Optimize asset loading & caching

only fetch each resource from the network once,
and only compile each wasm module once

package.json

@@ -1,6 +1,6 @@
 {
  "name": "faust-loader",
- "version": "1.1.1",
+ "version": "1.2.0",
  "main": "dist/faustLoader.js",
  "types": "dist/faustLoader.d.ts",
  "scripts": {

src/loadProcessor.ts

@@ -10,7 +10,39 @@ function heap2Str(buf: Uint8Array) {
  return str;
 }
 
-const loadedProcessors: string[] = [];
+const processorModules: Record<string, Promise<void>> = {};
+async function loadProcessorModule(context: IAudioContext, url: string) {
+ if (!context.audioWorklet) {
+ console.error(
+ "Error loading FaustAudioProcessorNode: standardized-audio-context AudioWorklet isn't supported in this environment."
+ );
+ return null;
+ }
+
+ const existing = processorModules[url];
+
+ if (existing) {
+ return existing;
+ }
+
+ processorModules[url] = context.audioWorklet.addModule(url);
+ return processorModules[url];
+}
+
+const wasmModules: Record<string, Promise<WebAssembly.Module>> = {};
+async function getWasmModule(url: string) {
+ const existing = wasmModules[url];
+
+ if (existing) {
+ return existing;
+ }
+
+ wasmModules[url] = fetch(url)
+ .then((response) => response.arrayBuffer())
+ .then((dspBuffer) => WebAssembly.compile(dspBuffer));
+ return wasmModules[url];
+}
+
 const importObject = {
  env: {
  memoryBase: 0,
@@ -81,32 +113,19 @@ export default async function loadProcessor(
  baseURL: string
 ) {
  const cleanedBaseURL = baseURL.endsWith("/") ? baseURL : `${baseURL}/`;
- // Load DSP wasm
- const dspFile = await fetch(`${cleanedBaseURL}${name}.wasm`);
- const dspBuffer = await dspFile.arrayBuffer();
- const dspModule = await WebAssembly.compile(dspBuffer);
+
+ const [dspModule] = await Promise.all([
+ getWasmModule(`${cleanedBaseURL}${name}.wasm`),
+ loadProcessorModule(context, `${cleanedBaseURL}${name}-processor.js`),
+ ]);
+
  const dspInstance = await WebAssembly.instantiate(dspModule, importObject);
 
  const HEAPU8 = new Uint8Array(dspInstance.exports.memory.buffer);
  const json = heap2Str(HEAPU8);
  const json_object = JSON.parse(json);
  const processorOptions = { wasm_module: dspModule, json: json };
 
- if (!context.audioWorklet) {
- console.error(
- "Error loading FaustAudioProcessorNode: standardized-audio-context AudioWorklet isn't supported in this environment."
- );
- return null;
- }
-
- // Load processor script, if necessary
- if (!loadedProcessors.includes(name)) {
- await context.audioWorklet.addModule(
- `${cleanedBaseURL}${name}-processor.js`
- );
- loadedProcessors.push(name);
- }
-
  const nodeOptions = {
  numberOfInputs: parseInt(json_object.inputs) > 0 ? 1 : 0,
  numberOfOutputs: parseInt(json_object.outputs) > 0 ? 1 : 0,

test/index.js

@@ -2,7 +2,10 @@ import { AudioContext } from "standardized-audio-context";
 import createCompressor from "./Compressor.dsp";
 
 const ctx = new AudioContext();
-createCompressor(ctx).then((node) => {
- console.log(node);
- console.log(node.getParams());
+Promise.all([
+ createCompressor(ctx),
+ createCompressor(ctx),
+ createCompressor(ctx),
+]).then((nodes) => {
+ console.log(nodes);
 });