Method enable

lib/async_hooks.js:108–141

()

  }

  enable() {
    // The set of callbacks for a hook should be the same regardless of whether
    // enable()/disable() are run during their execution. The following
    // references are reassigned to the tmp arrays if a hook is currently being
    // processed.
    const { 0: hooks_array, 1: hook_fields } = getHookArrays();

    // Each hook is only allowed to be added once.
    if (ArrayPrototypeIncludes(hooks_array, this))
      return this;

    const prev_kTotals = hook_fields[kTotals];

    // createHook() has already enforced that the callbacks are all functions,
    // so here simply increment the count of whether each callbacks exists or
    // not.
    hook_fields[kTotals] = hook_fields[kInit] += +!!this[init_symbol];
    hook_fields[kTotals] += hook_fields[kBefore] += +!!this[before_symbol];
    hook_fields[kTotals] += hook_fields[kAfter] += +!!this[after_symbol];
    hook_fields[kTotals] += hook_fields[kDestroy] += +!!this[destroy_symbol];
    hook_fields[kTotals] +=
        hook_fields[kPromiseResolve] += +!!this[promise_resolve_symbol];
    ArrayPrototypePush(hooks_array, this);

    if (prev_kTotals === 0 && hook_fields[kTotals] > 0) {
      enableHooks();
    }

    if (!this[kNoPromiseHook]) {
      updatePromiseHookMode();
    }

    return this;
  }

  disable() {
    const { 0: hooks_array, 1: hook_fields } = getHookArrays();