Commit Graph
7 Commits
Author SHA1 Message Date
dtourolle 80c2b1fb2f fix: try_push must distinguish delivered from discarded
try_push returned bool, and returned *true* for a closed channel — so "the
value arrived" and "the value was thrown away because nobody is listening"
were the same answer.

Every caller was nonetheless correct, because both cases mean "stop trying,
do not park and retry". But nothing above the channel could tell the two
apart: a node counting successful pushes counted discards among them, and the
only record of the loss was the channel's own drop counter, visible solely to
whoever read the diagnostics table.

Now a three-way PushResult { Taken, Full, Closed }, matching the shape
SentinelResult already uses. Behaviour is unchanged at every call site —
each treats Closed the same as Taken, and only Full parks — but the
distinction is now available to anyone who needs it, and a scoped enum means
a future caller cannot silently reintroduce the conflation with `if (push)`.

deliver_one benefits immediately: it no longer reaches its teardown path for
a closed channel, only for one that is still full, so the last-ditch throwing
push it does there to record the loss now records an overflow rather than a
drop the channel had already counted.
2026-08-05 16:14:50 +02:00
dtourolle a8cfe7300a fix: a lossless fanout, a node that starts awake, and the instrumentation that found them
Three changes from one debugging session on the intermittent wedge, kept
together because the instrumentation is what made the other two findable.

**Fanout was never made lossless.** 6595e6e made node outputs lossless and
28e0667 stopped them parking a worker; FanoutNode was in neither and kept
`catch (ChannelOverflowError&) {}` per output. Whichever branch fell behind
lost items, silently, by an amount that depended on timing — so two runs of
the same input could disagree. deliver() now retries each output
independently until it is taken, rechecking stop_flag_ every pass so
teardown cannot hang on a full output. A fanout owns a private thread, so
waiting costs no scheduler worker.

**A node could start with a wake already outstanding.** start() enables the
input channel several statements before it installs the push callback, and
StaticNetwork starts nodes sources-first, so an upstream node is already
firing into the gap. A push landing there is accepted by the ring but wakes
nobody: push_callback_ fires only on the empty→non-empty transition, and at
that instant the callback is null. Every later push sees a non-empty ring
and stays silent, so the node is never submitted. Asking on_input_ready()
once at the end of start() converts the missed edge into a state check.

The signature is distinctive — zero items delivered, not a stall partway.
Under `ctest -j4` on a loaded machine it reproduced 7 times in 24 and never
in 10 unloaded runs, which is almost certainly the "~1 run in 20" hang
28e0667 recorded as known-incomplete.

**NodeSnapshot now carries scheduling state and a true exec total.** queued
and wake_pending make the 9c5ce5f invariant observable at runtime; it could
previously only be inspected in a debugger, and the bug does not reproduce
under one. total_exec_us is a real sum — frames × ema_exec_us tracks the
tail of a run, not the whole of it, and diverges badly on a workload whose
per-frame cost varies. Both are exposed over the web debug JSON so a wedged
pipeline can be interrogated without attaching to it.
2026-08-05 12:40:03 +02:00
dtourolle f6bcaa15b0 Performance improvements, better readme and complete python bindings
🧪 Test / test (push) Failing after 28m30s
2026-05-12 21:23:33 +02:00
dtourolle 9acc42b2e9 Fix fanout naming for debug graph
🧪 Test / test (push) Failing after 2m38s
2026-05-09 09:54:40 +02:00
dtourolle da8f4d9926 Add debug graph to static network 2026-05-09 08:59:19 +02:00
dtourolle 9ce581b5ce Fixed bug when generating identical fanouts 2026-05-09 08:36:51 +02:00
dtourolle 2bca2a7554 Add static network
🧪 Test / test (push) Successful in 6m4s
2026-05-08 20:00:15 +02:00