JSON Serializer JIT Compiler for .NET Core 3.0

Emit CIL/MSIL code at runtime for JSON serialization, utilizing the System.Test.Json namespace provided since .NET Core 3.0.

Installation

dotnet add package MartinCl2.Text.Json.Serialization

https://www.nuget.org/packages/MartinCl2.Text.Json.Serialization

Usage

public static class Example<T>
{
    private static JsonJitSerializer<T> serializer = JsonJitSerializer<T>.Compile(new JsonSerializerOptions()
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase
    });

    public static string SerializeToString<T>(T obj)
    {
        return serializer.Serialize(obj);
    }

    public static async Task SerializeToStreamAsync(Stream stream, T obj)
    {
        await serializer.SerializeAsync(stream, obj);
    }
}

High level design

The JIT compiler generates a dynamic class inside a dynamic assembly when JsonJitSerializer.Compile<T> is called. This dynamic class is a value type and implements ISerializerImplementation<T>. That interface defines two methods: Serialize and SerializeChunk. Serialize serializes an object in one shot. SerializeChunk is re-enterable which can be called with the same parameter until it returns false, so it can be used for asynchronized serialization. Both methods will be implemented by generated IL codes. Other than that, the dynamic class contains static fields used as constants, such as converters, names and serialization options.

The dynamic class contains a list of Object fields used as serialization stack. The type Object is actually used as void* (Note: value type will be boxed). However there is no runtime casting involved. Therefore the runtime memory consumption is linear to the depth of the payload object. One exception is IDictionary<string, T>, because a local variable is needed to store a KeyValuePair<string, T> for every dictionary. Since the dynamic class is a value type, the serialization stack will be allocated on the stack at runtime.

Supported feature

• Just-in-time compiled JSON serialization with System.Text.Json.JsonSerializerOptions.
• Custom JsonConverter attribute.
• Custom JsonPropertyName attribute.
• Both synchronized and asynchronized (re-enterable) serialization.
• struct serialization.
• Correctly deal with ref getter.
• IEnumerable<T> and IDictionary<string, T> serialization.
• Value type enumerator optimization.
• O(depth of structure + number of dictionary) runtime memory consumption.

Roadmap (randomly ordered)

• Support element converter for IEnumerable<T> and IDictionary<string, T>. (Not supported in the official JsonSerializer yet)
• Optionally skip null. (Looks like the official implementation always keeps null.)
• Avoid boxing for struct?
• Pointer type serialization?
• Pointer getter?
• Unit test for Enum.

How to: Run unit tests and generate code coverage

dotnet test ./tests/JsonJitSerializerTests.csproj /p:CollectCoverage=true /p:CoverletOutputFormat="lcov" /p:CoverletOutput=../coverage/

Benchmark

Framework: my fork of dotnet/performance/micro (forked from a fork of dotnet/performance)

Command: dotnet run -c Release -f netcoreapp3.0 --filter *Json_ToStream*

Json_ToStream_LoginViewModel_

BenchmarkDotNet=v0.11.3.1003-nightly, OS=Windows 10.0.18362
Intel Core i7-9700K CPU 3.60GHz, 1 CPU, 8 logical and 8 physical cores
.NET Core SDK=3.0.100-preview9-014004
  [Host]     : .NET Core 3.0.0-preview9-19423-09 (CoreCLR 4.700.19.42102, CoreFX 4.700.19.42104), 64bit RyuJIT
  Job-RUHLRH : .NET Core 3.0.0-preview9-19423-09 (CoreCLR 4.700.19.42102, CoreFX 4.700.19.42104), 64bit RyuJIT

IterationTime=250.0000 ms  MaxIterationCount=20  MinIterationCount=15  
WarmupCount=1  

Json_ToStream_Location_

BenchmarkDotNet=v0.11.3.1003-nightly, OS=Windows 10.0.18362
Intel Core i7-9700K CPU 3.60GHz, 1 CPU, 8 logical and 8 physical cores
.NET Core SDK=3.0.100-preview9-014004
  [Host]     : .NET Core 3.0.0-preview9-19423-09 (CoreCLR 4.700.19.42102, CoreFX 4.700.19.42104), 64bit RyuJIT
  Job-RUHLRH : .NET Core 3.0.0-preview9-19423-09 (CoreCLR 4.700.19.42102, CoreFX 4.700.19.42104), 64bit RyuJIT

IterationTime=250.0000 ms  MaxIterationCount=20  MinIterationCount=15  
WarmupCount=1  

Json_ToStream_IndexViewModel_

BenchmarkDotNet=v0.11.3.1003-nightly, OS=Windows 10.0.18362
Intel Core i7-9700K CPU 3.60GHz, 1 CPU, 8 logical and 8 physical cores
.NET Core SDK=3.0.100-preview9-014004
  [Host]     : .NET Core 3.0.0-preview9-19423-09 (CoreCLR 4.700.19.42102, CoreFX 4.700.19.42104), 64bit RyuJIT
  Job-RUHLRH : .NET Core 3.0.0-preview9-19423-09 (CoreCLR 4.700.19.42102, CoreFX 4.700.19.42104), 64bit RyuJIT

IterationTime=250.0000 ms  MaxIterationCount=20  MinIterationCount=15  
WarmupCount=1  

Json_ToStream_MyEventsListerViewModel_

BenchmarkDotNet=v0.11.3.1003-nightly, OS=Windows 10.0.18362
Intel Core i7-9700K CPU 3.60GHz, 1 CPU, 8 logical and 8 physical cores
.NET Core SDK=3.0.100-preview9-014004
  [Host]     : .NET Core 3.0.0-preview9-19423-09 (CoreCLR 4.700.19.42102, CoreFX 4.700.19.42104), 64bit RyuJIT
  Job-RUHLRH : .NET Core 3.0.0-preview9-19423-09 (CoreCLR 4.700.19.42102, CoreFX 4.700.19.42104), 64bit RyuJIT

IterationTime=250.0000 ms  MaxIterationCount=20  MinIterationCount=15  
WarmupCount=1  

Json_ToStream_CollectionsOfPrimitives_

BenchmarkDotNet=v0.11.3.1003-nightly, OS=Windows 10.0.18362
Intel Core i7-9700K CPU 3.60GHz, 1 CPU, 8 logical and 8 physical cores
.NET Core SDK=3.0.100-preview9-014004
  [Host]     : .NET Core 3.0.0-preview9-19423-09 (CoreCLR 4.700.19.42102, CoreFX 4.700.19.42104), 64bit RyuJIT
  Job-RUHLRH : .NET Core 3.0.0-preview9-19423-09 (CoreCLR 4.700.19.42102, CoreFX 4.700.19.42104), 64bit RyuJIT

IterationTime=250.0000 ms  MaxIterationCount=20  MinIterationCount=15  
WarmupCount=1