nstdlib-nightly/lib/internal/heap_utils.mjs

Node.js standard library converted to runtime-agnostic ES modules.

// Source: https://github.com/nodejs/node/blob/65eff1eb/lib/internal/heap_utils.js

import {
  kUpdateTimer,
  onStreamRead,
} from "nstdlib/lib/internal/stream_base_commons";
import { symbols as __symbols__ } from "nstdlib/lib/internal/async_hooks";
import { Readable } from "nstdlib/lib/stream";
import {
  validateObject,
  validateBoolean,
  validateFunction,
} from "nstdlib/lib/internal/validators";
import { codes as __codes__ } from "nstdlib/lib/internal/errors";
import {
  kEmptyObject,
  emitExperimentalWarning,
} from "nstdlib/lib/internal/util";
import { queryObjects as _queryObjects } from "nstdlib/stub/binding/internal_only_v8";
import { inspect } from "nstdlib/lib/internal/util/inspect";

const { owner_symbol } = __symbols__;

const { ERR_INVALID_ARG_VALUE } = __codes__;
const kHandle = Symbol("kHandle");

function getHeapSnapshotOptions(options = kEmptyObject) {
  validateObject(options, "options");
  const { exposeInternals = false, exposeNumericValues = false } = options;
  validateBoolean(exposeInternals, "options.exposeInternals");
  validateBoolean(exposeNumericValues, "options.exposeNumericValues");
  return new Uint8Array([+exposeInternals, +exposeNumericValues]);
}

class HeapSnapshotStream extends Readable {
  constructor(handle) {
    super({ autoDestroy: true });
    this[kHandle] = handle;
    handle[owner_symbol] = this;
    handle.onread = onStreamRead;
  }

  _read() {
    if (this[kHandle]) this[kHandle].readStart();
  }

  _destroy() {
    // Release the references on the handle so that
    // it can be garbage collected.
    this[kHandle][owner_symbol] = undefined;
    this[kHandle] = undefined;
  }

  [kUpdateTimer]() {
    // Does nothing
  }
}

const inspectOptions = {
  __proto__: null,
  depth: 0,
};
function queryObjects(ctor, options = kEmptyObject) {
  validateFunction(ctor, "constructor");
  if (options !== kEmptyObject) {
    validateObject(options, "options");
  }
  const format = options.format || "count";
  if (format !== "count" && format !== "summary") {
    throw new ERR_INVALID_ARG_VALUE("options.format", format);
  }
  emitExperimentalWarning("v8.queryObjects()");
  // Matching the console API behavior - just access the .prototype.
  const objects = _queryObjects(ctor.prototype);
  if (format === "count") {
    return objects.length;
  }
  // options.format is 'summary'.
  return Array.prototype.map.call(objects, (object) =>
    inspect(object, inspectOptions),
  );
}

export { getHeapSnapshotOptions };
export { HeapSnapshotStream };
export { queryObjects };