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Merged
Tarmil merged 2 commits into from
Jun 9, 2025
Merged

Specialize tuple converter up to size 4 #201

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8b95e44
feat: specialize tuple serializer up to 4
Tarmil Jun 9, 2025
1631bc2
benchmark: test tuple serialized vs generic
Tarmil Jun 9, 2025
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27 changes: 26 additions & 1 deletion benchmarks/FSharp.SystemTextJson.Benchmarks/Program.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -94,6 +94,30 @@ type ReflectionComparison() =
for i in 0 .. this.Iterations do
TypeCache.isRecord typeof<TestRecord> |> ignore

type TupleComparison() =

let fsharpOptions = JsonFSharpOptions.Default()
let specializedOptions = fsharpOptions.ToJsonSerializerOptions()
let genericOptions =
let o = JsonSerializerOptions()
o.Converters.Add(JsonTupleConverter(fsharpOptions, true))
o

[<Benchmark>]
member this.StructGeneric() =
System.Text.Json.JsonSerializer.Deserialize<struct (int * bool)>("[1,true]", genericOptions)

[<Benchmark>]
member this.StructSpecialized() =
System.Text.Json.JsonSerializer.Deserialize<struct (int * bool)>("[1,true]", specializedOptions)

[<Benchmark>]
member this.RefGeneric() =
System.Text.Json.JsonSerializer.Deserialize<int * bool>("[1,true]", genericOptions)

[<Benchmark>]
member this.RefSpecialized() =
System.Text.Json.JsonSerializer.Deserialize<int * bool>("[1,true]", specializedOptions)

let config =
ManualConfig
Expand All @@ -106,7 +130,8 @@ let defaultSwitch () =
BenchmarkSwitcher(
[| typeof<Records>
typeof<Classes>
typeof<ReflectionComparison> |]
typeof<ReflectionComparison>
typeof<TupleComparison> |]
)


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193 changes: 168 additions & 25 deletions src/FSharp.SystemTextJson/Tuple.fs
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Original file line number Diff line number Diff line change
@@ -1,65 +1,208 @@
namespace System.Text.Json.Serialization

open System
open System.Runtime.InteropServices
open System.Text.Json
open System.Text.Json.Serialization.Helpers
open FSharp.Reflection

type internal TupleProperty = { Type: Type; NeedsNullChecking: bool }
type internal TupleProperty<'T> =
{ Type: Type
NeedsNullChecking: bool }

type JsonTupleConverter<'T> internal (fsOptions) =
static member MakeUntyped fsOptions t =
let needsNullChecking =
let tIsNullable = isNullableFieldType fsOptions t
not tIsNullable && not t.IsValueType
{ Type = t; NeedsNullChecking = needsNullChecking }

static member MakeTyped fsOptions =
TupleProperty<'T>.MakeUntyped fsOptions typeof<'T>

member this.CheckNull(x: 'T) =
if this.NeedsNullChecking && isNull (box x) then
failf "Unexpected null inside tuple-array. Expected type %s, but got null." this.Type.Name

member this.ReadAndDeserializeTyped(reader: Utf8JsonReader byref, options: JsonSerializerOptions) =
reader.Read() |> ignore
let res = JsonSerializer.Deserialize<'T>(&reader, options)
this.CheckNull(res)
res

[<AbstractClass>]
type BaseJsonTupleConverter<'T>() =
inherit JsonConverter<'T>()

abstract ReadCore: Utf8JsonReader byref * JsonSerializerOptions -> 'T
abstract WriteCore: Utf8JsonWriter * 'T * JsonSerializerOptions -> unit

override this.Read(reader, typeToConvert, options) =
expectAlreadyRead JsonTokenType.StartArray "array" &reader typeToConvert
let res = this.ReadCore(&reader, options)
readExpecting JsonTokenType.EndArray "end of array" &reader typeToConvert
res

override this.Write(writer, value, options) =
writer.WriteStartArray()
this.WriteCore(writer, value, options)
writer.WriteEndArray()

override _.HandleNull = true

type JsonTupleConverter<'T>(fsOptions: JsonFSharpOptions) =
inherit BaseJsonTupleConverter<'T>()

let ty = typeof<'T>
let fieldProps =
FSharpType.GetTupleElements(ty)
|> Array.map (fun t ->
let tIsNullable = isNullableFieldType fsOptions t
let needsNullChecking = not tIsNullable && not t.IsValueType
{ Type = t; NeedsNullChecking = needsNullChecking }
)
|> Array.map (TupleProperty<obj>.MakeUntyped fsOptions.Record)
let ctor = FSharpValue.PreComputeTupleConstructor(ty)
let reader = FSharpValue.PreComputeTupleReader(ty)

override _.Read(reader, typeToConvert, options) =
expectAlreadyRead JsonTokenType.StartArray "array" &reader typeToConvert
override _.ReadCore(reader, options) =
let elts = Array.zeroCreate fieldProps.Length
for i in 0 .. fieldProps.Length - 1 do
let p = fieldProps[i]
reader.Read() |> ignore
let value = JsonSerializer.Deserialize(&reader, p.Type, options)
if p.NeedsNullChecking && isNull (box value) then
failf "Unexpected null inside tuple-array. Expected type %s, but got null." p.Type.Name
p.CheckNull value
elts[i] <- value
readExpecting JsonTokenType.EndArray "end of array" &reader typeToConvert
ctor elts :?> 'T

override _.Write(writer, value, options) =
writer.WriteStartArray()
override _.WriteCore(writer, value, options) =
let values = reader value
for i in 0 .. fieldProps.Length - 1 do
JsonSerializer.Serialize(writer, values[i], fieldProps[i].Type, options)
writer.WriteEndArray()

override _.HandleNull = true
type JsonTupleConverter<'T1, 'T2>(fsOptions: JsonFSharpOptions) =
inherit BaseJsonTupleConverter<'T1 * 'T2>()

let p1 = TupleProperty<'T1>.MakeTyped fsOptions.Record
let p2 = TupleProperty<'T2>.MakeTyped fsOptions.Record

override this.ReadCore(reader, options) =
(p1.ReadAndDeserializeTyped(&reader, options), p2.ReadAndDeserializeTyped(&reader, options))

override this.WriteCore(writer, (x1, x2), options) =
JsonSerializer.Serialize(writer, x1, options)
JsonSerializer.Serialize(writer, x2, options)

type JsonStructTupleConverter<'T1, 'T2>(fsOptions: JsonFSharpOptions) =
inherit BaseJsonTupleConverter<struct ('T1 * 'T2)>()

let p1 = TupleProperty<'T1>.MakeTyped fsOptions.Record
let p2 = TupleProperty<'T2>.MakeTyped fsOptions.Record

override this.ReadCore(reader, options) =
(p1.ReadAndDeserializeTyped(&reader, options), p2.ReadAndDeserializeTyped(&reader, options))

override this.WriteCore(writer, (x1, x2), options) =
JsonSerializer.Serialize(writer, x1, options)
JsonSerializer.Serialize(writer, x2, options)

type JsonTupleConverter<'T1, 'T2, 'T3>(fsOptions: JsonFSharpOptions) =
inherit BaseJsonTupleConverter<'T1 * 'T2 * 'T3>()

let p1 = TupleProperty<'T1>.MakeTyped fsOptions.Record
let p2 = TupleProperty<'T2>.MakeTyped fsOptions.Record
let p3 = TupleProperty<'T3>.MakeTyped fsOptions.Record

override this.ReadCore(reader, options) =
(p1.ReadAndDeserializeTyped(&reader, options),
p2.ReadAndDeserializeTyped(&reader, options),
p3.ReadAndDeserializeTyped(&reader, options))

override this.WriteCore(writer, (x1, x2, x3), options) =
JsonSerializer.Serialize(writer, x1, options)
JsonSerializer.Serialize(writer, x2, options)
JsonSerializer.Serialize(writer, x3, options)

type JsonStructTupleConverter<'T1, 'T2, 'T3>(fsOptions: JsonFSharpOptions) =
inherit BaseJsonTupleConverter<struct ('T1 * 'T2 * 'T3)>()

let p1 = TupleProperty<'T1>.MakeTyped fsOptions.Record
let p2 = TupleProperty<'T2>.MakeTyped fsOptions.Record
let p3 = TupleProperty<'T3>.MakeTyped fsOptions.Record

override this.ReadCore(reader, options) =
(p1.ReadAndDeserializeTyped(&reader, options),
p2.ReadAndDeserializeTyped(&reader, options),
p3.ReadAndDeserializeTyped(&reader, options))

override this.WriteCore(writer, (x1, x2, x3), options) =
JsonSerializer.Serialize(writer, x1, options)
JsonSerializer.Serialize(writer, x2, options)
JsonSerializer.Serialize(writer, x3, options)

type JsonTupleConverter<'T1, 'T2, 'T3, 'T4>(fsOptions: JsonFSharpOptions) =
inherit BaseJsonTupleConverter<'T1 * 'T2 * 'T3 * 'T4>()

let p1 = TupleProperty<'T1>.MakeTyped fsOptions.Record
let p2 = TupleProperty<'T2>.MakeTyped fsOptions.Record
let p3 = TupleProperty<'T3>.MakeTyped fsOptions.Record
let p4 = TupleProperty<'T4>.MakeTyped fsOptions.Record

override this.ReadCore(reader, options) =
(p1.ReadAndDeserializeTyped(&reader, options),
p2.ReadAndDeserializeTyped(&reader, options),
p3.ReadAndDeserializeTyped(&reader, options),
p4.ReadAndDeserializeTyped(&reader, options))

override this.WriteCore(writer, (x1, x2, x3, x4), options) =
JsonSerializer.Serialize(writer, x1, options)
JsonSerializer.Serialize(writer, x2, options)
JsonSerializer.Serialize(writer, x3, options)
JsonSerializer.Serialize(writer, x4, options)

type JsonStructTupleConverter<'T1, 'T2, 'T3, 'T4>(fsOptions: JsonFSharpOptions) =
inherit BaseJsonTupleConverter<struct ('T1 * 'T2 * 'T3 * 'T4)>()

let p1 = TupleProperty<'T1>.MakeTyped fsOptions.Record
let p2 = TupleProperty<'T2>.MakeTyped fsOptions.Record
let p3 = TupleProperty<'T3>.MakeTyped fsOptions.Record
let p4 = TupleProperty<'T4>.MakeTyped fsOptions.Record

override this.ReadCore(reader, options) =
(p1.ReadAndDeserializeTyped(&reader, options),
p2.ReadAndDeserializeTyped(&reader, options),
p3.ReadAndDeserializeTyped(&reader, options),
p4.ReadAndDeserializeTyped(&reader, options))

override this.WriteCore(writer, (x1, x2, x3, x4), options) =
JsonSerializer.Serialize(writer, x1, options)
JsonSerializer.Serialize(writer, x2, options)
JsonSerializer.Serialize(writer, x3, options)
JsonSerializer.Serialize(writer, x4, options)

new(fsOptions: JsonFSharpOptions) = JsonTupleConverter<'T>(fsOptions.Record)

type JsonTupleConverter(fsOptions) =
type JsonTupleConverter(fsOptions, [<Optional>] forceGeneric) =
inherit JsonConverterFactory()

static member internal CanConvert(typeToConvert: Type) =
TypeCache.isTuple typeToConvert

static member internal CreateConverter(typeToConvert: Type, fsOptions: JsonFSharpOptions) =
typedefof<JsonTupleConverter<_>>
.MakeGenericType([| typeToConvert |])
.GetConstructor([| typeof<JsonFSharpOptions> |])
.Invoke([| fsOptions |])
:?> JsonConverter
static member internal CreateConverter
(typeToConvert: Type, fsOptions: JsonFSharpOptions, [<Optional>] forceGeneric: bool)
=
let converterType =
if forceGeneric then
typedefof<JsonTupleConverter<_>>.MakeGenericType(typeToConvert)
else
let targs = typeToConvert.GetGenericArguments()
let isStruct =
typeToConvert.GetGenericTypeDefinition().Name.StartsWith("ValueTuple")
match targs.Length, isStruct with
| 2, false -> typedefof<JsonTupleConverter<_, _>>.MakeGenericType(targs)
| 3, false -> typedefof<JsonTupleConverter<_, _, _>>.MakeGenericType(targs)
| 4, false -> typedefof<JsonTupleConverter<_, _, _, _>>.MakeGenericType(targs)
| 2, true -> typedefof<JsonStructTupleConverter<_, _>>.MakeGenericType(targs)
| 3, true -> typedefof<JsonStructTupleConverter<_, _, _>>.MakeGenericType(targs)
| 4, true -> typedefof<JsonStructTupleConverter<_, _, _, _>>.MakeGenericType(targs)
| _ -> typedefof<JsonTupleConverter<_>>.MakeGenericType(typeToConvert)
converterType.GetConstructor([| typeof<JsonFSharpOptions> |]).Invoke([| fsOptions |]) :?> JsonConverter

override _.CanConvert(typeToConvert) =
JsonTupleConverter.CanConvert(typeToConvert)

override _.CreateConverter(typeToConvert, _options) =
JsonTupleConverter.CreateConverter(typeToConvert, fsOptions)
JsonTupleConverter.CreateConverter(typeToConvert, fsOptions, forceGeneric)