LibraryManager.cs Memory Cache

[TrueCodePoet]

As mentioned, I pulled the Source code down.  I am still running v 10.10 so this is the .Net 8 build.  The LibraryManager.cs code is basically the same.

The subtle changes I have made are simple as a proof of concept.  Adding a TTL to the Cache in LibraryManager.

here is my implementation : 

Code:

        private const string ShortcutFileExtension = ".mblink";
        private static readonly TimeSpan DefaultTTL = TimeSpan.FromHours(2);
        private static readonly TimeSpan CleanupInterval = TimeSpan.FromHours(1);
        private readonly Timer _cleanupTimer;

Added this to the constructor:

Code:

            _cache = new ConcurrentDictionary<Guid, CacheEntry>();
            _cleanupTimer = new Timer(state => PurgeExpiredEntries(), null, CleanupInterval, CleanupInterval);

Change the model being stored in Cach to :

Code:

        private class CacheEntry
        {
            public CacheEntry(BaseItem item, DateTime expiration)
            {
                Item = item;
                Expiration = expiration;
            }
            public BaseItem Item { get; set; }
            public DateTime Expiration { get; set; }
        }

Added a Cleanup to purge Expired entries :

Code:

        private void PurgeExpiredEntries()
        {
            var purgeCount = 0;
            foreach (var kv in _cache)
            {
                if (kv.Value.Expiration <= DateTime.UtcNow)
                {
                    _cache.TryRemove(kv.Key, out _);
                    purgeCount++;
                }
            }
            _lastCleanup = DateTime.UtcNow;
            _logger.LogInformation("Purged {Count} expired entries from the library cache", purgeCount);
            _logger.LogInformation("Library cache contains {Count} entries", _cache.Count);

        }

An example use for get item : 

Code:

        
public BaseItem? GetItemById(Guid id)
        {
            if (id.IsEmpty())
            {
                throw new ArgumentException("Guid can't be empty", nameof(id));
            }
            if (_cache.TryGetValue(id, out var entry))
            {
                if (entry.Expiration <= DateTime.UtcNow)
                {
                    _cache.TryRemove(id, out _);
                }
                else
                {
                    if ((DateTime.UtcNow - _lastCleanup) > CleanupInterval)
                    {
                        PurgeExpiredEntries();
                    }
                    return entry.Item;
                }
            }
            var item = RetrieveItem(id);
            if (item is not null)
            {
                RegisterItem(item);
            }
            return item;
        }

I have also added some general logging in areas I felt needed a little boost.

So far my server is staying under 1 gig of ram.  but I am going to let it keep running.  I watch it bump when scans run and then settle back down a couple hours later.  I have noticed no real performance issues as I thought it could take a small hit.  But if you are using it.  then the cache is saturated.  If anything I think the overall performance is better especially on my resource starved backup server.

I will keep you updated as we could have other areas that could use a bump.