Get rid of as many SqlColumnCollection related allocations as possible

Author: AlexUstinov

Orm/Xtensive.Orm/Orm/Providers/Expressions/ExpressionProcessor.cs

@@ -28,13 +28,13 @@ internal sealed partial class ExpressionProcessor : ExpressionVisitor<SqlExpress
     private readonly StorageDriver driver;
     private readonly BooleanExpressionConverter booleanExpressionConverter;
     private readonly IMemberCompilerProvider<SqlExpression> memberCompilerProvider;
-    private readonly List<SqlExpression>[] sourceColumns;
+    private readonly IReadOnlyList<SqlExpression>[] sourceColumns;
     private readonly ExpressionEvaluator evaluator;
     private readonly ParameterExtractor parameterExtractor;
     private readonly LambdaExpression lambda;
     private readonly HashSet<QueryParameterBinding> bindings;
     private readonly List<ParameterExpression> activeParameters;
-    private readonly Dictionary<ParameterExpression, List<SqlExpression>> sourceMapping;
+    private readonly Dictionary<ParameterExpression, IReadOnlyList<SqlExpression>> sourceMapping;
     private readonly SqlCompiler compiler;
 
     private readonly Dictionary<QueryParameterIdentity, QueryParameterBinding> bindingsWithIdentity
@@ -448,7 +448,7 @@ private SqlExpression TryUnwrapEnum(SqlContainer container)
     // Constructors
 
     public ExpressionProcessor(
-      LambdaExpression lambda, HandlerAccessor handlers, SqlCompiler compiler, params List<SqlExpression>[] sourceColumns)
+      LambdaExpression lambda, HandlerAccessor handlers, SqlCompiler compiler, params IReadOnlyList<SqlExpression>[] sourceColumns)
     {
       ArgumentValidator.EnsureArgumentNotNull(lambda, "lambda");
       ArgumentValidator.EnsureArgumentNotNull(handlers, "handlers");
@@ -478,7 +478,7 @@ public ExpressionProcessor(
         throw Exceptions.InternalError(Strings.ExParametersCountIsNotSameAsSourceColumnListsCount, OrmLog.Instance);
       if (sourceColumns.Any(list => list.Any(c => c.IsNullReference())))
         throw Exceptions.InternalError(Strings.ExSourceColumnListContainsNullValues, OrmLog.Instance);
-      sourceMapping = new Dictionary<ParameterExpression, List<SqlExpression>>();
+      sourceMapping = new Dictionary<ParameterExpression, IReadOnlyList<SqlExpression>>();
     }
   }
 }

Orm/Xtensive.Orm/Orm/Providers/SqlCompiler.Apply.cs

@@ -167,15 +167,15 @@ private SqlSelect ProcessApplyViaCrossApply(ApplyProvider provider, SqlProvider
         ? left.PermanentReference
         : left.Request.Statement.From;
       var leftColumns = leftShouldUseReference
-        ? leftTable.Columns.Cast<SqlColumn>()
+        ? (IReadOnlyList<SqlColumn>) leftTable.Columns
         : left.Request.Statement.Columns;
 
       var rightShouldUseReference = ShouldUseQueryReference(provider, right);
       var rightTable = rightShouldUseReference
         ? right.PermanentReference
         : right.Request.Statement.From;
       var rightColumns = rightShouldUseReference
-        ? rightTable.Columns.Cast<SqlColumn>()
+        ? (IReadOnlyList<SqlColumn>) rightTable.Columns
         : right.Request.Statement.Columns;
 
       var joinType = provider.ApplyType==JoinType.LeftOuter
@@ -186,8 +186,8 @@ private SqlSelect ProcessApplyViaCrossApply(ApplyProvider provider, SqlProvider
         joinType,
         leftTable,
         rightTable,
-        leftColumns.ToList(),
-        rightColumns.ToList());
+        leftColumns,
+        rightColumns);
 
       var query = SqlDml.Select(joinedTable);
       if (!leftShouldUseReference)

Orm/Xtensive.Orm/Orm/Providers/SqlCompiler.Helpers.cs

@@ -67,7 +67,7 @@ protected virtual string ProcessAliasedName(string name)
     }
 
     protected Pair<SqlExpression, IEnumerable<QueryParameterBinding>> ProcessExpression(LambdaExpression le,
-      params List<SqlExpression>[] sourceColumns)
+      params IReadOnlyList<SqlExpression>[] sourceColumns)
     {
       var processor = new ExpressionProcessor(le, Handlers, this, sourceColumns);
       var result = new Pair<SqlExpression, IEnumerable<QueryParameterBinding>>(

Orm/Xtensive.Orm/Orm/Providers/SqlCompiler.cs

@@ -175,7 +175,7 @@ protected override SqlProvider VisitJoin(JoinProvider provider)
         ? left.PermanentReference
         : left.Request.Statement.From;
       var leftColumns = leftShouldUseReference
-        ? leftTable.Columns.Cast<SqlColumn>()
+        ? (IReadOnlyList<SqlColumn>) leftTable.Columns
         : left.Request.Statement.Columns;
       var leftExpressions = leftShouldUseReference
         ? leftTable.Columns.Cast<SqlExpression>().ToList()
@@ -186,7 +186,7 @@ protected override SqlProvider VisitJoin(JoinProvider provider)
         ? right.PermanentReference
         : right.Request.Statement.From;
       var rightColumns = rightShouldUseReference
-        ? rightTable.Columns.Cast<SqlColumn>()
+        ? (IReadOnlyList<SqlColumn>) rightTable.Columns
         : right.Request.Statement.Columns;
       var rightExpressions = rightShouldUseReference
         ? rightTable.Columns.Cast<SqlExpression>().ToList()
@@ -207,8 +207,8 @@ protected override SqlProvider VisitJoin(JoinProvider provider)
         joinType,
         leftTable,
         rightTable,
-        leftColumns.ToList(),
-        rightColumns.ToList(),
+        leftColumns,
+        rightColumns,
         joinExpression);
 
       var query = SqlDml.Select(joinedTable);
@@ -231,21 +231,21 @@ protected override SqlProvider VisitPredicateJoin(PredicateJoinProvider provider
         ? left.PermanentReference
         : left.Request.Statement.From;
       var leftColumns = leftShouldUseReference
-        ? leftTable.Columns.Cast<SqlColumn>()
+        ? (IReadOnlyList<SqlColumn>) leftTable.Columns
         : left.Request.Statement.Columns;
       var leftExpressions = leftShouldUseReference
-        ? leftTable.Columns.Cast<SqlExpression>().ToList()
+        ? (IReadOnlyList<SqlExpression>) leftTable.Columns
         : ExtractColumnExpressions(left.Request.Statement);
 
       var rightShouldUseReference = ShouldUseQueryReference(provider, right);
       var rightTable = rightShouldUseReference
         ? right.PermanentReference
         : right.Request.Statement.From;
       var rightColumns = rightShouldUseReference
-        ? rightTable.Columns.Cast<SqlColumn>()
+        ? (IReadOnlyList<SqlColumn>) rightTable.Columns
         : right.Request.Statement.Columns;
       var rightExpressions = rightShouldUseReference
-        ? rightTable.Columns.Cast<SqlExpression>().ToList()
+        ? (IReadOnlyList<SqlExpression>) rightTable.Columns
         : ExtractColumnExpressions(right.Request.Statement);
 
 
@@ -259,8 +259,8 @@ protected override SqlProvider VisitPredicateJoin(PredicateJoinProvider provider
         joinType,
         leftTable,
         rightTable,
-        leftColumns.ToList(),
-        rightColumns.ToList(),
+        leftColumns,
+        rightColumns,
         joinExpression);
 
       var query = SqlDml.Select(joinedTable);

Orm/Xtensive.Orm/Sql/Dml/Collections/SqlColumnCollection.cs

@@ -39,9 +39,13 @@ public class SqlColumnCollection : ICollection<SqlColumn>, IReadOnlyList<SqlColu
     public List<SqlColumn>.Enumerator GetEnumerator() => columnList.GetEnumerator();
 
     /// <summary>
-    /// Gets the column at the specified <paramref name="index"/>.
+    /// Gets or sets the column at the specified <paramref name="index"/>.
     /// </summary>
-    public SqlColumn this[int index] => columnList[index];
+    public SqlColumn this[int index]
+    {
+      get => columnList[index];
+      set => columnList[index] = value;
+    }
 
     /// <summary>
     /// Gets the column with the specified <paramref name="name"/>
@@ -141,9 +145,18 @@ public SqlColumnCollection()
     /// <summary>
     /// Initializes new instance of this type.
     /// </summary>
-    public SqlColumnCollection(IReadOnlyList<SqlColumn> list)
+    public SqlColumnCollection(IEnumerable<SqlColumn> columns)
+    {
+      columnList = new List<SqlColumn>(columns);
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SqlColumnCollection"/> class.
+    /// This is special version it uses provided list as is.
+    /// </summary>
+    internal SqlColumnCollection(List<SqlColumn> columns)
     {
-      columnList = new List<SqlColumn>(list);
+      columnList = columns;
     }
   }
 }

Orm/Xtensive.Orm/Sql/Dml/Collections/SqlTableColumnCollection.cs

@@ -16,7 +16,7 @@ public class SqlTableColumnCollection : IReadOnlyList<SqlTableColumn>
   {
     private static readonly StringComparer Comparer = StringComparer.OrdinalIgnoreCase;
     private readonly List<SqlTableColumn> columnList;
-    private readonly Dictionary<string, SqlTableColumn> columnLookup;
+    private Dictionary<string, SqlTableColumn> columnLookup;
 
     /// <summary>
     /// Gets the number of elements contained in the <see cref="SqlTableColumnCollection"/>.
@@ -50,33 +50,52 @@ public SqlTableColumn this[string name]
           return null;
         }
 
-        if (columnLookup == null) {
-          return columnList.Find(column => Comparer.Equals(column.Name, name));
+        if (columnLookup != null) {
+          return columnLookup.TryGetValue(name, out var column) ? column : null;
         }
 
-        {
-          return columnLookup.TryGetValue(name, out var column) ? column : null;
+        var count = columnList.Count;
+        if (count <= 16) {
+          foreach (var column in columnList) {
+            if (Comparer.Equals(column.Name, name)) {
+              return column;
+            }
+          }
+
+          return null;
         }
+
+        SqlTableColumn result = null;
+        columnLookup = new Dictionary<string, SqlTableColumn>(count, Comparer);
+        for (var index = count - 1; index >= 0; index--) {
+          var column = columnList[index];
+          var columnName = column.Name;
+          columnLookup[columnName] = column;
+          if (Comparer.Equals(columnName, name)) {
+            result = column;
+          }
+        }
+
+        return result;
       }
     }
 
     /// <summary>
     /// Initializes a new instance of the <see cref="SqlTableColumnCollection"/> class.
     /// </summary>
     /// <param name="columns">A collection of <see cref="SqlTableColumn"/>s to be wrapped.</param>
-    public SqlTableColumnCollection(IReadOnlyCollection<SqlTableColumn> columns)
+    public SqlTableColumnCollection(IEnumerable<SqlTableColumn> columns)
     {
-      if (columns.Count <= 8) {
-        columnList = new List<SqlTableColumn>(columns);
-      }
-      else {
-        columnList = new List<SqlTableColumn>(columns.Count);
-        columnLookup = new Dictionary<string, SqlTableColumn>(columns.Count, Comparer);
-        foreach (var column in columns) {
-          columnList.Add(column);
-          columnLookup.Add(column.Name, column);
-        }
-      }
+      columnList = new List<SqlTableColumn>(columns);
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SqlTableColumnCollection"/> class.
+    /// This is special version it uses provided list as is.
+    /// </summary>
+    internal SqlTableColumnCollection(List<SqlTableColumn> columns)
+    {
+      columnList = columns;
     }
   }
 }

Orm/Xtensive.Orm/Sql/Dml/SqlContainsTable.cs

@@ -66,35 +66,40 @@ public SqlQueryExpression UnionAll(ISqlQueryExpression operand)
     // Constructors
 
 
-    internal SqlContainsTable(DataTable dataTable, SqlExpression freeText, IEnumerable<string> columnNames)
+    internal SqlContainsTable(DataTable dataTable, SqlExpression freeText, ICollection<string> columnNames)
       : this(dataTable, freeText, columnNames, ArrayUtils<string>.EmptyArray, null)
     {
     }
 
-    internal SqlContainsTable(DataTable dataTable, SqlExpression freeText, IEnumerable<string> columnNames, ICollection<string> targetColumnNames)
+    internal SqlContainsTable(DataTable dataTable, SqlExpression freeText, ICollection<string> columnNames, ICollection<string> targetColumnNames)
       : this(dataTable, freeText, columnNames, targetColumnNames, null)
     {
     }
 
-    internal SqlContainsTable(DataTable dataTable, SqlExpression freeText, IEnumerable<string> columNames, SqlExpression topN)
-      : this(dataTable, freeText, columNames, ArrayUtils<string>.EmptyArray, topN)
+    internal SqlContainsTable(DataTable dataTable, SqlExpression freeText, ICollection<string> columnNames, SqlExpression topN)
+      : this(dataTable, freeText, columnNames, ArrayUtils<string>.EmptyArray, topN)
     {
     }
 
-    internal SqlContainsTable(DataTable dataTable, SqlExpression searchCondition, IEnumerable<string> columnNames, ICollection<string> targetColumnNames, SqlExpression topNByRank)
+    internal SqlContainsTable(DataTable dataTable, SqlExpression searchCondition, ICollection<string> columnNames, ICollection<string> targetColumnNames, SqlExpression topNByRank)
       : base(string.Empty)
     {
       TargetTable = SqlDml.TableRef(dataTable);
       SearchCondition = searchCondition;
       TopNByRank = topNByRank;
-      var targetColumns = new List<SqlTableColumn>();
-      if (targetColumnNames.Count == 0)
-        targetColumns.Add(Asterisk);
-      else
-        targetColumns = targetColumnNames.Select(cn => SqlDml.TableColumn(this, cn)).ToList();
-      TargetColumns = new SqlTableColumnCollection(targetColumns);
-
-      columns = new SqlTableColumnCollection(columnNames.Select(column=>SqlDml.TableColumn(this, column)).ToList());
+      var targetColumnCount = targetColumnNames.Count;
+      if (targetColumnCount == 0) {
+        TargetColumns = new SqlTableColumnCollection(new List<SqlTableColumn>(1) {Asterisk});
+      }
+      else {
+        var targetColumns = new List<SqlTableColumn>(targetColumnCount);
+        targetColumns.AddRange(targetColumnNames.Select(columnName => SqlDml.TableColumn(this, columnName)));
+        TargetColumns = new SqlTableColumnCollection(targetColumns);
+      }
+
+      var columnList = new List<SqlTableColumn>(columnNames.Count);
+      columnList.AddRange(columnNames.Select(columnName => SqlDml.TableColumn(this, columnName)));
+      columns = new SqlTableColumnCollection(columnList);
     }
   }
 }

Orm/Xtensive.Orm/Sql/Dml/SqlFreeTextTable.cs

@@ -71,35 +71,40 @@ public SqlQueryExpression UnionAll(ISqlQueryExpression operand)
 
     // Constructors
 
-    internal SqlFreeTextTable(DataTable dataTable, SqlExpression freeText, IEnumerable<string> columnNames)
+    internal SqlFreeTextTable(DataTable dataTable, SqlExpression freeText, ICollection<string> columnNames)
       : this(dataTable, freeText, columnNames, ArrayUtils<string>.EmptyArray, null)
     {
     }
 
-    internal SqlFreeTextTable(DataTable dataTable, SqlExpression freeText, IEnumerable<string> columnNames, ICollection<string> targetColumnNames)
+    internal SqlFreeTextTable(DataTable dataTable, SqlExpression freeText, ICollection<string> columnNames, ICollection<string> targetColumnNames)
       : this(dataTable, freeText, columnNames, targetColumnNames, null)
     {
     }
 
-    internal SqlFreeTextTable(DataTable dataTable, SqlExpression freeText, IEnumerable<string> columNames, SqlExpression topN)
-      : this(dataTable, freeText, columNames, ArrayUtils<string>.EmptyArray, topN)
+    internal SqlFreeTextTable(DataTable dataTable, SqlExpression freeText, ICollection<string> columnNames, SqlExpression topN)
+      : this(dataTable, freeText, columnNames, ArrayUtils<string>.EmptyArray, topN)
     {
     }
 
-    internal SqlFreeTextTable(DataTable dataTable, SqlExpression freeText, IEnumerable<string> columnNames, ICollection<string> targetColumnNames, SqlExpression topNByRank)
+    internal SqlFreeTextTable(DataTable dataTable, SqlExpression freeText, ICollection<string> columnNames, ICollection<string> targetColumnNames, SqlExpression topNByRank)
       : base(string.Empty)
     {
       TargetTable = SqlDml.TableRef(dataTable);
       FreeText = freeText;
       TopNByRank = topNByRank;
-      var targetColumns = new List<SqlTableColumn>();
-      if (targetColumnNames.Count == 0)
-        targetColumns.Add(Asterisk);
-      else
-        targetColumns = targetColumnNames.Select(cn => SqlDml.TableColumn(this, cn)).ToList();
-      TargetColumns = new SqlTableColumnCollection(targetColumns);
-
-      columns = new SqlTableColumnCollection(columnNames.Select(column=>SqlDml.TableColumn(this, column)).ToList());
+      var targetColumnCount = targetColumnNames.Count;
+      if (targetColumnCount == 0) {
+        TargetColumns = new SqlTableColumnCollection(new List<SqlTableColumn>(1) {Asterisk});
+      }
+      else {
+        var targetColumns = new List<SqlTableColumn>(targetColumnCount);
+        targetColumns.AddRange(targetColumnNames.Select(columnName => SqlDml.TableColumn(this, columnName)));
+        TargetColumns = new SqlTableColumnCollection(targetColumns);
+      }
+
+      var columnList = new List<SqlTableColumn>(columnNames.Count);
+      columnList.AddRange(columnNames.Select(columnName => SqlDml.TableColumn(this, columnName)));
+      columns = new SqlTableColumnCollection(columnList);
     }
   }
 }