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feat: abstract away Wazero's api.ValueType and api.EncodeXX/api.DecodeXX
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@mhmd-azeez
mhmd-azeez committed Dec 5, 2023
1 parent 055ce19 commit 17b0914
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Showing 3 changed files with 112 additions and 51 deletions.
8 changes: 4 additions & 4 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -165,8 +165,8 @@ kvRead := extism.NewHostFunctionWithStack(

stack[0], err = p.WriteBytes(value)
},
[]api.ValueType{extism.PTR},
[]api.ValueType{extism.PTR},
[]ValueType{ValueTypePTR},
[]ValueType{ValueTypePTR},
)

kvWrite := extism.NewHostFunctionWithStack(
Expand All @@ -184,8 +184,8 @@ kvWrite := extism.NewHostFunctionWithStack(

kvStore[key] = value
},
[]api.ValueType{extism.PTR, extism.PTR},
[]api.ValueType{},
[]ValueType{ValueTypePTR, ValueTypePTR},
[]ValueType{},
)
```

Expand Down
23 changes: 11 additions & 12 deletions extism_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,6 @@ import (

"github.com/stretchr/testify/assert"
"github.com/tetratelabs/wazero"
"github.com/tetratelabs/wazero/api"
"github.com/tetratelabs/wazero/sys"
)

Expand Down Expand Up @@ -227,13 +226,13 @@ func TestHost_simple(t *testing.T) {
mult := NewHostFunctionWithStack(
"mult",
func(ctx context.Context, plugin *CurrentPlugin, stack []uint64) {
a := api.DecodeI32(stack[0])
b := api.DecodeI32(stack[1])
a := DecodeI32(stack[0])
b := DecodeI32(stack[1])

stack[0] = api.EncodeI32(a * b)
stack[0] = EncodeI32(a * b)
},
[]api.ValueType{PTR, PTR},
[]api.ValueType{PTR},
[]ValueType{ValueTypePTR, ValueTypePTR},
[]ValueType{ValueTypePTR},
)

if plugin, ok := plugin(t, manifest, mult); ok {
Expand Down Expand Up @@ -274,8 +273,8 @@ func TestHost_memory(t *testing.T) {

stack[0] = offset
},
[]api.ValueType{PTR},
[]api.ValueType{PTR},
[]ValueType{ValueTypePTR},
[]ValueType{ValueTypePTR},
)

mult.SetNamespace("host")
Expand Down Expand Up @@ -323,8 +322,8 @@ func TestHost_multiple(t *testing.T) {

stack[0] = offset
},
[]api.ValueType{PTR},
[]api.ValueType{PTR},
[]ValueType{ValueTypePTR},
[]ValueType{ValueTypePTR},
)

purple_message := NewHostFunctionWithStack(
Expand All @@ -348,8 +347,8 @@ func TestHost_multiple(t *testing.T) {

stack[0] = offset
},
[]api.ValueType{PTR},
[]api.ValueType{PTR},
[]ValueType{ValueTypePTR},
[]ValueType{ValueTypePTR},
)

hostFunctions := []HostFunction{
Expand Down
132 changes: 97 additions & 35 deletions host.go
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Original file line number Diff line number Diff line change
Expand Up @@ -15,11 +15,20 @@ import (
"github.com/tetratelabs/wazero/api"
)

type ValType = api.ValueType

const I32 = api.ValueTypeI32
const I64 = api.ValueTypeI64
const PTR = I64
type ValueType = byte

const (
// ValueTypeI32 is a 32-bit integer.
ValueTypeI32 = api.ValueTypeI32
// ValueTypeI64 is a 64-bit integer.
ValueTypeI64 = api.ValueTypeI64
// ValueTypeF32 is a 32-bit floating point number.
ValueTypeF32 = api.ValueTypeF32
// ValueTypeF64 is a 64-bit floating point number.
ValueTypeF64 = api.ValueTypeF64
// ValueTypePTR represents a pointer to an Extism memory block. Alias for ValueTypeI64
ValueTypePTR = ValueTypeI64
)

// HostFunctionStackCallback is a Function implemented in Go instead of a wasm binary.
// The plugin parameter is the calling plugin, used to access memory or
Expand All @@ -33,18 +42,18 @@ const PTR = I64
// Here's a typical way to read three parameters and write back one.
//
// // read parameters in index order
// argv, argvBuf := api.DecodeU32(inputs[0]), api.DecodeU32(inputs[1])
// argv, argvBuf := DecodeU32(inputs[0]), DecodeU32(inputs[1])
//
// // write results back to the stack in index order
// stack[0] = api.EncodeU32(ErrnoSuccess)
// stack[0] = EncodeU32(ErrnoSuccess)
//
// This function can be non-deterministic or cause side effects. It also
// has special properties not defined in the WebAssembly Core specification.
// Notably, this uses the caller's memory (via Module.Memory). See
// https://www.w3.org/TR/wasm-core-1/#host-functions%E2%91%A0
//
// To safely decode/encode values from/to the uint64 inputs/ouputs, users are encouraged to use
// Wazero's api.EncodeXXX or api.DecodeXXX functions.
// Extism's EncodeXXX or DecodeXXX functions.
type HostFunctionStackCallback func(ctx context.Context, p *CurrentPlugin, stack []uint64)

// HostFunction represents a custom function defined by the host.
Expand All @@ -67,19 +76,19 @@ func (f *HostFunction) SetNamespace(namespace string) {
// mult := NewHostFunctionWithStack(
// "mult",
// func(ctx context.Context, plugin *CurrentPlugin, stack []uint64) {
// a := api.DecodeI32(stack[0])
// b := api.DecodeI32(stack[1])
// a := DecodeI32(stack[0])
// b := DecodeI32(stack[1])
//
// stack[0] = api.EncodeI32(a * b)
// stack[0] = EncodeI32(a * b)
// },
// []api.ValueType{api.ValueTypeI64, api.ValueTypeI64},
// api.ValueTypeI64
// []ValueType{ValueTypeI64, ValueTypeI64},
// ValueTypeI64
// )
func NewHostFunctionWithStack(
name string,
callback HostFunctionStackCallback,
params []api.ValueType,
returnTypes []api.ValueType) HostFunction {
params []ValueType,
returnTypes []ValueType) HostFunction {

return HostFunction{
stackCallback: callback,
Expand Down Expand Up @@ -225,7 +234,7 @@ func defineCustomHostFunctions(builder wazero.HostModuleBuilder, funcs []HostFun
func buildEnvModule(ctx context.Context, rt wazero.Runtime, extism api.Module) (api.Module, error) {
builder := rt.NewHostModuleBuilder("extism:host/env")

wrap := func(name string, params []ValType, results []ValType) {
wrap := func(name string, params []ValueType, results []ValueType) {
f := extism.ExportedFunction(name)
builder.
NewFunctionBuilder().
Expand All @@ -238,33 +247,33 @@ func buildEnvModule(ctx context.Context, rt wazero.Runtime, extism api.Module) (
Export(name)
}

wrap("alloc", []ValType{I64}, []ValType{I64})
wrap("free", []ValType{I64}, []ValType{})
wrap("load_u8", []ValType{I64}, []ValType{I32})
wrap("input_load_u8", []ValType{I64}, []ValType{I32})
wrap("store_u64", []ValType{I64, I64}, []ValType{})
wrap("store_u8", []ValType{I64, I32}, []ValType{})
wrap("input_set", []ValType{I64, I64}, []ValType{})
wrap("output_set", []ValType{I64, I64}, []ValType{})
wrap("input_length", []ValType{}, []ValType{I64})
wrap("output_length", []ValType{}, []ValType{I64})
wrap("output_offset", []ValType{}, []ValType{I64})
wrap("length", []ValType{I64}, []ValType{I64})
wrap("reset", []ValType{}, []ValType{})
wrap("error_set", []ValType{I64}, []ValType{})
wrap("error_get", []ValType{}, []ValType{I64})
wrap("memory_bytes", []ValType{}, []ValType{I64})
wrap("alloc", []ValueType{ValueTypeI64}, []ValueType{ValueTypeI64})
wrap("free", []ValueType{ValueTypeI64}, []ValueType{})
wrap("load_u8", []ValueType{ValueTypeI64}, []ValueType{ValueTypeI32})
wrap("input_load_u8", []ValueType{ValueTypeI64}, []ValueType{ValueTypeI32})
wrap("store_u64", []ValueType{ValueTypeI64, ValueTypeI64}, []ValueType{})
wrap("store_u8", []ValueType{ValueTypeI64, ValueTypeI32}, []ValueType{})
wrap("input_set", []ValueType{ValueTypeI64, ValueTypeI64}, []ValueType{})
wrap("output_set", []ValueType{ValueTypeI64, ValueTypeI64}, []ValueType{})
wrap("input_length", []ValueType{}, []ValueType{ValueTypeI64})
wrap("output_length", []ValueType{}, []ValueType{ValueTypeI64})
wrap("output_offset", []ValueType{}, []ValueType{ValueTypeI64})
wrap("length", []ValueType{ValueTypeI64}, []ValueType{ValueTypeI64})
wrap("reset", []ValueType{}, []ValueType{})
wrap("error_set", []ValueType{ValueTypeI64}, []ValueType{})
wrap("error_get", []ValueType{}, []ValueType{ValueTypeI64})
wrap("memory_bytes", []ValueType{}, []ValueType{ValueTypeI64})

builder.NewFunctionBuilder().
WithGoModuleFunction(api.GoModuleFunc(api.GoModuleFunc(inputLoad_u64)), []ValType{I64}, []ValType{I64}).
WithGoModuleFunction(api.GoModuleFunc(api.GoModuleFunc(inputLoad_u64)), []ValueType{ValueTypeI64}, []ValueType{ValueTypeI64}).
Export("input_load_u64")

builder.NewFunctionBuilder().
WithGoModuleFunction(api.GoModuleFunc(load_u64), []ValType{I64}, []ValType{I64}).
WithGoModuleFunction(api.GoModuleFunc(load_u64), []ValueType{ValueTypeI64}, []ValueType{ValueTypeI64}).
Export("load_u64")

builder.NewFunctionBuilder().
WithGoModuleFunction(api.GoModuleFunc(store_u64), []ValType{I64, I64}, []ValType{}).
WithGoModuleFunction(api.GoModuleFunc(store_u64), []ValueType{ValueTypeI64, ValueTypeI64}, []ValueType{}).
Export("store_u64")

hostFunc := func(name string, f interface{}) {
Expand Down Expand Up @@ -528,3 +537,56 @@ func httpStatusCode(ctx context.Context, m api.Module) int32 {

panic("Invalid context, `plugin` key not found")
}

// EncodeI32 encodes the input as a ValueTypeI32.
func EncodeI32(input int32) uint64 {
return api.EncodeI32(input)
}

// DecodeI32 decodes the input as a ValueTypeI32.
func DecodeI32(input uint64) int32 {
return api.DecodeI32(input)
}

// EncodeU32 encodes the input as a ValueTypeI32.
func EncodeU32(input uint32) uint64 {
return api.EncodeU32(input)
}

// DecodeU32 decodes the input as a ValueTypeI32.
func DecodeU32(input uint64) uint32 {
return api.DecodeU32(input)
}

// EncodeI64 encodes the input as a ValueTypeI64.
func EncodeI64(input int64) uint64 {
return api.EncodeI64(input)
}

// EncodeF32 encodes the input as a ValueTypeF32.
//
// See DecodeF32
func EncodeF32(input float32) uint64 {
return api.EncodeF32(input)
}

// DecodeF32 decodes the input as a ValueTypeF32.
//
// See EncodeF32
func DecodeF32(input uint64) float32 {
return api.DecodeF32(input)
}

// EncodeF64 encodes the input as a ValueTypeF64.
//
// See EncodeF32
func EncodeF64(input float64) uint64 {
return api.EncodeF64(input)
}

// DecodeF64 decodes the input as a ValueTypeF64.
//
// See EncodeF64
func DecodeF64(input uint64) float64 {
return api.DecodeF64(input)
}

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