Interface

Interface: Transferable

Objects may implement the Transferable interface to create their own custom transferable objects. This is useful when an object being passed into or from a worker contains a deeply nested transferable object such as an ArrayBuffer or MessagePort.

Transferable objects expose two properties inspected by Piscina to determine how to transfer the object. These properties are named using the special static Piscina.transferableSymbol and Piscina.valueSymbol properties:

• The Piscina.transferableSymbol property provides the object (or objects) that are to be included in the transferList.

• The Piscina.valueSymbol property provides a surrogate value to transmit in place of the Transferable itself.

Both properties are required.

For example:

const {
  move,
  transferableSymbol,
  valueSymbol
} = require('piscina');

module.exports = () => {
  const obj = {
    a: { b: new Uint8Array(5); },
    c: { new Uint8Array(10); },

    get [transferableSymbol]() {
      // Transfer the two underlying ArrayBuffers
      return [this.a.b.buffer, this.c.buffer];
    }

    get [valueSymbol]() {
      return { a: { b: this.a.b }, c: this.c };
    }
  };
  return move(obj);
};