【数据存储】任务调度：定时任务的分布式锁

local LOCK_KEY = "SCHED_LOCK_DAILY"
local NODE_ID = "node_a"
local function tryLock()
    local holder = getsysvar(LOCK_KEY) or ""
    if holder == "" or holder == NODE_ID then
        setsysvarex(LOCK_KEY, NODE_ID, 1)
        return true
    end
    return false
end

setontimerex(204, 60)
function ontimer204()
    local holder = getsysvar(LOCK_KEY) or ""
    local ts = tonumber(getsysvar("LOCK_TS") or "0")
    if holder ~= "" and holder ~= NODE_ID and os.time() - ts > 300 then
        setsysvarex(LOCK_KEY, "", 1)
        sendcentermsg("任务锁 " .. LOCK_KEY .. " 超时释放")
    end
    if holder == NODE_ID then
        setsysvarex("LOCK_TS", os.time(), 1)
    end
end