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.
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if (deflate.result) yield [deflate.result];，推荐阅读同城约会获取更多信息
"So two of our grandparents are unfortunately no longer present, one works full time and the other one has her own health concerns," he added.