Adding changes as requested for code review

src/Microsoft.SqlTools.ServiceLayer/QueryExecution/Query.cs

@@ -1,4 +1,9 @@
-using System;
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
 using System.Collections.Generic;
 using System.Data;
 using System.Data.Common;
@@ -10,18 +15,39 @@ using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts;
 
 namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
 {
-    public class Query //: IDisposable
+    /// <summary>
+    /// Internal representation of an active query
+    /// </summary>
+    public class Query : IDisposable
     {
         #region Properties
 
-        public string QueryText { get; set; }
-
-        public ConnectionInfo EditorConnection { get; set; }
-
+        /// <summary>
+        /// Cancellation token source, used for cancelling async db actions
+        /// </summary>
         private readonly CancellationTokenSource cancellationSource;
 
+        /// <summary>
+        /// The connection info associated with the file editor owner URI, used to create a new
+        /// connection upon execution of the query
+        /// </summary>
+        public ConnectionInfo EditorConnection { get; set; }
+
+        public bool HasExecuted { get; set; }
+
+        /// <summary>
+        /// The text of the query to execute
+        /// </summary>
+        public string QueryText { get; set; }
+
+        /// <summary>
+        /// The result sets of the query execution
+        /// </summary>
         public List<ResultSet> ResultSets { get; set; }
 
+        /// <summary>
+        /// Property for generating a set result set summaries from the result sets
+        /// </summary>
         public ResultSetSummary[] ResultSummary
         {
             get
@@ -35,10 +61,13 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
             }
         }
 
-        public bool HasExecuted { get; set; }
-
         #endregion
 
+        /// <summary>
+        /// Constructor for a query
+        /// </summary>
+        /// <param name="queryText">The text of the query to execute</param>
+        /// <param name="connection">The information of the connection to use to execute the query</param>
         public Query(string queryText, ConnectionInfo connection)
         {
             // Sanity check for input
@@ -59,6 +88,9 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
             cancellationSource = new CancellationTokenSource();
         }
 
+        /// <summary>
+        /// Executes this query asynchronously and collects all result sets
+        /// </summary>
         public async Task Execute()
         {
             // Sanity check to make sure we haven't already run this query
@@ -67,11 +99,13 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
                 throw new InvalidOperationException("Query has already executed.");
             }
 
+            DbConnection conn = null;
+
             // Create a connection from the connection details
             try
             {
                 string connectionString = ConnectionService.BuildConnectionString(EditorConnection.ConnectionDetails);
-                using (DbConnection conn = EditorConnection.Factory.CreateSqlConnection(connectionString))
+                using (EditorConnection.Factory.CreateSqlConnection(connectionString))
                 {
                     await conn.OpenAsync(cancellationSource.Token);
 
@@ -112,6 +146,11 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
                     }
                 }
             }
+            catch (Exception)
+            {
+                // Dispose of the connection
+                conn?.Dispose();
+            }
             finally
             {
                 // Mark that we have executed
@@ -119,6 +158,13 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
             }
         }
 
+        /// <summary>
+        /// Retrieves a subset of the result sets
+        /// </summary>
+        /// <param name="resultSetIndex">The index for selecting the result set</param>
+        /// <param name="startRow">The starting row of the results</param>
+        /// <param name="rowCount">How many rows to retrieve</param>
+        /// <returns>A subset of results</returns>
         public ResultSetSubset GetSubset(int resultSetIndex, int startRow, int rowCount)
         {
             // Sanity check that the results are available
@@ -152,5 +198,37 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
                 RowCount = rows.Length
             };
         }
+
+        #region IDisposable Implementation
+
+        private bool disposed;
+
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposed)
+            {
+                return;
+            }
+
+            if (disposing)
+            {
+                cancellationSource.Dispose();
+            }
+
+            disposed = true;
+        }
+
+        ~Query()
+        {
+            Dispose(false);
+        }
+
+        #endregion
     }
 }