Lua信号量：计数配额的进出闸门

local function newSemaphore(n)
    local s = {count = n}
    function s.acquire()
        if s.count <= 0 then
            return false
        end
        s.count = s.count - 1
        return true
    end
    function s.release()
        s.count = s.count + 1
    end
    return s
end

local quota = newSemaphore(5)
local function enterMine(actor)
    if not quota.acquire() then
        sendmsg(actor, 1, "矿地已满 5 人，请稍后")
        return
    end
    sendmsg(actor, 1, "进入矿地，剩余名额 "
        .. quota.count)
end
local function leaveMine(actor)
    quota.release()
    sendmsg(actor, 1, "已离开矿地")
end
local p = getplayerbyname("sem01")
enterMine(p)
leaveMine(p)