[GitHub] [beam] damondouglas commented on a diff in pull request #24081: Implement embedded WebAssembly example

[GitBox <gi...@apache.org>]

damondouglas commented on code in PR #24081:
URL: https://github.com/apache/beam/pull/24081#discussion_r1020789962


##########
sdks/go/examples/wasm/wasm.go:
##########
@@ -0,0 +1,159 @@
+// Licensed to the Apache Software Foundation (ASF) under one or more
+// contributor license agreements.  See the NOTICE file distributed with
+// this work for additional information regarding copyright ownership.
+// The ASF licenses this file to You under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance with
+// the License.  You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// wasm is an EXPERIMENTAL simple example that loads and executes a wasm file function.
+// greet.wasm, Cargo.toml and greet.rs were copied from the example provided by the wazero library:
+// https://github.com/tetratelabs/wazero/blob/v1.0.0-pre.3/examples/allocation/rust/greet.go
+//
+// New Concepts:
+// 1. Load a wasm file compiled from: cargo build --release --target wasm32-unknown-unknown
+// 2. Execute a wasm function within a DoFn
+package main
+
+import (
+	"context"
+	_ "embed"
+	"flag"
+	"fmt"
+	"github.com/apache/beam/sdks/v2/go/pkg/beam"
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/io/textio"
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/register"
+	"github.com/apache/beam/sdks/v2/go/pkg/beam/x/beamx"
+	"github.com/tetratelabs/wazero"
+	"github.com/tetratelabs/wazero/api"
+	"log"
+)
+
+const (
+	wasmFunctionName           = "greeting"
+	wasmAllocateFunctionName   = "allocate"
+	wasmDeallocateFunctionName = "deallocate"
+)
+
+//go:embed greet.wasm
+var greetWasm []byte
+
+var (
+	output = flag.String("output", "", "Output file (required).")
+)
+
+func init() {
+	// register.DoFnXxY registers a struct DoFn so that it can be correctly
+	// serialized and does some optimization to avoid runtime reflection. Since
+	// embeddedWasmFn's ProcessElement func has 2 inputs (context.Context) and 2 outputs (string, error),
+	// we use register.DoFn2x2 and provide its input and output types as its constraints.
+	// Struct DoFns must be registered for a pipeline to run.
+	register.DoFn2x2[context.Context, string, string, error](&embeddedWasmFn{})
+}
+
+func preRun() error {
+	if *output == "" {
+		return fmt.Errorf("--output is required")
+	}
+	return nil
+}
+
+func main() {
+	flag.Parse()
+	beam.Init()
+	ctx := context.Background()
+	if err := preRun(); err != nil {
+		panic(err)
+	}
+	if err := run(ctx); err != nil {
+		panic(err)
+	}
+}
+
+func run(ctx context.Context) error {
+	p, s := beam.NewPipelineWithRoot()
+
+	in := beam.Create(s, "a", "b", "c", "d", "e", "f", "g", "h")

Review Comment:
   Thank you :-) I replaced with `"Ada", "Lovelace", "World", "Beam", "Senior López"`. The last one is so we can see this with unicode and because Senior López is an important 🐕 member of the Beam community.



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