Envisioned use of BYOB reader to reuse buffers

ping-pong.js

// Run processFn on each chunk, while only ever allocating maxChunkSize * 2
// memory, and never causing GC (by reusing the same backing buffers)
// Is able to do a read in parallel with the async processFn operation!
async function processPingPong(rbs, maxChunkSize, processFn) {
  const reader = rbs.getByobReader();
  const pool = [new Uint8Array(maxChunkSize), new Uint8Array(maxChunkSize)];
  
  let i = 0;
  let toProcess;
  await doRead(0);

  while (!toProcess.done) {
    await Promise.all([
      doProcess(i % 2),
      doRead((i + 1) % 2)
    ]);
    ++i;
  }
  
  function doProcess(i) {
    const view = toProcess.value;
    await processFn(view);
    pool[i] = view;
  }
  
  function doRead(i) {
    toProcess = await reader.read(pool[i]);
  }
}

reuse-buffers.js

// Run processFn on each chunk, while only ever allocating maxChunkSize
// memory, and never causing GC (by reusing the same backing buffer)
async function processChunkwise(rbs, maxChunkSize, processFn) {
  const reader = rbs.getByobReader();

  let currentView = new Uint8Array(maxChunkSize);
  let result;
  while (!(result = await reader.read(currentView)).done) {
    // calling reader.read detaches currentView, but reuses its backing buffer
    // now result.value uses the same backing buffer and is not detached

    // result.value.byteLength contains the number of bytes read
    // (which might be less than maxChunkSize)
    await processChunk(result.value);

    // reuse the same backing buffer for the next iteration
    currentView = result.value;
  }
}