refactor(core): decompose the client run_pump monolith into pump/ submodules

client/pump.rs was a single 1192-line async fn stacking six concerns.
It is now a 190-line orchestrator (same spawn order, same channel
wiring) over five focused modules:

- pump/handshake.rs   — connect + Hello/Welcome/Start + skew handshake +
                        hole punch + Session construction (HandshakeOut)
- pump/input_task.rs  — the gamepad snapshot/removal/arrival re-send
                        state machine + passthrough input forwarding
- pump/control_task.rs— the control-stream select loop (renegotiation,
                        probes, bitrate acks, clock re-sync, clip
                        metadata), bundled as ControlTask
- pump/datagram_task.rs — the datagram tag demux + rumble reorder gate
- pump/data.rs        — the blocking data-plane pump (loss reports, ABR
                        + capacity probe, jump-to-live detectors,
                        standing-latency bleed), bundled as DataPump

Every body moved verbatim (dedent + arg-struct destructures aliasing
the original binding names); no per-frame indirection added — the pump
loop, its locals, and the hot-path shape are byte-equivalent. The
Ctrl/DataPump arg structs exist only to stay under too_many_arguments.

196 lib tests pass; clippy clean on --features quic AND
--no-default-features (--all-targets); include/punktfunk_core.h
byte-identical; fmt clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
2026-07-20 18:07:14 +02:00
co-authored by Claude Fable 5
parent eacaaa5cd8
commit ce51a2ba74
6 changed files with 1241 additions and 1080 deletions
@@ -0,0 +1,563 @@
//! The blocking data-plane pump: poll the session for access units, run the adaptive-FEC
//! loss reports, the ABR controller + startup capacity probe, the jump-to-live detectors,
//! and the standing-latency bleed, and hand frames to the embedder.
use super::super::*;
use super::*;
/// Data-plane pump on a blocking thread: poll the session, hand frames to the embedder.
/// try_send drops the newest frame when the embedder lags (freshness over completeness).
/// Speed-test filler ([`FLAG_PROBE`]) is folded into the probe accumulator instead of the
/// decoder queue — it isn't video.
pub(super) struct DataPump {
pub(super) session: Session,
pub(super) frames: Arc<FrameChannel>,
pub(super) ctrl_tx: tokio::sync::mpsc::Sender<CtrlRequest>,
pub(super) shutdown: Arc<std::sync::atomic::AtomicBool>,
pub(super) probe: Arc<Mutex<ProbeState>>,
pub(super) hot_tids: Arc<Mutex<Vec<i32>>>,
pub(super) clock_offset: Arc<std::sync::atomic::AtomicI64>,
pub(super) clock_gen: Arc<AtomicU32>,
pub(super) decode_lat: Arc<Mutex<DecodeLatAcc>>,
pub(super) frames_dropped: Arc<std::sync::atomic::AtomicU64>,
pub(super) fec_recovered: Arc<std::sync::atomic::AtomicU64>,
pub(super) bitrate_ack: Arc<Mutex<Option<u32>>>,
/// The embedder's REQUESTED rate (0 = Automatic — the only case the ABR arms).
pub(super) bitrate_kbps: u32,
/// The rate the host actually configured (echoed in Welcome).
pub(super) resolved_bitrate_kbps: u32,
pub(super) negotiated_codec: u8,
}
impl DataPump {
pub(super) fn run(self) {
let DataPump {
mut session,
frames,
ctrl_tx,
shutdown: pump_shutdown,
probe: pump_probe,
hot_tids: pump_hot_tids,
clock_offset: pump_clock_offset,
clock_gen: pump_clock_gen,
decode_lat: pump_decode_lat,
frames_dropped,
fec_recovered,
bitrate_ack,
bitrate_kbps,
resolved_bitrate_kbps,
negotiated_codec,
} = self;
pin_thread_user_interactive(); // feeds the frame channel → the user-interactive video pump
register_hot_tid(&pump_hot_tids); // this thread does UDP receive + FEC reassembly — hint it
// Adaptive-FEC loss reporting: every ADAPT_REPORT_INTERVAL, report the loss observed over the
// window (shards FEC recovered, plus a bump if any frame went unrecoverable) so the host can
// size FEC to the link. Suppressed during a speed test (its FLAG_PROBE filler would skew it).
const ADAPT_REPORT_INTERVAL: Duration = Duration::from_millis(750);
let mut last_report = Instant::now();
let (
mut last_recovered,
mut last_late,
mut last_received,
mut last_dropped,
mut last_bytes,
) = (0u64, 0u64, 0u64, 0u64, 0u64);
// PUNKTFUNK_PERF: per-window pump observability — the Session's receive stage split
// (recv / decrypt / reassemble+FEC, see `Session::take_pump_perf`) and completed-AU
// inter-arrival jitter. Smoothness has no metric otherwise: jump-to-live counters only
// fire after the stream is already seconds behind.
let pump_perf_on = std::env::var("PUNKTFUNK_PERF").is_ok_and(|v| v != "0");
let mut arrivals_us: Vec<u32> = Vec::new();
let mut last_arrival: Option<Instant> = None;
// Adaptive bitrate (see `crate::abr`): armed only when the embedder asked for Automatic
// (`bitrate_kbps == 0`) and the host echoed the rate it actually configured (an old host
// echoes 0 → controller stays permanently off). Fed once per report window with the same
// deltas the LossReport uses, plus the window's mean skew-corrected one-way delay, the
// actual delivered throughput (climb gate + proven-throughput mark), and whether a
// jump-to-live flush fired.
// PyroWave sessions PIN their rate (§4.6): AIMD descent turns wavelets to mush well
// above its floor, and the climb probe's VBV reasoning doesn't apply to hard
// per-frame CBR — controller and capacity probe stay off (0 = permanently off).
let rate_pinned = negotiated_codec == crate::quic::CODEC_PYROWAVE;
let mut abr = BitrateController::new(if bitrate_kbps == 0 && !rate_pinned {
resolved_bitrate_kbps
} else {
0
});
// Startup link-capacity probe (Automatic sessions): the controller's ceiling is the
// negotiated start rate — the conservative 20 Mbps default, historically a box Automatic
// could NEVER climb out of. One speed-test burst shortly after the stream settles
// measures what the link actually delivers; ×0.7 (headroom for FEC overhead + variance)
// becomes the climb ceiling and slow start does the rest. Old hosts decline (all-zero
// reply) or never answer (timeout clears the state so LossReports resume) — either way
// the ceiling stays negotiated, exactly the old behavior. PUNKTFUNK_ABR_PROBE=0 opts out.
const CAPACITY_PROBE_KBPS: u32 = 2_000_000;
const CAPACITY_PROBE_MS: u32 = 800;
const CAPACITY_PROBE_DELAY: Duration = Duration::from_secs(2);
const CAPACITY_PROBE_TIMEOUT: Duration = Duration::from_secs(6);
let mut capacity_probe_at: Option<Instant> = (bitrate_kbps == 0
&& !rate_pinned
&& resolved_bitrate_kbps > 0
&& std::env::var("PUNKTFUNK_ABR_PROBE").map_or(true, |v| v != "0"))
.then(|| Instant::now() + CAPACITY_PROBE_DELAY);
let mut capacity_probe_deadline: Option<Instant> = None;
// Edge detector + watchdog for a probe of EITHER origin (the startup capacity probe or an
// embedder speed test via `NativeClient::request_probe`). The startup path had both built
// in; the embedder path had neither, so an unanswered request wedged the report tick and a
// finished one left the ABR window anchored before the burst.
let mut was_probing = false;
let mut probe_watchdog: Option<Instant> = None;
let (mut owd_sum_ns, mut owd_frames) = (0i128, 0u32);
let mut flush_in_window = false;
// Jump-to-live state (see the guard in the loop below): when the clock-based over-bound
// run began (`stale_since`, armed only when the skew handshake succeeded so the clocks
// are comparable), when the clock-free non-draining-queue run began (`standing_since`),
// and the last-jump instant for the shared cooldown. Wall-clock runs (T1.4), not frame
// counts — the detectors' sensitivity must not scale with fps or repeat cadence.
let mut stale_since: Option<Instant> = None;
let mut standing_since: Option<Instant> = None;
let mut last_flush: Option<Instant> = None;
// Clock-detector health: consecutive clock-triggered flushes that found no local backlog
// (see NOOP_FLUSH_DATAGRAMS). Reaching NOOP_CLOCK_FLUSHES_TO_DISARM turns the clock-based
// detector off (a clock step / upstream queue it can't fix) — until a mid-stream clock
// re-sync lands and re-arms it (`pump_clock_gen` below). The FIRST no-op flush also asks
// the control task for an immediate re-sync (via the report tick): the flush finding no
// local backlog IS the "the wall clock stepped under me" signal.
let mut noop_clock_flushes: u32 = 0;
let mut clock_detector_armed = true;
let mut resync_wanted = false;
let mut seen_clock_gen = pump_clock_gen.load(Ordering::Relaxed);
// Standing-latency bleed (see StandingLatency): the third detector, for the small,
// constant, loss-free OWD elevation the two jump-to-live detectors deliberately
// tolerate (< QUEUE_HIGH frames, < FLUSH_LATENCY behind) — a sub-frame standing
// backlog, or a stale clock offset after a wall-clock step, either of which otherwise
// reads as permanent extra "network" latency for the rest of the session.
let mut standing_lat = StandingLatency::new();
while !pump_shutdown.load(Ordering::SeqCst) {
// The live host↔client offset: re-loaded every iteration so an applied mid-stream
// re-sync takes effect on the very next frame's latency math.
let clock_offset_ns = pump_clock_offset.load(Ordering::Relaxed);
// An applied re-sync invalidates the staleness run measured under the OLD offset:
// reset the counters and re-arm the clock-based detector if a step had disarmed it.
let gen = pump_clock_gen.load(Ordering::Relaxed);
if gen != seen_clock_gen {
seen_clock_gen = gen;
stale_since = None;
noop_clock_flushes = 0;
// Every OWD reading shifted with the offset — the standing-latency floor and
// any elevation measured under the old one are meaningless now. If a stale
// offset WAS the elevation, this is also the moment it gets fixed.
standing_lat.rebase();
if !clock_detector_armed {
clock_detector_armed = true;
tracing::info!("clock re-sync applied — clock-based jump-to-live re-armed");
}
}
// Mirror the reassembler's unrecoverable-drop count for the client's keyframe-recovery
// loop, and (during a speed test) the packet-level receive counters for the throughput
// measurement. Updated every iteration (not just on a produced frame) so they stay current
// through a total-loss drought where no AU completes. Cheap: a few relaxed atomic loads.
let st = session.stats();
frames_dropped.store(st.frames_dropped, Ordering::Relaxed);
fec_recovered.store(st.fec_recovered_shards, Ordering::Relaxed);
let probe_active = {
let mut p = pump_probe.lock().unwrap();
if p.active && !p.done {
p.rx_packets_now = st.packets_received;
p.rx_bytes_now = st.bytes_received;
p.base_packets.get_or_insert(st.packets_received);
p.base_bytes.get_or_insert(st.bytes_received);
}
p.active && !p.done
};
// A probe just ended (either kind): rebase EVERY window anchor past the burst. Its
// FLAG_PROBE filler landed in `bytes_received`/`packets_received` (session.rs counts
// every accepted datagram) but never reached the decoder, and the report tick was
// suppressed for the whole burst, so `last_*` still points before it. Without this the
// first post-burst window reads the burst rate as `actual_kbps` and poisons the ABR's
// monotone proven-throughput high-water mark — which never decays — and divides the
// window's loss by a packet count inflated with filler.
if was_probing && !probe_active {
last_recovered = st.fec_recovered_shards;
last_late = st.fec_late_shards;
last_received = st.packets_received;
last_dropped = st.frames_dropped;
last_bytes = st.bytes_received;
last_report = Instant::now();
}
// Arm a watchdog on the leading edge of ANY probe, so a host that silently ignores
// `ProbeRequest` (an old build — anticipated, see the capacity-probe timeout below)
// cannot latch `active` forever and suppress the report tick for the whole session.
if !was_probing && probe_active {
let burst = Duration::from_millis(pump_probe.lock().unwrap().duration_ms as u64);
probe_watchdog = Some(Instant::now() + burst + CAPACITY_PROBE_TIMEOUT);
}
if !probe_active {
probe_watchdog = None;
} else if let Some(deadline) = probe_watchdog {
if Instant::now() >= deadline {
probe_watchdog = None;
pump_probe.lock().unwrap().active = false;
tracing::warn!(
"speed-test probe unanswered — clearing it so loss reports and ABR resume"
);
}
}
was_probing = probe_active;
// Fire the startup link-capacity probe once the stream has settled (see the constants
// above), and fold its measurement into the ABR ceiling when the result lands.
// Never steal the slot from an embedder speed test in flight: there is one `ProbeState`
// and no correlation id, so a clobber both wrecks the user's "Test connection" figure
// (its base counters get re-snapshotted mid-burst against the full-burst denominator)
// and mis-scales our own ceiling. Retry once it finishes.
if capacity_probe_at.is_some_and(|at| Instant::now() >= at) && probe_active {
capacity_probe_at = Some(Instant::now() + CAPACITY_PROBE_DELAY);
} else if capacity_probe_at.is_some_and(|at| Instant::now() >= at) {
capacity_probe_at = None;
*pump_probe.lock().unwrap() = ProbeState {
active: true,
duration_ms: CAPACITY_PROBE_MS,
..Default::default()
};
if ctrl_tx
.try_send(CtrlRequest::Probe(ProbeRequest {
target_kbps: CAPACITY_PROBE_KBPS,
duration_ms: CAPACITY_PROBE_MS,
}))
.is_ok()
{
capacity_probe_deadline = Some(Instant::now() + CAPACITY_PROBE_TIMEOUT);
tracing::info!(
target_kbps = CAPACITY_PROBE_KBPS,
duration_ms = CAPACITY_PROBE_MS,
"adaptive bitrate: startup link-capacity probe"
);
} else {
pump_probe.lock().unwrap().active = false; // ctrl queue full — skip
}
}
if let Some(deadline) = capacity_probe_deadline {
let mut p = pump_probe.lock().unwrap();
if p.done {
capacity_probe_deadline = None;
// An all-zero reply is a decline (old host / probe-less build) — keep the
// negotiated ceiling. Otherwise: delivered wire kbps × 0.7.
if p.host_duration_ms > 0 && p.delivered_bytes > 0 {
let delivered_kbps = (p.delivered_bytes.saturating_mul(8)
/ p.host_duration_ms.max(1) as u64)
as u32;
let ceiling = delivered_kbps.saturating_mul(7) / 10;
abr.set_ceiling(ceiling);
tracing::info!(
delivered_kbps,
ceiling_kbps = ceiling,
"adaptive bitrate: link-capacity probe done — climb ceiling set"
);
} else {
tracing::info!(
"adaptive bitrate: capacity probe declined — keeping negotiated ceiling"
);
}
// The probe's FLAG_PROBE filler landed in `bytes_received` but never reached
// the decoder — rebase the ABR window's byte counter past it, or the next
// window's "actual throughput" reads as the burst rate and poisons the
// controller's proven-throughput high-water mark with the LINK rate.
last_bytes = st.bytes_received;
} else if Instant::now() >= deadline {
// The host never answered (a build that ignores ProbeRequest): clear the
// stuck-active state so LossReports resume, keep the negotiated ceiling.
p.active = false;
capacity_probe_deadline = None;
tracing::info!(
"adaptive bitrate: capacity probe timed out (old host?) — keeping negotiated ceiling"
);
}
}
if !probe_active && last_report.elapsed() >= ADAPT_REPORT_INTERVAL {
// A no-op clock flush earlier in this window suspected a wall-clock step: fire
// the mid-stream re-sync now (once — the 60 s periodic covers everything else).
if resync_wanted {
resync_wanted = false;
let _ = ctrl_tx.try_send(CtrlRequest::ClockResync);
}
let window_dropped = st.frames_dropped.wrapping_sub(last_dropped);
let loss_ppm = window_loss_ppm(
st.fec_recovered_shards.wrapping_sub(last_recovered),
st.fec_late_shards.wrapping_sub(last_late),
st.packets_received.wrapping_sub(last_received),
window_dropped,
);
let _ = ctrl_tx.try_send(CtrlRequest::Loss(LossReport { loss_ppm }));
// Standing-latency bleed: close the detector's window with this report's loss
// verdict and run its escalation ladder — re-sync first (free; a stale offset
// from a stepped wall clock produces exactly this signature and the applied
// re-sync rebases the floor), then a bounded flush+keyframe (drains a real
// sub-threshold standing backlog the jump-to-live thresholds tolerate), then a
// loud disarm (the path latency itself changed; nothing local fixes that).
match standing_lat.on_window(loss_ppm == 0 && window_dropped == 0) {
StandingLatAction::None => {}
StandingLatAction::Resync { above_ms } => {
tracing::info!(
above_ms,
"standing latency above the session floor with zero loss — \
requesting a clock re-sync first (a stale offset reads exactly \
like this)"
);
let _ = ctrl_tx.try_send(CtrlRequest::ClockResync);
}
StandingLatAction::Bleed { above_ms } => {
// Shares the jump-to-live cooldown: an unexecuted bleed simply re-arms
// over the next windows (the detector's run rebuilds).
if last_flush.is_none_or(|t| t.elapsed() >= FLUSH_COOLDOWN) {
last_flush = Some(Instant::now());
flush_in_window = true;
let flushed = session.flush_backlog().unwrap_or(0);
let dropped = frames.clear();
let _ = ctrl_tx.try_send(CtrlRequest::Keyframe);
standing_lat.bled();
tracing::warn!(
above_ms,
flushed_datagrams = flushed,
dropped_frames = dropped,
"standing latency survived a clock re-sync — bled the local \
backlog (flush + keyframe)"
);
}
}
StandingLatAction::Disarm { above_ms } => {
tracing::warn!(
above_ms,
"standing latency persists after a re-sync and every bleed — not \
local, not clock; the path latency changed. Leaving it be \
(reconnect re-baselines)"
);
}
}
// Adaptive bitrate: drain any host ack first (its clamp is authoritative), then
// feed the controller this window's congestion signals; a decision becomes a
// SetBitrate on the control stream.
if let Some(acked) = bitrate_ack.lock().unwrap().take() {
abr.on_ack(acked);
}
let owd_mean_us =
(owd_frames > 0).then(|| (owd_sum_ns / owd_frames as i128 / 1000) as i64);
(owd_sum_ns, owd_frames) = (0, 0);
// Drain the embedder's decode-latency window (always, so it stays bounded even when
// the controller is disabled) → the mean feeds the decode signal; `None` when the
// embedder reported nothing this window (old embedder / no decoded frames).
let decode_mean_us = {
let mut acc = pump_decode_lat.lock().unwrap();
let (sum, count) = (acc.sum_us, acc.count);
*acc = DecodeLatAcc::default();
(count > 0).then(|| (sum / count as u64) as i64)
};
// The window's ACTUAL delivered throughput — what the pipeline really carried, vs
// the target it was allowed. Wire bytes (headers + FEC) slightly overstate the
// media rate the decoder ingests; acceptable for the climb gate / proven-mark
// semantics (both compare against targets with their own headroom).
let window_ms = last_report.elapsed().as_millis().max(1) as u64;
let actual_kbps = (st.bytes_received.wrapping_sub(last_bytes).saturating_mul(8)
/ window_ms) as u32;
if let Some(kbps) = abr.on_window(
Instant::now(),
window_dropped,
loss_ppm,
owd_mean_us,
decode_mean_us,
actual_kbps,
flush_in_window,
) {
// Log the window's signals alongside the decision so an on-glass session can
// tell a decode-driven re-target (the new signal — decode_mean_us elevated with
// loss/OWD flat) from a network-driven one.
tracing::info!(
kbps,
loss_ppm,
owd_mean_us = owd_mean_us.unwrap_or(-1),
decode_mean_us = decode_mean_us.unwrap_or(-1),
actual_kbps,
flushed = flush_in_window,
"adaptive bitrate: requesting encoder re-target"
);
let _ = ctrl_tx.try_send(CtrlRequest::SetBitrate(kbps));
}
flush_in_window = false;
last_report = Instant::now();
last_recovered = st.fec_recovered_shards;
last_late = st.fec_late_shards;
last_received = st.packets_received;
last_dropped = st.frames_dropped;
last_bytes = st.bytes_received;
if pump_perf_on {
if let Some(p) = session.take_pump_perf() {
let per_pkt_ns = |ns: u64| ns.checked_div(p.packets).unwrap_or(0);
tracing::info!(
recv_ms = p.recv_ns / 1_000_000,
decrypt_ms = p.decrypt_ns / 1_000_000,
reasm_ms = p.reasm_ns / 1_000_000,
packets = p.packets,
batches = p.batches,
pkts_per_batch = p.packets.checked_div(p.batches).unwrap_or(0),
decrypt_ns_pkt = per_pkt_ns(p.decrypt_ns),
reasm_ns_pkt = per_pkt_ns(p.reasm_ns),
"pump stage split (window)"
);
}
// Inter-arrival jitter over the window's completed AUs. `late` counts gaps
// over 2× the window median — the "a frame arrived visibly off-beat" tally.
if arrivals_us.len() >= 8 {
arrivals_us.sort_unstable();
let pct = |q: usize| arrivals_us[(arrivals_us.len() - 1) * q / 100];
let (p50, p95) = (pct(50), pct(95));
let late = arrivals_us.iter().filter(|&&d| d > p50 * 2).count();
tracing::info!(
frames = arrivals_us.len() + 1,
arrival_p50_us = p50,
arrival_p95_us = p95,
arrival_max_us = arrivals_us.last().copied().unwrap_or(0),
late,
"frame inter-arrival jitter (window)"
);
}
arrivals_us.clear();
}
}
match session.poll_frame() {
Ok(frame) => {
if frame.flags & FLAG_PROBE as u32 != 0 {
continue; // speed-test filler, not video — measured via the counters above
}
if pump_perf_on {
let now = Instant::now();
if let Some(prev) = last_arrival.replace(now) {
// 4096 ≈ 17 s at 240 fps — a stuck window can't grow it unbounded.
if arrivals_us.len() < 4096 {
arrivals_us
.push((now - prev).as_micros().min(u32::MAX as u128) as u32);
}
}
}
// Jump-to-live guard. A standing receive/hand-off queue never drains by itself —
// the pump consumes strictly in order at the arrival rate, so once behind, the
// stream stays behind for good (observed live: stuck 67 s). Pre-decode AUs are
// reference-chained (infinite GOP), so we can NOT drop a frame mid-stream to catch
// up; the only safe recovery is to discard the whole backlog and re-anchor decode
// on a fresh keyframe. Two independent "we're behind" signals arm it, both gated by
// FLUSH_COOLDOWN, both suspended during a speed test (the probe MEASURES a saturated
// queue; flushing would corrupt its counters):
// * clock-based — completed frames sit > FLUSH_LATENCY behind the skew-corrected
// capture clock continuously for FLUSH_AFTER. Needs the skew handshake, and
// also catches kernel/reassembler backlog the hand-off queue hasn't reached yet.
// * clock-free — the pre-decode hand-off queue stopped draining: its depth stayed
// ≥ QUEUE_HIGH (never falling to QUEUE_LOW, still high at the trip) for
// STANDING_TIME. Works with no handshake / a same-clock session (where the
// clock path is disarmed), and is the direct signal that the embedder can't
// keep up. A transient Wi-Fi clump drains within ~100 ms and never trips it.
if probe_active {
// Keep both detectors disarmed across a speed test so its (deliberately)
// saturated queue doesn't leave a primed run that fires the moment it ends.
stale_since = None;
standing_since = None;
} else {
let lat_ns = if clock_offset_ns != 0 {
now_realtime_ns() + clock_offset_ns as i128 - frame.pts_ns as i128
} else {
0
};
// Feed the adaptive-bitrate controller's OWD window (mean capture→received
// delay): rising delay under zero loss is queue growth — the pre-loss
// congestion signal. Only meaningful with a clock handshake.
if clock_offset_ns != 0 && lat_ns > 0 {
owd_sum_ns += lat_ns;
owd_frames += 1;
// The standing-latency detector rides the same signal, but off the
// window MINIMUM (robust against jitter/burst spikes — a standing
// state elevates the floor itself). Same 10 s plausibility clamp as
// the hn stats use.
if lat_ns < 10_000_000_000 {
standing_lat.note_frame(lat_ns);
}
}
if clock_detector_armed
&& clock_offset_ns != 0
&& lat_ns > FLUSH_LATENCY.as_nanos() as i128
{
stale_since.get_or_insert_with(Instant::now);
} else {
stale_since = None;
}
let depth = frames.depth();
if depth >= QUEUE_HIGH {
standing_since.get_or_insert_with(Instant::now);
} else if depth <= QUEUE_LOW {
standing_since = None;
}
// The queue trip additionally requires the depth to still be high NOW, so
// a run that started ≥ high but is hovering in the hysteresis band (a
// clump mid-drain) never fires on elapsed time alone.
let clock_behind = stale_since.is_some_and(|t| t.elapsed() >= FLUSH_AFTER);
let queue_behind = depth >= QUEUE_HIGH
&& standing_since.is_some_and(|t| t.elapsed() >= STANDING_TIME);
if (clock_behind || queue_behind)
&& last_flush.is_none_or(|t| t.elapsed() >= FLUSH_COOLDOWN)
{
stale_since = None;
standing_since = None;
last_flush = Some(Instant::now());
flush_in_window = true; // strongest "link can't hold the rate" signal
let flushed = session.flush_backlog().unwrap_or(0);
let dropped = frames.clear();
let _ = ctrl_tx.try_send(CtrlRequest::Keyframe);
tracing::warn!(
behind_ms = if clock_behind { lat_ns / 1_000_000 } else { -1 },
queue_depth = depth,
flushed_datagrams = flushed,
dropped_frames = dropped,
"receive backlog stopped draining — jumped to live (flush + keyframe)"
);
// Clock-detector health check: a clock-only trigger whose flush found
// no local backlog is a false "behind" reading (a wall-clock step, or
// an upstream queue a local flush can't drain) — repeated, it would
// cost a recovery IDR every cooldown forever. Disarm after two in a
// row; the clock-free queue detector keeps covering real backlogs.
if clock_behind
&& !queue_behind
&& flushed < NOOP_FLUSH_DATAGRAMS
&& dropped == 0
{
noop_clock_flushes += 1;
if noop_clock_flushes == 1 {
// First no-op flush = a wall-clock step is the prime
// suspect: ask for an immediate re-sync (sent on the next
// report tick). Applied, it resets these counters and
// re-arms the detector before the disarm below triggers.
resync_wanted = true;
}
if noop_clock_flushes >= NOOP_CLOCK_FLUSHES_TO_DISARM {
clock_detector_armed = false;
tracing::warn!(
"clock-based jump-to-live disarmed — its flushes found no \
local backlog (clock step or upstream queueing suspected); \
the queue-depth detector stays armed"
);
}
} else {
noop_clock_flushes = 0;
}
continue; // this frame is part of the stale past — don't render it
}
}
frames.push(frame);
}
Err(PunktfunkError::NoFrame) => {
std::thread::sleep(Duration::from_micros(300));
}
Err(_) => break,
}
}
// The pump exited (shutdown / fatal session error) — wake any consumer blocked in
// `next_frame` with a Closed signal instead of a spurious timeout (the old mpsc did this
// implicitly when the sender dropped).
frames.close();
}
}