[游戏对外服 - 内置与可选 handler] - 总人数限制（过载保护）

[iohao]

当游戏对外服设置了最多承载上限时（假设值为 5000 人），如果连接数超过所设置的承载值时，将直接返回错误码，并断开连接。

目的

1. 面对突发流量，但又没有提前准备更多的游戏对外服时。
2. 提升系统的稳定性， 最重要的是保护目前已经在线的玩家。

[iohao]

其他参考 内置与可选的 Handler

[duongxinh2003]

How to count online users?

@iohao I want to prevent users from logging into the application when there are too many simultaneous users (e.g., around 500 users at the same time). How can I get the number of online users?
I can see the log showing the number of online users like this: INFO 91380 --- [ Simple-12-2] CommonStdout : [PlayerOffline] CountOnline:0 userId:1 ....., but I don't know how to get that variable.
Edit:
I used ExternalBizRegion class and implemented like this:

@Override
    public Serializable request(ExternalBizRegionContext regionContext) throws MsgException {
        return regionContext.getUserSessions().countOnline();
    }

After, get count online:

@ActionMethod(20)
    public Integer getTotalOnlineUsers(FlowContext flowContext) {
        ResponseCollectExternalMessage response = flowContext.invokeExternalModuleCollectMessage(ExternalRegionCode.onlineUser);
        if (response.anySuccess()) {
            return response.getMessageList().getFirst().getData();
        }
        return -1;
    }

Is this okay?

[iohao]

Add a custom NettyHandler to the external service。

the custom NettyHandler implements UserSessionsAware
see https://iohao.github.io/game/docs/external/aware

Custom NettyHandler

@Slf4j
@ChannelHandler.Sharable
public final class MyOnlineTotalLimitHandler extends ChannelInboundHandlerAdapter implements UserSessionsAware {
    SocketUserSessions userSessions;

    @Override
    public void setUserSessions(UserSessions<?, ?> userSessions) {
        this.userSessions = (SocketUserSessions) userSessions;
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        int countOnline = userSessions.countOnline();

        if (countOnline > 500) {
            log.info("[{}] The maximum number of online users has been reached. Please try again later!", countOnline);
            ctx.close();
            return;
        }
        
        super.channelActive(ctx);
    }

    private MyOnlineTotalLimitHandler() {
    }

    public static MyOnlineTotalLimitHandler me() {
        return Holder.ME;
    }

    private static class Holder {
        static final MyOnlineTotalLimitHandler ME = new MyOnlineTotalLimitHandler();
    }
}

Add a custom NettyHandler to the external

public ExternalServer create(int externalPort) {
    // external
    DefaultExternalServerBuilder builder = DefaultExternalServer.newBuilder(externalPort);
    var setting = builder.setting();

    setting.setMicroBootstrapFlow(new WebSocketMicroBootstrapFlow() {
        @Override
        public void pipelineCustom(PipelineContext context) {
            context.addLast("MyOnlineTotalLimitHandler", MyOnlineTotalLimitHandler.me());
            super.pipelineCustom(context);
        }
    });

    return builder.build();
}

[undertaker86001]

@iohao 您好，我对这个问题比较感兴趣，为此创建了一个commit。包含netifix的三种限流算法。可以请您有时间看下嘛
https://gummary.github.io/post/netfix%E8%87%AA%E9%80%82%E5%BA%94%E9%99%90%E6%B5%81%E7%AE%97%E6%B3%95/