lsp: Implement shutdown for SphinxManager and PreviewManager

This is likely not enough to fully resolve the shutdown issue (as that
requires a fix in `pygls`[1]) but at least now the server will make an
attempt to shut itself down.

[1]: openlawlibrary/pygls#433

lib/esbonio/esbonio/server/features/preview_manager/__init__.py

@@ -1,5 +1,6 @@
 import asyncio
 import logging
+import sys
 from http.server import HTTPServer
 from http.server import SimpleHTTPRequestHandler
 from typing import Any
@@ -92,6 +93,20 @@ def __init__(self, server: EsbonioLanguageServer, sphinx: SphinxManager):
         self._ws_server: Optional[WebviewServer] = None
         self._ws_task: Optional[asyncio.Task] = None
 
+    def shutdown(self, params: None):
+        """Called when the client instructs the server to ``shutdown``."""
+        args = {}
+        if sys.version_info.minor > 8:
+            args["msg"] = "Server is shutting down."
+
+        if self._http_server:
+            self.logger.debug("Shutting down preview HTTP server")
+            self._http_server.shutdown()
+
+        if self._ws_task:
+            self.logger.debug("Shutting down preview WebSocket server")
+            self._ws_task.cancel(**args)
+
     @property
     def preview_active(self) -> bool:
         """Return true if the preview is active.

lib/esbonio/esbonio/server/features/sphinx_manager/manager.py

@@ -2,6 +2,7 @@
 
 import asyncio
 import inspect
+import sys
 import typing
 import uuid
 from typing import Callable
@@ -86,6 +87,26 @@ async def document_save(self, params: lsp.DidSaveTextDocumentParams):
 
         await self.trigger_build(uri)
 
+    async def shutdown(self, params: None):
+        """Called when the server is instructed to ``shutdown``."""
+
+        # Stop creating any new clients.
+        if self._client_creating and not self._client_creating.done():
+            args = {}
+            if sys.version_info.minor > 8:
+                args["msg"] = "Server is shutting down"
+
+            self.logger.debug("Aborting client creation")
+            self._client_creating.cancel(**args)
+
+        # Stop any existing clients.
+        tasks = []
+        for client in self.clients.values():
+            self.logger.debug("Stopping SphinxClient: %s", client)
+            tasks.append(asyncio.create_task(client.stop()))
+
+        await asyncio.gather(*tasks)
+
     async def trigger_build_after(self, uri: Uri, app_id: str, delay: float):
         """Trigger a build for the given uri after the given delay."""
         await asyncio.sleep(delay)
@@ -217,7 +238,7 @@ async def start_progress(self, client: SphinxClient):
             return
 
         token = str(uuid.uuid4())
-        self.logger.error("Starting progress: '%s'", token)
+        self.logger.debug("Starting progress: '%s'", token)
 
         try:
             await self.server.progress.create_async(token)