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flow_control: reserve window for single stream, cap multi-stream stalls #45

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Merged
Mygod merged 9 commits into from
Jan 23, 2026
Merged

flow_control: reserve window for single stream, cap multi-stream stalls #45

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1ac93f6
flow_control: reserve window for single stream, cap multi-stream stalls
Mygod Jan 23, 2026
cc3d794
Fix single‑stream write‑drain logic
Mygod Jan 23, 2026
8312103
Address review comments
Mygod Jan 23, 2026
2b06ebe
Reduce dup
Mygod Jan 23, 2026
eb8e7ac
Fix env in test
Mygod Jan 23, 2026
2e93da7
Refactor to remove dup
Mygod Jan 23, 2026
8b12336
Refactor further
Mygod Jan 23, 2026
0d353a7
Add missing file
Mygod Jan 23, 2026
cc2fcc8
More refactor
Mygod Jan 23, 2026
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239 changes: 164 additions & 75 deletions crates/slipstream-client/src/streams.rs
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Original file line number Diff line number Diff line change
@@ -1,9 +1,14 @@
use slipstream_core::flow_control::{
conn_reserve_bytes, consume_error_log_message, consume_stream_data, handle_stream_receive,
overflow_log_message, promote_error_log_message, promote_streams, reserve_target_offset,
FlowControlState, HasFlowControlState, PromoteEntry, StreamReceiveConfig, StreamReceiveOps,
};
use slipstream_core::tcp::{stream_read_limit_chunks, tcp_send_buffer_bytes};
use slipstream_ffi::picoquic::{
picoquic_add_to_stream, picoquic_call_back_event_t, picoquic_cnx_t, picoquic_current_time,
picoquic_get_close_reasons, picoquic_get_cnx_state, picoquic_get_next_local_stream_id,
picoquic_mark_active_stream, picoquic_provide_stream_data_buffer, picoquic_reset_stream,
picoquic_stream_data_consumed,
picoquic_stop_sending, picoquic_stream_data_consumed,
};
use slipstream_ffi::{SLIPSTREAM_FILE_CANCEL_ERROR, SLIPSTREAM_INTERNAL_ERROR};
use std::collections::HashMap;
Expand All @@ -21,6 +26,7 @@ pub(crate) struct ClientState {
ready: bool,
closing: bool,
streams: HashMap<u64, ClientStream>,
multi_stream_mode: bool,
command_tx: mpsc::UnboundedSender<Command>,
data_notify: Arc<Notify>,
path_events: Vec<PathEvent>,
Expand All @@ -39,6 +45,7 @@ impl ClientState {
ready: false,
closing: false,
streams: HashMap::new(),
multi_stream_mode: false,
command_tx,
data_notify,
path_events: Vec::new(),
Expand Down Expand Up @@ -81,6 +88,7 @@ impl ClientState {
}
self.ready = false;
self.closing = false;
self.multi_stream_mode = false;
self.path_events.clear();
self.debug_enqueued_bytes = 0;
self.debug_last_enqueue_at = 0;
Expand All @@ -91,12 +99,19 @@ struct ClientStream {
write_tx: mpsc::UnboundedSender<StreamWrite>,
read_abort_tx: Option<oneshot::Sender<()>>,
data_rx: Option<mpsc::Receiver<Vec<u8>>>,
queued_bytes: usize,
rx_bytes: u64,
tx_bytes: u64,
consumed_offset: u64,
fin_offset: Option<u64>,
fin_enqueued: bool,
flow: FlowControlState,
}

impl HasFlowControlState for ClientStream {
fn flow_control(&self) -> &FlowControlState {
&self.flow
}

fn flow_control_mut(&mut self) -> &mut FlowControlState {
&mut self.flow
}
}

enum StreamWrite {
Expand Down Expand Up @@ -171,11 +186,11 @@ pub(crate) unsafe extern "C" fn client_callback(
"stream {}: reset event={} rx_bytes={} tx_bytes={} queued={} consumed_offset={} fin_offset={:?} fin_enqueued={}",
stream_id,
reason,
stream.rx_bytes,
stream.flow.rx_bytes,
stream.tx_bytes,
stream.queued_bytes,
stream.consumed_offset,
stream.fin_offset,
stream.flow.queued_bytes,
stream.flow.consumed_offset,
stream.flow.fin_offset,
stream.fin_enqueued
);
} else {
Expand Down Expand Up @@ -242,6 +257,12 @@ fn handle_stream_data(
let debug_streams = state.debug_streams;
let mut reset_stream = false;
let mut remove_stream = false;
let multi_stream = state.multi_stream_mode;
let reserve_bytes = if multi_stream {
0
} else {
conn_reserve_bytes()
};

{
let Some(stream) = state.streams.get_mut(&stream_id) else {
Expand All @@ -257,46 +278,84 @@ fn handle_stream_data(
return;
};

if !data.is_empty() {
// Backpressure is enforced via connection-level max_data, not per-stream buffer caps.
stream.rx_bytes = stream.rx_bytes.saturating_add(data.len() as u64);
if stream
.write_tx
.send(StreamWrite::Data(data.to_vec()))
.is_err()
{
warn!(
"stream {}: tcp write channel closed queued={} rx_bytes={} tx_bytes={}",
stream_id, stream.queued_bytes, stream.rx_bytes, stream.tx_bytes
);
reset_stream = true;
} else {
stream.queued_bytes = stream.queued_bytes.saturating_add(data.len());
}
if handle_stream_receive(
stream,
data.len(),
StreamReceiveConfig::new(multi_stream, reserve_bytes),
StreamReceiveOps {
enqueue: |stream: &mut ClientStream| {
if stream
.write_tx
.send(StreamWrite::Data(data.to_vec()))
.is_err()
{
warn!(
"stream {}: tcp write channel closed queued={} rx_bytes={} tx_bytes={}",
stream_id,
stream.flow.queued_bytes,
stream.flow.rx_bytes,
stream.tx_bytes
);
Err(())
} else {
Ok(())
}
},
on_overflow: |stream: &mut ClientStream| {
let (drain_tx, _drain_rx) = mpsc::unbounded_channel();
stream.write_tx = drain_tx;
},
consume: |new_offset| unsafe {
picoquic_stream_data_consumed(cnx, stream_id, new_offset)
},
stop_sending: || {
let _ =
unsafe { picoquic_stop_sending(cnx, stream_id, SLIPSTREAM_INTERNAL_ERROR) };
},
log_overflow: |queued, incoming, max| {
warn!("{}", overflow_log_message(stream_id, queued, incoming, max));
},
on_consume_error: |ret, current, target| {
warn!(
"{}",
consume_error_log_message(stream_id, "", ret, current, target)
);
},
},
) {
reset_stream = true;
}

if fin {
if stream.fin_offset.is_none() {
stream.fin_offset = Some(stream.rx_bytes);
}
stream.data_rx = None;
if !stream.fin_enqueued {
if stream.write_tx.send(StreamWrite::Fin).is_err() {
warn!(
"stream {}: tcp write channel closed on fin queued={} rx_bytes={} tx_bytes={}",
stream_id,
stream.queued_bytes,
stream.rx_bytes,
stream.tx_bytes
);
reset_stream = true;
} else {
stream.fin_enqueued = true;
if stream.flow.discarding {
remove_stream = true;
} else {
if stream.flow.fin_offset.is_none() {
stream.flow.fin_offset = Some(stream.flow.rx_bytes);
}
stream.data_rx = None;
if !stream.fin_enqueued {
if stream.write_tx.send(StreamWrite::Fin).is_err() {
warn!(
"stream {}: tcp write channel closed on fin queued={} rx_bytes={} tx_bytes={}",
stream_id,
stream.flow.queued_bytes,
stream.flow.rx_bytes,
stream.tx_bytes
);
reset_stream = true;
} else {
stream.fin_enqueued = true;
}
}
}
}

if !reset_stream && stream.fin_enqueued && stream.queued_bytes == 0 {
if !reset_stream
&& !stream.flow.discarding
&& stream.fin_enqueued
&& stream.flow.queued_bytes == 0
{
remove_stream = true;
}
}
Expand Down Expand Up @@ -406,14 +465,34 @@ pub(crate) fn handle_command(
write_tx,
read_abort_tx: Some(read_abort_tx),
data_rx: Some(data_rx),
queued_bytes: 0,
rx_bytes: 0,
tx_bytes: 0,
consumed_offset: 0,
fin_offset: None,
fin_enqueued: false,
flow: FlowControlState::default(),
},
);
if !state.multi_stream_mode && state.streams.len() > 1 {
state.multi_stream_mode = true;
promote_streams(
state
.streams
.iter_mut()
.map(|(stream_id, stream)| PromoteEntry {
stream_id: *stream_id,
rx_bytes: stream.flow.rx_bytes,
consumed_offset: &mut stream.flow.consumed_offset,
discarding: stream.flow.discarding,
}),
|stream_id, new_offset| unsafe {
picoquic_stream_data_consumed(cnx, stream_id, new_offset)
},
|stream_id, ret, consumed_offset, rx_bytes| {
warn!(
"{}",
promote_error_log_message(stream_id, ret, consumed_offset, rx_bytes)
);
},
);
}
let _ = unsafe { picoquic_mark_active_stream(cnx, stream_id, 1, std::ptr::null_mut()) };
if state.debug_streams {
debug!("stream {}: accepted", stream_id);
Expand Down Expand Up @@ -455,11 +534,11 @@ pub(crate) fn handle_command(
warn!(
"stream {}: tcp read error rx_bytes={} tx_bytes={} queued={} consumed_offset={} fin_offset={:?}",
stream_id,
stream.rx_bytes,
stream.flow.rx_bytes,
stream.tx_bytes,
stream.queued_bytes,
stream.consumed_offset,
stream.fin_offset
stream.flow.queued_bytes,
stream.flow.consumed_offset,
stream.flow.fin_offset
);
} else {
warn!("stream {}: tcp read error (unknown stream)", stream_id);
Expand All @@ -471,11 +550,11 @@ pub(crate) fn handle_command(
warn!(
"stream {}: tcp write error rx_bytes={} tx_bytes={} queued={} consumed_offset={} fin_offset={:?}",
stream_id,
stream.rx_bytes,
stream.flow.rx_bytes,
stream.tx_bytes,
stream.queued_bytes,
stream.consumed_offset,
stream.fin_offset
stream.flow.queued_bytes,
stream.flow.consumed_offset,
stream.flow.fin_offset
);
} else {
warn!("stream {}: tcp write error (unknown stream)", stream_id);
Expand All @@ -484,33 +563,43 @@ pub(crate) fn handle_command(
}
Command::StreamWriteDrained { stream_id, bytes } => {
let mut remove_stream = false;
let mut reset_stream = false;
if let Some(stream) = state.streams.get_mut(&stream_id) {
stream.queued_bytes = stream.queued_bytes.saturating_sub(bytes);
stream.consumed_offset = stream.consumed_offset.saturating_add(bytes as u64);
if let Some(fin_offset) = stream.fin_offset {
if stream.consumed_offset > fin_offset {
stream.consumed_offset = fin_offset;
}
if stream.flow.discarding {
return;
}
let ret = unsafe {
picoquic_stream_data_consumed(cnx, stream_id, stream.consumed_offset)
};
if ret < 0 {
warn!(
"stream {}: stream_data_consumed failed ret={} consumed_offset={}",
stream_id, ret, stream.consumed_offset
stream.flow.queued_bytes = stream.flow.queued_bytes.saturating_sub(bytes);
if !state.multi_stream_mode {
let new_offset = reserve_target_offset(
stream.flow.rx_bytes,
stream.flow.queued_bytes,
stream.flow.fin_offset,
conn_reserve_bytes(),
);
reset_stream = true;
} else if stream.fin_enqueued && stream.queued_bytes == 0 {
if !consume_stream_data(
&mut stream.flow.consumed_offset,
new_offset,
|new_offset| unsafe {
picoquic_stream_data_consumed(cnx, stream_id, new_offset)
},
|ret, current, target| {
warn!(
"{}",
consume_error_log_message(stream_id, "", ret, current, target)
);
},
) {
let _ = unsafe {
picoquic_reset_stream(cnx, stream_id, SLIPSTREAM_INTERNAL_ERROR)
};
state.streams.remove(&stream_id);
return;
}
}
if stream.fin_enqueued && stream.flow.queued_bytes == 0 {
remove_stream = true;
}
}
if reset_stream {
let _ =
unsafe { picoquic_reset_stream(cnx, stream_id, SLIPSTREAM_FILE_CANCEL_ERROR) };
state.streams.remove(&stream_id);
} else if remove_stream {
if remove_stream {
state.streams.remove(&stream_id);
}
}
Expand Down
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