exp: javy& wasmtime-go

wasm-play/README.md

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+# WASM experiment
+
+## Compile JS to WASM
+
+```bash
+npx javy-cli@latest compile samples/hello.js -o samples/hello.wasm  --wit samples/index.wit -n index-world
+```
+
+## Executing
+
+using wasmtime cli:
+install cli:
+
+```bash
+curl https://wasmtime.dev/install.sh -sSf | bash
+```
+
+```bash
+echo '{"foo": "bar"}' | wasmtime --invoke run samples/hello.wasm  
+```
+
+using Go:
+
+```bash
+echo '{}' |  go run main.go
+```

wasm-play/go.mod

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+module rudder-transformer/wasm-play
+
+go 1.21.5
+
+require github.com/bytecodealliance/wasmtime-go v1.0.0

wasm-play/go.sum

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+github.com/bytecodealliance/wasmtime-go v1.0.0 h1:9u9gqaUiaJeN5IoD1L7egD8atOnTGyJcNp8BhkL9cUU=
+github.com/bytecodealliance/wasmtime-go v1.0.0/go.mod h1:jjlqQbWUfVSbehpErw3UoWFndBXRRMvfikYH6KsCwOg=

wasm-play/index.js

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+// Assume add.wasm file exists that contains a single function adding 2 provided arguments
+import fs from 'node:fs';
+
+const wasmBuffer = fs.readFileSync('./samples/sample1.wasm');
+const wasmModule = await WebAssembly.instantiate(wasmBuffer, {
+    imports: {
+        print(arg) {
+          console.log(arg);
+        },
+    },
+    env: {
+        abortStackOverflow: () => { throw new Error('overflow'); },
+        table: new WebAssembly.Table({ initial: 0, element: 'anyfunc' }),
+        __table_base: 0,
+        memory: new WebAssembly.Memory({ initial: 256 }),
+        __memory_base: 1024,
+        STACKTOP: 0,
+        STACK_MAX: 0,
+    }
+});
+
+console.log(wasmModule.instance)

wasm-play/main.go

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+package main
+
+import (
+	"log"
+	"os"
+
+	"github.com/bytecodealliance/wasmtime-go"
+)
+
+func main() {
+	engine := wasmtime.NewEngine()
+	// Almost all operations in wasmtime require a contextual `store`
+	// argument to share, so create that first
+	store := wasmtime.NewStore(engine)
+
+	wasm, err := os.ReadFile("./samples/hello.wasm")
+	check(err)
+	// Once we have our binary `wasm` we can compile that into a `*Module`
+	// which represents compiled JIT code.
+	module, err := wasmtime.NewModule(engine, wasm)
+	check(err)
+
+	// Create a linker with WASI functions defined within it
+	linker := wasmtime.NewLinker(engine)
+	check(err)
+
+	err = linker.DefineWasi()
+	check(err)
+
+	// Configure WASI imports to write stdout into a file, and then create
+	// a `Store` using this wasi configuration.
+	wasiConfig := wasmtime.NewWasiConfig()
+	wasiConfig.InheritStdout()
+	wasiConfig.InheritStderr()
+	wasiConfig.InheritStdin()
+	store.SetWasi(wasiConfig)
+
+	instance, err := linker.Instantiate(store, module)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// After we've instantiated we can lookup our `run` function and call
+	// it.
+	run := instance.GetFunc(store, "run")
+	if run == nil {
+		panic("not a function")
+	}
+	_, err = run.Call(store)
+	check(err)
+
+}
+
+func check(e error) {
+	if e != nil {
+		panic(e)
+	}
+}

wasm-play/samples/hello.js

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+
+
+
+// The transform function.
+function transform(input) {
+    return { foo: input.n + 1, newBar: input.bar + "!" };
+}
+
+// SUPPORT CODE:
+
+
+// Read input from stdin
+function readInput() {
+    const chunkSize = 1024;
+    const inputChunks = [];
+    let totalBytes = 0;
+
+    // Read all the available bytes
+    while (1) {
+        const buffer = new Uint8Array(chunkSize);
+        // Stdin file descriptor
+        const fd = 0;
+        const bytesRead = Javy.IO.readSync(fd, buffer);
+
+        totalBytes += bytesRead;
+        if (bytesRead === 0) {
+            break;
+        }
+        inputChunks.push(buffer.subarray(0, bytesRead));
+    }
+
+    // Assemble input into a single Uint8Array
+    const { finalBuffer } = inputChunks.reduce((context, chunk) => {
+        context.finalBuffer.set(chunk, context.bufferOffset);
+        context.bufferOffset += chunk.length;
+        return context;
+    }, { bufferOffset: 0, finalBuffer: new Uint8Array(totalBytes) });
+
+    return JSON.parse(new TextDecoder().decode(finalBuffer));
+}
+
+// Write output to stdout
+function writeOutput(output) {
+    const encodedOutput = new TextEncoder().encode(JSON.stringify(output));
+    const buffer = new Uint8Array(encodedOutput);
+    // Stdout file descriptor
+    const fd = 1;
+    Javy.IO.writeSync(fd, buffer);
+}
+
+
+export function run() {
+    // Read input from stdin
+    const input = readInput();
+    // Call the function with the input
+    const result = transform(input);
+    // Write the result to stdout
+    writeOutput(result);
+}

wasm-play/samples/index.wit

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+package local:main;
+
+world index-world {
+  export run: func(); 
+}