Ensure custom pool policies corrently use default values when unspecified

Author: DustinCampbell

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/Optional`1.cs

@@ -9,6 +9,9 @@ public readonly struct Optional<T>(T value)
 
     public T Value { get; } = value;
 
+    public T GetValueOrDefault(T defaultValue)
+        => HasValue ? Value : defaultValue;
+
     public static implicit operator Optional<T>(T value)
         => new(value);
 

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/PooledObjects/ArrayBuilderPool`1.Policy.cs

@@ -9,23 +9,36 @@ internal partial class ArrayBuilderPool<T>
 {
     private sealed class Policy : PooledObjectPolicy
     {
-        public static readonly Policy Default = new(DefaultMaximumObjectSize);
+        // This is the default initial capacity for ImmutableArray<T>.Builder.
+        private const int DefaultInitialCapacity = 8;
 
+        public static readonly Policy Default = new(DefaultInitialCapacity, DefaultMaximumObjectSize);
+
+        private readonly int _initialCapacity;
         private readonly int _maximumObjectSize;
 
-        private Policy(int maximumObjectSize)
+        private Policy(int initialCapacity, int maximumObjectSize)
         {
+            ArgHelper.ThrowIfNegative(initialCapacity);
+            ArgHelper.ThrowIfNegative(maximumObjectSize);
+
+            _initialCapacity = initialCapacity;
             _maximumObjectSize = maximumObjectSize;
         }
 
-        public static Policy Create(Optional<int> maximumObjectSize = default)
+        public static Policy Create(
+            Optional<int> initialCapacity = default,
+            Optional<int> maximumObjectSize = default)
         {
-            if (!maximumObjectSize.HasValue || maximumObjectSize.Value == Default._maximumObjectSize)
+            if ((!initialCapacity.HasValue || initialCapacity.Value == Default._initialCapacity) &&
+                (!maximumObjectSize.HasValue || maximumObjectSize.Value == Default._maximumObjectSize))
             {
                 return Default;
             }
 
-            return new(maximumObjectSize.Value);
+            return new(
+                initialCapacity.GetValueOrDefault(DefaultInitialCapacity),
+                maximumObjectSize.GetValueOrDefault(DefaultMaximumObjectSize));
         }
 
         public override ImmutableArray<T>.Builder Create()

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/PooledObjects/ArrayBuilderPool`1.cs

@@ -23,9 +23,10 @@ private ArrayBuilderPool(PooledObjectPolicy policy, Optional<int> poolSize)
     }
 
     public static ArrayBuilderPool<T> Create(
+        Optional<int> initialCapacity = default,
         Optional<int> maximumObjectSize = default,
         Optional<int> poolSize = default)
-        => new(Policy.Create(maximumObjectSize), poolSize);
+        => new(Policy.Create(initialCapacity, maximumObjectSize), poolSize);
 
     public static ArrayBuilderPool<T> Create(PooledObjectPolicy policy, Optional<int> poolSize = default)
         => new(policy, poolSize);

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/PooledObjects/DictionaryBuilderPool`2.Policy.cs

@@ -26,7 +26,7 @@ public static Policy Create(Optional<IEqualityComparer<TKey>?> keyComparer = def
                 return Default;
             }
 
-            return new(keyComparer.Value);
+            return new(keyComparer.GetValueOrDefault(null));
         }
 
         public override ImmutableDictionary<TKey, TValue>.Builder Create()

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/PooledObjects/DictionaryPool`2.Policy.cs

@@ -33,7 +33,9 @@ public static Policy Create(
                 return Default;
             }
 
-            return new(comparer.Value, maximumObjectSize.Value);
+            return new(
+                comparer.GetValueOrDefault(null),
+                maximumObjectSize.GetValueOrDefault(DefaultMaximumObjectSize));
         }
 
         public override Dictionary<TKey, TValue> Create() => new(_comparer);

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/PooledObjects/HashSetPool`1.Policy.cs

@@ -9,7 +9,7 @@ internal partial class HashSetPool<T>
 {
     private sealed class Policy : PooledObjectPolicy
     {
-        public static readonly Policy Default = new(comparer: null, DefaultMaximumObjectSize);
+        public static readonly Policy Default = new(comparer: EqualityComparer<T>.Default, DefaultMaximumObjectSize);
 
         public IEqualityComparer<T> Comparer { get; }
 
@@ -33,7 +33,9 @@ public static Policy Create(
                 return Default;
             }
 
-            return new(comparer.Value, maximumObjectSize.Value);
+            return new(
+                comparer.GetValueOrDefault(EqualityComparer<T>.Default) ?? EqualityComparer<T>.Default,
+                maximumObjectSize.GetValueOrDefault(DefaultMaximumObjectSize));
         }
 
         public override HashSet<T> Create() => new(Comparer);

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/PooledObjects/ListPool`1.Policy.cs

@@ -25,7 +25,7 @@ public static Policy Create(Optional<int> maximumObjectSize = default)
                 return Default;
             }
 
-            return new(maximumObjectSize.Value);
+            return new(maximumObjectSize.GetValueOrDefault(DefaultMaximumObjectSize));
         }
 
         public override List<T> Create() => [];

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/PooledObjects/QueuePool`1.Policy.cs

@@ -25,7 +25,7 @@ public static Policy Create(Optional<int> maximumObjectSize = default)
                 return Default;
             }
 
-            return new(maximumObjectSize.Value);
+            return new(maximumObjectSize.GetValueOrDefault(DefaultMaximumObjectSize));
         }
 
         public override Queue<T> Create() => new();

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/PooledObjects/StackPool`1.Policy.cs

@@ -25,7 +25,7 @@ public static Policy Create(Optional<int> maximumObjectSize = default)
                 return Default;
             }
 
-            return new(maximumObjectSize.Value);
+            return new(maximumObjectSize.GetValueOrDefault(DefaultMaximumObjectSize));
         }
 
         public override Stack<T> Create() => new();

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/PooledObjects/StringBuilderPool.Policy.cs

@@ -25,7 +25,7 @@ public static Policy Create(Optional<int> maximumObjectSize = default)
                 return Default;
             }
 
-            return new(maximumObjectSize.Value);
+            return new(maximumObjectSize.GetValueOrDefault(DefaultMaximumObjectSize));
         }
 
         public override StringBuilder Create() => new();