Bug 26421 – resources not fetched when application cache is on

• Component: Page Loading
• Status: RESOLVED INVALID

[Yong Li]

When application cache is used, fetching some resources that are neither in the cache nor in application cache fallback URL list can be refused.

As a result, the software doesn't show the list of checkboxes on http://static.webvm.net/appcache/todo.html

bool DocumentLoader::shouldLoadResourceFromApplicationCache(const ResourceRequest& request, ApplicationCacheResource*& resource)
{
    ApplicationCache* cache = applicationCache();
    if (!cache || !cache->isComplete())
        return false;

    // If the resource is not a HTTP/HTTPS GET, then abort
    if (!ApplicationCache::requestIsHTTPOrHTTPSGet(request))
        return false;

    // If the resource's URL is an master entry, the manifest, an explicit entry, a fallback entry, or a dynamic entry
    // in the application cache, then get the resource from the cache (instead of fetching it).
    resource = cache->resourceForURL(request.url());

    // Resources that match fallback namespaces or online whitelist entries are fetched from the network,
    // unless they are also cached.
    if (!resource && (cache->urlMatchesFallbackNamespace(request.url()) || cache->isURLInOnlineWhitelist(request.url())))
        return false;

    // Resources that are not present in the manifest will always fail to load (at least, after the
    // cache has been primed the first time), making the testing of offline applications simpler.
    return true;
}

[Yong Li]

Possible solution?

change the following code:

    if (!resource && (cache->urlMatchesFallbackNamespace(request.url()) || cache->isURLInOnlineWhitelist(request.url())))
        return false;

into:

    if (!resource || cache->urlMatchesFallbackNamespace(request.url()) || cache->isURLInOnlineWhitelist(request.url()))
        return false;

[Anders Carlsson]

It's actually a feature not to fetch resources not listed in the manifest when using the application cache, see 

http://www.whatwg.org/specs/web-apps/current-work/#changesToNetworkingModel