main.go

package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/bytecodealliance/wasmtime-go"
)

func getRSS() int64 {
	buf, err := ioutil.ReadFile("/proc/self/statm")
	if err != nil {
		panic(err)
	}

	fields := strings.Split(string(buf), " ")
	if len(fields) < 2 {
		panic(err)
	}

	rss, err := strconv.ParseInt(fields[1], 10, 64)
	if err != nil {
		panic(err)
	}

	return (rss * int64(os.Getpagesize())) / (1024 * 1024)
}

func main() {

	store := wasmtime.NewStore(wasmtime.NewEngine())

	wasm, err := ioutil.ReadFile("policy.wasm")
	if err != nil {
		panic(err)
	}

	module, err := wasmtime.NewModule(store.Engine, wasm)
	if err != nil {
		panic(err)
	}

	memorytype := wasmtime.NewMemoryType(wasmtime.Limits{Min: 2})
	memory := wasmtime.NewMemory(store, memorytype)

	opaAbort := wasmtime.WrapFunc(store, func(int32) {
		panic("opa_abort")
	})

	opaBuiltin0 := wasmtime.WrapFunc(store, func(int32, int32) int32 {
		panic("opaBuiltin0")
	})

	opaBuiltin1 := wasmtime.WrapFunc(store, func(int32, int32, int32) int32 {
		panic("opaBuiltin1")
	})

	opaBuiltin2 := wasmtime.WrapFunc(store, func(int32, int32, int32, int32) int32 {
		panic("opaBuiltin2")
	})

	opaBuiltin3 := wasmtime.WrapFunc(store, func(int32, int32, int32, int32, int32) int32 {
		panic("opaBuiltin3")
	})

	opaBuiltin4 := wasmtime.WrapFunc(store, func(int32, int32, int32, int32, int32, int32) int32 {
		panic("opaBuiltin4")
	})

	for {
		instance, err := wasmtime.NewInstance(store, module, []*wasmtime.Extern{
			memory.AsExtern(),
			opaAbort.AsExtern(),
			opaBuiltin0.AsExtern(),
			opaBuiltin1.AsExtern(),
			opaBuiltin2.AsExtern(),
			opaBuiltin3.AsExtern(),
			opaBuiltin4.AsExtern(),
		})
		if err != nil {
			panic(err)
		}

		fmt.Println(getRSS(), "MB")
		_ = instance
		time.Sleep(time.Millisecond * 100)
	}

}