The IDD-push consume loop acquired the slot's keyed mutex by hand
(`AcquireSync(0,8)` … work … `ReleaseSync(0)`), with a comment warning that a
`?`-return between acquire and release would leak the lock and stall the driver
on that slot — the reason the HDR converter is built *before* the acquire.
Replace with a `KeyedMutexGuard` RAII (acquire → `ReleaseSync` on drop), scoped
to JUST the convert/copy block so the lock releases at the EXACT same point as
before (the driver gets the slot back immediately; not held across the rest of
`try_consume`). Now the release can't be skipped on any early return/panic — the
leak footgun is gone by construction, and the hot loop has no raw `ReleaseSync`.
Behavior/latency-equivalent (same acquire params, same release point). Windows-
only (CI + on-glass gated); to be validated on the RTX box (host clippy build +
a PERF=1 latency A/B vs the shipping binary — the change should show no delta).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler
658564353c