WIP Convert EntityKey to struct

build-common/NHibernate.props

@@ -14,6 +14,7 @@
 
     <NhAppTargetFrameworks Condition ="$(NhAppTargetFrameworks) == ''">net461;netcoreapp2.0</NhAppTargetFrameworks>
     <NhLibTargetFrameworks Condition ="$(NhLibTargetFrameworks) == ''">net461;netcoreapp2.0;netstandard2.0</NhLibTargetFrameworks>
+    <LangVersion>7.3</LangVersion>
 
     <Product>NHibernate</Product>
     <Company>NHibernate.info</Company>

src/NHibernate.Test.VisualBasic/NHibernate.Test.VisualBasic.vbproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <Import Project="../../build-common/NHibernate.props" />
   <PropertyGroup>
+    <LangVersion/>
     <Description>The Visual Basic Unit Tests for NHibernate.</Description>
     <TargetFrameworks>$(NhAppTargetFrameworks)</TargetFrameworks>
     <IsTestProject>true</IsTestProject>

src/NHibernate/Action/EntityIdentityInsertAction.cs

@@ -19,7 +19,7 @@ public EntityIdentityInsertAction(object[] state, object instance, IEntityPersis
 			: base(null, state, instance, persister, session)
 		{
 			this.isDelayed = isDelayed;
-			delayedEntityKey = this.isDelayed ? GenerateDelayedEntityKey() : null;
+			delayedEntityKey = this.isDelayed ? GenerateDelayedEntityKey() : EntityKey.Empty;
 		}
 
 		public object GeneratedId

src/NHibernate/Async/Event/Default/AbstractSaveEventListener.cs

@@ -150,7 +150,7 @@ protected virtual async Task<object> PerformSaveAsync(object entity, object id,
 			}
 			else
 			{
-				key = null;
+				key = EntityKey.Empty;
 			}
 
 			if (InvokeSaveLifecycle(entity, persister, source))
@@ -184,7 +184,7 @@ protected virtual async Task<object> PerformSaveOrReplicateAsync(object entity,
 			cancellationToken.ThrowIfCancellationRequested();
 			Validate(entity, persister, source);
 
-			object id = key == null ? null : key.Identifier;
+			object id = key.IsEmpty ? null : key.Identifier;
 
 			bool shouldDelayIdentityInserts = !requiresImmediateIdAccess;
 

src/NHibernate/Async/Event/Default/DefaultReplicateEventListener.cs

@@ -102,7 +102,7 @@ public virtual async Task OnReplicateAsync(ReplicateEvent @event, CancellationTo
 				}
 
 				bool regenerate = persister.IsIdentifierAssignedByInsert; // prefer re-generation of identity!
-				EntityKey key = regenerate ? null : source.GenerateEntityKey(id, persister);
+				EntityKey key = regenerate ? EntityKey.Empty : source.GenerateEntityKey(id, persister);
 
 				await (PerformSaveOrReplicateAsync(entity, key, persister, regenerate, replicationMode, source, true, cancellationToken)).ConfigureAwait(false);
 			}

src/NHibernate/Async/Impl/MultiCriteriaImpl.cs

@@ -185,7 +185,7 @@ private async Task GetResultsFromDatabaseAsync(IList results, CancellationToken
 
 							object o =
 								await (loader.GetRowFromResultSetAsync(reader, session, queryParameters, loader.GetLockModes(queryParameters.LockModes),
-																					 null, hydratedObjects[i], keys, true,
+																					 EntityKey.Empty, hydratedObjects[i], keys, true,
 																					(persister, data) => cacheBatcher.AddToBatch(persister, data), cancellationToken)).ConfigureAwait(false);
 							if (createSubselects[i])
 							{

src/NHibernate/Async/Loader/Loader.cs

@@ -118,7 +118,7 @@ protected async Task<object> LoadSingleRowAsync(DbDataReader resultSet, ISession
 			try
 			{
 				result =
-					await (GetRowFromResultSetAsync(resultSet, session, queryParameters, GetLockModes(queryParameters.LockModes), null,
+					await (GetRowFromResultSetAsync(resultSet, session, queryParameters, GetLockModes(queryParameters.LockModes), EntityKey.Empty,
 										hydratedObjects, new EntityKey[entitySpan], returnProxies, (persister, data) => cacheBatcher.AddToBatch(persister, data), cancellationToken)).ConfigureAwait(false);
 			}
 			catch (OperationCanceledException) { throw; }
@@ -185,7 +185,7 @@ internal async Task<object> GetRowFromResultSetAsync(DbDataReader resultSet, ISe
 				{
 					object entity = row[i];
 					var key = keys[i];
-					if (entity == null && key != null && IsChildFetchEntity(i))
+					if (entity == null && key.IsNotEmpty && IsChildFetchEntity(i))
 					{
 						// The entity was missing in the session, fallback on internal load (which will just yield a
 						// proxy if the persister supports it).
@@ -564,7 +564,7 @@ private async Task<EntityKey> GetKeyFromResultSetAsync(int i, IEntityPersister p
 				}
 			}
 
-			return resultId == null ? null : session.GenerateEntityKey(resultId, persister);
+			return resultId == null ? EntityKey.Empty : session.GenerateEntityKey(resultId, persister);
 		}
 
 		/// <summary>
@@ -620,7 +620,7 @@ private async Task<object[]> GetRowAsync(DbDataReader rs, ILoadable[] persisters
 				object obj = null;
 				EntityKey key = keys[i];
 
-				if (key == null)
+				if (key.IsEmpty)
 				{
 					// do nothing
 					/* TODO NH-1001 : if (persisters[i]...EntityType) is an OneToMany or a ManyToOne and
@@ -756,7 +756,7 @@ private async Task<object> InstanceNotYetLoadedAsync(DbDataReader dr, int i, ILo
 
 			string instanceClass = await (GetInstanceClassAsync(dr, i, persister, key.Identifier, session, cancellationToken)).ConfigureAwait(false);
 
-			if (optionalObjectKey != null && key.Equals(optionalObjectKey))
+			if (optionalObjectKey.IsNotEmpty && key.Equals(optionalObjectKey))
 			{
 				// its the given optional object
 				obj = optionalObject;

src/NHibernate/Engine/BatchFetchQueue.cs

@@ -61,7 +61,7 @@ public void Clear()
 		/// <param name="key">The entity key for which to locate any defined subselect fetch.</param>
 		/// <returns>The fetch descriptor; may return null if no subselect fetch queued for
 		/// this entity key.</returns>
-		public SubselectFetch GetSubselect(EntityKey key)
+		public SubselectFetch GetSubselect(in EntityKey key)
 		{
 			SubselectFetch result;
 			subselectsByEntityKey.TryGetValue(key, out result);
@@ -73,7 +73,7 @@ public SubselectFetch GetSubselect(EntityKey key)
 		/// </summary>
 		/// <param name="key">The entity for which to register the subselect fetch.</param>
 		/// <param name="subquery">The fetch descriptor.</param>
-		public void AddSubselect(EntityKey key, SubselectFetch subquery)
+		public void AddSubselect(in EntityKey key, SubselectFetch subquery)
 		{
 			subselectsByEntityKey[key] = subquery;
 		}
@@ -84,7 +84,7 @@ public void AddSubselect(EntityKey key, SubselectFetch subquery)
 		/// call this after loading the entity, since we might still
 		/// need to load its collections)
 		/// </summary>
-		public void RemoveSubselect(EntityKey key)
+		public void RemoveSubselect(in EntityKey key)
 		{
 			subselectsByEntityKey.Remove(key);
 		}
@@ -111,7 +111,7 @@ public void ClearSubselects()
 		/// referenced entity to be included in a batch even though it is
 		/// already associated with the <see cref="ISession" />.
 		/// </remarks>
-		public void AddBatchLoadableEntityKey(EntityKey key)
+		public void AddBatchLoadableEntityKey(in EntityKey key)
 		{
 			if (key.IsBatchLoadable)
 			{
@@ -129,7 +129,7 @@ public void AddBatchLoadableEntityKey(EntityKey key)
 		/// need to batch fetch it anymore, remove it from the queue
 		/// if necessary
 		/// </summary>
-		public void RemoveBatchLoadableEntityKey(EntityKey key)
+		public void RemoveBatchLoadableEntityKey(in EntityKey key)
 		{
 			if (key.IsBatchLoadable)
 			{

src/NHibernate/Engine/EntityEntry.cs

@@ -215,7 +215,7 @@ public EntityKey EntityKey
 		{
 			get
 			{
-				if (cachedEntityKey == null)
+				if (cachedEntityKey.IsEmpty)
 				{
 					if (id == null)
 						throw new InvalidOperationException("cannot generate an EntityKey when id is null.");

src/NHibernate/Engine/EntityKey.cs

@@ -6,14 +6,18 @@
 
 namespace NHibernate.Engine
 {
-	//TODO 6.0: Remove IDeserializationCallback interface
 	/// <summary>
 	/// A globally unique identifier of an instance, consisting of the user-visible identifier
 	/// and the identifier space (eg. tablename)
 	/// </summary>
 	[Serializable]
-	public sealed class EntityKey : IDeserializationCallback, ISerializable, IEquatable<EntityKey>
+	public readonly struct EntityKey : ISerializable, IEquatable<EntityKey>
 	{
+		public static EntityKey Empty { get; } = new EntityKey();
+
+		public bool IsEmpty => identifier == null;
+		public bool IsNotEmpty => !IsEmpty;
+
 		private readonly object identifier;
 		private readonly IEntityPersister _persister;
 		// hashcode may vary among processes, they cannot be stored and have to be re-computed after deserialization
@@ -30,8 +34,16 @@ public EntityKey(object id, IEntityPersister persister)
 		private EntityKey(SerializationInfo info, StreamingContext context)
 		{
 			identifier = info.GetValue(nameof(Identifier), typeof(object));
+			if (identifier == null)
+			{
+				_hashCode = 0;
+				_persister = null;
+				return;
+			}
+
 			var factory = (ISessionFactoryImplementor) info.GetValue(nameof(_persister.Factory), typeof(ISessionFactoryImplementor));
-			var entityName = (string) info.GetValue(nameof(EntityName), typeof(string));
+			var entityName = info.GetString(nameof(EntityName));
+
 			_persister = factory.GetEntityPersister(entityName);
 			_hashCode = GenerateHashCode(_persister, identifier);
 		}
@@ -54,10 +66,8 @@ public override bool Equals(object other)
 
 		public bool Equals(EntityKey other)
 		{
-			if (other == null)
-			{
-				return false;
-			}
+			if (other.IsEmpty)
+				return IsEmpty;
 
 			return
 				other.RootEntityName.Equals(RootEntityName)
@@ -82,19 +92,20 @@ private static int GenerateHashCode(IEntityPersister persister, object id)
 
 		public override string ToString()
 		{
-			return "EntityKey" + MessageHelper.InfoString(_persister, Identifier, _persister.Factory);
+			return IsEmpty
+				? Util.StringHelper.NullObject 
+				: "EntityKey" + MessageHelper.InfoString(_persister, Identifier, _persister?.Factory);
 		}
 
 		[SecurityCritical]
 		void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
 		{
 			info.AddValue(nameof(Identifier), identifier);
+			if (identifier == null)
+				return;
+
 			info.AddValue(nameof(_persister.Factory), _persister.Factory);
 			info.AddValue(nameof(EntityName), EntityName);
 		}
-
-		[Obsolete("IDeserializationCallback interface has no usages and will be removed in a future version")]
-		public void OnDeserialization(object sender)
-		{}
 	}
 }

src/NHibernate/Engine/IPersistenceContext.cs

@@ -113,7 +113,7 @@ public partial interface IPersistenceContext
 		/// <item><description>an entry of NO_ROW here is interpreted as an exception</description></item>
 		/// </list>
 		/// </remarks>
-		object[] GetCachedDatabaseSnapshot(EntityKey key);
+		object[] GetCachedDatabaseSnapshot(in EntityKey key);
 
 		/// <summary>
 		/// Get the values of the natural id fields as known to the underlying
@@ -123,22 +123,22 @@ public partial interface IPersistenceContext
 		object[] GetNaturalIdSnapshot(object id, IEntityPersister persister);
 
 		/// <summary> Add a canonical mapping from entity key to entity instance</summary>
-		void AddEntity(EntityKey key, object entity);
+		void AddEntity(in EntityKey key, object entity);
 
 		/// <summary>
 		/// Get the entity instance associated with the given <tt>EntityKey</tt>
 		/// </summary>
-		object GetEntity(EntityKey key);
+		object GetEntity(in EntityKey key);
 
 		/// <summary> Is there an entity with the given key in the persistence context</summary>
-		bool ContainsEntity(EntityKey key);
+		bool ContainsEntity(in EntityKey key);
 
 		/// <summary>
 		/// Remove an entity from the session cache, also clear
 		/// up other state associated with the entity, all except
 		/// for the <tt>EntityEntry</tt>
 		/// </summary>
-		object RemoveEntity(EntityKey key);
+		object RemoveEntity(in EntityKey key);
 
 		/// <summary> Get an entity cached by unique key</summary>
 		object GetEntity(EntityUniqueKey euk);
@@ -216,9 +216,9 @@ EntityEntry AddEntry(object entity, Status status, object[] loadedState, object
 		/// Attempts to check whether the given key represents an entity already loaded within the
 		/// current session.
 		/// </summary>
-		/// <param name="obj">The entity reference against which to perform the uniqueness check.</param>
 		/// <param name="key">The entity key.</param>
-		void CheckUniqueness(EntityKey key, object obj);
+		/// <param name="obj">The entity reference against which to perform the uniqueness check.</param>
+		void CheckUniqueness(in EntityKey key, object obj);
 
 		/// <summary>
 		/// If the existing proxy is insufficiently "narrow" (derived), instantiate a new proxy
@@ -231,14 +231,14 @@ EntityEntry AddEntry(object entity, Status status, object[] loadedState, object
 		/// <param name="key">The internal cache key for the proxied entity. </param>
 		/// <param name="obj">(optional) the actual proxied entity instance. </param>
 		/// <returns> An appropriately narrowed instance. </returns>
-		object NarrowProxy(INHibernateProxy proxy, IEntityPersister persister, EntityKey key, object obj);
+		object NarrowProxy(INHibernateProxy proxy, IEntityPersister persister, in EntityKey key, object obj);
 
 		/// <summary>
 		/// Return the existing proxy associated with the given <tt>EntityKey</tt>, or the
 		/// third argument (the entity associated with the key) if no proxy exists. Init
 		/// the proxy to the target implementation, if necessary.
 		/// </summary>
-		object ProxyFor(IEntityPersister persister, EntityKey key, object impl);
+		object ProxyFor(IEntityPersister persister,in EntityKey key, object impl);
 
 		/// <summary>
 		/// Return the existing proxy associated with the given <tt>EntityKey</tt>, or the
@@ -326,13 +326,13 @@ EntityEntry AddEntry(object entity, Status status, object[] loadedState, object
 		CollectionEntry GetCollectionEntryOrNull(object collection);
 
 		/// <summary> Get an existing proxy by key</summary>
-		object GetProxy(EntityKey key);
+		object GetProxy(in EntityKey key);
 
 		/// <summary> Add a proxy to the session cache</summary>
-		void AddProxy(EntityKey key, INHibernateProxy proxy);
+		void AddProxy(in EntityKey key, INHibernateProxy proxy);
 
 		/// <summary> Remove a proxy from the session cache</summary>
-		object RemoveProxy(EntityKey key);
+		object RemoveProxy(in EntityKey key);
 
 		/// <summary> Called before cascading</summary>
 		int IncrementCascadeLevel();
@@ -360,10 +360,10 @@ EntityEntry AddEntry(object entity, Status status, object[] loadedState, object
 		/// <summary>
 		/// Record the fact that the association belonging to the keyed entity is null.
 		/// </summary>
-		void AddNullProperty(EntityKey ownerKey, string propertyName);
+		void AddNullProperty(in EntityKey ownerKey, string propertyName);
 
 		/// <summary> Is the association property belonging to the keyed entity null?</summary>
-		bool IsPropertyNull(EntityKey ownerKey, string propertyName);
+		bool IsPropertyNull(in EntityKey ownerKey, string propertyName);
 
 		/// <summary>
 		/// Change the read-only status of an entity (or proxy).
@@ -398,7 +398,7 @@ EntityEntry AddEntry(object entity, Status status, object[] loadedState, object
 		/// <seealso cref="IPersistenceContext.SetReadOnly(object, bool)" />
 		bool IsReadOnly(object entityOrProxy);
 
-		void ReplaceDelayedEntityIdentityInsertKeys(EntityKey oldKey, object generatedId);
+		void ReplaceDelayedEntityIdentityInsertKeys(in EntityKey oldKey, object generatedId);
 
 		/// <summary>Is in a two-phase load? </summary>
 		bool IsLoadFinished { get; }
@@ -425,7 +425,7 @@ public static EntityEntry AddEntity(
 			object entity,
 			Status status,
 			object[] loadedState,
-			EntityKey entityKey,
+			in EntityKey entityKey,
 			object version,
 			LockMode lockMode,
 			bool existsInDatabase,