Fast Allocation of ArrayBuffer with maxByteLength

[ronag]

Currently we have an optimization which turns off zero fill of ArrayBuffers during allocation through the Buffer.allocUnsafeSlow method:

let zeroFill = getZeroFillToggle();
function createUnsafeBuffer(size) {
  zeroFill[0] = 0;
  try {
    return new FastBuffer(size);
  } finally {
    zeroFill[0] = 1;
  }
}

This can be used to quickly allocate ArrayBuffers:

const arrayBuffer = Buffer.allocateUnsafeSlow(size).buffer

The problem is that this does not allow allocating ArrayBuffers with a specified maxByteLength:

const arrayBuffer = new ArrayBuffer(size, { maxByteLength: capacity })

Could we add some way to perform the allocation similarly? Maybe an option to Buffer.allocateUnsafeSlow?

[ronag]

@joyeecheung @nodejs/performance @nodejs/buffer

[joyeecheung]

On a side note it seems we need general support for resizable array buffers in the Buffer API…

[mcollina]

On a side note it seems we need general support for resizable array buffers in the Buffer API…

I agree. They are almost a game-changing feature for a lot of cases.

[ronag]

If there was a way to write to and read from arrays buffers without always allocating a 200+ byte typed array that would be even cooler.