Update SwappableLock to support NET9+ Lock type - #1077
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dwcullop merged 4 commits intoApr 17, 2026
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Add Lock overloads for SwappableLock.SwapTo and constructor to support the new System.Threading.Lock type on .NET 9+. Uses #if NET9_0_OR_GREATER conditional compilation. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
dwcullop
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Pull request overview
Adds .NET 9+ System.Threading.Lock support to SwappableLock so ObservableCache can atomically swap between synchronization primitives without forcing object/Monitor locks on newer runtimes.
Changes:
- Added
CreateAndEnter(Lock gate)factory for NET9+. - Added
SwapTo(Lock gate)overload and updatedSwapTo(object gate)to correctly release whichever gate type is currently held. - Updated
Dispose()to release a heldLockon NET9+.
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JakenVeina
requested changes
Apr 13, 2026
… tests Replace #if spaghetti throughout every method with two complete, independent implementations behind a single top-level #if NET9_0_OR_GREATER. NET9: uses System.Threading.Lock directly (simpler, no _hasLock bool needed). Pre-NET9: uses Monitor.Enter/Exit on object gates (unchanged behavior). Filter.Dynamic: gates upgraded to Lock on NET9 for consistency. Added SwappableLockFixture with 7 tests covering CreateAndEnter, Dispose (release + idempotent), SwapTo (basic + chained), uninitialized throws, and Dispose after swap.
dwcullop
enabled auto-merge (squash)
April 13, 2026 17:27
JakenVeina
approved these changes
Apr 14, 2026
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Problem
SwappableLockis aref structused internally byFilter.Dynamicto atomically swap between lock objects during filtered changeset processing. It originally only supportedMonitor.Enter/Monitor.Exitonobjectgates..NET 9 introduced
System.Threading.Lock: a dedicated, more efficient lock type that is non-reentrant and does not supportMonitor.Enter. Code paths that useLockon .NET 9 were incompatible withSwappableLock.Approach
Instead of sprinkling
#if NET9_0_OR_GREATERthroughout every method (mixingLockandobjectstate in the same struct), we splitSwappableLockinto two complete, independent implementations behind a single top-level#if:System.Threading.Lockdirectly. Simpler (no_hasLockbool needed,Locktracks its own state).Monitor.Enter/Exitonobjectgates. Unchanged behavior from the original.Each implementation is self-contained and readable without mental
#ifgymnastics.Changes
Internal/SwappableLock.cs- Two complete implementations behind top-level#if. NET9 version usesLock.Cache/Internal/Filter.Dynamic.cs- Gate properties returnLockon NET9,objectotherwise. DedicatedLockfields on NET9.Tests/Internal/SwappableLockFixture.cs- New. 7 tests covering CreateAndEnter, Dispose (release + idempotent), SwapTo (basic + chained), uninitialized throws, and Dispose after swap.Zero behavioral change on pre-.NET 9 targets.