Purpose/Motivation

Defines a device-based storage object that may be used by WebNN operations. This is a sub-issue of #482.

Proposed API

typedef unsigned long MLFlagsConstant;

[Exposed=(Window, DedicatedWorker)]
interface MLBuffer {
  readonly attribute MLFlagsConstant usage;
  readonly attribute MLOperandDescriptor descriptor;
  [CallWith=Isolate] void destroy();
}

[Exposed=(Window, DedicatedWorker), SecureContext]
namespace MLBufferUsage {
    // TBD
};

[Exposed=(Window, DedicatedWorker), SecureContext]
partial interface MLContext {
    Promise<MLBuffer> createBuffer(MLOperandDescriptor descriptor, MLBufferUsage usages);
};

Example JS

const ml_buffer = await mlContext.createBuffer(descriptor, usages);
ml_buffer.Destroy(); // invalid

• The buffer's allocation will be zeroed (as it is for WebGPU's createBuffer() method)
• Layout of MLBuffer is always known (and linear access is assumed).
• Destroy() gets called on the context timeline but doesn't actually release until the device signals completion.

Edits

• 5/14/24 - Removed "size" in favor or using MLOperandDescriptor
• 6/03/24 - Added usage flags and descriptor attributes
• 7/09/24 - createBuffer() now returns promise.

Alternative API proposals

N/A

Opens

1. Where will an MLBuffer's memory be allocated on systems where an MLContext may not be as closely tied to a given physical device as an IDMLDevice? See Need to understand how WebNN supports implementation that involves multiple devices and timelines #350 @a-sully
2. Must an MLBuffer only be used with an MLContext it was created from? @a-sully
3. Can an MLBuffer's size always be known at the time of buffer allocation? @a-sully
4. When will MLBuffer be deallocated if destroy() is not called? @a-sully
5. Does MLBuffer require explicit buffer usages (ex. input, output, or both)? @bbernhar
6. Does MLBuffer need to support being a staging buffer? @bbernhar
7. Is a zero sized MLBuffer allowed? @bbernhar