class ContextFilter implements Filter {

    @Override
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
        Map<String, String> attachments = invocation.getAttachments();
        if (attachments != null) {
            attachments = new HashMap<String, String>(attachments);
            attachments.remove(Constants.PATH_KEY);
            attachments.remove(Constants.GROUP_KEY);
            attachments.remove(Constants.VERSION_KEY);
            attachments.remove(Constants.DUBBO_VERSION_KEY);
            attachments.remove(Constants.TOKEN_KEY);
            attachments.remove(Constants.TIMEOUT_KEY);
            attachments.remove(Constants.ASYNC_KEY);// Remove async property to avoid being passed to the following invoke chain.
        }
        RpcContext.getContext()
                .setInvoker(invoker)
                .setInvocation(invocation)
//                .setAttachments(attachments)  // merged from dubbox
                .setLocalAddress(invoker.getUrl().getHost(),
                        invoker.getUrl().getPort());

        // mreged from dubbox
        // we may already added some attachments into RpcContext before this filter (e.g. in rest protocol)
        if (attachments != null) {
            if (RpcContext.getContext().getAttachments() != null) {
                RpcContext.getContext().getAttachments().putAll(attachments);
            } else {
                RpcContext.getContext().setAttachments(attachments);
            }
        }

        if (invocation instanceof RpcInvocation) {
            ((RpcInvocation) invocation).setInvoker(invoker);
        }
        try {
            RpcResult result = (RpcResult) invoker.invoke(invocation);
            // pass attachments to result
            result.addAttachments(RpcContext.getServerContext().getAttachments());
            return result;
        } finally {
            RpcContext.removeContext();
            RpcContext.getServerContext().clearAttachments();
        }
    }

}