RavenDB-21028 : Operation.WaitForCompletion : don't await the additio…

…nal task if we had an error during processing, since it can cause us to hang

src/Raven.Client/Documents/Operations/Operation.cs

@@ -37,7 +37,7 @@ public class Operation : IObserver<OperationStatusChange>
         private readonly RequestExecutor _requestExecutor;
         private readonly Func<IDatabaseChanges> _changes;
         private readonly DocumentConventions _conventions;
-        private readonly Task _additionalTask;
+        private Task _additionalTask;
         private readonly long _id;
         private TaskCompletionSource<IOperationResult> _result = new TaskCompletionSource<IOperationResult>(TaskCreationOptions.RunContinuationsAsynchronously);
         private readonly SemaphoreSlim _lock = new SemaphoreSlim(1, 1);
@@ -355,6 +355,7 @@ public async Task<TResult> WaitForCompletionAsync<TResult>(CancellationToken tok
                 catch (Exception e)
                 {
                     await StopProcessingUnderLock(e).ConfigureAwait(false);
+                    _additionalTask = Task.CompletedTask; // don't await the additional task if we had an error
                 }
 
                 await _additionalTask.ConfigureAwait(false);

test/SlowTests/Issues/RavenDB-21028.cs

@@ -0,0 +1,33 @@
+using System.Threading.Tasks;
+using Xunit.Abstractions;
+using System;
+using FastTests;
+using Raven.Client.Documents.Smuggler;
+using Raven.Client.Exceptions;
+using Tests.Infrastructure;
+using Xunit;
+
+namespace SlowTests.Issues
+{
+    public class RavenDB_21028 : RavenTestBase
+    {
+
+        public RavenDB_21028(ITestOutputHelper output) : base(output)
+        {
+        }
+
+        [RavenFact(RavenTestCategory.Smuggler)]
+        public async Task WaitForCompletionShouldNotHangOnFailureDuringExport()
+        {
+            using var store = GetDocumentStore();
+            await store.Maintenance.SendAsync(new CreateSampleDataOperation());
+
+            var file = GetTempFileName();
+            var op = await store.Smuggler.ExportAsync(new DatabaseSmugglerExportOptions { EncryptionKey = "fakeKey" }, file);
+
+            await Assert.ThrowsAsync<RavenException>(async () => await op.WaitForCompletionAsync(TimeSpan.FromSeconds(10)));
+
+        }
+
+    }
+}