Send incomplete fin packets even if nagle enabled#665
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bors[bot] merged 1 commit intosmoltcp-rs:masterfrom Aug 16, 2022
OxIonics:ignore_nagle_if_want_fin
Merged
Send incomplete fin packets even if nagle enabled#665bors[bot] merged 1 commit intosmoltcp-rs:masterfrom OxIonics:ignore_nagle_if_want_fin
bors[bot] merged 1 commit intosmoltcp-rs:masterfrom
OxIonics:ignore_nagle_if_want_fin
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If we have an incomplete packet to send and the socket has been closed then send it. Without this change (with nagle enabled) we wait for the penultimate packet in the stream to be acked before sending the final packet even if there's plenty of space in the window.
Dirbaio
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Aug 16, 2022
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Dirbaio
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Thank you! Makes a lot of sense, there's no point in delaying the last packet indeed. Nice find!
bors r+
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If we have an incomplete packet to send and the socket has been closed
then send it. Without this change (with nagle enabled) we wait for the
penultimate packet in the stream to be acked before sending the final
packet even if there's plenty of space in the window.
I think this is strictly only an optimisation, but when I wrote the code I thought it was necessary.
If there is no packet loss this change saves you a RTT before sending the final packet in the stream (plus any ack delay). If there is incoming packet loss so that you've missed an ACK, this change might additionally save you from having to do some retransmission. Once the far end has received the FIN/ACK it can drive retransmission if that gets dropped.