damondouglas commented on code in PR #24081: URL: https://github.com/apache/beam/pull/24081#discussion_r1020790141
########## 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") + + out := beam.ParDo(s.Scope("embeddedWasm"), &embeddedWasmFn{}, in) + + textio.Write(s, *output, out) + + if err := beamx.Run(ctx, p); err != nil { + return fmt.Errorf("failed to run pipeline: %v", err) + } + return nil +} + +// Concept #2 wrap wasm function execution within a DoFn. +// wasmFn wraps a DoFn to execute a Rust compiled wasm function +type embeddedWasmFn struct { + r wazero.Runtime + mod api.Module + greeting, allocate, deallocate api.Function +} + +// Setup loads and initializes the embedded wasm functions +// Concept #1: Load a compiled wasm file []byte content and function. +// This example is derived from +// https://github.com/tetratelabs/wazero/blob/v1.0.0-pre.3/examples/allocation/rust/greet.go +func (fn *embeddedWasmFn) Setup(ctx context.Context) error { + fn.r = wazero.NewRuntime(ctx) + _, err := fn.r.NewHostModuleBuilder("env"). + NewFunctionBuilder().WithFunc(logString).Export("log"). + Instantiate(ctx, fn.r) + if err != nil { + return fmt.Errorf("failed to instantiate host module: %w", err) + } + fn.mod, err = fn.r.InstantiateModuleFromBinary(ctx, greetWasm) + if err != nil { + return fmt.Errorf("failed to instantiate wasm module: %v", err) + } + fn.greeting = fn.mod.ExportedFunction(wasmFunctionName) + fn.allocate = fn.mod.ExportedFunction(wasmAllocateFunctionName) + fn.deallocate = fn.mod.ExportedFunction(wasmDeallocateFunctionName) + return nil +} + +// ProcessElement processes a string calling a wasm function written in Rust +// This example is derived from +// https://github.com/tetratelabs/wazero/blob/v1.0.0-pre.3/examples/allocation/rust/greet.go +func (fn *embeddedWasmFn) ProcessElement(ctx context.Context, s string) (string, error) { + size := uint64(len(s)) + results, err := fn.allocate.Call(ctx, size) + if err != nil { + return "", fmt.Errorf("error calling allocate: %w", err) + } + ptr := results[0] + defer fn.deallocate.Call(ctx, ptr, size) + if !fn.mod.Memory().Write(ctx, uint32(ptr), []byte(s)) { + return "", fmt.Errorf("Memory.Write(%d, %d) out of range of memory size %d", + ptr, size, fn.mod.Memory().Size(ctx)) + } + + ptrSize, err := fn.greeting.Call(ctx, ptr, size) + resultPtr := uint32(ptrSize[0] >> 32) + resultSize := uint32(ptrSize[0]) + defer fn.deallocate.Call(ctx, uint64(resultPtr), uint64(resultSize)) + bytes, ok := fn.mod.Memory().Read(ctx, resultPtr, resultSize) + if !ok { + return "", fmt.Errorf("Memory.Read(%d, %d) out of range of memory size %d", + resultPtr, resultSize, fn.mod.Memory().Size(ctx)) + } + return string(bytes), nil +} Review Comment: I added back the original helpful comments from the wazero example with some edits to reflect the Beam context within which the DoFn invokes these methods. -- This is an automated message from the Apache Git Service. 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