【高级技巧】超时治理：外部调用的超时预算分配

local BUDGETS = {
    crossQuery = 800,
    dbWrite = 2000,
    httpNotify = 3000,
}
local callers = {
    crossQuery = doCrossQuery,
    dbWrite = doDbWrite,
    httpNotify = doHttpNotify,
}
local function callWithBudget(kind, ...)
    local fn = callers[kind]
    if fn == nil then
        return false, "未知调用类型"
    end
    local done = false
    local result
    local co = coroutine.create(function()
        result = { fn(...) }
        done = true
    end
    )
    local t0 = os.clock()
    while not done do
        coroutine.resume(co)
        if (os.clock() - t0) * 1000 > BUDGETS[kind] then
            return false, kind .. " 超时"
        end
    end
    return true, table.unpack(result, 1, #result)
end

local ok, rankList = callWithBudget("crossQuery", "沙巴克榜")
if not ok then
    rankList = lastSnapshot
end