Add schema compare publish changes operation (#795)

* add schema compare publish changes operation

src/Microsoft.SqlTools.ServiceLayer/SchemaCompare/SchemaComparePublishChangesOperation.cs

@@ -0,0 +1,73 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+using Microsoft.SqlServer.Dac.Compare;
+using Microsoft.SqlTools.ServiceLayer.SchemaCompare.Contracts;
+using Microsoft.SqlTools.ServiceLayer.TaskServices;
+using Microsoft.SqlTools.Utility;
+using System;
+using System.Diagnostics;
+using System.IO;
+using System.Threading;
+
+namespace Microsoft.SqlTools.ServiceLayer.SchemaCompare
+{
+    /// <summary>
+    /// Class to represent an in-progress schema compare publish changes operation
+    /// </summary>
+    class SchemaComparePublishChangesOperation : ITaskOperation
+    {
+        private CancellationTokenSource cancellation = new CancellationTokenSource();
+        private bool disposed = false;
+
+        /// <summary>
+        /// Gets the unique id associated with this instance.
+        /// </summary>
+        public string OperationId { get; private set; }
+
+        public SchemaComparePublishChangesParams Parameters { get; }
+
+        protected CancellationToken CancellationToken { get { return this.cancellation.Token; } }
+
+        public string ErrorMessage { get; set; }
+
+        public SqlTask SqlTask { get; set; }
+
+        public SchemaComparisonResult ComparisonResult { get; set; }
+
+        public SchemaComparePublishResult PublishResult { get; set; }
+
+        public SchemaComparePublishChangesOperation(SchemaComparePublishChangesParams parameters, SchemaComparisonResult comparisonResult)
+        {
+            Validate.IsNotNull("parameters", parameters);
+            this.Parameters = parameters;
+            Validate.IsNotNull("comparisonResult", comparisonResult);
+            this.ComparisonResult = comparisonResult;
+        }
+
+        public void Execute(TaskExecutionMode mode)
+        {
+            if (this.CancellationToken.IsCancellationRequested)
+            {
+                throw new OperationCanceledException(this.CancellationToken);
+            }
+
+            try
+            {
+                this.PublishResult = this.ComparisonResult.PublishChangesToTarget();
+            }
+            catch (Exception e)
+            {
+                ErrorMessage = e.Message;
+                Logger.Write(TraceEventType.Error, string.Format("Schema compare publish changes operation {0} failed with exception {1}", this.OperationId, e.Message));
+                throw;
+            }
+        }
+
+        // The schema compare public api doesn't currently take a cancellation token so the operation can't be cancelled
+        public void Cancel()
+        {
+        }
+    }
+}