Offer API to adjust the ArrayPool

src/MessagePack.UnityClient/Assets/Scripts/MessagePack/Formatters/CollectionFormatter.cs

@@ -346,7 +346,7 @@ public void Serialize(ref MessagePackWriter writer, TCollection value, MessagePa
                     }
                     else
                     {
-                        using (var scratchRental = SequencePool.Shared.Rent())
+                        using (var scratchRental = options.Pool.Rent())
                         {
                             var scratch = scratchRental.Value;
                             MessagePackWriter scratchWriter = writer.Clone(scratch);
@@ -950,7 +950,7 @@ public void Serialize(ref MessagePackWriter writer, IEnumerable value, MessagePa
 
             IMessagePackFormatter<object> formatter = options.Resolver.GetFormatterWithVerify<object>();
 
-            using (var scratchRental = SequencePool.Shared.Rent())
+            using (var scratchRental = options.Pool.Rent())
             {
                 var scratch = scratchRental.Value;
                 MessagePackWriter scratchWriter = writer.Clone(scratch);

src/MessagePack.UnityClient/Assets/Scripts/MessagePack/Formatters/TypelessFormatter.cs

@@ -202,7 +202,7 @@ public void Serialize(ref MessagePackWriter writer, object value, MessagePackSer
             }
 
             // mark will be written at the end, when size is known
-            using (var scratchRental = SequencePool.Shared.Rent())
+            using (var scratchRental = options.Pool.Rent())
             {
                 MessagePackWriter scratchWriter = writer.Clone(scratchRental.Value);
                 scratchWriter.WriteString(typeName);

src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializer.Json.cs

@@ -21,7 +21,9 @@ public partial class MessagePackSerializer
         /// <exception cref="MessagePackSerializationException">Thrown if an error occurs during serialization.</exception>
         public static void SerializeToJson<T>(TextWriter textWriter, T obj, MessagePackSerializerOptions options = null, CancellationToken cancellationToken = default)
         {
-            using (var sequenceRental = SequencePool.Shared.Rent())
+            options = options ?? DefaultOptions;
+
+            using (var sequenceRental = options.Pool.Rent())
             {
                 var msgpackWriter = new MessagePackWriter(sequenceRental.Value)
                 {
@@ -85,7 +87,7 @@ public static void ConvertToJson(ref MessagePackReader reader, TextWriter jsonWr
             {
                 if (options.Compression.IsCompression())
                 {
-                    using (var scratchRental = SequencePool.Shared.Rent())
+                    using (var scratchRental = options.Pool.Rent())
                     {
                         if (TryDecompress(ref reader, scratchRental.Value))
                         {
@@ -133,7 +135,9 @@ public static void ConvertFromJson(string str, ref MessagePackWriter writer, Mes
         /// </summary>
         public static byte[] ConvertFromJson(string str, MessagePackSerializerOptions options = null, CancellationToken cancellationToken = default)
         {
-            using (var scratchRental = SequencePool.Shared.Rent())
+            options = options ?? DefaultOptions;
+
+            using (var scratchRental = options.Pool.Rent())
             {
                 var writer = new MessagePackWriter(scratchRental.Value)
                 {
@@ -155,14 +159,15 @@ public static byte[] ConvertFromJson(string str, MessagePackSerializerOptions op
         public static void ConvertFromJson(TextReader reader, ref MessagePackWriter writer, MessagePackSerializerOptions options = null)
         {
             options = options ?? DefaultOptions;
+
             if (options.Compression.IsCompression())
             {
-                using (var scratchRental = SequencePool.Shared.Rent())
+                using (var scratchRental = options.Pool.Rent())
                 {
                     MessagePackWriter scratchWriter = writer.Clone(scratchRental.Value);
                     using (var jr = new TinyJsonReader(reader, false))
                     {
-                        FromJsonCore(jr, ref scratchWriter);
+                        FromJsonCore(jr, ref scratchWriter, options);
                     }
 
                     scratchWriter.Flush();
@@ -173,12 +178,12 @@ public static void ConvertFromJson(TextReader reader, ref MessagePackWriter writ
             {
                 using (var jr = new TinyJsonReader(reader, false))
                 {
-                    FromJsonCore(jr, ref writer);
+                    FromJsonCore(jr, ref writer, options);
                 }
             }
         }
 
-        private static uint FromJsonCore(TinyJsonReader jr, ref MessagePackWriter writer)
+        private static uint FromJsonCore(TinyJsonReader jr, ref MessagePackWriter writer, MessagePackSerializerOptions options)
         {
             uint count = 0;
             while (jr.Read())
@@ -189,10 +194,10 @@ private static uint FromJsonCore(TinyJsonReader jr, ref MessagePackWriter writer
                         break;
                     case TinyJsonToken.StartObject:
                         // Set up a scratch area to serialize the collection since we don't know its length yet, which must be written first.
-                        using (var scratchRental = SequencePool.Shared.Rent())
+                        using (var scratchRental = options.Pool.Rent())
                         {
                             MessagePackWriter scratchWriter = writer.Clone(scratchRental.Value);
-                            var mapCount = FromJsonCore(jr, ref scratchWriter);
+                            var mapCount = FromJsonCore(jr, ref scratchWriter, options);
                             scratchWriter.Flush();
 
                             mapCount = mapCount / 2; // remove propertyname string count.
@@ -206,10 +211,10 @@ private static uint FromJsonCore(TinyJsonReader jr, ref MessagePackWriter writer
                         return count; // break
                     case TinyJsonToken.StartArray:
                         // Set up a scratch area to serialize the collection since we don't know its length yet, which must be written first.
-                        using (var scratchRental = SequencePool.Shared.Rent())
+                        using (var scratchRental = options.Pool.Rent())
                         {
                             MessagePackWriter scratchWriter = writer.Clone(scratchRental.Value);
-                            var arrayCount = FromJsonCore(jr, ref scratchWriter);
+                            var arrayCount = FromJsonCore(jr, ref scratchWriter, options);
                             scratchWriter.Flush();
 
                             writer.WriteArrayHeader(arrayCount);
@@ -299,7 +304,7 @@ private static void ToJsonCore(ref MessagePackReader reader, TextWriter writer,
                     WriteJsonString(reader.ReadString(), writer);
                     break;
                 case MessagePackType.Binary:
-                    ArraySegment<byte> segment = ByteArraySegmentFormatter.Instance.Deserialize(ref reader, DefaultOptions);
+                    ArraySegment<byte> segment = ByteArraySegmentFormatter.Instance.Deserialize(ref reader, options);
                     writer.Write("\"" + Convert.ToBase64String(segment.Array, segment.Offset, segment.Count) + "\"");
                     break;
                 case MessagePackType.Array:

src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializer.cs

@@ -79,7 +79,7 @@ public static void Serialize<T>(ref MessagePackWriter writer, T value, MessagePa
             {
                 if (options.Compression.IsCompression() && !PrimitiveChecker<T>.IsMessagePackFixedSizePrimitive)
                 {
-                    using (var scratchRental = SequencePool.Shared.Rent())
+                    using (var scratchRental = options.Pool.Rent())
                     {
                         var scratch = scratchRental.Value;
                         MessagePackWriter scratchWriter = writer.Clone(scratch);
@@ -119,7 +119,8 @@ public static byte[] Serialize<T>(T value, MessagePackSerializerOptions options
                 scratchArray = array = new byte[65536];
             }
 
-            var msgpackWriter = new MessagePackWriter(SequencePool.Shared, array)
+            options = options ?? DefaultOptions;
+            var msgpackWriter = new MessagePackWriter(options.Pool, array)
             {
                 CancellationToken = cancellationToken,
             };
@@ -137,8 +138,10 @@ public static byte[] Serialize<T>(T value, MessagePackSerializerOptions options
         /// <exception cref="MessagePackSerializationException">Thrown when any error occurs during serialization.</exception>
         public static void Serialize<T>(Stream stream, T value, MessagePackSerializerOptions options = null, CancellationToken cancellationToken = default)
         {
+            options = options ?? DefaultOptions;
             cancellationToken.ThrowIfCancellationRequested();
-            using (SequencePool.Rental sequenceRental = SequencePool.Shared.Rent())
+
+            using (SequencePool.Rental sequenceRental = options.Pool.Rent())
             {
                 Serialize<T>(sequenceRental.Value, value, options, cancellationToken);
 
@@ -168,8 +171,10 @@ public static void Serialize<T>(Stream stream, T value, MessagePackSerializerOpt
         /// <exception cref="MessagePackSerializationException">Thrown when any error occurs during serialization.</exception>
         public static async Task SerializeAsync<T>(Stream stream, T value, MessagePackSerializerOptions options = null, CancellationToken cancellationToken = default)
         {
+            options = options ?? DefaultOptions;
             cancellationToken.ThrowIfCancellationRequested();
-            using (SequencePool.Rental sequenceRental = SequencePool.Shared.Rent())
+
+            using (SequencePool.Rental sequenceRental = options.Pool.Rent())
             {
                 Serialize<T>(sequenceRental.Value, value, options, cancellationToken);
 
@@ -222,7 +227,7 @@ public static T Deserialize<T>(ref MessagePackReader reader, MessagePackSerializ
             {
                 if (options.Compression.IsCompression())
                 {
-                    using (var msgPackUncompressedRental = SequencePool.Shared.Rent())
+                    using (var msgPackUncompressedRental = options.Pool.Rent())
                     {
                         var msgPackUncompressed = msgPackUncompressedRental.Value;
                         if (TryDecompress(ref reader, msgPackUncompressed))
@@ -315,12 +320,14 @@ public static T Deserialize<T>(ReadOnlyMemory<byte> buffer, MessagePackSerialize
         /// </remarks>
         public static T Deserialize<T>(Stream stream, MessagePackSerializerOptions options = null, CancellationToken cancellationToken = default)
         {
+            options = options ?? DefaultOptions;
+
             if (TryDeserializeFromMemoryStream(stream, options, cancellationToken, out T result))
             {
                 return result;
             }
 
-            using (var sequenceRental = SequencePool.Shared.Rent())
+            using (var sequenceRental = options.Pool.Rent())
             {
                 var sequence = sequenceRental.Value;
                 try
@@ -362,12 +369,14 @@ public static T Deserialize<T>(Stream stream, MessagePackSerializerOptions optio
         /// </remarks>
         public static async ValueTask<T> DeserializeAsync<T>(Stream stream, MessagePackSerializerOptions options = null, CancellationToken cancellationToken = default)
         {
+            options = options ?? DefaultOptions;
+
             if (TryDeserializeFromMemoryStream(stream, options, cancellationToken, out T result))
             {
                 return result;
             }
 
-            using (var sequenceRental = SequencePool.Shared.Rent())
+            using (var sequenceRental = options.Pool.Rent())
             {
                 var sequence = sequenceRental.Value;
                 try

src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializerOptions.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text.RegularExpressions;
+using Nerdbank.Streams;
 
 namespace MessagePack
 {
@@ -60,6 +61,7 @@ protected MessagePackSerializerOptions(MessagePackSerializerOptions copyFrom)
             this.OmitAssemblyVersion = copyFrom.OmitAssemblyVersion;
             this.AllowAssemblyVersionMismatch = copyFrom.AllowAssemblyVersionMismatch;
             this.Security = copyFrom.Security;
+            this.Pool = copyFrom.Pool;
         }
 
         /// <summary>
@@ -113,6 +115,11 @@ protected MessagePackSerializerOptions(MessagePackSerializerOptions copyFrom)
         /// </value>
         public MessagePackSecurity Security { get; private set; } = MessagePackSecurity.TrustedData;
 
+        /// <summary>
+        /// Gets a thread-safe pool of reusable <see cref="Sequence{T}"/> objects.
+        /// </summary>
+        public SequencePool Pool { get; private set; } = new SequencePool();
+
         /// <summary>
         /// Gets a type given a string representation of the type.
         /// </summary>
@@ -259,6 +266,28 @@ public MessagePackSerializerOptions WithSecurity(MessagePackSecurity security)
             return result;
         }
 
+        /// <summary>
+        /// Gets a copy of these options with the <see cref="Pool"/> property set to a new value.
+        /// </summary>
+        /// <param name="pool">The new value for the <see cref="Pool"/> property.</param>
+        /// <returns>The new instance.</returns>
+        public MessagePackSerializerOptions WithPool(SequencePool pool)
+        {
+            if (pool is null)
+            {
+                throw new ArgumentNullException(nameof(pool));
+            }
+
+            if (this.Pool == pool)
+            {
+                return this;
+            }
+
+            var result = this.Clone();
+            result.Pool = pool;
+            return result;
+        }
+
         /// <summary>
         /// Creates a clone of this instance with the same properties set.
         /// </summary>

src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackStreamReader.cs

@@ -21,7 +21,7 @@ public partial class MessagePackStreamReader : IDisposable
     {
         private readonly Stream stream;
         private readonly bool leaveOpen;
-        private SequencePool.Rental sequenceRental = SequencePool.Shared.Rent();
+        private SequencePool.Rental sequenceRental;
         private SequencePosition? endOfLastMessage;
 
         /// <summary>
@@ -39,9 +39,36 @@ public MessagePackStreamReader(Stream stream)
         /// <param name="stream">The stream to read from.</param>
         /// <param name="leaveOpen">If true, leaves the stream open after this <see cref="MessagePackStreamReader"/> is disposed; otherwise, false.</param>
         public MessagePackStreamReader(Stream stream, bool leaveOpen)
+            : this(stream, SequencePool.Shared, leaveOpen)
         {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="MessagePackStreamReader"/> class.
+        /// </summary>
+        /// <param name="stream">The stream to read from. This stream will be disposed of when this <see cref="MessagePackStreamReader"/> is disposed.</param>
+        /// <param name="pool">The pool to get result.</param>
+        public MessagePackStreamReader(Stream stream, SequencePool pool)
+            : this(stream, pool, leaveOpen: false)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="MessagePackStreamReader"/> class.
+        /// </summary>
+        /// <param name="stream">The stream to read from.</param>
+        /// <param name="pool">The pool to get result.</param>
+        /// <param name="leaveOpen">If true, leaves the stream open after this <see cref="MessagePackStreamReader"/> is disposed; otherwise, false.</param>
+        public MessagePackStreamReader(Stream stream, SequencePool pool, bool leaveOpen)
+        {
+            if (pool == null)
+            {
+                throw new ArgumentNullException(nameof(pool));
+            }
+
             this.stream = stream ?? throw new ArgumentNullException(nameof(stream));
             this.leaveOpen = leaveOpen;
+            this.sequenceRental = pool.Rent();
         }
 
         /// <summary>

src/MessagePack.UnityClient/Assets/Scripts/MessagePack/SequencePool.cs

@@ -11,16 +11,17 @@ namespace MessagePack
     /// <summary>
     /// A thread-safe, alloc-free reusable object pool.
     /// </summary>
-    internal class SequencePool
+#if MESSAGEPACK_INTERNAL
+    internal
+#else
+    public
+#endif
+    class SequencePool
     {
         /// <summary>
         /// A thread-safe pool of reusable <see cref="Sequence{T}"/> objects.
         /// </summary>
-        /// <remarks>
-        /// We use a <see cref="maxSize"/> that allows every processor to be involved in messagepack serialization concurrently,
-        /// plus one nested serialization per processor (since LZ4 and sometimes other nested serializations may exist).
-        /// </remarks>
-        internal static readonly SequencePool Shared = new SequencePool(Environment.ProcessorCount * 2);
+        internal static readonly SequencePool Shared = new SequencePool();
 
         /// <summary>
         /// The value to use for <see cref="Sequence{T}.MinimumSpanLength"/>.
@@ -41,18 +42,41 @@ internal class SequencePool
         /// <summary>
         /// The array pool which we share with all <see cref="Sequence{T}"/> objects created by this <see cref="SequencePool"/> instance.
         /// </summary>
+        private readonly ArrayPool<byte> arrayPool;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="SequencePool"/> class.
+        /// </summary>
+        /// <remarks>
+        /// We use a <see cref="maxSize"/> that allows every processor to be involved in messagepack serialization concurrently,
+        /// plus one nested serialization per processor (since LZ4 and sometimes other nested serializations may exist).
+        /// </remarks>
+        public SequencePool()
+            : this(Environment.ProcessorCount * 2, ArrayPool<byte>.Create(80 * 1024, 100))
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="SequencePool"/> class.
+        /// </summary>
+        /// <param name="maxSize">The maximum size to allow the pool to grow.</param>
         /// <devremarks>
         /// We allow 100 arrays to be shared (instead of the default 50) and reduce the max array length from the default 1MB to something more reasonable for our expected use.
         /// </devremarks>
-        private readonly ArrayPool<byte> arrayPool = ArrayPool<byte>.Create(80 * 1024, 100);
+        public SequencePool(int maxSize)
+            : this(maxSize, ArrayPool<byte>.Create(80 * 1024, 100))
+        {
+        }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="SequencePool"/> class.
         /// </summary>
         /// <param name="maxSize">The maximum size to allow the pool to grow.</param>
-        internal SequencePool(int maxSize)
+        /// <param name="arrayPool">Array pool that will be used.</param>
+        public SequencePool(int maxSize, ArrayPool<byte> arrayPool)
         {
             this.maxSize = maxSize;
+            this.arrayPool = arrayPool;
         }
 
         /// <summary>