static ResourceLoadPriority loadPriority(Resource::Type type, const FetchRequest& request)
{
if (request.priority() != ResourceLoadPriorityUnresolved)
return request.priority();
switch (type) {
case Resource::MainResource:
return ResourceLoadPriorityVeryHigh;
case Resource::Raw:
case Resource::Font:
case Resource::ImportResource:
return ResourceLoadPriorityMedium;
case Resource::Image:
// We'll default images to VeryLow, and promote whatever is visible. This improves
// speed-index by ~5% on average, ~14% at the 99th percentile.
return ResourceLoadPriorityVeryLow;
case Resource::Media:
return ResourceLoadPriorityLow;
case Resource::LinkPrefetch:
return ResourceLoadPriorityVeryLow;
case Resource::LinkSubresource:
return ResourceLoadPriorityLow;
}
ASSERT_NOT_REACHED();
return ResourceLoadPriorityUnresolved;
}
ResourcePtr<Resource> ResourceFetcher::requestResource(Resource::Type type, FetchRequest& request)
{
ASSERT(request.options().synchronousPolicy == RequestAsynchronously || type == Resource::Raw);
TRACE_EVENT0("blink", "ResourceFetcher::requestResource");
KURL url = request.resourceRequest().url();
WTF_LOG(ResourceLoading, "ResourceFetcher::requestResource '%s', charset '%s', priority=%d, type=%s", url.elidedString().latin1().data(), request.charset().latin1().data(), request.priority(), ResourceTypeName(type));
// If only the fragment identifiers differ, it is the same resource.
url = MemoryCache::removeFragmentIdentifierIfNeeded(url);
if (!url.isValid())
return 0;
if (!canRequest(type, url, request.options(), request.originRestriction()))
return 0;
if (LocalFrame* f = frame())
f->loaderClient()->dispatchWillRequestResource(&request);
// See if we can use an existing resource from the cache.
ResourcePtr<Resource> resource = memoryCache()->resourceForURL(url);
const RevalidationPolicy policy = determineRevalidationPolicy(type, request, resource.get());
switch (policy) {
case Reload:
memoryCache()->remove(resource.get());
// Fall through
case Load:
resource = createResourceForLoading(type, request, request.charset());
break;
case Revalidate:
resource = createResourceForRevalidation(request, resource.get());
break;
case Use:
memoryCache()->updateForAccess(resource.get());
break;
}
if (!resource)
return 0;
if (!resource->hasClients())
m_deadStatsRecorder.update(policy);
if (policy != Use)
resource->setIdentifier(createUniqueIdentifier());
ResourceLoadPriority priority = loadPriority(type, request);
if (priority != resource->resourceRequest().priority()) {
resource->mutableResourceRequest().setPriority(priority);
resource->didChangePriority(priority, 0);
}
if (resourceNeedsLoad(resource.get(), request, policy)) {
if (!shouldLoadNewResource(type)) {
if (memoryCache()->contains(resource.get()))
memoryCache()->remove(resource.get());
return 0;
}
resource->load(this, request.options());
// For asynchronous loads that immediately fail, it's sufficient to return a
// null Resource, as it indicates that something prevented the load from starting.
// If there's a network error, that failure will happen asynchronously. However, if
// a sync load receives a network error, it will have already happened by this point.
// In that case, the requester should have access to the relevant ResourceError, so
// we need to return a non-null Resource.
if (resource->errorOccurred()) {
if (memoryCache()->contains(resource.get()))
memoryCache()->remove(resource.get());
return 0;
}
}
requestLoadStarted(resource.get(), request, policy == Use ? ResourceLoadingFromCache : ResourceLoadingFromNetwork);
ASSERT(resource->url() == url.string());
m_documentResources.set(resource->url(), resource);
return resource;
}