Function serializeDebugThenable

packages/react-server/src/ReactFlightServer.js:854–948

(
  request: Request,
  counter: {objectLimit: number},
  thenable: Thenable<any>,
)

}

function serializeDebugThenable(
  request: Request,
  counter: {objectLimit: number},
  thenable: Thenable<any>,
): string {
  // Like serializeThenable but for renderDebugModel
  request.pendingDebugChunks++;
  const id = request.nextChunkId++;
  const ref = serializePromiseID(id);
  request.writtenDebugObjects.set(thenable, ref);

  switch (thenable.status) {
    case 'fulfilled': {
      emitOutlinedDebugModelChunk(request, id, counter, thenable.value);
      return ref;
    }
    case 'rejected': {
      const x = thenable.reason;
      // We don't log these errors since they didn't actually throw into Flight.
      const digest = '';
      emitErrorChunk(request, id, digest, x, true, null);
      return ref;
    }
  }

  if (request.status === ABORTING) {
    // Ensure that we have time to emit the halt chunk if we're sync aborting.
    emitDebugHaltChunk(request, id);
    return ref;
  }

  const deferredDebugObjects = request.deferredDebugObjects;
  if (deferredDebugObjects !== null) {
    // For Promises that are not yet resolved, we always defer them. They are async anyway so it's
    // safe to defer them. This also ensures that we don't eagerly call .then() on a Promise that
    // otherwise wouldn't have initialized. It also ensures that we don't "handle" a rejection
    // that otherwise would have triggered unhandled rejection.
    deferredDebugObjects.retained.set(id, (thenable: any));
    const deferredRef = '$Y@' + id.toString(16);
    // We can now refer to the deferred object in the future.
    request.writtenDebugObjects.set(thenable, deferredRef);
    return deferredRef;
  }

  let cancelled = false;

  thenable.then(
    value => {
      if (cancelled) {
        return;
      }
      cancelled = true;
      if (request.status === ABORTING) {
        emitDebugHaltChunk(request, id);
        enqueueFlush(request);
        return;
      }
      emitOutlinedDebugModelChunk(request, id, counter, value);