simplify background tasks with SessionSnapshot (#289)

Author: joshuadavidthomas

crates/djls-server/src/server.rs

@@ -19,6 +19,7 @@ use crate::ext::TextDocumentIdentifierExt;
 use crate::ext::UriExt;
 use crate::queue::Queue;
 use crate::session::Session;
+use crate::session::SessionSnapshot;
 
 const SERVER_NAME: &str = "Django Language Server";
 const SERVER_VERSION: &str = "0.1.0";
@@ -59,12 +60,15 @@ impl DjangoLanguageServer {
 
     pub async fn with_session_task<F, Fut>(&self, f: F)
     where
-        F: FnOnce(Arc<Mutex<Session>>) -> Fut + Send + 'static,
+        F: FnOnce(SessionSnapshot) -> Fut + Send + 'static,
         Fut: Future<Output = anyhow::Result<()>> + Send + 'static,
     {
-        let session_arc = Arc::clone(&self.session);
+        let snapshot = {
+            let session = self.session.lock().await;
+            session.snapshot()
+        };
 
-        if let Err(e) = self.queue.submit(async move { f(session_arc).await }).await {
+        if let Err(e) = self.queue.submit(async move { f(snapshot).await }).await {
             tracing::error!("Failed to submit task: {}", e);
         } else {
             tracing::info!("Task submitted successfully");
@@ -174,10 +178,8 @@ impl LanguageServer for DjangoLanguageServer {
     async fn initialized(&self, _params: lsp_types::InitializedParams) {
         tracing::info!("Server received initialized notification.");
 
-        self.with_session_task(move |session_arc| async move {
-            let session = session_arc.lock().await;
-
-            if let Some(project) = session.project() {
+        self.with_session_task(move |session| async move {
+            if let Some(project) = session.db().project() {
                 let path = project.root(session.db()).clone();
                 tracing::info!("Task: Starting initialization for project at: {}", path);
                 project.initialize(session.db());

crates/djls-server/src/session.rs

@@ -71,6 +71,10 @@ impl Session {
         }
     }
 
+    pub fn snapshot(&self) -> SessionSnapshot {
+        SessionSnapshot::new(self.db.clone(), self.client_capabilities)
+    }
+
     pub fn client_capabilities(&self) -> ClientCapabilities {
         self.client_capabilities
     }
@@ -193,6 +197,30 @@ impl Default for Session {
     }
 }
 
+/// Immutable snapshot of session state for background tasks
+#[derive(Clone)]
+pub struct SessionSnapshot {
+    db: DjangoDatabase,
+    client_capabilities: ClientCapabilities,
+}
+
+impl SessionSnapshot {
+    pub fn new(db: DjangoDatabase, client_capabilities: ClientCapabilities) -> Self {
+        Self {
+            db,
+            client_capabilities,
+        }
+    }
+
+    pub fn db(&self) -> &DjangoDatabase {
+        &self.db
+    }
+
+    pub fn client_capabilities(&self) -> ClientCapabilities {
+        self.client_capabilities
+    }
+}
+
 #[derive(Debug, Clone, Copy)]
 pub struct ClientCapabilities {
     pull_diagnostics: bool,
@@ -334,6 +362,21 @@ mod tests {
         assert_eq!(content, "updated");
     }
 
+    #[test]
+    fn test_snapshot_creation() {
+        let session = Session::default();
+        let snapshot = session.snapshot();
+
+        assert_eq!(
+            session.client_capabilities().position_encoding(),
+            snapshot.client_capabilities().position_encoding()
+        );
+        assert_eq!(
+            session.project().is_some(),
+            snapshot.db().project().is_some()
+        );
+    }
+
     #[test]
     fn test_negotiate_prefers_utf8_when_available() {
         let capabilities = lsp_types::ClientCapabilities {