【性能调优】热点缓存：首领刷新时间的内存缓存设计

-- 热点缓存：读写与过期
local cache = {}
local TTL = 300
local function getBossRemain(player, bossName)
    local key = "Remain_" .. bossName
    local entry = cache[key]
    if entry and os.time() - entry.ts < TTL then
        return entry.value, true
    end
    local deadTs = tonumber(getsysvar("ZumaDeadTick") or 0)
    local value = math.max(0, 21600 - (os.time() - deadTs))
    cache[key] = {ts = os.time(), value = value}
    return value, false
end

-- 缓存击穿：定向失效
local player = class(actor)
local function invalidateBoss(bossName)
    cache["Remain_" .. bossName] = nil
    cache["Hint_" .. bossName] = nil
    local p = class(actor)
    sendmsg(p, 1, 0, bossName .. " 状态已更新，查询将重新计算。")
end
local function queryWithCache(player, bossName)
    local value, hit = getBossRemain(player, bossName)
    sendmsg(player, 1, 0, bossName .. " 预计 " .. math.floor(value / 60) .. " 分钟后刷新" ..
        (hit and "" or "（实时计算）"))
end