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fix(driver-abcip): resolve Medium code-review finding (Driver.AbCip-010)

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Add `EvictRuntime` helper that removes + disposes a stale
`ConcurrentDictionary` entry. Call it from `ReadSingleAsync`,
`ReadGroupAsync`, and `WriteAsync` on non-zero libplctag status and
transport exceptions so the next call for the same tag re-creates a
fresh handle — mirroring the probe loop's recreate-on-failure pattern.
Value-conversion exceptions (NotSupportedException, FormatException,
InvalidCastException, OverflowException) are not transport faults and
do not evict the handle.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Joseph Doherty
2026-05-22 09:24:45 -04:00
parent a17de80cdb
commit 72728a5d45
2 changed files with 40 additions and 6 deletions
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code-reviews/Driver.AbCip/findings.md
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@@ -168,13 +168,13 @@
| Severity | Medium |
| Category | Error handling & resilience |
| Location | `AbCipDriver.cs:621-648`, `AbCipDriver.cs:346-391` |
| Status | Open |
| Status | Resolved |
**Description:** Once `EnsureTagRuntimeAsync` successfully creates and initializes a `LibplctagTagRuntime`, that runtime is cached for the lifetime of the device and never re-created on failure. If the underlying native tag enters a permanently-bad state (connection dropped, controller rebooted, tag handle invalidated by a PLC program download), every subsequent `ReadAsync`/`WriteAsync` reuses the same dead handle and returns errors forever. The probe loop does tear down and recreate its runtime after a failure, but the read/write path has no equivalent recovery; only a full `ReinitializeAsync` (itself broken, see Driver.AbCip-001) clears the cache. The normal data path should self-heal from a transient handle fault without operator-driven reinitialize.
**Recommendation:** On a non-zero libplctag status or transport exception in `ReadSingleAsync`/`ReadGroupAsync`/`WriteAsync`, evict the offending runtime from `device.Runtimes` (and dispose it) so the next call re-creates and re-initializes it. Mirror the probe loop recreate-on-failure behavior.
**Resolution:** _(open)_
**Resolution:** Resolved 2026-05-22 — added `EvictRuntime(device, tagName)` helper that calls `ConcurrentDictionary.TryRemove` + disposes the evicted instance; called from `ReadSingleAsync`, `ReadGroupAsync`, and `WriteAsync` on both non-zero libplctag status and transport exceptions (type/value-conversion exceptions are not transport faults and do not evict). The next read/write for the affected tag re-runs `EnsureTagRuntimeAsync`, which creates and initializes a fresh handle, mirroring the probe loop's recreate-on-failure behaviour.
### Driver.AbCip-011