substream: Decrement the bytes counter to avoid excessive flushing #511
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calls Signed-off-by: Alexandru Vasile <[email protected]>
Signed-off-by: Alexandru Vasile <[email protected]>
dmitry-markin
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Jan 15, 2026
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| // This attempts to empty 'pending_out_frames' into the socket. | ||
| match futures::Sink::poll_flush(self.as_mut(), cx) { | ||
| Poll::Ready(Ok(())) => {} | ||
| Poll::Ready(Err(e)) => return Poll::Ready(Err(e)), | ||
| Poll::Pending => { | ||
| // Still flushing. We cannot accept new data yet. | ||
| return Poll::Pending; | ||
| } | ||
| } |
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How is this different from poll_flush!?
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The poll_flush! should call into the socket / TCP under the hood via AsyncWrite::poll_flush.
By calling the futures::Sink::poll_flush we ensure our impl is always called and try to write any pending frames before calling poll_flush
dmitry-markin
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Jan 21, 2026
## [0.13.0] - 2026-01-21 This release brings multiple fixes to both the transport and application-level protocols. Specifically, it enhances WebSocket stability by resolving AsyncWrite errors and ensuring that partial writes during the negotiation phase no longer trigger connection failures. At the same time, Bitswap client functionality is introduced, which makes this release semver breaking. ### Added - Add Bitswap client ([#501](#501)) ### Fixed - notif/fix: Avoid CPU busy loops on litep2p full shutdown ([#521](#521)) - protocol: Ensure transport manager knows about closed connections ([#515](#515)) - substream: Decrement the bytes counter to avoid excessive flushing ([#511](#511)) - crypto/noise: Improve stability of websockets by fixing AsyncWrite implementation ([#518](#518)) - bitswap: Split block responses into batches under 2 MiB ([#516](#516)) - crypto/noise: Fix connection negotiation logic on partial writes ([#519](#519)) - substream/fix: Fix partial reads for ProtocolCodec::Identity ([#512](#512)) - webrtc: Avoid panics returning error instead ([#509](#509)) - bitswap: e2e test & max payload fix ([#508](#508)) - tcp: Exit connections when events fail to propagate to protocols ([#506](#506)) - webrtc: Avoid future being dropped when channel is full ([#483](#483)) --------- Co-authored-by: Alexandru Vasile <[email protected]>
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The substream implementation utilises a
pending_out_bytescounter to enforce backpressure via flushing once the buffer fills up to 64KiB.poll_readyto make a syscall to flush the socket at every callThis implementation decrements the counter when data is moved to the socket. This should optimize the
poll_readyfn for long lived substreams.While at it, the
poll_readyimplementation calls into theSink::poll_flushwhich also drains the pending frames.