[feature] Storage events

src/Neo/Persistence/DataCache.cs

@@ -42,9 +42,20 @@ public class Trackable(StorageItem item, TrackState state)
             public TrackState State { get; set; } = state;
         }
 
+        /// <summary>
+        /// Delegate for storage entries
+        /// </summary>
+        /// <param name="sender">DataCache</param>
+        /// <param name="key">Key</param>
+        /// <param name="item">Item</param>
+        public delegate void OnEntryDelegate(DataCache sender, StorageKey key, StorageItem item);
+
         private readonly Dictionary<StorageKey, Trackable> _dictionary = [];
         private readonly HashSet<StorageKey>? _changeSet;
 
+        public event OnEntryDelegate? OnRead;
+        public event OnEntryDelegate? OnUpdate;
+
         /// <summary>
         /// True if DataCache is readOnly
         /// </summary>
@@ -145,7 +156,7 @@ public virtual void Commit()
                             trackable.State = TrackState.None;
                             break;
                         case TrackState.Changed:
-                            UpdateInternal(key, trackable.Item);
+                            UpdateInternalWrapper(key, trackable.Item);
                             trackable.State = TrackState.None;
                             break;
                         case TrackState.Deleted:
@@ -218,7 +229,7 @@ public void Delete(StorageKey key)
                 }
                 else
                 {
-                    var item = TryGetInternal(key);
+                    var item = TryGetInternalWrapper(key);
                     if (item == null) return;
                     _dictionary.Add(key, new Trackable(item, TrackState.Deleted));
                     _changeSet?.Add(key);
@@ -390,7 +401,7 @@ public bool Contains(StorageKey key)
                 }
                 else
                 {
-                    var item = TryGetInternal(key);
+                    var item = TryGetInternalWrapper(key);
                     if (item == null)
                     {
                         if (factory == null) return null;
@@ -407,6 +418,21 @@ public bool Contains(StorageKey key)
             }
         }
 
+        private StorageItem? TryGetInternalWrapper(StorageKey key)
+        {
+            var item = TryGetInternal(key);
+            if (item == null) return null;
+
+            OnRead?.Invoke(this, key, item);
+            return item;
+        }
+
+        private void UpdateInternalWrapper(StorageKey key, StorageItem value)
+        {
+            UpdateInternal(key, value);
+            OnUpdate?.Invoke(this, key, value);
+        }
+
         /// <summary>
         /// Reads a specified entry from the cache.
         /// If the entry is not in the cache, it will be automatically loaded from the underlying storage.
@@ -440,7 +466,7 @@ public StorageItem GetOrAdd(StorageKey key, Func<StorageItem> factory)
                 }
                 else
                 {
-                    var item = TryGetInternal(key);
+                    var item = TryGetInternalWrapper(key);
                     if (item == null)
                     {
                         trackable = new Trackable(factory(), TrackState.Added);
@@ -538,7 +564,7 @@ public StorageItem GetOrAdd(StorageKey key, Func<StorageItem> factory)
                         return null;
                     return trackable.Item;
                 }
-                var value = TryGetInternal(key);
+                var value = TryGetInternalWrapper(key);
                 if (value == null) return null;
                 _dictionary.Add(key, new Trackable(value, TrackState.None));
                 return value;

src/Neo/Persistence/IStore.cs

@@ -23,6 +23,18 @@ public interface IStore :
         IWriteStore<byte[], byte[]>,
         IDisposable
     {
+        /// <summary>
+        /// Delegate for OnNewSnapshot
+        /// </summary>
+        /// <param name="sender">Store</param>
+        /// <param name="snapshot">Snapshot</param>
+        public delegate void OnNewSnapshotDelegate(IStore sender, IStoreSnapshot snapshot);
+
+        /// <summary>
+        /// Event raised when a new snapshot is created
+        /// </summary>
+        public event OnNewSnapshotDelegate? OnNewSnapshot;
+
         /// <summary>
         /// Creates a snapshot of the database.
         /// </summary>

src/Neo/Persistence/Providers/MemoryStore.cs

@@ -27,6 +27,9 @@ public class MemoryStore : IStore
     {
         private readonly ConcurrentDictionary<byte[], byte[]> _innerData = new(ByteArrayEqualityComparer.Default);
 
+        /// <inheritdoc/>
+        public event IStore.OnNewSnapshotDelegate? OnNewSnapshot;
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public void Delete(byte[] key)
         {
@@ -38,7 +41,9 @@ public void Dispose() { }
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public IStoreSnapshot GetSnapshot()
         {
-            return new MemorySnapshot(this, _innerData);
+            var snapshot = new MemorySnapshot(this, _innerData);
+            OnNewSnapshot?.Invoke(this, snapshot);
+            return snapshot;
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]

src/Plugins/LevelDBStore/Plugins/Storage/Store.cs

@@ -25,6 +25,9 @@ internal class Store : IStore, IEnumerable<KeyValuePair<byte[], byte[]>>
         private readonly DB _db;
         private readonly Options _options;
 
+        /// <inheritdoc/>
+        public event IStore.OnNewSnapshotDelegate? OnNewSnapshot;
+
         public Store(string path)
         {
             _options = new Options
@@ -47,8 +50,12 @@ public void Dispose()
             _options.Dispose();
         }
 
-        public IStoreSnapshot GetSnapshot() =>
-            new Snapshot(this, _db);
+        public IStoreSnapshot GetSnapshot()
+        {
+            var snapshot = new Snapshot(this, _db);
+            OnNewSnapshot?.Invoke(this, snapshot);
+            return snapshot;
+        }
 
         public void Put(byte[] key, byte[] value) =>
             _db.Put(WriteOptions.Default, key, value);

src/Plugins/RocksDBStore/Plugins/Storage/Store.cs

@@ -22,6 +22,9 @@ internal class Store : IStore
     {
         private readonly RocksDb _db;
 
+        /// <inheritdoc/>
+        public event IStore.OnNewSnapshotDelegate? OnNewSnapshot;
+
         public Store(string path)
         {
             _db = RocksDb.Open(Options.Default, Path.GetFullPath(path));
@@ -34,7 +37,9 @@ public void Dispose()
 
         public IStoreSnapshot GetSnapshot()
         {
-            return new Snapshot(this, _db);
+            var snapshot = new Snapshot(this, _db);
+            OnNewSnapshot?.Invoke(this, snapshot);
+            return snapshot;
         }
 
         /// <inheritdoc/>