From d9db07db2a377f8cfcf43b42ad9a35074b77173f Mon Sep 17 00:00:00 2001
From: Simon Hausmann <simon.hausmann@sixtyfps.io>
Date: Tue, 6 Apr 2021 11:10:30 +0200
Subject: [PATCH] Try to gracefully terminate the LSP server when requested

---
 tools/lsp/main.rs    | 58 ++++++++++++++++++++++++--------------------
 tools/lsp/preview.rs |  6 +++++
 2 files changed, 38 insertions(+), 26 deletions(-)

diff --git a/tools/lsp/main.rs b/tools/lsp/main.rs
index 58a7978bc..93acf707a 100644
--- a/tools/lsp/main.rs
+++ b/tools/lsp/main.rs
@@ -45,7 +45,15 @@ impl<'a> DocumentCache<'a> {
 }
 
 fn main() {
-    start_lsp_thread();
+    std::thread::spawn(|| {
+        match run_lsp_server() {
+            Ok(_) => {}
+            Err(error) => {
+                eprintln!("Error running LSP server: {}", error);
+            }
+        }
+        preview::quit_ui_event_loop();
+    });
     // TODO: Don't terminate the event loop when the window is closed with Qt
     // TODO: There's a race condition where theoretically the LSP could receive a preview
     // request before the gui event loop has started, which would cause post_event to panic.
@@ -54,32 +62,30 @@ fn main() {
     preview::start_ui_event_loop();
 }
 
-fn start_lsp_thread() {
-    std::thread::spawn(|| {
-        let (connection, io_threads) = Connection::stdio();
-        let capabilities = ServerCapabilities {
-            completion_provider: Some(CompletionOptions {
-                resolve_provider: Some(true),
-                trigger_characters: None,
-                work_done_progress_options: WorkDoneProgressOptions::default(),
-            }),
-            hover_provider: Some(HoverProviderCapability::Simple(true)),
-            document_highlight_provider: Some(OneOf::Left(true)),
-            document_symbol_provider: Some(OneOf::Left(true)),
-            workspace_symbol_provider: Some(OneOf::Left(true)),
-            definition_provider: Some(OneOf::Left(true)),
-            text_document_sync: Some(TextDocumentSyncCapability::Kind(
-                lsp_types::TextDocumentSyncKind::Full,
-            )),
+fn run_lsp_server() -> Result<(), Error> {
+    let (connection, io_threads) = Connection::stdio();
+    let capabilities = ServerCapabilities {
+        completion_provider: Some(CompletionOptions {
+            resolve_provider: Some(true),
+            trigger_characters: None,
+            work_done_progress_options: WorkDoneProgressOptions::default(),
+        }),
+        hover_provider: Some(HoverProviderCapability::Simple(true)),
+        document_highlight_provider: Some(OneOf::Left(true)),
+        document_symbol_provider: Some(OneOf::Left(true)),
+        workspace_symbol_provider: Some(OneOf::Left(true)),
+        definition_provider: Some(OneOf::Left(true)),
+        text_document_sync: Some(TextDocumentSyncCapability::Kind(
+            lsp_types::TextDocumentSyncKind::Full,
+        )),
 
-            ..ServerCapabilities::default()
-        };
-        let server_capabilities = serde_json::to_value(&capabilities).unwrap();
-        let initialization_params = connection.initialize(server_capabilities).unwrap();
-        main_loop(&connection, initialization_params).unwrap();
-        io_threads.join().unwrap();
-        // TODO: notify the gui thread to gracefully terminate the event loop
-    });
+        ..ServerCapabilities::default()
+    };
+    let server_capabilities = serde_json::to_value(&capabilities).unwrap();
+    let initialization_params = connection.initialize(server_capabilities)?;
+    main_loop(&connection, initialization_params)?;
+    io_threads.join()?;
+    Ok(())
 }
 
 fn main_loop(connection: &Connection, params: serde_json::Value) -> Result<(), Error> {
diff --git a/tools/lsp/preview.rs b/tools/lsp/preview.rs
index 74600e6c4..24071dfad 100644
--- a/tools/lsp/preview.rs
+++ b/tools/lsp/preview.rs
@@ -49,6 +49,12 @@ pub fn start_ui_event_loop() {
     sixtyfps_interpreter::run_event_loop();
 }
 
+pub fn quit_ui_event_loop() {
+    sixtyfps_rendering_backend_default::backend().post_event(Box::new(|| {
+        sixtyfps_rendering_backend_default::backend().quit_event_loop();
+    }));
+}
+
 pub fn load_preview(path: std::path::PathBuf) {
     run_in_ui_thread(Box::pin(async move { reload_preview(&path).await }));
 }