Add option to avoid large buffer allocations

Allocating 1MB buffers contribute to the large object heap and should be avoidable for applications that it is a problem for.

6 files changed, 72 insertions, 5 deletions

diff --git a/src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializer.cs b/src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializer.cs
index 24b5373c..8c4a454c 100644
--- a/src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializer.cs
+++ b/src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializer.cs
@@ -18,7 +18,6 @@ namespace MessagePack
     [System.Diagnostics.CodeAnalysis.SuppressMessage("ApiDesign", "RS0026:Do not add multiple public overloads with optional parameters", Justification = "Each overload has sufficiently unique required parameters.")]
     public static partial class MessagePackSerializer
     {
-        private const int MaxHintSize = 1024 * 1024;
         private static MessagePackSerializerOptions defaultOptions;
 
         /// <summary>
@@ -349,7 +348,7 @@ namespace MessagePack
                     do
                     {
                         cancellationToken.ThrowIfCancellationRequested();
-                        Span<byte> span = sequence.GetSpan(stream.CanSeek ? (int)Math.Min(MaxHintSize, stream.Length - stream.Position) : 0);
+                        Span<byte> span = sequence.GetSpan(stream.CanSeek ? (int)Math.Min(options.SuggestedContiguousMemorySize, stream.Length - stream.Position) : 0);
                         bytesRead = stream.Read(span);
                         sequence.Advance(bytesRead);
                     }
@@ -397,7 +396,7 @@ namespace MessagePack
                     int bytesRead;
                     do
                     {
-                        Memory<byte> memory = sequence.GetMemory(stream.CanSeek ? (int)Math.Min(MaxHintSize, stream.Length - stream.Position) : 0);
+                        Memory<byte> memory = sequence.GetMemory(stream.CanSeek ? (int)Math.Min(options.SuggestedContiguousMemorySize, stream.Length - stream.Position) : 0);
                         bytesRead = await stream.ReadAsync(memory, cancellationToken).ConfigureAwait(false);
                         sequence.Advance(bytesRead);
                     }
diff --git a/src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializerOptions.cs b/src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializerOptions.cs
index 771aa25f..a9a9ec51 100644
--- a/src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializerOptions.cs
+++ b/src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializerOptions.cs
@@ -58,6 +58,7 @@ namespace MessagePack
             this.Resolver = copyFrom.Resolver;
             this.Compression = copyFrom.Compression;
             this.CompressionMinLength = copyFrom.CompressionMinLength;
+            this.SuggestedContiguousMemorySize = copyFrom.SuggestedContiguousMemorySize;
             this.OldSpec = copyFrom.OldSpec;
             this.OmitAssemblyVersion = copyFrom.OmitAssemblyVersion;
             this.AllowAssemblyVersionMismatch = copyFrom.AllowAssemblyVersionMismatch;
@@ -93,6 +94,16 @@ namespace MessagePack
         public int CompressionMinLength { get; private set; } = 64;
 
         /// <summary>
+        /// Gets the size of contiguous memory blocks in bytes that may be allocated for buffering purposes.
+        /// </summary>
+        /// <value>The default value is 1MB.</value>
+        /// <remarks>
+        /// Larger values may perform a bit faster, but may result in adding a runtime perf tax due to using the
+        /// <see href="https://docs.microsoft.com/en-us/dotnet/standard/garbage-collection/large-object-heap">Large Object Heap</see>.
+        /// </remarks>
+        public int SuggestedContiguousMemorySize { get; private set; } = 1024 * 1024;
+
+        /// <summary>
         /// Gets a value indicating whether to serialize with <see cref="MessagePackWriter.OldSpec"/> set to some value
         /// causing messagepack spec compliance to be explicitly set to the old or new format.
         /// </summary>
@@ -228,6 +239,28 @@ namespace MessagePack
         }
 
         /// <summary>
+        /// Gets a copy of these options with the <see cref="SuggestedContiguousMemorySize"/> property set to a new value.
+        /// </summary>
+        /// <param name="suggestedContiguousMemorySize">The new value for the <see cref="SuggestedContiguousMemorySize"/> property. Must be at least 256.</param>
+        /// <returns>The new instance; or the original if the value is unchanged.</returns>
+        public MessagePackSerializerOptions WithSuggestedContiguousMemorySize(int suggestedContiguousMemorySize)
+        {
+            if (this.SuggestedContiguousMemorySize == suggestedContiguousMemorySize)
+            {
+                return this;
+            }
+
+            if (suggestedContiguousMemorySize < 256)
+            {
+                throw new ArgumentOutOfRangeException(nameof(suggestedContiguousMemorySize), "This should be at least 256");
+            }
+
+            var result = this.Clone();
+            result.SuggestedContiguousMemorySize = suggestedContiguousMemorySize;
+            return result;
+        }
+
+        /// <summary>
         /// Gets a copy of these options with the <see cref="OldSpec"/> property set to a new value.
         /// </summary>
         /// <param name="oldSpec">The new value for the <see cref="OldSpec"/>.</param>
diff --git a/src/MessagePack.UnityClient/Assets/Scripts/Tests/ShareTests/MessagePackSerializerOptionsTests.cs b/src/MessagePack.UnityClient/Assets/Scripts/Tests/ShareTests/MessagePackSerializerOptionsTests.cs
index dfe988f8..0db5157c 100644
--- a/src/MessagePack.UnityClient/Assets/Scripts/Tests/ShareTests/MessagePackSerializerOptionsTests.cs
+++ b/src/MessagePack.UnityClient/Assets/Scripts/Tests/ShareTests/MessagePackSerializerOptionsTests.cs
@@ -14,7 +14,8 @@ public class MessagePackSerializerOptionsTests
         .WithOmitAssemblyVersion(true)
         .WithResolver(BuiltinResolver.Instance)
         .WithOldSpec(false)
-        .WithSecurity(MySecurityOptions.Instance);
+        .WithSecurity(MySecurityOptions.Instance)
+        .WithSuggestedContiguousMemorySize(64 * 1024);
 
     [Fact]
     public void AllowAssemblyVersionMismatch()
@@ -48,6 +49,16 @@ public class MessagePackSerializerOptionsTests
     }
 
     [Fact]
+    public void SuggestedContiguousMemorySize()
+    {
+        Assert.Equal(1024 * 1024, MessagePackSerializerOptions.Standard.SuggestedContiguousMemorySize);
+        Assert.Throws<ArgumentOutOfRangeException>(() => MessagePackSerializerOptions.Standard.WithSuggestedContiguousMemorySize(0));
+        Assert.Throws<ArgumentOutOfRangeException>(() => MessagePackSerializerOptions.Standard.WithSuggestedContiguousMemorySize(4));
+        MessagePackSerializerOptions options = MessagePackSerializerOptions.Standard.WithSuggestedContiguousMemorySize(512);
+        Assert.Equal(512, options.SuggestedContiguousMemorySize);
+    }
+
+    [Fact]
     public void OldSpec()
     {
         Assert.Null(MessagePackSerializerOptions.Standard.OldSpec);
@@ -74,6 +85,7 @@ public class MessagePackSerializerOptionsTests
         var mutated = NonDefaultOptions.WithOldSpec(true);
         Assert.True(mutated.OldSpec.Value);
         Assert.Equal(NonDefaultOptions.Compression, mutated.Compression);
+        Assert.Equal(NonDefaultOptions.SuggestedContiguousMemorySize, mutated.SuggestedContiguousMemorySize);
         Assert.Equal(NonDefaultOptions.AllowAssemblyVersionMismatch, mutated.AllowAssemblyVersionMismatch);
         Assert.Equal(NonDefaultOptions.OmitAssemblyVersion, mutated.OmitAssemblyVersion);
         Assert.Same(NonDefaultOptions.Resolver, mutated.Resolver);
@@ -93,11 +105,25 @@ public class MessagePackSerializerOptionsTests
     }
 
     [Fact]
+    public void WithSuggestedContiguousMemorySize_PreservesOtherProperties()
+    {
+        var mutated = NonDefaultOptions.WithSuggestedContiguousMemorySize(612);
+        Assert.Equal(612, mutated.SuggestedContiguousMemorySize);
+        Assert.Equal(NonDefaultOptions.Compression, mutated.Compression);
+        Assert.Equal(NonDefaultOptions.OldSpec, mutated.OldSpec);
+        Assert.Equal(NonDefaultOptions.AllowAssemblyVersionMismatch, mutated.AllowAssemblyVersionMismatch);
+        Assert.Equal(NonDefaultOptions.OmitAssemblyVersion, mutated.OmitAssemblyVersion);
+        Assert.Same(NonDefaultOptions.Resolver, mutated.Resolver);
+        Assert.Same(MySecurityOptions.Instance, mutated.Security);
+    }
+
+    [Fact]
     public void WithAllowAssemblyVersionMismatch_PreservesOtherProperties()
     {
         var mutated = NonDefaultOptions.WithAllowAssemblyVersionMismatch(false);
         Assert.False(mutated.AllowAssemblyVersionMismatch);
         Assert.Equal(NonDefaultOptions.Compression, mutated.Compression);
+        Assert.Equal(NonDefaultOptions.SuggestedContiguousMemorySize, mutated.SuggestedContiguousMemorySize);
         Assert.Equal(NonDefaultOptions.OldSpec, mutated.OldSpec);
         Assert.Equal(NonDefaultOptions.OmitAssemblyVersion, mutated.OmitAssemblyVersion);
         Assert.Same(NonDefaultOptions.Resolver, mutated.Resolver);
@@ -110,6 +136,7 @@ public class MessagePackSerializerOptionsTests
         var mutated = NonDefaultOptions.WithOmitAssemblyVersion(false);
         Assert.False(mutated.OmitAssemblyVersion);
         Assert.Equal(NonDefaultOptions.Compression, mutated.Compression);
+        Assert.Equal(NonDefaultOptions.SuggestedContiguousMemorySize, mutated.SuggestedContiguousMemorySize);
         Assert.Equal(NonDefaultOptions.OldSpec, mutated.OldSpec);
         Assert.Equal(NonDefaultOptions.AllowAssemblyVersionMismatch, mutated.AllowAssemblyVersionMismatch);
         Assert.Same(NonDefaultOptions.Resolver, mutated.Resolver);
@@ -122,6 +149,7 @@ public class MessagePackSerializerOptionsTests
         var mutated = NonDefaultOptions.WithResolver(ContractlessStandardResolver.Instance);
         Assert.Same(ContractlessStandardResolver.Instance, mutated.Resolver);
         Assert.Equal(NonDefaultOptions.Compression, mutated.Compression);
+        Assert.Equal(NonDefaultOptions.SuggestedContiguousMemorySize, mutated.SuggestedContiguousMemorySize);
         Assert.Equal(NonDefaultOptions.OldSpec, mutated.OldSpec);
         Assert.Equal(NonDefaultOptions.AllowAssemblyVersionMismatch, mutated.AllowAssemblyVersionMismatch);
         Assert.Equal(NonDefaultOptions.OmitAssemblyVersion, mutated.OmitAssemblyVersion);
@@ -135,6 +163,7 @@ public class MessagePackSerializerOptionsTests
         Assert.Same(MessagePackSecurity.TrustedData, mutated.Security);
         Assert.Same(NonDefaultOptions.Resolver, mutated.Resolver);
         Assert.Equal(NonDefaultOptions.Compression, mutated.Compression);
+        Assert.Equal(NonDefaultOptions.SuggestedContiguousMemorySize, mutated.SuggestedContiguousMemorySize);
         Assert.Equal(NonDefaultOptions.OldSpec, mutated.OldSpec);
         Assert.Equal(NonDefaultOptions.AllowAssemblyVersionMismatch, mutated.AllowAssemblyVersionMismatch);
         Assert.Equal(NonDefaultOptions.OmitAssemblyVersion, mutated.OmitAssemblyVersion);
diff --git a/src/MessagePack/net6.0/PublicAPI.Unshipped.txt b/src/MessagePack/net6.0/PublicAPI.Unshipped.txt
index 78006a92..89697310 100644
--- a/src/MessagePack/net6.0/PublicAPI.Unshipped.txt
+++ b/src/MessagePack/net6.0/PublicAPI.Unshipped.txt
@@ -9,6 +9,8 @@ MessagePack.Formatters.TimeOnlyFormatter
 MessagePack.Formatters.TimeOnlyFormatter.Deserialize(ref MessagePack.MessagePackReader reader, MessagePack.MessagePackSerializerOptions options) -> System.TimeOnly
 MessagePack.Formatters.TimeOnlyFormatter.Serialize(ref MessagePack.MessagePackWriter writer, System.TimeOnly value, MessagePack.MessagePackSerializerOptions options) -> void
 MessagePack.MessagePackSerializerOptions.CompressionMinLength.get -> int
+MessagePack.MessagePackSerializerOptions.SuggestedContiguousMemorySize.get -> int
 MessagePack.MessagePackSerializerOptions.WithCompressionMinLength(int compressionMinLength) -> MessagePack.MessagePackSerializerOptions
+MessagePack.MessagePackSerializerOptions.WithSuggestedContiguousMemorySize(int suggestedContiguousMemorySize) -> MessagePack.MessagePackSerializerOptions
 static readonly MessagePack.Formatters.DateOnlyFormatter.Instance -> MessagePack.Formatters.DateOnlyFormatter
 static readonly MessagePack.Formatters.TimeOnlyFormatter.Instance -> MessagePack.Formatters.TimeOnlyFormatter
diff --git a/src/MessagePack/netcoreapp3.1/PublicAPI.Unshipped.txt b/src/MessagePack/netcoreapp3.1/PublicAPI.Unshipped.txt
index 9ba64088..ba449cac 100644
--- a/src/MessagePack/netcoreapp3.1/PublicAPI.Unshipped.txt
+++ b/src/MessagePack/netcoreapp3.1/PublicAPI.Unshipped.txt
@@ -3,4 +3,6 @@ MessagePack.Formatters.StringInterningFormatter.Deserialize(ref MessagePack.Mess
 MessagePack.Formatters.StringInterningFormatter.Serialize(ref MessagePack.MessagePackWriter writer, string value, MessagePack.MessagePackSerializerOptions options) -> void
 MessagePack.Formatters.StringInterningFormatter.StringInterningFormatter() -> void
 MessagePack.MessagePackSerializerOptions.CompressionMinLength.get -> int
+MessagePack.MessagePackSerializerOptions.SuggestedContiguousMemorySize.get -> int
 MessagePack.MessagePackSerializerOptions.WithCompressionMinLength(int compressionMinLength) -> MessagePack.MessagePackSerializerOptions
+MessagePack.MessagePackSerializerOptions.WithSuggestedContiguousMemorySize(int suggestedContiguousMemorySize) -> MessagePack.MessagePackSerializerOptions
diff --git a/src/MessagePack/netstandard2.0/PublicAPI.Unshipped.txt b/src/MessagePack/netstandard2.0/PublicAPI.Unshipped.txt
index 49e84ad1..2cdd3d32 100644
--- a/src/MessagePack/netstandard2.0/PublicAPI.Unshipped.txt
+++ b/src/MessagePack/netstandard2.0/PublicAPI.Unshipped.txt
@@ -3,4 +3,6 @@ MessagePack.Formatters.StringInterningFormatter.Deserialize(ref MessagePack.Mess
 MessagePack.Formatters.StringInterningFormatter.Serialize(ref MessagePack.MessagePackWriter writer, string value, MessagePack.MessagePackSerializerOptions options) -> void
 MessagePack.Formatters.StringInterningFormatter.StringInterningFormatter() -> void
 MessagePack.MessagePackSerializerOptions.CompressionMinLength.get -> int
-MessagePack.MessagePackSerializerOptions.WithCompressionMinLength(int compressionMinLength) -> MessagePack.MessagePackSerializerOptions
\ No newline at end of file
+MessagePack.MessagePackSerializerOptions.SuggestedContiguousMemorySize.get -> int
+MessagePack.MessagePackSerializerOptions.WithCompressionMinLength(int compressionMinLength) -> MessagePack.MessagePackSerializerOptions
+MessagePack.MessagePackSerializerOptions.WithSuggestedContiguousMemorySize(int suggestedContiguousMemorySize) -> MessagePack.MessagePackSerializerOptions
\ No newline at end of file