【运维发布】性能基线：核心接口的耗时水位

---接口耗时采样：1% 采样率进环形桶
local Sample = { buf = {}, idx = 0, cap = 2000 }

function Sample.record(iface, costMs)
    if math.random(1, 100) ~= 1 then return end
    Sample.idx = Sample.idx + 1
    local slot = Sample.idx % Sample.cap
    Sample.buf[slot] = { iface = iface, cost = costMs, at = os.time() }
end

function Sample.percentile(iface, p)
    local costs = {}
    for _, s in pairs(Sample.buf) do
        if s.iface == iface then costs[#costs + 1] = s.cost end
    end
    table.sort(costs)
    local i = math.max(1, math.floor(#costs * p))
    return costs[i] or 0
end

---全局定时器 31 号：每分钟聚合一次
setontimerex(31, 60)
function Baseline.tick()
    for _, iface in ipairs(IFACE_LIST) do
        local p95 = Sample.percentile(iface, 0.95)
        local base = Baseline.load(iface)
        if base > 0 and p95 > base * 1.4 then
            Baseline.alarm(iface, p95, base)
        end
        Baseline.save(iface, p95)
    end
end