I looked up the document of libuv, there's no explaination about what it is used for:https://docs.libuv.org/en/v1.x/stream.html#c.uv_write2
There are two handles in arguments of uv_write2. The first one I guess means the target fd we want to write to. But the second one send_handle, I can't understand.
I also read on the source code of libuv. I found that send_handle was not used, it's only assign to the send_handle attribute of the first argument uv_write_t req.
I want to know what's the meaning of "send_handle"