The T21 press pass 1 test host died at exit with "A callback was made on a garbage
collected delegate of type ...plctag+callback_func_ex::Invoke". The cause is in
libplctag.NET 1.5.2. When a tag's create fails, for example with NotFound,
InitializeAsync throws with the callback still registered. Dispose() destroys a tag
only if it is initialised, so the native tag outlives its wrapper. The GC then frees
the delegate, and libplctag's atexit plc_tag_shutdown raises DESTROYED into it.
Reproduced against ab_server: the production LibplctagTagRuntime with a NotFound tag
exits 134 with that exact message, and exits 0 with this fix.
A timed-out create unregisters its callback but never destroys the handle either,
so that native tag keeps reconnecting for the life of the process.
The fix adds LibplctagOrphanRelease (AbCip and AbLegacy). After a failed
initialise/read/write that leaves the tag uninitialised, it reads the handle through
the pinned wrapper's private fields, unregisters the callback and destroys the tag.
If those fields cannot be read, it roots the tag for the life of the process
instead. It is applied in both tag runtimes, the symbol-listing reader and the
template reader. GetStatus keeps the status the tag held before it was destroyed.
Pins: offline refused-connection tests in AbCip.Tests and AbLegacy.Tests, a live
NotFound test on ab_server, and a reflection-shape pin. All go red with the release
disabled. The differential harness also asserts that no orphan had to be rooted.
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
- AbCip/AbLegacy driver forms gain a Transport InputSelect; FromOptions/ToOptions now carry
Transport, so saving any other field no longer silently reverts Native to libplctag.
- Both drivers log the constructed transport once per init.
- AbCip factory now takes the host ILoggerFactory (it ran on NullLogger in production, hiding
every AbCip log line); DriverFactoryBootstrap passes it.
- Gate results: AdminUI /run (T19) native, inverted (dead port) and libplctag legs.
The libplctag adapters assigned Tag.Path straight from the device's parsed
CipPath. A device address with no route (ab://host:44818/ - the normal
Micro800 form, and a MicroLogix with no route) parses to "", and libplctag
rejects an empty path attribute with ErrorBadData; omitting the attribute
(null) is what it accepts. So Micro800 could not connect on the default
libplctag transport.
This predates the native transport work and exists on master.
Add an internal LibplctagPath.Normalize helper per driver project (blank ->
null) and route all four Tag constructions through it (AbCip tag runtime,
symbol-list enumerator, template reader; AbLegacy tag runtime). The runtime
tag construction is extracted to an internal BuildTag so tests can inspect
Tag.Path without connecting. Tests fail with Normalize reverted to identity.
Update the Micro800 smoke-test comment: both transports are expected to pass.
ab_server answers every Execute PCCC with a fixed requestor id (pccc.c
PCCC_RESP_PREFIX: 07 3D F3 45 43 50 21) instead of echoing the request's, so
the R14-3 echo check rejected every native reply sent under the 0x1337 CIP
originator identity as BadReply. The pooled runtime now sends libplctag's
identity (PcccServices.RequestorVendor/RequestorSerial), which passes the echo
check against ab_server and against a real controller that echoes. Pinned by a
FakeEipServer round trip that answers with ab_server's fixed prefix.
ab_server's RegisterSession sanity check rejects any non-zero sender context
with encapsulation status 1 and a header-only reply, so every native session
against the simulator failed with BadCommunicationError. libplctag sends zero
(logix-register-session.hex); the codec test now matches that capture byte for
byte instead of excluding the context, and a client test pins the zero on the wire.
Scheduler tests (exclusive mid-queue and at head) and a template-reader test that
genuinely queues a Read Template behind a small read; bounded QueuedCount wait
replaces the fixed delay. Falsified: removing exclusive from the reader turns the
reader test red; removing the Exclusive handling in RequestScheduler turns all three red.
Joseph Doherty