【性能调优】千人同屏广播：合帧与增量的下发优化

-- 原始广播：每个动作对视野内每个玩家发一次
function Combat.broadcastOld(action, targets)
    for _, viewer in ipairs(targets) do
        for _, unit in ipairs(action.units) do
            sendmsg(viewer, 1, unit.name .. action.text)
        end
    end
end

-- 合帧广播：同帧动作打包成一条
local frameBuffer = {}
function Combat.broadcastNew(action, viewers)
    frameBuffer[#frameBuffer + 1] = action
    if #frameBuffer >= 20 then
        Combat.flush(viewers)
    end
end

function Combat.flush(viewers)
    if #frameBuffer == 0 then return end
    local pack = table.concat(frameBuffer, "|")
    for _, viewer in ipairs(viewers) do
        sendmsg(viewer, 2, pack)
    end
    frameBuffer = {}
end