public_loader_proxy.js

const { Worker } = require('internal/worker');
const { deserialize, serialize } = require('v8');


/**
 * The communication vehicle constituting all memory shared between the main and the worker
 */
const commsChannel = new SharedArrayBuffer(2048);
/**
 * The lock/unlock segment of the shared memory. Atomics require this to be a Int32Array. This
 * segment is used to tell the main to sleep when the worker is worker, and vice verse (for the
 * worker to sleep whilst the main is working).
 * 0 → main sleeps
 * 1 → worker sleeps
 */
const lock = new Int32Array(commsChannel, 0, 4);
/**
 * The request & response segment of the shared memory. TextEncoder/Decoder (needed to convert
 * requests & responses into a format supported by the comms channel) reads and writes with
 * Uint8Array.
 */
const requestResponseData = new Uint8Array(commsChannel, 4, 2044);

const worker = new Worker('./worker.js', {
  workerData: { commsChannel },
});
worker.unref(); // ! Allows the process to eventually exit when worker is in its final sleep.

Atomics.wait(lock, 0, 0); // ! Block this module until the worker is ready.

function makeRequest(type, data) {
  requestResponseData.fill(0); // Erase any previous request/response (it's already been handled)
  const request = serialize({ data, type });
  requestResponseData.set(request);
  Atomics.store(lock, 0, 0); // Send request to worker
  Atomics.notify(lock, 0); // Notify worker of new request
  Atomics.wait(lock, 0, 0); // Sleep until worker responds
  return deserialize(requestResponseData);
}

module.exports = {
  addCustomLoaders: (data) => makeRequest('addCustomLoaders', data),
  cjsCache: {
    delete: (data) => makeRequest('cjsCache.delete', data),
    get: (data) => makeRequest('cjsCache.get', data),
    has: (data) => makeRequest('cjsCache.has', data),
    set: (data) => makeRequest('cjsCache.set', data),
  },
  import: (data) => makeRequest('import', data),
  resolve: (data) => makeRequest('resolve', data),
};