Thread-bezpieczne biblioteki pamięci podręcznej for.NET

Znam twój ból, ponieważ jestem jednym z architektów Dedoose . Namieszałem w wielu bibliotekach buforujących i skończyłem z budowaniem tej Po wielu uciskach. Jedynym założeniem dla tego Menedżera pamięci podręcznej jest to, że wszystkie kolekcje przechowywane przez tę klasę implementują interfejs, aby uzyskać GUID jako właściwość " Id " na każdym obiekcie. Ponieważ jest to dla RIA, zawiera wiele metod dodawania /aktualizowania / usuwania elementów z tych kolekcji.

Oto mój CollectionCacheManager

public class CollectionCacheManager
{
    private static readonly object _objLockPeek = new object();
    private static readonly Dictionary<String, object> _htLocksByKey = new Dictionary<string, object>();
    private static readonly Dictionary<String, CollectionCacheEntry> _htCollectionCache = new Dictionary<string, CollectionCacheEntry>();

    private static DateTime _dtLastPurgeCheck;

    public static List<T> FetchAndCache<T>(string sKey, Func<List<T>> fGetCollectionDelegate) where T : IUniqueIdActiveRecord
    {
        List<T> colItems = new List<T>();

        lock (GetKeyLock(sKey))
        {
            if (_htCollectionCache.Keys.Contains(sKey) == true)
            {
                CollectionCacheEntry objCacheEntry = _htCollectionCache[sKey];
                colItems = (List<T>) objCacheEntry.Collection;
                objCacheEntry.LastAccess = DateTime.Now;
            }
            else
            {
                colItems = fGetCollectionDelegate();
                SaveCollection<T>(sKey, colItems);
            }
        }

        List<T> objReturnCollection = CloneCollection<T>(colItems);
        return objReturnCollection;
    }

    public static List<Guid> FetchAndCache(string sKey, Func<List<Guid>> fGetCollectionDelegate)
    {
        List<Guid> colIds = new List<Guid>();

        lock (GetKeyLock(sKey))
        {
            if (_htCollectionCache.Keys.Contains(sKey) == true)
            {
                CollectionCacheEntry objCacheEntry = _htCollectionCache[sKey];
                colIds = (List<Guid>)objCacheEntry.Collection;
                objCacheEntry.LastAccess = DateTime.Now;
            }
            else
            {
                colIds = fGetCollectionDelegate();
                SaveCollection(sKey, colIds);
            }
        }

        List<Guid> colReturnIds = CloneCollection(colIds);
        return colReturnIds;
    }


    private static List<T> GetCollection<T>(string sKey) where T : IUniqueIdActiveRecord
    {
        List<T> objReturnCollection = null;

        if (_htCollectionCache.Keys.Contains(sKey) == true)
        {
            CollectionCacheEntry objCacheEntry = null;

            lock (GetKeyLock(sKey))
            {
                objCacheEntry = _htCollectionCache[sKey];
                objCacheEntry.LastAccess = DateTime.Now;
            }

            if (objCacheEntry.Collection != null && objCacheEntry.Collection is List<T>)
            {
                objReturnCollection = CloneCollection<T>((List<T>)objCacheEntry.Collection);
            }
        }

        return objReturnCollection;
    }


    public static void SaveCollection<T>(string sKey, List<T> colItems) where T : IUniqueIdActiveRecord
    {

        CollectionCacheEntry objCacheEntry = new CollectionCacheEntry();

        objCacheEntry.Key = sKey;
        objCacheEntry.CacheEntry = DateTime.Now;
        objCacheEntry.LastAccess = DateTime.Now;
        objCacheEntry.LastUpdate = DateTime.Now;
        objCacheEntry.Collection = CloneCollection(colItems);

        lock (GetKeyLock(sKey))
        {
            _htCollectionCache[sKey] = objCacheEntry;
        }
    }

    public static void SaveCollection(string sKey, List<Guid> colIDs)
    {

        CollectionCacheEntry objCacheEntry = new CollectionCacheEntry();

        objCacheEntry.Key = sKey;
        objCacheEntry.CacheEntry = DateTime.Now;
        objCacheEntry.LastAccess = DateTime.Now;
        objCacheEntry.LastUpdate = DateTime.Now;
        objCacheEntry.Collection = CloneCollection(colIDs);

        lock (GetKeyLock(sKey))
        {
            _htCollectionCache[sKey] = objCacheEntry;
        }
    }

    public static void UpdateCollection<T>(string sKey, List<T> colItems) where T : IUniqueIdActiveRecord
    {
        lock (GetKeyLock(sKey))
        {
            if (_htCollectionCache.ContainsKey(sKey) == true)
            {
                CollectionCacheEntry objCacheEntry = _htCollectionCache[sKey];
                objCacheEntry.LastAccess = DateTime.Now;
                objCacheEntry.LastUpdate = DateTime.Now;
                objCacheEntry.Collection = new List<T>();

                //Clone the collection before insertion to ensure it can't be touched
                foreach (T objItem in colItems)
                {
                    objCacheEntry.Collection.Add(objItem);
                }

                _htCollectionCache[sKey] = objCacheEntry;
            }
            else
            {
                SaveCollection<T>(sKey, colItems);
            }
        }
    }

    public static void UpdateItem<T>(string sKey, T objItem)  where T : IUniqueIdActiveRecord
    {
        lock (GetKeyLock(sKey))
        {
            if (_htCollectionCache.ContainsKey(sKey) == true)
            {
                CollectionCacheEntry objCacheEntry = _htCollectionCache[sKey];
                List<T> colItems = (List<T>)objCacheEntry.Collection;

                colItems.RemoveAll(o => o.Id == objItem.Id);
                colItems.Add(objItem);

                objCacheEntry.Collection = colItems;

                objCacheEntry.LastAccess = DateTime.Now;
                objCacheEntry.LastUpdate = DateTime.Now;
            }
        }
    }

    public static void UpdateItems<T>(string sKey, List<T> colItemsToUpdate) where T : IUniqueIdActiveRecord
    {
        lock (GetKeyLock(sKey))
        {
            if (_htCollectionCache.ContainsKey(sKey) == true)
            {
                CollectionCacheEntry objCacheEntry = _htCollectionCache[sKey];
                List<T> colCachedItems = (List<T>)objCacheEntry.Collection;

                foreach (T objItem in colItemsToUpdate)
                {
                    colCachedItems.RemoveAll(o => o.Id == objItem.Id);
                    colCachedItems.Add(objItem);
                }

                objCacheEntry.Collection = colCachedItems;

                objCacheEntry.LastAccess = DateTime.Now;
                objCacheEntry.LastUpdate = DateTime.Now;
            }
        }
    }

    public static void RemoveItemFromCollection<T>(string sKey, T objItem) where T : IUniqueIdActiveRecord
    {
        lock (GetKeyLock(sKey))
        {
            List<T> objCollection = GetCollection<T>(sKey);
            if (objCollection != null && objCollection.Count(o => o.Id == objItem.Id) > 0)
            {
                objCollection.RemoveAll(o => o.Id == objItem.Id);
                UpdateCollection<T>(sKey, objCollection);
            }
        }
    }

    public static void RemoveItemsFromCollection<T>(string sKey, List<T> colItemsToAdd) where T : IUniqueIdActiveRecord
    {
        lock (GetKeyLock(sKey))
        {
            Boolean bCollectionChanged = false;

            List<T> objCollection = GetCollection<T>(sKey);
            foreach (T objItem in colItemsToAdd)
            {
                if (objCollection != null && objCollection.Count(o => o.Id == objItem.Id) > 0)
                {
                    objCollection.RemoveAll(o => o.Id == objItem.Id);
                    bCollectionChanged = true;
                }
            }
            if (bCollectionChanged == true)
            {
                UpdateCollection<T>(sKey, objCollection);
            }
        }
    }

    public static void AddItemToCollection<T>(string sKey, T objItem) where T : IUniqueIdActiveRecord
    {
        lock (GetKeyLock(sKey))
        {
            List<T> objCollection = GetCollection<T>(sKey);
            if (objCollection != null && objCollection.Count(o => o.Id == objItem.Id) == 0)
            {
                objCollection.Add(objItem);
                UpdateCollection<T>(sKey, objCollection);
            }
        }
    }

    public static void AddItemsToCollection<T>(string sKey, List<T> colItemsToAdd) where T : IUniqueIdActiveRecord
    {
        lock (GetKeyLock(sKey))
        {
            List<T> objCollection = GetCollection<T>(sKey);
            Boolean bCollectionChanged = false;
            foreach (T objItem in colItemsToAdd)
            {
                if (objCollection != null && objCollection.Count(o => o.Id == objItem.Id) == 0)
                {
                    objCollection.Add(objItem);
                    bCollectionChanged = true;
                }
            }
            if (bCollectionChanged == true)
            {
                UpdateCollection<T>(sKey, objCollection);
            }
        }
    }

    public static void PurgeCollectionByMaxLastAccessInMinutes(int iMinutesSinceLastAccess)
    {
        DateTime dtThreshHold = DateTime.Now.AddMinutes(iMinutesSinceLastAccess * -1);

        if (_dtLastPurgeCheck == null || dtThreshHold > _dtLastPurgeCheck)
        {

            lock (_objLockPeek)
            {
                CollectionCacheEntry objCacheEntry;
                List<String> colKeysToRemove = new List<string>();

                foreach (string sCollectionKey in _htCollectionCache.Keys)
                {
                    objCacheEntry = _htCollectionCache[sCollectionKey];
                    if (objCacheEntry.LastAccess < dtThreshHold)
                    {
                        colKeysToRemove.Add(sCollectionKey);
                    }
                }

                foreach (String sKeyToRemove in colKeysToRemove)
                {
                    _htCollectionCache.Remove(sKeyToRemove);
                }
            }

            _dtLastPurgeCheck = DateTime.Now;
        }
    }

    public static void ClearCollection(String sKey)
    {
        lock (GetKeyLock(sKey))
        {
            lock (_objLockPeek)
            {
                if (_htCollectionCache.ContainsKey(sKey) == true)
                {
                    _htCollectionCache.Remove(sKey);
                }
            }
        }
    }


    #region Helper Methods
    private static object GetKeyLock(String sKey)
    {
        //Ensure even if hell freezes over this lock exists
        if (_htLocksByKey.Keys.Contains(sKey) == false)
        {
            lock (_objLockPeek)
            {
                if (_htLocksByKey.Keys.Contains(sKey) == false)
                {
                    _htLocksByKey[sKey] = new object();
                }
            }
        }

        return _htLocksByKey[sKey];
    }

    private static List<T> CloneCollection<T>(List<T> colItems) where T : IUniqueIdActiveRecord
    {
        List<T> objReturnCollection = new List<T>();
        //Clone the list - NEVER return the internal cache list
        if (colItems != null && colItems.Count > 0)
        {
            List<T> colCachedItems = (List<T>)colItems;
            foreach (T objItem in colCachedItems)
            {
                objReturnCollection.Add(objItem);
            }
        }
        return objReturnCollection;
    }

    private static List<Guid> CloneCollection(List<Guid> colIds)
    {
        List<Guid> colReturnIds = new List<Guid>();
        //Clone the list - NEVER return the internal cache list
        if (colIds != null && colIds.Count > 0)
        {
            List<Guid> colCachedItems = (List<Guid>)colIds;
            foreach (Guid gId in colCachedItems)
            {
                colReturnIds.Add(gId);
            }
        }
        return colReturnIds;
    } 
    #endregion

    #region Admin Functions
    public static List<CollectionCacheEntry> GetAllCacheEntries()
    {
        return _htCollectionCache.Values.ToList();
    }

    public static void ClearEntireCache()
    {
        _htCollectionCache.Clear();
    }
    #endregion

}

public sealed class CollectionCacheEntry
{
    public String Key;
    public DateTime CacheEntry;
    public DateTime LastUpdate;
    public DateTime LastAccess;
    public IList Collection;
}

Oto przykład jak go używam:

public static class ResourceCacheController
{
    #region Cached Methods
    public static List<Resource> GetResourcesByProject(Guid gProjectId)
    {
        String sKey = GetCacheKeyProjectResources(gProjectId);
        List<Resource> colItems = CollectionCacheManager.FetchAndCache<Resource>(sKey, delegate() { return ResourceAccess.GetResourcesByProject(gProjectId); });
        return colItems;
    } 

    #endregion

    #region Cache Dependant Methods
    public static int GetResourceCountByProject(Guid gProjectId)
    {
        return GetResourcesByProject(gProjectId).Count;
    }

    public static List<Resource> GetResourcesByIds(Guid gProjectId, List<Guid> colResourceIds)
    {
        if (colResourceIds == null || colResourceIds.Count == 0)
        {
            return null;
        }
        return GetResourcesByProject(gProjectId).FindAll(objRes => colResourceIds.Any(gId => objRes.Id == gId)).ToList();
    }

    public static Resource GetResourceById(Guid gProjectId, Guid gResourceId)
    {
        return GetResourcesByProject(gProjectId).SingleOrDefault(o => o.Id == gResourceId);
    }
    #endregion

    #region Cache Keys and Clear
    public static void ClearCacheProjectResources(Guid gProjectId)
    {            CollectionCacheManager.ClearCollection(GetCacheKeyProjectResources(gProjectId));
    }

    public static string GetCacheKeyProjectResources(Guid gProjectId)
    {
        return string.Concat("ResourceCacheController.ProjectResources.", gProjectId.ToString());
    } 
    #endregion

    internal static void ProcessDeleteResource(Guid gProjectId, Guid gResourceId)
    {
        Resource objRes = GetResourceById(gProjectId, gResourceId);
        if (objRes != null)
        {                CollectionCacheManager.RemoveItemFromCollection(GetCacheKeyProjectResources(gProjectId), objRes);
        }
    }

    internal static void ProcessUpdateResource(Resource objResource)
    {
        CollectionCacheManager.UpdateItem(GetCacheKeyProjectResources(objResource.Id), objResource);
    }

    internal static void ProcessAddResource(Guid gProjectId, Resource objResource)
    {
        CollectionCacheManager.AddItemToCollection(GetCacheKeyProjectResources(gProjectId), objResource);
    }
}

Oto interfejs, o którym mowa:

public interface IUniqueIdActiveRecord
{
    Guid Id { get; set; }

}

Mam nadzieję, że to pomoże, przeszedłem przez piekło i z powrotem kilka razy, aby w końcu dojść do tego jako rozwiązania, i dla nas było to darem niebios, ale nie mogę zagwarantować, że jest idealny, tylko, że nie znaleźliśmy jeszcze problemu.