Eliminate multiple API entry points; simplify Node compatibility code.

I found out that you can just create a `Response` object, meaning you
can make any blob work with `WebAssembly.compileStreaming`, and not only
an actual `fetch` response; and that Node doesn't have a working `fetch`
for file URLs but has a working `new Response()`. This allowed me to
simplify this library considerably.

This commit also parallelizes fetching of code and data.

Author: whitequark

.eslintrc.json

@@ -1,7 +1,8 @@
 {
     "env": {
+        "es2021": true,
         "browser": true,
-        "es2021": true
+        "node": true
     },
     "extends": "eslint:recommended",
     "parserOptions": {

.github/workflows/package.yml

@@ -50,7 +50,7 @@ jobs:
   release:
     needs: check
     runs-on: ubuntu-latest
-    if: "contains(github.event.head_commit.message, 'autorelease') && github.event_name == 'push' && github.event.ref == 'refs/heads/develop'"
+    if: contains(github.event.head_commit.message, 'autorelease') && github.event_name == 'push' && github.event.ref == 'refs/heads/develop'
     steps:
       - name: Check out source code
         uses: actions/checkout@v3

lib/api-browser.js

@@ -1,9 +1,45 @@
+import fetch from './fetch.js';
 import { Exit, Environment, directoryFromTree, directoryIntoTree } from './wasi-virt.js';
 import { lineBuffered } from './util.js';
 
 export { Exit } from './wasi-virt.js';
 
-export class BaseApplication {
+async function fetchObject(obj, fetchFn) {
+    // Mutate the object being fetched, to avoid re-fetches within the same session.
+    // Do this in parallel to avoid head-of-line blocking.
+    const promises = [];
+    for (const [key, value] of Object.entries(obj)) {
+        if (typeof value === "string" || value instanceof Uint8Array) {
+            promises.push(Promise.resolve([key, value]));
+        } else if (value instanceof URL) {
+            promises.push(fetchFn(value).then((fetched) => [key, fetched]));
+        } else {
+            promises.push(fetchObject(value, fetchFn).then((fetched) => [key, fetched]));
+        }
+    }
+    for (const [key, value] of await Promise.all(promises))
+        obj[key] = value;
+    return obj;
+}
+
+function fetchWebAssembly(url) {
+    return fetch(url).then(WebAssembly.compileStreaming);
+}
+
+function fetchUint8Array(url) {
+    return fetch(url).then((resp) => resp.arrayBuffer()).then((buf) => new Uint8Array(buf));
+}
+
+function fetchResources({ modules, filesystem }) {
+    return Promise.all([
+        fetchObject(modules, fetchWebAssembly),
+        fetchObject(filesystem, fetchUint8Array)
+    ]).then(([modules, filesystem]) => {
+        return { modules, filesystem };
+    });
+}
+
+export class Application {
     constructor(resourceFileURL, instantiate, argv0) {
         this.resourceFileURL = resourceFileURL;
         this.resources = null;
@@ -14,10 +50,10 @@ export class BaseApplication {
     // The `printLine` option is deprecated and not documented but still accepted for compatibility.
     async run(args = null, files = {}, { stdout, stderr, decodeASCII = true, printLine } = {}) {
         if (this.resources === null)
-            this.resources = await this._fetchResources();
+            this.resources = await import(this.resourceFileURL).then(fetchResources);
 
         if (args === null)
-            return; // only fetch resources
+            return; // prefetch resources, but do not run
 
         const environment = new Environment();
         environment.args = [this.argv0].concat(args);
@@ -51,39 +87,4 @@ export class BaseApplication {
             return files;
         }
     }
-
-    async _fetchResources() {
-        // Async import, to allow inlining some of the resources within resource file.
-        const { modules, filesystem } = await import(this.resourceFileURL);
-        return {
-            modules: await this._fetchObject(modules, this._fetchWebAssembly),
-            filesystem: await this._fetchObject(filesystem, this._fetchUint8Array),
-        };
-    }
-
-    async _fetchObject(obj, fetchFn) {
-        // Mutate the object being fetched, to avoid re-fetches within the same session.
-        // Do this in parallel to avoid head-of-line blocking.
-        const promises = [];
-        for (const [key, value] of Object.entries(obj)) {
-            if (value instanceof URL) {
-                promises.push(fetchFn(value).then((fetched) => [key, fetched]));
-            } else if (typeof value === "string" || value instanceof Uint8Array) {
-                promises.push(Promise.resolve([key, value]));
-            } else {
-                promises.push(this._fetchObject(value, fetchFn).then((fetched) => [key, fetched]));
-            }
-        }
-        for (const [key, value] of await Promise.all(promises))
-            obj[key] = value;
-        return obj;
-    }
-
-    async _fetchUint8Array(_url) {
-        throw 'not implemented';
-    }
-
-    async _fetchWebAssembly(_url) {
-        throw 'not implemented';
-    }
 }

lib/api-node.js

@@ -0,0 +1,15 @@
+// Node v18.x doesn't have a usable `fetch()`.
+let fetch;
+if (typeof process === 'object' && typeof process.release === 'object' && process.release.name === 'node') {
+    fetch = async function(url) {
+        const { readFile } = await import('fs/promises');
+        let contentType = 'application/octet-stream';
+        if (url.pathname.endsWith('.wasm'))
+            contentType = 'application/wasm';
+        return new Response(await readFile(url), { headers: { "Content-Type": contentType } });
+    };
+} else {
+    fetch = globalThis.fetch;
+}
+
+export default fetch;

lib/api-base.js renamed to lib/api.js

@@ -1 +1 @@
-export function lineBuffered(processLine: (line: string) => void): (bytes: Uint8Array) => void;
+export function lineBuffered(processLine: (line: string) => void): (bytes: Uint8Array) => void;

lib/fetch.js

@@ -19,8 +19,7 @@
     ],
     "exports": {
         ".": {
-            "node": "./lib/api-node.js",
-            "browser": "./lib/api-browser.js",
+            "default": "./lib/api.js",
             "types": "./lib/api.d.ts"
         },
         "./util": {

lib/util.d.ts

@@ -7,7 +7,7 @@
         "@yowasp/runtime": "file:../../"
     },
     "devDependencies": {
-        "@bytecodealliance/jco": "^0.14.1"
+        "@bytecodealliance/jco": "0.14.2"
     },
     "scripts": {
         "pack": "yowasp-pack-resources gen/resources.js gen share",