setting timeout for oe tasks (#363)

src/Microsoft.SqlTools.ServiceLayer/ObjectExplorer/ObjectExplorerService.cs

@@ -10,6 +10,7 @@ using System.Collections.ObjectModel;
 using System.Composition;
 using System.Globalization;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.SqlTools.Extensibility;
 using Microsoft.SqlTools.Hosting;
@@ -19,6 +20,8 @@ using Microsoft.SqlTools.ServiceLayer.Connection.Contracts;
 using Microsoft.SqlTools.ServiceLayer.ObjectExplorer.Contracts;
 using Microsoft.SqlTools.ServiceLayer.ObjectExplorer.Nodes;
 using Microsoft.SqlTools.ServiceLayer.ObjectExplorer.SmoModel;
+using Microsoft.SqlTools.ServiceLayer.SqlContext;
+using Microsoft.SqlTools.ServiceLayer.Workspace;
 using Microsoft.SqlTools.Utility;
 
 namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer
@@ -39,6 +42,11 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer
         private readonly Lazy<Dictionary<string, HashSet<ChildFactory>>> applicableNodeChildFactories;
         private IMultiServiceProvider serviceProvider;
 
+        /// <summary>
+        /// This timeout limits the amount of time that object explorer tasks can take to complete
+        /// </summary>
+        private ObjectExplorerSettings settings;
+
         /// <summary>
         /// Singleton constructor
         /// </summary>
@@ -101,8 +109,34 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer
             serviceHost.SetRequestHandler(ExpandRequest.Type, HandleExpandRequest);
             serviceHost.SetRequestHandler(RefreshRequest.Type, HandleRefreshRequest);
             serviceHost.SetRequestHandler(CloseSessionRequest.Type, HandleCloseSessionRequest);
+            WorkspaceService<SqlToolsSettings> workspaceService = WorkspaceService;
+            if (workspaceService != null)
+            {
+                workspaceService.RegisterConfigChangeCallback(HandleDidChangeConfigurationNotification);
+            }
         }
 
+        /// <summary>
+        /// Gets the workspace service. Note: should handle case where this is null in cases where unit tests do not set this up
+        /// </summary>
+        private WorkspaceService<SqlToolsSettings> WorkspaceService
+        {
+            get { return serviceProvider.GetService<WorkspaceService<SqlToolsSettings>>(); }
+        }
+
+
+        /// <summary>
+        /// Ensure formatter settings are always up to date
+        /// </summary>
+        public Task HandleDidChangeConfigurationNotification(
+            SqlToolsSettings newSettings,
+            SqlToolsSettings oldSettings,
+            EventContext eventContext)
+        {
+            // update the current settings to reflect any changes (assuming formatter settings exist)
+            settings = newSettings.SqlTools.ObjectExplorer ?? settings;
+            return Task.FromResult(true);
+        }
 
 
         internal async Task HandleCreateSessionRequest(ConnectionDetails connectionDetails, RequestContext<CreateSessionResponse> context)
@@ -140,8 +174,6 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer
 
                 string uri = expandParams.SessionId;
                 ObjectExplorerSession session = null;
-                NodeInfo[] nodes = null;
-                ExpandResponse response;
                 if (!sessionMap.TryGetValue(uri, out session))
                 {
                     Logger.Write(LogLevel.Verbose, $"Cannot expand object explorer node. Couldn't find session for uri. {uri} ");
@@ -170,7 +202,6 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer
 
             string uri = refreshParams.SessionId;
             ObjectExplorerSession session = null;
-            ExpandResponse response;
             if (!sessionMap.TryGetValue(uri, out session))
             {
                 Logger.Write(LogLevel.Verbose, $"Cannot expand object explorer node. Couldn't find session for uri. {uri} ");
@@ -237,11 +268,28 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer
 
         private void  RunCreateSessionTask(ConnectionDetails connectionDetails, string uri)
         {
+            CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
             if (connectionDetails != null && !string.IsNullOrEmpty(uri))
             {
-                Task task = CreateSessionAsync(connectionDetails, uri);
+                Task task = CreateSessionAsync(connectionDetails, uri, cancellationTokenSource.Token);
                 CreateSessionTask = task;
-                Task.Run(async () => await task);
+                Task.Run(async () => 
+                {
+                    ObjectExplorerTaskResult result = await RunTaskWithTimeout(task, settings.CreateSessionTimeout);
+                    if (result != null && !result.IsComplete)
+                    {
+                        cancellationTokenSource.Cancel();
+                        SessionCreatedParameters response = new SessionCreatedParameters
+                        {
+                            Success = false,
+                            SessionId = uri,
+                            ErrorMessage = result.Exception != null ? result.Exception.Message : $"Failed to create session for session id {uri}"
+
+                        };
+                        await serviceHost.SendEvent(CreateSessionCompleteNotification.Type, response);
+                    }
+                    return result;
+                });
             }
         }
 
@@ -254,7 +302,7 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer
             private set;
         }
 
-        private async Task<SessionCreatedParameters> CreateSessionAsync(ConnectionDetails connectionDetails, string uri)
+        private async Task<SessionCreatedParameters> CreateSessionAsync(ConnectionDetails connectionDetails, string uri, CancellationToken cancellationToken)
         {
             ObjectExplorerSession session;
             if (!sessionMap.TryGetValue(uri, out session))
@@ -264,7 +312,7 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer
             }
 
             SessionCreatedParameters response;
-            if (session != null)
+            if (session != null && !cancellationToken.IsCancellationRequested)
             {
                 // Else we have a session available, response with existing session information
                 response = new SessionCreatedParameters
@@ -366,14 +414,40 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer
 
         private void RunExpandTask(ObjectExplorerSession session, ExpandParams expandParams, bool forceRefresh = false)
         {
-            Task task = ExpandNodeAsync(session, expandParams, forceRefresh);
+            CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
+            Task task = ExpandNodeAsync(session, expandParams,  cancellationTokenSource.Token, forceRefresh);
             ExpandTask = task;
             Task.Run(async () =>
             {
-                await task;
+                ObjectExplorerTaskResult result =  await RunTaskWithTimeout(task, settings.ExpandTimeout);
+                if (result != null && !result.IsComplete)
+                {
+                    cancellationTokenSource.Cancel();
+                    ExpandResponse response = CreateExpandResponse(session, expandParams);
+                    response.ErrorMessage = result.Exception != null ? result.Exception.Message: $"Failed to expand node: {expandParams.NodePath} in session {session.Uri}";
+                    await serviceHost.SendEvent(ExpandCompleteNotification.Type, response);
+                }
+                return result;
             });
         }
 
+        private async Task<ObjectExplorerTaskResult> RunTaskWithTimeout(Task task, int timeoutInSec)
+        {
+            ObjectExplorerTaskResult result = new ObjectExplorerTaskResult();
+            TimeSpan timeout = TimeSpan.FromSeconds(timeoutInSec);
+            await Task.WhenAny(task, Task.Delay(timeout));
+            result.IsComplete = task.IsCompleted;
+            if(task.Exception != null)
+            {
+                result.Exception = task.Exception;
+            }
+            else if (!task.IsCompleted)
+            {
+                result.Exception = new TimeoutException($"Object Explorer task didn't completed in {timeoutInSec} seconds.");
+            }
+            return result;
+        }
+
         /// <summary>
         /// For tests only
         /// </summary>
@@ -383,15 +457,26 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer
             set;
         }
 
-        private async Task ExpandNodeAsync(ObjectExplorerSession session, ExpandParams expandParams, bool forceRefresh = false)
+        private async Task ExpandNodeAsync(ObjectExplorerSession session, ExpandParams expandParams, CancellationToken cancellationToken, bool forceRefresh = false)
         {
             NodeInfo[] nodes = null;
             nodes = await ExpandNode(session, expandParams.NodePath, forceRefresh);
-            ExpandResponse response = new ExpandResponse() { Nodes = nodes, SessionId = session.Uri, NodePath = expandParams.NodePath };
+            if (cancellationToken.IsCancellationRequested)
+            {
+                Logger.Write(LogLevel.Verbose, "OE expand canceled ");
+            }
+            else
+            {
+                ExpandResponse response = CreateExpandResponse(session, expandParams);
+                response.Nodes = nodes;
                 await serviceHost.SendEvent(ExpandCompleteNotification.Type, response);
             }
+        }
 
-       
+        private ExpandResponse CreateExpandResponse(ObjectExplorerSession session, ExpandParams expandParams)
+        {
+            return new ExpandResponse() { SessionId = session.Uri, NodePath = expandParams.NodePath };
+        }
 
         private async Task<T> HandleRequestAsync<T>(Func<Task<T>> handler, RequestContext<T> requestContext, string requestType)
         {
@@ -491,6 +576,12 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer
             applicableFactories.Add(factory);
         }
 
+        internal class ObjectExplorerTaskResult
+        {
+            public bool IsComplete { get; set; }
+            public Exception Exception { get; set; }
+        }
+
         internal class ObjectExplorerSession
         {
             private ConnectionService connectionService;

src/Microsoft.SqlTools.ServiceLayer/ObjectExplorer/SmoModel/SqlHistoryTableQuerier.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 //
 
+using System;
 using Microsoft.SqlServer.Management.Smo;
 
 namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer.SmoModel
@@ -16,8 +17,19 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer.SmoModel
         {
             Table parentTable = parent as Table;
             Table historyTable = smoObject as Table;
-
+            if (parentTable != null && historyTable != null)
+            {
+                try
+                {
                     return (parentTable.HistoryTableID == historyTable.ID);
                 }
+                catch(Exception)
+                {
+                    //TODO: have a better filtering here. HistoryTable is not available for SQL 2014.
+                    //and the property throws exception here
+                }
+            }
+            return false;
+        }
     }
 }

src/Microsoft.SqlTools.ServiceLayer/Scripting/ScriptingService.cs

@@ -312,7 +312,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Scripting
                             if (operation == ScriptOperation.Select)
                             {                    
                                 return string.Format(
-                                    @"SELECT TOP 100 * " + Environment.NewLine + @"FROM {0}.{1}",
+                                    @"SELECT TOP 1000 * " + Environment.NewLine + @"FROM {0}.{1}",
                                     metadata.Schema, metadata.Name);
                             }
                             else if (operation == ScriptOperation.Create)

src/Microsoft.SqlTools.ServiceLayer/SqlContext/ObjectExplorerSettings.cs

@@ -0,0 +1,29 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+namespace Microsoft.SqlTools.ServiceLayer.SqlContext
+{
+    /// <summary>
+    /// Contract for receiving object explorer settings as part of workspace settings
+    /// </summary>
+    public class ObjectExplorerSettings
+    {
+        public ObjectExplorerSettings()
+        {
+            CreateSessionTimeout = 10;
+            ExpandTimeout = 10;
+        }
+
+        /// <summary>
+        /// Number of seconds to wait before fail create session request with timeout error
+        /// </summary>
+        public int CreateSessionTimeout { get; set; }
+
+        /// <summary>
+        /// Number of seconds to wait before fail expand request with timeout error
+        /// </summary>
+        public int ExpandTimeout { get; set; }
+    }
+}

src/Microsoft.SqlTools.ServiceLayer/SqlContext/SqlToolsSettings.cs

@@ -134,5 +134,11 @@ namespace Microsoft.SqlTools.ServiceLayer.SqlContext
         /// </summary>
         [JsonProperty("format")]
         public FormatterSettings Format { get; set; }
+
+        /// <summary>
+        /// Gets or sets the formatter settings
+        /// </summary>
+        [JsonProperty("objectExplorer")]
+        public ObjectExplorerSettings ObjectExplorer { get; set; }
     }
 }