private void login(ChannelHandlerContext ctx, int messageId, User user, Version version) {
    var pipeline = (DefaultChannelPipeline) ctx.pipeline();
    cleanPipeline(pipeline);

    var appStateHolder = new MobileStateHolder(user, version);
    pipeline.addLast("AAppHandler", new MobileHandler(holder, appStateHolder));

    var channel = ctx.channel();

    //todo back compatibility code. remove in future.
    if (user.region == null || user.region.isEmpty()) {
        user.region = holder.props.region;
    }

    var session = holder.sessionDao.getOrCreateSessionByUser(appStateHolder.userKey, channel.eventLoop());
    if (session.isSameEventLoop(channel)) {
        completeLogin(channel, session, user, messageId, version);
    } else {
        log.debug("Re registering app channel. {}", ctx.channel());
        ReregisterChannelUtil.reRegisterChannel(ctx, session, channelFuture ->
                completeLogin(channelFuture.channel(), session, user, messageId, version));
    }
}
 

private static void cleanPipeline(DefaultChannelPipeline pipeline) {
    pipeline.removeIfExists(MobileLoginHandler.class);
    pipeline.removeIfExists(UserNotLoggedHandler.class);
    pipeline.removeIfExists(MobileGetServerHandler.class);
    pipeline.removeIfExists(MobileRegisterHandler.class);
    pipeline.removeIfExists(MobileShareLoginHandler.class);
    pipeline.removeIfExists(MobileResetPasswordHandler.class);
}
 

@Override
protected final DefaultChannelPipeline newChannelPipeline() {
    return new EmbeddedChannelPipeline(this);
}
 

private ChannelFuture failedFuture(String message) {
    DefaultChannelPipeline pipeline = new DefaultChannelPipeline(ch) {
    };
    return pipeline.newFailedFuture(new RuntimeException(message));
}