【Lua实战】协程批量邮件：暂停恢复的分批发送实现

local co = nil
local function buildMailTask(list)
    return coroutine.create(function()
        for i = 1, #list, 20 do
            for j = i, math.min(i + 19, #list) do
                sendmail(list[j], 0, "活动奖励", "感谢参与", "金币|5000")
            end
            coroutine.yield(i + 19)
        end
        return "done"
    end)
end

setontimerex(103, 1)
function ontimer103()
    if co == nil then return end
    local ok, pos = coroutine.resume(co)
    if not ok or coroutine.status(co) == "dead" then
        setsysvar("MAIL_TASK", "done:" .. tostring(pos))
        co = nil
    else
        setsysvar("MAIL_POS", tostring(pos))
    end
end