SetReadDeadline (an alternative to deadline contexts)

Hey,

For the continuous reads, it's convenient to use something like Gorilla's SetReadDeadline, instead of creating a new context each time a Read is called. Though I know Gorilla's encapsulating the net.Conn, while this pkg isn't. How do you think is it possible to add something like that in this library?

首先检查库对 continuous-read 和 Read 上下文的处理，然后将其与 Gorilla 的 SetReadDeadline 以及该包与 net.Conn 的关系进行比较。确定在不暴露 net.Conn 的情况下是否可行地提供等效 API，包括其 deadline 语义以及如何验证完成状态。

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