static + Send + Sync + Clone {
     fn tasks(&self) -> Self::TaskManager;
 
     /// Create a new query context for executing queries on processors
-    fn query_context(&self) -> Result<Self::QueryContext>;
+    fn query_context(&self) -> Result<Self::QueryContext, SessionContextError>;
 
     /// Create a new execution context initializing operators
-    fn execution_context(&self) -> Result<Self::ExecutionContext>;
+    fn execution_context(&self) -> Result<Self::ExecutionContext, SessionContextError>;
 
     /// Get the list of available data volumes
-    fn volumes(&self) -> Result<Vec<Volume>>;
+    fn volumes(&self) -> Result<Vec<Volume>, SessionContextError>;
 
     /// Get the current session
     fn session(&self) -> &Self::Session;