【高级技巧】配额推进：万级任务的分片批处理

local QUOTA = 500
local function advanceBatch()
    local cursor = tonumber(getsysvar("MailCursor") or "") or 1
    local board = tostring(getsysvar("MailBoard") or "")
    local done, moved = 0, cursor
    for e in string.gmatch(board, "[^|]+") do
        moved = moved + 1
        if moved > cursor then
            local who, item, num = string.match(e, "([^:]+):([^:]+):(%d+)")
            if who ~= nil then
                sendmail("#" .. who, 9070, "补偿发放",
                    "全服补偿邮件。", item .. "#" .. num .. "#1")
                done = done + 1
            end
            if done >= QUOTA then
                break
            end
        end
    end
    setsysvarex("MailCursor", moved, 1)
    sendmsg(nil, 1, "本轮推进 " .. done .. " 封，游标 " .. moved .. "。")
end

local function onBatchTick()
    advanceBatch()
end