Multiple Connection Simple Execute (#421)

* change simple execute to open a new connection and close it every query

* updated tests for simple execute

* removed an unnecessary connect

* refactored code to be more readable

* global try catch on simple execute

* added multiple execution test

* update execution to be asynchrous; update tests to account for asynchrounous nature

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

@@ -4,9 +4,12 @@
 //
 using System;
 using System.Collections.Concurrent;
+using System.Data.Common;
+using System.Data.SqlClient;
 using System.IO;
 using System.Threading.Tasks;
 using Microsoft.SqlTools.ServiceLayer.Connection;
+using Microsoft.SqlTools.ServiceLayer.Connection.Contracts;
 using Microsoft.SqlTools.Hosting.Protocol;
 using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts;
 using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts.ExecuteRequests;
@@ -118,6 +121,17 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
         /// </summary>
         internal SqlToolsSettings Settings { get; set; }
 
+        /// <summary>
+        /// Holds a map from the simple execute unique GUID and the underlying task that is being ran
+        /// </summary>
+        private readonly Lazy<ConcurrentDictionary<string, Task>> simpleExecuteRequests = 
+            new Lazy<ConcurrentDictionary<string, Task>>(() => new ConcurrentDictionary<string, Task>());
+
+        /// <summary>
+        /// Holds a map from the simple execute unique GUID and the underlying task that is being ran
+        /// </summary>
+        internal ConcurrentDictionary<string, Task> ActiveSimpleExecuteRequests => simpleExecuteRequests.Value;
+
         #endregion
 
         /// <summary>
@@ -173,82 +187,111 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
         /// <summary>
         /// Handles a request to execute a string and return the result
         /// </summary>
-        internal Task HandleSimpleExecuteRequest(SimpleExecuteParams executeParams,
+        internal async Task HandleSimpleExecuteRequest(SimpleExecuteParams executeParams,
             RequestContext<SimpleExecuteResult> requestContext)
         {
-             ExecuteStringParams executeStringParams = new ExecuteStringParams
+            try
             {
-                Query = executeParams.QueryString,
-                // generate guid as the owner uri to make sure every query is unique
-                OwnerUri = Guid.NewGuid().ToString()
-            };
-
-            // get connection
-            ConnectionInfo connInfo;
-            if (!ConnectionService.TryFindConnection(executeParams.OwnerUri, out connInfo))
-            {
-                return requestContext.SendError(SR.QueryServiceQueryInvalidOwnerUri);
-            }
-
-            if (connInfo.ConnectionDetails.MultipleActiveResultSets == null || connInfo.ConnectionDetails.MultipleActiveResultSets == false) {
-                // if multipleActive result sets is not allowed, don't specific a connection and make the ownerURI the true owneruri
-                connInfo = null;
-                executeStringParams.OwnerUri = executeParams.OwnerUri;
-            }
-
-            Func<string, Task> queryCreateFailureAction = message => requestContext.SendError(message);
-
-            ResultOnlyContext<SimpleExecuteResult> newContext = new ResultOnlyContext<SimpleExecuteResult>(requestContext);
-
-            // handle sending event back when the query completes
-            Query.QueryAsyncEventHandler queryComplete = async q =>
-            {
-                Query removedQuery;
-                // check to make sure any results were recieved
-                if (q.Batches.Length == 0 || q.Batches[0].ResultSets.Count == 0) 
+                string randomUri = Guid.NewGuid().ToString();
+                ExecuteStringParams executeStringParams = new ExecuteStringParams
                 {
-                    await requestContext.SendError(SR.QueryServiceResultSetHasNoResults);
-                    ActiveQueries.TryRemove(executeStringParams.OwnerUri, out removedQuery);
-                    return;
-                } 
+                    Query = executeParams.QueryString,
+                    // generate guid as the owner uri to make sure every query is unique
+                    OwnerUri = randomUri
+                };
 
-                var rowCount = q.Batches[0].ResultSets[0].RowCount;
-                // check to make sure there is a safe amount of rows to load into memory
-                if (rowCount > Int32.MaxValue) 
+                // get connection
+                ConnectionInfo connInfo;
+                if (!ConnectionService.TryFindConnection(executeParams.OwnerUri, out connInfo))
                 {
-                    await requestContext.SendError(SR.QueryServiceResultSetTooLarge);
-                    ActiveQueries.TryRemove(executeStringParams.OwnerUri, out removedQuery);
+                    await requestContext.SendError(SR.QueryServiceQueryInvalidOwnerUri);
                     return;
                 }
                 
-                SubsetParams subsetRequestParams = new SubsetParams
+                ConnectParams connectParams = new ConnectParams
                 {
-                    OwnerUri = executeStringParams.OwnerUri,
-                    BatchIndex = 0,
-                    ResultSetIndex = 0,
-                    RowsStartIndex = 0,
-                    RowsCount = Convert.ToInt32(rowCount)
+                    OwnerUri = randomUri,
+                    Connection = connInfo.ConnectionDetails,
+                    Type = ConnectionType.Default
                 };
-                // get the data to send back
-                ResultSetSubset subset = await InterServiceResultSubset(subsetRequestParams);
-                SimpleExecuteResult result = new SimpleExecuteResult
-                {
-                    RowCount = q.Batches[0].ResultSets[0].RowCount,
-                    ColumnInfo = q.Batches[0].ResultSets[0].Columns,
-                    Rows = subset.Rows
-                };
-                await requestContext.SendResult(result);
-                // remove the active query since we are done with it
-                ActiveQueries.TryRemove(executeStringParams.OwnerUri, out removedQuery);
-            };
+                
+                Task workTask = Task.Run(async () => {
+                    await ConnectionService.Connect(connectParams);
 
-            // handle sending error back when query fails
-            Query.QueryAsyncErrorEventHandler queryFail = async (q, e) =>
+                    ConnectionInfo newConn;
+                    ConnectionService.TryFindConnection(randomUri, out newConn);
+
+                    Func<string, Task> queryCreateFailureAction = message => requestContext.SendError(message);
+
+                    ResultOnlyContext<SimpleExecuteResult> newContext = new ResultOnlyContext<SimpleExecuteResult>(requestContext);
+
+                    // handle sending event back when the query completes
+                    Query.QueryAsyncEventHandler queryComplete = async query =>
+                    {
+                        try
+                        {
+                            // check to make sure any results were recieved
+                            if (query.Batches.Length == 0 || query.Batches[0].ResultSets.Count == 0) 
+                            {
+                                await requestContext.SendError(SR.QueryServiceResultSetHasNoResults);
+                                return;
+                            } 
+
+                            var rowCount = query.Batches[0].ResultSets[0].RowCount;
+                            // check to make sure there is a safe amount of rows to load into memory
+                            if (rowCount > Int32.MaxValue) 
+                            {
+                                await requestContext.SendError(SR.QueryServiceResultSetTooLarge);
+                                return;
+                            }
+                            
+                            SubsetParams subsetRequestParams = new SubsetParams
+                            {
+                                OwnerUri = randomUri,
+                                BatchIndex = 0,
+                                ResultSetIndex = 0,
+                                RowsStartIndex = 0,
+                                RowsCount = Convert.ToInt32(rowCount)
+                            };
+                            // get the data to send back
+                            ResultSetSubset subset = await InterServiceResultSubset(subsetRequestParams);
+                            SimpleExecuteResult result = new SimpleExecuteResult
+                            {
+                                RowCount = query.Batches[0].ResultSets[0].RowCount,
+                                ColumnInfo = query.Batches[0].ResultSets[0].Columns,
+                                Rows = subset.Rows
+                            };
+                            await requestContext.SendResult(result);
+                        } 
+                        finally 
+                        {
+                            Query removedQuery;
+                            Task removedTask;
+                            // remove the active query since we are done with it
+                            ActiveQueries.TryRemove(randomUri, out removedQuery);
+                            ActiveSimpleExecuteRequests.TryRemove(randomUri, out removedTask);
+                            ConnectionService.Disconnect(new DisconnectParams(){
+                                OwnerUri = randomUri,
+                                Type = null
+                            });
+                        }
+                    };
+
+                    // handle sending error back when query fails
+                    Query.QueryAsyncErrorEventHandler queryFail = async (q, e) =>
+                    {
+                        await requestContext.SendError(e);
+                    };
+
+                    await InterServiceExecuteQuery(executeStringParams, newConn, newContext, null, queryCreateFailureAction, queryComplete, queryFail);
+                });
+
+                ActiveSimpleExecuteRequests.TryAdd(randomUri, workTask);
+            }
+            catch(Exception ex) 
             {
-                await requestContext.SendError(e);
-            };
-
-            return InterServiceExecuteQuery(executeStringParams, connInfo, newContext, null, queryCreateFailureAction, queryComplete, queryFail);
+                await requestContext.SendError(ex.ToString());
+            }
         }
 
         /// <summary>