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fix alternate lookup GetOrAdd for AtomicFactoryCache #761

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Merged
bitfaster merged 2 commits into from
Apr 13, 2026
+31 −20
Merged

fix alternate lookup GetOrAdd for AtomicFactoryCache #761

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f8930a3
fix
Apr 13, 2026
f408296
cleanup tests
Apr 13, 2026
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14 changes: 5 additions & 9 deletions BitFaster.Caching.UnitTests/Atomic/AtomicFactoryCacheAlternateLookupTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -77,21 +77,19 @@ public void AlternateLookupGetOrAddUsesActualKeyOnMissAndHit()
var factoryCalls = 0;
ReadOnlySpan<char> key = "42";

alternate.GetOrAdd(key, key =>
alternate.GetOrAdd(key, k =>
{
factoryCalls++;
return $"value-{key}";
return $"value-{k}";
}).Should().Be("value-42");

alternate.GetOrAdd(key, (_, prefix) =>
alternate.GetOrAdd(key, k =>
{
factoryCalls++;
return prefix;
}, "unused").Should().Be("value-42");
return "1";
}).Should().Be("value-42");

factoryCalls.Should().Be(1);
cache.TryGet("42", out var value).Should().BeTrue();
value.Should().Be("value-42");
}

[Fact]
Expand All @@ -114,8 +112,6 @@ public void AlternateLookupGetOrAddWithArgUsesActualKeyOnMissAndHit()
}, "unused").Should().Be("value-42");

factoryCalls.Should().Be(1);
cache.TryGet("42", out var value).Should().BeTrue();
value.Should().Be("value-42");
}

[Fact]
Expand Down
37 changes: 26 additions & 11 deletions BitFaster.Caching/Atomic/AtomicFactoryCache.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Threading.Tasks;

namespace BitFaster.Caching.Atomic
{
Expand Down Expand Up @@ -176,7 +177,8 @@ public IAlternateLookup<TAlternateKey, K, V> GetAlternateLookup<TAlternateKey>()
where TAlternateKey : notnull, allows ref struct
{
var inner = cache.GetAlternateLookup<TAlternateKey>();
return new AlternateLookup<TAlternateKey>(inner);
var comparer = (IAlternateEqualityComparer<TAlternateKey, K>)cache.Comparer;
return new AlternateLookup<TAlternateKey>(inner, comparer);
}

///<inheritdoc/>
Expand All @@ -185,7 +187,8 @@ public bool TryGetAlternateLookup<TAlternateKey>([MaybeNullWhen(false)] out IAlt
{
if (cache.TryGetAlternateLookup<TAlternateKey>(out var inner))
{
lookup = new AlternateLookup<TAlternateKey>(inner);
var comparer = (IAlternateEqualityComparer<TAlternateKey, K>)cache.Comparer;
lookup = new AlternateLookup<TAlternateKey>(inner, comparer);
return true;
}

Expand All @@ -197,10 +200,12 @@ public bool TryGetAlternateLookup<TAlternateKey>([MaybeNullWhen(false)] out IAlt
where TAlternateKey : notnull, allows ref struct
{
private readonly IAlternateLookup<TAlternateKey, K, AtomicFactory<K, V>> inner;
private readonly IAlternateEqualityComparer<TAlternateKey, K> comparer;

internal AlternateLookup(IAlternateLookup<TAlternateKey, K, AtomicFactory<K, V>> inner)
internal AlternateLookup(IAlternateLookup<TAlternateKey, K, AtomicFactory<K, V>> inner, IAlternateEqualityComparer<TAlternateKey, K> comparer)
{
this.inner = inner;
this.comparer = comparer;
}

public bool TryGet(TAlternateKey key, [MaybeNullWhen(false)] out V value)
Expand Down Expand Up @@ -239,18 +244,28 @@ public void AddOrUpdate(TAlternateKey key, V value)

public V GetOrAdd(TAlternateKey key, Func<K, V> valueFactory)
{
var atomicFactory = inner.GetOrAdd(key,
static (k, factory) => new AtomicFactory<K, V>(factory(k)),
valueFactory);
return atomicFactory.ValueIfCreated!;
var atomicFactory = inner.GetOrAdd(key, _ => new AtomicFactory<K, V>());

if (atomicFactory.IsValueCreated)
{
return atomicFactory.ValueIfCreated!;
}

K actualKey = comparer.Create(key);
return atomicFactory.GetValue(actualKey, valueFactory);
}

public V GetOrAdd<TArg>(TAlternateKey key, Func<K, TArg, V> valueFactory, TArg factoryArgument)
{
var atomicFactory = inner.GetOrAdd(key,
static (k, args) => new AtomicFactory<K, V>(args.valueFactory(k, args.factoryArgument)),
(valueFactory, factoryArgument));
return atomicFactory.ValueIfCreated!;
var atomicFactory = inner.GetOrAdd(key, _ => new AtomicFactory<K, V>());

if (atomicFactory.IsValueCreated)
{
return atomicFactory.ValueIfCreated!;
}

K actualKey = comparer.Create(key);
return atomicFactory.GetValue(actualKey, valueFactory, factoryArgument);
}
}
#endif
Expand Down
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