Switch from events to locks during parsing (#87)

* Switch from event to locks in binding.

* Remove unneeded null check.

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

@@ -4,6 +4,7 @@
 //
 
 using System.Collections.Generic;
+using System.Threading;
 using Microsoft.SqlServer.Management.SqlParser.Binder;
 using Microsoft.SqlServer.Management.SqlParser.Intellisense;
 using Microsoft.SqlServer.Management.SqlParser.Parser;
@@ -572,12 +573,10 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
                 var scriptFile = AutoCompleteHelper.WorkspaceServiceInstance.Workspace.GetFile(info.OwnerUri);                                
                 LanguageService.Instance.ParseAndBind(scriptFile, info);
 
-                if (scriptInfo.BuildingMetadataEvent.WaitOne(LanguageService.OnConnectionWaitTimeout))
+                if (Monitor.TryEnter(scriptInfo.BuildingMetadataLock, LanguageService.OnConnectionWaitTimeout))
                 {
                     try
                     {
-                        scriptInfo.BuildingMetadataEvent.Reset();
-
                         QueueItem queueItem = bindingQueue.QueueBindingOperation(
                             key: scriptInfo.ConnectionKey,
                             bindingTimeout: AutoCompleteHelper.PrepopulateBindTimeout,
@@ -631,7 +630,7 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
                     }
                     finally
                     {
-                        scriptInfo.BuildingMetadataEvent.Set();
+                        Monitor.Exit(scriptInfo.BuildingMetadataLock);
                     }
                 }
             }

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

@@ -191,19 +191,22 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
                             continue;
                         }
 
+                        bool lockTaken = false;
                         try
                         {                                                    
                             // prefer the queue item binding item, otherwise use the context default timeout
                             int bindTimeout = queueItem.BindingTimeout ?? bindingContext.BindingTimeout;
 
                             // handle the case a previous binding operation is still running                            
-                            if (!bindingContext.BindingLocked.WaitOne(bindTimeout))
+                            if (!Monitor.TryEnter(bindingContext.BindingLock, bindTimeout))
                             {
                                 queueItem.Result = queueItem.TimeoutOperation(bindingContext);
                                 queueItem.ItemProcessed.Set();
                                 continue;
                             }
 
+                            lockTaken = true;
+
                             // execute the binding operation
                             object result = null;
                             CancellationTokenSource cancelToken = new CancellationTokenSource();
@@ -237,7 +240,11 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
                         }
                         finally
                         {
-                            bindingContext.BindingLocked.Set();
+                            if (lockTaken)
+                            {
+                                Monitor.Exit(bindingContext.BindingLock);
+                            }
+
                             queueItem.ItemProcessed.Set();
                         }
 

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

@@ -4,7 +4,6 @@
 //
 
 using System;
-using System.Threading;
 using Microsoft.SqlServer.Management.Common;
 using Microsoft.SqlServer.Management.SmoMetadataProvider;
 using Microsoft.SqlServer.Management.SqlParser.Binder;
@@ -21,6 +20,8 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
     {
         private ParseOptions parseOptions;
 
+        private object bindingLock;
+
         private ServerConnection serverConnection;
 
         /// <summary>
@@ -28,7 +29,7 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
         /// </summary>
         public ConnectedBindingContext()
         {
-            this.BindingLocked = new ManualResetEvent(initialState: true);            
+            this.bindingLock = new object();            
             this.BindingTimeout = ConnectedBindingQueue.DefaultBindingTimeout;
             this.MetadataDisplayInfoProvider = new MetadataDisplayInfoProvider();
         }
@@ -72,9 +73,15 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
         public IBinder Binder { get; set; }
 
         /// <summary>
-        /// Gets or sets an event to signal if a binding operation is in progress
+        /// Gets the binding lock object
         /// </summary>
-        public ManualResetEvent BindingLocked { get; set; } 
+        public object BindingLock 
+        { 
+            get
+            {
+                return this.bindingLock;
+            }
+        }
 
         /// <summary>
         /// Gets or sets the binding operation timeout in milliseconds

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

@@ -63,22 +63,22 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
             string connectionKey = GetConnectionContextKey(connInfo);
             IBindingContext bindingContext = this.GetOrCreateBindingContext(connectionKey);
 
-            try
+            lock (bindingContext.BindingLock)
             {
-                // increase the connection timeout to at least 30 seconds and and build connection string
+                try
-                // enable PersistSecurityInfo to handle issues in SMO where the connection context is lost in reconnections
-                int? originalTimeout = connInfo.ConnectionDetails.ConnectTimeout;
-                bool? originalPersistSecurityInfo = connInfo.ConnectionDetails.PersistSecurityInfo;
-                connInfo.ConnectionDetails.ConnectTimeout = Math.Max(DefaultMinimumConnectionTimeout, originalTimeout ?? 0);
-                connInfo.ConnectionDetails.PersistSecurityInfo = true;
-                string connectionString = ConnectionService.BuildConnectionString(connInfo.ConnectionDetails);
-                connInfo.ConnectionDetails.ConnectTimeout = originalTimeout;
-                connInfo.ConnectionDetails.PersistSecurityInfo = originalPersistSecurityInfo;
-
-                // open a dedicated binding server connection
-                SqlConnection sqlConn = new SqlConnection(connectionString);
-                if (sqlConn != null)
                 {
+                    // increase the connection timeout to at least 30 seconds and and build connection string
+                    // enable PersistSecurityInfo to handle issues in SMO where the connection context is lost in reconnections
+                    int? originalTimeout = connInfo.ConnectionDetails.ConnectTimeout;
+                    bool? originalPersistSecurityInfo = connInfo.ConnectionDetails.PersistSecurityInfo;
+                    connInfo.ConnectionDetails.ConnectTimeout = Math.Max(DefaultMinimumConnectionTimeout, originalTimeout ?? 0);
+                    connInfo.ConnectionDetails.PersistSecurityInfo = true;
+                    string connectionString = ConnectionService.BuildConnectionString(connInfo.ConnectionDetails);
+                    connInfo.ConnectionDetails.ConnectTimeout = originalTimeout;
+                    connInfo.ConnectionDetails.PersistSecurityInfo = originalPersistSecurityInfo;
+
+                    // open a dedicated binding server connection
+                    SqlConnection sqlConn = new SqlConnection(connectionString);                    
                     sqlConn.Open();
 
                     // populate the binding context to work with the SMO metadata provider
@@ -91,16 +91,12 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
                     bindingContext.Binder = BinderProvider.CreateBinder(bindingContext.SmoMetadataProvider);                           
                     bindingContext.ServerConnection = serverConn;
                     bindingContext.BindingTimeout = ConnectedBindingQueue.DefaultBindingTimeout;
-                    bindingContext.IsConnected = true;
+                    bindingContext.IsConnected = true;                    
                 }
-            }
+                catch (Exception)
-            catch (Exception)
+                {
-            {
+                    bindingContext.IsConnected = false;
-                bindingContext.IsConnected = false;
+                }                
-            }
-            finally
-            {
-                bindingContext.BindingLocked.Set();                
             }
 
             return connectionKey;

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

@@ -44,9 +44,9 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
         IBinder Binder { get; set; }
 
         /// <summary>
-        /// Gets or sets an event to signal if a binding operation is in progress
+        /// Gets the binding lock object
         /// </summary>
-        ManualResetEvent BindingLocked { get; set; }
+        object BindingLock { get; }
 
         /// <summary>
         /// Gets or sets the binding operation timeout in milliseconds

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

@@ -452,12 +452,10 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
             // get or create the current parse info object
             ScriptParseInfo parseInfo = GetScriptParseInfo(scriptFile.ClientFilePath, createIfNotExists: true);
 
-            if (parseInfo.BuildingMetadataEvent.WaitOne(LanguageService.BindingTimeout))
+            if (Monitor.TryEnter(parseInfo.BuildingMetadataLock, LanguageService.BindingTimeout))
             {
                 try
                 {
-                    parseInfo.BuildingMetadataEvent.Reset();
-
                     if (connInfo == null || !parseInfo.IsConnected)
                     {
                         // parse current SQL file contents to retrieve a list of errors
@@ -518,7 +516,7 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
                 }
                 finally
                 {
-                    parseInfo.BuildingMetadataEvent.Set();
+                    Monitor.Exit(parseInfo.BuildingMetadataLock);
                 }
             }
             else
@@ -538,11 +536,10 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
             await Task.Run(() => 
             {
                 ScriptParseInfo scriptInfo = GetScriptParseInfo(info.OwnerUri, createIfNotExists: true);
-                if (scriptInfo.BuildingMetadataEvent.WaitOne(LanguageService.OnConnectionWaitTimeout))
+                if (Monitor.TryEnter(scriptInfo.BuildingMetadataLock, LanguageService.OnConnectionWaitTimeout))
                 {
                     try
-                    {
+                    {                                                                      
-                        scriptInfo.BuildingMetadataEvent.Reset();                                                                       
                         scriptInfo.ConnectionKey = this.BindingQueue.AddConnectionContext(info);
                         scriptInfo.IsConnected = true;
                         
@@ -556,7 +553,7 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
                     {
                         // Set Metadata Build event to Signal state.
                         // (Tell Language Service that I am ready with Metadata Provider Object)
-                        scriptInfo.BuildingMetadataEvent.Set();
+                        Monitor.Exit(scriptInfo.BuildingMetadataLock);
                     }
                 }  
 
@@ -631,9 +628,8 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
             ScriptParseInfo scriptParseInfo = GetScriptParseInfo(textDocumentPosition.TextDocument.Uri);
             if (scriptParseInfo != null && scriptParseInfo.ParseResult != null)
             {
-                if (scriptParseInfo.BuildingMetadataEvent.WaitOne(LanguageService.FindCompletionStartTimeout))
+                if (Monitor.TryEnter(scriptParseInfo.BuildingMetadataLock, LanguageService.FindCompletionStartTimeout))
                 {
-                    scriptParseInfo.BuildingMetadataEvent.Reset();
                     try
                     {
                         QueueItem queueItem = this.BindingQueue.QueueBindingOperation(
@@ -661,8 +657,8 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
                     }
                     finally
                     {
-                        scriptParseInfo.BuildingMetadataEvent.Set();
+                        Monitor.Exit(scriptParseInfo.BuildingMetadataLock);
-                    }                
+                    }               
                 }
             }
 
@@ -691,8 +687,7 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
 
             this.currentCompletionParseInfo = null;
 
-            // Take a reference to the list at a point in time in case we update and replace the list
+            // get the current script parse info object
-
             ScriptParseInfo scriptParseInfo = GetScriptParseInfo(textDocumentPosition.TextDocument.Uri);
             if (connInfo == null || scriptParseInfo == null)
             {
@@ -711,18 +706,18 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
             }
 
             if (scriptParseInfo.IsConnected 
-                && scriptParseInfo.BuildingMetadataEvent.WaitOne(LanguageService.FindCompletionStartTimeout))
+                && Monitor.TryEnter(scriptParseInfo.BuildingMetadataLock, LanguageService.FindCompletionStartTimeout))
-            {
+            {        
-                scriptParseInfo.BuildingMetadataEvent.Reset();                
+                try
-                
+                {    
-                QueueItem queueItem = this.BindingQueue.QueueBindingOperation(
+                    // queue the completion task with the binding queue    
-                    key: scriptParseInfo.ConnectionKey,
+                    QueueItem queueItem = this.BindingQueue.QueueBindingOperation(
-                    bindingTimeout: LanguageService.BindingTimeout,
+                        key: scriptParseInfo.ConnectionKey,
-                    bindOperation: (bindingContext, cancelToken) =>
+                        bindingTimeout: LanguageService.BindingTimeout,
-                    {
+                        bindOperation: (bindingContext, cancelToken) =>
-                        CompletionItem[] completions = null;
-                        try
                         {
+                            CompletionItem[] completions = null;
+            
                             // get the completion list from SQL Parser
                             scriptParseInfo.CurrentSuggestions = Resolver.FindCompletions(
                                 scriptParseInfo.ParseResult, 
@@ -738,26 +733,27 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
                                 scriptParseInfo.CurrentSuggestions, 
                                 startLine, 
                                 startColumn, 
-                                endColumn);
+                                endColumn);                        
-                        }
-                        finally
-                        {
-                            scriptParseInfo.BuildingMetadataEvent.Set();
-                        }
 
-                        return completions;
+                            return completions;
-                    },
+                        },
-                    timeoutOperation: (bindingContext) =>
+                        timeoutOperation: (bindingContext) =>
+                        {
+                            return AutoCompleteHelper.GetDefaultCompletionItems(startLine, startColumn, endColumn, useLowerCaseSuggestions);
+                        });
+
+                    queueItem.ItemProcessed.WaitOne();
+
+                    var completionItems = queueItem.GetResultAsT<CompletionItem[]>(); 
+                    if (completionItems != null && completionItems.Length > 0)
                     {
-                        return AutoCompleteHelper.GetDefaultCompletionItems(startLine, startColumn, endColumn, useLowerCaseSuggestions);
+                        return completionItems;
-                    });            
+                    }          
-                
-                queueItem.ItemProcessed.WaitOne();   
-                var completionItems = queueItem.GetResultAsT<CompletionItem[]>(); 
-                if (completionItems != null && completionItems.Length > 0)
-                {
-                    return completionItems;
                 }
+                finally
+                {                    
+                    Monitor.Exit(scriptParseInfo.BuildingMetadataLock);
+                }                
             }
             
             return AutoCompleteHelper.GetDefaultCompletionItems(startLine, startColumn, endColumn, useLowerCaseSuggestions);

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

@@ -5,7 +5,6 @@
 
 using System;
 using System.Threading;
-using System.Threading.Tasks;
 
 namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
 {

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

@@ -4,7 +4,6 @@
 //
 
 using System.Collections.Generic;
-using System.Threading;
 using Microsoft.SqlServer.Management.SqlParser.Intellisense;
 using Microsoft.SqlServer.Management.SqlParser.Parser;
 
@@ -15,14 +14,14 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
     /// </summary>
     internal class ScriptParseInfo
     {
-        private ManualResetEvent buildingMetadataEvent = new ManualResetEvent(initialState: true);
+        private object buildingMetadataLock = new object();
 
         /// <summary>
         /// Event which tells if MetadataProvider is built fully or not
         /// </summary>
-        public ManualResetEvent BuildingMetadataEvent 
+        public object BuildingMetadataLock
         { 
-            get { return this.buildingMetadataEvent; }
+            get { return this.buildingMetadataLock; }
         }
 
         /// <summary>

test/Microsoft.SqlTools.ServiceLayer.Test/LanguageServer/BindingQueueTests.cs

@@ -4,7 +4,6 @@
 //
 
 using System.Threading;
-using System.Threading.Tasks;
 using Microsoft.SqlServer.Management.Common;
 using Microsoft.SqlServer.Management.SmoMetadataProvider;
 using Microsoft.SqlServer.Management.SqlParser.Binder;
@@ -25,7 +24,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Test.LanguageServices
     {
         public TestBindingContext()
         {
-            this.BindingLocked = new ManualResetEvent(initialState: true);
+            this.BindingLock = new object();
             this.BindingTimeout = 3000;
         }
 
@@ -39,7 +38,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Test.LanguageServices
 
         public IBinder Binder { get; set; }
 
-        public ManualResetEvent BindingLocked { get; set; } 
+        public object BindingLock { get; set; } 
 
         public int BindingTimeout { get; set; }