openresty+websocket+redis simple chat

openresty 很早就支持websocket了，但是早期的版本cosocket是单工的，处理起来比较麻烦参见邮件列表讨论 websocket chat，后来的版本cosocket是双全工的，就可以按照这个讨论的方案来实现基于websocket的聊天，或者是push程序了，但是网络上没有找到一个具体一点的例子，于是自己写了个simple的例子。

1 思路

client的websocket连接到openresty之后，使用ngx.thread.spawn启动两个 轻线程，一个用来接收客户端提交的数据往redis的channel写，另一个用来订阅channel，读取redis的数据写给客户端。channel相当于一个chat room，多个client一起订阅，有人发聊天信息(pub)，所有人都能得到信息(sub)。代码比较简陋，简单的思路的实现。

2 服务端代码

依赖:

• openresty
• redis
• lua-resty-redis
• lua-resty-websocket 只支持RFC 6455

nginx的配置全贴了，就是两个location，一个是页面地址，一个是websocket地址。

配置片段

    location = /sredis {
        content_by_lua_file conf/lua/ws_redis.lua;
    }    location ~ /ws/(.*) {
        alias conf/html/$1.html;
    }

lua代码

-- simple chat with redislocal server = require"resty.websocket.server"local redis = require"resty.redis"local channel_name = "chat"local msg_id = 0--create connectionlocal wb, err = server:new{
  timeout = 10000,
  max_payload_len = 65535
}

--create successifnot wb then
  ngx.log(ngx.ERR, "failed to new websocket: ", err)
  return ngx.exit(444)
endlocal push = function()-- --create redislocal red = redis:new()
    red:set_timeout(5000) -- 1 seclocal ok, err = red:connect("127.0.0.1", 6379)
    ifnot ok then
        ngx.log(ngx.ERR, "failed to connect redis: ", err)
        wb:send_close()
        returnend--sublocal res, err = red:subscribe(channel_name)
    ifnot res then
        ngx.log(ngx.ERR, "failed to sub redis: ", err)
        wb:send_close()
        returnend-- loop : read from rediswhiletruedolocal res, err = red:read_reply()
        if res thenlocal item = res[3]
            local bytes, err = wb:send_text(tostring(msg_id).." "..item)
            ifnot bytes then-- better error handling
                ngx.log(ngx.ERR, "failed to send text: ", err)
                return ngx.exit(444)
            end
            msg_id = msg_id + 1endendendlocal co = ngx.thread.spawn(push)

--main loopwhiletruedo-- 获取数据local data, typ, err = wb:recv_frame()

    -- 如果连接损坏 退出if wb.fatal then
        ngx.log(ngx.ERR, "failed to receive frame: ", err)
        return ngx.exit(444)
    endifnot data thenlocal bytes, err = wb:send_ping()
        ifnot bytes then
          ngx.log(ngx.ERR, "failed to send ping: ", err)
          return ngx.exit(444)
        end
        ngx.log(ngx.ERR, "send ping: ", data)
    elseif typ == "close"thenbreakelseif typ == "ping"thenlocal bytes, err = wb:send_pong()
        ifnot bytes then
            ngx.log(ngx.ERR, "failed to send pong: ", err)
            return ngx.exit(444)
        endelseif typ == "pong"then
        ngx.log(ngx.ERR, "client ponged")
    elseif typ == "text"then--send to redislocal red2 = redis:new()
        red2:set_timeout(1000) -- 1 seclocal ok, err = red2:connect("127.0.0.1", 6379)
        ifnot ok then
            ngx.log(ngx.ERR, "failed to connect redis: ", err)
            breakendlocal res, err = red2:publish(channel_name, data)
        ifnot res then
            ngx.log(ngx.ERR, "failed to publish redis: ", err)
        endendendwb:send_close()
ngx.thread.wait(co)

3 页面代码

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