Record what the smppload bind actually does, and what is still untested

2026-09-20 23:48:09 +02:00
parent b85d1f1dab
commit cbd1190b96
1 changed files with 22 additions and 1 deletions
@@ -39,7 +39,28 @@ Traced as far as `oserl`'s `smpp_pdu_syntax:pack/2` (the `trx_deadlock_fix_1` br
 `rebar.config` pins), which builds the header as plain 32-bit bit-syntax
 (`<<Len:32, CmdId:32, 0:32, SeqNum:32>>`) - correct on inspection, so the corruption happens
 somewhere between that call and the socket write, not chased further given the time-box. Reproduced
-identically on three separate runs (byte-for-byte). Recorded as **blocked**; `smppload.test.ts`
+Re-examined 2026-09-20 to see whether it could be unblocked for the throughput comparison in
 `benchmarks/`. Four things are now established, and one earlier suspicion is ruled out:
 - **It is one write, not a split one.** A raw listener that accumulates every chunk rather than
  reading the first receives `40 octets across 1 chunks`, byte-identical to the 2026-09-06 capture,
  with `command_length` reading 2,752,512. So the two leading zero octets are absent from the socket
  write itself; nothing about our framing or the capture is involved.
 - **The compiled `pack/2` is correct**, checked in the built tree rather than the repository:
  `Len = size(BodyBin) + 16` written as `<<Len:32, CmdId:32, 0:32, SeqNum:32>>`, returned as the
  iolist `[Header, BodyBin]`. For this bind that is 16 + 26 = 42.
 - **The remaining suspect is `smpp_session.erl:158`**, which writes with `erlang:port_command/2`
  rather than `gen_tcp:send/2` — an undocumented fast path in oserl code that predates OTP 27.
 - **That suspect is untested.** Two attempts to swap it were both invalidated by rebar3 dep caching:
  editing a fetched dependency's source does not rebuild its beam, and the `_checkouts/` route
  re-verifies every dependency, which needs network and git in the build container. Whoever picks
  this up should patch before the first compile, or force the dep to rebuild, and confirm the beam
  actually changed before believing a result.
 Enough for an upstream report — a reproducer needing no SMSC, the exact octets, and a named
 suspect — but not enough for a patch, since the one-line candidate has never actually run.
 Recorded as **blocked**; `smppload.test.ts`
 keeps a live reproducer asserting what our server does when it receives it (refuses the stream as
 unframeable - see Scenarios) rather than removing the peer. `smpp-dumb-client` covers S9, and
 substitutes for S6 and (partially) S8 - see below.