private void updateModelWorkers()

in frontend/server/src/main/java/com/amazonaws/ml/mms/http/ManagementRequestHandler.java [280:330]
50 lines of code
6 McCabe index (conditional complexity)

    private void updateModelWorkers(
            final ChannelHandlerContext ctx,
            final String modelName,
            int minWorkers,
            int maxWorkers,
            boolean synchronous,
            final Function<Void, Void> onError) {

        ModelManager modelManager = ModelManager.getInstance();
        CompletableFuture<HttpResponseStatus> future =
                modelManager.updateModel(modelName, minWorkers, maxWorkers);
        if (!synchronous) {
            NettyUtils.sendJsonResponse(
                    ctx,
                    new StatusResponse("Processing worker updates..."),
                    HttpResponseStatus.ACCEPTED);
            return;
        }
        future.thenApply(
                        v -> {
                            boolean status = modelManager.scaleRequestStatus(modelName);
                            if (HttpResponseStatus.OK.equals(v)) {
                                if (status) {
                                    NettyUtils.sendJsonResponse(
                                            ctx, new StatusResponse("Workers scaled"), v);
                                } else {
                                    NettyUtils.sendJsonResponse(
                                            ctx,
                                            new StatusResponse("Workers scaling in progress..."),
                                            new HttpResponseStatus(210, "Partial Success"));
                                }
                            } else {
                                NettyUtils.sendError(
                                        ctx,
                                        v,
                                        new InternalServerException("Failed to start workers"));
                                if (onError != null) {
                                    onError.apply(null);
                                }
                            }
                            return v;
                        })
                .exceptionally(
                        (e) -> {
                            if (onError != null) {
                                onError.apply(null);
                            }
                            NettyUtils.sendError(ctx, HttpResponseStatus.INTERNAL_SERVER_ERROR, e);
                            return null;
                        });
    }