Reinstate caching in schema generation (#5908)

* Reinstate caching in schema generation

* Address feedback.

* Only cache on the AIFunctionFactory level.

* Reorder properties,

* Rename serialization helper.

Author: eiriktsarpalis

src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonSchemaCreateOptions.cs

@@ -4,12 +4,14 @@
 using System;
 using System.Text.Json.Nodes;
 
+#pragma warning disable S1067 // Expressions should not be too complex
+
 namespace Microsoft.Extensions.AI;
 
 /// <summary>
 /// Provides options for configuring the behavior of <see cref="AIJsonUtilities"/> JSON schema creation functionality.
 /// </summary>
-public sealed class AIJsonSchemaCreateOptions
+public sealed class AIJsonSchemaCreateOptions : IEquatable<AIJsonSchemaCreateOptions>
 {
     /// <summary>
     /// Gets the default options instance.
@@ -40,4 +42,21 @@ public sealed class AIJsonSchemaCreateOptions
     /// Gets a value indicating whether to mark all properties as required in the schema.
     /// </summary>
     public bool RequireAllProperties { get; init; } = true;
+
+    /// <inheritdoc/>
+    public bool Equals(AIJsonSchemaCreateOptions? other)
+    {
+        return other is not null &&
+            TransformSchemaNode == other.TransformSchemaNode &&
+            IncludeTypeInEnumSchemas == other.IncludeTypeInEnumSchemas &&
+            DisallowAdditionalProperties == other.DisallowAdditionalProperties &&
+            IncludeSchemaKeyword == other.IncludeSchemaKeyword &&
+            RequireAllProperties == other.RequireAllProperties;
+    }
+
+    /// <inheritdoc />
+    public override bool Equals(object? obj) => obj is AIJsonSchemaCreateOptions other && Equals(other);
+
+    /// <inheritdoc />
+    public override int GetHashCode() => (TransformSchemaNode, IncludeTypeInEnumSchemas, DisallowAdditionalProperties, IncludeSchemaKeyword, RequireAllProperties).GetHashCode();
 }

src/Libraries/Microsoft.Extensions.AI/Functions/AIFunctionFactory.Utilities.cs

@@ -1,6 +1,10 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System;
+using System.Buffers;
+using System.IO;
+using System.Reflection;
 using System.Text.RegularExpressions;
 using Microsoft.Shared.Diagnostics;
 
@@ -30,4 +34,104 @@ internal static string SanitizeMemberName(string memberName)
     private static Regex InvalidNameCharsRegex() => _invalidNameCharsRegex;
     private static readonly Regex _invalidNameCharsRegex = new("[^0-9A-Za-z_]", RegexOptions.Compiled);
 #endif
+
+    /// <summary>Invokes the MethodInfo with the specified target object and arguments.</summary>
+    private static object? ReflectionInvoke(MethodInfo method, object? target, object?[]? arguments)
+    {
+#if NET
+        return method.Invoke(target, BindingFlags.DoNotWrapExceptions, binder: null, arguments, culture: null);
+#else
+        try
+        {
+            return method.Invoke(target, BindingFlags.Default, binder: null, arguments, culture: null);
+        }
+        catch (TargetInvocationException e) when (e.InnerException is not null)
+        {
+            // If we're targeting .NET Framework, such that BindingFlags.DoNotWrapExceptions
+            // is ignored, the original exception will be wrapped in a TargetInvocationException.
+            // Unwrap it and throw that original exception, maintaining its stack information.
+            System.Runtime.ExceptionServices.ExceptionDispatchInfo.Capture(e.InnerException).Throw();
+            throw;
+        }
+#endif
+    }
+
+    /// <summary>
+    /// Implements a simple write-only memory stream that uses pooled buffers.
+    /// </summary>
+    private sealed class PooledMemoryStream : Stream
+    {
+        private const int DefaultBufferSize = 4096;
+        private byte[] _buffer;
+        private int _position;
+
+        public PooledMemoryStream(int initialCapacity = DefaultBufferSize)
+        {
+            _buffer = ArrayPool<byte>.Shared.Rent(initialCapacity);
+            _position = 0;
+        }
+
+        public ReadOnlySpan<byte> GetBuffer() => _buffer.AsSpan(0, _position);
+        public override bool CanWrite => true;
+        public override bool CanRead => false;
+        public override bool CanSeek => false;
+        public override long Length => _position;
+        public override long Position
+        {
+            get => _position;
+            set => throw new NotSupportedException();
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            EnsureNotDisposed();
+            EnsureCapacity(_position + count);
+
+            Buffer.BlockCopy(buffer, offset, _buffer, _position, count);
+            _position += count;
+        }
+
+        public override void Flush()
+        {
+        }
+
+        public override int Read(byte[] buffer, int offset, int count) => throw new NotSupportedException();
+        public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();
+        public override void SetLength(long value) => throw new NotSupportedException();
+
+        protected override void Dispose(bool disposing)
+        {
+            if (_buffer is not null)
+            {
+                ArrayPool<byte>.Shared.Return(_buffer);
+                _buffer = null!;
+            }
+
+            base.Dispose(disposing);
+        }
+
+        private void EnsureCapacity(int requiredCapacity)
+        {
+            if (requiredCapacity <= _buffer.Length)
+            {
+                return;
+            }
+
+            int newCapacity = Math.Max(requiredCapacity, _buffer.Length * 2);
+            byte[] newBuffer = ArrayPool<byte>.Shared.Rent(newCapacity);
+            Buffer.BlockCopy(_buffer, 0, newBuffer, 0, _position);
+
+            ArrayPool<byte>.Shared.Return(_buffer);
+            _buffer = newBuffer;
+        }
+
+        private void EnsureNotDisposed()
+        {
+            if (_buffer is null)
+            {
+                Throw();
+                static void Throw() => throw new ObjectDisposedException(nameof(PooledMemoryStream));
+            }
+        }
+    }
 }