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Update SwappableLock to support NET9+ Lock type #1077

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Update SwappableLock to support NET9+ Lock type #1077

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56 changes: 55 additions & 1 deletion src/DynamicData/Internal/SwappableLock.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,23 +18,73 @@ public static SwappableLock CreateAndEnter(object gate)
return result;
}

#if NET9_0_OR_GREATER
public static SwappableLock CreateAndEnter(Lock gate)
{
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Copilot AI Apr 10, 2026

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On NET9+, the Lock overloads can still receive null at runtime (despite non-nullable annotations). Currently that would throw a NullReferenceException from gate.Enter()/Exit(), unlike the object overloads which throw ArgumentNullException. Consider adding an explicit null guard (e.g., ArgumentNullException.ThrowIfNull(gate)) in CreateAndEnter(Lock) to provide a consistent and clearer failure mode.

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{
{
System.ArgumentNullException.ThrowIfNull(gate);

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gate.Enter();
return new SwappableLock() { _lockGate = gate };
}
#endif

public void SwapTo(object gate)
{
#if NET9_0_OR_GREATER
if (_gate is null && _lockGate is null)
throw new InvalidOperationException("Lock is not initialized");
#else
if (_gate is null)
throw new InvalidOperationException("Lock is not initialized");
#endif

var hasNewLock = false;
Monitor.Enter(gate, ref hasNewLock);

#if NET9_0_OR_GREATER
if (_lockGate is not null)
{
_lockGate.Exit();
_lockGate = null;
}
else
#endif
if (_hasLock)
Monitor.Exit(_gate);
{
Monitor.Exit(_gate!);
}

_hasLock = hasNewLock;
_gate = gate;
}

#if NET9_0_OR_GREATER
public void SwapTo(Lock gate)
{
if (_lockGate is null && _gate is null)
throw new InvalidOperationException("Lock is not initialized");

gate.Enter();

Comment on lines +60 to +66
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Copilot AI Apr 10, 2026

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SwapTo(Lock gate) should guard against a null Lock argument as well; otherwise gate.Enter() will throw NullReferenceException. Adding an explicit ArgumentNullException for a null gate keeps behavior consistent with Monitor.Enter on the object overloads and produces a more actionable exception.

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if (_lockGate is not null)
_lockGate.Exit();
else if (_hasLock)
Monitor.Exit(_gate!);

_lockGate = gate;
_hasLock = false;
_gate = null;
}
Comment on lines +21 to +75
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Copilot AI Apr 10, 2026

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This PR adds new NET9+ behavior (CreateAndEnter(Lock), SwapTo(Lock), and mixed-type swapping/release logic) but there are no tests covering it. Since the test project targets net9.0, it should be feasible to add unit tests that validate swapping object→Lock, Lock→object, and Dispose releasing the correct gate.

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#endif

public void Dispose()
{
#if NET9_0_OR_GREATER
if (_lockGate is not null)
{
_lockGate.Exit();
_lockGate = null;
}
else
#endif
if (_hasLock && (_gate is not null))
{
Monitor.Exit(_gate);
Expand All @@ -45,4 +95,8 @@ public void Dispose()

private bool _hasLock;
private object? _gate;

#if NET9_0_OR_GREATER
private Lock? _lockGate;
#endif
}
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