Persistant cache abstraction and runtime loading

1 files changed, 79 insertions, 0 deletions

diff --git a/lib/VNLib.Data.Caching.ObjectCache/src/IPersistantCacheStore.cs b/lib/VNLib.Data.Caching.ObjectCache/src/IPersistantCacheStore.cs
new file mode 100644
index 0000000..40f39f2
--- /dev/null
+++ b/lib/VNLib.Data.Caching.ObjectCache/src/IPersistantCacheStore.cs
@@ -0,0 +1,79 @@
+/*
+* Copyright (c) 2023 Vaughn Nugent
+* 
+* Library: VNLib
+* Package: VNLib.Data.Caching.ObjectCache
+* File: IPersistantCacheStore.cs 
+*
+* IPersistantCacheStore.cs is part of VNLib.Data.Caching.ObjectCache which 
+* is part of the larger VNLib collection of libraries and utilities.
+*
+* VNLib.Data.Caching.ObjectCache is free software: you can redistribute it and/or modify 
+* it under the terms of the GNU Affero General Public License as 
+* published by the Free Software Foundation, either version 3 of the
+* License, or (at your option) any later version.
+*
+* VNLib.Data.Caching.ObjectCache is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+* GNU Affero General Public License for more details.
+*
+* You should have received a copy of the GNU Affero General Public License
+* along with this program.  If not, see https://www.gnu.org/licenses/.
+*/
+
+using System;
+
+namespace VNLib.Data.Caching.ObjectCache
+{
+    /// <summary>
+    /// Provides a persitance layer to memory caching.
+    /// </summary>
+    public interface IPersistantCacheStore : IDisposable
+    {
+        /// <summary>
+        /// Invoked when an entry has been evicted from main-memory cache
+        /// and is expected to be stored in a "persistant" storage solution.
+        /// <para>
+        /// When this method returns, the <paramref name="entry"/> is no longer valid.
+        /// </para>
+        /// <para>
+        /// This method is called while the bucket lock is held. This call is maded
+        /// during an <see cref="IBlobCache.Add(string, CacheEntry)"/> method call.
+        /// </para>
+        /// </summary>
+        /// <param name="bucketId">The id of the bucket requesting the operation</param>
+        /// <param name="key">The key identifying the the entry</param>
+        /// <param name="entry">The entry containing the object data to store</param>
+        void OnEntryEvicted(uint bucketId, string key, in CacheEntry entry);
+
+        /// <summary>
+        /// Called when a cache item does not exist in main memory cache and should
+        /// be promoted from persistant cache to main memory cache.
+        /// <para>
+        /// This method is called while the bucket lock is held. This call is maded
+        /// during an <see cref="IBlobCache.Add(string, CacheEntry)"/> method call.
+        /// </para>
+        /// <para>
+        /// The <see cref="IMemoryCacheEntryFactory"/> should be used to create the 
+        /// cache entry for the return value. Once this method returns, the caller owns the new <see cref="CacheEntry"/>
+        /// </para>
+        /// </summary>
+        /// <param name="key">The key identifying the entry to promot</param>
+        /// <param name="factory">The cache entry factory</param>
+        /// <param name="bucketId">The id of the bucket requesting the operation</param>
+        /// <param name="entry">The newly created entry when data is found</param>
+        /// <returns>
+        /// A value inidcating if the entry was successfully recovered from the persistant storage and 
+        /// was successfully promoted.
+        /// </returns>
+        bool OnCacheMiss(uint bucketId, string key, IMemoryCacheEntryFactory factory, out CacheEntry entry);
+
+        /// <summary>
+        /// Removes an entry from the backing store
+        /// </summary>
+        /// <param name="key">The key identifying the entry to remove</param>
+        /// <param name="bucketId">The id of the bucket requesting the operation</param>
+        void OnEntryDeleted(uint bucketId, string key);
+    }
+}