【高级技巧】连接管理：连接生命周期的状态机封装

local S = { NEW = 1, AUTHED = 2, ACTIVE = 3, CLOSED = 4 }
local TRANS = {
    [S.NEW] = { [S.AUTHED] = true, [S.CLOSED] = true },
    [S.AUTHED] = { [S.ACTIVE] = true, [S.CLOSED] = true },
    [S.ACTIVE] = { [S.CLOSED] = true },
    [S.CLOSED] = {},
}
local conns = {}
local function connNew(connId)
    conns[connId] = { state = S.NEW, since = os.time() }
end
local function connMove(connId, to)
    local c = conns[connId]
    if c == nil then
        return false
    end
    if TRANS[c.state][to] ~= true then
        print("非法迁移：" .. c.state .. " 到 " .. to)
        return false
    end
    c.state = to
    c.since = os.time()
    return true
end
local function connClose(connId)
    return connMove(connId, S.CLOSED)
end

connNew("c1001")
connMove("c1001", S.AUTHED)
connMove("c1001", S.ACTIVE)
connMove("c1001", S.AUTHED)