// gets a new set of elements
// always creates a new set of elements,
// even though the underlying elements may not change (store snapshots)
public PublishedSnapshot.PublishedSnapshotElements GetElements(bool previewDefault)
{
EnsureCaches();
// note: using ObjectCacheAppCache for elements and snapshot caches
// is not recommended because it creates an inner MemoryCache which is a heavy
// thing - better use a dictionary-based cache which "just" creates a concurrent
// dictionary
// for snapshot cache, DictionaryAppCache MAY be OK but it is not thread-safe,
// nothing like that...
// for elements cache, DictionaryAppCache is a No-No, use something better.
// ie FastDictionaryAppCache (thread safe and all)
ContentStore.Snapshot contentSnap, mediaSnap;
SnapDictionary <int, Domain> .Snapshot domainSnap;
IAppCache elementsCache;
// Here we are reading/writing to shared objects so we need to lock (can't be _storesLock which manages the actual nucache files
// and would result in a deadlock). Even though we are locking around underlying readlocks (within CreateSnapshot) it's because
// we need to ensure that the result of contentSnap.Gen (etc) and the re-assignment of these values and _elements cache
// are done atomically.
lock (_elementsLock)
{
IScopeContext scopeContext = _scopeProvider.Context;
if (scopeContext == null)
{
contentSnap = _contentStore.CreateSnapshot();
mediaSnap = _mediaStore.CreateSnapshot();
domainSnap = _domainStore.CreateSnapshot();
elementsCache = _elementsCache;
}
else
{
contentSnap = _contentStore.LiveSnapshot;
mediaSnap = _mediaStore.LiveSnapshot;
domainSnap = _domainStore.Test.LiveSnapshot;
elementsCache = _elementsCache;
// this is tricky
// we are returning elements composed from live snapshots, which we need to replace
// with actual snapshots when the context is gone - but when the action runs, there
// still is a context - so we cannot get elements - just resync = nulls the current
// elements
// just need to make sure nothing gets elements in another enlisted action... so using
// a MaxValue to make sure this one runs last, and it should be ok
scopeContext.Enlist("Umbraco.Web.PublishedCache.NuCache.PublishedSnapshotService.Resync", () => this, (completed, svc) =>
{
svc.CurrentPublishedSnapshot?.Resync();
}, int.MaxValue);
}
// create a new snapshot cache if snapshots are different gens
if (contentSnap.Gen != _contentGen || mediaSnap.Gen != _mediaGen || domainSnap.Gen != _domainGen || _elementsCache == null)
{
_contentGen = contentSnap.Gen;
_mediaGen = mediaSnap.Gen;
_domainGen = domainSnap.Gen;
elementsCache = _elementsCache = new FastDictionaryAppCache();
}
}
var snapshotCache = new DictionaryAppCache();
var memberTypeCache = new PublishedContentTypeCache(null, null, _serviceContext.MemberTypeService, _publishedContentTypeFactory, _loggerFactory.CreateLogger <PublishedContentTypeCache>());
var defaultCulture = _defaultCultureAccessor.DefaultCulture;
var domainCache = new DomainCache(domainSnap, defaultCulture);
return(new PublishedSnapshot.PublishedSnapshotElements
{
ContentCache = new ContentCache(previewDefault, contentSnap, snapshotCache, elementsCache, domainCache, Options.Create(_globalSettings), _variationContextAccessor),
MediaCache = new MediaCache(previewDefault, mediaSnap, _variationContextAccessor),
MemberCache = new MemberCache(previewDefault, memberTypeCache, _publishedSnapshotAccessor, _variationContextAccessor, _publishedModelFactory),
DomainCache = domainCache,
SnapshotCache = snapshotCache,
ElementsCache = elementsCache
});
}
