fixed the issue with resources not disposed correctly (#439)

* fixed the issue with resources not disposed correctly

* disposing language service at shutdown

src/Microsoft.SqlTools.ServiceLayer/Admin/Common/DataContainer.cs

@@ -1119,9 +1119,10 @@ namespace Microsoft.SqlTools.ServiceLayer.Admin
                 throw new ArgumentException("sourceXml");
             }
 
-            MemoryStream memoryStream = new MemoryStream();
-            StreamWriter streamWriter = new StreamWriter(memoryStream);
-
+            using (MemoryStream memoryStream = new MemoryStream())
+            {
+                using (StreamWriter streamWriter = new StreamWriter(memoryStream))
+                {
                     //  Writes the xml to the memory stream
                     streamWriter.Write(sourceXml);
                     streamWriter.Flush();
@@ -1141,6 +1142,8 @@ namespace Microsoft.SqlTools.ServiceLayer.Admin
 
                     return xmlDocument;
                 }
+            }
+        }
 
         #endregion
 

src/Microsoft.SqlTools.ServiceLayer/Admin/Database/DatabasePrototype.cs

@@ -647,17 +647,20 @@ WHERE do.database_id = @DbID
                 { //If it's under v12 we need to query the master DB directly since that has the views containing the necessary information
                     using (var conn = new SqlConnection(context.Server.ConnectionContext.ConnectionString))
                     {
-                        var cmd = new SqlCommand(dbSloQuery, conn);
+                        using (var cmd = new SqlCommand(dbSloQuery, conn))
+                        {
                             cmd.Parameters.AddWithValue("@DbID", db.ID);
                             conn.Open();
-                        SqlDataReader reader = cmd.ExecuteReader();
+                            using (SqlDataReader reader = cmd.ExecuteReader())
+                            {
                                 while (reader.Read())
                                 {
                                     this.configuredServiceLevelObjective = reader["configured_slo_name"].ToString();
                                     this.currentServiceLevelObjective = reader["current_slo_name"].ToString();
                                     break; //Got our service level objective so we're done
                                 }
-
+                            }
+                        }
                     }
                 }
             }

src/Microsoft.SqlTools.ServiceLayer/Admin/Database/DatabasePrototypeAzure.cs

@@ -178,7 +178,8 @@ namespace Microsoft.SqlTools.ServiceLayer.Admin
            //Altering the DB needs to be done on the master DB
            using (var conn = new SqlConnection(this.context.ServerConnection.GetDatabaseConnection("master").ConnectionString))
            {
-               var cmd = new SqlCommand();
+                using (var cmd = new SqlCommand())
+                {
                     cmd.Connection = conn;
                     conn.Open();
 
@@ -205,6 +206,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Admin
                         cmd.ExecuteNonQuery();
                     }
                 }
+           }
 
            //Because we didn't use SMO to do the alter we should refresh the DB object so it picks up the correct properties
            db.Refresh();

src/Microsoft.SqlTools.ServiceLayer/HostLoader.cs

@@ -2,6 +2,7 @@
 // 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 Microsoft.SqlTools.Credentials;
 using Microsoft.SqlTools.Extensibility;
 using Microsoft.SqlTools.Hosting;
@@ -13,7 +14,6 @@ using Microsoft.SqlTools.ServiceLayer.EditData;
 using Microsoft.SqlTools.ServiceLayer.Hosting;
 using Microsoft.SqlTools.ServiceLayer.LanguageServices;
 using Microsoft.SqlTools.ServiceLayer.Metadata;
-using Microsoft.SqlTools.ServiceLayer.ObjectExplorer;
 using Microsoft.SqlTools.ServiceLayer.QueryExecution;
 using Microsoft.SqlTools.ServiceLayer.Scripting;
 using Microsoft.SqlTools.ServiceLayer.SqlContext;

src/Microsoft.SqlTools.ServiceLayer/LanguageServices/BindingQueue.cs

@@ -14,7 +14,7 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
     /// <summary>
     /// Main class for the Binding Queue
     /// </summary>
-    public class BindingQueue<T> where T : IBindingContext, new()
+    public class BindingQueue<T> : IDisposable where T : IBindingContext, new()
     {
         private CancellationTokenSource processQueueCancelToken = new CancellationTokenSource();
 
@@ -313,5 +313,24 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
                 }
             }
         }
+
+        public void Dispose()
+        {
+            if (itemQueuedEvent != null)
+            {
+                itemQueuedEvent.Dispose();
+            }
+
+            if (this.BindingContextMap != null)
+            {
+                foreach (var item in this.BindingContextMap)
+                {
+                    if (item.Value != null && item.Value.ServerConnection != null && item.Value.ServerConnection.SqlConnectionObject != null)
+                    {
+                        item.Value.ServerConnection.SqlConnectionObject.Close();
+                    }
+                }
+            }
+        }
     }
 }

src/Microsoft.SqlTools.ServiceLayer/LanguageServices/LanguageService.cs

@@ -36,7 +36,7 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
     /// Main class for Language Service functionality including anything that requires knowledge of
     /// the language to perform, such as definitions, intellisense, etc.
     /// </summary>
-    public sealed class LanguageService
+    public sealed class LanguageService: IDisposable
     {
         #region Singleton Instance Implementation
 
@@ -249,6 +249,7 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
             {
                 Logger.Write(LogLevel.Verbose, "Shutting down language service");
                 DeletePeekDefinitionScripts();
+                this.Dispose();
                 await Task.FromResult(0);
             });
 
@@ -1716,5 +1717,13 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
 
             return string.Empty;
         }
+
+        public void Dispose()
+        {
+            if (bindingQueue != null)
+            {
+                bindingQueue.Dispose();
+            }
+        }
     }
 }

src/Microsoft.SqlTools.ServiceLayer/TaskServices/SqlTask.cs

@@ -147,10 +147,11 @@ namespace Microsoft.SqlTools.ServiceLayer.TaskServices
             Task<TaskResult> completedTask = null;
 
             try
+            {
+                using (AutoResetEvent onCompletedEvent = new AutoResetEvent(initialState: false))
                 {
                     if (TaskToCancel != null)
                     {
-                    AutoResetEvent onCompletedEvent = new AutoResetEvent(initialState: false);
                         Task<TaskResult> cancelTask = Task.Run(() => CancelTaskAsync(TokenSource.Token, onCompletedEvent));
 
                         completedTask = await Task.WhenAny(performTask, cancelTask);
@@ -169,7 +170,7 @@ namespace Microsoft.SqlTools.ServiceLayer.TaskServices
                     AddMessage(completedTask.Result.TaskStatus == SqlTaskStatus.Failed ? completedTask.Result.ErrorMessage : SR.TaskCompleted,
                                        completedTask.Result.TaskStatus);
                     taskResult = completedTask.Result;
-
+                }
             }
             catch (OperationCanceledException)
             {