Progressive Results Part 2: Result Completion Event (#134)

The main change in this pull request is to add a new event that will be fired upon completion of a resultset but before the completion of a batch. This event will only fire if a resultset is available and generated.

Changes:
* ConnectionService - Slight changes to enable mocking, cleanup 
* Batch - Moving summary generation into ResultSet class, adding generation of ordinals for resultset and locking of result set list (which needs further refinement, but would be outside scope of this change)
* Adding new event and associated parameters for completion of a resultset. Params return the resultset summary
* Adding logic for assigning the event a handler in the query execution service
* Adding unit tests for testing the new event /making sure the existing tests work
* Refactoring some private properties into member variables

* Refactor to remove SectionData class in favor of BufferRange

* Adding callback for batch completion that will let the extension know that a batch has completed execution

* Refactoring to make progressive results work as per async query execution

* Allowing retrieval of batch results while query is in progress

* reverting global.json, whoops

* Adding a few missing comments, and fixing a couple code style bugs

* Using SelectionData everywhere again

* One more missing comment

* Adding new notification type for result set completion

* Plumbing event for result set completion

* Unit tests for result set events

This includes a fairly substantial change to create a mock of the
ConnectionService and to create separate memorystream storage arrays. It
preserves more correct behavior with a integration test, fixes an issue
where the test db reader will return n-1 rows because the Reliable
Connection Helper steals a record.

* Adding locking to ResultSets for thread safety

* Adding/fixing unit tests

* Adding batch ID to result set summary

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

@@ -92,25 +92,13 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
             Batches = batchSelection.ToArray();
         }
 
-        #region Properties
-
-        /// <summary>
-        /// Delegate type for callback when a query completes or fails
-        /// </summary>
-        /// <param name="q">The query that completed</param>
-        public delegate Task QueryAsyncEventHandler(Query q);
+        #region Events
 
         /// <summary>
         /// Event to be called when a batch is completed.
         /// </summary>
         public event Batch.BatchAsyncEventHandler BatchCompleted;
 
-        /// <summary>
-        /// Delegate type for callback when a query connection fails
-        /// </summary>
-        /// <param name="message">Message to return</param>
-        public delegate Task QueryAsyncErrorEventHandler(string message);
-
         /// <summary>
         /// Callback for when the query has completed successfully
         /// </summary>
@@ -126,6 +114,27 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
         /// </summary>
         public event QueryAsyncErrorEventHandler QueryConnectionException;
 
+        /// <summary>
+        /// Event to be called when a resultset has completed.
+        /// </summary>
+        public event ResultSet.ResultSetAsyncEventHandler ResultSetCompleted;
+
+        #endregion
+
+        #region Properties
+
+        /// <summary>
+        /// Delegate type for callback when a query completes or fails
+        /// </summary>
+        /// <param name="q">The query that completed</param>
+        public delegate Task QueryAsyncEventHandler(Query q);
+
+        /// <summary>
+        /// Delegate type for callback when a query connection fails
+        /// </summary>
+        /// <param name="message">Message to return</param>
+        public delegate Task QueryAsyncErrorEventHandler(string message);
+
         /// <summary>
         /// The batches underneath this query
         /// </summary>
@@ -146,6 +155,10 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
             }
         }
 
+        /// <summary>
+        /// Storage for the async task for execution. Set as internal in order to await completion
+        /// in unit tests.
+        /// </summary>
         internal Task ExecutionTask { get; private set; }
 
         /// <summary>
@@ -242,11 +255,11 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
                 {
                     await conn.OpenAsync();
                 }
-                catch(Exception exception)
+                catch (Exception exception)
                 {
-                    this.HasExecuted = true;                 
+                    this.HasExecuted = true;
                     if (QueryConnectionException != null)
-                    {                        
+                    {
                         await QueryConnectionException(exception.Message);
                     }
                     return;
@@ -265,6 +278,7 @@ namespace Microsoft.SqlTools.ServiceLayer.QueryExecution
                     foreach (Batch b in Batches)
                     {
                         b.BatchCompletion += BatchCompleted;
+                        b.ResultSetCompletion += ResultSetCompleted;
                         await b.Execute(conn, cancellationSource.Token);
                     }