【高级技巧】LRU淘汰：热身缓存的容量治理

local function createLRU(capacity)
    local data, stamp = {}, {}
    local count = 0
    local function get(k)
        local v = data[k]
        if v ~= nil then
            stamp[k] = os.clock()
        end
        return v
    end
    local function put(k, v)
        if data[k] == nil then
            count = count + 1
        end
        data[k] = v
        stamp[k] = os.clock()
        if count > capacity then
            local victims = {}
            for kk, t in pairs(stamp) do
                victims[#victims + 1] = { k = kk, t = t }
            end
            table.sort(victims, function(a, b) return a.t < b.t end)
            local sweep = math.floor(capacity * 0.1)
            for i = 1, sweep do
                data[victims[i].k] = nil
                stamp[victims[i].k] = nil
            end
            count = count - sweep
        end
    end
    return { get = get, put = put }
end

local coordCache = createLRU(512)
local function cacheProbe(actor, key)
    actor = getplayerbyname(actor)
    local v = coordCache.get(key)
    if v == nil then
        v = "resolved_" .. key
        coordCache.put(key, v)
    end
    sendmsg(actor, 1, "查询[" .. key .. "] => " .. tostring(v))
end