Function followCompositeSignal

lib/internal/abort_controller.js:159–192

(signal)

}

function followCompositeSignal(signal) {
  if (signal[kFollowing] || signal[kAborted] || !signal[kSourceSignals]?.size) {
    return;
  }

  const resultSignalWeakRef = signal[kResultSignalWeakRef] ??= new SafeWeakRef(signal);

  for (const sourceSignalWeakRef of signal[kSourceSignals]) {
    const sourceSignal = sourceSignalWeakRef.deref();
    if (sourceSignal === undefined) {
      signal[kSourceSignals].delete(sourceSignalWeakRef);
      continue;
    }

    if (sourceSignal.aborted) {
      abortSignal(signal, sourceSignal.reason);
      return;
    }

    sourceSignal[kDependantSignals] ??= new SafeSet();
    sourceSignal[kDependantSignals].add(resultSignalWeakRef);
    dependantSignalsCleanupRegistry.register(signal, {
      sourceSignalRef: sourceSignalWeakRef,
      dependantSignalRef: resultSignalWeakRef,
      sourceSignalsCleanupToken: sourceSignalWeakRef,
    });
    sourceSignalsCleanupRegistry.register(sourceSignal, {
      sourceSignalRef: sourceSignalWeakRef,
      composedSignalRef: resultSignalWeakRef,
    }, sourceSignalWeakRef);
  }

  signal[kFollowing] = true;
}

// Because the AbortSignal timeout cannot be canceled, we don't want the
// presence of the timer alone to keep the AbortSignal from being garbage