Feat: add mechanism to check cancellation in Agent (#10766)

### What problem does this PR solve?

Add mechanism to check cancellation in Agent.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

api/apps/canvas_app.py

@@ -156,7 +156,7 @@ def run():
         return get_json_result(data={"message_id": task_id})
 
     try:
-        canvas = Canvas(cvs.dsl, current_user.id, req["id"])
+        canvas = Canvas(cvs.dsl, current_user.id)
     except Exception as e:
         return server_error_response(e)
 
@@ -168,8 +168,10 @@ def run():
 
             cvs.dsl = json.loads(str(canvas))
             UserCanvasService.update_by_id(req["id"], cvs.to_dict())
+
         except Exception as e:
             logging.exception(e)
+            canvas.cancel_task()
             yield "data:" + json.dumps({"code": 500, "message": str(e), "data": False}, ensure_ascii=False) + "\n\n"
 
     resp = Response(sse(), mimetype="text/event-stream")
@@ -177,6 +179,7 @@ def run():
     resp.headers.add_header("Connection", "keep-alive")
     resp.headers.add_header("X-Accel-Buffering", "no")
     resp.headers.add_header("Content-Type", "text/event-stream; charset=utf-8")
+    resp.call_on_close(lambda: canvas.cancel_task())
     return resp
 
 
@@ -430,7 +433,7 @@ def test_db_connect():
             catalog, schema = _parse_catalog_schema(req["database"])
             if not catalog:
                 return server_error_response("For Trino, 'database' must be 'catalog.schema' or at least 'catalog'.")
-            
+
             http_scheme = "https" if os.environ.get("TRINO_USE_TLS", "0") == "1" else "http"
 
             auth = None
@@ -603,4 +606,4 @@ def download():
     id = request.args.get("id")
     created_by = request.args.get("created_by")
     blob = FileService.get_blob(created_by, id)
-    return flask.make_response(blob)
+    return flask.make_response(blob)