defer imports to get around perspective cloudpickle incompatibility

Signed-off-by: Tim Paine <[email protected]>

raydar/dashboard/server.py

@@ -14,14 +14,8 @@
 from ray.serve import Application, deployment, ingress
 
 if parse(perspective_version) >= parse("3"):
-    from perspective import Server as PerspectiveServer, Table
-    from perspective.handlers.starlette import PerspectiveStarletteHandler
-
     PERSPECTIVE_3 = True
 else:
-    from perspective import PerspectiveManager as PerspectiveServer, Table
-    from perspective.handlers import PerspectiveStarletteHandler
-
     PERSPECTIVE_3 = False
 
 class PerspectiveRayServerArgs(BaseModel):
@@ -53,6 +47,11 @@ def __init__(self, args: PerspectiveRayServerArgs = None):
         self._psp_server = None
 
     def _init(self):
+        if PERSPECTIVE_3:
+            from perspective import Server as PerspectiveServer
+        else:
+            from perspective import PerspectiveManager as PerspectiveServer
+
         if self._psp_server is None:
             self._psp_server = PerspectiveServer()
             if PERSPECTIVE_3:
@@ -68,8 +67,10 @@ def new_table(self, tablename: str, schema) -> None:
             return self._schemas[tablename]
         self._schemas[tablename] = schema
         if PERSPECTIVE_3:
-            self._psp_client.table(schema, name=tablename)
+            self._tables[tablename] = self._psp_client.table(schema, name=tablename)
         else:
+            from perspective import Table
+
             self._tables[tablename] = Table(schema)
             self._psp_client.host_table(tablename, self._tables[tablename])
 
@@ -87,8 +88,10 @@ def update(self, tablename: str, data):
     @app.websocket("/ws")
     async def ws(self, ws: WebSocket):
         if PERSPECTIVE_3:
+            from perspective.handlers.starlette import PerspectiveStarletteHandler
             handler = PerspectiveStarletteHandler(perspective_server=self._psp_server, websocket=ws)
         else:
+            from perspective.handlers import PerspectiveStarletteHandler
             handler = PerspectiveStarletteHandler(manager=self._psp_server, websocket=ws)
         try:
             await handler.run()