f

worker.ts

@@ -7,16 +7,53 @@ export interface EventData {
 }
 
 addEventListener("message", async ({ data }: MessageEvent<EventData>) => {
-  for (const item of data.chunks) {
-    const r = await fetch(data.url, {
-      headers: {
-        ...data.headers,
-        Range: `bytes=${item.start}-${item.end}`,
-      },
-    });
-    if (r.status !== 206) throw new Error(`Invalid status code ${r.status}"}`);
-    const buf = new Uint8Array(await r.arrayBuffer());
-    self.postMessage(buf, [buf]);
+  const r = await fetch(data.url, {
+    headers: {
+      ...data.headers,
+      Range: `bytes=${data.chunks[0].start}-${data.chunks.at(-1)!.end}`,
+    },
+  });
+  if (r.status !== 206) throw new Error(`Invalid status code ${r.status}"}`);
+  if (!r.body) throw new Error("No body");
+  const reader = r.body.getReader();
+  let currentChunkIndex = 0;
+  let currentBuffer: Uint8Array | null = null;
+  let bufferOffset = 0;
+  try {
+    while (true) {
+      const { done, value } = await reader.read();
+      if (done) break;
+      let bytesProcessed = 0;
+      while (bytesProcessed < value.length) {
+        if (!currentBuffer && currentChunkIndex < data.chunks.length) {
+          const chunk = data.chunks[currentChunkIndex];
+          currentBuffer = new Uint8Array(chunk.end - chunk.start + 1);
+          bufferOffset = 0;
+        }
+        if (!currentBuffer) throw new Error("Unexpected extra data received");
+        const remainingBytes = currentBuffer.length - bufferOffset;
+        const bytesToCopy = Math.min(
+          remainingBytes,
+          value.length - bytesProcessed
+        );
+        currentBuffer.set(
+          value.subarray(bytesProcessed, bytesProcessed + bytesToCopy),
+          bufferOffset
+        );
+        bufferOffset += bytesToCopy;
+        bytesProcessed += bytesToCopy;
+        if (bufferOffset === currentBuffer.length) {
+          postMessage(currentBuffer, [currentBuffer]);
+          currentChunkIndex++;
+          currentBuffer = null;
+        }
+      }
+    }
+    if (currentChunkIndex !== data.chunks.length || currentBuffer) {
+      throw new Error("Incomplete data received");
+    }
+  } finally {
+    reader.releaseLock();
   }
 });