Optimize filter applying logic (#2295)

Author: bahusoid

src/NHibernate/Persister/Entity/AbstractEntityPersister.cs

@@ -2148,13 +2148,18 @@ public string GenerateTableAlias(string rootAlias, int tableNumber)
 			if (tableNumber == 0)
 				return rootAlias;
 
-			StringBuilder buf = new StringBuilder().Append(rootAlias);
-			if (!rootAlias.EndsWith("_"))
-			{
-				buf.Append('_');
-			}
+			string x = rootAlias.EndsWith('_')
+				? string.Empty
+				: "_";
+			return string.Concat(rootAlias, x, tableNumber.ToString(), "_");
+		}
 
-			return buf.Append(tableNumber).Append('_').ToString();
+		private string GetSubclassAliasedColumn(string rootAlias, int tableNumber, string columnName)
+		{
+			if (string.IsNullOrEmpty(rootAlias))
+				return columnName;
+
+			return GenerateTableAlias(rootAlias, tableNumber) + "." + columnName;
 		}
 
 		public string[] ToColumns(string name, int i)
@@ -3655,16 +3660,21 @@ protected void LogStaticSQL()
 
 		public virtual string FilterFragment(string alias, IDictionary<string, IFilter> enabledFilters)
 		{
-			StringBuilder sessionFilterFragment = new StringBuilder();
+			var filterFragment = FilterFragment(alias);
+			if (!filterHelper.IsAffectedBy(enabledFilters))
+				return filterFragment;
 
+			var sessionFilterFragment = new StringBuilder();
 			filterHelper.Render(sessionFilterFragment, GenerateFilterConditionAlias(alias), GetColumnsToTableAliasMap(alias), enabledFilters);
-
-			return sessionFilterFragment.Append(FilterFragment(alias)).ToString();
+			return sessionFilterFragment.Append(filterFragment).ToString();
 		}
 
 		private IDictionary<string, string> GetColumnsToTableAliasMap(string rootAlias)
 		{
-			IDictionary<PropertyKey, string> propDictionary = new Dictionary<PropertyKey, string>();
+			if (SubclassTableSpan < 2)
+				return CollectionHelper.EmptyDictionary<string, string>();
+
+			var propDictionary = new Dictionary<PropertyKey, string>();
 			for (int i =0; i < SubclassPropertyNameClosure.Length; i++)
 			{
 				string property = SubclassPropertyNameClosure[i];
@@ -3677,20 +3687,11 @@ private IDictionary<string, string> GetColumnsToTableAliasMap(string rootAlias)
 				}
 			}
 
-			IDictionary<string, string> dict = new Dictionary<string, string>();
+			var dict = new Dictionary<string, string>();
 			for (int i = 0; i < SubclassColumnTableNumberClosure.Length; i++ )
 			{
-				string fullColumn;
 				string col = SubclassColumnClosure[i];
-				if (!string.IsNullOrEmpty(rootAlias))
-				{
-					string alias = GenerateTableAlias(rootAlias, SubclassColumnTableNumberClosure[i]);
-					fullColumn = string.Format("{0}.{1}", alias, col);
-				}
-				else
-				{
-					fullColumn = col;
-				}
+				var fullColumn = GetSubclassAliasedColumn(rootAlias, SubclassColumnTableNumberClosure[i], col);
 
 				PropertyKey key = new PropertyKey(col, SubclassColumnTableNumberClosure[i]);
 				if (propDictionary.ContainsKey(key))
@@ -3709,8 +3710,7 @@ private IDictionary<string, string> GetColumnsToTableAliasMap(string rootAlias)
 			{
 				foreach (var key in GetSubclassTableKeyColumns(i))
 				{
-					var alias = i == 0 ? rootAlias : GenerateTableAlias(rootAlias, i);
-					dict[key] = $"{alias}.{key}";
+					dict[key] = GetSubclassAliasedColumn(rootAlias, i, key);
 				}
 			}
 
@@ -3753,7 +3753,7 @@ public virtual string OneToManyFilterFragment(string alias)
 		public virtual SqlString FromJoinFragment(string alias, bool innerJoin, bool includeSubclasses)
 		{
 			return SubclassTableSpan == 1
-				? new SqlString(string.Empty) // just a performance opt!
+				? SqlString.Empty // just a performance opt!
 				: CreateJoin(alias, innerJoin, includeSubclasses).ToFromFragmentString;
 		}
 

src/NHibernate/Util/FilterHelper.cs

@@ -55,50 +55,44 @@ public string Render(String alias, IDictionary<string, IFilter> enabledFilters)
 
 		public void Render(StringBuilder buffer, string alias, IDictionary<string, IFilter> enabledFilters)
 		{
-			Render(buffer, alias, new Dictionary<string, string>(), enabledFilters);
+			Render(buffer, alias, CollectionHelper.EmptyDictionary<string, string>(), enabledFilters);
 		}
 
 		public void Render(StringBuilder buffer, string defaultAlias, IDictionary<string, string> propMap, IDictionary<string, IFilter> enabledFilters)
 		{
-			if (filterNames != null)
+			for (int i = 0; i < filterNames.Length; i++)
 			{
-				int max = filterNames.Length;
-				if (max > 0)
+				if (enabledFilters.ContainsKey(filterNames[i]))
 				{
-					for (int i = 0; i < max; i++)
+					string condition = filterConditions[i];
+					if (!string.IsNullOrEmpty(condition))
 					{
-						if (enabledFilters.ContainsKey(filterNames[i]))
-						{
-							string condition = filterConditions[i];
-							if (StringHelper.IsNotEmpty(condition))
-							{
-								buffer.Append(" and ");
-								AddFilterString(buffer, defaultAlias, propMap, condition);
-							}
-						}
+						buffer.Append(" and ");
+						AddFilterString(buffer, defaultAlias, propMap, condition);
 					}
 				}
 			}
 		}
 
 		private static void AddFilterString(StringBuilder buffer, string defaultAlias, IDictionary<string, string> propMap, string condition)
 		{
-			int i = condition.IndexOf(FilterImpl.MARKER);
+			int i;
 			int upTo = 0;
-			while (i > -1 && upTo < condition.Length)
+			while ((i = condition.IndexOf(FilterImpl.MARKER, upTo, StringComparison.Ordinal)) >= 0 && upTo < condition.Length)
 			{
-				buffer.Append(condition.Substring(upTo, i - upTo));
+				buffer.Append(condition, upTo, i - upTo);
 				int startOfProperty = i + FilterImpl.MARKER.Length + 1;
 
-				upTo = condition.IndexOf(" ", startOfProperty);
+				upTo = condition.IndexOf(' ', startOfProperty);
 				upTo = upTo >= 0 ? upTo : condition.Length;
 				string property = condition.Substring(startOfProperty, upTo - startOfProperty);
 
-				string fullColumn = propMap.ContainsKey(property) ? propMap[property] : string.Format("{0}.{1}", defaultAlias, property);
+				if (!propMap.TryGetValue(property, out var fullColumn))
+					fullColumn = string.IsNullOrEmpty(defaultAlias)
+						? property
+						: defaultAlias + "." + property;
 
 				buffer.Append(fullColumn);
-
-				i = condition.IndexOf(FilterImpl.MARKER, upTo);
 			}
 			buffer.Append(condition.Substring(upTo));
 		}