public bool TryAddItem(MediaItem item, IRelationshipRoleExtractor itemMatcher)
{
ICollection <string> identifiers = itemMatcher.GetExternalIdentifiers(item.Aspects);
//We can only cache using external identifiers
if (identifiers == null || identifiers.Count == 0)
{
return(false);
}
//Lazily created below
CacheItem cacheItem = null;
foreach (string identifier in identifiers)
{
IList <CacheItem> cacheList;
if (!_cache.TryGetValue(identifier, out cacheList))
{
//Identifier has never been cached, add it
cacheList = new List <CacheItem>();
_cache.Add(identifier, cacheList);
}
else if (cacheList.Any(c => c.Id == item.MediaItemId))
{
//Already cached under this identifier
continue;
}
//Create the cache item if not already created.
//Only the minimum number of aspects required by the itemMatcher
//will be cached to avoid caching large thumbnails, etc
if (cacheItem == null)
{
cacheItem = CreateCacheItem(item, itemMatcher);
}
cacheList.Add(cacheItem);
}
if (cacheItem == null)
{
return(false);
}
//Item was added, add it to the cache history
_cacheHistory.Add(item.MediaItemId);
return(true);
}
public bool TryGetItemId(IDictionary <Guid, IList <MediaItemAspect> > aspects, IRelationshipRoleExtractor itemMatcher, out Guid mediaItemId)
{
mediaItemId = Guid.Empty;
ICollection <string> identifiers = itemMatcher.GetExternalIdentifiers(aspects);
//We can only match using external identifiers
if (identifiers == null || identifiers.Count == 0)
{
return(false);
}
//All items that have been checked under the identifiers but didn't match
ICollection <Guid> checkedIds = new HashSet <Guid>();
foreach (string identifier in identifiers)
{
IList <CacheItem> cacheList;
//Is the identifier in the cache?
if (!_cache.TryGetValue(identifier, out cacheList))
{
continue;
}
//Multiple media items can be cached under the same external identifier, we need
//to delegate the actual matching to the itemMatcher
foreach (CacheItem item in cacheList)
{
//The same media items can appear under each identifier, don't bother checking
//any items that we've already checked.
if (checkedIds.Contains(item.Id))
{
continue;
}
if (itemMatcher.TryMatch(aspects, item.Aspects))
{
mediaItemId = item.Id;
return(true);
}
//Store this unmatching id so it's not checked again
checkedIds.Add(item.Id);
}
}
return(false);
}
