The primary signal is desiredSize on the controller. It can be positive (wants data), zero (at capacity), negative (over capacity), or null (closed). Producers are supposed to check this value and stop enqueueing when it's not positive. But there's nothing enforcing this: controller.enqueue() always succeeds, even when desiredSize is deeply negative.
线下渠道商面临提货价上涨与消费者接受度下降的双重压力。随着3月后新品陆续上市，销售难度大增，可能引发一轮关店潮。
，这一点在im钱包官方下载中也有详细论述
"inventoryItemChanges": {
（本报记者朱隽、王浩、常钦、郁静娴、李晓晴、邓剑洋）