What happens if a cache fails to download

[jakearchibald]

this.oninstall = function(event) {
  var core = new Cache(
    // urls
  );
  var level1 = new Cache(
    // urls
  );
  var level2 = new Cache(
    // urls
  );

  caches.set('core', core);
  caches.set('level1', level1);
  caches.set('level2', level2);

  event.waitUntil(Promise.all([core, level1]));
};

Here I only want to wait until the core & level1 download. I'm happy for this to be my offline experience, and level 2 etc will download in the background.

If core or level1 fail, that's covered by #115, but what if level2 fails?

I suppose I could do:

this.onfetch = function(event) {
  if (event.type === 'navigate') {
    caches.forEach(function(cache) {
      cache.ready().catch(cache.update.bind(cache));
    });
  }

  //...
}

Or should failed cache creation/update be automatically retried?

[KenjiBaheux]

@jakearchibald

Does the latest spec capture the expected behavior? I'm thinking of the following sentence: "If any oninstall handler throws an exception, or if any lifetime extension via event.waitUntil() fails (via promise rejection), installation fails and activation is not carried out. "

I'm assuming that the latest incarnation of caches.set (*) would throw if it fails.
*: I couldn't find it in CacheStorage interface, will double check with the team and file a new issue if appropriate.

Should this issue be closed? If not can you explain what's missing?

Background:
I'm going over the open issues, hoping to understand the potential impact against our current implementation.

[jakearchibald]

Yeah, spec covers this.

As for caches.set, we're still debating whether it should exist vs caches.create(name). We'll definitely have the latter, but unsure whether we should have the former & allow new Cache() to work.