Generate Web ReadableStream by converting Node.js Readable

test/metadata-parsers.ts

@@ -2,7 +2,7 @@ import fs from 'node:fs';
 
 import * as mm from '../lib/index.js';
 import type { IAudioMetadata, IOptions } from '../lib/index.js';
-import { makeReadableByteFileStream } from './util.js';
+import { makeByteReadableStreamFromFile } from './util.js';
 
 type ParseFileMethod = (skipTest: () => void, filePath: string, mimeType?: string, options?: IOptions) => Promise<IAudioMetadata>;
 
@@ -39,7 +39,7 @@ export const Parsers: IParser[] = [
     description: 'parseWebStream',
     webStream: true,
     initParser: async (skipTest, filePath: string, mimeType?: string, options?: IOptions) => {
-      const webStream = await makeReadableByteFileStream(filePath);
+      const webStream = await makeByteReadableStreamFromFile(filePath);
       try {
         return await mm.parseWebStream(webStream.stream, {mimeType: mimeType, size: webStream.fileSize}, options);
       } finally {

test/util.ts

@@ -3,8 +3,9 @@
 import { Readable } from 'node:stream';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
+import { createReadStream } from 'node:fs';
 import fs from 'node:fs/promises';
-import { ReadableStream } from 'node:stream/web';
+import type {ReadableByteStreamController, ReadableStreamBYOBRequest} from 'node:stream/web';
 
 const filename = fileURLToPath(import.meta.url);
 const dirname = path.dirname(filename);
@@ -24,52 +25,71 @@ export class SourceStream extends Readable {
   }
 }
 
-export async function makeReadableByteFileStream(filename: string, delay = 0): Promise<{ fileSize: number, stream: ReadableStream<Uint8Array>, closeFile: () => Promise<void> }> {
+export async function makeByteReadableStreamFromFile(filename: string): Promise<{ fileSize: number, stream: ReadableStream<Uint8Array>, closeFile: () => Promise<void> }> {
 
-  let position = 0;
   const fileInfo = await fs.stat(filename);
-  const fileHandle = await fs.open(filename, 'r');
+  const nodeStream = createReadStream(filename);
 
   return {
     fileSize: fileInfo.size,
-    stream: new ReadableStream({
-      type: 'bytes',
-
-      async pull(controller) {
-
-        // @ts-ignore
-        const view = controller.byobRequest.view;
-
-        setTimeout(async () => {
-          try {
-            const {bytesRead} = await fileHandle.read(view, 0, view.byteLength, position);
-            if (bytesRead === 0) {
-              await fileHandle.close();
-              controller.close();
-              // @ts-ignore
-              controller.byobRequest.respond(0);
-            } else {
-              position += bytesRead;
-              // @ts-ignore
-              controller.byobRequest.respond(bytesRead);
-            }
-          } catch (err) {
-            controller.error(err);
-            await fileHandle.close();
-          }
-        }, delay);
-      },
-
-      cancel() {
-        return fileHandle.close();
-      },
-
-      autoAllocateChunkSize: 1024
-    }),
-    closeFile: () => {
-      return fileHandle.close();
-    }
+    stream: makeByteReadableStreamFromNodeReadable(nodeStream),
+    closeFile: () => Promise.resolve()
   };
 }
 
+function makeByteReadableStreamFromNodeReadable(nodeReadable: Readable): ReadableStream<Uint8Array> {
+  return new ReadableStream<Uint8Array>({
+    type: 'bytes',
+    start(controller: ReadableByteStreamController) {
+      const onData = (chunk: Buffer) => {
+        if (controller.byobRequest) {
+          const view = (controller.byobRequest as ReadableStreamBYOBRequest).view;
+          const bytesToCopy = Math.min(view.byteLength, chunk.byteLength);
+
+          new Uint8Array(view.buffer, view.byteOffset, view.byteLength)
+            .set(new Uint8Array(chunk.buffer, chunk.byteOffset, bytesToCopy));
+
+          (controller.byobRequest as ReadableStreamBYOBRequest).respond(bytesToCopy);
+
+          if (bytesToCopy < chunk.byteLength) {
+            controller.enqueue(chunk.subarray(bytesToCopy));
+          }
+        } else {
+          controller.enqueue(new Uint8Array(chunk));
+        }
+      };
+
+      const onEnd = () => {
+        controller.close();
+        cleanup();
+      };
+
+      const onError = (err: Error) => {
+        controller.error(err);
+        cleanup();
+      };
+
+      const cleanup = () => {
+        nodeReadable.off('data', onData);
+        nodeReadable.off('end', onEnd);
+        nodeReadable.off('error', onError);
+      };
+
+      nodeReadable.on('data', onData);
+      nodeReadable.on('end', onEnd);
+      nodeReadable.on('error', onError);
+      nodeReadable.resume();
+    },
+    pull(controller) {
+      if (nodeReadable.isPaused()) {
+        nodeReadable.resume();
+      }
+    },
+    cancel(reason) {
+      nodeReadable.destroy(reason);
+    }
+  });
+}
+
+
 export const samplePath = path.join(dirname, 'samples');