add support pending operation marker

Kudu.Console/Program.cs

@@ -5,6 +5,7 @@
 using System.IO;
 using System.Net;
 using System.Net.Http;
+using System.Threading.Tasks;
 using Kudu.Console.Services;
 using Kudu.Contracts.Infrastructure;
 using Kudu.Contracts.Settings;
@@ -163,8 +164,16 @@ private static int Main(string[] args)
             {
                 try
                 {
-                    deploymentManager.DeployAsync(gitRepository, changeSet: null, deployer: deployer, clean: false)
-                        .Wait();
+                    // although the api is called DeployAsync, most expensive works are done synchronously.
+                    // need to launch separate task to go async explicitly (consistent with FetchDeploymentManager)
+                    var deploymentTask = Task.Run(async () => await deploymentManager.DeployAsync(gitRepository, changeSet: null, deployer: deployer, clean: false));
+
+#pragma warning disable 4014
+                    // Track pending task
+                    PostDeploymentHelper.TrackPendingOperation(deploymentTask, TimeSpan.Zero);
+#pragma warning restore 4014
+
+                    deploymentTask.Wait();
 
                     if (PostDeploymentHelper.IsAutoSwapEnabled())
                     {

Kudu.Core/Deployment/FetchDeploymentManager.cs

@@ -369,6 +369,11 @@ private bool ShouldDeploy(IRepository repository, DeploymentInfoBase deploymentI
                 }
             });
 
+#pragma warning disable 4014
+            // Track pending task
+            PostDeploymentHelper.TrackPendingOperation(deploymentTask, TimeSpan.Zero);
+#pragma warning restore 4014
+
             // When the frontend/ARM calls /deploy with isAsync=true, it starts polling
             // the deployment status immediately, so it's important that the temp deployment
             // is created before we return.

Kudu.Core/Helpers/PostDeploymentHelper.cs

@@ -12,7 +12,7 @@
 using System.Threading.Tasks;
 using System.Web.Script.Serialization;
 using Kudu.Contracts.Settings;
-using Microsoft.Win32.SafeHandles;
+using Kudu.Core.Infrastructure;
 
 namespace Kudu.Core.Helpers
 {
@@ -394,6 +394,51 @@ public static void RunPostDeploymentScripts(TraceListener tracer)
             }
         }
 
+        /// <summary>
+        /// As long as the task was not completed, we will keep updating the marker file.
+        /// The routine completes when either task completes or timeout.
+        /// If task is completed, we will remove the marker.
+        /// If timeout, we will leave the stale marker.
+        /// </summary>
+        public static async Task TrackPendingOperation(Task task, TimeSpan timeout)
+        {
+            const int DefaultTimeoutMinutes = 30;
+            const int DefaultUpdateMarkerIntervalMS = 10000;
+            const string MarkerFilePath = @"%TEMP%\SCMPendingOperation.txt";
+
+            // only applicable to azure env
+            if (!Environment.IsAzureEnvironment())
+            {
+                return;
+            }
+
+            if (timeout <= TimeSpan.Zero || timeout >= TimeSpan.FromMinutes(DefaultTimeoutMinutes))
+            {
+                // track at most N mins by default
+                timeout = TimeSpan.FromMinutes(DefaultTimeoutMinutes);
+            }
+
+            var start = DateTime.UtcNow;
+            var markerFile = System.Environment.ExpandEnvironmentVariables(MarkerFilePath);
+            while (start.Add(timeout) >= DateTime.UtcNow)
+            {
+                // create or update marker timestamp
+                OperationManager.SafeExecute(() => File.WriteAllText(markerFile, start.ToString("o")));
+
+                var cancelation = new CancellationTokenSource();
+                var delay = Task.Delay(DefaultUpdateMarkerIntervalMS, cancelation.Token);
+                var completed = await Task.WhenAny(delay, task);
+                if (completed != delay)
+                {
+                    cancelation.Cancel();
+                    break;
+                }
+            }
+
+            // remove marker
+            OperationManager.SafeExecute(() => File.Delete(markerFile));
+        }
+
         private static void ExecuteScript(string file)
         {
             var fi = new FileInfo(file);

Kudu.Core/SiteExtensions/SiteExtensionManager.cs

@@ -18,6 +18,7 @@
 using Kudu.Contracts.SiteExtensions;
 using Kudu.Contracts.Tracing;
 using Kudu.Core.Deployment.Generator;
+using Kudu.Core.Helpers;
 using Kudu.Core.Infrastructure;
 using Kudu.Core.Settings;
 using Kudu.Core.Tracing;
@@ -210,8 +211,19 @@ public async Task<SiteExtensionInfo> GetLocalExtension(string id, bool checkLate
             return info;
         }
 
-        // <inheritdoc />
-        public async Task<SiteExtensionInfo> InstallExtension(string id, string version, string feedUrl, SiteExtensionInfo.SiteExtensionType type, ITracer tracer, string installationArgs = null)
+        public Task<SiteExtensionInfo> InstallExtension(string id, string version, string feedUrl, SiteExtensionInfo.SiteExtensionType type, ITracer tracer, string installationArgs = null)
+        {
+            var installationTask = InstallExtensionCore(id, version, feedUrl, type, tracer, installationArgs);
+
+#pragma warning disable 4014
+            // Track pending task
+            PostDeploymentHelper.TrackPendingOperation(installationTask, TimeSpan.Zero);
+#pragma warning restore 4014
+
+            return installationTask;
+        }
+
+        private async Task<SiteExtensionInfo> InstallExtensionCore(string id, string version, string feedUrl, SiteExtensionInfo.SiteExtensionType type, ITracer tracer, string installationArgs)
         {
             try
             {